WorldWideScience

Sample records for cermets

  1. Cermet fuel reactors

    Energy Technology Data Exchange (ETDEWEB)

    Cowan, C.L.; Palmer, R.S.; Van Hoomissen, J.E.; Bhattacharyya, S.K.; Barner, J.O.

    1987-09-01

    Cermet fueled nuclear reactors are attractive candidates for high performance space power systems. The cermet fuel consists of tungsten-urania hexagonal fuel blocks characterized by high strength at elevated temperatures, a high thermal conductivity and resultant high thermal shock resistance. Key features of the cermet fueled reactor design are (1) the ability to achieve very high coolant exit temperatures, and (2) thermal shock resistance during rapid power changes, and (3) two barriers to fission product release - the cermet matrix and the fuel element cladding. Additionally, thre is a potential for achieving a long operating life because of (1) the neutronic insensitivity of the fast-spectrum core to the buildup of fission products and (2) the utilization of a high strength refractory metal matrix and structural materials. These materials also provide resistance against compression forces that potentially might compact and/or reconfigure the core. In addition, the neutronic properties of the refractory materials assure that the reactor remains substantially subcritical under conditions of water immersion. It is concluded that cermet fueled reactors can be utilized to meet the power requirements for a broad range of advanced space applications. 4 refs., 4 figs., 3 tabs.

  2. Cermet fuel reactors

    International Nuclear Information System (INIS)

    Cermet fueled nuclear reactors are attractive candidates for high performance space power systems. The cermet fuel consists of tungsten-urania hexagonal fuel blocks characterized by high strength at elevated temperatures, a high thermal conductivity and resultant high thermal shock resistance. Key features of the cermet fueled reactor design are (1) the ability to achieve very high coolant exit temperatures, and (2) thermal shock resistance during rapid power changes, and (3) two barriers to fission product release - the cermet matrix and the fuel element cladding. Additionally, thre is a potential for achieving a long operating life because of (1) the neutronic insensitivity of the fast-spectrum core to the buildup of fission products and (2) the utilization of a high strength refractory metal matrix and structural materials. These materials also provide resistance against compression forces that potentially might compact and/or reconfigure the core. In addition, the neutronic properties of the refractory materials assure that the reactor remains substantially subcritical under conditions of water immersion. It is concluded that cermet fueled reactors can be utilized to meet the power requirements for a broad range of advanced space applications. 4 refs., 4 figs., 3 tabs

  3. Manufacture of annular cermet articles

    Science.gov (United States)

    Forsberg, Charles W.; Sikka, Vinod K.

    2004-11-02

    A method to produce annular-shaped, metal-clad cermet components directly produces the form and avoids multiple fabrication steps such as rolling and welding. The method includes the steps of: providing an annular hollow form with inner and outer side walls; filling the form with a particulate mixture of ceramic and metal; closing, evacuating, and hermetically sealing the form; heating the form to an appropriate temperature; and applying force to consolidate the particulate mixture into solid cermet.

  4. Solid solution cermet: (Ti,Nb)(CN)-Ni cermet.

    Science.gov (United States)

    Kwon, Hanjung; Jung, Sun-A

    2014-11-01

    Solid solution powders without W, (Ti,Nb)(CN) powders with a B1 structure (NaCl like), were synthesized by high energy milling and carbothermal reduction in nitrogen. The range of molar ratios of Ti/Nb for forming complete (Ti,Nb)(CN) phase was broader than that of Ti/W for the (Ti,W)(CN) phase because carbide or carbonitride of Nb had a B1 crystal structure identical to Ti(CN) while WC had a hexagonal crystal structure. The results revealed that the hardness of (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,W)(CN)-Ni cermets. The lower density of the (Ti,Nb)(CN) powder contributed to the higher hardness compared to (Ti,W)(CN) because the volumetric ratio of (Ti,Nb)(CN) in the (Ti,Nb)(CN)-Ni cermets was higher than that of (Ti,Nb)(CN) in the (Ti,W)(CN)-Ni cermets at the same weight ratio of Ni. Additionally, it was assumed that intrinsic the properties of (Ti,Nb)(CN) could also be the cause for the high hardness of the (Ti,Nb)(CN)-Ni cermets. PMID:25958611

  5. Uranium-Based Cermet Alloys

    International Nuclear Information System (INIS)

    The paper describes certain features of dispersion-hardened uranium-based cermets. As possible hardening materials, consideration was given to UO2, UC, Al2O3, MgO and UBe13. Data were obtained on the behaviour of uranium alloys containing the above-mentioned admixtures during creep tests, short-term strength tests and cyclic thermal treatment. The corrosion resistance o f UBe13-based uranium alloys was also studied. )author)

  6. Surface properties of copper based cermet materials

    Energy Technology Data Exchange (ETDEWEB)

    Voinea, M. [The Centre: Product Design for Sustainable Development, Transilvania University of Brasov, Eroilor 29, 500036 (Romania)], E-mail: m.voinea@unitbv.ro; Vladuta, C.; Bogatu, C.; Duta, A. [The Centre: Product Design for Sustainable Development, Transilvania University of Brasov, Eroilor 29, 500036 (Romania)

    2008-08-25

    The paper presents the characterization of the surface properties of copper based cermets obtained by two different techniques: spray pyrolysis deposition (SPD) and electrodeposition. Copper acetate was used as precursor of Cu/CuO{sub x} cermet. The surface morphology was tailored by adding copolymers of maleic anhydride with controlled hydrophobia. The films morphology of Cu/CuO{sub x} was assessed using contact angle measurements and AFM analysis. The porous structures obtained via SPD lead to higher liquid adsorption rate than the electrodeposited films. A highly polar liquid - water is recommended as testing liquid in contact angle measurements, for estimating the porosity of copper based cermets, while glycerol can be used to distinguish among ionic and metal predominant structures. Thus, contact angle measurements can be used for a primary evaluation of the films morphology and, on the other hand, of the ratio between the cermet components.

  7. Cermet-fueled reactors for advanced space applications

    International Nuclear Information System (INIS)

    Cermet-fueled nuclear reactors are attractive candidates for high-performance advanced space power systems. The cermet consists of a hexagonal matrix of a refractory metal and a ceramic fuel, with multiple tubular flow channels. The high performance characteristics of the fuel matrix come from its high strength at elevated temperatures and its high thermal conductivity. The cermet fuel concept evolved in the 1960s with the objective of developing a reactor design that could be used for a wide range of mobile power generating sytems, including both Brayton and Rankine power conversion cycles. High temperature thermal cycling tests for the cermet fuel were carried out by General Electric as part of the 710 Project (General Electric 1966), and by Argonne National Laboratory in the Direct Nuclear Rocket Program (1965). Development programs for cermet fuel are currently under way at Argonne National Laboratory and Pacific Northwest Laboratory. The high temperature qualification tests from the 1960s have provided a base for the incorporation of cermet fuel in advanced space applications. The status of the cermet fuel development activities and descriptions of the key features of the cermet-fueled reactor design are summarized in this paper

  8. Fe-Cr-C Cermet Made by Reaction Sintering

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Fe-Cr-C cermet was prepared by reaction sintering of ferrochromium and graphite. The exothermic reaction was determined by DTA. The effect of carbon content on the porosity, hardness and oxidation resistance was investigated. The result showed that the cermet with 6 %-7 % of carbon has high hardness and oxidation resistance.

  9. Investigation of Impact Resistance of Protective Barriers Made from Cermets

    Science.gov (United States)

    Ischenko, A. N.; Tabachenko, A. N.; Afanasieva, S. A.; Belov, N. N.; Burkin, V. V.; Martsunova, L. S.; Rogaev, K. S.; Yugov, N. T.

    2016-01-01

    Ceramic-metal materials (cermets) based on titanium diboride and boron carbide are designed and produced by the method of self-propagating high-temperature synthesis, with the pressure applied to the combustion products. The data, obtained by an experimental-theoretical investigation of impact resistance of protective barriers containing the above-mentioned materials in collisions with a spherical steel projectile, are presented. A better impact resistance of TiB2 + B4C cermets compared to that of Al2O3- ceramics is demonstrated. A possibility of prediction calculations of impact resistance of the specimens containing cermets in the range of collision rates under study is shown.

  10. Final report on cermet high-level waste forms

    International Nuclear Information System (INIS)

    Cermets are being developed as an alternate method for the fixation of defense and commercial high level radioactive waste in a terminal disposal form. Following initial feasibility assessments of this waste form, consisting of ceramic particles dispersed in an iron-nickel base alloy, significantly improved processing methods were developed. The characterization of cermets has continued through property determinations on samples prepared by various methods from a variety of simulated and actual high-level wastes. This report describes the status of development of the cermet waste form as it has evolved since 1977. 6 tables, 18 figures

  11. Molybdenum-base cermet fuel development

    Science.gov (United States)

    Pilger, James P.; Gurwell, William E.; Moss, Ronald W.; White, George D.; Seifert, David A.

    Development of a multimegawatt (MMW) space nuclear power system requires identification and resolution of several technical feasibility issues before selecting one or more promising system concepts. Demonstration of reactor fuel fabrication technology is required for cermet-fueled reactor concepts. The MMW reactor fuel development activity at Pacific Northwest Laboratory (PNL) is focused on producing a molybdenum-matrix uranium-nitride (UN) fueled cermte. This cermet is to have a high matrix density (greater than or equal to 95 percent) for high strength and high thermal conductance coupled with a high particle (UN) porosity (approximately 25 percent) for retention of released fission gas at high burnup. Fabrication process development involves the use of porous TiN microspheres as surrogate fuel material until porous Un microspheres become available. Process development was conducted in the areas of microsphere synthesis, particle sealing/coating, and high-energy-rate forming (HERF) and the vacuum hot press consolidation techniques. This paper summarizes the status of these activities.

  12. Materials characterization of cermet anodes tested in a pilot cell

    Energy Technology Data Exchange (ETDEWEB)

    Windisch, C.F. Jr.; Strachan, D.M.; Henager, C.H. Jr. (Pacific Northwest Lab., Richland, WA (United States)); Alcorn, T.R.; Tabereaux, A.T.; Richards, N.E. (Reynolds Metals Co., Muscle Shoals, AL (United States). Mfg. Technology Lab.)

    1993-02-01

    Cermet anodes were evaluated as nonconsumable substitutes for carbon anodes using a pilot-scale reduction cell at the Reynolds Manufacturing Technology Laboratory. After pilot cell testing, tile anodes were subjected to extensive materials characterization and physical properties measurements at the Pacific Northwest Laboratory. Significant changes in the composition of the cermet anodes were observed including the growth of a reaction layer and penetration of electrolyte deep into the cermet matrix. Fracture strength and toughness were measured as a function of temperature and the ductile-brittle transition wasreduced by 500C following pilot cell testing. These results imply difficulties with anode material and control of operating conditions in the pilot cell, and suggest that additional development work be performed before the cermet anodes are used in commercial reduction cells. The results also highlight specific fabrication and operational considerations that should be addressed in future testing.

  13. A cermet fuel reactor for nuclear thermal propulsion

    Science.gov (United States)

    Kruger, Gordon

    1991-01-01

    Work on the cermet fuel reactor done in the 1960's by General Electric (GE) and the Argonne National Laboratory (ANL) that had as its goal the development of systems that could be used for nuclear rocket propulsion as well as closed cycle propulsion system designs for ship propulsion, space nuclear propulsion, and other propulsion systems is reviewed. It is concluded that the work done in the 1960's has demonstrated that we can have excellent thermal and mechanical performance with cermet fuel. Thousands of hours of testing were performed on the cermet fuel at both GE and AGL, including very rapid transients and some radiation performance history. We conclude that there are no feasibility issues with cermet fuel. What is needed is reactivation of existing technology and qualification testing of a specific fuel form. We believe this can be done with a minimum development risk.

  14. Fabrication of High Temperature Cermet Materials for Nuclear Thermal Propulsion

    Science.gov (United States)

    Hickman, Robert; Panda, Binayak; Shah, Sandeep

    2005-01-01

    Processing techniques are being developed to fabricate refractory metal and ceramic cermet materials for Nuclear Thermal Propulsion (NTP). Significant advances have been made in the area of high-temperature cermet fuel processing since RoverNERVA. Cermet materials offer several advantages such as retention of fission products and fuels, thermal shock resistance, hydrogen compatibility, high conductivity, and high strength. Recent NASA h d e d research has demonstrated the net shape fabrication of W-Re-HfC and other refractory metal and ceramic components that are similar to UN/W-Re cermet fuels. This effort is focused on basic research and characterization to identify the most promising compositions and processing techniques. A particular emphasis is being placed on low cost processes to fabricate near net shape parts of practical size. Several processing methods including Vacuum Plasma Spray (VPS) and conventional PM processes are being evaluated to fabricate material property samples and components. Surrogate W-Re/ZrN cermet fuel materials are being used to develop processing techniques for both coated and uncoated ceramic particles. After process optimization, depleted uranium-based cermets will be fabricated and tested to evaluate mechanical, thermal, and hot H2 erosion properties. This paper provides details on the current results of the project.

  15. Cermet fabrication by thermal spraying and hot isostatic pressing

    International Nuclear Information System (INIS)

    An assessment is made of the feasibility of fabricating high integrity cermets by means of thermal spraying and hot isostatic pressing. Such cermets are applicable in the form of erosion-resistant gun tube liners obviating the use of such strategic elements as Co and Cr. Al2O3-28 vol percent Ni disks and cylinders were prepared by plasma spraying and hot isostatic pressing at 1350 C and 103 MPa. Characterization consisted of immersion density measurements and microstructural analysis. Specimens machined from the disks were used for thermal and mechanical properties testing. While thermal properties were found to be comparable to those of highly developed cermet systems, moduli and strengths were lower due to residual pores, high metal content, and a coarse microstructure

  16. Cold Spray Deposition of WC-Co Cermets

    OpenAIRE

    Pereira de Magalhaes e Couto, Miguel

    2014-01-01

    The main subject of this Thesis is the production of hard, wear and corrosion resistant cermets tungsten carbide and cobalt cermets (WC-Co) with different contents in cobalt matrix, onto low carbon steels and aluminum alloy Al7075-T6 substrates, by means of Cold Gas Spray (CGS). The current state of the art for the deposition of WC-Co uses High Velocity Oxy-Fuel (HVOF) as the main technique. Understanding both techniques was also one of the keys points in this work. A deep theoretical ap...

  17. Structure And Properties Of PVD Coatings Deposited On Cermets

    Directory of Open Access Journals (Sweden)

    Żukowska L.

    2015-06-01

    Full Text Available The main aim of the research is the investigation of the structure and properties of single-layer and gradient coatings of the type (Ti,AlN and Ti(C,N deposited by physical vapour deposition technology (PVD on the cermets substrate.

  18. Research on Wear Behavior of ATC Cermet Material

    Institute of Scientific and Technical Information of China (English)

    ZHULiu; LINGGuo-ping; LIJian; WANGYou-wen

    2004-01-01

    By electroless chemical deposition process, a layer of metal cobalt film was coated on the surface of nano-ceramic powders of Al2O3 and TiC. The mixture of the two kinds of Co-coated power (about 70wt.% Al2O3-Co+30wt.%TiC-Co) was hot-pressed into ATC (Al2O3-TiC-Co8wt% ) cermet samples. The wear test was carried out under dry sliding wear condition by the pin-on-disk rig. The volume-loss of the samples in three sliding pairs, ATC/Steel, ATC/SiC and ATC/artificial diamond (AD) were investigated. The wear morphologies were examined by SEM. The wear-resistance between ATC cermet and Co-cemented WC were compared. The results show that the effect of fracture toughness is better than that of hardness to the wear resistance of high hardness materials. The wear mechanisms of ATC cermet samples were found that abrasion predominated in the wear process. The wear surface of ATC cermet samples became smoother with fine asperities spalling off and the volume loss was decreased.

  19. Research on Wear Behavior of ATC Cermet Material

    Institute of Scientific and Technical Information of China (English)

    ZHU Liu; LING Guo-ping; LI Jian; WANG You-wen

    2004-01-01

    By electroless chemical deposition process, a layer of metal cobalt film was coated on the surface of nano-ceramic powders of Al203 and TiC. The mixture of the two kinds of Co-coated power (about 70wt.%Al2O3-Co+30wt.%TiC-Co) was hot-pressed into ATC (Al2O3-TiC-Co8wt%) cermet samples. The wear test was carried out under dry sliding wear condition by the pin-on-disk rig. The volume-loss of the samples in three sliding pairs,ATC/Steel, ATC/SiC and ATC/artificial diamond (AD) were investigated. The wear morphologies were examined by SEM.The wear-resistance between ATC cermet and Co-cemented WC were compared. The results show that the effect of fracture toughness is better than that of hardness to the wear resistance of high hardness materials. The wear mechanisms of ATC cermet samples were found that abrasion predominated in the wear process. The wear surface of ATC cermet samples became smoother with fine asperities spalling off and the volume loss was decreased.

  20. Dynamic SEM wear studies of tungsten carbide cermets

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined. Etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the WC and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation. The wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  1. A binder phase of TiO based cermets

    Institute of Scientific and Technical Information of China (English)

    LI Qing-kui; GUAN Shao-kang; ZHONH Hui; LI Jiang; ZHONG Hai-yun

    2005-01-01

    A binder phase of TiO based cermets, a kind of imitated gold materials, was developed by adding active element Si to Fe-Cr alloy, and the related mechanisms were studied. The wettability, matching in thermodynamics and interfacial strength were investigated by the high temperature sessile drop method and element area scanning. The linear expansion coefficients of the materials were measured using TAH100 thermal analyzer. The results show that the wettability of Fe-Cr alloy on TiO are small, with a wetting angle about 90°. After adding some Si in Fe-Cr alloy, its wetting angle can be decreased to about 25°, the interfacial reactions can be prevented effectively and high interface binding can be formed. Fe-25%Cr-1.5%Si matches the thermal expansion coefficient of TiO, so it is a kind of relatively perfect binder for TiO based cermets imitated gold.

  2. Effect of Mo2C content on the properties of TiC/TiB2 base cermets

    Science.gov (United States)

    Takagi, Ken-ichi; Osada, Ken; Koike, Wataru; Fujima, Takuya

    2009-06-01

    The effects of Mo2C content on the microstructure and mechanical properties of TiC/TiB2 base cermets were studied using the model cermets with the compositions of TiC/TiB2-(11-17)Mo2C-24Ni (mass%). TiC and TiB2 ratio is set to molar ratio of 59:41 that is near quasi-eutectic composition. As a result, both transverse rupture strength and hardness of the cermets showed maxima for the cermet containing 13% Mo2C. The cermet achieved remarkable microstructural refinement and still maintained characteristic core-rim structure of the TiC base cermets. TiC/TiB2 cermets, in addition to TiCN base cermets, are a good alternative material to cemented carbides.

  3. Ultra fine microstructure in WC-Co cermet

    Energy Technology Data Exchange (ETDEWEB)

    Lay, S.; Loubradou, M.; Donnadieu, P. [LTPCM- UMR 5614 - CNRS -INPG-UJF, Domaine Universitaire, Saint Martin d' Heres cedex (France)

    2004-10-01

    Grain growth inhibitors like VC are added to WC-Co cermets to avoid abnormal grain growth during sintering. Though the effect of vanadium is known for a long time, the controlling mechanism remains to understand. Microstructural investigations carried out on industrial samples have permitted to locate precisely the inhibitor after sintering. These results are discussed in connection with WC grain growth mechanism. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  4. Assessment of polyphase sintered iron-cobalt-iron boride cermets

    International Nuclear Information System (INIS)

    Sintering of iron, cobalt and boron powders has been analysed. As a result iron-iron boride, Fe-Fe2B and iron/cobalt boride with a slight admixture of molybdenum, Fe - Co - (FeMoCo)2B cermets have been produced. Iron was introduced to the mixture as the Astalloy Mo Hoeganaes grade powder. Elemental amorphous boron powder was used, and formation of borides occurred both during heating and isothermal sintering periods causing dimensional changes of the sintered body. Dilatometry was chosen to control basic phenomena taking place during multiphase sintering of investigated systems. The microstructure and phase constituents of sintered compacts were controlled as well. The cermets produced were substituted to: metallographic tests, X-ray analysis, measurements of hardness and of microhardness, and of wear in the process of sliding dry friction. Cermets are made up of two phases; hard grains of iron - cobalt boride, (FeCo)2B (1800 HV) constituting the reinforcement and a relatively soft and plastic eutectic mixture Fe2B - Co (400-500 HV) constituting the matrix. (author)

  5. Combustion synthesis of TiB2-based cermets: modeling and experimental results

    NARCIS (Netherlands)

    Martinez Pacheco, M.; Bouma, R.H.B.; Katgerman, L.

    2008-01-01

    TiB2-based cermets are prepared by combustion synthesis followed by a pressing stage in a granulate medium. Products obtained by combustion synthesis are characterized by a large remaining porosity (typically 50%). To produce dense cermets, a subsequent densification step is performed after the comb

  6. Magnetic Properties of the WC-Co Cermet Powders

    Science.gov (United States)

    Serban, V. A.; Malaescu, I.; Ercuta, A.; Marin, C. N.; Stefu, N.; Opris, C.; Codrean, C.; Utu, D.

    2010-08-01

    The magnetic behavior, both quasistatic (50 Hz) and dynamic (10 kHz-1 MHz) of a set of three powder samples from the WC-Co cermet system were investigated in the as-cast state. The results have shown magnetic hysteresis in the low frequency AC fields. In high frequency fields, the complex magnetic permeability was examined; a weak maximum of the imaginary component that was detected in the frequency range close to 100 kHz was attributed to structure-dependent magnetic relaxation.

  7. Mechanism of Combustion Synthesis of TiC-Ti Cermet

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In order to investigate the mechanism of combustion synthesis of TiC-Ti cermet, a mixture of Ti and C was used for a combustion front quenching test, and the microstructural evolution in the quenched sample was analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX). Also,a temperature-time profile of the combustion reaction was measured. Based on the experimental results, a reaction-dissolution-precipitation mechanism of the combustion synthesis of TiC-Ti was proposed.

  8. Biocompatibility assessment of spark plasma-sintered alumina-titanium cermets.

    Science.gov (United States)

    Guzman, Rodrigo; Fernandez-García, Elisa; Gutierrez-Gonzalez, Carlos F; Fernandez, Adolfo; Lopez-Lacomba, Jose Luis; Lopez-Esteban, Sonia

    2016-01-01

    Alumina-titanium materials (cermets) of enhanced mechanical properties have been lately developed. In this work, physical properties such as electrical conductivity and the crystalline phases in the bulk material are evaluated. As these new cermets manufactured by spark plasma sintering may have potential application for hard tissue replacements, their biocompatibility needs to be evaluated. Thus, this research aims to study the cytocompatibility of a novel alumina-titanium (25 vol. % Ti) cermet compared to its pure counterpart, the spark plasma sintered alumina. The influence of the particular surface properties (chemical composition, roughness and wettability) on the pre-osteoblastic cell response is also analyzed. The material electrical resistance revealed that this cermet may be machined to any shape by electroerosion. The investigated specimens had a slightly undulated topography, with a roughness pattern that had similar morphology in all orientations (isotropic roughness) and a sub-micrometric average roughness. Differences in skewness that implied valley-like structures in the cermet and predominance of peaks in alumina were found. The cermet presented a higher surface hydrophilicity than alumina. Any cytotoxicity risk associated with the new materials or with the innovative manufacturing methodology was rejected. Proliferation and early-differentiation stages of osteoblasts were statistically improved on the composite. Thus, our results suggest that this new multifunctional cermet could improve current alumina-based biomedical devices for applications such as hip joint replacements.

  9. Tribological properties of TiA1N-coated cermets

    Institute of Scientific and Technical Information of China (English)

    ZHENG Liyun; ZHAO Lixin; XIONG Weihao

    2009-01-01

    Ti(C,N)-based cermets were coated with TiAlN using multi-arc ion plating technology. Sliding wear tests were performed on the coated cermets. The microstructure and morphologies oftbe coated cermets before and after friction and wear tests were characterized. The results show that the TiAlN coating surface was smooth and its root mean square roughness was 16.6 nm. The hardness (HK) of TiAlN coating lay-ers reached approximately 3200 and the critical load (Lc) under which the coating failure occurred was 59 N. The sliding wear test results show that the friction coefficients of the TiAlN-coated cermets were lower than that of the cermets without any coating. Under the same load, the adhesion phenomenon of the counterpart materials on the specimens was improved and the mean friction coefficient increased with in-average friction coefficient of the TiAlN-coated cermets was lower under a higher load. The wear mechanisms of the TiAIN-coated cermets were mainly adhesive and abrasive wear.

  10. Development and Characterization of Nanostructured Cermet Coatings Produced by Co-electrodeposition

    Science.gov (United States)

    Farrokhzad, Mohammad Ali

    Nanostructured cermet (ceramic-metallic) coatings are a group of materials that combine properties possessed by ceramics, such as oxidation resistance and high hardness, and the properties of metals such as strength and ductility. These coatings consist of nano-sized metal-oxide particles (i.e. Al2 O3) dispersed into a corrosion resistant metal matrix such as nickel. Cermet coatings have been used in many industrial applications such as cutting tools and jet engines where high temperature and erosion resistance performance are required. However, despite the promising properties, the lack of experimental data and theories on high temperature oxidation and mechanical properties of cermet coatings have restricted their full potential to be used in technologies for oil sand production such as In-Situ Combustion (ISC). In this study, the structure of cermet coatings was investigated to identify the characteristics that give rise to oxidation performance and wear resistance properties of cermet coatings. The experimental oxidation results on the single-component oxide cermet coatings showed that when Al2O3 and TiO2 were combined in the electrolyte, the new combination can improve oxidation performance (less mass gain) as compared to a pure Ni coating. Based on the oxidation and micro-hardness results, a new group of nanostructured cermet coatings (double-component oxides) was developed and investigated using long term oxidation tests, thermo-gravimetric analysis in mixed gas, thermal cycling, micro-hardness and abrasive wear tests. The mechanical analysis of the newly developed coatings showed improved resistance against wear and thermal cycling compared to single-component oxide cermet and pure Ni coatings. Furthermore, some new theoretical analysis were also put forward that aims at a new explanation of high temperature oxidation for cermet coatings.

  11. Oxygen potential of a prototypic Mo-cermet fuel containing plutonium oxide

    Science.gov (United States)

    Miwa, Shuhei; Osaka, Masahiko; Nozaki, Takahiro; Arima, Tatsumi; Idemitsu, Kazuya

    2015-10-01

    Oxygen potential of a prototypic Mo-cermet fuel containing 50 vol.% PuO2-x were investigated by the thermogravimetric analysis in the temperature range from 1273 K to 1473 K. It was shown that the oxygen potential and oxidation rate of the Mo-cermet were the same as those of pure PuO2-x below the oxygen potential of Mo/MoO2 oxidation reaction. The same features of the Mo-cermet sample containing 50 vol.% PuO2-x with those of pure PuO2-x were discussed in terms of the microstructure.

  12. Characteristics and fabrication of cermet spent nuclear fuel casks: ceramic particles embedded in steel

    Energy Technology Data Exchange (ETDEWEB)

    Forsberg, C.W.; Swaney, P.M.; Tiegs, T.N. [Oak Ridge National Lab., Oak Ridge, TN (United States)

    2004-07-01

    Cermets are being investigated as an advanced material of construction for casks that can be used for storage, transport, or disposal of spent nuclear fuel (SNF). Cermets, which consist of ceramic particles embedded in steel, are a method to incorporate brittle ceramics with highly desirable properties into a strong ductile metal matrix with a high thermal conductivity, thus combining the best properties of both materials. Traditional applications of cermets include tank armor, vault armor, drill bits, and nuclear test-reactor fuel. Cermets with different ceramics (DUO{sub 2}, Al{sub 2}O{sub 3}, Gd{sub 2}O{sub 3}, etc.) are being investigated for the manufacture of SNF casks. Cermet casks offer four potential benefits: greater capacity (more SNF assemblies) for the same gross weight cask, greater capacity (more SNF assemblies) for the same external dimensions, improved resistance to assault, and superior repository performance. These benefits are achieved by varying the composition, volume fraction, and particulate size of the ceramic particles in the cermet with position in the cask body. Addition of depleted uranium dioxide (DUO{sub 2}) to the cermet increases shielding density, improves shielding effectiveness, and increases cask capacity for a given cask weight or size. Addition of low-density aluminium oxide (Al{sub 2}O{sub 3}) to the outer top and bottom sections of the cermet cask, where the radiation levels are lower, can lower cask weight without compromising shielding. The use of Al2O3 and other oxides, in appropriate locations, can increase resistance to assault. Repository performance may be improved by compositional control of the cask body to (1) create a local geochemical environment that slows the long-term degradation of the SNF and (2) enables the use of DUO{sub 2} for longterm criticality control. While the benefits of using cermets follow directly from their known properties, the primary challenge is to develop low-cost methods to fabricate

  13. Microstructure and Raman spectra of Ag-MgF2 cermet films

    Institute of Scientific and Technical Information of China (English)

    Shouhua Shi(史守华); Zhuoliang Cao(曹卓良); Zhaoqi Sun(孙兆奇)

    2003-01-01

    Ag-MgF2 cermet films with different Ag fractions were prepared by vacuum evaporation. The microstruc-ture of the films was examined by Raman scattering technique. The surface-enhanced Raman spectrumfor MgF2 molecules in the cermet film strongly suggests the existence of Ag nanoparticles dispersed inMgF2 matrix. The intensities of the Raman spectra of Ag-MgF2 cermet films increase with Ag fraction.The enhancement of Raman scattering disappears when Ag content reaches wt.20%. The analyses withthe transmission electron microscopy showed that Ag-MgF2 cermet films are mainly composed of amor-phous MgF2 matrix with embedded faced-center-cubic Ag nanoparticles. It suggests that the percolationthreshold should be around wt.20% of Ag content.

  14. The Influence of Sintering Temperature of Reactive Sintered (Ti, MoC-Ni Cermets

    Directory of Open Access Journals (Sweden)

    Marek Jõeleht

    2015-09-01

    Full Text Available Titanium-molybdenum carbide nickel cermets ((Ti, MoC-Ni were produced using high energy milling and reactive sintering process. Compared to conventional TiC-NiMo cermet sintering the parameters for reactive sintered cermets vary since additional processes are present such as carbide synthesis. Therefore, it is essential to acquire information about the suitable sintering regime for reactive sintered cermets. One of the key parameters is the final sintering temperature when the liquid binder Ni forms the final matrix and vacancies inside the material are removed. The influence of the final sintering temperature is analyzed by scanning electron microscopy. Mechanical properties of the material are characterized by transverse rupture strength, hardness and fracture toughness.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7179

  15. Properties of U sub 3 O sub 8 -aluminum cermet fuel

    Energy Technology Data Exchange (ETDEWEB)

    Peacock, H.B.

    1989-10-01

    Nuclear fuel elements containing U{sub 3}O{sub 8} dispersed in an aluminum matrix have been used in research and test reactors for about 30 years. These elements, sometimes called cermet fuel, are made by powder metallurgical methods (PM) and can accommodate up to approximately 50 wt % uranium in the core section of extruded tubes. Cermet fuel elements have been fabricated and irradiated at the Savannah River Site (SRS). Irradiation behavior is excellent. Extruded tubes with up to 50 wt % uranium have been successfully irradiated to fission densities of about 2 {times} 10{sup 21} fissions per cc of core. Physical, mechanical, and chemical properties of cermet fuels are assembled into a reference document. Results will be used by Argonne National Laboratory to design cermet fuel elements for possible use in the New Production Reactor at SRS. 57 refs., 33 figs., 12 tabs.

  16. Steady polarization process modelling of noble metal-electrolyte cermet composite electrode

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Cermet composites containing mixture of noble metal phase and electrolyte phase are the state-of-the-art electrode materials used for electrochemical sensor and solid oxide fuel cell(SOFC). A steady polarization model was developed. The model was based on electronic and ionic transfer process together with the electrochemical reaction regardless of mass transport in the electrode. The modelling results can help to understand the electrochemistry of cermet composite electrode.

  17. Numerical Simulation of Brazing TiC Cermet to Iron with TiZrNiCu Filler Metal

    Institute of Scientific and Technical Information of China (English)

    Lixia ZHANG; Jicai FENG

    2004-01-01

    The maximum thermal stress and stress concentration zones of iron/TiC cermet joint during cooling were studied in this paper. The results showed that the shear stress on iron/TiC cermet joint concentrates on the interface tip and the maximum shear stress appears on the left tip of iron/TiZrNiCu interlace. Positive tensile stress on TiC cermet undersurface concentrates on both sides of TiC cermet and its value decreases during cooling. Negative tensile stress on TiC cermet undersurface concentrates on the center of TiC cermet and its value increases during cooling. Brazing temperature has little effect on the development and maximum thermal stress.

  18. Nanocomposite cermets for hydrogen production and SOFC anodes

    Energy Technology Data Exchange (ETDEWEB)

    Mezentseva, Natalia; Alikina, Galina; Pelipenko, Vladimir [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Smorygo, Oleg [Powder Metallurgy Institute, Minsk (Belarus); Ross, Julian R.H. [Limerick Univ. (Iran, Islamic Republic of). Centre of Environmental Research; Sadykov, Vladislav [Boreskov Institute of Catalysis, Novosibirsk (Russian Federation); Novosibirsk State Univ. (Russian Federation)

    2010-07-01

    Nanocomposite cermets comprised of Ni particles (10-60 wt.%) embedded into complex oxide matrix (Y- or Sc-stabilized zirconia combined with doped Ce-Zr oxides or perovskites) and promoted by Pt or Tu were synthesized via Pechini and (co)impregnation routes. Samples were characterized by BET, XRD, TEM with EDX, H{sub 2}, C{sub 2}H{sub 5}OH and CH{sub 4} TPR. The catalytic properties of nanocomposite materials were studied in the Sr of CH{sub 4}, ethanol and acetone at intermediate temperatures and short contact times. Performance of best compositions supported as porous strongly adhering layers on several types of heat-conducting substrates was demonstrated to be high and stable in SR (steam reforming) for all types of fuels. (orig.)

  19. Fracture toughness of two phase WC-Co cermets

    International Nuclear Information System (INIS)

    The present analysis is an attempt to show that fracture toughness of cermets based on WC-Co and the like can be predicted with reasonable accuracy from a simple fracture mechanics relationship. The resistance to fracture has been considered to manifest primarily from the plastic deformation of Co phase. The constrained deformation behavior of the ductile Co phase between the rigid WC grains, approximated to the behavior of ideal plastic flow of a ductile layer sandwiched between rigid platens, has been incorporated into the fracture toughness predictions. Reasonable assumptions on in situ flow and fracture behavior of Co phase have been made in such estimations. Comparison of the calculated fracture toughness values with the experimental data of a large number of WC-Co systems of varying microstructural conditions, indicates reasonable agreement

  20. Evolution of Ti(C,N)-based cermet microstructures

    Institute of Scientific and Technical Information of China (English)

    李晨辉; 熊惟皓; 余立新

    2002-01-01

    Two series of Ti(C,N)-based cermet materials originating from the same chemical composition but with different grain size distribution and sintered to different stages of the sintering cycle have been studied using SEM,TEM,EDX,and XRD.Much of the surrounding structure is formed during solid state sintering.During the solid state sintering,at first,the Mo and W rich (Ti,Mo,W)C inner rim is formed by the interaction among TiC,WC,and Mo2C;then the Mo and W lean (Ti,Mo,W)(C,N)outer rim is formed.During the liquid phase sintering,the outer rim of coarse grains grows rapidly throw a solution-reprecipitation process;also coarse grains grow by particle coalescence.The interface between coarse grain outer rim and binder is flat (crystal surface).

  1. Cermet sphere-pac concept for inert matrix fuel

    Science.gov (United States)

    Pouchon, M. A.; Nakamura, M.; Hellwig, Ch.; Ingold, F.; Degueldre, C.

    2003-06-01

    In the inert matrix fuel concept, plutonium reprocessed from spent fuel is burned in an inert matrix, e.g. yttria-stabilized zirconia. Coming from wet reprocessing, the internal gelation can perform an easy micro-spheres production. Utilization of these particles in a sphere-pac realizes a direct fuel production. Besides being economical, this direct usage offers an almost dustless fabrication. One disadvantage of yttria-stabilized zirconia as matrix is its low thermal conductivity. A further reduction by the macroscopic structure of a sphere bed seems unacceptable. This can be eluded by the insertion of a highly conducting phase. Similar to the cermet concept with the embedment of ceramic fuel into metal, the infiltration of a fine metal fraction into a coarse ceramic fuel fraction is studied here. The initial thermal conductivity shows much higher calculated values and the sintering behaviour is also clearly enhanced compared to the pure ceramic bed.

  2. Effect of a titanium nitride interlayer on the densification, properties and microstructure of cermets based on alumina and nickel. Part 1: Densification and properties

    NARCIS (Netherlands)

    Li, Shujie; Khosrovabadi, Paul Babayan; Kolster, Ben H.

    1992-01-01

    In order to manufacture cermets based on Al2O3 and Ni, Al2O3 particles were first coated with TiN by CVD and then mixed with pure Ni powder. The cermets were produced from the mixed powders by powder metallurgy processes. The relative density and the mechanical properties of the cermets are improved

  3. Preparation and preliminary testing of cermet inert anode for aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    李劼; 赖延清; 周科朝; 李志友; 刘业翔

    2003-01-01

    Recent development of inert anodes for the primary aluminium industry was reviewed. The preparation method of functionally gradient material was introduced into inert anode research area, and a research flow sheet of functionally gradient cermet inert anode was set down. In order to carry out the preparation and optimization of composite oxides as the ceramic matrix of cermet inert anode, the following problems: solid state reaction synthesis of complex oxides, corrosion mechanism of complex oxides in Na3AlF6-Al2O3 melts, effects of NiO content on the corrosion rate and resistivity at high temperature of NiFe2O4-NiO ceramics were studied. The preparation and sintering mechanism of NiFe2O4 based cermets were deeply studied to properly control the sintering atmosphere and temperature system. By efficaciously controlling the sintering atmosphere, the oxidization of metallic phase and the decomposition or deoxidization of ceramic phase are avoided effectively during the sintering process of cermets at various temperatures. By optimizing the composition recipe and sintering temperature system, cermets of relatively high density are prepared without the spillage or asymmetric distribution of metallic phase.

  4. Mo-Al{sub 2}O{sub 3} cermet research and development

    Energy Technology Data Exchange (ETDEWEB)

    Glass, S.J.; Monroe, S.L.; Stephens, J.J.; Moore, R.H. [and others

    1997-08-01

    This report describes the results to date of a program that was initiated to predict and measure residual stresses in Mo-Al{sub 2}O{sub 3} cermet-containing components and to develop new materials and processes that would lead to the reduction or elimination of the thermal mismatch stresses. The period of performance includes work performed CY95-97. Excessive thermal mismatch stresses had produced cracking in some cermet-containing neutron tube components. This cracking could lead to a loss of hermeticity or decreased tube reliability. Stress predictions were conducted using finite element models of the various components, along with the thermal coefficient of expansion (CTE), Young`s modulus, and strength properties. A significant portion of the program focused on the property measurements for the existing cermet materials, processing conditions, and the measurement technique. The effects of differences in the properties on the predicted residual stresses were calculated for existing designs. Several potential approaches were evaluated for reducing the residual stresses and cracking in cermet-containing parts including reducing the Mo content of the cermet, substituting a ternary alloy with a better CTE match with alumina, and substituting Nb for Mo. Processing modifications were also investigated for minimizing warpage that occurs during sintering due to differential sintering. These modifications include changing the pressing of the 94ND2 alumina and changing to a 96% alumina powder from AlSiMag.

  5. Low Cost Nuclear Thermal Rocket Cermet Fuel Element Environment Testing

    Science.gov (United States)

    Bradley, David E.; Mireles, Omar R.; Hickman, Robert R.

    2011-01-01

    Deep space missions with large payloads require high specific impulse (Isp) and relatively high thrust in order to achieve mission goals in reasonable time frames. Conventional, storable propellants produce average Isp. Nuclear thermal rockets (NTR) capable of high Isp thrust have been proposed. NTR employs heat produced by fission reaction to heat and therefore accelerate hydrogen which is then forced through a rocket nozzle providing thrust. Fuel element temperatures are very high (up to 3000K) and hydrogen is highly reactive with most materials at high temperatures. Data covering the effects of high temperature hydrogen exposure on fuel elements is limited. The primary concern is the mechanical failure of fuel elements which employ high-melting-point metals, ceramics or a combination (cermet) as a structural matrix into which the nuclear fuel is distributed. It is not necessary to include fissile material in test samples intended to explore high temperature hydrogen exposure of the structural support matrices. A small-scale test bed designed to heat fuel element samples via non-contact RF heating and expose samples to hydrogen is being developed to assist in optimal material and manufacturing process selection without employing fissile material. This paper details the test bed design and results of testing conducted to date.

  6. Zr-ZrO2 cermet solar coatings designed by modelling calculations and deposited by dc magnetron sputtering

    Science.gov (United States)

    Zhang, Qi-Chu; Hadavi, M. S.; Lee, K.-D.; Shen, Y. G.

    2003-03-01

    High solar performance Zr-ZrO2 cermet solar coatings were designed using a numerical computer model and deposited experimentally. The layer thickness and Zr metal volume fraction for the Zr-ZrO2 cermet solar selective coatings on a Zr or Al reflector with a surface ZrO2 or Al2O3 anti-reflection layer were optimized to achieve maximum photo-thermal conversion efficiency at 80°C under concentration factors of 1-20 using the downhill simplex method in multi-dimensions in the numerical calculation. The dielectric function and the complex refractive index of Zr-ZrO2 cermet materials were calculated using Sheng's approximation. Optimization calculations show that Al2O3/Zr-ZrO2/Al solar coatings with two cermet layers and three cermet layers have nearly identical solar absorptance, emittance and photo-thermal conversion efficiency that are much better than those for films with one cermet layer. The optimized Al2O3/Zr-ZrO2/Al solar coating film with two cermet layers has a high solar absorptance value of 0.97 and low hemispherical emittance value of 0.05 at 80°C for a concentration factor of 2. The Al2O3/Zr-ZrO2/Al solar selective coatings with two cermet layers were deposited using dc magnetron sputtering technology. During the deposition of Zr-ZrO2 cermet layer, a Zr metallic target was run in a gas mixture of argon and oxygen. By control of oxygen flow rate the different metal volume fractions in the cermet layers were achieved using dc reactive sputtering. A solar absorptance of 0.96 and normal emittance of 0.05 at 80°C were achieved.

  7. Zr-ZrO{sub 2} cermet solar coatings designed by modelling calculations and deposited by dc magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Qichu [School of Physics, University of Sydney, NSW 2006 (Australia); Hadavi, M S [School of Physics, University of Sydney, NSW 2006 (Australia); Lee, K-D [School of Physics, University of Sydney, NSW 2006 (Australia); Shen, Y G [Department of Manufacturing Engineering and Engineering Management, City University of Hong Kong, Hong Kong (China)

    2003-03-21

    High solar performance Zr-ZrO{sub 2} cermet solar coatings were designed using a numerical computer model and deposited experimentally. The layer thickness and Zr metal volume fraction for the Zr-ZrO{sub 2} cermet solar selective coatings on a Zr or Al reflector with a surface ZrO{sub 2} or Al{sub 2}O{sub 3} anti-reflection layer were optimized to achieve maximum photo-thermal conversion efficiency at 80 deg. C under concentration factors of 1-20 using the downhill simplex method in multi-dimensions in the numerical calculation. The dielectric function and the complex refractive index of Zr-ZrO{sub 2} cermet materials were calculated using Sheng's approximation. Optimization calculations show that Al{sub 2}O{sub 3}/Zr-ZrO{sub 2}/Al solar coatings with two cermet layers and three cermet layers have nearly identical solar absorptance, emittance and photo-thermal conversion efficiency that are much better than those for films with one cermet layer. The optimized Al{sub 2}O{sub 3}/Zr-ZrO{sub 2}/Al solar coating film with two cermet layers has a high solar absorptance value of 0.97 and low hemispherical emittance value of 0.05 at 80 deg. C for a concentration factor of 2. The Al{sub 2}O{sub 3}/Zr-ZrO{sub 2}/Al solar selective coatings with two cermet layers were deposited using dc magnetron sputtering technology. During the deposition of Zr-ZrO{sub 2} cermet layer, a Zr metallic target was run in a gas mixture of argon and oxygen. By control of oxygen flow rate the different metal volume fractions in the cermet layers were achieved using dc reactive sputtering. A solar absorptance of 0.96 and normal emittance of 0.05 at 80 deg. C were achieved.

  8. Spark Plasma Sintering Properties of Ultrafine Ti ( C,N)-based Cermet

    Institute of Scientific and Technical Information of China (English)

    FENG Ping; XIONG Wei-hao; ZHENG Yong; YU Li-xin; XIA Yang-hua

    2004-01-01

    Ultrafine Ti( C, N )-based cermet was sintered by SPS from 1050℃ to 1450℃ and its sintering properties, such as porosity, mechanical properties and phase transformation, were investigated by optical mi-croscopy (OM), scanning electron microscopy (SEM), X- ray diffraction (XRD), and differential scanning calo-rimeter (DSC). It is found that the spark plasma sintering properties of Ti( C, N )-based cermet differ from thoseof conventional vacuum sintering. The liquid phase appearance is at least lower by 150℃ than that in vacuum sin-tering. The porosity decreases sharply below 1 200℃ and reaches minimum at 1 200℃ , and afterwards it almostkeeps invariable and no longer increases. SPS remarkably accelerates the phase transformation of Ti( C, N )-basedcermet and it has a powerful ability to remove oxides in Ti( C, N )-based cermets. Above 1 3502 ,denitrificationoccurred. Fresh graphite phase formed above 1 430℃ . Both the porosity and graphite are responsible for the poor TRS.

  9. Fabrication of cermet bearings for the control system of a high temperature lithium cooled nuclear reactor

    Science.gov (United States)

    Yacobucci, H. G.; Heestand, R. L.; Kizer, D. E.

    1973-01-01

    The techniques used to fabricate cermet bearings for the fueled control drums of a liquid metal cooled reference-design reactor concept are presented. The bearings were designed for operation in lithium for as long as 5 years at temperatures to 1205 C. Two sets of bearings were fabricated from a hafnium carbide - 8-wt. % molybdenum - 2-wt. % niobium carbide cermet, and two sets were fabricated from a hafnium nitride - 10-wt. % tungsten cermet. Procedures were developed for synthesizing the material in high purity inert-atmosphere glove boxes to minimize oxygen content in order to enhance corrosion resistance. Techniques were developed for pressing cylindrical billets to conserve materials and to reduce machining requirements. Finishing was accomplished by a combination of diamond grinding, electrodischarge machining, and diamond lapping. Samples were characterized in respect to composition, impurity level, lattice parameter, microstructure and density.

  10. Fabrication of WC-Co cermets by laser engineered net shaping

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Yuhong [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States); Smugeresky, John E. [Sandia National Laboratories, Livermore, CA 94551 (United States); Ajdelsztajn, Leonardo [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States); Schoenung, Julie M. [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States)], E-mail: jmschoenung@ucdavis.edu

    2008-10-15

    The Laser Engineered Net Shaping (LENS) technology is an extension of rapid prototyping technologies into the direct fabrication of metal parts. Bulk dense tungsten carbide-cobalt (WC-Co) cermets were produced without any molds using the LENS technology, starting from granules consisting of nanostructured WC crystallites in a Co matrix. Thermal behavior of the LENS process, shape change and coarsening of WC crystallites were investigated in this work to study the mechanisms of microstructural evolution of the cermets. Microstructures with alternating layers were observed, which is relevant to the thermal behavior of the LENS process. Variations in hardness result from the change in cooling rate along the specimen height.

  11. Grain size stabilization of tetragonal phase of zirconia in sputtered Zr- O cermet films

    OpenAIRE

    M. S. Hadavi; S. H. Keshmiri; A. Kompany; Zhang, Q. C.

    2005-01-01

     In this research, thin films of Zr/ZrO2 composites were deposited by reactive magnetron sputtering technique on Si and fused Silica substrates, and their structures were investigated by XRD method. During the deposition of the cermet layers, a Zr metallic target was sputtered in a gas mixture of Ar and O2. By controlling of O2 flow rate, the different metal volume fractions in the cermet layers were achieved. The optical response of the samples was studied using spectroscopy methods. Also th...

  12. Low Cost Nuclear Thermal Rocket Cermet Fuel Element Environment Testing

    Science.gov (United States)

    Bradley, D. E.; Mireles, O. R.; Hickman, R. R.

    2011-01-01

    Deep space missions with large payloads require high specific impulse and relatively high thrust to achieve mission goals in reasonable time frames.1,2 Conventional storable propellants produce average specific impulse. Nuclear thermal rockets capable of producing high specific impulse are proposed. Nuclear thermal rockets employ heat produced by fission reaction to heat and therefore accelerate hydrogen, which is then forced through a rocket nozzle providing thrust. Fuel element temperatures are very high (up to 3000 K), and hydrogen is highly reactive with most materials at high temperatures. Data covering the effects of high-temperature hydrogen exposure on fuel elements are limited.3 The primary concern is the mechanical failure of fuel elements that employ high-melting-point metals, ceramics, or a combination (cermet) as a structural matrix into which the nuclear fuel is distributed. The purpose of the testing is to obtain data to assess the properties of the non-nuclear support materials, as-fabricated, and determine their ability to survive and maintain thermal performance in a prototypical NTR reactor environment of exposure to hydrogen at very high temperatures. The fission process of the planned fissile material and the resulting heating performance is well known and does not therefore require that active fissile material be integrated in this testing. A small-scale test bed designed to heat fuel element samples via non-contact radio frequency heating and expose samples to hydrogen is being developed to assist in optimal material and manufacturing process selection without employing fissile material. This paper details the test bed design and results of testing conducted to date.

  13. Nickel/Yttria-stabilised zirconia cermet anodes for solid oxide fuel cells

    NARCIS (Netherlands)

    Primdahl, Søren

    1999-01-01

    This thesis deals with the porous Ni/yttria-stabilized zirconia (YSZ) cermet anode on a YSZ electrolyte for solid oxide fuel cells (SOFC). Such anodes are predominantly operated in moist hydrogen at 700°C to 1000°C, and the most important technological parameters are the polarization resistance and

  14. The possible use of cermet fuel in the DIDO and PLUTO heavy-water research reactors

    International Nuclear Information System (INIS)

    International restrictions on the supply of highly enriched uranium have resulted in the requirement to fuel research reactors with a lower-enrichment uranium fuel. A study has been made of the feasibility of using low-enrichment fuels of a new type in the DIDO and PLUTO reactors. This work has been done as a contribution to the studies currently being carried out internationally on the implications of using lower-enrichment fuels in heavy-water-moderated research reactors. The uranium content of the U/Al alloy at present used cannot be increased sufficiently to maintain the requisite U235 content without undesirable effects on the physical properties of the alloy. A different type of fuel will therefore be required to maintain the desired nuclear characteristics. A possible solution to the problem is the use of a cermet (U3O8/Al) fuel material. Cermet fuel has poorer thermal conductivity than metallic fuel, and may also contain particles of the ceramic of a size that approaches the total thickness of the cermet core. We therefore have to consider both the average temperature of the centre of the fuel and whether large particles of the ceramic may be significantly hotter than the average. This paper describes a preliminary study of the feasibility of this concept from the heat-transfer and safety viewpoints. Calculations have been made for a cermet of 20%-enrichment 2.3g U/cm3, used in a high-power element in a DIDO-type reactor. To accommodate the cermet, the cladding has been reduced in thickness to 0.318mm (0.0125 in) the core increasing to 1.044mm, but the fuel geometry is otherwise unchanged. It is concluded that from the heat-transfer viewpoint there is no problem during normal operation or the maximum credible power transient in these reactors. (author). 10 refs, 6 figs, 2 tabs

  15. Microstructural development and mechanical properties of iron based cermets processed by pressureless and spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Alvaredo, P. [Department of Materials Science and Engineering, IQMAAB, University Carlos III Madrid, Avda. de la Universidad, 30, 28911 Leganes (Spain); Gordo, E., E-mail: elena.gordo@uc3m.es [Department of Materials Science and Engineering, IQMAAB, University Carlos III Madrid, Avda. de la Universidad, 30, 28911 Leganes (Spain); Van der Biest, O.; Vanmeensel, K. [Katholieke Universiteit Leuven, Kasteelpark Arenberg, 44 3001 Heverlee (Belgium)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Processing of Fe-based cermets by pressureless sintering and spark plasma sintering. Black-Right-Pointing-Pointer Influence of carbon content on the sintering mechanism and hardness. Black-Right-Pointing-Pointer The cermet phase diagram was calculated and permits to explain the microstructure. Black-Right-Pointing-Pointer SPS provides ferritic matrix and different carbide distribution than CPS samples. Black-Right-Pointing-Pointer Pressureless sintered samples contain retained austenite at room temperature. - Abstract: Iron-based cermets are an interesting class of metal-ceramic composites in which properties and the factors influencing them are to be explored. In this work the metal matrix contains Cr, W, Mo and V as alloying elements, and the hard phase is constituted by 50 vol% of titanium carbonitride (TiCN) particles. The work studies the influence of the C content and the processing method on the sinterability, microstructure and hardness of the developed cermet materials. For that purpose, cermet samples with different C content in the matrix (0 wt%, 0.25 wt%, 0.5 wt%, 1.0 wt%) were prepared by conventional pressureless sintering (CPS) and, in order to achieve finer microstructures and to reduce the sintering time, by spark plasma sintering (SPS). The density and hardness (HV30) of the processed materials was evaluated, while their phase composition and microstructure was characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The equilibrium phase diagram of the composite material was calculated by ThermoCalc software in order to elucidate the influence of the carbon content on the obtained phases and developed microstructures.

  16. Resource recovery of WC-Co cermet using hydrothermal oxidation technique

    Energy Technology Data Exchange (ETDEWEB)

    Gao Ningfeng [EcoTopia Science Inst., Nagoya Univ., Nagoya (Japan); Advanced Mfg. Research Inst., National Inst. of Advanced Industrial Science and Technology, Nagoya (Japan); Inagaki, F.; Sasai, R.; Itoh, H. [EcoTopia Science Inst., Nagoya Univ., Nagoya (Japan); Watari, K. [Advanced Mfg. Research Inst., National Inst. of Advanced Industrial Science and Technology, Nagoya (Japan)

    2005-07-01

    WC-Co cermet is widely used in industrial applications such as cutting tools, dies, wear parts and so on. It is of great importance to establish the recycling process for the precious metal resources contained in WC-Co cermet, because all these metals used in Japan are imported. In this paper we reported a hydrothermal oxidation technique using nitric acid for the reclamation of WC and Co. The WC-Co cermet specimens with various WC particle sizes and Co contents were hydrothermally treated in HNO{sub 3} aqueous solutions at temperatures of 110-200 C for durations of 6-240 h. The Co was preferentially leached out into the acidic solution, while the WC was oxidized to insoluble WO{sub 3} hydrate which was subsequently separated by filtration. The hydrothermal treatment parameters such as solvent concentrations, treatment temperatures, holding time were optimized in respect to different kinds of WC-Co cermets. A hydrothermal oxidation treatment in 3M HNO{sub 3} aqueous solution at 150 C for 24 h was capable of fully disintegrating the cermet chip composed of coarse WC grains of 1-5 {mu}m in size with 20 wt% of Co as binder. While the more oxidation resistant specimen composed of fine WC grains of 0.5-1.0 {mu}m in size with 13 wt% of Co, was completely disintegrated by a treatment in 7 M HNO{sub 3} aqueous solution at 170 C for 24 h. The filtered solid residues were composed of fine WO{sub 3}.0.33H{sub 2}O powder and a small amount of WO{sub 3}. The recovered WO{sub 3}.0.33H{sub 2}O powder can be easily returned to the industrial process for the synthesis of WC powder so that the overall recycling cost can be possibly lowered. (orig.)

  17. Microstructural development and mechanical properties of iron based cermets processed by pressureless and spark plasma sintering

    International Nuclear Information System (INIS)

    Highlights: ► Processing of Fe-based cermets by pressureless sintering and spark plasma sintering. ► Influence of carbon content on the sintering mechanism and hardness. ► The cermet phase diagram was calculated and permits to explain the microstructure. ► SPS provides ferritic matrix and different carbide distribution than CPS samples. ► Pressureless sintered samples contain retained austenite at room temperature. - Abstract: Iron-based cermets are an interesting class of metal-ceramic composites in which properties and the factors influencing them are to be explored. In this work the metal matrix contains Cr, W, Mo and V as alloying elements, and the hard phase is constituted by 50 vol% of titanium carbonitride (TiCN) particles. The work studies the influence of the C content and the processing method on the sinterability, microstructure and hardness of the developed cermet materials. For that purpose, cermet samples with different C content in the matrix (0 wt%, 0.25 wt%, 0.5 wt%, 1.0 wt%) were prepared by conventional pressureless sintering (CPS) and, in order to achieve finer microstructures and to reduce the sintering time, by spark plasma sintering (SPS). The density and hardness (HV30) of the processed materials was evaluated, while their phase composition and microstructure was characterised by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The equilibrium phase diagram of the composite material was calculated by ThermoCalc software in order to elucidate the influence of the carbon content on the obtained phases and developed microstructures.

  18. The development of fabrication techniques for europia/iron cermets tips for coarse control arms in Dido and Pluto

    International Nuclear Information System (INIS)

    The applicability of cermet-fabrication techniques to the production of europia/iron cermets for use as coarse-control arm tips in the materials test reactors DIDO and PLUTO has been investigated. Spheroids of europia were prepared by a dry agglomeration process. These were sintered, dispersed in iron powder and pressed into plates; the plates were then sintered to densify the iron matrix. These stages were optimised to produce a strong cermet with a europia density of 2.75 g/cm3. The uniformity of distribution of the absorber particles was confirmed by radiography, and adequate neutron-absorption worth by measurements carried out in the GLEEP reactor. An outline flow sheet has been prepared for the manufacture of europia/iron cermet plates suitable for use in the tips of DIDO and PLUTO coarse-control arms. (U.K.)

  19. Preparation and properties of 4. 25Cu-0.75Ni/NiFe2O4 cermet

    Institute of Scientific and Technical Information of China (English)

    LI Jie; ZHANG Gang; LAI Yan-qing; TIAN Zhong-liang; QIN Qing-wei

    2005-01-01

    4.25Cu-0.75Ni/NiFe2 O4 cermets were prepared by doping NiFe2 O4 ceramic matrix with the mixed powders of Cu and Ni or Cu-Ni alloy powder as the electrical conducting metallic elements. The effects of technological parameters, such as the adding modes of metallic elements, the ball milling time, the sintering time and the sintering temperature, on the relative density and resistivity of the cermets were studied. The results show that the resistivity of 4.25Cu-0.75Ni/NiFe2 O4 cermets decreases with increasing temperature, and has a turning point at 590 ℃, which is similar to that of NiFe2 O4 ceramic. The sintering temperature and adding modes of metallic elements have a great influence on the properties of 4. 25Cu-0. 75Ni/NiFe2O4 cermets. When the sintering temperature increases from 1 200 ℃ to 1 300 ℃, the relative density increases from 89.86% to 95.33 %0, and the resistivity at 960 ℃ decreases and Ni, the cermets of finely and uniformly dispersed metallic phase, high density and electric conductivity are obples sintered at 1 200 ℃ for 2 h, which are both better than those of the cermets prepared under the same technique conditions but with the metallic elements added as 85Cu-15Ni alloy powders.

  20. Zr-ZrO sub 2 cermet solar coatings designed by modelling calculations and deposited by dc magnetron sputtering

    CERN Document Server

    Zhang Qi Chu; Lee, K D; Shen, Y G

    2003-01-01

    High solar performance Zr-ZrO sub 2 cermet solar coatings were designed using a numerical computer model and deposited experimentally. The layer thickness and Zr metal volume fraction for the Zr-ZrO sub 2 cermet solar selective coatings on a Zr or Al reflector with a surface ZrO sub 2 or Al sub 2 O sub 3 anti-reflection layer were optimized to achieve maximum photo-thermal conversion efficiency at 80 deg. C under concentration factors of 1-20 using the downhill simplex method in multi-dimensions in the numerical calculation. The dielectric function and the complex refractive index of Zr-ZrO sub 2 cermet materials were calculated using Sheng's approximation. Optimization calculations show that Al sub 2 O sub 3 /Zr-ZrO sub 2 /Al solar coatings with two cermet layers and three cermet layers have nearly identical solar absorptance, emittance and photo-thermal conversion efficiency that are much better than those for films with one cermet layer. The optimized Al sub 2 O sub 3 /Zr-ZrO sub 2 /Al solar coating film w...

  1. An Overview of Current and Past W-UO[2] CERMET Fuel Fabrication Technology

    Energy Technology Data Exchange (ETDEWEB)

    Douglas E. Burkes; Daniel M. Wachs; James E. Werner; Steven D. Howe

    2007-06-01

    Studies dating back to the late 1940s performed by a number of different organizations and laboratories have established the major advantages of Nuclear Thermal Propulsion (NTP) systems, particularly for manned missions. A number of NTP projects have been initiated since this time; none have had any sustained fuel development work that appreciably contributed to fuel fabrication or performance data from this era. As interest in these missions returns and previous space nuclear power researchers begin to retire, fuel fabrication technologies must be revisited, so that established technologies can be transferred to young researchers seamlessly and updated, more advanced processes can be employed to develop successful NTP fuels. CERMET fuels, specifically W-UO2, are of particular interest to the next generation NTP plans since these fuels have shown significant advantages over other fuel types, such as relatively high burnup, no significant failures under severe transient conditions, capability of accommodating a large fission product inventory during irradiation and compatibility with flowing hot hydrogen. Examples of previous fabrication routes involved with CERMET fuels include hot isostatic pressing (HIPing) and press and sinter, whereas newer technologies, such as spark plasma sintering, combustion synthesis and microsphere fabrication might be well suited to produce high quality, effective fuel elements. These advanced technologies may address common issues with CERMET fuels, such as grain growth, ductile to brittle transition temperature and UO2 stoichiometry, more effectively than the commonly accepted ‘traditional’ fabrication routes. Bonding of fuel elements, especially if the fabrication process demands production of smaller element segments, must be investigated. Advanced brazing techniques and compounds are now available that could produce a higher quality bond segment with increased ease in joining. This paper will briefly address the history of

  2. Effects of metal binder on the microstructure and mechanical properties of Ti(C,N)-based cermets

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Qingzhong; Ai, Xing, E-mail: aixingsdu@163.com; Zhao, Jun; Gong, Feng; Pang, Jiming; Wang, Yintao

    2015-09-25

    Highlights: • Ni–Co binder improves the solid solution reaction and the wetting of hard phases. • Cermets with 25 wt.% binder have evenly distributed grains with moderate rims. • Co/(Ni + Co) ratios influence the grain sizes and microstructure features of cermets. • The cermets with pure Co as binder exhibit optimal mechanical properties. - Abstract: To optimize the mechanical properties of Ti(C,N)-based cermets used as tool materials, the cermets with different Ni–Co binder contents and Co/(Ni + Co) weight ratios were prepared. The effects of metal binder content and Co/(Ni + Co) ratio on the microstructure and mechanical properties of Ti(C,N)-based cermets were investigated by scanning electron microscope (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and measuring the transverse rupture strength (TRS), Vickers hardness (HV) and fracture toughness (K{sub IC}). The experimental results reveal that increasing Ni–Co binder content can increase the thickness of rim phases by improving the solid solution reaction and the wetting of hard phases. The cermets with 25 wt.% binder addition present good comprehensive mechanical properties, which is attributed to the moderate rim phases and uniformly distributed Ti(C,N) grains. The Co/(Ni + Co) weight ratios in binder have a great influence on the grain sizes and microstructure features of Ti(C,N)-based cermets, in virtue of the synergic effects between the wettability of Co and the solubilizing capacity of Ni on hard phases. The cermets with pure Co as binder exhibit optimal mechanical properties with a TRS of 1767 ± 81 MPa, a hardness of 12.26 ± 0.10 GPa and a K{sub IC} of 8.40 ± 0.47 MPa m{sup 1/2}, which meet the requirements for tool materials. And the cermets with a Co/(Ni + Co) ratio of 0.2 have the second best mechanical properties with a TRS of 1848 ± 201 MPa, a hardness of 11.12 ± 0.40 GPa and a K{sub IC} of 9.43 ± 0.54 MPa m{sup 1/2}, in which the lower hardness can

  3. Lateral stress evolution in chromium sulfide cermets with varying excess chromium

    Science.gov (United States)

    Petel, O. E.; Appleby-Thomas, G. J.; Wood, D. C.; Capozzi, A.; Nabavi, A.; Goroshin, S.; Frost, D. L.; Hazell, P. J.

    2016-04-01

    The shock response of chromium sulfide-chromium, a cermet of potential interest as a matrix material for ballistic applications, has been investigated at two molar ratios. Using a combustion synthesis technique allowed for control of the molar ratio of the material, which was investigated under near-stoichiometric (cermet) and excess chromium (interpenetrating composite) conditions, representing chromium:sulfur molar ratios of 1.15:1 and 4:1, respectively. The compacts were investigated via the plate-impact technique, which allowed the material to be loaded under a one-dimensional state of strain. Embedded manganin stress gauges were employed to monitor the temporal evolution of longitudinal and lateral components of stress in both materials. Comparison of these two components has allowed assessment of the variation of material shear strength both with impact pressure/strain-rate and time for the two molar ratio conditions. The two materials exhibited identical material strength despite variations in their excess chromium contents.

  4. Dynamic SEM wear studies of tungsten carbide cermets. [friction and wear experiments

    Science.gov (United States)

    Brainard, W. A.; Buckley, D. H.

    1975-01-01

    Dynamic friction and wear experiments were conducted in a scanning electron microscope. The wear behavior of pure tungsten carbide and composite with 6 and 15 weight percent cobalt binder was examined, and etching of the binder was done to selectively determine the role of the binder in the wear process. Dynamic experiments were conducted as the tungsten carbide (WC) and bonded WC cermet surfaces were transversed by a 50 micron radiused diamond stylus. These studies show that the predominant wear process in WC is fracture initiated by plastic deformation, and the wear of the etched cermets is similar to pure WC. The presence of the cobalt binder reduces both friction and wear. The cementing action of the cobalt reduces granular separation, and promotes a dense polished layer because of its low shear strength film-forming properties. The wear debris generated from unetched surface is approximately the same composition as the bulk.

  5. Effect of air plasma spraying parameters on WC-Co cermet coating

    International Nuclear Information System (INIS)

    WC-Co cermet coatings were produced on AISI 321 stainless steel samples by air plasma spraying system. In this regard, the coatings were deposited by varying the spraying distance i.e. 80 mm and 100 mm. It was observed that spraying distance play an important role on the final properties of the WC-Co cermet coating. The coatings were characterized by optical and electron microscopy, microhardness testing and X-Ray Diffractometry. A remarkable micro-structural difference was observed between the two coatings. It was observed that the coatings produced at 80 mm having more porosity and un-melted particles as compared to that produced at higher distance. Similarly, the change in concentration of metallurgical phases was also observed. (author)

  6. Structure and mechanical properties of plasma WC-Co cermet coatings

    International Nuclear Information System (INIS)

    A comparative analysis of phase compositions and microhardness values of WC-Co cermet coatings produced by plasma and high-speed gas-flame spraying has been carried out. It was shown that WC carbide and all type tungsten carbides content in the coatings rise up to 52 and 80% respectively when the plasma flow temperature is decreased. Microhardness of sprayed particles takes a value of 22 GPa while that of initial powder is 23 GPa

  7. Submersion criticality safety of tungsten-rhenium urania cermet fuel for space propulsion and power applications

    Energy Technology Data Exchange (ETDEWEB)

    Craft, A.E., E-mail: aaron.craft@inl.gov [Center for Space Nuclear Research (CSNR), INL, Idaho Falls, ID (United States); O’Brien, R.C., E-mail: Robert.OBrien@inl.gov [Center for Space Nuclear Research (CSNR), INL, Idaho Falls, ID (United States); Howe, S.D., E-mail: Steven.Howe@inl.gov [Center for Space Nuclear Research (CSNR), INL, Idaho Falls, ID (United States); King, J.C., E-mail: kingjc@mines.edu [Nuclear Science and Engineering Program, Metallurgical and Materials Engineering Department, Colorado School of Mines, Golden, CO 80401 (United States)

    2014-07-01

    Highlights: • Criticality safety studies consider a generic space nuclear reactor in reentry scenarios. • Describes the submersion criticality behavior for a reactor fueled with a tungsten cermet fuel. • Study considers effects of varying fuel content, geometry, and other conditions. - Abstract: Nuclear thermal rockets are the preferred propulsion technology for a manned mission to Mars, and tungsten–uranium oxide cermet fuels could provide significant performance and cost advantages for nuclear thermal rockets. A nuclear reactor intended for use in space must remain subcritical before and during launch, and must remain subcritical in launch abort scenarios where the reactor falls back to Earth and becomes submerged in terrestrial materials (including seawater, wet sand, or dry sand). Submersion increases reflection of neutrons and also thermalizes the neutron spectrum, which typically increases the reactivity of the core. This effect is typically very significant for compact, fast-spectrum reactors. This paper provides a submersion criticality safety analysis for a representative tungsten/uranium oxide fueled reactor with a range of fuel compositions. Each submersion case considers both the rhenium content in the matrix alloy and the uranium oxide volume fraction in the cermet. The inclusion of rhenium significantly improves the submersion criticality safety of the reactor. While increased uranium oxide content increases the reactivity of the core, it does not significantly affect the submersion behavior of the reactor. There is no significant difference in submersion behavior between reactors with rhenium distributed within the cermet matrix and reactors with a rhenium clad in the coolant channels. The combination of the flooding of the coolant channels in submersion scenarios and the presence of a significant amount of spectral shift absorbers (i.e. high rhenium concentration) further decreases reactivity for short reactor cores compared to longer cores.

  8. Metal-Matrix Hardmetal/Cermet Reinforced Composite Powders for Thermal Spray

    Directory of Open Access Journals (Sweden)

    Dmitri GOLJANDIN

    2012-03-01

    Full Text Available Recycling of materials is becoming increasingly important as industry response to public demands, that resources must be preserved and environment protected. To produce materials competitive in cost with primary product, secondary producers have to pursue new technologies and other innovations. For these purposes different recycling technologies for composite materials (oxidation, milling, remelting etc are widely used. The current paper studies hardmetal/cermet powders produced by mechanical milling technology. The following composite materials were studied: Cr3C2-Ni cermets and WC-Co hardmetal. Different disintegrator milling systems for production of powders with determined size and shape were used. Chemical composition of produced powders was analysed.  To estimate the properties of recycled hardmetal/cermet powders, sieving analysis, laser granulometry and angularity study were conducted. To describe the angularity of milled powders, spike parameter–quadric fit (SPQ was used and experiments for determination of SPQ sensitivity and precision to characterize particles angularity were performed. Images used for calculating SPQ were taken by SEM processed with Omnimet Image Analyser 22. The graphs of grindability and angularity were composed. Composite powders based on Fe- and Ni-self-fluxing alloys for thermal spray (plasma and HVOF were produced. Technological properties of powders and properties of thermal sprayed coatings from studied powders were investigated. The properties of spray powders reinforced with recycled hardmetal and cermet particles as alternatives for cost-sensitive applications were demonstrated.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1348

  9. Development of mixed conducting dense nickel/Ca-doped lanthanum zirconate cermet for gas separation application

    Energy Technology Data Exchange (ETDEWEB)

    Nag, S. [CSIR - Central Glass and Ceramic Research Institute, 196 Raja S. C. Mullick Road, Kolkata - 700 032 (India); Mukhopadhyay, S. [Department of Chemical Technology, Calcutta University, 92 A. P. C. Road, Kolkata - 700 009 (India); Basu, R.N., E-mail: rajenbasu54@gmail.com [CSIR - Central Glass and Ceramic Research Institute, 196 Raja S. C. Mullick Road, Kolkata - 700 032 (India)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Phase pure La{sub 1.95}Ca{sub 0.05}Zr{sub 2}O{sub 7-{delta}} (LCZ) material is prepared by combustion synthesis. Black-Right-Pointing-Pointer LCZ and Ni-LCZ bulk samples are prepared with theoretical density close to 100%. Black-Right-Pointing-Pointer Bulk electrical conductivity {approx}400 S/cm is obtained for Ni-LCZ cermet at 750 Degree-Sign C. -- Abstract: La{sub 1.95}Ca{sub 0.05}Zr{sub 2}O{sub 7-{delta}} (LCZ) and Ni-LCZ cermet have been prepared by combustion synthesis and conventional solid state mixing methods respectively. Both the materials are sintered in air and controlled atmosphere (5% H{sub 2} in Ar). The density obtained for the material sintered at 1400 Degree-Sign C in controlled atmosphere is found to be more than 99.5%. This sintering temperature (1400 Degree-Sign C) is considered to be much lower compared to the conventional sintering temperature. The corresponding total conductivity for such Ni-LCZ cermet materials is {approx}400 S/cm measured at 750 Degree-Sign C having 40 vol% of Ni and 60 vol% LCZ.

  10. Densification of Ni-NiFe2O4 cermets for aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    LAI Yan-qing; SUN Xiao-gang; LI Jie; DUAN Hua-nan; LI Xin-zheng; ZHANG Gang; TIAN Zhong-liang

    2005-01-01

    The density of cermet inert anodes in aluminum electrolysis is of great importance. Ni-NiFe2 O4 cermetswere studied with respect to their densification affected by ball milling time, particle size of raw powders, contentsof metallic phase, sintering atmosphere and temperature. The results show that, prolonging ball milling time willincrease the density with the optimum value of 150 min; cermets containing 0 - 15 %Ni(mass fraction) have high rel-ative density ranging from 94% to 96%, but with Ni content increasing, the density slightly decreases; weak reduc-tive atmosphere is favorable to densification; the relative density increases from 80.38% to 96.85% with the sinte-ring temperature increasing from 1 100 ℃ to 1 300 ℃ while it decreases at 1 400 ℃, which may be due to crystalgrain coarsening. So the sintering temperature of Ni-NiFe2 O4 cermets in current work should be controlled at 1 300℃, where the relative density is 96.85%.

  11. Repository Criticality Control with Depleted-Uranium-Dioxide Cermet Waste Packages

    International Nuclear Information System (INIS)

    It is proposed that the structural components and internal basket structures of waste packages (WPs) be constructed of depleted uranium dioxide (DUO2)-steel cermets. The cermet contains 2 DUO2 imbedded in a steel matrix. The WPs are filled with spent nuclear fuel (SNF) and placed 2 in a geological repository. The WP provides a handling container for placement of SNF in the repository and is an engineered barrier to delay SNF degradation and subsequent release of radionuclides. SNF and other fissile wastes contain enriched uranium and transuranic fissile isotopes; thus, the potential for nuclear criticality exists. Most of the transuranic fissile isotopes, such as 239Pu, will have decayed to 233U or 235U before significant fissile-isotope migration from the degraded SNF or other fissile waste forms has occurred. Consequently, post-closure repository criticality issues are primarily from the fissile isotopes of uranium. As the WP degrades, the 238U in the DUO2-steel cermet would mix with the degrading SNF and isotopically dilute 233U and 235U to levels that would ensure that post-closure criticality would not occur

  12. Grain size stabilization of tetragonal phase of zirconia in sputtered Zr- O cermet films

    Directory of Open Access Journals (Sweden)

    M. S. Hadavi

    2005-06-01

    Full Text Available  In this research, thin films of Zr/ZrO2 composites were deposited by reactive magnetron sputtering technique on Si and fused Silica substrates, and their structures were investigated by XRD method. During the deposition of the cermet layers, a Zr metallic target was sputtered in a gas mixture of Ar and O2. By controlling of O2 flow rate, the different metal volume fractions in the cermet layers were achieved. The optical response of the samples was studied using spectroscopy methods. Also the effect of vacuum annealing on the structures and the optical properties were studied. XRD results indicated that the prepared samples were amorphous and vacuum annealing induced crystallization in the cermet films. This research also showed that without doping, the tetragonal phase of zirconia can be stabilized at a temperature lower than the normal transition temperature. This is “grain size stabilization” and relates to the small size of the crystallites. In order to study the electron diffraction in the selected area patterns (SAD, the samples were analyzed by a high-resolution transmission microscope. The SAD results showed that all of the as prepared samples were amorphous showing evidence of very small Zr crystallites immersed in a dielectric medium.The SAD results are in close agreement with those obtained by XRD analysis.

  13. Submersion criticality safety of tungsten-rhenium urania cermet fuel for space propulsion and power applications

    Energy Technology Data Exchange (ETDEWEB)

    A.E. Craft; R. C. O' Brien; S. D. Howe; J. C. King

    2014-07-01

    Nuclear thermal rockets are the preferred propulsion technology for a manned mission to Mars, and tungsten–uranium oxide cermet fuels could provide significant performance and cost advantages for nuclear thermal rockets. A nuclear reactor intended for use in space must remain subcritical before and during launch, and must remain subcritical in launch abort scenarios where the reactor falls back to Earth and becomes submerged in terrestrial materials (including seawater, wet sand, or dry sand). Submersion increases reflection of neutrons and also thermalizes the neutron spectrum, which typically increases the reactivity of the core. This effect is typically very significant for compact, fast-spectrum reactors. This paper provides a submersion criticality safety analysis for a representative tungsten/uranium oxide fueled reactor with a range of fuel compositions. Each submersion case considers both the rhenium content in the matrix alloy and the uranium oxide volume fraction in the cermet. The inclusion of rhenium significantly improves the submersion criticality safety of the reactor. While increased uranium oxide content increases the reactivity of the core, it does not significantly affect the submersion behavior of the reactor. There is no significant difference in submersion behavior between reactors with rhenium distributed within the cermet matrix and reactors with a rhenium clad in the coolant channels. The combination of the flooding of the coolant channels in submersion scenarios and the presence of a significant amount of spectral shift absorbers (i.e. high rhenium concentration) further decreases reactivity for short reactor cores compared to longer cores.

  14. TiC/Fe cermet coating by plasma cladding using asphalt as a carbonaceous precursor

    Institute of Scientific and Technical Information of China (English)

    Junbo Liu

    2008-01-01

    A new Ti-Fe-C compound powder for plasma cladding was prepared by heating a mixture powder of ferrotitanium and asphalt pyro-lyzed as a carbonaceous precursor. The carbon by the pyrolysis of the asphalt acts as a reactive constituent as well as a binder in the compound powder. The TiC/Fe cermet coatings were prepared by plasma cladding with the compound powder. Results show that the Ti-Fe-C compound powder has a very tight structure, which can avoid the problem of the reactive constituent particles being separated during cladding. The TiC/Fe cermet coating presents a typical morphology of plasma cladding coatings with two different laminated layers: one is the composite layer in which the round fine TiC particles (<500 nm) are dispersed within a Fe matrix, the other is the paragentic layer of TiC and Ti2O3. The coating shows high hardness and excellent wear resistance. The surface hardness of the coating is 68 ± 5(HR30N). In the same fretting conditions, the wear area of Ni60 coating is about 11 times as much as the TiC/Fe cermet coating.

  15. Microstructure and mechanical properties of hot isostatically pressed cermets with TiN coatings

    Institute of Scientific and Technical Information of China (English)

    ZHENG Liyun; XIONG Weihao; YAN Xianmei; LI Guo'an

    2006-01-01

    To increase the adhesion strength between the coating and the substrate, sintered Ti(C,N)-based cermets were selected and deposited with monolayer TiN using a multiarc ion-plating technique; subsequently, hot isostatic pressing (HIPing) treatment was performed at 1000℃ using nitrogen pressure up to 110 MPa. The mechanical properties of cermets after a coating process and subsequent HIPing treatment have been evaluated with respect to the hardness, the residual stress, and the coating adhesion. The results show that after the HIPing process, there was a higher increase in critical load in the TiN-coated cermets with lower surface roughness compared with those with higher surface roughness. In all cases, the residual stress was found to be compressive. The effects of substrate surface roughness and posttreatment on the adhesion strength of the coatings were thus investigated. It was also found that the HIPing posttreatment process is well suited for increasing the adhesion strength between the coating and the substrate.

  16. Wear Resistant Thermal Sprayed Composite Coatings Based on Iron Self-Fluxing Alloy and Recycled Cermet Powders

    Directory of Open Access Journals (Sweden)

    Heikki SARJAS

    2012-03-01

    Full Text Available Thermal spray and WC-Co based coatings are widely used in areas subjected to abrasive wear. Commercial  cermet thermal spray powders for HVOF are relatively expensive. Therefore applying these powders in cost-sensitive areas like mining and agriculture are hindered. Nowadays, the use of cheap iron based self-fluxing alloy powders for thermal spray is limited. The aim of this research was to study properties of composite powders based on self-fluxing alloys and recycled cermets and to examine the properties of thermally sprayed (HVOF coatings from composite powders based on iron self-fluxing alloy and recycled cermet powders (Cr3C2-Ni and WC-Co. To estimate the properties of  recycled cermet powders, the sieving analysis, laser granulometry and morphology were conducted. For deposition of coatings High Velocity Oxy-Fuel spray was used. The structure and composition of powders and coatings were estimated by SEM and XRD methods. Abrasive wear performance of coatings was determined and compared with wear resistance of coatings from commercial powders. The wear resistance of thermal sprayed coatings from self-fluxing alloy and recycled cermet powders at abrasion is comparable with wear resistance of coatings from commercial expensive spray powders and may be an alternative in tribological applications in cost-sensitive areas.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1338

  17. Research on the cutting performance and the wear mechanism of the cermet cutter in high speed turn-milling

    Institute of Scientific and Technical Information of China (English)

    JIA Chun-de; HUANG Shu-tiao; JIANG Zeng-hui; ZHANG Zhi-jun; SHI Li

    2005-01-01

    When machining D60 steel by high speed turn-milling under the different cooling and lubricating conditions, the cutting performance and the wear mechanism of the cermet cutter are researched. With water soluble cooling fluid, the wear performance of the cermet cutter is bad, and does not adapt to the requirements of machining. However, when machining D60 by high speed turn-milling is under dry conditions, the wearing performance of the cermet cutter is very good and the cutting time lasts almost 3 hours. The wear mechanism of the cermet cutter under the water soluble cooling fluid is different from the dry condition. With the water soluble cooling fluid, a great deal of little chap units are formed since high frequency alternates heat stress. The crash and desquamate of these chap units is the main cause of the cutter wearing. Under dry cutting conditions, it is the main cause of cermet cutter wear in the felting phase intenerating causing rigid phase grains to fall.

  18. Working of Mo-TiC cermets for 'future nuclear systems'; Mise en forme de cermets Mo-TiC pour les 'Systemes Nucleaires du futur'

    Energy Technology Data Exchange (ETDEWEB)

    Allemand, Alexandre [CEA-Saclay, DRT/LITEN/LTMEx, 91191 Gif-sur-Yvette (France); Le Flem, Marion [CEA-Saclay, DEN/DMN/SRMA, 91191 Gif-sur-Yvette (France); Rousselet, Jerome [UTT Troyes, 10010 Troyes (France)

    2006-07-01

    The nuclear reactor cores (generation IV) will form an extremely severe environment (high temperature, severe and long irradiation...). These drastic criteria and the preoccupation to ensure a higher and higher safety level lead, beyond the preoccupations due to the feasibility of such reactors, to harsh choices in materials able to be used. Innovating materials such as Mo-TiC cermet are the subject of intense researches in the CEA. This study presents and compares two modes of Mo-TiC cermet working: the hot isostatic compression and the extrusion. Different compositions of Mo-TiC cermets are prepared by hot isostatic compression and extrusion, and then characterized in term of microstructural properties. At last, this study concludes to a very satisfying working by hot isostatic compression, nevertheless the extrusion has still to be improved. (O.M.)

  19. Effect of metallic phase species on the corrosion resistance of M/(10NiO-NiFe2O4) cermet inert anode of aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    NiFe2O4-based cermet inert anodes with metallic phase compositions of Cu, Ni and 85Cu15Ni were prepared by cold pressing-sintering. Their corrosion resistance was also investigated in Na3 AlF6-Al2 O3 melts. The results show that the metallic phase species in cermets have no effect on the concentration of impurities in bath during electrolysis, the total steady-state concentration of impurities is almost the same, I.e. Between 4.12 × 10-4- 4.80 × 10-4. There exists metal preferential corrosion for the cermet inert anode with metal Ni as metallic phase. For NiFe2 O4-based cermets, the cermet with metal Cu as metallic phase exhibits better corrosion resistance than the others.

  20. Spark Plasma Sintering of Load-Bearing Iron-Carbon Nanotube-Tricalcium Phosphate CerMets for Orthopaedic Applications

    Science.gov (United States)

    Montufar, Edgar B.; Horynová, Miroslava; Casas-Luna, Mariano; Diaz-de-la-Torre, Sebastián; Celko, Ladislav; Klakurková, Lenka; Spotz, Zdenek; Diéguez-Trejo, Guillermo; Fohlerová, Zdenka; Dvorak, Karel; Zikmund, Tomáš; Kaiser, Jozef

    2016-04-01

    Recently, ceramic-metallic composite materials (CerMets) have been investigated for orthopaedic applications with promising results. This first generation of bio-CerMets combine the bioactivity of hydroxyapatite with the mechanical stability of titanium to fabricate bioactive, tough and biomechanically more biocompatible osteosynthetic devices. Nonetheless, these first CerMets are not biodegradable materials and a second surgery is required to remove the implant after bone healing. The present work aims to develop the next generation bio-CerMets, which are potential biodegradable materials. The process to produce the new biodegradable CerMet consisted of mixing powder of soluble and osteoconductive alpha tricalcium phosphate with biocompatible and biodegradable iron with consolidation through spark plasma sintering (SPS). The microstructure, composition and mechanical strength of the new CerMet were studied by metallography, x-ray diffraction and diametral tensile strength tests, respectively. The results show that SPS produces CerMet with higher mechanical performance (120 MPa) than the ceramic component alone (29 MPa) and similar mechanical strength to the pure metallic component (129 MPa). Nonetheless, although a short sintering time (10 min) was used, partial transformation of the alpha tricalcium phosphate into its allotropic and slightly less soluble beta phase was observed. Cell adhesion tests show that osteoblasts are able to attach to the CerMet surface, presenting spread morphology regardless of the component of the material with which they are in contact. However, the degradation process restricted to the small volume of the cell culture well quickly reduces the osteoblast viability.

  1. Microstructure and optical absorption of Au-MgF2 nanoparticle cermet films

    Institute of Scientific and Technical Information of China (English)

    Sun Zhao-Qi; Cai Qi; Song Xue-Ping

    2006-01-01

    The microstructure and optical absorption of Au-MgF2 nanoparticle cermet films with different Au contents are studied.The microstructural analysis shows that the films are mainly composed of the amorphous MgF2 matrix with embedded fcc Au nanoparticles with a mean size of 9.8-21.4nm.Spectral analysis suggests that the surface plasma resonance (SPR) absorption peak of Au particles appears at λ=492-537nm.With increasing Au content,absorption peak intensity increases,profile narrows and location redshifts.Theoretical absorption spectra are calculated based on Maxwell-Garnett theory and compared with experimental spectra.

  2. Plasma cermet WC-Co coatings hardened by micro- and nanosized carbides

    International Nuclear Information System (INIS)

    Significant changes of the structure and phase composition of formed cermet WC-Co coatings are possible under plasma spraying of mechanically alloyed nano- and micro-sized powders. WC carbide content can be lowered from 43.9% in initial powder to 3.8% in coating. During deposition process, intense formation of non-equilibrium phases takes place which are fixed in the coating at quenching from a liquid state at cooling rate of 108 K/s. In spite of the changes of phase composition of WC-Co hard alloy, inner bulk of sprayed particles has a high (15-23 GPa) value of microhardness

  3. Nondestructive evaluation of a cermet coating using ultrasonic and eddy current techniques

    International Nuclear Information System (INIS)

    This paper describes a series of experiments conducted to characterize cermet coatings using conventional ultrasonic and eddy current techniques as well as an ultrasonic leaky surface wave method. The results demonstrate the ability of these techniques to detect the presence of artificial defects on the surface or beneath the surface of the coating. In addition, ultrasonic tests in particular ultrasonic leaky surface waves demonstrate the ability to detect the presence of manufacturing flaws. Ultrasonic time-of-flight and eddy current quadrature measurements also show sensitivity to variations in coating thickness

  4. Methods of three-dimensional electrophoretic deposition for ceramic and cermet applications and systems thereof

    Energy Technology Data Exchange (ETDEWEB)

    Rose, Klint Aaron; Kuntz, Joshua D.; Worsley, Marcus

    2016-09-27

    A ceramic, metal, or cermet according to one embodiment includes a first layer having a gradient in composition, microstructure and/or density in an x-y plane oriented parallel to a plane of deposition of the first layer. A ceramic according to another embodiment includes a plurality of layers comprising particles of a non-cubic material, wherein each layer is characterized by the particles of the non-cubic material being aligned in a common direction. Additional products and methods are also disclosed.

  5. The anomalous behaviour of Ag-Al2O3 Cermet electroformed devices

    International Nuclear Information System (INIS)

    Cermet coating consisting of silver particles in an aluminium oxide matrix were prepared on glass substrates by vacuum deposition. Variation of the circulating current with potential difference was obtained in evaporated Al/Ag-Al2O3/Cu sandwich structures, 100 to 200 nm thick containing 10 wt % Ag. It was observed that the investigated sandwich structures exhibit anomalous behaviour such as electroforming with Voltage-Controlled-Negative Resistance (VCNR) in vacuo of ∼ 4 x 10-6 torr. The formed characteristics were explained on the basis of filamentary model. (author)

  6. Influence of characteristics of stabilized zirconia electrolyte on performance of cermet supported tubular SOFCs

    Institute of Scientific and Technical Information of China (English)

    LI Changjiu; LI Chengxin; XING Yazhe; XIE Yingxin; LONG Huiguo

    2006-01-01

    Ni-Al2O3 cermet supported tubular SOFC was fabricated by thermal spraying. Flame-sprayed Al2O3-Ni cermet coating plays dual roles of a support tube and an anode current collector. 4.5mol.% yttria-stabilized zirconia (YSZ) and 10mol.% scandia-stabilized zirconia (ScSZ) coatings were deposited by atmospheric plasma spraying (APS) as the electrolyte in present study. The electrical conductivity of electrolyte was measured using DC method. The post treatment was employed using nitrate solution infiltration to densify APS electrolyte layer for improvement of gas permeability. The electrical conductivity of electrolyte and the performance of single cell were investigated to optimize SOFC performance. The electrical conductivity of the as-sprayed YSZ and ScSZ coating is about 0.03 and 0.07 S·cm-1 at 1000 ℃, respectively. The ohmic polarization significantly influences the performance of SOFC. The maximum output power density at 1000 ℃ increases from 0.47 to 0.76 W·cm-2 as the YSZ electrolyte thickness reduces from 100 μm to 40 μm. Using APS ScSZ coating of about 40 μm as the electrolyte, the test cell presents a maximum power output density of over 0.89 W·m-2 at 1000 ℃.

  7. Formation of layer-shaped pores in TiC-Fe cermet by combustion synthesis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    To study the formation of layer-shaped pores in TiC-Fe cermet, two Ti-C-Fe powder compacts containing Ti powders with two size ranges (<44?μm and 135~154?μm) respectively were ignited in a special ignition mode. The combustion temperatures of the reactions were measured, the phase constituents of the combustion-synthesized products were inspected by X-ray diffractometry (XRD), and the structures of the products were observed with scanning electron microscope (SEM). In the case of the finer Ti powder used, TiC-Fe cermet and pore rank in an alternately laminar shape, and the shape of the pore is the same as that of the combustion wavefront, implying that the layer-shaped pore results from a gather of the retained gas into the combustion wavefront. While in the case of the coarser Ti powder used, the lower combustion temperature causes the gather of the retained gas to be difficult, the pore being present in an arbitrary shape and distributing randomly.

  8. Electrical conductivity of Cu/(10NiO-NiFe2O4) cermet inert anode for aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Cu/(10NiO-NiFe2O4) cermets containing mass fractions of Cu of 5%, 10%, 15% and 20% were prepared, and their electrical conductivities were measured at different temperatures. The effects of temperature and content of metal Cu on the electrical conductivity were investigated especially. The results indicate that the metallic phase Cu distributes evenly in 10NiO-NiFe2O4 ceramic matrix. The mechanism of electrical conductivity of Cu/(10NiO-NiFe2O4) cermets obeys the rule of electrical mechanism of semiconductor, the electrical conductivity for cermet containing 5% Cu increases from 2.70 to 20.41 S/cm with temperature increasing from 200 to 900 ℃. The change trend of electrical conductivity with temperature is similar with each other and it increases with increasing temperature and content of metal Cu. At 960 ℃, the electrical conductivity of cermet increases from 2.88 to 82.65 S/cm with the content of metal Cu increasing from 0 to 20%.

  9. Advanced WC-Co cermet composites with reinforcement of TiCN prepared by extended thermal plasma route

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, B. [Centre for Advanced Materials Processing, Central Mechanical Engineering Research Institute, Mahatma Gandhi Avenue, Durgapur 713 209, West Bengal (India)], E-mail: bnmondal@rediffmail.com; Das, P.K. [Central Glass and Ceramic Research Institute, Kolkata (India); Singh, S.K. [Institute of Minerals and Materials Technology (IIMT), Bhubeneswar (India)

    2008-12-20

    The synthesis of titanium carbonitride (TiCN) powders by thermal plasma using extended arc thermal plasma reactor and the effect of TiCN reinforcement for the development of advanced WC-Co cermets has been studied with respect to hardness and fracture toughness. These classes of materials are being investigated for future application in wear-resistant seals, cutting tools, etc. Metallurgical reactions and microstructural developments during sintering of cermets and functionally graded cemented carbonitrides are being investigated by analytical methods such as differential thermal analysis/thermo-gravimetric analysis, X-ray diffraction and analytical Scanning electron microscopy with energy dispersive X-ray spectroscopy. By an in-depth understanding of the complex phase reactions and the mechanisms that govern the sintering process and metallurgical reactions, new cermets and different types of functionally graded cemented carbonitrides with desired microstructures and properties have been attempted to develop. The significant improvement of micro-hardness was observed with optimal concentration of TiCN reinforcement addition in WC-Co system without sacrificing much fracture toughness value of the composite cermets.

  10. Electrochemical behaviour of Ni-BZO and Ni-BZY cermet anodes for Protonic Ceramic Fuel Cells (PCFCs) – A comparative study

    International Nuclear Information System (INIS)

    Highlights: • Cermet anodes Ni-BaZrO3 (Ni-BZO) & Ni-BaZr0.85Y0.15O3-δ (Ni-BZY) were synthesised • Resultant microstructure of both cermet anodes shown to be similar • Minimum Rp in Ni-BZY in 10%H2/N2 with matrix phase of higher proton conductivity. • Strong links shown between R2 and proton conduction in cermet matrix phase. • Magnitude of R3 lower for Ni-BZO than for Ni-BZY under similar conditions. - Abstract: The matrix phase of protonic ceramic fuel cell (PCFC) cermet anodes potentially plays a vital role in hydrogen oxidation kinetics. The present work aims to investigate such involvement by selecting ceramic-oxide matrices with widely dissimilar levels of proton conduction. The materials chosen were that of the proton conducting phase BaZr0.85Y0.15O3-δ and the nominal composition BaZrO3 of negligible proton conduction. Cermet anodes Ni-BaZrO3 and Ni-BaZr0.85Y0.15O3-δ were synthesized by the acetate-H2O2 combustion method for Ni contents of 40 vol%. The microstructure and electrochemical performance of the cermet anodes were investigated by scanning electron microscopy (SEM) and electrochemical impedance measurements (EIS) respectively. The polarisation behaviour of the two nickel cermet anodes was studied as a function of temperature, hydrogen partial pressure (pH2) and water vapor partial pressure (pH2O). The results confirm that polarisation resistance is highly sensitive to the composition of the ceramic phase of the cermet anode and that the higher frequency electrode response exhibits strong links to levels of proton transport in the ceramic-oxide matrix

  11. Structure and properties of selected cemented carbides and cermets covered with TiN/(Ti,Al,Si)N/TiN coatings obtained by the cathodic arc evaporation process

    OpenAIRE

    Leszek A. Dobrzañski; Klaudiusz Golombek

    2005-01-01

    This study presents the results of microstructural examinations, mechanical tests and service performance tests carried out on thin TiN/(Ti,Al,Si)N/TiN wear resistance coatings obtained by the CAE process on cermet and cemented carbide substrates. Microstructural examinations of the applied coatings and the substrate were made with an OPTON DSM 940 SEM and a LEICA MEF4A light microscope. Adhesion of the coatings on cemented carbides and cermets was measured using the scratch test. The cutting...

  12. TiN+gradient or multi(Ti,Al,Si)N+TiN coatings deposited on cermets by CAE process: characteristic of structure and properties

    OpenAIRE

    L.A. Dobrzański; K. Gołombek

    2005-01-01

    Purpose: It has been demonstrated in the paper that deposition of the multilayer and gradient coatings with the PVD method in the Cathodic Arc Evaporation CAE process on tools made from cermets.Design/methodology/approach: Structural examinations are presented of the applied coatings and their substrate made on the TEM, SEM and on the light microscope. Evaluation of the adhesion of the deposited coatings onto the cermets was made using the scratch test. Cutting properties of the investigated ...

  13. Evaluation of fatigue strength of WC cermet- and 13Cr steel-sprayed materials; WC cermet oyobi 13Cr ko yosha hifukuzai no hiro kyodo hyoka

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, T.; Tokaji, K.; Ejima, T. [Gifu University, Gifu (Japan); Kobayashi, Y.; Harada, Y. [Tocalo Co. Ltd., Kobe (Japan)

    1997-10-15

    Rotating bending fatigue tests have been conducted at room temperature in air using the specimens of medium carbon steel (S45C), low alloy steel (SCM435) and titanium alloy (Ti-6Al-4V) with HVOF sprayed coating of a cermet (WC-12%Co) and S45C with WFS sprayed coating of a 13Cr steel (SUS420 J2). The fatigue strength and fracture mechanisms were studied. The fatigue strength evaluated by nominal stress was strongly influenced by substrate materials and the thickness of sprayed coatings. Detailed observation of crack initiation on the coating surface and fracture surface revealed that microcracks initiated at the WC grain boundary coalesced, and then the crack grew rapidly in the coating. Cracks in the substrate were initiated by the stress concentration of the crack in the coating, which was modeled by finite element analysis. For the specimens tested in this study, the fatigue strength of sprayed specimens was dominated by that of sprayed coating. Thus, the fatigue strength could be evaluated uniquely by the true stress on the coating surface. 9 refs., 12 figs., 2 tabs.

  14. The Influence of Cr3C2 and VC as Alloying Additives on the Microstructure and Properties of Reactive Sintered WC-Co Cermets

    Directory of Open Access Journals (Sweden)

    Kristjan JUHANI

    2012-03-01

    Full Text Available Investigated WC-Co cermets were produced via reactive sintering. In case of reactive sintering the elemental powders of tungsten, carbon black as graphite source and cobalt at first activated throw high energy milling and then the carbide synthesis is taking place in the same cycle with liquid phase sintering of the cermets. Because there is a lack of information about the influence of alloying additives on the reactive sintered WC-Co cermets, small amount of chromium carbide or vanadium carbide was added to the powders. To investigate the influence of carbon content in initial powder mixture on the microstructure and properties of reactive sintered WC-Co cermets alloyed with Cr3C2 and VC cermets with different carbon content were produced. The hardness, transverse rupture strength and erosion resistance of alloyed WC-Co cermets depending on carbon content in initial powder mixture is exhibited.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1347

  15. Faradaic current in different mullite materials. Single crystal, ceramic and cermets

    Energy Technology Data Exchange (ETDEWEB)

    Mata-Osoro, Gustavo; Moya, Jose S.; Pecharroman, Carlos [Instituto de Ciencia de Materiales de Madrid (CSIC) (Spain); Morales, Miguel [Universidad de Santiago de Compostela (Spain). LabCaF; Diaz, L. Antonio [Centro de Investigacion en Nanomateriales y Nanotecnologia (CINN-CSIC), Llanera (Spain); Schneider, Hartmut [Koeln Univ. (Germany). Inst. fuer Kristallographie

    2012-04-15

    Faradaic current measurements have been carried out on three different types of mullite: 2: 1 mullite single crystals (E perpendicular to c), 3: 2 ceramics and 11 % mullite/Mo composites. Measurements were carried out on very thin samples (60 {mu}m) at high voltages (500 to 1 000 V). Under these conditions, measurable currents were recorded even at room temperature. Results indicate notable differences between these three samples, which suggest that, although they share the same name and similar crystalline structure, binding energies and defect distributions seem to be very different. Finally, it has been seen that the excellent behaviour against dielectric breakdown of ceramic mullite does not hold for single crystals or mullite based cermets. (orig.)

  16. A Comparison of Materials Issues for Cermet and Graphite-Based NTP Fuels

    Science.gov (United States)

    Stewart, Mark E.; Schnitzler, Bruce G.

    2013-01-01

    This paper compares material issues for cermet and graphite fuel elements. In particular, two issues in NTP fuel element performance are considered here: ductile to brittle transition in relation to crack propagation, and orificing individual coolant channels in fuel elements. Their relevance to fuel element performance is supported by considering material properties, experimental data, and results from multidisciplinary fluid/thermal/structural simulations. Ductile to brittle transition results in a fuel element region prone to brittle fracture under stress, while outside this region, stresses lead to deformation and resilience under stress. Poor coolant distribution between fuel element channels can increase stresses in certain channels. NERVA fuel element experimental results are consistent with this interpretation. An understanding of these mechanisms will help interpret fuel element testing results.

  17. Methods of characterization of the binder phase in WC-Co cermets

    International Nuclear Information System (INIS)

    In technological application of cermets carbides are sintered with so-called binder metals Co and Ni. It is supposed that relevant properties are dependent on the partial solution of carbides and carbon in the binder. In thepresent work alloys W-Co-C were produced with more than 850Co to simulate the binder phase of the technological material, solution treated at 1300K, 1400K and 1500K, and saturation magnetisation plus the lattice parameter of the cubic Co determined. The corresponding property curves show breaks at the solubility limits. In the solubility regions the content dependence of the two properties were fitted to certain expressions. Whereas the W dependence is well-known from the literature the present work show als a significant C dependence. (G.Q.)

  18. Design Evolutuion of Hot Isotatic Press Cans for NTP Cermet Fuel Fabrication

    Science.gov (United States)

    Mireles, O. R.; Broadway, J.; Hickman, R.

    2014-01-01

    Nuclear Thermal Propulsion (NTP) is under consideration for potential use in deep space exploration missions due to desirable performance properties such as a high specific impulse (> 850 seconds). Tungsten (W)-60vol%UO2 cermet fuel elements are under development, with efforts emphasizing fabrication, performance testing and process optimization to meet NTP service life requirements [1]. Fuel elements incorporate design features that provide redundant protection from crack initiation, crack propagation potentially resulting in hot hydrogen (H2) reduction of UO2 kernels. Fuel erosion and fission product retention barriers include W coated UO2 fuel kernels, W clad internal flow channels and fuel element external W clad resulting in a fully encapsulated fuel element design as shown.

  19. Microstructure and mechanical properties of WC-20wt% Co/ZrO2(3Y)cermet composites

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The cermet composites WC-20wt%Co/ZrO2(3Y) with four different contents of ZrO2(3Y) were prepared by normal vacuum sinter processing; the optical microscope and SEM were used to characterize their microstructures.The hardness, bending strength and impact toughness of the specimens were determined.The experimental results show that ZrO2(3Y) particles in WC-20wt%Co matrix are spherical particles in different sizes which are distributed uniformly in Co phases and WC phases, the bending strength and impact toughness of the WC-20wt%Co cermet composites added ZrO2(3Y) improve remarkably, but the hardness values have little change.

  20. Microstructure and cutting performance of Ti(C, N)-based cermets heat-treated in nitrogen

    Institute of Scientific and Technical Information of China (English)

    LIU Wenjun; XIONG Weihao; ZHENG Yong; SHI Zengmin; YE Jiajian

    2007-01-01

    Ti(C, N)-based cermets were treated using hot isostatic pressing (HIP) at 1423 K in nitrogen. The microstructures compared with the as-sintered cermets were investigated using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray analysis, and electron microprobe analysis. It was found that high nitrogen activity in the surface zone resulted in the formation of gradient structure. Approximately 20-μm-deep, nitrogen-rich and titanium-rich hard surface zone was introduced by the beat treatment. The nitrogen activity was the driving force that caused the transportation of the atoms through the binder, titanium towards the surface, and tungsten and molybdenum inwards. In the surface zone, the particle size became fine, the inner rim disappeared, and the volume fraction of the outer rim and the binder phase considerably reduced. Small grains of TiN, WC, Mo2C, and nitrogen-rich carbonitride phases formed in the surface zone during the heat treatment, improving the tribological property of the heat-treated cermet.

  1. Structural Characteristics and Magnetic Properties of Al2O3 Matrix-Based Co-Cermet Nanogranular Films

    Directory of Open Access Journals (Sweden)

    Giap Van Cuong

    2015-01-01

    Full Text Available Magnetic micro- and nanogranular materials prepared by different methods have been used widely in studies of magnetooptical response. However, among them there seems to be nothing about magnetic nanogranular thin films prepared by a rf cosputtering technique for both metals and insulators till now. This paper presented and discussed preparation, structural characteristics, and magnetic properties of alumina (Al2O3 matrix-based granular Co-cermet thin films deposited by means of the cosputtering technique for both Co and Al2O3. By varying the ferromagnetic (Co atomic fraction, x, from 0.04 to 0.63, several dominant features of deposition for these thin films were shown. Structural characteristics by X-ray diffraction confirmed a cermet-type structure for these films. Furthermore, magnetic behaviours presented a transition from paramagnetic- to superparamagnetic- and then to ferromagnetic-like properties, indicating agglomeration and growth following Co components of Co clusters or nanoparticles. These results show a typical granular Co-cermet feature for the Co-Al2O3 thin films prepared, in which Co magnetic nanogranules are dispersed in a ceramic matrix. Such nanomaterials can be applied suitably for our investigations in future on the magnetooptical responses of spinplasmonics.

  2. The influence of high energy milling and sintering parameters on reactive sintered (Ti, Mo)C–Ni cermets

    Energy Technology Data Exchange (ETDEWEB)

    Jõeleht, Marek, E-mail: marek.joeleht@ttu.ee [Department of Materials Engineering, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086 (Estonia); Pirso, Jüri; Juhani, Kristjan [Department of Materials Engineering, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086 (Estonia); Viljus, Mart; Traksmaa, Rainer [Materials Research Centre, Tallinn University of Technology, Ehitajate tee 5, Tallinn 19086 (Estonia)

    2015-07-05

    Highlights: • High energy milling and reactive sintering was used to produce (Ti, Mo)C–Ni cermets. • A linear relationship between milling time and oxygen contamination was observed. • TiC grain cores were visible with shorter milling durations. • Optimal milling time was found to be 6 h. • Mechanical properties above 1500 HV10 and 1.1 GPa were obtained. - Abstract: Reactive sintering was used to produce titanium carbide cermets with molybdenum as an alloying element and nickel for binder. High energy attritor mill was used to mill the same composition of Ti, C, Ni and Mo powders with different durations. High energy milling significantly reduces the temperatures at which a series of reactions occurs between metal and carbon during the heating. A two-step sintering cycle was used with vacuum and argon gas isostatic pressure as sintering atmospheres. Dense (Ti, Mo)C–17 wt%Ni cermets were obtained with mechanical properties above 1500 HV10 and 1.1 GPa. The optimum milling duration was found to be 6 h of milling with the available attritor. The powders were investigated with SEM, XRD and by oxygen/nitrogen analysis. The materials were characterised by density, Vicker’s hardness and transverse rupture strength were studied.

  3. Influence of the chemical composition and temperature in the mechanical behaviour of U3O8-Al cermets

    International Nuclear Information System (INIS)

    U3O8-Al nuclear cermets, with U3O8 content varying from zero to 80 wt%, were prepared by rotary swaging of U3O8-Al compacts at 5000C. Specimens were fabricated from these materials and tensile tested at the temperatures 250, 2000, 3000 and 4000C at a strain rate of 4.3 x 10-5s-1. The yield stress σ sub(E) and the ultimate tensile strength σ sub(R), were analysed as a function of the test temperature and cermet composition. The results show that the dependence of σ sub(E) and σ sub(R) on composition can be explained in terms of the variation of the minimum load bearing cross-sectional area of the aluminum matrix with U3O8 concentration. The temperature dependence of σ sub(R) and σ sub(E) of the cermets was seen to be similar to the temperature dependence of these parameters of the aluminum matrix. (Author)

  4. Design and safety studies on the European Facility for Industrial Transmutation (EFIT) with CERMET fuel

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X.N.; Rineiski, A.; Liu, P.; Matzerath Boccaccini, C.; Flad, M.; Gabrielli, F.; Maschek, W. [Forschungszentrum Karlsruhe (Germany). IKET; Morita, K. [Kyushu Univ. (Japan). Dept. of Applied Quantum Physics and Nuclear Engineering

    2008-07-01

    European R and D for ADS design and fuel development is driven in the 6{sup th} FP of the EU by the EUROTRANS Programme [1]. In EUROTRANS two ADS design routes are followed, the XT-ADS and the EFIT. The XT-ADS is designed to provide the experimental demonstration of transmutation in an Accelerator Driven System. The EFIT development, the European Facility for Industrial Transmutation, aims at a generic conceptual design of a full transmuter. A key issue of the R and D work is the choice of an adequate fuel to be used in an Accelerator Driven Transmuter (ADT) like EFIT. Various fuel forms have been assessed. CERCER and CERMET fuels, specifically with the matrices MgO and Mo, have finally been selected and are now under closer investigation. Within EUROTRANS, a special domain named 'AFTRA', is responsible to more deeply assess the behavior of these dedicated fuels and to provide the fuel data base for the core design of the EFIT. The EFIT concept has to be optimized towards: a good transmutation efficiency, high burnup, low reactivity swing, low power peaking, adequate subcriticality, reasonable beam requirements and a high safety level. The final recommendation on fuels by AFTRA gave a ranking of these fuels based on the mentioned criteria. The composite CERMET fuel (Pu{sub 0.5},Am{sub 0.5})O{sub 2-x} - Mo (with the isotope {sup 92}Mo comprising 93% of the molybdenum) has been recommended as the primary candidate for the EFIT. This CERMET fuel fulfils adopted criteria for fabrication and reprocessing, and provides excellent safety margins. Disadvantages include the cost for enrichment of {sup 92}Mo and a lower specific transmutation rate of minor actinides, because of the higher neutron absorption cross-section of the matrix. The composite CERCER fuel (Pu{sub 0.4},Am{sub 0.6})O{sub 2-x} - MgO has therefore been recommended as a backup solution as it might offer a higher consumption rate of minor actinides, and can be manufactured for a lower unit cost

  5. Effect of CaO doping on corrosion resistance of Cu/(NiFe2O4-10NiO) cermet inert anode for aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The CaO-doped Cu/(NiFe2O4-10NiO) cermet inert anodes were prepared by the cold isostatic pressing-sintering process,and their corrosion resistance to Na3AlF6-K3AlF6-AI2O3 melt was studied.The results show that the relative density of 5Cu/(NiFe2O4-10NiO) cermet sintered at 1 200 ℃ increases from 82.83% to 97.63% when 2% CaO (mass fraction) is added.During the electrolysis,the relative density of cermet inert anode descends owing to the chemical dissolution of additive CaO atceramic grain boundary,which accelerates the penetration of electrolyte.Thus,the corrosion resistance to melts ofCu/(NiFe2O4-10NiO) cermet inert anode is reduced.To improve the corrosion resistance of the cermet inert anode,the content of CaO doped should be decreased and the technology of cleaning the ceramic grain boundary should be applied.

  6. EFFECT OF Mo AND Mo2C ON THE MICROSTRUCTURE AND PROPERTIES OF THE CERMETS BASED ON Ti(C,N)

    Institute of Scientific and Technical Information of China (English)

    S.Q.Zhou; W.Zhao; W.H.Xiong; Y.N.Zhou

    2008-01-01

    Effect of Mo and Mo2 C on the microstructure and properties of Ti(C,N)-based cermets was investigated in this article. The results have indicated that the weight percentage of Mo from 5 to 10 can reduce Ti(C,N) grain diameter and thickness of the rim,and Ti(C,N) grain can be wetted by Ni-Cu-Mo liquid so as to get small contiguity of Ti(C,N) grain. In that way, the transverse rupture strength of Ti(C,N)-based cermets has reached 1800-1900 MPa; the fracture toughness has been due to 16-18 MPa.m1/2.But 15 wt pct Mo was not more effective on Ti(C,N)-based cermets, because the thickness of the rim becomes larger. In the circumstance of Mo2C, 5 wt pct Mo2C was good for microstructure and properties of Ti(C,N)-based cermets, but 11 wt pct Mo2C has resulted in larger contiguity of Ti(C,N) grain and big Ti(C,N) grain diameter so as to reduce transverse rupture strength and fracture toughness. So that, the effect of Mo on Ti(C,N)-based cermets is better than Mo2C.

  7. Fabrication and Testing of CERMET Fuel Materials for Nuclear Thermal Propulsion

    Science.gov (United States)

    Hickman, Robert; Broadway, Jeramie; Mireles, Omar

    2012-01-01

    A first generation Nuclear Cryogenic Propulsion Stage (NCPS) based on Nuclear Thermal Propulsion (NTP) is currently being developed for Advanced Space Exploration Systems. The overall goal of the project is to address critical NTP technology challenges and programmatic issues to establish confidence in the affordability and viability of NTP systems. The current technology roadmap for NTP identifies the development of a robust fuel form as a critical near term need. The lack of a qualified nuclear fuel is a significant technical risk that will require a considerable fraction of program resources to mitigate. Due to these risks and the cost for qualification, the development and selection of a primary fuel must begin prior to Authority to Proceed (ATP) for a specific mission. The fuel development is a progressive approach to incrementally reduce risk, converge the fuel materials, and mature the design and fabrication process of the fuel element. A key objective of the current project is to advance the maturity of CERMET fuels. The work includes fuel processing development and characterization, fuel specimen hot hydrogen screening, and prototypic fuel element testing. Early fuel materials development is critical to help validate requirements and fuel performance. The purpose of this paper is to provide an overview and status of the work at Marshall Space Flight Center (MSFC).

  8. Formation/consolidation of WC-Co cermets by simple shear

    International Nuclear Information System (INIS)

    Previous research using equal channel angular extrusion (ECAE) has shown that the process can be used to produce ultrafine equiaxed grains and filamentary microstructures. This method can also be used to effectively consolidate discontinuous material such as powder. A drawback of conventional extrusion is that the resulting inhomogeneous deformation is often not ideal for complex shaped industrial parts. In contrast, ECAE can be used for uniform deformations by simple shear to produce large and small cross-section material form which parts can be made. The extrusion procedure is carried out by extruding a long billet from an inlet channel to an exit channel of the same size which intersects the inlet channel at a sharp angle; 90 degree is typical. The process can be repeated on the same part to impart a large amount of shear deformation to the entire billet, except for small end areas. The principal objective of this study was to determine the effect of simple shear on the consolidation of WC-Co powders. The effect of the extrusion temperature and the amount of shear on the compaction and formation of the WC cermets were investigated. In this research, the successful consolidation of (W+C)-Co and WC-Co powders by ECAE is reported. The ECAE processed WC-Co phases and sample properties compare favorably with those of conventionally sintered material

  9. Corrosion of MTR type fuel plates containing U3O8-Al cermet cores

    International Nuclear Information System (INIS)

    The fuel plate samples containing U3O8-Al cermet cores with concentrations from 10 to 90% of U3O8 weight were fabricated. Samples with 58% of U3O8 eight were fabricated using compacts with densities from 75 to 95% of theoretical density. The influences of U3O8 concentration and porosity of compacted core on porosity and uniformity of core thickness are discussed. The U3O8-Al cores were submitted to corrosion tests and exposed to deionized water at temperatures of 30, 50, 70 and 900C by cladding deffect produced artificially. The results shown that core corrosion is accompanied by hydrogen release. The total volum of released hydrogen and the time interval to observe the initiation of hydrogen releasing (incubation time) are depending on core pososity and absolute temperature. A mechanism for U3O8-Al core corrosion process is proposed and discussed. The cladding of fuel plate samples was submitted to corrosion tests under similar conditons of the IAE-R1 reactor operating at 2, 5 and 10 MW. (Author)

  10. Corrosion of cermet anodes during low temperature electrolysis of alumina. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kozarek, R.L.; Ray, S.P.; Dawless, R.K.; LaCamera, A.F.

    1997-09-26

    Successful development of inert anodes to replace carbon anodes in Hall cells has the potential benefits of lower energy consumption,lower operating costs, and reduced CO{sub 2} and CO emissions. Using inert anodes at reduced current density and reduced operating temperature (800 C) has potential for decreasing the corrosion rate of inert anodes. It may also permit the use of new materials for containment and insulation. This report describes the fabrication characteristics and the corrosion performance of 5324-17% Cu Cermet anodes in 100 hour tests. Although some good results were achieved, the corrosion rate at low temperature (800 C) is varied and not significantly lower than typical results at high temperature ({approximately} 960 C). This report also describes several attempts at 200 hour tests, with one anode achieving 177 hours of continuous operation and another achieving a total of 235 hours but requiring three separate tests of the same anode. The longest run did show a lower wear rate in the last test; but a high resistance layer developed on the anode surface and forced an unacceptably low current density. It is recommended that intermediate temperatures be explored as a more optimal environment for inert anodes. Other electrolyte chemistries and anode compositions (especially high conductivity anodes) should be considered to alleviate problems associated with lower temperature operation.

  11. Conceptual Design of a CERMET NTR Fission Core Using Multiphysics Modeling Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Jonathan A. Webb; Brian J. Gross; William T. Taitano

    2011-08-01

    An initial pre-conceptual CERMET Nuclear Thermal Propulsion reactor system is investigated within this paper. Reactor configurations are investigated where the fuel consists of 60 vol.% UO2 and 40 vol.% W where the UO2 consists of Gd2O3 concentrations of 5 and 10 mol.%.Gd2O3. The fuel configuration consisting of 5 mol.% UO2 was found to have a total mass of 2761 kg and a thrust to weight ratio of 4.10 and required a coolant channel surface area to fueled volume ratio of approximately 15.0 in order to keep the centerline temperature below 3000 K. The configuration consisting of 10 mol.% Gd2O3 required a surface area to volume ratio of approximately 12.2 to cool the reactor to a peak temperature of 3000 K and had a total mass of 3200 kg and a thrust to weight ratio of 3.54. It is not known yet what concentration of Gd2O3 is required to maintain fuel stability at 3000 K; however, both reactors offer the potential for operations at 25,000 lb, and at a specific impulse which may range from 900 to 950 seconds.

  12. Sintering behaviour and mechanical properties of Cr3C2–NiCr cermets

    Indian Academy of Sciences (India)

    A Özer; Y K Tür

    2013-10-01

    Cr3C2–NiCr cermets are used as metal cutting tools due to their relatively high hardness and low sintering temperatures. In this study, a powder mixture consisting of 75 wt% Cr3C2–25 wt% NiCr was sintered at four different temperatures and characterized for itsmicrostructure and mechanical properties. The highest relative density obtained was 97% when sintered at 1350 °C. As the relative density increased, elastic modulus, transverse rupture strength, fracture toughness and hardness of the samples reached to a maximum of 314 GPa, 810 MPa, 10.4 MPa.m1/2 and 11.3 GPa, respectively. However, sintering at 1400 °C caused further grain growth and pore coalescence which resulted in decreasing density and degradation of all mechanical properties. Fracture surface investigation showed that the main failure mechanism was the intergranular fracture of ceramic phase accompanied by the ductile fracture of the metal phase which deformed plastically during crack propagation and enhanced the fracture toughness.

  13. Soudage par explosion thermique sous charge de cermets poreux à base de TiC-Ni sur substrat en acier-comportement tribologique Welding of porous TiC–Ni based cermets on substrate steel by thermal explosion under load-tribological behaviour

    Directory of Open Access Journals (Sweden)

    Lemboub Samia

    2013-11-01

    Full Text Available Dans ce travail, nous nous intéressons à l'élaboration de cermets à base de TiC-Ni par dispersion de particules de carbures, oxydes ou borures dans une matrice de nickel, grâce à la technique de l'explosion thermique sous une charge de 20 MPa. La combustion de mélanges actifs (Ti-C-Ni-An où An = Al2O3, MgO, SiC, TiB2, WC, basée sur la réaction de synthèse de TiC (ΔHf298K = −184 kJ/mole, génère des cermets complexes. Un court maintien sous charge du cermet à 1373 K, après l'explosion thermique, permet son soudage sur un substrat en acier XC55. Les cermets obtenus dans ces conditions demeurent poreux et conservent une porosité de l'ordre de 25–35 %. La densité relative du cermet, sa dureté et son comportement tribologique, dépendront de la nature de l'addition dans les mélanges de départ. Porous TiC-Ni based cermets were obtained by dispersion of carbides, oxides or borides particles in a nickel matrix thanks to the thermal explosion technique realized under a load of 20 MPa. The combustion of active mixtures (Ti-C-Ni-An where An = Al2O3, MgO, SiC, TiB2 or WC based on the titanium carbide reaction synthesis (ΔHf = −184 kJ/mol, generates porous complex cermets. After the thermal explosion, a short maintenance under load at 1373 K of the combustion product, allows at the same time the cermets welding on a carbon steel substrate. The obtained cermets under these conditions preserve a porosity of about 25–35%. The relative density, hardness and tribological behaviour of the complex cermets depend on the additions nature (An in the starting mixtures.

  14. Microstructure and temperature coefficient of resistance of thin cermet resistor films deposited from CrSi2-Cr-SiC targets by S-gun magnetron

    International Nuclear Information System (INIS)

    Technological solutions for producing nanoscale cermet resistor films with sheet resistances above 1000 Ω/□ and low temperature coefficients of resistance (TCR) have been investigated. 2-40 nm thick cermet films were sputter deposited from CrSi2-Cr-SiC targets by a dual cathode dc S-gun magnetron. In addition to studying film resistance versus temperature, the nanofilm structural features and composition were analyzed using scanning electron microscopy, atomic force microscopy, high-resolution transmission electron microscopy, energy-dispersive x-ray spectroscopy, and electron energy loss spectroscopy. This study has revealed that all cermet resistor films deposited at ambient and elevated temperatures were amorphous. The atomic ratio of Si to Cr in these films was about 2 to 1. The film TCR displayed a significant increase when the deposited film thickness was reduced below 2.5 nm. An optimized sputter process consisting of wafer degassing, cermet film deposition at elevated temperature with rf substrate bias, and a double annealing in vacuum, consisting of in situ annealing following the film sputtering and an additional annealing following the exposure of the wafers to air, has been found to be very effective for the film thermal stabilization and for fine tuning the film TCR. Cermet films with thicknesses in the range of 2.5-4 nm deposited using this technique had sheet resistances ranging from 1800 to 1200 Ω/□ and TCR values from -50 ppm/ deg. C to near zero, respectively. A possible mechanism responsible for the high efficiency of annealing the cermet films in vacuum (after preliminary exposure to air), resulting in resistance stabilization and TCR reduction, is also discussed.

  15. High temperature oxidation behaviour of nanostructured cermet coatings in amixed CO/sub 2/ - O/sub 2/ environment

    International Nuclear Information System (INIS)

    Nanostructured ceramic-metallic (cermet) coatings composed of nanosized ceramic particles (alpha-Al /sub 2/O/sub 3/ and TiO/sub 2/) dispersed in a nickel matrix were co-electrodeposited and then oxidized at 500 degree C, 600 degree C and 700 degree C in a mixed gas using a Thermo-gravimetric Analysis (TGA) apparatus. The mixed gas was composed of 15 percentage CO/sub 2/, 10 percentage O/sub 2/ and 75 percentage N/sub 2/. This research investigates the effects of CO/sub 2/ and O/sub 2/ partial pressures on time-depended oxidation rates for coatings and compared them to the results from atmospheric oxidation under similar temperatures. The increase in partial pressure of oxygen due to the presence of CO/sub 2/ at each tested temperature was calculated and correlated to the oxidation rate of the coatings. The results showed that the presence of CO/sub 2/ in the system increased the oxidation rate of cermet coatings when compared to atmospheric oxidation at the same temperature. It was also shown that the increase in the oxidation rate is not the result of CO/sub 2/ acting as the primary oxidant but as a secondary oxidant which results in an increase of the total partial pressure of oxygen and consequently higher oxidation rates. The WDS and XRD analyses results showed that the presence of nanosized TiO/sub 2/ particles in a nickel matrix can improve oxidation behaviour of the coatings by formation of Nu i-Tau i compounds on oxidizing surface of the coating which was found beneficiary in reducing the oxidation rates for cermet coatings. (author)

  16. High temperature oxidation behaviour of nanostructured cermet coatings in a mixed CO2 – O2 environment

    International Nuclear Information System (INIS)

    Nanostructured ceramic-metallic (cermet) coatings composed of nanosized ceramic particles (α-Al2O3 and TiO2) dispersed in a nickel matrix were co-electrodeposited and then oxidized at 500°C, 600°C and 700°C in a mixed gas using a Thermo-gravimetric Analysis (TGA) apparatus. The mixed gas was composed of 15% CO2, 10% O2 and 75% N2. This research investigates the effects of CO2 and O2 partial pressures on time-depended oxidation rates for coatings and compared them to the results from atmospheric oxidation under similar temperatures. The increase in partial pressure of oxygen due to the presence of CO2 at each tested temperature was calculated and correlated to the oxidation rate of the coatings. The results showed that the presence of CO2 in the system increased the oxidation rate of cermet coatings when compared to atmospheric oxidation at the same temperature. It was also shown that the increase in the oxidation rate is not the result of CO2 acting as the primary oxidant but as a secondary oxidant which results in an increase of the total partial pressure of oxygen and consequently higher oxidation rates. The WDS and XRD analyses results showed that the presence of nanosized TiO2 particles in a nickel matrix can improve oxidation behaviour of the coatings by formation of Ni-Ti compounds on oxidizing surface of the coating which was found beneficiary in reducing the oxidation rates for cermet coatings

  17. Prognosis and comparison of performances of composite CERCER and CERMET fuels dedicated to transmutation of TRU in an EFIT ADS

    Science.gov (United States)

    Sobolev, V.; Uyttenhove, W.; Thetford, R.; Maschek, W.

    2011-07-01

    The neutronic and thermomechanical performances of two composite fuel systems: CERCER with (Pu,Np,Am,Cm)O 2-x fuel particles in ceramic MgO matrix and CERMET with metallic Mo matrix, selected for transmutation of minor actinides in the European Facility for Industrial Transmutation (EFIT), were analysed aiming at their optimisation. The ALEPH burnup code system, based on MNCPX and ORIGEN codes and JEFF3.1 nuclear data library, and the modern version of the fuel rod performance code TRAFIC were used for this analysis. Because experimental data on the properties of the mixed minor-actinide oxides are scarce, and the in-reactor behaviour of the T91 steel chosen as cladding, as well as of the corrosion protective layer, is still not well-known, a set of "best estimates" provided the properties used in the code. The obtained results indicate that both fuel candidates, CERCER and CERMET, can satisfy the fuel design and safety criteria of EFIT. The residence time for both types of fuel elements can reach about 5 years with the reactivity swing within ±1000 pcm, and about 22% of the loaded MA is transmuted during this period. However, the fuel centreline temperature in the hottest CERCER fuel rod is close to the temperature above which MgO matrix becomes chemically instable. Moreover, a weak PCMI can appear in about 3 years of operation. The CERMET fuel can provide larger safety margins: the fuel temperature is more than 1000 K below the permitted level of 2380 K and the pellet-cladding gap remains open until the end of operation.

  18. The Hot Corrosion Performance of NiCr-Cr3 C2 Cermet Coating to Boiler Tube

    Institute of Scientific and Technical Information of China (English)

    DINGZhang-xiong; TUGuo-fu

    2004-01-01

    Three kinds of NiCr-Cr3 C2 cermet coatings were designed and deposited by the subsonic velocity flame spraying, and their performances of hot corrosion performance were evaluated in comt)arison with 102G,20G boiler tube steel, FeCrAl, NiCrTi, Ni5OCr and NiCrAIMoFe-Cr3 C2 coatings, which are widely used at present for protection of boiler tubes. Meanwhile, the influence of sealer on the hot corrosion resistance of warious coatings and the mechanisms of coating corrosion were explored.

  19. Characterization and High-Temperature Erosion Behaviour of HVOF Thermal Spray Cermet Coatings

    Science.gov (United States)

    Kumar, Pardeep; Sidhu, Buta Singh

    2016-01-01

    High-velocity oxygen fuel (HVOF) thermal spray, carbide-cermet-based coatings are usually employed in high-temperature erosive and erosive-corrosive environments. Extensive literature is available on high-temperature erosion performance of HVOF coatings under moderate to low particle flux and velocities for application in boiler tubes. This research work presents the characterization and high-temperature erosion behaviour of Cr3C2-25NiCr and WC-10Co-4Cr HVOF-sprayed coatings. Coatings were formulated on the substrate steel of type AISI 304, commonly used for the fabrication of pulverized coal burner nozzles (PCBN). Erosion testing was carried out in high-temperature air-jet erosion tester after simulating the conditions akin to that prevailing in PCBN in the boiler furnace. The coatings were tested for erosion behaviour at different angles and temperatures by freezing other test parameters. Brittle erosion behaviour was depicted in erosion testing, and the coatings couldn't restrain the erodent attacks to protect the substrate. High particle velocity and high particle flux were attributed to be the reasons of extensive erosive weight loss of the coatings. The surface morphology of the eroded specimens was analysed from back-scattered electron images to depict the probable mechanism of material removal. The coatings were characterized with optical microscopy, SEM-EDS analysis, XRD analysis, micro-hardness testing, porosity measurements, surface roughness testing and bond strength testing. The work was undertaken to investigate the performance of the selected coatings in highly erosive environment, so as to envisage their application in PCBNs for protection against material degradation. The coatings could only sustain in oblique impact erosion at room temperature and depleted fully under all other conditions.

  20. Effect of Mo{sub 2}C/(Mo{sub 2}C + WC) weight ratio on the microstructure and mechanical properties of Ti(C,N)-based cermet tool materials

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Qingzhong; Zhao, Jun, E-mail: zhaojun@sdu.edu.cn; Ai, Xing; Qin, Wenzhen; Wang, Dawei; Huang, Weimin

    2015-11-15

    To optimize the Mo{sub 2}C content in Ti(C,N)-based cermet tool materials used for cutting the high-strength steel of 42CrMo (AISI 4140/4142 steel), the cermets with different Mo{sub 2}C/(Mo{sub 2}C + WC) weight ratios were prepared. And the microstructure and mechanical properties of cermets were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and measurements of transverse rupture strength (TRS), Vickers hardness (HV) and fracture toughness (K{sub IC}). The results indicate that the Mo{sub 2}C/(Mo{sub 2}C + WC) ratios have great influences on the microstructure features and mechanical properties of Ti(C,N)-based cermets. When the Mo{sub 2}C/(Mo{sub 2}C + WC) ratio increases, the Ti(C,N) grains become finer with smaller black cores surrounded by thinner rims, and the structure of cermets tends to be more compact with smaller binder mean free path. Owing to the medium grains and moderate rims, the cermets with a Mo{sub 2}C/(Mo{sub 2}C + WC) ratio of 0.4 exhibit better mechanical properties, and can be chosen as the tool material for machining 42CrMo steel due to the lower Mo content. - Highlights: • Mo{sub 2}C/(Mo{sub 2}C + WC) ratios affect microstructure and mechanical properties of cermets. • Grains become fine and structure of cermets tends to be compact with raised Mo{sub 2}C. • The cermets with a Mo{sub 2}C/(Mo{sub 2}C + WC) ratio of 0.4 can be used to machine 42CrMo steel.

  1. Characterization of Ni-cermet degradation phenomena I. Long term resistivity monitoring, image processing and X-ray fluorescence analysis

    Science.gov (United States)

    Ananyev, M. V.; Bronin, D. I.; Osinkin, D. A.; Eremin, V. A.; Steinberger-Wilckens, R.; de Haart, L. G. J.; Mertens, J.

    2015-07-01

    The present paper is devoted to Ni-cermet degradation phenomena and places emphasis on experimental approaches and data handling. The resistivity of Ni-YSZ cermet (nickel and 8 mol.% yttria stabilized zirconia) anode substrates was monitored during 3000 h at 700 and 800 °C in a gas mixture of 80 vol.% water vapor and 20 vol.% hydrogen. The experimentally evaluated dependence of resistivity of the Ni-YSZ substrates can be well described by exponential decay functions. Post test analysis by image processing and XRF (X-ray fluorescence) analysis for characterization of the microstructure and elemental composition were carried out for virgin samples and after 300, 1000 and 3000 h of exposure time. The 3D-microstructure was reconstructed using an original spheres packing algorithm. Two processes leading to the Ni-YSZ degradation were observed: Ni-phase particle coarsening and volatilization. The effect of these processes on resistivity and such microstructure parameters as porosity, Ni-phase fraction, Ni and YSZ phases particle size distributions, triple phase boundary length, and tortuosity factor are considered in this paper.

  2. Development of UO2/PuO2 dispersed in uranium matrix CERMET fuel system for fast reactors

    International Nuclear Information System (INIS)

    CERMET fuel with either PuO2 or enriched UO2 dispersed in uranium metal matrix has a strong potential of becoming a fuel for the liquid metal cooled fast breeder reactors (LMR’s). In fact it may act as a bridge between the advantages and disadvantages associated with the two extremes of fuel systems (i.e. ceramic fuel and metallic fuel) for fast reactors. At Bhabha Atomic Research Centre (BARC), R and D efforts are on to develop this CERMET fuel by powder metallurgy route. This paper describes the development of flow sheet for preparation of UO2 dispersed in uranium metal matrix pellets for three different compositions i.e. U–20 wt%UO2, U–25 wt%UO2 and U–30 wt%UO2. It was found that the sintered pellets were having excellent integrity and their linear mass was higher than that of carbide fuel pellets used in Fast Breeder Test Reactor programme (FBTR) in India. The pellets were characterized by X-ray diffraction (XRD) technique for phase analysis and lattice parameter determination. The optical microstructures were developed and reported for all the three different U–UO2 compositions.

  3. Characterization of phase transformation and microstructure of nano hard phase Ti(C,N)-based cermet by spark plasma sintering

    Institute of Scientific and Technical Information of China (English)

    丰平; 熊惟皓; 李鹏; 余新; 夏阳华

    2004-01-01

    By means of optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM), the process of densification, the characterization of phase transformation and the microstructure for spark plasma sintering (SPS) nano hard phase Ti(C,N)-based cermet were investigated. It is found that the spark plasma sintering (SPS) enables the nano hard phase Ti(C,N)-based cermet to densify rapidly, however, the full densification of the sintered samples can not be obtained. The rate of phase transformation is significantly quick.When being sintered at 1 200 ℃ for 8 min, Mo2C is completely dissolved, and TiN dissolves into TiC entirely and disappears. Above 1 200 ℃, Ti(C,N) begins to decompose and the atoms of C and N separate from Ti(C,N) resulting in the generation of N2 and the graphite. Due to the denitrification and the graphitization, the density and the hardness of sintered samples are rather low. The distribution of grain size of the sample sintered at 1 350 ℃ covers a wide range of 90 - 500 nm, and most of the grain size are about 200 nm. The hard phase is not of typical core-rim structure. Oxides on the surface of particles can not be fully removed and present in sample as titanium oxide TiO2.Graphite exists in band-like shape.

  4. The behaviour under irradiation of molybdenum matrix for inert matrix fuel containing americium oxide (CerMet concept)

    Science.gov (United States)

    D'Agata, E.; Knol, S.; Fedorov, A. V.; Fernandez, A.; Somers, J.; Klaassen, F.

    2015-10-01

    Americium is a strong contributor to the long term radiotoxicity of high activity nuclear waste. Transmutation by irradiation in nuclear reactors or Accelerator Driven System (ADS, subcritical reactors dedicated to transmutation) of long-lived nuclides like 241Am is therefore an option for the reduction of radiotoxicity of waste packages to be stored in a repository. In order to safely burn americium in a fast reactor or ADS, it must be incorporated in a matrix that could be metallic (CerMet target) or ceramic (CerCer target). One of the most promising matrix to incorporate Am is molybdenum. In order to address the issues (swelling, stability under irradiation, gas retention and release) of using Mo as matrix to transmute Am, two irradiation experiments have been conducted recently at the High Flux Reactor (HFR) in Petten (The Netherland) namely HELIOS and BODEX. The BODEX experiment is a separate effect test, where the molybdenum behaviour is studied without the presence of fission products using 10B to "produce" helium, the HELIOS experiment included a more representative fuel target with the presence of Am and fission product. This paper covers the results of Post Irradiation Examination (PIE) of the two irradiation experiments mentioned above where molybdenum behaviour has been deeply investigated as possible matrix to transmute americium (CerMet fuel target). The behaviour of molybdenum looks satisfying at operating temperature but at high temperature (above 1000 °C) more investigation should be performed.

  5. Soudage par explosion thermique sous charge de cermets poreux à base de TiC-Ni sur substrat en acier-comportement tribologique Welding of porous TiC–Ni based cermets on substrate steel by thermal explosion under load-tribological behaviour

    OpenAIRE

    Lemboub Samia; Boudebane Said; Atoui L'hadi

    2013-01-01

    Dans ce travail, nous nous intéressons à l'élaboration de cermets à base de TiC-Ni par dispersion de particules de carbures, oxydes ou borures dans une matrice de nickel, grâce à la technique de l'explosion thermique sous une charge de 20 MPa. La combustion de mélanges actifs (Ti-C-Ni-An où An = Al2O3, MgO, SiC, TiB2, WC), basée sur la réaction de synthèse de TiC (ΔHf298K = −184 kJ/mole), génère des cermets complexes. Un court maintien sous charge du cermet à 1373 K, après l'explosion thermiq...

  6. Exploring Cu2O/Cu cermet as a partially inert anode to produce aluminum in a sustainable way

    International Nuclear Information System (INIS)

    Highlights: • Cu2O/Cu cermet was used as a candidate partially inert anode material to produce aluminum alloys. • The thermal corrosion behavior of Cu2O/Cu was investigated in molten salt at 960 °C. • The corrosion rate is largely governed by the geometrical structures of Cu in the prepared samples. • The corrosion rate increases with decreasing sizes and increasing filling contents of Cu phase. • The corrosion rate was 1.8–9 cm/y and the Cu contents is less than 6.2 wt.% in the produced aluminum. - Abstract: As an energy-intensive process, aluminum production by the Hall–Héroult method accounts for significant emissions of CO2 and some toxic greenhouse gases. The utilization of an inert anode in place of a carbon anode was considered as a revolutionary technique to solve most of the current environmental problems resulting from the Hall–Héroult process. However, the critical property requirements of the inert anode materials significantly limit the application of this technology. In light of the higher demand for aluminum alloys than for pure aluminum, a partially inert anode was designed to produce aluminum alloys in a more sustainable way. Here, Cu2O/Cu cermet was chosen as the material of interest. The thermal corrosion behavior of Cu2O/Cu was investigated in Na3AlF6–CaF2–Al2O3 electrolyte at 960 °C to elucidate the corrosion mechanisms of this type of partially inert anode for the production of aluminum or aluminum alloys. Furthermore, the effects of the geometrical structure of the Cu phase on the thermal corrosion behavior of Cu2O/Cu cermet in the electrolyte were investigated as well. The thermal corrosion rate was evaluated by the weight loss method and the results show that the samples prepared with branch-like Cu have higher thermal corrosion rate than those prepared with spherical Cu, and the corrosion rate increases with decreasing size and increasing filling content of Cu phase. The calculated corrosion rate was about 1.5–7

  7. Degradation of conductivity and microstructure under thermal and current load in Ni-YSZ cermets for SOFC anodes

    DEFF Research Database (Denmark)

    Thydén, Karl Tor Sune; Barfod, R.; Liu, Yuliang

    2006-01-01

    The degradation of electrical conductivity in porous nickel-yttria stabilized zirconia composite cermets in a H2/H2O atmosphere under high temperature treatments has been investigated. The parameters varied were: temperature, water partial pressure, and electrical current load. The microstructure...... fraction of percolated Ni was measured. Temperature proved to have the largest effect on the degradation. Samples tested at 1000°C, in contrast to 750°C, showed a severe decrease of conductivity and growth of Ni particles. Higher water partial pressure accelerated Ni particle growth at both temperatures......, but the loss of percolation and conductivity at 1000°C was less severe under high water partial pressure. A possible explanation for this behavior is discussed....

  8. Microstructure and strength of brazed joints of TiB2 cermet to TiAl-based alloys

    Institute of Scientific and Technical Information of China (English)

    李卓然; 冯吉才; 曹健

    2003-01-01

    In this study, TiB2 cermet and TiAl-based alloy are vacuum brazed successfully by using Ag-Cu-Ti filler metal. The microstructural analyses indicate that two reaction products, Ti(Cu, Al)2 and Ag based solid solution (Ag(s.s)), are present in the brazing seam, and the interface structure of the brazed joint is TiB2/TiB2+ Ag(s.s) /Ag(s.s)+Ti(Cu, Al)2/Ti(Cu, Al)2/TiAl. The experimental results show that the shear strength of the brazed TiB2/TiAl joints decreases as the brazing time increases at a definite brazing temperature. When the joint is brazed at 1 223 K for 5 min, a joint strength up to 173 MPa is achieved.

  9. Combustion Synthesis of Ti-2B-Cu/Ni and 3Ti-2BN-Cu/Ni Bilayered Cermets

    Institute of Scientific and Technical Information of China (English)

    Weiping SHEN; Wenbin CAO; Changchun GE; E.H.Grigoryan; A.E.Sytschev; A.S.Rogachev

    2003-01-01

    The effects of Cu and Ni (x=0, 10, 20 and 40 wt pct) and compaction pressures (12, 24, 84 and 108 MPa)on combustion wave velocity and wave front shape for Ti-2B-Cu/Ni and 3Ti-2BN-Cu/Ni bilayered cermets were investigated by a video camera. Since the boiling point of Cu is lower, the wave velocities of specimens are slower.Due to the higher specific heat of Ni than that of Cu, the wave velocities of specimens was slowed down a lot with increasing the Ni diluent. The wave velocity differences of the specimens containing Ni are more than that of the bilayered specimens containing Cu. Wave velocities of the specimens containing Ni increased more than that of the specimens containing Cu when higher pressure was employed for green mixture. The more the wave velocity difference of the bilayer, the more curved the specimen.

  10. Corrosion behavior of laser-clad Mo2NiB2 cermet coating on low carbon steel substrate

    International Nuclear Information System (INIS)

    A Mo2NiB2 cermet coating on low carbon steel substrate was fabricated by laser cladding technique. The coating consisted of γ-(Fe, Ni) as a metallic matrix binder and Mo2NiB2 particles as a reinforced phase distributed uniformly in the microstructure. Corrosion behavior of the coating was investigated and the commercial 1Cr, 304SS, and G3 were used for comparison. G3 exhibited the highest corrosion resistance and 1Cr the lowest corrosion resistance, whereas 304SS and the coating exhibited the intermediate and similar corrosion resistance. However, the severe pitting corrosion which was observed in 304SS did not exist for the coating. (author)

  11. Effect of hot isostatic pressing nitrogen on the microstructure and properties of a Ti(C, N)-based cermet

    Institute of Scientific and Technical Information of China (English)

    YAN Xianmei; XIONG Weihao; YANG Yong; ZHENG Liyun

    2006-01-01

    The high-temperature, high-pressure hot isostatic pressing technology was used for depositing hard coatings on Ti(C, N)-based cermets. The microstructure and properties of the sample were investigated using optical microscopy, scanning electron microscopy, X-ray diffraction, electron probe microanalysis, and microhardness tester. The results showed that the rich titanium and nitrogen in surface zone were induced by the heat treatment. The high nitrogen activity of the surface region was the driving force for outward transport of titanium and inward transport of tungsten in the cobalt binder. The toughness and hardness were improved and a hardness gradient was formed. It is the high-temperature, high-pressure N2that enables closure of holes, thereby alleviating defects and prolonging tool life.

  12. Machinability of Hastelloy C-276 Using Hot-pressed Sintered Ti(C7N3)-based Cermet Cutting Tools

    Institute of Scientific and Technical Information of China (English)

    XU Kaitao; ZOU Bin; HUANG Chuanzhen; YAO Yang; ZHOU Huijun; LIU Zhanqiang

    2015-01-01

    C-276 nickel-based alloy is a difficult-to-cut material. In high-speed machining of Hastelloy C-276, notching is a prominent fallure mode due to high mechanical properties of work piece, which results in the short tool life and low productivity. In this paper, a newly developed Ti(C7N3)-based cermet insert manufactured by a hot-pressing method is used to machine the C-276 nickel-based alloy, and its cutting performances are studied. Based on orthogonal experiment method, the influence of cutting parameters on tool life, material removal rates and surface roughness are investigated. Experimental research results indicate that the optimal cutting condition is a cutting speed of 50 m/min, depth of cut of 0.4 mm and feed rate of 0.15 mm/r if the tool life and material removal rates are considered comprehensively. In this case, the tool life is 32 min and material removal rates are 3000 mm3/min, which is appropriate to the rough machining. If the tool life and surface roughness are considered, the better cutting condition is a cutting speed of 75 m/min, depth of cut of 0.6 mm and feed rate of 0.1 mm/r. In this case, the surface roughness is 0.59mm. Notch wear, flank wear, chipping at the tool nose, built-up edge(BUE) and micro-cracks are found when Ti(C7N3)-based cermet insert turned Hastelloy C-276. Oxidation, adhesive, abrasive and diffusion are the wear mechanisms, which can be investigated by the observations of scanning electron microscope and energy-dispersive spectroscopy. This research will help to guide studies on the evaluation of machining parameters to further advance the productivity of nickel based alloy Hastelloy C-276 machining.

  13. Hot Hydrogen Testing of Tungsten-Uranium Dioxide (W-UO2) CERMET Fuel Materials for Nuclear Thermal Propulsion

    Science.gov (United States)

    Hickman, Robert; Broadway, Jeramie

    2014-01-01

    CERMET fuel materials are being developed at the NASA Marshall Space Flight Center for a Nuclear Cryogenic Propulsion Stage. Recent work has resulted in the development and demonstration of a Compact Fuel Element Environmental Test (CFEET) System that is capable of subjecting depleted uranium fuel material samples to hot hydrogen. A critical obstacle to the development of an NCPS engine is the high-cost and safety concerns associated with developmental testing in nuclear environments. The purpose of this testing capability is to enable low-cost screening of candidate materials, fabrication processes, and further validation of concepts. The CERMET samples consist of depleted uranium dioxide (UO2) fuel particles in a tungsten metal matrix, which has been demonstrated on previous programs to provide improved performance and retention of fission products1. Numerous past programs have utilized hot hydrogen furnace testing to develop and evaluate fuel materials. The testing provides a reasonable simulation of temperature and thermal stress effects in a flowing hydrogen environment. Though no information is gained about radiation damage, the furnace testing is extremely valuable for development and verification of fuel element materials and processes. The current work includes testing of subscale W-UO2 slugs to evaluate fuel loss and stability. The materials are then fabricated into samples with seven cooling channels to test a more representative section of a fuel element. Several iterations of testing are being performed to evaluate fuel mass loss impacts from density, microstructure, fuel particle size and shape, chemistry, claddings, particle coatings, and stabilizers. The fuel materials and forms being evaluated on this effort have all been demonstrated to control fuel migration and loss. The objective is to verify performance improvements of the various materials and process options prior to expensive full scale fabrication and testing. Post test analysis will

  14. Acoustic emission analysis of Vickers indentation fracture of cermet and ceramic coatings

    International Nuclear Information System (INIS)

    The aim of this work was to develop an instrumented experimental methodology of quantitative material evaluation based on the acoustic emission (AE) monitoring of a dead-weight Vickers indentation. This was to assess the degree of cracking and hence the toughness of thermally sprayed coatings. AE data were acquired during indentation tests on samples of coatings of nominal thickness 250–325 µm at a variety of indentation loads ranging from 49 to 490 N. Measurements were carried out on five different carbide and ceramic coatings (HVOF as-sprayed WC-12%Co (JP5000 and JetKote), HIPed WC-12%Co (JetKote) and as-sprayed Al2O3 (APS/Metco and HVOF/theta-gun)). The raw AE signals recorded during indentation were analysed and the total surface crack length around the indent determined. The results showed that the total surface crack length measured gave fracture toughness (K1c) values which were consistent with the published literature for similar coatings but evaluated using the classical approach (Palmqvist/half-penny model). Hence, the total surface crack length criteria can be applied to ceramic and cermet coatings which may or may not exhibit fracture via radial cracks. The values of K1c measured were 3.4 ± 0.1 MPa m1/2 for high-velocity oxygen fuel (HVOF) (theta-gun) Al2O3, 4.6 ± 0.3 MPa m1/2 for as-sprayed HVOF (JetKote) WC-12%Co, 7.1±0.1 MPa m1/2 for as-sprayed HVOF (JP5000) WC-12%Co and 7.4 ± 0.2 MPa m1/2 for HIPed HVOF (JetKote) WC-12%Co coatings. The crack lengths were then calibrated against the AE response and correlation coefficients evaluated. The values of K1c measured using AE correlations were 3.3 MPa m1/2 for HVOF (theta-gun) Al2O3, 2.6 MPa m1/2 for APS (Metco) Al2O3, 2.5 MPa m1/2 for as-sprayed HVOF (JetKote) WC-12%Co, 6.3 MPa m1/2 for as-sprayed HVOF (JP5000) WC-12%Co and 8.6 MPa m1/2 for HIPed HVOF (JetKote) WC-12%Co coatings. It is concluded that within each category of coating type, AE can be used as a suitable surrogate for crack length

  15. Theoretical research on the propagation of the crack normal to and dwelling on the interface of the cermet cladding material structure

    International Nuclear Information System (INIS)

    The interface crack propagation problem in the cermet cladding material structure was studied. A comparative propagation property parameter (CP) suitable to judge the propagation direction of the interface crack in the cermet cladding material structure was proposed. The interface crack propagation criterion was established. Theoretical models of the CPs for the crack normal to and dwelling on the interface deflecting separately into the clad, the interface and the substrate were built, and the relations between the CPs and the load action angle, the clad thickness ratio and the load were investigated with an example. The research results show that, under the research conditions, the interface crack will more easily propagate into the clad layer than into the substrate

  16. Theoretical research on the propagation of the crack normal to and dwelling on the interface of the cermet cladding material structure

    Energy Technology Data Exchange (ETDEWEB)

    Junru, Yang; Chuanjuan, Song; Minglan, Wang; Yeukan, Zhang; Jing, Sun [College of Mechanical and Electronic Engineering, Shandong University of Science and Technology, Qingdao (China)

    2016-01-15

    The interface crack propagation problem in the cermet cladding material structure was studied. A comparative propagation property parameter (CP) suitable to judge the propagation direction of the interface crack in the cermet cladding material structure was proposed. The interface crack propagation criterion was established. Theoretical models of the CPs for the crack normal to and dwelling on the interface deflecting separately into the clad, the interface and the substrate were built, and the relations between the CPs and the load action angle, the clad thickness ratio and the load were investigated with an example. The research results show that, under the research conditions, the interface crack will more easily propagate into the clad layer than into the substrate.

  17. Propriétés thermomécaniques de cermets à base de ferrite spinelle : influence de l'oxydation

    OpenAIRE

    Huchet, Guillaume

    2010-01-01

    Co-encadrement de la thèse : Vincent Maurel In order to replace consumable carbon electrodes in the Hall-Heroult electrolysis process, the development of inert anodes resistant to oxidation is a technical challenge for main leaders in aluminum production. Some of the recent researches were focused on promising and original cermets constituted of a dual phase ceramic matrix and dispersed metallic particles, which have sufficient electric conductivity and corrosion resistance at high tempera...

  18. A Comparative Study on SiC-B4C-Si Cermet Prepared by Pressureless Sintering and Spark Plasma Sintering Methods

    Science.gov (United States)

    Sahani, P.; Karak, S. K.; Mishra, B.; Chakravarty, D.; Chaira, D.

    2016-06-01

    Silicon carbide (SiC)-boron carbide (B4C) based cermets were doped with 5, 10, and 20 wt pct Silicon (Si) and their sinterability and properties were investigated for conventional sintering at 2223 K (1950 °C) and spark plasma sintering (SPS) at 1623 K (1350 °C). An average particle size of ~3 µm was obtained after 10 hours of milling. There is an enhancement of Vickers microhardness in the 10 wt pct Si sample from 18.10 in conventional sintering to 27.80 GPa for SPS. The relative density, microhardness, and indentation fracture toughness of the composition SiC60(B4C)30Si10 fabricated by SPS are 98 pct, 27.80 GPa, and 3.8 MPa m1/2, respectively. The novelty of the present study is to tailor the wettability and ductility of the cermet by addition of Si into the SiC-B4C matrix. Better densification with improved properties is achieved for cermets consolidated by SPS at lower temperatures than conventional sintering.

  19. Effect of metallic phase content on mechanical properties of (85Cu- 15Ni)/(10NiO-NiFe2O4) cermet inert anode for aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    (85Cu-15Ni)/(10NiO-NiFe2O4) cermets were prepared with Cu-Ni mixed powders as toughening metallic phase and 10NiO-NiFe2O4 as ceramic matrix. The phase composition, microstructure of composite and the effect of metallic phase content on bending strength, hardness, fracture toughness and thermal shock resistance were studied. X-ray diffraction analysis indicates the coexistence of (Cu-Ni), NiO and NiFe2O4 phases in the cermets. Within the content range of metallic phase from 0% to 20% (mass fraction), the maximal bending strength (176.4 MPa) and the minimal porosity (3.9%) of composite appear at the metallic phase content of 5%. The fracture toughness increases and Vickers' hardness decreases with increasing metal content. When the thermal shock temperature difference (△t) is below 200 ℃, the loss rate of residual strength for 10NiO-NiFe2O4 ceramic is only 8%, but about 40% for (85Cu-15Ni)/(10NiO-NiFe2O4) cermets. As △t is above 200 ℃, the residual strength sharply decreases for sample CN0 and falls slowly for samples CN5-CN20.

  20. Laser nanostructured Co nanocylinders-Al2O3 cermets for enhanced & flexible solar selective absorbers applications

    Science.gov (United States)

    Karoro, A.; Nuru, Z. Y.; Kotsedi, L.; Bouziane, Kh.; Mothudi, B. M.; Maaza, M.

    2015-08-01

    We report on the structural and optical properties of laser surface structured Co nanocylinders-Al2O3 cermets on flexible Aluminium substrate for enhanced solar selective absorbers applications. This new family of solar selective absorbers coating consisting of Co nanocylinders embedded into nanoporous alumina template which were produced by standard electrodeposition and thereafter submitted to femtosecond laser surface structuring. While their structural and chemical properties were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and atomic force microscopy, their optical characteristics were investigated by specular & diffuse reflectance. The optimized samples exhibit an elevated optical absorptance α(λ) above 98% and an emittance ɛ(λ) ∼0.03 in the spectral range of 200-1100 nm. This set of values was suggested to be related to several surface and volume phenomena such as light trapping, plasmon surface effect as well as angular dependence of light reflection induced by the ultrafast laser multi-scale structuring.

  1. Laser nanostructured Co nanocylinders-Al{sub 2}O{sub 3} cermets for enhanced & flexible solar selective absorbers applications

    Energy Technology Data Exchange (ETDEWEB)

    Karoro, A., E-mail: angela@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Western Cape (South Africa); Nuru, Z.Y.; Kotsedi, L.; Bouziane, Kh. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Western Cape (South Africa); Mothudi, B.M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Physics Dept., University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Western Cape (South Africa)

    2015-08-30

    Highlights: • Co-Al{sub 2}O{sub 3} was synthesized by electrodeposition & femtosecond laser structuring. • The ultrafast laser structuring significantly increases the solar absorption. • Co-Al{sub 2}O{sub 3} exhibited 0.98 solar absorptance and 0.03 thermal emittance. - Abstract: We report on the structural and optical properties of laser surface structured Co nanocylinders-Al{sub 2}O{sub 3} cermets on flexible Aluminium substrate for enhanced solar selective absorbers applications. This new family of solar selective absorbers coating consisting of Co nanocylinders embedded into nanoporous alumina template which were produced by standard electrodeposition and thereafter submitted to femtosecond laser surface structuring. While their structural and chemical properties were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and atomic force microscopy, their optical characteristics were investigated by specular & diffuse reflectance. The optimized samples exhibit an elevated optical absorptance α(λ) above 98% and an emittance ε(λ) ∼0.03 in the spectral range of 200–1100 nm. This set of values was suggested to be related to several surface and volume phenomena such as light trapping, plasmon surface effect as well as angular dependence of light reflection induced by the ultrafast laser multi-scale structuring.

  2. Laser nanostructured Co nanocylinders-Al2O3 cermets for enhanced & flexible solar selective absorbers applications

    International Nuclear Information System (INIS)

    Highlights: • Co-Al2O3 was synthesized by electrodeposition & femtosecond laser structuring. • The ultrafast laser structuring significantly increases the solar absorption. • Co-Al2O3 exhibited 0.98 solar absorptance and 0.03 thermal emittance. - Abstract: We report on the structural and optical properties of laser surface structured Co nanocylinders-Al2O3 cermets on flexible Aluminium substrate for enhanced solar selective absorbers applications. This new family of solar selective absorbers coating consisting of Co nanocylinders embedded into nanoporous alumina template which were produced by standard electrodeposition and thereafter submitted to femtosecond laser surface structuring. While their structural and chemical properties were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and atomic force microscopy, their optical characteristics were investigated by specular & diffuse reflectance. The optimized samples exhibit an elevated optical absorptance α(λ) above 98% and an emittance ε(λ) ∼0.03 in the spectral range of 200–1100 nm. This set of values was suggested to be related to several surface and volume phenomena such as light trapping, plasmon surface effect as well as angular dependence of light reflection induced by the ultrafast laser multi-scale structuring

  3. Investigation on hole manufacture in 42CrMo4 steel using 3-flute carbide drills and 6-flute cermet reamers

    DEFF Research Database (Denmark)

    Müller, Pavel; De Chiffre, Leonardo

    2009-01-01

    An investigation on cutting forces and hole quality using carbide 3-flute self-centering drills and 6-flute cermet reamers was performed on 42CrMo4 alloy steel. Different depths of cuts were analyzed with respect to cutting thrust and cutting torque, hole diameter, form and surface integrity. Good...... reproducibility in cutting forces was obtained for all drilled holes with coefficients of variation less than 6% for thrust and 8% for torque respectively. Good reproducibility for all depths of cuts was obtained in reaming, reaching coefficient of variation in the range 7-13% for thrust and 9-23% for torque...

  4. Cinétique et mécanismes de corrosion sèche d'un cermet à base Cu-Ni

    OpenAIRE

    Rioult, Fabien

    2005-01-01

    In the course of the development of new materials for inert anodes in the aluminum electrolysis process, cermets have been shown to be good candidates due to combined properties of conduction and resistance to corrosion. At temperatures as high as 900-1000°C, these materials must be particularly resistant, not only to the corrosion by the electrolytic bath, but also to the corrosion by the gaseous atmosphere, which contains oxygen and fluorides. This study was devoted to the kinetics of oxida...

  5. Abrasive wear behaviour of conventional and large-particle tungsten carbide-based cermet coatings as a function of abrasive size and type

    OpenAIRE

    Kamdi, Z.; Shipway, P.H.; Voisey, K.T.; Sturgeon, A.J.

    2011-01-01

    Abrasive wear behaviour of materials can be assessed using a wide variety of testing methods, and the relative performance of materials will tend to depend upon the testing procedure employed. In this work, two cermet type coatings have been examined, namely (i) a conventional tungsten carbide-cobalt thermally sprayed coating with a carbide size of between ∼0.3 – 5 μm and (ii) a tungsten carbide-nickel alloy weld overlay with large spherical carbides of the order of ∼50 – 140 μm in diameter (...

  6. Comparative study of the fabrication of ultrafine Ti(C,N)-based cermets by spark plasma sintering and conventional vacuum sintering

    Institute of Scientific and Technical Information of China (English)

    LEI Yan; XIONG Weihao; LIANG Zaiguo; FENG Ping; WANG Zhiwu

    2005-01-01

    Spark plasma sintering (SPS) and conventional vacuum sintering (VS) were employed to fabricate ultrafine Ti(C,N)-based cermets. The shrinkage behavior, microstructure, and porosity and mechanical properties of the samples fabricated by SPS were compared with those of the samples sintered by VS using optical microscopy, scanning electron microscopy, universal testing machine, and rockwell tester. The results are as follows: (1) The shrinkage process occurred mainly in the range of 1000-1300℃ during the VS process, and only a 0.2% linear shrinkage ratio appeared below 800℃;during the SPS process, a 60% dimensional change occurred below 800℃ as a result of pressure action. (2) By utilizing the SPS technique, it is difficult for obtaining fully dense Ti(C,N)-based cermets. Due to the much existence of pores and uncombined carbon, the mechanical properties of the sintered samples by SPS are inferior to sintered ones by VS. (3) grain size of the samples sintered by SPS is still below 0.5 μm, but not by VS; because of low sintering temperature, there are no typical core/rim structures formed in the sintered samples by SPS 1; the main microstructures of the sintered samples by SPS2 are a white core/grey shell structure, whereas by VS show a typical black core/grey shell structure.

  7. Study on Temperature Filed Simulation During Electro-discharge Machining of TiC/Ni Cermet%TiC/Ni金属陶瓷电火花加工温度场仿真研究

    Institute of Scientific and Technical Information of China (English)

    冯业瑞; 郭永丰; 李宗峰

    2016-01-01

    为深入研究TiC/Ni金属陶瓷电火花加工过程,进行了TiC/Ni金属陶瓷电火花加工单脉冲放电温度场仿真。建立了TiC/Ni金属陶瓷颗粒随机分布模型,运用ANSYS软件采用生死单元法对TiC/Ni金属陶瓷进行单脉冲温度场仿真研究,并对结果进行了实验验证。结果表明:TiC/Ni金属陶瓷颗粒随机分布模型适于TiC/Ni金属陶瓷电火花加工温度场仿真,且随着峰值电流及脉宽的增大,TiC/Ni金属陶瓷蚀除体积增加,表现为试验时材料蚀除率增加。%To study electro-discharge machining (EDM) process of TiC/Ni cermet ,the temperature field simulation of single pulse EDM of TiC/Ni cermet was carried out ,the randomly distribution model of TiC/Ni cermet particles was established. The single pulse temperature field was simulated using birth-death element method based on ANSYS software. Experimental results verify that the model is suitable for EDM temperature field simulation of TiC/Ni cermet. The results also show that with increase of peak current and pulse-on time ,due to increase of material removal rate ,material removal volume of TiC/Ni cermet increase.

  8. Ni-CeO2 Cermets Synthesis by Solid State Sintering of Ni/CeO2 Multilayer

    Directory of Open Access Journals (Sweden)

    Aleksandras ILJINAS

    2013-12-01

    Full Text Available Nickel and gadolinium doped cerium oxide (GDC cermet is intensively investigated for an application as an anode material for solid oxide fuel cells based on various electrolytes. The purpose of the present investigation is to analyze morphology, microstructure, and optical properties of deposited and annealed for one hour in the temperatures from 500 ºC to 900 ºC Ni/CeO2 multilayer thin films deposited by sputtering. The crystallographic structure of thin films was investigated by X-ray diffraction. The morphology of the film cross-section was investigated with scanning electron microscope. The elemental analysis of samples was investigated by energy-dispersive X-ray spectroscopy. The fitting of the optical reflectance data was made using Abeles matrix method that is used for the design of interference coatings. The film cross-section of the post-annealed samples consisted of four layers. The first CeO2 layer (on Si had the same fine columnar structure with no features of Ni intermixing. The part of Ni (middle-layer after annealing was converted to NiO with grain size exceeding 100 nm. The CeO2 layer deposited on Ni was divided into two layers. Lower layer had small grains not exceeding 25 nm and consisting of NiO and CeO2 mixture. Upper layer consisted of CeO2 columns with approximate thickness of 50 nm. Ni sample annealed at 600 ºC was fully oxidized. The NiO thickness and refraction index were almost steady after annealing in various temperatures. The approximation of experimental reflectance data was successful only for the samples with one transparent homogeneous layer. The reflectance of the Ni/CeO2 samples annealed at intermediate temperatures could not be fitted using one-layer or three-layer model. That may show that a simplified model could not be implemented.  The real system has complicated distribution of refraction index. DOI: http://dx.doi.org/10.5755/j01.ms.19.4.3073

  9. Exploring Cu{sub 2}O/Cu cermet as a partially inert anode to produce aluminum in a sustainable way

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Li-Chao [School of Mechanical Engineering, Huaihai Institute of Technology and Jiangsu Province R and D Institute of Marine Resources, Lianyungang 222005 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xie, Ning, E-mail: xiening@hit.edu.cn [School of Transportation Science and Engineering, Harbin Institute of Technology, Harbin 150090 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Shao, Wen-Zhu, E-mail: wzshao@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Zhen, Liang [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Ivanov, V.V. [Physical Chemistry Department, Siberian Federal University, Krasnoyarsk 660041 (Russian Federation)

    2014-10-15

    Highlights: • Cu{sub 2}O/Cu cermet was used as a candidate partially inert anode material to produce aluminum alloys. • The thermal corrosion behavior of Cu{sub 2}O/Cu was investigated in molten salt at 960 °C. • The corrosion rate is largely governed by the geometrical structures of Cu in the prepared samples. • The corrosion rate increases with decreasing sizes and increasing filling contents of Cu phase. • The corrosion rate was 1.8–9 cm/y and the Cu contents is less than 6.2 wt.% in the produced aluminum. - Abstract: As an energy-intensive process, aluminum production by the Hall–Héroult method accounts for significant emissions of CO{sub 2} and some toxic greenhouse gases. The utilization of an inert anode in place of a carbon anode was considered as a revolutionary technique to solve most of the current environmental problems resulting from the Hall–Héroult process. However, the critical property requirements of the inert anode materials significantly limit the application of this technology. In light of the higher demand for aluminum alloys than for pure aluminum, a partially inert anode was designed to produce aluminum alloys in a more sustainable way. Here, Cu{sub 2}O/Cu cermet was chosen as the material of interest. The thermal corrosion behavior of Cu{sub 2}O/Cu was investigated in Na{sub 3}AlF{sub 6}–CaF{sub 2}–Al{sub 2}O{sub 3} electrolyte at 960 °C to elucidate the corrosion mechanisms of this type of partially inert anode for the production of aluminum or aluminum alloys. Furthermore, the effects of the geometrical structure of the Cu phase on the thermal corrosion behavior of Cu{sub 2}O/Cu cermet in the electrolyte were investigated as well. The thermal corrosion rate was evaluated by the weight loss method and the results show that the samples prepared with branch-like Cu have higher thermal corrosion rate than those prepared with spherical Cu, and the corrosion rate increases with decreasing size and increasing filling

  10. A New Innovative Spherical Cermet Nuclear Fuel Element to Achieve an Ultra-Long Core Life for use in Grid-Appropriate LWRs

    Energy Technology Data Exchange (ETDEWEB)

    Senor, David J.; Painter, Chad L.; Geelhood, Ken J.; Wootan, David W.; Meriwether, George H.; Cuta, Judith M.; Adkins, Harold E.; Matson, Dean W.; Abrego, Celestino P.

    2007-12-01

    Spherical cermet fuel elements are proposed for use in the Atoms For Peace Reactor (AFPR-100) concept. AFPR-100 is a small-scale, inherently safe, proliferation-resistant reactor that would be ideal for deployment to nations with emerging economies that decide to select nuclear power for the generation of carbon-free electricity. The basic concept of the AFPR core is a water-cooled fixed particle bed, randomly packed with spherical fuel elements. The flow of coolant within the particle bed is at such a low rate that the bed does not fluidize. This report summarizes an approach to fuel fabrication, results associated with fuel performance modeling, core neutronics and thermal hydraulics analyses demonstrating a ~20 year core life, and a conclusion that the proliferation resistance of the AFPR reactor concept is high.

  11. Influence of the HVOF Gas Composition on the Thermal Spraying of WC-Co Submicron Powders (-8 + 1 μm) to Produce Superfine Structured Cermet Coatings

    Science.gov (United States)

    Tillmann, W.; Vogli, E.; Baumann, I.; Matthaeus, G.; Ostrowski, T.

    2008-12-01

    Thermal spraying technology represents a novel and promising approach to protect forming tools with complex surfaces and highest shape accuracy against abrasive wear and galling. However, due to high or nonuniform layer thicknesses or inappropriate surface roughness conventional coarse-structured coatings are not suitable to achieve this aim. The application of novel submicron or nanoscaled feedstock materials in the thermal spray process can provide the deposition of cermet coatings with significantly improved characteristics and is recently of great interest in science and industry. In this collaborative study, the feeding and HVOF spraying of WC-Co submicron powders (-8 + 1 μm) have been investigated to manufacture superfine structured, wear resistant, near-net-shape coatings with improved macroscopic properties and smooth surfaces. The influences of varying HVOF gas compositions on the spray process and the coating properties have been analyzed.

  12. Results from 100 h electrolysis testing of NiFe2O4 based cermet as inert anode in aluminum reduction

    Institute of Scientific and Technical Information of China (English)

    LAI Yan-qing; TIAN Zhong-liang; LI Jie; YE Shao-long; LI Xin-zheng; LIU Ye-xiang

    2006-01-01

    A 100 mm diameter cup-shaped inert anode for aluminum electrolysis consisting of cermet 17Ni/83(10NiO-90NiFe2O4) was prepared and the operating performance was evaluated in a laboratory cell with the electrolyte CR2.3 and Al2O3 concentration 7.43% (mass fraction). The results indicate that no major operational difficulties are encountered during the testing which lasts for 101.5 h and the inert anode exhibits good general performances. The steady-state average concentration of impurity Ni in the bath is close to the solubility, however, the Fe concentration is lower than its solubility. The contents of the main contaminants for aluminum produced are Ni 0.128 8%, Fe 1.007 4%. The corrosion rate of inert anode under electrolysis conditions based on the content of impurity Ni in metal aluminum is approximately 8.51 mm/a.

  13. Effect of Si on 1Cr18Ni11Nb/TiO interface and investigation of TiO based cermet binder phase

    Institute of Scientific and Technical Information of China (English)

    LI Qingkui; ZHONG Hui; GUAN Shaokang; LI Jiang; ZHONG Haiyun

    2005-01-01

    The effect of trace amount of active element Si on the wetting and interface characteristics of 1Cr1 8Ni1 1Nb/TiO was investigated. Based on the results, a new binder phase for TiO based cermets imitated gold materials was developed,and the related mechanisms were studied. The results indicated that there was small wet-ability of the 1Crl8Ni11Nb alloy on TiO, and the interface binding strength of 1Cr1 8Ni1 1Nb/TiO was low. 1.5%Si in 1Cr1 8Ni1 1No could not only make the alloy wet TiO, but also lead to mutual dissolving near the interface, forming high interface binding strength and matching with the thermal expansion coefficient of TiO.

  14. Estudio del desgaste del flanco de carburos recubiertos y cermet durante el torneado de alta velocidad en seco del acero AISI 1045

    Directory of Open Access Journals (Sweden)

    Hernández-González, L. W.

    2011-06-01

    Full Text Available This work deals with the experimental study of the flank wear evolution of two coating carbide inserts and a cermet insert during the dry finishing turning of AISI 1045 steel with 400, 500 and 600 m/min cutting speeds. The results were analyzed using the variance analysis and lineal regression analysis in order to describe the relationship between the flank wear and machining time, obtaining the adjusted model equation. The investigation demonstrated a significant effect of cutting speed and machining time on the flank wear at high speed machining. The three coating layers insert showed the best performance while the two layers insert had the worst behaviour of the cutting tool wear at high cutting speeds.

    El objetivo de este trabajo es el estudio experimental de la evolución del desgaste del flanco respecto al tiempo de dos insertos de carburo recubiertos y un cermet durante el torneado de acabado en seco del acero AISI 1045 con velocidades de corte de 400, 500 y 600 m/min. Los resultados fueron comparados utilizando el análisis de varianza y el análisis de regresión lineal para describir la relación entre el desgaste del flanco y el tiempo de maquinado, obteniéndose la ecuación del modelo ajustado. La investigación demostró un efecto significativo de la velocidad de corte y del tiempo de maquinado en el desgaste del flanco en el maquinado de alta velocidad. El mejor desempeño se obtuvo para el carburo recubierto con tres capas, mientras que el carburo con dos capas sufrió el mayor desgaste a elevadas velocidades de corte.

  15. Electrocatalytic cermet sensor

    Science.gov (United States)

    Shoemaker, Erika L.; Vogt, Michael C.

    1998-01-01

    A sensor for O.sub.2 and CO.sub.2 gases. The gas sensor includes a plurality of layers driven by a cyclic voltage to generate a unique plot characteristic of the gas in contact with the sensor. The plurality of layers includes an alumina substrate, a reference electrode source of anions, a lower electrical reference electrode of Pt coupled to the reference source of anions, a solid electrolyte containing tungsten and coupled to the lower reference electrode, a buffer layer for preventing flow of Pt ions into the solid electrolyte and an upper catalytically active Pt electrode coupled to the buffer layer.

  16. Microstructure and Properties of Micon and Submicron Ti(C,N)-based Cermets%微米级和亚微米级Ti(C,N)基金属陶瓷的组织和性能

    Institute of Scientific and Technical Information of China (English)

    郑勇; 熊惟皓

    2001-01-01

    对用微米级和亚微米级基金属陶瓷的显微组织和性能进行了研究。发现这两类金属陶瓷的显微组织均由三部分组成:芯部为黑色、具有明显包覆层的陶瓷颗粒、芯部为白色、包覆层不明显的陶瓷颗粒和粘结相。但对于亚微米级的金属陶瓷,其芯部为白色的陶瓷颗粒的数目要比微米级的金属陶瓷多,其断裂韧性略有下降,但其抗弯强度要高出许多。另外通过EDA和X射线衍射分析,得到了这两类金属陶瓷显微组织的形成机制。%The microstructure and properties of micron and submicron Ti(C,N)-based cermets were studied in this paper.The microstructures of the two kinds of cermet are composed of a kind of grains with black cores and obvious rim structure,and another kind of grains with cores and unconspicuous rim structure and adhesive phase.For submicron cermet,the grains with white cores,are much more than that in micron cermet,and the properties are higher.In addition,the forming mechanism for the two kinds of cemet is obtained by EDA and Xray diffraction analysis.

  17. Nouveaux revêtements multicouches diamantés nanograins sur cermets WC-Co : étude des phénomènes microstructuraux intervenant aux interfaces lors de l'élaboration

    OpenAIRE

    Faure, Cyril

    2010-01-01

    The combination of good mechanical properties and low specific mass ensures the increasing use of composite materials to reduce the weight of mechanical structures. However, their machining induces premature and random wear of WC-Co cermet cutting-tools. The origin of this study comes from the necessity to protect cutting-tools surfaces by hard and resistant coatings like NCD diamond. Unfortunately, the cobalt found in these cemented carbides catalyses graphite formation at the interface with...

  18. Model-supported interpretation of the electrochemical characteristics of solid oxide fuel cells with Ni/YSZ cermet anodes; Modellgestuetzte Interpretation der elektrochemischen Charakteristik von Festoxid-Brennstoffzellen mit Ni/YSZ-Cermetanoden

    Energy Technology Data Exchange (ETDEWEB)

    Gewies, Stefan

    2009-01-29

    This work presents the development, validation and application of a multiscale model for the detailed description of a solid oxide fuel cell (SOFC) with a Ni/YSZ (nickel/yttria-stabilized zirconia) cermet anode. The aim of the study is the identification of the physico-chemical loss processes, as seen in impedance spectra and polarization curves. The model consists of an elementary kinetic description of the electrochemistry including the development of an electrical double layer at the electrode/electrolyte interface of the cermet anode, a homogenized description of charge and gas-phase transport in the electrodes as well as a macroscopic description of convective and diffusive mass transport in the gas phase above the electrodes. For the rst time this study allows for a complete description of the impedance spectra of a diffusively fuel-supplied cermet anode. By comparing simulations with experiments on symmetrical cells (University of Karlsruhe) three dominant loss processes could be identified. The model was extended to account for the description of segmented SOFCs. In correspondence with experimental data (German Aerospace Center) the simulations show strong gradients in current densities and gas concentrations. (orig.)

  19. Effect of H{sub 2}S on the thermodynamic stability and electrochemical performance of Ni cermet-type of anodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Venkateswara Rao, M.

    2006-11-15

    For SOFCs to be main means of power generation, they should be able to exploit wide variety of fuels. Among Ni-cermets, Ni-YSZ is the state-of-the-art materials for SOFC-anode which is the fuel electrode. But sulphur impurity present in different gaseous fuels (e.g Biogas), depending on its concentration, is highly poisonous to the stability and electrochemical performance of the Ni catalyst in the cermet anodes. Thus in this study the microstructural stability of Ni-YSZ, Ni-CGO and Ni-LSGM cermets in H{sub 2}S-containing hydrogen gas is studied in the intermediate temperature range of SOFC operation. Thermodynamic modelling of Ni-S-O-H quaternary system was performed for the calculation of thermodynamic stability and sulphur-tolerance limit of Ni in the gaseous atmosphere made up of H, O and S. The effect of presence H{sub 2}S in fuel gas, in the concentrations well below the thermodynamic tolerance limit, on the electrochemical performance of the anodes is studied by using model Ni-patterned electrodes on YSZ and LSGM. Thermodynamic modelling of the Ni-S-O-H quaternary was performed by employing CALPHAD methodology. The modelling of Ni-S binary phase diagram was performed by using sublattice models for the non-stoichiometric phases. The optimised binaries of Ni-O, and Ni-H were taken from the literature. The Ni-O-S and Ni-O-H ternaries were extrapolated from the lower order binaries. In Ni-O-S ternary, NiSO{sub 4} is the only ternary compound present. The ternary compounds, Ni(OH){sub 2} and NiOOH in the Ni-O-H ternary were considered as stoichiometric line compounds. The model parameters of the ternary compounds were optimised using the experimental data. The Ni-S-O-H quaternary was calculated by extrapolation method as employed in the CALPHAD methodology. Inorder to understand the H{sub 2}-oxidation mechanism and the role played by the electrolyte in the reaction mechanism, symmetrical cells of Ni-patterned YSZ single crystals with different crystallographic

  20. Enhancing Sulfur Tolerance of Ni-Based Cermet Anodes of Solid Oxide Fuel Cells by Ytterbium-Doped Barium Cerate Infiltration.

    Science.gov (United States)

    Li, Meng; Hua, Bin; Luo, Jing-Li; Jiang, San Ping; Pu, Jian; Chi, Bo; Li, Jian

    2016-04-27

    Conventional anode materials for solid oxide fuel cells (SOFCs) are Ni-based cermets, which are highly susceptible to deactivation by contaminants in hydrocarbon fuels. Hydrogen sulfide is one of the commonly existed contaminants in readily available natural gas and gasification product gases of pyrolysis of biomasses. Development of sulfur tolerant anode materials is thus one of the critical challenges for commercial viability and practical application of SOFC technologies. Here we report a viable approach to enhance substantially the sulfur poisoning resistance of a Ni-gadolinia-doped ceria (Ni-GDC) anode through impregnation of proton conducting perovskite BaCe0.9Yb0.1O3-δ (BCYb). The impregnation of BCYb nanoparticles improves the electrochemical performance of the Ni-GDC anode in both H2 and H2S containing fuels. Moreover, more importantly, the enhanced stability is observed in 500 ppm of H2S/H2. The SEM and XPS analysis indicate that the infiltrated BCYb fine particles inhibit the adsorption of sulfur and facilitate sulfur removal from active sites, thus preventing the detrimental interaction between sulfur and Ni-GDC and the formation of cerium sulfide. The preliminary results of the cell with the BCYb+Ni-GDC anode in methane fuel containing 5000 ppm of H2S show the promising potential of the BCYb infiltration approach in the development of highly active and stable Ni-GDC-based anodes fed with hydrocarbon fuels containing a high concentration of sulfur compounds.

  1. Effect of electrolysis superheat degree on anticorrosion performance of 5Cu/(10NiO-NiFe2O4) cermet inert anode

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    5Cu/(10NiO-NiFe2O4) cermet inert anodes were prepared by cold-pressing and sintering process, and the effect of superheat degree of melting K3AIF6-Na3AlF6-AlF3 on their anticorrosion performance was studied under electrolysis conditions. The results show that, the fluctuation of cell becomes small with increasing of superheat degree, which is helpful to inhibit the formation of cathodic encrustation; the concentration of impurities from inert anode in bath goes up to certain degree, but it is far smaller than those in traditional high-temperature bath. Increasing the superheat degree of melting K3AlF6-Na3AlF6-AlF3 has unconspicuous effect on the contents of impurities in cathodic aluminum. The total mass fractions of Fe, Ni and Cu in aluminum are 15.38% and15.09% respectively under superheat degree of 95 and 195 ℃C. From micro-topography of anode used view, increasing the superheat degree can aggravate corrosion of metal Cu in inert anode, and has negative influence on electrical conductivity of electrode to some extent.

  2. Study on cermet CBN grinding wheels for ultra-precision grinding%一种新型超精磨金属陶瓷CBN砂轮的研究

    Institute of Scientific and Technical Information of China (English)

    陈卫东; 韩云

    2012-01-01

    通过考察不同因素对砂轮锋利性、寿命及加工工件表面粗糙度的影响,优选出了端面超精磨CBN砂轮的制备工艺.通过对比实验,得出最优配比如下:CBN磨料的粒径优选添加40 μm,陶瓷空心球的粒度优选添加240目,其添加量优选体积分数为20%,金属粉的优选体积分数为9%.该配方制备的CBN砂轮的锋利性、寿命及加工工件的表面粗糙度均达到了较好的效果.%By studying main influence factors on wheel sharpness, lifetime and machined surface roughness of workpieces, optimum manufacturing technology of cermet CBN grinding wheel for end ultra-precision grinding was researched. After a series of comparative experiments, optimized manufacturing parameters were obtained as follows; particle size of CBN grits 40 μm; hollow ceramic sphere size 240 meshes with addition amount 20% (volume fraction) ; and volume fraction of metal powder 9%. CBN grinding wheels prepared according to the formula above showed better properties, such as sharpness, lifespan and surface roughness of machined workpieces.

  3. History of ``NANO''-Scale VERY EARLY Solid-State (and Liquid-State) Physics/Chemistry/Metallurgy/ Ceramics; Interstitial-Alloys Carbides/Nitrides/Borides/...Powders and Cermets, Rock Shocks, ...

    Science.gov (United States)

    Maiden, Colin; Siegel, Edward

    History of ``NANO'': Siegel-Matsubara-Vest-Gregson[Mtls. Sci. and Eng. 8, 6, 323(`71); Physica Status Solidi (a)11,45(`72)] VERY EARLY carbides/nitrides/borides powders/cermets solid-state physics/chemistry/metallurgy/ ceramics FIRST-EVER EXPERIMENTAL NANO-physics/chemistry[1968 ->Physica Status Solidi (a)11,45(`72); and EARLY NANO-``physics''/NANO-``chemistry'' THEORY(after: Kubo(`62)-Matsubara(`60s-`70s)-Fulde (`65) [ref.: Sugano[Microcluster-Physics, Springer('82 `98)

  4. EFFECT OF Cu-Ni CONTENT ON THE CORROSION RESISTANCE OF (Cu-Ni)/(10NiO-90NiFe2O4) CERMET INERT ANODE FOR ALUMINUM ELECTROLYSIS

    Institute of Scientific and Technical Information of China (English)

    Z.L. Tian; Y.Q. Lai; J. Li; Y.X. Liu

    2008-01-01

    (Cu-Ni)/(10NiO-9ONiFe2O4 ) cermet inert anodes containing metal Cu-Ni 0,5, 10, 15 and 20 wt pet were prepared and their corrosion resistance to Na3AlF6-Al2O3 melts was investigated. The results indicate that the content of metal Cu-Ni has little effect on the steady-state concentration of Ni in the electrolyte and the values could not be used to effectively differentiate their corrosion resistance. The steady-state concentration of Fe decreases from 304×10-8 to 168×10-6 and that of Cu increases from 21×10-6 to 71×10-6 with the content of metal Cu-Ni increasing from 0 to 20 wt pct. Post-examination shows that metallic phase Cu-Ni is corroded preferentially during electrolysis and many pores are left at the anode surface. Considering the corrosion resistance and electrical conductivity, the cermet containing metal Cu-Ni 5 wt pct should be selected and studied further.

  5. 激光熔覆MoB/CoCr金属陶瓷涂层的微观组织%Microstructure of MoB/CoCr cermet coating by laser cladding

    Institute of Scientific and Technical Information of China (English)

    陈枭; 纪岗昌; 王洪涛; 白小波; 林厚勤; 温雨

    2012-01-01

    MoB/CoCr cermet coating was prepared on 45 steel surface by using 5 kW CO2 laser. Microstructure, composition analysis and microhardness were studied. The results show that MoB/CoCr cermet coating is metallurgically bonded with substrate. The main elements of cladding layer are Mo, Cr and Co, the content of Fe ( wt% ) are increased obviously for diffusing among the alloyed zone. The hardness of the cladding layer is obviously higher than that of the substrate, which achieves the effect of surface strengthening.%采用5 kW CO2激光器在45钢表面激光熔覆制备MoB/CoCr金属陶瓷涂层,对涂层的微观组织、成分分布和显微硬度进行研究。结果表明,MoB/CoCr金属陶瓷涂层组织致密,与基体呈冶金结合。激光熔覆的熔覆区中的主要元素是Mo、Cr和Co,合金化区由于元素互扩散,Fe元素含量明显增加。激光熔覆后MoB/CoCr金属陶瓷涂层的硬度远远大于基体的硬度,起到了表面强化的作用。

  6. Microstructure and Mechanical Properties of Nano-TiN Particle-modified TiC-WC-Mo2C-Ni-Co Cermets%纳米TiN颗粒增强TiC-WC-Mo2C-Ni-Co金属陶瓷的组织和力学性能

    Institute of Scientific and Technical Information of China (English)

    朱晓勇; 许育东; 黄琼; 王雷; 石敏; 苏海林; 于涛; 陈云帮

    2012-01-01

    Nanoparticle-modified cermets are attracting extensive attentions for their exceUent mechanical properties.The experimental preparation,microstructure and mechanical properties of the nanoparticle-modified cermets ale introduced,and the formation of core/rim structure in the cermets is dicussed.The results show that the crystal grains get finer with the increase of M02C content.The cermet has the highest hardness value when the content of Mo2C reaches 10%.%纳米颗粒增强金属陶瓷材料具有优良的力学性能因而受到广泛关注.介绍了纳米颗粒增强金属陶瓷的实验制备、组织和性能,重点论述了微观组织中的芯/壳结构.研究表明,随着Mo2C添加量的增加,金属陶瓷的组织存在着变细的趋势.当Mo2C含量为10%时,金属陶瓷材料硬度出现最大值.

  7. Mo2C对Ti(C,N)基金属陶瓷腐蚀性能的影响%Effect of Mo2C on Corrosion Behavior of Ti(C,N)-based Cermets

    Institute of Scientific and Technical Information of China (English)

    董广彪; 熊计; 郭智兴; 万维财; 易成红

    2012-01-01

    通过静态浸泡腐蚀和动电位极化两种方法,研究了Mo2C对Ti(C,N)基金属陶瓷在NaOH溶液中腐蚀性能的影响.实验结果表明:Ti(C,N)基金属陶瓷的耐蚀性明显优于WC-Co硬质合金;添加Mo2C可以大幅度提高Ti(C,N)基金属陶瓷的机械性能,硬度从91.2到94.0 HRA和抗弯强度从930到1350 MPa,但会降低金属陶瓷的耐蚀性能;由于Mo2C的加入,会使金属陶瓷的动电位极化曲线出现两个钝化区,但是两个钝化区域的电流均未达到真正的钝化电流(10-5 A/cm2),因而这些钝化现象均为伪钝化;在经动电位极化后的试样表面,粘结相Ni和白色的内环相均会被腐蚀,其中内环相为富Mo的(Mo,Ti)(C,N)固溶体,其耐腐蚀性较未溶的Ti(C,N)芯更差.随着Mo2C添加量的提高,内环形相的厚度随之会增加,从而降低了Ti(C,N)基金属陶瓷的耐蚀性能.%The effect of M02C on corrosion behavior of Ti (C,N)-based cermets in NaOH alkali solution was studied by static corrosion and electrochemical corrosion. The results show that the corrosion resistance of Ti(C,N)-based cermets is obviously better than that of cemented carbides. The M02C addition could improve mechanical properties of cermets greatly, as the hardness increases from 91.2 to 94.0 HRA and transverse rupture strength increases from 930 to 1 350 MPa, but it also decreases the corrosion resistance of cermets. As the MojC addition added, there are two passive regions for the polarization curves. But those passive regions are all pseudopassivation which could not reach the real passivation current(10-5 A/cm2). It could be found on electrochemical corrosion surface that the binder Ni and the inner rims are all corroded. The inner rims is (Mo,Ti)(C,N) solid solution which is poor in corrosion resistance. With the increase of Mo2C addition, the thickness of inner rims increases. So the corrosion resistance of Ti(C,N)-based cermets decreases with the Mo2C addition.

  8. 汽车刹车片用复合型金属陶瓷涂层制备及性能研究%Preparation and Property Study of Composite Cermet Coating Used in Automobile Brake Shoes

    Institute of Scientific and Technical Information of China (English)

    侯占祥; 靳清

    2012-01-01

    The Preparation process and application property of composite cermet coating used in automobile brake shoes were studied in this paper. A new type of WC-CoCr10/4 cermet powder that joint R&D with a domestic research institute were selected and the optimized HVOF spraying process were uesd to made coating directly on the braking disc. The study found that, using the composite cermet coating as a braking disc can make its tensile strength up to 75 Mpa above with brake pads, Microhardness can reach 1300 (HV0.3), at the same time, the coating has compact structure and low porosity, which not only improving the wearing resistance and significant extending the life of brake shoes, but also reduce the cost of production,. And the coatings fully meet the practical use requirements and have a broad application prospect.%本文进行了将复合型金属陶瓷涂层用于汽车刹车片的制备工艺与应用性能的初步研究。选用与国内某研究机构联合研制的新型WC—CoCr10/4金属陶瓷粉体作为刹车片材料并采用优化后的HVOF超音速火焰喷涂工艺直接在制动盘上制备,经研究发现,采用该复合涂层作为刹车片可以使其与制动盘之间的拉伸结合强度达到75Mpa以上,显微硬度可达HV0.31300,同时该涂层具有组织致密、孔隙率低等特点,在提高刹车片耐磨性、显著延长使用寿命的同时也降低了生产成本,完全满足实际使用需求,具有广阔的应用前景。

  9. Anodic Corrosion Behavior of NiFe2O4-Based Cermet in Na3AlF6-K3AlF6-AlF3 for Aluminum Electrolysis

    Science.gov (United States)

    Tian, Zhongliang; Lai, Yanqing; Yang, Shu; Li, Jie; Hwang, Jiann-Yang; Liu, Yexiang

    2015-03-01

    A (Cu,Ni)/(10NiO-NiFe2O4) cermet was tested as an inert anode for aluminum electrolysis in Na3AlF6-K3AlF6-AlF3 melt at 1173 K (900 °C), and its corrosion behavior was studied. The results show that the low-temperature Na3AlF6-K3AlF6-AlF3 bath is beneficial, improving the service conditions. With the combined effects of the electrolyte composition and the nascent oxygen during electrolysis, the metal phase (Cu,Ni) at the surface of anode will not be leached preferentially, but be transferred into the aluminates including FeAl2O4, NiAl2O4 and CuAl2O4. This is helpful for the anode to improve its corrosion resistance.

  10. Research on Cutting Performance of Ti(C,N)-based Cermets with WC and Mo_2C Addition%WC和Mo_2C添加对Ti(C,N)基金属陶瓷切削性能的影响

    Institute of Scientific and Technical Information of China (English)

    吴悦梅; 熊计; 陈云; 郭智兴; 范洪远

    2011-01-01

    Mo2C has been used in conventional Ti(C,N)-based cermets to improve its wettability between hard phase and binder phase.Recently,some researchers have attempted to develop Ti(C,N)-based cermets free of Mo.To investigate the effect of replacing Mo2C by WC in conventional Ti(C,N)-based cermets,the cutting performance of cermets with the addition of WC and Mo2C was studied,respectively.Wear morphology of cutting tool was observed by SEM,and element distribution of tool surface was analyzed by EDS.The results showed that the cutting tool life of cermets with WC addition was equal to that with Mo2C addition.When the size of the initial WC powder decreased,the cutting tool life could be prolonged,the zonal tangle chip changed to helix chip,and the chip build-up could be reduced.Diffusion wear,oxidation wear accompanied by abrasive wear were considered to be the main wear mechanisms of the cermets.%传统的Ti(C,N)基金属陶瓷刀具材料广泛采用Mo2C来改善粘结相对硬质相的润湿性,近年来Mo的价格不断上涨,寻找低成本金属代替Mo已成为Ti(C,N)基金属陶瓷的发展趋势。为了探讨WC代替Mo2C添加的可行性及其效果,研究了WC和Mo2C添加对Ti(C,N)基金属陶瓷切削性能的影响,采用电子扫描显微镜(SEM)观察刀具的磨损形貌,通过能谱分析(EDS)分析磨损表面的元素分布,并对刀具的主要磨损机理进行分析。实验结果表明,添加WC的金属陶瓷的切削长度和添加Mo2C的相当,将原始WC粉末粒度细化后,不仅切削

  11. The Study on Machining of Nano-TiN Modified Cermets Cutters based on FEM%基于FEM的纳米TiN改性金属陶瓷刀具的切削性能研究

    Institute of Scientific and Technical Information of China (English)

    何光春

    2011-01-01

    In this paper, nano-TiN modified TiC-based cermets cutters are taken as object investigated.Based on large deformation-strain, increment theory and Lagrangian equation, to establish machining finite element model of Cochcroft & Latham fracture and Archard wear rule. And AISI 1045 steel is used to simulate the cutting process. And obtain the dominating force/temperature/wear graph of nano-TiN modified cermets cutter by changing rake angle, the simulated results is comparatively in agreement with relevant machining theory. And the wear mechanism is analyzed in brief by combining SEM. This study may be able to develop new way for the coming new cutter materials, to expect to aim to shorten researched cycle and lower the cost.%文章以纳米TiN改性金属陶瓷刀具作为研究对象.基于大变形-大应变、增量理论及拉格朗日算法,建立了Cockcroft&Latham断裂分离及磨损准则的有限元模型,并对AISI1045钢进行切削加工模拟.改变刀具角度,得到不同角度纳米TiN改性金属陶瓷刀具切削过程中的主切削力、温度及后刀面磨损变化曲线,模拟结果与相关切削理论比较吻合.结合刀具磨损SEM形貌,简要分析了此刀具磨损机理.文章的研究能够为后期新型刀具材料的研究开辟了新路径,以期到达缩短研制周期,降低成本的目的.

  12. Basic study on cermet fuels

    Energy Technology Data Exchange (ETDEWEB)

    Takano, Kimihide; Sato, Seichi; Ohashi, Hiroshi [Hokkaido Univ., Sapporo (Japan). Faculty of Engineering; Minato, Kazuo; Fukuda, Kosaku

    1996-01-01

    Cesium is a major nuclear fission product which is volatile and corrosive and it is able to interact with fuels, cladding tubes and/or other fission products resulting in productions of various compounds. The presence of those compounds may give rise to physical and chemical interactions between fuels and the cladding tube, resulting in changes in their heat transfer coefficients. In this study, some cesium uranates were prepared in the laboratory. Then, Cs{sub 2}UO{sub 4}, Cs{sub 2}U{sub 2}O{sub 7} and Cs{sub 2}U{sub 4}O{sub 12} were thermodynamically analyzed by phase equilibrium calculation using the calculation code, CHEMSAGE. And physicochemical properties of these compounds were investigated. The reaction conditions for producing the three compounds were determined. The equilibrium diagram revealed that Cs{sub 2}UO{sub 4} is stable in a wider range for the partial pressures of oxygen and cesium than Cs{sub 2}U{sub 2}O{sub 7} or Cs{sub 2}U{sub 4}O{sub 12}. Some orange colored product was obtained from the reaction of Cs{sub 2}CO{sub 3} and U{sub 3}O{sub 8} in an electric furnace and Cs{sub 2}U{sub 2}O{sub 7} but not Cs{sub 2}UO{sub 4} was identified by X-ray diffraction of the product. (M.N.)

  13. INVESTIGATION ON MICROSTRUCTURE OF TiC-Fe CERMETS PREPARED BY SHS/PHIP%SHS/PHIP制备TiC-Fe金属陶瓷的微观组织研究

    Institute of Scientific and Technical Information of China (English)

    张卫方; 韩杰才; 杜善义; 陶春虎; 习年生

    2001-01-01

    The microstructure of TiC-Fe cermets prepared by SHS/PHIP was studied. A thin diffusion layer was found between Fe and TiC. As the Fe content was increased, the thickness of diffusion layer and particle size of TiC were decreased, and the combustion reaction became incomplete since some of the lath structure consisting mainly of C were found in Fe-binder phase of TiC-40Fe. There exists a little of precipitate phase of Fe2Ti in Fe-binder phase. A great deal of dislocation were observed in TiC grains.%对SHS/PHIP技术制备出的TiC-Fe金属陶瓷的微观组织结构进行了分析和研究.结果表明,TiC与Fe之间有一扩散层,随着Fe含量的增加,扩散层厚度和颗粒尺寸减小,且反应趋于不完全,TF40金属陶瓷中发现以石墨为主的板条状组织.在Fe粘结相中发现少量析出相Fe2Ti;TiC晶粒中存在大量位错.

  14. Study on Abrasive Wear Properties of MoB/CoCr Cermet Coating%MoB/CoCr金属陶瓷涂层的磨粒磨损性能研究

    Institute of Scientific and Technical Information of China (English)

    陈枭; 纪岗昌

    2012-01-01

    在310S基体表面采用低压等离子喷涂(LPPS)技术制备MoB/CoCr金属陶瓷涂层.用扫描电镜观察涂层的组织结构:测试了MoB/CoCr涂层的显微硬度和结合强度;用湿式橡胶轮磨粒磨损试验机测试涂层的磨损性能.结果显示:MoB/CoCr涂层组织为层状结构,涂层与310S基体之间、表面涂层与过渡涂层之间结合良好.MoB/CoCr涂层具有较高的硬度值和结合强度,且具有良好的抗磨粒磨损性能.%MoB/CoCr cermet coating was deposited by low pressure plasma spraying (LPPS) on 310S steel. The microstructure of the MoB/CoCr coating was observed by SEM. The microhardness and bonding strength of the MoB/CoCr coating were tested. The abrasive wear properties were evaluated by wet sand rubber wheel tester. The results show that MoB/CoCr coating is dense and has excellent combination with 310S steel substrate. MoB/CoCr coating has high hardness and excellent wear properties.

  15. Effect of Co addition on densification and mechanical properties of 17Ni-(10NiO-NiFe2O4) cermet%Co添加对17Ni-(10NiO-NiFe2O4)金属陶瓷的致密化及力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    林启权; 赵爽; 姜滔; 董文正

    2015-01-01

    为了改善17Ni-(10NiO-NiFe2O4)金属陶瓷惰性阳极中金属相的分布,在原料中添加不同含量的Co,以Co-Ni取代纯Ni作为金属相,采用真空烧结方法制备17(xCo-Ni)-(10NiO-NiFe 2 O 4)金属陶瓷,并研究Co添加量对金属陶瓷物相组成、显微组织、致密度及力学性能的影响。结果表明:烧结样品主要由Co-Ni、NiFe 2 O 4、NiO组成,部分Co与陶瓷基体反应生成CoO与Fe 2 O 3。添加适量Co可以改善金属相在陶瓷相的分布和形貌,使团聚孤立的金属相分布均匀,且部分球状金属相变为长条状金属相;同时,添加适量Co还可以促进烧结,提高试样的致密度。适量Co的添加还能降低晶粒尺寸,大幅提高金属陶瓷材料强度与韧性。当Co质量分数为金属相的20%时,金属陶瓷的综合性能最好,致密度、抗弯强度、断裂韧性及硬度分别达到96.87%、163.65 MPa、8.38 MPa/m1/2和820.81HV。%In order to improve the distribution of metal phase in the 17Ni-(10NiO-NiFe2O4)cermet, 17(xCo-Ni)-(10NiO-NiFe2O4)cermet were prepared by vacuum sintering method using Co-Ni instead of Ni as the metal phase. And the effects of Co content on the phase composition, microstructure, relative density and mechanical properties of the cermet were investigated. The results show that the cermet is composed of Co-Ni, NiFe2O4and NiO, a part of Co reacts with ceramic matrix to form CoO and Fe2O3. The proper addition of Co can significantly improve the distribution and morphology of the metal phase, the agglomerate isolated metal phases can distribute uniformly and a part of spherical metal phases can change to elongated metal phases. Moreover, the proper addition of Co can promote sintering and increase the density of sample. Co addition can refine the grain size and greatly increase the strength and the toughness of cermet. When the mass fraction of Co in metal phase is 20%, the combination properties of sample are the best. The

  16. Microstructure and properties of MoB/CoCr cermet coating on 45 steel prepared by laser cladding%45钢表面激光熔覆MoB/CoCr金属陶瓷覆层的组织与性能

    Institute of Scientific and Technical Information of China (English)

    陈枭; 纪岗昌; 王洪涛; 白小波; 于福义

    2012-01-01

    采用激光熔覆技术在45钢基体表面熔覆MoB/CoCr金属陶瓷覆层,对MoB/CoCr覆层进行X射线衍射(XRD)、扫描电镜(SEM)、能谱(EDS)的微观组织结构分析和对覆层的硬度进行测试。结果表明:熔覆层组织致密,与基体结合牢固且呈冶金结合;熔覆层的主要物相为CoMo2B2和CoMoB,主要的化学成分是Mo、Cr和Co,合金化区中Fe元素的含量明显增加。硬度测试表明熔覆层的硬度值是45钢硬度值的10倍以上。%MoB/CoCr cermet coating was prepared on 45 steel surface by laser cladding. Microstructure of MoB/CoCr coating was characterized by XRD, SEM and EDS,and mierohardness of the coating was also studied. The results show that MoB/CoCr cermet coating with metallurgical bonding to substrate is dense. The main phases of the cladding layer are CoMo2B2and CoMoB, and its main chemical composition is Mo, Cr and Co, the content of Fe increases obviously in the alloying zone of the cladding layer. The hardness of the cladding layer is much higher than that of the substrate.

  17. Stability, characterization and functionality of proton conducting NiO–BaCe{sub 0.85−x}Nb{sub x}Y{sub 0.15}O{sub 3−δ} cermet anodes for IT-SOFC application

    Energy Technology Data Exchange (ETDEWEB)

    Žunić, Milan, E-mail: milan@iq.unesp.br [Instituto de Quimica, UNESP-LIEC, CMDMC, Rua Prof. Francisco Degni, 55, CEP 14800-900, Araraquara, SP (Brazil); Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11000 Belgrade (Serbia); Branković, Goran [Institute for Multidisciplinary Research, University of Belgrade, Kneza Viseslava 1, 11000 Belgrade (Serbia); Basoli, Francesco [Department of Chemical Science and Technologies, University of Rome Tor Vergata, Via Ricerca Scientifica 1, 00133 Rome (Italy); Cilense, Mario; Longo, Elson; Varela, José Arana [Instituto de Quimica, UNESP-LIEC, CMDMC, Rua Prof. Francisco Degni, 55, CEP 14800-900, Araraquara, SP (Brazil)

    2014-10-01

    Highlights: • The influence niobium concentration on properties of anode substrates was investigated. • The cermet anode powders were obtained without any undesirable phases. • Porous anode substrates showed chemical stability in the CO{sub 2} atmosphere. • Conductivity values of reduced anode samples were σ{sup *} > 50 S cm{sup −1}. • Fuel cell tests demonstrated functionality of anode substrates. - Abstract: There are many of properties of anodes based on proton conductors, like microstructure, conductivity and chemical stability, which should be optimized. In this work we were dealing with the influence of niobium on the chemical stability, microstructural and electrical characteristics of proton conducting NiO–BaCe{sub 0.85−x}Nb{sub x}Y{sub 0.15}O{sub 3−δ} (NiO–BCNYx) anodes. Four anode substrates NiO–BCNYx of different Nb concentration were prepared using the method of evaporation and decomposition of solutions and suspensions (EDSS). Sintered anode substrates were reduced and their microstructural and electrical properties were examined before and after reduction as a function of the amount of niobium. Chemical stability tests showed strong influence of Nb amount on the chemical stability of anodes in the CO{sub 2}. Microstructural properties of the anode pellets before and after testing in CO{sub 2} were investigated using X-ray diffraction analysis. Electrical properties of anode samples were examined by impedance spectroscopy measurements and the conductivity values of reduced anodes were more than 50 S cm{sup −1} at 600 °C confirming percolation through Ni particles. Fuel cells were fabricated with aim to examine the functionality of anodes. During the fuel cell test the cell with Ni–BCNY10 anode achieved the highest performance, demonstrating a peak power density of 164 mW cm{sup −2} at 650 °C, which confirmed the functionality of Ni–BCNY anodes.

  18. Carbon-resistant Ni-Zr0.92Y0.08O2-δ supported solid oxide fuel cells using Ni-Cu-Fe alloy cermet as on-cell reforming catalyst and mixed methane-steam as fuel

    Science.gov (United States)

    Hua, Bin; Li, Meng; Luo, Jing-li; Pu, Jian; Chi, Bo; Li, Jian

    2016-01-01

    Two types of anode-supported cell are fabricated by tape casting, screen printing and sintering processes. The first one is a conventional anode supported cell (ASC); and the other, namely CASC, contains an extra layer of Ni-Cu/Ni-Fe alloys-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (NCF-BZCYYb) cermet catalyst on the surface of the anode-support. Using CH4-3 mol. % H2O as the fuel, the initial performance of the CASC is moderately improved, compared with that of the ASC; the power density of the CASC and ASC at 500 mA cm-2 and 800 °C remain stable on the level of 470 mW cm-2 for approximately 11 and 0.8 h, respectively, before cell disintegration caused by carbon formation. The performances of the CASC in the fuel of CH4-33.3 mol. % H2O are significantly increased above the level of the ASC, demonstrating an initial peak power density ranging from 280 to 1638 mW cm-2 at temperatures between 600 and 800 °C and a stable power density of 485 mW cm-2 at 500 mA cm-2 and 800 °C for 48 h. Carbon deposition in the anode region of the tested CASC cell is not detected, as the NCF-BZCYYb is a more active catalyst than the Ni-Zr0.92Y0.08O2-δ (YSZ) anode-support for CH4 steam reforming.

  19. Research on Microstructure and Performance of MoB/CoCr Cermet Coatings Sprayed on 20G Steel Surface%20G钢表面喷涂MoB/CoCr金属陶瓷涂层的组织性能研究

    Institute of Scientific and Technical Information of China (English)

    陈袅; 张仁元; 李风

    2011-01-01

    MoB/CoCr cermet coatings were deposited on 20G steel by low pressure plasma spraying (LPPS). The microstructure and phase composition of coatings were characterized by XRD, SEM and EDAX, and the bond strength and thermal shock resistance performance were studied. The results show that phase component of powder and coating had little change. The coatings are dense and have excellent combination with substrate. The main constituents of coatings remain invariant and the coatings have excellent performance of bond strength and thermal shock resistance. The MoB/CoCr coating has much higer durability after 1080 h immersion test in the molten Al-12.07% Si.%在20G钢换热管表面上利用低压等离子喷涂(UPS)制备MoB/CoCr金属陶瓷涂层.采用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDAX)对涂层的物相组成、微观组织和成分进行了表征,并对涂层的结合强度和抗热震性能进行研究.研究表明:喷涂前后涂层的物相相差不大,涂层为层状结构;涂层与20G基体之间、表面涂层与过渡涂层之间结合良好,涂层致密;涂层具有良好的结合强度和抗热震性能,在熔融AI-12.07% Si中经过1080h腐蚀后,涂层基本保持完好,具有很好的抗熔融铝硅腐蚀性能.

  20. Development of Planar Metal Supported SOFC with Novel Cermet Anode

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Hjelm, Johan; Klemensø, Trine;

    2009-01-01

    SOFC, electrode material from the active anode layer may interdiffuse with the metallic support during sintering. The purpose of this work is to illustrate how the interdiffusion problem can be circumvented by using an alternative anode design based on porous and electronically conducting layers......Metal-supported solid oxide fuel cells are expected to offer several potential advantages over conventional anode (Ni-YSZ) supported cells, such as increased resistance against mechanical and thermal stresses and a reduction in materials cost. When Ni-YSZ based anodes are used in metal supported......, into which electrocatalytically active materials are infiltrated after sintering. The paper presents the recent results on the electrochemical performance and durability of the novel planar metal-supported SOFC design. The results presented in the paper show that the novel cell and anode design has...

  1. Cavitation Erosion of Cermet-Coated Aluminium Bronzes

    Directory of Open Access Journals (Sweden)

    Ion Mitelea

    2016-03-01

    Full Text Available The cavitation erosion resistance of CuAl10Ni5Fe2.5Mn1 following plasma spraying with Al2O3·30(Ni20Al powder and laser re-melting was analyzed in view of possible improvements of the lifetime of components used in hydraulic environments. The cavitation erosion resistance was substantially improved compared with the one of the base material. The thickness of the re-melted layer was in the range of several hundred micrometers, with a surface microhardness increasing from 250 to 420 HV 0.2. Compositional, structural, and microstructural explorations showed that the microstructure of the re-melted and homogenized layer, consisting of a cubic Al2O3 matrix with dispersed Ni-based solid solution is associated with the hardness increase and consequently with the improvement of the cavitation erosion resistance.

  2. Fine Grained Tungsten Claddings for Cermet Based NTP Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In October 2011, NASA initiated the Nuclear Cryogenic Propulsion Stage (NCPS) program to evaluate the feasibility and affordability of Nuclear Thermal Propulsion...

  3. Formation of molybdenum boride cermet coating by the detonation spray process

    Science.gov (United States)

    Yang, Gao; Zu-Kun, Hei; Xiaolei, Xu; Gang, Xin

    2001-09-01

    The effects of the powder particle size and the acetylene/oxygen gas flow ratio during the detonation spray process on the amount of molybdenum phase, porosity, and hardness of the coatings using MoB powder were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), etc. The results show that the presence of metallic molybdenum in the coating results from decomposition of MoB powder during thermal spray. The compositions of the coatings are metallic Mo, MoB, and Mo2B, which are different from the phases of the original powder. The amount of molybdenum phase increases monotonously with the oxygen/acetylene ratio, but the increasing rate for the fine powder is faster than that for the coarse powder. The porosity and hardness of the coating are related to the amount of molybdenum phase. The phase constitution of the coating is discussed.

  4. A Conceptual Multi-Megawatt System Based on a Tungsten CERMET Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jonathan A. Webb; Brian Gross

    2011-02-01

    Abstract. A conceptual reactor system to support Multi-Megawatt Nuclear Electric Propulsion is investigated within this paper. The reactor system consists of a helium cooled Tungsten-UN fission core, surrounded by a beryllium neutron reflector and 13 B4C control drums coupled to a high temperature Brayton power conversion system. Excess heat is rejected via carbon reinforced heat pipe radiators and the gamma and neutron flux is attenuated via segmented shielding consisting of lithium hydride and tungsten layers. Turbine inlet temperatures ranging from 1300 K to 1500 K are investigated for their effects on specific powers and net electrical outputs ranging from 1 MW to 100 MW. The reactor system is estimated to have a mass, which ranges from 15 Mt at 1 MWe and a turbine inlet temperature of 1500 K to 1200 Mt at 100 MWe and a turbine temperature of 1300 K. The reactor systems specific mass ranges from 32 kg/kWe at a turbine inlet temperature of 1300 K and a power of 1 MWe to 9.5 kg/kW at a turbine temperature of 1500 K and a power of 100 MWe.

  5. Selective laser sintering of cermet mixtures Ti and B4C

    Science.gov (United States)

    Filippov, A. A.; Fomin, V. M.; Malikov, A. G.; Orishich, A. M.

    2016-10-01

    The work is dedicated to the creation of a new heterogeneous ceramic-composite materials based on boron carbide and titanium, using a laser, in order to further layer-growing 3D products from these materials. The paper discussed two methods for obtaining ceramic-composite material: laser sintering of boron carbide powder and a metal-melting the powder mixture. We study the microstructure of the samples at various energy process modes. An attempt was made to justify the applicability of the regime used for the cultivation of layered products.

  6. Stainless steel binder for the development of novel TiC-reinforced steel cermets

    Institute of Scientific and Technical Information of China (English)

    Akhtar Farid; Shiju Guo; Xia Yang; Yudong Lian

    2006-01-01

    Steel reinforced TiC composites are an attractive choice for wear resistance and corrosion resistance applications. TiCreinforced 17-4PH maraging stainless matrix composites were processed by conventional powder metallurgy (P/M). TiC-reinforced maraging stainless steel composites with >97% of theoretical density were fabricated. The microstructure, mechanical and wear properties of the composites were evaluated. The microstructure of these composites consisted of spherical and semi-spherical TiC particles.A few microcracks appeared in the composites, showing the presence of tensile stress in the composites produced during sintering.Typical properties, namely, hardness and bend strength were reported for the sintered composites. After heat treatment and aging, the increase of hardness was observed. The increase of hardness was attributed to the aging reaction in the 17-4PH stainless steel. The precipitates appeared in the microstructure and were responsible for the increase in hardness. The specific wear behavior of the composites was strongly dependent on the content of TiC particles, the interparticle spacing, and the presence of hard precipitates in the binder phase.

  7. Microstructural evolution during the combustion synthesis of TiC-Al cermet with larger metallic particles

    International Nuclear Information System (INIS)

    Carbon black powders were incorporated into coarse aluminum and titanium powders, and the mixture was used for a combustion front quenching test. The microstructural evolution in the quenched sample was analyzed with scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). In addition, the combustion temperature and rate were measure, and the phase constituent of the final product was inspected by X-ray diffraction (XRD). The results showed that the combustion reaction started with the melting of the Al particles and formation of Al3Ti around the Ti particles, and it proceeded in a reaction-dissolution-precipitation mechanism. After melting of the Al and formation of Al3Ti, the Ti, especially C particles dissolved into the Al liquid and forming Ti-Al-C solution, as a result, TiC grains precipitated out of the saturated liquid solution. With an increase in temperature, Al3Ti then decomposed and TiC also precipitated from the melt. In the final products, besides TiC particles and Al matrix, a small amount of Al3Ti was also founded. Also, previous results were explained, and a model corresponding to this mechanism was drawn

  8. Phase Evolution during the Sintering of Submicron Ti(C,N)-Based Cermets

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The submicron powder mixtures of TiC-TiN-WC-Mo-C-Ni sintered at 1400℃ or below in vacuum were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. The results showed that Mo2C formed at 800℃ or below. Both WC and Mo2C disappeared at 1200℃, and TiN disappeared at 1250℃. In addition, the variations of lattice constants of the titanium carbonitride and nickel binder phase with sintering temperature were experimentally obtained, and the reason was analyzed.

  9. Fragmentation analysis of alumina-nickel cermets subjected to Hopkinson bar tests at high strain rates; Analisis de la fragmentacion de cermets de alumina-niquel ensayados en Barra Hopkinson a altas velocidades de deformacion

    Energy Technology Data Exchange (ETDEWEB)

    Orgaz, F.; Lecue, E.; Sanchez Herencia, A. J.; Gomez del Rio, T.

    2014-07-01

    A comparative study of the influence of the strain rate on the dynamic mechanical behaviour of an alumina matrix with 15 and 50 % of dispersed nickel is presented. The fragmentation under high speed impact compression loads have been studied using a compression split Hopkinson pressure bar (SHPB). Dense alumina and alumina-nickel composites were processed by slip casting of water based slurries on porous moulds. Samples with the metallic phase dispersed were pre-oxidized to achieve an effective joining interface and sintered under flowing inert atmosphere. The strain rate was determined from the impact experiments. The statistics of the SHPB recovered fragments have been determined and analysed according to the exponential models of Weibull and Rosin y Rammler and the effects of the strain rate on the average fragment size are described according to the existing energy models. Finally the rupture mechanisms of the samples and the sources of fracture have been explored and compared to the quasi static mechanical behaviour of these materials. (Author)

  10. Impact of Reduction Parameters on the Initial Performance and Stability of Ni/(Sc)YSZ Cermet Anodes for SOFCs

    DEFF Research Database (Denmark)

    Ebbehøj, Søren Lyng; Ramos, Tania; Mogensen, Mogens Bjerg

    2012-01-01

    temperatures of 850 °C and 1000 °C was evaluated for tape-cast, thin electrolyte, Nickel/8 mol% Yttria-Stabilized Zirconia (Ni/8YSZ) or (Ni/10Sc1YSZ) symmetric cells. High temperature activation produced the lower Ohmic and polarization resistances related to Triple Phase Boundary (TPB) charge transfer...... processes for Ni/10Sc1YSZ cells. The Ni/8YSZ cells behaved oppositely with respect to reduction temperature. A hypothesis is proposed relating performance to variations in Ni microstructure, Ni/ceramic contacting and extent of TPB resulting from differences in reduction parameters. Further, the performance...

  11. Microwave processing: A potential technique for preparing NiO–YSZ composite and Ni–YSZ cermet

    Indian Academy of Sciences (India)

    Kanchan Lata Singh; Ajay Kumar; Anirudh P Singh; S S Sekhon

    2008-08-01

    In the present study, microwave energy (2.45 GHz) has been used to prepare nickel oxide–yttria stabilized zirconia (NiO–YSZ) composites of composition, NiO–(1 – ) Zr0.9Y0.1O1.95 ( = 0.2, 0.3, 0.4, 0.5 and 0.6), from a precursor obtained by mixing NiO, Y2O3 and monoclinic ZrO2 in their stoichiometric ratio. The composites have been prepared by conventional processing also to compare the products with those of microwave processed products. During comparison, it was observed that NiO–YSZ composites of each composition obtained by microwave processing had cubic phase of YSZ while in the conventionally prepared composites of compositions, = 0.2 and 0.3, monoclinic, tetragonal and cubic phases of zirconia existed instead of its pure cubic phase. The composites were reduced to yield Ni–YSZ.

  12. Spray pyrolytically grown NiAlOx cermets for solar thermal selective absorbers: spectral properties and thermal stability

    Indian Academy of Sciences (India)

    A Bagheri Khatibani; S M Rozati

    2016-02-01

    After deposition of NiAlOx thin films on stainless-steel substrates by the spray pyrolysis technique, various properties of the films were investigated using Fourier transform infrared spectroscopy, UV–visible reflectance spectrophotometry, energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical quantities were determined using reflectance spectra in the relevant spectrum region. At first the optimal substrate temperature was selected and then different nickel to aluminium ratios were examined to find the efficient solar absorber. The SEM revealed changes in morphology due to different molar ratios. The XRD of the selected sample showed a mixture of nickel and nickel oxide phases with the strong presence of substrate peaks and without the presence of alumina phase while in the EDX test the peaks corresponding to O, Al and Ni appeared. Long-term thermal stability study was performed by means of performance criterion concept.

  13. The Use of Molybdenum-Based Ceramic-Metal (CerMet) Fuel for the Actinide Management in LWRs

    International Nuclear Information System (INIS)

    The technical and economic aspects of the use of molybdenum depleted in the isotope 95Mo (DepMo) for the transmutation of actinides in a light water reactor are discussed. DepMo has a low neutron absorption cross section and good physical and chemical properties. Therefore, DepMo is expected to be a good inert matrix in ceramic-metal fuel. The costs of the use of DepMo have been assessed, and it was concluded that these costs can be justified for the transmutation of the actinides neptunium, americium, and plutonium

  14. Effect of working condition on thermal stress of NiFe2O4-based cermet inert anode in aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    LI Jie; WANG Zhi-gang; LAI Yan-qing; LIU Wei; YE Shao-long

    2007-01-01

    Based on the FEA software ANSYS, a model was developed to simulate the thermal stress distribution of inert anode. In order to reduce its thermal stress, the effect of some parameters on thermal stress distribution was investigated, including the temperature of electrolyte, the current, the anode cathode distance, the anode immersion depth, the surrounding temperature and the convection coefficient between anode and circumstance. The results show that there exists a large axial tensile stress near the tangent interface between the anode and bath, which is the major cause of anode breaking. Increasing the temperature of electrolyte or the anode immersion depth will deteriorate the stress distribution of inert anode. When the bath temperature increases from 750 to 970 ℃, the maximal value and absolute minimal value of the 1st principal stress increase by 29.7% and 29.6%, respectively. When the anode immersion depth is changed from 1 to 10 cm, the maximal value and absolute minimal value of the 1st principal stress increase by 52.1% and 65.0%, respectively. The effects of other parameters on stress distribution are not significant.

  15. EFFECT OF STRUCTURAL PARAMETERS ON THE THERMAL STRESS OF A NiFe2O4-BASED CERMET INERT ANODE IN ALUMINUM ELECTROLYSIS

    Institute of Scientific and Technical Information of China (English)

    J. Li; Z.G. Wang; Y. Q. Lai; Y.Y. Wu; S.L. Ye

    2007-01-01

    Inert anode has been a hot issue in the aluminum industry for many decades. With the help of FEA (finite element analysis) software ANSYS, a model was developed to simulate the thermal stress distribution working condition of an inert anode. To reduce its thermal stress,the effect of some parameters on the thermal stress distribution was investigated, including the anode height, the anode radius, the hole depth, the hole radius, and the radius of inner chamfer and outer chamfer. The results showed that in the actual working condition of an inert anode, there existed a large axial tensile stress near the tangent interface between the anode and bath, which was the major cause of anode breaking. Increasing the anode height and reducing the hole depth properly seemed to be beneficial for the stress distribution. With the increase of anode radius, the stress distribution became better first and then deteriorated,the reasonable value was between 0.045 to 0.06m. The hole radius had a significant effect on the stress and a smaller radius would reduce the thermal stress. The effect of the radius of the inner chamfer and the outer chamfer was less than other parameters.

  16. An investigation of the corrosion of WC-Co cermets in CN{sup -}-containing aqueous solutions. Part II: Synchrotron-based high lateral-resolution XPS study

    Energy Technology Data Exchange (ETDEWEB)

    Bozzini, Benedetto [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, via Monteroni, 73100 Lecce (Italy)], E-mail: benedetto.bozzini@unile.it; Dalmiglio, Matteo [Sincrotrone Trieste SCpA, SS14-Km163.5 in Area Science Park, I-34012 Trieste (Italy); De Gaudenzi, Gian Pietro [Films S.p.a., v. Megolo 2, I-28877, Anzola d' Ossola (Italy); D' Urzo, Lucia [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, via Monteroni, 73100 Lecce (Italy); Gregoratti, Luca [Sincrotrone Trieste SCpA, SS14-Km163.5 in Area Science Park, I-34012 Trieste (Italy)

    2009-08-15

    In the literature on the corrosion behaviour of WC-Co hardmetal grades, it has been pointed out that - typically - corrosion resistance in several aqueous environments relies on the formation of pseudo-passivating layers on top of the two-phase material. So far, no detailed space-dependent study has been performed of the local structure and chemistry of such peculiar corrosion-product layers. In this paper, we propose a detailed chemical analysis - performed with a remarkably advanced synchrotron-based photo-electron microscope - of samples whose electrochemical (CV) and spectroelectrochemical (in situ SFG and ERS) characterisation has been published in a companion paper [B. Bozzini, B. Busson, G.P. De Gaudenzi, L. D'Urzo, C. Mele, A. Tadjeddine, Corros. Sci. 49 (2007) 2392-2405].

  17. TiB-Ti基金属陶瓷的燃烧合成%Combustion synthesis of TiB-Ti cermets

    Institute of Scientific and Technical Information of China (English)

    汪建利; 张光胜; 张幸红

    2002-01-01

    通过自蔓延高温燃烧合成, 结合准热等静压工艺 (SHS/PHIP)制备了相对密度超过9 4%的TiB- x Ti基金属陶瓷复合材料, 研究了金属Ti含量对燃烧合成TiB-Ti基金属陶瓷复合材料的影响. 研究结果表明: 随着Ti含量的增加, 绝热温度、燃烧温度和燃烧速度均降低, 反应产物主要由Ti B和Ti两相组成, 部分产物还有TiB2相存在, 产物组织中, TiB相主要有针状、棒状和片状等形态, 增强相的尺寸随Ti含量的增加而减小; 随Ti含量的增加, 产物的抗弯强度、抗拉强度、抗压强度和断裂韧性提高, 且在Ti含量为40%(质量分数)时达到最大值.

  18. SHS-PHIP法制备TiC-Ni(Mo)金属陶瓷%Preparation of TiC-Ni(Mo) Cermet Via SHS-PHIP

    Institute of Scientific and Technical Information of China (English)

    栾振涛; 周丽; 殷凤仕; 李树军

    2003-01-01

    采用Ti粉、碳黑、Ni粉和Mo粉的混合物,通过自蔓延高温合成(SHS)结合准等静压(PHIP)方法制备了TiC-Ni(Mo)金属陶瓷材料.X射线衍射结果表明,材料由TiC相和Ni合金粘结相组成.扫描电镜观察,球形的TiC颗粒较均匀地分布在Ni合金粘结相中,TiC颗粒尺寸约为2~4 μm,在局部较大的TiC颗粒之间存在微孔缺陷.SHS-PHIP法制备的TiC-Ni(Mo)金属陶瓷材料具有良好的致密性和优良的力学性能.

  19. Electron-beam Treatment of Tungsten-free TiC/NiCr Cermet Ⅱ: Structural Transformations in the Subsurface Layer

    Institute of Scientific and Technical Information of China (English)

    Baohai YU; V.E.Ovcharenko; S.G.Psakhie; O.V.Lapshin

    2006-01-01

    The character of structural changes in the surface layer of titanium carbide (TiC) with Ni-Cr alloy binder was investigated theoretically and experimentally after electron-beam treatment of the material surface. The thermal influence of the electron-beam irradiation on the surface layer microstructure of the composite fine-grained material was mathematically analyzed. Quantitative estimations of the depth of the zone in microstructural phase transformations were carried out. The microstructure and concentration profile of Ti distribution in the metallic binder over the cross section of the surface layer with microstructural phase transformations after electron-pulse treatment of the hard metal surface were experimentally investigated.

  20. Ti(C,N)基硬质合金中的润湿性研究%WETTABILITY OF Ti(C,N)-BASED CERMETS

    Institute of Scientific and Technical Information of China (English)

    刘红卫; 陈康华; 吕海波

    2000-01-01

    主要研究(C,N)基硬质合金中不同粘结相Ni-Co、Ni-Co-Mo和Ni-Co-Mo2C与不同TiN/(TiC+TiN)的硬质相Ti(C,N)之间的润湿性.研究表明,当硬质相中TiN/(TiC+TiN)<0.5时,Ni-Co粘结相是最好的,当TiN/(TiC+TiN)≥0.5时,最适合的粘结相为Ni-Co- Mo2C,而Ni-Co-Mo不宜作为Ti(C,N)基硬质合金的粘结相.

  1. Microstructure degradation of cermet anodes for solid oxide fuel cells: Quantification of nickel grain growth in dry and in humid atmospheres

    Science.gov (United States)

    Holzer, L.; Iwanschitz, B.; Hocker, Th.; Münch, B.; Prestat, M.; Wiedenmann, D.; Vogt, U.; Holtappels, P.; Sfeir, J.; Mai, A.; Graule, Th.

    The effects of compositional and environmental parameters on the kinetics of microstructural degradation are investigated for porous Ni/CGO anodes in solid oxide fuel cells (SOFC). Improved methodologies of SEM-imaging, segmentation and object recognition are described which enable a precise quantification of nickel grain growth over time. Due to these methodological improvements the grain growth can be described precisely with a standard deviation of only 5-15 nm for each time step. In humid atmosphere (60 vol.% H 2O, 40% N 2/H 2) the growth rates of nickel are very high (up to 140%/100 h) during the initial period (1000 h) the growth rates decrease significantly to nearly 0%/100 h. In contrast, under dry conditions (97 vol.% N 2, 3 vol.% H 2) the growth rates during the initial period are much lower (ca. 1%/100 h) but they do not decrease over a period of 2000 h. In addition to the humidity factor there are other environmental and compositional parameters which have a strong influence on the kinetics of the microstructural degradation. The nickel coarsening is strongly depending on the gas flow rate. Also the initial microstructures and the anode compositions have a big effect on the degradation kinetics. Thereby small average grain sizes, wide distribution of particle size and high contents of nickel lead to higher coarsening and degradation rates. Whereas the nickel coarsening appears to be the dominant degradation mechanism during the initial period (1000 h) in humidified gas. Thereby the evaporation of volatile nickel species may lead to a local increase of the Ni/CGO ratio. Due to the surface wetting of CGO a continuous layer tends to form on the surface of the nickel grains which prevents further grain growth and evaporation of nickel. These phenomena lead to a microstructural reorganization between 1000 and 2300 h of exposure. This complex pattern of degradation phenomena also leads to a change of the amount of active microstructural sites that are important for catalytic reactions at the pore-nickel interfaces and for electrochemical reactions at the triple phase boundaries (TPB).

  2. Characterization of time-varying macroscopic electro-chemo-mechanical behavior of SOFC subjected to Ni-sintering in cermet microstructures

    Science.gov (United States)

    Muramatsu, M.; Terada, K.; Kawada, T.; Yashiro, K.; Takahashi, K.; Takase, S.

    2015-10-01

    In order to perform stress analyses of a solid oxide fuel cell (SOFC) under operation, we propose a characterization method of its time-varying macroscopic electro-chemo-mechanical behavior of electrodes by considering the time-varying geometries of anode microstructures due to Ni-sintering. The phase-field method is employed to simulate the micro-scale morphology change with time, from which the time-variation of the amount of triple-phase boundaries is directly predicted. Then, to evaluate the time-variation of the macroscopic oxygen ionic and electronic conductivities and the inelastic properties of the anode electrode, numerical material tests based on the homogenization method are conducted for each state of sintered microstructures. In these homogenization analyses, we also have to consider the dependencies of the properties of constituent materials on the temperature and/or the oxygen potential that is supposed to change within an operation period. To predict the oxygen potential distribution in an overall SOFC structure under long-period operation, which determines reduction-induced expansive/contractive deformation of oxide materials, an unsteady problem of macroscopic oxygen ionic and electronic conductions is solved. Using the calculated stress-free strains and the homogenized mechanical properties, both of which depend on the operational environment, we carry out the macroscopic stress analysis of the SOFC.

  3. Enhanced Thermal Stability of W-Ni-Al[subscript 2]O[subscript 3] Cermet-Based Spectrally Selective Solar Absorbers with Tungsten Infrared Reflectors

    OpenAIRE

    Cao, Feng; Kraemer, Daniel; Sun, Tianyi; Lan, Yucheng; Chen, Gang; Ren, Zhifeng

    2014-01-01

    Solar thermal technologies such as solar hot water and concentrated solar power trough systems rely on spectrally selective solar absorbers. These solar absorbers are designed to efficiently absorb the sunlight while suppressing re-emission of infrared radiation at elevated temperatures. Efforts for the development of such solar absorbers must not only be devoted to their spectral selectivity but also to their thermal stability for high temperature applications. Here, selective solar absorber...

  4. Detailed impedance characterization of a well performing and durable Ni:CGO infiltrated cermet anode for metal-supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Klemensø, Trine; Blennow Tullmar, Peter

    2012-01-01

    as a transmission line response could account for the intermediate frequency arc. The PET model enabled a detailed insight into the effect of adding minor amounts of Ni into the infiltrated CGO and allowed an estimation of important characteristics such as the electrochemical utilization thickness of the anode...

  5. Wear Micro-Mechanisms of Composite WC-Co/Cr - NiCrFeBSiC Coatings. Part I: Dry Sliding

    OpenAIRE

    D. Kekes; P. Psyllaki; M. Vardavoulias

    2014-01-01

    The influence of the cermet fraction in cermet/ metal composite coatings developed by High-Velocity Oxyfuel Flame (HVOF) spraying on their tribological behaviour was studied. Five series of coatings, each one containing different proportion of cermet-metal components, prepared by premixing commercially available feedstocks of NiCrFeBSiC metallic and WC-Co/Cr cermet powders were deposited on AISI 304 stainless steel substrate. The microstructure of as-sprayed coatings was characterized by part...

  6. Effect of Carburization on the Mechanical Properties of Biomedical Grade Titanium Alloys

    Institute of Scientific and Technical Information of China (English)

    Yong Luo; Haibo Jiang; Gang Cheng; Hongtao Liu

    2011-01-01

    Titanium cermets were successfully synthesized on the surface of biomedical grade titanium alloys by using sequential carburization method. The mechanical properties such as hardness, fracture toughness and plasticity were measured to estimate the potential application of titanium cermets. The results show that after carburization the surface hardness of titanium cermets was 778 HV, with a significant improvement of 128% compared with that of titanium alloys. In addition, the fracture toughness of titanium cermets was 21.5×106 Pa·m1/2, much higher than that of other ceramics. Furthermore, the analysis of the loading-unloading curve in the nanoindentation test also indicates that the plasticity of titanium cermet reached 32.1%, a relatively high value which illustrates the combination of the metal and ceramics properties. The results suggest that sequential carburization should be an efficient way to produce titanium cermets with hard surface, high toughness and plasticity.

  7. Effects of MoS2 on Properties of Copper-based Cermet Friction Materials%MoS2对铜基金属陶瓷摩擦材料性能的影响

    Institute of Scientific and Technical Information of China (English)

    白同庆; 佟林松; 李东生

    2006-01-01

    研究了MoS2在铜基摩擦材料中的作用,结果表明,作为润滑组元加入的MoS并非以MoS2的形式影响摩擦材料的性能.在烧结过程中MoS2发生了分解反应,分解后的S大部分生成了FeS等硫化物,对材料起润滑作用.随着MoS2含量的增加,材料的耐磨性、稳定系数逐渐提高,而硬度、摩擦系数逐渐降低.

  8. An SFG and ERS investigation of the corrosion of CoW0.013C0.001 alloys and WC-Co cermets in CN--containing aqueous solutions

    International Nuclear Information System (INIS)

    In order to increase the knowledge of the corrosion mechanism, in situ spectroelectrochemical methodologies were employed in the investigation of the electrochemical interface of WC-Co hardmetals. Together with standard cyclic voltammetries (CV), ElectroReflectance Spectroscopy (ERS) and Sum Frequency Generation (SFG) spectroscopy measurements were performed both on a Co-base alloy, simulating the metallic binder of hardmetal composites, and on a model WC-Co system. A cyanide solution, encountered in the gold extraction industry, was employed as electrolyte. Electrochemical cells and experimental apparatuses were designed to allow in situ experiments. CV measurements showed corrosion attack to run at potentials more anodic than -500 mV vs. Ag/AgCl, both for the alloy and the composite. The high reactivity of the alloy in cyanide environment was witnessed by the time-dependence of the surface vibrational (SFG) and electronic (SFG and ERS) properties under cathodic polarisation. Furthermore, SFG measurements highlighted two different adsorbation sites for cyanide ion, probably α- and ε-Co. The WC-Co system showed a pseudo-passivation peak, typical of the corrosion behaviour of this material, due to precipitation of corrosion products. ERS data at 532 nm showed an ennobling of the potential at which the reflectivity increase was recorded

  9. An SFG and ERS investigation of the corrosion of CoW{sub 0.013}C{sub 0.001} alloys and WC-Co cermets in CN{sup -}-containing aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Bozzini, Benedetto [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, v. Monteroni, I-73100 Lecce (Italy)]. E-mail: benedetto.bozzini@unile.it; Busson, Bertrand [CLIO-LCP, Batiment 201P2, Universitaire Paris Sud 11, 91420 Orsay Cedex (France); De Gaudenzi, Gian Pietro [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, v. Monteroni, I-73100 Lecce (Italy); D' Urzo, Lucia [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, v. Monteroni, I-73100 Lecce (Italy); Mele, Claudio [Dipartimento di Ingegneria dell' Innovazione, Universita di Lecce, v. Monteroni, I-73100 Lecce (Italy); Tadjeddine, Abderrahmane [UDIL-CNRS, Batiment 201P1, BP34, 91898 Orsay, Cedex (France)

    2007-05-15

    In order to increase the knowledge of the corrosion mechanism, in situ spectroelectrochemical methodologies were employed in the investigation of the electrochemical interface of WC-Co hardmetals. Together with standard cyclic voltammetries (CV), ElectroReflectance Spectroscopy (ERS) and Sum Frequency Generation (SFG) spectroscopy measurements were performed both on a Co-base alloy, simulating the metallic binder of hardmetal composites, and on a model WC-Co system. A cyanide solution, encountered in the gold extraction industry, was employed as electrolyte. Electrochemical cells and experimental apparatuses were designed to allow in situ experiments. CV measurements showed corrosion attack to run at potentials more anodic than -500 mV vs. Ag/AgCl, both for the alloy and the composite. The high reactivity of the alloy in cyanide environment was witnessed by the time-dependence of the surface vibrational (SFG) and electronic (SFG and ERS) properties under cathodic polarisation. Furthermore, SFG measurements highlighted two different adsorbation sites for cyanide ion, probably {alpha}- and {epsilon}-Co. The WC-Co system showed a pseudo-passivation peak, typical of the corrosion behaviour of this material, due to precipitation of corrosion products. ERS data at 532 nm showed an ennobling of the potential at which the reflectivity increase was recorded.

  10. DENSE TiC-Al2O3-Fe CERMET FABRICATED BY SHS%致密TiC-Al2O3-Fe金属陶瓷的自蔓延高温合成

    Institute of Scientific and Technical Information of China (English)

    张卫方; 韩杰才; 陈贵清; 尹京智; 陶春虎; 杜善义

    2000-01-01

    通过自蔓延高温合成结合准热等静压法(SHS/PHIP)制备出了致密的TiC-Al2O3-20Fe金属陶瓷.研究了延迟时间、高压持续时间、压力等工艺参数对金属陶瓷密实度的影响,分析了金属陶瓷的相组成、微观组织及性能.结果表明,燃烧合成过程中气体的排放和液相的存在是合成密实材料的关键,通过优化工艺合成了密实度为97.7%的TiC-Al2O3-20Fe金属陶瓷.金属陶瓷由TiC、Al2O3和Fe粘结相组成.粘结相Fe与Al2O3之间界面光滑,Fe与TiC之间有一较薄扩散层.TiC-Al2O3-20Fe金属陶瓷的抗弯强度和抗压强度分别为890 MPa和18.4 GPa.

  11. Investigation of TiC-Al2O3-Fe Cermet by SHS%TiC-Al2O3-Fe金属陶瓷的自蔓延高温合成研究

    Institute of Scientific and Technical Information of China (English)

    张化宇; 韩杰才; 张卫方; 杜善义

    1999-01-01

    通过自蔓延高温合成结合准热等静压法(SHS/PHIP)制备出了致密度为97.7%的TiC-Al2O3-20Fe金属陶瓷(TAF20).分析了金属陶瓷的相组成、微观组织及性能.结果表明:金属陶瓷由TiC,Al2O3陶瓷颗粒和Fe粘结相组成;粘结相中Fe与Al2O3之间的界面光滑,与TiC之间有一薄的扩散层;TAF20金属陶瓷的抗弯强度和抗压强度分别为890MPa和18.4GPa.

  12. High-temperature ablation behavior of TiB2-Cu matrix cermets%TiB2-Cu基金属陶瓷高温烧蚀行为研究

    Institute of Scientific and Technical Information of China (English)

    徐丽; 韩杰才; 张幸红; 徐强

    2009-01-01

    为研究TiB2-Cu基金属陶瓷材料的高温烧蚀行为,采用燃烧合成与同时致密化技术(SHS/PHIP)制备了TiB2-40Cu及TiB2-40Cu-8Ni金属陶瓷复合材料,利用电弧风洞试验考察了材料的抗热震和抗烧蚀性能,利用扫描电镜、电子探针及X射线衍射等方法对材料烧蚀前后的微观组织形貌及成分进行了检测.结果表明,试验模型表面均有烧蚀冲刷痕迹,TiB2-40Cu模型由于抗热震性较差,其表面有裂纹出现,TiB2-40Cu-8Ni的质量烧蚀率较TiB2-40Cu的质量烧蚀率低,微观组织分析表明,TiB2-40Cu模型烧蚀面中心区域剖面附近存在沿厚度方向100 μm左右的烧蚀区.TiB2-40Cu复合材料的烧蚀机理为金属相的熔化、化学烧蚀和机械剥蚀.

  13. M02C对Ti(C,N)基金属陶瓷冲刷腐蚀性能的影响%Effect of Mo2C Addition on Erosion-corrosion Property of Ti(C,N)-based Cermets

    Institute of Scientific and Technical Information of China (English)

    廖舟; 梁孟霞; 董广彪

    2014-01-01

    采用传统的粉末冶金烧结工艺制备了4组不同Mo2C含量的Ti(C,N)基金属陶瓷.用洛氏硬度计、金相显微镜和三点弯曲法分别测得试样的硬度、孔隙度及抗弯强度.通过观察发现Ti(C,N)基金属陶瓷的组织呈现典型的芯-环结构,并随Mo2C含量的增加,组织细化明显.对冲刷腐蚀后的试样表面采用SEM、EDS等方式进行研究测试,结果发现Mo2C能提高金属陶瓷的抗冲刷腐蚀性能,但添加过多会降低该性能.

  14. MICROSTRUCTURE AND MECHANICAL PROPERTIES OF Ti(C, N)-BASED CERMET%Ti(C,N)基金属陶瓷的力学性能与显微结构的研究

    Institute of Scientific and Technical Information of China (English)

    何林; 黄传真; 刘玉先; 孙静; 刘含莲

    2003-01-01

    热压烧结制备了不同Mo2C和Cr3C2含量的Ti(C0.7N0.3)-(Ni-Co)-Mo2C-Cr3C2金属陶瓷,对其性能测试表明,低Mo2C,Cr3C2含量材料具有良好力学性能.利用透射电镜、能谱分析和扫描电镜对低Mo2C,Cr3C2含量金属陶瓷显微组织进行了分析.研究表明,材料显微组织中没有发现明显可见的环形相,Mo元素富集在硬质相颗粒边缘附近,Cr元素富集在粘结相中.未完全溶解的Cr3C2分布在粘结相内和相界上抑制了裂纹的扩展,断口上沿晶断裂面弯曲不规整以及穿晶解理条纹较多,这是材料具有较高的断裂韧性的原因.

  15. Research on Preparation, Microstructure and Performance of MoB/CoCr Cermet Coatings%MoB/CoCr金属陶瓷涂层的制备、组织结构及性能研究

    Institute of Scientific and Technical Information of China (English)

    陈枭; 张仁元; 李风

    2009-01-01

    利用低压等离子喷涂(LPPS)制备了MoB/CoCr金属陶瓷涂层.通过X射线衍射(XRD)分析物相组成、扫描电镜(SEM)、能谱(EDAX)对涂层的微观组织和成分进行分析,并对涂层的结合强度和抗热震性能进行研究.研究结果表明:粉末与喷涂后涂层物相差异不大,涂层为层状结构,随压力越高,粉末熔化越充分;涂层与基体结合良好,涂层致密;涂层喷涂后主要成分保持不变,且具有良好的结合强度和抗热震性能,经过1080 h熔融Al-12.07%Si腐蚀后,涂层完好,具有很好的抗腐蚀性能.

  16. Effect of TiB2 on microstructure of TiC-based cermet%TiB2对TiC基金属陶瓷显微组织的影响

    Institute of Scientific and Technical Information of China (English)

    李鹏; 曾晓雁; 熊惟皓

    2005-01-01

    研究了TiB2对TiC基金属陶瓷显微组织的影响.试验发现1420℃下烧结90min后,TiC基金属陶瓷的硬质相颗粒明显长大.分析表明,TiB2在高温下能够与TiC基金属陶瓷中的Mo反应生成MoB,并主要分布于硬质相表面的环形相中.硬质相的长大可能与MoB导致的液相不足和硬质相颗粒接触长大有关.

  17. Ni-YSZ solid oxide fuel cell anode behavior upon redox cycling based on electrical characterization

    DEFF Research Database (Denmark)

    Klemensø, Trine; Mogensen, Mogens Bjerg

    2007-01-01

    Nickel (Ni)—yttria-stabilized zirconia (YSZ) cermets are a prevalent material used for solid oxide fuel cells. The cermet degrades upon redox cycling. The degradation is related to microstructural changes, but knowledge of the mechanisms has been limited. Direct current conductivity measurements...

  18. SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel joints prepared by dynamic diffusion bonding: Microelectrochemical studies in 0.6 M NaCl solution

    International Nuclear Information System (INIS)

    Corrosion of SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel interfaces was investigated in 0.6 M NaCl solution using an electrochemical microcell, which enables local electrochemical characterization at the micrometer scale. Two pieces of steel, one with a WC-Co coating covered with Ni (12 μm) and Cu (5 μm) layers, and the other with a Ni (15 μm) layer, were welded by dynamic diffusion bonding. A WC-Co coating was applied to the steel by the high velocity oxygen-fuel process, and Ni-Cu and Ni layers by electroplating. Polarization curves were recorded using an electrochemical microcell. Different regions of welded samples were investigated, including steel, cermet coating, and steel/cermet and steel/Ni-Cu-Ni/cermet interfaces. Optical and electronic microscopes were employed to study the corroded regions. Potentiodynamic polarization curves obtained using the microcell revealed that the base metal was more susceptible to corrosion than the cermet. In addition, cermet steel/cermet and steel/Ni-Cu-Ni/cermet joints exhibited different breakdown potentials. Steel was strongly corroded in the regions adjacent to the interfaces, while the cermet was less corroded. Iron oxides/hydroxides and chloride salts were the main corrosion products of steel. After removal of the superficial layer of corrosion products, iron oxides were mainly observed. Chloride ions were detected mainly on a copper-enriched layer placed between two Ni-enriched layers.

  19. SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel joints prepared by dynamic diffusion bonding: Microelectrochemical studies in 0.6 M NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Andreatta, Francesco, E-mail: francesco.andreatta@uniud.i [Dipartimento di Scienze e Tecnologie Chimiche, Universita Degli Studi di Udine, Via del Cotonificio 108, 33100 Udine (Italy); Matesanz, Laura [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid (Spain); Akita, Adriano H. [UNESP, Instituto de Quimica, CP 355, 14800-900 Araraquara, SP (Brazil); Paussa, Luca; Fedrizzi, Lorenzo [Dipartimento di Scienze e Tecnologie Chimiche, Universita Degli Studi di Udine, Via del Cotonificio 108, 33100 Udine (Italy); Fugivara, Cecilio S. [UNESP, Instituto de Quimica, CP 355, 14800-900 Araraquara, SP (Brazil); Gomez de Salazar, Jose M. [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica, Facultad de Ciencias Quimicas, Universidad Complutense de Madrid (Spain); Benedetti, Assis V. [UNESP, Instituto de Quimica, CP 355, 14800-900 Araraquara, SP (Brazil)

    2009-12-30

    Corrosion of SAE 1045 steel/WC-Co/Ni-Cu-Ni/SAE 1045 steel interfaces was investigated in 0.6 M NaCl solution using an electrochemical microcell, which enables local electrochemical characterization at the micrometer scale. Two pieces of steel, one with a WC-Co coating covered with Ni (12 mum) and Cu (5 mum) layers, and the other with a Ni (15 mum) layer, were welded by dynamic diffusion bonding. A WC-Co coating was applied to the steel by the high velocity oxygen-fuel process, and Ni-Cu and Ni layers by electroplating. Polarization curves were recorded using an electrochemical microcell. Different regions of welded samples were investigated, including steel, cermet coating, and steel/cermet and steel/Ni-Cu-Ni/cermet interfaces. Optical and electronic microscopes were employed to study the corroded regions. Potentiodynamic polarization curves obtained using the microcell revealed that the base metal was more susceptible to corrosion than the cermet. In addition, cermet steel/cermet and steel/Ni-Cu-Ni/cermet joints exhibited different breakdown potentials. Steel was strongly corroded in the regions adjacent to the interfaces, while the cermet was less corroded. Iron oxides/hydroxides and chloride salts were the main corrosion products of steel. After removal of the superficial layer of corrosion products, iron oxides were mainly observed. Chloride ions were detected mainly on a copper-enriched layer placed between two Ni-enriched layers.

  20. Wear Micro-Mechanisms of Composite WC-Co/Cr - NiCrFeBSiC Coatings. Part I: Dry Sliding

    Directory of Open Access Journals (Sweden)

    D. Kekes

    2014-12-01

    Full Text Available The influence of the cermet fraction in cermet/ metal composite coatings developed by High-Velocity Oxyfuel Flame (HVOF spraying on their tribological behaviour was studied. Five series of coatings, each one containing different proportion of cermet-metal components, prepared by premixing commercially available feedstocks of NiCrFeBSiC metallic and WC-Co/Cr cermet powders were deposited on AISI 304 stainless steel substrate. The microstructure of as-sprayed coatings was characterized by partial decomposition of the WC particles, lamellar morphology and micro-porosity among the solidified splats. Tribological behavior was studied under sliding friction conditions using a Si3N4 ball as counterbody and the friction coefficient and volume loss were determined as a function of the cermet fraction. Microscopic examinations of the wear tracks and relevant cross sections identified the wear mechanisms involved. Coatings containing only the metallic phase were worn out through a combination of ploughing, micro-cracking and splat exfoliation, whilst those containing only the cermet phase primarily by micro-cracking at the individual splat scale. The wear mechanisms of the composite coatings were strongly affected by their randomly stratified structure. In-depth cracks almost perpendicular to the coating/ substrate interface occurring at the wear track boundaries resulted in cermet trans-splat fracture.

  1. Relationships between structures and performance of SOFC anodes

    DEFF Research Database (Denmark)

    Klemensø, Trine; Mogensen, Mogens Bjerg; Jacobsen, Torben

    The nickel-YSZ cermet of the state-of-the-art anode-supported solid oxide fuel cell (SOFC) degrades upon redox cycling. The degradation is a critical issue for the commercialization of the technology. Nickel-YSZ cermets with variable composition and microstructure were examined during redox cycling...... will be required to discover the full potential of the application of additives. The future work will be empirically based, or include detailed descriptions of the relationships between microstructural parameters and the cermet bulk properties....

  2. Platinum containing amorphous hydrogenated carbon (a-C:H/Pt) thin films as selective solar absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Yung-Hsiang; Brahma, Sanjaya [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Tzeng, Y.H. [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Ting, Jyh-Ming, E-mail: jting@mail.ncku.edu.tw [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan (China)

    2014-10-15

    We have investigated a double-cermet structured thin film in which an a-C:H thin film was used as an anti-reflective (AR) layer and two platinum-containing amorphous hydrogenated carbon (a-C:H/Pt) thin films were used as the double cermet layers. A reactive co-sputter deposition method was used to prepare both the anti-reflective and cermet layers. Effects of the target power and heat treatment were studied. The obtained films were characterized using X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy. The optical absorptance and emittance of the as deposited and annealed films were determined using UV–vis-NIR spectroscopy. We show that the optical absorptance of the resulting double-cermet structured thin film is as high as 96% and remains to be 91% after heat treatment at 400 °C, indicating the thermal stability of the film.

  3. Immersion pyrometer

    International Nuclear Information System (INIS)

    A protective sheath for a temperature sensing device is described comprising: (a) a metal tube having one closed end to provide a cavity for a temperature sensing device; (b) a series of protective layers comprising at least two cermet layers consisting essentially of Al/sub 2/O/sub 3/-Cr/sub 2/O/sub 3/-Mo covering the outer surface of the metal tube, the concentration of molybdenum in the at least two cermet layers decreasing in proceeding from the inner to the outer layers, and each of the cermet layers having a porosity of from about 4% to about 33%; (c) a ceramic layer of substantially pure Al/sub 2/O/sub 3/-Cr/sub 2/O/sub 3/ covering the outermost of the at least two cermet layers, the ceramic layer having a porosity of from about 4% to about 33%

  4. Internal reforming development for solid oxide fuel cells

    International Nuclear Information System (INIS)

    Internal reforming of natural gas within a solid oxide fuel cell (SOFC) is expected to make it a more efficient system for the production of electrical power. Nickel-zirconia cermets are prime candidate material for use as the anode in an SOFC. This paper reports four procedures used to prepare 16 nickel-zirconia cermets: tape casting, slurry, incorporation of pore formers, and granulation. The resultant cermets had nickel contents from 50% to 80%,porosities from 14% to 66%, and mean pore sizes of 0.25--1.8 μm. The catalytic behavior of two cermets was determined in a continuously stirred tank reactor at atmospheric pressure over a temperature range of 800--1000 degrees C and steam-to-hydrocarbon ratios of 2--8 mol/mol using pure methane as the feed. The data support the reaction being first order with respect to methane and -1.25 for steam

  5. Properties of porous FeAlO/FeAl ceramic matrix composite influenced by mechanical activation of FeAl powder

    Indian Academy of Sciences (India)

    V Usoltsev; S Tikhov; A Salanov; V Sadykov; G Golubkova; O Lomovskii

    2013-12-01

    Porous ceramic matrix composites FeAlO/FeAl with incorporated metal inclusions (cermets) were synthesized by pressureless method, which includes hydrothermal treatment of mechanically alloyed FeAl powder followed by calcination. Their main structural, textural and mechanical features are described. Variation of FeAl powder alloying time results in non-monotonous changes of the porosity and mechanical strength. Details of the cermet microstructure and its relation to the mechanical properties are discussed.

  6. Fabrication of Dispersed CERamic-CERamic and Ceramic-METallic pellets for the Transmutation of Actinides

    Science.gov (United States)

    Fernández, A.; Haas, D.; Konings, R. J. M.; Somers, J.

    2003-07-01

    This paper describes the development of fabrication technology for target materials to be used in irradiation experiments, in the PHENIX and HFR reactors. Several target concepts will be tested: micro- as well as macrodispersed composites of (Am,Y,Zr)O2 in MgO (cercer) and macrodispersed composites of (Pu,Y,Zr)O2 in Stainless Steel (cermet) material. Results of the completed fabrication campaigns for cermet and cercer will be presented.

  7. Development of low enrichment MTR fuel at Dounreay

    International Nuclear Information System (INIS)

    Work up to October 1983 on the development of a manufacturing route for the manufacture of low enriched fuel at Dounreay concentrated on the roll-bonding method of plate manufacture. Both U-Al alloy and U3O8-Al cermet elements at 45% enrichment have been irradiated and the fabrication of 20% enriched U3O8-Al cermet elements is in hand. (author). 3 refs, 2 tabs

  8. Preparation of anode-electrolyte structures using graphite, sodium bicarbonate or citric acid as pore forming agents for application in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Paz Fiuza, Raigenis da; Silva, Marcos Aurelio da; Guedes, Bruna C.; Pontes, Luiz A.; Boaventura, Jaime Soares [UFBA, Salvador, Bahia (Brazil). Energy and Materials Science Group

    2010-07-01

    Cermets based on Ni supported on YSZ or GDC were prepared for use as anode in direct reform SOFCs. NaHCO3 (Na-Ni-YSZ and Na-Ni-GDC) or citric acid (Ac-Ni-YSZ and Ac-Ni-GDC) were used as pore forming agents (PFAs). The SOFC anode was also prepared using graphite (G-Ni-YSZ and G-Ni-GDC) as PFA for the purposes of comparison. The testing unitary SOFC, planar type, was made by pressing the anode-electrolyte assembly, followed by sintering at 1500 C. After this, LSM (lanthanum and strontium manganite) paint was used for the cathode deposition. The powdered cermets were evaluated in ethanol steam reforming at 650 C. The ethanol conversion was 84% and 32% for cermets Na-Ni-YSZ and G-Ni-YSZ, respectively and the selectivity to H{sub 2} was 32 and 20% for the two cermets, respectively. The Na-Ni-YSZ cermet was ten times more resistant to carbon deposition than the G-Ni-YSZ cermet. SEM micrographs of the anode-electrolyte assembly showed that the use of NaHCO{sub 3} as PFA created a well formed interface between layers with homogeneously distributed pores. In contrast, graphite as PFA formed a loose interface between anode and electrolyte. The performance of the unitary SOFC was evaluated using ethanol, hydrogen or methane as fuel. The cell operated well using any of these fuels; however, they exhibited different electrochemical behavior. (orig.)

  9. O processo de infiltração em ferramentas de perfuração de rochas com o uso dos pós de tungstênio e carboneto de tungstênio: as características e resultados da microestrutura e dureza do cermet

    Directory of Open Access Journals (Sweden)

    Luis Antonio Ccopa Ybarra

    2009-01-01

    Full Text Available The process of infiltration for manufacturing of rock drilling tools (crown analyzed three process with the utilization of the three powders (matrix, two containing tungsten carbides and one containing tungsten particles, on the microstructure and hardness of a hard metal for rock drilling tool (crown were investigated. The crown samples were prepared by the infiltration technique, where the compacted matrix powder in a graphite mold, assembled with a steel shank, was infiltrated by a copper alloy in order to consolidate the hard metal and to join it with the steel shank. The powders and/ or the cross-sections of the hard metals were characterized by chemical analysis, X-ray diffraction, particle size analysis, density, optical and scanning electron microscopy, energy dispersive spectroscopy, and differential thermal analysis. Beside the predominant phases, tungsten carbide and/or tungsten, the powders presented a small fraction of metallic particles. The results of microstructural analysis of hard metals were correlated with the chemical, phase, particle size and morphology, and compressibility characteristics of the powders investigated. Also were determinate the micro and macrohardness of the hard metals and realized the microstructural analysis on the region of the interface between the hard metals and the steel shank and also difference of temperature on process of infiltration on each matrix powder.

  10. Effect of copper content on the microstructures and properties of TiB2 based cermets by SHS%铜含量对燃烧合成TiB2-Cu基金属陶瓷组织和性能的影响

    Institute of Scientific and Technical Information of China (English)

    徐强; 张幸红; 韩杰才; 赫晓东

    2005-01-01

    利用自蔓延高温燃烧合成结合准热等静压技术制备了不同Cu含量的TiB2-Cu基金属陶瓷.为了得到金属粘结剂的最佳含量,研究了Cu含量对TiB2-Cu基金属陶瓷热力学、微观组织和性能的影响.在Ti-B-Cu体系的燃烧合成过程中,可能存在TiB2、TiB和TiCu三个相.热力学计算结果表明TiB2是最稳定的相.随着Cu含量的增加,TiB2-Cu基金属陶瓷的绝热温度(Tad)和燃烧温度(Tc)逐渐降低.燃烧温度会影响产物中陶瓷相的形貌,TiB2颗粒的尺寸随金属含量的增加而减小.TiB,-Cu基金属陶瓷的硬度(HRA)和弯曲强度随着Cu含量的增多均呈现先增加后降低的趋势,最大值分别对应20wt.%和40wt.%的Cu含量.随Cu含量的增加,TiB2-Cu基金属陶瓷的孔隙率由于金属Cu良好的流动性而呈下降趋势,断裂韧性则呈逐渐上升的趋势.材料的韧化机制为裂纹尖端塑性钝化机制和裂纹偏转机制.TiB2-Cu基金属陶瓷的最佳金属粘结剂含量位于40wt.%~50wt.%.

  11. Orthogonal optimization of process parameter during TiC-TiB2/Cu cermets combustion synthesis%TiC-TiB2/Cu金属陶瓷燃烧合成及工艺参数的正交优化

    Institute of Scientific and Technical Information of China (English)

    朱春城; 林红; 李翀; 李庆芬

    2007-01-01

    利用正交试验对SHS/PHIP工艺制备TiC-TiB2/Cu复合材料的工艺进行了研究,通过采用正交设计、试验和计算,分析了延迟时间、保压时间和加压压力三个因素对合成材料致密度的影响规律,通过扫描电镜对合成材料的微观组织进行了观测.研究结果表明,最佳工艺参数为:延迟时间7 s;保压时间10 s;加压压力180 MPa.

  12. Preparation of large-scale TiB2-Cu-Ni cermet by combustion synthesis+pseudo hot isostatic pressing%大尺寸TiB2-Cu-Ni金属陶瓷块体的燃烧合成及准热等静压致密化

    Institute of Scientific and Technical Information of China (English)

    徐强; 张幸红; 张学忠; 韩杰才

    2002-01-01

    利用燃烧合成结合准热等静压(PHIP)技术成功制备了直径为240 mm的大尺寸TiB2-Cu-Ni金属陶瓷,对合成产物进行了X射线衍射(XRD)、扫描电镜(SEM)和力学性能等实验研究.XRD结果表明反应产物中只有TiB2和(Cu,Ni)两相.SEM分析发现增强相TiB2陶瓷颗粒已经形成骨架状,其间为(Cu,Ni)基体相,TiB2颗粒形貌为近等轴状,尺寸细小且较均匀.合成产物的致密度为94.2%,弯曲强度和断裂韧性分别达到599.4 MPa和12.56 MPa*m1/2.

  13. SHS/PHIP技术制备TiC-Al2O3-Fe金属陶瓷及其微观组织分析%Microstructure of the TiC-Al2O3-Fe cermets fabricated by SHS/PHIP

    Institute of Scientific and Technical Information of China (English)

    张卫方; 韩杰才; 张化宇; 杜善义

    1999-01-01

    采用SHS/PHIP技术制备出了致密的TiC-Al2O3-Fe金属陶瓷.分析了合成产物的微观组织结构.结果表明,随着金属Fe相的加入,TiC颗粒尺寸变小,颗粒趋于均匀,且消除了TiC与Al2O3颗粒之间的微孔.粘结相中Fe与Al2O3之间的界面光滑,与TiC之间有一薄的扩散层.Fe粘结相中有少量胞状有序结构,它可能是以Fe3Al为基的DO3型合金相.由于SHS/PHIP过程中的快速加压,合成产物的TiC颗粒中存在高密度位错.

  14. Effect of the Content of Mo2 C on the Mechanical Properties and Microstructure of Ti(C,N) Based Cermet%Mo2C含量对Ti(C,N)基陶瓷力学性能和显微结构的影响

    Institute of Scientific and Technical Information of China (English)

    何林; 黄传真; 黄勤; 宋世学; 王随莲; 艾兴

    2003-01-01

    采用热压烧结工艺制备了添加微量Cr3C2的Ti(C0.5N0.5)-(Ni-Co)-Mo2C-Cr3C2系Ti(C,N)基金属陶瓷.分析三种不同Mo2C含量材料的力学性能、断口形貌和磨削表面压痕裂纹扩展情况,研究表明:材料的断裂均以沿晶断裂为主;材料的抗弯强度与Rim相有关,8wt%Mo2C含量的金属陶瓷Rim相厚度适中,抗弯强度高;1.6wt%Mo2C含量的金属陶瓷的扩展裂纹短,裂纹扩展发生偏转,断裂韧性高.

  15. Co-Ni-NiFe2O4金属陶瓷的制备及抗氧化性研究%THE PREPARATION OF Co-Ni-NiFe2O4 CERMET AND STUDY OF ANTI-OXIDATION

    Institute of Scientific and Technical Information of China (English)

    王俊茹; 李玉胶; 朱春城

    2009-01-01

    采用传统的粉末冶金技术及真空固相烧结的方法,制备出了Co-Ni-NiFe2O4金属陶瓷惰性阳极材料,通过研究确定了制备NiFe2O4粉体及真空固相烧结Co-Ni-NiFe2O4金属陶瓷的合理工艺.实验表明:Co-Ni-NiFe2O4金属陶瓷在960℃条件下的氧化动力学曲线近似符合抛物线规律,NiFe2O4含量越多,试样的抗氧化性越强;并且在高温氧化后,氧化膜在生长过程中产生明显的择优取向.

  16. Elaboration et étude de l'oxydation à haute température d'un cermet dense constitué de particules d'acier inoxydable 304L dispersées dans une matrice de zircone yttriée.

    OpenAIRE

    Tarabay, Jinan

    2013-01-01

    Ceramic matrix composite dispersed with metallic particles, called M(p)-CMC(s), are being developed for optimizing several functions of industrial components in severe atmospheres at high temperature.The corrosion of a model M(p)-CMC(s), based on 304L stainless steel and yttrium doped zirconia (304L(p)-ZrO2(s); 40%/60% in volume) is studied and compared with the oxidation behaviour of the stainless steel powders. The oxidation behaviour of the model 304L(p)-ZrO2(s) composite produced by powde...

  17. Microstructure and Properties of TiCN-based Functionally Graded Cermet Fabricated by Microwave Assisted Nitriding Sintering%微波辅助氮化烧结制备TiCN基功能梯度金属陶瓷的组织与性能

    Institute of Scientific and Technical Information of China (English)

    唐思文; 苏闯南; 肖雄; 陈宇强; 李鹏南; 刘德顺

    2015-01-01

    采用微波加热氮化烧结法制备了TiCN基梯度功能金属陶瓷,运用超景深显微镜、带有能谱的电子探针和扫描电镜分析了材料的微观组织和成分,研究了烧结温度对材料微观组织和力学性能的影响.结果表明:随烧结温度的升高,材料的力学性能先升高后降低.在1500℃获得较高的综合力学性能,分别为弯曲强度1456MPa,硬度90.7HRA,断裂韧性10.06 MPa·m1/2.材料的韧化机制为细晶强韧化,裂纹偏转,裂纹桥接.在所制备的金属陶瓷基体中,发现了一种新的芯-环结构,这种结构对材料力学性能的提高具有显著作用.

  18. Analysis of space systems for the space disposal of nuclear waste follow-on study. Volume 2. Technical report

    Energy Technology Data Exchange (ETDEWEB)

    None

    1982-01-01

    Some of the conclusions reached as a result of this study are summarized. Waste form parameters for the reference cermet waste form are available only by analogy. Detail design of the waste payload would require determination of actual waste form properties. The billet configuration constraints for the cermet waste form limit the packing efficiency to slightly under 75% net volume. The effect of this packing inefficiency in reducing the net waste form per waste payload can be seen graphically. The cermet waste form mass per unit mass of waste payload is lower than that of the iodine waste form even though the cermet has a higher density (6.5 versus 5.5). This is because the lead iodide is cast achieving almost 100% efficiency in packing. This inefficiency in the packing of the cermet results in a 20% increase in number of flights which increases both cost and risk. Alternative systems for waste mixes requiring low flight rates (technetium-99, iodine-129) can make effective use of the existing 65K space transportation system in either single- or dual-launch scenarios. A comprehensive trade study would be required to select the optimum orbit transfer system for low-launch-rate systems. This study was not conducted as part of the present effort due to selection of the cermet waste form as the reference for the study. Several candidates look attractive for both single- and dual-launch systems (see sec. 4.4), but due to the relatively small number of missions, a comprehensive comparison of life cycle costs including DDT and E would be required to select the best system. The reference system described in sections 5.0, 6.0, 7.0, and 8.0 offers the best combination of cost, risk, and alignment with ongoing NASA technology development efforts for disposal of the reference cermet waste form.

  19. Thermal Performance of an Annealed Pyrolytic Graphite Solar Collector

    Science.gov (United States)

    Jaworske, Donald A.; Hornacek, Jennifer

    2002-01-01

    A solar collector having the combined properties of high solar absorptance, low infrared emittance, and high thermal conductivity is needed for applications where solar energy is to be absorbed and transported for use in minisatellites. Such a solar collector may be used with a low temperature differential heat engine to provide power or with a thermal bus for thermal switching applications. One concept being considered for the solar collector is an Al2O3 cermet coating applied to a thermal conductivity enhanced polished aluminum substrate. The cermet coating provides high solar absorptance and the polished aluminum provides low infrared emittance. Annealed pyrolytic graphite embedded in the aluminum substrate provides enhanced thermal conductivity. The as-measured thermal performance of an annealed pyrolytic graphite thermal conductivity enhanced polished aluminum solar collector, coated with a cermet coating, will be presented.

  20. Investigation of the Corrosion Behaviors of HVOF-Sprayed Carbide Cernet Coatings in Molten Al-Zn-Si Alloy Bath

    Institute of Scientific and Technical Information of China (English)

    JIANG Zhen-hua; TAN Xing-hai; ZHANG Yue-gang; SUN Jia-shu

    2004-01-01

    In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.

  1. Properties and microstructure of NiO/SDC materials for SOFC anode applications

    Institute of Scientific and Technical Information of China (English)

    CHENG Jigui; DENG Liping; ZHANG Benrui; SHI Ping; MENG Guangyao

    2007-01-01

    NiO/SDC composites and Ni/SDC cermets for solid oxide fuel cell (SOFC) anode applications were prepared from nickel oxide (NiO) and samaria doped ceria (SDC) powders by the powder metallurgy process. The physical and mechanical properties, as well as the microstructure of the NiO/SDC composites and the Ni/SDC cermets were investigated. It is shown that the sintering temperature of the NiO/SDC composites and NiO content plays an important role in determining the microstructure and properties of the NiO/SDC composites, which, in turn, influences the microstructure, electrical conductivity, and mechanical properties of the Ni/SDC cermets. The present study demonstrated that composition and tprocess parameters must be appropriately selected to optimize the microstructure and the properties of NiO/SDC materials for solid oxide fuel cell applications.

  2. Tungsten carbide coatings with different binders prepared by low power plasma spray system

    Institute of Scientific and Technical Information of China (English)

    GAO Yang; M.F.Morks; FU Ying-qing

    2004-01-01

    Thermal spraying of cermet coatings is widely used for protection of machining parts against wear and corrosion. These coatings consist of WC particles in metal binders such as Co, Cr and Ni. Three kinds of WC powders with different metal binders (Co, NiCr and CoCr) were sprayed by low power plasma spray system on Al-Si-Cu alloy substrate. Fundamental aspects of sprayed cermet coatings, including (i) the effects of binder type on the coating structure, (ii) the hardness and (iii) the microstructure, were investigated. All cermet coatings have the same phase structure such as WC and W2 C. However, the intensities of these phases are different in each coating, mainly due to the difference in solidification rate in each case. Moreover, the hardness measurements are found to be different in each coating. The results show that, binder type has a significant effect on the physical and mechanical properties of the sprayed coatings.

  3. Fracture toughness of a nanoscale WC-Co tool steel

    International Nuclear Information System (INIS)

    Tungsten carbide tool steels, comprising WC particles with 6.7--25wt% Co distributed in the interparticle regions as a quasi-continuous binder phase, can be considered as WC-Co composites. The fracture toughness of such WC-Co composites is dependent on the volume fraction, contiguity and thickness of the cobalt binder, and the size of the tungsten carbide grains. Research has shown that the ductile binder undergoes nearly all the plastic deformation during fracture, which provides the primary energy consuming process that enhances fracture resistance. Recent manufacturing developments have given rise to the production of a WC-6.7wt% Co cermet having an average WC grain size of 70 nm, with a corresponding binder mean thickness, h, of 9 nm calculated from d = h(1-Vf)/Vf where d = 70 nm and Vf = 0.114. This composite has shown a higher wear resistance than that of conventional cermets in proportion to their hardness. Such improvement has been attributed to the difficulty in forming dislocations in the very small grains. There are also indications that the Co binder in the nanoscale cermet contains higher contents of dissolved W and C than for conventional scale cermets. Because plastic deformation is initially confined to the binder phase, it was of interest to perform mode 1 and mixed mode toughness tests on the nanoscale cermet to determine whether flow localization influenced mixed mode toughness as in bulk materials. Two generations of this cermet were provided by Rogers Tool Works. The first generation, A, had lower binder contiguity, with occasional agglomerations of WC grains. The second generation, B, was cleaner, with the cobalt binder more uniformly separating the WC grains

  4. ADVANCED HYDROGEN TRANSPORT MEMBRANES FOR VISION 21 FOSSIL FUEL PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    Carl R. Evenson; Anthony F. Sammells; Richard Mackay; Scott R. Morrison; Sara L. Rolfe; Richard Blair; U. Balachandran; Richard N. Kleiner; James E. Stephan; Frank E. Anderson; Chandra Ratnasamy; Jon P. Wagner; Clive Brereton; Warren Wolfs

    2004-04-26

    During this quarter, work was focused on testing layered composite membranes under varying feed stream flow rates at high pressure. By optimizing conditions, H{sub 2} permeation rates in excess of 400 mL {center_dot} min{sup -1} {center_dot} cm{sup -2} at 440 C were measured. Membrane stability was characterized by repeated thermal and pressure cycling. The effect of cermet grain size on permeation was determined. Finally, progress is summarized on thin film cermet fabrication, catalyst development, and H{sub 2} separation unit scale up.

  5. ADVANCED HYDROGEN TRANSPORT MEMBRANES FOR VISION 21 FOSSIL FUEL PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    Carl R. Evenson; Anthony F. Sammells; Richard Mackay; Richard Treglio; Sara L. Rolfe; Richard Blair; U. Balachandran; Richard N. Kleiner; James E. Stephan; Frank E. Anderson; Chandra Ratnasamy; Jon P. Wagner; Clive Brereton; Warren Wolfs

    2004-07-26

    During this quarter, work was focused on testing layered composite membranes under varying feed stream flow rates at high pressure. By optimizing conditions, H{sub 2} permeation rates as high as 423 mL {center_dot} min{sup -1} {center_dot} cm{sup -2} at 440 C were measured. Membrane stability was investigated by comparison to composite alloy membranes. Permeation of alloyed membranes showed a strong dependence on the alloying element. Impedance analysis was used to investigate bulk and grain boundary conductivity in cermets. Thin film cermet deposition procedures were developed, hydrogen dissociation catalysts were evaluated, and hydrogen separation unit scale-up issues were addressed.

  6. Dimensional behavior of Ni-YSZ composites during redox cycling

    DEFF Research Database (Denmark)

    Pihlatie, Mikko; Kaiser, Andreas; Larsen, Peter Halvor;

    2009-01-01

    The dimensional behavior of Ni-yttria-stabilized zirconia (YSZ) cermets during redox cycling was tested in dilatometry within the temperature range 600-1000 degrees C. The effect Of humidity oil redox stability was investigated at intermediate and low temperatures. We show that both the sintering...

  7. Materials and Concepts for Full Ceramic SOFCs with Focus on Carbon Containing Fuels

    DEFF Research Database (Denmark)

    Holtappels, Peter; Sudireddy, Bhaskar Reddy; Veltzé, Sune;

    stimulated the development for full ceramic anodes based on strontium titanates. Furthermore, the Ni-cermet is primarily a hydrogen oxidation electrode and efficiency losses might occur when operating on carbon containing fuels. In a recent European project full ceramic cells comprising CGO/Ni infiltrated Nb...

  8. Biogas Upgrading Using SOEC with a Ni-ScYSZ Electrode

    DEFF Research Database (Denmark)

    Ebbesen, Sune Dalgaard; Bøgild Hansen, John; Mogensen, Mogens Bjerg

    2013-01-01

    Biogas consists mainly of CH4, CO2 and small amounts of H2S. The value of biogas will increase significantly if it is upgraded to pipeline quality by converting CO2 and H2O in the biogas to CO and H2 using a Solid Oxide Electrolysis Cell (SOEC) followed by methanation. The Ni-ScYSZ-cermet electrode...

  9. A Critical Review of Models of the H-2/H2O/Ni/SZ Electrode Kinetics

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Høgh, Jens Valdemar Thorvald; Hansen, Karin Vels;

    2007-01-01

    experimental findings that a useful model must be able to explain such as difference in sensitivity to poisoning by H2S due to differences in the detailed composition of the SZ and large change in apparent activation energy by change in cermet preparation. Finally, we will point out some elements, which seem...

  10. Electrical conductivity of Ni–YSZ composites: Variants and redox cycling

    DEFF Research Database (Denmark)

    Pihlatie, Mikko; Kaiser, Andreas; Mogensen, Mogens Bjerg

    2012-01-01

    Short-term changes in the electrical conductivity of different Ni–YSZ composites (cermets) were measured by an in-situ 4-point DC technique. The isothermal reduction was carried out in dry, humidified or wet hydrogen at temperatures from 600 to 850°C. The cermets reduced at 600°C showed a stable...... conductivity of about 1100S/cm, which increased to an enhanced ~2000S/cm upon re-oxidation and subsequent re-reduction cycling at the same temperature. At 850°C, a rapid initial conductivity loss was observed; upon re-reduction after the re-oxidation both the conductivity and its loss rate were largely...... the same as in the initial reduction. The presence of steam had an accelerating effect on the conductivity loss at 850°C. In addition to cermets with a typical microstructure, different modified microstructures and compositions were tested. In the modified cermets, Al, Mg, and Ce were used as Ni dopants...

  11. Reaction of uranium dioxide with copper-containing chloride melts

    International Nuclear Information System (INIS)

    Cermet composition materials consisting of metallic copper and uranium dioxide can be used for manufacturing fuel rods of nuclear power reactors. Reprocessing of such irradiated fuel of dispersive type can be done employing non-aqueous pyrochemical methods and developing such technology requires information on interaction of uranium dioxide with chloride melts containing copper ions

  12. Internal reforming development for solid oxide fuel cells

    Science.gov (United States)

    Lee, A. L.

    1987-02-01

    Internal reforming of natural gas within a solid oxide fuel cell (SOFC) should simplify the overall system design and make the SOFC an attractive means for producing electrical power. This program was undertaken to investigate the catalytic properties of nickel cermets, which are prime candidates for SOFC anodes. The initial task in this program was an extensive literature search for information on steam reforming of light hydrocarbons. The second task was to modify and calibrate the reactor systems that were used in the experimental kinetic studies. Two systems were used in this investigation; a continuously stirred tank reactor system (CSTR) and a plug flow reactor system (PFR). In the third task, 16 nickel-zirconia cermets were prepared using four procedures, tape casting, Westinghouse slurry, incorporation of performers, and granulation. The catalytic behavior of three cermets was determined in the fourth task. The reaction was first order with respect to methane and -1.25 for steam. Ethane and propane in the feed did not affect the methane conversion rate. The cermet has a higher initial tolerance for sulfur than standard nickel reforming catalysts. The final task was a mechanistic study of the steam reforming reaction on nickel and nickel-zirconia catalysts.

  13. Sintering behavior, microstructure and properties of TiC-FeCr hard alloy

    Institute of Scientific and Technical Information of China (English)

    Farid Akhtar; Shiju Guo; Jawid Askari; Jianjun Tian

    2007-01-01

    TiC based cermets were produced with FeCr,as a binder,by conventional P/M (powder metallurgy) to near >97% of the theoretical density.Sintering temperature significantly affects the mechanical properties of the composite.The sintering temperature of>1360 ℃ caused severe chemical reaction between TiC particles and the binder phase.In the TiC-FeCr cermets,the mechanical properties did not vary linearly with the carbide content.Optimum mechanical properties were found in the composite containing 57wt%TiC reinforcement,when sintered at 1360 ℃ for 1 h.Use of carbon as an additive enhanced the mechanical properties of the composites.Cermets containing carbon as an additive with 49wt% TiC exhibited attractive mechanical properties.The microstructure of the developed composite contained less or no debonding,representing good wettability of the binder with TiC particles.Homogeneous distribution of the TiC particles ensured the presence of isotropic mechanical properties and homogeneous distribution of stresses in the composite.Preliminary experiments for evaluation of the oxidation resistance of FeCr bonded TiC cermets indicate that they are more resistant than WC-Co hardmetals.

  14. Preparation and electrochemical characterisation of supporting SOFC–Ni–YZT anodes

    NARCIS (Netherlands)

    Holtappels, P.; Verbraeken, M.; Vogt, U.; Blank, D.H.A.; Boukamp, B.A.

    2006-01-01

    Symmetrical cells consisting of Ni–Y0.20Ti0.18Zr0.62O1.90 (Ni–YZT) cermet electrodes on a Ni–YSZ support have been investigated with respect to the hydrogen/water partial pressures. Impedance spectra at open circuit potential were obtained as function of temperature and analysed in terms of a fracta

  15. SOFC-anodes, proof for a finite-length type Gerischer impedance?

    NARCIS (Netherlands)

    Boukamp, B.A.; Verbraeken, M.; Blank, D.H.A.; Holtappels, P.

    2006-01-01

    The impedance of a symmetric cell with Ni/Ti-doped YSZ cermet anodes was measured as function of ambient (PH2, PH2O) and temperature. The impedances showed identical shapes with a minor dispersive contribution in the high frequency region and a dominating dispersion down to 0.01 Hz. The characterist

  16. Shock wave fabricated ceramic-metal nozzles

    NARCIS (Netherlands)

    Carton, E.P.; Stuivinga, M.E.C.; Keizers, H.L.J.; Verbeek, H.J.; Put, P.J. van der

    1999-01-01

    Shock compaction was used in the fabrication of high temperature ceramic-based materials. The materials' development was geared towards the fabrication of nozzles for rocket engines using solid propellants, for which the following metal-ceramic (cermet) materials were fabricated and tested: B4C-Ti (

  17. 切削温度

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Economical Cryogenic Machining,Effect of Si content and hardness on the machinability of hot working die steels, Measuring of temperature cutting by research heat physics ultra-high speed edge machining of metal,Mechanical and Physical Properties of Cermets Based on Titanium Carbide,On the cutting temperatures generated high speed hard machining.

  18. Proceedings of the twentieth DAE-BRNS symposium on thermal analysis: book of abstracts

    International Nuclear Information System (INIS)

    The topics covered in this symposium are: thermodynamics and phase diagram studies, thermochemical and thermophysical properties of materials, solid-state reactions and kinetics, thermal properties of ceramics and cermets, thermal behaviour of nanomaterials and coated particles and thermal analysis of materials. Papers relevant to INIS are indexed separately

  19. Pt–Al2O3 nanocoatings for high temperature concentrated solar thermal power applications

    International Nuclear Information System (INIS)

    Nano-phased structures based on metal–dielectric composites, also called cermets (ceramic–metal), are considered among the most effective spectral selective solar absorbers. For high temperature applications (stable up to 650 °C) noble metal nanoparticles and refractory oxide host matrices are ideal as per their high temperature chemical inertness and stability: Pt/Al2O3 cermet nano-composites are a representative family. This contribution reports on the optical properties of Pt/Al2O3 cermet nano-composites deposited in a multilayered tandem structure. The radio-frequency sputtering optimized Pt/Al2O3 solar absorbers consist of stainless steel substrate/ Mo coating layer/ Pt–Al2O3/ protective Al2O3 layer and stainless steel substrate/ Mo coating layer /Pt–Al2O3 for different composition and thickness of the Pt–Al2O3 cermet coatings. The microstructure, morphology, theoretical modeling and optical properties of the coatings were analyzed by the x-ray diffraction, atomic force, microscopy, effective medium approximation and UV–vis specular and diffuse reflectance.

  20. 挤压模

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A survey of manifold designs for flat die extrusion;Cermet Dies for Hot Extrusion of Hard Aluminium;Cluster computing in numerical simulation of extrusion flow;Computer aided design and manufacture of streamlined extrusion dies;Deposition of hard films on hot-working steel dies for aluminium;Development of a remote quick CAE system on sculptured metal extrusion die surface;

  1. Manufacturing and characterization of metal-supported solid oxide fuel cells

    DEFF Research Database (Denmark)

    Blennow Tullmar, Peter; Hjelm, Johan; Klemensø, Trine;

    2011-01-01

    A metal-supported solid oxide fuel cell design offers competitive advantages, for example reduced material costs and improved robustness. This paper reports the performance and stability of a recently developed metal-supported cell design, based on a novel cermet anode, on a 25cm2 (1cm2/16cm2...

  2. FeAl-TiC and FeAl-WC composites - melt infiltration processing, microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, R.; Schneibel, J.H.

    1997-04-01

    TiC-based and WC-based cermets were processed with iron aluminide, an intermetallic, as a binder by pressureless melt infiltration to near full density (> 97 % theoretical density). Phase equilibria calculations in the quaternary Fe-Al-Ti-C and Fe-Al-W-C systems at 145{degrees}C were performed to determine the solubility of the carbide phases in liquid iron aluminide. This was done by using Thermocalc{trademark} and the results show that molten Fe-40 at.% Al in equilibrium with Ti{sub 0.512}C{sub 0.488} and graphite, dissolves 4.9 at% carbon and 64 atomic ppm titanium. In the Fe-Al-W-C system, liquid Fe-40 at.% Al in equilibrium with graphite dissolves about 5 at.% carbon and 1 at.% tungsten. Due to the low values for the solubility of the carbide phases in liquid iron aluminide, liquid phase sintering of mixed powders does not yield a dense, homogeneous microstructure for carbide volume fractions greater than 0.70. Melt infiltration of molten FeAl into TiC and WC preforms serves as a successful approach to process cermets with carbide contents ranging from 70 to 90 vol. %, to greater than 97% of theoretical density. Also, the microstructures of cermets prepared by melt infiltration were very homogeneous. Typical properties such as hardness, bend strength and fracture toughness are reported. SEM observations of fracture surfaces suggest the improved fracture toughness to result from the ductility of the intermetallic phase. Preliminary experiments for the evaluation of the oxidation resistance of iron aluminide bonded cermets indicate that they are more resistant than WC-Co cermets.

  3. Mars Mission Analysis Trades Based on Legacy and Future Nuclear Propulsion Options

    Science.gov (United States)

    Joyner, Russell; Lentati, Andrea; Cichon, Jaclyn

    2007-01-01

    The purpose of this paper is to discuss the results of mission-based system trades when using a nuclear thermal propulsion (NTP) system for Solar System exploration. The results are based on comparing reactor designs that use a ceramic-metallic (CERMET), graphite matrix, graphite composite matrix, or carbide matrix fuel element designs. The composite graphite matrix and CERMET designs have been examined for providing power as well as propulsion. Approaches to the design of the NTP to be discussed will include an examination of graphite, composite, carbide, and CERMET core designs and the attributes of each in regards to performance and power generation capability. The focus is on NTP approaches based on tested fuel materials within a prismatic fuel form per the Argonne National Laboratory testing and the ROVER/NERVA program. NTP concepts have been examined for several years at Pratt & Whitney Rocketdyne for use as the primary propulsion for human missions beyond earth. Recently, an approach was taken to examine the design trades between specific NTP concepts; NERVA-based (UC)C-Graphite, (UC,ZrC)C-Composite, (U,Zr)C-Solid Carbide and UO2-W CERMET. Using Pratt & Whitney Rocketdyne's multidisciplinary design analysis capability, a detailed mission and vehicle model has been used to examine how several of these NTP designs impact a human Mars mission. Trends for the propulsion system mass as a function of power level (i.e. thrust size) for the graphite-carbide and CERMET designs were established and correlated against data created over the past forty years. These were used for the mission trade study. The resulting mission trades presented in this paper used a comprehensive modeling approach that captures the mission, vehicle subsystems, and NTP sizing.

  4. Novel dense membrane for hydrogen separation for energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Bandopadhyay, Sukumar [Univ. of Alaska, Fairbanks, AL (United States); Balachandran, Uthamalingam [Argonne National Lab. (ANL), Argonne, IL (United States); Nag, Nagendra [Surmet Corp., Burlington, MA (United States)

    2013-10-24

    The main objectives of this project are: (1) Characterization of the thermo mechanical properties of the novel dense HTM bulk sample; (2) Development of a correlation among the intrinsic factors (such as grain size and phase distribution), and the extrinsic factors (such as temperature and atmosphere) and the thermo-mechanical properties (such as strengths and stress) to predict the performance of a HTM system (HTM membrane and porous substrate) ; and (3) Evaluation of the stability of the novel HTM membrane and its property correlations after thermal cycling. Based on all results and analysis of the thermo mechanical properties for the HTM cermet bulk samples, several important conclusions were made. The mean σfs at room temperature is approximately 356 MPa for the HTM cermet. The mean σfs value decreases to 284 MPa as the temperature increases to 850?C. The Difference difference in atmosphere, such as air or N2, had an insignificant effect on the flexural strength values at 850?C for the HTM cermet. The HTM cermet samples at room temperature and at 500?C fractured without any significant plastic deformation. Whereas, at 850?C, the HTM cermet samples fractured, preceded by an extensive plastic deformation. It seems that the HTM cermet behaves more like an elastic material such as a nonmetal ceramic at the room temperature, and more like a ductile material at increased temperature (850?C). The exothermic peak during the TG/DTA tests centered at 600?C is most likely associated with both the enthalpy change of transformation from the amorphous phase into crystalline zirconia and the oxidation of Pd phase in HTM cermet in air. The endothermic peak centered at 800?C is associated with the dissociation of PdO to Pd for the HTM cermet sample in both inert N2 environment and air. There is a corresponding weight gain as oxidation occurs for palladium (Pd) phase to form palladium oxide (PdO) and there is a weight loss as the unstable PdO is dissociated back to Pd and

  5. A Stability Study of Ni/Yttria-Stabilized Zirconia Anode for Direct Ammonia Solid Oxide Fuel Cells.

    Science.gov (United States)

    Yang, Jun; Molouk, Ahmed Fathi Salem; Okanishi, Takeou; Muroyama, Hiroki; Matsui, Toshiaki; Eguchi, Koichi

    2015-12-30

    In recent years, solid oxide fuel cells fueled with ammonia have been attracting intensive attention. In this work, ammonia fuel was supplied to the Ni/yttria-stabilized zirconia (YSZ) cermet anode at 600 and 700 °C, and the change of electrochemical performance and microstructure under the open-circuit state was studied in detail. The influence of ammonia exposure on the microstructure of Ni was also investigated by using Ni/YSZ powder and Ni film deposited on a YSZ disk. The obtained results demonstrated that Ni in the cermet anode was partially nitrided under an ammonia atmosphere, which considerably roughened the Ni surface. Moreover, the destruction of the anode support layer was confirmed for the anode-supported cell upon the temperature cycling test between 600 and 700 °C because of the nitriding phenomenon of Ni, resulting in severe performance degradation.

  6. Intermetallic bonded ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Plucknett, K.P.; Tiegs, T.N.; Alexander, K.B.; Becher, P.F.; Schneibel, J.H.; Waters, S.B.; Menchhofer, P.A. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1995-07-01

    A range of carbide and oxide-based cermets have been developed utilizing ductile nickel aluminide (Ni{sub 3}Al) alloy binder phases. Some of these, notably materials based upon tungsten and titanium carbides (WC and TiC respectively), offer potential as alternatives to the cermets which use cobalt binders (i.e. WC/Co). Samples have been prepared by blending commercially available Ni{sub 3}Al alloy powders with the desired ceramic phases, followed by hot-pressing. Alumina (Al{sub 2}O{sub 3}) matrix materials have also been prepared by pressurized molten alloy infiltration. The microstructure, flexure strength and fracture toughness of selected materials are discussed.

  7. Ni-Based Solid Oxide Cell Electrodes

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Holtappels, Peter

    2013-01-01

    . The main emphasis will be on the following subjects: (a) electronic conductivity of cermets, (b) dimensional and thermodynamic stability including redox cycling, © thermal expansion coefficient matching, (d) chemical compatibility with stack components and gaseous reactants and (e) electrode reaction......This paper is a critical review of the literature on nickel-based electrodes for application in solid oxide cells at temperature from 500 to 1000 _C. The applications may be fuel cells or electrolyser cells. The reviewed literature is that of experimental results on both model electrodes...... and practical composite cermet electrodes. A substantially longer three-phase boundary (TPB) can be obtained per unit area of cell in such a composite of nickel and electrolyte material, provided that two interwoven solid networks of the two solid and one gaseous phases are obtained to provide a three...

  8. Development of high-activity 252Cf sources for neutron brachytherapy

    International Nuclear Information System (INIS)

    The Gershenson Radiation Oncology Center of Wayne State University (WSU), Detroit, Michigan, is using 252Cf medical sources for neutron brachytherapy. These sources are based on a 20-year-old design containing ≤ 30 microg 252Cf in the form of a cermet wire of Cf2O3 in a palladium matrix. The Radiochemical Engineering Development Center (REDC) of Oak Ridge National Laboratory has been asked to develop tiny high-activity 252Cf neutron sources for use with remote afterloading equipment to reduce treatment times and dose to clinical personnel and to expedite treatment of brain and other tumors. To date, the REDC has demonstrated that 252Cf loadings can be greatly increased in cermet wires much smaller than before. Equipment designed for hot cell fabrication of these wires is being tested. A parallel program is under way to relicense the existing source design for fabrication at the REDC

  9. In-situ Raman spectroscopy analysis of the interfaces between Ni-based SOFC anodes and stabilized zirconia electrolyte

    CERN Document Server

    Agarkov, D A; Tsybrov, F M; Tartakovskii, I I; Kharton, V V; Bredikhin, S I

    2016-01-01

    A new experimental approach for in-situ Raman spectroscopy of the electrode | solid electrolyte interfaces in controlled atmospheres, based on the use of optically transparent single-crystal membranes of stabilized cubic zirconia, has been proposed and validated. This technique makes it possible to directly access the electrochemical reaction zone in SOFCs by passing the laser beam through single-crystal electrolyte onto the interface, in combination with simultaneous electrochemical measurements. The case study centered on the analysis of NiO reduction in standard cermet anodes under open-circuit conditions, demonstrated an excellent agreement between the observed kinetic parameters and literature data on nickel oxide. The porous cermet reduction kinetics at 400-600C in flowing H2-N2 gas mixture can be described by the classical Avrami model, suggesting that the reaction rate is determined by the metal nuclei growth limited by Ni diffusion. The advantages and limitations of the new experimental approach were...

  10. サーメット系溶射皮膜のスラリー摩耗深さ予測

    OpenAIRE

    杉山, 憲一; 服部, 修次; Sugiyama, Kenichi; HATTORI, Shuji

    2007-01-01

    Slurry erosion with sand particles is a serious problem for pumps operating at the Yellow River pumping station. Therefore, a technique to predict erosion volume loss is required for selecting erosion resistant material and determining specification of the maintenance period. This paper reports a method to predict the volume loss of thermal sprayed cermet layers using slurry jet apparatus. An equation for prediction is derived from combining an analysis of sand particle behavior in the slurry...

  11. Plutonium-238 processing at Savannah River Plant

    Energy Technology Data Exchange (ETDEWEB)

    Burney, G.A.

    1983-01-01

    Plutonium-238 is produced by irradiating NpO/sub 2/-Al cermet slugs or tubes with neutrons. The neptunium-237 is produced as a by-product when natural or enriched uranium is irradiated with neutrons. The neptunium is separated by solvent extraction and ion exchange and precipitated as neptunium oxalate. Neptunium oxalate is calcined to neptunium oxide and fabricated into targets for irradiation. The irradiation conditions are controlled to produce plutonium with 80 to 90 wt % /sup 238/Pu.

  12. Cutting-tool recycling process with the zinc-melt method for obtaining thermal-spray feedstock powder (WC-Co): Postopek recikliranja orodij za rezanje z metodo taljenja v Zn za pridobivanje prahu WC-Co za termično nabrizgavanje:

    OpenAIRE

    Altuncu, Ekrem; Erdogan, Garip; Ozturk, Savas; Turk, Ahmet; Ustel, Fatih

    2013-01-01

    Various recycling processes for WC-Co cermets from cutting tools, such as chemical modification, thermal modification, the cold-stream method and the electrochemical method have been investigated and some of them are actually employed in industry. However, these conventional methods have many problems to be solved and they are not always established technologies. Therefore, a more economical and high-efficiency recycling procedure needs to be developed. In this study we investigated the appli...

  13. Estudio por emisión acústica del comportamiento a flexión de recubrimientos WC-Co obtenidos por plasma atmosférico

    OpenAIRE

    Segovia, F.; Klyatskina, E.; Bonache, V.; Salvador, M. D.; Sanchez, E.; Cantavella, V.; Bloem, C.

    2007-01-01

    Plasma sprayed cermet coatings WC-Co are used in a wide range of industrial applications, mainly due to their wear resistance even in corrosive environments. The objective of this work is to analyze mechanical response of hard metal coatings by means of three- and four-points bend tests applying acoustic emission technique to determine failure critical strength. It has been observed the effect of supported charge level in structural damage by means of optical microscopy and scanning electron ...

  14. Effect of oxygen/fuel ratio on the in-flight particle parameters and properties of HVOF WC–CoCr coatings

    OpenAIRE

    Picas Barrachina, Josep Anton; Punset Fusté, Miquel; Baile Puig, Maria Teresa; Martín Fuentes, Enrique; Forn Alonso, Antonio

    2010-01-01

    High Velocity Oxy-Fuel (HVOF) spray techniques can produce high performance alloy and cermet coatings for applications that require wear resistant surfaces. In HVOF spraying heat is produced by burning mixtures of oxygen and fuel, mainly hydrogen, kerosene, propane, propylene, natural gas or acetylene. In these processes, the particle velocity and temperature determine the resultant coating properties and in many cases enables a better understanding of the process. The aim o...

  15. Modified strontium titanates: From defect chemistry to SOFC anodes

    DEFF Research Database (Denmark)

    Verbraeken, M.C.; Ramos, Tania; Agersted, Karsten;

    2015-01-01

    Modified strontium titanates have received much attention recently for their potential as anode material in solid oxide fuel cells (SOFC). Their inherent redox stability and superior tolerance to sulphur poisoning and coking as compared to Ni based cermet anodes could improve durability of SOFC...... systems dramatically. Various substitution strategies can be deployed to optimise materials properties in these strontium titanates, such as electronic conductivity, electrocatalytic activity, chemical stability and sinterability, and thus mechanical strength. Substitution strategies not only cover choice...

  16. 热喷涂

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A proposal for methods for decreasing thermal spraying noise acoustic characteristic of various materials;A stochastic model to simulate the formation of a thermal spray coating;Abrasive wear behavior of Ni(Cr)-TiB { sub } 2 co atings deposited by HVOF spraying of SHS-derived cermet powders;Adhesion of sealers on thermal spray coatings;An experimental study of the wear performance of NiCrBSi thermal spray coatings

  17. Gradient tool WC/HS6-5-2 materials produced using the powder metallurgy method

    OpenAIRE

    L.A. Dobrzański; A. Kloc-Ptaszna; G. Matula

    2008-01-01

    Purpose: The goal of this work is development of the new group of the gradient cermets with the high-speed steelmatrix, reinforced with the hard carbides phases of the WC types.Design/methodology/approach: The materials were fabricated using the conventional powder metallurgymethod, consisting in compacting the powder in a closed die, and subsequent sintering. All the sintered test pieces weresubjected to examination of density and hardness; observations were also made using the scanning elec...

  18. Properties of the multicomponent and gradient PVD coatings

    OpenAIRE

    L.W. Żukowska; L.A. Dobrzański

    2007-01-01

    Purpose: This paper presents investigation results of the properties of the multicomponent (Ti,Al)N and gradient Ti(C,N) wear resistant coatings, deposited with the PVD process onto the substrate from the cemented carbides, cermets and Al2O3+TiC type oxide tool ceramics.Design/methodology/approach: The methodology includes analysis of the mechanical and functional properties. The Ra parameter was assumed to be the value describing surface roughness. The microhardness tests using the Vickers m...

  19. Electrochemical Characterization of Ni/(Sc)YSZ Electrodes

    DEFF Research Database (Denmark)

    Ramos, Tania; Thydén, Karl Tor Sune; Mogensen, Mogens Bjerg

    2010-01-01

    Investigations of Ni/(Sc)YSZ cermets for solid oxide cells (SOCs) were performed by electrochemical impedance spectroscopy (EIS), under varying experimental conditions and upon redox cycling, using three different designs of symmetric cells. The deconvolution and fitting of the obtained impedance...... parameters. Initial degradation results for both Ni/ScYSZ and Ni/YSZ based anodes under very high steam content are also reported. ©2010 COPYRIGHT ECS - The Electrochemical Society...

  20. Numerical evaluation of oxide growth in metallic support microstructures of Solid Oxide Fuel Cells and its influence on mass transport

    DEFF Research Database (Denmark)

    Reiss, Georg; Frandsen, Henrik Lund; Persson, Åsa Helen;

    2015-01-01

    Metal-supported Solid Oxide Fuel Cells (SOFCs) are developed as a durable and cost-effective alternative to the state-of-the-art cermet SOFCs. This novel technology offers new opportunities but also new challenges. One of them is corrosion of the metallic support, which will decrease the long....... In addition to that an analytical frame-work is proposed, which is capable of estimating the porosity, tortuosity and the corresponding ASR based on weight gain measurements....

  1. Ti(C,N) and (Ti,Al)N hard wear resistant coatings

    OpenAIRE

    K. Gołombek; J. Mikuła; W. Kwaśny; L.W. Żukowska; L.A. Dobrzański

    2010-01-01

    Purpose: Investigation the influence of kind of PVD coatings structure (homogenous or gradient) on properties of deposited tool materials: cemented carbides and cermets.Design/methodology/approach: Analysis of the structure, analysis of the mechanical and functional properties: surface roughness, microhardness tests, scratch tests, cutting tests. The Ti(C,N) gradient coating was investigated by XPS method with multifunctional PHI 5700/660 spectrometer. The characteristic of surface region coa...

  2. CALPHAD study of cubic carbide systems with Cr

    OpenAIRE

    He, Zhangting

    2015-01-01

    Cubic carbides (titanium, tantalum, niobium, and zirconium carbides) can constitute a significant proportion of so-called cubic and cermet grades, where it is added to substitute a portion of tungsten carbide. It is thus critical to understand and be able to thermodynamically model the cubic carbide systems. In order to do this, the thermodynamic descriptions of lower order systems, such as the Ti-Cr-C system, need to be well studied. To approach this goal, an extensive literature survey of t...

  3. Solar Selective Coatings Developed for Space Power Applications

    Science.gov (United States)

    Jaworske, Donald A.

    2002-01-01

    A solar collector having the combined properties of high solar absorptance, low infrared emittance, and high thermal conductivity is envisioned for space power applications on minisatellites. A high solar absorptance is needed to collect as much of the incident solar radiation as possible and a low infrared emittance is needed to minimize radiant energy losses. A lightweight material having a high thermal conductivity is needed to transport the absorbed energy to where it is needed. Such a solar collector may be used with a low temperature-differential heat engine to provide electric power to the minisatellite components or as a source of thermal energy for a thermal bus that would heat remote regions of the spacecraft. The key to such a collector is the use of cermet coatings. Cermet coatings are composed of molecular islands of metal embedded in a three-dimensional matrix of dielectric. Recent research on molecular mixtures of aluminum and aluminum oxide at the NASA Glenn Research Center has yielded cermet coatings with a solar absorptance a of 0.797 and an infrared emittance epsilon of 0.131, yielding an alpha/epsilon ratio of 6. Although additional work is needed to further increase the alpha/epsilon ratio, these coatings are attractive owing to their potential durability in the space environment. The aluminum oxide surface should provide substantial protection from the atomic oxygen found in low Earth orbit. To help minimize emittance, these coatings are deposited on a smooth surface. The selected surface is aluminum that has been diamond turned to a mirror finish. Cermet coatings are manufactured by sputter deposition. To achieve the desired variable composition, Glenn's researchers implemented a novel approach using a cylindrical target composed of aluminum and aluminum oxide. Rotating the cylinder during the deposition process yields a coating of variable composition. A photograph of the custom-made aluminum and aluminum oxide cylindrical target installed

  4. Qualification under irradiation of the U3 O8-Al MTR fuels fabricated at IPEN-CNEN/SP

    International Nuclear Information System (INIS)

    The specifications of U3 O8 cermet fuel, utilized in the Research Reactor IEA-R1, and fabricated by IPEN/CNEN-SP, are presented. The history of the specification development is followed through descriptions of the world experience in research and material test reactor fuel utilization and post-irradiation examination in hot cells. An inspection program has been carried out for fuel qualification. (author)

  5. Aluminum oxide as a dual-functional modifier of Ni-based anodes of solid oxide fuel cells for operation on simulated biogas

    Science.gov (United States)

    Wang, Feng; Wang, Wei; Ran, Ran; Tade, Moses O.; Shao, Zongping

    2014-12-01

    Al2O3 and SnO2 additives are introduced into the Ni-YSZ cermet anode of solid oxide fuel cells (SOFCs) for operation on simulated biogas. The effects of incorporating Al2O3/SnO2 on the electrical conductivity, morphology, coking resistance and catalytic activity for biogas reforming of the cermet anode are systematically studied. The electrochemical performance of the internal reforming SOFC is enhanced by introducing an appropriate amount of Al2O3 into the anode, but it becomes worse with excess alumina addition. For SnO2, a negative effect on the electrochemical performance is demonstrated, although the coking resistance of the anode is improved. For fuel cells operating on biogas, stable operation under a polarization current for 130 h at 750 °C is achieved for a cell with an Al2O3-modified anode, while cells with unmodified or SnO2-modified Ni-YSZ anodes show much poorer stability under the same conditions. The improved performance of the cell with the Al2O3-modified anode mainly results from the suppressed coking and sintering of the anode and from the formation of NiAl2O4 in the unreduced anode. In sum, modifying the anode with Al2O3 may be a useful and facile way to improve the coking resistance and electrochemical performance of the nickel-based cermet anodes for SOFCs.

  6. Development of an Engineered Producet Storage Concept for the UREX+1 Combined Transuraqnic?Lanthanide Product Streams

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sean M. McDeavitt; Thomas J. Downar; Dr. Temitope A. Taiwo; Dr. Mark A. Williamson

    2009-03-01

    The U.S. Department of Energy is developing next generation processing methods to recycle uranium and transuranic (TRU) isotopes from spent nuclear fuel. The objective of the 3-year project described in this report was to develop near-term options for storing TRU oxides isolated through the uranium extraction (UREX+) process. More specifically, a Zircaloy matrix cermet was developed as a storage form for transuranics with the understanding that the cermet also has the ability to serve as a inert matrix fuel form for TRU burning after intermediate storage. The goals of this research projects were: 1) to develop the processing steps required to transform the effluent TRU nitrate solutions and the spent Xircaloy cladding into a zireonium matrix cermet sotrage form; and 2) to evaluate the impact of phenomena that govern durability of the storage form, material processing, and TRU utiliztion in fast reactor fuel. This report represents a compilation of the results generated under this program. The information is presented as a brief technical narrative in the following sections with appended papers, presentations and academic theses to provide a detailed review of the project's accomplishments.

  7. ADVANCED HYDROGEN TRANSPORT MEMBRANES FOR VISION 21 FOSSIL FUELS PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    Shane E. Roark; Anthony F. Sammells; Richard Mackay; Stewart Schesnack; Scott Morrison; Thomas A. Zirbel; Thomas F. Barton; Sara L. Rolfe; U. Balachandran; Richard N. Kleiner; James E. Stephan; Frank E. Anderson; Aaron L. Wagner; Jon P. Wagner

    2003-07-31

    Eltron Research Inc. and team members CoorsTek, Sued Chemie, and Argonne National Laboratory are developing an environmentally benign, inexpensive, and efficient method for separating hydrogen from gas mixtures produced during industrial processes, such as coal gasification. This project was motivated by the National Energy Technology Laboratory (NETL) Vision 21 initiative, which seeks to economically eliminate environmental concerns associated with the use of fossil fuels. Currently, this project is focusing on four basic categories of dense membranes: (1) mixed conducting ceramic/ceramic composites, (2) mixed conducting ceramic/metal (cermet) composites, (3) cermets with hydrogen permeable metals, and (4) layered composites containing hydrogen permeable alloys. Ultimately, these materials must enable hydrogen separation at practical rates under ambient and high-pressure conditions, without deactivation in the presence of feedstream components such as carbon dioxide, water, and sulfur. This report presents hydrogen permeation data during long term tests and tests at high pressure in addition to progress with cermet, ceramic/ceramic, and thin film membranes.

  8. Microstructure, mechanical properties and wear resistance of WC/Co nanocomposites

    International Nuclear Information System (INIS)

    The microstructure, mechanical properties, abrasion and wear resistance of WC-Co nanocomposites synthesized by the spray conversion technique by McCaundlish, Kear and Kim have been investigated. The binder phase of WC-Co nanocomposites is enriched in W and C, compared to conventional cermets. Small amorphous regions exist in the binder despite the slow cooling after liquid phase sintering. Few dislocations are found in the WC grains. The increased WC content and the amorphous regions modify (i.e. strengthen) the binder phase of the composites. Vickers indentation measurements show a hardness of the nanocomposites reaching 2,310 kg/mm2. While the toughness of conventional cermets decreases with increasing hardness, the toughness does not decrease further as the WC grain size decreases from 0.7 to 0.07 microm but remains constant at 8 MPam1/2. Scratches caused by a diamond indenter are small, commensurate with their hardness. These scratches are ductile, devoid of the grain fracture that is observed with conventional materials. The abrasions resistance of nanocomposites is about double that of conventional materials, although their hardness is larger by 23% only. This is due to the lack of WC grain fragmentation and removal which takes place in conventional cermets. Sliding wear resistance of WC/Co is proportional to their hardness; no additional benefit of nanostructure is obtained. This results from the very small size of adhesive wear events in even large WC grains

  9. Fabrication and Properties of Cylindrical and Tubular UO2-Stainless Steel Fuel Elements

    International Nuclear Information System (INIS)

    The fabrication by extrusion sintering of canned tubes and rods containing a dispersed fuel nucleus of UO2-stainless steel was investigated. The fuel elements may be up to 2 m long; the diameter of the rods is less than 30 mm; the total thickness of the tubes may be as low as 0.8 mm. The fuel cermet contains 20 to 60% UO2 by weight in the form of spherical particles having a diameter greater than 50 μm. The grade of steel for the cermet can be chosen relative to the conditions in which it is to be used. The fuel elements are checked by gammagraphy, macrography and micrography. The thermal conductivity and mechanical tensile properties of the cermets were investigated with respect to UO2 content and particle granulometry. Thermal shock tests and lengthy annealing of the tubular elements caused no cracking or lessening of the can. By this method of extrusion sintering canned fuel elements can be obtained directly; handling of the UO2 powder is reduced to a minimum, so that the losses of enriched uranium in the industrial fabrication of the fuel elements can also be reduced.

  10. Development of an Engineered Product Storage Concept for the UREX+1 Combined Transuranic/Lanthanide Product Streams

    International Nuclear Information System (INIS)

    The U.S. Department of Energy is developing next generation processing methods to recycle uranium and transuranic (TRU) isotopes from spent nuclear fuel. The objective of the 3-year project described in this report was to develop near-term options for storing TRU oxides isolated through the uranium extraction (UREX+) process. More specifically, a Zircaloy matrix cermet was developed as a storage form for transuranics with the understanding that the cermet also has the ability to serve as a inert matrix fuel form for TRU burning after intermediate storage. The goals of this research projects were: (1) to develop the processing steps required to transform the effluent TRU nitrate solutions and the spent Xircaloy cladding into a zireonium matrix cermet storage form; and (2) to evaluate the impact of phenomena that govern durability of the storage form, material processing, and TRU utilization in fast reactor fuel. This report represents a compilation of the results generated under this program. The information is presented as a brief technical narrative in the following sections with appended papers, presentations and academic theses to provide a detailed review of the project's accomplishments

  11. Initial evaluation of dry storage issues for spent nuclear fuels in wet storage at the Idaho Chemical Processing Plant

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, R J; Johnson, Jr, A B; Lund, A L; Gilbert, E R [and others

    1996-07-01

    The Pacific Northwest Laboratory has evaluated the basis for moving selected spent nuclear fuels in the CPP-603 and CPP-666 storage pools at the Idaho Chemical Processing Plant from wet to dry interim storage. This work is being conducted for the Lockheed Idaho Technologies Company as part of the effort to determine appropriate conditioning and dry storage requirements for these fuels. These spent fuels are from 22 test reactors and include elements clad with aluminum or stainless steel and a wide variety of fuel materials: UAl{sub x}, UAl{sub x}-Al and U{sub 3}O{sub 8}-Al cermets, U-5% fissium, UMo, UZrH{sub x}, UErZrH, UO{sub 2}-stainless steel cermet, and U{sub 3}O{sub 8}-stainless steel cermet. The study also included declad uranium-zirconium hydride spent fuel stored in the CPP-603 storage pools. The current condition and potential failure mechanisms for these spent fuels were evaluated to determine the impact on conditioning and dry storage requirements. Initial recommendations for conditioning and dry storage requirements are made based on the potential degradation mechanisms and their impacts on moving the spent fuel from wet to dry storage. Areas needing further evaluation are identified.

  12. Advanced Hydrogen Transport Membranes for Vision 21 Fossil Fuel Plants

    Energy Technology Data Exchange (ETDEWEB)

    Carl R. Evenson; Shane E. Roark

    2006-03-31

    The objective of this project was to develop an environmentally benign, inexpensive, and efficient method for separating hydrogen from gas mixtures produced during industrial processes, such as coal gasification. A family of hydrogen separation membranes was developed including single phase mixed conducting ceramics, ceramic/ceramic composites, cermet membranes, cermet membranes containing a hydrogen permeable metal, and intermediate temperature composite layered membranes. Each membrane type had different operating parameters, advantages, and disadvantages that were documented over the course of the project. Research on these membranes progressed from ceramics to cermets to intermediate temperature composite layered membranes. During this progression performance was increased from 0.01 mL x min{sup -1} x cm{sup -2} up to 423 mL x min{sup -1} x cm{sup -2}. Eltron and team membranes not only developed each membrane type, but also membrane surface catalysis and impurity tolerance, creation of thin film membranes, alternative applications such as membrane promoted alkane dehydrogenation, demonstration of scale-up testing, and complete engineering documentation including process and mechanical considerations necessary for inclusion of Eltron membranes in a full scale integrated gasification combined cycle power plant. The results of this project directly led to a new $15 million program funded by the Department of Energy. This new project will focus exclusively on scale-up of this technology as part of the FutureGen initiative.

  13. Initial evaluation of dry storage issues for spent nuclear fuels in wet storage at the Idaho Chemical Processing Plant

    International Nuclear Information System (INIS)

    The Pacific Northwest Laboratory has evaluated the basis for moving selected spent nuclear fuels in the CPP-603 and CPP-666 storage pools at the Idaho Chemical Processing Plant from wet to dry interim storage. This work is being conducted for the Lockheed Idaho Technologies Company as part of the effort to determine appropriate conditioning and dry storage requirements for these fuels. These spent fuels are from 22 test reactors and include elements clad with aluminum or stainless steel and a wide variety of fuel materials: UAlx, UAlx-Al and U3O8-Al cermets, U-5% fissium, UMo, UZrHx, UErZrH, UO2-stainless steel cermet, and U3O8-stainless steel cermet. The study also included declad uranium-zirconium hydride spent fuel stored in the CPP-603 storage pools. The current condition and potential failure mechanisms for these spent fuels were evaluated to determine the impact on conditioning and dry storage requirements. Initial recommendations for conditioning and dry storage requirements are made based on the potential degradation mechanisms and their impacts on moving the spent fuel from wet to dry storage. Areas needing further evaluation are identified

  14. Electrical conductivity of Ni–YSZ composites: Degradation due to Ni particle growth

    DEFF Research Database (Denmark)

    Pihlatie, Mikko; Kaiser, Andreas; Mogensen, Mogens Bjerg;

    2011-01-01

    The short-term changes in the electrical conductivity of Ni–YSZ composites (cermets) suitable for use in Solid Oxide Fuel Cells (SOFC) were measured by an in-situ 4-point DC technique. The isothermal reduction was carried out in dry, humidified or wet hydrogen at temperatures from 600 to 1000°C....... While the cermets reduced at 600°C showed a stable conductivity of 1000–1200S/cm, rapid initial conductivity loss was observed at elevated temperatures. At 1000°C the conductivity degraded nearly instantaneously to about 800S/cm, and continued to decline fast to about 400S/cm. At 850°C, the presence...... of steam did have an accelerating effect on the conductivity loss. Scanning Electron Microscopy of cermets reduced in different conditions showed increasing particle size and loss of metal-to-metal percolation in the samples reduced at higher temperatures. The short-term changes in conductivity were...

  15. Study of the U3O8-Al thermite reaction and strength of reactor fuel tubes

    International Nuclear Information System (INIS)

    Research and test reactors are presently operated with aluminum-clad fuel elements containing highly enriched uranium-aluminum alloy cores. To lower the enrichment and still maintain reactivity, the uranium content of the fuel element will need to be higher than currently achievable with alloy fuels. This will necessitate conversion to other forms such as U3O8-aluminum cermets. Above the aluminum melting point, U3O8 and aluminum undergo an exothermic thermite reaction and cermet fuel cores tend to keep their original shape. Both factors could affect the course and consequences of a reactor accident, and prompted an investigation of the behavior of cermet fuels at elevated temperatures. Tests were carried out using pellets and extruded tube-sections with 53 wt % U3O8 in aluminum. This content corresponds to a theoretical uranium density of 1.9 g/cc. Results indicate that the thermite reaction occurs at about 9000C in air without a violent effect. The heat of reaction was approximately 123 cal/g of U3O8-aluminum fuel. Tensile and compressive strength of the fuel tube section is low above 6600C. In tension, sections failed at about the aluminum melting point. In compression with 2-psi average axial stress, failure occurred at 9170C, while 7 psi average axial stress produced failure at 6690C

  16. Study of the U/sub 3/O/sub 8/-Al thermite reaction and strength of reactor fuel tubes

    Energy Technology Data Exchange (ETDEWEB)

    Peacock, H B

    1983-01-01

    Research and test reactors are presently operated with aluminum-clad fuel elements containing highly enriched uranium-aluminum alloy cores. To lower the enrichment and still maintain reactivity, the uranium content of the fuel element will need to be higher than currently achievable with alloy fuels. This will necessitate conversion to other forms such as U/sub 3/O/sub 8/-aluminum cermets. Above the aluminum melting point, U/sub 3/O/sub 8/ and aluminum undergo an exothermic thermite reaction and cermet fuel cores tend to keep their original shape. Both factors could affect the course and consequences of a reactor accident, and prompted an investigation of the behavior of cermet fuels at elevated temperatures. Tests were carried out using pellets and extruded tube-sections with 53 wt % U/sub 3/O/sub 8/ in aluminum. This content corresponds to a theoretical uranium density of 1.9 g/cc. Results indicate that the thermite reaction occurs at about 900/sup 0/C in air without a violent effect. The heat of reaction was approximately 123 cal/g of U/sub 3/O/sub 8/-aluminum fuel. Tensile and compressive strength of the fuel tube section is low above 660/sup 0/C. In tension, sections failed at about the aluminum melting point. In compression with 2-psi average axial stress, failure occurred at 917/sup 0/C, while 7 psi average axial stress produced failure at 669/sup 0/C.

  17. ADVANCED HYDROGEN TRANSPORT MEMBRANES FOR VISION 21 FOSSIL FUEL PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    Shane E. Roark; Anthony F. Sammells; Richard Mackay; Stewart R. Schesnack; Scott R. Morrison; Thomas F. Barton; Sara L. Rolfe; U. Balachandran; Richard N. Kleiner; James E. Stephan; Frank E. Anderson; Aaron L. Wagner; Jon P. Wagner

    2003-10-30

    Eltron Research Inc. and team members CoorsTek, Sued Chemie, Argonne National Laboratory, and NORAM are developing an environmentally benign, inexpensive, and efficient method for separating hydrogen from gas mixtures produced during industrial processes, such as coal gasification. This project was motivated by the National Energy Technology Laboratory (NETL) Vision 21 initiative, which seeks to economically eliminate environmental concerns associated with the use of fossil fuels. Over the past 12 months, this project has focused on four basic categories of dense membranes: (1) mixed conducting ceramic/ceramic composites, (2) mixed conducting ceramic/metal (cermet) composites, (3) cermets with hydrogen permeable metals, and (4) layered composites containing hydrogen permeable alloys. Ultimately, these materials must enable hydrogen separation at practical rates under ambient and high-pressure conditions, without deactivation in the presence of feedstream components such as carbon dioxide, water, and sulfur. The ceramic/ceramic composites demonstrate the lowest hydrogen permeation rates, with a maximum of approximately 0.1 mL/min/cm{sup 2} for 0.5-mm thick membranes at 800 to 950 C. Under equivalent conditions, cermets achieve a hydrogen permeation rate near 1 mL/min/cm{sup 2}, and the metal phase also improves structural stability and surface catalysis for hydrogen dissociation. Furthermore, if metals with high hydrogen permeability are used in cermets, permeation rates near 4 mL/min/cm{sup 2} are achievable with relatively thick membranes. Layered composite membranes have by far the highest permeation rates with a maximum flux in excess of 200 mL {center_dot} min{sup -1} {center_dot} cm{sup -2}. Moreover, these permeation rates were achieved at a total pressure differential across the membrane of 450 psi. Based on these results, effort during the next year will focus on this category of membranes. This report contains long-term hydrogen permeation data over eight

  18. Interfacial engineering of solution-processed Ni nanochain-SiOx (x solar selective absorbers

    Science.gov (United States)

    Yu, Xiaobai; Wang, Xiaoxin; Zhang, Qinglin; Liu, Jifeng

    2016-04-01

    Cermet solar thermal selective absorber coatings are an important component of high-efficiency concentrated solar power (CSP) receivers. The oxidation of the metal nanoparticles in cermet solar absorbers is a great challenge for vacuum-free operation. Recently, we have demonstrated that oxidation is kinetically retarded in solution processed, high-optical-performance Ni nanochain-SiOx cermet system compared to conventional Ni-Al2O3 system when annealed in air at 450-600 °C for several hours. However, for long-term, high-temperature applications in CSP systems, thermodynamically stable antioxidation behavior is highly desirable, which requires new mechanisms beyond kinetically reducing the oxidation rate. Towards this goal, in this paper, we demonstrate that pre-operation annealing of Ni nanochain-SiOx cermets at 900 °C in N2 forms the thermodynamically stable orthorhombic phase of NiSi at the Ni/SiOx interfaces, leading to self-terminated oxidation at 550 °C in air due to this interfacial engineering. In contrast, pre-operation annealing at a lower temperature of 750 °C in N2 (as conducted in our previous work) cannot achieve interfacial NiSi formation directly, and further annealing in air at 450-600 °C for >4 h only leads to the formation of the less stable (metastable) hexagonal phase of NiSi. Therefore, the high-temperature pre-operation annealing is critical to form the desirable orthorhombic phase of NiSi at Ni/SiOx interfaces towards thermodynamically stable antioxidation behavior. Remarkably, with this improved interfacial engineering, the oxidation of 80-nm-diameter Ni nanochain-SiOx saturates after annealing at 550 °C in air for 12 h. Additional annealing at 550 °C in air for as long as 20 h (i.e., 32 h air annealing at >550 °C in total) has almost no further impact on the structural or optical properties of the coatings, the latter being very sensitive to any interfacial changes due to the localized surface plasmon resonances of the metal

  19. Irradiation Experiments on Plutonium Fuels for Fast Reactors

    International Nuclear Information System (INIS)

    An assessment carried out some years ago indicated that cermet fuels might provide the high burn-up and integrity required for fast reactors. An irradiation programme was started at Harwell on (U, Pu)O2 -SS cermet plates and rods, mainly In thermal neutron fluxes, to gain experience of dimensional stability at temperatures typical of modern sodium-cooled fast reactor designs (600-650°C). A subsequent assessment showed that cermets carried a large penalty as far as breeding was concerned and (U, Pu)C was chosen by Harwell for long-term study as an alternative, economic, fast reactor fuel. However, the results from the cermet experiments were of sufficient promise to proceed with parallel irradiation programmes on cermets and carbide. The studies of cermets showed that dimensional instability (swelling and cladding rupture) were caused by the pressures exerted on the steel matrix by the fuel particles, and that the initial density of the fuel particles was important in determining the burn-up at which failure occurred. Further, it was shown that cermets provided a useful vehicle for studying the changes occurring in oxide fuel particles with increasing burn-up. The disappearance of initial porosity and its replacement by fission gas bubbles and segregated solid fission products was studied in some detaiL No significant differences were observed between UO2 and(U,Pu)O2 particles. The initial studies of (U, Pu)C were concerned with the effect of varying composition and structure on swelling and fission gas release. A tantalum-lined nickel alloy cladding material was used to contain both pellet and powder specimens In an irradiation experiment in the core of the Dounreay fast reactor. This showed that the presence of a metal phase in the fuel led to a high swelling rate, that fission gas release was low up to ∼ 3% bum-up, and that a low density powder accommodated the swelling without excessive straining of the can. A subsequent experiment was conducted in a thermal

  20. RESISTÊNCIA À REMOÇÃO POR TRAÇÃO E INFILTRAÇÃO MARGINAL DE COROAS TOTAIS FUNDIDAS, CIMENTADAS EM DENTES NATURAIS RECONSTRUÍDOS COM IONÔMERO DE VIDRO

    Directory of Open Access Journals (Sweden)

    Romualdo Caldeira de ANDRADA

    1997-07-01

    Full Text Available O objetivo deste estudo foi verificar a resistência à remoção por tração e a infiltração marginal de coroas totais fundidas cimentadas com cimento de ionômero de vidro, em dentes reconstruídos com duas formulações de cimento de ionômero de vidro, ou seja, Cermet e "mistura milagrosa", em comparação às coroas totais cimentadas em dentes com preparo para coroa total (sem reconstrução. Foram selecionados trinta molares superiores recém-extraídos, dez para cada condição experimental. Uma liga do sistema prata/estanho (M3 foi utilizada para obtenção das coroas totais. As amostras foram submetidas a ciclagens térmicas nas temperaturas de 5ºC, 37ºC e 55ºC, por sessenta minutos, durante sete dias. Para a última ciclagem térmica, foi utilizado o corante Rhodamina B a 0,1%, em solução aquosa. A seguir, as amostras foram lavadas e mantidas em condições ambientais por vinte e quatro horas, para serem levadas à máquina de ensaios universal, para os testes de remoção por tração axial. A análise de variância mostrou diferença estatisticamente significante, no nível de 5%, dos dentes sem reconstrução (controle, com relação aos dentes reconstruídos com "mistura milagrosa" e dentes reconstruídos com Cermet. Os dentes sem reconstrução apresentaram maior média aos testes de resistência por tração. Verificou-se, pela comparação individual entre as condições avaliadas, que o grupo reconstruído com "mistura milagrosa" e Cermet não mostrou diferença estatisticamente significante. Da mesma forma, foram elaboradas comparações individuais entre as condições avaliadas dos escores de infiltração, em que se pôde observar que houve significância entre os grupos de "mistura milagrosa" e Cermet com o grupo controle (dentes sem reconstrução. Os dentes reconstruídos com "mistura milagrosa" e Cermet não mostraram diferenças estatisticamente significantes entre siThe aim of this work was to measure tensile

  1. ADVANCED HYDROGEN TRANSPORT MEMBRANES FOR VISION 21 FOSSIL FUEL PLANTS

    Energy Technology Data Exchange (ETDEWEB)

    Shane E. Roark; Anthony F. Sammells; Richard Mackay; Scott R. Morrison; Sara L. Rolfe; U. Balachandran; Richard N. Kleiner; James E. Stephen; Frank E. Anderson; Shandra Ratnasamy; Jon P. Wagner; Clive Brereton

    2004-01-30

    The objective of this project is to develop an environmentally benign, inexpensive, and efficient method for separating hydrogen from gas mixtures produced during industrial processes, such as coal gasification. Currently, this project is focusing on four basic categories of dense membranes: (1) mixed conducting ceramic/ceramic composites, (2) mixed conducting ceramic/metal (cermet) composites, (3) cermets with hydrogen permeable metals, and (4) layered composites with hydrogen permeable alloys. The primary technical challenge in achieving the goals of this project will be to optimize membrane composition to enable practical hydrogen separation rates and chemical stability. Other key aspects of this developing technology include catalysis, ceramic processing methods, and separation unit design operating under high pressure. To achieve these technical goals, Eltron Research Inc. has organized a consortium consisting of CoorsTek, Sued Chemie, Inc. (SCI), Argonne National Laboratory (ANL), and NORAM. Hydrogen permeation rates in excess of 50 mL {center_dot} min{sup -1} {center_dot} cm{sup 2} at {approx}440 C were routinely achieved under less than optimal experimental conditions using a range of membrane compositions. Factors that limit the maximum permeation attainable were determined to be mass transport resistance of H{sub 2} to and from the membrane surface, as well as surface contamination. Mass transport resistance was partially overcome by increasing the feed and sweep gas flow rates to greater than five liters per minute. Under these experimental conditions, H2 permeation rates in excess of 350 mL {center_dot} min{sup -1} {center_dot} cm{sup 2} at {approx}440 C were attained. These results are presented in this report, in addition to progress with cermets, thin film fabrication, catalyst development, and H{sub 2} separation unit scale up.

  2. In situ characterization of nanoscale catalysts during anodic redox processes

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Renu [National Institute of Standards and Technology; Crozier, Peter [Arizona State University; Adams, James [Arizona State University

    2013-09-19

    Controlling the structure and composition of the anode is critical to achieving high efficiency and good long-term performance. In addition to being a mixed electronic and ionic conductor, the ideal anode material should act as an efficient catalyst for oxidizing hydrogen, carbon monoxide and dry hydrocarbons without de-activating through either sintering or coking. It is also important to develop novel anode materials that can operate at lower temperatures to reduce costs and minimized materials failure associated with high temperature cycling. We proposed to synthesize and characterize novel anode cermets materials based on ceria doped with Pr and/or Gd together with either a Ni or Cu metallic components. Ceria is a good oxidation catalyst and is an ionic conductor at room temperature. Doping it with trivalent rare earths such as Pr or Gd retards sintering and makes it a mixed ion conductor (ionic and electronic). We have developed a fundamental scientific understanding of the behavior of the cermet material under reaction conditions by following the catalytic oxidation process at the atomic scale using a powerful Environmental Scanning Transmission Electron Microscope (ESTEM). The ESTEM allowed in situ monitoring of structural, chemical and morphological changes occurring at the cermet under conditions approximating that of typical fuel-cell operation. Density functional calculations were employed to determine the underlying mechanisms and reaction pathways during anode oxidation reactions. The dynamic behavior of nanoscale catalytic oxidation of hydrogen and methane were used to determine: ? Fundamental processes during anodic reactions in hydrogen and carbonaceous atmospheres ? Interfacial effects between metal particles and doped ceria ? Kinetics of redox reaction in the anode material

  3. Safety and design concepts of the 400 MW{sub th}-class EFIT accelerator driven transmuter and considerations for further developments

    Energy Technology Data Exchange (ETDEWEB)

    Maschek, W.; Chen, X.-N.; Liu, P.; Rineiski, A.; Flad, M. [Karlsruhe Institute of Technology, Institute for Nuclear and Energy Technologies, P.O. Box 3640, D-76021 Karlsruhe (Germany); Rimpault, G. [CEA, Cadarache Center, DER/SPRC, Laboratory of Core Development Studies, F-13108 Saint Paul Lez Durance (France)

    2010-09-15

    European R and D for ADS design and fuel development is driven in the 6th FP of the EU by the EUROTRANS Programme. In EUROTRANS, the longer-term EFIT development, the european facility for industrial transmutation, aims at a generic conceptual design of a full transmuter. A CERCER U-free fuel core with an MgO matrix and a CERMET core with a Mo-92 matrix have been designed. Both the CERCER and the CERMET EFIT concept were optimized towards: a high transmutation efficiency, high burn-up, low reactivity swing, low power peaking, adequate subcriticality, reasonable beam requirements and a high level of safety. Protected and unprotected transients which are initiated by a mismatch of power-to-flow or resulting from a beam disturbance or overpower situation were analyzed. Potentials which can lead to the introduction of positive reactivity into the core were identified, as e.g. the steam generator tube rupture (SGTR) accident or the pin failure with a gas release from the fission gas plena. Both for the CERCER and the CERMET fuelled core the design and safety analyses are close to completion in EUROTRANS and thus a first preliminary resume can be drawn on the achieved design and safety goals. In addition, scenario studies in the framework of the PATEROS CA project of the 6th FP highlighted the specific needs on transmutation machines serving in countries with different nuclear options. Based on these studies in the 6th FP first reflections can be performed on needs or options for further optimizing an EFIT type ADS. (author)

  4. Correlation of microstructure and thermo-mechanical properties of a novel hydrogen transport membrane

    Science.gov (United States)

    Zhang, Yongjun

    A key part of the FutureGen concept is to support the production of hydrogen to fuel a "hydrogen economy," with the use of clean burning hydrogen in power-producing fuel cells, as well as for use as a transportation fuel. One of the key technical barriers to FutureGen deployment is reliable and efficient hydrogen separation technology. Most Hydrogen Transport Membrane (HTM) research currently focuses on separation technology and hydrogen flux characterization. No significant work has been performed on thermo-mechanical properties of HTMs. The objective of the thesis is to understand the structure-property correlation of HTM and to characterize (1) thermo mechanical properties under different reducing environments and thermal cycles (thermal shock), and (2) evaluate the stability of the novel HTM material. A novel HTM cermet bulk sample was characterized for its physical and mechanical properties at both room temperature and at elevated temperature up to 1000°C. Micro-structural properties and residual stresses were evaluated in order to understand the changing mechanism of the microstructure and its effects on the mechanical properties of materials. A correlation of the microstructural and thermo mechanical properties of the HTM system was established for both HTM and the substrate material. Mechanical properties of both selected structural ceramics and the novel HTM cermet bulk sample are affected mainly by porosity and microstructural features, such as grain size and pore size-distribution. The Young's Modulus (E-value) is positively correlated to the flexural strength for materials with similar crystallographic structure. However, for different crystallographic materials, physical properties are independent of mechanical properties. Microstructural properties, particularly, grain size and crystallographic structure, and thermodynamic properties are the main factors affecting the mechanical properties at both room and high temperatures. The HTM cermet behaves

  5. Vaporisation of candidate nuclear fuels and targets for transmutation of minor actinides

    Energy Technology Data Exchange (ETDEWEB)

    Gotcu-Freis, P., E-mail: p.gotcu@tudelft.nl [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Delft University of Technology, Faculty of Applied Sciences, Mekelweg 15, 2629 JB Delft (Netherlands); Hiernaut, J.-P. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Colle, J.-Y., E-mail: jean-yves.colle@ec.europa.eu [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany); Naestren, C.; Carretero, A. Fernandez; Konings, R.J.M. [European Commission, Joint Research Centre, Institute for Transuranium Elements, P.O. Box 2340, 76125 Karlsruhe (Germany)

    2011-04-15

    The thermal stability and high temperature behaviour of candidate fuels and targets for transmutation of minor actinides has been investigated. Zirconia-based solid solution, MgO-based CERCER and molybdenum-based CERMET fuels containing Am and/or Pu in various concentrations were heated up to 2700 K in a Knudsen cell coupled with a quadrupole mass spectrometer, to measure their vapour pressure and vapour composition. The results reveal that the vaporisation of the actinides from the samples is not only determined by the thermodynamics of the system but is also related to the dynamic evolution of multi-component mixtures with complex composition or microstructure.

  6. The electrochemical oxidation of H{sub 2} and CO at patterned Ni anodes of SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Utz, Annika

    2011-07-01

    In this work, a deeper understanding of the electrochemical oxidation at SOFC anodes was gained by the experimental characterization of patterned Ni anodes in H{sub 2}-H{sub 2}O and CO-CO{sub 2} atmosphere. By high resolution data analysis, the Line Specific Resistance attributed to charge transfer and its dependencies on gas composition, temperature and polarization voltage were identified. Furthermore, the comparison of the performance of patterned and cermet anodes was enabled using a transmission line model. (orig.)

  7. An investigation of microstructure and sliding wear in thermally sprayed WC-Co coatings

    OpenAIRE

    Sudaprasert, Tippaban

    2002-01-01

    Four types of WC-Co cermet powders (conventional WC-12 wt% Co, two different types of conventional WC-17 wt% Co and nanoscale WC-12 wt% Co powders), which have differences in terms of Co content, powder manufacturing process and WC grain size, have been sprayed to form coatings with both the high velocity oxygen-gas fuel (HVOGF) and the high velocity oxygen-liquid fuel (HVOLF) processes. The carbide grain size, powder particle size distribution and phase volume fraction of the starting powder...

  8. High volume production of nanostructured materials

    Science.gov (United States)

    Ripley, Edward B.; Morrell, Jonathan S.; Seals, Roland D.; Ludtka, Gerard M.

    2009-10-13

    A system and method for high volume production of nanoparticles, nanotubes, and items incorporating nanoparticles and nanotubes. Microwave, radio frequency, or infrared energy vaporizes a metal catalyst which, as it condenses, is contacted by carbon or other elements such as silicon, germanium, or boron to form agglomerates. The agglomerates may be annealed to accelerate the production of nanotubes. Magnetic or electric fields may be used to align the nanotubes during their production. The nanotubes may be separated from the production byproducts in aligned or non-aligned configurations. The agglomerates may be formed directly into tools, optionally in compositions that incorporate other materials such as abrasives, binders, carbon-carbon composites, and cermets.

  9. Development and application of DZ9000E portable HVOF system

    Institute of Scientific and Technical Information of China (English)

    Wang Ruijun; Tian Hehong; Lü Yufen; Zhang Tianjian

    2008-01-01

    A new type of DZ9OOOE Oxygen Gaseous HVOF system (GHVOF) is developed which can reduce the cost of coatings and increase the in-situ removability to adapt various working conditions. The whole system is economical, which enables the system to meet the requirement of spraying medium or low cost High Velocity Oxy-Fuel (HVOF) coatings for medium and small job shops. The deposited cermets coatings by the DZ9OOOE system have good performance with average microhardness Hvo.2 of more than 1 000 and the bond strength between coating and substrate of greater than 50 Mpa.

  10. Anchored nanostructure materials and method of fabrication

    Science.gov (United States)

    Seals, Roland D; Menchhofer, Paul A; Howe, Jane Y; Wang, Wei

    2012-11-27

    Anchored nanostructure materials and methods for their fabrication are described. The anchored nanostructure materials may utilize nano-catalysts that include powder-based or solid-based support materials. The support material may comprise metal, such as NiAl, ceramic, a cermet, or silicon or other metalloid. Typically, nanoparticles are disposed adjacent a surface of the support material. Nanostructures may be formed as anchored to nanoparticles that are adjacent the surface of the support material by heating the nano-catalysts and then exposing the nano-catalysts to an organic vapor. The nanostructures are typically single wall or multi-wall carbon nanotubes.

  11. Acoustic emission study on flexural behaviour of WC-Co coatings obtained by atmospheric plasma spray; Estudio por emision acustica del comportamiento a flexion de recubrimientos WC-Co obtenidos por plasma atomosferico

    Energy Technology Data Exchange (ETDEWEB)

    Segovia, F.; Klyatskina, E.; Bonache, V.; Salvador, M. D.; Sanchez, E.; Cantavella, V.; Bloem, C.

    2007-07-01

    Plasma spayed cermet coatings WC-Co are used in a wide range of industrial applications, mainly due to their wear resistance even in corrosive environments. the objective of this work is to analyze mechanical response of hard metal coatings by means of three-and four-points bend tests applying acoustic emission technique to determine failure critical strength. It has been observed the effect of supported charge level in structural damage by means of optical microscopy and scanning electron microscopy. Acoustic emission has allowed us to relate damage level to stresses level and then to understand coatings failure mechanism. (Author) 29 refs.

  12. Large-area metallic photonic lattices for military applications.

    Energy Technology Data Exchange (ETDEWEB)

    Luk, Ting Shan

    2007-11-01

    In this project we developed photonic crystal modeling capability and fabrication technology that is scaleable to large area. An intelligent optimization code was developed to find the optimal structure for the desired spectral response. In terms of fabrication, an exhaustive survey of fabrication techniques that would meet the large area requirement was reduced to Deep X-ray Lithography (DXRL) and nano-imprint. Using DXRL, we fabricated a gold logpile photonic crystal in the <100> plane. For the nano-imprint technique, we fabricated a cubic array of gold squares. These two examples also represent two classes of metallic photonic crystal topologies, the connected network and cermet arrangement.

  13. High Power MPD Nuclear Electric Propulsion (NEP) for Artificial Gravity HOPE Missions to Callisto

    Science.gov (United States)

    McGuire, Melissa L.; Borowski, Stanley K.; Mason, Lee M.; Gilland, James

    2003-01-01

    The following paper documents the results of a one-year multi-center NASA study on the prospect of sending humans to Jupiter's moon, Callisto, using an all Nuclear Electric Propulsion (NEP) space transportation system architecture with magnetoplasmadynamic (MPD) thrusters. The fission reactor system utilizes high temperature uranium dioxide (UO2) in tungsten (W) metal matrix ``cermet'' fuel and electricity is generated using advanced dynamic Brayton power conversion technology. The mission timeframe assumes on-going human Moon and Mars missions and existing space infrastructure to support launch of cargo and crewed spacecraft to Jupiter in 2041 and 2045, respectively.

  14. Study on spinel-based inert anode for aluminium electrolysis

    Institute of Scientific and Technical Information of China (English)

    WANG; Zhao-wen; HU; Xian-wei; LUO; Tao; GAO; Bing-liang; SHI; Zhong-ning; QIU; Zhu-xian

    2005-01-01

    Hot press-sintering was adopted to fabricate inert cermets anodes based on the nickel aluminate and nickel ferrite for use in aluminum electrolysis research. The density of samples, fabricated by hot pressing, is close to the theoretic density. At 900℃, the electrical conductivity of the periments. Effect of anode current on nickel ferrite-based and the reason for it were studied. A theory is that a more uniform metal distribution by improving the hot pressing process gives increased corrosion resistance of the anode.

  15. TOF-SIMS characterization of impurity enrichment and redistribution in solid oxide electrolysis cells during operation

    DEFF Research Database (Denmark)

    Kiebach, Wolff-Ragnar; Norrman, Kion; Chatzichristodoulou, Christodoulos;

    2014-01-01

    TOF-SIMS analyses of state-of-the-art high temperature solid oxide electrolysis cells before and after testing under different operating conditions were performed. The investigated cells consist of an yttria stabilized zirconia (YSZ) electrolyte, a La1-xSrxMnO3-δ composite anode and a Ni-YSZ cermet...... and Ca, increases. For Si, a concentration gradient is found from the gas inlet to the gas outlet. Additionally, a loss of Ni percolation in the active cathode is observed in the same area where the Si enrichment is found. Based on the obtained TOF-SIMS results, the influence of the operating conditions...

  16. Composite fuel behaviour under and after irradiation

    International Nuclear Information System (INIS)

    Two kinds of composite fuels have been irradiated in the SILOE reactor. They are made of UO2 particles dispersed in a molybdenum metallic (CERMET) or a MgAl2O4 ceramic (CERCER) matrix. The irradiation conditions have allowed to reach a 50000 MWd/t U burn-up in these composite fuels after a hundred equivalent full power days long irradiation. The irradiation is controlled by a continuous measure of the pellet centre line temperature. It allows to have information about the TANOX rods thermal behaviour and the fuels thermal conductivities in comparing the centre line temperature versus linear power curves among themselves. Our results show that the CERMET centre line temperature is much lower than the CERCER and UO2 ones: 520 deg. C against 980 deg. C at a 300W/cm linear power. After pin puncturing tests the rods are dismantled to recover each fuel pellet. In the CERCER case, the cladding peeling off has revealed that the fuel came into contact with the cladding and that some of the pellets were linked together. Optical microscopy observations show a changing of the MgAl2O4 matrix state around the UO2 particles at the pellets periphery. This transformation may have caused a swelling and would be at the origin of the pellet-cladding and the pellet-pellet interactions. No specific damage is seen after irradiation. The CERMET pellets are not cracked and remain as they were before irradiation. The CERCER crack network is slightly different from that observed in UO2. Kr retention was evaluated by annealing tests under vacuum at 1580 deg. C or 1700 deg. C for 30 minutes. The CERMET fission gas release is lower than the CERCER one. Inter- and intragranular fission gas bubbles are observed in the UO2 particles after heat treatments. The CERCER pellet periphery has also cracked and the matrix has transformed again around UO2 particles to present a granular and porous aspect. (author). 4 refs, 6 figs, 2 tabs

  17. Hard and wear resistant coatings for cutting tools

    OpenAIRE

    K. Gołombek; L.A. Dobrzański

    2007-01-01

    Purpose: The paper presents investigation results of structure and properties of the cemented carbide tips and cermet tools, both uncoated and coated with single and multiple hard surface layers in the physical (PVD) and chemical (CVD) vapour deposition processes.Design/methodology/approach: SEM, TEM, X-ray, Microhardness, Scratch test, Cutting test.Findings: The TiN+gradient or multi (Ti,Al,Si)N+TiN system coatings deposited with the PVD method in the cathodic arc evaporation CAE onto the s...

  18. Oxygen-producing inert anodes for SOM process

    Science.gov (United States)

    Pal, Uday B

    2014-02-25

    An electrolysis system for generating a metal and molecular oxygen includes a container for receiving a metal oxide containing a metallic species to be extracted, a cathode positioned to contact a metal oxide housed within the container; an oxygen-ion-conducting membrane positioned to contact a metal oxide housed within the container; an anode in contact with the oxygen-ion-conducting membrane and spaced apart from a metal oxide housed within the container, said anode selected from the group consisting of liquid metal silver, oxygen stable electronic oxides, oxygen stable crucible cermets, and stabilized zirconia composites with oxygen stable electronic oxides.

  19. Efecto del volumen de metal cortado y de la velocidad de corte en el desgaste de la herramienta durante el torneado de alta velocidad del acero AISI 1045

    OpenAIRE

    Luis W. Hernández González; Roberto Pérez Rodríguez; Luminita Dumitrescu; Patricia C. Zambrano Robledo; Martha P. Guerrero Mata

    2011-01-01

    En este trabajo se aborda el estudio experimental del efecto del volumen de metal cortado y de la velocidad de corte en el desgaste del flanco de dos insertos de carburos recubiertos y un cermet, durante el torneado de acabado en seco del acero AISI 1045 a velocidades de corte moderada, intermedia y alta. Los resultados fueron comparados utilizando la dimensión volumétrica de la vida útil de la herramienta, el análisis de varianza y el análisis de regresión lineal para describir la relación e...

  20. Solid oxide fuels cells past present and future perspectives for SOFC technologies

    CERN Document Server

    Irvine, John TS

    2012-01-01

    Solid Oxide Fuel Cells (SOFCs) operate at high temperatures allowing more fuel flexibility and also useful heat output and so increase total efficiency, but does give some interesting engineering challenges. Solid Oxide Fuels Cells: Facts and Figures provides clear and accurate data for a selection of SOFC topics from the specific details of Ni cermet anodes, chemical expansion in materials, and the measuring and modelling of mechanical stresses, to the broader scope of the history and present design of cells, to SOFC systems and the future of SOFC. Celebrating Ulf Bossel s work on Solid Oxide

  1. The preliminary design of bearings for the control system of a high-temperature lithium-cooled nuclear reactor

    Science.gov (United States)

    Yacobucci, H. G.; Waldron, W. D.; Walowit, J. A.

    1973-01-01

    The design of bearings for the control system of a fast reactor concept is presented. The bearings are required to operate at temperatures up to 2200 F in one of two fluids, lithium or argon. Basic bearing types are the same regardless of the fluid. Crowned cylindrical journals were selected for radially loaded bearings and modified spherical bearings were selected for bearings under combined thrust and radial loads. Graphite and aluminum oxide are the materials selected for the argon atmosphere bearings while cermet compositions (carbides or nitrides bonded with refractory metals) were selected for the lithium lubricated bearings. Mounting of components is by shrink fit or by axial clamping utilizing differential thermal expansion.

  2. Vaporisation of candidate nuclear fuels and targets for transmutation of minor actinides

    International Nuclear Information System (INIS)

    The thermal stability and high temperature behaviour of candidate fuels and targets for transmutation of minor actinides has been investigated. Zirconia-based solid solution, MgO-based CERCER and molybdenum-based CERMET fuels containing Am and/or Pu in various concentrations were heated up to 2700 K in a Knudsen cell coupled with a quadrupole mass spectrometer, to measure their vapour pressure and vapour composition. The results reveal that the vaporisation of the actinides from the samples is not only determined by the thermodynamics of the system but is also related to the dynamic evolution of multi-component mixtures with complex composition or microstructure.

  3. On the possibility of reprocessing of fuel elements of dispersion type with copper matrix by pyrochemical methods

    International Nuclear Information System (INIS)

    A consideration is given to pyrochemical processes suitable for separation of uranium dioxide from structural materials when reprocessing cermet type fuel elements. The estimation of the possibility to apply liquid antimony and bismuth, potassium and copper chlorides melts is made. The specimens compacted of copper and uranium dioxide powders in a stainless steel can are used as simulators of fuel element sections. It is concluded that the dissolution of structural materials in molten salts at the stage of uranium dioxide concentration is the process of choice for reprocessing of dispersion type fuel elements

  4. Solid state processing of massive uranium mononitride, using uranium and uranium higher nitride powders as starting materials (1962); Preparation a l'etat solide de mononitrure d'uranium massif a partir de poudres d'uranium et de nitrures superieurs d'uranium (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Molinari, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1960-12-15

    The mechanism and the optimum conditions for preparing uranium mononitride have been studied. The results have been used for hot pressing (250 kg/cm{sup 2}, 1000 deg. C, under vacuum) a mixture of powders of uranium and uranium higher nitrides. The products obtained have been identified by X-ray measurements and may be - at will and depending upon the stoichiometry - either UN, or a cermet a U{sub {alpha}}-UN. As revealed by the curved shape of grain boundaries, the sinters obtained here do not easily evolve towards physico-chemical equilibrium when submitted to heat treatment. This behaviour is quite different from the one observed with uranium monocarbide prepared by a similar method. This fact may be ascribed to the insolubility in the matrix UN of particles of UO{sub 2} being present as impurities. The density, hardness and thermal conductivity of these products are higher than those measured on uranium nitride or cermets U-UN obtained by other methods. (author) [French] Apres une etude prealable du mecanisme et des conditions optimales de nitruration de l'uranium, on a montre qu'il est possible de preparer par frittage sous charge (250 kg/cm{sup 2}, 1000 deg. C sous vide) d'un melange de poudres d'uranium et de nitrures superieurs d'uranium, un produit qui a ete identifie par diffraction de rayons X. On peut ainsi obtenir a volonte, soit le monocarbure UN, soit un cermet U{sub {alpha}}-UN dans le cas de compositions sous-stoechiometriques. Au contraire du monocarbure d'uranium prepare dans des conditions analogues, les produits obtenus ici, soumis a un traitement thermique, n'evoluent pas facilement vers un etat d'equilibre physico-chimique caracterise par l'existence de joints de grains rectilignes. On attribue ce phenomene a l'insolubilite de l'impurete UO{sub 2} dans UN. La densite, la durete, la conductibilite thermique de ces produits se revelent superieures a celles des nitrures d'uranium ou des

  5. Long Term Stability Investigation of Solid Oxide Electrolysis Cell with Infiltrated Porous YSZ Air Electrode Under High Current

    DEFF Research Database (Denmark)

    Veltzé, Sune; Ovtar, Simona; Simonsen, Søren Bredmose;

    2015-01-01

    The increased interest in stable and low cost electrodes for solid oxide cells (SOC) has driven the research of electrode preparation to infiltration of catalyst material into porous backbone material. The infiltration method enables a reduction of amount of catalyst material and increases its...... stabilised zirconia (YSZ) backbone air electrode and Ni/YSZ cermet fuel electrode. The SOC was tested at electrolysis conditions under high current (up to -1 A/cm2). The porous YSZ electrodes was infiltrated with gadolinium-doped ceria oxide (CGO), to act as a barrier layer between the catalyst...

  6. Advanced fuel developments for an industrial accelerator driven system prototype

    Energy Technology Data Exchange (ETDEWEB)

    Delage, Fabienne; Ottaviani, Jean Pierre [Commissariat a l' Energie Atomique CEA (France); Fernandez-Carretero, Asuncion; Staicu, Dragos [JRC-ITU (Germany); Boccaccini, Claudia-Matzerath; Chen, Xue-Nong; Mascheck, Werner; Rineiski, Andrei [Forschungszentrum Karlsruhe - FZK (Germany); D' Agata, Elio [JRC-IE (Netherlands); Klaassen, Frodo [NRG, PO Box 25, NL-1755 ZG Petten (Netherlands); Sobolev, Vitaly [SCK-CEN (Belgium); Wallenius, Janne [KTH Royal Institute of Technology (Sweden); Abram, T. [National Nuclear Laboratory - NNL (United Kingdom)

    2009-06-15

    Fuel to be used in an Accelerator Driven System (ADS) for transmutation in a fast spectrum, can be described as a highly innovative concept in comparison with fuels used in critical cores. ADS fuel is not fertile, so as to improve the transmutation performance. It necessarily contains a high concentration ({approx}50%) of minor actinides and plutonium. This unusual fuel composition results in high gamma and neutron emissions during its fabrication, as well as degraded core performance. So, an optimal ADS fuel is based on finding the best compromise between thermal, mechanical, chemical, neutronic and technological constraints. CERCER and CERMET composite fuels consisting of particles of (Pu,MA)O{sub 2} phases dispersed in a magnesia or molybdenum matrix are under investigation within the frame of the ongoing European Integrated Project EUROTRANS (European Research programme for Transmutation) which aims at performing a conceptual design of a 400 MWth transmuter: the European Facility for Industrial Transmutation (EFIT). Performances and safety of EFIT cores loaded with CERCER and CERMET fuels have been evaluated. Out-of-pile and in-pile experiments are carried out to gain knowledge on the properties and the behaviour of these fuels. The current paper gives an overview of the work progress. (authors)

  7. Optimisation of composite metallic fuel for minor actinide transmutation in an accelerator-driven system

    Science.gov (United States)

    Uyttenhove, W.; Sobolev, V.; Maschek, W.

    2011-09-01

    A potential option for neutralization of minor actinides (MA) accumulated in spent nuclear fuel of light water reactors (LWRs) is their transmutation in dedicated accelerator-driven systems (ADS). A promising fuel candidate dedicated to MA transmutation is a CERMET composite with Mo metal matrix and (Pu, Np, Am, Cm)O 2-x fuel particles. Results of optimisation studies of the CERMET fuel targeting to increasing the MA transmutation efficiency of the EFIT (European Facility for Industrial Transmutation) core are presented. In the adopted strategy of MA burning the plutonium (Pu) balance of the core is minimized, allowing a reduction in the reactivity swing and the peak power form-factor deviation and an extension of the cycle duration. The MA/Pu ratio is used as a variable for the fuel optimisation studies. The efficiency of MA transmutation is close to the foreseen theoretical value of 42 kg TW -1 h -1 when level of Pu in the actinide mixture is about 40 wt.%. The obtained results are compared with the reference case of the EFIT core loaded with the composite CERCER fuel, where fuel particles are incorporated in a ceramic magnesia matrix. The results of this study offer additional information for the EFIT fuel selection.

  8. Comparative study of mechanical properties of direct core build-up materials

    Directory of Open Access Journals (Sweden)

    Girish Kumar

    2015-01-01

    Full Text Available Background and Objectives: The strength greatly influences the selection of core material because core must withstand forces due to mastication and para-function for many years. This study was conducted to evaluate certain mechanical properties of commonly used materials for direct core build-up, including visible light cured composite, polyacid modified composite, resin modified glass ionomer, high copper amalgam, and silver cermet cement. Materials and Methods: All the materials were manipulated according to the manufacturer′s recommendations and standard test specimens were prepared. A universal testing machine at different cross-head speed was used to determine all the four mechanical properties. Mean compressive strength, diametral tensile strength, flexural strength, and elastic modulus with standard deviations were calculated. Multiple comparisons of the materials were also done. Results: Considerable differences in compressive strength, diametral tensile strength, and flexural strength were observed. Visible light cured composite showed relatively high compressive strength, diametral tensile strength, and flexural strength compared with the other tested materials. Amalgam showed the highest value for elastic modulus. Silver cermet showed less value for all the properties except for elastic modulus. Conclusions: Strength is one of the most important criteria for selection of a core material. Stronger materials better resist deformation and fracture provide more equitable stress distribution, greater stability, and greater probability of clinical success.

  9. Alternative anode materials for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Goodenough, John B.; Huang, Yun-Hui [Texas Materials Institute, ETC 9.102, 1 University Station, C2200, The University of Texas at Austin, Austin, TX 78712 (United States)

    2007-11-08

    The electrolyte of a solid oxide fuel cell (SOFC) is an O{sup 2-}-ion conductor. The anode must oxidize the fuel with O{sup 2-} ions received from the electrolyte and it must deliver electrons of the fuel chemisorption reaction to a current collector. Cells operating on H{sub 2} and CO generally use a porous Ni/electrolyte cermet that supports a thin, dense electrolyte. Ni acts as both the electronic conductor and the catalyst for splitting the H{sub 2} bond; the oxidation of H{sub 2} to H{sub 2}O occurs at the Ni/electrolyte/H{sub 2} triple-phase boundary (TPB). The CO is oxidized at the oxide component of the cermet, which may be the electrolyte, yttria-stabilized zirconia, or a mixed oxide-ion/electron conductor (MIEC). The MIEC is commonly a Gd-doped ceria. The design and fabrication of these anodes are evaluated. Use of natural gas as the fuel requires another strategy, and MIECs are being explored for this application. The several constraints on these MIECs are outlined, and preliminary results of this on-going investigation are reviewed. (author)

  10. Specific power of liquid-metal-cooled reactors

    International Nuclear Information System (INIS)

    Calculations of the core specific power for conceptual space-based liquid-metal-cooled reactors, based on heat transfer considerations, are presented for three different fuel types: (1) pin-type fuel; (2) cermet fuel; and (3) thermionic fuel. The calculations are based on simple models and are intended to provide preliminary comparative results. The specific power is of interest because it is a measure of the core mass required to produce a given amount of power. Potential problems concerning zero-g critical heat flux and loss-of-coolant accidents are also discussed because these concerns may limit the core specific power. Insufficient experimental data exists to accurately determine the critical heat flux of liquid-metal-cooled reactors in space; however, preliminary calculations indicate that it may be a concern. Results also indicate that the specific power of the pin-type fuels can be increased significantly if the gap between the fuel and the clad is eliminated. Cermet reactors offer the highest specific power because of the excellent thermal conductivity of the core matrix material. However, it may not be possible to take fuel advantage of this characteristic when loss-of-coolant accidents are considered in the final core design. The specific power of the thermionic fuels is dependent mainly on the emitter temperature. The small diameter thermionic fuels have specific powers comparable to those of pin-type fuels. 11 refs., 12 figs, 2 tabs

  11. Development of a feedstock formulation based on PP for MIM of carbides reinforced M2

    Directory of Open Access Journals (Sweden)

    A. Várez

    2008-04-01

    Full Text Available Purpose: Influence of binder composition on some selected properties of feedstock contained powder of M2 with 10% of carbides powders are demonstrated in the paper.Design/methodology/approach: Torque-load test, rheological tests.Findings: Examination of the effect of the binder type and portion on structure and properties of the experimental tool materials with the cermets structure revealed that using the stearic acid reduces viscosity, thus improving technological properties of the feedstock. Employment of polyethylene instead of the high density polypropylene reduces viscosity and torque-load of the investigated feedstocks. Therefore, there is a possibility to increase the portion of the metallic or ceramic powder.Practical implications: It is expected that further investigations of these materials will make possible their injection moulding, as well as their heat treatment increasing hardness and strength of matrix and thereby of the whole tool material. The extrusion process or PIM (Powder Injection Moulding gives the possibility to manufacturing tools materials on the basis of high speed-steel which characterised very good properties with their final or near net shape.Originality/value: In the paper the using extruding of the polymer-powder mix gives the possibility to fabricate cermets which, with their structure and mechanical properties, fill the gap in tool materials between the high-speed steels and cemented carbides.

  12. Stainless steel-supported solid oxide fuel cell with La0.2Sr0.8Ti0.9Ni0.1O3-δ/yttria-stabilized zirconia composite anode

    Science.gov (United States)

    Dayaghi, Amir Masoud; Kim, Kun Joong; Kim, Sunwoong; Park, Juahn; Kim, Sun Jae; Park, Byung Hyun; Choi, Gyeong Man

    2016-08-01

    A metal-supported solid oxide fuel cell (MS-SOFC) is fabricated by co-firing stainless steel (STS) support with a new reduction-resistant oxide-anode and yttria-stabilized zirconia electrolyte. La and Ni co-doped SrTiO3 (La0.2Sr0.8Ti0.9Ni0.1O3-δ, LSTN) which shows Ni exsolution capability is composited with Y0.16Zr0.84O2-δ (YSZ) electrolyte to form a new LSTN-YSZ anode. A cermet layer composed of STS and YSZ (STS-YSZ) is inserted between a porous STS support and a new LSTN-YSZ composite anode for stable contact. With La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode and Ce0.8Gd0.2O2-δ (GDC) interlayer coated on top of co-fired half-cell, YSZ/LSTN-YSZ/STS-YSZ/STS, a newly designed and fabricated cell achieved maximum power density of 185 mW cm-2 at 650 °C. This power density is an improvement over many conventional co-fired MS-SOFCs that use a Ni-cermet anode.

  13. Consideraciones clínicas sobre la resorción radicular externa por impactación dentaria Clinical considerations on external root resorptions caused by dental impactation

    Directory of Open Access Journals (Sweden)

    MA Martínez Lozano

    2003-02-01

    Full Text Available La resorción externa por presión (RREP consiste en una pérdida de tejido dentinario y cementario de las raíces dentarias que se origina a nivel del ligamento periodontal, ocasionada por presiones prolongadas y mantenidas sobre la raíz. Presentamos tres casos con diferente repercusión y tratamiento. Según el distinto grado de afectación se describe y clasifica el tratamiento de RREP a causa de dientes impactados. En cuanto a la restauración de RREP se perfila la cavidad clase V de diseño 5 y el empleo de cermet o amalgamas de plata para su relleno.Pressure external root resorption (PERR is a loss of dental root tissues (dentine and cementum that begin in the periodontal area caused by a impacted teeth. We show three cases with differents clinical situations and therapeutical aspects. Pulpal injurie and difficulty in the post-endodontic cavity acces are characteristiques of these processes. Depending on the level of tissue destruction we discusse the therapeutical orientation in each case. Some treatments like class V type 5 cavities or fillings with cermet glass-ionomer in the more atipical situations (generally after an endodontic treatment are a good choice in these situations.

  14. Effects of carbon nanotubes incorporation on the grain growth and properties of WC/Co nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Faming; Sun Jianfei; Shen Jun [School of Materials Science and Engineering, Harbin Inst. of Tech. (China)

    2005-07-01

    Carbon nanotubes (CNTs) combining unique mechanical and physical properties could offer a kind of nanosized reinforcements for composite materials. Incorporating of CNTs to develop advance engineering composites has become an interesting concept, but the cermets based CNTs composites have been less focused. WC-Co-CNTs nanocomposites were consolidated by spark plasma sintering (SPS) to investigate the effects of CNTs incorporation on the grain growth and mechanical properties of WC-Co nanocomposites. Experimental results show that CNTs could preserve their tubular structures in high temperature SPS process, some CNTs are surviving in the WC-Co fracture surfaces featured bridging and pulling out manner. The interaction between the CNTs and the matrix has a retardation effect of grain growth of WC, but CNTs additions could be resulted in an increase of carbon content in the binder phase that causes enhanced tendency of grain growth, either of which plays the dominated role depending on the CNTs content. The WC-10Co-0.5wt% CNTs nanocomposites possess superior hardness to toughness combinations, which hardness is about 15% and fracture toughness is about 40% higher than that of the pure nano-WC-10Co cermets consolidated under the same process. (orig.)

  15. Conception of transport cask with advanced safety, aimed at transportation and storage of spent nuclear fuel of power reactors, which meets the requirements of IAEA in terms of safety and increased stability during beyond-design-basis accidents and acts of terrorism

    International Nuclear Information System (INIS)

    The report is devoted to the problem of creation of a new generation of multi-purpose universal transport cask with advanced safety, aimed at transportation and storage of spent nuclear fuel (SNF) of power reactors, which meets all requirements of IAEA in terms of safety and increased stability during beyond-design-basis accidents and acts of terrorism. Meeting all IAEA requirements in terms of safety both in normal operation conditions and accidents, as well as increased stability of transport cask (TC) with SNF under the conditions of beyond-design-basis accidents and acts of terrorism has been achieved in the design of multi-purpose universal TC due to the use of DU (depleted uranium) in it. At that, it is suggested to use DU in TC, which acts as effective gamma shield and constructional material in the form of both metallic depleted uranium and metal-ceramic mixture (cermet), based on stainless or carbon steel and DU dioxide. The metal in the cermet is chosen to optimize cask performance. The use of DU in the design of multi-purpose universal TC enables getting maximum load of the container for spent nuclear fuel when meeting IAEA requirements in terms of safety and providing increased stability of the container with SNF under conditions of beyond-design-basis accident and acts of terrorism

  16. Californium Recovery from Palladium Wire

    Energy Technology Data Exchange (ETDEWEB)

    Burns, Jon D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-08-01

    The recovery of 252Cf from palladium-252Cf cermet wires was investigated to determine the feasibility of implementing it into the cermet wire production operation at Oak Ridge National Laboratory’s Radiochemical Engineering Development Center. The dissolution of Pd wire in 8 M HNO3 and trace amounts of HCl was studied at both ambient and elevated temperatures. These studies showed that it took days to dissolve the wire at ambient temperature and only 2 hours at 60°C. Adjusting the ratio of the volume of solvent to the mass of the wire segment showed little change in the kinetics of dissolution, which ranged from 0.176 mL/mg down to 0.019 mL/mg. A successful chromatographic separation of 153Gd, a surrogate for 252Cf, from Pd was demonstrated using AG 50x8 cation exchange resin with a bed volume of 0.5 mL and an internal diameter of 0.8 cm.

  17. METAL-MATRIX COMPOSITES AND THERMAL SPRAY COATINGS FOR EARTH MOVING MACHINES

    Energy Technology Data Exchange (ETDEWEB)

    D. Trent Weaver; Matthew T. Kiser; Frank W. Zok; Carlos G. Levi; Jeffrey Hawk

    2004-02-01

    In an effort to realize minimum of a 2x increase in wear life of ground engaging components used on mining machines, two potentially cost effective processes were explored for the production of tailored, highly abrasion resistant materials: (1) hybrid pressure casting of steel composites, and (2) arc lamp fusing of thermal spray coatings. Steel composites comprised of cermet or oxide hard particles were successfully produced using pressure casting processes, although a cost effective process has not yet been identified for oxide particles. Both composites achieved project wear targets in high stress gouging wear, but the cermet composites did not meet the targets in impact wear, due to poor matrix toughness resulting from particle dissolution. Oxide composites had superior toughness and are expected to meet impact wear goals. Arc lamp processing of thermal spray coatings was successfully demonstrated to produce a metallurgical bond at the coating interface. Functionally graded materials were developed and successfully fused to allow for the accommodation of thermal process stresses in an intermediate layer. Ultimately, three functionally graded materials were identified as having high stress, three-body abrasion resistance sufficient to exceed project goals.

  18. Design of a Uranium Dioxide Spheroidization System

    Science.gov (United States)

    Cavender, Daniel P.; Mireles, Omar R.; Frendi, Abdelkader

    2013-01-01

    The plasma spheroidization system (PSS) is the first process in the development of tungsten-uranium dioxide (W-UO2) fuel cermets. The PSS process improves particle spherocity and surface morphology for coating by chemical vapor deposition (CVD) process. Angular fully dense particles melt in an argon-hydrogen plasma jet at between 32-36 kW, and become spherical due to surface tension. Surrogate CeO2 powder was used in place of UO2 for system and process parameter development. Particles range in size from 100 - 50 microns in diameter. Student s t-test and hypothesis testing of two proportions statistical methods were applied to characterize and compare the spherocity of pre and post process powders. Particle spherocity was determined by irregularity parameter. Processed powders show great than 800% increase in the number of spherical particles over the stock powder with the mean spherocity only mildly improved. It is recommended that powders be processed two-three times in order to reach the desired spherocity, and that process parameters be optimized for a more narrow particles size range. Keywords: spherocity, spheroidization, plasma, uranium-dioxide, cermet, nuclear, propulsion

  19. Sliding and Abrasive Wear Behavior of WC-CoCr Coatings with Different Carbide Sizes

    Science.gov (United States)

    Thakur, Lalit; Arora, Navneet

    2013-02-01

    This study examines the sliding and abrasive wear behaviors of high-velocity oxy-fuel (HVOF)-sprayed WC-CoCr coatings with different WC grain sizes. The HVOF coating deposition was assisted by in-flight particle temperature and velocity measurement system. The powder feedstocks and their corresponding coatings were characterized by means of XRD and Field Emission Scanning Electron Microscope analysis. Hardness, porosity, and indentation fracture toughness of these coatings were calculated and compared with each other. Sliding wear resistance of these coatings was calculated using pin-on-disk tribometer (ASTM G99-90). The two-body abrasion was quantified by sliding the samples over silicon carbide (SiC) abrasive paper bonded to a rotating flat disk of auto-polisher. The mechanism of materials' removal in both the sliding and abrasive wears was studied and discussed on microstructural investigations. It was observed that fine grain WC-CoCr cermet coating exhibits higher sliding and abrasive wear resistances as compared with conventional cermet coating.

  20. Microstructure, mechanical and electrical properties of Ni-YSZ anode supported solid oxide fuel cells

    Directory of Open Access Journals (Sweden)

    G. Matula

    2008-07-01

    Full Text Available Purpose: Investigation of the Ni-YSZ cermets for anode supported solid oxide fuel cells (SOFC prepared byuniaxial pressure, sintered and reduced pellets of NiO-YSZ.Design/methodology/approach: Density examination, shrinkage examination, transverse rupture strengthtests, microstructure examination.Findings: Basing on the investigations of the anode Ni-YSZ type fabricated with powder metallurgy it wasfound of that density of sintered samples depends on NiO portion, temperature of sintering and reducing. Increaseof sintering temperature causes increase of density. Moreover increase of NiO portion and reducing temperaturecauses decrease of density and linear contraction of anode.Practical implications: The Ni-YSZ cermets fabricated using of powder metallurgy are characterized by verygood properties and can be used as SOFC anode. Powder metallurgy gives the possibility to manufacturing cermetused as an anode for SOFC on the basis of Ni-YSZ.Originality/value: Investigations of compacted, sintered and reduced samples with different amount of NiOgives information about optimal manufacturing conditions and volume fraction of NiO/YSZ components. Thisinformation is especially important at production process of extruded tubes.

  1. System and safety studies of accelerator driven systems for transmutation. Annual report 2008

    Energy Technology Data Exchange (ETDEWEB)

    Arzhanov, Vasily; Bergloef, Calle; Fokau, Andrei; Jolkkonen, Mikael; Runevall, Odd; Sandberg, Nils; Tesinsky, Milan; Wallenius, Janne; Youpeng Zhang (Div. of Reactor Physics, Royal Institute of Technology, Stockholm (Sweden))

    2009-07-15

    Within this project, research on design and safety of subcritical reactors for recycling of minor actinides is performed. During 2008, the reactor physics division at KTH has made a design study of a source efficient ADS with nitride fuel, based on the EFIT design made within the EUROTRANS project. Transient analysis for EFIT-400 ADS with cercer and cermet fuels was made with SAS4A, taking into account flow reversal phenomena. Using Pulsed Neutron Source techniques, reference reactivity values for detectors in the sub-critical YALINA booster facility were obtained and it was observed that the results carry strong spatial effects. It was shown that the beam trip technique can be used to obtain the reactivity at beam trips and the values can be used for calibration of a current-to-flux reactivity indicator. Multi-scale modelling of helium desorption from molybdenum was performed, with the final aim to predict the in-pile behaviour of Mo based CERMET fuel. Good agreement with experimental data was obtained, except at the highest temperatures

  2. PROPERTIES OF TiC-Al2O3/Fe COMPOSITES PREPARED BY SHS/PHIP%SHS/PHIP制备TiC-Al2O3/Fe复合材料的性能

    Institute of Scientific and Technical Information of China (English)

    张卫方; 韩杰才; 杜善义; 习年生; 陶春虎

    2001-01-01

    对SHS/PHIP技术制备出的TiC-Al2O3/Fe复合材料的性能进行了测试和分析.结果表明,TiC-Al2O3/Fe复合材料具有良好的综合力学性能.材料具有很高的比刚度.金属Fe相的加入,较大地提高了材料的抗弯强度和断裂韧性.TiC-Al2O3复相陶瓷为典型的脆性断裂;随着Fe含量的增加,材料具有明显韧性断裂的特征.%The influence of Fe content on the properties of TiC-Al2O3/Fe composites prepared by SHS/PHIP was studied. The results show that the TiC-Al2O3/Fe cermets prepared by SHS/PHIP possess high mechanical properties such as well-improved flexural strength and fracture toughness owing to the addition of Fe, and highly special stiffness. The TiC-Al2O3 ceramic exhibits the typical brittle fracture behavior. However, the TiC-Al2O3/Fe cermets exhibit obvious characteristic of tough fracture with Fe content increasing.

  3. RSMASS-D nuclear thermal propulsion and bimodal system mass models

    Energy Technology Data Exchange (ETDEWEB)

    King, D.B. [DSWA/FC, Thermionic Evaluation Facility 801 University Blvd. SE Albuquerque, New Mexico (United States); Marshall, A.C. [DSWA/FC, Thermionic Evaluation Facility 801 University Blvd. SE Albuquerque, New Mexico (United States)

    1997-01-01

    Two relatively simple models have been developed to estimate reactor, radiation shield, and balance of system masses for a particle bed reactor (PBR) nuclear thermal propulsion concept and a cermet-core power and propulsion (bimodal) concept. The approach was based on the methodology developed for the RSMASS-D models. The RSMASS-D approach for the reactor and shield sub-systems uses a combination of simple equations derived from reactor physics and other fundamental considerations along with tabulations of data from more detailed neutron and gamma transport theory computations. Relatively simple models are used to estimate the masses of other subsystem components of the nuclear propulsion and bimodal systems. Other subsystem components include instrumentation and control (I&C), boom, safety systems, radiator, thermoelectrics, heat pipes, and nozzle. The user of these models can vary basic design parameters within an allowed range to achieve a parameter choice which yields a minimum mass for the operational conditions of interest. Estimated system masses are presented for a range of reactor power levels for propulsion for the PBR propulsion concept and for both electrical power and propulsion for the cermet-core bimodal concept. The estimated reactor system masses agree with mass predictions from detailed calculations with xx percent for both models. {copyright} {ital 1997 American Institute of Physics.}

  4. Preliminary study of impact of fuel options on performance of Nuclear Thermal Propulsion (NTP) concepts

    Science.gov (United States)

    Ludewig, H.; Todosow, M.; Montanez, P.; Bezler, P.

    2002-01-01

    A study of the sensitivity to fuel type and composition on the performance of two Nuclear Thermal Rocket (NTR) concepts is presented. The performance measures are the specific impulse and the thrust/weight (T/W) ratio, and the concepts considered are based on the NERVA and ESCORT reactors. For the NERVA concept use of alternative fissile materials showed significant reductions in core mass which improves the values of T/W. However, launch safety considerations may be the dominant factor in selection of fissile material. The use of ternary carbide based fuels allows higher exhaust temperatures, but due to their higher density reduces T/W. The use of molybdenum based cermets, and cermets which use UN or UC2 fuel allow for significant reductions in the reactor mass, and thus an increase in T/W. However, the use of molybdenum reduces the exhaust temperature. Both these results for the NERVA and ESCORT based systems indicate the need to axially zone the core. The lower temperature but lighter material should be used in the cooler (<2500 K) parts of the core, and the heavier, higher temperature material should be used in the outlet end of the core. In addition, the thermal response, and implied stress is estimated for the NERVA concept. .

  5. Electrochemical reduction of CO 2 in solid oxide electrolysis cells

    Science.gov (United States)

    Zhan, Zhongliang; Zhao, Lin

    This paper describes results on the electrochemical reduction of carbon dioxide using the same device as the typical planar nickel-YSZ cermet electrode supported solid oxide fuel cells (H 2-CO 2, Ni-YSZ|YSZ|LSCF-GDC, LSCF, air). Operation in both the fuel cell and the electrolysis mode indicates that the electrodes could work reversibly for the charge transfer processes. An electrolysis current density of ≈1 A cm -2 is observed at 800 °C and 1.3 V for an inlet mixtures of 25% H 2-75% CO 2. Mass spectra measurement suggests that the nickel-YSZ cermet electrode is highly effective for reduction of CO 2 to CO. Analysis of the gas transport in the porous electrode and the adsorption/desorption process over the nickel surface indicates that the cathodic reactions are probably dominated by the reduction of steam to hydrogen, whereas carbon monoxide is mainly produced via the reverse water gas shift reaction.

  6. Neutronics Study on LEU Nuclear Thermal Rocket Fuel Options

    Energy Technology Data Exchange (ETDEWEB)

    Venneri, Paolo; Kim, Yong Hee [KAIST, Daejeon (Korea, Republic of); Howe, Steven [CSNR, Idaho (United States)

    2014-10-15

    This has resulted in a non-trivial simplification of the tasks needed to develop such an engine and the quick initial development of the concept. There are, however, a series of key core-design choices that are currently under scrutiny in the field that have to be resolved in order for the LEU-NTR to be fully developed. The most important of these is the choice of fuel: carbide composite or tungsten cermet. This study presents a first comparison of the two fuel types specifically in the neutronic application to the LEU-NTR, keeping in mind the unique neutronic environment and the system requirements of the system. The scope of the study itself is limited to a neutronics study of the two fuels and only a cursory overview of the material properties of the fuels themselves... The results of this study have led to two major conclusions. First of all is that the carbide composite fuel is, from a neutronics standpoint, a much better fuel. It has a low absorption cross-section, is inherently a strong moderator, is able to achieve a higher reactivity using smaller amounts of fissile material, and can potentially enable a smaller reactor. Second is that despite its neutronic difficulties (high absorption, inferior moderating abilities, and lower k-infinity values) the tungsten cermet fuel is still able to perform satisfactorily in an LEU-NTR, largely due to its ability to have an extremely high fuel loading.

  7. Estudio por emisión acústica del comportamiento a flexión de recubrimientos WC-Co obtenidos por plasma atmosférico

    Directory of Open Access Journals (Sweden)

    Segovia, F.

    2007-12-01

    Full Text Available Plasma sprayed cermet coatings WC-Co are used in a wide range of industrial applications, mainly due to their wear resistance even in corrosive environments. The objective of this work is to analyze mechanical response of hard metal coatings by means of three- and four-points bend tests applying acoustic emission technique to determine failure critical strength. It has been observed the effect of supported charge level in structural damage by means of optical microscopy and scanning electron microscopy. Acoustic emission has allowed us to relate damage level to stresses level and then to understand coatings failure mechanism.

    Los recubrimientos de cermet WC-Co proyectados por plasma se utilizan en un amplio rango de aplicaciones industriales, principalmente por su resistencia al desgaste, incluso en medio corrosivo. El objetivo de este trabajo es analizar la respuesta mecánica de los recubrimientos de metal duro mediante ensayos de flexión a 3 y 4 puntos aplicando el método de emisión acústica para determinar las tensiones críticas de fallo. Se ha observado el efecto del nivel de carga soportado en el dañado estructural mediante microscopia óptica y electrónica de barrido. La emisión acústica ha permitido relacionar el grado de dañado con el nivel de tensiones y, así, entender el mecanismo de fallo de los recubrimientos.

  8. Fuel reforming and electrical performance studies in intermediate temperature ceria - gadolinia-based SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Livermore, S.J.A. [CERAM Research, Stoke-on-Trent (United Kingdom); Birchall Centre for Inorganic Chemistry and Materials Science, Department of Chemistry, Keele Univ. (United Kingdom); Cotton, J.W. [CERAM Research, Stoke-on-Trent (United Kingdom); Ormerod, R.M. [Birchall Centre for Inorganic Chemistry and Materials Science, Department of Chemistry, Keele Univ. (United Kingdom)

    2000-03-01

    The methane reforming and carbon deposition characteristics of two nickel/ceria-gadolinia cermet anodes have been studied over the temperature range 550-700 C, for use in intermediate temperature ceria-gadolinia (CGO)-based solid oxide fuel cells (SOFCs), using conventional catalytic methods and temperature-programmed spectroscopy. The electrical performance and durability of planar CGO-based SOFCs with a 280-{mu}m-thick CGO electrolyte, screen printed cathode and different screen printed nickel/CGO cermet anodes have been studied over the temperature range 500-650 C. Temperature-programmed reduction has been used to study the reduction characteristics of the anodes, and indicates the presence of 'bulk' NiO particles and smaller NiO particles in intimate contact with the ceria. Both anodes show good activity towards methane steam reforming with methane activation occurring at temperatures as low as 210 C; steady-state steam reforming of methane was observed using a methane-rich mixture at 650 C, with 20% methane conversion. Post-reaction temperature-programmed oxidation has been used to determine the amount of carbon deposited during reforming and the strength of its interaction with the anode. (orig.)

  9. Highly redox-resistant solid oxide fuel cell anode materials based on La-doped SrTiO3 by catalyst impregnation strategy

    Science.gov (United States)

    Shen, X.; Sasaki, K.

    2016-07-01

    An anode backbone using 40 wt% (ZrO2)0.89(Sc2O3)0.1(CeO2)0.01 (SSZ)-Sr0.9La0.1TiO3 (SLT) cermet was prepared for SSZ electrolyte-supported SOFC single cells. 15 mgcm-2 Ce0.9Gd0.1O2 (GDC) was impregnated to totally cover the SSZ-SLT anode backbone surface acting as a catalyst, and the cell voltage achieved 0.865 V at 200 mAcm-2 using (La0.75Sr0.25)0.98MnO3 (LSM)-SSZ cathode in 3%-humidified hydrogen fuel at 800 °C. Cell performance was substantially improved from 0.865 V to >0.97 V when 0.03 mgcm-2 Pd or Ni was further incorporated as a secondary catalyst into the anode layer. 50 redox cycles were performed to investigate redox stability of this high performance anode. It was found that even after the 50 redox cycle long-term degradation test, cell voltage at 200 mAcm-2 was retained around 0.94 V, higher than the cell performance using the conventional Ni-SSZ cermet anode. The catalytically-active reaction sites at ceria-Pd or ceria-Ni may account for the excellent performance, and the extremely low metal catalyst concentration prevent serious metal aggregation in achieving excellent redox stability.

  10. A multilayer innovative solution to improve the adhesion of nanocrystalline diamond coatings

    Energy Technology Data Exchange (ETDEWEB)

    Poulon-Quintin, A., E-mail: poulon@icmcb-bordeaux.cnrs.fr [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France); Faure, C.; Teulé-Gay, L.; Manaud, J.P. [CNRS, ICMCB, UPR 9048, F-33600 Pessac (France); Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac (France)

    2015-03-15

    Highlights: • Improvement of the NCD adhesion on WC-12%Co substrates for tooling applications using a multi-interlayer additional system. • Reduction of the graphite layer thickness and continuity at the interface with the diamond. • Transmission electron microscopy study for a better understanding of the diffusion phenomena occurring at the interfaces. - Abstract: Nano-crystalline diamond (NCD) films grown under negative biased substrates by chemical vapor deposition (CVD) are widely used as surface overlay coating onto cermet WC-Co cutting tools to get better performances. To improve the diamond adhesion to the cermet substrate, suitable multi-layer systems have been added. They are composed of a cobalt diffusion barrier close to the substrate (single and sequenced nitrides layers) coated with a nucleation extra layer to improve the nucleus density of diamond during CVD processing. For all systems, before and after diamond deposition, transmission electron microscopy (TEM) has been performed for a better understanding of the diffusion phenomena occurring at the interfaces and to evaluate the presence of graphitic species at the interface with the diamond. Innovative multilayer system dedicated to the regulation of cobalt diffusion coated with a bilayer system optimized for the carbon diffusion control, is shown as an efficient solution to significantly reduce the graphite layer formation at the interface with the diamond down to 10 nm thick and to increase the adhesion of NCD diamond layer as scratch-tests confirm.

  11. A novel Ni/ceria-based anode for metal-supported solid oxide fuel cells

    Science.gov (United States)

    Rojek-Wöckner, Veronika A.; Opitz, Alexander K.; Brandner, Marco; Mathé, Jörg; Bram, Martin

    2016-10-01

    For optimization of ageing behavior, electrochemical performance, and sulfur tolerance of metal-supported solid oxide fuel cells a new anode concept is introduced, which is based on a Ni/GDC cermet replacing the established Ni/YSZ anodes. In the present work optimized processing parameters compatible with MSC substrates are specified by doing sintering studies on pressed bulk specimen and on real porous anode structures. The electrochemical performance of the Ni/GDC anodes was characterized by means of symmetrical electrolyte supported model-type cells. In this study, three main objectives are pursued. Firstly, the effective technical realization of the Ni/GDC concept is demonstrated. Secondly, the electrochemical behavior of Ni/GDC porous anodes is characterized by impedance spectroscopy and compared with the current standard Ni/YSZ anode. Further, a qualitative comparison of the sulfur poisoning behavior of both anode types is presented. Thirdly, preliminary results of a successful implementation of the Ni/GDC cermet into a metal-supported single cell are presented.

  12. Tribological study of hard coatings without cobalt intended to isolation components of PWR primary cooling system; Etude tribologique de revetements durs sans cobalt destines aux organes d`isolement du circuit primaire des REP

    Energy Technology Data Exchange (ETDEWEB)

    Cachon, L.

    1995-10-18

    The objective is to qualify coatings without cobalt to replace ``Stellites`` coatings in isolation valves of PWR primary cooling system, as Co is activated when passing in the reactor core and contaminated the cooling loop. Three families of coatings were tested: PVD thin films from 1 to 8 {mu}m monolayers of Cr/C{sub x} with x varying between 1.6 and 9.5 at% or multilayers of pure chromium and Cr/C{sub 1.6} at%, coatings with a thickness between 100 and 200 {mu}m of cermets NiCr{sub y} (y varying from 5 to 35 at%) matrix binding chromium or tungsten carbides, and thick coatings 2 mm thickness of cermets Nitronic 60 or Inconel 625 matrix binding 10, 20 or 30% titanium or niobium carbides. Stellite 6 (2 mm) is the reference coating for tribology. Coatings were qualified and selected by thermal shocks, corrosion and plane friction. The thin film and the thick families were disqualified by their destruction or by their high friction coefficient. Then coatings between 100 and 200 {mu}m were used in a valve mock-up working in PWR primary cooling system pressure and temperature conditions. Tests show that these coatings have better wear or tightness performances than stellite 6, except for a slightly higher friction coefficient. (A.B.).

  13. Conception of transport cask with advanced safety, aimed at transportation and storage of spent nuclear fuel of power reactors, which meets the requirements of IAEA in terms of safety and increased stability during beyond-design-basis accidents and acts of terrorism

    Energy Technology Data Exchange (ETDEWEB)

    Il' kaev, R.I.; Matveev, V.Z.; Morenko, A.I.; Shapovalov, V.I. [Russian Federal Nuclear Center - All-Russian Research Inst. of Experimental Physics, Sarov (Russian Federation); Semenov, A.G.; Sergeyev, V.M.; Orlov, V.K. [All-Russian Research Inst. of Inorganic Materials, Moscow (Russian Federation); Shatalov, V.V.; Gotovchikov, V.T.; Seredenko, V.A. [All-Russian Research Inst. of Applied Chemistry, Moscow (Russian Federation); Haire, Jonathan M.; Forsberg, C.W. [Oak Ridge National Lab., Oak Ridge (United States)

    2004-07-01

    The report is devoted to the problem of creation of a new generation of multi-purpose universal transport cask with advanced safety, aimed at transportation and storage of spent nuclear fuel (SNF) of power reactors, which meets all requirements of IAEA in terms of safety and increased stability during beyond-design-basis accidents and acts of terrorism. Meeting all IAEA requirements in terms of safety both in normal operation conditions and accidents, as well as increased stability of transport cask (TC) with SNF under the conditions of beyond-design-basis accidents and acts of terrorism has been achieved in the design of multi-purpose universal TC due to the use of DU (depleted uranium) in it. At that, it is suggested to use DU in TC, which acts as effective gamma shield and constructional material in the form of both metallic depleted uranium and metal-ceramic mixture (cermet), based on stainless or carbon steel and DU dioxide. The metal in the cermet is chosen to optimize cask performance. The use of DU in the design of multi-purpose universal TC enables getting maximum load of the container for spent nuclear fuel when meeting IAEA requirements in terms of safety and providing increased stability of the container with SNF under conditions of beyond-design-basis accident and acts of terrorism.

  14. Mixed conductor anodes: Ni as electrocatalyst for hydrogen conversion

    DEFF Research Database (Denmark)

    Primdahl, S.; Mogensen, Mogens Bjerg

    2002-01-01

    (0.6)Gd(0.4)O(1.8) (CG4) ceramic, a La(0.75)Sr(0.25)Cr(0.97)V(0.03)O(3) (LSCV) ceramic and a Ti(0.22) Y(0.16)Zr(0.92)O(2.52) (TiYSZ) ceramic, Addition of small amounts ( approximate to I w/o) of Ni to the electrode surface is found to improve electrode performance on mixed electronic and ionic......Five types of anodes for solid oxide fuel cells (SOFC) are examined on an yttria-stabilised zirconia (YSZ) electrolyte by impedance spectroscopy at 850 degreesC in hydrogen. The examined porous anodes are a Ni/Zr(0.92)Y(0.16)O(2.08) (Ni/YSZ) cermet, a Ni/Ce(0.9)Gd(0.1)O(1.95) (Ni/CGI) cermet, a Ce...... conductors (MIEC's), distinctly in the low-frequency part of the impedance spectra. An effect of isotope exchange (H(2)/H(2)O to D(2)/D(2)O) is observed for all anodes. The low-frequency limitation is suggested to be hydrogen adsorption and/or dissociation on the surface of MIEC electrodes, (C) 2002 Elsevier...

  15. A Novel Processing Route for Ni-doped Alumina Composites

    Institute of Scientific and Technical Information of China (English)

    JING Mao-xiang; SHEN Xiang-qian; ZHOU Jian-xin; LI Dong-hong; LI Wang-xing

    2006-01-01

    Alumina-based composites containing 0-15wt% Ni metallic phase were produced by hot press-sintering Ni-coated alumina powders. The Ni-coated alumina powders were prepared by the aqueous heterogeneous precipitation of alumina micro-powders and nickel sulfate salt followed by reduction process. The microstructural features and dispersion of Ni phase in Ni-coated alumina powders and the subsequent alumina-Ni cermets were investigated using scanning electron microscope (SEM), X-ray diffractometer (XRD), and transmission electron microscope (TEM). The relative density of the hot press-sintered composites was measured with the Archimedes' method while the fracture strength and the fracture toughness were defined with the three-point bending method and the micro-indentation fracture method. In the formation of alumina-Ni cermets from sintered Ni-coated alumina powders, Ni phase to some extent limits the densification rate and stifles the coarsening and growing process of alumina grains. The Ni phase is found to be located at the interfaces and the triple-joint junctions of alumina grains which results into alteration of the fracture mode of alumina and its increased fracture strength and fracture toughness if compared with monolithic alumina.

  16. High sensitivity and high resolution element 3D analysis by a combined SIMS–SPM instrument

    Directory of Open Access Journals (Sweden)

    Yves Fleming

    2015-04-01

    Full Text Available Using the recently developed SIMS–SPM prototype, secondary ion mass spectrometry (SIMS data was combined with topographical data from the scanning probe microscopy (SPM module for five test structures in order to obtain accurate chemical 3D maps: a polystyrene/polyvinylpyrrolidone (PS/PVP polymer blend, a nickel-based super-alloy, a titanium carbonitride-based cermet, a reticle test structure and Mg(OH2 nanoclusters incorporated inside a polymer matrix. The examples illustrate the potential of this combined approach to track and eliminate artefacts related to inhomogeneities of the sputter rates (caused by samples containing various materials, different phases or having a non-flat surface and inhomogeneities of the secondary ion extraction efficiencies due to local field distortions (caused by topography with high aspect ratios. In this respect, this paper presents the measured relative sputter rates between PVP and PS as well as in between the different phases of the TiCN cermet.

  17. In situ surface reduction of a NiO-YSZ-alumina composite using scanning probe microscopy

    DEFF Research Database (Denmark)

    Hansen, Karin Vels; Jacobsen, Torben; Thydén, Karl Tor Sune;

    2014-01-01

    In situ surface reductions of NiO-YSZ-Al2O3 composites into Ni-YSZ-Al2O3 cermets were carried out at 312–525 °C in a controlled atmosphere high-temperature scanning probe microscope (CAHT-SPM) in dry and humidified 9 % H2 in N2. The reduction of NiO was followed by contact mode scanning of topogr......In situ surface reductions of NiO-YSZ-Al2O3 composites into Ni-YSZ-Al2O3 cermets were carried out at 312–525 °C in a controlled atmosphere high-temperature scanning probe microscope (CAHT-SPM) in dry and humidified 9 % H2 in N2. The reduction of NiO was followed by contact mode scanning...... dependent and followed the Arrhenius equation. For samples reduced in dry hydrogen, the Arrhenius plot showed two regions with different activation energies. Scanning electron microscopy confirmed a difference in microstructure between these temperature regimes. A strong retarding effect of steam (H2O...

  18. Development of wear-resistant ceramic coatings for diesel engine components

    Energy Technology Data Exchange (ETDEWEB)

    Naylor, M.G.S. (Cummins Engine Co., Inc., Columbus, IN (United States))

    1992-06-01

    The tribological properties of a variety of advanced coating materials have been evaluated under conditions which simulate the piston ring -- cylinder liner environment near top ring reversal in a heavy duty diesel engine. Coated ring'' samples were tested against a conventional pearlitic grey cast iron liner material using a high temperature reciprocating wear test rig. Tests were run with a fresh CE/SF 15W40lubricant at 200 and 350{degrees}C, with a high-soot, engine-tested oil at 200{degrees}C and with no lubrication at 200{degrees}C. For lowest wear under boundary lubricated conditions, the most promising candidates to emerge from this study were high velocity oxy-fuel (HVOF) Cr{sub 3} C{sub 2} - 20% NiCr and WC - 12% Co cermets, low temperature arc vapor deposited (LTAVD) CrN and plasma sprayed chromium oxides. Also,plasma sprayed Cr{sub 2}O{sub 3} and A1{sub 2}O{sub 3}-ZrO{sub 2} materials were found to give excellent wear resistance in unlubricated tests and at extremely high temperatures (450{degrees}C) with a syntheticoil. All of these materials would offer substantial wear reductions compared to the conventional electroplated hard chromium ring facing and thermally sprayed metallic coatings, especially at high temperatures and with high-soot oils subjected to degradation in diesel environments. The LTAVD CrN coating provided the lowest lubricated wear rates of all the materials evaluated, but may be too thin (4 {mu}m) for use as a top ring facing. Most of the coatings evaluated showed higher wear rates with high-soot, engine-tested oil than with fresh oil, with increases of more than a factor of ten in some cases. Generally, metallic materials were found to be much more sensitive to soot/oil degradation than ceramic and cermet coatings. Thus, decreased soot sensitivity'' is a significant driving force for utilizing ceramic or cermet coatings in diesel engine wear applications.

  19. Development of wear-resistant ceramic coatings for diesel engine components. Volume 1, Coating development and tribological testing: Final report: DOE/ORNL Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    Naylor, M.G.S. [Cummins Engine Co., Inc., Columbus, IN (United States)

    1992-06-01

    The tribological properties of a variety of advanced coating materials have been evaluated under conditions which simulate the piston ring -- cylinder liner environment near top ring reversal in a heavy duty diesel engine. Coated ``ring`` samples were tested against a conventional pearlitic grey cast iron liner material using a high temperature reciprocating wear test rig. Tests were run with a fresh CE/SF 15W40lubricant at 200 and 350{degrees}C, with a high-soot, engine-tested oil at 200{degrees}C and with no lubrication at 200{degrees}C. For lowest wear under boundary lubricated conditions, the most promising candidates to emerge from this study were high velocity oxy-fuel (HVOF) Cr{sub 3} C{sub 2} - 20% NiCr and WC - 12% Co cermets, low temperature arc vapor deposited (LTAVD) CrN and plasma sprayed chromium oxides. Also,plasma sprayed Cr{sub 2}O{sub 3} and A1{sub 2}O{sub 3}-ZrO{sub 2} materials were found to give excellent wear resistance in unlubricated tests and at extremely high temperatures (450{degrees}C) with a syntheticoil. All of these materials would offer substantial wear reductions compared to the conventional electroplated hard chromium ring facing and thermally sprayed metallic coatings, especially at high temperatures and with high-soot oils subjected to degradation in diesel environments. The LTAVD CrN coating provided the lowest lubricated wear rates of all the materials evaluated, but may be too thin (4 {mu}m) for use as a top ring facing. Most of the coatings evaluated showed higher wear rates with high-soot, engine-tested oil than with fresh oil, with increases of more than a factor of ten in some cases. Generally, metallic materials were found to be much more sensitive to soot/oil degradation than ceramic and cermet coatings. Thus, decreased ``soot sensitivity`` is a significant driving force for utilizing ceramic or cermet coatings in diesel engine wear applications.

  20. 硼化物陶瓷基涂层制备技术的研究进展%Research Progress of Preparation Technology on the Boride Ceramic-based Coating

    Institute of Scientific and Technical Information of China (English)

    贾成科; 张鑫; 任先京; 冀晓鹃; 彭浩然

    2012-01-01

    Boride cermet is a new cermet with many excellent properties such as high melting temperature, bulk hardness, high chemical stability, high wearable property, and good anti-causticity, which is used in the fields such as fire-resistant material, engineering cermet, nuclear industry, and space navigation. The same excellent properties of the boride ceramic based coating prepared by many kinds of techniques, which are play important roles in many fields such as ultra high-temperature components, high wearable property units,good anti-causticity parts, anti-liquid metal-causticity component, and neutron-ratiant guard etc. The preparation methods of the boride ceramic- based coating with the strongpoint and disadvantage are introduced. The advances and the application of boride ceramic- based coating, mostly including duality boride ceramic based coatings and ternary ones, are also summarized as well as the existing problems and the prospects are analyzed.%硼化物陶瓷是一种新型陶瓷材料,具有诸如高熔点、高硬度、高化学稳定性以及高耐磨、抗腐蚀性等优异的综合性能,在耐火材料、工程陶瓷、核工业、宇航等领域有着广泛应用,而通过多种工艺制备的硼化物陶瓷基涂层同样具有很好的性质和功能,这些优异的特性使得目前硼化物涂层在很多工程领域发挥着极其重要的作用,如超高温部件、高耐磨蚀性部件以及抗金属液腐蚀性的部件、中子辐射防护装置等。本文介绍了硼化物陶瓷基涂层的制备方法,指出了各种方法的优缺点,综述了硼化物陶瓷基涂层的研究进展及其涂层的应用情况,主要包括二元硼化物陶瓷基涂层、多元硼化物基金属涂层等,总结了目前该领域存在的问题,并对今后的发展前景进行了展望。

  1. Computer-Controlled Detonation Spraying: From Process Fundamentals Toward Advanced Applications

    Science.gov (United States)

    Ulianitsky, V.; Shtertser, A.; Zlobin, S.; Smurov, I.

    2011-06-01

    Detonation spraying is a well-known technology which is applied for deposition of diverse powders, in particular cermets, to form various protective coatings. Actual progress is related to a recently developed technique of computer-controlled detonation spraying and its application in non-traditional domains as development of composite and graded coatings or metallization of plastics. The gas detonation parameters are analyzed to estimate the efficiency of different fuels to vary particle-in-flight velocity and temperature over a broad range thus providing conditions to spray diverse powders. A particle of a given nature and fixed size could be sprayed in a solid state or being strongly overheated above the melting point by variation of the quantity of the explosive gas mixture which is computer-controlled. Particle-in-flight velocity and temperature are calculated and compared with jet monitoring by a CCD-camera-based diagnostic tool and experimental data on splats formation.

  2. Carbon deposition in CH4/CO2 operated SOFC: Simulation and experimentation studies

    Science.gov (United States)

    Girona, K.; Laurencin, J.; Fouletier, J.; Lefebvre-Joud, F.

    2012-07-01

    Due to their high operating temperatures, SOFCs can be directly fed with biogas, mainly composed of CH4 and CO2. In this work, experiments was performed with a classical Ni-YSZ cermet//YSZ//LSM cell fed either with a synthetic simulated biogas (CH4/CO2 ratio equal to 1 with 6% humidity), or with humidified H2. In both cases, the performances are found to be very similar, which confirms the ability of SOFCs to operate with internal reforming of biogas. Nevertheless, carbon formation in these operating conditions needs to be considered because of durability concerns. Thermodynamic calculations and modelling are carried out to evaluate the risk of carbon deposition depending on operating parameters. In the ternary diagram Csbnd Hsbnd O, the limits for carbon deposition are plotted, allowing the determination of “safe” operating conditions in terms of CH4 inlet flow rate and cell voltage. First experiments confirm these modelling results.

  3. Freeze-casting as a Novel Manufacturing Process for Fast Reactor Fuels. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Wegst, Ulrike G.K. [Dartmouth College, Hanover, NH (United States). Thayer School of Engineering; Allen, Todd [Idaho National Lab. (INL), Idaho Falls, ID (United States); Univ. of Wisconsin, Madison, WI (United States); Sridharan, Kumar [Idaho National Lab. (INL), Idaho Falls, ID (United States); Univ. of Wisconsin, Madison, WI (United States)

    2014-04-07

    Advanced burner reactors are designed to reduce the amount of long-lived radioactive isotopes that need to be disposed of as waste. The input feedstock for creating advanced fuel forms comes from either recycle of used light water reactor fuel or recycle of fuel from a fast burner reactor. Fuel for burner reactors requires novel fuel types based on new materials and designs that can achieve higher performance requirements (higher burn up, higher power, and greater margins to fuel melting) then yet achieved. One promising strategy to improved fuel performance is the manufacture of metal or ceramic scaffolds which are designed to allow for a well-defined placement of the fuel into the host, and this in a manner that permits greater control than that possible in the production of typical CERMET fuels.

  4. Experimental investigation of cutting tool performance in high speed cutting of hardened X210 Cr12 cold-work tool steel (62 HRC)

    International Nuclear Information System (INIS)

    This study explored the performance and wear behaviour of different cutting tools in end milling of X210 Cr12 cold-work tool steel hardened to 62 HRC. The purpose of the experiments reported in this paper is to investigate the wear of TiCN coated tungsten carbide, TiCN + TiAlN coated tungsten carbide, TiAlN coated cermet, mixed ceramic with Al2O3 + TiCN and cubic boron nitride (CBN) tools. Tool performance evaluation was based on the surface finish and tool flank wear. Tool flank wear was studied carefully through JSM 5600 (30 kW) scanning electron microscope. Surface roughness values were measured by Mitutoyo Metusurf 310 equipment. CBN tool exhibited the best cutting performance in terms of both flank wear and surface finish. The highest volume of metal removal was obtained with CBN tool

  5. Method of producing homogeneous mixed metal oxides and metal-metal oxide mixtures

    International Nuclear Information System (INIS)

    A method for preparing particulate metal or metal oxide of controlled partile size comprises contacting an an aqueous solution containing dissolved metal values with excess urea at a temperature sufficient to cause urea to react with water to provide a molten urea solution containing the metal values; heating the molten urea solution to cause the metal values to precipitate, forming a mixture containing precipitated metal values; heating the mixture containing precipitated metal values to evaporate volatile material leaving a dry powder containing said metal values. The dry powder can be calcined to provide particulate metal oxide or reduced to provide particulate metal. Oxide mixtures are provided when the aqueous solution contains values of more than one metal. Homogeneousmetal-metal oxide mistures for preparing cermets can be prepared by selectively reducing at least one of the metal oxides. (auth)

  6. System and safety studies of accelerator driven systems for transmutation. Annual report 2007

    Energy Technology Data Exchange (ETDEWEB)

    Arzhanov, Vasily; Fokau, Andrei; Persson, Calle; Runevall, Odd; Sandberg, Nils; Tesinsky, Milan; Wallenius, Janne; Youpeng Zhang (Div. of Reactor Physics, Royal Institute of Technology, Stockholm (Sweden))

    2008-05-15

    Within the project 'System and safety studies of accelerator driven systems for transmutation', research on design and safety of sub-critical reactors for recycling of minor actinides is performed. During 2007, the reactor physics division at KTH has calculated safety parameters for EFIT-400 with cermet fuel, permitting to start the transient safety analysis. The accuracy of different reactivity meters applied to the YALINA facility was assessed and neutron detection studies were performed. A model to address deviations from point kinetic behaviour was developed. Studies of basic radiation damage physics included calculations of vacancy formation and activation enthalpies in bcc niobium. In order to predict the oxygen potential of inert matrix fuels, a thermo-chemical model for mixed actinide oxides was implemented in a phase equilibrium code

  7. Synthesis of complex carbonitride powders Ti{sub y}M{sub T1-y}C{sub x}N{sub 1-x} (M{sub T}: Zr, V, Ta, Hf) via a mechanically induced self-sustaining reaction

    Energy Technology Data Exchange (ETDEWEB)

    Cordoba, Jose M., E-mail: jmcordoba@icmse.csic.e [Instituto de Ciencia de Materiales de Sevilla, Centro Mixto CSIC-US, Americo Vespucio 49, 41092 Sevilla (Spain); Aviles, Miguel A.; Sayagues, Maria J.; Alcala, Maria D.; Gotor, Francisco J. [Instituto de Ciencia de Materiales de Sevilla, Centro Mixto CSIC-US, Americo Vespucio 49, 41092 Sevilla (Spain)

    2009-08-12

    The machinability of materials is a dynamic field with enormous implications in different industrial sectors because manufacturers are constantly looking for improvements that can increase the overall productivity. Manufacturers of cutting tool inserts need to develop products that can perform at higher speeds and last longer under increasingly rigorous operating conditions. It has been revealed that cermets may exhibit better properties and performances when solid solution of multiple hard compounds is added instead of a mixture of several binary ones. In this work, a mechanically induced self-sustaining reaction (MSR) is described as a suitable synthesis method to obtain a wide range of different new quaternary carbonitride systems by milling mixtures of elemental powders of transition metals and graphite in a nitrogen atmosphere. Characterization was carried out using X-ray powder diffraction, elemental analysis, energy dispersive X-ray analysis (EDX), scanning and transmission electron microscopy and electron diffraction (ED).

  8. Carbon Deposition during CO2 Electrolysis in Ni-Based Solid-Oxide-Cell Electrodes

    DEFF Research Database (Denmark)

    Skafte, Theis Løye; Graves, Christopher R.; Blennow, P.;

    2015-01-01

    -stabilized zirconia (Ni-YSZ) cermets were supplied by Haldor Topsoe A/S and the operating conditions were chosen so as to take stack relevant considerations into account. Formation of carbon nanotubes in Ni containing fuel electrodes has previously been observed in co-electrolysis of H2O and CO2 [1]. Hence......, the carbon formation threshold in an operating cell was investigated during electrolysis of an idealized reactant atmosphere of CO and CO2. The electrolysis current was gradually increased in steps until the cell voltage spontaneously increased, thereby indicating cell degradation and possibly the onset...... of carbon deposition. The outlet gas composition at each current step was estimated based on the inlet gas composition and the reactant conversion using Faraday's law. The increase in voltage was observed at lower pCO/pCO2 ratios than that corresponding to the thermodynamic threshold for carbon formation...

  9. Correlation between discharging property and coatings microstructure during plasma electrolytic oxidation

    Institute of Scientific and Technical Information of China (English)

    GUAN Yong-jun; XIA Yuan

    2006-01-01

    The voltage-current properties during plasma electrolytic discharge were determined by measuring the current density and cell voltage as functions of processing time and then by mathematical transformation. Correlation between discharge I-V property and the coatings microstructure on aluminum alloy during plasma electrolytic oxidation was determined by comparing the voltage-current properties at different process stages with SEM results of the corresponding coatings. The results show that the uniform passive film corresponds to a I-V property with one critical voltage, and a compound of porous layer and sintered ceramic particles corresponds to a I-V property with two critical voltages. The growth regularity of PEO cermet coatings was also studied.

  10. Quantitative characterization of the microstructure and properties of nanocrystalline WC–Co bulk

    International Nuclear Information System (INIS)

    Graphical abstract: Microstructure of the nanocrystalline WC–Co cermet bulk was quantitatively described by transmission electron microscopy based precession electron diffraction technology. It is discovered that the fraction of the Σ2 grain boundaries increases with the decrease of WC grain size. The effect of microstructure on mechanical properties depends on Co distribution, Σ2 boundaries fraction and WC grain contiguity. -- Nanocrystalline WC–Co bulk was prepared using a novel route that combined in situ reactions and subsequent spark plasma sintering. The microstructure was characterized by transmission electron microscopy-based precession electron diffraction technology. The nanocrystalline microstructure has a high WC grain contiguity. The fraction of Σ2 boundaries increases with a decrease in WC grain size. The effect of microstructure on the mechanical properties was analyzed in terms of the correlations between Co distribution, Σ2 boundary fraction and WC grain contiguity.

  11. 渗硼

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    [ 篇名 ]A method of making boride and vitreous compound by powder metallurgy,[ 篇名 ] Ceramic-metal composites obtained by reactive prcssurclcss countcrflow inlitration/pcnctration (RPCI) of a ceramic substrate with two different metallic infiltrants,[篇名] Characterization of Directionally Solidified B{sub}4C-TiB{sub)2 and B{sub)4C-SiC Eutectic Composites Prepared by Floating-Zone Method,[篇名] Corrosion resistance of an iron base boridc cermets with oxide surface layers n a molten al alloy,[ 篇名 ] Crack propagation characteristics and fracture surface energy of boride conners,[篇名] Deposition of hard and/or corrosion resistant, single and multielement coatings on ferrous and nonferrous alloys in fluidized bed reactor,[ 篇名] Deposition of protective coatings on tungstenfree hard alloys。

  12. Optical materials technology for energy efficiency and solar energy conversion VIII; Proceedings of the Meeting, San Diego, CA, Aug. 10, 11, 1989

    Science.gov (United States)

    Granqvist, Claes G.; Lampert, Carl M.

    1989-12-01

    The preparation, properties, and applications of advanced optical materials are discussed in reviews and reports. Sections are devoted to optical switching materials, wavelength-selective surfaces, photovoltaic technology, and solar optical materials. Particular attention is given to the IR properties of electrochromic (EC) materials, the anomalous EC behavior of Ag-WO3 and Au-WO3 cermets, EC WO3 films prepared at room temperature by chemical deposition, the multilayered structure of silicon oxynitrides and oxides for radiative cooling, and light trapping in solar cells and the determination of the absorbed energy by calorimetry. Also considered are hydrogenated a-Si/Ge films prepared by reactive sputtering, electrodeposition of CdTe thin films, a PC-based test system for on-line characterization of solar cells and modules, chromatic-dispersion compensation in a Fresnel lens using a diffraction grating, stretched-membrane heliostats for solar central-receiver power plants, and angular-selective window coatings.

  13. Optical materials technology for energy efficiency and solar energy conversion VIII; Proceedings of the Meeting, San Diego, CA, Aug. 10, 11, 1989

    Energy Technology Data Exchange (ETDEWEB)

    Granqvist, C.G.; Lampert, C.M.

    1989-01-01

    The preparation, properties, and applications of advanced optical materials are discussed in reviews and reports. Sections are devoted to optical switching materials, wavelength-selective surfaces, photovoltaic technology, and solar optical materials. Particular attention is given to the IR properties of electrochromic (EC) materials, the anomalous EC behavior of Ag-WO3 and Au-WO3 cermets, EC WO3 films prepared at room temperature by chemical deposition, the multilayered structure of silicon oxynitrides and oxides for radiative cooling, and light trapping in solar cells and the determination of the absorbed energy by calorimetry. Also considered are hydrogenated a-Si/Ge films prepared by reactive sputtering, electrodeposition of CdTe thin films, a PC-based test system for on-line characterization of solar cells and modules, chromatic-dispersion compensation in a Fresnel lens using a diffraction grating, stretched-membrane heliostats for solar central-receiver power plants, and angular-selective window coatings.

  14. Absence of Dopant Segregation to the Surface of Scandia and Yttria Co-Stabilized Zirconia

    DEFF Research Database (Denmark)

    Vels Hansen, Karin; Mogensen, Mogens Bjerg

    2012-01-01

    The surface composition of sintered scandia and yttria co-stabilized zirconia was analyzed with x-ray photoelectron spectroscopy. The samples were sintered at 1300°C or 1500°C in flowing dry or moisturized air. It was found that Sc2O3 does not segregate to the surface, unlike the Y2O3 in yttria...... stabilized zirconia. The probable reason for this is that due to its size the Sc3+ ion fits better in the zirconia lattice than Y3+ does. The difference in surface composition may be the explanation for the observed increased tolerance toward sulfur of Ni-ScYSZ compared to Ni-YSZ cermets....

  15. Physical chemistry of WC-12 %Co coatings deposited by thermal spraying at different standoff distances

    Energy Technology Data Exchange (ETDEWEB)

    Afzal, Muhammad; Ahmed, Furqan; Anwar, Muhammad Yousaf; Ali, Liaqat; Ajmal, Muhammad [Univ. of Engineering and Technology, Metallurgical and Materials Engineering, Lahore (Pakistan); Khan, Aamer Nusair [Institute of Industrial and Control System, Rawalpindi (Pakistan)

    2015-09-15

    In the present research, WC-12 %Co cermet coatings were deposited on AISI-321 stainless steel substrate using air plasma spraying. During the deposition process, the standoff distance was varied from 80 to 130 mm with 10 mm increments. Other parameters such as current, voltage, time, carrier gas flow rate and powder feed rate etc. were kept constant. The objective was to study the effects of spraying distance on the microstructure of as-sprayed coatings. The microscopic analyses revealed that the band of spraying distance ranging from 90 to 100 mm was the threshold distance for optimum results, provided that all the other spraying parameters were kept constant. In this range of threshold distance, minimum percentages of porosity and defects were observed. Further, the formation of different phases, at six spraying distances, was studied using X-ray diffraction, and the phase analysis was correlated with hardness results.

  16. Performance Factors and Sulfur Tolerance of Metal Supported Solid Oxide Fuel Cells with Nanostructured Ni:GDC Infiltrated Anodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Sudireddy, Bhaskar Reddy; Hagen, Anke;

    2016-01-01

    Two metal supported solid oxide fuel cells (active area 16 cm2) with nanostructured Ni:GDC infiltrated anodes, possessing different anode and support microstructures were studied in respect to sulfur tolerance at an operating temperature of 650°C. The studied MS-SOFCs are based on ferretic...... stainless steel (FeCr) and showed excellent performance characteristics at 650°C with fuel utilization corrected area specific resistances of 0.35 Ωcm2 and 0.7 Ωcm2 respectively. The sulfur tolerance testing was performed by periodic addition of 2, 5, and 10 ppm H2S in hydrogen based fuel under...... galvanostatic operation at a current load of 0.25 Acm−2. The results were compared with literature on the sulfur tolerance of conventional SOFC Ni/YSZ cermet anode. The comparison in terms of absolute cell resistance increase and relative anode polarization resistance increase indicates, that the nanostructured...

  17. Performance of a novel type of electrolyte-supported solid oxide fuel cell with honeycomb structure

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Morales, Juan Carlos; Savvin, Stanislav N.; Nunez, Pedro [Departmento de Quimica Inorganica, Universidad de La Laguna, 38200 Tenerife (Spain); Marrero-Lopez, David [Departamento de Fisica Aplicada I, Universidad de Malaga, 29071 Malaga (Spain); Pena-Martinez, Juan; Canales-Vazquez, Jesus [Instituto de Energias Renovables-Universidad de Castilla la Mancha, 02006 Albacete (Spain); Roa, Joan Josep; Segarra, Merce [DIOPMA, Departamento de Ciencia de los Materiales e Ing. Metalurgica, 08028 Barcelona (Spain)

    2010-01-15

    A novel design, alternative to the conventional electrolyte-supported solid oxide fuel cell (SOFC) is presented. In this new design, a honeycomb-electrolyte is fabricated from hexagonal cells, providing high mechanical strength to the whole structure and supporting the thin layer used as electrolyte of a SOFC. This new design allows a reduction of {proportional_to}70% of the electrolyte material and it renders modest performances over 320 mW cm{sup -2} but high volumetric power densities, i.e. 1.22 W cm{sup -3} under pure CH{sub 4} at 900 C, with a high OCV of 1.13 V, using the standard Ni-YSZ cermet as anode, Pt as cathode material and air as the oxidant gas. (author)

  18. Development and optimisation of electrodematerials in solid oxide fuel cells

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Solid oxide fuel cell (SOFC) is an all solid electrochemical device to convert fuels such as hydrogen and natural gas to electricity with high efficiency and very low greenhouse gas emission compared to traditional thermal power generation plants. Moreover, the reliability and efficiency of SOFC is critically dependent on the performance and stability of its components including anode, cathode and electrolyte. This in turn is largely dependent on the material selection and the fabrication processes. In this paper, specific examples are given to demonstrate strategy and process in the development and optimisation of electrode materials such as Ni/Y2O3-ZrO2 cermet anodes and (LaSr)MnO3 based cathodes. The results also demonstrate the importance of fabrication processes and that the understanding of the electrode process plays a very important role in the optimisation process of electrode materials.

  19. Redox Stable Anodes for Solid Oxide Fuel Cells

    Directory of Open Access Journals (Sweden)

    Guoliang eXiao

    2014-06-01

    Full Text Available Solid oxide fuel cells (SOFCs can convert chemical energy from the fuel directly to electrical energy with high efficiency and fuel flexibility. Ni-based cermets have been the most widely adopted anode for SOFCs. However, the conventional Ni-based anode has low tolerance to sulfur-contamination, is vulnerable to deactivation by carbon build-up (coking from direct oxidation of hydrocarbon fuels, and suffers volume instability upon redox cycling. Among these limitations, the redox instability of the anode is particularly important and has been intensively studied since the SOFC anode may experience redox cycling during fuel cell operations even with the ideal pure hydrogen as the fuel. This review aims to highlight recent progresses on improving redox stability of the conventional Ni-based anode through microstructure optimization and exploration of alternative ceramic-based anode materials.

  20. Degradation behavior of anode-supported solid oxide fuel cell using LNF cathode as function of current load

    Energy Technology Data Exchange (ETDEWEB)

    Komatsu, Takeshi; Yoshida, Yoshiteru; Watanabe, Kimitaka; Chiba, Reiichi; Taguchi, Hiroaki; Orui, Himeko; Arai, Hajime [NTT Energy and Environment Systems Laboratories, Atsugi-shi, Kanagawa 243-0198 (Japan)

    2010-09-01

    We investigated the effect of current loading on the degradation behavior of an anode-supported solid oxide fuel cell (SOFC). The cell consisted of LaNi{sub 0.6}Fe{sub 0.4}O{sub 3} (LNF), alumina-doped scandia stabilized zirconia (SASZ), and a Ni-SASZ cermet as the cathode, electrolyte, and anode, respectively. The test was carried out at 1073 K with constant loads of 0.3, 1.0, 1.5, and 2.3 A cm{sup -2}. The degradation rate, defined by the voltage loss during a fixed period (about 1000 h), was faster at higher current densities. From an impedance analysis, the degradation depended mainly on increases in the cathodic resistance, while the anodic and ohmic resistances contributed very little. The cathode microstructures were observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). (author)

  1. Multi-metallic anodes for solid oxide fuel cell applications; Anodos multi-metalicos para aplicacoes em celulas a combustivel de oxido solido

    Energy Technology Data Exchange (ETDEWEB)

    Restivo, T.A. Guisard; Mello-Castanho, S.R.H. [Instituto de Pesquisas Energeticas e Nucleares (CCTM/IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia dos Materiais; Leite, D. Will [Instituto de Pesquisas e Estudos Industriais (IPEI/FEI), Sao Bernardo do Campo, SP (Brazil). Fac. de Engenharia Industrial

    2009-07-01

    A new method for direct preparation of materials for solid oxide fuel cell anode - Ni- YSZ cermets - based on mechanical alloying (MA) of the original powders is developed, allowing to admix homogeneously any component. Additive metals are selected from thermodynamic criteria, leading to compacts consolidation through sintering by activated surface (SAS). The combined process MA-SSA can reduce the sintering temperature by 300 deg C, yielding porous anodes. Densification mechanisms are discussed from quasi-isothermal sintering kinetics results. Doping with Ag, W, Cu, Mo, Nb, Ta, in descending order, promotes the densification of pellets through liquid phase sintering and evaporation of metals and oxides, which allow reducing the sintering temperature. Powders and pellets characterization by electronic microscopy and X-ray diffraction completes the result analyses. (author)

  2. Physical chemistry of WC-12 %Co coatings deposited by thermal spraying at different standoff distances

    International Nuclear Information System (INIS)

    In the present research, WC-12 %Co cermet coatings were deposited on AISI-321 stainless steel substrate using air plasma spraying. During the deposition process, the standoff distance was varied from 80 to 130 mm with 10 mm increments. Other parameters such as current, voltage, time, carrier gas flow rate and powder feed rate etc. were kept constant. The objective was to study the effects of spraying distance on the microstructure of as-sprayed coatings. The microscopic analyses revealed that the band of spraying distance ranging from 90 to 100 mm was the threshold distance for optimum results, provided that all the other spraying parameters were kept constant. In this range of threshold distance, minimum percentages of porosity and defects were observed. Further, the formation of different phases, at six spraying distances, was studied using X-ray diffraction, and the phase analysis was correlated with hardness results.

  3. Performance and life-time behaviour of NiCu-CGO anodes for the direct electro-oxidation of methane in IT-SOFCs

    Science.gov (United States)

    Sin, A.; Kopnin, E.; Dubitsky, Y.; Zaopo, A.; Aricò, A. S.; La Rosa, D.; Gullo, L. R.; Antonucci, V.

    An anodic cermet of NiCu alloy and gadolinia doped ceria has been investigated for CH 4 electro-oxidation in IT-SOFCs. Polarization curves have been recorded in the temperature range from 650 to 800 °C. A maximum power density of 320 mW cm -2 at 800 °C has been obtained in the presence of dry methane in an electrolyte-supported cell. The electrochemical behaviour during 1300 h operation in dry methane and in the presence of redox-cycles has been investigated at 750 °C; variation of the electrochemical properties during these experiments have been interpreted in terms of anode morphology modifications. The methane cracking process at the anode catalyst has been investigated by analysing the oxidative stripping of deposited carbon species.

  4. Performance and life-time behaviour of NiCu-CGO anodes for the direct electro-oxidation of methane in IT-SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Sin, A.; Kopnin, E.; Dubitsky, Y.; Zaopo, A. [Pirelli Labs S.p.A., Viale Sarca 222, I-20126 Milan (Italy); Arico, A.S.; La Rosa, D.; Gullo, L.R.; Antonucci, V. [CNR-ITAE, Via Salita Santa Lucia Sopra Contesse 5, I-98125 Messina (Italy)

    2007-01-10

    An anodic cermet of NiCu alloy and gadolinia doped ceria has been investigated for CH{sub 4} electro-oxidation in IT-SOFCs. Polarization curves have been recorded in the temperature range from 650 to 800{sup o}C. A maximum power density of 320mWcm{sup -2} at 800{sup o}C has been obtained in the presence of dry methane in an electrolyte-supported cell. The electrochemical behaviour during 1300h operation in dry methane and in the presence of redox-cycles has been investigated at 750{sup o}C; variation of the electrochemical properties during these experiments have been interpreted in terms of anode morphology modifications. The methane cracking process at the anode catalyst has been investigated by analysing the oxidative stripping of deposited carbon species. (author)

  5. Laser ablation synthesis of C-Si-H-doped Co1-xO with novel (hkl)-specific paracrystal, Co interlayer and lattice shuffling

    Science.gov (United States)

    Hsu, Shang-Ju; Lin, Shih-Siang; Zheng, Yuyuan; Shen, Pouyan; Chen, Shuei-Yuan

    2016-04-01

    C-Si-H-doped Co1-xO particulates/nanocondensates of rocksalt-derived types were formed by pulsed laser ablation of metallic Co plate in tetraethyl orthosilicate and characterized by X-ray/electron diffraction and vibrational/optical spectroscopy. Such crystals were found to contain (001) paracrystal plate having defect cluster periodicity ca. 2.5 times that of the host lattice, and 1D 3x and 5x{111} commensurate superstructures along with (111) (Co/CoO) n multilayer. The (Co/CoO) n multilayer by (111)-specific faulting and oxygen diffusion is of interest to the synthesis of cermet, in particular giant magnetoresistance material, whereas the overall substances with characteristic vibration modes, binding energy and UV-visible absorptions (3.1 and 3.7 eV) may have potential optocatalytic applications.

  6. Estimation of terrorist attack resistibility of dual-purpose cask TP-117 with DU (depleted uranium) gamma shield

    Energy Technology Data Exchange (ETDEWEB)

    Alekseev, O.G.; Matveev, V.Z.; Morenko, A.I.; Il' kaev, R.I.; Shapovalov, V.I. [Russian Federal Nuclear Center - All-Russian Research Inst. of Experimental Physics, Sarov (Russian Federation)

    2004-07-01

    Report is devoted to numerical research of dual-purpose unified cask (used for SFA transportation and storage) resistance to terrorist attacks. High resistance of dual-purpose unified cask has been achieved due to the unique design-technological solutions and implementation of depleted uranium in cask construction. In suggested variant of construction depleted uranium fulfils functions of shielding and constructional material. It is used both in metallic and cermet form (basing on steel and depleted uranium dioxide). Implementation of depleted uranium in cask construction allows maximal load in existing overall dimensions of the cask. At the same time: 1) all safety requirements (IAEA) are met, 2) dual-purpose cask with SFA has high resistance to terrorist attacks.

  7. Solid Oxide Fuel Cells: Technology Status

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Prabhakar; Minh, Nguyen Q.

    2004-08-01

    In its most common configuration, solid oxide fuel cell (SOFC) uses an oxygen ion conducting ceramic electrolyte membrane, perovskite cathode and nickel cermet anode electrode. Cells operate in the 600-1000 C temperature range and utilize metallic or ceramic current collectors for cell-to-cell interconnection. Recent development in engineered electrode architectures, component materials chemistry, cell and stack designs and fabrication processes have led to significant improvement in the electrical performance and performance stability as well as reduction in the operating temperature of such cells. Large kW-size power generation systems have been designed and field demonstrated. This paper reviews the status of SOFC power generation systems with emphasis on cell and stack component materials, electrode reactions, materials reactions and corrosion processes

  8. Stabilization of green bodies via sacrificial gelling agent during electrophoretic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Worsley, Marcus A.; Kuntz, Joshua D.; Rose, Klint A.

    2016-03-22

    In one embodiment, a method for electrophoretic deposition of a three-dimensionally patterned green body includes suspending a first material in a gelling agent above a patterned electrode of an electrophoretic deposition (EPD) chamber, and gelling the suspension while applying a first electric field to the suspension to cause desired patterning of the first material in a resulting gelation. In another embodiment, a ceramic, metal, or cermet includes a plurality of layers, wherein each layer includes a gradient in composition, microstructure, and/or density in an x-y plane oriented parallel to a plane of deposition of the plurality of layers along a predetermined distance in a z-direction perpendicular to the plane of deposition.

  9. Estimation of terrorist attack resistibility of dual-purpose cask TP-117 with DU (depleted uranium) gamma shield

    International Nuclear Information System (INIS)

    Report is devoted to numerical research of dual-purpose unified cask (used for SFA transportation and storage) resistance to terrorist attacks. High resistance of dual-purpose unified cask has been achieved due to the unique design-technological solutions and implementation of depleted uranium in cask construction. In suggested variant of construction depleted uranium fulfils functions of shielding and constructional material. It is used both in metallic and cermet form (basing on steel and depleted uranium dioxide). Implementation of depleted uranium in cask construction allows maximal load in existing overall dimensions of the cask. At the same time: 1) all safety requirements (IAEA) are met, 2) dual-purpose cask with SFA has high resistance to terrorist attacks

  10. Revised Point of Departure Design Options for Nuclear Thermal Propulsion

    Science.gov (United States)

    Fittje, James E.; Borowski, Stanley K.; Schnitzler, Bruce

    2015-01-01

    In an effort to further refine potential point of departure nuclear thermal rocket engine designs, four proposed engine designs representing two thrust classes and utilizing two different fuel matrix types are designed and analyzed from both a neutronics and thermodynamic cycle perspective. Two of these nuclear rocket engine designs employ a tungsten and uranium dioxide cermet (ceramic-metal) fuel with a prismatic geometry based on the ANL-200 and the GE-710, while the other two designs utilize uranium-zirconium-carbide in a graphite composite fuel and a prismatic fuel element geometry developed during the Rover/NERVA Programs. Two engines are analyzed for each fuel type, a small criticality limited design and a 111 kN (25 klbf) thrust class engine design, which has been the focus of numerous manned mission studies, including NASA's Design Reference Architecture 5.0. slightly higher T/W ratios, but they required substantially more 235U.

  11. Determination of the percolation threshold in Fe/MgO magnetic granular multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-GarcIa, A; Algarabel, P A; De Teresa, J M; Morellon, L; Ibarra, M R [Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC, 50009-Zaragoza (Spain); Vovk, A; Strichovanec, P; Pardo, J A; Magen, C, E-mail: vovk@imag.kiev.u [Instituto de Nanociencia de Aragon, Universidad de Zaragoza, 50018-Zaragoza (Spain)

    2010-02-10

    The evolution of the morphology, magnetic and transport properties of Fe(t nm)/MgO(3.0 nm) multilayers with respect to the nominal metallic layer thickness was investigated. A comparison with existing experimental data on discontinuous metal-insulator multilayers, ultrathin epitaxial Fe films on MgO substrates and granular cermet films is made. It is confirmed that the deposition conditions and the material composition play a crucial role in the percolation process. Nominal thicknesses of Fe layers at which an infinite metallic cluster is formed and the conditions for continuous Fe coverage were determined. Different methods of percolation threshold detection were analysed. We show that investigation of the temperature dependence of resistance in nanostructures could lead to an overestimation of the percolation threshold value, while magnetic measurements alone could lead to its underestimation.

  12. Morphology, magnetic and resonance properties of Fe/MgO multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Garcia, A; Algarabel, P A; Ibarra, M R [Instituto de Ciencia de Materiales de Aragon, Universidad de Zaragoza-CSIC 50009 Zaragoza (Spain); Vovk, A [Centro de Fisica da Materia Condensada Unversidade de Lisboa, Campo Grande Ed. C8, 1749-016, Lisboa (Portugal); Strichovanec, P; Pardo, J A; Magen, C [Instituto de Nanociencia de Aragon, Universidad de Zaragoza 50018 Zaragoza (Spain); Golub, V; Salyuk, O, E-mail: ayvovk@fc.ul.pt [Institute of Magnetism NAS of Ukraine, 36-b Vernnadsky blvd., 03142, Kyiv (Ukraine)

    2011-07-06

    Magnetic, resonance and transport properties of Fe(t nm)/MgO(3.0 nm) multilayers prepared by pulsed laser deposition were investigated. Comparison of the data allows conclusions on Fe layers morphology. For t<0.61 nm typical features of granular cermet films in dielectric regime are observed, i.e. high electrical resistance, isotropic magnetoresistance and strong temperature dependence of magnetization. For higher t coalescence of Fe granules occurs and metallic percolation cluster is formed at t{approx}0.81 nm. This is manifested by rapid decrease of films resistance and formation of multipeak ferromagnetic resonance spectra. For t>1.25 nm a continuous coverage of MgO by Fe takes place. However, the morphology of Fe layers is rough. This causes the appearance of magnetostatic resonance modes analogous to those observed for continuous films deposited on embossed surfaces.

  13. The Nuclear Cryogenic Propulsion Stage

    Science.gov (United States)

    Houts, Michael G.; Kim, Tony; Emrich, William J.; Hickman, Robert R.; Broadway, Jeramie W.; Gerrish, Harold P.; Belvin, Anthony D.; Borowski, Stanley K.; Scott, John H.

    2014-01-01

    Nuclear Thermal Propulsion (NTP) development efforts in the United States have demonstrated the technical viability and performance potential of NTP systems. For example, Project Rover (1955 - 1973) completed 22 high power rocket reactor tests. Peak performances included operating at an average hydrogen exhaust temperature of 2550 K and a peak fuel power density of 5200 MW/m3 (Pewee test), operating at a thrust of 930 kN (Phoebus-2A test), and operating for 62.7 minutes in a single burn (NRX-A6 test). Results from Project Rover indicated that an NTP system with a high thrust-to-weight ratio and a specific impulse greater than 900 s would be feasible. Excellent results were also obtained by the former Soviet Union. Although historical programs had promising results, many factors would affect the development of a 21st century nuclear thermal rocket (NTR). Test facilities built in the US during Project Rover no longer exist. However, advances in analytical techniques, the ability to utilize or adapt existing facilities and infrastructure, and the ability to develop a limited number of new test facilities may enable affordable development, qualification, and utilization of a Nuclear Cryogenic Propulsion Stage (NCPS). Bead-loaded graphite fuel was utilized throughout the Rover/NERVA program, and coated graphite composite fuel (tested in the Nuclear Furnace) and cermet fuel both show potential for even higher performance than that demonstrated in the Rover/NERVA engine tests.. NASA's NCPS project was initiated in October, 2011, with the goal of assessing the affordability and viability of an NCPS. FY 2014 activities are focused on fabrication and test (non-nuclear) of both coated graphite composite fuel elements and cermet fuel elements. Additional activities include developing a pre-conceptual design of the NCPS stage and evaluating affordable strategies for NCPS development, qualification, and utilization. NCPS stage designs are focused on supporting human Mars

  14. Microstructural degradation of Ni-YSZ anodes for solid oxide fuel cells

    DEFF Research Database (Denmark)

    Thydén, Karl Tor Sune

    2008-01-01

    are of technological relevance, it is difficult to identify the effect from isolated parameters such as temperature, fuel gas composition and polarization. Model studies of high temperature aged Ni-YSZ cermets are generally performed in atmospheres containing relatively low concentrations of H2O. In this work......, the microstructural degradation in both electrochemically longterm tested cells and high-temperature aged model materials are studied. Since Ni particle sintering / coarsening is attributed to be the major cause of anode degradation, this subject attains the primary focus. A large part of the work is focused......-reforming catalysis. In the context of electrochemically tested and technologically relevant cells, the majority of the microstructural work is performed on a cell tested at 850°C under relatively severe conditions for 17,500 hours. It is demonstrated that the major Ni rearrangements take place at the interface...

  15. High Temperature Electrolysis

    DEFF Research Database (Denmark)

    Elder, Rachael; Cumming, Denis; Mogensen, Mogens Bjerg

    2015-01-01

    High temperature electrolysis of carbon dioxide, or co-electrolysis of carbon dioxide and steam, has a great potential for carbon dioxide utilisation. A solid oxide electrolysis cell (SOEC), operating between 500 and 900. °C, is used to reduce carbon dioxide to carbon monoxide. If steam is also...... electrolyte, commonly yttria-stabilised-zirconia (YSZ), with porous fuel and oxygen side electrodes. The electrodes must be both electron and oxide ion conducting, and maximising the active surface area is essential for efficient operation. For the fuel electrode a cermet of nickel and YSZ is often used......, whereas a lanthanum strontium manganite - YSZ mix is utilised for the oxygen electrode. Long term durability and performance are key for commercialisation of SOEC technology. To date, experimental tests of 1000. h on electrolysis stacks operated at low current density have shown little or no degradation...

  16. Joining of dissimilar materials

    Science.gov (United States)

    Tucker, Michael C; Lau, Grace Y; Jacobson, Craig P

    2012-10-16

    A method of joining dissimilar materials having different ductility, involves two principal steps: Decoration of the more ductile material's surface with particles of a less ductile material to produce a composite; and, sinter-bonding the composite produced to a joining member of a less ductile material. The joining method is suitable for joining dissimilar materials that are chemically inert towards each other (e.g., metal and ceramic), while resulting in a strong bond with a sharp interface between the two materials. The joining materials may differ greatly in form or particle size. The method is applicable to various types of materials including ceramic, metal, glass, glass-ceramic, polymer, cermet, semiconductor, etc., and the materials can be in various geometrical forms, such as powders, fibers, or bulk bodies (foil, wire, plate, etc.). Composites and devices with a decorated/sintered interface are also provided.

  17. Freeze-casting as a Novel Manufacturing Process for Fast Reactor Fuels. Final Report

    International Nuclear Information System (INIS)

    Advanced burner reactors are designed to reduce the amount of long-lived radioactive isotopes that need to be disposed of as waste. The input feedstock for creating advanced fuel forms comes from either recycle of used light water reactor fuel or recycle of fuel from a fast burner reactor. Fuel for burner reactors requires novel fuel types based on new materials and designs that can achieve higher performance requirements (higher burn up, higher power, and greater margins to fuel melting) then yet achieved. One promising strategy to improved fuel performance is the manufacture of metal or ceramic scaffolds which are designed to allow for a well-defined placement of the fuel into the host, and this in a manner that permits greater control than that possible in the production of typical CERMET fuels.

  18. Multi-metallic anodes for solid oxide fuel cell applications

    International Nuclear Information System (INIS)

    A new method for direct preparation of materials for solid oxide fuel cell anode - Ni- YSZ cermets - based on mechanical alloying (MA) of the original powders is developed, allowing to admix homogeneously any component. Additive metals are selected from thermodynamic criteria, leading to compacts consolidation through sintering by activated surface (SAS). The combined process MA-SSA can reduce the sintering temperature by 300 deg C, yielding porous anodes. Densification mechanisms are discussed from quasi-isothermal sintering kinetics results. Doping with Ag, W, Cu, Mo, Nb, Ta, in descending order, promotes the densification of pellets through liquid phase sintering and evaporation of metals and oxides, which allow reducing the sintering temperature. Powders and pellets characterization by electronic microscopy and X-ray diffraction completes the result analyses. (author)

  19. Mechanical properties testing and results for thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Cruse, T.A.; Johnsen, B.P.; Nagy, A.

    1995-10-01

    The paper reports on several years of mechanical testing of thermal barrier coatings. The test results were generated to support the development of durability models for the coatings in heat engine applications. The test data that are reviewed include modulus, static strength, and fatigue strength data. The test methods and results are discussed, along with the significant difficulties inherent in mechanical testing of thermal barrier coating materials. The materials include 7 percent wt. and 8 percent wt. yttria, partially stabilized zirconia as well as a cermet material. Both low pressure plasma spray and electron-beam physical vapor deposited coatings were tested. The data indicate the basic trends in the mechanical properties of the coatings over a wide range of isothermal conditions. Some of the trends are correlated with material density.

  20. Mechanical properties testing and results for thermal barrier coatings

    Science.gov (United States)

    Cruse, Thomas A.; Johnsen, B. P.; Nagy, Andrew

    1995-01-01

    The paper reports on several years of mechanical testing of thermal barrier coatings. The test results were generated to support the development of durability models for the coatings in heat engine applications. The test data that are reviewed include modulus, static strength, and fatigue strength data. The test methods and results are discussed, along with the significant difficulties inherent in mechanical testing of thermal barrier coating materials. The materials include 7 percent wt. and 8 percent wt. yttria, partially stabilized zirconia as well as a cermet material. Both low pressure plasma spray and electron-beam physical vapor deposited coatings were tested. The data indicate the basic trends in the mechanical properties of the coatings over a wide range of isothermal conditions. Some of the trends are correlated with material density.

  1. Effectiveness of paper-structured catalyst for the operation of biodiesel-fueled solid oxide fuel cell

    Science.gov (United States)

    Quang-Tuyen, Tran; Kaida, Taku; Sakamoto, Mio; Sasaki, Kazunari; Shiratori, Yusuke

    2015-06-01

    Mg/Al-hydrotalcite (HDT)-dispersed paper-structured catalyst (PSC) was prepared by a simple paper-making process. The PSC exhibited excellent catalytic activity for the steam reforming of model biodiesel fuel (BDF), pure oleic acid methyl ester (oleic-FAME, C19H36O2) which is a mono-unsaturated component of practical BDFs. The PSC exhibited fuel conversion comparable to a pelletized catalyst material, here, conventional Ni-zirconia cermet anode for solid oxide fuel cell (SOFC) with less than one-hundredth Ni weight. Performance of electrolyte-supported cell connected with the PSC was evaluated in the feed of oleic-FAME, and stable operation was achieved. After 60 h test, coking was not observed in both SOFC anode and PSC.

  2. Very High Output Thermoelectric Devices Based on ITO Nanocomposites

    Science.gov (United States)

    Fralick, Gustave; Gregory, Otto J.

    2009-01-01

    A material having useful thermoelectric properties was synthesized by combining indium-tin-oxide (ITO) with a NiCoCrAlY alloy/alumina cermet. This material had a very large Seebeck coefficient with electromotive-force-versustemperature behavior that is considered to be excellent with respect to utility in thermocouples and other thermoelectric devices. When deposited in thin-film form, ceramic thermocouples offer advantages over precious-metal (based, variously, on platinum or rhodium) thermocouples that are typically used in gas turbines. Ceramic thermocouples exhibit high melting temperatures, chemical stability at high temperatures, and little or no electromigration. Oxide ceramics also resist oxidation better than metal thermocouples, cost substantially less than precious-metal thermocouples, and, unlike precious-metal thermocouples, do not exert catalytic effects.

  3. Analysis of nuclear waste disposal in space, phase 3. Volume 2: Technical report

    Science.gov (United States)

    Rice, E. E.; Miller, N. E.; Yates, K. R.; Martin, W. E.; Friedlander, A. L.

    1980-01-01

    The options, reference definitions and/or requirements currently envisioned for the total nuclear waste disposal in space mission are summarized. The waste form evaluation and selection process is documented along with the physical characteristics of the iron nickel-base cermet matrix chosen for disposal of commercial and defense wastes. Safety aspects of radioisotope thermal generators, the general purpose heat source, and the Lewis Research Center concept for space disposal are assessed as well as the on-pad catastrophic accident environments for the uprated space shuttle and the heavy lift launch vehicle. The radionuclides that contribute most to long-term risk of terrestrial disposal were determined and the effects of resuspension of fallout particles from an accidental release of waste material were studied. Health effects are considered. Payload breakup and rescue technology are discussed as well as expected requirements for licensing, supporting research and technology, and safety testing.

  4. Quantitative differential thermal analysis study of the U3O8-Al thermite reaction

    International Nuclear Information System (INIS)

    Concerns about proliferation resistance of nuclear fuel cycles and fuels have prompted a reinvestigation of U3O8-Al cermet fuels currently being used in research and test reactors. In particular, higher loadings of U3O8 are being considered. These new fuel compositions are in the region of maximum possible thermal energy release from the high-temperature thermite reaction between the U3O8 and aluminum components. This study was initiated to quantitatively measure the amount of reaction heat evolved. A differential thermal analysis system was calibrated with materials of known heat of reaction. Subsequently, specimens of high-uranium-loaded U3O8-Al powder mixtures were analyzed. Thermite reaction heat measured for these specimens was much lower than expected. Specimens of simulated fuel plates showed similar low results. Possible reasons for this behavior are discussed

  5. Quantitative differential thermal analysis study of the U3O8-Al thermite reaction

    Energy Technology Data Exchange (ETDEWEB)

    Pasto, A. E.; Copeland, G. L.; Martin, M. M.

    1980-01-01

    Concerns about proliferation resistance of nuclear fuel cycles and fuels have prompted a reinvestigation of U/sub 3/O/sub 8/-Al cermet fuels currently being used in research and test reactors. In particular, higher loadings of U/sub 3/O/sub 8/ are being considered. These new fuel compositions are in the region of maximum possible thermal energy release from the high-temperature thermite reaction between the U/sub 3/O/sub 8/ and aluminum components. This study was initiated to quantitatively measure the amount of reaction heat evolved. A differential thermal analysis system was calibrated with materials of known heat of reaction. Subsequently, specimens of high-uranium-loaded U/sub 3/O/sub 8/-Al powder mixtures were analyzed. Thermite reaction heat measured for these specimens was much lower than expected. Specimens of simulated fuel plates showed similar low results. Possible reasons for this behavior are discussed.

  6. Quantitative differential thermal analysis study of the U3O8-Al thermite reaction

    International Nuclear Information System (INIS)

    Concerns about proliferation resistance of nuclear fuel cycles and fuels have prompted a reinvestigation of U3O8-Al cermet fuels currently being used in research and test reactors. In particular, higher loadings of U3O8 are being considered. These new fuel compositions are in the region of maximum possible thermal energy release from the high-temperature thermite reaction between the U3O8 and aluminum components. This study was initiated to quantitatively measure the amount of reaction heat evolved. A differential thermal analysis system was calibrated with materials of known heat of reaction. Subsequently, specimens of high-uranium-loaded U3O8-Al powder mixtures were analyzed. Thermite reaction heat measured for these specimens was much lower than expected. Possible reason(s) for this behavior are discussed in the report

  7. Quantitative differential thermal analysis study of the U/sub 3/O/sub 8/-Al thermite reaction

    Energy Technology Data Exchange (ETDEWEB)

    Pasto, A.E.; Copeland, G.L.; Martin, M.M.

    1980-06-01

    Concerns about proliferation resistance of nuclear fuel cycles and fuels have prompted a reinvestigation of U/sub 3/O/sub 8/-Al cermet fuels currently being used in research and test reactors. In particular, higher loadings of U/sub 3/O/sub 8/ are being considered. These new fuel compositions are in the region of maximum possible thermal energy release from the high-temperature thermite reaction between the U/sub 3/O/sub 8/ and aluminum components. This study was initiated to quantitatively measure the amount of reaction heat evolved. A differential thermal analysis system was calibrated with materials of known heat of reaction. Subsequently, specimens of high-uranium-loaded U/sub 3/O/sub 8/-Al powder mixtures were analyzed. Thermite reaction heat measured for these specimens was much lower than expected. Possible reason(s) for this behavior are discussed in the report.

  8. Deposition and characterisation of epitaxial oxide thin films for SOFCs

    KAUST Repository

    Santiso, José

    2010-10-24

    This paper reviews the recent advances in the use of thin films, mostly epitaxial, for fundamental studies of materials for solid oxide fuel cell (SOFC) applications. These studies include the influence of film microstructure, crystal orientation and strain in oxide ionic conducting materials used as electrolytes, such as fluorites, and in mixed ionic and electronic conducting materials used as electrodes, typically oxides with perovskite or perovskite-related layered structures. The recent effort towards the enhancement of the electrochemical performance of SOFC materials through the deposition of artificial film heterostructures is also presented. These thin films have been engineered at a nanoscale level, such as the case of epitaxial multilayers or nanocomposite cermet materials. The recent progress in the implementation of thin films in SOFC devices is also reported. © 2010 Springer-Verlag.

  9. A pilot-scale trial of an improved galvanic deoxidation process for refining molten copper

    Science.gov (United States)

    Soral, P.; Pal, U.; Larson, H. R.; Schroeder, B.

    1999-04-01

    A laboratory-scale galvanic deoxidation technology developed by earlier workers has been improved, with the aim of developing a prototype pilot-scale deoxidation unit. Each deoxidation cell consists of a one end-closed yttria-stabilized zirconia (YSZ) tube coated with a Ni-YSZ cermet anode on the inner walls. The YSZ tube is immersed, with its closed end in the metallic melt, and an oxygen-chemical-potential gradient across the tube is established by passing a reducing gas through the tube. The melt is then deoxidized by short circuiting it with the anode. Through laboratory experimentation, the nature of the anode/electrolyte interface adhesion was identified to be an important factor in obtaining enhanced deoxidation kinetics. The kinetics of oxygen removal from the melt was increased by an order of magnitude with an improved anode/electrolyte interface. A pilot-scale refining unit consisting of 53 cells with the improved anode/electrolyte interface was manufactured, and a field evaluation of the galvanic deoxidation of copper was conducted. The deoxidation-process model was modified to include multiple deoxidation cells, which were required for the pilot-scale trials, and to analyze the effect of electrolyte/electrode adhesion on deoxidation kinetics. Preliminary studies on process component lifetimes were conducted by investigating the thermal cycling, corrosion behavior of the electrolyte, and stability of the cermet anode structure. Based on the results of the field trial and the analyses of the process component lifetime, future work needed toward commercializing the technology is discussed.

  10. Oxidation-resistant, solution-processed plasmonic Ni nanochain-SiOx (x < 2) selective solar thermal absorbers

    International Nuclear Information System (INIS)

    Metal oxidation at high temperatures has long been a challenge in cermet solar thermal absorbers, which impedes the development of atmospherically stable, high-temperature, high-performance concentrated solar power (CSP) systems. In this work, we demonstrate solution-processed Ni nanochain-SiOx (x 2 selective solar thermal absorbers that exhibit a strong anti-oxidation behavior up to 600 °C in air. The thermal stability is far superior to previously reported Ni nanoparticle-Al2O3 selective solar thermal absorbers, which readily oxidize at 450 °C. The SiOx (x 2 matrices are derived from hydrogen silsesquioxane and tetraethyl orthosilicate precursors, respectively, which comprise Si-O cage-like structures and Si-O networks. Fourier transform infrared spectroscopy shows that the dissociation of Si-O cage-like structures and Si-O networks at high temperatures have enabled the formation of new bonds at the Ni/SiOx interface to passivate the surface of Ni nanoparticles and prevent oxidation. X-ray photoelectron spectroscopy and Raman spectroscopy demonstrate that the excess Si in the SiOx (x x (x 2 systems. This oxidation-resistant Ni nanochain-SiOx (x < 2) cermet coating also exhibits excellent high-temperature optical performance, with a high solar absorptance of ∼90% and a low emittance ∼18% measured at 300 °C. These results open the door towards atmospheric stable, high temperature, high-performance solar selective absorber coatings processed by low-cost solution-chemical methods for future generations of CSP systems

  11. Ti(C,N and (Ti,AlN hard wear resistant coatings

    Directory of Open Access Journals (Sweden)

    K. Gołombek

    2010-04-01

    Full Text Available Purpose: Investigation the influence of kind of PVD coatings structure (homogenous or gradient on properties of deposited tool materials: cemented carbides and cermets.Design/methodology/approach: Analysis of the structure, analysis of the mechanical and functional properties: surface roughness, microhardness tests, scratch tests, cutting tests. The Ti(C,N gradient coating was investigated by XPS method with multifunctional PHI 5700/660 spectrometer. The characteristic of surface region coating were determined from XPS depth profile. X-ray qualitative phase analysis and the grazing incidence X-ray diffraction method (GIXRD was employed to collect the detailed information about phase composition of investigated material’s surface layer. Microstructural of investigations substrates and coatings by transmission electron miocroscopy (TEM were done.Findings: Results of the investigation the influence of PVD coatings structure (homogenous or gradient and kind on properties of coated tool materials: cemented carbides and cermets are given in the paper. Coatings are characterized by dense, compact structure, there have been identified no pores, fractures and discontinuities. The coatings were deposited uniformly onto the investigated substrate materials and show a characteristic columnar, fine-graded structure. The results of roughness, microhardness and cutting tests confirm the advantages of the PVD coatings. The coatings deposited onto the investigated substrates are characterised by good adhesion and causes increasing of wear resistance. The grazing incidence X-ray diffraction method (GIXRD in the investigated coatings were used to describe the structure and gradient character of the coatings.Practical implications: Deposition of hard, thin, gradient coatings on materials surface by PVD method features one of the most intensely developed directions of improvement of the working properties of materials.Originality/value: New techniques of gradient

  12. Evaluación de las transformaciones estructurales en recubrimientos de WC10Ni depositados por laser cladding sobre acero para herramienta EN 12379

    Directory of Open Access Journals (Sweden)

    Candel, J. J.

    2011-08-01

    Full Text Available Carbide metal matrix composite materials are known for a high resistance to all types of wear. It is due to a beneficial combination of properties given by hard phase particles included in a tough matrix. Different kinds of those materials have been employed in the development of new high properties cutting tools. Laser cladding (LC technique allows obtaining an accurate defect-free coating with a low thermal affectation of the component. But in the case of WC cermet coatings due to its high laser absorption and the different mechanical and thermal properties between substrate and coating can appear a wide range of different defects as cracks, pores, massive carbide dilution and lacks of adherence. The aim of the present work is to study the metallurgical transformations during LC process of WC cermet coating on cold work tool steel substrate (EN 12379. Also it has been related process parameters with defects generation. Microstructure and composition of the coating and the heat affected zone have been analysed. Microhardness evolution profile has been obtained. Results show that although process parameters control reduce the generation of defects, in the deposition of overlapped layers appear different metallurgical transformations related with massive WC decomposition and the diffusion of alloying elements from substrate to the coating.

    Los materiales compuestos de matriz metálica reforzados con carburos, son conocidos por su elevada resistencia a todos los tipos de desgaste, debido a la combinación de las partículas duras en una matriz metálica tenaz. Diferentes tipos de estos materiales, se han empleado en el desarrollo de nuevas herramientas de corte de altas prestaciones. La técnica de láser cladding (LC, permite obtener recubrimientos libres de defectos sobre zonas muy concretas, con un aporte de calor muy localizado. Pero en el caso de carburos de wolframio (WC, debido a la enorme absorción de energía y la

  13. Microstructural degradation of Ni-YSZ anodes for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Thyden, K.

    2008-03-15

    Ni-YSZ cermets have been used as anode materials in SOFCs for more than 20 years. Despite this fact, the major cause of degradation within the Ni-YSZ anode, namely Ni sintering / coarsening, is still not fully understood. Even if microstructural studies of anodes in tested cells are of technological relevance, it is difficult to identify the effect from isolated parameters such as temperature, fuel gas composition and polarization. Model studies of high temperature aged Ni-YSZ cermets are generally performed in atmospheres containing relatively low concentrations of H2O. In this work, the microstructural degradation in both electrochemically longterm tested cells and high-temperature aged model materials are studied. Since Ni particle sintering / coarsening is attributed to be the major cause of anode degradation, this subject attains the primary focus. A large part of the work is focused on improving microstructural techniques and shows that the application of low acceleration voltages (<= 1 kV) in a FE-SEM makes it possible to obtain two useful types of contrast between the phases in Ni-YSZ composites. By changing between the ordinary lateral SE detector and the inlens detector, using similar microscope settings, two very different sample characteristics are probed: 1) The difference in secondary emission coefficient, delta, between the percolating and non-percolating Ni is maximized in the low-voltage range due to a high delta for the former and the suppression of delta by a positive charge for the latter. This difference yields a contrast between the two phases which is picked up by an inlens secondary electron detector. 2) The difference in backscatter coefficient, eta, between Ni and YSZ is shown to increase with decreasing voltage. The contrast is illustrated in images collected by the normal secondary detector since parts of the secondary signals are generated by backscattered electrons. High temperature aging experiments of model Ni-YSZ anode cermets show

  14. Effects of dopants and trace elements at the Ni / ScYSZ interface

    Energy Technology Data Exchange (ETDEWEB)

    Stenbaek Schmidt, M.

    2008-08-15

    The interfaces between the various materials and phases in solid oxide fuel cells (SOFCs) play a fundamental role, when optimizing SOFC performance. The industrial grade materials commonly used in SOFCs contain numerous impurities. At the catalyst / electrolyte interfaces in SOFC cermet anodes, these impurities are believed to be responsible for losses in electrochemical performance. Impurities such as silica have been shown to segregate to the three phase boundary (TPB) in SOFC cermet anodes. A three-electrode configuration, with a high purity (99.999 %) nickel pointelectrode acting as the working electrode, was used as a simplified model of the SOFC cermet anode. Electrochemical impedance spectroscopy was used to characterise the electrode polarisation resistances on selected electrolyte materials at 850 deg. C in humidified hydrogen atmospheres. Electrode reactions were characterized on two types of scandia and yttria co-doped zirconia electrolytes (ScYSZ) with different purity levels, a ScYSZ electrolyte doped with alumina and an yttria stabilized zirconia (YSZ) electrolyte. A point electrode setup provided a well defined electrode / electrolyte interface (EEI) and TPB during electrochemical characterisation, which, after lifting the electrode off the electrolyte, could be studied by surface analysis techniques. Surface analysis was performed using low acceleration voltage scanning electron microscopy (SEM), atomic force microscopy (AFM), time of flight secondary ion mass spectrometry (ToF-SIMS) and xray photoelectron spectroscopy (XPS). For all electrolyte materials the electrode polarization resistances dropped rapidly during the first 50 hours of measurements at 850 deg. C before stabilising. From ToFSIMS and SEM analysis, rim zones with relatively low impurity concentrations were identified at the outer perimeter of the EEI on the electrolyte surfaces. It was suggested that the rim zones were formed, as the nickel electrode expanded, due to metallic creep

  15. ESCORT: A Pratt & Whitney nuclear thermal propulsion and power system for manned mars missions

    Science.gov (United States)

    Feller, Gerald J.; Joyner, Russell

    1999-01-01

    The purpose of this paper is to describe the conceptual design of an upgrade to the Pratt & Whitney ESCORT nuclear thermal rocket engine. The ESCORT is a bimodal engine capable of supporting a wide range of vehicle propulsive and electrical power requirements. The ESCORT engine is powered by a fast-spectrum beryllium-reflected CERMET-fueled nuclear reactor. In propulsive mode, the reactor is used to heat hot hydrogen to approximately 2700 K which is expanded through a converging/diverging nozzle to generate thrust. Heat pickup in the nozzle and the radial beryllium reflectors is used to drive the turbomachinery in the ESCORT expander cycle. In electrical mode, the reactor is used to heat a mixture of helium and xenon to drive a closed-loop Brayton cycle in order to generate electrical energy. This closed loop system has the additional function of a decay heat removal system after the propulsive mode operation is discontinued. The original ESCORT design was capable of delivering 4448.2 N (1000 lbf) of thrust at a vacuum impulse level of approximately 900 s. Design Reference Mission requirements (DRM) from NASA Johnson Space Center and NASA Lewis Research Center studies in 1997 and 1998 have detailed upgraded requirements for potential manned Mars missions. The current NASA DRM requires a nuclear thermal propulsion system capable of delivering total mission requirements of 200170 N (45000 lbf) thrust and 50 kWe of spacecraft electrical power. This is met assuming three engines capable of each delivering 66723 N (15000 lbf) of vacuum thrust and 25 kWe of electrical power. The individual engine requirements were developed assuming three out of three engine reliability for propulsion and two out of three engine reliability for spacecraft electrical power. The approximate target vacuum impulse is 925 s. The Pratt & Whitney ESCORT concept was upgraded to meet these requirements. The hexagonal prismatic fuel elements were modified to address the uprated power requirements

  16. Brazing of 14-5 PH steel and WC-Co sinterson considerable dimension surfaces

    Directory of Open Access Journals (Sweden)

    J. Nowacki

    2007-03-01

    Full Text Available Purpose: of this paper is study of structure properties of considerable surfaces vacuum brazed joints of WC-Co sinters and precipitation hardened stainless steel of 14-5 PH using copper and silver-copper as the brazing filler metal.Design/methodology/approach: the joints are used in large dimension spinning nozzles of a die for polyethylene granulation, in that considerable strength and ductility of the joints are required. Structure and mechanical properties of joints have been described. Shear strength Rt and tensile strength Rm of the joints have been defined.Findings: to have been state, that the basic factors decreasing quality of the joint, which can occur during vacuum brazing of the WC-Co ISO K05 sinter – Cu or Ag-Cu brazing filler metal – 14-5 PH steel joints are diffusive processes leading to exchange of elements of cermets and the brazing filler metal and creation of intermetalics in the joint. It can have an unfavourable influence on ductility of sinters and quality of joint. As a result of brazing tests the influence of means and parameters of the brazing on quality of a joint was determined.Research limitations/implications: as a result of the experiments scheme of the joint structure WC-Co ISO K05 sinter – Cu brazing filler metal – 14-5 PH steel joint and WC-Co ISO K05 sinter – Cu brazing filler metal – 14-5 PH have been described.Practical implications: as a result of conducted experiments a production of spinning nozzle of a die for polyethylene granulation with a vacuum-brazed with a WC-Co ISO K05 sinters plates cutting surface of large surfaces on precipitation hardened stainless steel 14-5 PH have been worked out and industrial applied.Originality/value: the basic factors decreasing quality of the joint, which can occur while vacuum brazing of stainless steels and cermets have been determined.

  17. 溶胶-凝胶法制备Ti(C,N)-Mo2C-Ni复合粉末的研究%Study on Preparation of Ti(C,N)-Mo2C-Ni Power by Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    陈明; 伍小波

    2012-01-01

    In this research, a kind of Ti(C,N)-Mo2C-Ni cermet powder was prepared by sol-gel method at low temperature (1400℃). Through infrared spectrum (FTIR), X-ray ray diffraction (XRD), thermogravimetric analyzer (TG-DTA), scanning electron microscopy (SEM), energy spectrum (EDS), specific surface area analyzer (BET) and nitrogen/ oxygen content detecting method, the preparation process of the powder was primarily studied and analyzed. The results show that, by using tetrabutyl titanate as titanium source, sucrose as carbon source and ethylene glycol as solvent, the metal ceramic powder prepared by sol-gel method and carbothermal reduction method under the 1 400℃ and vacuum conditions, has fine crystal grain and high purity. Its evolution process as that, through hydrolysis, polycondensation, cracking/ decomposition reactions and drying, the TiO2 mixed precursor was obtained, then after carbon thermal reduction and a series of chemical reactions the Ti(C,N)-Mo2C-Ni cermet powder was finally prepared.%本文采用溶胶-凝胶法在较低温度(1400℃)下制备了Ti(C,N)-Mo2C-Ni金属陶瓷复合粉末.通过红外光谱(FTIR)、X-ray衍射(XRD)、热重分析(TG-DTA),扫描电镜(SEM)、能谱(EDS)、比表面积分析(BET)、氮/氧含量测定等分析检测方法,对该粉末的制备过程进行了初步的研究与分析.结果表明:在1400℃,真空条件下,以钛酸四丁酯为钛源,以蔗糖为碳源,乙二醇为溶剂,采用溶胶-凝胶法结合碳热还原法所制得的Ti(C,N)-Mo2C-Ni金属陶瓷复合粉末晶粒小,纯度较高;其制备机理为:原料通过水解、缩聚、裂解/分解等反应,经过干燥后首先得到TiO2混合先驱体粉末,再经过碳热还原及一系列化学反应最后生成了Ti(C,N)-Mo2C-Ni金属陶瓷复合粉末.

  18. Investigations of the oxidation-induced service life of chromium steels for high temperature fuel cell application (SOFC); Untersuchungen zur oxidationsbedingten Lebensdauer von Chromstaehlen fuer die Anwendung in der Hochtemperaturbrennstoffzelle (SOFC)

    Energy Technology Data Exchange (ETDEWEB)

    Ertl, S.T.

    2006-08-17

    The increasing energy consumption of future automobiles should be covered by a solid oxide fuel cell (SOFC) used as an additional energy supply (auxiliary power unit). The application of a SOFC with about 5 kW power in cars requires small size, low weight and an economic fabrication. To achieve this goal the interconnector and the metallic anode substrate (depending on an alternative concept of construction) should be manufactured out of thin Crofer22APU, a high chromium ferritic steel. The scale formation mechanisms on Crofer22APU sheets, wires and powder metallurgical produced foils of different thicknesses were investigated in several atmospheres of water vapour/hydrogen at 800 and 900 C, simulating the anode conditions. For scale characterization a number of conventional analysis techniques such as optical metallography, scanning electron microscopy and X-ray diffraction were used in combination with deflection testing in monofacial oxidation and two-stage oxidation studies using {sup 18}O and H{sub 2} {sup 18}O tracer. With these results a theoretical model for the determination of lifetime was developed for Crofer22APU components in simulated anode gas. It was found that the lifetime at a given temperature depends not only on the surface-to-volume ratio, but also on the geometry of the component (e.g. sheet or wire). The critical Cr content required for breakaway oxidation depends on microcrack formation in the surface oxide scale, which occurs on ridges of a sheet during thermal cycling. The development of a metallic interconnector and a metallic anode substrate requires measures to avoid interdiffusion between the alloy and the bordering nickel-YSZ (yttrium stabilized zirconia) cermet of the anode, or depending on the conception of the stack, the bordering nickel-YSZ cermet of the anode functional layer. Therefore the suitability of preoxidation layers after different preoxidation conditions was tested. It was found that the inhibition of the interdiffusion

  19. LONG-TERM PERFORMANCE OF SOLID OXIDE STACKS WITH ELECTRODE-SUPPORTED CELLS OPERATING IN THE STEAM ELECTROLYSIS MODE

    Energy Technology Data Exchange (ETDEWEB)

    J. E. O' Brien; R. C. O' Brien; X. Zhang; G. Tao; B. J. Butler

    2011-11-01

    Performance characterization and durability testing have been completed on two five-cell high-temperature electrolysis stacks constructed with advanced cell and stack technologies. The solid oxide cells incorporate a negative-electrode-supported multi-layer design with nickel-zirconia cermet negative electrodes, thin-film yttria-stabilized zirconia electrolytes, and multi-layer lanthanum ferrite-based positive electrodes. The per-cell active area is 100 cm2. The stack is internally manifolded with compliant mica-glass seals. Treated metallic interconnects with integral flow channels separate the cells. Stack compression is accomplished by means of a custom spring-loaded test fixture. Initial stack performance characterization was determined through a series of DC potential sweeps in both fuel cell and electrolysis modes of operation. Results of these sweeps indicated very good initial performance, with area-specific resistance values less than 0.5 ?.cm2. Long-term durability testing was performed with A test duration of 1000 hours. Overall performance degradation was less than 10% over the 1000-hour period. Final stack performance characterization was again determined by a series of DC potential sweeps at the same flow conditions as the initial sweeps in both electrolysis and fuel cell modes of operation. A final sweep in the fuel cell mode indicated a power density of 0.356 W/cm2, with average per-cell voltage of 0.71 V at a current of 50 A.

  20. Open- and closed-circuit study of an intermediate temperature SOFC directly fueled with simulated biogas mixtures

    Science.gov (United States)

    Yentekakis, Ioannis V.

    An intermediate temperature solid oxide fuel cell (SOFC) based on a gadolinia doped ceria (GDC) solid electrolyte, a Ni(Au)-GDC cermet anode and a La 0.54Sr 0.46MnO 3 perovskite cathode was tested at 600 and 640 °C on direct feed of simulated biogas mixtures. The catalytic (open-circuit) rate of the methane dry (CO 2)-reforming reaction over Ni(Au)-GDC anode was found to be maximized at about equimolar CH 4/CO 2 feed ratio. Cell power density up to 60 mW cm -2, at a cell voltage of 445 mV and a current density of 135 mA cm -2 at 640 °C, has been obtained under closed-circuit cell operation at this optimal feed ratio. Carbon deposition was found not to downgrade cell output characteristics under closed-circuit conditions at constant external loads for ∼120 h, preceded by open- or closed-circuit operation for ∼100 additional hours.

  1. Standard test method for static leaching of monolithic waste forms for disposal of radioactive waste

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method provides a measure of the chemical durability of a simulated or radioactive monolithic waste form, such as a glass, ceramic, cement (grout), or cermet, in a test solution at temperatures <100°C under low specimen surface- area-to-leachant volume (S/V) ratio conditions. 1.2 This test method can be used to characterize the dissolution or leaching behaviors of various simulated or radioactive waste forms in various leachants under the specific conditions of the test based on analysis of the test solution. Data from this test are used to calculate normalized elemental mass loss values from specimens exposed to aqueous solutions at temperatures <100°C. 1.3 The test is conducted under static conditions in a constant solution volume and at a constant temperature. The reactivity of the test specimen is determined from the amounts of components released and accumulated in the solution over the test duration. A wide range of test conditions can be used to study material behavior, includin...

  2. Pinellas Plant facts

    International Nuclear Information System (INIS)

    This plant was built in 1956 in response to a need for the manufacture of neutron generators, a principal component in nuclear weapons. The neutron generators consist of a miniaturized linear ion accelerator assembled with the pulsed electrical power supplies required for its operation. The ion accelerator, or neutron tube, requires ultra clean, high vacuum technology: hermetic seals between glass, ceramic, glass-ceramic, and metal materials: plus high voltage generation and measurement technology. The existence of these capabilities at the Pinellas Plant has led directly to the assignment of the lightning arrester connector, specialty capacitor, vacuum switch, and crystal resonator. Active and reserve batteries and the radioisotopically-powered thermoelectric generator draw on the materials measurement and controls technologies which are required to ensure neutron generator life. A product development and production capability in alumina ceramics, cermet (electrical) feedthroughs, and glass ceramics has become a specialty of the plant; the laboratories monitor the materials and processes used by the plant's commercial suppliers of ferroelectric ceramics. In addition to the manufacturing facility, a production development capability is maintained at the Pinellas Plant

  3. Helium in inert matrix dispersion fuels

    International Nuclear Information System (INIS)

    The behaviour of helium, an important decay product in the transmutation chains of actinides, in dispersion-type inert matrix fuels is discussed. A phenomenological description of its accumulation and release in CERCER and CERMET fuel is given. A summary of recent He-implantation studies with inert matrix metal oxides (ZrO2, MgAl2O4, MgO and Al2O3) is presented. A general picture is that for high helium concentrations helium and vacancy defects form helium clusters which convert into over-pressurized bubbles. At elevated temperature helium is released from the bubbles. On some occasions thermal stable nano-cavities or nano-pores remain. On the basis of these results the consequences for helium induced swelling and helium storage in oxide matrices kept at 800-1000 deg. C will be discussed. In addition, results of He-implantation studies for metal matrices (W, Mo, Nb and V alloys) will be presented. Introduction of helium in metals at elevated temperatures leads to clustering of helium to bubbles. When operational temperatures are higher than 0.5 melting temperature, swelling and helium embrittlement might occur

  4. Thermal sensor properties of PANI(EB)–CSA ( = 0.4 ± 0.1 mol) polymer thin films

    Indian Academy of Sciences (India)

    T Prakash; S A K Narayan Dass; K Prem Nazeer

    2002-11-01

    Films of polyaniline(EB) doped with camphor sulfonic acid (CSA) from -cresol on glass substrates exhibit considerable metallic properties. Such polymer metallic films have thermal sensitivity superior to ceramic metal (Cermet) films, prepared by metallo organic deposition (MOD) technique on silicon substrates. These PANI(EB)–CSA ( = 0.5, 0.4, 0.3 mol) polymer films were developed through controlled temperature atmosphere 60 ± 2°C for 60 min, and with the help of temperature dependence of resistivity (ρ) values, high temperature coefficient of resistance (TCR) i.e. values, and figure of merit (ρ ) values of these films, thermal sensitivity were compared from that we observed. Among the three doping ratios the PANI(EB)–CSA$_{0.3 mol}$ film (4.4 m thick) on glass substrate resistivity (ρ) values in the range of 838–1699 .m with high TCR i.e. = 10,291 ppm/°C and figure of merit (ρ ) value in range of 8.62–17.48 m/°C seems to be the best. This paper deals with these superior thermal-sensing properties together with optical studies and surface topography by atomic force microscopy (AFM). These polymer films offer design advantages in developing ‘thin film polymer thermal sensor’.

  5. Thermionic Technology Program: A, Insulator test and evaluation: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Dobson, J.C.; Witt, T.

    1987-11-30

    The Thermionic Technology Program (TTP) consisted of two major efforts, evaluation of insulators and evaluation of thermionic converters. This report details the work performed on the insulator phase of the program. Efforts were made to better understand the mechanisms involved in the electrochemistry of insulators at elevated temperatures by modelling the ionic transport through the various layers of the insulator package. Although rigorous analytic solutions could not be obtained owing to a lack of detailed data, a simplified model indicated that alumina should not fail by depletion of aluminum for thousands of years, whereas calculations for yttria revealed a far more rapid depletion of oxygen and consequently earlier failure. Methods for microscopic and electrical testing of cylindrical insulator samples were developed, and an improved test oven design was initiated. Testing of alumina/niobium cermet samples revealed rapid failure contrary to the theoretical predictions for alumina. Large discrepancies in the initial conduction activation energy among the various samples suggested that different mechanisms could have controlled the conduction and hence the failure in different samples, although all had undergone nominally identical processing. The short lifetimes reveal how rapidly ambient conditions in thermionic power conversion can degrade the performance of insulating oxides. It was concluded that minor dopants could have been responsible for the early breakdowns. Thus, high purity materials with precise quality control will be necessary for trilayer package development. 35 refs., 28 figs., 5 tabs.

  6. Design and analysis of a single stage to orbit nuclear thermal rocket reactor engine

    Energy Technology Data Exchange (ETDEWEB)

    Labib, Satira, E-mail: Satira.Labib@duke-energy.com; King, Jeffrey, E-mail: kingjc@mines.edu

    2015-06-15

    Graphical abstract: - Highlights: • Three NTR reactors are optimized for the single stage launch of 1–15 MT payloads. • The proposed rocket engines have specific impulses in excess of 700 s. • Reactivity and submersion criticality requirements are satisfied for each reactor. - Abstract: Recent advances in the development of high power density fuel materials have renewed interest in nuclear thermal rockets (NTRs) as a viable propulsion technology for future space exploration. This paper describes the design of three NTR reactor engines designed for the single stage to orbit launch of payloads from 1 to 15 metric tons. Thermal hydraulic and rocket engine analyses indicate that the proposed rocket engines are able to reach specific impulses in excess of 800 s. Neutronics analyses performed using MCNP5 demonstrate that the hot excess reactivity, shutdown margin, and submersion criticality requirements are satisfied for each NTR reactor. The reactors each consist of a 40 cm diameter core packed with hexagonal tungsten cermet fuel elements. The core is surrounded by radial and axial beryllium reflectors and eight boron carbide control drums. The 40 cm long reactor meets the submersion criticality requirements (a shutdown margin of at least $1 subcritical in all submersion scenarios) with no further modifications. The 80 and 120 cm long reactors include small amounts of gadolinium nitride as a spectral shift absorber to keep them subcritical upon submersion in seawater or wet sand following a launch abort.

  7. Kinetic and geometric aspects of solid oxide fuel cell electrodes

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Skaarup, Steen

    1996-01-01

    The paper gives an overview of the main factors controlling the performance of the solid oxide fuel cell (SOFC) electrodes, emphasizing the most widely chosen anodes and cathodes, Ni-YSZ and LSM-YSZ. They are often applied as composites (mixtures) of the electron conducting electrode material...... and the ion conducting electrolyte. Some reasons for this choice are: I)to increase the three-phase-boundary (TPB) length (key reactants must pass the TPB) and 2) to assure good adherence of the electrodes to the electrolyte. In the case of Ni-YSZ cermet anode it is also clear that the electrochemical...... are is much more dependent on the structure than the low frequency arcs. In the case of LSM-YSZ composite it has been demonstrated that both the ratio of LSM to YSZ and the conductivity of the YSZ is of major importance. The length and the nature of the three-phase-boundary between LSM, YSZ and air influence...

  8. Application of powder injection moulding and extrusion process to manufacturing of Ni-YSZ anodes

    Directory of Open Access Journals (Sweden)

    G. Matula

    2009-09-01

    Full Text Available Purpose: Investigation of the Ni-YSZ cermets for anode supported solid oxide fuel cells (SOFC prepared by extrusion or powder injection moulding process, sintered and reduced of NiO-YSZ. Design/methodology/approach: Density examination, shrinkage examination, transverse rupture strength tests, microstructure examination.Findings: Results of the rheological and torque investigations have essential importance for further search of the optimum feedstock to injection moulding machines and extruders making forming possible of shapes for fuel cells anodes, which require in addition debinding of the binder, sintering, and reduction.Practical implications: The proposed technological solutions for fabricating anodes as tubes or flat shapes will make connecting the cells into packets possible which will allow increasing the cell power.Originality/value: The presented investigation results confirm purposefulness of employing injection moulding or extrusion for fabrication of fuel cells anodes. These two methods are used for manufacturing elements of devices in a mass scale. Significant interest in fuel cells and rapid development of their production which should take place in the close future may be the reason for searching the inexpensive technological solutions in the manufacturing process of the cells.

  9. Development of high toughness, high strength aluminide-bonded carbide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Becher, P.F.; Plucknett, K.P.; Tiegs, T.N. [Oak Ridge National Lab., TN (United States)] [and others

    1997-04-01

    Cemented carbides are widely used in applications where resistance to abrasion and wear are important, particularly in combination with high strength and stiffness. In the present case, ductile aluminides have been used as a binder phase to fabricate dense carbide cermets by either sintering of mixed powders or a melt-infiltration sintering process. The choice of an aluminide binder was based on the exceptional high temperature strength and chemical stability exhibited by these alloys. For example, TiC-based composites with a Ni{sub 3}Al binder phase exhibit improved oxidation resistance, Young`s moduli > 375 GPa, high fracture strengths (> 1 GPa) that are retained to {ge} 900{degrees}C, and fracture toughness values of 10 to 15 MPa{radical}m, identical to that measured in commercial cobalt-bonded WC with the same test method. The thermal diffusivity values at 200{degrees}C for these composites are {approximately} 0.070 to 0.075 cm{sup 2}/s while the thermal expansion coefficients rise with Ni3Al content from {approximately} 8 to {approximately}11 x 10{sup {minus}6}/{degrees}C over the range of 8 to 40 vol. % Ni{sub 3}Al. The oxidation and acidic corrosion resistances are quite promising as well. Finally, these materials also exhibit good electrical conductivity allowing them to be sectioned and shaped by electrical discharge machining (EDM) processes.

  10. Pinellas Plant facts. [Products, processes, laboratory facilities

    Energy Technology Data Exchange (ETDEWEB)

    1986-09-01

    This plant was built in 1956 in response to a need for the manufacture of neutron generators, a principal component in nuclear weapons. The neutron generators consist of a miniaturized linear ion accelerator assembled with the pulsed electrical power supplies required for its operation. The ion accelerator, or neutron tube, requires ultra clean, high vacuum technology: hermetic seals between glass, ceramic, glass-ceramic, and metal materials: plus high voltage generation and measurement technology. The existence of these capabilities at the Pinellas Plant has led directly to the assignment of the lightning arrester connector, specialty capacitor, vacuum switch, and crystal resonator. Active and reserve batteries and the radioisotopically-powered thermoelectric generator draw on the materials measurement and controls technologies which are required to ensure neutron generator life. A product development and production capability in alumina ceramics, cermet (electrical) feedthroughs, and glass ceramics has become a specialty of the plant; the laboratories monitor the materials and processes used by the plant's commercial suppliers of ferroelectric ceramics. In addition to the manufacturing facility, a production development capability is maintained at the Pinellas Plant.

  11. [Alloys for metal-ceramics 3].

    Science.gov (United States)

    Quintero Englembright, M A; Barceló Santana, F; Palma Calero, M

    1991-01-01

    A wide variety of restoration materials for prosthetic odontology is now available to the dental surgeon, either of the covalent type (acrylic resins), metallic (alloys), ionic (porcelains), or a combination of them, as in the so-called composites, such as the composite resins, or as ceramics-metals mixtures. An example of the latter is a product called Miracle-Mix, a glass ionomere cement reinforced with an amalgam alloy. In those cases where the blend is done by a synterization process, the material is called Cermet. The above-listed alternatives clearly evidence day-to-day advances in odontology, with researchers and manufacturers engaged the world over in improving existing products or developing new ones to enrich the dentist's armamentarium. As a side effect of this constant renewal, those dentists who have failed to update their knowledge fall behind in their practice as they persist in using products they have known for years, and may be deceived by advertisements of too-often unreliable products. It is, therefore, important to be aware of available products and their latest improvements. PMID:1946199

  12. [Prosthetic dental alloys. 1].

    Science.gov (United States)

    Quintero Engelmbright, M A

    1990-11-01

    A wide variety of restoration materials for prosthetic odontology is now available to the dental surgeon, either of the covalent type (acrylic resins), metallic (alloys), ionic (porcelains), or a combination of them, as in the so-called composites, such as the composite resins, or as ceramics-metals mixtures. An example of the latter is a product called Miracle-Mix, a glass ionomere cement reinforced with an amalgam alloy. In those cases where the blend is done by a synterization process, the material is called Cermet. The above-listed alternatives clearly evidence day-to-day advances in odontology, with researchers and manufacturers engaged the world over in improving existing products or developing new ones to enrich the dentist's armamentarium. As a side effect of this constant renewal, those dentists who have failed to update their knowledge fall behind in their practice as they persist in using products they have known for years, and may be deceived by advertisements of too-often unreliable products. It is, therefore, important to be aware of available products and their latest improvements. PMID:2132464

  13. [Prosthetic dental alloys (2)].

    Science.gov (United States)

    Quintero Englembright, M A

    1990-12-01

    A wide variety of restoration materials for prosthetic odontology is now available to the dental surgeon, either of the covalent type (acrylic resins), metallic (alloys), ionic (porcelains), or a combination of them, as in the so-called composites, such as the composite resins, or as ceramics-metals mixtures. An example of the latter is a product called Miracle-Mix, a glass ionomere cement reinforced with an amalgam alloy. In those cases where the blend is done by a synterization process, the material is called Cermet. The above-listed alternatives clearly evidence day-to-day advances in odontology, with researchers and manufacturers engaged the world over in improving existing products or developing new ones to enrich the dentist's armamentarium. As a side effect of this constant renewal, those dentists who have failed to update their knowledge fall behind in their practice as they persist in using products they have known for years, and may be deceived by advertisements of too-often unreliable products. It is, therefore, important to be aware of available products and their latest improvements. PMID:2132470

  14. Compact Fuel Element Environment Test

    Science.gov (United States)

    Bradley, D. E.; Mireles, O. R.; Hickman, R. R.; Broadway, J. W.

    2012-01-01

    Deep space missions with large payloads require high specific impulse (I(sub sp)) and relatively high thrust to achieve mission goals in reasonable time frames. Conventional, storable propellants produce average I(sub sp). Nuclear thermal rockets (NTRs) capable of high I(sub sp) thrust have been proposed. NTR employs heat produced by fission reaction to heat and therefore accelerate hydrogen, which is then forced through a rocket nozzle providing thrust. Fuel element temperatures are very high (up to 3,000 K) and hydrogen is highly reactive with most materials at high temperatures. Data covering the effects of high-temperature hydrogen exposure on fuel elements are limited. The primary concern is the mechanical failure of fuel elements that employ high melting point metals, ceramics, or a combination (cermet) as a structural matrix into which the nuclear fuel is distributed. It is not necessary to include fissile material in test samples intended to explore high-temperature hydrogen exposure of the structural support matrices. A small-scale test bed designed to heat fuel element samples via noncontact radio frequency heating and expose samples to hydrogen for typical mission durations has been developed to assist in optimal material and manufacturing process selection without employing fissile material. This Technical Memorandum details the test bed design and results of testing conducted to date.

  15. Investigation into the diffusion and oxidation behavior of the interface between a plasma-sprayed anode and a porous steel support for solid oxide fuel cells

    Science.gov (United States)

    Zhang, Shan-Lin; Li, Cheng-Xin; Li, Chang-Jiu; Liu, Meilin; Yang, Guan-Jun

    2016-08-01

    Porous metal-supported solid oxide fuel cells (SOFCs) have attracted much attention because their potential to dramatically reduce the cost while enhancing the robustness and manufacturability. In particular, 430 ferritic steel (430L) is one of the popular choice for SOFC support because of its superior performance and low cost. In this study, we investigate the oxidation and diffusion behavior of the interface between a Ni-based anode and porous 430L support exposed to a humidified (3% H2O) hydrogen atmosphere at 700 °C. The Ni-GDC (Ce0.8Gd0.2O2-δ) cermet anodes are deposited on the porous 430L support by atmospheric plasma spraying (APS). The effect of exposure time on the microstructure and phase structure of the anode and the supports is studied and the element diffusion across the support/anode interface is characterized. Results indicate that the main oxidation product of the 430L support is Cr2O3, and that Cr and Fe will diffuse to the anode and the diffusion thickness increases with the exposure time. The diffusion thickness of Cr and Fe reach about 5 and 2 μm, respectively, after 1000 h exposure. However, the element diffusion and oxidation has little influence on the area-specific resistance, indicating that the porous 430L steel and plasma sprayed Ni-GDC anode are promising for durable SOFCs.

  16. Hydrogen Permeation Performance of Ni-BaZr0.1Ce0.7Y0.2O3-δ Metal-Ceramic Hollow Fiber Membrane

    Institute of Scientific and Technical Information of China (English)

    Chun-li Yang; Qi-ming Xu; Zhi-wen Zhu; Wei Liu

    2012-01-01

    A dense Ni-BaZr0.1Ce0.7Y0.2O3-δ (BZCY) cermet hollow fiber is fabricated by sintering NiOBZCY hollow fiber precursors prepared by phase inversion method in 5%H2/95%Ar and its hydrogen permeation performance is investigated. The Ni-BZCY hollow fiber membrane possesses a "sandwich" structure.Finger-like structures are observed near both the inner and outer surfaces,while a dense layer is present in the center part.With 200 mL/min wet 20%H2/80%N2 on the shell side and 150 mL/min high purity Ar on the core side,the hydrogen permeation flux through the Ni-BZCY hollow fiber membrane at 900 ℃ is 0.53 μmol/cm2s.Owing to a high packing density,the hydrogen permeation flux per unit volume is greatly improved and membrane components composed of an assembly of hollow fibers may be applied in industrial hydrogen separation.

  17. Dynamic evaluation of low-temperature metal-supported solid oxide fuel cell oriented to auxiliary power units

    Science.gov (United States)

    Wang, Zhenwei; Berghaus, Jörg Oberste; Yick, Sing; Decès-Petit, Cyrille; Qu, Wei; Hui, Rob; Maric, Radenka; Ghosh, Dave

    A metal-supported solid oxide fuel cell (SOFC) composed of a Ni-Ce 0.8Sm 0.2O 2- δ (Ni-SDC) cermet anode and an SDC electrolyte was fabricated by suspension plasma spraying on a Hastelloy X substrate. The cathode, an Sm 0.5Sr 0.5CoO 3 (SSCo)-SDC composite, was screen-printed and fired in situ. The dynamic behaviour of the cell was measured while subjected to complete fuel shutoff and rapid start-up cycles, as typically encountered in auxiliary power units (APU) applications. A promising performance - with a maximum power density (MPD) of 0.176 W cm -2 at 600 °C - was achieved using humidified hydrogen as fuel and air as the oxidant. The cell also showed excellent resistance to oxidation at 600 °C during fuel shutoff, with only a slight drop in performance after reintroduction of the fuel. The Cr and Mn species in the Hastelloy X alloy appeared to be preferentially oxidized while the oxidation of nickel in the metallic substrate was temporarily alleviated. In rapid start-up cycles with a heating rate of 60 °C min -1, noticeable performance deterioration took place in the first two thermal cycles, and then continued at a much slower rate in subsequent cycles. A postmortem analysis of the cell suggested that the degradation was mainly due to the mismatch of the thermal expansion coefficient across the cathode/electrolyte interface.

  18. Synthesis and Deposition of TiC-Fe Coatings by Oxygen-acetylene Flame Spraying

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A simpler and more convenient method for producing wear-resistant, TiC-reinforced coatings were investigated in this study. It consists of the simultaneous synthesis and deposition of TiC-Fe materials by oxyacetylene flame spraying.Solid reagents bound together to form a single particle are injected into the flame stream where an in-situ reaction occurs. The reaction products are propelled onto a substrate to form a coating. Microstructural analyses reveal that TiC and Fe are the dominant phases in the coatings. The reaction between Ti and C happens step by step along with the reactive spray powder flight, and TiC-Fe materials were mainly synthesized where the spray distance is 125~170 mm. The TiC-Fe coatings are composed of alternate TiC-rich and TiC-poor lamellae with different microhardness of 11.9~13.7 and 3.0~6.0 Gpa, respectively. Submicron and round TiC particles are dispersed within a ductile metal matrix. The peculiar microstructure is thought to be responsible for its good wear resistance, which is better nearly five times than WC-reinforced cermet coatings obtained by traditional oxyacetylene flame spray.

  19. Experimental studies of thermal and chemical interactions between oxide and silicide nuclear fuels with water

    Energy Technology Data Exchange (ETDEWEB)

    farahani, A.A.; Corradini, M.L. [Univ. of Wisconsi, Madison, WI (United States)

    1995-09-01

    Given some transient power/cooling mismatch is a nuclear reactor and its inability to establish the necessary core cooling, energetic fuel-coolant interactions (FCI`s commonly called `vapor explosions`) could occur as a result of the core melting and coolant contact. Although a large number of studies have been done on energetic FCI`s, very few experiments have been performed with the actual fuel materials postulated to be produced in severe accidents. Because of the scarcity of well-characterized FCI data for uranium allows in noncommercial reactors (cermet and silicide fuels), we have conducted a series of experiments to provide a data base for the foregoing materials. An existing 1-D shock-tube facility was modified to handle depleted radioactive materials (U{sub 3}O{sub 8}-Al, and U{sub 3}Si{sub 2}-Al). Our objectives have been to determine the effects of the initial fuel composition and temperature and the driving pressure (triggering) on the explosion work output, dynamic pressures, transient temperatures, and the hydrogen production. Experimental results indicate limited energetics, mainly thermal interactions, for these fuel materials as compared to aluminum where more chemical reactions occur between the molten aluminum and water.

  20. Effect of helium plasma gas flow rate on the properties of WC-12 wt.%Co coatings sprayed by atmospheric plasma

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2014-06-01

    Full Text Available The cermet coatings of WC-12wt.%Co are extensively used to improve the wear resistance of a wide range of technical components. This paper analyses the influence of the plasma gas flow of helium on the microstructure and mechanical properties of WC-12wt.%Co coatings deposited by plasma spraying at atmospheric pressure (APS. In order to obtain homogeneous and denser coatings, three different flows of He ( 8 l/min., 16 l/min. and 32 l/min were used in the research. With the application of He, coatings achieved higher values of hardness due to less degradation of the primary WC carbides. The main goal was to deposit dense and homogeneous layers of WC-12wt.%Co coatings with improved wear resistance for different applications. The test results of the microstructure of the layers were evaluated under a light microscope. The analysis of the microstructure and the mechanical properties of the deposited layers was made in accordance with the standard of Pratt-Whitney. The morphology of the powder particles and the microstructure of the best coating was examined on the SEM (scanning electron microscope. The evaluation of the mechanical properties of the layers was done by applying the HV0.3 method for microhardness testing and by applying tensile testing to test the bond strength. The research has shown that the flow of He plasma gas significantly affects the microstructure, the mechanical properties and the structure of WC-12 wt.%Co coatings.

  1. Characterization of Nanostructured WC-Co Deposited by Cold Spraying

    Science.gov (United States)

    Li, Chang-Jiu; Yang, Guan-Jun; Gao, Pei-Hu; Ma, Jian; Wang, Yu-Yue; Li, Cheng-Xin

    2007-12-01

    Nanostructured WC-Co coating was deposited by cold spraying using a nanostructured WC-12Co powder. The critical velocity for the particle to deposit was measured. The coating microstructure was characterized by X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy. The coating hardness was tested using a Vickers hardness tester. The deposition behavior of single WC-Co particle was examined. WC particle size was measured for comparison of deposit properties to that of sintered bulk. The result shows that the nanostructured WC-Co coating can be successfully deposited by cold spraying using nanostructured powders. The coating exhibited a dense microstructure with full retention of the original nanostructure in the powder to the coating. The test of microhardness of the coating yielded a value of over 1820 Hv0.3, which is comparable to that of sintered nanostructured WC-Co. The deposition behavior of WC-Co powders as superhard cermet materials in cold spraying and powder structure effects is discussed.

  2. WC-Co/Al Multilayer Coatings by Warm Spray Deposition

    Science.gov (United States)

    Watanabe, Makoto; Komatsu, Masayuki; Kuroda, Seiji

    2012-06-01

    WC-Co/aluminum multilayer coatings have been developed by using warm spray deposition to improve fracture toughness and damage tolerance of conventional WC-Co coatings and to investigate the effects of ductile layer addition on their fracture properties. Prior to depositing the multilayer coatings, the mechanical properties of three metal coatings of aluminum, copper, and titanium, which were deposited by warm spraying, were evaluated. The aluminum coating showed excellent ductility among them and was selected for use as ductile layers for the multilayer coatings. The fracture behavior of WC-Co/Al coatings was examined by the four-point bending test. The multilayer coatings did not break in a brittle manner after reaching maximum load, but exhibited a plateau as a result of the ductility of the aluminum layers. The fracture behavior was compared with the finite element analysis results, and they showed good agreement in a general trend. It has been concluded that ductile metal reinforcements, by advanced thermal spray techniques such as warm spray deposition, are very effective to enhance the toughness and damage tolerance of sprayed cermet coatings.

  3. The electrical conductivity of binary disordered systems, percolation clusters, fractals and related models

    Science.gov (United States)

    Clerc, J. P.; Giraud, G.; Laugier, J. M.; Luck, J. M.

    1990-05-01

    We review theoretical and experimental studies of the AC dielectric response of inhomogeneous materials, modelled as bond percolation networks, with a binary (conductor-dielectric) distribution of bond conductances. We first summarize the key results of percolation theory, concerning mostly geometrical and static (DC) transport properties, with emphasis on the scaling properties of the critical region around the percolation threshold. The frequency-dependent (AC) response of a general binary model is then studied by means of various approaches, including the effective-medium approximation, a scaling theory of the critical region, numerical computations using the transfer-matrix algorithm, and several exactly solvable deterministic fractal models. Transient regimes, related to singularities in the complex-frequency plane, are also investigated. Theoretical predictions are made more explicit in two specific cases, namely R-C and RL-C networks, and compared with a broad variety of experimental results, concerning, for example, granular composites, thin films, powders, microemulsions, cermets, porous ceramics and the viscoelastic properties of gels.

  4. An all-in-one flourite-based symmetrical solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Morales, Juan Carlos; Marrero-Lopez, David; Perez-Coll, Domingo; Pena-Martinez, Juan; Nunez, Pedro [Department of Inorganic Chemistry, University of La Laguna, Avda. Francisco Sanchez s/n, La Laguna, CP 38200 Tenerife (Spain); Canales-Vazquez, Jesus [Renewable Energy Research Institute, University of Castilla la Mancha, 02006 Albacete (Spain)

    2008-02-15

    A novel concept of solid oxide fuel cell (SOFC), the symmetrical SOFC, that uses simultaneously the same material as both anode and cathode has been investigated. Common materials typically used as anode components such as a combination of YSZ and CeO{sub 2} plus a noble metal may be considered good candidates for such a configuration at relatively high temperatures (i.e. above 900 C). These symmetrical electrodes exhibit enhanced electrochemical properties under both reducing and oxidising conditions, in part due to the catalytic properties of the noble metal used. In air the polarisation values are improved by a factor of four compared to electrodes without CeO{sub 2}, whereas under reducing conditions an improvement of two-three orders of magnitude has been observed. The best results correspond to cermets containing 50-60% of CeO{sub 2}. This simple combination allows the assembly of all-in-one fluorite-based symmetrical fuel cells (SFCs): YSZ-CeO{sub 2}/YSZ/YSZ-CeO{sub 2} plus a noble metal with good catalytic behaviour. Performances of 140 mW cm{sup -2} at 950 C were obtained when using H{sub 2} as fuel and thick YSZ electrolytes. Interesting performances of 500 mW cm{sup -2} are expected for thin YSZ electrolyte layer under identical experimental conditions. (author)

  5. Characterization of the Micro-Welding Process for Repair of Nickel Base Superalloys

    Science.gov (United States)

    Durocher, J.; Richards, N. L.

    2007-12-01

    Micro-welding is a low-heat input process whereby a metal or cermet, is deposited by the generation of a low-power arc between a consumable electrode and a substrate. The low-heat input of this process offers unique advantages over more common welding processes such as gas tungsten arc, plasma arc, laser, and electron beam welding. At present, the repair of turbine blades and vanes commonly involves gas tungsten arc welding and these components are susceptible to heat affected zone cracking during the weld repair process; vacuum brazing is also used but mainly on low-stress components such as stators. In this study, the low-heat input characteristic of micro-welding has been utilized to simulate repair of Inconel (Trade Mark of Special Metals) 625, Inconel 718, and Inconel 722 filler alloys to a cast Inconel 738 substrate. The effect of micro-welding process parameters on the deposition rate, coating quality, and substrate has been investigated.

  6. The Influence Of The Way Of Alumina Addition On Properties Improvement Of 3YSZ Material

    Directory of Open Access Journals (Sweden)

    Drożdż E.

    2015-06-01

    Full Text Available Yttria-stabilized zirconia (YSZ is the best known ceramic-oxide material employed as a component of either solid electrolyte or anode cermet material for intermediate solid oxide fuel cell (IT - SOFC. The properties of traditionally produced (by mechanical mixing of oxides Al2O3/3YSZ composite with the same composition materials obtained by citrate and impregnation methods and with properties of pure tetragonal zirconia (3YSZ were compared. The materials were characterised by X-ray diffraction, SEM observations with EDX analysis, density and impedance spectroscopy measurements. The results shown that Al2O3/3YSZ composites reveals higher conductivity than pure 3YSZ and that addition of alumina (regardless of methods improve electric properties of resulting materials. Taking into account application of this materials as anode in IT-SOFC the determined values of energy activation of conductivity and microstructural properties of composites show that materials obtained by citric method are the most promising.

  7. Compatibility between glass sealants and electrode materials of solid oxide fuel cells

    Institute of Scientific and Technical Information of China (English)

    PIAO Jinhua; SUN Kening; Chen Xinbing

    2008-01-01

    BaO-CaO-Al2O3-SiO2-La2O3-B2O3 system glass materials were investigated as sealants for a solid oxide fuel cell (SOFC).The transition temperature (Tg) and the crystal temperature (Td) values decrease greatly with the increase of BaCO3 content when the other components do not change.For the thermal expansion coefficient (TEC) values,the trend is inverse.The sealant has superior thermal expansion coefficient matching properties with La(Sr)MnO3 (LSM) cathode,La(Sr)FeO3 (LSF) cathode,Ni-LDC (La doped CeO2) anode,and Ni-YSZ (yttria stabilized zirconia) cermet anode.The sealant also has superior stability,compatibility,and good bonding characteristic with these electrode materials at 800-900℃.The results indicate that the aluminosilicate system glass sealant possesses superior compatibility with electrode materials of the solid oxide fuel cell.

  8. Coke-free direct formic acid solid oxide fuel cells operating at intermediate temperatures

    Science.gov (United States)

    Chen, Yubo; Su, Chao; Zheng, Tao; Shao, Zongping

    2012-12-01

    Formic acid is investigated as a fuel for Solid Oxide Fuel Cells (SOFCs) for the first time. Thermodynamic calculations demonstrate that carbon deposition is avoidable above 600 °C. The carbon deposition properties are also investigated experimentally by first treating a nickel plus yttria-stabilized zirconia (Ni-YSZ) anode material in particle form under a formic acid-containing atmosphere for a limited time at 500-800 °C and then analyzing the particles by O2-TPO. This analysis confirms that carbon deposition on Ni-YSZ is weak above 600 °C. We further treat half-cells composed of YSZ electrolyte and Ni-YSZ anode under formic acid-containing atmosphere at 600, 700 and 800 °C; the anodes maintain their original geometric shape and microstructure and show no obvious weight gain. It suggests that formic acid can be directly fed into SOFCs constructed with conventional nickel-based cermet anodes. I-V tests show that the cell delivers a promising peak power density of 571 mW cm-2 at 800 °C. In addition, the cells also show good performance stability. The results indicate that formic acid is highly promising as a direct fuel for SOFCs without the need for cell material modifications.

  9. Reprocessability of molybdenum and magnesia based inert matrix fuels

    Directory of Open Access Journals (Sweden)

    Ebert Elena L.

    2015-12-01

    Full Text Available This work focuses on the reprocessability of metallic 92Mo and ceramic MgO, which is under investigation for (Pu,MA-oxide (MA = minor actinide fuel within a metallic 92Mo matrix (CERMET and a ceramic MgO matrix (CERCER. Magnesium oxide and molybdenum reference samples have been fabricated by powder metallurgy. The dissolution of the matrices was studied as a function of HNO3 concentration (1-7 mol/L and temperature (25-90°C. The rate of dissolution of magnesium oxide and metallic molybdenum increased with temperature. While the MgO rate was independent of the acid concentration (1-7 mol/L, the rate of dissolution of Mo increased with acid concentration. However, the dissolution of Mo at high temperatures and nitric acid concentrations was accompanied by precipitation of MoO3. The extraction of uranium, americium, and europium in the presence of macro amounts of Mo and Mg was studied by three different extraction agents: tri-n-butylphosphate (TBP, N,Nʹ-dimethyl-N,Nʹ-dioctylhexylethoxymalonamide (DMDOHEMA, and N,N,N’,N’- -tetraoctyldiglycolamide (TODGA. With TBP no extraction of Mo and Mg occurred. Both matrix materials are partly extracted by DMDOHEMA. Magnesium is not extracted by TODGA (D < 0.1, but a weak extraction of Mo is observed at low Mo concentration.

  10. Mechanical property changes in HVOF sprayed nano-structured WC-17wt.%Ni (80/20)Cr coating with varying substrate roughness

    International Nuclear Information System (INIS)

    Thermally sprayed coatings developed by use of high velocity oxy-fuel (HVOF) process are known for their superior wear characteristics. In many industrial applications, new parts as well as repaired and refurbished parts coated with WC-Co microstructured coatings have shown enhanced erosion-corrosion and abrasive resistant properties when compared with other surface modification technologies such as chrome replacement, fusion welding, and cladding. This research has been further directed towards the development of HVOF technique to deposit dense nanostructured ceramic-metallic composites. The mechanism of plastic deformation, which determines the strength and ductility of materials, in nanostructured materials are different, thereby leading to novel mechanical properties. Various parameters can influence these properties, but the substrate surface preparation by grit blasting before thermal spraying is one critical parameter. The grit blasting process generates a surface roughness, which ensures mechanical anchoring between the coating and the substrate surface. In this work, the sliding wear behavior and microhardness of WC-17wt. percentage Ni(80/20)Cr cermet coatings deposited onto carbon steel substrates are examined as a function of three different surface roughness values under different loads. The results show that as-prepared surface with different blasting profiles have a direct influence on the surface roughness and wear performance of the coatings. The sliding wear resistance of the coatings increased as the substrate surface roughness increased. The wear depth decreased with increasing surface roughness. (author)

  11. Mechanical property changes in HVOF sprayed nano-structured WC-17wt.%Ni(80/20)Cr coating with varying substrate roughness

    International Nuclear Information System (INIS)

    Thermally sprayed coatings developed by use of high velocity oxy-fuel (HVOF) process are known for their superior wear characteristics. In many industrial applications, new parts as well as repaired and refurbished parts coated with WC-Co microstructured coatings have shown enhanced erosion-corrosion and abrasive resistant properties when compared with other surface modification technologies such as chrome replacement, fusion welding, and cladding. This research has been further directed towards the development of HVOF technique to deposit dense nanostructured ceramic-metallic composites. The mechanism of plastic deformation, which determines the strength and ductility of materials, in nanostructured materials are different, thereby leading to novel mechanical properties. Various parameters can influence these properties, but the substrate surface preparation by grit blasting before thermal spraying is one critical parameter. The grit blasting process generates a surface roughness, which ensures mechanical anchoring between the coating and the substrate surface. In this work, the sliding wear behavior and microhardness of WC-17wt.%Ni(80/20)Cr cermet coatings deposited onto carbon steel substrates are examined as a function of three different surface roughness values under different loads. The results show that as-prepared surface with different blasting profiles have a direct influence on the surface roughness and wear performance of the coatings. The sliding wear resistance of the coatings increased as the substrate surface roughness increased. The wear depth decreased with increasing surface roughness

  12. SUSEE: A Compact, Lightweight Space Nuclear Power System Using Present Water Reactor Technology

    Science.gov (United States)

    Maise, George; Powell, James; Paniagua, John

    2006-01-01

    The SUSEE space reactor system uses existing nuclear fuels and the standard steam cycle to generate electrical and thermal power for a wide range of in-space and surface applications, including manned bases, sub-surface mobile probes to explore thick ice deposits on Mars and the Jovian moons, and mobile rovers. SUSEE cycle efficiency, thermal to electric, ranges from ~20 to 24%, depending on operating parameters. Rejection of waste heat is by a lightweight condensing radiator that can be launched as a compact rolled-up package and deployed into flat panels when appropriate. The 50 centimeter diameter SUSEE reactor can provide power over the range of 10 kW(e) to 1 MW(e) for a period of 10 years. Higher power outputs are possible using slightly larger reactors. System specific weight (reactor, turbine, generator, piping, and radiator is ~3 kg/kW(e). Two SUSEE reactor options are described, based on the existing Zr/O2 cermet and the UH3/ZrH2 TRIGA nuclear fuels.

  13. A review and discussion of candidate ceramics for immobilization of high-level fuel reprocessing wastes

    International Nuclear Information System (INIS)

    This review discusses and attempts to evaluate 11 of the leading ceramic processes for hosting the high-level and high-level plus medium-level wastes which would arise from the reprocessing of used UO2, (Th,Pu)O2 and (Th,U)O2 fuels. The wasteform materials considered include glass ceramics, supercalcine ceramics, SYNROC ceramics, 'stuffed glass', titanate ceramics, cermets, clay ceramics, cement-based materials and multibarrier wasteforms. Although no attempt has been made to rank these candidates in order of superiority, the conclusion is drawn that, of the materials proposed so far, a glass ceramic appears to be best suited to the Canadian program, taking into account durability in the potential environment of a flooded vault, ability to withstand radiation and transmutation damage without serious loss of durability, ability to accommodate variable waste compositions, and ease of processing and quality control. This conclusion does not necessarily apply to other national waste management programs. However, many of the points raised might be included in any critical assessment of alternative wasteform materials

  14. Performance Factors and Sulfur Tolerance of Metal Supported Solid Oxide Fuel Cells with Nanostructured Ni:GDC Infiltrated Anodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Sudireddy, Bhaskar Reddy; Hagen, Anke;

    2015-01-01

    Two metal supported solid oxide fuel cells (active area 16 cm2) with nanostructured Ni:GDC infiltrated anodes, but different anode and support microstructures were studied in respect to sulfur tolerance at the aimed operating temperature of 650ºC. The studied MS-SOFCs are based on ferretic stainl...... anode is significantly more sulfur tolerant than the conventional Ni/YSZ cermet anode. © 2015 ECS - The Electrochemical Society......Two metal supported solid oxide fuel cells (active area 16 cm2) with nanostructured Ni:GDC infiltrated anodes, but different anode and support microstructures were studied in respect to sulfur tolerance at the aimed operating temperature of 650ºC. The studied MS-SOFCs are based on ferretic...... stainless steel (FeCr) and showed excellent performance characteristics at 650ºC with area specific resistances (ASR) of 0.35 Ωcm2 and 0.7 Ωcm2 respectively. The sulfur tolerance testing was performed by addition/removal of 2, 5, and 10 ppm H2S in hydrogen based fuel under galvanostatic operation...

  15. Nanostructured Cu-CGO anodes fabricated using a microwave-assisted glycine-nitrate process

    Science.gov (United States)

    Shaikh, Shabana P. S.; Somalu, Mahendra R.; Muchtar, Andanastuti

    2016-11-01

    This work reports a study of nanostructured copper-doped gadolinium cermet (Cu-CGO) composite anodes prepared via conventional synthesis (CS) and microwave-synthesis (MS) involving the glycine-nitrate process (GNP). A detailed investigation on the mechanical properties, electrical conductivity and electrochemical performance of prepared Cu0.5(Ce0.9Gd0.1)0.5O2-δ anodes is included. The prepared samples were characterized by techniques, such as XRD, EDX, SEM and electrical characterizations. After reduction in 10% H2 and 90% N2, the DC conductivities of the Cu-CGO anodes prepared via CS-GNP and MS-GNP are found to be 5.43×103 and 1.09×104 S cm-1 at 700 °C, respectively. The electrochemical performances of the spin-coated anode symmetrical cells sintered at 700 °C are evaluated at cell operating temperatures of 600, 700 and 800 °C. The lowest area specific resistance (ASR) values for the Cu-CGO/CGO/Cu-CGO symmetrical cells prepared via the MS-GNP route at operating temperatures of 600, 700 and 800 °C are found to be 0.34, 0.71 and 1.10 Ω cm2, respectively. The as-prepared (via MS-GNP) Cu-CGO anode exhibits excellent electrical and electrochemical performance consistent with the uniform nanostructured morphology compared with the anode prepared via CS-GNP.

  16. Negative permittivity behavior in Fe50Ni50/Al2O3 magnetic composite near percolation threshold

    International Nuclear Information System (INIS)

    The physical properties of conductor–insulator composites often take dramatic changes near the percolation threshold (fc), leading to interesting applications, such as double negative material. This phenomenon also will be enlarged by increasing the differences between the properties of the constitutive phases. In this paper, the Fe50Ni50/Al2O3 magnetic cermets with different Fe50Ni50 volume contents (10%, 20%, 30%, 40%) were prepared via hot-pressing sintering. The permittivity of Fe50Ni50/Al2O3 composites has been studied in the radio frequency range. The results indicate that when the Fe50Ni50 content is below fc, the reactance of the composites takes a negative value, which indicates a capacitive character. The metallic Fe50Ni50 grains are isolated in the insulating ceramic matrix, leading to an insulator-like dielectric property. When the volume fraction of Fe50Ni50 reaches 40% which is above fc, the composites manifest an inductive character. In this case, the negative permittivity has been obtained over the whole test frequency range due to the percolation phenomenon, which makes Fe50Ni50/Al2O3 composites as promising candidates for double negative materials. - Highlights: • The negative permittivity in Fe50Ni50/Al2O3 composites was achieved. • The percolation phenomenon was observed when the volume fraction of Fe50Ni50 was between 30% and 40%. • The frequency range that the negative permittivity could be generated is tunable

  17. Study on the influences of reduction temperature on nickel-yttria-stabilized zirconia solid oxide fuel cell anode using nickel oxide-film electrode

    Science.gov (United States)

    Jiao, Zhenjun; Ueno, Ai; Suzuki, Yuji; Shikazono, Naoki

    2016-10-01

    In this study, the reduction processes of nickel oxide at different temperatures were investigated using nickel-film anode to study the influences of reduction temperature on the initial performances and stability of nickel-yttria-stabilized zirconia anode. Compared to conventional nickel-yttria-stabilized zirconia composite cermet anode, nickel-film anode has the advantage of direct observation at nickel-yttria-stabilized zirconia interface. The microstructural changes were characterized by scanning electron microscopy. The reduction process of nickel oxide is considered to be determined by the competition between the mechanisms of volume reduction in nickel oxide-nickel reaction and nickel sintering. Electrochemical impedance spectroscopy was applied to analyze the time variation of the nickel-film anode electrochemical characteristics. The anode performances and microstructural changes before and after 100 hours discharging and open circuit operations were analyzed. The degradation of nickel-film anode is considered to be determined by the co-effect between the nickel sintering and the change of nickel-yttria-stabilized zirconia interface bonding condition.

  18. Densification of porous bodies in a granular pressure-transmitting medium

    International Nuclear Information System (INIS)

    Densification is a critical step in the manufacture of near-net-shaped components via powder processing. A non-isostatic stress state will in general result in shape distortion in addition to densification. In the quasi-isostatic pressing (QIP) process the green body is placed into a granular pressure-transmitting medium (i.e. PTM), which is itself contained in a rigid die. Upon the application of a uniaxial load, the PTM redistributes the tractions on the green body, thereby creating a stress state that is quasi-isostatic. The character of the deformation of the PTM is studied using model experiments on pressing of the PTM in a rigid die and a scanning electron microscopy analysis of the PTM powder. An important problem of the optimization of the PTM chemical composition enabling the maximum densification of a porous specimen with the minimum possible shape distortion is solved. The results of modeling agree satisfactorily with the experimental data on cold QIPing Ti and Ni powder samples and hot QIPing TiC-TiNi cermet composites

  19. Research on Calcium Doped Ceria Used in Intermediate-Temperature SOFCs Anodes

    Institute of Scientific and Technical Information of China (English)

    Yin Yanhong; Li Shaoyu; Zhu Wei; Xia Changrong; Meng Guangyao

    2005-01-01

    As a mixed ion-electronic conductor, doped ceria, especially rare earth doped ceria, were used as anodes or components of anodes in SOFCs. In this work, calcium doped ceria (CCO) was synthesized to be used in intermediate-temperature SOFCs (IT-SOFCs) anodes in order to reduce the cost of anode-supported SOFCs. Electrical conductivity of 20% calcium doped ceria (20CCO) reached 0.209 S·cm-1 in hydrogen at 850 ℃, and 0.041 S·cm-1 in air at 800 ℃, which is about 0.04 S·cm-1 lower than that of conventional samaria-doped ceria (0.079 S·cm-1). Electrochemical performance of Ni-20CCO cermet as anode was investigated using a fuel cell with 35 μm-thick SDC electrolyte and Sm0.5Sr0.5Co-SDC cathode. Maximum power density was 623 mW·cm-2 under humidified (3% H2O) hydrogen at 650 ℃, inferring high catalytic activity of the Ni-20CCO anode.

  20. Realisation of an anode supported planar SOFC system

    Energy Technology Data Exchange (ETDEWEB)

    Buchkremer, H.P.; Stoever, D. [Institut fuer Werkstoffe der Energietechnik, Juelich (Germany); Diekmann, U. [Zentralabteilung Technologie, Juelich (Germany)] [and others

    1996-12-31

    Lowering the operating temperature of S0FCs to below 800{degrees}C potentially lowers production costs of a SOFC system because of a less expensive periphery and is able to guarantee sufficient life time of the stack. One way of achieving lower operating temperatures is the development of new high conductive electrolyte materials. The other way, still based on state-of-the-art material, i.e. yttria-stabilized zirconia (YSZ) electrolyte, is the development of a thin film electrolyte concept. In the Forschungszentrum Julich a program was started to produce a supported planar SOFC with an YSZ electrolyte thickness between 10 to 20 put. One of the electrodes, i.e. the anode, was used as support, in order not to increase the number of components in the SOFC. The high electronic conductivity of the anode-cermet allows the use of relatively thick layers without increasing the cell resistance. An additional advantage of the supported planar concept is the possibility to produce single cells larger than 10 x 10 cm x cm, that is with an effective electrode cross area of several hundred cm{sup 2}.

  1. The Evaluations of Hydrogen Permeation and Life Cycle Assessment on Nanocrystallined TiN-BCY Hydrogen Membrane.

    Science.gov (United States)

    Lee, Soo-Sun; Hong, Tae-Whan

    2016-02-01

    Recently, Membrane technologies are used for the separation of mixtures in various industries. The promising method to reduce the CO2 emission and production of H2 from the coal based power plants is membrane separation with polymer, metal, ceramic and cermet materials. In this study, TiN ceramic material was selected, that is much less expensive than Pd. Also it has resistance to acids and chemically steady. Yttrium doped barium cerate (BCY) is a proton conductor. This perovskite exhibit both high proton conductivity and thermodynamic stability. But its chemical stability is very low under real operating environments. Thus, TiN-BCY may provide'a new membrane material for application. Life cycle assessment (LCA) based on fabrication of membrane and it was carried out to evaluate the energy demand and environmental impact. The analysis is performed according to the recommendations of ISO norms 14040 and obtained using the Gabi 6 software. This LCA will contribute to optimizing the eco-design, reducing the energy consumption and pollutant emissions during the eco-profiles of the TiN-BCY membrane. PMID:27433683

  2. Effect of sintering atmosphere on composition and properties of NiFe2O4 ceramic

    Institute of Scientific and Technical Information of China (English)

    田忠良; 张腾; 刘恺; 赖延清; 李劼

    2015-01-01

    NiFe2O4 ceramics were prepared in different sintering atmospheres. The phase compositions, microstructures and mechanical properties were studied. The results show that the stoichiometric compound NiFe2O4 cannot be obtained in vacuum or atmospheres with oxygen contents of 2×10−5, 2×10−4 and 2×10−3, respectively. All the samples sintered in above-mentioned atmospheres contain phases of NiFe2O4 and NiO. With increasing oxygen content, NiFe2O4 content in the ceramic increases, while NiO content appears a contrary trend. In vacuum, NiFe2O4 ceramic has average grain size of 3.94μm, and bending strength of 85.12 MPa. The changes of the phase composition and mechanical properties of NiFe2O4 based cermets are mainly caused by the alteration of their properties of NiFe2O4 ceramic.

  3. `Research and Development of Technology for Controlling the Structure of Multiple-Function Component,` local research and development of important technology for fiscal 1997. 2. Technological development of advanced surface treatment for methane-powered aircraft engine components (Laser-aided advanced treatment system (technology)); 1997 nendo juyo chiiki gijutsu kenkyu kaihatsu `fukugo kino buzai kozo seigyo gijutsu no kenkyu kaihatsu`. 2. Methane nenryo kokukiyo engine buzai no kodo hyomen kako gijutsu kaihatsu (laser oyo senshin kako system gijutsu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    Surface reforming technologies, such as laser-aided Ti alloying, are studied for developing erosion-resistant materials for the fore section of a methane-fueled aircraft engine. In the formation of intermetallic compound film, the laser plasma hybrid spraying is applied for the formation of a film which is 100-400 times higher than Ti6Al4V in terms of resistance to erosion. For the quantitative evaluation of bond strength, a boundary shear testing jig is built. When the laser irradiating conditions are optimized, the boundary shear strength is elevated to 150-230MPa. NiAl film is studied for realizing resistance to high-temperature oxidation, and then a perfect NiAl film is obtained, which is done by use of a mechanical alloying powder mixed on the atomic level. In the manufacture of ceramic cermet film, a powder is studied, in which powder SiC and Al2O3, excellent in high-temperature oxidation characteristics and fracture toughness, are the parent materials which are coated by NiCr. It is found that an excellent oxidation-resistant film will be manufactured by use of this powder. 40 refs., 132 figs., 12 tabs.

  4. Californium-252 neutron sources

    International Nuclear Information System (INIS)

    Major production programs for the Savannah River reactors and the High Flux Isotopes Reactor at Oak Ridge have made 252Cf one of the most available and, at the USAEC's sales price of $10/μg, one of the least-expensive isotopic neutron sources. Reactor production has totaled approximately 2 g, and, based on expected demand, an additional 10 g will be produced in the next decade. The approximately 800 mg chemically separated to date has been used to prepare over 600 neutron sources. Most, about 500, have been medical sources containing 1 to 5 μg of 252Cf plated in needles for experimental cancer therapy studies. The remainder have generally been point sources containing 10 μg to 12 mg of oxide for activation, well logging, or radiography uses. Bulk sources have also been supplied to the commercial encapsulators. The latest development has been the production of 252Cf cermet wire which can be cut into almost contamination-free lengths of the desired 252Cf content. Casks are available for transport of sources up to 50 mg. Subcritical assemblies have been developed to multiply the source neutrons by a factor of 10 to 40, and collimators and thermalizers have also been extensively developed to shape the neutron flux and energy distributions for special applications. (U.S.)

  5. Basic concept for an accelerator-driven subcritical system to be used as a long-pulse neutron source for Condensed Matter research

    Energy Technology Data Exchange (ETDEWEB)

    Vivanco, R., E-mail: raul.vivanco.sanchez@gmail.com [ESS-BILBAO, Parque Tecnológico Bizkaia, Laida Bidea, Edificio 207 B Planta Baja, 48160 Derio (Spain); Instituto de Fusión Nuclear - UPM, ETS Ingenieros Industriales, C/ José Gutiérrez Abascal, 2, 28006 Madrid Spain (Spain); Ghiglino, A.; Vicente, J.P. de; Sordo, F.; Terrón, S.; Magán, M. [ESS-BILBAO, Parque Tecnológico Bizkaia, Laida Bidea, Edificio 207 B Planta Baja, 48160 Derio (Spain); Instituto de Fusión Nuclear - UPM, ETS Ingenieros Industriales, C/ José Gutiérrez Abascal, 2, 28006 Madrid Spain (Spain); Perlado, J.M. [Instituto de Fusión Nuclear - UPM, ETS Ingenieros Industriales, C/ José Gutiérrez Abascal, 2, 28006 Madrid Spain (Spain); Bermejo, F.J. [Instituto de Estructura de la Materia, IEM-CSIC, Consejo Superior de Investigaciones Científicas, Serrano 123, 28006 Madrid (Spain)

    2014-12-11

    A model for an accelerator-driven subcritical system to be operated as a source of cold neutrons for Condensed Matter research is developed at the conceptual level. Its baseline layout relies upon proven accelerator, spalattion target and fuel array technologies, and consists in a proton accelerator able to deliver some 67.5 mA of proton beam with kinetic energy 0.6 GeV, a pulse length of 2.86 ms, and repetition rate of 14 Hz. The particle beam hits a target of conventional design that is surrounded by a multiplicative core made of fissile/fertile material, composed by a subcritical array of fuel bars made of aluminium Cermet cooled by light water poisoned with boric acid. Relatively low enriched uranium is chosen as fissile material. An optimisation of several parameters is carried out, using as components of the objective function several characteristics pertaining the cold neutron pulse. The results show that the optimal device will deliver up to 80% of the cold neutron flux expected for some of the ongoing projects using a significantly lower proton beam power than that managed in such projects. The total power developed within the core rises up to 22.8 MW, and the criticality range shifts to a final k{sub eff} value of around 0.9 after the 50 days cycle.

  6. Post-treatment of Plasma-Sprayed Cr2O3 with Methane-Containing Gas for Conversion to Binder-Free Cr3C2

    Science.gov (United States)

    Brupbacher, Michael C.; Zhang, Dajie; Buchta, William M.; Rhim, Yo-Rhin; Nagle, Dennis C.; Spicer, James B.

    2015-12-01

    In most applications, the performance of thermally sprayed Cr3C2-NiCr cermet coatings is known to be adversely affected by the presence of the NiCr binder phase. A processing technique for the rapid synthesis of Cr3C2 on industrial-scale components could improve the functionality of these coatings by eliminating the metallic binder phase. To form a thick, continuous surface layer of adherent, binder-free Cr3C2, the reduction of plasma-sprayed Cr2O3 with methane-containing gas was investigated. Conversion of the plasma-sprayed Cr2O3 to carbide resulted in a significant increase in coating porosity, yielding a highly microporous Cr3C2 surface layer. The physical characteristics of the reduction process appear to be dependent on the coating defect structure at the reduction temperature. Phase morphology and porosity evolution throughout the reduction process were qualitatively examined using x-ray diffraction and scanning electron microscopy. The utility of the resultant Cr3C2 coating is discussed with respect to these microstructural characterizations and microindentation hardness measurements.

  7. Efecto del volumen de metal cortado y de la velocidad de corte en el desgaste de la herramienta durante el torneado de alta velocidad del acero AISI 1045

    Directory of Open Access Journals (Sweden)

    Luis W. Hernández González

    2011-01-01

    Full Text Available En este trabajo se aborda el estudio experimental del efecto del volumen de metal cortado y de la velocidad de corte en el desgaste del flanco de dos insertos de carburos recubiertos y un cermet, durante el torneado de acabado en seco del acero AISI 1045 a velocidades de corte moderada, intermedia y alta. Los resultados fueron comparados utilizando la dimensión volumétrica de la vida útil de la herramienta, el análisis de varianza y el análisis de regresión lineal para describir la relación entre el desgaste y el volumen removido, según las ecuaciones del modelo ajustado. La investigación mostró un efecto significativo de la velocidad de corte y del volumen cortado en el desgaste del flanco, pues se logró el mejor desempeño para la alta velocidad con el carburo recubierto con tres capas y el peor funcionamiento con el carburo recubierto con dos capas.

  8. Nuclear Thermal Rocket Simulation in NPSS

    Science.gov (United States)

    Belair, Michael L.; Sarmiento, Charles J.; Lavelle, Thomas M.

    2013-01-01

    Four nuclear thermal rocket (NTR) models have been created in the Numerical Propulsion System Simulation (NPSS) framework. The models are divided into two categories. One set is based upon the ZrC-graphite composite fuel element and tie tube-style reactor developed during the Nuclear Engine for Rocket Vehicle Application (NERVA) project in the late 1960s and early 1970s. The other reactor set is based upon a W-UO2 ceramic-metallic (CERMET) fuel element. Within each category, a small and a large thrust engine are modeled. The small engine models utilize RL-10 turbomachinery performance maps and have a thrust of approximately 33.4 kN (7,500 lbf ). The large engine models utilize scaled RL-60 turbomachinery performance maps and have a thrust of approximately 111.2 kN (25,000 lbf ). Power deposition profiles for each reactor were obtained from a detailed Monte Carlo N-Particle (MCNP5) model of the reactor cores. Performance factors such as thermodynamic state points, thrust, specific impulse, reactor power level, and maximum fuel temperature are analyzed for each engine design.

  9. Precracking and interfacial delamination in a bi-material structure: Static and dynamic loadings

    Institute of Scientific and Technical Information of China (English)

    Barbara Gambin; Jordanka Ivanova; Varbinka Valeva; Gergana Nikolova

    2011-01-01

    The behavior of a precracked bi-material structure interface under given static and dynamic axial loading is an interest object in the present paper. Firstly, it is shown that the shear-lag model is a proper tool to analyze a delamination process in a precracked bi-material structure undergoing static loading. Secondly, the “shear-lag model” is applied to the structure under dynamic loading. To solve the problem for an interface delamination of the structure and to determine the debond length along the interface, our own 2D boundary element method (BEM) code is proposed in the case of static loading, and the shear-lag model together with the Laplace transforms and half-analytical calculations are used in the case of dynamic loading. The interface layer is assumed as a very thin plate compared with the other two. The parametric (geometric and elastic) analysis of the debond length and interface shear stress is done.The results from the 2D BEM code proved the validity of analytical solutions to the shear-lag model. In the dynamic case, the influence of loading characteristics, i.e., frequencies and amplitude fluctuations on the shear stress and the value of debond length for an interval of time, is discussed.The analysis of the obtained results is illustrated by an example of the modern ceramic-metal composite, namely cermet,and depicted in figures.

  10. Electro-spark deposition technology

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.N. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-12-01

    Electro-Spark Deposition (ESD) is a micro-welding process that uses short duration, high-current electrical pulses to deposit or alloy a consumable electrode material onto a metallic substrate. The ESD process was developed to produce coatings for use in severe environments where most other coatings fail. Because of the exceptional damage resistance of these coatings, and the versatility of the process to apply a wide variety of alloys, intermetallics, and cermets to metal surfaces, the ESD process has been designated critical to the life and economy of the advanced fossil energy systems as the higher temperatures and corrosive environments exceed the limits of known structural materials to accommodate the service conditions. Developments include producing iron aluminide-based coatings with triple the corrosion resistance of the best previous Fe{sub 3}Al coatings, coatings with refractory metal diffusion barriers and multi layer coatings for achieving functionally gradient properties between the substrate and the surface. A new development is the demonstration of advanced aluminide-based ESD coatings for erosion and wear applications. One of the most significant breakthroughs to occur in the last dozen years is the discovery of a process regime that yields an order of magnitude increase in deposition rates and achievable coating thicknesses. Achieving this regime has required the development of advanced ESD electronic capabilities. Development is now focused on further improvements in deposition rates, system reliability when operating at process extremes, and economic competitiveness.

  11. Energy Efficient Aluminum Production - Pilot-Scale Cell Tests - Final Report for Phase I and Phase II

    Energy Technology Data Exchange (ETDEWEB)

    R. A. Christini

    1999-12-30

    A cermet anode that produces oxygen and a cathode material that is wetted by aluminum can provide a dimensionally stable inter-electrode distance in the Hall-Heroult cell. This can be used to greatly improve the energy and/or productivity efficiencies. The concept, which was developed and tested, uses a system of vertically interleaved anodes and cathodes. The major advantage of this concept is the significant increase in electrochemical surface area compared to a horizontal orientation of anode and cathode that is presently used in the Hall-Heroult process. This creates an additional advantage for energy reduction of 1.3 kWh/lb or a 20% productivity improvement. The voltages obtained in an optimized cell test met the energy objectives of the project for at least two weeks. An acceptable current efficiency was never proven, however, during either pilot scale or bench scale tests with the vertical plate configuration. This must be done before a vertical cell can be considered viab le. Anode corrosion rate must be reduced by at least a factor of three in order to produce commercial purity aluminum. It is recommended that extensive theoretical and bench scale investigations be done to improve anode materials and to demonstrate acceptable current efficiencies in a vertical plate cell before pilot scale work is continued.

  12. Electro-spark deposited coatings for protection of materials

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.N. [Battelle Pacific Northwest Lab., Richland, WA (United States)

    1995-08-01

    Electro-Spark Deposition (ESD) is a micro-welding process that uses short duration, high-current electrical pulses to deposit or alloy a consumable electrode material onto a metallic substrate. The coating is fused (metallurgically bonded) to the substrate with such a low total heat input that the bulk substrate material remains at or near ambient temperature. Rapid solidification of the deposit typically results in an extremely fine-grained deposit that may be amorphous for some materials. Nearly any electrically conductive metal, alloy or cermet can be applied to metallic substrates. The ESD process allows multi-layer coatings to be built-up using different materials to create graded structures or surface compositions that would be difficult to achieve by other means. A series of iron-aluminide coatings based on Fe{sub 3}Al and FeAl in combination with refractory metal diffusion-barrier coatings and supplementary additions of other elements are in corrosion testing at ANL. The most recent FeAl coatings are showing a factor of three better corrosion performance than the best previous coatings. Technology transfer activities are a significant portion of the ESD program effort. Notable successes now include the start-up of a new business to commercialize the ESD technology, major new applications in gas turbine engines and steam turbine blade coatings, and in military, medical, metal-working, and recreational equipment applications.

  13. Application of High Temperature Corrosion-Resistant Materials and Coatings Under Severe Corrosive Environment in Waste-to-Energy Boilers

    Science.gov (United States)

    Kawahara, Yuuzou

    2007-06-01

    Corrosion-resistant materials (CRMs) and coatings are key technologies to increase power generation efficiency and reduce maintenance in waste-to-energy (WTE) plants. Corrosion environment became severe as steam temperatures have increased. The steam condition of more than 400 °C/3.9 MPa became possible in WTE boilers by using highly durable corrosion-resistant coatings, such as thermal spray of Al/80Ni20Cr alloy, HVOF-sprayed NiCrSiB alloy, Alloy 625 weld overlay for waterwall tubes and also superheater tubes. Also, the use of 310S type stainless steels and high Cr-high Mo-Ni base and high Si-Cr-Ni-Fe alloys have progressed because of a better understanding of corrosion mechanisms. Furthermore, high durability coatings using cermet and ceramic materials were applied to high temperature superheaters. This paper describes the major developments and the application of CRMs and coating technologies in the last 30 years in WTE plants, the corrosion mechanisms of alloys, the deterioration mechanisms of spray coating layers, and future subjects for the development of corrosion-resistant materials and coatings.

  14. Preparation and characterization of IrO{sub 2}-YSZ nanocomposite electrodes by MOCVD

    Energy Technology Data Exchange (ETDEWEB)

    Torres-Huerta, A.M. [Instituto Politecnico Nacional, Departamento de Metalurgia y Materiales, A.P. 75-874, 07300 Mexico (Mexico); Universidad Nacional Autonoma de Mexico, Instituto de Investigacion en Materiales, Circuito Exterior s/n, Ciudad Universitaria, A.P. 70-360, Del. Coyoacan, C.P. 04510 Mexico (Mexico); Vargas-Garcia, J.R. [Instituto Politecnico Nacional, Departamento de Metalurgia y Materiales, A.P. 75-874, 07300 Mexico (Mexico); Dominguez-Crespo, M.A. [Instituto Politecnico Nacional, Grupo de Ingenieria en Procesamiento de Materiales CICATA-IPN, Unidad Altamira. Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C.P. 89600. Altamira, Tamps. (Mexico)

    2007-12-15

    The electrochemical performance of IrO{sub 2}/yttria stabilized zirconia (YSZ) cermet cathodes for solid oxide fuel cells was experimentally evaluated in relation to their microstructure. Noble metal films were prepared by MOCVD using metal-acetylacetonate precursors which were mixed and evaporated together (493 K) to achieve codeposition. The effects of experimental conditions on deposition rates, composition and microstructure were studied, and the optimum conditions were determined. The growth of the films was columnar and layered in structure, with porous morphology. TEM observations revealed that the IrO{sub 2}-YSZ composites are constituted by single-phase particles, between 4 and 10 nm in size, with an excellent composite distribution. The cathode-related polarization resistance, Rp, was measured by impedance spectroscopy and found to be in the range of 21-968 {omega} cm{sup 2} under the experimental conditions (573-873 K). IrO{sub 2}-YSZ electrodes undergo structural and/or morphological changes caused by cathodic polarization and high temperature (873 K). However, this behavior could contribute to the improvement of the electrochemical performance of the electrode. IrO{sub 2}-YSZ films displayed superior electrochemical properties as electrodes to zirconia electrolytes than that exhibited for the Pt-C and conventional Pt paste electrodes. (author)

  15. Catalytic modification of conventional SOFC anodes with a view to reducing their activity for direct internal reforming of natural gas

    Energy Technology Data Exchange (ETDEWEB)

    Boder, M.; Dittmeyer, R. [Research Group Technical Chemistry, Karl-Winnacker-Institut, DECHEMA e.V., Theodor-Heuss-Allee 25, D-60486 Frankfurt (Germany)

    2006-04-18

    When using natural gas as fuel for the solid oxide fuel cell (SOFC), direct internal reforming lowers the requirement for cell cooling and, theoretically, offers advantages with respect to capital cost and efficiency. The high metal content of a nickel/zirconia anode and the high temperature, however, cause the endothermic reforming reaction to take place very fast. The resulting drop of temperature at the inlet produces thermal stresses, which may lower the system efficiency and limit the stack lifetime. To reduce the reforming rate without lowering the electrochemical activity of the cell, a wet impregnation procedure for modifying conventional cermets by coverage with a less active metal was developed. As the coating material copper was chosen. Copper is affordable, catalytically inert for the reforming reaction and exhibits excellent electronic conductivity. The current density-voltage characteristics of the modified units showed that it is possible to maintain a good electrochemical performance of the cells despite the catalytic modification. A copper to nickel ratio of 1:3 resulted in a strong diminution of the catalytic reaction rate. This indicates that the modification could be a promising method to improve the performance of solid oxide fuel cells with direct internal reforming of hydrocarbons. (author)

  16. TOPICAL REVIEW Warm spraying—a novel coating process based on high-velocity impact of solid particles

    Directory of Open Access Journals (Sweden)

    Seiji Kuroda et al

    2008-01-01

    Full Text Available In recent years, coating processes based on the impact of high-velocity solid particles such as cold spraying and aerosol deposition have been developed and attracting much industrial attention. A novel coating process called 'warm spraying' has been developed, in which coatings are formed by the high-velocity impact of solid powder particles heated to appropriate temperatures below the melting point of the powder material. The advantages of such process are as follows: (1 the critical velocity needed to form a coating can be significantly lowered by heating, (2 the degradation of feedstock powder such as oxidation can be significantly controlled compared with conventional thermal spraying where powder is molten, and (3 various coating structures can be realized from porous to dense ones by controlling the temperature and velocity of the particles. The principles and characteristics of this new process are discussed in light of other existing spray processes such as high-velocity oxy-fuel spraying and cold spraying. The gas dynamics of particle heating and acceleration by the spraying apparatus as well as the high-velocity impact phenomena of powder particles are discussed in detail. Several examples of depositing heat sensitive materials such as titanium, metallic glass, WC–Co cermet and polymers are described with potential industrial applications.

  17. The effect of porosity gradient in a Nickel/Yttria Stabilized Zirconia anode for an anode-supported planar solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    An, Chung Min; Sammes, Nigel [Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO (United States); Song, Jung-Hoon [RIST, Pohang (Korea); Kang, Inyong [Department of Chemical Engineering, Colorado School of Mines, Golden, CO (United States)

    2010-02-01

    In this paper, a graded Ni/YSZ cermet anode, an 8 mol.%YSZ electrolyte, and a lanthanum strontium manganite (LSM) cathode were used to fabricate a solid oxide fuel cell (SOFC) unit. An anode-supported cell was prepared using a tape casting technique followed by hot pressing lamination and a single step co-firing process, allowing for the creation of a thin layer of dense electrolyte on a porous anode support. To reduce activation and concentration overpotential in the unit cell, a porosity gradient was developed in the anode using different percentages of pore former to a number of different tape-slurries, followed by tape casting and lamination of the tapes. The unit cell demonstrated that a concentration distribution of porosity in the anode increases the power in the unit cell from 76 mW cm{sup -2} to 101 mW cm{sup -2} at 600 C in humidified hydrogen. Although the results have not been optimized for good performance, the effect of the porosity gradient is quite apparent and has potential in developing superior anode systems. (author)

  18. Eltron Research & Development

    Energy Technology Data Exchange (ETDEWEB)

    Evenson, Carl; Mackay, Richard; Faull, John

    2014-03-01

    This topical report covers technical work conducted under contract DE-FC26-05NT42469 between FY06 Q1 through FY14 Q2. The project evolved through several budget periods, budget revisions and continuation applications. This report covers work performed under the “base” program. In 2010 ARRA funding was added to the project. A separate report covering the ARRA portion of the project was submitted to DOE. The original project was focused on research and development for scale-up of hydrogen separation membrane for a FutureGen type power plant. The work included membrane testing and evaluation of metal alloy flat plates vs. tubes and metal membranes vs. cermet membranes. In addition, economic analysis and process modeling was performed. The original project team included CoorsTek, NORAM, and Praxair. In FY10Q2 a continuation application was filed for conducting a scale-up test at Eastman Chemical. In this part of the project a Subscale Engineering Prototype (SEP) membrane skid was designed, fabricated, and operated on a gasified coal slip-stream on Eastman’s site in Kingsport, TN. Following operation, the project was reorganized and a second continuation application with a new statement of work was initiated in FY12Q1. Finally, based on DOE’s decision not to proceed with a Process Development Unit (PDU) field test, a third continuation application and statement of work was initiated in FY13Q1 to close out the project.

  19. The development of lower enrichment fuels for Canadian research reactors

    International Nuclear Information System (INIS)

    As part of the world wide move to proliferation resistant fuels, new fuels which use reduced enrichment uranium are being developed for use in the NRX and NRU reactors. A fuel consisting of particles of a USiAl alloy dispersed in an Al matrix has been selected for development along with Al-37 wt% U alloy and Al-U3O8 cermet as backup fuels. This report outlines the progress made in the development of the Al-USiAl and Al-37 wt% U. Results show that good quality extruded rods containing either fuel can be made with techniques similar to those used to fabricate the current NRX and NRU fuels. However, the new fuels will be more expensive to make. Although the oxidation behaviour of the Al-USiAl is not as good as that of the Al-U alloys, its corrosion behaviour in high temperature water does not seem much worse. The oxidation and aqueous corrosion of A-37 wt% U are not much different from those of the Al-U alloys currently used. (author)

  20. Quantitative differential thermal analysis study of the U/sub 3/O/sub 8/-Al thermite reaction

    International Nuclear Information System (INIS)

    Concerns about proliferation resistance of nuclear fuels and fuel cycles have prompted a reinvestigation of U/sub 3/O/sub 8/-Al cermet fuels currently being used in research and test reactors. In particular, higher loadings of U/sub 3/O/sub 8/ are being considered. These new fuel compositions are in the region of maximum possible thermal energy release from the high temperature thermite reaction between the U/sub 3/O/sub 8/ and aluminum components. The present study was initiated to measure the amount of reaction heat evolved quantitatively. A differential thermal analysis system was calibrated with materials of known heats of reaction. Subsequently, specimens of high uranium-load U/sub 3/O/sub 8/-Al powder mixtures were analyzed. Preliminary results showed that the thermite reaction heat evolved from these specimens was much lower than expected. Specimens of simulated fuel plates showed similar low results. Possible reasons for this behavior are discussed. 18 refs

  1. Coextrusion of 60 to 80 wt % U3O8 nuclear fuel elements

    International Nuclear Information System (INIS)

    Aluminum-clad billets with up to 80 wt % U3O8 in U3O8-Al cores have been coextruded at SRP. However, above 70 wt % U3O8, yields are low because of core-cracking. Proper selection of materials and extrusion parameters will give process conditions for successful fabrication. Studies were begun of the effects of these parameters on the flow of metal during coextrusion. In coextruded tubes, cracks are formed in large uranium oxide particles. Cracking is caused by the high tensile deformation of these particles that occurs as the cermet material flows through the die. Lower extrusion ratios and larger die angles appear to reduce severe particle cracking and increase fabrication yields. The particle size distribution of the ceramic fuel phase also influences fabricability. Six P/M assemblies with up to 57 wt % U3O8 in U3O8-Al cores were successfully irradiated to 1.6 x 1021 fissions per cm3 of core. No swelling or blistering of the tubes occurred

  2. Development of lower enrichment fuels for Canadian research reactors

    International Nuclear Information System (INIS)

    As part of the worldwide move to proliferation resistant fuels, new fuels which use reduced enrichment uranium are being developed for use in the NRX and NRU reactors. A fuel consisting of particles of a USiAl alloy dispersed in an Al matrix has been selected for development along with Al-37 wt % U alloy and Al-U3O8 cermet as backup fuels. This report outlines the progress made in the development of the Al-USiAl and Al-37 wt % U. Results show that good quality extruded rods containing either fuel can be made with techniques similar to those used to fabricate the current NRX and NRU fuels. However, the new fuels will be more expensive to make. Although the oxidation behavior of the Al-USiAl is not as good as that of the Al-U alloys, its corrosion behavior in high temperature water does not seem much worse. The oxidation and aqueous corrosion of Al-37 wt % U are not much different from those of the Al-U alloys currently used

  3. Ceramic solvents for the RA-1 Reactor

    International Nuclear Information System (INIS)

    Full text: The new version of fuel for the RA-1 reactor will consist of Zry cladding tubes of 8.2 mm external diameter and, as fuel material, of pellets of 20% enriched U3O8 and Al powder mixture. Because significant internal temperatures are expected (higher than those obtained in plate fuel elements) and that Al oxide formation in the interfaces between U3O8 particles have been detected in experiences outside the reactor and in post-irradiation examinations, the possibility to use ceramic oxides as fissile material solvent, for instance Alumina or Zirconia is explored, since they are inert materials which would avoid fuel transformations and, therefore, possible dimensional and thermal changes. Besides, the oxidation resistance improvement is analyzed through the utilization of UO2 in the Al cermet, since it is more stable in the reaction with Al. The possibility of using the existing utilities to explore these alternatives is considered. This type of fuel is also of interest because it is potentially apt to be used with highly enriched uranium coming from nuclear weapons

  4. Application of a quality control program for developing fuel elements for research reactors

    International Nuclear Information System (INIS)

    The development of nuclear fuel elements for the IEAR-1 research reactor is a task that is being pursued by IPEN/CNEN-SP for several years. The studies included the development of U3O8-Al Nuclear cermets, rolling of U3O8-Al brickets using the picture frame technique for the obtension of Nuclear fuel plates as well as the fabrication of components and the final assembling of the fuel elements. The prototypes are made to conform to stringent quality control specifications. These specifications cover various aspects such as the metallurgical, ceramical, and mechanical properties of the materials involved as well as non-destructive tests and dimensional and visual requirements of the various components. In this context, an extensive specification of the materials and components used have been compiled and are periodically reviewed and revised. An extensive quality control program was planned and is being tested in practice simultaneously to the fuel element development. During the elaboration of the procedures for the characterization tests, special attention has been devoted to the storage of data that could be used for the analysis of the irradiation behaviour of the fuel element. The various procedures used during implementation of the system required for the quality control of the nuclear fuel elements for the IEAR-1 Nuclear reactor are presented. (Author)

  5. Kinetics of (reversible) internal reforming of methane in solid oxide fuel cells under stationary and APU conditions

    Science.gov (United States)

    Timmermann, H.; Sawady, W.; Reimert, R.; Ivers-Tiffée, E.

    The internal reforming of methane in a solid oxide fuel cell (SOFC) is investigated and modeled for flow conditions relevant to operation. To this end, measurements are performed on anode-supported cells (ASC), thereby varying gas composition (y CO = 4-15%, yH2 = 5 - 17 % , yCO2 = 6 - 18 % , yH2O = 2 - 30 % , yCH4 = 0.1 - 20 %) and temperature (600-850 °C). In this way, operating conditions for both stationary applications (methane-rich pre-reformate) as well as for auxiliary power unit (APU) applications (diesel-POX reformate) are represented. The reforming reaction is monitored in five different positions alongside the anodic gas channel by means of gas chromatography. It is shown that methane is converted in the flow field for methane-rich gas compositions, whereas under operation with diesel reformate the direction of the reaction is reversed for temperatures below 675 °C, i.e. (exothermic) methanation occurs along the anode. Using a reaction model, a rate equation for reforming could be derived which is also valid in the case of methanation. By introducing this equation into the reaction model the methane conversion along a catalytically active Ni-YSZ cermet SOFC anode can be simulated for the operating conditions specified above.

  6. 高温发汗自润滑技术及其理论研究%Research on the Theory and Technology of the Sweating Self-Lubrication at Elevated Temperature

    Institute of Scientific and Technical Information of China (English)

    刘佐民; 王砚军; 张一兵; 燕松山; 解芳; 冯雪梅; 杨丽颖; 郭红; 卢平

    2011-01-01

    The project is supported by National Science Foundation of China"The Study of the Theory and Technology of Sweating Diffusion Lubrication, No. 50275110) and "The Study of the Structure Morphology and Function Control Mechanism of High Temperature Lubrication Cells,No. 50775168),as well the Project of Doctoral Foundation of Ministry of Education of China"The Study of the Multi-Cellular Structure Stability of High Temperature Sweating Lubrication Cells,No. 20070497105). In the project,the lubrication mechanisms, mechanical properties, characterization of lubrication and its control scenarios of the High Temperature Sweating Self-Lubrication Composite ( HTSSLC) are studied based on theorital model and experiments. The cellular structures and its strength are also established by developing new therital models and used to analyze the mutual coupling between the cellular structure and preparing technology. For opening up the application range of the composite,some new lubricants and its compound technologies are made up based on design of the materials and experiments. Based on the above research, the HTSSLC and its theoretic and technological systems are developed. Sweating self-lubrication at elevated temperature is a new technology developed based on the principle of the sweat gland structure and sweating mechanism of organism. HTSSLC is composed of the cermet matrix (cellular wall) with ordered pores and multi-elemental lubricants (cellular nuclear) which infiltrat into the pores of the matrix. During friction, the lubricants are driven by the friction therm-stress and diffused out of the matrix along ordered pores to the friction surface to realize self-compensating lubrication. Based on the human sweat gland structure and the concept of sweating self-lubrication at elevated temperature,a new Pore Structure Distribution Model (PSDM) has been developed for characterizing the gland-like cermet matrix with porous structure. The model is used to study the effect of the

  7. POROUS NiO/YSZ MATERIALS PREPARED BY A TAPE CALENDERING PROCESS%轧膜成型法制备燃料电池NiO/YSZ多孔阳极材料的研究

    Institute of Scientific and Technical Information of China (English)

    王永乾; 程继贵; 朱金传; 杨俊芳; 樊玉萌; 王睿

    2011-01-01

    NiO/YSZ green tapes were prepared by an aqueous tape calendering process, which were sintered at 1350-1450℃ to obtain NiO/YSZ anode materials. Effects of the adhesive contents used in the green tapes and the sintering temperature on the microstructure and property of the sintered NiO/YSZ materials were investigated. Density and porosity of the sintered NiO/YSZ samples were measured and pore size and distribution were tested by the N2 bubble method. Microstructure of the NiO/YSZ samples was observed by scanning electron microscope (SEM) and electrical conductivity of the reduced Ni/YSZ cermets were also tested by the four-probe method. It was found that porosity and pore size and distribution of the sintered NiO/ YSZ samples depend greatly on sintering temperature, all of which decreases with the increase of sintering temperature, consistent with the SEM observation. Furthermore, the increase of adhesive content in the green tapes results in the increase of porosity and mean pore size of the sintered NiO/YSZ samples. Electrical conductivity of the Ni/YSZ cermets increases with increase of sintering temperature and decreases with increase of test temperature.%以水基轧膜工艺制备出了不同粘结剂含量的NiO/氧化钇稳定氧化锆(YSZ)固体氧化物燃料电池多孔阳极材料。研究了粘结剂含量和制备工艺条件等对多孔阳极微结构和性能的影响。实验结果表明:轧膜坯体的烧结温度对NiO/YSZ阳极烧结体的孔隙率有着决定的影响;为获得较高孔隙率和一定孔径分布的阳极烧结体,轧膜生坯的烧结温度应不超过I450℃。此外,粘结剂含量对轧膜生坯的烧结行为及烧结体的性能也有明显的影响,在相同的烧结温度下,高粘结剂含量阳极烧结体的孔隙率和孔径范围明显高于低粘结剂含量的烧结体,其中,粘接剂含量5%的生坯烧结后得到的NiO/YSZ阳极材料具有较好的综合性能;此外,NiO

  8. 真空管式太阳能集热器研究最新进展%Latest Development of Vacuum Tube Solar Collectors

    Institute of Scientific and Technical Information of China (English)

    李建昌; 侯雪艳; 王紫瑄; 吴隽稚; 巴德纯

    2012-01-01

    The latest development of the vacuum tube solar collectors was reviewed. The discussions centered on three aspects: the advanced materials, structures, and thermal stabilities of the selective absorption coatings in vacuum. The stainless steel,Ti, Al and Ni are good materials for applications at low and medium temperatures;whereas Mo and W do well at high temperatures. The absorption coatings are mainly divided into two types: the absorber layer/anti-reflection dielectric layer, based on light interference;the metal infrared reflection layer/metal dielectric absorber layer/anti-reflection dielectric layer, named as the cermet absorber coating. Three main factors influencing the thermal stability include cracks,oxidation,and atomic inter-diffusion at high temperatures. Besides,the thermal stability also depends on its thickness and microstructures.The scenarios possibly focus on,I) .growth of multilayer and gradient structured layers by electrochemical route and/or by magnetron sputtering,and hopefully with some nano-materials or nano-structures;ii). Development of the Mo-based cermet coatings with high efficiency at high temperatures; iii) . Realization of the devices with high intelligence,automation,and integration in buildings.%从选择性吸收涂层的材料、结构、热稳定性及真空环境等方面综述了真空管式太阳能集热器的研究进展.不锈钢、Ti、Al、Ni类材料适于制备中低温选择性吸收涂层;而Mo和W类等高熔点材料,适于高温涂层.涂层结构方面,主要有吸收层/介质减反层的光干涉类、金属红外反射层/金属介质吸收层/介质减反层的金属陶瓷类.影响涂层热稳定性的主要因素是高温下涂层的破裂、氧化及元素扩散,涂层厚度与结构也能影响热稳定性.结果表明:①选择性吸收涂层制备,应采用电化学或磁控溅射技术并结合纳米材料对涂层进行多层化、梯度化研究;②应着重发展Mo类金属

  9. Development of conventional and single-chamber planar solid oxide fuel cells by screen-printing; Developpement de piles a combustible de type SOFC, conventionnelles et mono-chambres, en technologie planaire par serigraphie

    Energy Technology Data Exchange (ETDEWEB)

    Rotureau, D.

    2005-06-15

    This work is the first of a new research theme of the laboratory in the field of solid oxide planar fuel cells. With his high experience in the sensor field, the objectives were to realize prototypes using a 'low cost' technology like screen-printing, using classical materials in the field of fuel cells, rather than researching new materials having optimum properties which may be damaged during the realisation of the complete fuel cell. These materials are yttria stabilised zirconia (YSZ) for electrolyte, strontium doped lanthanum manganite (LSM) for cathode and a nickel oxide-YSZ cermet (NiO-YSZ) for anode. The first part of the study consists in structural and electrical characterizations of chosen materials, both on dense pellets and on screen-printed layers of YSZ, LSM or NiO-YSZ. These characterizations showed a good adequation of our materials for a fuel cell application. The second part consists in testing realised prototypes on electrolyte support and on anode support with screen-printed electrodes and electrolyte. The weak obtained performances are mainly due to the low functional temperature (800 C), the thickness of the electrolyte support (about 1 mm) and the porosity of the YSZ screen-printed layers. Finally, we tested in the same time an original device in which both electrodes are exposed to a fuel and air mixture. This promising device inspired from the research on potentiometric sensors developed in the team by N. Guillet (2001), avoids the tightness problem encountered with two gaseous chambers. Moreover, the performances obtained are just twice below than those obtained with a conventional fuel cell with two gaseous chambers. (author)

  10. Structural and chemical degradation mechanisms of pure YSZ and its components ZrO2 and Y2O3 in carbon-rich fuel gases.

    Science.gov (United States)

    Köck, Eva-Maria; Kogler, Michaela; Götsch, Thomas; Klötzer, Bernhard; Penner, Simon

    2016-05-25

    Structural and chemical degradation mechanisms of metal-free yttria stabilized zirconia (YSZ-8, 8 mol% Y2O3 in ZrO2) in comparison to its pure oxidic components ZrO2 and Y2O3 have been studied in carbon-rich fuel gases with respect to coking/graphitization and (oxy)carbide formation. By combining operando electrochemical impedance spectroscopy (EIS), operando Fourier-transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS), the removal and suppression of CH4- and CO-induced carbon deposits and of those generated in more realistic fuel gas mixtures (syngas, mixtures of CH4 or CO with CO2 and H2O) was examined under SOFC-relevant conditions up to 1273 K and ambient pressures. Surface-near carbidization is a major problem already on the "isolated" (i.e. Nickel-free) cermet components, leading to irreversible changes of the conduction properties. Graphitic carbon deposition takes place already on the "isolated" oxides under sufficiently fuel-rich conditions, most pronounced in the pure gases CH4 and CO, but also significantly in fuel gas mixtures containing H2O and CO2. For YSZ, a comparative quantification of the total amount of deposited carbon in all gases and mixtures is provided and thus yields favorable and detrimental experimental approaches to suppress the carbon formation. In addition, the effectivity and reversibility of removal of the coke/graphite layers was comparably studied in the pure oxidants O2, CO2 and H2O and their effective contribution upon addition to the pure fuel gases CO and CH4 verified.

  11. Características de los recubrimientos WC-NiCrBSiFe en función del sistema de proyección térmica

    Directory of Open Access Journals (Sweden)

    Higuera-Hidalgo, V.

    2004-10-01

    Full Text Available WC-NiCrBSiFe coatings are normally used as protection against heat, corrosion and erosion actions encountered in superheater and reheater tubes in power plant boilers. This coating was thermal-spray projected using different procedures (plasma, HVOF and HFPD onto stainless steel specimens. The microstructures, porosities, oxide contents and microhardnesses of the coatings were determined. Thermal fatigue tests under simulative power plant service conditions were conducted in an experimental combustion chamber and, finally, the adhesion between the substrate and the coating layer was evaluated by means of tensile tests.The obtained results are discussed, and special attention was paid to the specific characteristics of the different spraying procedures.

    El material tipo cermet WC-NiCrBSiFe se emplea como elemento protector frente al desgaste, en elementos de calderas de vapor, como son los sobrecalentadores y recalentadores de vapor, donde las condiciones de servicio tan severas (alta temperatura, erosión por cenizas volantes, etc. acortan notablemente la vida útil de los materiales convencionales empleados. En este trabajo se ha realizado la proyección térmica de este recubrimiento por arco plasma no transferido, proyección mediante llama a elevada velocidad (HVOF y proyección por detonación a elevada frecuencia (HFPD. Se determinaron las microestructuras, porosidades, contenidos en óxidos y microdurezas de los distintos recubrimientos obtenidos. También, se llevaron a cabo ensayos de fatiga térmica en condiciones similares a las imperantes en el interior de una caldera, mediante el empleo de un combustor experimental. Finalmente, se determinó la adherencia de las capas a los sustratos receptores, mediante ensayos de tracción. Los resultados obtenidos son discutidos en función de las características específicas de los diferentes sistemas de proyección utilizados.

  12. Effect of SUS316L stainless steel surface conditions on the wetting of molten multi-component oxides ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jin, E-mail: wangjinustb@gmail.com [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, 808-0196 (Japan); Matsuda, Nozomu [Bar and Wire Product Unit, Nippon steel and Sumitomo Metal Corporation, Fukuoka, 802-8686 (Japan); Shinozaki, Nobuya [Graduate School of Life Science and Systems Engineering, Kyushu Institute of Technology, Fukuoka, 808-0196 (Japan); Miyoshi, Noriko [The Center for Instrumental Analysis, Kyushu Institute of Technology, Fukuoka, 804-8550 (Japan); Shiraishi, Takanobu [Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8588 (Japan)

    2015-02-01

    Highlights: • Multi-component oxides had a good wetting on stainless substrates with pretreatments. • Various substrates surface roughness caused the difference of final contact angles. • The wetting rate was slow on polished substrate due to the slow surface oxidation. - Abstract: A study on the effect of SUS316L stainless steel surface conditions on the wetting behavior of molten multi-component oxides ceramic was performed and aimed to contribute to the further understanding of the application of oxides ceramic in penetration treatment of stainless steel coatings and the deposition of stainless steel cermet coatings. The results show that at 1273 K, different surface pre-treatments (polishing and heating) had an important effect on the wetting behavior. The molten multi-component oxides showed good wettability on both stainless steel substrates, however, the wetting process on the polished substrate was significantly slower than that on the heated substrates. The mechanism of the interfacial reactions was discussed based on the microscopic and thermodynamic analysis, the substrates reacted with oxygen generated from the decomposition of the molten multi-component oxides and oxygen contained in the argon atmosphere, and the oxide film caused the molten multi-component oxides ceramic to spread on the substrates surfaces. For the polished substrate, more time was required for the surface oxidation to reach the surface composition of Heated-S, which resulted in relatively slow spreading and wetting rates. Moreover, the variance of the surface roughness drove the final contact angles to slightly different values following the sequence Polished-S > Heated-S.

  13. Study on the Secondary Electron Emission of Rare Earth-Molybdenum Cathodes%稀土-钼阴极二次电子发射性能研究

    Institute of Scientific and Technical Information of China (English)

    刘伟; 王金淑; 高非; 任志远; 周美玲

    2011-01-01

    采用固固掺杂、液固掺杂和液液掺杂方法制备了稀土氧化物掺杂钼粉,随后利用等离子体快速烧结( spark plasma sinterin,SPS)和传统的压制与高温烧结分别制备稀土-钼金属陶瓷材料,利用金相显微镜、发射性能测试方法对样品的微观结构和二次电子发射性能进行了研究.结果表明:稀土氧化物均匀掺杂和组织的细化有利于材料发射性能提高.经过高温氢气处理,使得样品激活温度大幅降低,发射系数大幅提高.%The rare earth oxides (REO) doped molybdenum powder was prepared by solid-solid doping, solid-liquid doping and liquid-liquid doping, respectively; afterwards, the powder was sintered by spark plasma sintering and traditional sintering combined with cold isostatic compaction method for fabricating REO-Mo cermet cathodes. OM and emission property tests were used to research the microstructure and the secondary electron emission properties of the samples. The results show that the emission properties of the material can be enhanced through the uniform distribution of rare earth oxides and the refinement of structure. The activation temperature can be decreased greatly by annealing in hydrogen at high temperature, and the secondary emission yield is also enhanced apparently.

  14. Improvement of tool materials by deposition of gradient and multilayers coatings

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2006-10-01

    Full Text Available Purpose: Investigation of the functional properties of cermets, Si3N4 and Al2O3 based ceramics, coated with the PVD andCVD multilayer and gradient coatings and comparison them with the commercial uncoated and coated tool materials.Design/methodology/approach: TEM, SEM, confocal microscopy, scratch test, microhardness tests, roughnesstests, cutting tests.Findings: Employment of the hard wear resistant coatings deposited onto the sintered ceramic tool materials withthe physical deposition from the gaseous phase (PVD is reckoned as one of the most important achievements inthe last years in the area of improvement of the service properties of ceramic cutting tools. Depositing the antiwearcoatings of the gradient and multi TiN+(Ti,Al,SiN+TiN types onto the investigated ceramic tool materialsmakes it possible to achieve the clear improvement of their tool life and also of the quality of the machinedsurfaces, reduction of machining costs and elimination of cutting fluids used in machining.Practical implications: The widespread use in machining of oxide and nitride ceramics, as well as of cermetswith the complex nanocrystaline coatings deposited in the PVD processes contributes to the increased interestin the contemporary „Near-Net-Shape” technology, i.e., manufacturing semi-products with the shape anddimensions as close as possible to those of the finished products.Originality/value: In the paper the research of multilayer and gradient TiN+(Ti,Al,SiN+TiN nanocrystalline coatingsdeposited in the PVD method on sintered tool materials carried out in order to improve the tool cutting properties.

  15. Influence of ion/atom arrival ratio on structure and optical properties of AlN films by ion beam assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Jian-ping [Department of Energy Material and Technology, General Research Institute for Nonferrous Metals, Beijing 100088 (China); School of Engineering and Technology, China University of Geosciences, Beijing 100083 (China); Fu, Zhi-qiang, E-mail: fuzq@cugb.edu.cn [School of Engineering and Technology, China University of Geosciences, Beijing 100083 (China); Liu, Xiao-peng [Department of Energy Material and Technology, General Research Institute for Nonferrous Metals, Beijing 100088 (China); Yue, Wen; Wang, Cheng-biao [School of Engineering and Technology, China University of Geosciences, Beijing 100083 (China)

    2014-10-30

    Highlights: • AlN films were fabricated by dual ion beam sputtering. • Chemical bond status and phase composition of the films were studied by XPS and XRD. • Optical constants were measured by spectroscopic ellipsometry. • Influence of ion/atom arrival ratio on the films was studied. - Abstract: In order to improve the optical properties of AlN films, the influence of the ion/atom arrival ratio on the structure and optical characteristics of AlN films deposited by dual ion beam sputtering was studied by using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, spectroscopic ellipsometry and UV–vis spectroscopy. The films prepared at the ion/atom arrival ratio of 1.4 are amorphous while the crystalline quality is improved with the increase of the ion/atom arrival ratio. The films deposited at the ion/atom arrival ratio of no less than 1.8 have an approximately stoichiometric ratio and mainly consist of aluminum nitride with little aluminum oxynitride, while metallic aluminum component appears in the films deposited at the ion/atom arrival ratio of 1.4. When the ion/atom arrival ratio is not less than 1.8, films are smooth, high transmitting and dense. The films prepared with high ion/atom arrival ratio (≥1.8) display the characteristic of a dielectric. The films deposited at the ion/atom arrival ratio of 1.4 are coarse, opaque and show characteristic of cermet.

  16. Influence of reduction conditions of NiO on its mechanical and electrical properties

    Directory of Open Access Journals (Sweden)

    Yehor Brodnikovskyi

    2016-04-01

    Full Text Available Yttria stabilized zirconia with a nickel catalyst (Ni-YSZ is the most developed, widely used cermet anode for manufacturing Solid Oxide Fuel Cells (SOFCs. Its electro-catalytic properties, mechanical durability and performance stability in hydrogen-rich environ­ments makes it the state of the art fuel electrode for SOFCs. During the reduction stage in initial SOFC operation, the virgin anode material, a NiO-YSZ mixture, is reduced to Ni-YSZ. The volume decrease associated with the change from NiO-YSZ to Ni-YSZ creates voids and causes structural changes, which can influence the physical properties of the anode. In this work, the structural, mechanical and electrical properties of NiO samples before and after reduction in pure H2 and a mixture of 5 vol. % H2-Ar were studied. The NiO to Ni phase transformations that occur in the anode under reducing and Reduction-Oxidation (RedOx cycling conditions and the impact on cell microstruc­ture, strength and electrical conductivity have been examined. Results show that the RedOx treatment of the NiO samples influence on their properties controversially, due to structural transfor­mation (formation of large amount of fine pores of the reduced Ni. It strengthened the treated samples yielding the highest mechanical strength values of 25.7 MPa, but from another side it is resulting in lowest electrical conductivity value of 1.9×105 S m-1 among all reduced samples. The results of this investigation shows that reduction conditions of NiO is a powerful tool for influence on properties of the anode substrate.

  17. Synthesis, crystal growth, structure, and micro-hardness of W{sub 9}Al{sub 3}CoC{sub 3}-First single crystal studies on an ordered hexagonal {kappa}-carbide

    Energy Technology Data Exchange (ETDEWEB)

    Kotzott, Dominik [Albert-Ludwigs-Universitaet Freiburg, Institut fuer Anorganische und Analytische Chemie, Albertstrasse 21, D-79104 Freiburg (Germany); Hillebrecht, Harald, E-mail: harald.hillebrecht@ac.uni-freiburg.d [Albert-Ludwigs-Universitaet Freiburg, Institut fuer Anorganische und Analytische Chemie, Albertstrasse 21, D-79104 Freiburg (Germany); Freiburger Materialforschungszentrum FMF, Stefan-Maier-Strasse 25, D-79104 Freiburg (Germany)

    2010-04-02

    Single crystals of the new carbides W{sub 9}Al{sub 3}CoC{sub 3} were synthesized from a metallic melt and characterised by XRD and EDXS measurements. The crystal structure of W{sub 9}Al{sub 3}CoC{sub 3} was refined on the basis of single crystal data (hP32, P6{sub 3}/mmc, a = 7.9051(11) A, c = 7.7869(16) A, Z = 2, 304 reflections, 20 parameters, R{sub 1}(F) = 0.0272, wR{sub 2}(F{sup 2}) = 0.0562). W{sub 9}Al{sub 3}CoC{sub 3} belongs to the family of {kappa}-carbide M{sub 9}M{sub 3}'C{sub 3} or M{sub 10}M{sub 3}'C{sub 3} which are important components for cermets. Its crystal structure is characterised by CW{sub 6}-octahedra which are connected to 6.3.6.3 Kagome-net. Co and Al have no contacts to C-atoms. The metal atoms are ordered and all positions show full occupation. W{sub 9}Al{sub 3}CoC{sub 3} represents the first {kappa}-carbide with a complete structure refinement on the basis of single crystal data. Micro-hardness measurement on single crystals yield values of H{sub V} = 15.5 GPa and H{sub K} = 12.5 GPa.

  18. Preliminary evaluation of alternative waste form solidification processes. Volume I. Identification of the processes.

    Energy Technology Data Exchange (ETDEWEB)

    Treat, R.L.; Nesbitt, J.F.; Blair, H.T.; Carter, J.G.; Gorton, P.S.; Partain, W.L.; Timmerman, C.L.

    1980-04-01

    This document contains preconceptual design data on 11 processes for the solidification and isolation of nuclear high-level liquid wastes (HLLW). The processes are: in-can glass melting (ICGM) process, joule-heated glass melting (JHGM) process, glass-ceramic (GC) process, marbles-in-lead (MIL) matrix process, supercalcine pellets-in-metal (SCPIM) matrix process, pyrolytic-carbon coated pellets-in-metal (PCCPIM) matrix process, supercalcine hot-isostatic-pressing (SCHIP) process, SYNROC hot-isostatic-pressing (SYNROC HIP) process, titanate process, concrete process, and cermet process. For the purposes of this study, it was assumed that each of the solidification processes is capable of handling similar amounts of HLLW generated in a production-sized fuel reprocessing plant. It was also assumed that each of the processes would be enclosed in a shielded canyon or cells within a waste facility located at the fuel reprocessing plant. Finally, it was assumed that all of the processes would be subject to the same set of regulations, codes and standards. Each of the solidification processes converts waste into forms that may be acceptable for geological disposal. Each process begins with the receipt of HLLW from the fuel reprocessing plant. In this study, it was assumed that the original composition of the HLLW would be the same for each process. The process ends when the different waste forms are enclosed in canisters or containers that are acceptable for interim storage. Overviews of each of the 11 processes and the bases used for their identification are presented in the first part of this report. Each process, including its equipment and its requirements, is covered in more detail in Appendices A through K. Pertinent information on the current state of the art and the research and development required for the implementation of each process are also noted in the appendices.

  19. Influence of a powder feed rate on the properties of the plasma sprayed chromium carbide- 25% nickel chromium coating

    Directory of Open Access Journals (Sweden)

    Mihailo R. Mrdak

    2014-04-01

    Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 The plasma spray process is a leading technology of powder depositing in the production of coatings widely used in the aerospace industry for the protection of new parts and for the repair of worn ones. Cermet 75Cr3C2 - 25Ni(Cr coatings based on Cr3C2 carbides are widely used to protect parts as they retain high values of hardness, strength and resistance to wear up to a temperature of 850°C. This paper discusses the influence of the parameters of the plasma spray deposition of 75Cr3C2 - 25Ni(Cr powder on the structure and mechanical properties of the coating. The powder is deposited using plasma spraying at atmospheric pressure (APS. The plasma gas is He, which is an inert gas and does not react with the powder; it produces dense plasma with lower heat content and less incorporated ambient air in the plasma jet thus reducing temperature decomposition and decarburization of Cr3C2 carbide.. In this study, three groups of coatings were deposited with three different powder feed rates of: 30, 45 and 60 g/min. The  coating with the best properties was deposited on the inlet flange parts of the turbo - jet engine TV2-117A to reduce the influence of vibrations and wear. The structures and the mechanical properties of 75Cr3C2 - 25Ni(Cr coatings are analyzed in accordance with the Pratt & Whitney standard. Studies have shown that powder feed rates have an important influence on the mechanical properties and structures of 75Cr3C2 - 25Ni(Cr coatings. 

  20. Engine System Model Development for Nuclear Thermal Propulsion

    Science.gov (United States)

    Nelson, Karl W.; Simpson, Steven P.

    2006-01-01

    In order to design, analyze, and evaluate conceptual Nuclear Thermal Propulsion (NTP) engine systems, an improved NTP design and analysis tool has been developed. The NTP tool utilizes the Rocket Engine Transient Simulation (ROCETS) system tool and many of the routines from the Enabler reactor model found in Nuclear Engine System Simulation (NESS). Improved non-nuclear component models and an external shield model were added to the tool. With the addition of a nearly complete system reliability model, the tool will provide performance, sizing, and reliability data for NERVA-Derived NTP engine systems. A new detailed reactor model is also being developed and will replace Enabler. The new model will allow more flexibility in reactor geometry and include detailed thermal hydraulics and neutronics models. A description of the reactor, component, and reliability models is provided. Another key feature of the modeling process is the use of comprehensive spreadsheets for each engine case. The spreadsheets include individual worksheets for each subsystem with data, plots, and scaled figures, making the output very useful to each engineering discipline. Sample performance and sizing results with the Enabler reactor model are provided including sensitivities. Before selecting an engine design, all figures of merit must be considered including the overall impacts on the vehicle and mission. Evaluations based on key figures of merit of these results and results with the new reactor model will be performed. The impacts of clustering and external shielding will also be addressed. Over time, the reactor model will be upgraded to design and analyze other NTP concepts with CERMET and carbide fuel cores.