WorldWideScience

Sample records for cermets

  1. Nickel-Magnesia Cermet Coatings

    Science.gov (United States)

    1952-06-01

    alumin " oxide cermet. To develop a bond between these tw components it in first necessary to produce a controlled film of Cr 203 on the Cr grains...somewhat more refractory. A cobalt - magnesia cermet may be made in the same way as the nickel - magnesia cermet, the bond being through the agency...of the oxide CoO. However, cobalt is not as oxidation resistant as nickel and is more strategic. Iron will wet probably all oxides and silicates and

  2. 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.

  3. 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.

  4. Solid solution lithium alloy cermet anodes

    Science.gov (United States)

    Richardson, Thomas J.

    2013-07-09

    A metal-ceramic composite ("cermet") has been produced by a chemical reaction between a lithium compound and another metal. The cermet has advantageous physical properties, high surface area relative to lithium metal or its alloys, and is easily formed into a desired shape. An example is the formation of a lithium-magnesium nitride cermet by reaction of lithium nitride with magnesium. The reaction results in magnesium nitride grains coated with a layer of lithium. The nitride is inert when used in a battery. It supports the metal in a high surface area form, while stabilizing the electrode with respect to dendrite formation. By using an excess of magnesium metal in the reaction process, a cermet of magnesium nitride is produced, coated with a lithium-magnesium alloy of any desired composition. This alloy inhibits dendrite formation by causing lithium deposited on its surface to diffuse under a chemical potential into the bulk of the alloy.

  5. Stochastic Computer Simulation of Cermet Coatings Formation

    Directory of Open Access Journals (Sweden)

    Oleg P. Solonenko

    2015-01-01

    Full Text Available An approach to the modeling of the process of the formation of thermal coatings lamellar structure, including plasma coatings, at the spraying of cermet powders is proposed. The approach based on the theoretical fundamentals developed which could be used for rapid and sufficiently accurate prediction of thickness and diameter of cermet splats as well as temperature at interface “flattening quasi-liquid cermet particle-substrate” depending on the key physical parameters (KPPs: temperature, velocity and size of particle, substrate temperature, and concentration of finely dispersed solid inclusions uniformly distributed in liquid metal binder. The results are presented, which concern the development of the computational algorithm and the program complex for modeling the process of laying the splats in the coating with regard to the topology of its surface, which varies dynamically at the spraying, as well as the formation of lamellar structure and porosity of the coating. The results of numerical experiments are presented through the example of thermal spraying the cermet TiC-30 vol.% NiCr powder, illustrating the performance of the developed computational technology.

  6. Toughening behavior in ceramics and cermets

    Energy Technology Data Exchange (ETDEWEB)

    Becher, P.F.; Sun, E.Y.; Hsueh, C.H.; Plucknett, K.P. [Oak Ridge National Lab., TN (United States); Kim, H.D. [Korean Inst. of Machinery and Materials, Changwon (Korea, Republic of); Hirao, K.; Brito, M. [National Industrial Research Inst., Nagoya (Japan)

    1998-10-01

    The development of high strength ({ge} 1 GPa), high toughness ({ge} 10 MPa {radical}m) ceramic systems is being examined using two approaches. In silicon nitride, toughening is achieved by the introduction of large prismatic shaped grains dispersed in a fine grain matrix. For the system examined herein, both the microstructure and the composition must be controlled. A distinctly bimodal distribution of grain diameters combined with controlled yttria to alumina ratio in additives to promote interfacial debonding is required. Using a cermet approach, ductile Ni{sub 3}Al-bonded TiC exhibited toughening due to plastic deformation within the Ni{sub 3}Al binder phase assisted by interfacial debonding and cleavage of TiC grains. The TiC-Ni{sub 3}Al cermets have toughness values equal to those of the WC-Co cermets. Furthermore, the TiC-Ni{sub 3}Al cermets exhibit high strengths that are retained in air to temperatures of {approximately} 1,000 C.

  7. Titanium Carbide-Nickel Cermets: Processing and Joing

    Science.gov (United States)

    1952-03-01

    Titanium carbide -nickel cermets can be sintered to have transverse rupture strengths over 250,000 pounds per square inch. To do so, four principal...enough to allow thorough degassing. Joining titanium - carbide cermets to high-temperature alloys has been accomplished by vacuum diffusion, and gives

  8. Overlay metallic-cermet alloy coating systems

    Science.gov (United States)

    Gedwill, M. A.; Levine, S. R.; Glasgow, T. K. (Inventor)

    1984-01-01

    A substrate, such as a turbine blade, vane, or the like, which is subjected to high temperature use is coated with a base coating of an oxide dispersed, metallic alloy (cermet). A top coating of an oxidation, hot corrosion, erosion resistant alloy of nickel, cobalt, or iron is then deposited on the base coating. A heat treatment is used to improve the bonding. The base coating serves as an inhibitor to interdiffusion between the protective top coating and the substrate. Otherwise, the protective top coating would rapidly interact detrimentally with the substrate and degrade by spalling of the protective oxides formed on the outer surface at elevated temperatures.

  9. Final report on cermet high-level waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Kobisk, E.H.; Quinby, T.C.; Aaron, W.S.

    1981-08-01

    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.

  10. 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.

  11. Development of boron carbide-copper cermets. Status report

    Energy Technology Data Exchange (ETDEWEB)

    1979-09-01

    The status of a program to develop a B/sub 4/C-Cu cermet for Breeder Reactor spent-fuel shipping cask neutron shields is presented. It is shown that inspectable 6 to 7 cm thick 60 to 70 volume percent B/sub 4/C cermets can be fabricated using hot isostatic powder processing procedures. An alternative manufacturing method, rheocasting, also appears to be a promising, perhaps more cost-effective method for producing these cermets. Recommendations for further development of these manufacturing processes are given.

  12. 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.

  13. Spark Plasma Sintering of Fuel Cermets for Nuclear Reactor Applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang Zhong; Robert C. O' Brien; Steven D. Howe; Nathan D. Jerred; Kristopher Schwinn; Laura Sudderth; Joshua Hundley

    2011-11-01

    The feasibility of the fabrication of tungsten based nuclear fuel cermets via Spark Plasma Sintering (SPS) is investigated in this work. CeO2 is used to simulate fuel loadings of UO2 or Mixed-Oxide (MOX) fuels within tungsten-based cermets due to the similar properties of these materials. This study shows that after a short time sintering, greater than 90 % density can be achieved, which is suitable to possess good strength as well as the ability to contain fission products. The mechanical properties and the densities of the samples are also investigated as functions of the applied pressures during the sintering.

  14. 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.

  15. 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.

  16. 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.

  17. Basic research on cermet nuclear fuel

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-01-01

    Production of cermet nuclear fuel having fine uranium dioxide (UO{sub 2}) particles dispersed in matrix metal requires basic property data on the compatibility of matrix metal with fission product compounds. It is thermodynamically suggested that, as burnup increases, cesium in oxide fuel reacts with the fuel, other fission products or cladding pipe and produces cesium uranates, cesium molybdate, or cesium chromate in stainless steel cladding pipe. Attempt was made to measure the thermal expansion coefficient and thermal conductivity of cesium uranates (Cs{sub 2}UO{sub 4} and Cs{sub 2}U{sub 2}O{sub 7}), cesium molybdate (Cs{sub 2}MoO{sub 4}) and cesium chromate (Cs{sub 2}CrO{sub 4}). Thermal expansion was measured by X-ray diffraction and determined by Cohen`s method. Thermal conductivity was obtained by measuring thermal diffusion by laser flash method. The thermal expansion of Cs{sub 2}UO{sub 4} and Cs{sub 2}U{sub 2}O{sub 7} is as low as 1.2% for the former and 1.0% for the latter, up to 1000K. The thermal expansion of Cs{sub 2}MoO{sub 4} is as high as that of Cs{sub 2}CrO{sub 4}, 2.1% for the former and 2.5% for the latter at temperatures from room temperature to 873K. Average thermal expansion in this temperature range is 4.4 x 10{sup -5} K{sup -1} for Cs{sub 2}MoO{sub 4} and 4.2 x 10{sup -5} K{sup -1}. The thermal expansion of Cs{sub 2}CrO{sub 4} is four times higher than that of UO{sub 2} and five times higher than that of Cr{sub 2}O{sub 3}. The thermal conductivity of Cs{sub 2}UO{sub 4} is nearly equal to that of Cs{sub 2}U{sub 2}O{sub 7} in absolute value and temperature dependency. Cs{sub 2}U{sub 2}O{sub 7}, having different thermal conductivity between {alpha} and {beta} phases, shows higher conductivity with {beta} than with {alpha}, about 1/4 of that of UO{sub 2} at 1000K. The thermal conductivity of Cs{sub 2}CrO{sub 4} is nearly equal to that of Cs{sub 2}MoO{sub 4} in absolute value and temperature dependency. (N.H.)

  18. 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.

  19. 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.

  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 Science-Based Understanding of Cermet Processing.

    Energy Technology Data Exchange (ETDEWEB)

    Cesarano, Joseph; Roach, Robert Allen; Kilgo, Alice C.; Susan, Donald Francis; Van Ornum, David J.; Stuecker, John N.

    2006-04-01

    AbstractThis report is a summary of the work completed in FY01 for science-based characterization of the processes used to fabricate 1) cermet vias in source feedthrus using slurry and paste-filling techniques and 2) cermet powder for dry pressing. Common defects found in cermet vias were characterized based on the ability of subsequent processing techniques (isopressing and firing) to remove the defects. Non-aqueous spray drying and mist granulation techniques were explored as alternative methods of creating CND50, the powder commonly used for dry pressed parts. Compaction and flow characteristics of these techniques were analyzed and compared to standard dry-ball-milled CND50. Due to processing changes, changes in microstructure can occur. A microstructure characterization technique was developed to numerically describe cermet microstructure. Machining and electrical properties of dry pressed parts were also analyzed and related to microstructure using this analytical technique.3 Executive SummaryThis report outlines accomplishments in the science-based understanding of cermet processing up to fiscal year 2002 for Sandia National Laboratories. The three main areas of work are centered on 1) increasing production yields of slurry-filled cermets, 2) evaluating the viability of high-solids-loading pastes for the same cermet components, and 3) optimizing cermet powder used in pressing processes (CND50). An additional development that was created as a result of the effort to fully understand the impacts of alternative processing techniques is the use of analytical methods to relate microstructure to physical properties. Recommendations are suggested at the end of this report. Summaries of these four efforts are as follows:1.Increase Production Yields of Slurry-Filled Cermet Vias Finalized slurry filling criteria were determined based on three designs of experiments where the following factors were analyzed: vacuum time, solids loading, pressure drop across the filter

  2. Functionally graded TiC-based cermets via combustion synthesis and quasi-isostatic pressing

    NARCIS (Netherlands)

    Martinez Pacheco, M.; Stuivinga, M.E.C.; Carton, E.P.; Katgerman, L.

    2004-01-01

    Experimental results on the preparation of functionally graded TiC-based cermets obtained by combustion synthesis (also known as Self-Propagating High-Temperature Synthesis, SHS) followed by quasi-isostatic (QIP) pressing in a granulate medium are presented. Pellets of TiC-Fe graded cermets are prod

  3. 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

  4. 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.

  5. Characterization of TiC-FeCrMn Cermets Produced by Powder Metallurgy Method

    Directory of Open Access Journals (Sweden)

    Märt Kolnes

    2015-09-01

    Full Text Available TiC-NiMo cermets combine relatively low density with high hardness. Because nickel is known as a toxin and allergen and allergy to nickel is a phenomenon which has assumed growing importance in recent years there has been a flurry of activity to find alternatives to the nickel binder in cermets. It is also the global research and technical development trend in the powder metallurgy cermets industry. In present research TiC-based cermets with FeCrMn binder system were fabricated. Three different sintering conditions were used (vacuum sintering, sinter/HIP and sintering under low Ar pressure. Because of high vapor pressure of manganese different sintering conditions and technologies were investigated to depress the Mn-loss during sintering. Chemical composition of TiC-FeCrMn cermets after different sintering conditions were analyzed by energy-dispersive X-ray spectroscopy (EDS and mechanical properties – hardness and fracture toughness were evaluated on the samples. Results of research showed that Ni-free TiC-based CrMn-steels bonded cermets compare unfavorably with cermets bonded with CrNi austenitic steels in terms of fracture toughness and corrosion resistance. Noticeable Mn-loss during vacuum sintering can be avoided when sintering under low Ar gas pressure.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7364

  6. Effect of magnesium oxide content on oxidation behavior of some superalloy-base cermets

    Science.gov (United States)

    Zaplatynsky, I.

    1975-01-01

    The effect of increasing magnesium oxide (MgO) content on the cyclic oxidation resistance of hot-pressed cermets of MgO in NiCrAlY, MgO in Hoskins-875, MgO in Inconel-702, and MgO in Hastelloy-X was investigated. The cermets with magnesium oxide levels of 5, 10, 20, and 40 vol percent were examined. The cyclic oxidation behavior of these cermets at 1100 and 1200 C in still air was determined by a thermogravimetric method supplemented by X-ray diffraction analysis and light and electron microscopy. In all instances, MgO prevented grain growth in the metallic phase. No evidence of oxidation along interphase boundaries was detected. Cermets of MgO in NiCrAlY and MgO in Hoskins-875 were superior to cermets of MgO in Inconel-702 and MgO in Hastelloy-X. Their oxidation resistance was degraded only when the MgO content was 40 vol percent. The oxidation behavior of MgO-in-Inconel-702 powder cermets containing 5- and 10-vol percent MgO was approximately similar to that of pure Inconel-702 compacts. The 20- and 40-vol percent MgO content reduced the oxidation resistance of MgO-in-Inconel-702 powder cermets relative to that of pure Inconel-702.

  7. 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.

  8. 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.

  9. 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

  10. Investigation of a Cermet Gas-turbine-blade Material of Titanium Carbide Infiltrated with Hastalloy C

    Science.gov (United States)

    Hoffman, Charles A

    1955-01-01

    A cermet composition was investigated as a potential material for gas-turbine blades. Blades of HS-21 alloy were also operated in the engine simultaneously to provide a basis of comparison. The cermet blades survived as long as approximately 312-1/2 hours at about 1500 degrees F with an average midspan centrifugal stress of approximately 11,500 psi. The alloy blade midspan stress was about 15,300 psi. Because of extensive damage to both types of blade due to external causes, a reliable comparison of operating lives could not be made. The cermet blades tended to fail in the airfoil rather than in the base, although the base was the usual location of failure in a prior study of cold-pressed and sintered cermets of other compositions with the same blade shape.

  11. Structural state scale-dependent physical characteristics and endurance of cermet composite for cutting metal

    Energy Technology Data Exchange (ETDEWEB)

    Ovcharenko, V. E., E-mail: ovcharenko.ove45@mail.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055, Russia and Institute of Heavy-Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); Ivanov, Yu. F., E-mail: ivanov.yufi55@mail.ru [Institute of Heavy-Current Electronics SB RAS, Tomsk, 634055, Russia and National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Mohovikov, A. A., E-mail: mohovikov.maa28@rambler.ru [Institute of Heavy-Current Electronics SB RAS, Tomsk, 634055 (Russian Federation); Baohai, Yu, E-mail: baohai.bhyu@imr.ac.cn, E-mail: yanhui.yhzhao@imr.ac.cn; Zhao, Yanhui, E-mail: baohai.bhyu@imr.ac.cn, E-mail: yanhui.yhzhao@imr.ac.cn [Institute of Metal Research, Chinese Academy of Sciences, Wenhua Road 72, 110016 (China)

    2014-11-14

    A structural-phase state developed on the surface of a TiC/Ni–Cr–Al cermet alloy under superfast heating and cooling produced by pulse electron beam melting has been presented. The effect of the surface’s structural state multimodality on the temperature dependencies of the friction and endurance of the cermet tool in cutting metal has been investigated. The high-energy flux treatment of subsurface layers by electron beam pulses in argon-containing gas discharge plasma serves to improve the endurance of metal cutting tools manifold (by a factor of 6), to reduce the friction via precipitation of secondary 200 nm carbides in binder interlayers. It is possible to improve the cermet tool endurance for cutting metal by a factor of 10–12 by irradiating the cermet in a reactive nitrogen-containing atmosphere with the ensuing precipitation of nanosize 50 nm AlN particles in the binder interlayers.

  12. 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.

  13. 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

  14. Characterization of Nanometric-Sized Carbides Formed During Tempering of Carbide-Steel Cermets

    OpenAIRE

    Matus K.; Pawlyta M.; Matula G.; Gołombek K.

    2016-01-01

    The aim of this article of this paper is to present issues related to characterization of nanometric-sized carbides, nitrides and/or carbonitrides formed during tempering of carbide-steel cermets. Closer examination of those materials is important because of hardness growth of carbide-steel cermet after tempering. The results obtained during research show that the upswing of hardness is significantly higher than for high-speed steels. Another interesting fact is the displacement of secondary ...

  15. 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.

  16. Evaluation of cerium oxide coated Cu cermets as inert anodes for aluminum electrowinning

    Energy Technology Data Exchange (ETDEWEB)

    1992-08-01

    Cu/NiFe{sub 2}O{sub 4} cermets were evaluated, with and without an in-situ deposited CEROX (TM; cerium oxide) coating, in 100 h laboratory A1 electrowinning tests. Bath ratio and current density were varied between tests and corrosion was determined by contamination of the aluminum and cryolite by cermet components (Cu, Fe, and Ni). Higher bath ratios of 1.5 to 1.6 led to less corrosion and thicker CEROX coatings. Lower current densities led to slightly less corrosion but much less oxidation of the Cu cermet substrate. At identical test conditions, the corrosion of the CEROX coated cermets was 1/7 that of an uncoated cermet. Corrosion was increased in CEROX coated cermets tested under unsaturated alumina conditions. The electrical conductivity of the CEROX coating was measured to be {approximately}0.2 ohm{sup {minus}1}cm{sup {minus}1}, resulting in a slight voltage penalty, depending on the thickness of the coating.

  17. 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).

  18. Oxidation behavior of nickel-chromium-aluminum-yttrium - Magnesium oxide and nickel-chromium-aluminum-yttrium - zirconate type of cermets

    Science.gov (United States)

    Zaplatynsky, I.

    1976-01-01

    The 1100 and 1200 C cyclic oxidation resistance of dense Ni-Cr-Al-Y - MgO, Ni-Cr-Al-Y - CaZrO3, Ni-Cr-Al-Y - SrZrO3, Ni-Cr-Al-Y - MgZro3 cermets and a 70 percent dense Ni-Cr-Al-Y developmental material was determined. The cermets contained 60 and 50 volume percent of Ni-Cr-Al-Y which formed a matrix with the oxide particles imbedded in it. The cermets containing MgO were superior to cermets based on zirconates and to the porous Ni-Cr-Al-Y material.

  19. 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

  20. Influence of WC addition on the microstructure and mechanical properties of NbC-Co cermets

    Energy Technology Data Exchange (ETDEWEB)

    Huang, S.G. [Department of Metallurgy and Materials Engineering (MTM), Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee (Belgium); Li, L. [School of Material Science and Engineering, Shanghai University, 149 Yanchang Road, Shanghai 200072 (China); Van der Biest, O. [Department of Metallurgy and Materials Engineering (MTM), Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee (Belgium); Vleugels, J. [Department of Metallurgy and Materials Engineering (MTM), Katholieke Universiteit Leuven, Kasteelpark Arenberg 44, B-3001 Heverlee (Belgium)]. E-mail: Jozef.Vleugels@mtm.kuleuven.be

    2007-03-14

    NbC-24.5 wt.% Co cermets with up to 30 wt.% WC were obtained by solid state hot pressing at 1300 {sup o}C under a pressure of 45 MPa for 10 min and pressureless liquid phase sintering at 1360 {sup o}C for 60 min. The effect of WC addition on the microstructure and mechanical properties of NbC-Co based cermets was investigated. The hot pressed cermets exhibited interconnected and irregular niobium carbide (NbC) or (Nb,W)C grains, whereas the shape of the NbC grains changed from faceted with rounded corners to spherical, as the WC content increased in the pressureless sintered cermets. The undissolved WC increased with increasing WC addition. A clear core/rim structure was observed in the hot pressed cermets with 10-30 wt.% WC additions, whereas this structure was gradually eliminated when pressureless sintering. The hardness remains nearly constant whereas the fracture toughness slightly increases with increasing WC addition. The dissolution of WC in the Co binder and NbC grains, as well as the formation of a solid solution (Nb,W)C phase were supported by thermodynamic calculations.

  1. Phase evolution, microstructure and properties of Y2O3-doped TiCN-based cermets

    Institute of Scientific and Technical Information of China (English)

    孙万昌; 张佩; 李攀; 佘晓林; 赵坤

    2015-01-01

    Y2O3-doped TiCN-based cermets were prepared by pressureless sintering with powders TiC, TiN, Ni, etc. as main starting materials. The influence of sintering processes and Y2O3on properties of TiCN-based cermets were investigated. The phase composi-tion of TiCN-based cermets almost had no change with Y2O3 addition. The fullly densified TiCN-based cermets were achieved by P-2 sitering process. The fracture surface showed lots of small dimples caused by hard phase particles pulling-off, and the left hard phase particles were attached to the arborous dendritic matrix. The Vickers hardness, fracture toughness and bending strength of TiCN-based cermets increased firstly and then decreased with the increment of Y2O3 content. When Y2O3 contents were both 0.8 wt.%, compared with the P-1 sintered samples, the Vickers hardness, fracture toughness and bending strength of the P-2 sintered sam-ples reached 14.84 GPa, 8.66 MPa·m1/2 and 660.4 MPa, which were increased by 7.9%, 6.1% and 45.8%, respectively.

  2. 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.

  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. Microstructural Characterization of Cermet Cladding Developed Through Microwave Irradiation

    Science.gov (United States)

    Gupta, Dheeraj; Sharma, Apurbba Kumar

    2012-10-01

    In the present work, cladding of hardfacing WC10Co2Ni powder on austenitic stainless steel has been developed through a novel processing technique. The clads were developed using microwave hybrid heating. The clad of average thickness ~2 mm has been developed through the exposure of microwave radiation at frequency 2.45 GHz and power 900 W for the duration of 360 s. The developed clads were characterized using field emission scanning electron microscope, X-ray elemental analysis, X-ray diffraction, and measurement of Vicker's microhardness. The microstructure study of the clad showed good metallurgical bonding with substrate and revealed that clads are free from any visible interface cracking. Clads were formed with partial dilution of a thin layer of the substrate. The cermet microstructure mainly consists of relatively soft metallic matrix phase and uniformly distributed hard carbide phase with skeleton-like structure. The developed clads exhibit an average microhardness of 1064 ± 99 Hv. The porosity of developed clad has been significantly less at approximately 0.89%.

  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. 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.

  7. 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.

  8. Preparation of ultrafine Ti (C, N)-based cermet using oxygen-rich powders

    Institute of Scientific and Technical Information of China (English)

    FENG Ping; HE Yue-hui; XIONG Wei-hao; XIAO Yi-feng

    2005-01-01

    The availability using oxygen-rich powders to prepare ultrafine Ti(C,N)-based cermets was investigated. The deoxidation process, denitrification phenomenon and the effect of deoxidation on microstructure and mechanical properties of sintered samples were discussed, respectively. The results show that oxygen in the samples prepared even with high oxygen contained in starting powders can be almost completely cleaned away through suitable sintering process. The ultrafine oxygen-rich powders have a significant effect on microstructure, which promotes the formation of white core phase. A ultrafine Ti(C,N)-based cermet with mean particle size of 0. 30 μm, uniform microstructure and excellent mechanical properties is successfully prepared. It is also found that there exists severe denitrification phenomenon in the preparation process of ultrafine Ti(C,N)-based cermet.

  9. Preparation and electrical properties of dense micro-cermets made of nickel ferrite and metallic copper

    Science.gov (United States)

    Baco-Carles, Valérie; Pasquet, Isabelle; Laurent, Véronique; Gabriel, Armand; Tailhades, Philippe

    2009-08-01

    Dense micro-cermets made of nickel ferrites and copper micrometric particles were obtained from partial reduction under hydrogenated atmosphere at 350 °C of mixed copper nickel ferrites, and sintering in nitrogen at 980 °C. The small copper particles are homogeneous in size and well dispersed in the spinel oxide matrix. No exudation of copper metal was observed after sintering. The micro-cermets prepared are semi-conducting materials with electrical conductivity lying from 44 to 130 S/cm at 980 °C. Their overall characteristics make them interesting for inert anodes dedicated to aluminium electrolysis in melted cryolite.

  10. Induction Heating Model of Cermet Fuel Element Environmental Test (CFEET)

    Science.gov (United States)

    Gomez, Carlos F.; Bradley, D. E.; Cavender, D. P.; Mireles, O. R.; Hickman, R. R.; Trent, D.; Stewart, E.

    2013-01-01

    Deep space missions with large payloads require high specific impulse and relatively high thrust to achieve mission goals in reasonable time frames. Nuclear Thermal Rockets (NTR) are capable of producing a high specific impulse by employing heat produced by a fission reactor to heat and therefore accelerate hydrogen 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. The primary concern is the mechanical failure of fuel elements due to large thermal gradients; therefore, high-melting-point ceramics-metallic matrix composites (cermets) are one of the fuels under consideration as part of the Nuclear Cryogenic Propulsion Stage (NCPS) Advance Exploration System (AES) technology project at the Marshall Space Flight Center. The purpose of testing and analytical modeling is to determine their ability to survive and maintain thermal performance in a prototypical NTR reactor environment of exposure to hydrogen at very high temperatures and obtain data to assess the properties of the non-nuclear support materials. The fission process and the resulting heating performance are well known and do not require that active fissile material to be integrated in this testing. A small-scale test bed; Compact Fuel Element Environmental Tester (CFEET), designed to heat fuel element samples via induction heating and expose samples to hydrogen is being developed at MSFC to assist in optimal material and manufacturing process selection without utilizing fissile material. This paper details the analytical approach to help design and optimize the test bed using COMSOL Multiphysics for predicting thermal gradients induced by electromagnetic heating (Induction heating) and Thermal Desktop for radiation calculations.

  11. 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.

  12. Characterization of Nanometric-Sized Carbides Formed During Tempering of Carbide-Steel Cermets

    Directory of Open Access Journals (Sweden)

    Matus K.

    2016-06-01

    Full Text Available The aim of this article of this paper is to present issues related to characterization of nanometric-sized carbides, nitrides and/or carbonitrides formed during tempering of carbide-steel cermets. Closer examination of those materials is important because of hardness growth of carbide-steel cermet after tempering. The results obtained during research show that the upswing of hardness is significantly higher than for high-speed steels. Another interesting fact is the displacement of secondary hardness effect observed for this material to a higher tempering temperature range. Determined influence of the atmosphere in the sintering process on precipitations formed during tempering of carbide-steel cermets. So far examination of carbidesteel cermet produced by powder injection moulding was carried out mainly in the scanning electron microscope. A proper description of nanosized particles is both important and difficult as achievements of nanoscience and nanotechnology confirm the significant influence of nanocrystalline particles on material properties even if its mass fraction is undetectable by standard methods. The following research studies have been carried out using transmission electron microscopy, mainly selected area electron diffraction and energy dispersive spectroscopy. The obtained results and computer simulations comparison were made.

  13. Evaluation of Tests for Cermets as Components of Heat-Resistant Materials.

    Science.gov (United States)

    Specimens of one cermet composition for flexural tests were received. These specimens K 152B (nominal composition of 70% titanium carbide - 30...nickel) were substituted for K 162B (nominal composition of 62% titanium carbide - 8% columbium - 25% nickel - 5% molybdenum). Equipment was designed for

  14. 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

  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. 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...

  17. Evaluation of cerium oxide coated Cu cermets as inert anodes for aluminum electrowinning. Final report, August 1990--March 1992

    Energy Technology Data Exchange (ETDEWEB)

    1992-08-01

    Cu/NiFe{sub 2}O{sub 4} cermets were evaluated, with and without an in-situ deposited CEROX (TM; cerium oxide) coating, in 100 h laboratory A1 electrowinning tests. Bath ratio and current density were varied between tests and corrosion was determined by contamination of the aluminum and cryolite by cermet components (Cu, Fe, and Ni). Higher bath ratios of 1.5 to 1.6 led to less corrosion and thicker CEROX coatings. Lower current densities led to slightly less corrosion but much less oxidation of the Cu cermet substrate. At identical test conditions, the corrosion of the CEROX coated cermets was 1/7 that of an uncoated cermet. Corrosion was increased in CEROX coated cermets tested under unsaturated alumina conditions. The electrical conductivity of the CEROX coating was measured to be {approximately}0.2 ohm{sup {minus}1}cm{sup {minus}1}, resulting in a slight voltage penalty, depending on the thickness of the coating.

  18. Compatibility study between U-UO2 cermet fuel and T91 cladding

    Science.gov (United States)

    Mishra, Sudhir; Kaity, Santu; Khan, K. B.; Sengupta, Pranesh; Dey, G. K.

    2016-12-01

    Cermet is a new fuel concept for the fast reactor system and is ideally designed to combine beneficial properties of both ceramic and metal. In order to understand fuel clad chemical compatibility, diffusion couples were prepared with U-UO2 cermet fuel and T91 cladding material. These diffusion couples were annealed at 923-1073 K for 1000 h and 1223 K for 50 h, subsequently their microstructures were examined using scanning electron microscope (SEM), X-ray energy dispersive spectroscope (EDS) and electron probe microanalyser (EPMA). It was observed that the interaction between the fuel and constituents of T91 clad was limited to a very small region up to the temperature 993 K and discrete U6(Fe,Cr) and U(Fe,Cr)2 intermetallic phases developed. Eutectic microstructure was observed in the reaction zone at 1223 K. The activation energy for reaction at the fuel clad interface was determined.

  19. Microwave Sintering of A12O3-ZrO2-WC-Co Cermets

    Institute of Scientific and Technical Information of China (English)

    GU Tianben; LU hongzhi

    2011-01-01

    Composite powders of nanocrystalline WC-10Co (15wt%), Y2O3 (8mo1%) stabilized nanocrystalline ZrO2 (30wt%), industrial cobalt powder (4.5wt%) and submicron A12O3 (55wt%)composite powders were fabricated by high-energy ball-milling process. The nanocomposite powders were consolidated by microwave sintering process at temperature ranged 1300 ℃-1550 ℃ for 15 min,respectively. The optimum consolidation conditions, such as temperature, were researched during microwave sintering process. Vickers Hardness of the consolidated cermets was measured by using a Vickers indentation test, and density of specimens was also determined by Archimedes' principle.Microwave sintering process could not only increase the density of A12O3-ZrO2-WC-Co cermets and reduce the porosity, but also inhibit abnormal grain growth.

  20. Comparative study on ammonia oxidation over Ni-based cermet anodes for solid oxide fuel cells

    Science.gov (United States)

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

    2016-02-01

    In the current work, we investigate the performance of solid oxide fuel cells (SOFCs) with Ni‒yttria-stabilized zirconia (Ni-YSZ) and Ni‒gadolinia-dope ceria (Ni-GDC) cermet anodes fueled with H2 or NH3 in terms of the catalytic activity of ammonia decomposition. The cermet of Ni-GDC shows higher catalytic activity for ammonia decomposition than Ni-YSZ. In response to this, the performance of direct NH3-fueled SOFC improved by using Ni-GDC anode. Moreover, we observe further enhancement in the cell performance and the catalytic activity for ammonia decomposition with applying Ni-GDC anode synthesised by the glycine-nitrate combustion process. These results reveal that the high performance of Ni-GDC anode for the direct NH3-fueled SOFC results from its mixed ionic-electronic conductivity as well as high catalytic activity for ammonia decomposition.

  1. Microstructural and Optical Absorption Properties of Cu-MgF2 Nanoparticle Cermet Film

    Institute of Scientific and Technical Information of China (English)

    孙兆奇; 孙大明; 阮图南

    2002-01-01

    We examine the microstructural and optical absorption spectra of 10-30 vol% Cu-MgF2 nanoparticle cermet films prepared by co-evaporation in vacuum. The results show that the Cu-MgF2 cermet films are mainly composed of the amorphous MgF2 matrix with embedded fcc Cu nanoparticles of average size 12-24 nm. The results also show that the optical absorption of the films decreases as the wavelength increases in the range of 200-800nm. The surface plasmon resonance absorption peaks of Cu nanoparticles in 10, 20 and 30 vo1% Cu-MgF2 films appear at 578, 588 and 606nm, respectively. The interband transition absorption of Cu starts from 590nm downwards.Based on the Maxwell-Garnett theory, the experimental optical absorption properties of the films have been quantitatively evaluated.

  2. 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.

  3. A modular gas-cooled cermet reactor system for planetary base power

    Science.gov (United States)

    Jahshan, Salim N.; Borkowski, Jeffrey A.

    1993-01-01

    Fission nuclear power is foreseen as the source for electricity in planetary colonization and exploration. A six module gas-cooled, cermet-fueled reactor is proposed that can meet the design objectives. The highly enriched core is compact and can operate at high temperature for a long life. The helium coolant powers six modular Brayton cycles that compare favorably with the SP-100-based Brayton cycle.

  4. 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

  5. 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.

  6. 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.

  7. Investigation on microstructures of NiO-YSZ composite and Ni-YSZ cermet for SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Talebi, Tahereh; Sarrafi, Mohammad Hassan; Haji, Mohsen; Raissi, Babak; Maghsoudipour, Amir [Materials and Energy Research Center, Karaj, Tehran 14155-4777 (Iran)

    2010-09-15

    NiO-YSZ composites and Ni-YSZ cermets were successfully performed for solid oxide fuel cell applications. These composites must have enough porosity and appropriate microstructure for transferring the fuel gases. In this study, ball-milling was used as a simple, cost-effective method for the purpose of mixing the raw materials. The homogeneity of NiO-YSZ composites was examined by Map mode of SEM. NiO-YSZ composites were reduced at the high temperature under the controlled atmosphere to fabricate Ni-YSZ cermet. Variations in the anode phases were investigated by XRD and microstructure and porosity of composites were observed by SEM. Effective parameters like temperatures and the amount of pore former were investigated on open porosity, bulk density, electrical conductivity as well as electrochemical impedance of NiO-YSZ composites and Ni-YSZ cermet. A thin layer of YSZ was deposited by EPD as an electrolyte on NiO-YSZ composites which had various amount of open porosity, to study its effect on the performance of semi-cells by electrochemical impedance. (author)

  8. 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.

  9. 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.

  10. Investigation of the laser engineered net shaping process for nanostructured cermets

    Science.gov (United States)

    Xiong, Yuhong

    Laser Engineered Net Shaping (LENSRTM) is a solid freeform fabrication (SFF) technology that combines high power laser deposition and powder metallurgy technologies. The LENSRTM technology has been used to fabricate a number of metallic alloys with improved physical and mechanical material properties. The successful application provides a motivation to also apply this method to fabricate non-metallic alloys, such as tungsten carbide-cobalt (WC-Co) cermets in a timely and easy way. However, reports on this topic are very limited. In this work, the LENSRTM technology was used to investigate its application to nanostructured WC-Co cermets, including processing conditions, microstructural evolution, thermal behavior, mechanical properties, and environmental and economic benefits. Details of the approaches are described as follows. A comprehensive analysis of the relationships between process parameters, microstructural evolution and mechanical properties was conducted through various analytical techniques. Effects of process parameters on sample profiles and microstructures were analyzed. Dissolution, shape change and coarsening of WC particles were investigated to study the mechanisms of microstructural evolution. The thermal features were correlated with the microstructure and mechanical properties. The special thermal behavior during this process and its relevant effects on the microstructure have been experimentally studied and numerically simulated. A high-speed digital camera was applied to study the temperature profile, temperature gradient and cooling rate in and near the molten pool. Numerical modeling was employed for 3D samples using finite element method with ADINA software for the first time. The validated modeling results were used to interpret microstructural evolution and thermal history. In order to fully evaluate the capability of the LENSRTM technology for the fabrication of cermets, material properties of WC-Co cermets produced by different powder

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

    Energy Technology Data Exchange (ETDEWEB)

    Primdahl, S.

    1999-08-01

    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 deg. C to 1000 deg. C, and the most important technological parameters are the polarization resistance and the long-term stability. The polarization resistance can be measured by a number of techniques, in the present work impedance spectroscopy has been used extensively. By impedance spectroscopy limiting processes in the anode polarization resistance may often be separated and characterized individually, provided they have a reasonable separation in time constants. Three limiting processes are recognized in impedance spectra obtained on technological Ni/YSZ cermet anodes characterized against a stable reference electrode atmosphere. By parameter studies and illustrative experiments, the two contributions at low and medium frequency have been identified as gas conversion and diffusion limitations, respectively. Both of these effects are concentration limitations relating to the inefficient exchange of fuel gas in the test setup outside the porous cermet. A test setup geometry where these concentration effects are avoided for high-performance electrodes is recommended. The high frequency limitation is demonstrated to relate to the cermet structure. The dependence on gas composition, temperature, adsorbed species (sulfur), isotopes (H/D), sintering temperature and cermet thickness is investigated. Despite these studies and several similar studies by others, the exact chemical or physical nature of the limiting step has not been incontestably identified. However, these is a general consensus in literature about the hydrogen oxidation process taking place on or near to the triple phase boundary (TPB) line, where open gas-filled pores, the continuous electrolyte phase (oxide ion cunductor) and the continuous Ni phase (electronic conductor) meet. The physical thickness

  12. 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.

  13. 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.)

  14. A New-type of Cermets Cutter with Nano-TiN Addition: Microstructure, Mechanical and Cutting Properties

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The microstructure and mechanical properties of a new- type of cermets cutter ( tool A ) with nano- TiN modification and its cutting properties in cutting gray cast iron are investigated.SEM and TEM observations of the microstructure of the above material reveal that nano- TiN modified cermets possess a finer microstructure than conventional cermets .In the cutting tests, for comparison, cemented carbide cutter ( YG8 , tool B) was also utilized.The cutting results show that the cutting properties of tool A are superior to those of tool B.It is also found that the predominant failure mode of tool A is normal wear and micro-spalling under lower cutting quantities, and that chipping occurs under higher cutting quantities.SEM analysis reveals that cohesion, oxidation and diffusion wear become very apparent at a higher cutting speed.On the contrary, grain wear also exists but is not apparent.

  15. EFFECT OF BRAZING TIME ON TiC CERMET/IRON JOINT BRAZED WITH Ag-Cu-Zn FILLER METAL

    Institute of Scientific and Technical Information of China (English)

    L.X. Zhang; J.C. Feng; Z.R. Li; H.J. Liu

    2004-01-01

    The brazing of TiC cermet to iron was carried out at 1223K for 5-20min using Ag-Cu-Zn filler metal. The formation phase and interface structure of the joints were investigated by electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the joint strength was tested by shearing method. The results showed: there occurred three new formation phases, Cu(s.s), FeNi and Ag(s.s) in TiC cermet/iron joint. The interface structure was expressed as TiC cermet/Cu(s.s)+FeNi/Ag(s.s)+a little Cu(s.s)+a little FeNi/Cu(s.s)+ FeNi/iron. With brazing time increasing, there appeared highest shear strength of the joints, the value of which was up to 252.2MPa when brazing time was 10min.

  16. 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.

  17. The anomalous behaviour of Ag-Al sub 2 O sub 3 Cermet electroformed devices

    CERN Document Server

    Khan, M S R

    2003-01-01

    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-Al sub 2 O sub 3 /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 approx 4 x 10 sup - sup 6 torr. The formed characteristics were explained on the basis of filamentary model.

  18. 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.

  19. 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.

  20. TiC0.5N0.5-Based Cermets with Varied Amounts of Si3N4 Nanopowders Prepared by Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Changchun Lv

    2015-01-01

    Full Text Available TiCN-based cermets with varied fractions of Si3N4 nanopowder (0–5 wt.% were prepared by spark plasma sintering. The microstructural and mechanical properties of these cermets were investigated. In general, with increasing addition amount of Si3N4 nanopowder the relative density as well as mechanical properties of the as-prepared TiCN cermets increased first and then decreased. The samples containing 2 wt.% Si3N4 nanopowder presented the best performance with the relative density of about 98%, bending strength of 1000 MPa, and Vickers microhardness of about 1810 HV10.

  1. 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 ℃.

  2. 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.

  3. Electrical resistivity of NiFe2O4 ceramic and NiFe2O4 based cermets

    Institute of Scientific and Technical Information of China (English)

    田忠良; 赖延清; 李劼; 张刚; 刘业翔

    2004-01-01

    NiFe2O4 ceramic and NiFe2O4 based cermets, expected to be used as the inert anodes in aluminum electrolysis, were prepared and their electrical resistivities were measured at different temperatures. The effects of temperature and composition on their electrical resistivities were investigated. The results indicate that the electrical resistivities of NiFe2O4 based cermets mainly depend on temperature, resistivity of ceramic matrix, composition and dispersion of the metal phase among ceramic matrix. The electrical resistivity of NiFe2O4 ceramic decreases from 10. 094 Ω · cm to 0. 475 Ω · em with increasing temperature from 573 K to 1 233 K. The electrical resistivities of NiFe2O4 based cermets are greatly lowered, but decrease with increasing the temperature with similar trend compared to that of NiFe2O4 ceramic. The resistivities of NiFe2O4 based cermets containing 5 % Ni, 5 % Cu and 5 % CuNi alloy are 0. 046 8, 0.066 8 and 0. 0532 Ω · cm at 1 233 K, respectively, which are all acceptable as inert anode materials compared to that of the current carbon anode used for aluminum electrolysis.

  4. 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%.

  5. 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

    In-situ reduction of Ni cermet anodes produces the porosity and influences the microstructure, performance and stability of the anodes. The impact on initial performance, stability and microstructure of two different reduction procedures currently in use at DTU Energy Conversion with reduction te...

  6. 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.

  7. 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.

  8. 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.)

  9. Production of small uranium dioxide microspheres for cermet nuclear fuel using the internal gelation process

    Energy Technology Data Exchange (ETDEWEB)

    Collins, Robert T [ORNL; Collins, Jack Lee [ORNL; Hunt, Rodney Dale [ORNL; Ladd-Lively, Jennifer L [ORNL; Patton, Kaara K [ORNL; Hickman, Robert [NASA Marshall Space Flight Center, Huntsville, AL

    2014-01-01

    The U.S. National Aeronautics and Space Administration (NASA) is developing a uranium dioxide (UO2)/tungsten cermet fuel for potential use as the nuclear cryogenic propulsion stage (NCPS). The first generation NCPS is expected to be made from dense UO2 microspheres with diameters between 75 and 150 m. Previously, the internal gelation process and a hood-scale apparatus with a vibrating nozzle were used to form gel spheres, which became UO2 kernels with diameters between 350 and 850 m. For the NASA spheres, the vibrating nozzle was replaced with a custom designed, two-fluid nozzle to produce gel spheres in the desired smaller size range. This paper describes the operational methodology used to make 3 kg of uranium oxide microspheres.

  10. 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.

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

    Science.gov (United States)

    Stewart, Mark E.; Schnitzler, Bruce G.

    2015-01-01

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

  12. Combustion Synthesis of TiC-TiB2-Based Cermets from Elemental Powders

    Directory of Open Access Journals (Sweden)

    Jun Yu

    2011-01-01

    Full Text Available TiC-TiB2-based cermets with Ni binder were fabricated using combustion synthesis assisted by pseudohot isostatic pressing by heating the compacted powder mixture to approximately 700°C. The effects of composition on microstructure and hardness of the synthesized samples were investigated. The samples exhibited finer microstructure and higher hardness as TiC/TiB2 volume ratio increased and as Ni increased up to 30 vol%. A relatively high hardness value of 1950 HV was obtained for TiC-TiB2-Ni(52.5/17.5/30 vol%. However, the transverse rupture strength and the modulus of elasticity values were not very high. This may be due to weak bonding strength of the interface between hard phases and Ni binder and/or insufficient densification of the samples.

  13. Effect of Reaction Layers on the Residual Stress of the Brazed TiC Cermets/Steel Joints

    Institute of Scientific and Technical Information of China (English)

    Lixia Zhang; Jicai Feng

    2009-01-01

    For the first time, considering the effect of reaction layers, numerical simulation calculation of residual stress on brazed TiC cermets/steel joint was studied by finite element method (FEM). The calculation results show that, when the joint is brazed at 1123 K for 300 s (low brazing parameters), the maximum shear stress value occurs on (Cu, Ni) layer near TiC cermets, which is 92.16 MPa as the temperature is 300 K. When the joint is brazed at 1273 K for 900 s (high brazing parameters), the maximum shear stress value occurs on (Cu,Ni)+(Fe, Ni) layer, which is 39.18 MPa as the temperature is 300 K. The fracture sites of the joints obtained from numerical simulation calculation accord with experimental results.

  14. Influence of preparation process on sintering behavior and mechanical properties of ultrafine grained Ti(C, N)-based cermets

    Institute of Scientific and Technical Information of China (English)

    FENG Ping; HE Yue-hui; XIAO Yi-feng; LIU Wen-jun; XIONG Wei-hao

    2007-01-01

    The influences of forming and sintering processes on distortion, cracking as well as mechanical properties of sintered bodies of ultrafine grained Ti(C, N)-based cermets were investigated. The results show that lubricant is indispensable to fabrication of ultrafine Ti(C, N)-based cermets, however, with low binder content in powder mixture, the lubrication action of paraffin is attenuated. A appropriate level of 2% (mass fraction) paraffin is determined for a cermet with binder content of 36% (mass fraction). It is also found that the influence of compaction pressure on distortion and cracking of sintered bodies presents a complex relationship. A relatively lower or higher compaction pressure, less than 100 MPa and more than 400 MPa respectively, favors uniform density distribution in green compact. The heating rate of sintering should be strictly controlled. Too fast heating rate results in enclosed pores to burst and forms large size pores in sintering body. A heating rate of 3 ℃/min is recommended.

  15. Effect of metallic content on mechanical property of Ni/(10NiO-NiFe2O4) cermets

    Institute of Scientific and Technical Information of China (English)

    LI Jie; ZHANG Gang; YE Shao-long; LAI Yan-qing; TIAN Zhong-liang; SUN Xiao-gang

    2006-01-01

    Ni/ (10NiO-NiFe2O4 ) cermets were fabricated by using cold pressing-sintering method. The phase composition and effect of metallic content on the mechanical properties such as bending strength, Vickers' hardness,fracture toughness and thermal shock resistance were studied. The results show that the cermets consist of Ni, NiO and NiFe2O4. Within the range of metallic content from 0 to 17% (mass fraction), the relative density decreases with the increase of metallic content and the decrease of sintering temperature, Vickers' hardness decreases from 7 097 MPa to 4 814 MPa and the bending strength increases from 110 MPa to 157 MPa, and the fracture toughness mal shock testing falls sharply as the thermal shock temperature difference is above 200℃. The cermets samples,whose metallic content is 10% and 15%, respectively, exhibit promising property of thermal shock resistance at 960 ℃ with six cycles of heating and quenching testing.

  16. 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.

  17. 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.

  18. Microstructure and characteristics of high dimension brazed joints of cermets and steel

    Directory of Open Access Journals (Sweden)

    J. Nowacki

    2009-12-01

    Full Text Available Purpose: In the article a state of the question concerning stresses in brazing joints of different physical and mechanical properties was appraised as well as possibility of their decrease due to use of different techniques from technological experiments to numerical methods. Evaluation of microstructure and mechanical properties of large dimensional vacuum brazed joints of WC – Co and Ferro Titanit Nicro 128 sinters and precipitation hardened stainless steel of 14 –5 PH (X5CrNiMoCuNb14-5 using copper and silver – copper as the brazing filler metal.Design/methodology/approach: Microscopic examinations with the use of scanning electron microscope (SEM were performed to establish microstructure and diffusion influences on creation of intermetallic phases in the joint. Shear strength Rt and tensile strength Rm of the joints have been defined. It 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 the cermets and brazing filler metal elements and creation of intermetallic in the joint. It can have an unfavourable influence on ductility and quality of the joint.Findings: Results of numerical calculations of two-dimensional models of brazed joints for different sizes of surfaces brazed at a constant width of solder gap are presented. Particular attention was paid to stresses occurring in joints of large brazing surfaces.Results of the investigate proved that joints microstructure and mechanical properties depend on filler and parent materials, diffusion process during brazing, leading to exchange of the cermets components and filler metal as well as joint geometry (mainly gap thickness.Practical implications: The results have been applied in surfaces are used in large dimension spinning nozzles of a die for polyethylene granulation, in that

  19. 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.

  20. Effect of Mo/B atomic ratio on the properties of Mo{sub 2}NiB{sub 2}-based cermets

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Lang; Li, XiaoBo; Zhang, Dan; Yi, Li; Gao, XiaoQing [Xiangtan Univ. (China). School of Mechanical Engineering; Xiangtan Univ. (China). Key Laboratory of Materials Design and Preparation Technology of Hunan Province

    2015-05-15

    Using three elementary substances, Mo, Ni, and amorphous B as raw materials, four series of Mo{sub 2}NiB{sub 2}-based cermets with the Mo/B atomic ratio ranging from 0.9 to 1.2 were successfully prepared via reaction sintering. The effect of Mo/B atomic ratio on the microstructure and properties was studied for the cermets. The results indicate that there is a strong correlation between the Mo/B atomic ratio and properties. The transverse rupture strength of the cermets increases with an increase in Mo/B ratio and shows a maximum value of 1 872 MPa at an Mo/B atomic ratio of 1.1 and then decreases with increasing Mo/B atomic ratio. The hardness and the corrosion resistance of the cermets increase monotonically with an increase in Mo/B atomic ratio. In Mo-rich cermets with an atomic ratio of Mo/B above 1.1, a small amount Ni-Mo intermetallic compound is found precipitated at the interface of Mo{sub 2}NiB{sub 2} grains.

  1. Phase Evolution in Boride-Based Cermets and Reaction Bonding onto Plain Low Carbon Steel Substrate

    Science.gov (United States)

    Palanisamy, B.; Upadhyaya, A.

    2012-04-01

    Reaction sinter bonding is a process that aims to bond two materials for improvement in properties through reactive sintering technique. The process has been effectively used to sinter hard materials like borides in situ which not only possess excellent oxidation resistance, good corrosion resistance but also resistant to abrasive wear. Sinter bonding is a unique surface modification process achieved through powder metallurgy and is competent with other techniques like boronizing sintering and sinter-brazing since it eliminates the additional operations of heat treatment and assembly and removes the inherent setbacks with these processes. This study focuses on identifying the phase evolution mechanism using characterization tools like x-ray diffractometry and energy dispersive spectroscopy and study of sinter bonding of the boron containing precursors (Mo-Cr-Fe-Ni-FeB-MoB) onto plain carbon steel. A microstructure containing Fe-based matrix dispersed with complex borides develops with temperature in the tape cast sheets. A fivefold increase in hardness between plain carbon steel in wrought condition and sinter bonded steel was observed. The multilayer consisted of a reaction zone adjacent to the interface and was investigated with the composition profile and hardness measurements. A model of sinter bonding between the cermet and the steel has also been proposed.

  2. 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.

  3. 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.

  4. A Combined Neutronic-Thermal Hydraulic Model of CERMET NTR Reactor

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-02-01

    Abstract. Two different CERMET fueled Nuclear Thermal Propulsion reactors were modeled to determine the optimum coolant channel surface area to volume ratio required to cool a 25,000 lbf rocket engine operating at a specific impulse of 940 seconds. Both reactor concepts were computationally fueled with hexagonal cross section fuel elements having a flat-to-flat distance of 3.51 cm and containing 60 vol.% UO2 enriched to 93wt.%U235 and 40 vol.% tungsten. Coolant channel configuration consisted of a 37 coolant channel fuel element and a 61 coolant channel model representing 0.3 and 0.6 surface area to volume ratios respectively. The energy deposition from decelerating fission products and scattered neutrons and photons was determined using the MCNP monte carlo code and then imported into the STAR-CCM+ computational fluid dynamics code. The 37 coolant channel case was shown to be insufficient in cooling the core to a peak temperature of 3000 K; however, the 61 coolant channel model shows promise for maintaining a peak core temperature of 3000 K, with no more refinements to the surface area to volume ratio. The core was modeled to have a power density of 9.34 GW/m3 with a thrust to weight ratio of 5.7.

  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

    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.

  6. Effect of adding methods of metallic phase on microstructure and thermal shock resistance of Ni/(90NiFe2O4-10NiO) cermets

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Ball mixing and electroless plating were respectively used as the adding methods of metallic phase to prepare Ni/(90NiFe2O4-10NiO) cermets for the inert anode in aluminum electrolysis. The microstructure and thermal shock resistance of cermet samples were studied. The results show that, for the samples prepared by ball mixing method, aggregation of metallic phase is found in either the green blocks or sintered samples and the extent of aggregation increases with the increase of metal content. For 6.5Ni/(90NiFe2O4-10NiO) cermets prepared with electroless plating method, the homogeneous and fine metallic particles are found in either the green compacts or sintered samples, but the relative density and thermal shock residual strength decrease by 3% and 28%-58% respectively, compared with samples prepared with ball mixing method.

  7. Tribological performance evaluation of tungsten carbide-based cermets and development of a fracture mechanics wear model

    Energy Technology Data Exchange (ETDEWEB)

    Bhagat, R.B. [Pennsylvania State Univ., State College, PA (United States). Applied Research Lab.; Conway, J.C. Jr. [Pennsylvania State Univ., State College, PA (United States). Applied Research Lab.; Amateau, M.F. [Pennsylvania State Univ., State College, PA (United States). Applied Research Lab.; Brezler, R.A. III [Pennsylvania State Univ., State College, PA (United States). Applied Research Lab.

    1996-12-15

    Tungsten carbide tools may exhibit sudden brittle fracture at high stresses such as are encountered in shear and slitter knives. This has limited the use of tungsten carbide tools to certain applications in spite of their high hardness and wear resistance. The objective of this investigation is to evaluate the tribological performance of selected cermets and develop a fracture mechanics wear model. Six compositions of WC-Co materials (Co ranging from 4 to 30% by weight) with or without TiC, NbC, TaC, or Mo{sub 2}C were selected for relating wear modes of these tool materials to pertinent mechanical properties such as fracture toughness and hardness. The influence of mechanical properties such as Young`s modulus, hardness, fracture toughness, modulus of rupture, and Weibull modulus on wear rates and wear modes of the selected materials is presented and discussed. The major mechanisms of wear in WC-Co materials are discussed as they apply to the development of suitable relationships between wear and mechanical properties. The wear process is by the transfer of steel from the ring to the cemented carbide block specimens, initiation of mode I cracks normal to the mating surface, propagation of mode II cracks parallel to the wear surfaces and the subsequent separation of platelets with adhered WC and Co particles through adhesive forces with the steel ring. The wear rates of the cermets do not show a consistent relationship with mode I or mode II fracture toughness, but a general trend of decreasing wear rate with hardness is seen. This suggests that the tribological performance of these cermets depends on certain specific functions of pertinent parameters including fracture toughness, hardness, applied load, coefficient of friction and microstructural characteristics. A fracture mechanics-based wear model has been developed to relate the steady state wear rate (W{sub ss}) to hardness, mode II fracture toughness, coefficient of friction, and applied load. (orig./MM)

  8. 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.

  9. 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...... was analyzed before and after the treatment by optical microscopy and field emission scanning electron microscopy (FE-SEM). From the optical images the particle size and total amount of Ni, as area fraction, in the sample were measured. By the use of charge contrast (CC) in the FE-SEM particle size and area...

  10. Preliminary Investigation of the Effect of Surface Treatment on the Strength of a Titanium Carbide - 30 Percent Nickel Base Cermet

    Science.gov (United States)

    Robins, Leonard; Grala, Edward M

    1957-01-01

    Specimens of a nickel-bonded titanium carbide cermet were given the following surface treatments: (1) grinding, (2) lapping, (3) blast cleaning, (4) acid roughening, (5) oxidizing, and (6) oxidizing and refinishing. Room-temperature modulus-of-rupture and impact strength varied with the different surface treatments. Considerable strength losses resulted from the following treatments: (1) oxidation at 1600 F for 100 hours, (2) acid roughening, and (3) severe grinding with 60-grit silicon carbide abrasive. The strength loss after oxidation was partially recovered by grit blasting or diamond grinding.

  11. 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.

  12. A Study of the "toss Factor" in the Impact Testing of Cermets by the Izod Pendulum Test

    Science.gov (United States)

    Probst, H B; Mchenry, Howard T

    1957-01-01

    The test method presented shows that the "toss energy" contributed by the apparatus for brittle materials is negligible. The total toss energy is considered to consist of two components. (a) recovered stored elastic energy and (b) kinetic energy contributed directly by the apparatus. The results were verified by high-speed motion pictures of the test in operation. From these photographs, velocities of tossed specimens were obtained and toss energy computed. In addition, impact energies of some titanium carbide base cermets and high-temperature alloys, as measured by the low-capacity Izod pendulum test, compare well with impact energies measured by the NACA drop test.

  13. Enhanced stability of Zr-doped Ba(CeTb)O(3-δ)-Ni cermet membrane for hydrogen separation.

    Science.gov (United States)

    Wei, Yanying; Xue, Jian; Fang, Wei; Chen, Yan; Wang, Haihui; Caro, Jürgen

    2015-07-25

    A mixed protonic and electronic conductor material BaCe(0.85)Tb(0.05)Zr(0.1)O(3-δ) (BCTZ) is prepared and a Ni-BCTZ cermet membrane is synthesized for hydrogen separation. Stable hydrogen permeation fluxes can be obtained for over 100 h through the Ni-BCTZ membrane in both dry and humid conditions, which exhibits an excellent stability compared with Ni-BaCe(0.95)Tb(0.05)O(3-δ) membrane due to the Zr doping.

  14. In-pile and out-of-pile testing of a molybdenum-uranium dioxide cermet fueled themionic diode

    Science.gov (United States)

    Diianni, D. C.

    1972-01-01

    The behavior of Mo-UO2 cermet fuel in a diode for thermionic reactor application was studied. The diode had a Mo-0.5 Ti emitter and niobium collector. Output power ranged from 1.4 to 2.8 W/cm squared at emitter and collector temperatures of 1500 deg and 540 C. Thermionic performance was stable within the limits of the instrumentation sensitivity. Through 1000 hours of in-pile operation the emitter was dimensionally stable. However, some fission gases (15 percent) leaked through an inner clad imperfection that occurred during fuel fabrication.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

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

    NARCIS (Netherlands)

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

    1992-01-01

    SEM microstructural analyses in conjunction with EDX and TEM microstructural analyses have been conducted with cermets based on nickel and alumina, the latter as such and with a chemical-vapour-deposited titanium nitride layer. It has been proved that there is excellent bonding at both the Al2O3/TiN

  20. Effect of Yb2O3 doping on the grain boundary of NiFe2O4-10NiO-based cermets after sintering

    Institute of Scientific and Technical Information of China (English)

    Han-bing He

    2015-01-01

    xYb2O3–15(20Ni–Cu)/(85−x)(NiFe2O4–10NiO) (x=0, 0.25, 0.5, 0.75, 1.0, 2.0, and 10.0) cermets for aluminum electrolysis were prepared to investigate the effect of Yb2O3 doping on the grain boundary of the cermets after sintering. The results showed that each interface was very clear and that with increasing Yb2O3 content, most of the Yb was evenly distributed at the grain boundary. Moreover, according to the phase composition and microstructural analysis by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), and electron probe microanalysis (EPMA), YbFeO3 was produced along the grain boundary. The YbFeO3 was concluded to not only have formed from the interaction between the NiFe2O4 or Fe2O3 component and Yb2O3 at the grain boundary of the cermets, but also from the decomposition of NiFe2O4 into NiO and Fe2O3 and the subsequent reaction of Fe2O3 with Yb2O3. Thus, the pro-duction of YbFeO3 resulted in a cermet with high relative density, good electrical conductivity, and good corrosion resistance.

  1. Study of the Ni-NiAl{sub 2}O{sub 4}-YSZ cermet for its possible application as an anode in solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Reyes-Rojas, A [Centro de Investigacion en Materiales Avanzados SC, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua (Mexico); Universidad Autonoma del Estado de Mexico, Facultad de Quimica, Toluca (Mexico); Esparza-Ponce, H E [Centro de Investigacion en Materiales Avanzados SC, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua (Mexico); Reyes-Gasga, J [Universidad Nacional Autonoma de Mexico, Instituto de Fisica, Mexico DF (Mexico)

    2006-05-17

    Nanocrystalline Ni-NiAl{sub 2}O{sub 4}-YSZ cermet with a possible application as anode in solid oxide fuel cells (SOFCs) has been developed. The powders were prepared by using an alternative solid-state method that includes the use of nickel acetylacetonate as an inorganic precursor to obtain a highly porous material after sintering at 1400 {sup o}C and oxide reduction (NiO -Al{sub 2}O{sub 3}-YSZ {yields} Ni-NiAl{sub 2}O{sub 4}-YSZ) at 800 {sup o}C for 8 h in a tubular reactor furnace using 10% H{sub 2}/N{sub 2}. Eight samples with 45% Ni and 55% Al{sub 2}O{sub 3}-YSZ in concentrations of Al{sub 2}O{sub 3} oxides from 10 to 80 wt% of were mixed to obtain the cermets. The obtained material was compressed using unidirectional axial pressing and calcinations from room temperature to 800 {sup o}C. Good results were registered using a heating rate of 1 {sup o}C min{sup -1} and a special ramp to avoid anode cracking. Thermal expansion, electrical conductivity, and structural characterization by thermo-mechanical analyser (TMA) techniques/methods, the four-point probe method for conductivity, scanning electron microscopy (SEM), x-ray energy dispersive spectroscopy (EDS), x-ray diffraction (XRD), and the Rietveld method were carried out. Cermets in the range 5.5 to 11% Al{sub 2}O{sub 3} present a crystal size around 200 nm. An inversion degree (I) in the NiAl{sub 2}O{sub 4} spinel structure of the cermets Ni-NiAl{sub 2}O{sub 4}-YSZ was found after the sintering and reduction processes. Good electrical conductivity and thermal expansion coefficient were obtained for the cermet with 12 wt% of spinel structure formation.

  2. 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.

  3. 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.

  4. Dissolution-precipitation mechanism of self-propagating high-temperature synthesis of TiC-Cu cermets

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The mechanism of self-propagating high-temperature synthesis (SHS) of TiC-Cu cermets was studied using a combustion front quenching method. Microstructural evolution in the quenched sample was observed using scanning electron microscope (SEM) with energy dispersive X-ray (EDX) spectrometry, and the combustion temperature was measured. The results showed that the combustion reaction started with local formation of Ti-Cu melt and could be described with the dissolution-precipitation mechanism,namely, Ti, Cu, and C particles dissolved into the Ti-Cu solution and TiC particles precipitated in the saturated Ti-Cu-C liquid solution. The local formation of Ti-Cu melt resulted from the solid diffusion between Ti and Cu particles.

  5. 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.

  6. 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.

  7. Identification of nickel sulfides on Ni-YSZ cermet exposed to H 2 fuel containing H 2S using Raman spectroscopy

    Science.gov (United States)

    Dong, Jian; Cheng, Zhe; Zha, Shaowu; Liu, Meilin

    Ni-YSZ cermet was exposed to hydrogen containing different concentrations of H 2S to identify the phases formed under various conditions using Raman spectroscopy and X-ray diffraction (XRD). For Ni-YSZ samples exposed to hydrogen containing 100 ppm H 2S at 727 °C for 5 days, thermodynamic calculations indicate that Ni-YSZ would be stable and XRD analysis was unable to detect any changes. However, the vibration modes of Ni 3S 2 were detected using Raman spectroscopy, suggesting that Raman spectroscopy could be a powerful tool for in situ study of sulfur poisoning of SOFC anodes. For Ni-YSZ cermet exposed to hydrogen containing 10% H 2S at 950 °C for 5 days, Ni was converted to nickel sulfide, and vibration modes of NiS were detected using Raman spectroscopy.

  8. 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.

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

    Directory of Open Access Journals (Sweden)

    Leszek A. Dobrzañski

    2005-06-01

    Full Text Available This study presents the results of microstructural examinations, mechanical tests and service performance tests carried out on thin TiN/(Ti,Al,SiN/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 properties of the materials were determined from service tests in which continuous machining of C45E steel was carried out. The hardness of the substrate and the microhardness of the coatings were determined with a DUH 202 SHIMADZU ultra microhardness tester with a load of 70 mN. Roughness tests were also carried out before applying the coatings and after the PVD process. Cutting tests confirmed the advantages of the TiN/(Ti,Al,SiN/TiN type coatings obtained using the PVD method in the CAE mode on cemented carbides and cermets, as a material that undergoes very low abrasive, thermal and adhesion wear. These coatings extend tool life compared to commercially available uncoated tools with single and multi-layer coatings deposited using PVD/CVD methods.

  10. Interfacial engineering of solution-processed Ni nanochain-SiOx (x < 2) cermets towards thermodynamically stable, anti-oxidation 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

  11. 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.

  12. Study on proton-conducting solid oxide fuel cells with a conventional nickel cermet anode operating on dimethyl ether

    Science.gov (United States)

    Liu, Yu; Guo, Youmin; Wang, Wei; Su, Chao; Ran, Ran; Wang, Huanting; Shao, Zongping

    This study investigates dimethyl ether (DME) as a potential fuel for proton-conducting SOFCs with a conventional nickel cermet anode and a BaZr 0.4Ce 0.4Y 0.2O 3-δ (BZCY4) electrolyte. A catalytic test demonstrates that the sintered Ni + BZCY4 anode has an acceptable catalytic activity for the decomposition and steam reforming of DME with CO, CH 4 and CO 2 as the only gaseous carbon-containing products. An O 2-TPO analysis demonstrates the presence of a large amount of coke formation over the anode catalyst when operating on pure DME, which is effectively suppressed by introducing steam into the fuel gas. The selectivity towards CH 4 is also obviously reduced. Peak power densities of 252, 280 and 374 mW cm -2 are achieved for the cells operating on pure DME, a DME + H 2O gas mixture (1:3) and hydrogen at 700 °C, respectively. After the test, the cell operating on pure DME is seriously cracked whereas the cell operating on DME + H 2O maintains its original integrity. A lower power output is obtained for the cell operating on DME + H 2O than on H 2 at low temperature, which is mainly due to the increased electrode polarization resistance. The selection of a better proton-conducting phase in the anode is critical to further increase the cell power output.

  13. Preliminary testing of NiFe2O4-NiO-Ni cermet as inert anode in Na3AlF6-AlF3 melts

    Institute of Scientific and Technical Information of China (English)

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

    2006-01-01

    The electrical conductivity of cermet 83(90NiFe2O4-10NiO)-17Ni at different temperatures was measured in air, the operating performance of inert anode was evaluated in a laboratory electrolysis cell with various electrolyte compositions. The results indicate that the electrical resistivity of cermet studied has negative temperature coefficient, which is the characteristic of semi-conducting material. The proper addition of AlF3 in the bath can improve the corrosion resistance of cermet inert anode, but excess adding amount will cause the catastrophic corrosion. Post-examination of anodes shows that metal Ni leaches preferentially on the anode surface. Chemical dissolution, electrolyte penetration as well as electrochemical dissolution serve as major corrosion mechanisms.

  14. 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...

  15. Enhanced stability of Zr-doped Ba(CeTb)O3−δ-Ni cermet membrane for hydrogen separation

    OpenAIRE

    Wei, Yanying; Xue, Jian; Fang, Wei; Chen, Yan; Wang, Haihui; Caro, Jürgen

    2015-01-01

    A mixed protonic and electronic conductor material BaCe0.85Tb0.05Zr0.1O3−δ (BCTZ) is prepared and a Ni-BCTZ cermet membrane is synthesized for hydrogen separation. Stable hydrogen permeation fluxes can be obtained for over 100 h through the Ni-BCTZ membrane in both dry and humid conditions, which exhibits an excellent stability compared with Ni-BaCe0.95Tb0.05O3−δ membrane due to the Zr doping.

  16. Electronic structures, elastic properties, and minimum thermal conductivities of cermet M{sub 3}AlN

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jin [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Key Laboratory of Liquid–Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Chen, ZhiQian, E-mail: chen_zq@swu.edu.cn [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China); Li, ChunMei; Li, Feng; Nie, ChaoYin [Faculty of Materials and Energy, Southwest University, Chongqing 400715 (China)

    2014-08-15

    The electronic structures and elastic anisotropies of cubic Ti{sub 3}AlN, Zr{sub 3}AlN, and Hf{sub 3}AlN are investigated by pseudopotential plane-wave method based on density functional theory. At the Fermi level, the electronic structures of these compounds are successive with no energy gap between conduct and valence bands, and exhibit metallicity in ground states. In valence band of each partial density of states, the different orbital electrons indicate interaction of corresponding atoms. In addition, the anisotropy of Hf{sub 3}AlN is found to be significantly different from that of Ti{sub 3}AlN and Zr{sub 3}AlN, which involve the differences in the bonding strength. It is notable that Hf{sub 3}AlN is a desired thermal barrier material with the lowest thermal conductivity at high temperature among the three compounds. - Graphical abstract: 1.Young's moduli of anti-perovskite Ti{sub 3}AlN, Zr{sub 3}AlN, and Hf{sub 3}AlN in full space. 2.Electron density differences on crystal planes (1 0 0), (2 0 0), and (1 1 0) of anti-perovskite Zr{sub 3}AlN. - Highlights: • We calculated three anti-perovskite cermets with first-principles theory. • We illustrated 3D Young modulus and found the anomalous anisotropy. • We explained the anomaly and calculated the minimum thermal conductivities.

  17. Critical tuning of magnetron sputtering process parameters for optimized solar selective absorption of NiCrO{sub x} cermet coatings on aluminium substrate

    Energy Technology Data Exchange (ETDEWEB)

    Gaouyat, Lucie, E-mail: lucie.gaouyat@fundp.ac.be [Solid State Physics Laboratory, Research Center in Physics of Matter and Radiation (PMR), Facultés Universitaires Notre-Dame de la Paix (FUNDP), 61 rue de Bruxelles, B-5000 Namur (Belgium); Mirabella, Frédéric [CRM Group – AC and CS, 57b boulevard de Colonster, B-4000 Liège (Belgium); Deparis, Olivier [Solid State Physics Laboratory, Research Center in Physics of Matter and Radiation (PMR), Facultés Universitaires Notre-Dame de la Paix (FUNDP), 61 rue de Bruxelles, B-5000 Namur (Belgium)

    2013-04-15

    NiCrO{sub x} ceramic–metal composites (i.e. cermets) exhibit not only oxidation and moisture resistances, which are very important for industrial applications, but also remarkable solar selective absorption properties. In order to reach the best optical performances with only one coating layer, tuning of the magnetron sputtering process parameters (O{sub 2} flow rate, pressure and deposition time) was performed systematically. The process window turned out to be very narrow implying a critical tuning of the parameters. The optimal operating point was determined for a single layer coating of NiCrO{sub x} on an aluminium substrate, leading to a spectrally integrated solar absorption as high as 78%. Among various material properties, the focus was put on the optical reflectance of the coating/substrate system, which was measured by UV–vis–NIR spectrophotometry. Using complex refractive index data from the literature, the theoretical reflectance spectra were calculated and found to be in good agreement with the measurements. Chemical analysis combined with scanning electronic and atomic force microscopies suggested a cermet structure consisting of metallic Ni particles and a compound matrix made of a mixture of chromium oxide, nickel oxide and nickel hydroxide.

  18. 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.

  19. 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.

  20. 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

  1. High Temperature Oxidation of Nickel-based Cermet Coatings Composed of Al2O3 and TiO2 Nanosized Particles

    Science.gov (United States)

    Farrokhzad, M. A.; Khan, T. I.

    2014-09-01

    New technological challenges in oil production require materials that can resist high temperature oxidation. In-Situ Combustion (ISC) oil production technique is a new method that uses injection of air and ignition techniques to reduce the viscosity of bitumen in a reservoir and as a result crude bitumen can be produced and extracted from the reservoir. During the in-situ combustion process, production pipes and other mechanical components can be exposed to air-like gaseous environments at extreme temperatures as high as 700 °C. To protect or reduce the surface degradation of pipes and mechanical components used in in-situ combustion, the use of nickel-based ceramic-metallic (cermet) coating produced by co-electrodeposition of nanosized Al2O3 and TiO2 have been suggested and earlier research on these coatings have shown promising oxidation resistance against atmospheric oxygen and combustion gases at elevated temperatures. Co-electrodeposition of nickel-based cermet coatings is a low-cost method that has the benefit of allowing both internal and external surfaces of pipes and components to be coated during a single electroplating process. Research has shown that the volume fraction of dispersed nanosized Al2O3 and TiO2 particles in the nickel matrix which affects the oxidation resistance of the coating can be controlled by the concentration of these particles in the electrolyte solution, as well as the applied current density during electrodeposition. This paper investigates the high temperature oxidation behaviour of novel nanostructured cermet coatings composed of two types of dispersed nanosized ceramic particles (Al2O3 and TiO2) in a nickel matrix and produced by coelectrodeposition technique as a function of the concentration of these particles in the electrolyte solution and applied current density. For this purpose, high temperature oxidation tests were conducted in dry air for 96 hours at 700 °C to obtain mass changes (per unit of area) at specific time

  2. 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.

  3. 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.

  4. 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.

  5. 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

    Further knowledge of the novel, well performing and durable Ni:CGO infiltrated cermet anode for metal supported fuel cells has been acquired by means of a detailed impedance spectroscopy study. The anode impedance was shown to consist of three arcs. Porous electrode theory (PET) represented...... 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...... of the infiltrated submicron sized particles was surprisingly robust. TEM analysis revealed the nano sized Ni particles to be trapped within the CGO matrix, which along the self limiting grain growth of the CGO seem to be able to stabilize the submicron structured anode....

  6. 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.

  7. 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.

  8. 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.

  9. 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.)

  10. 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

  11. 添加Zn对AgCu钎料在TiC金属陶瓷表面润湿性的影响%Influence of Zn addition on wettability of AgCu brazing alloy on TiC cermet

    Institute of Scientific and Technical Information of China (English)

    雷敏; 张丽霞; 李宏伟; 冯吉才

    2012-01-01

    Wetting experiments of AgCu eutectic brazing alloy and AgCuZn brazing alloy with 30wt.% Zn addition were performed on TiC cermet.Based on observation of wetting angles of the two brazing alloys on the cermet and interfacial microstructure,it is found that wettability of brazing alloy on TiC cermet is greatly improved by Zn addition.When AgCu brazing alloy was adopted,the microstructure was Ag(s.s)+Cu(s.s)/(Cu,Ni)+Ag(s.s)/TiC cermet+Ag(s.s)+Cu(s.s)/TiC cermet from the near exterior surface of the alloy to the cermet.However,when Zn was added into AgCu brazing alloy,the microstructure was Ag(s.s)+Cu(s.s)+(Cu,Ni)/Ag(s.s)+Cu(s.s)/(Cu,Ni)/TiC cermet+Ag(s.s)+ Cu(s.s)/TiC cermet.And it's shown that evaporation of Zn in the vacuum improves dissolution and diffusion of Ni at the interface and the wetting angle of the brazing alloy on the cermet decreases from 120.6° to 33.9°.%分别采用AgCu共晶钎料和AgCu共晶钎料中添加30%(质量分数)Zn的AgCuZn钎料在TiC金属陶瓷表面进行润湿试验.结果表明,Zn元素的添加显著改善了钎料在TiC金属陶瓷表面的润湿性;AgCu钎料润湿TiC金属陶瓷时,从近钎料外表面到钎料/陶瓷界面,组织依次为Ag(s.s)+Cu(s.s)/(Cu,Ni)+Ag(s.s)/TiC金属陶瓷+Ag(s.s)+Cu(s.s)/TiC金属陶瓷;而采用AgCuZn钎料润湿TiC金属陶瓷后,从近钎料外表面到钎料/陶瓷界面,组织依次为Ag(s.s)+Cu(s.s)+(Cu,Ni)/Ag(s.s)+Cu(s.s)/(Cu,Ni)/TiC金属陶瓷+Ag(s.s)+Cu(s.s)/TiC金属陶瓷.Zn元素在真空中挥发促进了界面处Ni原子的溶解和扩散,使钎料在陶瓷表面的润湿角由120.6°减小到33.9°.

  12. Flank wear study of coating carbides and cermet inserts during the dry high speed turning of AISI 1045 steel; Estudio del desgaste del flanco de carburos recubiertos y cermet durante el torneado de alta velocidad en seco del acero AISI 1045

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Gonzalez, L. W.; Perez-Rodriguez, R.; Zambrano-Robledo, P.; Guerrero-Mata, M.; Dumitrescu, L.

    2011-07-01

    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. (Author) 19 refs.

  13. H2 and CO oxidation process at the three-phase boundary of Cu-ceria cermet anode for solid oxide fuel cell

    Science.gov (United States)

    Zheng, Minghao; Wang, Shuang; Li, Mei; Xia, Changrong

    2017-03-01

    Cu-ceria cermets have been widely investigated as the anode materials for solid oxide fuel cells (SOFCs) that operated with hydrocarbon fuels. However, the anode reaction processes are not clear yet, especially those at the ceria-Cu-gas three phase boundary (3 PB). This work investigates samaria-doped ceria (SDC)-Cu-gas 3 PB reaction kinetics for the oxidation of H2 and CO, the products from hydrocarbons via external and internal reforming. Electrochemical conductivity relaxation measurement demonstrates that Cu is a synergistic catalyst that can significantly increase the reaction rate. The reaction at 3 PB contributes 81.3/66.8% of H2/CO oxidation when 5.4% SDC surface is covered with Cu particles. Combining with AC impedance analysis, elementary steps are proposed for the reaction at 3 PB. Water vapor combining to oxygen vacancy and carbon monoxide transforming to carbonate are the rate-determining steps for the oxidation of H2 and CO, respectively. Cu-SDC has shown much higher catalytic activity, i.e. about fivefold reaction rate, for the oxidation of CO than H2. In addition, Cu-SDC electrodes exhibit lower interfacial polarization resistance and lower activation energy for the electrochemical oxidation of CO than H2. Consequently, CO is easier to be oxidized than H2 when the Cu-ceria anode is fueled with syngas, the reforming product from hydrocarbons.

  14. Cermet composite thermal spray coatings for erosion and corrosion protection in combustion environments of advanced coal-fired boilers. Semiannual technical report, January 14, 1997--August 14, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Schorr, B.S.; Levin, B.F.; DuPont, J.N.; Marder, A.R.

    1997-08-31

    Research is presently being conducted to determine the optimum ceramic/metal combination in thermally sprayed metal matrix composite coatings for erosion and corrosion resistance in new coal-fired boilers. The research will be accomplished by producing model cermet composites using powder metallurgy and electrodeposition methods in which the effect of ceramic/metal combination for the erosion and corrosion resistance will be determined. These results will provide the basis for determining the optimum hard phase constituent size and volume percent in thermal spray coatings. Thermal spray coatings will be applied by our industrial sponsor and tested in our erosion and corrosion laboratories. Bulk powder processed Ni-Al{sub 2}O{sub 3} composites were produced at Idaho National Engineering Laboratory. The composite samples contained 0, 21, 27, 37, and 45 volume percent Al{sub 2}O{sub 3} with an average particle size of 12 um. Also, to deposit model Ni-Al{sub 2}O{sub 3} coatings, an electrodeposition technique was developed and coatings with various volume fractions (0-35%) of Al{sub 2}O{sub 3} were produced. The powder and electrodeposition processing of Ni-Al{sub 2}O{sub 3} Composites provide the ability to produce two phase microstructure without changing the microstructure of the matrix material. Therefore, the effect of hard second phase particles size and volume fraction on erosion resistance could be analyzed.

  15. Modeling and multi-objective optimization of surface roughness and productivity in dry turning of AISI 52100 steel using (TiCN-TiN coating cermet tools

    Directory of Open Access Journals (Sweden)

    Ouahid Keblouti

    2017-01-01

    Full Text Available The present work concerns an experimental study of turning with coated cermet tools with TiCN-TiN coating layer of AISI 52100 bearing steel. The main objectives are firstly focused on the effect of cutting parameters and coating material on the performances of cutting tools. Secondly, to perform a Multi-objective optimization for minimizing surface roughness (Ra and maximizing material removal rate by desirability approach. A mathematical model was developed based on the Response Surface Methodology (RSM. ANOVA method was used to quantify the cutting parameters effects on the machining surface quality and the material removal rate. The results analysis shows that the feed rate has the most effect on the surface quality. The effect of coating layers on the surface quality is also studied. It is observed that a lower surface roughness is obtained when using PVD (TiCN-TiN coated insert when compared with uncoated tool. The values of root mean square deviation and coefficient of correlation between the theoretical and experimental data are also given in this work where the maximum calculated error is 2.65 %.

  16. 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.

  17. 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.

  18. 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.

  19. Fabrication and Characterization of Reactively Sputtered AlInGaN Films with a Cermet Target Containing 5% Al and 7.5% In

    Science.gov (United States)

    Lin, Kaifan; Kuo, Dong-Hau

    2016-12-01

    AlInGaN films were deposited at a substrate temperature in the range of 100-400°C and a radio frequency (RF) output power in the range of 90-150 W on Si (100) by reactive sputtering in an (Ar + N2) atmosphere. A (Ga + GaN) cermet target for sputtering, containing 5 at.% aluminum and 7.5 at.% indium powders, was made by hot pressing the mixed metal powders and ceramic GaN. The effects of substrate temperature and sputtering output power on the formation of AlInGaN films and their electrical and optical properties were investigated. X-ray diffraction results showed that AlInGaN films grew with a preferential m-(10bar{1}0 ) growth plane and had a wurtzite crystal structure. The film roughness was influenced by the sputtering power and the film composition. The AlInGaN films deposited at 400°C and 150 W had the best crystallinity, and an electron concentration of 4.5 × 1017 cm-3, a Hall mobility of 497 cm2 V-1 s-1, and an optical bandgap (E g) of 2.71 eV.

  20. 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)

  1. Preliminary testing of NiFe2O4-NiO as ceramic matrix of cermet inert anode in aluminum electrolysis

    Institute of Scientific and Technical Information of China (English)

    秦庆伟; 赖延清; 肖劲; 李劼; 刘业翔

    2003-01-01

    Sintered samples of nickel ferrite-nickel oxide ceramic, usually used as the ceramic phase of cermet inert anode in aluminum electrolysis, were prepared and characterized. The solubilities of NiFe2O4-NiO ceramics were measured using an equilibration technique in the Na3AlF6-10%AlF3-5%CaF2-5 %Al2O3 melts at 960 ℃. Electrical resistivity was also measured for NiFe2O4-NiO ceramic samples prepared using the usual ceramic technique as function of temperature and content of NiO with an improved pyroconductivity test device, consisting of a specially constructed closed furnace and a Potentiostat/Galvanostat, based on the conventional direct current four-probe technique. Results show that, under the experimental conditions, the solubility of Fe from NiFe2O4 is 0.06% and Ni from NiFe2O4 is 0.008%. The solubility of Fe and Ni from NiFe2O4-NiO ceramic is inversely related to each other. The solubility of Ni increases but overall solubility of NiFe2O4-NiO ceramics decreases with increasing NiO content. The studied ceramic samples have a semiconductor behavior where electrical resistivity ρ decreases with increasing temperature and the resistivity ρ increases with increasing porosity. The resistivity ρ of NiFe2O4-NiO ceramic shows a minimum with increasing the content of NiO at various temperatures.

  2. 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。

  3. 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.

  4. 高性能SS-AlN金属陶瓷真空太阳集热管的制备%Preparation of high performance evacuated SS-AlN cermet solar collector tubes

    Institute of Scientific and Technical Information of China (English)

    池华敬; 郭帅; 熊凯; 王双; 周旭; 苗建朋; 陈革; 章其初

    2012-01-01

    采用真空磁控溅射沉积SS-AlN金属陶瓷太阳选择性吸收涂层.涂层光学功能层的制备,先采用铜靶溅射Cu红外反射层;再采用不锈钢(SS)和铝两金属靶在Ar和N2的混合气体中同时溅射沉积SS-AlN金属陶瓷吸收层;最后采用Al靶在Ar和N2中反应溅射沉积AlN减反射层.金属陶瓷吸收层由高、低SS体积份额的两吸收子层组成.优化溅射镀膜工艺参数获得高性能吸收涂层,太阳吸收比α(AM1.5)高达0.956±0.003(国标GB:α≥0.86),比GB高10%;红外发射比ε仅为0.043±0.003(GB:ε≤0.08).制备成φ58×2100 mm全玻璃真空太阳集热管,80℃平均热损系数ULT仅为0.47±0.01 W/m2℃ (GB:ULT≤0.85 W/m2℃),比GB低0.38W/m2℃,性能提高45%.制备的真空集热管具有良好的真空品质,集热管内管加热350℃恒温480 h后,吸气镜面轴向长度平均消失率仅为2~3%,集热管真空品质优于GB高达100倍以上(GB:350℃恒温48 h,镜面消失率≤50%).%Stainless steel-aluminium nitride (SS-AHV) cermet solar selective coatings were deposited by vacuum magnetron sputtering. The depositing process of the SS-A1N solar coatings is described as follows. Firstly, a Cu inferred reflection layer was deposited with Cu target. Secondly, a SS-A1N cermet absorber layer was deposited by sputtering simultaneously with Al and SS two metallic targets in the gas mixture of Ar and N2. Finally, an A1N anti-reflection layer was deposited with Al target in the gas mixture of Ar and N2. The SS-A1N cermet absorber layer is composed of a double cermet layer film structure incorporating two distinct cermet layers, a high SS volume fraction absorbing layer and a low SS volume fraction absorbing layer. A solar absorptance a of 0.956±0.003, and emittance e of 0.043±0.003 were achieved with optimized sputtering deposition parameters. The optical performance of the SS-A1N solar absorber coatings were unchanged after baking-evacuating the solar collector tubes at 450

  5. 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.

  6. 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。

  7. 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

  8. 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.

  9. 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.)

  10. 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.

  11. Effect of NiO content on corrosion behaviour of Ni-xNiO-NiFe2O4 cermets in Na3AlF6-Al2O3 melts

    Institute of Scientific and Technical Information of China (English)

    李劼; 段华南; 赖延清; 田忠良; 刘业翔

    2004-01-01

    5Ni-xNiO-NiFe2O4 cermets with different NiO contents were prepared and the corrosion behaviour in Na3 AlF6-Al2O3 melts was investigated in laboratory electrolysis tests. The results indicate that adding NiO is unfavorable to the densification of NiFe2O4-xNiO ceramics, while small Ni doping can greatly improve the sintering property. The electrolysis tests show that excess NiO is beneficial to the reduction of Fe while has little effects on that of Ni in the bath; the steady-state concentrations of Ni, Fe are below the corresponding solubilities of NiFe2O4-xNiO, implying that corrosion mechanism changes while electrifying. Post-electrolysis examination of anodes shows that Ni metal leaches at the anode surface, yet the substrate ceramic prevents the penetration of bath and the further loss of metal phase.

  12. 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.

  13. Synergistic effects of Ni 1- xCo x-YSZ and Ni 1- xCu x-YSZ alloyed cermet SOFC anodes for oxidation of hydrogen and methane fuels containing H 2S

    Science.gov (United States)

    Grgicak, Catherine M.; Pakulska, Malgosia M.; O'Brien, Julie S.; Giorgi, Javier B.

    Preparation and performance of bimetallic Ni (1- x)Co x-YSZ and Ni (1- x)Cu x-YSZ anodes were tested to overcome common deficiencies of carbon and sulfur poisoning in SOFCs. Ni 1- xCo xO-YSZ and Ni (1- x)Cu xO-YSZ precursors were synthesized via co-precipitation of their respective chlorides. Single cell solid oxide fuel cells of these bimetallic anodes were tested in H 2, CH 4, and H 2S/CH 4 fuel mixtures. Addition of Cu 2+ into the NiO lattice resulted in large metal particle sizes and decreased SOFC performance. Addition of Co 2+ into the NiO lattice to form Ni 0.92Co 0.08O-YSZ anode precursor produced a cermet with a large BET surface area and active metal surface area, thus increasing the rate of hydrogen oxidation for this sample. The performance of both bimetallics was found to quickly degrade in dry CH 4 due to carbon deposition and lifting of the anode from the electrolyte. However, Ni 0.69Co 0.31-YSZ showed superior activity in a 10% (v/v) H 2S/CH 4 fuel mixture, surpassing performance with H 2 fuel, thereby demonstrating the exciting prospect of using sulfidated Ni (1- x)Co x-YSZ as SOFC anodes in sulfur containing methane streams. The active anode becomes a sulfidated alloy (Ni-Co-S) under operating conditions. This anode showed enhanced performance, which surpassed those of sulfidated Ni and Co anodes, thereby suggesting a synergistic behaviour in the Ni-Co-S anode.

  14. Influence of spraying powders on properties of cold-sprayed WC cermet coatings%粉末制备工艺对冷喷WC金属陶瓷涂层性能的影响

    Institute of Scientific and Technical Information of China (English)

    陈枭; 王洪涛; 纪岗昌; 白小波; 董增祥; 王芳

    2013-01-01

    采用包覆、机械混合与团聚烧结工艺制备了多尺度WC-17Ni和ZYT10001A(WC-17% Co),WCTN(WC-17% Co)金属陶瓷粉末.用3种粉末冷喷涂沉积涂层,运用扫描电镜分析了涂层的组织结构、X射线衍射表征粉末与涂层的物相结构,用压入法测定了涂层的显微硬度、弹性模量和断裂韧性.研究结果表明,3种粉末沉积的涂层均具呈现致密的组织结构,涂层中的相结构没有发生变化.3种涂层的显微硬度、弹性模量和断裂韧性分别在(650.8±40.4)~ (1350.0±115) HV0.3、(182.6±66.6) ~(309.9±52.9)GPa和(13.12±4.44)~ (24±1)MPa·m1/2之间变化,其中以ZYT10001A(WC-17% Co)涂层的硬度值最大及断裂韧性值最小.%WC-17Ni, ZYT10001A ( WC-17% Co) and WCTN ( WC-17% Co) powders fabricated by cladding, mechanical mixing, agglomerate-sintering method respectively were deposited on stainless steel substrate to obtain WC cermet coatings by cold spraying. Microstructure of the coatings was studied by scanning electron microscopy, phase composnent was investigated by means of X-ray diffraction, and the microhardness, elastic modulus and fracture toughness were measured by indentation method. The results show that the coatings depsited by using three kinds of powders exhibited dense microstructure. The phases of the feedstocks remained unchanged in the coatings. The microhardness, elastic modulus and fracture toughness of the coatings varied from (650.8±40.4) to (1350. 0 ± 115) HV0.3, (182. 6 ±66. 6) to (309. 9 ±52. 9) GPa and (13. 12+4.44) to (24±1) MPa-m1/2, respectively, and ZYT10001A( WC-17% Co) coating had the highest value of microhardness and the lowest value of fracture toughness in the three coatings.

  15. Comparación in Vitro de las Propiedades Físico - Químicas de un Ionómero de Vidrio Convencional, un Cermet Y un Ionómero de Vidrio Modificado con Aleación para Amalgama

    OpenAIRE

    Cosio, Herbert; Universidad Alas Peruanas; Zuñiga, Gladys; Zvietcovich, María

    2015-01-01

    El propósito fue comparar in vitro las propiedades físico - químicas de un ionomero de vidrio convencional, un cermet y un ionomero de vidrio modificado con aleación para amalgama. El trabajo de investigación consto de 90 troqueles, que cumplieron estrictamente los criterios de selección. Evaluando tres propiedades; resistencia a la compresión, abrasión y erosión con el ácido cítrico. La resistencia a la compresión con la prensa hidráulica, nos mostró que no existe diferencia estadísticamente...

  16. EFFECT OF TITANIUM CARBIDE ADDITION ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF ULTRA-FINE Ti(C, N)-Ni CERMET%添加碳化钛对超细Ti(C,N)-Ni金属陶瓷显微结构和力学性能的影响

    Institute of Scientific and Technical Information of China (English)

    陈文琳; 刘宁; 晁盛

    2007-01-01

    用传统粉末冶金法制备了添加碳化钛(TiC)的Ti(C,N)基金属陶瓷.为了得到超细晶粒的显微结构,主要硬质相[Ti(C,N),TiC和TiN]的初始粉末粒度为纳米、亚微米级.通过扫描电子显微镜观察,发现了一种新的白芯/灰壳结构,揭示了其形成机制.此外,通过能谱仪分析,获得了各相的化学成分.用X射线衍射仪并通过计算得出了各相的点阵参数.对室温下该材料的力学性能进行了测试,并尝试把它们与金属陶瓷的原始成分和显微结构的特点联系起来.%A Ti(C, N)-based cermet with titanium carbide (TiC) additive was fabricated by the conventional powder metallurgy technique. The initial powder particle sizes of the main hard phase components [Ti(C, N), TiC and TiN] were nano/submicron-sized, in order to achieve an ultra-fine grain sizes microstructure. Through scanning electron microscopy observation, a new kind of bright core and grayish rim structure was detected, and its formation mechanism was proposed. In addition, quantitative information about the chemical composition of various phases was obtained by energy dispersive X-ray analysis. Phase identification was carried out by X-ray diffraction and the lattice parameter of each phase was calculated. The mechanical properties at room temperature were also tested, in order to correlate them with the cermet's starting composition and microstructural features.

  17. 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.

  18. 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.

  19. 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.

  20. 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...

  1. TITANIUM CARBIDE CONTENT EFFECT ON EROSION IN CERMET ROCKET NOZZLES

    Science.gov (United States)

    class investigated consisted of an AISI Type 316 stainless steel matrix incorporating a hard phase of titanium carbide ranging in content from 20% to...55% by volume. The results of the study indicated that under the test conditions, increases in the titanium carbide constituents did increase the

  2. 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.

  3. Thermal expansion properties of metallic and cermet coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ilavsky, J.; Berndt, C.C. [State Univ. of New York, Stony Brook, NY (United States). Center for Thermal Spray Res.

    1998-04-01

    Free-standing deposits of NiCrAl, stainless steel, and 8 wt.% yttria-stabilized zirconia were prepared using atmospheric plasma spraying and high velocity oxygen fuel processing. Feedstock powders were blended, yielding mixtures (by weight) of 100%, 75%, and 50% of the metallic material. Porosity and composition (i.e. metal or ceramic constituents) of these deposits were measured by image analysis. The coefficient of thermal expansion (CTE) was measured in the 200-950 C interval for four thermal cycles. The first runs of these CTE measurements were not linear and differentiation of this curve established the CTE dependence with respect to temperature. Maximums in CTE behavior suggest that stress relaxation and/or oxidation may be occurring. Measurements of CTE from thermal cycles after the first cycle were constant and obeyed the law of mixtures in the measured temperature region, suggesting that stress relaxation and/or oxidation, evident in the first cycle, are no longer dominant. Microstructural analysis and microhardness measurements were used to confirm the findings from CTE measurements. (orig.) 13 refs.

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    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...... 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......, 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...

  5. Planar metal-supported SOFC with novel cermet anode

    DEFF Research Database (Denmark)

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

    2011-01-01

    Metal-supported solid oxide fuel cells are expected to offer several potential advantages over conventional anode (Ni-YSZ) supported cells. For example, increased resistance against mechanical and thermal stresses and a reduction in material costs. When Ni-YSZ based anodes are used in metal...... supported SOFC, elements from the active anode layer may inter-diffuse with the metallic support during sintering. This work illustrates how the inter-diffusion problem can be circumvented by using an alternative anode design based on porous and electronically conducting layers, into which...... electrocatalytically active materials are infiltrated after sintering. The paper presents the electrochemical performance and durability of the novel planar metal-supported SOFC design. The electrode performance on symmetrical cells has also been evaluated. The novel cell and anode design shows a promising performance...

  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. 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.

  8. A pilot study of the marginal adaptation and surface morphology of glass-cermet cements.

    Science.gov (United States)

    Chu, C H; King, N M; Lee, A M; Yiu, C K; Wei, S H

    1996-07-01

    This study investigated changes in the marginal adaptation and surface morphology of Ketac-Silver and Chelon-Silver glass-current cements over time. Dispersalloy amalgam was used as a control. Contralateral pairs of carious primary molars were restored with the test materials and amalgam. Clinical evaluations were scheduled at 12, 18, and 24 months after placement. Gold-plated replicas of the restorations were observed with scanning electron microscopy. Fractures and cracks in the surface of the Dispersalloy and Chelon-Silver increased the surface roughness; however, the damage was superficial and self-limiting in the Dispersalloy restorations, while in Chelon-Silver the fractures caused the material to break down in layers. A substantial quantity of pores, usually smaller than 50 microns in diameter, were observed throughout the surface of the Chelon-Silver restorations. The pores in the surface of Ketac-Silver were fewer and smaller. The incidence of cavomarginal breakdown increased with time. Chelon-Silver restorations had a higher rate of cavomarginal breakdown than did Ketac-Silver and Dispersalloy restorations up to 18 months. However, there was no statistically significant difference in the marginal adaptation of the three groups at 24 months.

  9. 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.

  10. Superstructure formation and variation in Ni-GDC cermet anodes in SOFC.

    Science.gov (United States)

    Li, Zhi-Peng; Mori, Toshiyuki; Auchterlonie, Graeme John; Zou, Jin; Drennan, John

    2011-05-28

    The microstructures and spatial distributions of constituent elements at the anode in solid oxide fuel cells (SOFCs) have been characterized by analytical transmission electron microscopy (TEM). High resolution TEM observations demonstrate two different types of superstructure formation in grain interiors and at grain boundaries. Energy-filtered TEM elemental imaging qualitatively reveals that mixture zones exist at metal-ceramic grain boundaries, which is also quantitatively verified by STEM energy dispersive X-ray spectroscopy. It was apparent that both metallic Ni and the rare-earth elements Ce/Gd in gadolinium-doped ceria can diffuse into each other with equal diffusion lengths (about 100 nm). This will lead to the existence of mutual diffusion zones at grain boundaries, accompanied by a change in the valence state of the diffusing ions, as identified by electron energy-loss spectroscopy (EELS). Such mutual diffusion is believed to be the dominant factor that gives rise to superstructure formation at grain boundaries, while a different superstructure is formed at grain interiors, as a consequence solely of the reduction of Ce(4+) to Ce(3+) during H(2) treatment. This work will enhance the fundamental understanding of microstructural evolution at the anode, correlating with advancements in sample preparation in order to improve the performance of SOFC anodes.

  11. Improvement in SOFC anode performance by finely-structured Ni/YSZ cermet prepared via heterocoagulation.

    Science.gov (United States)

    Sunagawa, Yoji; Yamamoto, Katsutoshi; Muramatsu, Atsushi

    2006-03-30

    A novel preparation technique for a nanostructured anode for a solid oxide fuel cell is investigated. By mixing nanometer-sized NiO and YSZ powders in a pH-controlled aqueous media, a fine mixture of nanoparticles is successfully obtained through heterocoagulation. The anode prepared from thus prepared mixture has a large triple phase boundary and shows a great improvement in the anode performance by increasing the electric conductivity and effective surface area.

  12. In-Situ Optical Studies of Oxidation/Reduction Kinetics on SOFC Cermet Anodes

    Science.gov (United States)

    2010-12-28

    Fuel Cells " Ann. Rev. Anal. Chem., 3 151-174 (2010). 2. B. C. Eigenbrodt1, M. B. Pomfret, D. A. Steinhurst, J. C. Owrutsky and R. A. Walker "Direct...in situ optical studies of solid oxide fuel cells operating with methanol and methane" J. Phys. Chem. C available online at ASAP. (Content from...Mapping of Surface Electrolyte Oxide Concentration in Solid Oxide Fuel Cells " submitted to Analytical Methods, accepted pending revisions. 4. J. D

  13. 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)

  14. 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.

  15. 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.

  16. Study on the diamond/ultrafine WC-Co cermets interface formed in a SPS consolidated composite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Nanocrystalline WC-Co composite powder and coated tungsten diamond by using vacuum vapor deposition were consolidated by the spark plasma sintering (SPS) process to prepare diamond-enhanced WC-Co cemented carbide composite materials. The interface microstructures between coated tungsten diamond and WC-Co cemented carbide matrix were investigated by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDXS). The results showed that there is a transitional layer between the diamond and the matrix, in which the carbon content is 62.97wt.%, and the content of cobalt in the transitional zone is 6.19wt.%; the content of cobalt in the WC-Co cemented carbide matrix is 6.07wt.%, in which the carbon content is 15.95wt.%, and the content of cobalt on the surface of diamond is 7.30wt.%, in which the carbon content is 80.38wt.%. The transitional zone prevents the carbon atom of the diamond from spreading to the matrix, in which the carbon content does coincide with the theoretical value of the raw nanocomposite powders, and the carbon content forms a graded distribution among the matrix, transitional zone, and the surface of diamond; after the 1280℃ SPS consolidated process the diamond still maintains a very good crystal shape, the coated tungsten on the surface of the diamond improves thermal stability of the diamond and increases the bonding strength of the interface between the diamond and the matrix.

  17. Development of Spatially-Based Emission Factors from Real-Time Measurements of Gaseous Pollutants Using Cermet Sensors

    Science.gov (United States)

    2005-03-01

    tungsten bismuth oxide YPG Yuma Proving Ground YSZ yttria-stabilized zirconium oxide v List of Figures Figure Page Figure 1a...Thurnauer, 1999. “Removal of Heavy Metals from Aqueous Waste Streams Using Surface-Modified Nanosized TiO2 Photocatalysts,” J. Adv. Oxid . Technol...metals, and metal oxides tailored to be sensitive to specific compounds. The arrays were self-heated to an ideal operating temperature, and were then

  18. Influence of Fracture Toughness and Microhardness on the Erosive Wear of Cermet Coatings Deposited by Thermal Spray

    Science.gov (United States)

    Mojena, Miguel Reyes; Orozco, Mario Sánchez; Fals, Hipólito Carvajal; Ferraresi, Valtair Antonio; Lima, Carlos Roberto Camello

    2017-02-01

    An evaluation of the relationship between the microhardness and fracture toughness with resistance to erosive wear of WC10Co4Cr, WC-12Co, and Cr3C2-25NiCr coatings was conducted. Powder and flexible cored wire feedstock materials were applied by high-velocity oxygen fuel (HVOF) and flame spray (FS), respectively. The erosive wear mechanism prevailing in the coatings was found to be brittle, which also explains the higher erosion rate for the experimental condition using the particle impact angle of 90 deg and impact velocity of 9.33 m/s. The best wear performance was for the coatings applied by HVOF that attains 1.83 mm3/kg for the 90 deg/3.61 m/s test condition. The coating obtained with the WC-10Co4Cr material using the FSFC method showed tungsten carbide decarburization, justifying its poor mechanical properties and poor performance in the erosive wear test. Flame-sprayed flexicords proved to be a promising alternative to HVOF in obtaining coatings with low porosity and acceptable mechanical properties, especially in applications where the use of the HVOF technique is inadequate because of inaccessibility or excessively high cost. Values of K c for the coatings obtained by HVOF (7.35 to 10.83 MPa.m1/2) were between two and three times greater than the values obtained for the coatings resulting from FSFC (2.39 to 3.59 MPa.m1/2), in a similar manner as with the microhardness.

  19. 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.

  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. Modification of subsurface structure in TiC-(Ni-Cr) cermet composite under pulsed electron-beam irradiation of samples in plasmas of light and heavy inert gases

    Science.gov (United States)

    Ovcharenko, V. E.; Ivanov, K. V.; Baohai, Yu; Zhengkun, Li; Hua, Xu Yun; Lisheng, Zhong

    2016-11-01

    Experiments with metal ceramic alloys with various ceramic content proved that the performance degree of pulsed electron-ion-plasma irradiation as a technology of creating a surface layer multilevel structural phase condition, where particles are measured within a nano dimensional diapason, depends on ionization energy degree as well as on plasma-supporting gas atomic weight. When ionization energy falls parallel to plasma-supporting gas atomic weight growth, ceramic component particles dissolve in a metal binding melt more quickly, and an accelerated dispersion of ceramic particles to nano sized level can be observed. A multilevel structural phase condition causes friction ratio decrease, while a metal ceramic alloy surface layer wear ability increases many-folds.

  2. 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.

  3. 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.

  4. 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.

  5. Nanoporous Ni-Ce0.8Gd0.2O1.9-x thin film cermet SOFC anodes prepared by pulsed laser deposition.

    Science.gov (United States)

    Infortuna, Anna; Harvey, Ashley S; Muecke, Ulrich P; Gauckler, Ludwig J

    2009-05-21

    Nickel oxide-gadolinia-doped ceria thin films with a ceria composition of 80 at% Ce and 20 at% Gd were grown by pulsed laser deposition on sapphire and SiO2/Si wafers as well as on yttria stabilized zirconia polycrystalline substrates. Upon reduction of the NiO phase in a H2/N2 atmosphere at 600 degrees C, a stable three-phase, 3-D interconnecting microstructure was obtained of metallic Ni, ceramic, and pores. Coarsening and segregation of the Ni to the surface of the film was observed at higher temperatures. The kinetics of this process depend strongly on the microstructures that can be developed in situ during deposition or post-deposition heat treatments. In situ minimization of Ni-coarsening can be achieved at temperatures as low as 500 degrees C when the deposition pressure does not exceed 0.02 mbar. For films deposited at higher pressure and at temperatures below 800 degrees C, coarsening can be minimized post deposition by annealing in air at 1000 degrees C. The films showed very good metallic conductivity and stability upon thermal cycling in a reducing atmosphere. Redox cycles performed at 600 degrees C between air and H2 induced a loss of connectivity of the metallic phase and consequent degradation of the conductivity. After 16 cycles, corresponding to 65 hrs, the conductivity is reduced by one order of magnitude.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Effect of the partial oxygen pressure on Cu-NiFe2O4 cermet phase%氧分压对Cu-NiFe2O4金属陶瓷相成份的影响

    Institute of Scientific and Technical Information of China (English)

    张明霞

    2009-01-01

    用高温固相法合成的NiFe2O4陶瓷粉末,选取Cu为金属陶瓷的金属相成分,研究了氧分压对Cu-NiFe2O4金属陶瓷的相成份的影响,结果表明:当烧结温度为1150℃,氧分压大于2.23Pa时,Cu被大量氧化;氧分压小于4.2×10-3Pa时,Cu和离解的Ni反应生产Cu3.8Ni合金,试样的导电性或抗氧化性都会降低,1150℃下烧结制备Cu-NiFe2O4金属陶瓷的最佳氧分压是( 0.3-42.0)×10-2Pa.

  17. 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.

  18. 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.

  19. Sonochemistry in the service of SOFC research.

    Science.gov (United States)

    Sakkas, Petros M; Schneider, Oliver; Sourkouni, Georgia; Argirusis, Christos

    2014-11-01

    Decoration of SOFC anode cermets with metal nanoparticles (NPs) enchance their ability and stability in natural gas to hydrogen reform. A novel sonoelectrochemical approach of Au-NPs synthesis (mean 12.31±2.69nm) is suggested, according to which the sonication is held constant while the electrochemical activity is either pulsed or continuous. The gold colloidal solution is cosonicated with state of the art cermet powder to yield particles decorated with Au-NPs. Nevertheless sonochemical routes of mixed molybdenum, rhenium or tungsten mixed oxides synthesis are utilized in order to decorate SOFC anode cermets. The decoration loading achieved spanned from 0.1 to 10.0wt.%.

  20. 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.

  1. 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.

  2. 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.)

  3. Reactively Sputtered Al2O3 Coating and Its Applications in Fabrication of Cermet Solar Collector Tubes%直流反应溅射沉积Al2O3薄膜及其在SS-AlN金属陶瓷太阳吸收涂层的应用

    Institute of Scientific and Technical Information of China (English)

    池华敬; 郭帅; 熊凯; 王双; 陈革; 章其初

    2012-01-01

    在沉积不锈钢-氮化铝(SS-AlN)金属陶瓷太阳吸收集热管的磁控溅射三靶镀膜机上,安装了UPS03反应溅射闭环控制单元,实现反应溅射Al2O3稳定反馈控制.采用国产直流电源在Al靶表面处于过渡态下,成功制备了吸收几乎为零的Al2O3薄膜.溅射功率在14 kW时,反应溅射沉积Al2O3的靶电压波动可长时间稳定控制在±3V范围内,沉积速率为5.4 nm/(min·kW),约为Al靶在无反应气体溅射下沉积Al薄膜速率的74%.采用Al2O3代替AlN作为减反射层,应用到SS-AlN太阳选择性吸收涂层中,进一步提高了复合膜的太阳光学性能,太阳吸收比由AlN作为减反射层的0.956提高到0.965,红外发射比不变,仍为0.044.%The Al2Q3 coatings were deposited by DC reactive magnetron sputtering on the outer wall surfaces of the inner tube of the ceimet solar collector,coated with Cu, stainless steel and aluminum nitride ceramics layers. Various factors influencing the Al2O3 deposition, such as the sputtering power, pressure, deposition rate, and ratio of the gas flow rates. The results show that the Al2Q3 films outperforms AlN films when used as the anti-reflection layer in stainless steel aluminum nitride (SS-A1N) metal ceramic solar absorbing coatings. The solar absorptance of the Al2O3 coatings, grown under optimized conditions,was found to be close to zero,resulting in an absorptance of 0.965,0.009 higher than that of A1N coatings, with no change in the infrared emission rate (0.044).

  4. 碳化钛粒径对碳氮化钛基金属陶瓷微观结构和力学性能的影响%EFFECT OF TITANIUM CARBIDE PARTICLE SIZE ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF TITANIUM CARBONITRIDE BASED CERMETS

    Institute of Scientific and Technical Information of China (English)

    陈文琳; 刘宁; 晁晟

    2007-01-01

    用粉末冶金真空烧结法制备了超细晶粒碳氮化钛[Ti(C,N)]基金属陶瓷.研究了原始粉末粒径对Ti(C,N)基金属陶瓷微观结构和力学性能的影响.结果表明:在化学成分相同的条件下,晶粒细化使材料的Vickers硬度和抗弯强度上升,但断裂韧性有所下降.在超细晶粒Ti(C,N)基金属陶瓷微观组织中出现了一种新型的白芯/灰壳结构和一种特殊化合物(Ni2Mo2.5W1.3)Cx.初步研究表明:由于原始粉末粒径微小,促进了扩散反应因而生成了这种芯/壳结构.芯/壳结构有利于提高材料的抗弯强度和断裂韧性.(Ni2Mo2.5W1.3)Cx有利于提高材料的Vickers硬度,但是降低了Ti(C,N)基金属陶瓷的抗弯强度和断裂韧性.

  5. 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.

  6. 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.

  7. 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.%.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. In situ thermal imaging and three-dimensional finite element modeling of tungsten carbide-cobalt during laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Yuhong [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States); Hofmeister, William H. [Center for Laser Applications, University of Tennessee Space Institute, Tullahoma, TN 37388 (United States); Cheng Zhao [Earth Mechanics Inc., Oakland, CA 94621 (United States); Smugeresky, John E. [Sandia National Laboratories, Livermore, CA 94551 (United States); Lavernia, Enrique J. [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States); Schoenung, Julie M., E-mail: jmschoenung@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616 (United States)

    2009-10-15

    Laser deposition is being used for the fabrication of net shapes from a broad range of materials, including tungsten carbide-cobalt (WC-Co) cermets (composites composed of a metallic phase and a hard refractory phase). During deposition, an unusual thermal condition is created for cermets, resulting in rather complex microstructures. To provide a fundamental insight into the evolution of such microstructures, we studied the thermal behavior of WC-Co cermets during laser deposition involving complementary results from in situ high-speed thermal imaging and three-dimensional finite element modeling. The former allowed for the characterization of temperature gradients and cooling rates in the vicinity of the molten pool, whereas the latter allowed for simulation of the entire sample. By combining the two methods, a more robust analysis of the thermal behavior was achieved. The model and the imaging results correlate well with each other and with the alternating sublayers observed in the microstructure.

  14. 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.

  15. 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.

  16. 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.

  17. 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...... the conductivity loss data. The MSC analysis yielded apparent activation energies for Ni sintering within the composite of 375kJ/mol when heated in dry H2 and 440kJ/mol when under wet H2....

  18. 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...... 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...

  19. 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.

  20. 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 (

  1. Redox stability of SOFC: Thermal analysis of Ni-YSZ composites

    DEFF Research Database (Denmark)

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

    2009-01-01

    by a period of parabolic kinetics slowing down to logarithmic towards full DoO. The shifts in the kinetic shape with time depended on the temperature and DoO. The rate constants for oxidation were fitted to the data. The BET surface area of the cermets after different reduction and oxidation treatments...

  2. Influence of the silicon content on the core corrosion properties of dispersion type fuel plates; Influencia del Contenido en silicio sobre la corrosion acuosa de los nucleos de placas combustibles

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, C.; Saenz de Tejada, L. M.; Diaz Diaz, J.

    1969-07-01

    A new process to produce aluminium base dispersion type fuel plates has been developed at the Spanish JEN (Junta de Energia Nuclear). The dispersed fuel material is obtained by an aluminothermic process to render a stoichiometric cermet of UAI{sub 3} and AI{sub 2}O{sub 3} according to the reaction. (Author)

  3. Self-sustained high-temperature reactions: initiation, propagation and synthesis

    NARCIS (Netherlands)

    Martinez Pacheco, M.

    2007-01-01

    Self-Propagating High-Temperature Synthesis (SHS), also called combustion synthesis is an exothermic and self-sustained reaction between the constituents, which has assumed significance for the production of ceramics and ceramic-metallic materials (cermets), because it is a very rapid processing tec

  4. 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...

  5. Full Ceramic Fuel Cells Based on Strontium Titanate Anodes, An Approach Towards More Robust SOFCs

    DEFF Research Database (Denmark)

    Holtappels, Peter; Irvine, J.T.S.; Iwanschitz, B.;

    2013-01-01

    The persistent problems with Ni-YSZ cermet based SOFCs, with respect to redox stability and tolerance towards sulfur has stimulated the development of a full ceramic cell based on strontium titanate(ST)- based anodes and anode support materials, within the EU FCH JU project SCOTAS-SOFC. Three...

  6. Assessment of full ceramic solid oxide fuel cells based on modified strontium titanates

    DEFF Research Database (Denmark)

    Holtappels, Peter; Ramos, Tania; Sudireddy, Bhaskar Reddy;

    2014-01-01

    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 the European project SCOTAS-SOFC full ceramic cells comprising CGO...

  7. 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.

  8. METHOD AND ALLOY FOR BONDING TO ZIRCONIUM

    Science.gov (United States)

    McCuaig, F.D.; Misch, R.D.

    1960-04-19

    A brazing alloy can be used for bonding zirconium and its alloys to other metals, ceramics, and cermets, and consists of 6 to 9 wt.% Ni, 6 to 9 wn~.% Cr, Mo, or W, 0 to 7.5 wt.% Fe, and the balance Zr.

  9. Multiple Scattering Theories for Optical Properties of Composite Materials.

    Science.gov (United States)

    2014-09-26

    34. III Taller de Fisica de Superficies, M. G6mez, et al; Mexico, 1985. PARTICIPATING SCIENTIFIC PERSONNEL AND DEGREES AWARDED This project provided...leave from Escuela de Fisica , Universidad de Costa Rica. ttPresent Address: Cornell University. 2 I. INTRODUCTION Cermets are inhomogeneous materials

  10. 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.

  11. The impact of NiO on microstructure and electrical property of solid oxide fuel cell anode

    Institute of Scientific and Technical Information of China (English)

    LI Yan; LUO Zhong-yang; YU Chun-jiang; LUO Dan; XU Zhu-an; CEN Ke-fa

    2005-01-01

    Ni-Ce0.8Sm0.2O1.9 (Ni-SDC) cermet was selected as anode material for reduced temperature (800 ℃) solid oxide fuel cells in this study. The influence of NiO powder fabrication methods for Ni-SDC cermets on the electrode performance was investigated so that the result obtained can be applied to make high-quality anode. Three kinds of NiO powder were synthesized with a fourth kind being available in the market. Four types of anode precursors were fabricated with these NiO powders and Ce0.sSm0.2O1.9 (SDC), and then were reduced to anode wafers for sequencing measurement. The electrical conductivity of the anodes was measured and the effect ofmicrostructure was investigated. It was found that the anode electrical conductivity depends strongly on the NiO powder morphologies, microstructure of the cermet anode and particle sizes, which are decided by NiO powder preparation technique. The highest electrical conductivity is obtained for anode cermets with NiO powder synthesized by NiCO3·2Ni(OH)2.4H2O or Ni(NO3)2.6H2O decomposition technique.

  12. 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

  13. Phase Transition Mapping by Means of Neutron Imaging in SOFC Anode Supports During Reduction Under Applied Stress

    DEFF Research Database (Denmark)

    Makowska, Malgorzata; Strobl, M.; Lauridsen, E. M.;

    2015-01-01

    Mechanical and electrochemical performance of layers composed of Ni-YSZ cermet in solid oxide fuel and electrolysis cells (SOC) depends on their microstructure and initial internal stresses. After sintering, the manufacturing conditions, i.e. temperature, atmosphere and loads, can influence the m...

  14. 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;

  15. 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.

  16. 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

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

    DEFF Research Database (Denmark)

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

    Todays' solid oxide fuels cells based on composite Ni-cermet anodes have been developed op to reasonable levels of performance and durability. However, especially for small combined heat and power supply systems, known failure mechanisms e.g. re-oxidation, sulfur tolerance and coking have...... 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......, stability, and S- tolerance has been investigated. These results and an assessment on a 1 kW system level using CPOX reformed natural gas will be reviewed and further perspectives of the cell concept discussed, especially with respect to efficient operation on high carbon containing fuels....

  18. 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...

  19. Mixed conductor anodes: Ni as electrocatalyst for hydrogen conversion

    DEFF Research Database (Denmark)

    Primdahl, S.; Mogensen, Mogens Bjerg

    2002-01-01

    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...

  20. Study of performance of high speed turning using the volumetric dimension coefficient of resultant cutting force; Estudio del rendimiento del torneado de alta velocidad utilizando el coeficiente de dimension volumetrica de la fuerza de corte resultante

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez-Gonzalez, L. W.; Perez-Rodriguez, R.; Zambrano-Robledo, P. C.; Siller-Carrillo, H. R.; Toscano-Reyes, H.

    2013-07-01

    This work deals with the experimental study of the resultant cutting force evolution of two coating carbide and a cermet inserts, during the dry turning of AISI 1045 steel with 400, 500 and 600 m/min cutting speeds. A new criterion for machinability study, the coefficient of volumetric dimension of cutting force, it is introduced. The investigation showed a better performance of cermet for moderate and intermediate cutting speeds, while at high cutting speed and final machining time, the three layers coated carbide achieved the best result. The factorial analysis of variance demonstrated a significant effect of machining time on the coefficient of volumetric dimension of resultant cutting force, while the material insert factor and their interaction, for intermediate cutting speed was just significant. (Author)

  1. 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.

  2. New binder phases for the consolidation of TiB{sub 2} hardmetals

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, R. [Univ. Panamericana, Mexico D.F. (Mexico); Barandika, M.G. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales; Ona, D. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales; Sanchez, J.M. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales; Villellas, A. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales; Valea, A. [Escuela de Ingenieria Tecnica Industrial, Dept. de Ingenieria Qumica y del Medio Ambiente, Bilbao (Spain); Castro, F. [Centro de Estudios e Investigaciones Tecnicas de Guipuzcoa (CEIT), San Sebastian (Spain). Dept. de Materiales

    1996-10-15

    New TiB{sub 2}-based cermets have been consolidated by hot isostatic pressing of powder mixtures of TiB{sub 2} and metallic alloys based on Fe, Ni and Co additions. Relevant thermodynamic aspects of the systems B-Ti-Ni, B-Ti-Fe and B-Ti-Co, essential for avoiding the formation of extremely brittle secondary borides, especially the secondary boride M{sub 23}B{sub 6}, are discussed in this work. The role of contaminants like oxygen, carbon and nitrogen, which can also lead to the formation of these compounds is also explained. The hardness, toughness and cutting behaviour of the cermets produced with these new binder phases are comparable with the highest commercial WC-Co grades. (orig.)

  3. Cu-Ni-YSZ anodes for solid oxide fuel cell by mechanical alloying processing

    Energy Technology Data Exchange (ETDEWEB)

    Guisard Restivo, Thomaz A.; Mello-Castanho, Sonia R.H. [IPEN, Inst. of Energetic and Nuclear Research, Sao Paulo, SP (Brazil)

    2010-01-15

    The work shows some results concerning a new cermet material 40 vol.% [(Cu)-Ni]-YSZ processed by mechanical alloying followed by Sintering by Activated Surface method. The projected cermet microstructure for this application is expected to possess microstructural characteristics that lead to better electric and ionic percolating, higher electrocatalytic activity and fuel reforming. The powder samples prepared by mechanical alloying optimized conditions show a homogeneous mixture. Transmission and scanning electron microscope analysis have demonstrated the powder particles are nanosized after 2 h of milling, showing lamellar internal structure aggregates. Suitable sintered pellets are obtained from these powders, within the required porosity and microstructure. Sintering kinetics studies for pellets of Ni-YSZ and Ni-Cu-YSZ indicate 2-step sintering processes. Copper additive promotes sintering and refines the microstructure. (orig.)

  4. Ag as an alternative for Ni in direct hydrocarbon SOFC anodes

    Energy Technology Data Exchange (ETDEWEB)

    Cantos-Gomez, A.; Van Duijn, J. [Instituto de Energias Renovables, Universidad de Castilla La Mancha, Paseo de la Investigacion 1, 02006 Albacete (Spain); Ruiz-Bustos, R. [Instituto de Energias Renovables, Parque Cientifico y Tecnologico de Albacete, Paseo de la Investigacion 1, 02006 Albacete (Spain)

    2011-02-15

    Ag has been shown to be a good metal for SOFC anode cermets using CO fuel. Here we have expanded on the work reported by testing Ag-YSZ cermets against different hydrocarbon based fuel (H{sub 2} and CH{sub 4}). This study shows that while Ag is a good current collector, it alone does not have the required catalytic activity for the direct oxidation of hydrocarbon based fuels needed to be used in SOFC anodes. As such an additional catalytic material (e.g. CeO{sub 2}) needs to be present when using fuels other then CO. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. RESPONSE SURFACE METHODOLOGY IN FINISH TURNING INCONEL 718

    Directory of Open Access Journals (Sweden)

    M. Aruna,

    2010-09-01

    Full Text Available Machining of hard materials used in aerospace applications require hard and tough cutting tools. Ceramic tools and cermets are used in machining of nickel alloys for such applications. In this study finish turning of Inconel 718 is carried out with cermet tools. Cutting parameters are designed using Taguchi’s DOE and the experiments are conducted for the designed parameters. The surface finish measurement is carried for the various conditions and data obtained are used to build up the mathematical surface model using response surface methodology. The adequacy of the developed mathematical model is proved by ANOVA. The findings of this study show new results and the second order model was quite adequate.

  6. 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.

  7. Ni-Based Solid Oxide Cell Electrodes

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Holtappels, Peter

    2013-01-01

    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...... - dimensional TPB throughout the electrode volume. Variables that are used for controlling the properties of Ni-cermet electrodes are: (1) Ni/YSZ volume ratio, and (2) porosity and particle size distribution, which mainly affected by raw materials morphology, application methods and production parameters...

  8. Development of wear resistant nanostructured duplex coatings by high velocity oxy-fuel process for use in oil sands industry.

    Science.gov (United States)

    Saha, Gobinda C; Khan, Tahir I; Glenesk, Larry B

    2009-07-01

    Oil sands deposits in Northern Alberta, Canada represent a wealth of resources attracting huge capital investment and significant research focus in recent years. As of 2005, crude oil production from the current oil sands operators accounted for 50% of Canada's domestic production. Alberta's oil sands deposits contain approximately 1.7 trillion barrels of bitumen, of which over 175 billion are recoverable with current technology, and 315 billion barrels are ultimately recoverable with technological advances. A major problem of operating machinery and equipment in the oil sands is the unpredictable failure from operating in this highly aggressive environment. One of the significant causes of that problem is premature material wear. An approach to minimize this wear is the use of protective coatings and, in particular, a cermet thin coating. A high level of coating homogeneity is critical for components such as bucketwheels, draglines, conveyors, shovels, heavyhauler trucks etc. that are subjected to severe degradation through abrasive wear. The identification, development and application of optimum wear solutions for these components pose an ongoing challenge. Nanostructured cermet coatings have shown the best results of achieving the degree of homogeneity required for these applications. In this study, WC-17Co cermet powder with nanocrystalline WC core encapsulated with 'duplex' Co layer was used to obtain a nanostructured coating. To apply this coating, high velocity oxy-fuel (HVOF) thermal spraying technique was used, as it is known for producing wear-resistant coatings superior to those obtained from plasma-based techniques. Mechanical, sliding wear and microstructural behavior of the coating was compared with those of the microstructured coating obtained from spraying WC-10Co-4Cr cermet powder by HVOF technique. Results from the nanostructured coating, among others, showed an average of 25% increase in microhardness, 30% increase in sliding wear resistance and

  9. The Effectof Insert of WC Powder on the Surface Hardening of Non Magnetic Foundry Materials

    OpenAIRE

    Ike, Hiroyuki; Shobuzawa, Yoshiyuki; Goto, Shoji; Aso, Setsuo; Konishi, Nobuo

    2002-01-01

    Non magnetic foundry materials such as the austenitic stainless cast steel had not been used for abrasion resistant materials, because their hardnesses were very low. Usually, ceramics, cermets and cemented carbides are used for the abrasion resistant materials even though they are expensive compared with foundry materials. In this study, WC powder were inserted by using the austenitic stainless cast steel (JIS SCS13A) and the austenitic cast iron (JIS FCA-NiCr202) for producing surface ha...

  10. 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...

  11. Relationships between structures and performance of SOFC anodes

    DEFF Research Database (Denmark)

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

    analysis), bulk measurements (porosity, dilatometry, mechanical properties), measurements of the electrical performance (direct current conductivity, impedance spectroscopy), measurements of the redox kinetics (thermo gravimetric analysis, synchrotron), and application of simple models of the layered...... expansion of the cermet structure upon oxidation. The bulk expansion promoted cracking of the electrolyte. The redistribution of the reduced nickel phase was observed to occur as rounding of the particles, and nickel sintering. The degree of sintering depended on the temperature, the composition...

  12. Estudio del rendimiento del torneado de alta velocidad utilizando el coeficiente de dimensión volumétrica de la fuerza de corte resultante

    Directory of Open Access Journals (Sweden)

    Hernández-González, L. W.

    2013-08-01

    Full Text Available This work deals with the experimental study of the resultant cutting force evolution of two coating carbide and a cermet inserts, during the dry turning of AISI 1045 steel with 400, 500 and 600 m/min cutting speeds. A new criterion for machinability study, the coefficient of volumetric dimension of cutting force, it is introduced. The investigation showed a better performance of cermet for moderate and intermediate cutting speeds, while at high cutting speed and final machining time, the three layers coated carbide achieved the best result. The factorial analysis of variance demonstrated a significant effect of machining time on the coefficient of volumetric dimension of resultant cutting force, while the material insert factor and their interaction, for intermediate cutting speed was just significant.En este trabajo se aborda el estudio experimental de la evolución de la fuerza de corte resultante de dos insertos de carburo recubierto y un cermet, durante el torneado en seco del acero AISI 1045 con velocidades de corte de 400, 500 y 600 m/min . Se introduce, además, un nuevo criterio para el estudio del rendimiento de las operaciones de mecanizado: el coeficiente de dimensión volumétrica de la fuerza de corte. La investigación mostró un mejor rendimiento del cermet para la velocidad de corte moderada e intermedia, mientras que para la alta velocidad de corte y tiempo final de mecanizado, el mejor resultado fue para el carburo recubierto con tres capas. El análisis de varianza factorial demostró un efecto significativo del tiempo de mecanizado en el coeficiente de dimensión volumétrica de la fuerza de corte resultante, mientras que la variable material del inserto y su interacción, fue solo significativa para la velocidad de corte intermedia.

  13. Manned Spacecraft

    Science.gov (United States)

    1989-09-14

    34 spacecraft. Improved were systems of conditioning and regeneration , and the system of soft landing, and there was provided high reliability of hermetic...ceramics, cermets or to cool them. 0 DOC = 89059215 PAGE :5Y (i)MeP ce71uneCKag oqKa 2ObtcoMorfle , epO - fi’loddD ueao tuu0 mnyp~aR U30J13NUU cmep

  14. Self-sustained high-temperature reactions: initiation, propagation and synthesis

    OpenAIRE

    Martinez Pacheco, M.

    2007-01-01

    Self-Propagating High-Temperature Synthesis (SHS), also called combustion synthesis is an exothermic and self-sustained reaction between the constituents, which has assumed significance for the production of ceramics and ceramic-metallic materials (cermets), because it is a very rapid processing technique without the need of complex furnaces. However, one of the drawbacks of this route is the high porosity of the final product (typically 50%). This implies the need for a subsequent densificat...

  15. Performance of Electrolyte Supported Solid Oxide Fuel Cells with STN Anodes

    DEFF Research Database (Denmark)

    Veltzé, Sune; Reddy Sudireddy, Bhaskar; Jørgensen, Peter Stanley

    2013-01-01

    In order to replace the state of the art Ni-cermet as SOFC anode, electrolyte supported cells comprising CGO/Ni infiltrated Nbdoped SrTiO3 anodes, and LSM/YSZ cathodes have been developed and tested as single 5 x 5 cm2 cells. The initial performance reached 0.4 W/cm2 at 850 C. Further tests under...

  16. Electrospark deposition coatings

    Science.gov (United States)

    Sheely, W. F.

    1986-11-01

    Hard surfacing for wear resistant and low-friction coatings has been improved by means of advances in the computer controls in electronic circuitry of the electrospark deposition (ESD) process. coatings of nearly any electrically conductive metal alloy or cermet can be deposited on conductive materials. Thickness is usually two mils or less, but can be as high as 10 mils. ESD coatings can quadrupole cutting tool life.

  17. European Science Notes Information Bulletin Reports on Current European/ Middle Eastern Science

    Science.gov (United States)

    1989-03-01

    electrochromic and can be colored blue by injection of Li U. Kreibig has been performing very careful ex- ions. The visible and infrared properties of the...examined. Electrochromic cermets were first 36 ESNIB 89-03 studied in the LIS in the late 1970’s for applications in dis- Montagna, and (. Viliani...the Lawrence Berkeley Laboratory included a storage ring (ESR) in the design of the ex- ( LBL ), indicated that construction is complete on MBE- panded

  18. Babcock and Wilcox assessment of the Pratt and Whitney XNR2000

    Science.gov (United States)

    Westerman, Kurt O.; Scoles, Stephen W.; Jensen, R. R.; Rodes, J. R.; Ales, M. W.

    1993-01-01

    Babcock & Wilcox performed four subtasks related to the assessment of the Pratt & Whitney XNR2000 nuclear reactor as follows: (1) cermet fuel element fabricability assessment; (2) mechanical design review of the reactor system; (3) neutronic analysis review; and (4) safety assessment. The results of the mechanical and physics reviews have been integrated into the reactor design. The results of the fuel and safety assessments are presented.

  19. The Manufacture of W-UO2 Fuel Elements for NTP Using the Hot Isostatic Pressing Consolidation Process

    Science.gov (United States)

    Broadway, Jeramie; Hickman, Robert; Mireles, Omar

    2012-01-01

    NTP is attractive for space exploration because: (1) Higher Isp than traditional chemical rockets (2)Shorter trip times (3) Reduced propellant mass (4) Increased payload. Lack of qualified fuel material is a key risk (cost, schedule, and performance). Development of stable fuel form is a critical path, long lead activity. Goals of this project are: Mature CERMET and Graphite based fuel materials and Develop and demonstrate critical technologies and capabilities.

  20. Electrical discharges under high voltage on surface of Silica-Nickel ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Jankowiak, A.; Blanchart, P. [Groupement d' Etude des Materiaux Heterogenes (GEMH), ENSCI, 87065 Limoges (France)

    2004-12-01

    Strong electrical breakdowns on surface of Silica-Nickel cermets are obtained under pulsed electric field. The electric field is significantly lower than for breakdowns at a similar air gap under the same atmosphere pressure. This hot plasma-like process can be used for gas or liquid ignition. Processes follow the Paschen's and the Fowler-Nordheim's laws at surface micro-protrusions, when the current percolates through the composite material. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

  1. Biotechnology and Composite Materials

    Science.gov (United States)

    1993-04-01

    Biotechnology, in general terms, is the science and engineering of using living organisms for making useful products such as pharmaceuticals, foods , fuels...chemicals, materials or in waste treatment processes and clinical and chemical analyses. It encompases the prosaic form of using yeast cells to make...ductile component of the composite. Table 1. Mechanical Properties of Ceramics, Cermets, and Abalone Shell •if KIC Hardness MPa MPam 1n 2 /2 Mohs KIlN

  2. 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...

  3. 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.

  4. Studies in new materials for intermediate temperature solid oxide fuel cells

    Science.gov (United States)

    Skinner, Alex W.

    Ceramic materials have historically been of interest for their thermal and mechanical properties. However, certain ceramic materials can have very interesting electrical, magnetic and optical properties, leading to a new subclass, the electroceramics. Perovskites, in particular, have become the subject of intense research in this field. Specifically, doped barium zirconates have shown high proton conductivity in the intermediate temperature range (600--800°C), making them advantageous for use in solid oxide fuel cells. Solid oxide fuel cells (SOFCs) are electrochemical devices that convert chemical energy into electricity using ion-conducting oxide ceramics as electrolytes. The anode component of the cell is also of interest. Cermets or ceramic metals can serve a dual role as substrates for thin film electrolytes and anodes in the cell. Thin films of gadolinium and ytterbium doped barium zirconate were deposited using pulsed laser deposition (KrF; 1--3 J/cm2) on several substrates, including cermets developed in our lab, in a 10--400 mTorr oxygen environment with various substrate temperatures. Crystalline structure and chemical composition was determined by X-ray diffraction (XRD) and energy dispersive x-ray analysis, respectively. Preliminary electrical measurements of the electrolyte/cermet structure were taken using electrochemical impedance spectroscopy. Keywords: solid oxide fuel cells (SOFCs), perovskites, proton conductors, electroceramics, gadolinium-doped barium zirconate (BZG).

  5. 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.

  6. 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.

  7. 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

  8. Evaluation of advanced materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Wright, I.G.; Clauer, A.H.; Shetty, D.K.; Tucker, T.R.; Stropki, J.T.

    1982-11-18

    Cemented tungsten carbides with a binder level in the range of 5 to 6 percent exhibited the best resistance to erosion for this class of materials. Other practical cermet meterials were diamond - Si/SiC, Al/sub 2/O/sub 3/-B/sub 4/C-Cr, and B/sub 4/C-Co. SiAlON exhibited erosion resistance equivalent to the best WC-cermet. The only coating system to show promise of improved erosion resistance was CVD TiB/sub 2/ on cemented TiB/sub 2/-Ni. Cracking and/or spalling of a TiC coating and a proprietary TMT coating occurred in the standard slurry erosion test. Ranking of cemented tungsten carbide materials in the laboratory erosion test was the same as that found in service in the Wilsonville pilot plant. Specimens from the Fort Lewis pilot plant which performed well in service exhibited low erosion in the laboratory test. A substitute slurry, was found to be 2 to 4 times more erosive than the coal-derived slurry 8 wt% solids. Ranking of materials in the substitute slurry was nearly identical to that in the coal-derived slurry. Three modes of erosion were: ductile cutting; elastic-plastic indentation and fracture; and intergranular fracture. Erosion of a given material was closely related to its microstructure. In the substitute slurry, the angle-dependence of erosion of two forms of SiC, hot-pressed and sintered, were similar, but the sintered material eroded slower. Laser fusing of preplaced powder mixtures can produce cermet-like structures with potential for erosive and sliding wear resistance. TiC particles in Stellite 6 matrix proved less prone to cracking than WC particles in the same matrix. 74 figures, 14 tables.

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. The FUTURIX - transmutation experiment in Phenix

    Energy Technology Data Exchange (ETDEWEB)

    Warin, D.; Sudreau, F.; Pillon, S.; Drin, N.; Donnet, L.; Brunon, E

    2004-07-01

    In support to the European and American strategies of long-live radioactive waste transmutation in GEN IV critical fast neutron reactors or ADS, an irradiation test of fuels with high contents of transuranium elements is being designed and will be irradiated during the two last cycles of the Phenix fast reactor. This experiment will provide the main data concerning the behaviour under irradiation in representative conditions of different innovative fuels (oxides, nitrides, metal alloys, cermets) and will allow qualification and validation of models developed to predict their performance. (authors)

  14. 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

  15. Investigation of atypical molten pool dynamics in tungsten carbide-cobalt during laser deposition using in-situ thermal imaging

    Science.gov (United States)

    Xiong, Yuhong; Hofmeister, William H.; Smugeresky, John E.; Delplanque, Jean-Pierre; Schoenung, Julie M.

    2012-01-01

    An atypical "swirling" phenomenon observed during the laser deposition of tungsten carbide-cobalt cermets by laser engineered net shaping (LENS®) was studied using in-situ high-speed thermal imaging. To provide fundamental insight into this phenomenon, the thermal behavior of pure cobalt during LENS was also investigated for comparison. Several factors were considered as the possible source of the observed differences. Of those, phase difference, material emissivity, momentum transfer, and free surface disruption from the powder jets, and, to a lesser extent, Marangoni convection were identified as the relevant mechanisms.

  16. Investigation of atypical molten pool dynamics in tungsten carbide-cobalt during laser deposition using in-situ thermal imaging

    Energy Technology Data Exchange (ETDEWEB)

    Xiong Yuhong; Schoenung, Julie M. [Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616 (United States); Hofmeister, William H. [Center for Laser Applications, University of Tennessee Space Institute, Tullahoma, Tennessee 37388 (United States); Smugeresky, John E. [Sandia National Laboratories, Livermore, California 94551 (United States); Delplanque, Jean-Pierre [Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616 (United States)

    2012-01-16

    An atypical ''swirling'' phenomenon observed during the laser deposition of tungsten carbide-cobalt cermets by laser engineered net shaping (LENS) was studied using in-situ high-speed thermal imaging. To provide fundamental insight into this phenomenon, the thermal behavior of pure cobalt during LENS was also investigated for comparison. Several factors were considered as the possible source of the observed differences. Of those, phase difference, material emissivity, momentum transfer, and free surface disruption from the powder jets, and, to a lesser extent, Marangoni convection were identified as the relevant mechanisms.

  17. Microstructural characterization of a composite Mo reinforced by 25 at.% TiC

    Energy Technology Data Exchange (ETDEWEB)

    Cedat, D. [Laboratoire de Mecanique des Sols, Structures et Materiaux, UMR 8579, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Chatenay-Malabry cedex (France); Rey, C. [Laboratoire de Mecanique des Sols, Structures et Materiaux, UMR 8579, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Chatenay-Malabry cedex (France)], E-mail: colette.rey@ecp.fr; Clavel, M.; Schmitt, J.H. [Laboratoire de Mecanique des Sols, Structures et Materiaux, UMR 8579, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Chatenay-Malabry cedex (France); Le Flem, M. [DEN/DANS/DMN/SRMA/LA2M, CEA, Centre de Saclay, 91191 Gif-sur-Yvette (France); Allemand, A. [DEN/DANS/DMN/SRMA/LTMEX, CEA, Centre de Saclay, 91191 Gif-sur-Yvette (France)

    2009-04-15

    In the scope of cermet development for structural pieces of future nuclear reactors (1000-1650 deg. C), Mo-TiC{sub 25at.%} was processed by hot isostatic pressure (HIP) and characterized in term of microstructure and chemical composition. The fabrication resulted in a three-phase material so called core/shell microstructure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, both coupled with X-ray detection (EDX), allowed to highlight the formation of TiC-Mo{sub 15at.%} phase at the TiC/Mo interface, in agreement with the phase diagram. The formation mechanisms of this phase are discussed.

  18. 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...

  19. 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

    This 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.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  1. Break down of losses in thin electrolyte SOFCs

    DEFF Research Database (Denmark)

    Barfod, Rasmus; Hagen, Anke; Ramousse, S.

    2006-01-01

    The contributions of the individual components of the cell (anode, cathode, and electrolyte) to the cell resistance were determined experimentally, directly from impedance spectra obtained from a full cell. It was an anode supported thin electrolyte cell, consisting of a YSZ electrolyte, a Ni....../YSZ cermet anode, and a LSM composite cathode. Additional, qualitative information was obtained using symmetric cells with LSM composite electrodes. The investigations were carried out in the temperature interval from 700 to 850 degrees C. The electrolyte and anode activation energies obtained were 0.9 and 1...

  2. Fundamental Material Properties Underlying Solid Oxide Electrochemistry

    DEFF Research Database (Denmark)

    Mogensen, Mogens Bjerg; Hansen, Karin Vels; Holtappels, Peter;

    2012-01-01

    such as “this is the rate limiting step of H2 oxidation in a Ni-zirconia cermet electrode...” will ever be found because the actual electrode properties are so dependent on the fabrication and operation history of the electrode. This does not mean, however, that deep knowledge of mechanisms of specific SOC...... in the TPB region. Also, segregations to the surfaces and interfaces of the electrode materials, which may affect the electrode reaction mechanism, are very dependent on the exact history of fabrication and operation. The positive effects of even small concentrations of nanoparticles in the electrodes may...

  3. 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.

  4. 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...... of nickel depending on temperature of the initial reduction and the operating conditions, and the temperature of reoxidation are very important for the size of the dimensional change. Cumulative redox strain (CRS) is shown to be correlated with temperature. Measured maximum CRS after three redox cycles...

  5. 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

    sets, which do not fit the model. We have inspected some models in the literature, and problems (e.g. no quantitative model has explained the large variation in reported values of apparent activation energy of the electrode kinetics) as well as strengths of the models are discussed. We point out...... 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...

  6. 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.

  7. 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...... 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...

  8. 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.

  9. 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.)

  10. 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.

  11. Nanophase modification of the superficial layer of cast iron during the interaction of the melt with a carbide-forming metal

    Science.gov (United States)

    Ovcharenko, V. E.; Ivanov, Yu. F.; Xu, Yunhua; Zhong, Lisheng; Zhao, Nana

    2016-11-01

    In the present publication, we report on the results of a study of the structural-phase state of the superficial layer of cast iron formed as a result of an interaction of cast-iron melt with a plate of carbide-forming Ta metal. It is found that, as a result of the interaction, in the superficial layer of cast iron there forms a cermet-type heterophase structure with nanocrystalline carbide phase. The influence of the formed heterophase structure on the physical properties of the superficial layer of cast iron is demonstrated.

  12. WC基涂层材料和制备工艺对其组织结构与性能的影响%Effect of WC Based Coating Materials and Fabrication Technology on the Structures and Properties

    Institute of Scientific and Technical Information of China (English)

    石琎; 丁翔; 胡一鸣; 丁彰雄; 肖俊钧; 王韶毅

    2015-01-01

    本文采用超音速火焰(HVOF)喷涂工艺制备了二种微米结构WC-10Co-4Cr及一种纳米结构WC-12Co金属陶瓷复合涂层;采用SEM、XRD等分析了涂层的组织结构;测量了涂层的显微硬度、孔隙率及开裂韧性;采用超声振动空蚀装置研究了涂层的抗空蚀性能,探讨了涂层空蚀机理。结果表明:由燃油型HVOF工艺制备的纳米WC-12Co涂层孔隙率最低,组织最细小,开裂韧性明显高于燃油型和燃气型HVOF工艺制备的微米WC-10Co-4Cr涂层;燃油型HVOF工艺制备的微米结构WC-10Co-4Cr涂层显示了最优异的抗空蚀性能,空蚀率仅为纳米WC-12Co涂层的1/3左右。%Two micro-structured WC-10Co-4Cr cermet coatings and a nano-structured WC-12Co cermet coating were deposited by High Velocity Oxy-Fuel spray(HVOF),and the morphologies and structures of the coatings were analyzed by SEM and XRD. Porosity, microhardness and fracture toughness of the coatings were measured. Resistance of coatings to cavitation erosion was studied by ultrasonic vibration cavitation equipment and the cavitation mechanisms were explored. Results show that the nano-structured WC-12Co coating deposited by High Velocity Fuel spray had lowest porosity and the densest microstructure and fracture toughness was significantly higher than that of micron-structured WC-10Co-4Cr coatings. Although the micron-structured WC-10Co-4Cr cermet coating deposited by HVOF had more coarser particles than the nano-structured, it exhibited the most excellent resistance to cavitation erosion, and the cavitation erosion rate was approximately one third that of the nano-structured WC-12Co cermet coating.

  13. 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.

  14. Intermediate-temperature solid oxide fuel cell employing reformed effective biogas: Power generation and inhibition of carbon deposition

    Science.gov (United States)

    Miyake, Michihiro; Iwami, Makoto; Goto, Kenta; Iwamoto, Kazuhito; Morimoto, Koki; Shiraishi, Makoto; Takatori, Kenji; Takeuchi, Mizue; Nishimoto, Shunsuke; Kameshima, Yoshikazu

    2017-02-01

    A power generation system consisting of an intermediate-temperature solid oxide fuel cell (IT-SOFC) and an external reformer for biogas is developed, and its performance is investigated for advanced use of effective biogas. The IT-SOFC is fueled with syngas produced via biogas reforming, and is successfully operated at 600 and 700 °C using Ni0.8Cu0.2 alloy/gadolinia-doped ceria electrolyte (Ni0.8Cu0.2/GDC) cermet anodes and a LaAlO3 supported-Ni (Ni/LaAlO3) catalyst. The Ni/LaAlO3 catalyst stably exhibits high reforming performance for effective biogas at 800 °C for 27 h, and carbon deposition on the catalyst is prevented. The electrochemical performance of the Ni0.8Cu0.2/GDC cermet anode using syngas fuel possessing a H2:CO ratio of approximately 3:1 is comparable to the performance achieved with H2 fuel; the anode remains stable after 24 h of operation at 700 °C without interruption and is unaffected by carbon deposition.

  15. Erosive wear of selected materials for fossil energy applications

    Energy Technology Data Exchange (ETDEWEB)

    Adler, Thomas A.; Rawers, James C.; Tylczak, Joseph H.; Hawk, Jeffrey A.

    2001-01-01

    A number of materials have been evaluated to determine their erosion resistance for fossil energy applications. This is part of a larger program to study wear and corrosion at Albany Research Center. This paper will present the results for some of these materials, including FeAl, FeAl cermets, WC-Co cemented carbides, Si3N4-MoSi2, Si3N4, Stellite 6B, white cast irons and 440C steel. Trends in erosion rates due to material properties and erosive conditions will be presented. FeAl cermets performed well compared to the WC-Co cemented carbides. The interparticle spacing of the WC-Co cemented carbides correlated with the erosion rate. The erosion rate of the WC-Co cemented carbides decreased as the interparticle spacing decreased. It is important to realize that erosion resistance is not an intrinsic material property, but is a system response. A change in the wear environment can significantly alter the relative rankings of materials with respect to their wear rate. For example, at relatively low velocities, the carbides in the white cast irons are more erosion resistant than the matrix, while at higher velocities the matrix is more erosion resistant.

  16. 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

  17. 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.

  18. 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.

  19. Synthesis of zirconia sphere particles based on gelation of sodium alginate

    Energy Technology Data Exchange (ETDEWEB)

    Nozaki, Takahiro [Department of Applied Quantum Physics and Nuclear Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Arima, Tatsumi, E-mail: arima@nucl.kyushu-u.ac.jp [Department of Applied Quantum Physics and Nuclear Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan); Idemitsu, Kazuya; Inagaki, Yaohiro [Department of Applied Quantum Physics and Nuclear Engineering, Faculty of Engineering, Kyushu University, 744 Motooka, Fukuoka 819-0395 (Japan)

    2011-05-01

    Zirconia sphere particles were synthesized through the gelation process of Na-alginate, and cermet (ZrO{sub 2}-Mo) pellets were fabricated under several conditions. In this process, a zirconia slurry was prepared by mixing oxide powders (ZrO{sub 2}, Y{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, CeO{sub 2}), distilled water and Na-alginate, and subsequently dropped into CaCl{sub 2} solution. As a result, zirconia sphere particles coated with a gelled film were synthesized. The slurry density (zirconia content in slurry) of 30-64 wt.% and Na-alginate concentration of a few% were good for gelation for up to 10 wt.% CaCl{sub 2} solution. Sphere particles with smaller diameter were obtained by dropping slurry with a mechanical vibration. The prolongation of the ball milling time for mixture of oxide powders was effective to increase the sintered density of zirconia sphere particles, especially for higher CeO{sub 2} concentration. The dense cermet pellets were fabricated for max. 50% volume ratio of zirconia phase for Mo matrix using zirconia particles covered with Mo powder by a rotating granulation method.

  20. 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.

  1. 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. .

  2. 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)

  3. 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.

  4. 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

  5. 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.

  6. Specific power of liquid-metal-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Dobranich, D.

    1987-10-01

    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.

  7. 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.

  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. 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. Thermionic Technology Program, fiscal year 1986: Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Cone, V.P.; Dunlay, J.B.

    1987-12-01

    During FY 1986, the Thermionic Technology Program at Thermo Electron Corporation concentrated on advancing the development of cermet sheath insulators and additive converters. Both development efforts were based on the thermionic technology established by thermionic reactor programs during the 1960's and early 1970's. Improved sheath insulators and additive converters were fabricated during FY 1986 and delivered to Rasor Associates Incorporated, for extensive testing and evaluation. The most promising cermet fabrication process changed from dry ceramic powder coating of niobium spherical particles to the use of water-based slurries of ceramic powder and fine, irregularly shaped, niobium powder. Slurry processing is much more controlled and reproducible. The fabrication of crack-free, fully dense yttria alumina garnet (YAG) sheath insulator trilayers remains to be accomplished. Measurements of the thermal expansion of YAG indicate that the expansion mismatch with niobium (particularly from 1300 to 1500 C) may cause cracking. Limited evidence also suggests that high-temperature (1500 C and higher) reactions between YAG and niobium may also contribute to cracking. Alternative fabrication schedules need to be explored to minimize these adverse high-temperature effects. Preliminary tests indicate that alternative ceramics, such as oxide composites and aluminum oxynitride (ALON), show promise as improved sheath insulators. 41 figs., 5 tabs.

  11. 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.

  12. 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.

  13. 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.).

  14. In situ studies of fuel oxidation in solid oxide fuel cells.

    Science.gov (United States)

    Pomfret, Michael B; Owrutsky, Jeffrey C; Walker, Robert A

    2007-03-15

    Existing electrochemical experiments and models of fuel oxidation postulate about the importance of different oxidation pathways and relative fuel conversion efficiencies, but specific information is often lacking. Experiments described below present the first direct, in situ measurements of relevant chemical species formed on solid oxide fuel cell (SOFC) cermet anodes operating with both butane and CO fuel feeds. Raman spectroscopy is used to acquire vibrational spectra from SOFC anodes at 715 degrees C during operation. Both C4H10 and CO form graphitic intermediates. In the limit of a large oxide flux, excess butane forms ordered graphite but only transiently. At higher cell potentials (e.g., less current being drawn) ordered and disordered graphite form on the Ni cermet anode following exposure to butane, and under open circuit voltage (OCV) conditions the graphite persists indefinitely. The chemistry of CO oxidation is such that ordered graphite and a Ni-COO intermediate form only at intermediate cell potentials. Concurrent voltammetry studies show that the formation of graphite with butane at OCV leads first to decreased cell performance after exposure to 25 cm3 butane, then recovered performance after 75 cm3. CO voltammetry data show that at lower potentials the oxide flux through the YSZ electrolyte is sufficient to oxidize the Ni in the anode especially near the interface with the electrolyte.

  15. 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.

  16. Mesoporous NiO-samaria doped ceria for low-temperature solid oxide fuel cells.

    Science.gov (United States)

    Kim, Jin-Yeop; Kim, Ji Hyeon; Choi, Hyung Wook; Kim, Kyung Hwan; Park, Sang Joon

    2014-08-01

    In order to prepare anode material for low-temperature solid oxide fuel cells (SOFCs), the mesoporous NiO-SDC was synthesized using a cationic surfactant (cetyltrimethyl-ammonium bromide; CTAB) for obtaining wide triple-phase boundary (TPB). In addition, Ni-SDC anode-supported SOFC single cells with YSZ electrolyte and LSM cathode were fabricated and the performance of single cells was evaluated at 600 °C. The microstructure of NiO-SDC was characterized by XRD, EDX, SEM, and BET, and the results showed that the mesoporous NiO-SDC with 10 nm pores could be obtained. It was found that the surface area and the electrical performance were strongly influenced by the Ni content in Ni-SDC cermets. After calcined at 600 °C, the surface area of NiO-SDC was between 90-117 m2/g at 35-45 Ni wt%, which was sufficiently high for providing large TPB in SOFC anode. The optimum Ni content for cell performance was around 45 wt% and the corresponding MPD was 0.36 W/cm2. Indeed, the mesoporous NiO-SDC cermet may be of interest for use as an anode for low-temperature SOFCs.

  17. 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.

  18. 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.

  19. The Dry Sliding Wear Behavior of HVOF-Sprayed WC: Metal Composite Coatings

    Science.gov (United States)

    Ward, Liam P.; Pilkington, Antony

    2014-09-01

    WC-based cermet coatings containing various metallic binders such as Ni, Co, and Cr are known for their superior tribological properties, particularly abrasion resistance and enhanced surface hardness. Consequently, these systems are considered as replacements for traditional hard chrome coatings in critical aircraft components such as landing gear. The purpose of this investigation was to conduct a comparative study on the dry sliding wear behavior of three WC-based cermet coatings (WC-12Ni, WC-20Cr2C3-7Ni, and WC-10Co-4Cr), when deposited on carbon steel substrates. Ball on disk wear tests were performed on the coatings using a CSEM Tribometer (pin-on-disk) with a 6-mm ruby ball at 20 N applied load, 0.2 m/s sliding velocity, and sliding distances up to 2000 m. Analysis of both the coating wear track and worn ruby ball was performed using optical microscopy and an Alphastep-250 profilometer. The results of the study revealed both wear of the ruby ball and coated disks allowed for a comparison of both the ball wear and coating wear for the systems considered. Generally, the use of Co and Cr as a binder significantly improved the sliding wear resistance of the coating compared to Ni and/or Cr2C3.

  20. 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.

  1. 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.

  2. Preparation of 6061 Borated Al alloy by hot isostatic pressing (HIP)

    Energy Technology Data Exchange (ETDEWEB)

    Uhm, Young Rang; Park, Jin Ju; Rhee, Chang Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Rhee, Won Hyuk [Daewha alloy technology Co., Hwaseong (Korea, Republic of)

    2012-05-15

    Neutron absorber for wet/dry spent fuel storage applications are used in plate or sheet form. Neutron absorber materials are comprised of a chemical form of the neutron absorber nuclide and a matrix that serve to hold the absorber nuclide in its intended location. Of the metal matrix neutron absorbers, aluminum has been the most commonly used although stainless steel is another choice that has been used, extensively. Aluminum (Al) matrix absorbers can be manufactured to generally thin plate form by a variety of methods. In one method, a preform with near maximum theoretical density can be produced by casting and hot rolling. In another, aluminum and boron carbide with a full dense is produced using powder metallurgy technology. This is well known as metal matrix composites (MMCs) such as BORAL. This material is prepared by hot rolling a cubic aluminum ingot containing powdered aluminum and boron carbide. Discontinuously reinforced aluminum /boron carbide (B{sub 4}C) composite like a cermet offer a product with superior mechanical properties relative to the aluminum alloys itself. However, the density of this cermet is less than 100 % dense due to some internal porosity in MMCs. The hot isostatic pressing (HIP) is a candidate to get full density. In this study, MMCs of aluminum and boron carbide were prepared by powder mixing and canning HIP process. The density of prepared plate were measured by using gas pycnometer method, and compared to MMCs produced by METAMIC Co

  3. Electrochemical and microstructural characterization of cyclic redox behaviour of SOFC anodes

    Institute of Scientific and Technical Information of China (English)

    KONG Jiangrong; SUN Kening; ZHOU Derui; ZHANG Naiqing; QIAO Jinshuo

    2006-01-01

    The oxidation of Ni to NiO in solid oxide fuel cell (SOFC) anode will result in large bulk volume change, which may change the interfaces of the two phases in the anode cermet and thus may cause significant performance degradation. The reduction and oxidation (redox) of the Ni/YSZ cermet were studied at 800 ℃. Anodic polarization measurements were performed before and after redox cycles. The anode current density at an overpotential of 100 mV kept decreasing during the whole redox treatment. It decreased from 19.11 to 7.95 mA·cm-2 after two redox cycles. Anode supported unit cell was assembled for cell's discharge measurements. Cell performance declined after each redox cycle. The maximum power density decreased from 126.28 to 40.32 mW·cm-2 . The microstructural changes after redox cycling were recorded using scanning electron microscopy (SEM). The results reveal that after re-oxidation, the Ni gets coarse and has a higher porosity; the nickel network structure turns to be desultory.

  4. Low Earth Orbit Environmental Durability of Recently Developed Thermal Control Coatings

    Science.gov (United States)

    Jaworske, Donald A.

    2015-01-01

    The Materials International Space Station Experiment provided a means to expose materials and devices to the low Earth orbit environment on the exterior of the International Space Station. By returning the specimens to Earth after flight, the specimens could be evaluated by comparison with pre-flight measurements. One area of continuing interest is thermal control paints and coatings that are applied to exterior surfaces of spacecraft. Though traditional radiator coatings have been available for decades, recent work has focused on new coatings that offer custom deposition or custom optical properties. The custom deposition of interest is plasma spraying and one type of coating recently developed as part of a Small Business Innovative Research effort was designed to be plasma sprayed onto radiator surfaces. The custom optical properties of interest are opposite to those of a typical radiator coating, having a combination of high solar absorptance and low infrared emittance for solar absorber applications, and achieved in practice via a cermet coating. Selected specimens of the plasma sprayed coatings and the solar absorber coating were flown on Materials International Space Station Experiment 7, and were recently returned to Earth for post-flight analyses. For the plasma sprayed coatings in the ram direction, one specimen increased in solar absorptance and one specimen decreased in solar absorptance, while the plasma sprayed coatings in the wake direction changed very little in solar absorptance. For the cermet coating deployed in both the ram and wake directions, the solar absorptance increased. Interestingly, all coatings showed little change in infrared emittance.

  5. 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。

  6. Investigations into the interactions between sulfur and anodes for solid oxide fuel cells

    Science.gov (United States)

    Cheng, Zhe

    Solid oxide fuel cells (SOFCs) are electrochemical devices based on solid oxide electrolytes that convert chemical energy in fuels directly into electricity via electrode reactions. SOFCs have the advantages of high energy efficiency and low emissions and hold the potential to be the power of the future especially for small power generation systems (1-10 kW). Another unique advantage of SOFCs is the potential to directly utilize hydrocarbon fuels such as natural gas through internal reforming. However, all hydrocarbon fuels contain some sulfur compounds, which transform to hydrogen sulfide (H2S) in the reforming process and dramatically degrade the performance of the existing SOFCs. In this study, the interactions between sulfur contaminant (in the form of H2S) and the anodes for SOFCs were systematically investigated in order to gain a fundamental understanding of the mechanism of sulfur poisoning and ultimately to achieve rational design of sulfur-tolerant anodes. The sulfur poisoning behavior of the state-of-the-art Ni-YSZ cermet anodes was characterized using electrochemical measurements performed on button cells (of different structures) under various operating conditions, including H2S concentration, temperature, cell current density/terminal voltage, and cell structure. Also, the mechanisms of interactions between sulfur and the Ni-YSZ cermet anode were investigated using both ex situ and in situ characterization techniques such as Raman spectroscopy. Results suggest that the sulfur poisoning of Ni-YSZ cermet anodes at high temperatures in fuels with ppm-level H2S is due not to the formation of multi-layer conventional nickel sulfides but to the adsorption of sulfur on the nickel surface. In addition, new sulfur-tolerant anode materials were explored in this study. Thermodynamic principles were applied to predict the stability of candidate sulfur-tolerant anode materials and explain complex phenomena concerning the reactivity of candidate materials with

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Electrical Resistance Measurements and Microstructural Characterization of the Anode/Interconnect Contact in Simulated Anode-Side SOFC Conditions

    DEFF Research Database (Denmark)

    Harthøj, Anders; Alimadadi, Hossein; Holt, Tobias

    2015-01-01

    in phase transformation of the steel and in formation of oxides with a poor electrical conductivity in the anode. In this study, the area specific resistance (ASR) of the steel Crofer 22 APU, in contact with a Ni/YSZ anode with and without a tape casted CeO2 barrier layer was measured in simulated SOFC....... The zone is austenitic at the exposure temperature but transforms to ferrite during cooling. When a CeO2 nickel diffusion barrier layer was used The ASR was considerably higher. These results imply that nickel diffusion is not only detrimental: It leads to microstructural instability but also results......Metallic interconnects in solid oxide fuel cell (SOFC) stacks are often in direct contact with a nickel/yttria stabilized zirconia (Ni/YSZ) cermet anode. Interdiffusion between the two components may occur at the operating temperature of 700–850◦C. The alteration of chemical composition can result...

  13. 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

  14. Stabilization of green bodies via sacrificial gelling agent during electrophoretic deposition

    Science.gov (United States)

    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.

  15. 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.

  16. 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)

  17. ANALYSIS OF CUTTING FORCE AND CHIP MORPHOLOGY DURING HARD TURNING OF AISI D2 STEEL

    Directory of Open Access Journals (Sweden)

    X. M. ANTHONY

    2015-03-01

    Full Text Available In this research work AISI D2 tool steel at a hardness of 55 HRC is being used for experimental investigation. Cutting speed, feed rate and depth of cut are the cutting parameters considered for the experimentation along with tool geometry namely, nose radius, clearance angle and rake angle. Three different cutting tool materials are used for experimentation namely multicoated carbide, cermet and ceramic inserts. The cutting force generated during the machining process is being measured using Kistler dynamometer and recorded for further evaluation. The chips produced during the machining process for every experimental trail is also collected for understanding the chip morphology. Based on the experimental data collected Analysis of Variance (ANOVA was conducted to understand the influence of all cutting parameters and tool geometry on cutting force.

  18. 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.

  19. Slurry Erosion Performance Study of Detonation Gun-Sprayed WC-10Co-4Cr Coatings on CF8M Steel Under Hydro-Accelerated Conditions

    Science.gov (United States)

    Bhandari, Sanjeev; Singh, Harpreet; Kumar, Harmesh; Rastogi, Vikas

    2012-09-01

    In the current investigation, cermet coatings (WC-10Co-4Cr) were deposited on CF8M steel by detonation gun (D-gun) thermal spraying process. Subsequently, the slurry erosion behaviors of the coated and bare steels were investigated using a high-speed erosion test rig. Slurry collected from an actual hydro power plant was used as the abrasive media. Effects of concentration (ppm), average particle sizes and rotational speed on the slurry erosion behaviors of coated and bare steels under different experimental conditions were studied. The analysis of eroded samples was done using SEM and stylus profilometry. Signatures of microcutting, fracture of well-bonded WC grains, and fragmentations were observed on the eroded surface of WC-10Co-4Cr coating, while signatures of formation of plowing, lips, shearing of platelet, formation of crater, and micro-cutting were observed on the eroded surface of CF8M steel.

  20. 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.

  1. 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.

  2. 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.

  3. Composition, Processing Technology and Property of Ceramic Die Materials Containing Rare Earth Additives

    Institute of Scientific and Technical Information of China (English)

    Xiao Guangchun; Xu Chonghai; Fang Bin

    2007-01-01

    Development and application of new ceramic die materials is one of the important topics in the field of die research. The composition, processing technology, mechanical property and engineering performance of the ceramic materials such as cermet, ZTA, TZP, TZP/Al2O3, TZP/TiC/Al2O3, PSZ and Sialon, etc., with rare earth yttrium, lanthanum and cerium, and so on working as additives, were investigated and analyzed in the present study. Problems existed in the research and application of rare earth ceramic die materials were discussed. Rare earth additives can effectively improve the mechanical property and engineering performance of ceramic die materials. Thus, it will have further perspectives of wider application. More attention should be paid in the future to the toughening and strengthening of the ceramic die materials, the adding forms and kinds of rare earth elements and acting mechanisms of rare earth additives in ceramic die materials.

  4. Fabrication of planar SOFC components at ECN

    Energy Technology Data Exchange (ETDEWEB)

    Huijsmans, J.P.P.; Siewers, E.J.; Van Heuveln, F.H.; De Jong, J.P.

    1991-03-01

    ECN is involved in several R and D programs for the development and testing of ceramic materials and components for flat plate SOFC reactors. Tape casting is used as the technique to manufacture SOFC components. First, the zirconia electrolyte (8YSZ) is tape cast, densified by firing and characterized. Then, the anode (Ni/YSZ cermet) and cathode ((La,Sr)MnO{sub 3}) structures are applied. The thickness of the electrolyte is 100-150 micrometer and that of the electrodes 30 micrometer. Firing of the electrodes occurs in oxidizing atmospheres at temperatures that ensure bonding to the electrolyte, but prevent degradation of the microstructure or the formation of reaction products on the electrolyte/electrode interfaces. 4 figs., 9 refs., 1 tab.

  5. 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)

  6. Preparation and characters of anode Ni-YSZ nanotubes of SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Meng, X.; Yang, N.; Tan, X. [Shandong Univ., Zibo (China). Dept. of Chemical Engineering

    2010-07-01

    Nickel/yttria-stabilized zirconia (Ni-YSZ) cermet composite nanotubes with a high specific surface area were synthesized using the sol-gel method with a porous anodic alumina oxide (AAO) as a template. X-ray diffraction (XRD) scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BET measurements were conducted to characterize the samples. The catalytic performance of the Ni-YSZ nanotubes was also evaluated using a fixed bed reactor. The analyses demonstrated that the nanotubes were approximately 200 nm. The methane conversion rate was improved by approximately 10 per cent. Results of the study suggested that the Ni-YSZ nanotubes possessed a higher catalytic performance than other Ni-YSZ powders in relation to methane oxidation. The improved performance was attributed to the higher specific surface of the nanotubes. Results indicated that the nanotubes can be used in solid oxide fuel cell (SOFC) applications. 4 refs.

  7. Plasma preparation and low-temperature sintering of spherical TiC-Fe composite powder

    Institute of Scientific and Technical Information of China (English)

    Jian-jun Wang; Jun-jie Hao; Zhi-meng Guo; Song Wang

    2015-01-01

    A spherical Fe matrix composite powder containing a high volume fraction (82vol%) of fine TiC reinforcement was produced us-ing a novel process combining in situ synthesis and plasma techniques. The composite powder exhibited good sphericity and a dense struc-ture, and the fine sub-micron TiC particles were homogeneously distributed in theα-Fe matrix. A TiC–Fe cermet was prepared from the as-prepared spherical composite powder using powder metallurgy at a low sintering temperature;the product exhibited a hardness of HRA 88.5 and a flexural strength of 1360 MPa. The grain size of the fine-grained TiC and special surface structure of the spherical powder played the key roles in the fabrication process.

  8. Break-down of Losses in High Performing Metal-Supported Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Kromp, Alexander; Nielsen, Jimmi; Blennow Tullmar, Peter;

    2012-01-01

    present the results of performance and stability improvements for a metal supported cell developed within the European project METSOFC and the Danish National Advanced Technology Foundation. The cells consist of a porous metal backbone, a metal / zirconia cermet anode and a 10ScYSZ electrolyte, cofired...... in hydrogen. The electrochemically active parts were applied by infiltrating CGO-Ni precursor solution into the porous metal and anode backbone and screenprinting (La,Sr)(Co,Fe)O3-based cathodes. To prevent a solid state reaction between cathode and zirconia electrolyte, CGO buffer layers were applied...... in between cathode and electrolyte. The detailed electrochemical characterization by means of impedance spectroscopy and a subsequent data analysis by the distribution of relaxation times enabled us to separate the different loss contributions in the cell. Based on an appropriate equivalent circuit model...

  9. Impurity features in Ni-YSZ-H2-H2O electrodes

    DEFF Research Database (Denmark)

    Utz, A.; Hansen, Karin Vels; Norrman, Kion;

    2011-01-01

    -of-flight secondary ion mass spectrometry). This analysis yields comprehensive information on composition and lateral distribution of impurity species as well as the size of impurity features. Small impurity striations are found at the triple phase boundary (TPB) as well as on the former electrode......–electrolyte interface and the impurity features were found to be influenced by the electrode configuration and the initial behavior of the Ni electrode during thermal exposure (creep or shrinkage).Furthermore, the electrochemical performance (the line specific resistance LSR) was compared to data reported for Ni point...... anodes. Good agreement was obtained for data with comparable impurity features.Additionally, an order of magnitude estimation of the effect of SiO2 content on surface coverage with an impurity film is performed for different electrode designs (point, patterned and cermet anode) and shows different...

  10. 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)

  11. On the stability of Sr-doped La{sub 2}CuO{sub 4} against different electrolytes for IT-SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz-Bustos, R.; Santos-Garcia, A.J. dos; Sanchez-Bautista, C. [Instituto de Energias Renovables, Parque Cientifico y Tecnologico de Albacete, Paseo de la Investigacion 1, 02006 Albacete (Spain); Cantos-Gomez, A.; Duijn, J. van [Instituto de Energias Renovables, Universidad de Castilla La Mancha, Paseo de la Investigacion 1, 02006 Albacete (Spain)

    2011-02-15

    The thermal stability of the cathode material against an electrolyte at the operating temperature plays an important role in the fuel cell's performance. As such, compatibility tests of the most common used electrolytes with La{sub 2-x}Sr{sub x}CuO{sub 4} have been performed. The chemical reaction between these two materials in the temperature ranging from 800 to 1,000 C was examined by X-ray diffraction analyses. The results show that in all the cases there is reaction above 925 C, making conventional cell fabrication non-appropriate. However, we demonstrate that infiltration is a useful technique for obtaining cuprate cermets for use as cathode materials in IT-SOFCs. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Optical materials technology for energy efficiency and solar energy conversion VII; Proceedings of the Meeting, Hamburg, Federal Republic of Germany, Sept. 19-21, 1988

    Science.gov (United States)

    Granqvist, Claes G.; Lampert, Carl M.

    Various papers on optical materials technology for energy efficiency and solar energy conversion are presented. Individual topics addressed include: nonlinear optical effects in organic molecules and polymers, optical and electrical properties of amorphous Li(x)WO3 films, electrochromism in sputtered vanadium pentoxide, characterization of nickel oxide electrochromic films, radiative cooling with pigmented polyethylene foils, plasma-film interactions in RF sputtered a-Si:H and a-Ge:H, metal oxyfluoride coatings for energy-efficient windows, fatigue-resistant photochromic plastics, evaporated VO(x) thin films, electrochromism in nickel oxide films, system design for high-rate deposition of indium oxide solar coatings, performance and bandwidth analysis of holographic solar reflectors, laser and spectroscopic characterization of thin films, high-efficiency collectors for solar energy applications, influence of surface roughness on the optical properties of cermet coatings, and sputtered aluminum composite selective absorbing surfaces.

  17. 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

  18. DOE advanced thermionic technology program. Progress report No. 46, January, February, March 1981

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    The primary long-term goal is to improve thermionic performance to the level that thermionic topping of fossil-fuel powerplants becomes technically possible and economically attractive. An intermediate goal is to operate a thermionic module in a powerplant during the mid-1980's. A short-term goal is to demonstrate reliable thermionic operation in a combustion environment. This report covers progress made during the three-month period from January through March 1981. During this period, significant accomplishments include: (1) continuing stable output from the combustion test of the one-inch diameter hemispherical silicon carbide diode at an emitter temperature of 1730 K for a period of over 6400 hours; (2) demonstration of an additive oxygen effect in a research diode with a cesium-graphite reservoir located in the collector; (3) preliminary testing of the four-diode module; and (4) evaluation of a research diode with ZrO/sub 2/-Mo cermet electrodes.

  19. Oxide anode materials for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Fergus, Jeffrey W. [Auburn University, Materials Research and Education Center, 275 Wilmore Laboratories, Auburn, AL 36849 (United States)

    2006-07-15

    A major advantage of solid oxide fuel cells (SOFCs) over polymer electrolyte membrane (PEM) fuel cells is their tolerance for the type and purity of fuel. This fuel flexibility is due in large part to the high operating temperature of SOFCs, but also relies on the selection and development of appropriate materials - particularly for the anode where the fuel reaction occurs. This paper reviews the oxide materials being investigated as alternatives to the most commonly used nickel-YSZ cermet anodes for SOFCs. The majority of these oxides form the perovskite structure, which provides good flexibility in doping for control of the transport properties. However, oxides that form other crystal structures, such as the cubic fluorite structure, have also shown promise for use as SOFC anodes. In this paper, oxides are compared primarily in terms of their transport properties, but other properties relative to SOFC anode performance are also discussed. (author)

  20. Impact of anode microstructure on solid oxide fuel cells.

    Science.gov (United States)

    Suzuki, Toshio; Hasan, Zahir; Funahashi, Yoshihiro; Yamaguchi, Toshiaki; Fujishiro, Yoshinobu; Awano, Masanobu

    2009-08-14

    We report a correlation between the microstructure of the anode electrode of a solid oxide fuel cell (SOFC) and its electrochemical performance for a tubular design. It was shown that the electrochemical performance of the cell was extensively improved when the size of constituent particles was reduced so as to yield a highly porous microstructure. The SOFC had a power density of greater than 1 watt per square centimeter at an operating temperature as low as 600 degrees C with a conventional zirconia-based electrolyte, a nickel cermet anode, and a lanthanum ferrite perovskite cathode material. The effect of the hydrogen fuel flow rate (linear velocity) was also examined for the optimization of operating conditions. Higher linear fuel velocity led to better cell performance for the cell with higher anode porosity. A zirconia-based cell could be used for a low-temperature SOFC system under 600 degrees C just by optimizing the microstructure of the anode electrode and operating conditions.

  1. 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.

  2. 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.

  3. U.S. program assessing nuclear waste disposal in space - A status report

    Science.gov (United States)

    Rice, E. E.; Priest, C. C.; Friedlander, A. L.

    1980-01-01

    Various concepts for the space disposal of nuclear waste are discussed, with attention given to the destinations now being considered (high earth orbit, lunar orbit, lunar surface, solar orbit, solar system escape, sun). Waste mixes are considered in the context of the 'Purex' (Plutonium and Uranium extraction) process and the potential forms for nuclear waste disposal (ORNL cermet, Boro-silicate glass, Metal matrix, Hot-pressed supercalcine) are described. Preliminary estimates of the energy required and the cost surcharge needed to support the space disposal of nuclear waste are presented (8 metric tons/year, requiring three Shuttle launches). When Purex is employed, the generated electrical energy needed to support the Shuttle launches is shown to be less than 1%, and the projected surcharge to electrical users is shown to be slightly more than two mills/kW-hour.

  4. 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.

  5. 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。

  6. Hydrogen transport membranes

    Science.gov (United States)

    Mundschau, Michael V.

    2005-05-31

    Composite hydrogen transport membranes, which are used for extraction of hydrogen from gas mixtures are provided. Methods are described for supporting metals and metal alloys which have high hydrogen permeability, but which are either too thin to be self supporting, too weak to resist differential pressures across the membrane, or which become embrittled by hydrogen. Support materials are chosen to be lattice matched to the metals and metal alloys. Preferred metals with high permeability for hydrogen include vanadium, niobium, tantalum, zirconium, palladium, and alloys thereof. Hydrogen-permeable membranes include those in which the pores of a porous support matrix are blocked by hydrogen-permeable metals and metal alloys, those in which the pores of a porous metal matrix are blocked with materials which make the membrane impervious to gases other than hydrogen, and cermets fabricated by sintering powders of metals with powders of lattice-matched ceramic.

  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. 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...

  9. Development Status of a CVD System to Deposit Tungsten onto UO2 Powder via the WCI6 Process

    Science.gov (United States)

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

    2014-01-01

    Nuclear Thermal Propulsion (NTP) is under development for deep space exploration. NTP's high specific impulse (> 850 second) enables a large range of destinations, shorter trip durations, and improved reliability. W-60vol%UO2 CERMET fuel development efforts emphasize fabrication, performance testing and process optimization to meet service life requirements. Fuel elements must be able to survive operation in excess of 2850 K, exposure to flowing hydrogen (H2), vibration, acoustic, and radiation conditions. CTE mismatch between W and UO2 result in high thermal stresses and lead to mechanical failure as a result UO2 reduction by hot hydrogen (H2) [1]. Improved powder metallurgy fabrication process control and mitigated fuel loss can be attained by coating UO2 starting powders within a layer of high density tungsten [2]. This paper discusses the advances of a fluidized bed chemical vapor deposition (CVD) system that utilizes the H2-WCl6 reduction process.

  10. Resistance of Cavitation Erosion of HVOF Sprayed WC-Co( Cr) Coating in NaCl Solution%超音速火焰喷涂WC-Co(Cr)涂层在NaCl溶液中抗空蚀性能研究

    Institute of Scientific and Technical Information of China (English)

    丁彰雄; 石琎; 丁翔; 胡一鸣; 廖星文; 邓帮华

    2016-01-01

    Two micro-structured WC-10Co4Cr cermet coatings and a nano-structured WC-12Co cermet coating are deposited by high velocity Oxy-fuel spray ( HVOF) , and the morphologies and structures of the coatings are analyzed by SEM .The coatings'porosity , fracture toughness and microhardness are measured .The CorrTest electrochemical testing system is used to analyze the electrochemical corrosion properties of the coatings .Resistance of coatings to cavitation erosion is studied by ultrasonic vibration cavitation equipment in 3.5wt%NaCl solution and the cavitation mechanisms are explored .It is shown that the nano-structured WC-12Co coating deposited by high velocity oxygen liquid fuel spray has lowest porosity and the densest microstructure , and frac-ture toughness is significantly higher than that of micron-structured WC-10Co4Cr coatings.Although the micron-structured WC-10Co4Cr cermet coating deposited by high velocity fuel oxygen liquid spray has coarser particles than the nano -structured, it ex-hibits the most excellent corrosion and cavitation erosion resistance .The cavitation rate is approximately one quarter that of the nano-structured WC-12Co cermet coating in 3.5wt%NaCl solution.%采用超音速火焰喷涂(HVOF)工艺制备2种微米结构WC-10Co4Cr及1种纳米结构WC-12Co金属陶瓷复合涂层;采用SEM分析涂层的组织结构;测量了涂层的显微硬度、孔隙率及开裂韧性;采用CorrT-est电化学测试系统分析涂层的电化学腐蚀性能;采用超声振动空蚀装置研究涂层在质量分数为3.5% NaCl溶液中的抗空蚀性能,探讨涂层的空蚀机理. 结果表明:使用液体燃料HVOF工艺喷涂的纳米WC-12Co涂层组织结构最细小,孔隙率最低,显微硬度和开裂韧性明显高于液体燃料和气体燃料HVOF工艺喷涂的微米WC-10Co4Cr涂层;采用液体燃料HVOF工艺喷涂的微米结构WC-10Co4Cr涂层在质量分数为3.5%NaCl溶液中显示了最优异的抗腐蚀和抗空蚀

  11. 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)

  12. Research and development activities: high-level waste immobilization program. Quarterly progress report, April-June 1979

    Energy Technology Data Exchange (ETDEWEB)

    McElroy, J.L.; Mendel, J.E.; Bonner, W.F.; Henry, M.H.

    1979-12-01

    Test results are available on 21 out of a total of 65 glass compositions in a generic study of composition effects on waste glass properties such as Soxhlet leach rate, viscosity, electrical conductivity, and volatility. Preliminary results indicate the leaching behavior of a Cermet waste form prepared at ORNL is similar to that of waste glass and supercalcine. Scanning transmission electron microscopy has confirmed that supercalcine contains up to 10 vol% glassy phase and that small fractions of Cs, Sr, and rare earth reside in the glassy phase. Two long-term runs were completed in the ceramic melter coupled directly to the full-scale spray calciner. Two new ceramic melters were put into operation. A preliminary test in the small spray calciner indicates that coal, which is present in some Savannah River Plant wastes, is only partially decomposed during spray calcination. 15 figures, 11 tables.

  13. Multi-objective genetic algorithm for the optimization of a flat-plate solar thermal collector.

    Science.gov (United States)

    Mayer, Alexandre; Gaouyat, Lucie; Nicolay, Delphine; Carletti, Timoteo; Deparis, Olivier

    2014-10-20

    We present a multi-objective genetic algorithm we developed for the optimization of a flat-plate solar thermal collector. This collector consists of a waffle-shaped Al substrate with NiCrOx cermet and SnO(2) anti-reflection conformal coatings. Optimal geometrical parameters are determined in order to (i) maximize the solar absorptance α and (ii) minimize the thermal emittance ε. The multi-objective genetic algorithm eventually provides a whole set of Pareto-optimal solutions for the optimization of α and ε, which turn out to be competitive with record values found in the literature. In particular, a solution that enables α = 97.8% and ε = 4.8% was found.

  14. Investigation on the Tribological Behavior of Arc-Sprayed and Hammer-Peened Coatings Using Tungsten Carbide Cored Wires

    Science.gov (United States)

    Tillmann, W.; Hagen, L.; Schröder, P.

    2017-01-01

    Due to their outstanding properties, WC-W2C iron-based cermet coatings are widely used in the field of wear protection. Regarding commonly used WC-W2C reinforced coating systems, it has been reported that their tribological behavior is mainly determined by the carbide grain size fraction. Although the manufacturing route for arc-sprayed WC-W2C cermet coatings is in an advanced state, there is still a lack of knowledge concerning the performance of cored wires with tungsten carbides as filling material and their related coating properties when post-treatment processes are used such as machine hammer peening (MHP). A major objective was to characterize WC-W2C FeCMnSi coatings, deposited with different carbide grain size fractions as a filling using cored wires, with respect to their tribological behavior. Moreover, deposits derived from cored wires with a different amount of hard phases are investigated. According to this, polished MHP surfaces are compared to as-sprayed and polished samples by means of metallographic investigations. With the use of ball-on-disk and dry rubber wheel tests, dry sliding and rolling wear effects on a microscopic level are scrutinized. It has been shown that the MHP process leads to a densification of the microstructure formation. For dry sliding experiments, the MHP coatings obtain lower wear resistances, but lower coefficients of friction than the conventional coatings. In view of abrasion tests, the MHP coatings possess an improved wear resistance. Strain hardening effects at the subsurface area were revealed by the mechanical response using nanoindentation. However, the MHP process has caused a cracking of embedded carbides, which favor breakouts, leading to advanced third-body wear.

  15. Mini-MITEE: Ultra Small, Ultra Light NTP Engines for Robotic Science and Manned Exploration Missions

    Science.gov (United States)

    Powell, James; Maise, George; Paniagua, John

    2006-01-01

    A compact, ultra lightweight Nuclear Thermal Propulsion (NTP) engine design is described with the capability to carry out a wide range of unique and important robotic science missions that are not possible using chemical or Nuclear Electric Propulsion (NEP). The MITEE (MInature ReacTor EnginE) reactor uses hydrogeneous moderator, such as solid lithium-7 hydride, and high temperature cermet tungsten/UO2 nuclear fuel. The reactor is configured as a modular pressure tube assembly, with each pressure tube containing an outer annual shell of moderator with an inner annular region of W/UO2 cermet fuel sheets. H2 propellant flows radially inwards through the moderator and fuel regions, exiting at ~3000 K into a central channel that leads to a nozzle at the end of the pressure tube. Power density in the fuel region is 10 to 20 megawatts per liter, depending on design, producing a thrust output on the order of 15,000 Newtons and an Isp of ~1000 seconds. 3D Monte Carlo neutronic analyses are described for MITEE reactors utilizing various fissile fuel options (U-235, U-233, and Am242m) and moderators (7LiH and BeH2). Reactor mass ranges from a maximum of 100 kg for the 7LiH/U-235 option to a minimum of 28 kg for the BeH2/Am-242 m option. Pure thrust only and bi-modal (thrust plus electric power generation) MITEE designs are described. Potential unique robotic science missions enabled by the MITEE engine are described, including landing on Europa and exploring the ice sheet interior with return of samples to Earth, hopping to and exploring multiple sites on Mars, unlimited ramjet flight in the atmospheres of Jupiter, Saturn, Uranus, and Neptune and landing on, and sample return from Pluto.

  16. Investigation on the Tribological Behavior of Arc-Sprayed and Hammer-Peened Coatings Using Tungsten Carbide Cored Wires

    Science.gov (United States)

    Tillmann, W.; Hagen, L.; Schröder, P.

    2016-12-01

    Due to their outstanding properties, WC-W2C iron-based cermet coatings are widely used in the field of wear protection. Regarding commonly used WC-W2C reinforced coating systems, it has been reported that their tribological behavior is mainly determined by the carbide grain size fraction. Although the manufacturing route for arc-sprayed WC-W2C cermet coatings is in an advanced state, there is still a lack of knowledge concerning the performance of cored wires with tungsten carbides as filling material and their related coating properties when post-treatment processes are used such as machine hammer peening (MHP). A major objective was to characterize WC-W2C FeCMnSi coatings, deposited with different carbide grain size fractions as a filling using cored wires, with respect to their tribological behavior. Moreover, deposits derived from cored wires with a different amount of hard phases are investigated. According to this, polished MHP surfaces are compared to as-sprayed and polished samples by means of metallographic investigations. With the use of ball-on-disk and dry rubber wheel tests, dry sliding and rolling wear effects on a microscopic level are scrutinized. It has been shown that the MHP process leads to a densification of the microstructure formation. For dry sliding experiments, the MHP coatings obtain lower wear resistances, but lower coefficients of friction than the conventional coatings. In view of abrasion tests, the MHP coatings possess an improved wear resistance. Strain hardening effects at the subsurface area were revealed by the mechanical response using nanoindentation. However, the MHP process has caused a cracking of embedded carbides, which favor breakouts, leading to advanced third-body wear.

  17. Desirability-Based Multi-Criteria Optimization of HVOF Spray Experiments to Manufacture Fine Structured Wear-Resistant 75Cr3C2-25(NiCr20) Coatings

    Science.gov (United States)

    Tillmann, W.; Vogli, E.; Baumann, I.; Kopp, G.; Weihs, C.

    2010-01-01

    Thermal spraying of fine feedstock powders allow the deposition of cermet coatings with significantly improved characteristics and is currently of great interest in science and industry. However, due to the high surface to volume ratio and the low specific weight, fine particles are not only difficult to spray but also show a poor flowability in the feeding process. In order to process fine powders reliably and to preserve the fine structure of the feedstock material in the final coating morphology, the use of novel thermal spray equipment as well as a thorough selection and optimization of the process parameters are fundamentally required. In this study, HVOF spray experiments have been conducted to manufacture fine structured, wear-resistant cermet coatings using fine 75Cr3C2-25(Ni20Cr) powders (-8 + 2 μm). Statistical design of experiments (DOE) has been utilized to identify the most relevant process parameters with their linear, quadratic and interaction effects using Plackett-Burman, Fractional-Factorial and Central Composite designs to model the deposition efficiency of the process and the majorly important coating properties: roughness, hardness and porosity. The concept of desirability functions and the desirability index have been applied to combine these response variables in order to find a process parameter combination that yields either optimum results for all responses, or at least the best possible compromise. Verification experiments in the so found optimum obtained very satisfying or even excellent results. The coatings featured an average microhardness of 1004 HV 0.1, a roughness Ra = 1.9 μm and a porosity of 1.7%. In addition, a high deposition efficiency of 71% could be obtained.

  18. 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.

  19. Study on Design and Performance of Anti-cavitation Erosion Coatings of LCQ Valve Splitter at Tianwan Nuclear Power Station%田湾核电站LCQ阀门分流片抗空蚀涂层设计及其性能研究

    Institute of Scientific and Technical Information of China (English)

    刘永生; 黄磊; 张云乾; 丁彰雄; 冯驰; 王韶毅; 邓帮华

    2015-01-01

    本文在分析核电站LCQ阀门分流片的空蚀失效机理基础上,设计了五种合金与金属陶瓷涂层.采用氧乙炔火焰喷熔和超音速火焰喷涂(HVOF)工艺分别制备了三种Ni基合金涂层与两种WC基金属陶瓷涂层;通过超声波振动空蚀试验装置对这些涂层进行抗空蚀试验,研究这些涂层的抗空蚀性能.结果表明:NiCrBSiMo喷熔层具有最优异的抗空蚀性能,可望应用于LCQ阀门分流片.%In this paper, on basis of the cavitation erosion failure mechanism of the LCQ valve splitter at nuclear power station, five kinds of alloy and cermet coatings were designed. Three kinds of nickel-based alloy coatings and two kinds of WC based cermet coatings were respectively deposited by oxyacetylene flame spraying and fusing process and High Velocity Oxy-Fuel spray(HVOF). Then the cavitation erosion resistance of these coatings was studied by ultrasonic vibration device. Results showed thatNiCrBSiMo coating prepared by spraying and fusing process has the most excellent anti-cavitation erosion performance,it can be applied to the LCQ valve splitter.

  20. 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

  1. 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

  2. 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

  3. Commercial Production Technique for Nanocrystalline Composite Powder of WC-Co%纳米晶复合碳化钨-钴粉末的工业化制备技术

    Institute of Scientific and Technical Information of China (English)

    吴伯麟; 邵刚勤; 段兴龙; 谢济仁; 魏明坤; 袁润章

    2000-01-01

    超细晶粒的WC-Co硬质合金具有高硬度、高强度的性能,纳米晶WC-Co复合粉末的合成是制备该合金的首要前提工作,中国正努力保持和强化"钨钴液相复合-喷雾干燥-流态化连续还原碳化技术"在国际的前沿优势。该技术将偏钨酸铵和水合硝酸钴以分子级水平混合,经喷雾干燥制备出CoWO4/WO3复合氧化物前驱体粉末,然后将前驱体粉末置于流态化反应炉中,在H2/CH4/CO2/N2气氛下经过连续的还原、碳化、调碳过程,得到无碳相的纳米晶WC-Co复合粉末。%Ultrafine grained WC-Co cermet has high hardness and highstrength. Preparing nanocrystalline WC-Co composite powder is one of the most important processes in the manufacture of the cermet. Currently Chinese researchers are leading the world in the area with their 'W/Co solution mixing-dry spraying-continuous fluidized reduction/carburization’technology. In this study, the precursor powder was prepared by mixing ammonium metatungstate and cobalt nitrate at the molecular level in distilled water and then spray-dried to form CoWO4/WO3 composite oxides. Through continuous reduction/carburization gas-solid reaction in a fluidized bed reactor in H2/CH4/CO2/N2, the precursor was converted to WC-Co nanocrystalline composite powder.

  4. 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.

  5. 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

  6. 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

  7. Damage tolerant functionally graded materials for advanced wear and friction applications

    Science.gov (United States)

    Prchlik, Lubos

    The research work presented in this dissertation focused on processing effects, microstructure development, characterization and performance evaluation of composite and graded coatings used for friction and wear control. The following issues were addressed. (1) Definition of prerequisites for a successful composite and graded coating formation by means of thermal spraying. (2) Improvement of characterization methods available for homogenous thermally sprayed coating and their extension to composite and graded materials. (3) Development of novel characterization methods specifically for FGMs, with a focus on through thickness property measurement by indentation and in-situ curvature techniques. (4) Design of composite materials with improved properties compared to homogenous coatings. (5) Fabrication and performance assessment of FGM with improved wear and impact damage properties. Materials. The materials studied included several material systems relevant to low friction and contact damage tolerant applications: MO-Mo2C, WC-Co cermets as materials commonly used sliding components of industrial machinery and NiCrAlY/8%-Yttria Partially Stabilized Zirconia composites as a potential solution for abradable sections of gas turbines and aircraft engines. In addition, uniform coatings such as molybdenum and Ni5%Al alloy were evaluated as model system to assess the influence of microstructure variation onto the mechanical property and wear response. Methods. The contact response of the materials was investigated through several techniques. These included methods evaluating the relevant intrinsic coating properties such as elastic modulus, residual stress, fracture toughness, scratch resistance and tests measuring the abrasion and friction-sliding behavior. Dry-sand and wet two-body abrasion testing was performed in addition to traditional ball on disc sliding tests. Among all characterization techniques the spherical indentation deserved most attention and enabled to

  8. 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.

  9. 硬质合金化学镀Ni/Co-P-Ag复合涂层工艺研究%Hard Alloy Electroless Plating Ni/Co-P-Ag Composite Coating

    Institute of Scientific and Technical Information of China (English)

    陈晓琼; 张怀清; 王金芳; 涂志标

    2016-01-01

    通过化学镀方式在经过清洗、粗化、活化的硬质合金表面镀覆了Ni/Co-P-Ag涂层。通过观察涂层的组织形貌,测试涂层的物理化学性能的方法研究了不同预处理工艺对化学镀Ag的影响,得到最佳的化学镀Co-P-Ag预处理方案。经过大量实验研究发现,通过预镀钴不仅能得到均匀的镀银涂层,化学镀Ag层还具备较好的结合力。%Ni/Co-P-Ag alloy film was deposited on the surface of cermet by electroless plating after cleaning, roughening and activation. Study the effects of different ways of Ag plating pretreatment by seeing the morphology of coating and testing the physical and chemical properties of coating, and the best Co-P-Ag plating pretreatment was obtained. Through large numbers of tests, we found that having a pre-cobalt layer before silver-plating could get a uniform coating, and the electroless silver plating layer has a forceful adhesion of the silver to the basis metal.

  10. 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.

  11. The Corrosion and Wear Performance of Microcrystalline WC-10Co-4Cr and Near-Nanocrystalline WC-17Co High Velocity Oxy-Fuel Sprayed Coatings on Steel Substrate

    Science.gov (United States)

    Saha, Gobinda C.; Khan, Tahir I.

    2010-11-01

    The study of near-nanocrystalline cermet composite coating was performed by depositing near-nanocrystalline WC-17Co powder using the high velocity oxy-fuel spraying technique. The WC-17Co powder consists of a core with an engineered near-nano-scale WC dispersion with a mean grain size 427 nm. The powder particle contains 6 wt pct of the ductile phase Co matrix mixed into the core to ensure that the reinforcing ceramic phase WC material is discontinuous to limit debridement during wear, while the remainder of the binding phase (11 wt pct) is applied as a coating on the powder particle to improve the ductility. The tribological properties of the coating, in terms of corrosion resistance, microhardness, and sliding abrasive wear, were studied and compared with those of an industrially standard microcrystalline WC-10Co-4Cr coating with a WC mean grain size 3 μm. Results indicated that the WC-17Co coating had superior wear and corrosion resistance compared to the WC-10Co-4Cr coating. The engineered WC-17Co powder with a duplex Co layer had prevented significant decarburization of the WC dispersion in the coating, thereby reducing the intersplat microporosity necessary for initiating microgalvanic cells. The improved wear resistance was attributed to the higher hardness value of the near-nanocrystalline WC-17Co coating.

  12. High Temperature Oxidation Behavior of HVOF-sprayed Coatings for Use in Thixoextrusion Processes

    Science.gov (United States)

    Picas, J. A.; Punset, M.; Menargues, S.; Campillo, M.; Baile, M. T.; Forn, A.

    2011-05-01

    The dies used for the thixoextrusion of steels have to be capable of withstanding complex thermal and mechanical loads, while giving a sufficient wear resistance against abrasion and adhesion at very high temperatures. In order to improve the wear resistance and reduce the heating of the extrusion die it can be protected with a hard cermet coating. The purpose of this work is to study the high-temperature performance of CrC-CoNiCrAlY coating and explore the potential application of this coating to improve dies used in thixoextrusion processes. A two-layer 75CrC-25CoNiCrAlY coating with a CoNiCrAlY bond-coating was fabricated by the HVOF thermal spray process on a steel substrate. Coatings were heat-treated at a range of temperatures between 900 °C and 1100 °C. The microstructural characterization of the coatings before and after heat treatment was conducted by scanning electron microscopy (SEM) and an X-ray diffractometer (XRD). The mechanical properties of coatings were determined as a function of the temperature of heat treatment. The bond coat effect on the thermal shock resistance of CrC-CoNiCrAlY coating was analyzed.

  13. [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.

  14. [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.

  15. [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.

  16. 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.

  17. Thermophysical and elastic properties of titanium carbonitrides containing molybdenum and tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, Tetsushi, E-mail: t_matsuda@jfcc.or.jp [Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan); Matsubara, Hideaki [Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587 (Japan)

    2013-06-15

    Highlights: ► (Ti,Me)(C,N) sintered bodies were prepared by hot-pressing. ► The thermophysical and elastic properties of the carbonitrides were evaluated. ► The porosities of the specimens were less than 1%. ► The Young’s modulus decreases with increasing Mo content. ► The Debye temperatures decrease with increasing Mo/W content. -- Abstract: Titanium carbonitride has good mechanical properties such as high hardness and high Young’s modulus. It is a major raw material for Ti(C,N)-based cermets, and their properties are strongly dependent on the properties of titanium carbonitrides. The thermophysical and elastic properties of the carbonitride need to be systematically investigated, so as to be used for designing cutting tools and wear-resistant tools. The thermophysical and elastic properties of (Ti,Me)(C,N) (Me = Mo. W) sintered bodies prepared by hot-pressing at 2200 °C were evaluated. The porosities of the specimens were less than 1%. The Young’s modulus decreased with increasing Mo, which seems to be the result of vacancy formation. The thermal expansion coefficient, the thermal conductivity and the Debye temperatures of (Ti,Me)(C,N) sintered bodies decreased with increasing Mo/W content.

  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. `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.

  20. Design of a uranium-dioxide powder spheroidization system by plasma processing

    Science.gov (United States)

    Cavender, Daniel

    The plasma spheroidization system (PSS) is the first process in the development of a tungsten-uranium dioxide (W-UO2) ceramic-metallic (cermet) fuel for nuclear thermal rocket (NTR) propulsion. For the purposes of fissile fuel retention, UO2 spheroids ranging in size from 50 - 100 micrometers (μm) in diameter will be encapsulated in a tungsten shell. The PSS produces spherical particles by melting angular stock particles in an argon-hydrogen plasma jet where they become spherical due to surface tension. Surrogate CeO 2 powder was used in place of UO2 for system and process parameter development. Stock and spheroidized powders were micrographed using optical and scanning electron microscopy and evaluated by statistical methods to characterize and compare the spherocity of pre and post process powders. Particle spherocity was determined by irregularity parameter. Processed powders showed a statistically significant improvement in spherocity, with greater that 60% of the examined particles having an irregularity parameter of equal to or lower than 1.2, compared to stock powder.

  1. 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.

  2. 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.

  3. Carbon dioxide reduction in a tubular solid oxide electrolysis cell for a carbon recycling energy system

    Energy Technology Data Exchange (ETDEWEB)

    Dipu, Arnoldus Lambertus, E-mail: dipu.a.aa@m.titech.ac.jp [Department of Nuclear Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Ujisawa, Yutaka [Nippon Steel and Sumitomo Metal Corporation, 16-1, Sunayama, Kamisu, Ibaraki 314-0255 (Japan); Ryu, Junichi; Kato, Yukitaka [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, 2-12-1-N1-22, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2014-05-01

    A new energy transformation system based on carbon recycling is proposed called the active carbon recycling energy system (ACRES). A high-temperature gas reactor was used as the main energy source for ACRES. An experimental study based on the ACRES concept of carbon monoxide (CO) regeneration via high-temperature reduction of carbon dioxide (CO{sub 2}) was carried out using a tubular solid oxide electrolysis cell employing Ni-LSM cermet|YSZ|YSZ-LSM as the cathode|electrolyte|anode. The current density increased with increasing CO{sub 2} concentration at the cathode, which was attributed to a decrease in cathode activation and concentration overpotential. Current density, as well as the CO and oxygen (O{sub 2}) production rates, increased with increasing operating temperature. The highest CO and O{sub 2} production rates of 1.24 and 0.64 μmol/min cm{sup 2}, respectively, were measured at 900 °C. Based on the electrolytic characteristics of the cell, the scale of a combined ACRES CO{sub 2} electrolysis/iron production facility was estimated.

  4. 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.

  5. Characterization of WC-10Ni HVOF Coating for Carbon Steel Blade

    Science.gov (United States)

    Ahmad, N. A.; Kamdi, Z.; Mohamad, Z.; Omar, A. S.; Latif, N. Abdul; Tobi, A. L. Mohd

    2017-01-01

    High Velocity Oxy-Fuel, HVOF is a depositing methods of a material layer over a base metal or substrate with characteristics of high flame velocity and moderate temperature. Where, tungsten carbide, WC cermet HVOF coatings is widely used to protect machine components from wear and corrosion. The main purpose of this present paper is to characterize the WC-10Ni coating deposited by HVOF thermal spray onto a carbon steel blade. The morphology and chemical composition of the coating were characterized by Scanning Electron Microstructure (SEM), electron dispersive spectrometer (EDS), and X-ray diffraction (XRD). The hardness test was carried out by using Vickers micro-hardness tester with loads of 490.3 mN (HV0.05). From XRD results, no sharp nickel peak was identified and has been replaced by a hump which indicate the amorphous Ni. The major crystalline phases were compounds WC, W2C and metallic phase of W. The WC-10Ni coating shows high hardness with low porosity distribution.

  6. Effective dielectric constants and spectral density analysis of plasmonic nanocomposites

    Science.gov (United States)

    Lu, Jin You; Raza, Aikifa; Fang, Nicholas X.; Chen, Gang; Zhang, TieJun

    2016-10-01

    Cermet or ceramic-metal composite coatings promise great potentials in light harvesting, but the complicated composite structure at the nanoscale induces a design challenge to predict their optical properties. We find that the effective dielectric constants of nanocomposites predicted by finite-difference-time-domain (FDTD) simulation results match those of different classical effective medium theories in their respective validity range. However, a precise prediction of the fabricated nanocomposite properties for different filling factors is very challenging. In this work, we extract the spectral density functions in the Bergman representation from the analytical models, numerical simulations, and experimental data of plasmonic nanocomposites. The spectral density functions, which only depend on geometry of the nanocomposite material, provide a unique measure on the contribution of individual and percolated particles inside the nanocomposite. According to the spectral density analysis of measured dielectric constants, the material properties of nanocomposites fabricated by the co-sputtering approach are dominated by electromagnetic interaction among individual metallic particles. While in the case of the nanocomposites fabricated by the multilayer thin film approach, the material properties are dominated by percolated metallic particles inside the dielectric host, as indicated by our FDTD simulation results. This understanding provides new physical insight into the interaction between light and plasmonic nanocomposites.

  7. Development of Fe-Ni/YSZ-GDC electro-catalysts for application as SOFC anodes. XRD and TPR characterization, and evaluation in ethanol steam reforming reaction

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-07-01

    Electro-catalysts based on Fe-Ni alloys were prepared using physical mixture and modified Pechini methods; they were supported on a composite of Yttria Stabilized Zirconia (YSZ) and Gadolinia Doped Ceria (GDC). The composites had compositions of 35% metal load and 65% support (70% wt. YSZ and 30% wt. GDC mixture) (cermets). The samples were characterized by Temperature-Programmed Reduction (TPR) and X-Ray Diffraction (XRD) and evaluated in ethanol steam reforming at 650 C for six hours and in the temperature range 300 - 900 C. The XRD results showed that the bimetallic sample calcined at 800 C formed a mixed oxide (NiFe{sub 2}O{sub 4}) in spinel structure; after reducing the sample in hydrogen, Ni-Fe alloys were formed. The presence of Ni decreased the final reduction temperature of the NiFe{sub 2}O{sub 4} species. The addition of Fe to Ni anchored to YSZ-GDC increased the hydrogen production and inhibits the carbon deposition. The bimetallic 30Fe5Ni samples reached an ethanol conversion of about 95%, and a hydrogen yield up to 48% at 750 C. In general, the ethanol conversion and hydrogen production were independent of the metal content in the electro-catalyst. However, the substitution of Ni for Fe significantly reduced the carbon deposition on the electro-catalyst: 74, 31 and 9 wt. % in the 35Ni, 20Fe15Ni, and 30Fe5Ni samples, respectively. (orig.)

  8. 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.

  9. 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.

  10. Extended Functionality of Environmentally-Resistant Mo-Si-B-Based Coatings

    Science.gov (United States)

    Perepezko, J. H.; Sakidja, R.

    2013-02-01

    Multiphase Mo-Si-B alloys with compositions which yield the ternary intermetallic Mo5SiB2 (T2) phase as a key microstructure constituent together with the Mo and Mo3Si phases, offer an attractive balance of high melting temperature, oxidation resistance, and mechanical properties. The investigation of reaction kinetics involving the T2 phase enables the analysis of oxidation in terms of diffusion pathways and the design of effective coatings. From this basis, kinetic biasing is used together with pack cementation to develop Mo-Si-B-based multilayered coatings with an aluminoborosilica surface and in situ diffusion barriers with self-healing characteristics for enhanced oxidation resistance. While a combustion environment contains water vapor that can accelerate an attack of silica-based coatings, the Mo-Si-B-based coatings provide oxidation resistance in water vapor up to at least 1,500°C. An exposure to hot ionized gas species generated in an arc jet confirms the robust coating performance in extreme environments. To extend the application beyond Mo-based systems, a two-stage process has been implemented to provide effective oxidation resistance for refractory metal cermets, SiC and ZrB2 ultra-high-temperature composites.

  11. 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.

  12. 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.

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. Internal reforming over nickel/zirconia anodes in SOFCS operating on methane: influence of anode formulation, pre-treatment and operating conditions

    Energy Technology Data Exchange (ETDEWEB)

    Finnerty, C.M.; Ormerod, R.M. [Birchall Centre of Inorganic Chemistry and Materials Science, Department of Chemistry, Keele Univ. (United Kingdom)

    2000-03-01

    Internal methane reforming over nickel/zirconia cermet anodes has been studied in detail using a thin-walled extruded zirconia tubular SOFC reactor. The influence of anode formulation, anode pre-treatment, operating temperature and methane/steam ratio on the reforming characteristics, resistance to carbon deposition and durability of the anode have been investigated under actual operating conditions. Post-reaction TPO has been used to determine the amount of carbon deposition and its strength of interaction with the anode. A 90-vol.% nickel/zirconia anode shows higher activity than a 50-vol.% Ni anode at higher reforming temperatures, and shows very good durability. Pre-reducing the anodes in H{sub 2} at 1173 K leads to a more active reforming catalyst. Carbon is removed from the anodes in two processes during TPO, suggesting two types of carbon species. As the reforming temperature increases both carbon types are removed at higher temperature, and there is an increase in the relative population of the more strongly bound form of carbon. (orig.)

  18. Thermally Sprayed Large Tubular Solid Oxide Fuel Cells and Its Stack: Geometry Optimization, Preparation, and Performance

    Science.gov (United States)

    Zhang, Shan-Lin; Li, Cheng-Xin; Liu, Shuai; Li, Chang-Jiu; Yang, Guan-Jun; He, Peng-Jiang; Yun, Liang-Liang; Song, Bo; Xie, Ying-Xin

    2017-02-01

    In this study, we develop a large tubular solid oxide fuel cells design with several cells in series on a porous cermet support, which has many characteristics such as self-sealing, low Ohmic loss, high strength, and good thermal expansion coefficient matching. Here, we investigate aspects of the cell design, manufacture, performance, and application. Firstly, the cell length and number of cells in series are optimized by theoretical analysis. Then, thermal spraying is applied as a cost-effective method to prepare all the cell components. Finally, the performance of different types of cells and two types of stacks is characterized. The maximum output power of one tube, which had 20 cells in series, reaches 31 and 40.5 W at 800 and 900 °C, respectively. Moreover, the output power of a stack assembled with 56 tubes, each with ten cells in series, reaches 800 W at 830 °C. The excellent single tube and cell stack performance suggest that thermally sprayed tubular SOFCs have significant potential for commercialized application.

  19. Application of surface plasmon polaritons in the laser ablation and characterisation of thin aluminium films

    Science.gov (United States)

    Cairns, G. F.; McNeill, D. A.; Dawson, P.

    1999-06-01

    Surface modification of thin aluminium films is both produced and characterised by exciting surface plasmon polaritons in an attenuated total reflection geometry: silica prism/aluminium/ aluminium oxide system. The modification is performed, under ambient conditions, by exposure to a low fluence (pulse of radiation from an excimer laser at wavelength 248 nm. Pre- and post-ablation characterisation of samples is performed at a centre wavelength of 250 nm by using a xenon lamp and optical filtration. Modelling of the characteristic reflectance-angle curves from areas exposed to the laser shows both an increased oxide thickness and the presence of an optically absorbing cermet layer, a region of mixed metal and oxide, between the aluminium and the aluminium oxide. Analysis of the results suggests that the interfacial aluminium/oxide region supporting the surface mode is ablated by means of a non-thermal, bond-breaking mechanism leading to further surface oxide formation and a progressively less complete oxidation process for a finite distance into the aluminium film. However, the ablation is frustrated in the sense that there is little or no net loss of aluminium from the system.

  20. 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.

  1. Parabolic Trough Receiver Heat Loss Testing (Poster)

    Energy Technology Data Exchange (ETDEWEB)

    Price, H.; Netter, J.; Bingham, C.; Kutscher, C.; Burkholder, F.; Brandemuehl, M.

    2007-03-01

    Parabolic trough receivers, or heat collection elements (HCEs), absorb sunlight focused by the mirrors and transfer that thermal energy to a fluid flowing within them. Thje absorbing tube of these receivers typically operates around 400 C (752 F). HCE manufacturers prevent thermal loss from the absorbing tube to the environment by using sputtered selective Cermet coatings on the absorber and by surrounding the absorber with a glass-enclosed evacuated annulus. This work quantifies the heat loss of the Solel UVAC2 and Schott PTR70 HCEs. At 400 C, the HCEs perform similarly, losing about 400 W/m of HCE length. To put this in perspective, the incident beam radiation on a 5 m mirror aperture is about 4500 W/m, with about 75% of that energy ({approx} 3400 W/m) reaching the absorber surface. Of the 3400 W/m on the absorber, about 3000 W/m is absorbed into the working fluid while 400 W/m is lost to the environment.

  2. Hydrogen production by water dissociation using ceramic membranes - annual report for FY 2010.

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y.; Picciolo, J. J. (Energy Systems)

    2011-03-14

    The objective of this project is to develop dense ceramic membranes that can produce hydrogen via coal/coal gas-assisted water dissociation without using an external power supply or circuitry. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen using OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.

  3. 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.

  4. 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.

  5. 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.

  6. Hydrogen production by water dissociation using ceramic membranes. Annual report for FY 2009.

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y.; Picciolo, J. J.; Energy Systems

    2010-04-20

    The objective of this project is to develop dense ceramic membranes that can produce hydrogen via coal/coal gas-assisted water dissociation without using an external power supply or circuitry. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen by means of OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.

  7. Hydrogen production by water dissociation using ceramic membranes - annual report for FY 2008.

    Energy Technology Data Exchange (ETDEWEB)

    Balachandran, U.; Dorris, S. E.; Emerson, J. E.; Lee, T. H.; Lu, Y.; Park, C. Y.; Picciolo, J. J.; Energy Systems

    2009-03-25

    The objective of this project is to develop dense ceramic membranes that, without using an external power supply or circuitry, can produce hydrogen via coal/coal gas-assisted water dissociation. This project grew from an effort to develop a dense ceramic membrane for separating hydrogen from gas mixtures such as those generated during coal gasification, methane partial oxidation, and water-gas shift reactions. That effort led to the development of various cermet (i.e., ceramic/metal composite) membranes that enable hydrogen production by two methods. In one method, a hydrogen transport membrane (HTM) selectively removes hydrogen from a gas mixture by transporting it through either a mixed protonic/electronic conductor or a hydrogen transport metal. In the other method, an oxygen transport membrane (OTM) generates hydrogen mixed with steam by removing oxygen that is generated through water splitting. This project focuses on the development of OTMs that efficiently produce hydrogen via the dissociation of water. Supercritical boilers offer very high-pressure steam that can be decomposed to provide pure hydrogen by means of OTMs. Oxygen resulting from the dissociation of steam can be used for coal gasification, enriched combustion, or synthesis gas production. Hydrogen and sequestration-ready CO{sub 2} can be produced from coal and steam by using the membrane being developed in this project. Although hydrogen can also be generated by high-temperature steam electrolysis, producing hydrogen by water splitting with a mixed-conducting membrane requires no electric power or electrical circuitry.

  8. Solid oxide fuel cell composite cathodes based on perovskite and fluorite structures

    Science.gov (United States)

    Sadykov, Vladislav; Mezentseva, Natalia; Usoltsev, Vladimir; Sadovskaya, Ekaterina; Ishchenko, Arkady; Pavlova, Svetlana; Bespalko, Yulia; Kharlamova, Tamara; Zevak, Ekaterina; Salanov, Aleksei; Krieger, Tamara; Belyaev, Vladimir; Bobrenok, Oleg; Uvarov, Nikolai; Okhlupin, Yury; Smorygo, Oleg; Smirnova, Alevtina; Singh, Prabhakar; Vlasov, Aleksandr; Korobeynikov, Mikhail; Bryazgin, Aleksandr; Kalinin, Peter; Arzhannikov, Andrei

    This work presents the results related to the functionally graded fluorite (F)-perovskite (P) nanocomposite cathodes for IT SOFC. Nanocrystalline fluorites (GDC, ScCeSZ) and perovskites (LSrMn, LSrFNi) were synthesized by Pechini method. Nanocomposites were prepared by the ultrasonic dispersion of F and P powders in isopropanol with addition of polyvinyl butyral. Different techniques for deposition and sintering of functionally graded cathode materials were applied including traditional approaches as well as original methods, such as radiation-thermal sintering under electron beam or microwave radiation. Morphology, microstructure and elemental composition of nanocomposites was characterized by XRD and HRTEM/SEM with EDX. Even for dense composites, the sizes of perovskite and fluorite domains remain in the nanorange providing developed P-F interfaces. Oxygen isotope heteroexchange and conductivity/weight relaxation studies demonstrated that these interfaces provide a path for fast oxygen diffusion. The redistribution of the elements between P and F phases in nanocomposites occurs without formation of insulating zirconate phases. Button-size fuel cells with nanocomposite functionally graded cathodes, thin YSZ layers and anode Ni/YSZ cermet (either bulk or supported on Ni-Al foam substrates) were manufactured. For optimized composition and functionally graded design of P-F nanocomposite cathodes, a stable performance in the intermediate temperature range with maximum power density up to 0.5 W cm -2 at 700 °C in wet H 2/air feeds was demonstrated.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. Nickel-based anode with water storage capability to mitigate carbon deposition for direct ethanol solid oxide fuel cells.

    Science.gov (United States)

    Wang, Wei; Su, Chao; Ran, Ran; Zhao, Bote; Shao, Zongping; Tade, Moses O; Liu, Shaomin

    2014-06-01

    The potential to use ethanol as a fuel places solid oxide fuel cells (SOFCs) as a sustainable technology for clean energy delivery because of the renewable features of ethanol versus hydrogen. In this work, we developed a new class of anode catalyst exemplified by Ni+BaZr0.4Ce0.4Y0.2O3 (Ni+BZCY) with a water storage capability to overcome the persistent problem of carbon deposition. Ni+BZCY performed very well in catalytic efficiency, water storage capability and coking resistance tests. A stable and high power output was well maintained with a peak power density of 750 mW cm(-2) at 750 °C. The SOFC with the new robust anode performed for seven days without any sign of performance decay, whereas SOFCs with conventional anodes failed in less than 2 h because of significant carbon deposition. Our findings indicate the potential applications of these water storage cermets as catalysts in hydrocarbon reforming and as anodes for SOFCs that operate directly on hydrocarbons.

  14. 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.

  15. 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.

  16. Influence of cell voltage and current on sulfur poisoning behavior of solid oxide fuel cells

    Science.gov (United States)

    Cheng, Zhe; Zha, Shaowu; Liu, Meilin

    The sulfur poisoning behavior of nickel-yttria stabilized zirconia (YSZ) cermet anodes in solid oxide fuel cells (SOFCs) was investigated under both potentiostatic and galvanostatic conditions. While the observed relative drop in cell power output caused by sulfur poisoning decreases as the cell-terminal voltage is lowered potentiostatically (thus more current passing through the cell), it increases as more current is drawn from the cell galvanostatically (thus leading to lower terminal voltage). The apparent contradictory trends in relative performance loss due to sulfur poisoning are explained using a simple equivalent circuit analysis, which was further validated by impedance measurements of cells before and after poisoning by trace amounts of hydrogen sulfide (H 2S) under different conditions. Results suggest that the relative increase in cell internal resistance caused by sulfur poisoning is smaller when more current is drawn from the cell (or the cell-terminal voltage is lowered) under either potentiostatic or galvanostatic conditions. Thus, the increase in anode polarization resistance, not the drop in cell power output, should be used to describe the degree of sulfur poisoning in order to avoid any confusion.

  17. 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}.

  18. 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.

  19. 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)

  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. 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’.

  2. 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.

  3. 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.

  4. 3D-WOVEN FIBER-REINFORCED COMPOSITE FOR CAD/CAM DENTAL APPLICATION.

    Science.gov (United States)

    Petersen, Richard; Liu, Perng-Ru

    2016-05-01

    Three-dimensional (3D)-woven noncrimp fiber-reinforced composite (FRC) was tested for mechanical properties in the two principal directions of the main XY plane and compared to different Computer-Aided-Design/Computer-Aided-Machining (CAD/CAM) Dental Materials. The Dental Materials included ceramic with Vitablock Mark II®, ProCAD®, InCeram® Spinel, InCeram® Alumina and InCeram® Zirconia in addition to a resin-based 3M Corp. Paradigm® particulate-filled composite. Alternate material controls included Coors 300 Alumina Ceramic and a tungsten carbide 22% cobalt cermet. The 3D-woven FRC was vacuum assisted resin transfer molding processed as a one-depth-thickness ~19-mm preform with a vinyl-ester resin and cut into blocks similar to the commercial CAD/CAM Dental Materials. Mechanical test samples prepared for a flexural three-point span length of 10.0 mm were sectioned for minimum-depth cuts to compare machinability and fracture resistance between groups. 3D-woven FRC improved mechanical properties with significant statistical differences over all CAD/CAM Dental Materials and Coors Alumina Ceramic for flexural strength (pfracture (p<0.001), strain energy release (p<0.05), critical stress intensity factor (p<0.001) and strain (p<0.001).

  5. Formation Mechanisms, Structure, and Properties of HVOF-Sprayed WC-CoCr Coatings: An Approach Toward Process Maps

    Science.gov (United States)

    Varis, T.; Suhonen, T.; Ghabchi, A.; Valarezo, A.; Sampath, S.; Liu, X.; Hannula, S.-P.

    2014-08-01

    Our study focuses on understanding the damage tolerance and performance reliability of WC-CoCr coatings. In this paper, the formation of HVOF-sprayed tungsten carbide-based cermet coatings is studied through an integrated strategy: First-order process maps are created by using online-diagnostics to assess particle states in relation to process conditions. Coating properties such as hardness, wear resistance, elastic modulus, residual stress, and fracture toughness are discussed with a goal to establish a linkage between properties and particle characteristics via second-order process maps. A strong influence of particle state on the mechanical properties, wear resistance, and residual stress stage of the coating was observed. Within the used processing window (particle temperature ranged from 1687 to 1831 °C and particle velocity from 577 to 621 m/s), the coating hardness varied from 1021 to 1507 HV and modulus from 257 to 322 GPa. The variation in coating mechanical state is suggested to relate to the microstructural changes arising from carbide dissolution, which affects the properties of the matrix and, on the other hand, cohesive properties of the lamella. The complete tracking of the coating particle state and its linking to mechanical properties and residual stresses enables coating design with desired properties.

  6. HVOF and HVAF Coatings of Agglomerated Tungsten Carbide-Cobalt Powders for Water Droplet Erosion Application

    Science.gov (United States)

    Tarasi, F.; Mahdipoor, M. S.; Dolatabadi, A.; Medraj, M.; Moreau, C.

    2016-12-01

    Water droplet erosion (WDE) is a phenomenon caused by impingement of water droplets of several hundred microns to a few millimeters diameter at velocities of hundreds of meters per second on the edges and surfaces of the parts used in such services. The solution to this problem is sought especially for the moving compressor blades in gas turbines and those operating at the low-pressure end of steam turbines. Thermal-sprayed tungsten carbide-based coatings have been the focus of many studies and are industrially accepted for a multitude of wear and erosion resistance applications. In the present work, the microstructure, phase analysis and mechanical properties (micro-hardness and fracture toughness) of WC-Co coatings are studied in relation with their influence on the WDE resistance of such coatings. The coatings are deposited by high-velocity oxygen fuel (HVOF) and high-velocity air fuel (HVAF) processes. The agglomerated tungsten carbide-cobalt powders were in either sintered or non-sintered conditions. The WDE tests were performed using 0.4 mm water droplets at 300 m/s impact velocity. The study shows promising results for this cermet as WDE-resistant coating when the coating can reach its optimum quality using the right thermal spray process and parameters.

  7. 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)

  8. Thermally Sprayed Large Tubular Solid Oxide Fuel Cells and Its Stack: Geometry Optimization, Preparation, and Performance

    Science.gov (United States)

    Zhang, Shan-Lin; Li, Cheng-Xin; Liu, Shuai; Li, Chang-Jiu; Yang, Guan-Jun; He, Peng-Jiang; Yun, Liang-Liang; Song, Bo; Xie, Ying-Xin

    2017-01-01

    In this study, we develop a large tubular solid oxide fuel cells design with several cells in series on a porous cermet support, which has many characteristics such as self-sealing, low Ohmic loss, high strength, and good thermal expansion coefficient matching. Here, we investigate aspects of the cell design, manufacture, performance, and application. Firstly, the cell length and number of cells in series are optimized by theoretical analysis. Then, thermal spraying is applied as a cost-effective method to prepare all the cell components. Finally, the performance of different types of cells and two types of stacks is characterized. The maximum output power of one tube, which had 20 cells in series, reaches 31 and 40.5 W at 800 and 900 °C, respectively. Moreover, the output power of a stack assembled with 56 tubes, each with ten cells in series, reaches 800 W at 830 °C. The excellent single tube and cell stack performance suggest that thermally sprayed tubular SOFCs have significant potential for commercialized application.

  9. Ionic conductivity and fuel cell properties of apatite-type lanthanum silicates doped with Mg and containing excess oxide ions

    Energy Technology Data Exchange (ETDEWEB)

    Yoshioka, Hideki [Hyogo Prefectural Institute of Technology, 3-1-12 Yukihira-cho, Suma-ku, Kobe 654-0037 (Japan); Nojiri, Yoshihiro [Kyushu University, Department of Mechanical Engineering Science, Faculty of Engineering, Motooka 744, Nishi-ku, Fukuoka 819-0935 (Japan); Tanase, Shigeo [National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)

    2008-11-30

    Enhancement of the ionic conductivity of lanthanum silicate-based apatites is examined with emphasis on optimizing the La composition and the Mg doping level at the same time. La{sub 10}Si{sub 5.8}Mg{sub 0.2}O{sub 26.8} and La{sub 9.8}Si{sub 5.7}Mg{sub 0.3}O{sub 26.4} show the highest level of the ionic conductivities among apatite silicates, 8.8 and 7.4 x 10{sup -} {sup 2} S cm{sup -} {sup 1} at 800 C, respectively, with a very low level of activation energy (0.42-0.43 eV). Their conductivities are higher than yttria stabilized zirconia (YSZ) below 900 C and even comparable to Sr and Mg doped lanthanum gallate (LSGM) below 550 C. A solid oxide fuel cell using La{sub 9.8}Si{sub 5.7}Mg{sub 0.3}O{sub 26.4} as an electrolyte with Ni-ceria cermet anode and Sr doped lanthanum cobaltite cathode exhibits a remarkable improvement in power generation compared to previous data using Pt electrodes. Structural investigation by the Rietveld analysis on the powder X-ray diffraction pattern shows significant enlargement of the bottleneck triangle sizes of the conduction channel with the Mg doping. (author)

  10. NEMO: A mission to search for and return to Earth possible life forms on Europa

    Science.gov (United States)

    Powell, Jesse; Powell, James; Maise, George; Paniagua, John

    2005-07-01

    The Nuclear Europa Mobile Ocean (NEMO) mission would land on the surface of Europa, and deploy a small, lightweight melt probe powered by a compact nuclear reactor to melt down through the multi-kilometer ice sheet. After reaching the sub-surface ocean, a small nuclear Autonomous Underwater Vehicle (AUV) would deploy to explore the sub-ice ocean. After exploration and sample collection, the AUV would return to the probe and melt back to the lander. The lander would have replenished its H2 propellant by electrolysis of H2O ice, and then hop to a new site on Europa to repeat the probe/AUV process. After completing the mission, the NEMO spacecraft would return to Earth with its collected samples. The NEMO melt probe and AUV utilize enriched U-235 fuel and conventional water reactor technology. The lander utilizes a compact nuclear thermal propulsion (NTP) engine based on the 710tungsten/UO2 cermet fuel and high-temperature H2 propellant. The compact nuclear reactors in both the NEMO melt probe and AUV drive a steam power cycle, generating over 10 kW(e) for use in each. Each nuclear reactor's operating lifetime is several years. With its high-mobility and long-duration mission, NEMO provides an ideal platform for life detection experiments.

  11. Xanadu: A Polar Base for Manufacturing Supplies on Mars

    Science.gov (United States)

    Powell, J.; Maise, G.; Paniagua, J.

    2004-02-01

    Human exploration of Mars requires much greater supplies of propellants, fuels, breathable air, construction materials, and food, than can come from Earth. However, these materials can be robotically manufactured from CO2 and N2 in the Mars atmosphere and water ice from the North Polar Cap. A small nuclear powered robotic factory landed on the Polar Cap can manufacture and stockpile hundreds of tons of supplies under the ice for astronauts coming from Earth. Sub-surface insulated ice caves can also provide insulated habitats to shield from cosmic radiation. Design and operation of the robotic factory is described including the nuclear reactor and chemical process units. The water-cooled reactor uses commercial ZrO2 cermet nuclear fuel. Commercial chemical process technology would include water electrolysis, liquefaction of H2, O2, and air (N2/O2), methane and methanol production, and polyethylene synthesis from CO2 and N2, and algae and yeast foodstuffs from methanol feedstock. Development and mission scenarios for the Xanadu concept are described, with implementation possible within the next decade.

  12. 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

  13. Methodology for Producing a Uniform Distribution of UO2 in a Tungsten Matrix

    Science.gov (United States)

    Tucker, Dennis S.; O'Conner, Andrew; Hickman, Rickman; Broadway, Jeramie; Belancik, Grace

    2015-01-01

    Current work at NASA's Marshall Space Flight Center (MSFC) is focused on the development CERMET fuel materials for Nuclear Thermal Propulsion (NTP). The CERMETs consist of uranium dioxide (UO2) fuel particles embedded in a tungsten (W) metal matrix. Initial testing of W-UO2 samples fabricated from fine angular powders performed reasonably well, but suffered from significant fuel loss during repeated thermal cycling due to agglomeration of the UO2 (1). The blended powder mixtures resulted in a non-uniform dispersion of the UO2 particles in the tungsten matrix, which allows rapid vaporization of the interconnected UO2 from the sample edges into the bulk material. Also, the angular powders create areas of stress concentrations due to thermal expansion mismatch, which eventually cracks the tungsten matrix. Evenly coating spherical UO2 particles with chemical vapor deposited (CVD) tungsten prior to consolidation was previously demonstrated to provide improved performance. However, the CVD processing technology is expensive and not currently available. In order to reduce cost and enhance performance, a powder coating process has been developed at MSFC to produce a uniform distribution of the spherical UO2 particles in a tungsten matrix. The method involves utilization of a polyethylene binder during mixing which leads to fine tungsten powders clinging to the larger UO2 spherical particles. This process was developed using HfO2 as a surrogate for UO2. Enough powder was mixed to make 8 discs (2cm diameter x 8mm thickness) using spark plasma sintering. A uniaxial pressure of 50 MPa was used at four different temperatures (2 samples at each temperature). The first two samples were heated to 1400C and 1500C respectively for 5 minutes. Densities for these samples were less than 85% of theoretical, so the time at temperature was increased to 20 minutes for the remaining samples. The highest densities were achieved for the two samples sintered at 1700C (approx. 92% of

  14. 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

  15. High temperature materials; Materiaux a hautes temperatures

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    The aim of this workshop is to share the needs of high temperature and nuclear fuel materials for future nuclear systems, to take stock of the status of researches in this domain and to propose some cooperation works between the different research organisations. The future nuclear systems are the very high temperature (850 to 1200 deg. C) gas cooled reactors (GCR) and the molten salt reactors (MSR). These systems include not only the reactor but also the fabrication and reprocessing of the spent fuel. This document brings together the transparencies of 13 communications among the 25 given at the workshop: 1) characteristics and needs of future systems: specifications, materials and fuel needs for fast spectrum GCR and very high temperature GCR; 2) high temperature materials out of neutron flux: thermal barriers: materials, resistance, lifetimes; nickel-base metal alloys: status of knowledge, mechanical behaviour, possible applications; corrosion linked with the gas coolant: knowledge and problems to be solved; super-alloys for turbines: alloys for blades and discs; corrosion linked with MSR: knowledge and problems to be solved; 3) materials for reactor core structure: nuclear graphite and carbon; fuel assembly structure materials of the GCR with fast neutron spectrum: status of knowledge and ceramics and cermets needs; silicon carbide as fuel confinement material, study of irradiation induced defects; migration of fission products, I and Cs in SiC; 4) materials for hydrogen production: status of the knowledge and needs for the thermochemical cycle; 5) technologies: GCR components and the associated material needs: compact exchangers, pumps, turbines; MSR components: valves, exchangers, pumps. (J.S.)

  16. 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.

  17. Development of Fe-Ni/YSZ-GDC electrocatalysts for application as SOFC anodes: XRD and TPR characterization and evaluation in the ethanol steam reforming reaction

    Energy Technology Data Exchange (ETDEWEB)

    da Paz Fiuza, Raigenis; Aurelio da Silva, Marcos; Boaventura, Jaime Soares [Energy and Materials Science Group - GECIM, Institute of Chemistry, Physical Chemistry Department, Universidade Federal da Bahia, 41170290 Salvador, Bahia (Brazil)

    2010-10-15

    Electrocatalysts based on Fe-Ni alloys were prepared by means of modified Pechini and physical mixture methods and using on a composite of Yttria Stabilized Zirconia (YSZ) and Gadolinia-Doped Ceria (GDC) as support. The former method was based on the formation a polymeric precursor that was subsequently calcined; the later method was based on the mixture of NiO and the support. The resulting composites had 35 wt.% metal load and 65 wt.% support (70 wt.% YSZ and 30 wt.% GDC mixture) (cermets). The samples were then characterized by Temperature-Programmed Reduction (TPR) and X-Ray Diffraction (XRD) and evaluated in the ethanol steam reforming at 650 C for 6 h in the temperature range of 300-900 C. The XRD results showed that the bimetallic sample calcined at 800 C formed a mixed oxide (NiFe{sub 2}O{sub 4}) with a spinel structure, which, after reduction in hydrogen, formed Ni-Fe alloys. The presence of Ni was observed to decrease the final reduction temperature of the NiFe{sub 2}O{sub 4} species. The addition of iron to the nickel anchored to YSZ-GDC increased the hydrogen production and inhibited carbon deposition. The resulting bimetallic 30Fe5Ni sample reached an ethanol conversion of about 95% and a hydrogen yield up to 48% at 750 C. In general, ethanol conversion and hydrogen production were independent of the metal content in the electrocatalyst. However, the substitution of nickel for iron significantly reduced carbon deposition on the electrocatalyst: 74, 31, and 9 wt.% in the 35Ni, 20Fe15Ni, and 30Fe5Ni samples, respectively. (author)

  18. 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.

  19. Electro-spark deposition technology

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, R.N. [Pacific Northwest Lab., WA (United States)

    1996-08-01

    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 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 as one of the enabling technologies for advanced energy systems. 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. One of the most significant breakthroughs to occur in the last dozen years is the discovery of a process regime that promises an order of magnitude increase in deposition rates and achievable coating thicknesses. Since this regime borders on and exceeds the normal operating limits of existing ESD electronic equipment, development is in progress to produce equipment that can consistently and reliably achieve these conditions for a broad range of materials. Progress so far has resulted in a consistent 500% increase in deposition rates, and greater rates still are anticipated. 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, the incorporation of the process into the operations of a major gas turbine manufacturer, major new applications in gas turbine blade and steam turbine blade protection and repair, and in military, medical, metal-working, and recreational equipment applications.

  20. Design analysis and risk assessment for a single stage to orbit nuclear thermal rocket

    Science.gov (United States)

    Labib, Satira I.

    Recent advances in high power density fuel materials have renewed interest in nuclear thermal rockets (NTRs) as a viable propulsion technology for future space exploration. This thesis describes the design of three NTR reactor engines designed for the single stage to orbit launch of payloads from 1-15 metric tons. Thermal hydraulic and rocket engine analyses indicate that the proposed rocket engines are able to reach specific impulses in excess of 700 seconds. 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. At the same power level, the 40 cm reactor results in the lowest radiation dose rate of the three reactors. Radiation dose rates decrease to background levels ~3.5 km from the launch site. After a one-year decay time, all of the activated materials produced by an NTR launch would be classified as Class A low-level waste. The activation of air produces significant amounts of argon-41 and nitrogen-16 within 100 m of the launch. The derived air concentration, DAC, from the activation products decays to less than unity within two days, with only argon-41 remaining. After 10 minutes of full power operation the 120 cm core corresponding to a 15 MT payload contains 2.5 x 1013, 1.4 x 1012, 1.5 x 1012, and 7.8 x 10 7 Bq of 131I, 137Cs, 90Sr, and 239Pu respectively. The decay heat after shutdown increases with increasing reactor power with a maximum decay heat of 108 kW immediately after shutdown for the 15 MT payload.

  1. ``Bimodal'' Nuclear Thermal Rocket (BNTR) Propulsion for an Artificial Gravity HOPE Mission to Callisto

    Science.gov (United States)

    Borowski, Stanley K.; McGuire, Melissa L.; Mason, Lee M.; Gilland, James H.; Packard, Thomas W.

    2003-01-01

    This paper summarizes the results of a year long, multi-center NASA study which examined the viability of nuclear fission propulsion systems for Human Outer Planet Exploration (HOPE). The HOPE mission assumes a crew of six is sent to Callisto. Jupiter's outermost large moon, to establish a surface base and propellant production facility. The Asgard asteroid formation, a region potentially rich in water-ice, is selected as the landing site. High thrust BNTR propulsion is used to transport the crew from the Earth-Moon L1 staging node to Callisto then back to Earth in less than 5 years. Cargo and LH2 ``return'' propellant for the piloted Callisto transfer vehicle (PCTV) is pre-deployed at the moon (before the crew's departure) using low thrust, high power, nuclear electric propulsion (NEP) cargo and tanker vehicles powered by hydrogen magnetoplasmadynamic (MPD) thrusters. The PCTV is powered by three 25 klbf BNTR engines which also produce 50 kWe of power for crew life support and spacecraft operational needs. To counter the debilitating effects of long duration space flight (~855 days out and ~836 days back) under ``0-gE'' conditions, the PCTV generates an artificial gravity environment of ``1-gE'' via rotation of the vehicle about its center-of-mass at a rate of ~4 rpm. After ~123 days at Callisto, the ``refueled'' PCTV leaves orbit for the trip home. Direct capsule re-entry of the crew at mission end is assumed. Dynamic Brayton power conversion and high temperature uranium dioxide (UO2) in tungsten metal ``cermet'' fuel is used in both the BNTR and NEP vehicles to maximize hardware commonality. Technology performance levels and vehicle characteristics are presented, and requirements for PCTV reusability are also discussed.

  2. 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. 

  3. 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.

  4. Anode supported single chamber solid oxide fuel cells operating in exhaust gases of thermal engine

    Science.gov (United States)

    Briault, Pauline; Rieu, Mathilde; Laucournet, Richard; Morel, Bertrand; Viricelle, Jean-Paul

    2014-12-01

    This project deals with the development and the electrochemical characterization of anode supported single chamber SOFC in a simulated environment of thermal engine exhaust gas. In the present work, a gas mixture representative of exhaust conditions is selected. It is composed of hydrocarbons (HC: propane and propene), oxygen, carbon monoxide, carbon dioxide, hydrogen and water. Only oxygen content is varied leading to different gas mixtures characterized by three ratios R = HC/O2. Concerning the cell components, a cermet made of nickel and an electrolyte material, Ce0.9Gd0.1O1.95 (CGO) is used as anode and two cathode materials, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) and Pr2NiO4+δ (PNO), are evaluated. The prepared cells are investigated in the various gas mixtures for temperatures ranging from 450 °C to 600 °C. Ni-CGO/CGO/LSCF-CGO cell has delivered a maximum power density of 15 mW cm-2 at 500 °C with R = HC/O2 = 0.21, while lower power densities are obtained for the other ratios, R = 0.44 and R = 0.67. Afterwards, LSCF and PNO cathode materials are compared and LSCF is found to deliver the highest power densities. Finally, by improving the electrolyte microstructure, some cells presenting a maximum power density of 25 mW cm-2 at 550 °C are produced. Moreover, up to 17% of initial HC are eliminated in the gas mixture.

  5. Feasibility of a Stack Integrated SOFC Optical Chemical Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Michael A. Carpenter

    2007-09-30

    The DOE-NETL Innovative Concepts (IC) phase II program investigated the feasibility of harsh environment compatible chemical sensors based on monitoring the surface plasmon resonance (SPR) bands of metal nanoparticle doped YSZ nano-cermets, as a function of fuel concentrations, impurities e.g. CO and temperature(500-900 C). In particular, Au nanoparticles (AuNPs) exhibit a strong surface plasmon resonance (SPR) band whose shape and spectral position is not only highly dependent on the refractive index of the host medium but also on chemical reactions at the interface between the metal and the surrounding environment. Studies have been completed on the oxygen and temperature dependence of the SPR band of the AuNPs, CO sensing studies, oxygen/hydrogen titration experiments, ethanol sensing studies and finally NO{sub 2} sensing studies. Reversible changes in the SPR band are observed for all chemical exposure studies with the sensing mechanism being determined by the oxidative or reductive properties of the exposure gases. Reactions which remove charge from the AuNPs was observed to cause a redshift in the SPR band, while charge donation to the AuNPs causes a blue shift in the SPR band. CO, hydrogen and ethanol in air mixtures were all reductive in nature as they reacted with the YSZ bound oxygen anions forming CO{sub 2} or H{sub 2}O thus ultimately inducing charge donation to the AuNPs and a blue shift in the SPR band. While NO{sub 2} and oxygen were oxidative and induced the production of YSZ bound oxygen anions, charge removal from the AuNPs and a redshift in the SPR band.

  6. 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.

  7. 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.

  8. 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.

  9. An Experimental Study of the Corrosion Behavior of Nickel Tungsten Carbide in Some Water-Glycol Hydraulic Fluids for Subsea Applications

    Science.gov (United States)

    Zheng, Lei; Neville, Anne; Gledhill, Andrew; Johnston, David

    2010-02-01

    Corrosion failures of components in electro-hydraulic control systems can have serious consequences for the operation of an entire subsea oil recovery system, especially in water depths more than 150 m (Fleming, Meas. Control, 2000, 33(7), p 207-213). An acceptable reason for this is that seawater ingress can have a great effect on stainless steel 316L, the most commonly used material for the failed components of the direction control valves, since chloride irons destabilize the passive film [Malik et al., Corros. Sci., 1992, 33(11), p 1809-1827; Desalination, 1994, 97(1-3), p 189-197; Al-Malahy and Hodgkiess, Desalination, 2003, 158(1-3), p 35-42]. Other materials, claimed to be seawater tolerant, are starting to be used in this system. However, problems can still exist due to the complex factors relating to the corrosion process and how the environmental parameters affect the corrosion mechanisms. In this work, the corrosion behavior of a nickel tungsten carbide cermet, one of the proposed materials, is compared with stainless steel 316L, in four different water-glycol hydraulic fluids and 50% hydraulic fluid/50% seawater solutions using an electrochemical test methodology. Systematic fluid analysis, which includes GC-MS for organic components and ICP-MS analysis for ionic content, and surface analysis of the material are carried out to assess the corrosion mechanisms. Detailed conclusions are then made to summarize the advantages and disadvantages of nickel tungsten carbide being used in this system. The effects of each factor on the corrosion rates and mechanisms are discussed.

  10. Semitransparent Metallic Photonic Crystals: Variety of Plasmons in Inverted Opal Nano-Meshes

    Science.gov (United States)

    Zakhidov, Anvar; Baughman, Ray; Khayrullin, Ilyas; Wiley, John; Eradat, Nayer; Efros, Alex; Vardeny, Valy

    2001-03-01

    We have recently fabricated three-dimensional nano-structures by self-assembling sub-micron particles into 3-D porous superlattices, and templating them with practically any material, both electrically conductive and insulating, including carbon [1], thermoelectric semiconductors [2], polymers [3], and magnets [4]. Being photonic crystals (PCs), our superlattices possess new, unconventional properties, such as the tunable intra-gap lasing [5], anomalous coherent backscattering [6], and structural solvatochromism. Here we describe synthesis and physical properties of another class of photonic crystals, called plasmon or metallic PC. Their metallo-dielectric structure has a metallic (or plasmon) photonic band gap (PBG) in IR spectral range, and therefore shows unusual optical properties. Of particular interest is the increased transparency and reflectivity spectrum, different from that of usual bulk metal. We demonstrate that by changing the topology from a network (continuos mesh) to a cermet (discontinuous web) one can achieve tunability of reflectivity peak in IR via modulation of plasmon spectrum and the metallicity PBG [7]. The theoretical model, which takes into account 1-D plasmon, surface plasmon and effectively changed 3-D plasmon (due to low filling factor), explains the observed peaks in reflectivity, and increase of the transparency. Such semitransparent metallic nano-meshes can be used for example as electrodes for LEDs and lasers. 1. A.A. Zakhidov, et al, Science, 282 (1998) 897. 2. R.H. Baughman, et al . Proc. ICT'98 (1998) 288. 3. A.A. Zakhidov, et al., Nanostructured Materials, 12 (1999) 1089. 4. T.-B,Xu, et al, J. Appl. Phys, 88 (2000) 405. 5. L.Xu, et al, Chem. Comm., (2000) 997. 6. M.N. Shkunov, et al. Synth.Met (in press), 7. AA. Zakhidov, et al., Synthetic Metals (in press).

  11. High energy electron beam joining of ceramic components

    Energy Technology Data Exchange (ETDEWEB)

    Turman, B.N.; Glass, S.J.; Halbleib, J.A. [and others

    1997-07-01

    High strength, hermetic braze joints between ceramic components have been produced using high energy electron beams. With a penetration depth into a typical ceramic of {approximately}1 cm for a 10 MeV electron beam, this method provides the capability for rapid, transient brazing operations where temperature control of critical components is essential. The method deposits energy directly into a buried joint, allowing otherwise inaccessible interfaces to be brazed. Because of transient heating, higher thermal conductivity, lower heat capacity, and lower melting temperature of braze metals relative to the ceramic materials, a pulsed high power beam can melt a braze metal without producing excessive ceramic temperatures. We have demonstrated the feasibility of this process related to ceramic coupons as well as ceramic and glass tubes. The transient thermal response was predicted, using as input the energy absorption predicted from the coupled electron-photon transport analysis. The joining experiments were conducted with an RF Linac accelerator at 10-13 MV. The repetition rate of the pulsed beam was varied between 8 and 120 Hz, the average beam current was varied between 8 and 120 microamps, and the power was varied up to 1.5 kW. These beam parameters gave a beam power density between 0.2 to 2 kW/cm{sup 2}. The duration of the joining runs varied from 5 to 600 sec. Joining experiments have provided high strength between alumina - alumina and alumina - cermet joints in cylindrical geometry. These joints provided good hermetic seals. A series of tests was conducted to determine the minimum beam power and exposure time for producing, a hermetic seal.

  12. The erosion performance of particle reinforced metal matrix composite coatings produced by co-deposition cold gas dynamic spraying

    Science.gov (United States)

    Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

    2017-02-01

    This work reports on the erosion performance of three particle reinforced metal matrix composite coatings, co-deposited with an aluminium binder via cold-gas dynamic spraying. The deposition of ceramic particles is difficult to achieve with typical cold spray techniques due to the absence of particle deformation. This issue has been overcome in the present study by simultaneously spraying the reinforcing particles with a ductile metallic binder which has led to an increased level of ceramic/cermet particles deposited on the substrate with thick (>400 μm) coatings produced. The aim of this investigation was to evaluate the erosion performance of the co-deposited coatings within a slurry environment. The study also incorporated standard metallographic characterisation techniques to evaluate the distribution of reinforcing particles within the aluminium matrix. All coatings exhibited poorer erosion performance than the uncoated material, both in terms of volume loss and mass loss. The Al2O3 reinforced coating sustained the greatest amount of damage following exposure to the slurry and recorded the greatest volume loss (approx. 2.8 mm3) out of all of the examined coatings. Despite the poor erosion performance, the WC-CoCr reinforced coating demonstrated a considerable hardness increase over the as-received AA5083 (approx. 400%) and also exhibited the smallest free space length between adjacent particles. The findings of this study reveal that the removal of the AA5083 matrix by the impinging silicon carbide particles acts as the primary wear mechanism leading to the degradation of the coating. Analysis of the wear scar has demonstrated that the damage to the soft matrix alloy takes the form of ploughing and scoring which subsequently exposes carbide/oxide particles to the impinging slurry.

  13. Activation of H(2) oxidation at sulphur-exposed Ni surfaces under low temperature SOFC conditions.

    Science.gov (United States)

    Deleebeeck, Lisa; Shishkin, Maxim; Addo, Paul; Paulson, Scott; Molero, Hebert; Ziegler, Tom; Birss, Viola

    2014-05-28

    Ni-YSZ (yttria-stabilized zirconia) cermets are known to be very good anodes in solid oxide fuel cells (SOFCs), which are typically operated at 700-1000 °C. However, they are expected to be increasingly degraded as the operating temperature is lowered in the presence of H2S (5-10 ppm) in the H2 fuel stream. However, at 500 to 600 °C, a temperature range rarely examined for sulphur poisoning, but of great interest for next generation SOFCs, we report that H2S-exposed Ni-YSZ anodes are catalytic towards the H2 oxidation reaction, rather than poisoned. By analogy with bulk Ni3S2/YSZ anodes, shown previously to enhance H2 oxidation kinetics, it is proposed that a thin layer of Ni sulphide, akin to Ni3S2, is forming, at least at the triple point boundary (TPB) region under our conditions. To explain why Ni3S2/YSZ is so active, it is shown from density functional theory (DFT) calculations that the O(2-) anions at the Ni3S2/YSZ TPB are more reactive towards hydrogen oxidation than is O(2-) at the Ni/YSZ TPB. This is accounted for primarily by structural transformations of Ni3S2 during H2 oxidation, rather than by the electronic properties of this interface. To understand why a thin layer of Ni3S2 could form when a single monolayer of sulphur on the Ni surface is the predicted surface phase under our conditions, it is possible that the reaction of H2 with O(2-), forming water, prevents sulphur from re-equilibrating to H2S. This may then promote Ni sulphide formation, at least in the TPB region.

  14. 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.

  15. LaCrO{sub 3}-dispersed Cr for metallic interconnect of planar SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Song, Rak-Hyun; Shin, Dong Ryul [Korea Institute of Energy Research, Taejon (Korea, Republic of); Dokiya, Masayuki [National Institute of Materials and Chemical Research, Ibaraki (Japan)

    1996-12-31

    In the planar SOFC, the interconnect materials plays two roles as an electrical connection and as a gas separation plate in a cell stack. The interconnect materials must be chemically stable in reducing and oxidizing environments, and have high electronic conductivity, high thermal conductivity, matching thermal expansion with an electrolyte, high mechanical strength, good fabricability, and gas tightness. Lanthanum chromite so far has been mainly used as interconnect materials in planar SOFC. However, the ceramic materials are very weak in mechanical strength and have poor machining property as compared with metal. Also the metallic materials have high electronic conductivity and high thermal conductivity. Recently some researchers have studied metallic interconnects such as Al{sub 2}O{sub 3}/Inconel 600 cermet, Ni-20Cr coated with (LaSr)CoO{sub 3}, and Y{sub 2}O{sub 3-} or La{sub 2}O{sub 3}-dispersed Cr alloy. These alloys have still some problems because Ni-based alloys have high thermal expansion, the added Al{sub 2}O{sub 3}, Y{sub 2}O{sub 3} and La{sub 2}O{sub 3} to metals have no electronic conductivity, and the oxide formed on the surface of Cr alloy has high volatility. To solve these problems, in this study, LaCrO{sub 3}-dispersed Cr for metallic interconnect of planar SOFC was investigated. The LaCrO{sub 3}-dispersed Cr can be one candidate of metallic interconnect because LaCrO{sub 3} possesses electronic conductivity and Cr metal has relatively low thermal expansion. The content of 25 vol.% LaCrO{sub 3} Was selected on the basis of a theoretically calculated thermal expansion. The thermal expansion, electrical and oxidation properties were examined and the results were discussed as related to SOFC requirements.

  16. Control of morphology and structure for β-Co nanoparticles from cobalt oxalate and research on its phase-change mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Ying [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Chongqing University of Arts and Science, Chongqing 402160 (China); Xiong, Xiang, E-mail: xiangxiong88@qq.com [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Zou, J.P., E-mail: zoujp@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Deng, Ling [Chengdu Chengliang Tool Group Co., Ltd., Chengdu 610056 (China); Tu, M.J. [Chongqing University of Arts and Science, Chongqing 402160 (China)

    2015-01-05

    Highlights: • Nanoscale precursor β-CoC{sub 2}O{sub 4}⋅2H{sub 2}O can be prepared by mechanical solid phase reaction. • Growth mechanism, morphology and crystal structure of β-CoC{sub 2}O{sub 4}⋅2H{sub 2}O have been studied. • Internal energy reserves of precursor making it directly generate β-Co in the thermal decomposition reaction. • Martensitic transformation of Co has been studied. • The Co powder will inherit the morphology of its precursor. - Abstract: The face-centered cubic crystal structure β-Co has excellent performance. As the main material to produce high toughness hard alloys and metal cermet, its morphology and structure will have an important impact on the performance of the alloy. This study, based on solid-phase reaction, starting from the crystal structure studied, discussed the effection of the mechanical solid-phase chemical reactions on the morphology of the cobalt precursor structure, researched the cobalt phase change mechanism, and presented a method to prepare nano β-Co. With H{sub 2}C{sub 2}O{sub 4}⋅2H{sub 2}O and Co(NO{sub 3}){sub 2}·6H{sub 2}O as raw materials, nano-crystalline cobalt oxalate powders with nearly spherical shape have been prepared by using solid-phase chemical reactions in high-speed ball milling, and then by decomposing at 400–450 °C, the target was prepared. The thermodynamical and IR analysis has been studied. The microstructure of the powders was characterized by XRD, SEM, TEM. It has been identified that a spherical, fcc structure, 100 nm β-Co powders was synthesized successfully, which confirmed the theoretical feasibility of this study.

  17. Structurally Integrated, Damage Tolerant Thermal Spray Coatings: Processing Effects on Surface and System Functionalities

    Science.gov (United States)

    Vackel, Andrew

    Thermal Spray (TS) coatings have seen extensive application as protective surfaces to enhance the service life of substrates prone to damage in their operating environment (wear, corrosion, heat etc.). With the advent of high velocity TS processes, the ability to deposit highly dense (>99%) metallic and cermet coatings has further enhanced the protective ability of these coatings. In addition to surface functionality, the influence of the coating application on the mechanical performance of a coated component is of great concern when such a component will experience either static or cyclic loading during service. Using a process mapping methodology, the processing-property interplay between coating materials meant to provide damage tolerant surface or for structural restoration are explored in terms of relevant mechanical properties. Most importantly, the residual stresses inherent in TS deposited coatings are shown to play a significant role in the integrated mechanical performance of these coatings. Unique to high velocity TS processes is the ability to produce compressive stresses within the deposit from the cold working induced by the high kinetic energy particles upon impact. The extent of these formation stresses are explored with different coating materials, as well as processing influence. The ability of dense TS coatings to carry significant structural load and synergistically strengthen coated tensile specimens is demonstrated as a function of coating material, processing, and thickness. The sharing of load between the substrate and otherwise brittle coating enables higher loads before yield for the bi-material specimens, offering a methodology to improve the tensile performance of coated components for structural repair or multi-functionality (surface and structure). The concern of cyclic fatigue damage in coated components is explored, since the majority of service application are designed for loading to be well below the yield point. The role of

  18. 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)

  19. NASA Glenn Research Center's Materials International Space Station Experiments (MISSE 1-7)

    Science.gov (United States)

    deGroh, Kim K.; Banks, Bruce a.; Dever, Joyce A.; Jaworske, Donald A.; Miller, Sharon K.; Sechkar, Edward A.; Panko, Scott R.

    2008-01-01

    NASA Glenn Research Center (Glenn) has 39 individual materials flight experiments (>540 samples) flown as part of the Materials International Space Station Experiment (MISSE) to address long duration environmental durability of spacecraft materials in low Earth orbit (LEO). MISSE is a series of materials flight experiments consisting of trays, called Passive Experiment Carriers (PECs) that are exposed to the space environment on the exterior of the International Space Station (ISS). MISSE 1-5 have been successfully flown and retrieved and were exposed to the space environment from one to four years. MISSE 6A & 6B were deployed during the STS-123 shuttle mission in March 2008, and MISSE 7A & 7B are being prepared for launch in 2009. The Glenn MISSE experiments address atomic oxygen (AO) effects such as erosion and undercutting of polymers, AO scattering, stress effects on AO erosion, and in-situ AO fluence monitoring. Experiments also address solar radiation effects such as radiation induced polymer shrinkage, stress effects on radiation degradation of polymers, and radiation degradation of indium tin oxide (ITO) coatings and spacesuit fabrics. Additional experiments address combined AO and solar radiation effects on thermal control films, paints and cermet coatings. Experiments with Orion Crew Exploration Vehicle (CEV) seals and UltraFlex solar array materials are also being flown. Several experiments were designed to provide ground-facility to in-space calibration data thus enabling more accurate in-space performance predictions based on ground-laboratory testing. This paper provides an overview of Glenn s MISSE 1-7 flight experiments along with a summary of results from Glenn s MISSE 1 & 2 experiments.

  20. Concentrated Solar Thermoelectric Power

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Gang [MIT; Ren, Zhifeng [University of Houston

    2015-07-09

    The goal of this project is to demonstrate in the lab that solar thermoelectric generators (STEGs) can exceed 10% solar-to-electricity efficiency, and STEGs can be integrated with phase-change materials (PCM) for thermal storage, providing operation beyond daylight hours. This project achieved significant progress in many tasks necessary to achieving the overall project goals. An accurate Themoelectric Generator (TEG) model was developed, which included realistic treatment of contact materials, contact resistances and radiative losses. In terms of fabricating physical TEGs, high performance contact materials for skutterudite TE segments were developed, along with brazing and soldering methods to assemble segmented TEGs. Accurate measurement systems for determining device performance (in addition to just TE material performance) were built for this project and used to characterize our TEGs. From the optical components’ side, a spectrally selective cermet surface was developed with high solar absorptance and low thermal emittance, with thermal stability at high temperature. A measurement technique was also developed to determine absorptance and total hemispherical emittance at high temperature, and was used to characterize the fabricated spectrally selective surfaces. In addition, a novel reflective cavity was designed to reduce radiative absorber losses and achieve high receiver efficiency at low concentration ratios. A prototype cavity demonstrated that large reductions in radiative losses were possible through this technique. For the overall concentrating STEG system, a number of devices were fabricated and tested in a custom built test platform to characterize their efficiency performance. Additionally, testing was performed with integration of PCM thermal storage, and the storage time of the lab scale system was evaluated. Our latest testing results showed a STEG efficiency of 9.6%, indicating promising potential for high performance concentrated STEGs.