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This document contains a listing of the written scientific information originating in the Materials Joining (formerly the Welding and Brazing Group), Metals and Ceramics Division, Oak Ridge National Laboratory during 1951 through June 1991. This registry of documents is as much as possible, in the order of issue date.

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According to the present invention, a joined product is at least two ceramic parts, specifically bi-element carbide parts with a bond joint therebetween, wherein the bond joint has a metal silicon phase. The bi-element carbide refers to compounds of MC, M.sub.2 C, M.sub.4 C and combinations thereof, where M is a first element and C is carbon. The metal silicon phase may be a metal silicon carbide ternary phase, or a metal silicide.

Science.gov (United States)

The Swedish Ceramic Institute is an industrial research institute working with product-oriented research and development of ceramics and closely related materials. The institute works with the processing and fabrication of ceramic materials as well as with materials properties and design questions. Its website provides details of research projects (engineering ceramics, electroceramics, traditional ceramics). Publications are listed, with some downloadable files (annual reports, research reports, information leaflets). Sample materials data (mechanical properties, thermal properties) is given for oxides and non-oxide ceramics.

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There are a number of characteristics exhibited by ceramic materials that may provide potential benefits for the reciprocating internal combustion engine. However, the brittle nature of these materials together with a variability in strength has created difficulties in applying ceramic materials to the engine environment. Although a wide range of physical properties is available from contemporary ceramic materials, a material offering consistently high strength has yet to be developed. For sliding-contact applications, desirable characteristics include good wear resistance, low friction, ability to join metals and good heat dissipation. Test results have shown that cam/follower components with cast iron cam sliding on a silicon nitride follower exhibit very low wear rates. The application of silicon carbide to face seals has also shown substantial reductions in both friction and wear when compared with ...

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Pore Fraction in Yttrium-Barium-Copper-Oxide and. Other Polycrystalline. Materials ...... Properties of Yttrium Ceramic. Sov. J. LowTemp.Phys. 14:395-402 . ...

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... structure crystal-phase transformations fluorescence fluorescence spectroscopy

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In this, the last of a series of three papers, we discuss a method of forming iron phosphate ceramics by a reduction process. We report the formation of iron oxide ceramics by reducing hematite with iron in a phosphoric acid solution. The reaction results in a rapid-setting ceramic (at room temperature) with a compressive strength of 3700 psi and a density of 1.7 g/cm{sup 3}. Although the exact mineral form of the binder is difficult to determine because it is mostly amorphous and hence is not amenable to X-ray diffraction analyses, this material is expected to consist of iron hydrophosphates. The reduction process is very useful in recycling several industrial wastes that are rich in hematite, including iron mine tailings, red mud (a caustic waste from the alumina industry), and machining swarfs. Formation of ceramics with red mud and swarfs is also discussed.

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Carbide ceramics such as boron carbide due to their unique properties such as low density, high refractoriness, and high strength to weight ratio have many applications in different industries. This study focuses on direct bonding of boron carbide for high temperature applications using nickel interlayer. The process variables such as bonding time, temperature, and pressure have been investigated. The microstructure of the joint area was studied using electron scanning microscope technique. At all the bonding temperatures ranging from 1150 to 1300degC a reaction layer formed across the ceramic/metal interface. The thickness of the reaction layer increased by increasing temperature. The strength of the bonded samples was measured using shear testing method. The highest strength value obtained was about 100 MPa and belonged to the samples bonded at 1250 for 75 min bonding time. The strength of the joints decreased by increasing the bonding ...

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#beta#-sialon ceramics of equal overall compositions but containing amorphous, partly crystalline and almost completely crystalline intergranular phase(s) have been oxidized in oxygen at 1350 deg C for 20 hours. The obtained weight gain curves do not follow the parabolic rate law (#DELTA#W/A_0)"2= k_pt + #beta#. To the extent that crystallization occurs in the oxide scale during the oxidation experiment, the amorphous cross section area through which oxygen most easily diffuses will decrease with time. A brief description of this new rate law is given, and the obtained oxidation curves will be discussed within that framework. 4 refs., 2 tabs., 2 figs.

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In the course of designing a catalytic porous membrane reactor for experimental studies, both inside and outside of the non-reaction zones as well as the two ends of the membrane need to be completely sealed to ensure that there is no flow across the membrane in the non-reaction zone. Experiments show that up to 50% of the total flow across the membrane may be contributed by the axial flow along the wall of the non-reaction zones if only one side of the membrane is sealed. Another problem that cannot be solved by sealing is the capillary flow of the catalyst along the tube wall into the non-reaction zones when the catalyst is doped on the membrane. One of the best ways to avoid this axial flow of catalyst would be to use non-porous tubes in the non-reaction zones and join them with the porous membrane tube. In doing so, the cost of the membrane reactor could be reduced simply because shorter membrane tube is needed.

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A survey is presented of the principles and practice of tailoring sintering liquid composition and processing cycle to enable crystallisation of intergranular phases in silicon nitride and sialon ceramics. Critical features in sialon ceramics are the O/N balance in residual glasses and post-sintering heat-treatment temperatures to enable nucleation of either intermediate phases at constant composition or oxide phases with re-partitioning of non stoichiometric components in #beta#' or #alpha#' solid solutions. Crystallisation of disilicate phases in non-sialon compositions exemplifies a problem in control of polymorphs with differing atomic volumes. Crystallisation of intergranular phases has an influence mainly on high-temperature mechanical and environmental behaviour of these ceramics. (orig.).

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SiAlONs are ceramics with high potential as biomaterials due to their chemical stability, associated with suitable mechanical properties, such as high fracture toughness and fracture resistance. The objective of this work was to investigate the mechanical properties and the cytotoxicity of these ceramic materials. Three different compositions were prepared, using silicon nitride, aluminum nitride and a rare earth oxide mixture as starting powders, yielding Si_3N_4-SiAlON composites or pure SiAlON ceramics, after hot-pressing at 1750 deg. C, for 30 min. The sintered samples were characterized by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). Furthermore, hardness and fracture toughness were determined using the Vicker's indentation method. The biological compatibility was evaluated by in vitro cytotoxicity tests. Ceramic with elevated hardness, ranging ...

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In support of the efforts to apply ceramics in advanced heat engines, a study was made of the sliding performance of ceramics at the ring/cylinder interface of low heat rejection engines. The objective was to understand the basic mechanisms controlling the wear of candidate ceramics and thereby identify means for applying these ceramics effectively. Attempts to operate three different zirconias, silicon carbide, silicon nitride, and several plasma-sprayed ceramic coatings without lubrication were unsuccessful because of high friction and high wear rates. Experiments using a polyalphaolefin lubricant at temperatures to 260 C identified several combinations having wear rates in the general range likely to be acceptable for engines. Plasma-sprayed coatings of chromium oxide and hypersonic powder flame sprayed coatings of cobalt-bonded tungsten carbide performed ...

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The use of Sialon ceramics has been restricted by the high temperature required for synthesis and the expense of the pure oxide and nitride raw materials required. For refractory applications the purity required is less demanding and it has been possible to exploit the outstanding durability of the Sialons at moderate cost. New low cost manufacturing routes are being developed by nitriding silicon metal powder at relatively low temperature with clay and various additives depending on the Sialon required. For example the introduction of carbon or fine silicon carbide allows the preparation of beta Sialons and alpha Sialons which can be stabilised by including the appropriate cations. A wide range of composite Sialon bodies with diverse properties can be prepared by a one step process. Current projects developing the synthesis routes are aimed, in the first instance, at refractory manufacture but are showing promise for more sophisticated ...

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Different semi precious alloys (Pd-Ag, Pd-Au) have been studied after thermal oxidation treatments to analyze the mechanical improvement of the interface between the metal and the ceramic. Using the four point bending test, the authors have analyzed the different steps corresponding to the mechanical evolution of the bi-material : cracking energy on the surface, relaxation energy after first cracking, propagation energy of cracks at the interface zone. It has been shown that some alloys only have a high resistance to the interface cracking and the role played by the interface reactions to improve this property. (orig.).

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... Society Physics Press Release 05-175Korea Joins International Computing Infrastructure ... connectivity with Korea in a ceremony last month. Facilitated by the Korea Institute for Science and ...

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This work has been undertaken with a view to study the effect of lanthanum content on properties of PLZT ceramics. The polycrystalline complex compounds of PLZT with Pb{sub 1-x}La{sub x}(Zr{sub 0.40}Ti{sub 0.60}){sub 1-x/4}O{sub 3}, +10% PbO formula were prepared from the nano-size individual oxides powders by hot-pressed process. Transparent PLZT (x/40/60) bulk ceramics with pure tetragonal phase was obtained. The studies of the microstructures, dielectric and ferroelectric properties of the ceramics were carried out. The experiment results showed that when La content increased from 7 to 13 mol.%, the grain size increased from 2 to 7 {mu}m. La content also effects the dielectric property obviously, the dielectric constant increased with La content increasing. Moreover, the ferroelectric properties are sensitive to the variation of La content.

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The chemical interaction of a Si{sub 3}N{sub 4} ceramic with pristine and oxidised 100Cr6 steel was studied by means of static interaction couple experiments between 500 and 1200 C. Si{sub 3}N{sub 4} was not chemically stable in contact with oxidised steel at elevated temperatures, and reacts with the formation of N{sub 2}, SiO{sub 2} and/or Fe{sub 2}SiO{sub 4} at temperatures at and above 1000 C. At 700 and 500 C, Si diffusion into the oxide layer indicated the dissociation of the Si{sub 3}N{sub 4} ceramic. Si{sub 3}N{sub 4} also dissociated in contact with pristine steel. In the temperature region between 700 and 1100 C, the Si dissolves and diffuses into the steel whereas a nitrogen pressure is built-up in the voids of the metal-ceramic interface, limiting the degree of interaction. Above 1100 C, the nitrogen dissolves and diffuses into the steel as well, enhancing the reactivity and resulting in the ...

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A method of kinetic analysis applicable to non-isothermal oxidation processes of ceramic nanocomposites is presented using Ti-Si-C-N powder as the substrate. The nanoparticle size and phase composition were determined using high-resolution transmission electron microscopy and X-ray diffraction (XRD). Thermogravimetric measurements were carried out for powder samples in dry air in the temperature range 298-1770 K. The following heating rates were applied: 3, 5, 10, 20 K min{sup -1}. Mass spectrometry was used to analyze gaseous oxidation products and solid products were identified by the XRD technique. The Coats-Redfern equation was applied for the kinetic analysis. For each stage of the oxidation kinetic models, the best accuracy was achieved using a series of criteria, and then the A and E parameters of the Arrhenius equations were estimated. Both linear regression and artificial neural networks were ...

International Nuclear Information System (INIS)

A family of sealant materials has been developed for use in the solid oxide fuel cell (SOFC) and in other applications in the temperature range of 800 endash 1000 degree C. These materials are based on glasses and glass-ceramics in the SrO endash La_2O_3 endash Al_2O_3 endash B_2O_3 endash SiO_2 system. The coefficients of thermal expansion (CTE) for these materials are in the range of 8 endash 13x10"-"6/degree C, a good match with those of the SOFC components. These sealant materials bond well with the ceramics of the SOFC and, more importantly, form bonds that can be thermally cycled without failure. At the fuel cell operating temperature, the sealants have viscosities in the range of 10"4-10"6 Pa-s, which allow them to tolerate a CTE mismatch of about 20% among the bonded substrates. The gas tightness of a sample seal was demonstrated in a simple zirconia-based oxygen concentration cell. copyright 1996 Materials Research ...

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The method of production of xAl{sub 2}O{sub 3}-yTiO{sub 2} compositions provides for the depth distribution of coating components and specifies its mechanical properties. In case of the composition obtained by cladding, titanium is mainly concentrated at the substrate. In case of mechanical mixture or composition obtained by sintering the oxides, the depth distribution of coating components is random.

Science.gov (United States)

Course website from Cambridge on ceramic materials. This site contains eight lectures in PDF format (Adobe Reader required), two question sheets, five practicals (including answers), digital movies and further useful links. "There is a strong relationship between the structure of a material and its physical properties. The properties of a material whether mechanical, electrical, optical or magnetic, determine how it can be used in practical applications. In this course, the focus is on the structure / property relationship for ionic materials with electrical properties utilised in various transducer devices. The materials considered include perovskites, which have special polarisation properties exploited in ferroelectric, pyroelectric and piezoelectric devices. Other oxides, such as zirconia, have structures permitting rapid diffusion of ions, making them suitable for use in sensors, fuel cells and batteries. The scientific principles ...

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Heat fusion is the most common joining method for polyethylene gas distribution piping. Butt fusion was studied with the intent of relating the quality of the joint to the joining conditions. A semi-empirical approach was used. The thermofluid consequences of joining conditions such as heater temperature, heating time and joining parameter were calculated using a computer model. The model was validated by instrumented tests. The strength of the joints was gauged by destructive mechanical testing. Tensile and tensile impact tests were used. Over 150 joints were fabricated using four different polyethylene resins. Most of the data are given in GRI Report No. 88/0276.2 -- Volume 2: Technical Reference on Butt Heat Fusion Joining of Polyethylene Gas Pipes. A parameter, termed the Joining Parameter, was found to characterize the joining ...

CERN Document Server

PLZT Ceramics Prepared from Conventional and Microwave Hydrothermal Powders

International Science & Technology Center (ISTC)

Development of Ceramic Composite Materials and Structural Elements for High-Temperature Nuclear Reactors

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Protonic ceramic membrane fuel cells (PCMFCs) based on proton-conducting electrolytes have attracted much attention because of many advantages, such as low activation energy and high energy efficiency. A stable, easily sintered perovskite oxide BaCe_0_._5Zr_0_._3Y_0_._1_6Zn_0_._0_4O_3_-_#delta# (BCZYZ) as electrolyte for proton-conducting solid oxide fuel cells (SOFCs) with Sm_0_._5Sr_0_._5CoO_3_-_#delta# (SSC) composite cathode is investigated. By fabricating thin membrane BCZYZ electrolyte (#approx#20 #mu#m) synthesized by a modified Pechini method on NiO-BCZYZ anode support, PCMFCs are assembled and tested by selecting SSC perovskite cathode with high mixed ionic and electronic conductivities. An open-circuit potential of 1.015 V, a maximal power density of 528 mW cm"-"2, and a low polarization resistance of the electrodes of 0.15 #OMEGA# cm"2 is achieved at 700 "oC. The results indicate that BCZYZ proton-conducting ...

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... joined together by a thin ribbon of glass that is bent into a frame shape in a prior operacion. The three glass pieces are ...

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Microwave-hydrothermal processing was compared with conventional hydrothermal processing in the crystallization of hematite from 1M ferric nitrate and hydroxyapatite from calcium oxide and phosphoric acid. Microwave-hydrothermal processing led to the crystallization of hematite while convention-hydrothermal process led to the crystallization of a mixture of goethite and hematite under the same temperature conditions. Thus the crystallization of hematite which is the stable iron oxide phase at high temperatures has been catalyzed by microwaves. Microwave-hydrothermal processing also led to highly crystalline hydroxyapatite powders compared to the conventional hydrothermal processing which also points to the catalytic role of microwaves. The microwave induced effects may be attributed to the generation of localized high temperatures at the reaction sites which enhance reaction rates.

British Library Electronic Table of Contents (United Kingdom)

Ceramic coatings with high emission were fabricated on Ti6Al4V alloy by microarc oxidation (MAO) with additive FeSO4 into the electrolyte. The microstructure, chemical composition and chemical state of the coatings were determined by SEM, XRD, EDS and XPS, respectively. The bonding strength between the coating and substrate was studied by tensile strength test, together with the thermal shock resistance of the coating. The results showed that Fe content in the coating layer significantly affect its thermal emissivity. The relative content of Fe in the coatings surface increased at first and then decreased with increasing the concentration of FeSO4 in electrolytes, so does the emissivity of the coatings. The bonding strength became weaker with increasing the concentration of FeSO4. In addit...

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Ferroelectric [Pb_0_._9_2(La_1_-_zSb _z)_0_._0_8][Zr_0_._6_0Ti_0_._4_0]O_3 for z = 0.0, 0.3, 0.6, 0.9 and 1 were prepared from their constituent oxides by a solid state reaction technique. The powders were calcined in the temperature range of 1000 deg. C for 6 h. Phase formation, crystal structure and lattice parameter were investigated by X-ray diffraction (XRD) technique. The compacts were sintered at 1250 deg. C for 2 h and their dielectric, ferroelectric and conductive properties were measured. The ferroelectric behavior of the doped samples was studied from their hysteresis loop.

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The behavior of MEMS devices is limited by the strength of critical features such as thin ligaments, oxide cuts joining layers, pin joints and hinges. Devices fabricated at Sandia's Microelectronic Development Laboratory have been successfully tested to investigate these features. A series of measurements were performed on samples with gage lengths of 15 to 1000 microns, using conventional and tungsten coated samples as well as samples that include the critical features of standard components in the test section. Specimens have a freely moving pin joint on one end that anchors the sample to the silicon die to allow rotation to reduce effects of bending. Each sample is loaded in uniaxial tension by pulling laterally with a flat tipped diamond in a computer-controlled Nanoindenter. Load is calculated by resolving the measured lateral and normal forces into the applied tensile force and frictional losses. The specimen cross section and ...

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The effect is reported of seven inorganic oxide additives on both the formation mechanism and the densification of X-Sialon prepared by a silicothermal process. The oxides were added to the starting mixture of halloysite clay, alumina and elemental silicon at a level of 1 wt% of the calculated final product, and fired in nitrogen at 1200-1500 deg C. The formation of X-Sialon was monitored by thermal analysis, powder XRD and 2"7"Al and "2"9Si solid state MAS NMR The effects of the additives are temperature dependent and influence the various stages of the reaction by differing degrees. The oxides which best promote the formation of crystalline X-Sialon (Y_2O_3, CaO and MgO) are also those which facilitate the conversion of initially-formed Si_3N_4 to SiO_2N_2 and SiO_3N units. Densification is most enhanced by Y_2O_3 CaO and CeO_2; MgO exerts its maximum effect on sintering at lower temperatures. Copyright (1998) ...

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A schematic diagram shows the various processing steps to be performed during feed preparation in the Hanford Waste Vitrification Plant (HWVP). The pretreated NCAW is transferred to the slurry receipt adjustment tank (SRAT) in the HWVP for concentration. Water removed during boildown is collected in the slurry mix evaporator condensate tank (SMECT). After waste treatment the water is returned to the storage tanks for eventual disposal. The pretreated Neutralized Current Acid Waste (NCAW) is concentrated in the SRAT to approximately 125 g waste oxides/ liter. Formic acid is then added at a controlled rate to improve rheological properties and achieve a required reduction/oxidation state. Reflux boiling is initiated and continued for several hours. The concentrated slurry is cooled and pumped to the slurry mix evaporator (SME). In the SME, glass frit is added, and the slurry is further concentrated to achieve a nominal composition of 500 g total ...

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YBa{sub 2}Cu{sub 3}O{sub x} superconducting ceramics containing various oxides were prepared, and their superconducting properties and degradation in moisture were discussed. The addition of Ag{sub 2}O greatly contributed to improve their properties, for example, in the specimen containing Ag{sub 2}O of 1-5wt%, a relative density was enhanced up to 95% of a theoretical density, and a critical current density was 2-3 times as large as that of non-added one. As the results of accelerated aging tests at 85{degree}C in the air of 100% relative humidity, in non-added specimens, the resistivity vs. temperature characteristics were strongly affected by moisture only for 30min, however, in Ag-added ones, no effects were detected even after 5h. A superconducting wire was made of an Ag pipe and superconducting powder containing Ag{sub 2}O of 5wt% by drawing and heating at 850{degree}C in air for 20h, and its critical current density consequently attained ...

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... The data were transformed into total hemispherical emittance values and correlated with respect to ceramic coating thickness and temperature ...

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Ba(Ti{sub 1-x}Ce{sub x})O{sub 3} ceramics with x = 0.1, 0.2, 0.3, 0.33, 0.4 and 0.5 have been synthesized by the mixed oxide method. Dielectric measurements were performed for Ba(Ti{sub 1-x}Ce{sub x})O{sub 3} ceramics from 10{sup 2} to 10{sup 5} Hz in the temperature range 85 - 700 K. The dielectric measurements confirmed that the solid solution range extends up to about x=0.3. In the solid solutions, the temperature of the permittivity maximum was shifted at a rate of -7 K/mol% Ce atom and the permittivity maximum decreased with increasing Ce content. The temperature and frequency dependence of the permittivity was fitted by the Curie - Weiss law beyond the transition temperature and characterized by parameters that are used to describe relaxor behaviour. (author)

International Nuclear Information System (INIS)

We provide a detailed overview of an on-going, multinational test programme that is developing aerosol data for some spent fuel sabotage scenarios on spent fuel transport and storage casks. Experiments are being performed to quantify the aerosolised materials plus volatilised fission products generated from actual spent fuel and surrogate material test rods, due to impact by a high-energy/density device. The programme participants in the United States plus Germany, France and the United Kingdom, part of the international Working Group for Sabotage Concerns of Transport and Storage Casks (WGSTSC) have strongly supported and coordinated this research programme. Sandia National Laboratories has the lead role for conducting this research programme; test programme support is provided by both the US Department of Energy and the US Nuclear Regulatory Commission. We provide a summary of the overall, multiphase test design and a description of all explosive containment and aerosol collection ...

International Nuclear Information System (INIS)

The authors provide a detailed overview of an on-going, multinational test program that is developing aerosol data for some spent fuel sabotage scenarios on spent fuel transport and storage casks. Experiments are being performed to quantify the aerosolized materials plus volatilized fission products generated from actual spent fuel and surrogate material test rods, due to impact by a high-energy-density device. The program participants in the United States plus Germany, France and the United Kingdom, part of the international Working Group for Sabotage Concerns of Transport and Storage Casks (WGSTSC) have strongly supported and coordinated this research program. Sandia National Laboratories has the lead role for conducting this research program; test program support is provided by both the US Department of Energy and the US Nuclear Regulatory Commission. The authors provide a summary of the overall, multiphase test design and a description of all explosive containment and aerosol ...

International Nuclear Information System (INIS)

Under the direction of the NASA-Glenn Research Center, the Edison Welding Institute (EWI) in Columbus, OH performed a series of non-fusion joining experiments to determine the feasibility of joining refractory metals or refractory metal alloys to Ni-based superalloys. Results, as reported by EWI, can be found in the project report for EWI Project 48819GTH (Attachment A, at the end of this document), dated October 10, 2005. The three joining methods used in this investigation were inertia welding, magnetic pulse welding, and electro-spark deposition joining. Five materials were used in these experiments: Mo-47Re, T-111, Hastelloy X, Mar M-247 (coarse-grained, 0.5 mm to several millimeter average grain size), and Mar M-247 (fine-grained, approximately 50 (micro)m average grain size). Several iterative trials of each material combination with each joining method were performed to ...

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Some properties of the remarkable Ti{sub 3}SiC{sub 2} based ceramic synthesised by hot pressing of elemental Ti, Si, and C powders have been investigated. Its flexural strength by using three point bending tests and fracture toughness by using single edge notched beam tests were measured at room temperature to be in the range 310-427 MPa and about 7.MPa m{sup 1/2}, respectively. This material is a relative 'soft' ceramic with a low hardness of 4 GPa. Ti{sub 3}SiC{sub 2} is similar to the soft metals and is a damage tolerant material that is able to contain the extent of microdamage. An oxidation test has been performed in the temperature range 1000-1400{sup o}C in air for 20 h. The oxidation resistance below 1100{sup o}C was good. Two oxidized layers were formed, the outer layer consisting of pure rutile-type TiO{sub 2}, and the inner layer a mixture of SiO{sub 2} ...

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Samarium cobaltite ceramic perovskites, with and without platinum particles dispersion, are possible candidates as electrode for electrochemical conversion of hydrocarbon and for intermediate temperature solid oxide fuel cells (ITSOFC). In this work, samarium cobaltites were synthesized by the combustion method using cobalt, and samarium nitrates as cation precursors and urea as fuel. For containing-platinum compositions Pt (II) acetyl acetonate was also employed as precursor. The effect of Sr on the phase formation and its electrical behavior is also studied. Specific surface area (BET), SEM-EDX, TEM and XRD analysis are used to characterize the powders obtained. Powders were pressed into pellets and sintered in air in the temperature range of 1200 -1400 C. Electrical impedance spectroscopy studies (EIS) are performed on sintered samples. The as-prepared powders showed an amorphous structure and by TEM a very small particle size ...

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May 25, 2006 ... Former NASA Astronaut Roger Crouch will help open the commemoration of the 400th anniversary of Jamestown in Alexandria, Va., ...

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Cambridge scientists in the late 1980's. This same team, then headed by Professor John Baldwin, built the world's first separated-element optical/infrared aperture synthesis...

International Nuclear Information System (INIS)

In this paper, 0.75Pb(Fe2/3W1/3)O3-0.25PbTiO3-0.15 wt% MnO (0.75PFW-0.25PT-0.15 wt% MnO) ceramics are synthesized by two different methods, the conventional direct oxide synthesized (DS) method and two-step indirect synthesized (IS) method. The low-field dielectric responses are investigated by using the empirical law, the Curie-Weiss law, the modified-Landau theory and the spin-glass model. Due to the IS method, the lattice structure and the grain structure of the samples are changed. Furthermore, the dielectric properties are evidently modified. It is suggested that the ordering degree of B-site cations is enhanced by using the IS synthesized method.

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... 300710+Ceramic+Transactions+Series 2120%28Series+Code%29+Ceramic+Transactions+Series Wiley::Ceramic Transactions Series WILEY KNOWLEDGE FOR GENERATIONS United States Change Location Home ...CART | MY ACCOUNT | CONTACT US | HELP Home / Engineering & Materials Science / Materials Science / Ceramic Transactions Series Related Subjects Soft Matter Organic Electronics Structural Materials, ... Ceramics Structural Materials, Composites Structural Materials or Construction Materials Corrosion Electronics Materials Related Series Ceramic Engineering and Science Proceedings Wiley Series in Materials ...for Electronic and Optoelectric Applications Ceramic Transactions (CTs) books contain papers presented at the Annual Meeting of the American Ceramic Society, ...

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Effect of alcohol solvent in mixing process on process on the microstructure and sintering behavior of ceramic-based composites was inestigated in detail. The mixture of fine ceramic powders was prepared through the conventional ball-milling method with various alcohol media. The particle distributions of fine ceramic powders were strongly dependent on the kind of alcohol employed during ball-milling. Ceramic-based composites were fabricated by hot-pressing the mixture of fine ceramic powders. Their microstructures and some mechanical properties of the ceramic-based composites were evaluated. It was found that the viscosity of alcohol, surface tension and contat angle greatly affect the sinterbility and some of the mechanical properties of ceramic-based somposites. (author)

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In addition to ceramics, alloys such as tool steel and nickel- and iron-based superalloys are being considered for high temperature applications such as missile bearings and low heat rejection engines. Studies were made to lubricate a nickel-based superalloy at 500{degrees}C, by using a vaporized aryl phosphate ester, at a concentration of 0.1% in air. From deposition and wear studies it was found that it was impossible to form a good polymeric coating on the superalloy surface. Energy dispersive X-ray analyzer (EDXA) analysis showed that this was due to minute quantities of aluminum in the alloy segregating to the surface, upon being heated to 500{degrees}C, forming a passive oxide coating. It was necessary to activate the surface, in order to lubricate the material successfully. A method of activation by electrodepositing the surface with a layer of iron oxide was developed. Once activated, a good lubricous polymer was ...

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An extensive R and D program on the development of the joining technologies between armour (beryllium, tungsten and carbon fibre composites)/copper alloys heat sink and copper alloys/ stainless steel has been carried out by ITER Home Teams. A brief review of this R and D program is presented in this paper. Based on the results, reference technologies for use in ITER have been selected and recommended for further development. (author)

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The report investigates a number of joining techniques, i.e. isothermal solidification, ultrasonic welding, thermocompression, and glueing. (HW) [Deutsch] In diesem Vorhaben wurden verschiedene Verbindungstechniken untersucht: Isotherme Erstarrung; Ultraschall-Schweissen; Thermokompression; Leitkleben. (HW)

UK PubMed Central (United Kingdom)

All ceramic fixed partial dentures (FPD)s exhibit enhanced biocompatibility and esthetics as compared to metal-ceramic restorations. However, framework fractures are frequently reported especially when...Full Text Available

Science.gov (United States)

Lecture notes (pdf) on Ceramics is part of a physics course on the properties of matter from the University of Auckland, Department of Chemical and Materials Engineering. The following topics are covered: types of chemical bonding, degree of ionic character, structure of ceramics and crystallography, interstitial sites in different crystal structures, silicate structures, glasses, glass transition temperature, glass viscosity, thermal and mechanical properties of ceramics and glasses, fracture properties of ceramics and processing of ceramic materials. Keywords: ionic bonds; covalent bonds; coordination numbers; thermal shock; grain growth; sintering; green body

International Nuclear Information System (INIS)

As part of a study into the properties of ferroelectric single crystals at nanoscale dimensions, the effects that focused ion beam (FIB) processing can have, in terms of structural damage and ion implantation, on perovskite oxide materials has been examined, and a post-processing procedure developed to remove such effects. Single crystal material of the perovskite ferroelectric barium titanate (BaTiO_3) has been patterned into thin film lamellae structures using a FIB microscope. Previous work had shown that FIB patterning induced gallium impregnation and associated creation of amorphous layers in a surface region of the single crystal material some 20 nm thick, but that both recrystallization and expulsion of gallium could be achieved through thermal annealing in air. Here we confirm this observation, but find that thermally induced gallium expulsion is associated with the formation of gallium-rich platelets on the surface of the annealed material. These platelets ...

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The integrity of a pipeline system is determined by its weakest links which may be the joints. Heat fusion is the most common method for joining gas distribution polyethylene (PE) piping. There are procedural, thermal, and mechanical aspects of making fusion joints. Acceptable procedural aspects, such as heater calibration and cleanliness, can be assured by rigorous training and certification of the operators. Thermal and mechanical aspects consist of specifying joining conditions such as the heater temperature, heating time, and joining pressure. In the absence of procedural errors, the strength of a fusion joint should depend on the pipe material, pipe dimensions, and the thermal and mechanical joining conditions. Socket heat fusion was studied both experimentally and analytically to determine how the strength of the joint varied with the conditions under which it was made. The standard tensile impact ...

International Nuclear Information System (INIS)

In the frame of the Primary Wall Module prototype manufacturing for ITER, a consistent R and D phase was conducted in order to identify the industrial allowable tolerances and manufacturing problems which would occur when joining pieces by HIPping process during the PW module manufacturing. The purpose of this development was to give as industrial as possible manufacturing routes for joining together large Stainless Steel or DS-Copper pieces with Stainless Steel tubes and for bonding Beryllium tiles onto a curved component surface. The study concerned surface preparations, allowable gaps and joint geometry, Beryllium tile geometry, Titanium interlayer thickness, etc. This R and D phase also allowed the development and validation of different ultrasonic inspection tools needed for plate-plate, tube-plate, edge to edge plate bonding.

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

Energy Technology Data Exchange (ETDEWEB)

The production, principal applications, characteristics and properties, advantages of the gas natural is showed. A sectorial overview of the ceramic industry and the utilization of the natural gas in the ceramic industry is presented. The expectations are systematized and the impact of the natural gas utilization in the ceramic industry is evaluated. Some conclusions are withdrawn and recommendations suggested.

International Nuclear Information System (INIS)

Short communication.

KoreaScience (Korea)

Full Text Available

Science.gov (United States)

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International Nuclear Information System (INIS)

Particulate ceramic composites that were composed of a combustion-synthesized #beta#'-SiAlON matrix and dispersed MoSi_2 particles were hot pressed at 1,600 C in a nitrogen atmosphere. The physical and mechanical properties of the composites that contained 15, 30, and 45 vol% MoSi_2 were evaluated. The average four-point bend strength, fracture toughness, and Vickers hardness of the composites were in the ranges of 500--600 MPa, 3--4 MPa#centre dot#m"1"/"2, and 11--13 GPa, respectively. The measured mechanical strength and hardness were very similar to the values that were predicted from the rule of mixtures. The fracture toughness of the combustion-synthesized #beta#'-SiAlON (2.5 MPa#centre dot#m"1"/"2) was apparently enhanced by the MoSi_2 particles that were added. The increase in the fracture toughness was predominantly attributed to the residual thermal stress that was induced by the thermal expansion mismatch between the MoSi_2 particles and the ...

Energy Technology Data Exchange (ETDEWEB)

Polycrystalline Al2O3, magnesium aluminate spinel (MgAl2O4), MgO, Si3N4, and SiC were irradiated with various ions at 200-450 K, and microstructures were examined following irradiation using cross-section TEM. Amorphization was not observed in any of the irradiated oxide ceramics, despsite damage energy densities up to {similar_to}7 keV/atom (70 displacements per atom). On the other hand, SiC readily amorphized after damage levels of {similar_to}0.4 dpa at room temperature (RT). Si3N4 exhibited intermediate behavior; irradiation with Fe{sup 2+} ions at RT produced amorphization in the implanted ion region after damage levels of {similar_to}1 dpa. However, irradiated regions outside the implanted ion region did not amorphize even after damage levels > 5 dpa. The amorphous layer in the Fe-implanted region of Si3N4 did not appear if the specimen was simultaneoulsy irradiated with 1-MeV He{sup +} ions at RT. By comparison with published results, ...

International Nuclear Information System (INIS)

Ferroelectric Pb_0_._9_8_2_-_zLa_0_._0_1_2#DELTA#_0_._0_0_6Ba_z(Zr_0_._5_5Ti_0_._4_5)O_3 (PLZT; z = 0-6 mol%) ceramic compositions were fabricated by a mixed-oxide method. X-ray diffraction studies of sintered ceramics indicate the coexistence of rhombohedral and tetragonal phases in the 5 mol% Ba-doped PLZT composition. Grain growth is inhibited with increasing Ba concentration in the PLZT system as evidenced by scanning electron micrographs. Dielectric constant and dielectric loss as a function of temperature suggest that #epsilon#_r_t and tan #delta# are increased up to compositions containing 4 and 5 mol% Ba, respectively. The dielectric maximum (#epsilon#_T_c) decreased to 4 mol% Ba and gradually increased to 6 mol% Ba, whereas, with increasing Ba concentration in the PLZT system, the Curie temperature (T_C) decreased from the composition with no Ba to that with 6 mol% Ba. Relaxor behavior as a function of temperature ...

Energy Technology Data Exchange (ETDEWEB)

We provide a detailed overview of an ongoing, multinational test program that is developing aerosol data for some spent fuel sabotage scenarios on spent fuel transport and storage casks. Experiments are being performed to quantify the aerosolized materials plus volatilized fission products generated from actual spent fuel and surrogate material test rods, due to impact by a high energy density device, HEDD. The program participants in the U.S. plus Germany, France, and the U.K., part of the international Working Group for Sabotage Concerns of Transport and Storage Casks, WGSTSC have strongly supported and coordinated this research program. Sandia National Laboratories, SNL, has the lead role for conducting this research program; test program support is provided by both the U.S. Department of Energy and Nuclear Regulatory Commission. WGSTSC partners need this research to better understand potential radiological impacts from sabotage of nuclear material shipments and storage casks, and ...

Science.gov (United States)

In the late 1980's, the traditional threat of anonymous break-ins to networked computers was joined by viruses and worms, multiplicative surrogates that carry out the bidding of their authors. Technologies for authentication and secrecy, supplemented by good management practices, are the principal countermeasures. Four articles on these subjects are presented.

UK PubMed Central (United Kingdom)

Conducting rigorous psychosocial intervention research with cancer patients has many challenges including encouraging them to join studies, asking them to engage in interventions or be part...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

High-spatial-resolution microfocus-based X-ray imaging technology, both real-time and film, has been used to study the thickness variation that occurs in the oxide core of silver-sheathed BSCCO ribbons produced by the powder-in-tube method. This thickness variation (also called ``sausaging``) occurs during incremental rolling and degrades the critical current densities of the ribbons. Using X-ray image data the authors determined the onset and severity of sausaging. Onset occurred at a ribbon thickness of 203 {micro}m, and the severity increased with subsequent rolling reductions. Scanning electron microscopy was used to confirm the X-ray image data. X-ray imaging provides several advantages over more traditional methods for characterizing the superconductors such as optical or scanning electron microscopy. The X-ray imaging provides nondestructive information about the entire width of the ribbon, with far greater speed, lower cost, and more flexibility than the ...

International Nuclear Information System (INIS)

MoSi_2-particulate-reinforced #alpha#-SiAlON ceramic composites 10, 20, 25, and 30 vol% were prepared by at 1,750--1,800C. The #alpha#-SiAlON matrix was of the composition (Y_0_._4_8Si_1_0_._0_0Al_2_._3_0O_1_._1_7N_1_5_._2_9). The hardness for the fully dense samples changed from HV10 = 22.5 to 15.3 GPa and the toughness from 3.2 to around 5.2 MPa#centre dot#m"1"/"2 when up to 30 vol% MoSi_2 was present. Two interesting microstructural features have been found. First, with an increasing amount of MoSi_2 a pronounced coalescence of MoSi_2 particles formed a ''dual phase'' material. The second effect was the growth of elongated #alpha#-SiAlON grains in the matrix with 10 vol% MoSi_2 added. The oxidation resistance has been determined, to be unaffected by the addition of 20 vol% MoSi_2 at 1,250 C in oxygen gas of 1 atm pressure.

International Nuclear Information System (INIS)

Ceramic matrix composites in the TiC-Ti, Y-TZP system can be synthesized by the reaction between carbon and the TiO_2-Y_2O_3-ZrO_2 solid solution nanopowder. This method results in the more homogeneous powders than those prepared by the physical mixing of TiC and zirconia s.s. powders. Twelve TiO_2-Y_2O_3-ZrO_2 solid solution nanopowders differing in the proportions of the constituent oxides were prepared by the coprecipitation- calcination route. They were reacted with the pyrolytic carbon evenly distributed within the system. Carbon was introduced by the thermal decomposition of the phenol-formaldehyde resin dissolved in ethyl alcohol and mixed with the zirconia s.s. nanopowder. Reaction was performed in vacuum. Compacts of the composite powders sintered in vacuum give dense materials of evenly distributed TiC inclusions of sizes not surpassing 400 nm. Hardness of such materials was dependent on their chemical and phase composition but was ...

Energy Technology Data Exchange (ETDEWEB)

This paper contains literature from American Power Conference Air Toxics Being Measured Accurately, Controlled Effectively NO{sub x} and SO{sub 2} Emissions Reduced; Surface Condensers Improve Heat Rate; Usable Fuel from Municipal Solid Waste; Cofiring Technology Reduces Gas Turbine Emissions; Trainable, Rugged Microsensor Identifies of Gases; High-Tc Superconductors Fabricated; High-Temperature Superconducting Current Leads; Vitrification of Low-Level Radioactive and Mixed Wastes; Characterization, Demolition, and Disposal of Contaminated Structures; On-Line Plant Diagnostics and Management; Sulfide Ceramic Materials for Improved Batteries; Flywheel Provides Efficient Energy Storage; Battery Systems for Electric Vehicles; Polymer-Electrolyte Fuel Cells for Transportation; Solid-Oxide Fuel Cells for Transportation; Surface Acoustic Wave Sensor Monitors Emissions in Real-Time; Advance Alternative-Fueled Automotive Technologies; Thermal & ...

International Nuclear Information System (INIS)

The objectives of this research were to investigate the possibility of controlling the #alpha#'/#beta#' phase ratio and morphology in Sialon ceramics. These objectives have been sought by the control of the starting composition, and by post sintering heat treatment. The main emphasis has been on the production of a series of #alpha#' and (#alpha#'+#beta#') Sialon ceramics with a minimum amount of the glass phase by the pressureless sintering technique and using ytterbium (Yb) as an #alpha#' stabilising element. The Yb additions were made via the oxide or the alumino- silicate presynthesised glass; the latter was found to improve the density. The XRD analysis of the as sintered materials revealed #alpha#' to be the dominant phase with minor contributions from #beta#' sialon and/ or 12H A1N polytype. Additions of SiO_2 or #beta#-Si_3N_4 were made to various materials to assess potential mechanisms for obtaining control over ...

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Porcelain fracture associated with an implant-supported, metal ceramic crown or fixed partial denture occurs at a higher rate than in tooth-supported restorations, according to the literature. Implant-specific and patient-specific causes of ceramic failure have not been fully evaluated. Purpose The purpose of this retrospective study was to evaluate the potential statistical predictors for porcelain fracture of implant-supported, metal ceramic restorations. Material and Methods Over a 6-month period, a consecutive series of patients having previously received implant-supported, metal ceramic fixed restorations were examined during periodic recall appointments. The number of supporting implants, number of dental units, type of restoration, date of prosthesis insertion, ...

Energy Technology Data Exchange (ETDEWEB)

Ceramic ball bearings of silicon nitride are used for hard disk drive (HDD) spindle motors, to increase seed, reliability and memory capacity of the HDDs. Silicon nitride ceramics have advantages of lightweight, high strength and hardness over the conventional steel for bearings, but is expensive. A new process of high cost performance has been developed for mass production of the small-size ceramic balls. The company plans to apply these bearings to higher devices, e.g., servers, for the time being, and to expand the applicable areas, e.g., common devices and other small-size motors. The ceramic bearings have been developed jointly with Koyo Seiko Co. Ltd. (translated by NEDO)

Energy Technology Data Exchange (ETDEWEB)

The Co-doped BaTiO{sub 3} nanosized powders and ceramics were prepared via the sol-gel process. The powders and ceramics were characterized by methods of XRD, SEM and TEM. The dielectric properties of the ceramics were also determined by these methods. The influence of sintering temperature, sintering time and Co concentration on the microstructure and dielectric properties was discussed. The results revealed that the powders were in nanometer scale (30-50 nm) and were mainly composed of cubic BaTiO{sub 3} phase and small amount of BaCO{sub 3}. After sintering, both the cubic BaTiO{sub 3} and BaCO{sub 3} were transformed into tetrahedron BaTiO{sub 3}. The sintering temperatures of the Co-doped BaTiO{sub 3} ceramics decreased (about 100 deg. C) and the Curie temperatures of the ceramics were then moved to lower temperature. In addition, the dielectric constant of the ...

Energy Technology Data Exchange (ETDEWEB)

In order to design the microstructure of ceramics with desired dielectric property, an estimation method of dielectric constant of ceramics taking into account the characteristics of microstructure of the ceramics is proposed. In the estimation model, the microstructure of ceramics is represented by the assembly of unit cells comprising of grain, pore and grain boundary. The sizes of grain and pore and the thickness of grain boundary in each unit cell were determined exactly according to their size and thickness distributions in a real ceramic. The dielectric constant of the assembly can be calculated on the basis of equivalent circuit theory. The estimated values of dielectric constant of ceramic BaTiO{sub 3} using the proposed estimation method agree well with experimental ones. The dependence of characteristics of microstructure on the dielectric constant was ...

Science.gov (United States)

... Accession Number : ADA539462. Title : 6.5 kW, Yb:YAG Ceramic Thin Disk Laser. Descriptive Note : Technical note 1 Jan-1 Dec 2010. ...

International Science & Technology Center (ISTC)

Development of SHS-technologies for SiC, Si3N4 and Ceramic Composites on Their Basis from Rocks

International Nuclear Information System (INIS)

English Mar 1999 [vp.] United Kingdom Jumali, MHH Warwick Univ.,

Science.gov (United States)

... 1 ..... 14 High Dielectric Constant Ceramics for Use in Blumlein Transmission Lines ..... 14 ...

Medline Plus

... energy. It consists of a stack of piezoelectric ceramics sandwiched under high pressure between two metal cylinders. ...

Energy Technology Data Exchange (ETDEWEB)

The addition of titanium to eutectic braze compositions causes these alloys to readily wet and bond to A1N ceramics. Electron microscopic characterizations of the metal-ceramic interfaces reveal the presence of TiN, along with other Ti- and Al-containing phases. The formation of such interfacial reaction products is an additional thermodynamic driving force for the creation of useful metal-ceramic bonds. 12 refs., 4 figs., 1 tab.

Energy Technology Data Exchange (ETDEWEB)

An advanced ceramic dome cavity receiver is discussed which heats pressurized gas to temperatures above 1800/sup 0/F (1000/sup 0/C) for use in solar Brayton power systems of the dispersed receiver/dish or central receiver type. Optical, heat transfer, structural, and ceramic material design aspects of the receiver are reported and the development and experimental demonstration of a high-temperature seal between the pressurized gas and the high-temperature silicon carbide dome material is described.

Science.gov (United States)

The use of ceramics as energy absorbents has been studied by many researchers and some improvements in the ballistic performance of ceramic tiles have been made by coating them with different classes of materials (e.g. E-glass/epoxy, carbon-fiber/epoxy, etc.). Using ceramics for energy absorbing applications leads to a significant weight reduction of the system. Therefore, any modification to the ceramic configuration in the system which leads to more energy absorption with the same or less areal density is significant. On the other hand, polyurea has been proved to be an excellent energy dissipating agent in many applications. Inspired by this, we are studying the effect of coating ceramics with polyurea and other materials, on the energy absorption and ballistic performance of the resulting ceramic-based composites. In this study, we investigate the effect of ...

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Computer-aided design/computer-aided manufacturing (CAD/CAM) titanium ceramic restorations were developed with the potential for replacing expensive, high noble metal ceramic restorations. However, there is a lack of information about the clinical performance of CAD/CAM titanium ceramic single crowns. Purpose The purpose of this study was to evaluate CAD/CAM titanium ceramic single crowns after 3 years in function. Material and methods A total of 41 crowns were fabricated for 21 patients. The titanium copings were CAD/CAM milled (Everest CAD/CAM system) with an even thickness of 0.5 mm, and low-fusing veneering porcelain (Vita Titanium Porcelain) was added incrementally. The crowns were cemented using zinc phosphate cement after confirming that there were no mechanical...

British Library Electronic Table of Contents (United Kingdom)

Statement of problem Although the esthetic outcome of a collarless metal ceramic restoration is superior to that of a restoration with a metal margin, its mechanical strength has not been evaluated. Purpose The purpose of this study was to evaluate and compare the fracture resistance of metal ceramic restorations with metal margins to that of metal ceramic restorations with circumferential porcelain margins, after exposure to masticatory simulation. Material and methods Twenty-four metal ceramic restorations were fabricated and paired with 24 cobalt-chrome tooth analogs. Twelve of the specimens had metal margins, while the remainder had circumferential porcelain margins. The restorations were cemented on the metal tooth analogs with a resin-modified glass ionomer luting agent (FujiCEM). Al...

International Nuclear Information System (INIS)

Interest in making complex net-shape ceramic parts with good surface finishing and sharp tolerances without machining is a driving force for studying the injection molding technique. This method consists of softhening the ceramic material by means of adding some plastic and heating in order to inject the mixture under pressure into a relatively cold mold where solidification takes place. Essentially, it is the same process used in thermoplastic industry but, in the present case, the ceramic powder load ranges between 80 to 90 wt.%. This work shows results obtained from the fabrication of pieces of different ceramic materials (alumina, barium titanate ferrites, etc.) in a small scale, using equipments developed and constructed in the laboratory. (Author).

J-STORE (Japan)

Full Text Available

Energy Technology Data Exchange (ETDEWEB)

Resulting of the remarkably growth on economical development in each countries of Asia, ceramics low heat rejection engines are paid attention as a technique corresponding with the third oil shock which is presumed in near future. On the other hand, in order to construct the low heat rejection engines, using the quite different property materials from metals which called ceramics, it is necessary to determine design and combustion method fitted to the feature of this different kind materials. Though the development of ceramics low heat rejection engines have been given up in the world, recently, the development of ceramics engines is again required for the purpose of realizing an engine with low fuel consumption. Authors have successfully solved the problems, such as the disuse of cooling system, the improvement of combustion to reduce fuel consumption and exhaust emissions, and the realization of ...

International Nuclear Information System (INIS)

A suspension-firing type radioactive waste incineration system is developed and cold demonstration testing of ceramic filters for the system are carried out. The incineration system, which is useful for a wide variety of waste materials, can serve to simplify the facilities and to reduce the costs for waste disposal. The incineration system can be used for drying-processing of concentrated waste liquids and disposal of flame resistant materials including ion exchange resins and rubber, as well as for ordinary combustible solid materials. An on-line backwash system is adopted to allow the ceramic filters to operate stably for a long period of time. For one-step filtering using the ceramic filter, the decontamination factor is greater than 10"5 for the processing of various wastes. In a practical situation, there exist vapor produced by the spray drier and the cladding in used ion exchange resin, which act to increase the ...

Energy Technology Data Exchange (ETDEWEB)

This task within the EU R and D for ITER was aimed at the development of basic manufacturing solutions for the high heat flux plasma facing components such as the divertor targets, the baffles and limiters. More than 50 representative small-scale mock-ups have been manufactured with beryllium, carbon and tungsten armour using various joining technologies. High heat flux testing of 20 of these mock-ups showed the carbon mono-blocks to be the most robust solution, surviving 2000 cycles at absorbed heat fluxes of up to 24 MW m{sup -2}. With flat armour tiles rapid joint failures occurred at 5-16 MW m{sup -2} depending on joining technology and armour material. These test results serve as a basis for the selection of manufacturing options and materials for the prototypes now being ordered. (orig.) 11 refs.

Energy Technology Data Exchange (ETDEWEB)

For several decades most of the efforts to develop new scintillator materials have concentrated on high-light-yield inorganic single-crystals while polycrystalline ceramic scintillators, since their inception in the early 1980 s, have received relatively little attention. Nevertheless, transparent ceramics offer a promising approach to the fabrication of relatively inexpensive scintillators via a simple mechanical compaction and annealing process that eliminates single-crystal growth. Until recently, commonly accepted concepts restricted the polycrystalline ceramic approach to materials exhibiting a cubic crystal structure. Here, we report our results on the development of two novel ceramic scintillators based on the non-cubic crystalline materials: Lu SiO:Ce (LSO:Ce) and LaBr:Ce. While no evidence for texturing has been found in their ceramic microstructures, our LSO:Ce ...

International Nuclear Information System (INIS)

... ammonium compounds benzilic acid chemical preparation lanthanum oxides

Wastenet

...The system recognises the name and confirms it before it starts to dial. To stop the number being dialled say 'cancel'. If ...of the conference : Press the Recall 'R' button and listen for holding dial tone. Select extension or outside number of the person to ...who is going to join the conference Press Recall 'R' to receive dial tone and select '*' and '4'. The call is ...line is faulty and should be reported to the switchboard operators by dialling '0' and giving full details of the fault, the extension ...

DEFF Research Database (Denmark)

In 1995 the exercise RESUME-95 (Rapid Environmental Surveying Using Mobile Equipment) took place in Finland. Groups from 8 European countries joined the exercise. The methods used were airborne gamma-ray measurements, car-borne measurements and in situ stationary measurements. The results of the measurements are analyses aiming at disclosing similarities and differences between groups and measuring techniques.

International Nuclear Information System (INIS)

The design of the ITER primary first wall incorporates a multi-layered structure consisting of a layer of beryllium bonded to a layer of copper alloy with embedded stainless steel tubes which in turn is bonded to a stainless steel structure. In this configuration, the stainless steel provides structural support, the copper alloy improved resistance to high heat loads, and the beryllium layer a low Z metal interface with plasma. Fabrication, testing and control of this multi-layered structure, and indeed the entire blanket shield module, calls for advanced methods. Several associations in the four home teams and their industrial partners have been involved in various fabrication and joining tasks now grouped under L4 blanket project. In this paper, an overview of the work done so far for joining stainless steel to stainless steel, stainless steel to copper alloy, copper alloy to copper alloy, and copper alloy to beryllium is presented. ...

International Nuclear Information System (INIS)

A technique has been developed for joining a large calcium fluoride crystal to a stainless-steel flange by means of a silver transition ring. The process involves both vacuum brazing using a copper-silver alloy and air brazing using silver chloride. This paper describes the procedure used in fabricating a high-vacuum leak-tight calcium fluoride window assembly.

Energy Technology Data Exchange (ETDEWEB)

Out of the R and D of mesoscopic metal group composite materials, the paper described the fiscal 1997 results. In the in-situ method as a composite material making method, elucidated to some degree were chemical composition of Fe-C-Cr-V-Nb-Mo-W-Ni base multi-dimensional alloys, and wear resistance and oxidation resistance of MC type carbide dispersion multi-phase texture crystallizing as primary crystal and eutectic. In the composite material making with ceramic fiber and alloy by the pressure infiltration method, the paper clarified the texture formation mechanism in solidification/heat treatment by a combination of Al alloys and alumina long fiber, and the relation between fiber configuration and wear resistance. By MA and MG methods as the powder metallurgy composite material making method, a composed body of {alpha}-stainless steel of Fe-12%Cr composition and M23C6 of 40-90vol% are designed for alloy composition, and powder of amorphous or ...

International Nuclear Information System (INIS)

We have investigated the growth behaviors of high temperature compatible ZrO_2 insulation coatings on Ag and AgMg sheathed Bi_2Sr_2Ca_1Cu_2O_x superconducting tapes depending on number of dipping and thermal conditions. The coatings were fabricated on long-length superconducting tape substrates using a solution derived from Zr tetrabutoxide, solvent and chelating agent for high magnetic field magnets. The layer-on-layer growth behaviors were characterized by environmental scanning electron microscope (ESEM), energy dispersive spectroscopy (EDS), X-ray maps and X-ray diffraction (XRD). This research showed that the ZrO_2 coatings were regularly grown on Ag-based tape substrates and coating thickness increased with increasing number of dipping. It was found that ceramic oxides formed at temperature range 450 and 550 deg. C. The final coating thickness changed between 6 and 8 #mu#m after annealing process. Resistance of insulation measured from ...

Energy Technology Data Exchange (ETDEWEB)

One of the five projects selected for funding within the Clean Coal Technology Program is a project proposed by the Pennsylvania Electric Company (Penelec) of Johnstown, Pennsylvania. Penelec proposes to enter into a cooperative agreement with DOE to design, construct and operate a 600 ton-per-day, 66-megawatt (MWe), coal-fueled, externally-fired combined cycle (EFCC) electric power generation facility. The EFCC is an emerging technology with promise for operating highefficiency combined gas- and steam-turbine cycles on coal. The central feature of EFCC is its coupling of the gas turbine to an external, atmospheric-pressure, coal combustor via a hightemperature ceramic heat exchanger (CerHx{reg_sign}) developed by Hague International. The EFCC technology is attractive because, unlike competing combined cycles such as Integrated Gasification (IGCC) and Pressurized Fluidized Bed Combustion (PFBC), it eliminates the need for a costly gas cleanup system to protect the ...

Energy Technology Data Exchange (ETDEWEB)

The industrial policy of fine ceramics which is one of the new material expected to solve energy/environmental problem, is described. Fine ceramics are possessed with the characteristics like surpassing electromagnetic properties, heat resistance, high strength, etc. and its use as highly efficient power generation plant material, functional material for various sensors/electronic, and activation of existing industries are cited. As for the reclamation of global environment, promotion of saving energy in a global scale, development of innovative environmental technology and increase of carbon dioxide absorption source are described. Furthermore, research and development work in Japan on global environmental industrial technology for 1992 to 1993, new sunshine project and technical developments relating to fine ceramics are explained. As for the results of research and development, the results from the case study of 300kw ...

International Nuclear Information System (INIS)

Study results on long-term thermal and corrosion resistance of packs with electro-insulation layer of aluminium nitride are presented. Structural changes of nitride ceramics and contact zones between metal and ceramics are considered. It is shown that multilayer metallo-ceramic packs, manufactured by gas-phase technology have high electro- and thermophysical properties, high thermal and corrosion resistance relative to cesium vapor, vacuum density as well as high thermo-resistance. 8 refs., 4 figs.

International Nuclear Information System (INIS)

Technologic regimes of cryomotor rotor fabrication are determined. Blanks of yttrium ceramics powder are molded hydrostatically at 400-600 MPa. To confirm the serviceability of electric machines of the considered, a hysteretic 10 W power electric motor with the following dimensions of HTSC-ceramics rotor: external diameter - 56 mm; internal diameter - 45 mm, height - 60 mm, is developed and tested in the liquid nitrogen medium. 8 refs.; 8 figs.; 1 tab.

International Nuclear Information System (INIS)

Monolithic SiAlON ceramics are hard and brittle with little possibility for property design, but multi-phase SiAlON ceramics offer great scope for controlling microstructural development and desired properties. The ceramics can also be reinforced by separate additions of other hard, refractory compounds. The toughness in all these SiAlON composites can be increased by several mechanisms, and the best effect is reached if they are combined. When glassy phase is present, crack paths are affected by the strains caused by different thermal expansion of the glassy phase and the crystals and also by the interface properties. The crystal shape influence toughness, especially pronounced is the effect of the elongated #beta#- grains. Different toughening mechanisms are achieved by separately added reinforcement phases. The hardness is raised by the presence of #alpha# SiAlON and other hard constituents, such as SiC. (orig.).

British Library Electronic Table of Contents (United Kingdom)

The addition of ?-Sialon nanoparticles to lubricants in heavy-duty frictional joints is shown to be effective.

International Nuclear Information System (INIS)

Turkish English ... Authors Sahin, O. (Suleyman Demirel University, Department of Physics, Isparta (Turkey))

British Library Electronic Table of Contents (United Kingdom)

Objective.The interest of dental research in metal-free restorations has been rising in the last 20 years following the introduction of innovative all-ceramic materials in the daily practice. In particular, high strength ceramics and related CAD/CAM techniques have widely increased the clinical indications of metal-free prostheses, showing more favourable mechanical characteristics compared to the early ceramic materials.The purpose of the present paper is providing a brief review on the all-ceramic dental materials, evaluating pros and cons in the light of the most recent scientific results and of the authors? clinical experience.Materials. A structured review of the literature was given on the basis of medical and engineering papers published in the last decades on the use of dental cera...

Science.gov (United States)

... 1. Reeber, RR, Kusy, RP, Yu, N. and Chu, WK " Formation of a Solid Lubricant in Boron Carbide by Nitrogen Ion Implantation and Laser Annealing ...

Science.gov (United States)

Description of courses, curriculum and degree program. "Ceramic and materials engineers design, develop, and participate in the manufacture of both standard and new materials intended for use in a wide variety of industries with diverse applications. These range from the semi-conductor to the aerospace and finally to the traditional ceramics industry. The broad scope of industrial responsibilities handled by ceramic and materials engineers requires knowledge in mathematics, science, engineering, and the social sciences, skills in problem solving, engineering analysis, design, and written and oral communication. The baccalaureate program integrates laboratory with classroom experiences to prepare students for life-long learning. Courses covering thermodynamics, kinetics, mechanical behavior, processing and characterization of materials prepare students for careers in industry and/or for graduate school. Clemson University ...

Energy Technology Data Exchange (ETDEWEB)

A hydrous oxide film for the application as dielectric film is synthesized by immersion of pure aluminum in hot water. From a Rutherford backscattering analysis, the ratio of aluminum to oxygen atoms was found to be 3:2 in the anodized aluminum oxide film, and 2:1 in the hydrous oxide layer. Anodization of the hydrous oxide layer was more effective for the transition of amorphous anodic oxides to the crystalline aluminum oxides.

Energy Technology Data Exchange (ETDEWEB)

The diffusion of alkali vapours in the anode compartment of a DIR-MCFC produces the deactivation of the internal reforming catalyst. Sets of ceramic porous membranes purposed to limit the diffusion have been manufactured by different techniques and the influence of the preparation technique and of the preparative variables on the morphological characteristics of the membranes structures has been studied.

Energy Technology Data Exchange (ETDEWEB)

The peculiarities of pulsed laser melting and evaporation of the superconducting ceramics are analyzed by means of numerical simulation. The appearance of the overheated metastable states in solid and liquid phases is shown as a result of the phase front dynamics and volume nature of laser energy release. A method of dynamic adaptation for the multifront Stefan problem is proposed.

International Nuclear Information System (INIS)

Lead lanthanum zirconate titanate (PLZT) nanopowders with chemical compositions x/65/35 PLZT (x = 6 - 10 mol%) were prepared by sol-gel method. PLZT ceramics was obtained by the conventional sintering method and utilizing the hot pressing method. The investigations of dielectric and ferroelectric measurements of as obtained PLZT ceramics have revealed the influence of lanthanum concentration on the properties of PLZT electroceramics. (author)

Science.gov (United States)

Lead-free piezoelectric ceramics (1-x)K0.5Na0.5NbO3-xAgSbO3+0.75 mol % MnO2 were prepared by a conventional solid-state sintering technique, and the piezoelectric and dielectric properties of the ceramics were studied. The results of x-ray diffraction suggest that AgSbO3 diffuses into the K0.5Na0.5NbO3 lattices to form a new solid solution with a single-phase orthorhombic perovskite structure. After the addition of AgSbO3, the paraelectric cubic-ferroelectric tetragonal phase transition temperature (TC) and the ferroelectric tetragonal-ferroelectric orthorhombic phase transition temperature (TO-T) decrease, and the ceramics become ``softened,'' resulting in significant improvements in the ferroelectric and piezoelectric properties. The ceramics with x=0.03-0.10 exhibit excellent piezoelectric properties: d33=130-216 pC/N, kp=0.44-0.51, and kt=0.40-0.52. The ceramics also exhibit a ...

International Nuclear Information System (INIS)

For several decades, ceramic matrix composite have been attracted attention in advanced structural and tribological applications. Advanced structural ceramics are presently used in diverse tribological applications such as tips for ballpoint pens, precision instrument bearings and cutting tools inserts. Design and selection of ceramics for these applications require reliable data on the effects of temperature, load and environment on the tribological behavior of these ceramics. In the present work, #alpha#-sialon matrix composites reinforced with different amounts of #beta#-sialon fibers were produced with the aim of improving their toughness to increase the industrial applications. The wear properties of #alpha#-sialon matrix composites were evaluated by carried out wear tests using a pin-on-disk tribometer under dry conditions. The #alpha#-sialon matrix composites were manufactured by slip casting and ...

Energy Technology Data Exchange (ETDEWEB)

Sintered glass-ceramics were produced from coal fly ashes, red mud from aluminum production and silica fume. The capabilities of Tuncbilek fly ash and a mixture of Orhaneli fly ash, red mud and silica fume to be vitrified and devitrified by sintering process were investigated by means of scanning electron microscopy and X-ray diffraction analysis. To determine the effect of binder in the sintering technique, glass powders were pressed without or with the addition of polyvinyl alcohol. Owing to microstructural observations, density and hardness measurements, it can be said that physical properties and the hardness of the produced samples strongly depended on the crystallization degree of the samples. Toxicity characteristic leaching procedure test results showed that glass-ceramic samples produced by using sintering technique could be considered as nonhazardous materials. Chemical durability of the sintered glass-ceramic ...

International Nuclear Information System (INIS)

The authors observed an extremely high permittivity (#approx#35 000 at T_C) in barium zirconate titanate (BaZr_0_._1Ti_0_._9O_3) ceramics with holmium substitution (1-5 mol %) in Ba site. Careful microstructural investigation and energy dispersive spectroscopy analysis of the 1-2 mol % of Ho substituted ceramics showed the enrichment of a Ho-phase along the grain boundaries with a composition close to the Ho_2Ti_2O_7 pyrochlore. The formation of Ho rich phase resulted in the Maxwell-Wagner polarization mechanism, which leads to this unusually high permittivity. Ceramics with 3 mol % or higher Ho content showed lesser permittivity values compared to 1-2 mol %, probably due to the increase in pyrochlore phase. These high dielectric constant ceramics are useful in nanoscale devices.

International Nuclear Information System (INIS)

Dysprosium #alpha#-sialon ceramic has been fabricated from #alpha#-Si_3N_4, AlN, Al_2O_3 and Dy_2O_3 starting powders, using gas pressure sintering at 1800 deg C or higher temperatures under a relatively low gas pressure of 0.9MPa N_2. The resultant #alpha#-sialon grains showed significantly different features, such as equiaxed, elongated, and even a few extraordinarily large with high aspect ratio grains in the fine matrix, which has rarely been observed in #alpha#' ceramics. It is suggested that the temperature strongly influences the grain morphologies of #alpha#-sialon, playing an important role particularly in the latter stage of the 'nucleation-growth' process. Such a microstructural morphology of mixed with equiaxed and elongated grains toughens the #alpha#-sialon ceramics and leaves them still hard. Overly high temperature treatment leads to the preferential growth of a few #alpha#' grains which become excessively ...

British Library Electronic Table of Contents (United Kingdom)

A type of Si3N4-based nanocomposites ceramic cutting tool material was prepared by the addition of nano-scale Si3N4W whisker and nano-scale TiN particle. Cutting performance of the Si3N4/Si3N4W/TiN nanocomposite ceramic tool in machining of cast iron was investigated in comparison with a commercial sialon ceramic tool, and the tool wear mechanism was studied. The two types of cutting tools have similar cutting performance at relatively low cutting parameters, while Si3N4/Si3N4W/TiN nanocomposite tool exhibits a better wear resistance than sialon tool at the relatively high cutting parameters. The wear of sialon ceramic cutting tool is dominated by the plastic deformation, abrasive action, microcracking, pullout of grains and chemical action at the higher cutting parameters. The higher mech...

J-STORE (Japan)

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International Nuclear Information System (INIS)

Short communication.

Energy Technology Data Exchange (ETDEWEB)

Short communication

International Nuclear Information System (INIS)

Bi-U mixed oxides were synthesized by two methods and characterized by X-ray diffraction and X-ray photoelectron spectroscopy. The samples were tested for the catalytic oxidation of carbon monoxide by oxygen. A stepwise redox mechanism consistent with the kinetic results is proposed. (orig.).

Energy Technology Data Exchange (ETDEWEB)

As the three-year period FY93-FY96 ended, there were six senior investigators on the grant full-time: Bulgac, Henley, Miller, Savage, van Kolck and Wilets. This represents an increase of two members from the previous three-year period, achieved with only a two percent increase over the budget for FY90-FY93. In addition, the permanent staff of the Institute for Nuclear Theory (George Bertsch, Wick Haxton, and David Kaplan) continued to be intimately associated with our physics research efforts. Aurel Bulgac joined the Group in September, 1993 as an assistant professor, with promotion requested by the Department and College of Arts and Sciences by September, 1997. Martin Savage, who was at Carnegie-Mellon University, jointed the Physics Department in September, 1996. U. van Kolck continued as research assistant professor, and we were supporting one postdoctoral research associate, Vesteinn Thorssen, who joined us in September, 1995. Seven ...

International Science & Technology Center (ISTC)

Development of Method and Technical Project of the Plant for Thermo-Vacuum Desorption of Tritium Oxide (HTO) from the Environmental Samples

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

A method is proposed for the quantitative isolation of radiothallium in gas form from proton-bombarded lead of mass up to 20 g. The molten lead is kept at about 800 K in hydrofluoric-acid vapor (HF/H/sub 2/O approx. = 1) at a reduced pressure (less than or equal to4 Pa). We used 99.9% lead with the U-240 cyclotron at the Nuclear Research Institute, Academy of Sciences of the Ukrainian SSR, or the phasotron at the Join Nuclear Research Institute, which gave protons at 65 and 680 MeV correspondingly.

International Nuclear Information System (INIS)

Astatine conversed into cationic form is shown to form stable complex with diethylenetriaminpentacetic acid. Due to this complex astatine joins RN_2 type monoclonal antibodies. More favorable conditions to prepare astatine labelled antibodies are found. Chromatographical analysis and electromigration experiments have shown that astatine is strongly retained in in-vitro biomolecule. Astatine did not escape from the labelled antibodies even in case of urea effect on them. Immune activity of astatine labelled antibodies remained similar in 20 h. 28 refs., 4 figs.

International Nuclear Information System (INIS)

Results of an investigation of the weldability of compact hollow automobile parts are reported. The use of magnetically impelled arc butt (MIAB) welding for a piston rod (OD_22_mm x 2.2_mm thickness), a shock-absorber (OD 40 mm x 2.2 mm) and a torque rod (OD 34 mm x 6 mm) has been investigated. Metallographic examination and comprehensive mechanical testing has been conducted to demonstrate the effectiveness of the method for joining of these types of automobile components

CERN Document Server

CERN, DESY, Fermilab and SLAC have joined forces to build INSPIRE, the next-generation HEP information platform offering innovative tools for information discovery and communication. Representing a natural community-based evolution of SPIRES, INSPIRE provides fast access to the entire body of HEP literature. As a subject repository it will host fulltexts of preprints, Open Access journal articles and supplementary material like conference slides and multimedia, enabling novel text- and data mining applications. In the spirit of Web2.0 INSPIRE will also supply tools for collaboration and user-enriched content.

CERN Document Server

In key management schemes that realize secure multicast communications encrypted by group keys on a public network, tree structures are often used to update the group keys efficiently. Selcuk and Sidhu have proposed an efficient scheme which updates dynamically the tree structures based on the withdrawal probabilities of members. In this paper, it is shown that Selcuk-Sidhu scheme is asymptotically optimal for the cost of withdrawal. Furthermore, a new key management scheme, which takes account of key update costs of joining in addition to withdrawal, is proposed. It is proved that the proposed scheme is also asymptotically optimal, and it is shown by simulation that it can attain good performance for nonasymptotic cases.

Energy Technology Data Exchange (ETDEWEB)

Chemical oxidation is a treatment technology that uses powertul chemical oxidizers to destroy organic contaminants. Typical oxidizers used in chemical oxidation processes include ozone, hydrogen peroxide, chlorine, and potassium permanganate. The chemical reaction products are usually simple organic compounds, such as carboxylic acids, and/or inorganic compounds, such as carbon dioxide, water, and simple inorganic complexes (e.g., chloride salts, in the case of chemical oxidation treatment of chlorinated solvents).

Energy Technology Data Exchange (ETDEWEB)

This work reports an alternative methodology for the linear attenuation coefficient determination ({mu} {rho}) of irregular form samples, in such a way that is not necessary to consider the sample thickness. With this methodology, indigenous archaeological ceramics fragments from the region of Londrina, north of Parana, were studied. These ceramics fragments belong to the Kaingaing and Tupiguarani traditions. The equation for the {mu} {rho} determination employing the two mean method was obtained and it was used for {mu} {rho} determination by the gamma ray beam attenuation if immersed ceramics, by turns, in two different means with known linear attenuation coefficient. By the other side, {mu} theoretical value was determined with the XCOM computer code. This code uses as input the ceramics chemistry composition and provides an energy versus mass attenuation coefficient table. In order to validate the ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this investigation was to simulate a machining front from an abrasive waterjet and its movements in a ceramic material. Wear factors affecting the abrasive waterjet nozzle were also to be established. Therefore, a low inclination angle (9[degree]) was used between the nozzle and test sample, simulating a moving machine front. A standard nozzle with an inner diameter of 0.76 mm was used in the test, and it was placed close to the samples. The outer diameter of the abrasive nozzle was 9.5 mm. The high wear rate from abrasive waterjets makes it possible to machine hard ceramics-including dense alumina, titanium boride, silicon nitride, and composites-at high machining speeds.

British Library Electronic Table of Contents (United Kingdom)

The design of solid breeder blankets is strongly affected by the low values of thermal conductivity and density of ceramic breeder pebble beds. A significant rise of both quantities would enhance the thermal performance and lead to an increased tritium breeding ratio. In order to improve these quantities pretreated lithium orthosilicate pebble material was dry pressed and subsequently sintered. The thermal conductivity of cylindrical pellets was determined by the heat pulse method using a laser flash device. A pebble bed characteristic sample was also investigated in order to check the measurement accuracy in comparison with previous results. Furthermore, two samples of low density cellular ceramics were also prepared by infiltration of polymer foams with a ceramic slurry. The thermal cond...

International Nuclear Information System (INIS)

The small pilot facility of a cyclone type suspension incineration system of radioactive waste was set up in order to evaluate the decontamination efficiency of a high efficiency ceramic filter. The evaluation was made by use of "5"4Mn, "5"9Fe, "6"0Co, "6"5Zn and "1"3"7Cs. 1. The decontamination factor by one line of ceramic filter for every species were over 10"5. 2. The decontamination factor increased by one oder when water vapor exists in off-gas. The same tendency was also observed when iron dioxide existed at the incineration of cation exchange resin. (author).

British Library Electronic Table of Contents (United Kingdom)

Objectives: The aim of this study was to evaluate the in vitro behaviour of all-ceramic zirconia molar crowns in regard to different core designs and marginal fit. Methods: Identically shaped methacrylate molars were prepared according to the ceramic restoration directives resulting in a 1-mm deep circular shoulder preparation. They were embedded in polymethylmethacrylate resin after covering their roots with a polyether layer to simulate periodontal mobility. The crown cores were made of yttria-stabilized zirconia veneered with a corresponding veneering ceramic. The crowns were divided into 5 groups (n=8) which differed in core design and cement gap thickness: #1: simple core, 40mm cement; #2: core with minimal occlusal support, 40mm cement; #3: core with optimized cusp support, 40mm ceme...

Energy Technology Data Exchange (ETDEWEB)

Sintered glass-ceramics have been produced using municipal incinerator solid residues and glass cullet or an inert waste, from feldspars processing, as sintering aids. The capability of three different mixtures, either previously vitrified or not, to be sintered was investigated by means of linear shrinkage, water absorption and bulk density measurements, and by X-ray diffraction analysis and scanning electron microscopy observations. Particular attention has been addressed to the study of particle size effect on the sintering process. The conclusions that can be drawn from the experimental study are that the preliminary vitrification step is essential in order to obtain a dense sintered glass-ceramic product in the 850-1050 C temperature range developing silicate crystalline phases. The optimal powder particle size that confers a good densification degree was found to be < 45 {mu}m. (orig.)

International Nuclear Information System (INIS)

BaTi_0_._9(Ni_1_/_2W_1_/_2)_0_._1O_3 ceramics were fabricated and their dielectric properties were investigated. With the sintering temperature increasing from 1250 to 1280 deg. C, the grain size abruptly increases from 1-2 to 20-40 #mu#m, accompanying significant changes in dielectric response. The samples with larger grains exhibit giant dielectric constant characteristics, which are considered to be mainly attributed to the domain boundary effect. The activation energies of the dielectric relaxation E_r_e_l_a_x=0.325 eV reveal the existence of microdomains in larger grains. The ac conductivity results also give the evidence of the domain boundary effect in the present ceramics.

International Nuclear Information System (INIS)

The formation of a porous coating is the decisive feature for the bio-compatibility of silica-free calcium phosphate glass ceramics on alloy surfaces like the #beta#-Ti structured Ti-29Nb-13Ta-4.6Zr used in this work. The ceramic composition is highly important: 50CaO-40P_2O_5-7Na_2O-3TiO_2 glass powder produces a pore-free coating unable to bind hydroxyapatite, whereas 60CaO-30P_2O_5-7Na_2O-3TiO_2 glass incorporates pores from which a crystalline hydroxyapatite phase can grow over the surface from simulated body fluid (see Figure). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

Energy Technology Data Exchange (ETDEWEB)

The properties of cast basalt and alumina are examined. The ways in which these materials have been used in applications in coal preparation plants, for example in bunker and pipe linings where abrasion and corrosion resistant materials are required, are discussed.

International Nuclear Information System (INIS)

Sodium silicate is vacuum impregnated in bauxite waste (red mud) at room temperature to develop ceramics of mechanical properties comparable to the sintered ceramics. For a concentration up to 10% the fracture toughness increases from 0.12 MNm"-"3"/"2 to 0.9 MNm"-"3"/"2, and the compressive strength from 7 MNm"-"2 to 30 MNm"-"2. The mechanical properties do not deteriorate, when soaked in water for an entire week. The viscosity and the concentration of the silicate solution are crucial, both for the success of the fabrication and the economics of the process. Similar successful results have been obtained for bauxite and lime stone, even though the latter has poor weathering properties. With scanning electron microscopy and energy dispersive analysis, an attempt is made to identify the crystals formed in the composite, which are responsible for the strength. The process is an economic alternative to the sintered ceramics in ...

Energy Technology Data Exchange (ETDEWEB)

The development of turbine components for the automotive 100 kW ceramic gas turbine has entered the final stage of the seven-year project and is making satisfactory progress, toward the goals. The authors attained the interim targets of the aerodynamic performances and have been carrying out tests to further improve efficiency. As for ceramic parts, they have changed the material of the turbine rotor to a new one that is excellent in long-sustained and high-temperature strength properties, and have confirmed substantial strength at high temperature through hot-spin tests. After evaluating blade-vibration stress through analyses and experiments, the authors completed an endurance evaluation at 1200 C (1473 K) TIT (Turbine Inlet Gas Temperature) and a rated speed of 100,000 rpm. The authors are now carrying out endurance tests at 1350 C (1623 K) TIT. For ceramic stationary parts, they already finished the evaluations at 1200 ...

UK PubMed Central (United Kingdom)

BackgroundThe successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics,...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

A neutron irradiation test on superplastic ceramic materials at high temperature has been proposed as an innovative basic research on high-temperature engineering using the High Temperature Engineering Test Reactor (HTTR). We investigated mechanical properties, such as the hardness and Young's modulus, of ceramic specimens after superplastic deformation. The tested material was 3Y-TZP (3mol% Yttria stabilized Tetragonal Zirconia Polycrystal) which is one of the representative superplastic ceramics. The properties were measured by a microindentation method. We also studied the relationship between crystal microstructures and the mechanical properties of deformed 3Y-TZP by scanning electron microscope (SEM). The indentation test showed that the mechanical properties of the specimens were reduced to about 1/2 by 30% deformation and to about 1/4 by 150% deformation. The SEM images showed that average grain size and ...

Energy Technology Data Exchange (ETDEWEB)

Externally Fired Combined Cycles (EFCCs) can increase the amount of electricity produced from ash bearing fuels up to 40%, with overall powerplant efficiencies in excess of 45%. Achieving such high efficiencies requires high temperature-high pressure air heaters capable of driving modern gas turbines from gas streams containing the products of coal combustion. A pilot plant has been constructed in Kennebunk, Maine to provide proof of concept and evaluation of system components. Tests using pulverized Western Pennsylvania bituminous coal have been carried out since April, 1995. The ceramic air heater extracts energy from the products of coal combustion to power a gas turbine. This air heater has operated at gas inlet temperatures over 1,095 C and pressures over 7.0 atm without damage to the ceramic tube string components. Stable gas turbine operation has been achieved with energy input from the air heater and a supplementary gas fired combustor. ...

Energy Technology Data Exchange (ETDEWEB)

A room-temperature process for stabilizing mineral waste streams has been developed, based on acid-base reaction between MgO and H3PO4 or acid phosphate solution. The resulting waste form sets into a hard ceramic in a few hours. In this way, various alumina industry wastes, such as red mud and treated potliner waste, can be solidified into ceramics which can be used as structural materials in waste management and construction industry. Red mud ceramics made by this process were low-porosity materials ({approx}2 vol%) with a compression strength equal to portland cement concrete (4944 psi). Bonding mechanism appears to be result of reactions of boehmite, goethite, and bayerite with the acid solution, and also encapsulation of red mud particles in Mg phosphate matrix. Possible applications include liners for ponds and thickned tailings disposal, dikes for waste ponds, and grouts. Compatability problems arising at the ...

Energy Technology Data Exchange (ETDEWEB)

This report covers the test methods and equipment for testing aircraft armor both hard and soft. The hard armor are the typical ceramic type while the soft armor are various types of layered composite materials. 10 figs. (JEF)

Energy Technology Data Exchange (ETDEWEB)

The electrochemical oxidation as a method to destroy drug residues like Aspirin {sup trademark}, tetracycline or gentamicin in water was investigated with C-Anode (modified by manganese oxides) and Pt Anode. The mechanism of Aspirin {sup trademark} and tetracycline oxidation and the influence of the biocide effect was observed using GC-MS and three different microbiological tests. In general the biological availability increases with progressive oxidation of the antibiotics. (orig.)

International Nuclear Information System (INIS)

Sialons are phases in the Si-Al-O-N and M-Si-Al-O-N systems where M includes Li, Mg, Ca, Sc, Y and the rare earth elements. They are comparable in variety with the mineral silicates and are built up of one-, two-, and three-dimensional arrangements of (Si,Al)(O,N)/sub 4/ tetrahedra in the same way that the structural units of the silicates are SiO/sub 4/ tetrahedra. These new materials include N-containing ceramics, glasses and glass-ceramics that are being explored for their thermal, chemical and physical properties.

British Library Electronic Table of Contents (United Kingdom)

Purpose - This paper aims to describe the technology and applications of nanocomposite materials. Design/methodology/approach - This paper discusses products, applications and technological developments in polymer, ceramic and metal nanocomposites. It concludes with a brief consideration of electronic component applications. Findings - It is shown that polymer nanocomposites and the materials used in their production are commercially available and finding applications in several industries, including automotive, military, food, electronics and leisure, due to their enhanced mechanical, electrical and thermal properties. Ceramic and metallic nanocomposites are at an earlier stage of development and a critical issue to resolve is optimising the dispersion of nanomaterials in the matrices. Pa...

International Nuclear Information System (INIS)

(Pb_1_-_x La_x) (Zr_0_._6_5 Ti_0_._3_5) ceramics, with x = 0.09 (PLZT 9/65/35) were prepared using lead monoxide (Pb O) with different amount of litharge (tetragonal) and massicot (orthorhombic) phases. Results, based on x-ray diffraction patterns, remanent polarization and dielectric measurements, show that the Pb O polymorphic phase does not change the final structure of the PLZT but causes changes on the remanent polarization and dielectric permittivity temperature dependence. (author). 11 refs, 2 figs, 2 tabs.

Energy Technology Data Exchange (ETDEWEB)

The objective of this contract is to research, develop and demonstrate a novel ceramic membrane reactor system for the low-cost conversion of natural gas to synthesis gas and hydrogen for liquid transportation fuels: the ITM Syngas process. Through an eight-year, three-phase program, the technology will be developed and scaled up to obtain the technical, engineering, operating and economic data necessary for the final step to full commercialization of the Gas-to-Liquids (GTL) conversion technology. This report is a summary of activities through February 1999.

Energy Technology Data Exchange (ETDEWEB)

Here we report detailed dielectric studies carried out on a Barium strontium titanate (BST) (95:5) composition. The material was synthesized by conventional ceramic method and microwave processing, and the later technique resulted in material with high density, improved microstructure and dielectric properties. The dielectric properties were studied as a function of frequency and temperature and well-defined ferroelectric behavior of first order transition was observed. It follows Curie-Weiss law above transition temperature (paraelectric region). Curie temperature is slightly higher for microwave sintered (MS) material.

Energy Technology Data Exchange (ETDEWEB)

The Externally-Fired Combined Cycle (EFCC) offers a method for operating high-efficiency gas and steam turbine combined cycles on coal. In the EFCC, an air heater replaces the gas turbine combustor so that the turbine can be indirectly fired. Ceramic materials are required for the heat exchange surfaces to accommodate the operating temperatures of modern gas turbines. The ceramic air heater or heat exchanger is the focus of this program, and the two primary objectives are (1) to demonstrate that a ceramic air heater can be reliably pressurized to a level of 225 psia (1.5 MPa); and (2) to show that the air heater can withstand exposure to the products of coal combustion at elevated temperatures. By replacing the gas turbine combustor with a ceramic air heater, the cycle can use coal or other ash-bearing fuels. Numerous programs have attempted to fuel high efficiency gas turbines directly with coal, often ...

International Nuclear Information System (INIS)

Engineering ceramics have excellent properties such as high strength, high hardness and high heat resistance compared with metallic materials. To apply the ceramic in fast reactor environment, it is necessary to evaluate the sodium compatibility and the influence of sodium on the mechanical properties of ceramics. In this study, the influence of high temperature sodium on the mechanical properties of sintered ceramics of conventional and high purity Al_2O_3, SiC, SiAlON, AlN and unidirectional solidified ceramics of Al_2O_3/YAG eutectic composite were investigated by means of flexure tests. Test specimens were exposed in liquid sodium at 823K and 923K for 3.6Ms. There were no changes in the flexural strength of the conventional and high purity Al_2O_3, AlN and Al_2O_3/YAG eutectic composite after the sodium exposure at 823K. On the contrary, the decrease in the flexural strength was ...

UK PubMed Central (United Kingdom)

Background. The Free Radical Theory of Aging mechanistically links oxidative stress to aging. Okinawa has among the world's longest-lived populations but oxidative stress in this...Full Text Available

UK PubMed Central (United Kingdom)

1. Nitric oxide generation is important in the regulation of resistance vessel tone. Until now, however, there has been no evidence of such a role for basal generation of nitric oxide in the skin microcirculation...Full Text Available

UK PubMed Central (United Kingdom)

Studies were conducted to quantitate the evolution of nitrogen oxides (NO_(x)) from soybean [Glycine max (L.) Merr.] leaves during in vivo nitrate reductase...Full Text Available

UK PubMed Central (United Kingdom)

The potential for oxidation of ammonia in anoxic marine sediments exists through anaerobic oxidation by Nitrosomonas-like organisms, utilizing nitrogen dioxide, coupling of nitrification,...Full Text Available

Energy Technology Data Exchange (ETDEWEB)

The theoretical principles underlying the formation of oxide and, in particular, anodic oxide coatings on metals produced by chemical oxidation, anodizing in solutions, and anodizing in cold plasmas are reviewed. The mechanisms and conditions of anodic oxidation are described, and the structure of anodic oxide coatings on aluminum, magnesium, beryllium, zinc, cadmium, iron, cobalt, nickel, titanium, zirconium, tantalum, and chromium alloys is examined. Attention is also given to various applictins of anodized coatings. 54 references.

Science.gov (United States)

The growth of an oxide interfacial layer was recently found to increase the open-circuit voltage (OCV) and efficiency by up to 60 per cent in GaAs metal-semiconductor solar cells. Details of oxidation techniques to provide the necessary oxide thickness and chemical structure and using ozone, water-vapor-saturated oxygen, or oxygen gas discharges are described, as well as apparent crystallographic orientation effects. Preliminary results of the oxide chemistry obtained from X-ray, photoelectron spectroscopy are given. Ratios of arsenic oxide to gallium oxide of unity or less seem to be preferable. Samples with the highest OVC predominantly have As(+3) in the arsenic oxide rather than As(+5). A major difficulty at this time is a reduction in OCV by 100-200 mV when the antireflection coating is vacuum deposited.

UK PubMed Central (United Kingdom)

PurposeCataracts are often considered to be an unavoidable consequence of aging. Oxidative damage is a major cause or consequence of cortical and nuclear cataracts, the most common...Full Text Available

Science.gov (United States)

Metastable yttrium-oxide films are synthesized using reactive sputter deposition. The yttrium concentration of the as-deposited film is found to vary as a function of the sputter deposition rate. In addition to the synthesis of the cubic equilibrium phase...

Energy Technology Data Exchange (ETDEWEB)

This patent describes a catalyst composition. It consists of the catalytic oxides of iron, bismuth, molybdenum and magnesium as essential components and optionally the oxides of cobalt, nickel, phosphorus and arsenic.

Science.gov (United States)

May 31, 2011 ... A Theoretical Solid Oxide Fuel Cell Model for System Controls and Stability Design AUTHOR(S): Kopasakis, George; Brinson, Thomas; Credle, ...

International Nuclear Information System (INIS)

This paper provides a brief overview of the young, but rapidly growing field of spintronics. Its primary objective is to explain how as electrons tunnel through simple insulators such as MgO, wavefunctions of certain symmetries are preferentially transmitted. This symmetry filtering property can be converted into a spin-filtering property if the insulator is joined epitaxially to a ferromagnetic electrode with the same two-dimensional symmetry parallel to the interface. A second requirement of the ferromagnetic electrodes is that a wavefunction with the preferred symmetry exists in one of the two spin channels but not in the other. These requirements are satisfied for electrons traveling perpendicular to the interface for Fe-MgO-Fe tunnel barriers. This leads to a large change in the resistance when the magnetic moment of one of the electrodes is rotated relative to those of the other electrode. This large tunneling magnetoresistance effect is being used as the ...

International Nuclear Information System (INIS)

Test Blanket Modules (TBM) will be tested in ITER to verify the capability of tritium breeding and recovery and the extraction of thermal energy suitable for the production of electricity. A Helium Cooled Solid Breeder (HCSB) TBM has been developed in Korea to accomplish these goals. Reduced Activation Ferritic/Martensitic (RAFM) steel has been chosen as the primary candidate structural material for Korean TBM. Due to the complexity of the First wall (FW) and Side wall (SW), it is necessary to develop various joining technologies, such as Hot Isostatic Pressing (HIP), Electron Beam Welding (EBW) and Tungsten Inert Gas (TIG) welding, for the successful fabrication of TBM. In this study, the mechanical properties of TIG welded RAFM steel were investigated. Various mechanical tests of TIG-welded RAFM steel were performed to obtain the optimized TIG welding process for RAFM steel

Energy Technology Data Exchange (ETDEWEB)

The majority of Brazilian big cities served by conventional railroad systems with routes starting in the center of the URBIS, destinate them the long distances transport of passengers and cargo. Actually, these systems are being transformed to become commuter trains which join a great capacity of transportation to a much lower costs of implantation than subway ones. The most important characteristic of this train, when talking about energy consumption, is the possibility of using different kinds of explosion engines from three cycles: Diesel, mixed (Diesel + Natural Gas), and Otto moved by natural gas, besides the traditional electric traction. The use of natural gas in Otto cycle engines shows itself competitive from the point of view of investments, operational costs and environmental preservation. (author). 10 refs., 1 fig

Energy Technology Data Exchange (ETDEWEB)

Considering beryllium as plasma facing armour this paper presents recent results obtained in Russia. A special process of joining beryllium to a Cu-alloy material structure is described and recent results of thermal cycling tests of such joints are presented. Summarizing the results, the authors show that a Cu-alloy heat sink structure armoured with beryllium can survive high heat fluxes ({>=}10 MW/m{sup 2}) during 1000 heating/cooling cycles without serious damage to the armour material and its joint. The principal feasibility of thermal cycling of beryllium grades and their joints directly in the core of a nuclear reactor is demonstrated and the main results of this test are presented. The paper also describes the thermal cycling of different beryllium grades having cracks initiated by previously applied high heat loads simulating plasma disruptions. (orig.)

Energy Technology Data Exchange (ETDEWEB)

An idea whose time has come takes center stage in London this week when BP Chemicals announces details of a consortium of chemical companies joining it in a new recycling project. In the project, which BP has been working on since 1989, waste plastic will be depolymerized to chemical feedstocks, via technology variously called feedstock or chemical recycling, polymer cracking, or tertiary recycling. BP's effort is one of the first to emerge from the research and pilot-plant stages that are committed to actual feedstock recycling of mixed polyolefins and other plastics. But it is only one of the many industry efforts under way to cope with the job of dealing with postconsumer plastics.

Science.gov (United States)

9 9 simulated Purex waste oxides was investigated as a function of Na/sub 2/O, CaO and P/sub 2/O/sub 5/ content. All compositions lost some sulfate at 50 to 100 deg C above the softening point. In generai the volatility decreased with increase of either Na/ sub 2/O or CaO relative to P/sub 2/O/sub 5/, but no simple correlation Was indicated. Softening temperatures were lowered by inc ease in Na/sub 2/O vs CaO. Ceramic solids were obtained but no true glasses. Attempts to produce glasses by addition of varying combinations of Al/sub 2/O/sub 3/, PbO, BaO, and B/sub 2/O/ sub 3/ to simulated Pure x waste plus phosphite were unsuccessful. The use of 0.005 M Na/sub 2/C/O/sub 3/ to precipitate calcium from wastes containing up to 3 ppm of phosphate was demonstrated in four pilot plant runs and produced a decrease in the hardness of the waste leaving the clarifier. An inadvertent Sr/ sup 90/ and Cs/sup 137/ breakthrough ...

Energy Technology Data Exchange (ETDEWEB)

Red mud is a waste product of the aluminium refining industry. It is composed of aluminium hydroxide and iron oxide. This study examined the feasibility of using red mud as a catalyst to eliminate volatile organic compounds in atmospheric pollutants. Volatile organic compounds can be eliminated by thermal oxidation between 600 and 1100 degrees C. However, the oxidation of volatile organic compounds can also be accomplished at lower temperatures (200 to 450 degrees C) if a catalyst is present. Currently, the low temperature destruction of volatile organic compounds is not widespread because of the difficulty in deactivating the catalyst. In this study, red mud was calcined in air at 500 degrees C. Under such conditions, the red mud converts to aluminium oxide and iron oxide. These 2 oxides are active and are carbon dioxide selective in the ...

International Nuclear Information System (INIS)

Lithium Ceramics offer tremendous potential as a source for the production of tritium ("3H) for fusion power reactors. Their successful application will depend to a great extent upon the diffusion properties of the "6Li within the matrix. Consequently knowledge of "6Li concentration gradients in the ceramic matrices is an important requirement in the continued development of the technology. In this investigation, the neutron depth profile (NDP) technique has been applied to the study of concentration profiles of "6Li in lithium aluminate ceramics, doped with 1.8%, 50% and 95% "6Li isotopic concentrations. Specimen for analysis were prepared at Battelle (PNL) as pellet discs. Samples for diffusion studies were arranged as diffusion couples in the following manner: 1.8% "6Li discs/85% "6Li powder. Experiments were performed at the Texas A and M Nuclear Science Center Reactor Building, utilizing 1 MW equivalent thermal neutron ...

KoreaScience (Korea)

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KoreaScience (Korea)

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KoreaScience (Korea)

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Czech Academy of Sciences Repository

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Science.gov (United States)

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International Nuclear Information System (INIS)

On the basis of experimental and extrapolated values the physico-chemical properties of astatine are reviewed considering all oxidation states.

International Nuclear Information System (INIS)

The influence of MeV electrons irradiation on the gate oxide layers of hydrogenated polysilicon thin film transistors (TFTs) was investigated by measuring gate leakage currents and threshold voltages. The experimental data revealed a decrease of oxide trap density and increase of positive oxide charge. Improvement in the interface roughness and in the oxide quality near the bottom interface was observed.

KoreaScience (Korea)

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Energy Technology Data Exchange (ETDEWEB)

We report on the fouling of Focused Ion Beam (FIB)-fabricated silicon oxide nanopores after exposure to tap water for two weeks. Pore clogging was monitored by Scanning Electron Microscopy (SEM) on both bare silicon oxide and chemically functionalized nanopores. While fouling occurred on hydrophilic silicon oxide pore walls, the hydrophobic nature of alkane chains prevented clogging on the chemically functionalized pore walls. These results have implications for nanopore sensing platform design.

KoreaScience (Korea)

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KoreaScience (Korea)

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DEFF Research Database (Denmark)

ATPase, endoplasmic reticulum, calcium, ischaemia