WorldWideScience

Sample records for nonoxide ceramic interactions

  1. Environmental Effects on Non-oxide Ceramics

    Science.gov (United States)

    Jacobson, Nathan S.; Opila, Elizabeth J.

    1997-01-01

    Non-oxide ceramics such as silicon carbide (SiC) and silicon nitride (Si3N4) are promising materials for a wide range of high temperature applications. These include such diverse applications as components for heat engines, high temperature electronics, and re-entry shields for space vehicles. Table I lists a number of selected applications. Most of the emphasis here will be on SiC and Si3N4. Where appropriate, other non-oxide materials such as aluminum nitride (AlN) and boron nitride (BN) will be discussed. Proposed materials include both monolithic ceramics and composites. Composites are treated in more detail elsewhere in this volume, however, many of the oxidation/corrosion reactions discussed here can be extended to composites. In application these materials will be exposed to a wide variety of environments. Table I also lists reactive components of these environments.It is well-known that SiC and Si3N4 retain their strength to high temperatures. Thus these materials have been proposed for a variety of hot-gas-path components in combustion applications. These include heat exchanger tubes, combustor liners, and porous filters for coal combustion products. All combustion gases contain CO2, CO, H2, H2O, O2, and N2. The exact gas composition is dependent on the fuel to air ratio or equivalence ratio. (Equivalence ratio (EQ) is a fuel-to-air ratio, with total hydrocarbon content normalized to the amount of O2 and defined by EQ=1 for complete combustion to CO2 and H2O). Figure 1 is a plot of equilibrium gas composition vs. equivalence ratio. Note that as a general rule, all combustion atmospheres are about 10% water vapor and 10% CO2. The amounts of CO, H2, and O2 are highly dependent on equivalence ratio.

  2. Polymer derived non-oxide ceramics modified with late transition metals.

    Science.gov (United States)

    Zaheer, Muhammad; Schmalz, Thomas; Motz, Günter; Kempe, Rhett

    2012-08-07

    This tutorial review highlights the methods for the preparation of metal modified precursor derived ceramics (PDCs) and concentrates on the rare non-oxide systems enhanced with late transition metals. In addition to the main synthetic strategies for modified SiC and SiCN ceramics, an overview of the morphologies, structures and compositions of both, ceramic materials and metal (nano) particles, is presented. Potential magnetic and catalytic applications have been discussed for the so manufactured metal containing non-oxide ceramics.

  3. Droplet size prediction in ultrasonic nebulization for non-oxide ceramic powder synthesis.

    Science.gov (United States)

    Muñoz, Mariana; Goutier, Simon; Foucaud, Sylvie; Mariaux, Gilles; Poirier, Thierry

    2018-03-01

    Spray pyrolysis process has been used for the synthesis of non-oxide ceramic powders from liquid precursors in the Si/C/N system. Particles with a high thermal stability and with variable composition and size distribution have been obtained. In this process, the mechanisms involved in precursor decomposition and gas phase recombination of species are still unknown. The final aim of this work consists in improving the whole process comprehension by an experimental/modelling approach that helps to connect the synthesized particles characteristics to the precursor properties and process operating parameters. It includes the following steps: aerosol formation by a piezoelectric nebulizer, its transport and the chemical-physical phenomena involved in the reaction processes. This paper focuses on the aerosol characterization to understand the relationship between the liquid precursor properties and the liquid droplet diameter distribution. Liquids with properties close to the precursor of interest (hexamethyldisilazane) have been used. Experiments have been performed using a shadowgraphy technique to determine the drop size distribution of the aerosol. For all operating parameters of the nebulizer device and liquids used, bimodal droplet size distributions have been obtained. Correlations proposed in the literature for the droplet size prediction by ultrasonic nebulization were used and adapted to the specific nebulizer device used in this study, showing rather good agreement with experimental values. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Laser beam joining of non-oxidic ceramics for ultra high temperature resistant joints

    International Nuclear Information System (INIS)

    Lippmann, W.; Knorr, J.; Wolf, R.; Reinecke, A.M.; Rasper, R.

    2004-01-01

    The excellent technical properties of silicon carbide (SiC) and silicon nitride (Si 3 N 4 ) ceramics, such as resistance to extreme temperatures, oxidation, mechanical wear, aggressive chemical substances and radioactive radiation and also its high thermal conductivity and good temperature-shock resistance, make these ceramics ideally suited for use in the field of nuclear technology. However, their practical use has been limited so far because of the unavailability of effective joining techniques for these ceramics, especially for high temperature applications. A new joining technology (CERALINK registered ) has been developed in a network project which allowed high temperature resistant and vacuum-tight joining of SiC or Si 3 N 4 ceramics. A power laser is used as heat source, which makes it possible to join ceramic components in free atmosphere in combination with a pure oxidic braze filler. As no furnace is necessary, there are no limitations on the component dimensions by the furnace-geometry. During the joining process, the heated area can be limited to the seam area so that this technology can also be used to encapsulate materials with a low melting point. The seam has a high mechanical strength, it is resistant to a wide range of chemicals and radiation and it is also vacuum-tight. The temperature resistance can be varied by variation of the braze filler composition - usually between 1,400 C and >1,600 C. Beside the optimum filler it is also important to select the suitable laser wavelength. The paper will demonstrate the influence of different wave lengths, i. e. various laser types, on the seam quality. Examples are chosen to illustrate the strengths and limitations of the new technology

  5. Processing of non-oxide ceramics from sol-gel methods

    Science.gov (United States)

    Landingham, Richard; Reibold, Robert A.; Satcher, Joe

    2014-12-12

    A general procedure applied to a variety of sol-gel precursors and solvent systems for preparing and controlling homogeneous dispersions of very small particles within each other. Fine homogenous dispersions processed at elevated temperatures and controlled atmospheres make a ceramic powder to be consolidated into a component by standard commercial means: sinter, hot press, hot isostatic pressing (HIP), hot/cold extrusion, spark plasma sinter (SPS), etc.

  6. A novel processing approach for free-standing porous non-oxide ceramic supports from polycarbosilane and polysilazane precursors

    OpenAIRE

    Konegger, Thomas; Patidar, Rajesh; Bordia, Rajendra K.

    2015-01-01

    In this contribution, a low-pressure/low-temperature casting technique for the preparation of novel free-standing macrocellular polymer-derived ceramic support structures is presented. Preceramic polymers (polycarbosilane and poly(vinyl)silazane) are combined with sacrificial porogens (ultra-high molecular weight polyethylene microbeads) to yield porous ceramic materials in the Si?C or Si?C?N systems, exhibiting well-defined pore structures after thermal conversion. The planar-disc-type speci...

  7. A novel processing approach for free-standing porous non-oxide ceramic supports from polycarbosilane and polysilazane precursors.

    Science.gov (United States)

    Konegger, Thomas; Patidar, Rajesh; Bordia, Rajendra K

    2015-09-01

    In this contribution, a low-pressure/low-temperature casting technique for the preparation of novel free-standing macrocellular polymer-derived ceramic support structures is presented. Preceramic polymers (polycarbosilane and poly(vinyl)silazane) are combined with sacrificial porogens (ultra-high molecular weight polyethylene microbeads) to yield porous ceramic materials in the Si-C or Si-C-N systems, exhibiting well-defined pore structures after thermal conversion. The planar-disc-type specimens were found to exhibit biaxial flexural strengths of up to 60 MPa. In combination with their observed permeability characteristics, the prepared structures were found to be suitable for potential applications in filtration, catalysis, or membrane science.

  8. Effect of Prior Exposure at Elevated Temperatures on Tensile Properties and Stress-Strain Behavior of Four Non-Oxide Ceramic Matrix Composites

    Science.gov (United States)

    2015-06-18

    Ceramics, San Diego, CA, manufactured the SiC/SiNC and C/SiC composites using polymer infiltration and pyrolysis (PIP). The C/HYPR-SiC™ and SiC/HYPR- SiC...research. Thank you to Dr. Kristin Keller (AFRL/RXCCM), Ms. Jennifer Pierce (AFRL/RXCM), Mr. Randall Corns (AFRL/RXCCM), and Dr. Kathleen Shugart (AFRL...with Hi-Nicalon™ SiC fibers in a SiNC matrix derived by polymer infiltration and pyrolysis (PIP) (manufactured by COI Ceramics, San Diego, CA

  9. Interaction phenomena at reactive metal/ceramic interfaces.

    Energy Technology Data Exchange (ETDEWEB)

    McDeavitt, S. M.; Billings, G. W.; Indacochea, J. E.

    2000-11-03

    The objective of this study was to understand the interface chemical reactions between stable ceramics and reactive liquid metals, and developing microstructure. Experiments were conducted at elevated temperatures where small metal samples of Zr and Zr-alloy were placed on top of selected oxide and non-oxide ceramic substrates (Y{sub 2}O{sub 3}, ZrN, ZrC, and HfC). The sample stage was heated in high-purity argon to about 2000 C, held in most cases for five minutes at the peak temperature, and then cooled to room temperature at {approximately}20 c/min. An external video camera was used to monitor the in-situ wetting and interface reactions. Post-test examinations of the systems were conducted by scanning electron microscopy and energy dispersive spectroscopy. It was determined that the Zr and the Zr-alloy are very active in the wetting of stable ceramics at elevated temperatures. In addition, in some systems, such as Zr/ZrN, a reactive transition phase formed between the ceramic and the metal. In other systems, such as Zr/Y{sub 2}O{sub 3}, Zr/ZrC and Zr/HfC, no reaction products formed, but a continuous and strong joint developed under these circumstances also.

  10. SUPPLEMENTARY INFORMATION Non-oxidative methane ...

    Indian Academy of Sciences (India)

    dell

    SUPPLEMENTARY INFORMATION. Non-oxidative methane dehydroaromatization reaction over highly active α-MoC1-x ZSM-5 derived from pretreatment. BUDDE PRADEEP KUMAR, ARVIND KUMAR SINGH and SREEDEVI UPADHYAYULA*. Heterogeneous Catalysis & Reaction Engineering Laboratory, Department of ...

  11. Corrosion of Ceramic Materials

    Science.gov (United States)

    Opila, Elizabeth J.; Jacobson, Nathan S.

    1999-01-01

    Non-oxide ceramics are promising materials for a range of high temperature applications. Selected current and future applications are listed. In all such applications, the ceramics are exposed to high temperature gases. Therefore it is critical to understand the response of these materials to their environment. The variables to be considered here include both the type of ceramic and the environment to which it is exposed. Non-oxide ceramics include borides, nitrides, and carbides. Most high temperature corrosion environments contain oxygen and hence the emphasis of this chapter will be on oxidation processes.

  12. Scale up issues involved with the ceramic waste form: ceramic-container interactions and ceramic cracking quantification

    International Nuclear Information System (INIS)

    Bateman, K. J.; DiSanto, T.; Goff, K. M.; Johnson, S. G.; O'Holleran, T.; Riley, W. P. Jr.

    1999-01-01

    Argonne National Laboratory is developing a process for the conditioning of spent nuclear fuel to prepare the material for final disposal. Two waste streams will result from the treatment process, a stainless steel based form and a ceramic based form. The ceramic waste form will be enclosed in a stainless steel container. In order to assess the performance of the ceramic waste form in a repository two factors must be examined, the surface area increases caused by waste form cracking and any ceramic/canister interactions that may release toxic material. The results indicate that the surface area increases are less than the High Level Waste glass and any toxic releases are below regulatory limits

  13. 4TH International Conference on High-Temperature Ceramic Matrix Composites

    National Research Council Canada - National Science Library

    2001-01-01

    .... Topic to be covered include fibers, interfaces, interphases, non-oxide ceramic matrix composites, oxide/oxide ceramic matrix composites, coatings, and applications of high-temperature ceramic matrix...

  14. Interactive Industrial Robot Programming for the Ceramic Industry

    OpenAIRE

    Germano Veiga; Pedro Malaca; Rui Cancela

    2013-01-01

    This paper presents an interactive programming method for programming industrial robots in ceramic applications. The main purpose was to develop a simple but flexible programming system that empowers the user with product driven programming without compromising flexibility. To achieve this flexibility, a two step hybrid programming model was designed: first the user sketches the desired trajectory in a spatial augmented reality programming table using the final product and then relies on an a...

  15. Nonoxidative free fatty acid disposal is greater in young women than men.

    Science.gov (United States)

    Koutsari, Christina; Basu, Rita; Rizza, Robert A; Nair, K Sreekumaran; Khosla, Sundeep; Jensen, Michael D

    2011-02-01

    Large increases in systemic free fatty acid (FFA) availability in the absence of a corresponding increase in fatty acid oxidation can create a host of metabolic abnormalities. These adverse responses are thought to be the result of fatty acids being shunted into hepatic very low-density lipoprotein-triglyceride production and/or intracellular lipid storage and signaling pathways because tissues are forced to increase nonoxidative FFA disposal. The objective of the study was to examine whether variations in postabsorptive nonoxidative FFA disposal within the usual range predict insulin resistance and hypertriglyceridemia. We measured: systemic FFA turnover using a continuous iv infusion of [9-10, (3)H]palmitate; substrate oxidation with indirect calorimetry combined with urinary nitrogen excretion; whole-body and peripheral insulin sensitivity with the labeled iv glucose tolerance test minimal model. the study was conducted at the Mayo Clinic General Clinical Research Center. Participants included healthy, postabsorptive, nonobese adults (21 women and 21 men). There were no interventions. Nonoxidative FFA disposal (micromoles per minute), defined as the FFA disappearance rate minus fatty acid oxidation. Women had 64% greater nonoxidative FFA disposal rate than men but a better lipid profile and similar insulin sensitivity. There was no significant correlation between nonoxidative FFA disposal and whole-body sensitivity, peripheral insulin sensitivity, or fasting serum triglyceride concentrations in men or women. Healthy nonobese women have greater rates of nonoxidative FFA disposal than men, but this does not appear to relate to adverse health consequences. Understanding the sex-specific interaction between adipose tissue lipolysis and peripheral FFA removal will help to discover new approaches to treat FFA-induced abnormalities.

  16. Hyperfine interaction measurements on ceramics: PZT revisited

    International Nuclear Information System (INIS)

    Guarany, Cristiano A.; Araujo, Eudes B.; Silva, Paulo R.J.; Saitovitch, Henrique

    2007-01-01

    The solid solution of PbZr 1- x Ti x O 3 , known as lead-zirconate titanate (PZT), was probably one of the most studied ferroelectric materials, especially due to its excellent dielectric, ferroelectric and piezoelectric properties. The highest piezoelectric coefficients of the PZT are found near the morphotropic phase boundary (MPB) (0.46≤x≤0.49), between the tetragonal and rhombohedral regions of the composition-temperature phase diagram. Recently, a new monoclinic phase near the MPB was observed, which can be considered as a 'bridge' between PZT's tetragonal and rhombohedral phases. This work is concerned with the study of the structural properties of the ferroelectric PZT (Zr/Ti=52/48, 53/47) by hyperfine interaction (HI) measurements obtained from experiments performed by using the nuclear spectroscopy time differential perturbed angular correlation (TDPAC) in a wide temperature range

  17. Hyperfine interaction measurements on ceramics: PZT revisited

    Energy Technology Data Exchange (ETDEWEB)

    Guarany, Cristiano A. [Universidade Estadual Paulista (Unesp), Departmento de Fisica Quimica, Caixa Postal 31, 15.385-000 Ilha Solteira, SP (Brazil); Araujo, Eudes B. [Universidade Estadual Paulista (Unesp), Departmento de Fisica Quimica, Caixa Postal 31, 15.385-000 Ilha Solteira, SP (Brazil); Silva, Paulo R.J. [Centro Brasileiro de Pesquisas Fisicas-Rua Dr. Xavier Sigaud, 150, 22290-180 Rio de Janeiro, RJ (Brazil); Saitovitch, Henrique [Centro Brasileiro de Pesquisas Fisicas-Rua Dr. Xavier Sigaud, 150, 22290-180 Rio de Janeiro, RJ (Brazil)]. E-mail: henrique@cbpf.br

    2007-02-01

    The solid solution of PbZr{sub 1-} {sub x} Ti {sub x} O{sub 3}, known as lead-zirconate titanate (PZT), was probably one of the most studied ferroelectric materials, especially due to its excellent dielectric, ferroelectric and piezoelectric properties. The highest piezoelectric coefficients of the PZT are found near the morphotropic phase boundary (MPB) (0.46{<=}x{<=}0.49), between the tetragonal and rhombohedral regions of the composition-temperature phase diagram. Recently, a new monoclinic phase near the MPB was observed, which can be considered as a 'bridge' between PZT's tetragonal and rhombohedral phases. This work is concerned with the study of the structural properties of the ferroelectric PZT (Zr/Ti=52/48, 53/47) by hyperfine interaction (HI) measurements obtained from experiments performed by using the nuclear spectroscopy time differential perturbed angular correlation (TDPAC) in a wide temperature range.

  18. Interaction at interface between superconducting yttrium ceramics and copper or niobium

    International Nuclear Information System (INIS)

    Karpov, M.I.; Korzhov, V.P.; Medved', N.V.; Myshlyaeva, M.M.

    1992-01-01

    Light metallography, scanning electron microscopy and local energy dispersion analysis have been used to study the interaction of Y-ceramics with copper and niobium. Samples in the form of wire of two types were employed, that is, consisting of ceramic core YBaCuO and Cu shell or a ceramic core YBaCuO and bimetallic Cu/Nb shell. The interaction of the ceramics with the shell metal began already at 500 deg with the formation at the interafaces Cu-YBaCuO of oxide layers containing ceramic elements, and in the ceramic core - nonsuperconducting phases. A thin Al-layer placed between the ceramics and the shell appreciably decreased the reactability of the ceramics with respect to copper and niobium

  19. Industrial ceramics - Properties, forming and applications

    International Nuclear Information System (INIS)

    Fantozzi, Gilbert; Niepce, Jean-Claude; Bonnefont, Guillaume; Alary, J.A.; Allard, B.; Ayral, A.; Bassat, J.M.; Elissalde, C.; Maglione, M.; Beauvy, M.; Bertrand, G.; Bignon, A.; Billieres, D.; Blanc, J.J.; Blumenfeld, P.; Bonnet, J.P.; Bougoin, M.; Bourgeon, M.; Boussuge, M.; Thorel, A.; Bruzek, C.E.; Cambier, F.; Carrerot, H.; Casabonne, J.M.; Chaix, J.M.; Chevalier, J.; Chopinet, M.H.; Couque, H.; Courtois, C.; Leriche, A.; Dhaler, D.; Denape, J.; Euzen, P.; Ganne, J.P.; Gauffinet, S.; Girard, A.; Gonon, M.; Guizard, C.; Hampshire, S.; Joulin, J.P.; Julbe, A.; Ferrato, M.; Fontaine, M.L.; Lebourgeois, R.; Lopez, J.; Maquet, M.; Marinel, S.; Marrony, M.; Martin, J.F.; Mougin, J.; Pailler, R.; Pate, M.; Petitpas, E.; Pijolat, C.; Pires-Franco, P.; Poirier, C.; Poirier, J.; Pourcel, F.; Potier, A.; Tulliani, J.M.; Viricelle, J.P.; Beauger, A.

    2013-01-01

    After a general introduction to ceramics (definition, general properties, elaboration, applications, market data), this book address conventional ceramics (elaboration, material types), thermo-structural ceramics (oxide based ceramics, non-oxide ceramics, fields of application, functional coatings), refractory ceramics, long fibre and ceramic matrix composites, carbonaceous materials, ceramics used for filtration, catalysis and the environment, ceramics for biomedical applications, ceramics for electronics and electrical engineering (for capacitors, magnetic, piezoelectric, dielectric ceramics, ceramics for hyper-frequency resonators), electrochemical ceramics, transparent ceramics (forming and sintering), glasses, mineral binders. The last chapter addresses ceramics used in the nuclear energy sector: in nuclear fuels and fissile material, absorbing ceramics and shields, in the management of nuclear wastes, new ceramics for reactors under construction or for future nuclear energy

  20. Interactive Industrial Robot Programming for the Ceramic Industry

    Directory of Open Access Journals (Sweden)

    Germano Veiga

    2013-10-01

    Full Text Available This paper presents an interactive programming method for programming industrial robots in ceramic applications. The main purpose was to develop a simple but flexible programming system that empowers the user with product driven programming without compromising flexibility. To achieve this flexibility, a two step hybrid programming model was designed: first the user sketches the desired trajectory in a spatial augmented reality programming table using the final product and then relies on an advanced 3D graphical system to tune the robot trajectory in the final workcell. The results measured by the end-user feedback show that a new level of flexibility was reached for this type of application.

  1. Characterization of the interaction between glazes and ceramic bodies

    Czech Academy of Sciences Publication Activity Database

    Kavanová, M.; Kloužková, A.; Kloužek, Jaroslav

    2017-01-01

    Roč. 61, č. 3 (2017), s. 267-275 ISSN 0862-5468 Institutional support: RVO:67985891 Keywords : glazes * ceramic s * thermal analysis * coefficients of the thermal expansion * dilatometry Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass OBOR OECD: Ceramic s Impact factor: 0.439, year: 2016

  2. Crystal-free Formation of Non-Oxide Optical Fiber

    Science.gov (United States)

    Nabors, Sammy A.

    2015-01-01

    Researchers at NASA Marshall Space Flight Center have devised a method for the creation of crystal-free nonoxide optical fiber preforms. Non-oxide fiber optics are extensively used in infrared transmitting applications such as communication systems, chemical sensors, and laser fiber guides for cutting, welding and medical surgery. However, some of these glasses are very susceptible to crystallization. Even small crystals can lead to light scatter and a high attenuation coefficient, limiting their usefulness. NASA has developed a new method of non-oxide fiber formation that uses axial magnetic fields to suppress crystallization. The resulting non-oxide fibers are crystal free and have lower signal attenuation rates than silica based optical fibers.

  3. Fiber Fabrication Facility for Non-Oxide and Specialty Glasses

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Unique facility for the research, development, and fabrication of non-oxide and specialty glasses and fibers in support of Navy/DoD programs.DESCRIPTION:...

  4. CHARACTERIZATION OF THE INTERACTION BETWEEN GLAZES AND CERAMIC BODIES

    Directory of Open Access Journals (Sweden)

    Maria Kavanova

    2017-07-01

    Full Text Available The paper presents the study of stress relations of ceramic body - glaze systems of model and real, both historical and contemporary ceramics. The systems were characterized in terms of chemical composition, linear thermal coefficients and degradation effects. The results show that calculation of stress relations between ceramic body and glaze is affected predominantly by the difference in values of thermal expansion coefficients. Calculated results provide relevant information about the accordance of the glaze - ceramic body and for the characterization of surface defects.

  5. Ceramics for Molten Materials Containment, Transfer and Handling on the Lunar Surface

    Science.gov (United States)

    Standish, Evan; Stefanescu, Doru M.; Curreri, Peter A.

    2009-01-01

    As part of a project on Molten Materials Transfer and Handling on the Lunar Surface, molten materials containment samples of various ceramics were tested to determine their performance in contact with a melt of lunar regolith simulant. The test temperature was 1600 C with contact times ranging from 0 to 12 hours. Regolith simulant was pressed into cylinders with the approximate dimensions of 1.25 dia x 1.25cm height and then melted on ceramic substrates. The regolith-ceramic interface was examined after processing to determine the melt/ceramic interaction. It was found that the molten regolith wetted all oxide ceramics tested extremely well which resulted in chemical reaction between the materials in each case. Alumina substrates were identified which withstood contact at the operating temperature of a molten regolith electrolysis cell (1600 C) for eight hours with little interaction or deformation. This represents an improvement over alumina grades currently in use and will provide a lifetime adequate for electrolysis experiments lasting 24 hours or more. Two types of non-oxide ceramics were also tested. It was found that they interacted to a limited degree with the melt resulting in little corrosion. These ceramics, Sic and BN, were not wetted as well as the oxides by the melt, and so remain possible materials for molten regolith handling. Tests wing longer holding periods and larger volumes of regolith are necessary to determine the ultimate performance of the tested ceramics.

  6. Mechanism of interaction of Co-B and Fe-B melts with ceramic materials

    International Nuclear Information System (INIS)

    Filonov, M.R.; Anikin, D.Yu.; Pecherkin, K.A.

    2003-01-01

    Stability of ceramic materials has been studied in the medium of melts being rendered amorphous. Measurements of limiting wetting angle for these materials were carried out on the ceramic surface. Two conclusions were made from the results of the experiments: melt-ceramics interaction takes place mainly through the slag phase; boron nitride is the most stable ceramics for melting and pouring of melts being rendered amorphous in the air. Materials on the basis of BN were synthesized by the self-propagating high-temperature synthesis. Other refractory compounds were introduced in the ceramics composition for the purpose of improving such service properties as fire resistance, thermal resistance, mechanical strength, stability of compounds to the effect of reaction-active melts. The most promising refractory compositions were determined from the results of the studies [ru

  7. Non-oxidative conversion of methane into higher hydrocarbons over ...

    Indian Academy of Sciences (India)

    SOURABH MISHRA

    2017-09-27

    Sep 27, 2017 ... ... in the Design and Development of Catalysts and their Applications ... of methane (natural gas) into transportable chemicals ... molybdenum (Mo) catalyst under non-oxidative condi- ... Micromeritics ASAP 2010 apparatus at liquid nitrogen tem- ... fixed-bed tubular reactor (500 mm length & 15 mm ID) at.

  8. Interaction mechanisms between ceramic particles and atomized metallic droplets

    Science.gov (United States)

    Wu, Yue; Lavernia, Enrique J.

    1992-10-01

    The present study was undertaken to provide insight into the dynamic interactions that occur when ceramic particles are placed in intimate contact with a metallic matrix undergoing a phase change. To that effect, Al-4 wt pct Si/SiCp composite droplets were synthesized using a spray atomization and coinjection approach, and their solidification microstructures were studied both qualitatively and quantitatively. The present results show that SiC particles (SiCp) were incor- porated into the matrix and that the extent of incorporation depends on the solidification con- dition of the droplets at the moment of SiC particle injection. Two factors were found to affect the distribution and volume fraction of SiC particles in droplets: the penetration of particles into droplets and the entrapment and/or rejection of particles by the solidification front. First, during coinjection, particles collide with the atomized droplets with three possible results: they may penetrate the droplets, adhere to the droplet surface, or bounce back after impact. The extent of penetration of SiC particles into droplets was noted to depend on the kinetic energy of the particles and the magnitude of the surface energy change in the droplets that occurs upon impact. In liquid droplets, the extent of penetration of SiC particles was shown to depend on the changes in surface energy, ΔEs, experienced by the droplets. Accordingly, large SiC particles encoun- tered more resistance to penetration relative to small ones. In solid droplets, the penetration of SiC particles was correlated with the dynamic pressure exerted by the SiC particles on the droplets during impact and the depth of the ensuing crater. The results showed that no pene- tration was possible in such droplets. Second, once SiC particles have penetrated droplets, their final location in the microstructure is governed by their interactions with the solidification front. As a result of these interactions, both entrapment and rejection of

  9. Proceedings of the fifteenth international workshop on ceramic breeder blanket interactions

    International Nuclear Information System (INIS)

    Tanigawa, Hisashi; Enoeda, Mikio

    2010-03-01

    This report is the Proceedings of 'the Fifteenth International Workshop on Ceramic Breeder Blanket Interactions' which was held as a workshop on ceramic breeders Under the IEA Implementing Agreement on the Nuclear Technology of Fusion Reactors. This workshop was held in Sapporo, Japan on 3-4, Sept. 2009. Twenty six participants from EU, Japan, India, Russia and USA attended the workshop. The scope of the workshop included 1) evolutions in ceramic breeder blanket design, 2) progress in ceramic breeder material development, 3) irradiation testing, 4) breeder material properties, 5) out-of-pile pebble bed experiment, 6) modeling of the thermal, mechanical and tritium transfer behavior of pebble beds and 7) interfacing issues of solid breeder blanket development. By this workshop, advance of key technologies for solid breeder blanket development was shared among the participants. Also, desired direction of further investigation and development was recognized. The 20 of the presented papers are indexed individually. (J.P.N.)

  10. Proceedings of the fifteenth international workshop on ceramic breeder blanket interactions

    Energy Technology Data Exchange (ETDEWEB)

    Tanigawa, Hisashi; Enoeda, Mikio [Japan Atomic Energy Agency, Fusion Research and Development Directorate, Naka, Ibaraki (Japan)

    2010-03-15

    This report is the Proceedings of 'the Fifteenth International Workshop on Ceramic Breeder Blanket Interactions' which was held as a workshop on ceramic breeders Under the IEA Implementing Agreement on the Nuclear Technology of Fusion Reactors. This workshop was held in Sapporo, Japan on 3-4, Sept. 2009. Twenty six participants from EU, Japan, India, Russia and USA attended the workshop. The scope of the workshop included 1) evolutions in ceramic breeder blanket design, 2) progress in ceramic breeder material development, 3) irradiation testing, 4) breeder material properties, 5) out-of-pile pebble bed experiment, 6) modeling of the thermal, mechanical and tritium transfer behavior of pebble beds and 7) interfacing issues of solid breeder blanket development. By this workshop, advance of key technologies for solid breeder blanket development was shared among the participants. Also, desired direction of further investigation and development was recognized. The 20 of the presented papers are indexed individually. (J.P.N.)

  11. Interactions of ceramic, metallic and polymeric filters with gaseous contaminants

    International Nuclear Information System (INIS)

    Haider, A.M.; Ma, Ce; Shadman, Farhang

    1993-01-01

    Outgassing characteristics of ceramic, metallic, and polymeric fitters for H 2 O, O 2 , CO 2 , and CH 4 were explored using APIMS in this study. The outgassing data has been normalized with respect to the parameters that varied from one filter to the other. Hydrocarbon outgassing is also explored both at room temperature from freshly installed filters as well as at elevated temperatures. Polymeric filters appeared to be more transparent but did show hydrocarbon outgassing when heated to 50 C

  12. Proceedings of the sixth international workshop on ceramic breeder blanket interactions

    International Nuclear Information System (INIS)

    Noda, Kenji

    1998-03-01

    This report is the Proceedings of ''the Sixth International Workshop on Ceramic Breeder Blanket Interactions'' which was held as a workshop on ceramic breeders under Annex II of IEA Implementing Agreement on a Programme of Research and Development on Fusion Materials, and Japan-US Workshop 97FT4-01. This workshop was held in Mito city, Japan on October 22-24, 1997. About forty experts from EU, Japan, USA, and Chile attended the workshop. The scope of the workshop included the following: 1) fabrication and characterization of ceramic breeders, 2) properties data for ceramic breeders, 3) tritium release characteristics, 4) modeling of tritium behavior, 5) irradiation effects on performance behavior, 6) blanket design and R and D requirements, 7) hydrogen behavior in materials, and 8) blanket system technology and structural materials. In the workshop, information exchange was performed for fabrication technology of ceramic breeder pebbles in EU and Japan, data of various properties of Li 2 TiO 3 , tritium release behavior of Li 2 TiO 3 and Li 2 ZrO 3 including tritium diffusion, modeling of tritium release from Li 2 ZrO 3 in ITER condition, helium release behavior from Li 2 O, results of tritium release irradiation tests of Li 4 SiO 4 pebbles in EXOTIC-7, R and D issues for ceramic breeders for ITER and DEMO blankets, etc. The 23 of the papers are indexed individually. (J.P.N.)

  13. Chemical interaction silicon nitride ceramics and iron alloys

    Directory of Open Access Journals (Sweden)

    Oliveira, F. J.

    2000-12-01

    Full Text Available Metal/ceramic diffusion experiments are helpful to study bonding mechanisms or the effect of metal composition on the chemical wear of ceramic cutting tools. The reaction kinetics of Fe alloys/Si3 N4 ceramic diffusion couples was investigated in the temperature range 1050ºC-1250ºC, for 0.5h to 80h, under inert atmosphere. Optical microscopy, SEM and EPMA were carried out in cross sections of the reacted pairs. Si3N4 decomposes into Si and N that dissolve and diffuse through the metal. Both the diffusion zone on the metal side and the reaction zone on the ceramic side obey parabolic growth laws of time, with activation energies in the range Q=310-460kJmol-1. The amount of dissolved Si, the length of the diffusion zone and thus the reactivity of the ceramic increase as the alloy carbon content decreases. Due to Si accumulation, the α-Fe solid solution is stabilised at the reaction temperature and a steep decrease in the Si concentration is observed beyond the diffusion zone. The reinforcement of the Si3N4 composites with A12O3 platelets enhances the chemical resistance of the ceramic due to the inertness of this oxide and to the partial crystallisation of the intergranular phase. Other dispersoids such as HfN, BN and TiN do not improve the chemical resistance of the matrix by iron attack.

    Los experimentos de difusión metal/cerámica permiten estudiar mecanismos de unión y analizar el efecto de la composición del metal en el desgaste químico de herramientas de corte cerámicas. En este trabajo se investigó la cinética de reacción en pares de difusión aleaciones de Fe/Si3N4 a temperaturas entre 1050ºC-1250ºC, tiempos entre 0.5h a 80h, en atmósfera inerte. Las secciones transversales de los pares de difusión se analizaron mediante microscopía óptica, SEM y microsonda electrónica. El Si3N4 se descompone en Si y N que se disuelven y difunden en el metal. Tanto la zona de difusión en el metal como la zona de reacción en la cer

  14. Interaction of elementary damage processes and their contribution to neutron damage of ceramics

    International Nuclear Information System (INIS)

    Itoh, Noriaki

    1989-01-01

    Specific features of radiation damage of ceramics as compared with those of metals are discussed. It is pointed out that the electronic excitation gives considerable contribution to radiation damage of ceramics not only by itself but also through interaction with knock-on processes. In the talk first I mention briefly the elementary damage processes; the knock-on process and the processes induced by electronic excitation; the latter is of particularly importance in ceramics because of large energy quantums. Then I discuss possible interactions between these elementary processes; why they may contribute to radiation damage and in what situation they are induced. The types of interactions discussed include those between knock-on processes, between electronic excitation and knock-on processes and between processes induced by electronic excitation. Experimental results which prove directly the significance of such interactions are also described. Importance of such interactions in radiation damage of ceramics and their relevance to other phenomena, such as laser damage, is emphasized. Possible experimental techniques, including those which uses high energy neutron sources, are described. (author)

  15. Corrosion of technical ceramics by molten aluminium

    NARCIS (Netherlands)

    Schwabe, U.; Wolff, L.R.; Loo, van F.J.J.; Ziegler, G.; With, de G.; Terpstra, R.A.; Metselaar, R.

    1989-01-01

    Corrosion investigations on various types of nonoxide technical ceramic materials, two types of silicon nitride (HIPRBSN and RBSN) and two types of silicon carbide (HIPSIC and SiSiC), were carried out in aluminum (Al99.99) melts. HIPRBSN showed nearly no corrosion attack under the most severe

  16. Proceedings of the sixth international workshop on ceramic breeder blanket interactions

    Energy Technology Data Exchange (ETDEWEB)

    Noda, Kenji [ed.

    1998-03-01

    This report is the Proceedings of `the Sixth International Workshop on Ceramic Breeder Blanket Interactions` which was held as a workshop on ceramic breeders under Annex II of IEA Implementing Agreement on a Programme of Research and Development on Fusion Materials, and Japan-US Workshop 97FT4-01. This workshop was held in Mito city, Japan on October 22-24, 1997. About forty experts from EU, Japan, USA, and Chile attended the workshop. The scope of the workshop included the following: (1) fabrication and characterization of ceramic breeders, (2) properties data for ceramic breeders, (3) tritium release characteristics, (4) modeling of tritium behavior, (5) irradiation effects on performance behavior, (6) blanket design and R and D requirements, (7) hydrogen behavior in materials, and (8) blanket system technology and structural materials. In the workshop, information exchange was performed for fabrication technology of ceramic breeder pebbles in EU and Japan, data of various properties of Li{sub 2}TiO{sub 3}, tritium release behavior of Li{sub 2}TiO{sub 3} and Li{sub 2}ZrO{sub 3} including tritium diffusion, modeling of tritium release from Li{sub 2}ZrO{sub 3} in ITER condition, helium release behavior from Li{sub 2}O, results of tritium release irradiation tests of Li{sub 4}SiO{sub 4} pebbles in EXOTIC-7, R and D issues for ceramic breeders for ITER and DEMO blankets, etc. The 23 of the papers are indexed individually. (J.P.N.)

  17. Technological pretreatment of the synchysite non-oxidized ore

    Science.gov (United States)

    Munkhtsetseg, B.; Burmaa, G.

    2013-06-01

    Mongolia has rich deposits of rare, precious, and poly-metallic ores. Nowadays, it is important to research separation of rare earth elements oxides concentrates from the ores, analyze their unique physical chemical characteristics, and purified it. Our investigation on raw materials focuses on rare earth non-oxidized ores. Main mineral in this rock sample is Synchysite (LnCa(CO3)2F. We did technological and thermal pretreatment: direct sulphurization (H2SO4), sulphurization with subsequent roasting (800°C+H2SO4), sulphurization prior to roasting (H2SO4+650°C). Sulphurization method based on dissolution of rare earth mineral into sulfuric acid (93%) according to the reaction. The amount of rare earth element oxides is almost 10 times greater (29.16%) after direct sulphurization process, almost 8 times greater (21.14%) after sulphurization with subsequent roasting, and almost 20 times greater (44.62%) after sulphurization prior to roasting process. After those technological pretreatment raw material's micro elements Thorium and Uranium contents are reduced as follows: H2SO4>800°C+H2SO4>H2SO4+650°C. These results show that cerium group rare earth elements have very good solubility in water at +2°C temperature and decreasing micro elements content uranium and thorium good pretreatment condition is prior to roasting (H2SO4+650°C) of synchysite non-oxidized ore.

  18. HosA, a MarR Family Transcriptional Regulator, Represses Nonoxidative Hydroxyarylic Acid Decarboxylase Operon and Is Modulated by 4-Hydroxybenzoic Acid.

    Science.gov (United States)

    Roy, Ajit; Ranjan, Akash

    2016-02-23

    Members of the Multiple antibiotic resistance Regulator (MarR) family of DNA binding proteins regulate transcription of a wide array of genes required for virulence and pathogenicity of bacteria. The present study reports the molecular characterization of HosA (Homologue of SlyA), a MarR protein, with respect to its target gene, DNA recognition motif, and nature of its ligand. Through a comparative genomics approach, we demonstrate that hosA is in synteny with nonoxidative hydroxyarylic acid decarboxylase (HAD) operon and is present exclusively within the mutS-rpoS polymorphic region in nine different genera of Enterobacteriaceae family. Using molecular biology and biochemical approach, we demonstrate that HosA binds to a palindromic sequence downstream to the transcription start site of divergently transcribed nonoxidative HAD operon and represses its expression. Furthermore, in silico analysis showed that the recognition motif for HosA is highly conserved in the upstream region of divergently transcribed operon in different genera of Enterobacteriaceae family. A systematic chemical search for the physiological ligand revealed that 4-hydroxybenzoic acid (4-HBA) interacts with HosA and derepresses HosA mediated repression of the nonoxidative HAD operon. Based on our study, we propose a model for molecular mechanism underlying the regulation of nonoxidative HAD operon by HosA in Enterobacteriaceae family.

  19. Upgrading non-oxidized carbon nanotubes by thermally decomposed hydrazine

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Pen-Cheng, E-mail: wangpc@ess.nthu.edu.tw [Department of Engineering and System Science, National Tsing Hua University, 101 Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Graduate Program for Science and Technology of Synchrotron Light Source, National Tsing Hua University, 101 Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Liao, Yu-Chun [Department of Engineering and System Science, National Tsing Hua University, 101 Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Graduate Program for Science and Technology of Synchrotron Light Source, National Tsing Hua University, 101 Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Liu, Li-Hung [Department of Engineering and System Science, National Tsing Hua University, 101 Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); Lai, Yu-Ling; Lin, Ying-Chang [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Hsu, Yao-Jane [Graduate Program for Science and Technology of Synchrotron Light Source, National Tsing Hua University, 101 Section 2, Kuang-Fu Road, Hsinchu 30013, Taiwan (China); National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China)

    2014-06-01

    We found that the electrical properties of conductive thin films based on non-oxidized carbon nanotubes (CNTs) could be further improved when the CNTs consecutively underwent a mild hydrazine adsorption treatment and then a sufficiently effective thermal desorption treatment. We also found that, after several rounds of vapor-phase hydrazine treatments and baking treatments were applied to an inferior single-CNT field-effect transistor device, the device showed improvement in I{sub on}/I{sub off} ratio and reduction in the extent of gate-sweeping hysteresis. Our experimental results indicate that, even though hydrazine is a well-known reducing agent, the characteristics of our hydrazine-exposed CNT samples subject to certain treatment conditions could become more graphenic than graphanic, suggesting that the improvement in the electrical and electronic properties of CNT samples could be related to the transient bonding and chemical scavenging of thermally decomposed hydrazine on the surface of CNTs.

  20. Upgrading non-oxidized carbon nanotubes by thermally decomposed hydrazine

    Science.gov (United States)

    Wang, Pen-Cheng; Liao, Yu-Chun; Liu, Li-Hung; Lai, Yu-Ling; Lin, Ying-Chang; Hsu, Yao-Jane

    2014-06-01

    We found that the electrical properties of conductive thin films based on non-oxidized carbon nanotubes (CNTs) could be further improved when the CNTs consecutively underwent a mild hydrazine adsorption treatment and then a sufficiently effective thermal desorption treatment. We also found that, after several rounds of vapor-phase hydrazine treatments and baking treatments were applied to an inferior single-CNT field-effect transistor device, the device showed improvement in Ion/Ioff ratio and reduction in the extent of gate-sweeping hysteresis. Our experimental results indicate that, even though hydrazine is a well-known reducing agent, the characteristics of our hydrazine-exposed CNT samples subject to certain treatment conditions could become more graphenic than graphanic, suggesting that the improvement in the electrical and electronic properties of CNT samples could be related to the transient bonding and chemical scavenging of thermally decomposed hydrazine on the surface of CNTs.

  1. Hybrid Ceramic Matrix Fibrous Composites: an Overview

    Science.gov (United States)

    Naslain, R.

    2011-10-01

    Ceramic-Matrix Composites (CMCs) consist of a ceramic fiber architecture in a ceramic matrix, bonded together through a thin interphase. The present contribution is limited to non-oxide CMCs. Their constituents being oxidation-prone, they are protected by external coatings. We state here that CMCs display a hybrid feature, when at least one of their components is not homogeneous from a chemical or microstructural standpoint. Hybrid fiber architectures are used to tailor the mechanical or thermal CMC-properties whereas hybrid interphases, matrices and coatings to improve CMC resistance to aggressive environments.

  2. Hybrid Ceramic Matrix Fibrous Composites: an Overview

    International Nuclear Information System (INIS)

    Naslain, R

    2011-01-01

    Ceramic-Matrix Composites (CMCs) consist of a ceramic fiber architecture in a ceramic matrix, bonded together through a thin interphase. The present contribution is limited to non-oxide CMCs. Their constituents being oxidation-prone, they are protected by external coatings. We state here that CMCs display a hybrid feature, when at least one of their components is not homogeneous from a chemical or microstructural standpoint. Hybrid fiber architectures are used to tailor the mechanical or thermal CMC-properties whereas hybrid interphases, matrices and coatings to improve CMC resistance to aggressive environments.

  3. Proceedings of the eleventh international workshop on ceramic breeder blanket interactions

    International Nuclear Information System (INIS)

    Enoeda, Mikio

    2004-07-01

    This report is the Proceedings of 'the Eleventh International Workshop on Ceramic Breeder Blanket Interactions' which was held as a workshop on ceramic breeders Under the IEA Implementing Agreement on the Nuclear Technology of Fusion Reactors, and the Japan-US Fusion Collaboration Framework. This workshop was held in Tokyo, Japan on December 15-17, 2003. About thirty experts from China, EU, Japan, Korea, Latvia, Russia and USA attended the workshop. The scope of the workshop included 1) evolutions in ceramic breeder blanket design, 2) progress in ceramic breeder material development, 3) irradiation testing, 4) breeder material properties, 5) out-of-pile pebble bed experiment, 6) modeling of the thermal, mechanical and tritium transfer behavior of pebble beds and 7) interfacing issues of solid breeder blanket. In the workshop, information exchange was performed for designs of solid breeder blankets and test blankets in EU, Russia and Japan, recent results of irradiation tests, HICU, EXOTIC-8 and the irradiation tests by IVV-2M, modeling study on tritium release behavior of Li 2 TiO 3 and so on, fabrication technology developments and characterization of the Li 2 TiO 3 and Li 4 SiO 4 pebbles, research on measurements and modeling of thermo-mechanical behaviors of Li 2 TiO 3 and Li 4 SiO 4 pebbles, and interfacing issues, such as, fabrication technology for blanket box structure, neutronics experiments of blanket mockups by fusion neutron source and tritium recovery system. The 26 of the presented papers are indexed individually. (J.P.N.)

  4. Interaction of HEPES buffer with glass-ceramic scaffold: Can HEPES replace TRIS in SBF?

    Science.gov (United States)

    Rohanová, Dana; Horkavcová, Diana; Paidere, Laine; Boccaccini, Aldo Roberto; Bozděchová, Pavlína; Bezdička, Petr

    2018-01-01

    An international standard (ISO: 23317:2014) exists for the in vitro testing of inorganic biomaterials in simulated body fluid (SBF). This standard uses TRIS buffer to maintain neutral pH in SBF, but in our previous paper, we showed that the interaction of a tested glass-ceramic material with TRIS can produce false-positive results. In this study, we evaluated whether the HEPES buffer, which also belongs to the group of Good´s buffers, would be more suitable for SBF. We compared its suitability in two media: SBF with HEPES and demineralized water with HEPES. The tested scaffold (45S5 bioactive glass-based) was exposed to the media under a static-dynamic arrangement (solutions were replaced on a daily basis) for 15 days. Leachate samples were collected daily for the analysis of Ca 2+ ions and Si (AAS), (PO 4 ) 3- ions (UV-VIS), and to measure pH. The glass-ceramic scaffold was analyzed by SEM/EDS, XRD, and WD-XRF before and after 0.3, 1, 3, 7, 11, and 15 days of exposure. Our results confirmed the rapid selective dissolution of the glass-ceramic crystalline phase (Combeite) containing Ca 2+ ions due to the presence of HEPES, hydroxyapatite supersaturation being reached within 24 h in both solutions. These new results suggest that, like TRIS, HEPES buffer is not suitable for the in vitro testing of highly reactive inorganic biomaterials (glass, glass-ceramics). The ISO standard for such tests requires revision, but HEPES is not a viable alternative to TRIS buffer. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 143-152, 2018. © 2016 Wiley Periodicals, Inc.

  5. Sensitive Ceramics

    DEFF Research Database (Denmark)

    2014-01-01

    Sensitive Ceramics is showing an interactive digital design tool for designing wall like composition with 3d ceramics. The experiment is working on two levels. One which has to do with designing compositions and patterns in a virtual 3d universe based on a digital dynamic system that responds on ...... with realizing the modules in ceramics by 3d printing directly in porcelain with a RapMan printer that coils up the 3d shape in layers. Finally the ceramic modules are mounted in a laser cut board that reflects the captured composition of the movement of the hands....

  6. Aerospace Ceramic Materials: Thermal, Environmental Barrier Coatings and SiC/SiC Ceramic Matrix Composites for Turbine Engine Applications

    Science.gov (United States)

    Zhu, Dongming

    2018-01-01

    Ceramic materials play increasingly important roles in aerospace applications because ceramics have unique properties, including high temperature capability, high stiffness and strengths, excellent oxidation and corrosion resistance. Ceramic materials also generally have lower densities as compared to metallic materials, making them excellent candidates for light-weight hot-section components of aircraft turbine engines, rocket exhaust nozzles, and thermal protection systems for space vehicles when they are being used for high-temperature and ultra-high temperature ceramics applications. Ceramic matrix composites (CMCs), including non-oxide and oxide CMCs, are also recently being incorporated in gas turbine engines for high pressure and high temperature section components and exhaust nozzles. However, the complexity and variability of aerospace ceramic processing methods, compositions and microstructures, the relatively low fracture toughness of the ceramic materials, still remain the challenging factors for ceramic component design, validation, life prediction, and thus broader applications. This ceramic material section paper presents an overview of aerospace ceramic materials and their characteristics. A particular emphasis has been placed on high technology level (TRL) enabling ceramic systems, that is, turbine engine thermal and environmental barrier coating systems and non-oxide type SiC/SiC CMCs. The current status and future trend of thermal and environmental barrier coatings and SiC/SiC CMC development and applications are described.

  7. Light Weight Biomorphous Cellular Ceramics from Cellulose Templates

    Science.gov (United States)

    Singh, Mrityunjay; Yee, Bo-Moon; Gray, Hugh R. (Technical Monitor)

    2003-01-01

    Bimorphous ceramics are a new class of materials that can be fabricated from the cellulose templates derived from natural biopolymers. These biopolymers are abundantly available in nature and are produced by the photosynthesis process. The wood cellulose derived carbon templates have three- dimensional interconnectivity. A wide variety of non-oxide and oxide based ceramics have been fabricated by template conversion using infiltration and reaction-based processes. The cellular anatomy of the cellulose templates plays a key role in determining the processing parameters (pyrolysis, infiltration conditions, etc.) and resulting ceramic materials. The processing approach, microstructure, and mechanical properties of the biomorphous cellular ceramics (silicon carbide and oxide based) have been discussed.

  8. Non-oxidative and oxidative torrefaction characterization and SEM observations of fibrous and ligneous biomass

    International Nuclear Information System (INIS)

    Chen, Wei-Hsin; Lu, Ke-Miao; Lee, Wen-Jhy; Liu, Shih-Hsien; Lin, Ta-Chang

    2014-01-01

    Highlights: • Non-oxidative and oxidative torrefaction of biomass is studied. • Two fibrous biomasses and two ligneous biomasses are tested. • SEM observations of four biomasses are provided. • Fibrous biomass is more sensitive to O 2 concentration than ligneous biomass. • The performance of non-oxidative torrefaction is better than that of oxidative torrefaction. - Abstract: Oxidative torrefaction is a method to reduce the operating cost of upgrading biomass. To understand the potential of oxidative torrefaction and its impact on the internal structure of biomass, non-oxidative and oxidative torrefaction of two fibrous biomass materials (oil palm fiber and coconut fiber) and two ligneous ones (eucalyptus and Cryptomeria japonica) at 300 °C for 1 h are studied and compared with each other. Scanning electron microscope (SEM) observations are also performed to explore the impact of torrefaction atmosphere on the lignocellulosic structure of biomass. The results indicate that the fibrous biomass is more sensitive to O 2 concentration than the ligneous biomass. In oxidative torrefaction, an increase in O 2 concentration decreases the solid yield. The energy yield is linearly proportional to the solid yield, which is opposite to the behavior of non-oxidative torrefaction. The performance of non-oxidative torrefaction is better than that of oxidative torrefaction. As a whole, ligneous biomass can be torrefied in oxidative environments at lower O 2 concentrations, whereas fibrous biomass is more suitable for non-oxidative torrefaction

  9. Nonoxidized, biologically active parathyroid hormone determines mortality in hemodialysis patients

    DEFF Research Database (Denmark)

    Tepel, Martin; Armbruster, Franz Paul; Grön, Hans Jürgen

    2013-01-01

    Background: It was shown that nonoxidized PTH (n-oxPTH) is bioactive, whereas the oxidation of PTH results in a loss of biological activity. Methods: In this study we analyzed the association of n-oxPTH on mortality in hemodialysis patients using a recently developed assay system. Results......: Hemodialysis patients (224 men, 116 women) had a median age of 66 years. One hundred seventy patients (50%) died during the follow-up period of 5 years. Median n-oxPTH levels were higher in survivors (7.2 ng/L) compared with deceased patients (5.0 ng/L; P = .002). Survival analysis showed an increased survival...... in the highest n-oxPTH tertile compared with the lowest n-oxPTH tertile (χ(2), 14.3; P = .0008). Median survival was 1702 days in the highest n-oxPTH tertile, whereas it was only 453 days in the lowest n-oxPTH tertile. Multivariable-adjusted Cox regression showed that higher age increased odds for death, whereas...

  10. Material interactions between system components and glass product melts in a ceramic melter

    International Nuclear Information System (INIS)

    Knitter, R.

    1989-07-01

    The interactions of the ceramic and metallic components of a ceramic melter for the vitrification of High Active Waste were investigated with simulated glass product melts in static crucible tests at 1000 0 C and 1150 0 C. Corrosion of the fusion-cast Al 2 O 3 -ZrO 2 -SiO 2 - and Al 2 O 3 -ZrO 2 -SiO 2 -Cr 2 O 3 -refractories (ER 1711 and ER 2161) is characterized by homogeneous chemical dissolution and diffusion through the glass matrix of the refractory. The resulting boundary compositions lead to characteristic modification and formation of phases, not only inside the refractory but also in the glass melt. The attack of the electrode material, a Ni-Cr-Fe-alloy Inconel 690, by the glass melt takes place via grain boundaries and leads to the oxidation of Cr and growth of Cr 2 O 3 -crystals at the boundary layer. Noble metals, added to the glass melt can form solid solutions with the alloy with varying compositions. (orig.) [de

  11. Ceramic membrane as a pretreatment for reverse osmosis: Interaction between marine organic matter and metal oxides

    KAUST Repository

    Dramas, Laure

    2013-02-01

    Scaling and (bio)fouling phenomena can severely alter the performance of the reverse osmosis process during desalination of seawater. Pretreatments must be applied to efficiently remove particles, colloids, and also precursors of the organic fouling and biofouling. Ceramic membranes offer a lot of advantages for micro and ultrafiltration pretreatments because their initial properties can be recovered using more severe cleaning procedure. The study focuses on the interaction between metal oxides and marine organic matter. Experiments were performed at laboratory scale. The first series of experiments focus on the filtration of different fractions of natural organic matter and model compounds solutions on flat disk ceramic membranes (47 mm of diameter) characterized with different pore size and composition. Direct filtration experiments were conducted at 0.7 bar or 2 bars and at room temperature (20 ± 0.5 °C). The efficiency of backflush and alkaline cleaning were eval, and titanium oxides. Each metal oxide corresponds to a specific pore size for the disk ceramic membranes: 80, 60, and 30 nm. Different sizes of metal oxide particles are used to measure the impact of the surface area on the adsorption of the organic matter. Seawaters from the Arabian Gulf and from the Red Sea were collected during algal blooms. Cultures of algae were also performed in the laboratory and in cooperation with woods hole oceanographic institute. Solutions of algal exudates were obtained after a couple of weeks of cultivation followed by sonication. Solutions were successively filtered through GFF (0.7 lm) and 0.45 lm membrane filters before use. The dissolved organic carbon (DOC) concentration of final solution was between 1 and 4 mg/L and showed strong hydrophilic character. These various solutions were prepared with the objective to mimic the dissolved organic matter composition of seawater subjected to algal bloom. Characterization of the solutions of filtration experiments (feed

  12. Contrasting the beam interaction characteristics of selected lasers with a partially stabilized zirconia bio-ceramic

    International Nuclear Information System (INIS)

    Lawrence, J.

    2002-01-01

    Differences in the beam interaction characteristics of a CO 2 laser, a Nd:YAG laser, a high power diode laser (HPDL) and an excimer laser with a partially stabilized zirconia bio-ceramic have been studied. A derivative of Beer-Lambert's law was applied and the laser beam absorption lengths of the four lasers were calculated as 33.55x10 -3 cm for the CO 2 laser, 18.22x10 -3 cm for the Nd : YAG laser, 17.17x10 -3 cm for the HPDL and 8.41x10 -6 cm for the excimer laser. It was determined graphically that the fluence threshold values at which significant material removal was effected by the CO 2 laser, the Nd:YAG laser, the HPDL and the excimer laser were 52 J cm -2 , 97 J cm -2 , 115 J cm -2 and 0.48 J cm -2 , respectively. The thermal loading value for the CO 2 laser, the Nd : YAG laser, the HPDL and the excimer laser were calculated as being 1.55 kJ cm -3 , 5.32 kJ cm 3 , 6.69 kJ cm -3 and 57.04 kJ cm -3 , respectively. (author)

  13. Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji-Won; Rondinone, Adam Justin; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

    2017-09-19

    The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component comprising at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

  14. Microbially-mediated method for synthesis of non-oxide semiconductor nanoparticles

    Science.gov (United States)

    Phelps, Tommy J.; Lauf, Robert J.; Moon, Ji Won; Rondinone, Adam J.; Love, Lonnie J.; Duty, Chad Edward; Madden, Andrew Stephen; Li, Yiliang; Ivanov, Ilia N.; Rawn, Claudia Jeanette

    2014-06-24

    The invention is directed to a method for producing non-oxide semiconductor nanoparticles, the method comprising: (a) subjecting a combination of reaction components to conditions conducive to microbially-mediated formation of non-oxide semiconductor nanoparticles, wherein said combination of reaction components comprises i) anaerobic microbes, ii) a culture medium suitable for sustaining said anaerobic microbes, iii) a metal component comprising at least one type of metal ion, iv) a non-metal component containing at least one non-metal selected from the group consisting of S, Se, Te, and As, and v) one or more electron donors that provide donatable electrons to said anaerobic microbes during consumption of the electron donor by said anaerobic microbes; and (b) isolating said non-oxide semiconductor nanoparticles, which contain at least one of said metal ions and at least one of said non-metals. The invention is also directed to non-oxide semiconductor nanoparticle compositions produced as above and having distinctive properties.

  15. Electrically conductive ceramics and new joining technology for applications in HTR engineering

    Energy Technology Data Exchange (ETDEWEB)

    Hille, Carmen, E-mail: carmen.hille@ilkdresden.de [Dresden University of Technology (TU Dresden), Institute of Power Engineering, Chair of Hydrogen Technology and Nuclear Power Engineering, George-Baehr-Str. 3b, D-01062 Dresden (Germany); Lippmann, Wolfgang, E-mail: wolfgang.lippmann@tu-dresden.de [Dresden University of Technology (TU Dresden), Institute of Power Engineering, Chair of Hydrogen Technology and Nuclear Power Engineering, George-Baehr-Str. 3b, D-01062 Dresden (Germany); Hurtado, Antonio, E-mail: antonio.hurtado@tu-dresden.de [Dresden University of Technology (TU Dresden), Institute of Power Engineering, Chair of Hydrogen Technology and Nuclear Power Engineering, George-Baehr-Str. 3b, D-01062 Dresden (Germany)

    2012-10-15

    Ceramic constructional components are quite extensively required for operation of high-temperature nuclear reactors. Functional ceramics, in addition to constructional ceramics, are increasingly coming into the focus of research. Ceramic materials are predestined for use at high temperatures and in corrosive atmospheres. Modification of silicon carbide (SiC) by targeted doping, for instance, produces a suitable material for the production of heating conductors and thermoelectric generators. As a construction material, silicon carbide (SiC) is especially interesting due to its very good thermal, mechanical and radiological properties. SiC, furthermore, performs well when activated by neutron irradiation, with the induced activation subsiding after only a few hours (). This property vector makes it an ideal starting material for use in a wide range of functional elements in high-temperature power engineering, particularly in high-temperature nuclear reactor engineering (e.g. V/HTR) including thermochemical plants for hydrogen generation or Synfuel production. In principle, it is possible to produce all-ceramic assemblies consisting of a thermoelectric generator and a sensor that can provide reliable measurement signals under extreme conditions in the high-temperature range without external power supply. This paper explains the feasibility of laser-joining such modified non-oxide ceramics, how to make electrically conductive joints, and thus, how to design complex assemblies. The parameters required for an optimal laser process to join ceramic materials were determined in extensive preliminary experiments. These investigations focused on the specific electrical resistances and optical properties. Specifically developed brazing fillers were fine-tuned so that the joints of the ceramics improved in terms of their physical interactions, chemical reactions and ability to bond or key chemically and mechanically with the ceramic surfaces. Thereby, the electrical

  16. Electrically conductive ceramics and new joining technology for applications in HTR engineering

    International Nuclear Information System (INIS)

    Hille, Carmen; Lippmann, Wolfgang; Hurtado, Antonio

    2012-01-01

    Ceramic constructional components are quite extensively required for operation of high-temperature nuclear reactors. Functional ceramics, in addition to constructional ceramics, are increasingly coming into the focus of research. Ceramic materials are predestined for use at high temperatures and in corrosive atmospheres. Modification of silicon carbide (SiC) by targeted doping, for instance, produces a suitable material for the production of heating conductors and thermoelectric generators. As a construction material, silicon carbide (SiC) is especially interesting due to its very good thermal, mechanical and radiological properties. SiC, furthermore, performs well when activated by neutron irradiation, with the induced activation subsiding after only a few hours (). This property vector makes it an ideal starting material for use in a wide range of functional elements in high-temperature power engineering, particularly in high-temperature nuclear reactor engineering (e.g. V/HTR) including thermochemical plants for hydrogen generation or Synfuel production. In principle, it is possible to produce all-ceramic assemblies consisting of a thermoelectric generator and a sensor that can provide reliable measurement signals under extreme conditions in the high-temperature range without external power supply. This paper explains the feasibility of laser-joining such modified non-oxide ceramics, how to make electrically conductive joints, and thus, how to design complex assemblies. The parameters required for an optimal laser process to join ceramic materials were determined in extensive preliminary experiments. These investigations focused on the specific electrical resistances and optical properties. Specifically developed brazing fillers were fine-tuned so that the joints of the ceramics improved in terms of their physical interactions, chemical reactions and ability to bond or key chemically and mechanically with the ceramic surfaces. Thereby, the electrical

  17. Interaction of HEPES buffer with glass-ceramic scaffold: Can HEPES replace TRIS in SBF?

    Czech Academy of Sciences Publication Activity Database

    Rohanová, D.; Horkavcová, D.; Paidere, L.; Boccanccini, A. R.; Bozděchová, P.; Bezdička, Petr

    2018-01-01

    Roč. 106, č. 1 (2018), s. 143-152 ISSN 1552-4973 Institutional support: RVO:61388980 Keywords : in vitro test * simulated body fluid * HEPES buffer * glass-ceramic scaffold * biomaterial Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 3.189, year: 2016

  18. Brain nonoxidative carbohydrate consumption is not explained by export of an unknown carbon source

    DEFF Research Database (Denmark)

    Rasmussen, Peter; Nyberg, Nils; Jaroszewski, Jerzy W

    2010-01-01

    Brain activation provokes nonoxidative carbohydrate consumption and during exercise it is dominated by the cerebral uptake of lactate resulting in that up to approximately 1 mmol/ 100 g of glucose equivalents cannot be accounted for by cerebral oxygen uptake. The fate of this 'extra' carbohydrate...... be accounted for by changes in the NMR-derived plasma metabolome across the brain.Journal of Cerebral Blood Flow & Metabolism advance online publication, 24 February 2010; doi:10.1038/jcbfm.2010.25....

  19. Modelling for near-surface interaction of lithium ceramics and sweep-gas by use of cellular automation

    International Nuclear Information System (INIS)

    Shimura, K.; Terai, T.; Yamawaki, M.; Yamaguchi, K.

    2003-01-01

    Tritium release from the lithium ceramics as a fusion reactor breeder material is strongly affected by the composition of the sweep-gas as result of its influences with the material's surface. The typical surface processes which play important roles are adsorption, desorption and interaction between vacancy site and the constituents of the sweep-gas. Among a large number of studies and models, yet it seems to be difficult to model the overall behaviour of those processes due to its complex time-transient nature. In the present work the coarse grained atomic simulation based on the Cellular Automaton (CA) is used to model the dynamics of near-surface interaction between Li 2 O surface and sweep-gas that is consisting of a noble gas, hydrogen gas and water vapour. (author)

  20. Application of ceramic and glass materials in nuclear power plants

    International Nuclear Information System (INIS)

    Hamnabard, Z.

    2008-01-01

    Ceramic and glass are high temperature materials that can be used in many fields of application in nuclear industries. First, it is known that nuclear fuel UO 2 is a ceramic material. Also, ability to absorb neutrons without forming long lived radio-nuclides make the non-oxide ceramics attractive as an absorbent for neutron radiation arising in nuclear power plants. Glass-ceramic materials are a new type of ceramic that produced by the controlled nucleation and crystallization of glass, and have several advantages such as very low or null porosity, uniformity of microstructure, high chemical resistance etc. over conventional powder processed ceramics. These ceramic materials are synthesized in different systems based on their properties and applications. In nuclear industries, those are resistant to leaching and radiation damage for thousands of years, Such as glass-ceramics designed for radioactive waste immobilization and machinable glass-ceramics are used. This article introduces requirements of different glass and ceramic materials used in nuclear power plants and have been focused on developments in properties and application of them

  1. Mechanical behavior of high strength ceramic fibers at high temperatures

    Science.gov (United States)

    Tressler, R. E.; Pysher, D. J.

    1991-01-01

    The mechanical behavior of commercially available and developmental ceramic fibers, both oxide and nonoxide, has been experimentally studied at expected use temperatures. In addition, these properties have been compared to results from the literature. Tensile strengths were measured for three SiC-based and three oxide ceramic fibers for temperatures from 25 C to 1400 C. The SiC-based fibers were stronger but less stiff than the oxide fibers at room temperature and retained more of both strength and stiffness to high temperatures. Extensive creep and creep-rupture experiments have been performed on those fibers from this group which had the best strengths above 1200 C in both single filament tests and tests of fiber bundles. The creep rates for the oxides are on the order of two orders of magnitude faster than the polymer derived nonoxide fibers. The most creep resistant filaments available are single crystal c-axis sapphire filaments. Large diameter CVD fabricated SiC fibers are the most creep and rupture resistant nonoxide polycrystalline fibers tested to date.

  2. Impact of the Interaction between Aquatic Humic Substances and Algal Organic Matter on the Fouling of a Ceramic Microfiltration Membrane.

    Science.gov (United States)

    Zhang, Xiaolei; Fan, Linhua; Roddick, Felicity A

    2018-02-01

    The influence of the interaction between aquatic humic substances and the algal organic matter (AOM) derived from Microcystis aeruginosa on the fouling of a ceramic microfiltration (MF) membrane was studied. AOM alone resulted in a significantly greater flux decline compared with Suwannee River humic acid (HA), and fulvic acid (FA). The mixture of AOM with HA and FA exhibited a similar flux pattern as the AOM alone in the single-cycle filtration tests, indicating the flux decline may be predominantly controlled by the AOM in the early filtration cycles. The mixtures resulted in a marked increase in irreversible fouling resistance compared with all individual feed solutions. An increase in zeta potential was observed for the mixtures (becoming more negatively charged), which was in accordance with the increased reversible fouling resistance resulting from enhanced electrostatic repulsion between the organic compounds and the negatively-charged ceramic membrane. Dynamic light scattering (DLS) and size exclusion chromatography analyses showed an apparent increase in molecular size for the AOM-humics mixtures, and some UV-absorbing molecules in the humics appeared to participate in the formation of larger aggregates with the AOM, which led to greater extent of pore plugging and hence resulted in higher irreversible fouling resistance.

  3. Impact of the Interaction between Aquatic Humic Substances and Algal Organic Matter on the Fouling of a Ceramic Microfiltration Membrane

    Directory of Open Access Journals (Sweden)

    Xiaolei Zhang

    2018-02-01

    Full Text Available The influence of the interaction between aquatic humic substances and the algal organic matter (AOM derived from Microcystis aeruginosa on the fouling of a ceramic microfiltration (MF membrane was studied. AOM alone resulted in a significantly greater flux decline compared with Suwannee River humic acid (HA, and fulvic acid (FA. The mixture of AOM with HA and FA exhibited a similar flux pattern as the AOM alone in the single-cycle filtration tests, indicating the flux decline may be predominantly controlled by the AOM in the early filtration cycles. The mixtures resulted in a marked increase in irreversible fouling resistance compared with all individual feed solutions. An increase in zeta potential was observed for the mixtures (becoming more negatively charged, which was in accordance with the increased reversible fouling resistance resulting from enhanced electrostatic repulsion between the organic compounds and the negatively-charged ceramic membrane. Dynamic light scattering (DLS and size exclusion chromatography analyses showed an apparent increase in molecular size for the AOM-humics mixtures, and some UV-absorbing molecules in the humics appeared to participate in the formation of larger aggregates with the AOM, which led to greater extent of pore plugging and hence resulted in higher irreversible fouling resistance.

  4. In vitro antibacterial activity of oxide and non-oxide bioceramics for arthroplastic devices: II. Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Boschetto, Francesco; Toyama, Nami; Horiguchi, Satoshi; Bock, Ryan M; McEntire, Bryan J; Adachi, Tetsuya; Marin, Elia; Zhu, Wenliang; Mazda, Osam; Bal, B Sonny; Pezzotti, Giuseppe

    2018-04-30

    The metabolic response of Gram-positive Staphylococcus epidermidis (S. epidermidis) bacteria to bioceramic substrates was probed by means of Fourier transform infrared spectroscopy (FTIR). Oxide zirconia-toughened alumina (ZTA) and non-oxide silicon nitride (Si3N4) substrates were tested. Bacteria exposed to silica glass substrates were used as a control. S. epidermidis, a major cause of periprosthetic infections, was screened to obtain a precise time-lapse knowledge of its molecular composition and to mechanistically understand its interaction with different substrates. At the molecular level, the structure of proteins, lipids, nucleic acid, and aromatic amino acids evolved with time in response to different substrates. In combination with statistical validation and local pH measurements, a chemical lysis mechanism was spectroscopically observed in situ on the Si3N4 substrates. Utilization of FTIR in this study avoided fluorescence noise which occurred while probing the ZTA samples with Raman spectroscopy in a companion paper. The substrate-driven dynamics of polysaccharide and peptide variations in the bacterial cell wall, peculiar to Si3N4 bioceramics, are elucidated.

  5. Modeling of Oxidized PTH (oxPTH) and Non-oxidized PTH (n-oxPTH) Receptor Binding and Relationship of Oxidized to Non-Oxidized PTH in Children with Chronic Renal Failure, Adult Patients on Hemodialysis and Kidney Transplant Recipients

    DEFF Research Database (Denmark)

    Hocher, Berthold; Oberthür, Dominik; Slowinski, Torsten

    2013-01-01

    Background: The biological properties of oxidized and non-oxidized PTH are substantially different. Oxidized PTH (oxPTH) loses its PTH receptor-stimulating properties, whereas non-oxidized PTH (n-oxPTH) is a full agonist of the receptor. This was described in more than 20 well published studies i......PTH measures describes most likely oxidative stress in patients with renal failure rather than the PTH hormone status. This, however, needs to be demonstrated in further clinical studies. © 2013 S. Karger AG, Basel......., we performed modeling of the interaction of either oxPTH or n-oxPTH with the PTH receptor using biophysical structure approaches. Results: The children had the highest mean as well as maximum n-oxPTH concentrations as compared to adult patients (both patients on dialysis as well as kidney transplant......-oxPTH. This indicated that PTH oxidation may induce refolding of PTH and hence alters PTH-PTH receptor interaction via oxidation induced three-dimensional structure alteration of PTH. Conclusion: A huge proportion of circulating PTH measured by current state-of-the-art assay systems is oxidized and thus...

  6. Non-oxidic nanoscale composites: single-crystalline titanium carbide nanocubes in hierarchical porous carbon monoliths.

    Science.gov (United States)

    Sonnenburg, Kirstin; Smarsly, Bernd M; Brezesinski, Torsten

    2009-05-07

    We report the preparation of nanoscale carbon-titanium carbide composites with carbide contents of up to 80 wt%. The synthesis yields single-crystalline TiC nanocubes 20-30 nm in diameter embedded in a hierarchical porous carbon matrix. These composites were generated in the form of cylindrical monoliths but can be produced in various shapes using modern sol-gel and nanocasting methods in conjunction with carbothermal reduction. The monolithic material is characterized by a combination of microscopy, diffraction and physisorption. Overall, the results presented in this work represent a concrete design template for the synthesis of non-oxidic nanoscale composites with high surface areas.

  7. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  8. Machining of insulation ZrO2 ceramics by EDM using graphite electrode

    International Nuclear Information System (INIS)

    Tani, T.; Okada, M.; Fukuzawa, Y.; Mohri, N.

    1998-01-01

    As we proposed and reported before, insulating ceramics may be made into machinable materials with electrical discharge machining method by using an assisting electrode method. The machining properties depend on the formation mechanism of carbonization layer which has electrical conductivity on the ceramics surface during discharge. A big difference in machinability occurs between oxide and non-oxide ceramics. When ZrO 2 ceramics are machined with a copper tool electrode which was used for a machining of the non-oxide ceramics Si 3 N 4 , the electrical conductive layer is not formed on the machined surface uniformly. In this paper, in order to activate a carbonization reaction on the ceramics surface during discharge, the use of a porous graphite tool electrode is described. As a result of that, carbonized reaction occurs actively on the discharge gap and the uniform carbonized layer adheres to the machined surface. The surface roughness is much improved compared with previous machining conditions. Copyright (1998) Australasian Ceramic Society

  9. Interactions of aqueous NOM with nanoscale TiO2: implications for ceramic membrane filtration-ozonation hybrid process.

    Science.gov (United States)

    Kim, Jeonghwan; Shan, Wenqian; Davies, Simon H R; Baumann, Melissa J; Masten, Susan J; Tarabara, Volodymyr V

    2009-07-15

    The combined effect of pH and calcium on the interactions of nonozonated and ozonated natural organic matter (NOM) with nanoscale TiO2 was investigated. The approach included characterization of TiO2 nanoparticles and NOM, extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) modeling of NOM-TiO2 and NOM-NOM interactions, batch study on the NOM adsorption onto TiO2 surface, and bench-scale study on the treatment of NOM-containing feed waters using a hybrid process that combines ozonation and ultrafiltration with a 5 kDa ceramic (TiO2 surface) membrane. It was demonstrated that depending on pH and TiO2 loading, the adsorption of NOM species is controlled by either the availability of divalent cations or by preozonation of NOM. XDLVO surface energy analysis predicts NOM adsorption onto TiO2 in the ozone-controlled regime but not in the calcium-controlled regime. In both regimes, short-range NOM-NOM and NOM-TiO2 interactions were governed by acid-base and van der Waals forces, whereas the role of electrostatic forces was relatively insignificant. Ozonation increased the surface energy of NOM, contributing to the hydrophilic repulsion component of the NOM-NOM and NOM-TiO2 interactions. In the calcium-controlled regime, neither NOM-TiO2 nor NOM-NOM interaction controlled adsorption. Non-XDLVO interactions such as intermolecular bridging by calcium were hypothesized to be responsible for the observed adsorption behavior. Adsorption data proved to be highly predictive of the permeate flux performance.

  10. Influence of fuel composition on the non-oxidizing heating of steel in a waste gas atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Minkler, W [LOI Industrieofenanlagen G.m.b.H., Essen (Germany, F.R.)

    1979-04-01

    On the basis of a number of graphs and data on theoretical combustion temperatures and the difference between the heating value of the fuel and the waste gas in respect of 1 m/sup 3/ of waste gas, the author demonstrates the influence of fuel composition on the non-oxidizing heating of steel in a waste gas atmosphere derived from five different fuels. A rotary-hearth furnace is described for the non-oxidizing heating of pressings from plain carbon and alloy steel.

  11. Preliminary experiments to simulate glass/electrode interactions within a Joule Ceramic Melter

    International Nuclear Information System (INIS)

    Dalton, J.T.; Paige, E.L.; Sutcliffe, P.W.

    1986-01-01

    Preliminary isothermal corrosion tests have been made on Inconel 690 coupon samples immersed in Harvest II M9 glass with and without excess additions of Li 2 O (1.5%) and RuO 2 (20%) together with TeO 2 (2%) at 1200 0 C for periods up to 100 hours. Inconel 690 corrosion and the products and ruthenium redox conditions within the glass approximate to those observed in the 1/3rd scale Joule Ceramic Melter operations. Corrosion takes place by an oxidation mechanism to form a chromium-rich surface oxide, and dissolution of this surface oxide by the surrounding glass. Additions of excess Li 2 O increase the corrosion rate of Inconel 690, whereas RuO 2 + TeO 2 are neutral. The latter however have a marked effect in lowering the room temperature resistivity by at least 5 orders of magnitude even though relatively small fraction of the RuO 2 precipitates were reduced to ruthenium metal. (author)

  12. Improvement of microstructure and mechanical properties of high dense SiC ceramics manufactured by high-speed hot pressing

    International Nuclear Information System (INIS)

    Voyevodin, V.; Sayenko, S.; Lobach, K.; Tarasov, R.; Zykova, A.; Svitlychnyi, Ye.; Surkov, A.; Abelentsev, V.; Ghaemi, H.; Szkodo, M.; Gajowiec, G.; Kmiec, M.; Antoszkiewicz, M.

    2017-01-01

    Non-oxide ceramics possess high physical-mechanical properties, corrosion and radiation resistance, which can be used as a protective materials for radioactive wastes disposal. The aim of the present study was the manufacturing of high density SiC ceramics with advanced physical and mechanical parameters. The high performance on the properties of produced ceramics was determined by the dense and monolithic structure. The densified silicon carbide samples possessed good mechanical strength, with a high Vickers micro hardness up to 28.5 GPa.

  13. Metabolic basis of ethanol-induced cytotoxicity in recombinant HepG2 cells: Role of nonoxidative metabolism

    International Nuclear Information System (INIS)

    Wu Hai; Cai Ping; Clemens, Dahn L.; Jerrells, Thomas R.; Ansari, G.A. Shakeel; Kaphalia, Bhupendra S.

    2006-01-01

    Chronic alcohol abuse, a major health problem, causes liver and pancreatic diseases and is known to impair hepatic alcohol dehydrogenase (ADH). Hepatic ADH-catalyzed oxidation of ethanol is a major pathway for the ethanol disposition in the body. Hepatic microsomal cytochrome P450 (CYP2E1), induced in chronic alcohol abuse, is also reported to oxidize ethanol. However, impaired hepatic ADH activity in a rat model is known to facilitate a nonoxidative metabolism resulting in formation of nonoxidative metabolites of ethanol such as fatty acid ethyl esters (FAEEs) via a nonoxidative pathway catalyzed by FAEE synthase. Therefore, the metabolic basis of ethanol-induced cytotoxicity was determined in HepG2 cells and recombinant HepG2 cells transfected with ADH (VA-13), CYP2E1 (E47) or ADH + CYP2E1 (VL-17A). Western blot analysis shows ADH deficiency in HepG2 and E47 cells, compared to ADH-overexpressed VA-13 and VL-17A cells. Attached HepG2 cells and the recombinant cells were incubated with ethanol, and nonoxidative metabolism of ethanol was determined by measuring the formation of FAEEs. Significantly higher levels of FAEEs were synthesized in HepG2 and E47 cells than in VA-13 and VL-17A cells at all concentrations of ethanol (100-800 mg%) incubated for 6 h (optimal time for the synthesis of FAEEs) in cell culture. These results suggest that ADH-catalyzed oxidative metabolism of ethanol is the major mechanism of its disposition, regardless of CYP2E1 overexpression. On the other hand, diminished ADH activity facilitates nonoxidative metabolism of ethanol to FAEEs as found in E47 cells, regardless of CYP2E1 overexpression. Therefore, CYP2E1-mediated oxidation of ethanol could be a minor mechanism of ethanol disposition. Further studies conducted only in HepG2 and VA-13 cells showed lower ethanol disposition and ATP concentration and higher accumulation of neutral lipids and cytotoxicity (apoptosis) in HepG2 cells than in VA-13 cells. The apoptosis observed in HepG2 vs

  14. Interfacial interactions between Skeletonema costatum extracellular organic matter and metal oxides: Implications for ceramic membrane filtration

    KAUST Repository

    Zaouri, Noor A

    2017-03-21

    In the current study, the interfacial interactions between the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) extracellular organic matter (EOM) and ZrO2 or Al2O3, were investigated by atomic force microscopy (AFM). HMW SKC-EOM was rigorously characterized and described as a hydrophilic organic compound mainly comprised of polysaccharide-like structures. Lipids and proteins were also observed, although in lower abundance. HMW SKC-EOM displayed attractive forces during approaching (i.e., leading to jump-to-contact events) and adhesion forces during retracting regime to both metal oxides at all solution conditions tested, where electrostatics and hydrogen bonding were suggested as dominant interacting mechanisms. However, the magnitude of these forces was significantly higher on ZrO2 surfaces, irrespective of cation type (Na+ or Ca2+) or concentration. Interestingly, while HMW SKC-EOM interacting forces to Al2O3 were practically insensitive to solution chemistry, the interactions between ZrO2 and HMW SKC-EOM increased with increasing cation concentration in solution. The structure, and lower charge, hydrophilicity, and density of hydroxyl groups on ZrO2 surface would play a key role on favoring zirconia associations with HMW SKC-EOM. The current results contribute to advance our fundamental understanding of Algogenic Organic Matter (AOM) interfacial interactions with metal oxides (i.e., AOM membrane fouling), and would highly assist in the proper selection of membrane material during episodic algal blooms.

  15. Interfacial interactions between Skeletonema costatum extracellular organic matter and metal oxides: Implications for ceramic membrane filtration

    KAUST Repository

    Zaouri, Noor A.; Gutierrez, Leonardo; Dramas, Laure; Garces, Daniel; Croue, Jean-Philippe

    2017-01-01

    In the current study, the interfacial interactions between the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) extracellular organic matter (EOM) and ZrO2 or Al2O3, were investigated by atomic force microscopy (AFM). HMW SKC-EOM was rigorously characterized and described as a hydrophilic organic compound mainly comprised of polysaccharide-like structures. Lipids and proteins were also observed, although in lower abundance. HMW SKC-EOM displayed attractive forces during approaching (i.e., leading to jump-to-contact events) and adhesion forces during retracting regime to both metal oxides at all solution conditions tested, where electrostatics and hydrogen bonding were suggested as dominant interacting mechanisms. However, the magnitude of these forces was significantly higher on ZrO2 surfaces, irrespective of cation type (Na+ or Ca2+) or concentration. Interestingly, while HMW SKC-EOM interacting forces to Al2O3 were practically insensitive to solution chemistry, the interactions between ZrO2 and HMW SKC-EOM increased with increasing cation concentration in solution. The structure, and lower charge, hydrophilicity, and density of hydroxyl groups on ZrO2 surface would play a key role on favoring zirconia associations with HMW SKC-EOM. The current results contribute to advance our fundamental understanding of Algogenic Organic Matter (AOM) interfacial interactions with metal oxides (i.e., AOM membrane fouling), and would highly assist in the proper selection of membrane material during episodic algal blooms.

  16. Interfacial interactions between Skeletonema costatum extracellular organic matter and metal oxides: Implications for ceramic membrane filtration.

    Science.gov (United States)

    Zaouri, Noor; Gutierrez, Leonardo; Dramas, Laure; Garces, Daniel; Croue, Jean-Philippe

    2017-06-01

    In the current study, the interfacial interactions between the high molecular weight (HMW) compounds of Skeletonema costatum (SKC) extracellular organic matter (EOM) and ZrO 2 or Al 2 O 3 , were investigated by atomic force microscopy (AFM). HMW SKC-EOM was rigorously characterized and described as a hydrophilic organic compound mainly comprised of polysaccharide-like structures. Lipids and proteins were also observed, although in lower abundance. HMW SKC-EOM displayed attractive forces during approaching (i.e., leading to jump-to-contact events) and adhesion forces during retracting regime to both metal oxides at all solution conditions tested, where electrostatics and hydrogen bonding were suggested as dominant interacting mechanisms. However, the magnitude of these forces was significantly higher on ZrO 2 surfaces, irrespective of cation type (Na + or Ca 2+ ) or concentration. Interestingly, while HMW SKC-EOM interacting forces to Al 2 O 3 were practically insensitive to solution chemistry, the interactions between ZrO 2 and HMW SKC-EOM increased with increasing cation concentration in solution. The structure, and lower charge, hydrophilicity, and density of hydroxyl groups on ZrO 2 surface would play a key role on favoring zirconia associations with HMW SKC-EOM. The current results contribute to advance our fundamental understanding of Algogenic Organic Matter (AOM) interfacial interactions with metal oxides (i.e., AOM membrane fouling), and would highly assist in the proper selection of membrane material during episodic algal blooms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. CO2 and Nd:YAP laser interaction with lithium disilicate and Zirconia dental ceramics: A preliminary study

    Science.gov (United States)

    Rocca, Jean-Paul; Fornaini, Carlo; Brulat-Bouchard, Nathalie; Bassel Seif, Samy; Darque-Ceretti, Evelyne

    2014-04-01

    Lithium disilicate and Zirconia ceramics offer a high level of accuracy when used in prosthetic dentistry. Their bonding using different resins is highly dependent on micro-mechanical interlocking and adhesive chemical bonding. Investigation of the performances of high strength ceramics when their surface is modified for chemical and mechanical bonding is then required. The aim of this study is to investigate the possibility of using laser for surface treatment of different high strength CAD/CAM ceramics and thus to improve their mechanical and chemical properties. Thirty two CAD/CAM ceramic discs were divided into two different groups: lithium disilicate ceramics (IPS e.max CAD®, Ivoclar, Vivadent, Italy) and Zirconia ceramics (IPS e.max ZirCAD®, Ivoclar, Vivadent, Italy). The Laser surface treatment was performed by Carbon Dioxide laser (Dream Pulse Laser®, Daeshin Enterprise Corp., Korea) at 20 W, 25 W and 30 W CW and by Neodymium Yttrium Aluminum Perovskite laser (Nd:YAP Lokki®, Lobel Medical, France) at 10 W and 30 Hz. Physical modifications of the irradiated ceramic discs were observed by scanning electron microscopy (SEM) and chemically analyzed by Energy-Dispersive Spectroscopy (EDS). Surface wettability was tested using the water drop test and the crystalline structure was investigated using X-ray diffraction (XRD). The macroscopic observation showed a shinier structure in all the groups, while at the SEM observation only CO2 25 W and 30 W treated groups showed cracks and fissures. In the conditions of this study, CO2 laser and Nd:YAP laser with the parameters used create chemical and physical surface modifications of the ceramics, indicating the possibility of an improvement in adhesion of the tested ceramics.

  18. Evaluation of R-curves in ceramic materials based on bridging interactions

    International Nuclear Information System (INIS)

    Fett, T.; Munz, D.

    1991-10-01

    In coarse-grained alumina the crack growth resistance increases with increasing crack extension due to crack-border interactions. The crack shielding stress intensity factor can be calculated from the relation between the bridging stresses and the crack opening displacement. The parameters of this relation can be obtained from experimental results on stable or subcritical crack extension. Finally the effected of the R-curve on the behaviour of components with small cracks is discussed. (orig.) [de

  19. Coating system to permit direct brazing of ceramics

    Science.gov (United States)

    Cadden, Charles H.; Hosking, F. Michael

    2003-01-01

    This invention relates to a method for preparing the surface of a ceramic component that enables direct brazing using a non-active braze alloy. The present invention also relates to a method for directly brazing a ceramic component to a ceramic or metal member using this method of surface preparation, and to articles produced by using this brazing method. The ceramic can be high purity alumina. The method comprises applying a first coating of a silicon-bearing oxide material (e.g. silicon dioxide or mullite (3Al.sub.2 O.sub.3.2SiO.sub.2) to the ceramic. Next, a thin coating of active metal (e.g. Ti or V) is applied. Finally, a thicker coating of a non-active metal (e.g. Au or Cu) is applied. The coatings can be applied by physical vapor deposition (PVD). Alternatively, the active and non-active metals can be co-deposited (e.g. by sputtering a target made of mullite). After all of the coatings have been applied, the ceramic can be fired at a high temperature in a non-oxidizing environment to promote diffusion, and to enhance bonding of the coatings to the substrate. After firing, the metallized ceramic component can be brazed to other components using a conventional non-active braze alloy. Alternatively, the firing and brazing steps can be combined into a single step. This process can replace the need to perform a "moly-manganese" metallization step.

  20. INTERACTION STUDIES OF CERAMIC VACUUM PLASMA SPRAYING FOR THE MELTING CRUCIBLE MATERIALS

    Directory of Open Access Journals (Sweden)

    JONG HWAN KIM

    2013-10-01

    Full Text Available Candidate coating materials for re-usable metallic nuclear fuel crucibles, TaC, TiC, ZrC, ZrO2, and Y2O3, were plasma-sprayed onto a niobium substrate. The microstructure of the plasma-sprayed coatings and thermal cycling behavior were characterized, and U-Zr melt interaction studies were carried out. The TaC and Y2O3 coating layers had a uniform thickness, and high density with only a few small closed pores showing good consolidation, while the ZrC, TiC, and ZrO2 coatings were not well consolidated with a considerable amount of porosity. Thermal cycling tests showed that the adhesion of the TiC, ZrC, and ZrO2 coating layers with niobium was relatively weak compared to the TaC and Y2O3 coatings. The TaC and Y2O3 coatings had better cycling characteristics with no interconnected cracks. In the interaction studies, ZrC and ZrO2 coated rods showed significant degradations after exposure to U-10 wt.% Zr melt at 1600°C for 15 min., but TaC, TiC, and Y2O3 coatings showed good compatibility with U-Zr melt.

  1. Proceedings of the national symposium on materials and processing: functional glass/glass-ceramics, advanced ceramics and high temperature materials

    International Nuclear Information System (INIS)

    Ghosh, A.; Sahu, A.K.; Viswanadham, C.S.; Ramanathan, S.; Hubli, R.C.; Kothiyal, G.P.

    2012-10-01

    With the development of materials science it is becoming increasingly important to process some novel materials in the area of glass, advanced ceramics and high temperature metals/alloys, which play an important role in the realization of many new technologies. Such applications demand materials with tailored specifications. Glasses and glass-ceramics find exotic applications in areas like radioactive waste storage, optical communication, zero thermal expansion coefficient telescopic mirrors, human safety gadgets (radiation resistance windows, bullet proof apparels, heat resistance components etc), biomedical (implants, hyperthermia treatment, bone cement, bone grafting etc). Advanced ceramic materials have been beneficial in biomedical applications due to their strength, biocompatibility and wear resistance. Non-oxide ceramics such as carbides, borides, silicides, their composites, refractory metals and alloys are useful as structural and control rod components in high temperature fission/ fusion reactors. Over the years a number of novel processing techniques like selective laser melting, microwave heating, nano-ceramic processing etc have emerged. A detailed understanding of the various aspects of synthesis, processing and characterization of these materials provides the base for development of novel technologies for different applications. Keeping this in mind and realizing the need for taking stock of such developments a National Symposium on Materials and Processing -2012 (MAP-2012) was planned. The topics covered in the symposium are ceramics, glass/glass-ceramics and metals and materials. Papers relevant to INIS are indexed separately

  2. CO sub 2 laser cutting of ceramics and metal-ceramic composites. CO sub 2 -Laserschneiden von Keramik und Metall-Keramik-Verbunden

    Energy Technology Data Exchange (ETDEWEB)

    Wielage, B.; Drozak, J. (Dortmund Univ. (Germany, F.R.). Lehrstuhl fuer Werkstofftechnologie)

    1991-01-01

    Oxide and non-oxide ceramics as well as active brazed and APS-sprayed metal-ceramic composites are cut by means of a 1500 Watt CO{sub 2} laser. In this context, the experience from ceramics cutting applications is applied to laser cutting of composites. The process parameters, which are adjusted to the property profile and the thickness of the material, permit cutting of ceramics of a maximum thickness of 10 mm with optimal cut edge quality and minimum damage to the material. The parameter sets were also optimized in the case of laser-cut active brazed and plasma-sprayed composites. In terms of roughness, composition and structure of the cut edge, composites can be optimally cut using oxygen as process gas. (orig.).

  3. The interaction between the permanent magnet and ceramic superconductor with organic filler

    International Nuclear Information System (INIS)

    Woźny, L; Kisiel, A; Garbera, A

    2016-01-01

    The aim of the study was to examine the phenomenon of magnetic levitation for YBaCuO superconducting samples in pure form and with epoxy resin content of 40%. Samples of superconductors were prepared by the standard reaction in the solid state. The forces of interaction between the superconductor and neodymium permanent magnet were measured. Samples with epoxy resin fillers had significantly smaller levitation force than the sample of the sintered superconductors. This is due to a much lower content of pure superconducting material in the sample volume (about 60% of the YBaCuO). However, the obvious advantage of such samples is the possibility of preparation superconductors with complicated shapes, eg. for use in a superconducting bearings or other devices. (paper)

  4. Tight ceramic UF membrane as RO pre-treatment: the role of electrostatic interactions on phosphate rejection.

    Science.gov (United States)

    Shang, Ran; Verliefde, Arne R D; Hu, Jingyi; Zeng, Zheyi; Lu, Jie; Kemperman, Antoine J B; Deng, Huiping; Nijmeijer, Kitty; Heijman, Sebastiaan G J; Rietveld, Luuk C

    2014-01-01

    Phosphate limitation has been reported as an effective approach to inhibit biofouling in reverse osmosis (RO) systems for water purification. The rejection of dissolved phosphate by negatively charged TiO2 tight ultrafiltration (UF) membranes (1 kDa and 3 kDa) was observed. These membranes can potentially be adopted as an effective process for RO pre-treatment in order to constrain biofouling by phosphate limitation. This paper focuses on electrostatic interactions during tight UF filtration. Despite the larger pore size, the 3 kDa ceramic membrane exhibited greater phosphate rejection than the 1 kDa membrane, because the 3 kDa membrane has a greater negative surface charge and thus greater electrostatic repulsion against phosphate. The increase of pH from 6 to 8.5 led to a substantial increase in phosphate rejection by both membranes due to increased electrostatic repulsion. At pH 8.5, the maximum phosphate rejections achieved by the 1 kDa and 3 kDa membrane were 75% and 86%, respectively. A Debye ratio (ratio of the Debye length to the pore radius) is introduced in order to evaluate double layer overlapping in tight UF membranes. Threshold Debye ratios were determined as 2 and 1 for the 1 kDa and 3 kDa membranes, respectively. A Debye ratio below the threshold Debye ratio leads to dramatically decreased phosphate rejection by tight UF membranes. The phosphate rejection by the tight UF, in combination with chemical phosphate removal by coagulation, might accomplish phosphate-limited conditions for biological growth and thus prevent biofouling in the RO systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Advanced Ceramics

    International Nuclear Information System (INIS)

    1989-01-01

    The First Florida-Brazil Seminar on Materials and the Second State Meeting about new materials in Rio de Janeiro State show the specific technical contribution in advanced ceramic sector. The others main topics discussed for the development of the country are the advanced ceramic programs the market, the national technic-scientific capacitation, the advanced ceramic patents, etc. (C.G.C.) [pt

  6. Skeletal muscle insulin signaling defects downstream of phosphatidylinositol 3-kinase at the level of akt are associated with impaired nonoxidative glucose disposal in HIV lipodystrophy

    DEFF Research Database (Denmark)

    Haugaard, Steen B.; Andersen, Ove; Madsbad, Sten

    2005-01-01

    More than 40% of HIV-infected patients on highly active antiretroviral therapy (HAART) experience fat redistribution (lipodystrophy), a syndrome associated with insulin resistance primarily affecting insulin-stimulated nonoxidative glucose metabolism (NOGM(ins)). Skeletal muscle biopsies, obtained...

  7. Exposure to lead in water and cysteine non-oxidative metabolism in Pelophylax ridibundus tissues

    International Nuclear Information System (INIS)

    Kaczor, Marta; Sura, Piotr; Bronowicka-Adamska, Patrycja; Wróbel, Maria

    2013-01-01

    Chronic, low-level exposure to metals is an increasing global problem. Lead is an environmentally persistent toxin that causes many lead-related pathologies, directly affects tissues and cellular components or exerts an effect of the generation of reactive oxygen species causing a diminished level of available sulfhydryl antioxidant reserves. Cysteine is one of substrates in the synthesis of glutathione – the most important cellular antioxidant, and it may also undergo non-oxidative desulfuration that produces compounds containing sulfane sulfur atoms. The aim of the experiment was to examine changes of the non-oxidative metabolism of cysteine and the levels of cysteine and glutathione in the kidneys, heart, brain, liver and muscle of Marsh frogs (Pelophylax ridibundus) exposed to 28 mg/L Pb(NO 3 ) 2 for 10 days. The activities of sulfurtransferases, enzymes related to the sulfane sulfur metabolism – 3-mercaptopyruvate sulfurtransfearse, γ-cystathionase and rhodanese – were detected in tissue homogenates. The activity of sulfurtransferases was much higher in the kidneys of frogs exposed to lead in comparison to control frogs, not exposed to lead. The level of sulfane sulfur remained unchanged. Similarly, the total level of cysteine did not change significantly. The total levels of glutathione and the cysteine/cystine and GSH/GSSG ratios were elevated. Thus, it seems that the exposure to lead intensified the metabolism of sulfane sulfur and glutathione synthesis in the kidneys. The results presented in this work not only confirm the participation of GSH in the detoxification of lead ions and/or products appearing in response to their presence, such as reactive oxygen species, but also indicate the involvement of sulfane sulfur and rhodanese in this process (e.g. brain). As long as the expression of enzymatic proteins (rhodanese, MPST and CST) is not examined, no answer will be provided to the question whether changes in their activity are due to differences

  8. Exposure to lead in water and cysteine non-oxidative metabolism in Pelophylax ridibundus tissues

    Energy Technology Data Exchange (ETDEWEB)

    Kaczor, Marta [Jagiellonian University Medical College, Kopernika 7, 31-034 Krakow (Poland); Sura, Piotr [Department of Human Developmental Biology, Jagiellonian University Medical College, Kopernika 7, 31-034 Krakow (Poland); Bronowicka-Adamska, Patrycja [Jagiellonian University Medical College, Kopernika 7, 31-034 Krakow (Poland); Wrobel, Maria, E-mail: mbwrobel@cyf-kr.edu.pl [Jagiellonian University Medical College, Kopernika 7, 31-034 Krakow (Poland)

    2013-02-15

    Chronic, low-level exposure to metals is an increasing global problem. Lead is an environmentally persistent toxin that causes many lead-related pathologies, directly affects tissues and cellular components or exerts an effect of the generation of reactive oxygen species causing a diminished level of available sulfhydryl antioxidant reserves. Cysteine is one of substrates in the synthesis of glutathione - the most important cellular antioxidant, and it may also undergo non-oxidative desulfuration that produces compounds containing sulfane sulfur atoms. The aim of the experiment was to examine changes of the non-oxidative metabolism of cysteine and the levels of cysteine and glutathione in the kidneys, heart, brain, liver and muscle of Marsh frogs (Pelophylax ridibundus) exposed to 28 mg/L Pb(NO{sub 3}){sub 2} for 10 days. The activities of sulfurtransferases, enzymes related to the sulfane sulfur metabolism - 3-mercaptopyruvate sulfurtransfearse, {gamma}-cystathionase and rhodanese - were detected in tissue homogenates. The activity of sulfurtransferases was much higher in the kidneys of frogs exposed to lead in comparison to control frogs, not exposed to lead. The level of sulfane sulfur remained unchanged. Similarly, the total level of cysteine did not change significantly. The total levels of glutathione and the cysteine/cystine and GSH/GSSG ratios were elevated. Thus, it seems that the exposure to lead intensified the metabolism of sulfane sulfur and glutathione synthesis in the kidneys. The results presented in this work not only confirm the participation of GSH in the detoxification of lead ions and/or products appearing in response to their presence, such as reactive oxygen species, but also indicate the involvement of sulfane sulfur and rhodanese in this process (e.g. brain). As long as the expression of enzymatic proteins (rhodanese, MPST and CST) is not examined, no answer will be provided to the question whether changes in their activity are due to

  9. FY 1997 report on the study on development of corrosion-resistant ceramics for refuse incinerators; 1997 nendo chosa hokokusho (gomi shokyakuroyo taishoku ceramics zairyo no kaihatsu ni kansuru kenkyu)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    This paper describes development of structural materials for municipal refuse incinerators, in particular, high- temperature corrosion-resistant ceramics for inner walls. Unlike boiler tubes of which inner walls are cooled by water or water vapor, refractory for inner walls is subjected to high-temperature flame over 1000degC, corrosive gases such as HCl and SO2. and low-melting point corrosive dust such as chloride, sulfate and oxide under strong corrosive environment. Experiment was made on 14 kinds of ceramics including commercially available oxide system, non-oxide system and refractory system ceramics. Except graphite system ones, every ceramics, in particular, Al2O3, ZrO2, B4C-doped SiC and CVD-SiO showed superior properties. Commercially available ceramics, in particular, non-oxide system ones are very expensive. Since inner wall materials for refuse incinerators are heat-/corrosion-resistant consumption articles, it is suggested that improvement of reasonable oxide system ceramics or conventional SiC system ones is better. 73 refs., 89 figs., 39 tabs.

  10. Simultaneous determination of ethanol's four types of non-oxidative metabolites in human whole blood by liquid chromatography tandem mass spectrometry

    DEFF Research Database (Denmark)

    Zhang, Xinyu; Zheng, Feng; Lin, Zebin

    2017-01-01

    The importance of ethanol non-oxidative metabolites as the specific biomarkers of alcohol consumption in clinical and forensic settings is increasingly acknowledged. Simultaneous determination of these metabolites can provide a wealth of information like drinking habit and history, but it was dif......The importance of ethanol non-oxidative metabolites as the specific biomarkers of alcohol consumption in clinical and forensic settings is increasingly acknowledged. Simultaneous determination of these metabolites can provide a wealth of information like drinking habit and history...

  11. Exfoliation of non-oxidized graphene flakes for scalable conductive film.

    Science.gov (United States)

    Park, Kwang Hyun; Kim, Bo Hyun; Song, Sung Ho; Kwon, Jiyoung; Kong, Byung Seon; Kang, Kisuk; Jeon, Seokwoo

    2012-06-13

    The increasing demand for graphene has required a new route for its mass production without causing extreme damages. Here we demonstrate a simple and cost-effective intercalation based exfoliation method for preparing high quality graphene flakes, which form a stable dispersion in organic solvents without any functionalization and surfactant. Successful intercalation of alkali metal between graphite interlayers through liquid-state diffusion from ternary KCl-NaCl-ZnCl(2) eutectic system is confirmed by X-ray diffraction and X-ray photoelectric spectroscopy. Chemical composition and morphology analyses prove that the graphene flakes preserve their intrinsic properties without any degradation. The graphene flakes remain dispersed in a mixture of pyridine and salts for more than 6 months. We apply these results to produce transparent conducting (∼930 Ω/□ at ∼75% transmission) graphene films using the modified Langmuir-Blodgett method. The overall results suggest that our method can be a scalable (>1 g/batch) and economical route for the synthesis of nonoxidized graphene flakes.

  12. An engineered non-oxidative glycolysis pathway for acetone production in Escherichia coli.

    Science.gov (United States)

    Yang, Xiaoyan; Yuan, Qianqian; Zheng, Yangyang; Ma, Hongwu; Chen, Tao; Zhao, Xueming

    2016-08-01

    To find new metabolic engineering strategies to improve the yield of acetone in Escherichia coli. Results of flux balance analysis from a modified Escherichia coli genome-scale metabolic network suggested that the introduction of a non-oxidative glycolysis (NOG) pathway would improve the theoretical acetone yield from 1 to 1.5 mol acetone/mol glucose. By inserting the fxpk gene encoding phosphoketolase from Bifidobacterium adolescentis into the genome, we constructed a NOG pathway in E.coli. The resulting strain produced 47 mM acetone from glucose under aerobic conditions in shake-flasks. The yield of acetone was improved from 0.38 to 0.47 mol acetone/mol glucose which is a significant over the parent strain. Guided by computational analysis of metabolic networks, we introduced a NOG pathway into E. coli and increased the yield of acetone, which demonstrates the importance of modeling analysis for the novel metabolic engineering strategies.

  13. Uranium mobility in non-oxidizing brines: field and experimental evidence

    International Nuclear Information System (INIS)

    Giblin, A.M.; Appleyard, E.C.

    1987-01-01

    The present distribution of U in the Wollaston Sediments in Saskatchewan can be related to the movement of brines as revealed in Na-Ca-Mg-Cl-metasomes. Experiments were conducted at 60 and 200 0 C under stringently non-oxidizing conditions using solvents ranging from distilled water to a Ca-Na-K brine formulated to simulate the major element composition of the Salton Sea geothermal brines. The experiments were conducted on natural pitchblende (UOsub(2.67)) and synthetic uraninite (UOsub(2.01)). Natural pitchblende was more strongly dissolved than the synthetic uraninite, and the synthetic Salton Sea brine was a more potent solvent than distilled water, 1:4 diluted Salton Sea brine, or pure NaCl brine. Within analytical limits of detection the dissolved U is present in the uranous (U 4+ ) state. The evidence demonstrates empirically the mechanism of dissolution of naturally occurring U minerals in reduced brines and describes a geological case where this appears to have happened. (author)

  14. Interdisciplinary approach to cell–biomaterial interactions: biocompatibility and cell friendly characteristics of RKKP glass–ceramic coatings on titanium

    International Nuclear Information System (INIS)

    Ledda, Mario; Lolli, Maria Grazia; Lisi, Antonella; De Bonis, Angela; Teghil, Roberto; Bertani, Francesca Romana; Cacciotti, Ilaria; Ravaglioli, Antonio; Rau, Julietta V

    2015-01-01

    In this work, titanium (Ti) supports have been coated with glass–ceramic films for possible applications as biomedical implant materials in regenerative medicine. For the film preparation, a pulsed laser deposition (PLD) technique has been applied. The RKKP glass–ceramic material, used for coating deposition, was a sol–gel derived target of the following composition: Ca-19.4, P-4.6, Si-17.2, O-43.5, Na-1.7, Mg-1.3, F-7.2, K-0.2, La-0.8, Ta-4.1 (all in wt%). The prepared coatings were compact and uniform, characterised by a nanometric average surface roughness. The biocompatibility and cell-friendly properties of the RKKP glass–ceramic material have been tested. Cell metabolic activity and proliferation of human colon carcinoma CaCo-2 cells seeded on RKKP films showed the same exponential trend found in the control plastic substrates. By the phalloidin fluorescence analysis, no significant modifications in the actin distribution were revealed in cells grown on RKKP films. Moreover, in these cells a high mRNA expression of markers involved in protein synthesis, proliferation and differentiation, such as villin (VIL1), alkaline phosphatase (ALP1), β-actin (β-ACT), Ki67 and RPL34, was recorded. In conclusion, the findings, for the first time, demonstrated that the RKKP glass–ceramic material allows the adhesion, growth and differentiation of the CaCo-2 cell line. (paper)

  15. Ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  16. Sustained nonoxidative glucose utilization and depletion of glycogen in reperfused canine myocardium

    International Nuclear Information System (INIS)

    Schwaiger, M.; Neese, R.A.; Araujo, L.

    1989-01-01

    Ischemically injured reperfused myocardium is characterized by increased 18F-fluorodeoxyglucose uptake as demonstrated by positron emission tomography. To elucidate the metabolic fate of exogenous glucose entering reperfused myocardium, D-[6-14C] glucose and L-[U-13C] lactate were used to determine glucose uptake, glucose oxidation and the contribution of exogenous glucose to lactate production. The pathologic model under investigation consisted of a 3 h balloon occlusion of the left anterior descending coronary artery followed by 24 h of reperfusion in canine myocardium. The extent and severity of myocardial injury after the ischemia and reperfusion were assessed by histochemical evaluation (triphenyltetrazolium chloride and periodic acid-Schiff stains). Thirteen intervention and four control dogs were studied. The glucose uptake in the occluded/reperfused area was significantly enhanced compared with that in control dogs (0.40 +/- 0.14 versus 0.15 +/- 0.10 mumol/ml, respectively). In addition, a significantly greater portion of the glucose extracted immediately entered glycolysis in the intervention group (75%) than in the control dogs (33%). The activity of the nonoxidative glycolytic pathway was markedly increased in the ischemically injured reperfused area, as evidenced by the four times greater lactate release in this area compared with the control value. The dual carbon-labeled isotopes showed that 57% of the exogenous glucose entering glycolysis was being converted to lactate. Exogenous glucose contributed to greater than 90% of the observed lactate production. This finding was confirmed by the histochemical finding of sustained glycogen depletion in the occlusion/reperfusion area. The average area of glycogen depletion (37%) significantly exceeded the average area of necrosis

  17. ANL-1(A) - Development of nondestructive evaluation methods for structural ceramics

    International Nuclear Information System (INIS)

    Ellingson, W.A.; Roberts, R.A.; Gopalsami, N.; Dieckman, S.; Hentea, T.; Vaitekunas, J.J.

    1989-01-01

    This section includes the following papers: Development of Nondestructive Evaluation Methods for Structural Ceramics; Effects of Flaws on the Fracture Behavior of Structural Ceramics; Design, Fabrication, and Interface Characterization of Ceramic Fiber-Ceramic Matrix Composites; Development of Advanced Fiber-Reinforced Ceramics; Modeling of Fibrous Preforms for CVD Infiltration; NDT of Advanced Ceramic Composite Materials; Joining of Silicon Carbide Reinforced Ceramics; Superconducting Film Fabrication Research; Short Fiber Reinforced Structural Ceramics; Structural Reliability and Damage Tolerance of Ceramic Composites for High-Temperature Applications; Fabrication of Ceramic Fiber-Ceramic Matrix Composites by Chemical Vapor Infiltration; Characterization of Fiber-CVD Matrix interfacial Bonds; Microwave Sintering of Superconducting Ceramics; Improved Ceramic Composites Through Controlled Fiber-Matrix Interactions; Evaluation of Candidate Materials for Solid Oxide Fuel Cells; Ceramic Catalyst Materials: Hydrous Metal Oxide Ion-Exchange Supports for Coal Liquefaction; and Investigation of Properties and Performance of Ceramic Composite Components

  18. [Ceramic posts].

    Science.gov (United States)

    Mainjot, Amélie; Legros, Caroline; Vanheusden, Alain

    2006-01-01

    As a result of ceramics and all-ceram technologies development esthetic inlay core and abutments flooded the market. Their tooth-colored appearance enhances restoration biomimetism principally on the marginal gingiva area. This article reviews indications and types of cores designed for natural teeth and implants.

  19. Physical and chemical mechanism underlying ultrasonically enhanced hydrochloric acid leaching of non-oxidative roasting of bastnaesite.

    Science.gov (United States)

    Zhang, Dongliang; Li, Mei; Gao, Kai; Li, Jianfei; Yan, Yujun; Liu, Xingyu

    2017-11-01

    In this study, we investigated an alternative to the conventional hydrochloric acid leaching of roasted bastnaesite. The studies suggested that the rare earth oxyfluorides in non-oxidatively roasted bastnaesite can be selectively leached only at elevated temperatures Further, the Ce(IV) in oxidatively roasted bastnaesite does not leach readily at low temperatures, and it is difficult to induce it to form a complex with F - ions in order to increase the leaching efficiency. Moreover, it is inevitably reduced to Ce(III) at elevated temperatures. Thus, the ultrasonically-assisted hydrochloric acid leaching of non-oxidatively roasted bastnaesite was studied in detail, including, the effects of several process factors and the, physical and chemical mechanisms underlying the leaching process. The results show that the leaching rate for the ultrasonically assisted process at 55°C (65% rare earth oxides) is almost the same as that for the conventional leaching process at 85°C. Based on the obtained results, it is concluded that ultrasonic cavitation plays a key role in the proposed process, resulting not only in a high shear stress, which damages the solid surface, but also in the formation of hydroxyl radicals (OH) and hydrogen peroxide (H 2 O 2 ). Standard electrode potential analysis and experimental results indicate that Ce(III) isoxidized by the hydroxyl radicals to Ce(IV), which can be leached with F - ions in the form of a complex, and that the Ce(IV) can subsequently be reduced to Ce(III) by the H 2 O 2. This prevents the Cl - ions in the solution from being oxidized to form chlorine. These results imply that the ultrasonically-assisted process can be used for the leaching of non-oxidatively roasted bastnaesite at low temperatures in the absence of a reductant. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Modeling of Oxidized PTH (oxPTH and Non-oxidized PTH (n-oxPTH Receptor Binding and Relationship of Oxidized to Non-Oxidized PTH in Children with Chronic Renal Failure, Adult Patients on Hemodialysis and Kidney Transplant Recipients

    Directory of Open Access Journals (Sweden)

    Berthold Hocher

    2013-07-01

    Full Text Available Background: The biological properties of oxidized and non-oxidized PTH are substantially different. Oxidized PTH (oxPTH loses its PTH receptor-stimulating properties, whereas non-oxidized PTH (n-oxPTH is a full agonist of the receptor. This was described in more than 20 well published studies in the 1970s and 80s. However, PTH oxidation has been ignored during the development of PTH assays for clinical use so far. Even the nowadays used third generation assay systems do not consider oxidation of PTH We recently developed an assay to differentiate between oxPTH and n-oxPTH. In the current study we established normal values for this assay system. Furthermore, we compare the ratio of oxPTH to n-oxPTH in different population with chronic renal failure: 620 children with renal failure stage 2-4 of the 4C study, 342 adult patients on dialysis, and 602 kidney transplant recipients. In addition, we performed modeling of the interaction of either oxPTH or n-oxPTH with the PTH receptor using biophysical structure approaches. Results: The children had the highest mean as well as maximum n-oxPTH concentrations as compared to adult patients (both patients on dialysis as well as kidney transplant recipients. The relationship between oxPTH and n-oxPTH of individual patients varied substantially in all three populations with renal impairment. The analysis of n-oxPTH in 89 healthy control subjects revealed that n-oxPTH concentrations in patient with renal failure were higher as compared to healthy adult controls (2.25-fold in children with renal failure, 1.53-fold in adult patients on dialysis, and 1.56-fold in kidney transplant recipients, respectively. Computer assisted biophysical structure modeling demonstrated, however, minor sterical- and/or electrostatic changes in oxPTH and n-oxPTH. This indicated that PTH oxidation may induce refolding of PTH and hence alters PTH-PTH receptor interaction via oxidation induced three-dimensional structure alteration of

  1. High-temperature nanoporous ceramic monolith prepared from a polymeric bicontinuous microemulsion template.

    Science.gov (United States)

    Jones, Brad H; Lodge, Timothy P

    2009-02-11

    Nanoporous ceramic with a unique pore structure was derived from an all-hydrocarbon polymeric bicontinuous microemulsion (BmuE). The BmuE was designed to allow facile removal of one phase, resulting in a nanoporous polymer monolith with BmuE-like structure. The pores were filled with a commercially available, polymeric precursor to nonoxide, Si-based ceramics. Pyrolysis resulted in a monolith of nanoporous ceramic, stable to at least 1000 degrees C, with a BmuE-like pore structure. The pore structure is disordered and 3-D continuous. Microscopy and gas sorption measurements suggest a well-defined pore size distribution spanning roughly 60-100 nm, sizes previously unattainable through related techniques.

  2. Fundamental studies of ceramic/metal interfacial reactions at elevated temperatures.

    Energy Technology Data Exchange (ETDEWEB)

    McDeavitt, S. M.; Billings, G. W.; Indacochea, J. E.

    2000-12-14

    This work characterizes the interfaces resulting from exposing oxide and non-oxide ceramic substrates to zirconium metal and stainless steel-zirconium containing alloys. The ceramic/metal systems together were preheated at about 600 C and then the temperatures were increased to the test maximum temperature, which exceeded 1800 C, in an atmosphere of high purity argon. Metal samples were placed onto ceramic substrates, and the system was heated to elevated temperatures past the melting point of the metallic specimen. After a short stay at the peak temperature, the system was cooled to room temperature and examined. The chemical changes across the interface and other microstructural developments were analyzed with energy dispersive spectroscopy (EDS). This paper reports on the condition of the interfaces in the different systems studied and describes possible mechanisms influencing the microstructure.

  3. Oxide ceramics

    International Nuclear Information System (INIS)

    Ryshkewitch, E.; Richerson, D.W.

    1985-01-01

    The book explores single-phase ceramic oxide systems from the standpoint of physical chemistry and technology. This second edition also focuses on advances in technology since publication of the original edition. These include improvements in raw materials and forming and sintering techniques, and the major role that oxide ceramics have had in development of advanced products and processes. The text is divided into five major sections: general fundamentals of oxide ceramics, advances in aluminum oxide technology, advances in zirconia technology, and advances in beryllium oxide technology

  4. Direct Integration of Red-NIR Emissive Ceramic-like An M6 Xi8 Xa6 Metal Cluster Salts in Organic Copolymers Using Supramolecular Interactions.

    Science.gov (United States)

    Robin, Malo; Dumait, Noée; Amela-Cortes, Maria; Roiland, Claire; Harnois, Maxime; Jacques, Emmanuel; Folliot, Hervé; Molard, Yann

    2018-04-03

    Hybrid nanomaterials made of inorganic nanocomponents dispersed in an organic host raise an increasing interest as low-cost solution-processable functional materials. However, preventing phase segregation while allowing a high inorganic doping content remains a major challenge, and usual methods require a functionalization step prior integration. Herein, we report a new approach to design such nanocomposite in which ceramic-like metallic nanocluster compounds are embedded at 10 wt % in organic copolymers, without any functionalization. Dispersion homogeneity and stability are ensured by weak interactions occurring between the copolymer lateral chains and the nanocluster compound. Hybrids could be ink-jet printed and casted on a blue LED. This proof-of-concept device emits in the red-NIR area and generates singlet oxygen, O 2 ( 1 Δg), of particular interest for lights, display, sensors or photodynamic based therapy applications. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Dissolution of crystalline ceramics

    International Nuclear Information System (INIS)

    White, W.B.

    1982-01-01

    The present program objectives are to lay out the fundamentals of crystalline waste form dissolution. Nuclear waste ceramics are polycrystalline. An assumption of the work is that to the first order, the release rate of a particular radionuclide is the surface-weighted sum of the release rates of the radionuclide from each crystalline form that contains it. In the second order, of course, there will be synergistic effects. There will be also grain boundary and other microstructural influences. As a first approximation, we have selected crystalline phases one at a time. The sequence of investigations and measurements is: (i) Identification of the actual chemical reactions of dissolution including identification of the solid reaction products if such occur. (ii) The rates of these reactions are then determined empirically to give what may be called macroscopic kinetics. (iii) Determination of the rate-controlling mechanisms. (iv) If the rate is controlled by surface reactions, the final step would be to determine the atomic kinetics, that is the specific atomic reactions that occur at the dissolving interface. Our concern with the crystalline forms are in two areas: The crystalline components of the reference ceramic waste form and related ceramics and the alumino-silicate phases that appear in some experimental waste forms and as waste-rock interaction products. Specific compounds are: (1) Reference Ceramic Phases (zirconolite, magnetoplumbite, spinel, Tc-bearing spinel and perovskite); (2) Aluminosilicate phases (nepheline, pollucite, CsAlSi 5 O 12 , Sr-feldspar). 5 figures, 1 table

  6. Effect of interactions between Co(2+) and surface goethite layer on the performance of α-FeOOH coated hollow fiber ceramic ultrafiltration membranes.

    Science.gov (United States)

    Zhu, Zhiwen; Zhu, Li; Li, Jianrong; Tang, Jianfeng; Li, Gang; Hsieh, Yi-Kong; Wang, TsingHai; Wang, Chu-Fang

    2016-03-15

    The consideration of water energy nexus inspires the environmental engineering community to pursue a more sustainable strategy in the wastewater treatment. One potential response would be to enhance the performance of the low-pressure driven filtration system. To reach this objective, it is essential to have a better understanding regarding the surface interaction between the target substance and the surface of membrane. In this study, the hollow fiber ceramic membranes were coated with a goethite layer in order to enhance the Co(2+) rejection. Experimental results indicate that higher Co(2+) rejections are always accompanied with the significant reduction in the permeability. Based on the consideration of electroviscous effect, the surface interactions including the induced changes in viscosity, pore radius and Donnan effect in the goethite layer are likely responsible for the pH dependent behaviors in the rejection and permeability. These results could be valuable references to develop the filtration system with high rejection along with acceptable degree of permeability in the future. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. An Overview on the Improvement of Mechanical Properties of Ceramics Nano composites

    International Nuclear Information System (INIS)

    Silvestre, J.; Brito, J. D.; Silvestre, N.

    2015-01-01

    Due to their prominent properties (mechanical, stiffness, strength, thermal stability), ceramic composite materials (CMC) have been widely applied in automotive, industrial and aerospace engineering, as well as in biomedical and electronic devices. Because monolithic ceramics exhibit brittle behaviour and low electrical conductivity, CMC_s have been greatly improved in the last decade. CMC_s are produced from ceramic fibres embedded in a ceramic matrix, for which several ceramic materials (oxide or non-oxide) are used for the fibres and the matrix. Due to the large diversity of available fibres, the properties of CMC_s can be adapted to achieve structural targets. They are especially valuable for structural components with demanding mechanical and thermal requirements. However, with the advent of nanoparticles in this century, the research interests in CMC_s are now changing from classical reinforcement (e.g., microscale fibres) to new types of reinforcement at nano scale. This review paper presents the current state of knowledge on processing and mechanical properties of a new generation of CMC_s: Ceramics Nano composites (CNC_s)

  8. An Overview on the Improvement of Mechanical Properties of Ceramics Nanocomposites

    Directory of Open Access Journals (Sweden)

    J. Silvestre

    2015-01-01

    Full Text Available Due to their prominent properties (mechanical, stiffness, strength, thermal stability, ceramic composite materials (CMC have been widely applied in automotive, industrial and aerospace engineering, as well as in biomedical and electronic devices. Because monolithic ceramics exhibit brittle behaviour and low electrical conductivity, CMCs have been greatly improved in the last decade. CMCs are produced from ceramic fibres embedded in a ceramic matrix, for which several ceramic materials (oxide or non-oxide are used for the fibres and the matrix. Due to the large diversity of available fibres, the properties of CMCs can be adapted to achieve structural targets. They are especially valuable for structural components with demanding mechanical and thermal requirements. However, with the advent of nanoparticles in this century, the research interests in CMCs are now changing from classical reinforcement (e.g., microscale fibres to new types of reinforcement at nanoscale. This review paper presents the current state of knowledge on processing and mechanical properties of a new generation of CMCs: Ceramics Nanocomposites (CNCs.

  9. Ceramic Seal.

    Energy Technology Data Exchange (ETDEWEB)

    Smartt, Heidi A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Romero, Juan A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Custer, Joyce Olsen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hymel, Ross W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Krementz, Dan [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Gobin, Derek [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Harpring, Larry [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Martinez-Rodriguez, Michael [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Varble, Don [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); DiMaio, Jeff [Tetramer Technologies, Pendleton, SC (United States); Hudson, Stephen [Tetramer Technologies, Pendleton, SC (United States)

    2016-11-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  10. Ceramic Seal

    International Nuclear Information System (INIS)

    Smartt, Heidi A.; Romero, Juan A.; Custer, Joyce Olsen; Hymel, Ross W.; Krementz, Dan; Gobin, Derek; Harpring, Larry; Martinez-Rodriguez, Michael; Varble, Don; DiMaio, Jeff; Hudson, Stephen

    2016-01-01

    Containment/Surveillance (C/S) measures are critical to any verification regime in order to maintain Continuity of Knowledge (CoK). The Ceramic Seal project is research into the next generation technologies to advance C/S, in particular improving security and efficiency. The Ceramic Seal is a small form factor loop seal with improved tamper-indication including a frangible seal body, tamper planes, external coatings, and electronic monitoring of the seal body integrity. It improves efficiency through a self-securing wire and in-situ verification with a handheld reader. Sandia National Laboratories (SNL) and Savannah River National Laboratory (SRNL), under sponsorship from the U.S. National Nuclear Security Administration (NNSA) Office of Defense Nuclear Nonproliferation Research and Development (DNN R&D), have previously designed and have now fabricated and tested Ceramic Seals. Tests have occurred at both SNL and SRNL, with different types of tests occurring at each facility. This interim report will describe the Ceramic Seal prototype, the design and development of a handheld standalone reader and an interface to a data acquisition system, fabrication of the seals, and results of initial testing.

  11. Synthesis of ZrB{sub 2}-SiC ceramic composites from a single-source precursor

    Energy Technology Data Exchange (ETDEWEB)

    Arish, Dasan, E-mail: arishd@rediffmail.com [Université of Limoges, SPCTS-CNRS, UMR 7315, Centre Européen de la Céramique (CEC), 12 Rue Atlantis, F-87068, Limoges Cedex (France); Shiju, Chellan [Synthetic Products Division, Corporate R & D Center (CRDC), HLL Lifecare Limited, Thiruvananthapuram, Kerala (India); Joseyphus, Raphael Selwin, E-mail: rsjoseyphus@gmail.com [PG & Research, Department of Chemistry, Mar Ivanios College (Autonomous), Thiruvananthapuram, 695015, Kerala (India); Pushparajan, Joseph [Travancore Titanium Products Ltd., Kochuveli, Thiruvananthapuram, 695021, Kerala (India)

    2017-06-15

    Preceramic polymer zirconoborosiloxane was synthesized from the reaction with boric acid, diphenyldiethoxysilane and zirconium (IV) propoxide via solventless process. The thermogravimetric analysis of the polymer showed that ceramic yield as decomposition product at 900 °C was 71%. The pyrolysis of zirconoborosiloxane in an argon gas environment was investigated as standard pyrolytic process up to 1650 °C. Microstructure evolution of ceramic phases was made by means of Fourier transform infrared, Raman spectroscopy, X-ray diffraction and scanning electron microscope analysis. The results clearly demonstrated the pyrolysis products at 1650 °C consist of totally non-oxide ceramic phases of β-SiC, ZrB{sub 2} and free carbon. - Highlights: • Preceramic polymer zirconoborosiloxane was synthesized by non-aqueous solventless process. • Non-oxide ZrB{sub 2}-SiC composites could be obtained from the pyrolysed products at 1650 °C. • Free carbon content was identified by Raman spectroscopy.

  12. Radiation-disorder and aperiodicity in irradiated ceramics

    International Nuclear Information System (INIS)

    Hobbs, L.W.

    1992-01-01

    This final technical report documents the accomplishments of the program of research entitled ''Radiation Disorder and Aperiodicity in Irradiated Ceramics'' for the period June 22, 1989--June 21, 1992. This research forms the latest part on an on-going program, begun at MIT in 1983 under DOE support, which has had as its objectives investigation of the responses in radiation environments of ceramics heavily-irradiated with electrons, neutrons and ions, with potential applications to fusion energy technology and high-level nuclear waste storage. Materials investigated have included SiO 2 , MgAl 2 O 4 , Al 23 O 27 N 5 , SiC, BeO, LiAlO 2 , Li 2 ZrO 3 , CaTiO 3 KTaO 3 and Ca(Zr, Pu)Ti 2 O 7 . The program initially proposed for 1989 had as its major objectives two main thrusts: (1) research on defect aggregation in irradiated non-oxide ceramics, and (2) research on irradiation-induced amorphization of network silicas and phosphates

  13. Mechanical interactions of cuspal-coverage designs and cement thickness in a cusp-replacing ceramic premolar restoration: a finite element study.

    Science.gov (United States)

    Chang, Yen-Hsiang; Lin, Wen-Hsueng; Kuo, Wen-Chieh; Chang, Chia-Yu; Lin, Chun-Li

    2009-04-01

    The aim of this study was to investigate the biomechanical interactions between cuspal preparation designs and cement thickness in a cusp-replacing ceramic premolar restoration. The cavity was designed in a typical MODP (mesial-occlusal-distal- palatal) restoration failure shape when the palatal cusp has been lost. Twelve 3D finite element (FE) models with four cavity preparations (without coverage and with buccal cuspal coverage in 1.0, 1.5 and 2.0 mm reducing in cuspal height) and three cement thicknesses (50, 100 and 150 microm) were constructed to perform the simulations. The results indicated that enamel and cement stresses in designs with no buccal cusp replacement or a 1.0 mm thick buccal cusp replacement were higher than the designs with 1.5 and 2.0 mm thick replacement. No apparent differences were found in the dentin, enamel, and cement stresses based on cement thicknesses of 50, 100, or 150 microm. This study concluded that when cusp replacement is indicated, reduction of the buccal cusp by 1.5 mm at least could reduce stress.

  14. Industrial ceramics

    International Nuclear Information System (INIS)

    Mengelle, Ch.

    1999-04-01

    After having given the definition of the term 'ceramics', the author describes the different manufacturing processes of these compounds. These materials are particularly used in the fields of 1)petroleum industry (in primary and secondary reforming units, in carbon black reactors and ethylene furnaces). 2)nuclear industry (for instance UO 2 and PuO 2 as fuels; SiC for encapsulation; boron carbides for control systems..)

  15. Microwave sintering of ceramic materials

    Science.gov (United States)

    Karayannis, V. G.

    2016-11-01

    In the present study, the potential of microwave irradiation as an innovative energy- efficient alternative to conventional heating technologies in ceramic manufacturing is reviewed, addressing the advantages/disadvantages, while also commenting on future applications of possible commercial interest. Ceramic materials have been extensively studied and used due to several advantages they exhibit. Sintering ceramics using microwave radiation, a novel technology widely employed in various fields, can be an efficient, economic and environmentally-friendlier approach, to improve the consolidation efficiency and reduce the processing cycle-time, in order to attain substantial energy and cost savings. Microwave sintering provides efficient internal heating, as energy is supplied directly and penetrates the material. Since energy transfer occurs at a molecular level, heat is generated throughout the material, thus avoiding significant temperature gradients between the surface and the interior, which are frequently encountered at high heating rates upon conventional sintering. Thus, rapid, volumetric and uniform heating of various raw materials and secondary resources for ceramic production is possible, with limited grain coarsening, leading to accelerated densification, and uniform and fine-grained microstructures, with enhanced mechanical performance. This is particularly important for manufacturing large-size ceramic products of quality, and also for specialty ceramic materials such as bioceramics and electroceramics. Critical parameters for the process optimization, including the electromagnetic field distribution, microwave-material interaction, heat transfer mechanisms and material transformations, should be taken into consideration.

  16. Mite allergoids coupled to nonoxidized mannan from Saccharomyces cerevisae efficiently target canine dendritic cells for novel allergy immunotherapy in veterinary medicine.

    Science.gov (United States)

    Soria, Irene; Alvarez, Javier; Manzano, Ana I; López-Relaño, Juan; Cases, Bárbara; Mas-Fontao, Ana; Cañada, F Javier; Fernández-Caldas, Enrique; Casanovas, Miguel; Jiménez-Barbero, Jesús; Palomares, Oscar; Viñals-Flórez, Luis M; Subiza, José L

    2017-08-01

    We have recently reported that grass pollen allergoids conjugated with nonoxidized mannan of Saccharomyces cerevisae using glutaraldehyde results in a novel hypoallergenic mannan-allergen complex with improved properties for allergen vaccination. Using this approach, human dendritic cells show a better allergen uptake and cytokine profile production (higher IL-10/IL-4 ratio) for therapeutic purposes. Here we aim to address whether a similar approach can be extended to dogs using canine dendritic cells. Six healthy Spanish Greyhound dogs were used as blood donors to obtain canine dendritic cells (DC) derived from peripheral blood monocytes. Allergens from Dermatophagoides farinae mite were polymerized and conjugated with nonoxidized mannan. Nuclear magnetic resonance (NMR), gel electrophoresis (SDS-PAGE), immunoblotting and IgE-ELISA inhibition studies were conducted to evaluate the main characteristics of the allergoid obtained. Mannan-allergen conjugate and controls were assayed in vitro for canine DC uptake and production of IL-4 and IL-10. The results indicate that the conjugation of D. farinae allergens with nonoxidized mannan was feasible using glutaraldehyde. The resulting product was a polymerized structure showing a high molecular weight as detected by NMR and SDS-PAGE analysis. The mannan-allergen conjugate was hypoallergenic with a reduced reactivity with specific dog IgE. An increase in both allergen uptake and IL-10/IL-4 ratio was obtained when canine DCs were incubated with the mannan-allergen conjugate, as compared with the control allergen preparations (unmodified D. farinae allergens and oxidized mannan-allergen conjugate). We conclude that hypoallergenic D. farinae allergens coupled to nonoxidized mannan is a novel allergen preparation suitable for canine allergy immunotherapy targeting dendritic cells. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  17. Simultaneous determination of ethanol's four types of non-oxidative metabolites in human whole blood by liquid chromatography tandem mass spectrometry.

    Science.gov (United States)

    Zhang, Xinyu; Zheng, Feng; Lin, Zebin; Johansen, Sys Stybe; Yu, Tianfang; Liu, Yuming; Huang, Zhibin; Li, Jiaolun; Yan, Jie; Rao, Yulan

    2017-04-22

    The importance of ethanol non-oxidative metabolites as the specific biomarkers of alcohol consumption in clinical and forensic settings is increasingly acknowledged. Simultaneous determination of these metabolites can provide a wealth of information like drinking habit and history, but it was difficult to achieve because of their wide range of polarity. This work describes development and validation of a simple liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for 4 types of ethanol non-oxidative metabolites (ethyl glucuronide, ethyl sulfate, fatty acid ethyl esters and phosphatidylethanols) in 50 μL of human whole blood. Pretreatment method, column and MS conditions were optimized. For the first time, the four types of ethanol non-oxidative metabolites with enormous discrepancies of property were simultaneously extracted and analyzed in one run within 40 min. The limits of detections (LODs) were among 0.1-10 ng/mL, and good linearity was obtained. Deviations in precision and accuracy were all lower than 15% at three QC levels. This method was then applied to two forensic samples, resulting in information on drinking habits and drinking time which were very useful for the interpretation of the blood alcohol results. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage restorations.

    Science.gov (United States)

    Bakeman, E M; Rego, N; Chaiyabutr, Y; Kois, J C

    2015-01-01

    This study evaluated the influence of ceramic thickness and ceramic materials on fracture resistance of posterior partial coverage ceramic restorations. Forty extracted molars were allocated into four groups (n=10) to test for two variables: 1) the thickness of ceramic (1 mm or 2 mm) and 2) the ceramic materials (a lithium disilicate glass-ceramic [IPS e.max] or leucite-reinforced glass ceramic [IPS Empress]). All ceramic restorations were luted with resin cement (Variolink II) on the prepared teeth. These luted specimens were loaded to failure in a universal testing machine, in the compression mode, with a crosshead speed of 1.0 mm/min. The data were analyzed using two-way analysis of variance and the Tukey Honestly Significantly Different multiple comparison test (α =0.05). The fracture resistance revealed a significant effect for materials (pceramic was not significant (p=0.074), and the interaction between the thickness of ceramic and the materials was not significant (p=0.406). Mean (standard deviation) fracture resistance values were as follows: a 2-mm thickness of a lithium disilicate bonded to tooth structure (2505 [401] N) revealed a significantly higher fracture resistance than did a 1-mm thickness of leucite-reinforced (1569 [452] N) and a 2-mm thickness of leucite-reinforced ceramic bonded to tooth structure (1716 [436] N) (pceramic at 1-mm thickness (2105 [567] N) and at 2-mm thickness. Using a lithium disilicate glass ceramic for partial coverage restoration significantly improved fracture resistance compared to using a leucite-reinforced glass ceramic. The thickness of ceramic had no significant effect on fracture resistance when the ceramics were bonded to the underlying tooth structure.

  19. The uniformity study of non-oxide thin film at device level using electron energy loss spectroscopy

    Science.gov (United States)

    Li, Zhi-Peng; Zheng, Yuankai; Li, Shaoping; Wang, Haifeng

    2018-05-01

    Electron energy loss spectroscopy (EELS) has been widely used as a chemical analysis technique to characterize materials chemical properties, such as element valence states, atoms/ions bonding environment. This study provides a new method to characterize physical properties (i.e., film uniformity, grain orientations) of non-oxide thin films in the magnetic device by using EELS microanalysis on scanning transmission electron microscope. This method is based on analyzing white line ratio of spectra and related extended energy loss fine structures so as to correlate it with thin film uniformity. This new approach can provide an effective and sensitive method to monitor/characterize thin film quality (i.e., uniformity) at atomic level for thin film development, which is especially useful for examining ultra-thin films (i.e., several nanometers) or embedded films in devices for industry applications. More importantly, this technique enables development of quantitative characterization of thin film uniformity and it would be a remarkably useful technique for examining various types of devices for industrial applications.

  20. Challenges and Opportunities in Reactive Processing and Applications of Advanced Ceramic Materials

    Science.gov (United States)

    Singh, Mrityunjay

    2003-01-01

    Recently, there has been a great deal of interest in the research, development, and commercialization of innovative synthesis and processing technologies for advanced ceramics and composite materials. Reactive processing approaches have been actively considered due to their robustness, flexibility, and affordability. A wide variety of silicon carbide-based advanced ceramics and composites are currently being fabricated using the processing approaches involving reactive infiltration of liquid and gaseous species into engineered fibrous or microporous carbon performs. The microporous carbon performs have been fabricated using the temperature induced phase separation and pyrolysis of two phase organic (resin-pore former) mixtures and fiber reinforcement of carbon and ceramic particulate bodies. In addition, pyrolyzed native plant cellulose tissues also provide unique carbon templates for manufacturing of non-oxide and oxide ceramics. In spite of great interest in this technology due to their affordability and robustness, there is a lack of scientific basis for process understanding and many technical challenges still remain. The influence of perform properties and other parameters on the resulting microstructure and properties of final material is not well understood. In this presentation, mechanism of silicon-carbon reaction in various systems and the effect of perform microstructure on the mechanical properties of advanced silicon carbide based materials will be discussed. Various examples of applications of reactively processed advanced silicon carbide ceramics and composite materials will be presented.

  1. Development status of metallic, dispersion and non-oxide advanced and alternative fuels for power and research reactors

    International Nuclear Information System (INIS)

    2003-09-01

    eighties until the present days. The aspects of HTGR fuels, as well as partitioning and transmutation (P and T) of minor actinides and relative specific fuels have not been addressed. The International Atomic Energy Agency's (IAEA) Division of Nuclear Fuel Cycle and Waste Technology has been closely involved for many years in the above mentioned activities in the framework of the Advisory Group on Advanced Fuel Technology and Performance (fast reactor fuels) and Technical Working Group on Water Reactor Fuel Performance and Technology (thermal power reactor fuels). Apart from the progress made during the last decade, this report summarizes technological approaches, out-of-pile and in-pile properties of many types of advanced non-oxide fuels. It is expected that the report will provide IAEA Member States and their nuclear engineers with useful information and will preserve knowledge in the area for future developments. The review was prepared by a group of experts in the field from Germany, India and the Russian Federation and supported by information from specialists in Japan, Switzerland and the IAEA engaged in non-oxide fuel developments and related subjects

  2. Boron nitride ceramics from molecular precursors: synthesis, properties and applications.

    Science.gov (United States)

    Bernard, Samuel; Salameh, Chrystelle; Miele, Philippe

    2016-01-21

    Hexagonal boron nitride (h-BN) attracts considerable interest because its structure is similar to that of carbon graphite while it displays different properties which are of interest for environmental and green technologies. The polar nature of the B-N bond in sp(2)-bonded BN makes it a wide band gap insulator with different chemistry on its surface and particular physical and chemical properties such as a high thermal conductivity, a high temperature stability, a high resistance to corrosion and oxidation and a strong UV emission. It is chemically inert and nontoxic and has good environmental compatibility. h-BN also has enhanced physisorption properties due to the dipolar fields near its surface. Such properties are closely dependent on the processing method. Bottom-up approaches consist of transforming molecular precursors into non-oxide ceramics with retention of the structural units inherent to the precursor molecule. The purpose of the present review is to give an up-to-date overview on the most recent achievements in the preparation of h-BN from borazine-based molecular single-source precursors including borazine and 2,4,6-trichloroborazine through both vapor phase syntheses and methods in the liquid/solid state involving polymeric intermediates, called the Polymer-Derived Ceramics (PDCs) route. In particular, the effect of the chemistry, composition and architecture of the borazine-based precursors and derived polymers on the shaping ability as well as the properties of h-BN is particularly highlighted.

  3. Formation of Si-C-N ceramics from melamine-carbosilazane single source precursors

    International Nuclear Information System (INIS)

    Shatnawi, Mazin; Al-Mansi, Wafaa; Arafa, Isam

    2008-01-01

    A series of melamine-carbosilazane pre-ceramic macromolecules (Mel-CSZs) were prepared by the condensation of melamine with different organochlorosilanes (R x SiCl 4-x where R is CH 3 /C 6 H 5 and x is 1, 2 or 3) using pyridine as a solvent under nitrogen atmosphere. These melamine-based carbosilazane macromolecules (Mel-CSZs) were characterized by infrared spectroscopy (FT-IR), mass spectrometry (MS), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The backbone of the resulting Mel-CSZs consists of melamine and carbosilazane building blocks. Pyrolysis of these Mel-CSZs at 600 deg. C under nitrogen and vacuum afforded the corresponding silicon-based nonoxide carbonitride ceramics (Si-C-N). The microstructure and textural morphology of the resulting fine ceramic materials were examined using FT-IR, powder X-ray diffraction (XRD), and scanning electron microscopy (SEM). - Graphical abstract: Pyrolysis of the prepared melamine-organosilane macromolecules afforded Si-C-N ceramics with different textural morphology

  4. Reaction-transport simulations of non-oxidative methane conversion with continuous hydrogen removal: Homogeneous-heterogeneous methane reaction pathways

    International Nuclear Information System (INIS)

    Li, Lin; Borry, Richard W.; Iglesia, Enrique

    2000-01-01

    Detailed kinetic-transport models were used to explore thermodynamic and kinetic barriers in the non-oxidative conversion of CH4 via homogeneous and homogeneous-heterogeneous pathways and the effects of continuous hydrogen removal and of catalytic sites on attainable yields of useful C2-C10 products. The homogeneous kinetic model combines separately developed models for low-conversion pyrolysis and for chain growth to form large aromatics and carbon. The H2 formed in the reaction decreases CH4 pyrolysis rates and equilibrium conversions and it favors the formation of lighter products. The removal of H2 along tubular reactors with permeable walls increases reaction rates and equilibrium CH4 conversions. C2-C10 yields reach values greater than 90 percent at intermediate values of dimensionless transport rates (delta=1-10), defined as the ratio hydrogen transport and methane conversion rates. Homogeneous reactions require impractical residence times, even with H2 removal, because of slow initiation and chain transfer rates. The introduction of heterogeneous chain initiation pathways using surface sites that form methyl radicals eliminates the induction period without influencing the homogeneous product distribution. Methane conversion, however, occurs predominately in the chain transfer regime, within which individual transfer steps and the formation of C2 intermediates become limited by thermodynamic constraints. Catalytic sites alone cannot overcome these constraints. Catalytic membrane reactors with continuous H2 removal remove these thermodynamic obstacles and decrease the required residence time. Reaction rates become limited by homogeneous reactions of C2 products to form C6+ aromatics. Higher delta values lead to subsequent conversion of the desired C2-C10 products to larger polynuclear aromatics. We conclude that catalytic methane pyrolysis at the low temperatures required for restricted chain growth and the elimination of thermodynamics constraints via

  5. Ceramic Laser Materials

    Directory of Open Access Journals (Sweden)

    Guillermo Villalobos

    2012-02-01

    Full Text Available Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

  6. Ceramic Laser Materials

    Science.gov (United States)

    Sanghera, Jasbinder; Kim, Woohong; Villalobos, Guillermo; Shaw, Brandon; Baker, Colin; Frantz, Jesse; Sadowski, Bryan; Aggarwal, Ishwar

    2012-01-01

    Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements. PMID:28817044

  7. Radiation Effects in Nuclear Ceramics

    Directory of Open Access Journals (Sweden)

    L. Thomé

    2012-01-01

    Full Text Available Due to outstanding physicochemical properties, ceramics are key engineering materials in many industrial domains. The evaluation of the damage created in ceramics employed in radiative media is a challenging problem for electronic, space, and nuclear industries. In this latter field, ceramics can be used as immobilization forms for radioactive wastes, inert fuel matrices for actinide transmutation, cladding materials for gas-cooled fission reactors, and structural components for fusion reactors. Information on the radiation stability of nuclear materials may be obtained by simulating the different types of interactions involved during the slowing down of energetic particles with ion beams delivered by various types of accelerators. This paper presents a review of the radiation effects occurring in nuclear ceramics, with an emphasis on recent results concerning the damage accumulation processes. Energetic ions in the KeV-GeV range are used to explore the nuclear collision (at low energy and electronic excitation (at high energy regimes. The recovery by electronic excitation of the damage created by ballistic collisions (SHIBIEC process is also addressed.

  8. Creep in ceramics

    CERN Document Server

    Pelleg, Joshua

    2017-01-01

    This textbook is one of its kind, since there are no other books on Creep in Ceramics. The book consist of two parts: A and B. In part A general knowledge of creep in ceramics is considered, while part B specifies creep in technologically important ceramics. Part B covers creep in oxide ceramics, carnides and nitrides. While covering all relevant information regarding raw materials and characterization of creep in ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  9. Ceramic Parts for Turbines

    Science.gov (United States)

    Jones, R. D.; Carpenter, Harry W.; Tellier, Jim; Rollins, Clark; Stormo, Jerry

    1987-01-01

    Abilities of ceramics to serve as turbine blades, stator vanes, and other elements in hot-gas flow of rocket engines discussed in report. Ceramics prime candidates, because of resistance to heat, low density, and tolerance of hostile environments. Ceramics considered in report are silicon nitride, silicon carbide, and new generation of such ceramic composites as transformation-toughened zirconia and alumina and particulate- or whisker-reinforced matrices. Report predicts properly designed ceramic components viable in advanced high-temperature rocket engines and recommends future work.

  10. Forming of superplastic ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Lesuer, D.R.; Wadsworth, J.; Nieh, T.G.

    1994-05-01

    Superplasticity in ceramics has now advanced to the stage that technologically viable superplastic deformation processing can be performed. In this paper, examples of superplastic forming and diffusion bonding of ceramic components are given. Recent work in biaxial gas-pressure forming of several ceramics is provided. These include yttria-stabilized, tetragonal zirconia (YTZP), a 20% alumina/YTZP composite, and silicon. In addition, the concurrent superplastic forming and diffusion bonding of a hybrid ceramic-metal structure are presented. These forming processes offer technological advantages of greater dimensional control and increased variety and complexity of shapes than is possible with conventional ceramic shaping technology.

  11. Ceramic gas turbine shroud

    Science.gov (United States)

    Shi, Jun; Green, Kevin E.

    2014-07-22

    An example gas turbine engine shroud includes a first annular ceramic wall having an inner side for resisting high temperature turbine engine gasses and an outer side with a plurality of radial slots. A second annular metallic wall is positioned radially outwardly of and enclosing the first annular ceramic wall and has a plurality of tabs in communication with the slot of the first annular ceramic wall. The tabs of the second annular metallic wall and slots of the first annular ceramic wall are in communication such that the first annular ceramic wall and second annular metallic wall are affixed.

  12. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  13. Boron-bearing species in ceramic matrix composites for long-term aerospace applications

    International Nuclear Information System (INIS)

    Naslain, R.; Guette, A.; Rebillat, F.; Pailler, R.; Langlais, F.; Bourrat, X.

    2004-01-01

    Boron-bearing refractory species are introduced in non-oxide ceramic matrix fibrous composites (such as SiC/SiC composites) to improve their oxidation resistance under load at high temperatures with a view to applications in the aerospace field. B-doped pyrocarbon and hex-BN have been successfully used as interphase (instead of pure pyrocarbon) either as homogeneous or multilayered fiber coatings, to arrest and deflect matrix cracks formed under load (mechanical fuse function) and to give toughness to the materials. A self-healing multilayered matrix is designed and used in a model composite, which combines B-doped pyrocarbon mechanical fuse layers and B- and Si-bearing compound (namely B 4 C and SiC) layers forming B 2 O 3 -based fluid healing phases when exposed to an oxidizing atmosphere. All the materials are deposited by chemical vapor infiltration. Lifetimes under tensile loading of several hundreds hours at high temperatures are reported

  14. Environmental Barrier Coatings for Ceramic Matrix Composites - An Overview

    Science.gov (United States)

    Lee, Kang; Zhu, Dongming; Wiesner, Valerie Lynn; van Roode, Mark; Kashyap, Tania; Zhu, Dongming; Wiesner, Valerie

    2016-01-01

    Ceramic Matrix Composites (CMCs) are increasingly being considered as structural materials for advanced power generation equipment. Broadly speaking the two classes of materials are oxide-based CMCs and non-oxide based CMCs. The non-oxide CMCs are primarily silicon-based. Under conditions prevalent in the gas turbine hot section the water vapor formed in the combustion of gaseous or liquid hydrocarbons reacts with the surface-SiO2 to form volatile products. Progressive surface recession of the SiC-SiC CMC component, strength loss as a result of wall thinning and chemical changes in the component occur, which leads to the loss of structural integrity and mechanical strength and becomes life limiting to the equipment in service. The solutions pursued to improve the life of SiC-SiC CMCs include the incorporation of an external barrier coating to provide surface protection to the CMC substrate. The coating system has become known as an Environmental Barrier Coating (EBC). The relevant early coatings work was focused on coatings for corrosion protection of silicon-based monolithic ceramics operating under severely corrosive conditions. The development of EBCs for gas turbine hot section components was built on the early work for silicon-based monolithics. The first generation EBC is a three-layer coating, which in its simplest configuration consists of a silicon (Si) base coat applied on top of the CMC, a barium-strontium-aluminosilicate (BSAS) surface coat resistant to water vapor attack, and a mullite-based intermediate coating layer between the Si base coat and BSAS top coat. This system can be represented as Si-Mullite-BSAS. While this baseline EBC presented a significant improvement over the uncoated SiC-SiC CMC, for the very long durations of 3-4 years or more expected for industrial operation further improvements in coating durability are desirable. Also, for very demanding applications with higher component temperatures but shorter service lives more rugged EBCs

  15. Hardness properties and microscopic investigation of crack- crystal interaction in SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F glass ceramic system.

    Science.gov (United States)

    Roy, Shibayan; Basu, Bikramjit

    2010-01-01

    In view of the potential engineering applications requiring machinability and wear resistance, the present work focuses to evaluate hardness property and to understand the damage behavior of some selected glass-ceramics having different crystal morphologies with SiO(2)-MgO-Al(2)O(3)-K(2)O-B(2)O(3)-F composition, using static micro-indentation tests as well as dynamic scratch tests, respectively. Vickers hardness of up to 5.5 GPa has been measured in glass-ceramics containing plate like mica crystals. Scratch tests at a high load of 50 Nin artificial saliva were carried out in order to simulate the crack-microstructure interaction during real-time abrasion wear and machining operation. The experimental observations indicate that the novel "spherulitic-dendritic shaped "crystals, similar to the plate like crystals, have the potential to hinder the scratching induced crack propagation. In particular, such potential of the 'spherulitic-dendritic' crystals become more effective due to the larger interfacial area with the glass matrix as well as the dendritic structure of each mica plate, which helps in crack deflection and crack blunting, to a larger extent.While modest damage tolerant behavior is observed in case of 'spherulitic-dendritic' crystal containing material, severe brittle fracture of plate like crystals were noted, when both were scratched at 50 N load.

  16. Basic research in crystalline and noncrystalline ceramic systems. Annual report, August 1, 1980-October 31, 1981

    International Nuclear Information System (INIS)

    1981-01-01

    The Basic Research Programs in Ceramics sponsored by the US Department of Energy supports a significant fraction of the research effort and graduate student training in ceramics at MIT. Various research activities involving ceramic materials include electrical properties; kinetic studies; defect structures, defect interactions, grain boundaries and surfaces; sintering studies; and mechanical properties

  17. Strengthening of Ceramic-based Artificial Nacre via Synergistic Interactions of 1D Vanadium Pentoxide and 2D Graphene Oxide Building Blocks

    Science.gov (United States)

    Knöller, Andrea; Lampa, Christian P.; Cube, Felix von; Zeng, Tingying Helen; Bell, David C.; Dresselhaus, Mildred S.; Burghard, Zaklina; Bill, Joachim

    2017-01-01

    Nature has evolved hierarchical structures of hybrid materials with excellent mechanical properties. Inspired by nacre’s architecture, a ternary nanostructured composite has been developed, wherein stacked lamellas of 1D vanadium pentoxide nanofibres, intercalated with water molecules, are complemented by 2D graphene oxide (GO) nanosheets. The components self-assemble at low temperature into hierarchically arranged, highly flexible ceramic-based papers. The papers’ mechanical properties are found to be strongly influenced by the amount of the integrated GO phase. Nanoindentation tests reveal an out-of-plane decrease in Young’s modulus with increasing GO content. Furthermore, nanotensile tests reveal that the ceramic-based papers with 0.5 wt% GO show superior in-plane mechanical performance, compared to papers with higher GO contents as well as to pristine V2O5 and GO papers. Remarkably, the performance is preserved even after stretching the composite material for 100 nanotensile test cycles. The good mechanical stability and unique combination of stiffness and flexibility enable this material to memorize its micro- and macroscopic shape after repeated mechanical deformations. These findings provide useful guidelines for the development of bioinspired, multifunctional systems whose hierarchical structure imparts tailored mechanical properties and cycling stability, which is essential for applications such as actuators or flexible electrodes for advanced energy storage. PMID:28102338

  18. Corrosion of immersed ceramic heat exchanger tubes in aluminium foundry baths

    Energy Technology Data Exchange (ETDEWEB)

    Bracho-Troconis, C.B.; Frot, G.; Bienvenu, Y. [Ecole des Mines de Paris, Evry (France). Centre des Materiaux; Frety, N. [Ecole des Mines d`Albi-Carmaux (France); Alliat, I. [CERSTA-Gaz de France, Saint-Denis (France)

    1997-12-31

    The corrosion of three non-oxide ceramics by Al-9Si-3Cu baths and by fluxes (mixtures of chlorides and fluorides of sodium and potassium) at about 750 C was studied in a foundry environment. Comparison of results of the metallurgical examination of A, a silicon-nitride-bonded silicon carbide and of B, a reaction-bonded silicon nitride, surface treated to fill all the external porosity provides some insight into the role of the bonding phase and the porosity. Grade C is a graphite bonded silicon carbide with an external protection by a ceramic glazing. The SiC phase in the tubes is inert to the corrosive liquids (attributed to the silicon content in the metal). A and C ceramics react only in the presence of a flux. Sodium and chlorine were identified in the corrosion products as well as AlN (A) and Al{sub 4}C{sub 3} (C), resulting from reaction of the silicon nitride or of the graphite bonding phase with aluminium. This suggests that the fluxes are responsible for the corrosive process, by causing the formation of gaseous aluminium halides which penetrate the porous bonding phase and react with it to form AlN or Al{sub 4}C{sub 3}. (orig.) 13 refs.

  19. Analyses of fine paste ceramics

    International Nuclear Information System (INIS)

    Sabloff, J.A.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics

  20. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 2. Science and Technology of Ceramics - Advanced Ceramics: Structural Ceramics and Glasses. Sheela K Ramasesha. Series Article Volume 5 Issue 2 February 2000 pp 4-11 ...

  1. Analyses of fine paste ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sabloff, J A [ed.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics. (DLC)

  2. [Ceramic inlays and onlays].

    Science.gov (United States)

    van Pelt, A W; de Kloet, H J; van der Kuy, P

    1996-11-01

    Large direct composite restorations can induce shrinkage related postoperative sensitivity. Indirect resin-bonded (tooth colored) restorations may perhaps prevent these complaints. Indirect bonded ceramics are especially attractive because of their biocompatibility and esthetic performance. Several procedures and techniques are currently available for the fabrication of ceramic restorations: firing, casting, heat-pressing and milling. In this article the different systems are described. Advantages, disadvantages and clinical performance of ceramic inlays are compared and discussed.

  3. Ceramic Electron Multiplier

    International Nuclear Information System (INIS)

    Comby, G.

    1996-01-01

    The Ceramic Electron Multipliers (CEM) is a compact, robust, linear and fast multi-channel electron multiplier. The Multi Layer Ceramic Technique (MLCT) allows to build metallic dynodes inside a compact ceramic block. The activation of the metallic dynodes enhances their secondary electron emission (SEE). The CEM can be used in multi-channel photomultipliers, multi-channel light intensifiers, ion detection, spectroscopy, analysis of time of flight events, particle detection or Cherenkov imaging detectors. (auth)

  4. Displacive Transformation in Ceramics

    Science.gov (United States)

    1994-02-28

    PZT ), ceramics have attracted natural abundance. much attention for use in nonvolatile semiconductor mem- We attribute the observed spectra in Fig. I to...near a crack tip in piezoelectric ceramics of lead zirconate titanate ( PZT ) and barium titanate. They reasoned that the poling of ferroelectric... Texture in Ferroelastic Tetragonal Zirconia," J. Am. Ceram . Soc., 73 (1990) no. 6: 1777-1779. 27. J. F. Jue and A. Virkar, "Fabrication, Microstructural

  5. Continuous Fiber Ceramic Composites

    Energy Technology Data Exchange (ETDEWEB)

    Fareed, Ali [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States); Craig, Phillip A. [Honeywell Advanced Composites Inc. (HACI), Newark, DE (United States)

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  6. Piezo-electrostrictive ceramics

    International Nuclear Information System (INIS)

    Kim, Ho Gi; Shin, Byeong Cheol

    1991-09-01

    This book deals with principle and the case of application of piezo-electrostrictive ceramics, which includes definition of piezoelectric materials and production and development of piezoelectric materials, coexistence of Pb(zr, Ti)O 3 ceramics on cause of coexistence in MPB PZT ceramics, electrostrictive effect of oxide type perovskite, practical piezo-electrostrictive materials, and breaking strength, evaluation technique of piezoelectric characteristic, and piezoelectric accelerometer sensor like printer head, ink jet and piezoelectric relay.

  7. Method of sintering ceramic materials

    Science.gov (United States)

    Holcombe, Cressie E.; Dykes, Norman L.

    1992-01-01

    A method for sintering ceramic materials is described. A ceramic article is coated with layers of protective coatings such as boron nitride, graphite foil, and niobium. The coated ceramic article is embedded in a container containing refractory metal oxide granules and placed within a microwave oven. The ceramic article is heated by microwave energy to a temperature sufficient to sinter the ceramic article to form a densified ceramic article having a density equal to or greater than 90% of theoretical density.

  8. Defect production in ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States); Kinoshita, C. [Kyushu Univ. (Japan)

    1997-08-01

    A review is given of several important defect production and accumulation parameters for irradiated ceramics. Materials covered in this review include alumina, magnesia, spinel silicon carbide, silicon nitride, aluminum nitride and diamond. Whereas threshold displacement energies for many ceramics are known within a reasonable level of uncertainty (with notable exceptions being AIN and Si{sub 3}N{sub 4}), relatively little information exists on the equally important parameters of surviving defect fraction (defect production efficiency) and point defect migration energies for most ceramics. Very little fundamental displacement damage information is available for nitride ceramics. The role of subthreshold irradiation on defect migration and microstructural evolution is also briefly discussed.

  9. Ceramic piezoelectric materials

    International Nuclear Information System (INIS)

    Kaszuwara, W.

    2004-01-01

    Ceramic piezoelectric materials conert reversibility electric energy into mechanical energy. In the presence of electric field piezoelectric materials exhibit deformations up to 0.15% (for single crystals up to 1.7%). The deformation energy is in the range of 10 2 - 10 3 J/m 3 and working frequency can reach 10 5 Hz. Ceramic piezoelectric materials find applications in many modern disciplines such as: automatics, micromanipulation, measuring techniques, medical diagnostics and many others. Among the variety of ceramic piezoelectric materials the most important appear to be ferroelectric materials such as lead zirconate titanate so called PZT ceramics. Ceramic piezoelectric materials can be processed by methods widely applied for standard ceramics, i.e. starting from simple precursors e.g. oxides. Application of sol-gel method has also been reported. Substantial drawback for many applications of piezoelectric ceramics is their brittleness, thus much effort is currently being put in the development of piezoelectric composite materials. Other important research directions in the field of ceramic piezoelectric materials composite development of lead free materials, which can exhibit properties similar to the PZT ceramics. Among other directions one has to state processing of single crystals and materials having texture or gradient structure. (author)

  10. Novel vaccines targeting dendritic cells by coupling allergoids to nonoxidized mannan enhance allergen uptake and induce functional regulatory T cells through programmed death ligand 1.

    Science.gov (United States)

    Sirvent, Sofía; Soria, Irene; Cirauqui, Cristina; Cases, Bárbara; Manzano, Ana I; Diez-Rivero, Carmen M; Reche, Pedro A; López-Relaño, Juan; Martínez-Naves, Eduardo; Cañada, F Javier; Jiménez-Barbero, Jesús; Subiza, Javier; Casanovas, Miguel; Fernández-Caldas, Enrique; Subiza, José Luis; Palomares, Oscar

    2016-08-01

    Allergen immunotherapy (AIT) is the only curative treatment for allergy. AIT faces pitfalls related to efficacy, security, duration, and patient compliance. Novel vaccines overcoming such inconveniences are in demand. We sought to study the immunologic mechanisms of action for novel vaccines targeting dendritic cells (DCs) generated by coupling glutaraldehyde-polymerized grass pollen allergoids to nonoxidized mannan (PM) compared with glutaraldehyde-polymerized allergoids (P) or native grass pollen extracts (N). Skin prick tests and basophil activation tests with N, P, or PM were performed in patients with grass pollen allergy. IgE-blocking experiments, flow cytometry, confocal microscopy, cocultures, suppression assays, real-time quantitative PCR, ELISAs, and ELISpot assays were performed to assess allergen capture by human DCs and T-cell responses. BALB/c mice were immunized with PM, N, or P. Antibody levels, cytokine production by splenocytes, and splenic forkhead box P3 (FOXP3)(+) regulatory T (Treg) cells were quantified. Experiments with oxidized PM were also performed. PM displays in vivo hypoallergenicity, induces potent blocking antibodies, and is captured by human DCs much more efficiently than N or P by mechanisms depending on mannose receptor- and dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin-mediated internalization. PM endorses human DCs to generate functional FOXP3(+) Treg cells through programmed death ligand 1. Immunization of mice with PM induces a shift to nonallergic responses and increases the frequency of splenic FOXP3(+) Treg cells. Mild oxidation impairs these effects in human subjects and mice, demonstrating the essential role of preserving the carbohydrate structure of mannan. Allergoids conjugated to nonoxidized mannan represent suitable vaccines for AIT. Our findings might also be of the utmost relevance to development of therapeutic interventions in other immune tolerance-related diseases. Copyright

  11. Interfacing design and making of Ceramics

    DEFF Research Database (Denmark)

    Hansen, Flemming Tvede

    2014-01-01

    investigates the idea of an interactive digital design tool for designing wall like composition with 3d ceramics and is working on two levels. One which has to do with a digital interactive system that responds on the movement of the hands; at a certain distance the user’s hands appear on a monitor screen......This research investigates the relationship between crafting materiality and digital representation, and how experiential knowledge of crafts rooted in ceramics can be transformed and utilized in the use of digital technologies. Thus the research refers to the overall theme Materiality...... and Aesthetics in the conference. Digital technology as 3D printing with ceramic allows to bridge from the digital design environment to fabrication. At the same time novel digital means can create new interfaces between the human, space and the material. Here advances in 3d motion capture technology and sensors...

  12. Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    The Ceramic Technology Project was developed by the USDOE Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the USDOE and NASA advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. These programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. A five-year project plan was developed with extensive input from private industry. In July 1990 the original plan was updated through the estimated completion of development in 1993. The objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities.

  13. Damage Assessment in TiB2 Ceramic Armor Targets

    National Research Council Canada - National Science Library

    Rupert, Nevin

    2001-01-01

    The interaction between long rods and ceramics is only partially understood; however, this understanding is essential in the design of improved performance of impact-resistant materials and armor system design applications...

  14. New ceramic materials

    International Nuclear Information System (INIS)

    Moreno, R.; Dominguez-Rodriguez, A.

    2010-01-01

    This article is to provide a new ceramic materials in which, with a control of their processing and thus their microstructural properties, you can get ceramic approaching ever closer to a metal, both in its structural behavior at low as at high temperatures. (Author) 30 refs.

  15. Mounting for ceramic scroll

    Science.gov (United States)

    Petty, Jack D.

    1993-01-01

    A mounting for a ceramic scroll on a metal engine block of a gas turbine engine includes a first ceramic ring and a pair of cross key connections between the first ceramic ring, the ceramic scroll, and the engine block. The cross key connections support the scroll on the engine block independent of relative radial thermal growth and for bodily movement toward an annular mounting shoulder on the engine. The scroll has an uninterrupted annular shoulder facing the mounting shoulder on the engine block. A second ceramic ring is captured between mounting shoulder and the uninterrupted shoulder on the scroll when the latter is bodily shifted toward the mouting shoulder to define a gas seal between the scroll and the engine block.

  16. Ceramic heat exchanger

    Science.gov (United States)

    LaHaye, Paul G.; Rahman, Faress H.; Lebeau, Thomas P. E.; Severin, Barbara K.

    1998-01-01

    A tube containment system. The tube containment system does not significantly reduce heat transfer through the tube wall. The contained tube is internally pressurized, and is formed from a ceramic material having high strength, high thermal conductivity, and good thermal shock resistance. The tube containment system includes at least one ceramic fiber braid material disposed about the internally pressurized tube. The material is disposed about the tube in a predetermined axial spacing arrangement. The ceramic fiber braid is present in an amount sufficient to contain the tube if the tube becomes fractured. The tube containment system can also include a plurality of ceramic ring-shaped structures, in contact with the outer surface of the tube, and positioned between the tube and the ceramic fiber braid material, and/or at least one transducer positioned within tube for reducing the internal volume and, therefore, the energy of any shrapnel resulting from a tube fracture.

  17. Sensitive Ceramics_Pattern #1-#5

    DEFF Research Database (Denmark)

    2014-01-01

    pattern of which are reflecting the position and speed of the hands. In that way the user is able to interact and model a responding pattern. The second level has to do with realizing the modules in ceramics by 3d printing directly in porcelain with a RapMan printer that coils up the 3d shape in layers...

  18. Using the Voice to Design Ceramics

    DEFF Research Database (Denmark)

    Tvede Hansen, Flemming; Jensen, Kristoffer

    2011-01-01

    Digital technology makes new possibilities in ceramic craft. This project is about how experiential knowledge that the craftsmen gains in a direct physical and tactile interaction with a responding material can be transformed and utilized in the use of digital technologies. The project presents...

  19. Development in laser peening of advanced ceramics

    Science.gov (United States)

    Shukla, Pratik; Smith, Graham C.; Waugh, David G.; Lawrence, Jonathan

    2015-07-01

    Laser peening is a well-known process applicable to surface treat metals and alloys in various industrial sectors. Research in the area of laser peening of ceramics is still scarce and a complete laser-ceramic interaction is still unreported. This paper focuses on laser peening of SiC ceramics employed for cutting tools, armor plating, dental and biomedical implants, with a view to elucidate the unreported work. A detailed investigation was conducted with 1064nm Nd:YAG ns pulse laser to first understand the surface effects, namely: the topography, hardness, KIc and the microstructure of SiC advanced ceramics. The results showed changes in surface roughness and microstructural modification after laser peening. An increase in surface hardness was found by almost 2 folds, as the diamond footprints and its flaws sizes were considerably reduced, thus, enhancing the resistance of SiC to better withstand mechanical impact. This inherently led to an enhancement in the KIc by about 42%. This is attributed to an induction of compressive residual stress and phase transformation. This work is a first-step towards the development of a 3-dimensional laser peening technique to surface treat many advanced ceramic components. This work has shown that upon tailoring the laser peening parameters may directly control ceramic topography, microstructure, hardness and the KIc. This is useful for increasing the performance of ceramics used for demanding applications particularly where it matters such as in military. Upon successful peening of bullet proof vests could result to higher ballistic strength and resistance against higher sonic velocity, which would not only prevent serious injuries, but could also help to save lives of soldiers on the battle fields.

  20. Experiences with voice to design ceramics

    DEFF Research Database (Denmark)

    Hansen, Flemming Tvede; Jensen, Kristoffer

    2014-01-01

    This article presents SoundShaping, a system to create ceramics from the human voice and thus how digital technology makes new possibilities in ceramic craft. The article is about how experiential knowledge that the craftsmen gains in a direct physical and tactile interaction with a responding...... material can be transformed and utilised in the use of digital technologies. SoundShaping is based on a generic audio feature extraction system and the principal component analysis to ensure that the pertinent information in the voice is used. Moreover, 3D shape is created using simple geometric rules....... The shape is output to a 3D printer to make ceramic results. The system demonstrates the close connection between digital technology and craft practice. Several experiments and reflections demonstrate the validity of this work....

  1. Experiences with Voice to Design Ceramics

    DEFF Research Database (Denmark)

    Hansen, Flemming Tvede; Jensen, Kristoffer

    2013-01-01

    This article presents SoundShaping, a system to create ceramics from the human voice and thus how digital technology makes new possibilities in ceramic craft. The article is about how experiential knowledge that the craftsmen gains in a direct physical and tactile interaction with a responding...... material can be transformed and utilized in the use of digital technologies. SoundShaping is based on a generic audio feature extraction system and the principal component analysis to ensure that the pertinent information in the voice is used. Moreover, 3D shape is created using simple geometric rules....... The shape is output to a 3D printer to make ceramic results. The system demonstrates the close connection between digital technology and craft practice. Several experiments and reflections demonstrate the validity of this work....

  2. Using the Voice to Design Ceramics

    DEFF Research Database (Denmark)

    Hansen, Flemming Tvede; Jensen, Kristoffer

    2011-01-01

    Digital technology makes new possibilities in ceramic craft. This project is about how experiential knowledge that the craftsmen gains in a direct physical and tactile interaction with a responding material can be transformed and utilized in the use of digital technologies. The project presents...... to make ceramic results. The system demonstrates the close connection between digital technology and craft practice....... SoundShaping, a system to create ceramics from the human voice. Based on a generic audio feature extraction system, and the principal component analysis to ensure that the pertinent information in the voice is used, a 3D shape is created using simple geometric rules. This shape is output to a 3D printer...

  3. Ceramic breeder materials

    International Nuclear Information System (INIS)

    Johnson, C.E.

    1990-01-01

    The breeding blanket is a key component of the fusion reactor because it directly involves tritium breeding and energy extraction, both of which are critical to development of fusion power. The lithium ceramics continue to show promise as candidate breeder materials. This promise was recognized by the International Thermonuclear Reactor (ITER) design team in its selection of ceramics as the first option for the ITER breeder material. Blanket design studies have indicated properties in the candidate materials data base that need further investigation. Current studies are focusing on tritium release behavior at high burnup, changes in thermophysical properties with burnup, compatibility between the ceramic breeder and beryllium multiplier, and phase changes with burnup. Laboratory and in-reactor tests, some as part of an international collaboration for development of ceramic breeder materials, are underway. 32 refs., 1 fig., 1 tab

  4. Corrosion resistant ceramic materials

    Science.gov (United States)

    Kaun, T.D.

    1996-07-23

    Ceramic materials are disclosed which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200--550 C or organic salt (including SO{sub 2} and SO{sub 2}Cl{sub 2}) at temperatures of 25--200 C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components. 1 fig.

  5. Ceramic injection molding

    International Nuclear Information System (INIS)

    Agueda, Horacio; Russo, Diego

    1988-01-01

    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) [es

  6. Applications of Piezoelectric Ceramics

    Indian Academy of Sciences (India)

    Applications of Piezoelectric Ceramics. Piezoelectric Actuators. Nano and Micropositioners. Vibration Control Systems. Computer Printers. Piezoelectric Transformers,Voltage Generators, Spark Plugs, Ultrasonic Motors,. Ultrasonic Generators and Sensors. Sonars, Medical Diagnostic. Computer Memories. NVFRAM ...

  7. Corrosion resistant ceramic materials

    Science.gov (United States)

    Kaun, Thomas D.

    1996-01-01

    Ceramic materials which exhibit stability in severely-corrosive environments having high alkali-metal activity, high sulfur/sulfide activity and/or molten halides at temperatures of 200.degree.-550.degree. C. or organic salt (including SO.sub.2 and SO.sub.2 Cl.sub.2) at temperatures of 25.degree.-200.degree. C. These sulfide ceramics form stoichiometric (single-phase) compounds with sulfides of Ca, Li, Na, K, Al, Mg, Si, Y, La, Ce, Ga, Ba, Zr and Sr and show melting-points that are sufficiently low and have excellent wettability with many metals (Fe, Ni, Mo) to easily form metal/ceramic seals. Ceramic compositions are also formulated to adequately match thermal expansion coefficient of adjacent metal components.

  8. Making Ceramic Cameras

    Science.gov (United States)

    Squibb, Matt

    2009-01-01

    This article describes how to make a clay camera. This idea of creating functional cameras from clay allows students to experience ceramics, photography, and painting all in one unit. (Contains 1 resource and 3 online resources.)

  9. "A New Class of Creep Resistant Oxide/Oxide Ceramic Matrix Composites"

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Mohit Jain, Dr. Ganesh Skandan, Prof. Roger Cannon, Rutgers University

    2007-03-30

    Despite recent progress in the development of SiC-SiC ceramic matrix composites (CMCs), their application in industrial gas turbines for distributed energy (DE) systems has been limited. The poor oxidation resistance of the non-oxide ceramics warrants the use of envrionmental barrier coatings (EBCs), which in turn lead to issues pertaining to life expectancy of the coatings. On the other hand, oxide/oxide CMCs are potential replacements, but their use has been limited until now due to the poor creep resistance at high temperatures, particularly above 1200 oC: the lack of a creep resistant matrix has been a major limiting factor. Using yttrium aluminum garnet (YAG) as the matrix material system, we have advanced the state-of-the-art in oxide/oxide CMCs by introducing innovations in both the structure and composition of the matrix material, thereby leading to high temperature matrix creep properties not achieved until now. An array of YAG-based powders with a unique set of particle characteristics were produced in-house and sintered to full density and compressive creep data was obtained. Aided in part by the composition and the microstructure, the creep rates were found to be two orders of magnitude smaller than the most creep resistant oxide fiber available commercially. Even after accounting for porosity and a smaller matrix grain size in a practical CMC component, the YAG-based matrix material was found to creep slower than the most creep resistant oxide fiber available commercially.

  10. Selecting Ceramics - Introduction

    OpenAIRE

    Cassidy, M.

    2002-01-01

    AIM OF PRESENTATION: To compare a number of materials for extracoronal restoration of teeth with particular reference to CAD-CAM ceramics. CASE DESCRIPTION AND TREATMENT CARRIED OUT: This paper will be illustrated using clinical examples of patients treated using different ceramic restorations to present the advantages and disadvantages and each technique. The different requirements of tooth preparation, impression taking and technical procedures of each system will be presented and compar...

  11. Cavitation damage of ceramics

    International Nuclear Information System (INIS)

    Kovalenko, V.I.; Marinin, V.G.

    1988-01-01

    Consideration is given to results of investigation of ceramic material damage under the effect of cavitation field on their surface, formed in water under the face of exponential concentrator, connected with ultrasonic generator UZY-3-0.4. Amplitude of vibrations of concentrator face (30+-2)x10 -6 m, frequency-21 kHz. It was established that ceramics resistance to cavitation effect correlated with the product of critical of stress intensity factor and material hardness

  12. Role of Oxygen in Ionic Liquid Gating on Two-Dimensional Cr2Ge2Te6: A Non-oxide Material.

    Science.gov (United States)

    Chen, Yangyang; Xing, Wenyu; Wang, Xirui; Shen, Bowen; Yuan, Wei; Su, Tang; Ma, Yang; Yao, Yunyan; Zhong, Jiangnan; Yun, Yu; Xie, X C; Jia, Shuang; Han, Wei

    2018-01-10

    Ionic liquid gating can markedly modulate a material's carrier density so as to induce metallization, superconductivity, and quantum phase transitions. One of the main issues is whether the mechanism of ionic liquid gating is an electrostatic field effect or an electrochemical effect, especially for oxide materials. Recent observation of the suppression of the ionic liquid gate-induced metallization in the presence of oxygen for oxide materials suggests the electrochemical effect. However, in more general scenarios, the role of oxygen in the ionic liquid gating effect is still unclear. Here, we perform ionic liquid gating experiments on a non-oxide material: two-dimensional ferromagnetic Cr 2 Ge 2 Te 6 . Our results demonstrate that despite the large increase of the gate leakage current in the presence of oxygen, the oxygen does not affect the ionic liquid gating effect on  the channel resistance of Cr 2 Ge 2 Te 6 devices (ionic liquid gating is more effective on the modulation of the channel resistances compared to the back gating across the 300 nm thick SiO 2 .

  13. Linkages between the life-history evolution of tropical and temperate birds and the resistance of cultured skin fibroblasts to oxidative and non-oxidative chemical injury.

    Science.gov (United States)

    Jimenez, Ana Gabriela; Harper, James M; Queenborough, Simon A; Williams, Joseph B

    2013-04-15

    A fundamental challenge facing physiological ecologists is to understand how variation in life history at the whole-organism level might be linked to cellular function. Thus, because tropical birds have higher annual survival and lower rates of metabolism, we hypothesized that cells from tropical species would have greater cellular resistance to chemical injury than cells from temperate species. We cultured dermal fibroblasts from 26 tropical and 26 temperate species of birds and examined cellular resistance to cadmium, H(2)O(2), paraquat, thapsigargin, tunicamycium, methane methylsulfonate (MMS) and UV light. Using ANCOVA, we found that the values for the dose that killed 50% of cells (LD(50)) from tropical birds were significantly higher for H(2)O(2) and MMS. When we tested for significance using a generalized least squares approach accounting for phylogenetic relationships among species to model LD(50), we found that cells from tropical birds had greater tolerance for Cd, H(2)O(2), paraquat, tunicamycin and MMS than cells from temperate birds. In contrast, tropical birds showed either lower or no difference in tolerance to thapsigargin and UV light in comparison with temperate birds. These findings are consistent with the idea that natural selection has uniquely fashioned cells of long-lived tropical bird species to be more resistant to forms of oxidative and non-oxidative stress than cells from shorter-lived temperate species.

  14. Bifunctional composite catalysts using Co3O4 nanofibers immobilized on nonoxidized graphene nanoflakes for high-capacity and long-cycle Li-O2 batteries.

    Science.gov (United States)

    Ryu, Won-Hee; Yoon, Taek-Han; Song, Sung Ho; Jeon, Seokwoo; Park, Yong-Joon; Kim, Il-Doo

    2013-09-11

    Designing a highly efficient catalyst is essential to improve the electrochemical performance of Li-O2 batteries for long-term cycling. Furthermore, these batteries often show significant capacity fading due to the irreversible reaction characteristics of the Li2O2 product. To overcome these limitations, we propose a bifunctional composite catalyst composed of electrospun one-dimensional (1D) Co3O4 nanofibers (NFs) immobilized on both sides of the 2D nonoxidized graphene nanoflakes (GNFs) for an oxygen electrode in Li-O2 batteries. Highly conductive GNFs with noncovalent functionalization can facilitate a homogeneous dispersion in solution, thereby enabling simple and uniform attachment of 1D Co3O4 NFs on GNFs without restacking. High first discharge capacity of 10 500 mAh/g and superior cyclability for 80 cycles with a limited capacity of 1000 mAh/g were achieved by (i) improved catalytic activity of 1D Co3O4 NFs with large surface area, (ii) facile electron transport via interconnected GNFs functionalized by Co3O4 NFs, and (iii) fast O2 diffusion through the ultrathin GNF layer and porous Co3O4 NF networks.

  15. Large ceramics for fusion applications

    International Nuclear Information System (INIS)

    Hauth, W.E.; Stoddard, S.D.

    1979-01-01

    Prominent ceramic raw materials and products manufacturers were surveyed to determine the state of the art for alumina ceramic fabrication. This survey emphasized current capabilities and limitations for fabrication of large, high-density, high-purity, complex shapes. Some directions are suggested for future needs and development. Ceramic-to-ceramic sealing has applications for several technologies that require large and/or complex vacuum-tight ceramic shapes. Information is provided concerning the assembly of complex monolithic ceramic shapes by bonding of subassemblies at temperatures ranging from 450 to 1500 0 C. Future applications and fabrication techniques for various materials are presented

  16. Clinical application of bio ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Anu, Sharma, E-mail: issaranu@gmail.com; Gayatri, Sharma, E-mail: sharmagayatri@gmail.com [Department of Chemistry, Govt. College of Engineering & Technology, Bikaner, Rajasthan (India)

    2016-05-06

    Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

  17. The history of ceramic filters.

    Science.gov (United States)

    Fujishima, S

    2000-01-01

    The history of ceramic filters is surveyed. Included is the history of piezoelectric ceramics. Ceramic filters were developed using technology similar to that of quartz crystal and electro-mechanical filters. However, the key to this development involved the theoretical analysis of vibration modes and material improvements of piezoelectric ceramics. The primary application of ceramic filters has been for consumer-market use. Accordingly, a major emphasis has involved mass production technology, leading to low-priced devices. A typical ceramic filter includes monolithic resonators and capacitors packaged in unique configurations.

  18. Clinical application of bio ceramics

    International Nuclear Information System (INIS)

    Anu, Sharma; Gayatri, Sharma

    2016-01-01

    Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

  19. Surface modification of ceramics. Ceramics no hyomen kaishitsu

    Energy Technology Data Exchange (ETDEWEB)

    Hioki, T. (Toyota Central Research and Development Labs., Inc., Nagoya (Japan))

    1993-07-05

    Surface modification of ceramics and some study results using in implantation in surface modification are introduced. The mechanical properties (strength, fracture toughness, flaw resistance) of ceramics was improved and crack was repaired using surface modification by ion implantation. It is predicted that friction and wear properties are considerably affected because the hardness of ceramics is changed by ion implantation. Cementing and metalization are effective as methods for interface modification and the improvement of the adhesion power of the interface between metal and ceramic is their example. It was revealed that the improvement of mechanical properties of ceramics was achieved if appropriate surface modification was carried out. The market of ceramics mechanical parts is still small, therefore, the present situation is that the field of activities for surface modification of ceramics is also narrow. However, it is thought that in future, ceramics use may be promoted surely in the field like medicine and mechatronics. 8 refs., 4 figs.

  20. Current Progress in Bioactive Ceramic Scaffolds for Bone Repair and Regeneration

    Science.gov (United States)

    Gao, Chengde; Deng, Youwen; Feng, Pei; Mao, Zhongzheng; Li, Pengjian; Yang, Bo; Deng, Junjie; Cao, Yiyuan; Shuai, Cijun; Peng, Shuping

    2014-01-01

    Bioactive ceramics have received great attention in the past decades owing to their success in stimulating cell proliferation, differentiation and bone tissue regeneration. They can react and form chemical bonds with cells and tissues in human body. This paper provides a comprehensive review of the application of bioactive ceramics for bone repair and regeneration. The review systematically summarizes the types and characters of bioactive ceramics, the fabrication methods for nanostructure and hierarchically porous structure, typical toughness methods for ceramic scaffold and corresponding mechanisms such as fiber toughness, whisker toughness and particle toughness. Moreover, greater insights into the mechanisms of interaction between ceramics and cells are provided, as well as the development of ceramic-based composite materials. The development and challenges of bioactive ceramics are also discussed from the perspective of bone repair and regeneration. PMID:24646912

  1. [Ceramic-on-ceramic bearings in total hip arthroplasty (THA)].

    Science.gov (United States)

    Sentürk, U; Perka, C

    2015-04-01

    The main reason for total hip arthroplasty (THA) revision is the wear-related aseptic loosening. Younger and active patients after total joint replacement create high demands, in particular, on the bearings. The progress, especially for alumina ceramic-on-ceramic bearings and mixed ceramics have solved many problems of the past and lead to good in vitro results. Modern ceramics (alumina or mixed ceramics containing alumina) are extremely hard, scratch-resistant, biocompatible, offer a low coefficient of friction, superior lubrication and have the lowest wear rates in comparison to all other bearings in THA. The disadvantage of ceramic is the risk of material failure, i.e., of ceramic fracture. The new generation of mixed ceramics (delta ceramic), has reduced the risk of head fractures to 0.03-0.05 %, but the risk for liner fractures remains unchanged at about 0.02 %. Assuming a non-impinging component implantation, ceramic-on-ceramic bearings have substantial advantages over all other bearings in THA. Due to the superior hardness, ceramic bearings produce less third body wear and are virtually impervious to damage from instruments during the implantation process. A specific complication for ceramic-on-ceramic bearings is "squeaking". The high rate of reported squeaking (0.45 to 10.7 %) highlights the importance of precise implant positioning and the stem and patient selection. With precise implant positioning this problem is rare with many implant designs and without clinical relevance. The improved tribology and the presumable resulting implant longevity make ceramic-on-ceramic the bearing of choice for young and active patients. Georg Thieme Verlag KG Stuttgart · New York.

  2. Numerical modelling of evaporation in a ceramic layer in the tape casting process

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Jambhekar, V. A.; Hattel, Jesper Henri

    2016-01-01

    Evaporation of water from a ceramic layer is a key phenomenon in the drying process for the manufacturing of tape cast ceramics. This process contains mass, momentum and energy exchange between the porous medium and the free-flow region. In order to analyze such interaction processes, a Represent......Evaporation of water from a ceramic layer is a key phenomenon in the drying process for the manufacturing of tape cast ceramics. This process contains mass, momentum and energy exchange between the porous medium and the free-flow region. In order to analyze such interaction processes...

  3. Testing method for ceramic armour and bare ceramic tiles

    NARCIS (Netherlands)

    Carton, E.P.; Roebroeks, G.H.J.J.

    2016-01-01

    TNO developed an alternative, more configuration independent ceramic test method than the Depth-of-Penetration test method. In this alternative test ceramic tiles and ceramic based armour are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

  4. Testing method for ceramic armor and bare ceramic tiles

    NARCIS (Netherlands)

    Carton, E.P.; Roebroeks, G.H.J.J.

    2014-01-01

    TNO has developed an alternative, more configuration independent ceramic test method than the standard Depth-of-Penetration test method. In this test ceramic tiles and ceramic based armor are evaluated as target without a semi-infinite backing layer. An energy approach is chosen to evaluate and rank

  5. Mechanical properties of ceramics

    CERN Document Server

    Pelleg, Joshua

    2014-01-01

    This book discusses the mechanical properties of ceramics and aims to provide both a solid background for undergraduate students, as well as serving as a text to bring practicing engineers up to date with the latest developments in this topic so they can use and apply these to their actual engineering work.  Generally, ceramics are made by moistening a mixture of clays, casting it into desired shapes and then firing it to a high temperature, a process known as 'vitrification'. The relatively late development of metallurgy was contingent on the availability of ceramics and the know-how to mold them into the appropriate forms. Because of the characteristics of ceramics, they offer great advantages over metals in specific applications in which hardness, wear resistance and chemical stability at high temperatures are essential. Clearly, modern ceramics manufacturing has come a long way from the early clay-processing fabrication method, and the last two decades have seen the development of sophisticated technique...

  6. Fatigue of dental ceramics.

    Science.gov (United States)

    Zhang, Yu; Sailer, Irena; Lawn, Brian R

    2013-12-01

    Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics. The nature of various fatigue modes is elucidated using fracture test data on ceramic layer specimens from the dental and biomechanics literature. Failure modes can change over a lifetime, depending on restoration geometry, loading conditions and material properties. Modes that operate in single-cycle loading may be dominated by alternative modes in multi-cycle loading. While post-mortem examination of failed prostheses can determine the sources of certain fractures, the evolution of these fractures en route to failure remains poorly understood. Whereas it is commonly held that loss of load-bearing capacity of dental ceramics in repetitive loading is attributable to chemically assisted 'slow crack growth' in the presence of water, we demonstrate the existence of more deleterious fatigue mechanisms, mechanical rather than chemical in nature. Neglecting to account for mechanical fatigue can lead to gross overestimates in predicted survival rates. Strategies for prolonging the clinical lifetimes of ceramic restorations are proposed based on a crack-containment philosophy. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Ceramic combustor mounting

    Science.gov (United States)

    Hoffman, Melvin G.; Janneck, Frank W.

    1982-01-01

    A combustor for a gas turbine engine includes a metal engine block including a wall portion defining a housing for a combustor having ceramic liner components. A ceramic outlet duct is supported by a compliant seal on the metal block and a reaction chamber liner is stacked thereon and partly closed at one end by a ceramic bypass swirl plate which is spring loaded by a plurality of circumferentially spaced, spring loaded guide rods and wherein each of the guide rods has one end thereof directed exteriorly of a metal cover plate on the engine block to react against externally located biasing springs cooled by ambient air and wherein the rod spring support arrangement maintains the stacked ceramic components together so that a normal force is maintained on the seal between the outlet duct and the engine block under all operating conditions. The support arrangement also is operative to accommodate a substantial difference in thermal expansion between the ceramic liner components of the combustor and the metal material of the engine block.

  8. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2000-10-01

    This is the third quarterly report on oxygen Transport Ceramic Membranes. In the following, the report describes the progress made by our university partners in Tasks 1 through 6, experimental apparatus that was designed and built for various tasks of this project, thermodynamic calculations, where applicable and work planned for the future. (Task 1) Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. (Task 2) Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. (Task 3) Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. (Task 4) Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. (Task 5) Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. (Task 6) Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques.

  9. Ceramic impregnated superabrasives

    Science.gov (United States)

    Radtke, Robert P.; Sherman, Andrew

    2009-02-10

    A superabrasive fracture resistant compact is formed by depositing successive layers of ceramic throughout the network of open pores in a thermally stable self-bonded polycrystalline diamond or cubic boron nitride preform. The void volume in the preform is from approximately 2 to 10 percent of the volume of the preform, and the average pore size is below approximately 3000 nanometers. The preform is evacuated and infiltrated under at least about 1500 pounds per square inch pressure with a liquid pre-ceramic polymerizable precursor. The precursor is infiltrated into the preform at or below the boiling point of the precursor. The precursor is polymerized into a solid phase material. The excess is removed from the outside of the preform, and the polymer is pyrolized to form a ceramic. The process is repeated at least once more so as to achieve upwards of 90 percent filling of the original void volume. When the remaining void volume drops below about 1 percent the physical properties of the compact, such as fracture resistance, improve substantially. Multiple infiltration cycles result in the deposition of sufficient ceramic to reduce the void volume to below 0.5 percent. The fracture resistance of the compacts in which the pores are lined with formed in situ ceramic is generally at least one and one-half times that of the starting preforms.

  10. Diffusion in ceramics

    CERN Document Server

    Pelleg, Joshua

    2016-01-01

    This textbook provides an introduction to changes that occur in solids such as ceramics, mainly at high temperatures, which are diffusion controlled, as well as presenting research data. Such changes are related to the kinetics of various reactions such as precipitation, oxidation and phase transformations, but are also related to some mechanical changes, such as creep. The book is composed of two parts, beginning with a look at the basics of diffusion according to Fick's Laws. Solutions of Fick’s second law for constant D, diffusion in grain boundaries and dislocations are presented along with a look at the atomistic approach for the random motion of atoms. In the second part, the author discusses diffusion in several technologically important ceramics. The ceramics selected are monolithic single phase ones, including: A12O3, SiC, MgO, ZrO2 and Si3N4. Of these, three refer to oxide ceramics (alumina, magnesia and zirconia). Carbide based ceramics are represented by the technologically very important Si-ca...

  11. FIB/SEM and SEM/EDS microstructural analysis of metal-ceramic and zirconia-ceramic interfaces.

    Science.gov (United States)

    Massimi, F; Merlati, G; Sebastiani, M; Battaini, P; Menghini, P; Bemporad, E

    2012-01-10

    Recently introduced FIB/SEM analysis in microscopy seems to provide a high-resolution characterization of the samples by 3D (FIB) cross-sectioning and (SEM) high resolution imaging. The aim of this study was to apply the FIB/SEM and SEM/EDS analysis to the interfaces of a metal-ceramic vs. two zirconia-ceramic systems. Plate samples of three different prosthetic systems were prepared in the dental lab following the manufacturers' instructions, where metal-ceramic was the result of a ceramic veneering (porcelain-fused-to-metal) and the two zirconia-ceramic systems were produced by the dedicated CAD-CAM procedures of the zirconia cores (both with final sintering) and then veneered by layered or heat pressed ceramics. In a FIB/SEM equipment (also called DualBeam), a thin layer of platinum (1 μm) was deposited on samples surface crossing the interfaces, in order to protect them during milling. Then, increasingly deeper trenches were milled by a focused ion beam, first using a relatively higher and later using a lower ion current (from 9 nA to 0.28 nA, 30KV). Finally, FEG-SEM (5KV) micrographs (1000-50,000X) were acquired. In a SEM the analysis of the morphology and internal microstructure was performed by 13KV secondary and backscattered electrons signals (in all the samples). The compositional maps were then performed by EDS probe only in the metal-ceramic system (20kV). Despite the presence of many voids in all the ceramic layers, it was possible to identify: (1) the grain structures of the metallic and zirconia substrates, (2) the thin oxide layer at the metal-ceramic interface and its interactions with the first ceramic layer (wash technique), (3) the roughness of the two different zirconia cores and their interactions with the ceramic interface, where the presence of zirconia grains in the ceramic layer was reported in two system possibly due to sandblasting before ceramic firing.

  12. High flow ceramic pot filters

    NARCIS (Netherlands)

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more

  13. Ceramic composites: Enabling aerospace materials

    Science.gov (United States)

    Levine, S. R.

    1992-01-01

    Ceramics and ceramic matrix composites (CMC) have the potential for significant impact on the performance of aerospace propulsion and power systems. In this paper, the potential benefits are discussed in broad qualitative terms and are illustrated by some specific application case studies. The key issues in need of resolution for the potential of ceramics to be realized are discussed.

  14. Interfacing design and making of Ceramics

    DEFF Research Database (Denmark)

    Hansen, Flemming Tvede

    2014-01-01

    allow capturing spatial hand gestures and body movement in real-time. Where technology often seems to take us away from material this approach enables the designers body to be once again involved in the making. This approach builds on McCullough’s (1998) idea about a close connection between digital...... investigates the idea of an interactive digital design tool for designing wall like composition with 3d ceramics and is working on two levels. One which has to do with a digital interactive system that responds on the movement of the hands; at a certain distance the user’s hands appear on a monitor screen...... as a pattern of circles, which size and 3d inner pattern are reflecting the position and speed of the hand. The second level has to do with realizing the modules in ceramics by 3d printing directly in porcelain with a RapMan printer that coils up the 3d shape in layers....

  15. Verification of Ceramic Structures

    Science.gov (United States)

    Behar-Lafenetre, Stephanie; Cornillon, Laurence; Rancurel, Michael; De Graaf, Dennis; Hartmann, Peter; Coe, Graham; Laine, Benoit

    2012-07-01

    In the framework of the “Mechanical Design and Verification Methodologies for Ceramic Structures” contract [1] awarded by ESA, Thales Alenia Space has investigated literature and practices in affiliated industries to propose a methodological guideline for verification of ceramic spacecraft and instrument structures. It has been written in order to be applicable to most types of ceramic or glass-ceramic materials - typically Cesic®, HBCesic®, Silicon Nitride, Silicon Carbide and ZERODUR®. The proposed guideline describes the activities to be performed at material level in order to cover all the specific aspects of ceramics (Weibull distribution, brittle behaviour, sub-critical crack growth). Elementary tests and their post-processing methods are described, and recommendations for optimization of the test plan are given in order to have a consistent database. The application of this method is shown on an example in a dedicated article [7]. Then the verification activities to be performed at system level are described. This includes classical verification activities based on relevant standard (ECSS Verification [4]), plus specific analytical, testing and inspection features. The analysis methodology takes into account the specific behaviour of ceramic materials, especially the statistical distribution of failures (Weibull) and the method to transfer it from elementary data to a full-scale structure. The demonstration of the efficiency of this method is described in a dedicated article [8]. The verification is completed by classical full-scale testing activities. Indications about proof testing, case of use and implementation are given and specific inspection and protection measures are described. These additional activities are necessary to ensure the required reliability. The aim of the guideline is to describe how to reach the same reliability level as for structures made of more classical materials (metals, composites).

  16. A Nonoxidative Electrochemical Sensor Based on a Self-Doped Polyaniline/Carbon Nanotube Composite for Sensitive and Selective Detection of the Neurotransmitter Dopamine: A Review

    Directory of Open Access Journals (Sweden)

    Rishi R. Parajuli

    2008-12-01

    Full Text Available Most of the current techniques for in vivo detection of dopamine exploit the ease of oxidation of this compound. The major problem during the detection is the presence of a high concentration of ascorbic acid that is oxidized at nearly the same potential as dopamine on bare electrodes. Furthermore, the oxidation product of dopamine reacts with ascorbic acid present in samples and regenerates dopamine again, which severely limits the accuracy of the detection. Meanwhile, the product could also form a melanin-like insulating film on the electrode surface, which decreases the sensitivity of the electrode. Various surface modifications on the electrode, new materials for making the electrodes, and new electrochemical techniques have been exploited to solve these problems. Recently we developed a new electrochemical detection method that did not rely on direct oxidation of dopamine on electrodes, which may naturally solve these problems. This approach takes advantage of the high performance of our newly developed poly(anilineboronic acid/carbon nanotube composite and the excellent permselectivity of the ion-exchange polymer Nafion. The high affinity binding of dopamine to the boronic acid groups of the polymer affects the electrochemical properties of the polyaniline backbone, which act as the basis for the transduction mechanism of this non-oxidative dopamine sensor. The unique reduction capability and high conductivity of single-stranded DNA functionalized single-walled carbon nanotubes greatly improved the electrochemical activity of the polymer in a physiologically-relevant buffer, and the large surface area of the carbon nanotubes increased the density of the boronic acid receptors. The high sensitivity and selectivity of the sensor show excellent promise toward molecular diagnosis of Parkinson's disease. In this review, we will focus on the discussion of this novel detection approach, the new interferences in this detection approach, and how to

  17. Cyclic mechanical fatigue in ceramic-ceramic composites: an update

    International Nuclear Information System (INIS)

    Lewis, D. III

    1983-01-01

    Attention is given to cyclic mechanical fatigue effects in a number of ceramics and ceramic composites, including several monolithic ceramics in which significant residual stresses should be present as a result of thermal expansion mismatches and anisotropy. Fatigue is also noted in several BN-containing ceramic matrix-particulate composites and in SiC fiber-ceramic matrix composites. These results suggest that fatigue testing is imperative for ceramics and ceramic composites that are to be used in applications subject to cyclic loading. Fatigue process models are proposed which provide a rationale for fatigue effect observations, but do not as yet provide quantitative results. Fiber composite fatigue damage models indicate that design stresses in these materials may have to be maintained below the level at which fiber pullout occurs

  18. Stereolithographic processing of ceramics: Photon diffusion in colloidal dispersion

    Science.gov (United States)

    Garg, Rajeev

    The technique of ceramic stereolithography (CSL) has been developed for fabricating near net shape ceramic objects. In stereolithography, the three-dimensional computer design file of the object is sliced into thin layers. Each layer is physically fabricated by photocuring the surface of a liquid photo-polymerizable resin bath by raster scanning an ultra-violet laser across the surface of the resin. In CSL, the liquid resin is a high concentration colloidal dispersion in a solution of ultraviolet curable polymers. The ceramic green body fabricated by ceramic stereolithography technique is subjected to the post processing steps of drying, binder burnout and sintering to form a dense ceramic object. An aqueous alumina dispersion in photocuring polymers with particle volume fraction greater than 0.5 was formulated for CSL process. Low molecular weight solution polymers were found to be best suited for formulating ceramic resins due to their inherently low viscosity and favorable interactions with the ceramic dispersant. A hydroxyapatite ceramic resin was also developed for the use in the CSL technique. A model is developed to describe the photocuring process in concentrated ceramic dispersion. The curing profile in ceramic dispersion is governed by multiple scattering from the ceramic particles and absorption by the photocuring polymers. Diffusion theory of light transport is used to model the multiple scattering and absorption phenomena. It is found that diffusive transport adequately describes the phenomena of laser pulse propagation in highly concentrated colloidal dispersions. A model was developed to describe the absorption in highly concentrated ceramic dispersion. Various complex-shaped monolithic alumina and hydroxyapatite objects were fabricated by CSL and shown to possess uniform microstructure. The mechanical properties and sintering behavior of the parts fabricated by CSL are shown to be comparable to those fabricated by other ceramic processing technique

  19. Polishing of silicon based advanced ceramics

    Science.gov (United States)

    Klocke, Fritz; Dambon, Olaf; Zunke, Richard; Waechter, D.

    2009-05-01

    Silicon based advanced ceramics show advantages in comparison to other materials due to their extreme hardness, wear and creep resistance, low density and low coefficient of thermal expansion. As a matter of course, machining requires high efforts. In order to reach demanded low roughness for optical or tribological applications a defect free surface is indispensable. In this paper, polishing of silicon nitride and silicon carbide is investigated. The objective is to elaborate scientific understanding of the process interactions. Based on this knowledge, the optimization of removal rate, surface quality and form accuracy can be realized. For this purpose, fundamental investigations of polishing silicon based ceramics are undertaken and evaluated. Former scientific publications discuss removal mechanisms and wear behavior, but the scientific insight is mainly based on investigations in grinding and lapping. The removal mechanisms in polishing are not fully understood due to complexity of interactions. The role of, e.g., process parameters, slurry and abrasives, and their influence on the output parameters is still uncertain. Extensive technological investigations demonstrate the influence of the polishing system and the machining parameters on the stability and the reproducibility. It is shown that the interactions between the advanced ceramics and the polishing systems is of great relevance. Depending on the kind of slurry and polishing agent the material removal mechanisms differ. The observed effects can be explained by dominating mechanical or chemo-mechanical removal mechanisms. Therefore, hypotheses to state adequate explanations are presented and validated by advanced metrology devices, such as SEM, AFM and TEM.

  20. Interaction of low-expansion NZP ceramics with Na{sub 2}SO{sub 4} at 1000{degrees}C

    Energy Technology Data Exchange (ETDEWEB)

    Lee, W.Y.; Cooley, K.M.; Stinton, D.P.; Joslin, D.L. [Oak Ridge National Lab., TN (United States)

    1996-08-01

    The interaction between several low-expansion NZP materials and Na{sub 2}SO{sub 4} at 1000{degrees}C in pure O{sub 2} was studied. Ba{sub 1.25}Zr{sub 4}P{sub 5.5}Si{sub 0.5}O{sub 24} experienced extensive cracking and delamination upon reaction with Na{sub 2}SO{sub 4}. On the other hand, Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}P{sub 6}O{sub 24} remained intact in terms of visual appearance, and had no significant weight loss or gain. However, the ion exchange between Na{sup +} ions and Ca{sup +2} ions was observed to be sufficiently rapid to allow the penetration of the Na{sup +} ions into the test specimens in 100h. The segregation of Ca to the specimen surface was observed due to the ion exchange. Ca{sub 0.6}Mg{sub 0.4}Zr{sub 4}P{sub 6}O{sub 24} was also tested, but its stability could not properly be assessed because the as-received specimens contained a significant amount of MgZr{sub 4}P{sub 6}O{sub 24} as an impurity phase.

  1. Exhibition contribution: AN EXPERIMENT WITH THE VOICE TO DESIGN CERAMICS

    DEFF Research Database (Denmark)

    2013-01-01

    The artefacts show how experiential knowledge that the craftsmen gains in a direct physical interaction with a responding material can be transformed and utilized in the use of digital technologies. The exhibition presents an experiment with a 3D interactive and dynamic system to create ceramics ...

  2. Distorting the ceramic familiar: materiality and non-ceramic intervention, Conference, Keramik Museum, Germany

    OpenAIRE

    Livingstone, Andrew

    2009-01-01

    Invited conference speaker, Westerwald Keramik Museum, August 2009. Paper title: Distorting the ceramic familiar: materiality and non-ceramic intervention.\\ud \\ud This paper will examine the integration of non-ceramic media into the discourse of ceramics.

  3. Piezoelectric displacement in ceramics

    International Nuclear Information System (INIS)

    Stewart, M.; Cain, M.; Gee, M.

    1999-01-01

    This Good Practice Guide is intended to aid a user to perform displacement measurements on piezoelectric ceramic materials such as PZT (lead zirconium titanate) in either monolithic or multilayer form. The various measurement issues that the user must consider are addressed, and good measurement practise is described for the four most suitable methods. (author)

  4. Dense ceramic articles

    International Nuclear Information System (INIS)

    Cockbain, A.G.

    1976-01-01

    A method is described for the manufacture of articles of substantially pure dense ceramic materials, for use in severe environments. Si N is very suitable for use in such environments, but suffers from the disadvantage that it is not amenable to sintering. Some disadvantages of the methods normally used for making articles of Si N are mentioned. The method described comprises mixing a powder of the substantially pure ceramic material with an additive that promotes densification, and which is capable of nuclear transmutation into a gas when exposed to radiation, and hot pressing the mixture to form a billet. The billet is then irradiated to convert the additive into a gas which is held captive in the billet, and it is then subjected to a hot forging operation, during which the captive gas escapes and an article of substantially pure dense ceramic material is forged. The method is intended primarily for use for Si N, but may be applied to other ceramic materials. The additive may be Li or Be or their compounds, to the extent of at least 5 ppm and not more than 5% by weight. Irradiation is effected by proton or neutron bombardment. (UK)

  5. OXYGEN TRANSPORT CERAMIC MEMBRANES

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Sukumar Bandopadhyay; Dr. Nagendfra Nagabhushana

    2001-07-01

    The mechanical properties of model systems were analyzed. A reasonably accurate finite element model was implemented and a rational metric to predict the strength of ceramic/metal concentrical joints was developed. The mode of failure of the ceramic/metal joints was determined and the importance of the mechanical properties of the braze material was assessed. Thermal cycling experiments were performed on the model systems and the results were discussed. Additionally, experiments using the concept of placing diffusion barriers on the ceramic surface to limit the extent of the reaction with the braze were performed. It was also observed that the nature and morphology of the reaction zone depends greatly on the nature of the perovskite structure being used. From the experiments, it is observed that the presence of Cr in the Fe-occupied sites decreases the tendency of Fe to segregate and to precipitate out of the lattice. In these new experiments, Ni was observed to play a major role in the decomposition of the ceramic substrate.

  6. Ceramic analysis in Greece

    NARCIS (Netherlands)

    Hilditch, J.

    2016-01-01

    Scientific, analytical or ‘archaeometric’ techniques for investigating ceramic material have been used within archaeology for over 50 years and now constitute an indispensable tool for archaeologists in the Aegean world (see Jones 1986 for a detailed summary of early work in Greece and Italy) and

  7. Ceramic solid electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Goodenough, John B. [Center for Materials Science and Engineering, University of Texas at Austin, Austin, TX (United States)

    1997-02-15

    Strategies for the design of ceramic solid electrolytes are reviewed. Problems associated with stoichiometric and doped compounds are compared. In the illustration of design principles, emphasis is given to oxide-ion electrolytes for use in solid-oxide fuel cells, oxygen pumps, and oxygen sensors

  8. Coated ceramic breeder materials

    Science.gov (United States)

    Tam, Shiu-Wing; Johnson, Carl E.

    1987-01-01

    A breeder material for use in a breeder blanket of a nuclear reactor is disclosed. The breeder material comprises a core material of lithium containing ceramic particles which has been coated with a neutron multiplier such as Be or BeO, which coating has a higher thermal conductivity than the core material.

  9. Achievement report for fiscal 1990. Research and development of ceramic gas turbine (Study on its adaptability with society); 1990 nendo ceramic gas turbine no kenkyu kaihatsu seika hokokusho. Shakai tekigosei kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-05-01

    With an objective to assist proliferation of ceramic gas turbine (CGT) which is desired of being put into practical use at an early time because of its effects of energy conservation, environmental preservation, and economic influence, investigations and studies were made on the CGT systems for cogeneration and portable power generation with regard to their latent markets, utilization patterns, and durability. In Section 1, investigations were given on stocking quantity by size in civil use buildings as the back-data for identification of effects by CGT and for estimation of its proliferation; identification of electric power to heat ratio (heat quantity/electric power amount) and patterns in use of energy in industries promising in CGT introduction; and on stocking quantity, energy demand and utilization patterns in industrial facilities. In Section 2, discussions were given on heat-power characteristics of the CGT, and energy utilization systems as the feasibility study on applicability of the cogeneration using the CGT. In Section 3, discussions were given on corrosion resistance of non-oxide based ceramics in relation with durability of the CGT, and oxidation behavior of silicon carbides in high temperature steam. In Section 4, future investigation assignments were discussed. (NEDO)

  10. Wonderland of ceramics superplasticity; Ceramics chososei no sekai

    Energy Technology Data Exchange (ETDEWEB)

    Wakai, F. [National Industrial Research Inst. of Nagoya, Nagoya (Japan)

    1995-07-01

    It has been ten years since it was found that ceramics, which is strong and hard at room temperatures and does not deform at all, may exhibit a superplasticity phenomenon at high temperatures that it endlessly elongates when pulled as if it were chewing gum. This phenomenon is one of peculiar behaviours which nano-crystal ceramics, pulverized to an extent that the crystalline particle size is on the order of nanometers, show. The application of superplasticity made the material engineers`s old dream come true that hard ceramics are arbitrarily deformed and machined like metal. Using as models materials such as silicone nitride, alumina and zirconia, this paper describes the history and deformation mechanism of ceramics superplasticity, material design aiming at superplasticization and application of ceramics superplasticity to the machining technology. Furthermore, it describes the trend and future development of international joint researches on the basic surveys on ceramics superplasticity. 25 refs., 11 figs.

  11. INTERACT

    DEFF Research Database (Denmark)

    Jochum, Elizabeth; Borggreen, Gunhild; Murphey, TD

    This paper considers the impact of visual art and performance on robotics and human-computer interaction and outlines a research project that combines puppetry and live performance with robotics. Kinesics—communication through movement—is the foundation of many theatre and performance traditions ...

  12. FIBROUS CERAMIC-CERAMIC COMPOSITE MATERIALS PROCESSING AND PROPERTIES

    OpenAIRE

    Naslain , R.

    1986-01-01

    The introduction of continuous fibers in a ceramic matrix can improve its toughness, if the fiber-matrix bonding is weak enough, due to matrix microcracking and fiber pull-out. Ceramic-ceramic composite materials are processed according to liquid or gas phase techniques. The most important are made of glass, carbide, nitride or oxide matrices reinforced with carbon, SiC or Al2O3 fibers.

  13. Positron annihilation in transparent ceramics

    Science.gov (United States)

    Husband, P.; Bartošová, I.; Slugeň, V.; Selim, F. A.

    2016-01-01

    Transparent ceramics are emerging as excellent candidates for many photonic applications including laser, scintillation and illumination. However achieving perfect transparency is essential in these applications and requires high technology processing and complete understanding for the ceramic microstructure and its effect on the optical properties. Positron annihilation spectroscopy (PAS) is the perfect tool to study porosity and defects. It has been applied to investigate many ceramic structures; and transparent ceramics field may be greatly advanced by applying PAS. In this work positron lifetime (PLT) measurements were carried out in parallel with optical studies on yttrium aluminum garnet transparent ceramics in order to gain an understanding for their structure at the atomic level and its effect on the transparency and light scattering. The study confirmed that PAS can provide useful information on their microstructure and guide the technology of manufacturing and advancing transparent ceramics.

  14. Positron annihilation in transparent ceramics

    International Nuclear Information System (INIS)

    Husband, P; Selim, F A; Bartošová, I; Slugeň, V

    2016-01-01

    Transparent ceramics are emerging as excellent candidates for many photonic applications including laser, scintillation and illumination. However achieving perfect transparency is essential in these applications and requires high technology processing and complete understanding for the ceramic microstructure and its effect on the optical properties. Positron annihilation spectroscopy (PAS) is the perfect tool to study porosity and defects. It has been applied to investigate many ceramic structures; and transparent ceramics field may be greatly advanced by applying PAS. In this work positron lifetime (PLT) measurements were carried out in parallel with optical studies on yttrium aluminum garnet transparent ceramics in order to gain an understanding for their structure at the atomic level and its effect on the transparency and light scattering. The study confirmed that PAS can provide useful information on their microstructure and guide the technology of manufacturing and advancing transparent ceramics. (paper)

  15. Ceramic hot-gas filter

    Science.gov (United States)

    Connolly, E.S.; Forsythe, G.D.; Domanski, D.M.; Chambers, J.A.; Rajendran, G.P.

    1999-05-11

    A ceramic hot-gas candle filter is described having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during back pulse cleaning and is resistant to chemical degradation at high temperatures.

  16. Ceramic hot-gas filter

    Science.gov (United States)

    Connolly, Elizabeth Sokolinski; Forsythe, George Daniel; Domanski, Daniel Matthew; Chambers, Jeffrey Allen; Rajendran, Govindasamy Paramasivam

    1999-01-01

    A ceramic hot-gas candle filter having a porous support of filament-wound oxide ceramic yarn at least partially surrounded by a porous refractory oxide ceramic matrix, and a membrane layer on at least one surface thereof. The membrane layer may be on the outer surface, the inner surface, or both the outer and inner surface of the porous support. The membrane layer may be formed of an ordered arrangement of circularly wound, continuous filament oxide ceramic yarn, a ceramic filler material which is less permeable than the filament-wound support structure, or some combination of continuous filament and filler material. A particularly effective membrane layer features circularly wound filament with gaps intentionally placed between adjacent windings, and a filler material of ceramic particulates uniformly distributed throughout the gap region. The filter can withstand thermal cycling during backpulse cleaning and is resistant to chemical degradation at high temperatures.

  17. Ceramics for fusion applications

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.

    1987-01-01

    Ceramics are required for a variety of uses in both near-term fusion devices and in commercial powerplants. These materials must retain adequate structural and electrical properties under conditions of neutron, particle and ionizing irradiation; thermal and applied stresses; and physical and chemical sputtering. Ceramics such as Al 2 O 3 , MgAl 2 O 4 , BeO, Si 3 N 4 and SiC are currently under study for fusion applications, and results to date show widely-varying responses to the fusion environment. Materials can be identified today that will meet initial operating requirements, but improvements in physical properties are needed to achieve satisfactory lifetimes for critical applications. (author)

  18. Ceramics for fusion applications

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.

    1986-01-01

    Ceramics are required for a variety of uses in both near-term fusion devices and in commercial powerplants. These materials must retain adequate structural and electrical properties under conditions of neutron, particle, and ionizing irradiation; thermal and applied stresses; and physical and chemical sputtering. Ceramics such as Al 2 O 3 , MgAl 2 O 4 , BeO, Si 3 N 4 and SiC are currently under study for fusion applications, and results to date show widely-varying response to the fusion environment. Materials can be identified today which will meet initial operating requirements, but improvements in physical properties are needed to achieve satisfactory lifetimes for critical applications

  19. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  20. Advanced ceramic in structural engineering

    OpenAIRE

    Alonso Rodea, Jorge

    2012-01-01

    The work deals with "Advanced Ceramics in Structural Engineering”. Throughout this work we present the different types of ceramic that are currently in wider use, and the main research lines that are being followed. Ceramics have very interesting properties, both mechanical and electrical and refractory where we can find some of the most interesting points of inquiry. Through this work we try tounderstand this complex world, analyzing both general and specific properties of ...

  1. The technical ceramics (second part)

    International Nuclear Information System (INIS)

    Auclerc, S.; Poulain, E.

    2004-01-01

    This work deals with ceramics used in the nuclear and the automotive industries. Concerning the nuclear sector, ceramics are particularly used in reactors, in the treatment of radioactive wastes and for the storage of the ultimate wastes. Details are given about the different ceramics used. In the automobile sector, aluminium is principally used for its lightness and cordierite, basic material of catalyst supports is especially used in the automobile devices of cleansing. (O.M.)

  2. Ceramic superconductors II

    International Nuclear Information System (INIS)

    Yan, M.F.

    1988-01-01

    This volume compiles papers on ceramic superconductors. Topics include: structural patterns in High-Tc superconductors, phase equilibria of barium oxide superconductors, localized electrons in tetragonal YBa/sub 2/Cu/sub 3/O/sub 7-δ/, lattice and defect structure and properties of rare earth/alkaline earth-copper-oxide superconductors, alternate candidates for High-Tc superconductors, perovskite-structure superconductors; superconductive thin film fabrication, and superconductor/polymer composites

  3. Piezoelectric Ceramics Characterization

    National Research Council Canada - National Science Library

    Jordan, T

    2001-01-01

    ... the behavior of a piezoelectric material. We have attempted to cover the most common measurement methods as well as introduce parameters of interest. Excellent sources for more in-depth coverage of specific topics can be found in the bibliography. In most cases, we refer to lead zirconate titanate (PZT) to illustrate some of the concepts since it is the most widely used and studied piezoelectric ceramic to date.

  4. OXYGEN TRANSPORT CERAMIC MEMBRANES

    International Nuclear Information System (INIS)

    Dr. Sukumar Bandopadhyay; Dr. Nagendra Nagabhushana

    2001-01-01

    Conversion of natural gas to liquid fuels and chemicals is a major goal for the Nation as it enters the 21st Century. Technically robust and economically viable processes are needed to capture the value of the vast reserves of natural gas on Alaska's North Slope, and wean the Nation from dependence on foreign petroleum sources. Technologies that are emerging to fulfill this need are all based syngas as an intermediate. Syngas (a mixture of hydrogen and carbon monoxide) is a fundamental building block from which chemicals and fuels can be derived. Lower cost syngas translates directly into more cost-competitive fuels and chemicals. The currently practiced commercial technology for making syngas is either steam methane reforming (SMR) or a two-step process involving cryogenic oxygen separation followed by natural gas partial oxidation (POX). These high-energy, capital-intensive processes do not always produce syngas at a cost that makes its derivatives competitive with current petroleum-based fuels and chemicals. This project has the following 6 main tasks: Task 1--Design, fabricate and evaluate ceramic to metal seals based on graded ceramic powder/metal braze joints. Task 2--Evaluate the effect of defect configuration on ceramic membrane conductivity and long term chemical and structural stability. Task 3--Determine materials mechanical properties under conditions of high temperatures and reactive atmospheres. Task 4--Evaluate phase stability and thermal expansion of candidate perovskite membranes and develop techniques to support these materials on porous metal structures. Task 5--Assess the microstructure of membrane materials to evaluate the effects of vacancy-impurity association, defect clusters, and vacancy-dopant association on the membrane performance and stability. Task 6--Measure kinetics of oxygen uptake and transport in ceramic membrane materials under commercially relevant conditions using isotope labeling techniques

  5. Ion conductivity of nasicon ceramics

    International Nuclear Information System (INIS)

    Hoj, J.W.; Engell, J.

    1989-01-01

    The Nasicon ss ,Na 1 + X Zr 2 Si X P 3 - X O 12 o , X , 3, includes some of the best solid state sodium conductors known today. Compositions in the interval 1.6 , X , 2.6 show conductivities comparable to the best β double-prime-alumina ceramics. It is well known that the ion conductivity of β-alumina is strongly dependent on the texture of the ceramic. Here a similar behavior is reported for Nasicon ceramics. Ceramics of the bulk composition Na 2.94 Zr 1.49 Si 2.20 P 0.80 O 10.85 were prepared by a gel method. The final ceramics consist of Nasicon crystals with x = 2.14 and a glass phase. The grain size and texture of the ceramics were controlled by varying the thermal history of the gel based raw materials and the sintering conditions. The room temperature resistivity of the resulting ceramics varies from 3.65*10 3 ohm cm to 1.23*10 3 ohm cm. Using the temperature comparison method and estimates of the area of grain boundaries in the ceramics, the resistivity of the Nasicon phase is estimated to be 225 ohm cm at 25 degrees C. B 2 O 3 - or Al 2 O 3 -doping of the glass bearing Nasicon ceramic lower the room temperature resistivity by a factor 2 to 5. The dopants do not substitute into the Nasicon phase in substantial amounts

  6. Synthetic flux as a whitening agent for ceramic tiles

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues dos Santos, Geocris, E-mail: geocris.rodrigues@gmail.com [INNOVARE Inteligência Em Cerâmica, 13566-420 São Carlos, SP (Brazil); Departamento De Engenharia Dos Materiais, Universidade Federal De São Carlos, 13565-905 São Carlos, SP (Brazil); Salvetti, Alfredo Roque [Departamento De Física, Universidade Federal De Mato Grosso Do Sul (Brazil); Cabrelon, Marcelo Dezena [INNOVARE Inteligência Em Cerâmica, 13566-420 São Carlos, SP (Brazil); Departamento De Engenharia Dos Materiais, Universidade Federal De São Carlos, 13565-905 São Carlos, SP (Brazil); Morelli, Márcio Raymundo [Departamento De Engenharia Dos Materiais, Universidade Federal De São Carlos, 13565-905 São Carlos, SP (Brazil)

    2014-12-05

    Highlights: • The synthetic flux acts as a whitening agent of firing color in raw material ceramics. • The raw material ceramics have high levels of the iron oxides and red color. • The different process obtained red color clays with hematite and illite phases. • The whiteness ceramic obtained herein can be used in a porcelain tile industry. - Abstract: A synthetic flux is proposed as a whitening agent of firing color in tile ceramic paste during the sinterization process, thus turning the red firing color into whiteness. By using this mechanism in the ceramic substrates, the stoneware tiles can be manufactured using low cost clays with high levels of iron oxides. This method proved to be an economical as well as commercial strategy for the ceramic tile industries because, in Brazil, the deposits have iron compounds as mineral component (Fe{sub 2}O{sub 3}) in most of the raw materials. Therefore, several compositions of tile ceramic paste make use of natural raw materials, and a synthetic flux in order to understand how the interaction of the iron element, in the mechanism of firing color ceramic, occurs in this system. The bodies obtained were fired at 1100 °C for 5 min in air atmosphere to promote the color change. After the heating, the samples were submitted to X-ray diffraction (XRD) and Scanning Electron Microscope (SEM) analyses. The results showed that the change of firing color occurs because the iron element, which is initially in the crystal structure of the hematite phase, is transformed into a new crystal (clinopyroxenes phase) formed during the firing, so as to make the final firing color lighter.

  7. Fracture strength of three all-ceramic systems: Top-Ceram compared with IPS-Empress and In-Ceram.

    Science.gov (United States)

    Quran, Firas Al; Haj-Ali, Reem

    2012-03-01

    The purpose of this study was to investigate the fracture loads and mode of failure of all-ceramic crowns fabricated using Top-Ceram and compare it with all-ceramic crowns fabricated from well-established systems: IPS-Empress II, In-Ceram. Thirty all-ceramic crowns were fabricated; 10 IPS-Empress II, 10 In-Ceram alumina and 10 Top-Ceram. Instron testing machine was used to measure the loads required to introduce fracture of each crown. Mean fracture load for In-Ceram alumina [941.8 (± 221.66) N] was significantly (p > 0.05) higher than those of Top-Ceram and IPS-Empress II. There was no statistically significant difference between Top-Ceram and IPS-Empress II mean fracture loads; 696.20 (+222.20) and 534 (+110.84) N respectively. Core fracture pattern was highest seen in Top- Ceram specimens.

  8. Challenges in Modeling the Degradation of Ceramic Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Devanathan, Ramaswami; Gao, Fei; Sun, Xin

    2011-09-01

    We identify the state of the art, gaps in current understanding, and key research needs in the area of modeling the long-term degradation of ceramic waste forms for nuclear waste disposition. The directed purpose of this report is to define a roadmap for Waste IPSC needs to extend capabilities of waste degradation to ceramic waste forms, which overlaps with the needs of the subconsinuum scale of FMM interests. The key knowledge gaps are in the areas of (i) methodology for developing reliable interatomic potentials to model the complex atomic-level interactions in waste forms; (ii) characterization of water interactions at ceramic surfaces and interfaces; and (iii) extension of atomic-level insights to the long time and distance scales relevant to the problem of actinide and fission product immobilization.

  9. Challenges in Modeling the Degradation of Ceramic Waste Forms

    International Nuclear Information System (INIS)

    Devanathan, Ramaswami; Gao, Fei; Sun, Xin

    2011-01-01

    We identify the state of the art, gaps in current understanding, and key research needs in the area of modeling the long-term degradation of ceramic waste forms for nuclear waste disposition. The directed purpose of this report is to define a roadmap for Waste IPSC needs to extend capabilities of waste degradation to ceramic waste forms, which overlaps with the needs of the subconsinuum scale of FMM interests. The key knowledge gaps are in the areas of (i) methodology for developing reliable interatomic potentials to model the complex atomic-level interactions in waste forms; (ii) characterization of water interactions at ceramic surfaces and interfaces; and (iii) extension of atomic-level insights to the long time and distance scales relevant to the problem of actinide and fission product immobilization.

  10. Deodorant ceramic catalyst. Dasshu ceramics shokubai

    Energy Technology Data Exchange (ETDEWEB)

    Arai, K. (Kobe Steel Ltd., Kobe (Japan)); Naka, R. (Hitachi Ltd., Tokyo (Japan))

    1993-07-01

    Concerning debromination to be used for the filter of deodorizing device, those of long life and high deodorizing performance are demanded a great deal. As one of this kind of debromination, a deodorant ceramic catalyst (mangantid) has been developed and put for practical use as deodorant for refrigerator. In this article, the information and knowledge obtained by the development of mangantid, the features as well as several properties of the product are stated. The deodorizing methods currently used practically are roughly divided into 6 kinds such as the adsorption method, the direct combustion method, the catalytic method and the oxidation method, but each of them has its own merit and demerit, hence it is necessary to select the method in accordance with the kind of odor and its generating condition. Mangantid is a compound body of high deodorant material in a honeycomb configuration, and has the features that in comparison with the existing deordorants, its pressure loss is smaller, its deodorizing rate is bigger, and acidic, neutral and basic gaseous components can be removed in a well-balanced manner. Deodorization with mangantid has the mechanism to let the odorous component contact and react with the catalyst and change the component to the non-odorous component in the temperature range from room temperature to the low temperature region. 5 refs., 11 figs., 1 tab.

  11. Structural and Chemical Analysis of the Zirconia-Veneering Ceramic Interface.

    Science.gov (United States)

    Inokoshi, M; Yoshihara, K; Nagaoka, N; Nakanishi, M; De Munck, J; Minakuchi, S; Vanmeensel, K; Zhang, F; Yoshida, Y; Vleugels, J; Naert, I; Van Meerbeek, B

    2016-01-01

    The interfacial interaction of veneering ceramic with zirconia is still not fully understood. This study aimed to characterize morphologically and chemically the zirconia-veneering ceramic interface. Three zirconia-veneering conditions were investigated: 1) zirconia-veneering ceramic fired on sandblasted zirconia, 2) zirconia-veneering ceramic on as-sintered zirconia, and 3) alumina-veneering ceramic (lower coefficient of thermal expansion [CTE]) on as-sintered zirconia. Polished cross-sectioned ceramic-veneered zirconia specimens were examined using field emission gun scanning electron microscopy (Feg-SEM). In addition, argon-ion thinned zirconia-veneering ceramic interface cross sections were examined using scanning transmission electron microscopy (STEM)-energy dispersive X-ray spectrometry (EDS) at high resolution. Finally, the zirconia-veneering ceramic interface was quantitatively analyzed for tetragonal-to-monoclinic phase transformation and residual stress using micro-Raman spectroscopy (µRaman). Feg-SEM revealed tight interfaces for all 3 veneering conditions. High-resolution transmission electron microscopy (HRTEM) disclosed an approximately 1.0-µm transformed zone at sandblasted zirconia, in which distinct zirconia grains were no longer observable. Straight grain boundaries and angular grain corners were detected up to the interface of zirconia- and alumina-veneering ceramic with as-sintered zirconia. EDS mapping disclosed within the zirconia-veneering ceramic a few nanometers thick calcium/aluminum-rich layer, touching the as-sintered zirconia base, with an equally thick silicon-rich/aluminum-poor layer on top. µRaman revealed t-ZrO2-to-m-ZrO2 phase transformation and residual compressive stress at the sandblasted zirconia surface. The difference in CTE between zirconia- and the alumina-veneering ceramic resulted in residual tensile stress within the zirconia immediately adjacent to its interface with the veneering ceramic. The rather minor chemical

  12. Joining Dental Ceramic Layers With Glass

    Science.gov (United States)

    Saied, MA; Lloyd, IK; Haller, WK; Lawn, BR

    2011-01-01

    Objective Test the hypothesis that glass-bonding of free-form veneer and core ceramic layers can produce robust interfaces, chemically durable and aesthetic in appearance and, above all, resistant to delamination. Methods Layers of independently produced porcelains (NobelRondo™ Press porcelain, Nobel BioCare AB and Sagkura Interaction porcelain, Elephant Dental) and matching alumina or zirconia core ceramics (Procera alumina, Nobel BioCare AB, BioZyram yttria stabilized tetragonal zirconia polycrystal, Cyrtina Dental) were joined with designed glasses, tailored to match thermal expansion coefficients of the components and free of toxic elements. Scanning electron microprobe analysis was used to characterize the chemistry of the joined interfaces, specifically to confirm interdiffusion of ions. Vickers indentations were used to drive controlled corner cracks into the glass interlayers to evaluate the toughness of the interfaces. Results The glass-bonded interfaces were found to have robust integrity relative to interfaces fused without glass, or those fused with a resin-based adhesive. Significance The structural integrity of the interfaces between porcelain veneers and alumina or zirconia cores is a critical factor in the longevity of all-ceramic dental crowns and fixed dental prostheses. PMID:21802131

  13. Fracture mechanisms in lead zirconate titanate ceramics

    International Nuclear Information System (INIS)

    Freiman, S.W.; Chuck, L.; Mecholsky, J.J.; Shelleman, D.L.

    1986-01-01

    Lead Zirconate Titanate (PZT) ceramics can be formed over a wide range of PbTiO 3 /PbZrO 3 ratios and exist in a number of crystal structures. This study involved the use of various fracture mechanics techniques to determine critical fracture toughness, K /SUB IC/ , as a function of composition, microstructure, temperature, and electrical and thermal history. The results of these experiments indicate that variations in K /SUB IC/ are related to phase transformations in the material as well as to other toughening mechanisms such as twinning and microcracking. In addition, the strength and fracture toughness of selected PZT ceramics were determined using specimens in which a crack was introduced by a Vicker's hardness indentor. The variation of K /SUB IC/ with composition and microstructure was related to the extent of twin-crack interaction. Comparison of the plot of strength as a function of indentation load with that predicted from indentation fracture models indicates the presence of internal stresses which contribute to failure. The magnitude of these internal stresses has been correlated with electrical properties of the ceramic. Fractographic analysis was used to determine the magnitude of internal stresses in specimens failing from ''natural flaws.''

  14. Basic research in crystalline and noncrystalline ceramic systems. Annual report, May 1, 1975--April 1, 1976

    International Nuclear Information System (INIS)

    1976-01-01

    Activities in research programs on ceramics are reported in sections on electric conductivity and dielectric properties, microstructure and properties, ion transport and diffusion, defect interactions and grain boundary phenomena, and future developments

  15. Micromolding for ceramic microneedle arrays

    NARCIS (Netherlands)

    van Nieuwkasteele-Bystrova, Svetlana Nikolajevna; Lüttge, Regina

    2011-01-01

    The fabrication process of ceramic microneedle arrays (MNAs) is presented. This includes the manufacturing of an SU-8/Si-master, its double replication resulting in a PDMS mold for production by micromolding and ceramic sintering. The robustness of the replicated structures was tested by means of

  16. Ceramics in nuclear waste management

    Energy Technology Data Exchange (ETDEWEB)

    Chikalla, T D; Mendel, J E [eds.

    1979-05-01

    Seventy-three papers are included, arranged under the following section headings: national programs for the disposal of radioactive wastes, waste from stability and characterization, glass processing, ceramic processing, ceramic and glass processing, leaching of waste materials, properties of nuclear waste forms, and immobilization of special radioactive wastes. Separate abstracts were prepared for all the papers. (DLC)

  17. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 12. Science and Technology of Ceramics - Functional Ceramics. Sheela K Ramasesha. Series Article Volume 4 Issue 12 December 1999 pp 21-30. Fulltext. Click here to view fulltext PDF. Permanent link:

  18. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 8. Science and Technology of Ceramics - Traditional Ceramics. Sheela K Ramasesha. Series Article Volume 4 Issue 8 August 1999 pp 16-24. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. Influence of implant abutment material on the color of different ceramic crown systems.

    Science.gov (United States)

    Dede, Doğu Ömür; Armağanci, Arzu; Ceylan, Gözlem; Celik, Ersan; Cankaya, Soner; Yilmaz, Burak

    2016-11-01

    Ceramics are widely used for anterior restorations; however, clinical color reproduction still constitutes a challenge particularly when the ceramic crowns are used on titanium implant abutments. The purpose of this in vitro study was to investigate the effect of implant abutment material on the color of different ceramic material systems. Forty disks (11×1.5 mm, shade A2) were fabricated from medium-opacity (mo) and high-translucency (ht) lithium disilicate (IPS e.max) blocks, an aluminous ceramic (VITA In-Ceram Alumina), and a zirconia (Zirkonzahn) ceramic system. Disks were fabricated to represent 3 different implant abutments (zirconia, gold-palladium, and titanium) and dentin (composite resin, A2 shade) as background (11×2 mm). Disk-shaped composite resin specimens in A2 shade were fabricated to represent the cement layer. The color measurements of ceramic specimens were made on composite resin abutment materials using a spectrophotometer. CIELab color coordinates were recorded, and the color coordinates measured on composite resin background served as the control group. Color differences (ΔE 00 ) between the control and test groups were calculated. The data were analyzed with 2-way analysis of variance (ANOVA) and compared with the Tukey HSD test (α=.05). The ceramics system, abutment material, and their interaction were significant for ΔE 00 values (P2.25) were observed for lithium disilicate ceramics on titanium abutments (2.46-2.50). The ΔE 00 values of lithium disilicate ceramics for gold-palladium and titanium abutments were significantly higher than for other groups (P2.25) of an implant-supported lithium disilicate ceramic restoration may be clinically unacceptable if it is fabricated over a titanium abutment. Zirconia may be a more suitable abutment material for implant-supported ceramic restorations. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  20. Low thermal expansion glass ceramics

    CERN Document Server

    1995-01-01

    This book is one of a series reporting on international research and development activities conducted by the Schott group of companies With the series, Schott aims to provide an overview of its activities for scientists, engineers, and managers from all branches of industry worldwide where glasses and glass ceramics are of interest Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated This volume describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization Thus glass ceramics with thermal c...

  1. Ceramic membrane development in NGK

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Kiyoshi; Sakai, Hitoshi, E-mail: kinsakai@ngk.co.jp [Corporate R and D, NGK Insulators, Ltd., Nagoya 467-8530 (Japan)

    2011-05-15

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R and D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  2. Ceramic membrane development in NGK

    Science.gov (United States)

    Araki, Kiyoshi; Sakai, Hitoshi

    2011-05-01

    NGK Insulators, Ltd. was established in 1919 to manufacture the electric porcelain insulators for power transmission lines. Since then, our business has grown as one of the world-leading ceramics manufacturing companies and currently supply with the various environmentally-benign ceramic products to worldwide. In this paper, ceramic membrane development in NGK is described in detail. We have been selling ceramic microfiltration (MF) membranes and ultra-filtration (UF) membranes for many years to be used for solid/liquid separation in various fields such as pharmaceutical, chemical, food and semiconductor industries. In Corporate R&D, new ceramic membranes with sub-nanometer sized pores, which are fabricated on top of the membrane filters as support, are under development for gas and liquid/liquid separation processes.

  3. Method of forming a ceramic matrix composite and a ceramic matrix component

    Science.gov (United States)

    de Diego, Peter; Zhang, James

    2017-05-30

    A method of forming a ceramic matrix composite component includes providing a formed ceramic member having a cavity, filling at least a portion of the cavity with a ceramic foam. The ceramic foam is deposited on a barrier layer covering at least one internal passage of the cavity. The method includes processing the formed ceramic member and ceramic foam to obtain a ceramic matrix composite component. Also provided is a method of forming a ceramic matrix composite blade and a ceramic matrix composite component.

  4. Zirconia based ceramics

    International Nuclear Information System (INIS)

    Bressiani, J.C.; Bressiani, A.H.A.

    1989-05-01

    Within the new generation of ceramic materials, zirconia continues to attract ever increasing attention of scients, technologists and users by virtue of its singular combination of properties and being able to perform thermo-mechanical, electroeletronic, chemico-biological functions. Nevertheless, in order to obtain these properties, a through understanding of the phase transformation mechanisms and microstructural changes is necessary. This paper discusses the main parameters that require control during fabrication of these materials to obtain desired properties for a specific application. (author) [pt

  5. Directionally Solidified Multifunctional Ceramics

    Science.gov (United States)

    2006-12-01

    Vidrio , Vol. 44 [5] (2005) pp 347 - 352. 9. F. W. Dynys and A. Sayir, "Self Assemble Silicide Architectures by Directional Solidification," Journal...Sociedad Espanola de Ceramica y Vidrio , Vol. 43 [4] (2004) pp 753 - 758. 21. A. Sayir and F. S. Lowery, "Combustion-Resistance of Silicon-Based Ceramics...Espafiola de Cerdmica y Vidrio , Vol. 43 [3], 2004. ISSN-0366-3175-BSCVB9. 14 37. P. Berger, A. Sayir and M. H. Berger, "Nuclear Microprobe using Elastic

  6. Compatibility of stainless steels and lithiated ceramics with beryllium

    Science.gov (United States)

    Flament, T.; Fauvet, P.; Sannier, J.

    1988-07-01

    The introduction of beryllium as a neutron multiplier in ceramic blankets of thermonuclear fusion reactors may give rise to the following compatibility problems: (i) oxidation of Be by ceramics (lithium aluminate and silicates) or by water vapour; (ii) interaction between beryllium and austenitic and martensitic steels. The studies were done in contact tests under vacuum and in tests under wet sweeping helium. The contact tests under vacuum have revealed that the interaction of beryllium with ceramics seems to be low up to 700°C, the interaction of beryllium with steels is significant and is characterized by the formation of a diffusion layer and of a brittle Be-Fe-Ni compound. With type 316 L austenitic steel, this interaction appears quite large at 600°C whereas it is noticeable only at 700°C with martensitic steels. The experiments carried out with sweeping wet helium at 600°C have evidenced a slight oxidation of beryllium due to water vapour which can be enhanced in the front of uncompletely dehydrated ceramics.

  7. Process considerations for hot pressing ceramic nuclear waste forms

    International Nuclear Information System (INIS)

    Wilson, C.N.; Brite, D.W.

    1981-01-01

    Spray calcined simulated ceramic nuclear waste powders were hot pressed in graphite, nickel-lined graphite and ZrO 2 -lined Al 2 O 3 dies. Densification, initial off-gas, waste element retention and pellet-die interactions were evaluated. Indicated process considerations and limitations are discussed. 15 figures

  8. Formulation and synthesis by melting process of titanate enriched glass-ceramics and ceramics

    International Nuclear Information System (INIS)

    Advocat, T.; Fillet, C.; Lacombe, J.; Bonnetier, A.; McGlinn, P.

    1999-01-01

    The main objective of this work is to provide containment for the separated radionuclides in stable oxide phases with proven resistance to leaching and irradiation damage and in consequence to obtain a glass ceramic or a ceramic material using a vitrification process. Sphene glass ceramic, zirconolite glass ceramic and zirconolite enriched ceramic have been fabricated and characterized by XRD, SEM/EDX and DTA

  9. Nano-ceramics and its molding technologies

    International Nuclear Information System (INIS)

    Liu Jian; Xu Yunshu

    2007-01-01

    Nano-ceramics and its related knowledge were introduced. Fabrication of nano-ceramic powder, as well as the molding and sintering technologies of nano-ceramics were reviewed. Features of the present molding technologies were analyzed. The applications of nano-ceramics were prospected. (authors)

  10. Preparation of 147Pm ceramic source core

    International Nuclear Information System (INIS)

    Mielcarski, M.

    1989-01-01

    Preparation of ceramic pellets containing fixed promethium-147 is described. Incorporation rate of 147 Pm into the ceramic material was determined. The leachability and vaporization of promethium from the obtained ceramics was investigated. The ceramic pellets prepared by the described procedure, mounted in special holders, can be applied as point sources in beta backscatter thickness gauges. (author)

  11. Shockless spalling damage of alumina ceramic

    Science.gov (United States)

    Erzar, B.; Buzaud, E.

    2012-05-01

    Ceramic materials are commonly used to build multi-layer armour. However reliable test data is needed to identify correctly models and to be able to perform accurate numerical simulation of the dynamic response of armour systems. In this work, isentropic loading waves have been applied to alumina samples to induce spalling damage. The technique employed allows assessing carefully the strain-rate at failure and the dynamic strength. Moreover, specimens have been recovered and analysed using SEM. In a damaged but unbroken specimen, interactions between cracks has been highlighted illustrating the fragmentation process.

  12. Fibrous monolithic ceramics

    International Nuclear Information System (INIS)

    Kovar, D.; King, B.H.; Trice, R.W.; Halloran, J.W.

    1997-01-01

    Fibrous monolithic ceramics are an example of a laminate in which a controlled, three-dimensional structure has been introduced on a submillimeter scale. This unique structure allows this all-ceramic material to fail in a nonbrittle manner. Materials have been fabricated and tested with a variety of architectures. The influence on mechanical properties at room temperature and at high temperature of the structure of the constituent phases and the architecture in which they are arranged are discussed. The elastic properties of these materials can be effectively predicted using existing models. These models also can be extended to predict the strength of fibrous monoliths with an arbitrary orientation and architecture. However, the mechanisms that govern the energy absorption capacity of fibrous monoliths are unique, and experimental results do not follow existing models. Energy dissipation occurs through two dominant mechanisms--delamination of the weak interphases and then frictional sliding after cracking occurs. The properties of the constituent phases that maximize energy absorption are discussed. In this article, the authors examine the structure of Si 3 N 4 -BN fibrous monoliths from the submillimeter scale of the crack-deflecting cell-cell boundary features to the nanometer scale of the BN cell boundaries

  13. Ceramic fiber reinforced filter

    Science.gov (United States)

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  14. On kinetics of paramagnetic radiation defects accumulation in beryllium ceramics

    International Nuclear Information System (INIS)

    Polyakov, A.I.; Ryabikin, Yu.A.; Zashkvara, O.V.; Bitenbaev, M.I.; Petykhov, Yu.V.

    1999-01-01

    Results of paramagnetic radiation defects concentration dependence study in beryllium ceramics from gamma-irradiation dose ( 60 Co) within interval 0-100 Mrem are cited. Obtained dose dependence has form of accumulation curve with saturation typical of for majority of solids (crystals, different polymers, organic substances and others) , in which under irradiation occur not only formation of paramagnetic radiation defects, but its destruction due to recombination and interaction with radiation fields. Analysis of accumulation curve by the method of distant asymptotics allows to determine that observed in gamma-irradiated beryllium ceramics double line of electron spin resonance is forming of two types of paramagnetic radiation defects. It was defined, that sum paramagnetic characteristics of beryllium ceramics within 1-100 Mrad gamma- irradiation dose field change insignificantly and define from first type of paramagnetic radiation defects

  15. Ceramic drug-delivery devices.

    Science.gov (United States)

    Lasserre, A; Bajpai, P K

    1998-01-01

    A variety of ceramics and delivery systems have been used to deliver chemicals, biologicals, and drugs at various rates for desired periods of time from different sites of implantation. In vitro and in vivo studies have shown that ceramics can successfully be used as drug-delivery devices. Matrices, inserts, reservoirs, cements, and particles have been used to deliver a large variety of therapeutic agents such as antibiotics, anticancer drugs, anticoagulants, analgesics, growth factors, hormones, steroids, and vaccines. In this article, the advantages and disadvantages of conventional drug-delivery systems and the different approaches used to deliver chemical and biological agents by means of ceramic systems will be reviewed.

  16. High flow ceramic pot filters

    OpenAIRE

    van Halem, D.; van der Laan, H.; Soppe, A. I.A.; Heijman, S.G.J.

    2017-01-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6–19 L h−1), but initial LRVs for E. coli o...

  17. Hardness of ion implanted ceramics

    International Nuclear Information System (INIS)

    Oliver, W.C.; McHargue, C.J.; Farlow, G.C.; White, C.W.

    1985-01-01

    It has been established that the wear behavior of ceramic materials can be modified through ion implantation. Studies have been done to characterize the effect of implantation on the structure and composition of ceramic surfaces. To understand how these changes affect the wear properties of the ceramic, other mechanical properties must be measured. To accomplish this, a commercially available ultra low load hardness tester has been used to characterize Al 2 O 3 with different implanted species and doses. The hardness of the base material is compared with the highly damaged crystalline state as well as the amorphous material

  18. Porous ceramics out of oxides

    International Nuclear Information System (INIS)

    Bakunov, V.S.; Balkevich, V.L.; Vlasov, A.S.; Guzman, I.Ya.; Lukin, E.S.; Poluboyarinov, D.N.; Poliskij, R.Ya.

    1977-01-01

    A review is made of manufacturing procedures and properties of oxide ceramics intended for high-temperature thermal insulation and thermal protection applications. Presented are structural characteristics of porous oxide refractories and their properties. Strength and thermal conductivity was shown to depend upon porosity. Described is a procedure for manufacturing porous ceramic materials from aluminium oxide, zirconium dioxide, magnesium oxide, beryllium oxide. The thermal resistance of porous ceramics from BeO is considerably greater than that of other high-refractoriness oxides. Listed are areas of application for porous materials based on oxides

  19. Magnetic Glass Ceramics by Sintering of Borosilicate Glass and Inorganic Waste

    Directory of Open Access Journals (Sweden)

    Inès M. M. M. Ponsot

    2014-07-01

    Full Text Available Ceramics and glass ceramics based on industrial waste have been widely recognized as competitive products for building applications; however, there is a great potential for such materials with novel functionalities. In this paper, we discuss the development of magnetic sintered glass ceramics based on two iron-rich slags, coming from non-ferrous metallurgy and recycled borosilicate glass. The substantial viscous flow of the glass led to dense products for rapid treatments at relatively low temperatures (900–1000 °C, whereas glass/slag interactions resulted in the formation of magnetite crystals, providing ferrimagnetism. Such behavior could be exploited for applying the obtained glass ceramics as induction heating plates, according to preliminary tests (showing the rapid heating of selected samples, even above 200 °C. The chemical durability and safety of the obtained glass ceramics were assessed by both leaching tests and cytotoxicity tests.

  20. Supersonic laser spray of aluminium alloy on a ceramic substrate

    International Nuclear Information System (INIS)

    Riveiro, A.; Lusquinos, F.; Comesana, R.; Quintero, F.; Pou, J.

    2007-01-01

    Applying a ceramic coating onto a metallic substrate to improve its wear resistance or corrosion resistance has attracted the interest of many researchers during decades. However, only few works explore the possibility to apply a metallic layer onto a ceramic material. This work presents a novel technique to coat ceramic materials with metals: the supersonic laser spraying. In this technique a laser beam is focused on the surface of the precursor metal in such a way that the metal is transformed to the liquid state in the beam-metal interaction zone. A supersonic jet expels the molten material and propels it to the surface of the ceramic substrate. In this study, we present the preliminary results obtained using the supersonic laser spray to coat a commercial cordierite ceramic plate with an Al-Cu alloy using a 3.5 kW CO 2 laser and a supersonic jet of Argon. Coatings were characterized by scanning electron microscopy (SEM) and interferometric profilometry

  1. Effects of process variables on the properties of YBa2Cu3O(7-x) ceramics formed by investment casting

    Science.gov (United States)

    Hooker, M. W.; Taylor, T. D.; Leigh, H. D.; Wise, S. A.; Buckley, J. D.; Vasquez, P.; Buck, G. M.; Hicks, L. P.

    1993-01-01

    An investment casting process has been developed to produce net-shape, superconducting ceramics. In this work, a factorial experiment was performed to determine the critical process parameters for producing cast YBa2Cu3O7 ceramics with optimum properties. An analysis of variance procedure indicated that the key variables in casting superconductive ceramics are the particle size distribution and sintering temperature. Additionally, the interactions between the sintering temperature and the other process parameters (e.g., particle size distribution and the use of silver dopants) were also found to influence the density, porosity, and critical current density of the fired ceramics.

  2. Agglomeration of ceramic powders

    Science.gov (United States)

    Cawley, James D.; Larosa, Judith; Dirkse, Fredrick

    1989-01-01

    A research program directed at a critical comparison of numerical models for power agglomeration with experimental observations is currently underway. Central to this program is the quantitative characterization of the distribution of mass within an agglomerate as a function of time. Current experiments are designed to restrict agglomeration to a surface, which is oriented perpendicular to the force of gravity. These experiments are discussed with reference to: their significance to ceramic processing; artifacts which may be avoided in microgravity experiments; and the comparison of information available in real space (from optical microscopy) to that in reciprocal space (from light scattering). The principle machine requirement appears to be a need to obtain information at small scattering angles.

  3. Creep in electronic ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Routbort, J. L.; Goretta, K. C.; Arellano-Lopez, A. R.

    2000-04-27

    High-temperature creep measurements combined with microstructural investigations can be used to elucidate deformation mechanisms that can be related to the diffusion kinetics and defect chemistry of the minority species. This paper will review the theoretical basis for this correlation and illustrate it with examples from some important electronic ceramics having a perovskite structure. Recent results on BaTiO{sub 3}, (La{sub 1{minus}x}Sr){sub 1{minus}y}MnO{sub 3+{delta}}, YBa{sub 2}Cu{sub 3}O{sub x}, Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x}, (Bi,Pb){sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub x} and Sr(Fe,Co){sub 1.5}O{sub x} will be presented.

  4. Ceramics for fusion devices

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.

    1984-01-01

    Ceramics are required for a number of applications in fusion devices, among the most critical of which are magnetic coil insulators, windows for RF heating systems, and structural uses. Radiation effects dominate consideration of candidate materials, although good pre-irradiation properties are a requisite. Materials and components can be optimized by careful control of chemical and microstructural content, and application of brittle material design and testing techniques. Future directions for research and development should include further extension of the data base in the areas of electrical, structural, and thermal properties; establishment of a fission neutron/fusion neutron correlation including transmutation gas effects; and development of new materials tailored to meet the specific needs of fusion reactors

  5. Moessbauer studies of Inca ceramics

    International Nuclear Information System (INIS)

    Wagner, U.; Wagner, F.E.; Marticorena, B.; Salazar, R.; Schwabe, R.; Riederer, J.

    1986-01-01

    To obtain information on the firing of Inca ceramics, 7 samples from different locations were studied by Moessbauer spectroscopy including a detailed laboratory refiring procedure. The glaze typical for the surface of this ware was studied by Moessbauer scattering. (Auth.)

  6. Non destructive evaluation of ceramics

    International Nuclear Information System (INIS)

    Green, R.E. Jr

    1992-01-01

    While monolithic and composite ceramics have been successfully manufactured, inconsistencies in processing and the unpredictable nature of their failure have limited their use as engineering materials. The optimization of the processing and properties of ceramics and the structures, devices and systems made from them demand the innovative application of modern nondestructive materials characterization techniques to monitor and control as many stages of the production process as possible. This paper will describe the state-of-the-art of nondestructive evaluation techniques for characterization of monolithic ceramics and ceramic composites. Among the techniques to be discussed are laser ultrasonics, acoustic microscopy, thermography, microfocus and x-ray tomography, and micro-photoelasticity. Application of these and other nondestructive evaluation techniques for more effective and efficient real-time process control will result in improved product quality and reliability. 27 refs

  7. Low Thermal Expansion Glass Ceramics

    CERN Document Server

    Bach, Hans

    2005-01-01

    This book appears in the authoritative series reporting the international research and development activities conducted by the Schott group of companies. This series provides an overview of Schott's activities for scientists, engineers, and managers from all branches of industry worldwide in which glasses and glass ceramics are of interest. Each volume begins with a chapter providing a general idea of the current problems, results, and trends relating to the subjects treated. This new extended edition describes the fundamental principles, the manufacturing process, and applications of low thermal expansion glass ceramics. The composition, structure, and stability of polycrystalline materials having a low thermal expansion are described, and it is shown how low thermal expansion glass ceramics can be manufactured from appropriately chosen glass compositions. Examples illustrate the formation of this type of glass ceramic by utilizing normal production processes together with controlled crystallization. Thus g...

  8. Inorganic glass ceramic slip rings

    Science.gov (United States)

    Glossbrenner, E. W.; Cole, S. R.

    1972-01-01

    Prototypes of slip rings have been fabricated from ceramic glass, a material which is highly resistant to deterioration due to high temperature. Slip ring assemblies were not structurally damaged by mechanical tests and performed statisfactorily for 200 hours.

  9. Metal-ceramic joint assembly

    Science.gov (United States)

    Li, Jian

    2002-01-01

    A metal-ceramic joint assembly in which a brazing alloy is situated between metallic and ceramic members. The metallic member is either an aluminum-containing stainless steel, a high chromium-content ferritic stainless steel or an iron nickel alloy with a corrosion protection coating. The brazing alloy, in turn, is either an Au-based or Ni-based alloy with a brazing temperature in the range of 9500 to 1200.degree. C.

  10. Multiphase-Multifunctional Ceramic Coatings

    Science.gov (United States)

    2013-06-30

    systems for high temperatura applications” “ Estudios de Ferroelasticidad en Sistemas Cerámicos Multifásicos para Aplicaciones en Alta Temperatura ...Ceramic Coatings Performing Organization names: Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional – Unidad Queretaro...materials, Cinvestav. Thesis: “Ferroelasticity studies in multiphase ceramic systems for high temperatura applications”. Her work mainly focused in the

  11. Nano-Ceramic Coated Plastics

    Science.gov (United States)

    Cho, Junghyun

    2013-01-01

    Plastic products, due to their durability, safety, and low manufacturing cost, are now rapidly replacing cookware items traditionally made of glass and ceramics. Despite this trend, some still prefer relatively expensive and more fragile ceramic/glassware because plastics can deteriorate over time after exposure to foods, which can generate odors, bad appearance, and/or color change. Nano-ceramic coatings can eliminate these drawbacks while still retaining the advantages of the plastic, since the coating only alters the surface of the plastic. The surface coating adds functionality to the plastics such as self-cleaning and disinfectant capabilities that result from a photocatalytic effect of certain ceramic systems. These ceramic coatings can also provide non-stick surfaces and higher temperature capabilities for the base plastics without resorting to ceramic or glass materials. Titanium dioxide (TiO2) and zinc oxide (ZnO) are the candidates for a nano-ceramic coating to deposit on the plastics or plastic films used in cookware and kitchenware. Both are wide-bandgap semiconductors (3.0 to 3.2 eV for TiO2 and 3.2 to 3.3 eV for ZnO), so they exhibit a photocatalytic property under ultraviolet (UV) light. This will lead to decomposition of organic compounds. Decomposed products can be easily washed off by water, so the use of detergents will be minimal. High-crystalline film with large surface area for the reaction is essential to guarantee good photocatalytic performance of these oxides. Low-temperature processing (nano-ceramic coatings (TiO2, ZnO) on plastic materials (silicone, Teflon, PET, etc.) that can possess both photocatalytic oxide properties and flexible plastic properties. Processing cost is low and it does not require any expensive equipment investment. Processing can be scalable to current manufacturing infrastructure.

  12. Method for preparing ceramic composite

    Science.gov (United States)

    Alexander, K.B.; Tiegs, T.N.; Becher, P.F.; Waters, S.B.

    1996-01-09

    A process is disclosed for preparing ceramic composite comprising blending TiC particulates, Al{sub 2}O{sub 3} particulates and nickel aluminide and consolidating the mixture at a temperature and pressure sufficient to produce a densified ceramic composite having fracture toughness equal to or greater than 7 MPa m{sup 1/2}, a hardness equal to or greater than 18 GPa. 5 figs.

  13. Fracture-dissociation of ceramic liner.

    Science.gov (United States)

    Hwang, Sung Kwan; Oh, Jin-Rok; Her, Man Seung; Shim, Young Jun; Cho, Tae Yeun; Kwon, Sung Min

    2008-08-01

    The use of BIOLOX delta ceramic (CeramTec AG, Plochingen, Germany) has been increasing. This ceramic prevents cracking by restraining the phase transformation due to the insertion of nano-sized, yttria-stabilized tetragonal zirconia into the alumina matrix. This restrains the progress of cracking through the formation of platelet-like crystal or whiskers due to the addition of an oxide additive. We observed a case of BIOLOX delta ceramic liner (CeramTec AG) rim fracture 4 months postoperatively. Radiographs showed that the ceramic liner was subluxated from the acetabular cup. Scratches on the acetabular cup and femoral neck were seen, and the fracture was visible on the rim of the liner. Under electron microscope, metal particle coatings from the ceramic liner were identified. The ceramic liner, fracture fragments, and adjacent tissues were removed and replaced with a ceramic liner and femoral head of the same size and design. We believe the mechanism of the fracture-dissociation of the ceramic liner in this case is similar to a case of separation of the ceramic liner from the polyethylene shell in a sandwich-type ceramic-ceramic joint. To prevent ceramic liner fracture-dissociation, the diameter of the femoral neck needs to be decreased in a new design, while the diameter of the femoral head needs to be increased to ensure an increase in range of motion.

  14. Ceramics as nuclear reactor fuels

    International Nuclear Information System (INIS)

    Reeve, K.D.

    1975-01-01

    Ceramics are widely accepted as nuclear reactor fuel materials, for both metal clad ceramic and all-ceramic fuel designs. Metal clad UO 2 is used commercially in large tonnages in five different power reactor designs. UO 2 pellets are made by familiar ceramic techniques but in a reactor they undergo complex thermal and chemical changes which must be thoroughly understood. Metal clad uranium-plutonium dioxide is used in present day fast breeder reactors, but may eventually be replaced by uranium-plutonium carbide or nitride. All-ceramic fuels, which are necessary for reactors operating above about 750 0 C, must incorporate one or more fission product retentive ceramic coatings. BeO-coated BeO matrix dispersion fuels and silicate glaze coated UO 2 -SiO 2 have been studied for specialised applications, but the only commercial high temperature fuel is based on graphite in which small fuel particles, each coated with vapour deposited carbon and silicon carbide, are dispersed. Ceramists have much to contribute to many aspects of fuel science and technology. (author)

  15. Method for Waterproofing Ceramic Materials

    Science.gov (United States)

    Cagliostro, Domenick E. (Inventor); Hsu, Ming-Ta S. (Inventor)

    1998-01-01

    Hygroscopic ceramic materials which are difficult to waterproof with a silane, substituted silane or silazane waterproofing agent, such as an alumina containing fibrous, flexible and porous, fibrous ceramic insulation used on a reentry space vehicle, are rendered easy to waterproof if the interior porous surface of the ceramic is first coated with a thin coating of silica. The silica coating is achieved by coating the interior surface of the ceramic with a silica precursor converting the precursor to silica either in-situ or by oxidative pyrolysis and then applying the waterproofing agent to the silica coated ceramic. The silica precursor comprises almost any suitable silicon containing material such as a silane, silicone, siloxane, silazane and the like applied by solution, vapor deposition and the like. If the waterproofing is removed by e.g., burning, the silica remains and the ceramic is easily rewaterproofed. An alumina containing TABI insulation which absorbs more that five times its weight of water, absorbs less than 10 wt. % water after being waterproofed according to the method of the invention.

  16. ADM guidance-Ceramics: all-ceramic multilayer interfaces in dentistry.

    Science.gov (United States)

    Lohbauer, Ulrich; Scherrer, Susanne S; Della Bona, Alvaro; Tholey, Michael; van Noort, Richard; Vichi, Alessandro; Kelly, J Robert; Cesar, Paulo F

    2017-06-01

    This guidance document describes the specific issues involved in dental multilayer ceramic systems. The material interactions with regard to specific thermal and mechanical properties are reviewed and the characteristics of dental tooth-shaped processing parameters (sintering, geometry, thickness ratio, etc.) are discussed. Several techniques for the measurement of bond quality and residual stresses are presented with a detailed discussion of advantages and disadvantages. In essence no single technique is able to describe adequately the all-ceramic interface. Invasive or semi-invasive methods have been shown to distort the information regarding the residual stress state while non-invasive methods are limited due to resolution, field of focus or working depth. This guidance document has endeavored to provide a scientific basis for future research aimed at characterizing the ceramic interface of dental restorations. Along with the methodological discussion it is seeking to provide an introduction and guidance to relatively inexperienced researchers. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  17. Design and In-Situ Processing of Metal-Ceramic and Ceramic-Ceramic Microstructures

    National Research Council Canada - National Science Library

    Sass, Stephen

    1997-01-01

    .... Metal-ceramic microstructures have been synthesized in situ by a variety of novel processing techniques, including the partial reduction of oxide compounds and displacement reactions and sol-gel...

  18. FOREWORD: Focus on Advanced Ceramics Focus on Advanced Ceramics

    Science.gov (United States)

    Ohashi, Naoki

    2011-06-01

    Much research has been devoted recently to developing technologies for renewable energy and improving the efficiency of the processes and devices used in industry and everyday life. Efficient solutions have been found using novel materials such as platinum and palladium-based catalysts for car exhaust systems, samarium-cobalt and neodymium-iron-boron permanent magnets for electrical motors, and so on. However, their realization has resulted in an increasing demand for rare elements and in their deficit, the development of new materials based on more abundant elements and new functionalities of traditional materials. Moreover, increasing environmental and health concerns demand substitution of toxic or hazardous substances with nature-friendly alternatives. In this context, this focus issue on advanced ceramics aims to review current trends in ceramics science and technology. It is related to the International Conference on Science and Technology of Advanced Ceramics (STAC) held annually to discuss the emerging issues in the field of ceramics. An important direction of ceramic science is the collaboration between experimental and theoretical sciences. Recent developments in density functional theory and computer technology have enabled the prediction of physical and chemical properties of ceramics, thereby assisting the design of new materials. Therefore, this focus issue includes articles devoted to theory and advanced characterization techniques. As mentioned above, the potential shortage of rare elements is becoming critical to the industry and has resulted in a Japanese government initiative called the 'Ubiquitous Element Strategy'. This focus issue also includes articles related to this strategy and to the associated topics of energy conversion, such as phosphors for high-efficiency lighting and photocatalysts for solar-energy harvesting. We hope that this focus issue will provide a timely overview of current trends and problems in ceramics science and

  19. All-ceramic crowns: bonding or cementing?

    Science.gov (United States)

    Pospiech, Peter

    2002-12-01

    Despite the wide variety of all-ceramic systems available today, the majority of dental practitioners hesitate to recommend and insert all-ceramic crowns. This article regards the nature of the ceramic materials, the principles of bonding and adhesion, and the clinical problems of the acid-etch technique for crowns. Advantages and disadvantages are discussed, and the influences of different factors on the strength of all-ceramic crowns are presented. Finally, the conclusion is drawn that conventional cementing of all-ceramic crowns is possible when the specific properties of the ceramics are taken into consideration.

  20. Exoelectron emission from magnesium borate glass ceramics

    International Nuclear Information System (INIS)

    Kawamoto, Takamichi; Yanagisawa, Hideo; Nakamichi, Hiroshi; Kikuchi, Riichi; Kawanishi, Masaharu.

    1986-01-01

    Thermally stimulated exoelectron emission (TSEE) of a magnesium borate glass ceramics was investigated for its application to dosemetric use. It has been found that the TSEE glow patterns of the magnesium borate glass ceramics as well as a Li 2 B 4 O 7 glass ceramics depend on the kind of the radiation used and that the heat resistance of the magnesium borate glass ceramics is higher than that of the Li 2 B 4 O 7 glass ceramics. Therefore, the TSEE glow patterns of the magnesium borate glass ceramics indicate a possibility to be used as the dose measurement for each kind of radiation in the mixed radiation field. (author)

  1. Producing ceramic laminate composites by EPD

    International Nuclear Information System (INIS)

    Nicholson, P.S.; Sarkar, P.; Datta, S.

    1996-01-01

    The search for tough structural ceramics to operate at high temperatures in hostile environments has led to the development of ceramic composites. This class of material includes laminar ceramic-ceramic composites, continuous-fiber-reinforced ceramic composites and functionally graded materials. The present authors developed electrophoretic deposition (EPD) to synthesize lamellar, fiber-reinforced and functionally graded composites. This paper briefly describes the synthesis and characterization of these EPD composites and introduces a novel class of lamellar composites with nonplanar layers. The synthesis of the latter demonstrates the facility of the EPD process for the synthesis of ceramic composites. The process is totally controllable via suspension concentration, deposition current, voltage and time

  2. Growth kinetics of dislocation loops in irradiated ceramic materials

    International Nuclear Information System (INIS)

    Ryazanov, A.I.; Kinoshita, C.

    2002-01-01

    Ceramic materials are expected to be applied in the future fusion reactor as radio frequency (RF) windows, toroidal insulating breaks and diagnostic probes. The radiation resistance of ceramic materials, degradation of the electrical properties and radiation induced conductivity of these materials under neutron irradiation are determined by the kinetics of the accumulation of point defects in the matrix and point defect cluster formation (dislocation loops, voids, etc.). Under irradiation, due to the ionization process, excitation of electronic subsystem and covalent type of interaction between atoms the point defects in ceramic materials are characterized by the charge state (e.g. an F + center, an oxygen vacancy with a single trapped electron) and the effective charge. For the investigation of radiation resistance of ceramic materials for future fusion applications it is very important to understand the physical mechanisms of formation and growth of dislocation loops and voids under irradiation taking into account in this system the effective charge of point defects. In the present paper the physical mechanisms of dislocation loop growth in ceramic material are investigated. For this aim a theoretical model is suggested for the description of the kinetics of point defect accumulation in the matrix taking into account the charge state of the point defects and the effect of an electric field on diffusion migration process of charged point defects. A self-consistent system of kinetic equations describing the generation of electrical fields near dislocation loops and diffusion migration of charged point defects in elastic and electrical fields is formulated. The solution of the kinetic equations allows to find the growth rate of dislocation loops in ceramic materials under irradiation taking into account the charge state of the point defects and the effect of electric and elastic stress fields near dislocation loop on the diffusion processes

  3. Glass Ceramic Formulation Data Package

    International Nuclear Information System (INIS)

    Crum, Jarrod V.; Rodriguez, Carmen P.; McCloy, John S.; Vienna, John D.; Chung, Chul-Woo

    2012-01-01

    A glass ceramic waste form is being developed for treatment of secondary waste streams generated by aqueous reprocessing of commercial used nuclear fuel (Crum et al. 2012b). The waste stream contains a mixture of transition metals, alkali, alkaline earths, and lanthanides, several of which exceed the solubility limits of a single phase borosilicate glass (Crum et al. 2009; Caurant et al. 2007). A multi-phase glass ceramic waste form allows incorporation of insoluble components of the waste by designed crystallization into durable heat tolerant phases. The glass ceramic formulation and processing targets the formation of the following three stable crystalline phases: (1) powellite (XMoO4) where X can be (Ca, Sr, Ba, and/or Ln), (2) oxyapatite Yx,Z(10-x)Si6O26 where Y is alkaline earth, Z is Ln, and (3) lanthanide borosilicate (Ln5BSi2O13). These three phases incorporate the waste components that are above the solubility limit of a single-phase borosilicate glass. The glass ceramic is designed to be a single phase melt, just like a borosilicate glass, and then crystallize upon slow cooling to form the targeted phases. The slow cooling schedule is based on the centerline cooling profile of a 2 foot diameter canister such as the Hanford High-Level Waste canister. Up to this point, crucible testing has been used for glass ceramic development, with cold crucible induction melter (CCIM) targeted as the ultimate processing technology for the waste form. Idaho National Laboratory (INL) will conduct a scaled CCIM test in FY2012 with a glass ceramic to demonstrate the processing behavior. This Data Package documents the laboratory studies of the glass ceramic composition to support the CCIM test. Pacific Northwest National Laboratory (PNNL) measured melt viscosity, electrical conductivity, and crystallization behavior upon cooling to identify a processing window (temperature range) for melter operation and cooling profiles necessary to crystallize the targeted phases in the

  4. Identification of a Critical Time with Acoustic Emission Monitoring during Static Fatigue Tests on Ceramic Matrix Composites: Towards Lifetime Prediction

    Directory of Open Access Journals (Sweden)

    Nathalie Godin

    2016-02-01

    Full Text Available Non-oxide fiber-reinforced ceramic-matrix composites are promising candidates for some aeronautic applications that require good thermomechanical behavior over long periods of time. This study focuses on the behavior of a SiCf/[Si-B-C] composite with a self-healing matrix at intermediate temperature under air. Static fatigue experiments were performed below 600 °C and a lifetime diagram is presented. Damage is monitored both by strain measurement and acoustic emission during the static fatigue experiments. Two methods of real-time analysis of associated energy release have been developed. They allow for the identification of a characteristic time that was found to be close to 55% of the measured rupture time. This critical time reflects a critical local energy release assessed by the applicability of the Benioff law. This critical aspect is linked to a damage phase where slow crack growth in fibers is prevailing leading to ultimate fracture of the composite.

  5. Creep Behavior in Interlaminar Shear of a SiC/SiC Ceramic Composite with a Self-healing Matrix

    Science.gov (United States)

    Ruggles-Wrenn, M. B.; Pope, M. T.

    2014-02-01

    Creep behavior in interlaminar shear of a non-oxide ceramic composite with a multilayered matrix was investigated at 1,200 °C in laboratory air and in steam environment. The composite was produced via chemical vapor infiltration (CVI). The composite had an oxidation inhibited matrix, which consisted of alternating layers of silicon carbide and boron carbide and was reinforced with laminated Hi-Nicalon™ fibers woven in a five-harness-satin weave. Fiber preforms had pyrolytic carbon fiber coating with boron carbide overlay applied. The interlaminar shear properties were measured. The creep behavior was examined for interlaminar shear stresses in the 16-22 MPa range. Primary and secondary creep regimes were observed in all tests conducted in air and in steam. In air and in steam, creep run-out defined as 100 h at creep stress was achieved at 16 MPa. Larger creep strains were accumulated in steam. However, creep strain rates and creep lifetimes were only moderately affected by the presence of steam. The retained properties of all specimens that achieved run-out were characterized. Composite microstructure, as well as damage and failure mechanisms were investigated.

  6. Disc piezoelectric ceramic transformers.

    Science.gov (United States)

    Erhart, Jirií; Půlpán, Petr; Doleček, Roman; Psota, Pavel; Lédl, Vít

    2013-08-01

    In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, and input and output impedances were measured for low-power signals. Transformer efficiency and transformation ratio were measured as a function of frequency and impedance load in the secondary circuit. Optimum impedance for the maximum efficiency has been found. Maximum efficiency and no-load transformation ratio can reach almost 100% and 52 for the fundamental resonance of ring-dot transformers and 98% and 67 for the second resonance of 2-segment wedge transformers. Maximum efficiency was reached at optimum impedance, which is in the range from 500 Ω to 10 kΩ, depending on the electrode pattern and size. Fundamental vibration mode and its overtones were further studied using frequency-modulated digital holographic interferometry and by the finite element method. Complementary information has been obtained by the infrared camera visualization of surface temperature profiles at higher driving power.

  7. Bar piezoelectric ceramic transformers.

    Science.gov (United States)

    Erhart, Jiří; Pulpan, Půlpán; Rusin, Luboš

    2013-07-01

    Bar-shaped piezoelectric ceramic transformers (PTs) working in the longitudinal vibration mode (k31 mode) were studied. Two types of the transformer were designed--one with the electrode divided into two segments of different length, and one with the electrodes divided into three symmetrical segments. Parameters of studied transformers such as efficiency, transformation ratio, and input and output impedances were measured. An analytical model was developed for PT parameter calculation for both two- and three-segment PTs. Neither type of bar PT exhibited very high efficiency (maximum 72% for three-segment PT design) at a relatively high transformation ratio (it is 4 for two-segment PT and 2 for three-segment PT at the fundamental resonance mode). The optimum resistive loads were 20 and 10 kΩ for two- and three-segment PT designs for the fundamental resonance, respectively, and about one order of magnitude smaller for the higher overtone (i.e., 2 kΩ and 500 Ω, respectively). The no-load transformation ratio was less than 27 (maximum for two-segment electrode PT design). The optimum input electrode aspect ratios (0.48 for three-segment PT and 0.63 for two-segment PT) were calculated numerically under no-load conditions.

  8. Reliability of ceramics for heat engine applications

    Science.gov (United States)

    1980-01-01

    The advantages and disadvantages associated with the use of monolithic ceramics in heat engines are discussed. The principle gaps in the state of understanding of ceramic material, failure origins, nondestructive tests as well as life prediction are included.

  9. III Advanced Ceramics and Applications Conference

    CERN Document Server

    Gadow, Rainer; Mitic, Vojislav; Obradovic, Nina

    2016-01-01

    This is the Proceedings of III Advanced Ceramics and Applications conference, held in Belgrade, Serbia in 2014. It contains 25 papers on various subjects regarding preparation, characterization and application of advanced ceramic materials.

  10. Panel report on high temperature ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Nolet, T C [ed.

    1979-01-01

    Fundamental research is reported concerning high temperature ceramics for application in turbines, engines, batteries, gasifiers, MHD, fuel cells, heat exchangers, and hot wall combustors. Ceramics microstructure and behavior are included. (FS)

  11. Ceramics: past, present, and future.

    Science.gov (United States)

    Lemons, J E

    1996-07-01

    The selection and application of synthetic materials for surgical implants has been directly dependent upon the biocompatibility profiles of specific prosthetic devices. The early rationale for ceramic biomaterials was based upon the chemical and biochemical inertness (minimal bioreactivity) of elemental compounds constituted into structural forms (materials). Subsequently, mildly reactive (bioactive), and partially and fully degradable ceramics were identified for clinical uses. Structural forms have included bulk solids or particulates with and without porosities for tissue ingrowth, and more recently, coatings onto other types of biomaterial substrates. The physical shapes selected were application dependent, with advantages and disadvantages determined by: (1) the basic material and design properties of the device construct; and (2) the patient-based functional considerations. Most of the ceramics (bioceramics) selected in the 1960s and 1970s have continued over the long-term, and the science and technology for thick and thin coatings have evolved significantly over the past decade. Applications of ceramic biomaterials range from bulk (100%) ceramic structures as joint and bone replacements to fully or partially biodegradable substrates for the controlled delivery of pharmaceutical drugs, growth factors, and morphogenetically inductive substances. Because of the relatively unique properties of bioceramics, expanded uses as structural composites with other biomaterials and macromolecular biologically-derived substances are anticipated in the future.

  12. Shock compression profiles in ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Grady, D.E.; Moody, R.L.

    1996-03-01

    An investigation of the shock compression properties of high-strength ceramics has been performed using controlled planar impact techniques. In a typical experimental configuration, a ceramic target disc is held stationary, and it is struck by plates of either a similar ceramic or by plates of a well-characterized metal. All tests were performed using either a single-stage propellant gun or a two-stage light-gas gun. Particle velocity histories were measured with laser velocity interferometry (VISAR) at the interface between the back of the target ceramic and a calibrated VISAR window material. Peak impact stresses achieved in these experiments range from about 3 to 70 GPa. Ceramics tested under shock impact loading include: Al{sub 2}O{sub 3}, AlN, B{sub 4}C, SiC, Si{sub 3}N{sub 4}, TiB{sub 2}, WC and ZrO{sub 2}. This report compiles the VISAR wave profiles and experimental impact parameters within a database-useful for response model development, computational model validation studies, and independent assessment of the physics of dynamic deformation on high-strength, brittle solids.

  13. Transparent ceramic lamp envelope materials

    Energy Technology Data Exchange (ETDEWEB)

    Wei, G C [OSRAM SYLVANIA, 71 Cherry Hill Drive, Beverly, MA 01915 (United States)

    2005-09-07

    Transparent ceramic materials with optical qualities comparable to single crystals of similar compositions have been developed in recent years, as a result of the improved understanding of powder-processing-fabrication- sintering-property inter-relationships. These high-temperature materials with a range of thermal and mechanical properties are candidate envelopes for focused-beam, short-arc lamps containing various fills operating at temperatures higher than quartz. This paper reviews the composition, structure and properties of transparent ceramic lamp envelope materials including sapphire, small-grained polycrystalline alumina, aluminium oxynitride, yttrium aluminate garnet, magnesium aluminate spinel and yttria-lanthana. A satisfactory thermal shock resistance is required for the ceramic tube to withstand the rapid heating and cooling cycles encountered in lamps. Thermophysical properties, along with the geometry, size and thickness of a transparent ceramic tube, are important parameters in the assessment of its resistance to fracture arising from thermal stresses in lamps during service. The corrosive nature of lamp-fill liquid and vapour at high temperatures requires that all lamp components be carefully chosen to meet the target life. The wide range of new transparent ceramics represents flexibility in pushing the limit of envelope materials for improved beamer lamps.

  14. High flow ceramic pot filters.

    Science.gov (United States)

    van Halem, D; van der Laan, H; Soppe, A I A; Heijman, S G J

    2017-11-01

    Ceramic pot filters are considered safe, robust and appropriate technologies, but there is a general consensus that water revenues are limited due to clogging of the ceramic element. The objective of this study was to investigate the potential of high flow ceramic pot filters to produce more water without sacrificing their microbial removal efficacy. High flow pot filters, produced by increasing the rice husk content, had a higher initial flow rate (6-19 L h -1 ), but initial LRVs for E. coli of high flow filters was slightly lower than for regular ceramic pot filters. This disadvantage was, however, only temporarily as the clogging in high flow filters had a positive effect on the LRV for E. coli (from below 1 to 2-3 after clogging). Therefore, it can be carefully concluded that regular ceramic pot filters perform better initially, but after clogging, the high flow filters have a higher flow rate as well as a higher LRV for E. coli. To improve the initial performance of new high flow filters, it is recommended to further utilize residence time of the water in the receptacle, since additional E. coli inactivation was observed during overnight storage. Although a relationship was observed between flow rate and LRV of MS2 bacteriophages, both regular and high flow filters were unable to reach over 2 LRV. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Emerging Ceramic-based Materials for Dentistry

    Science.gov (United States)

    Denry, I.; Kelly, J.R.

    2014-01-01

    Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance. PMID:25274751

  16. Ion implantation and fracture toughness of ceramics

    International Nuclear Information System (INIS)

    Clark, J.; Pollock, J.T.A.

    1985-01-01

    Ceramics generally lack toughness which is largely determined by the ceramic surface where stresses likely to cause failure are usually highest. Ion implantation has the capacity to improve the surface fracture toughness of ceramics. Significantly reduced ion size and reactivity restrictions exist compared with traditional methods of surface toughening. We are studying the effect of ion implantation on ceramic fracture toughness using indentation testing as the principal tool of analysis

  17. Ceramic cutting tools materials, development and performance

    CERN Document Server

    Whitney, E Dow

    1994-01-01

    Interest in ceramics as a high speed cutting tool material is based primarily on favorable material properties. As a class of materials, ceramics possess high melting points, excellent hardness and good wear resistance. Unlike most metals, hardness levels in ceramics generally remain high at elevated temperatures which means that cutting tip integrity is relatively unaffected at high cutting speeds. Ceramics are also chemically inert against most workmetals.

  18. Ferroelastic ceramic-reinforced metal matrix composites

    OpenAIRE

    2006-01-01

    Composite materials comprising ferroelastic ceramic particulates dispersed in a metal matrix are capable of vibration damping. When the ferroelastic ceramic particulates are subjected to stress, such as the cyclic stress experienced during vibration of the material, internal stresses in the ceramic cause the material to deform via twinning, domain rotation or domain motion thereby dissipating the vibrational energy. The ferroelastic ceramic particulates may also act as reinforcements to impro...

  19. Development of advanced ceramics at AECL

    International Nuclear Information System (INIS)

    Palmer, B.J.F.; MacEwen, S.R.; Sawicka, B.D.; Hayward, P.J.; Sridhar, S.

    1986-12-01

    Atomic Energy of Canada Limited (AECL) has a long history of developing ceramics for nuclear fission and fusion applications. AECL is now applying its multidisciplinary materials R and D capabilities, including unique capabilities in ceramic processing and nondestructive evaluation, to develop advanced ceramic materials for commercial and industrial applications. This report provides an overview of the facilities and programs associated with the development of advanced ceramics at AECL

  20. What every surgeon should know about Ceramic-on-Ceramic bearings in young patients

    OpenAIRE

    Hernigou, Philippe; Roubineau, Fran?ois; Bouthors, Charlie; Flouzat-Lachaniette, Charles-Henri

    2016-01-01

    Based on the exceptional tribological behaviour and on the relatively low biological activity of ceramic particles, Ceramic-on-Ceramic (CoC) total hip arthroplasty (THA) presents significant advantages CoC bearings decrease wear and osteolysis, the cumulative long-term risk of dislocation, muscle atrophy, and head-neck taper corrosion. However, there are still concerns regarding the best technique for implantation of ceramic hips to avoid fracture, squeaking, and revision of ceramic hips with...

  1. Durability of feldspathic veneering ceramic on glass-infiltrated alumina ceramics after long-term thermocycling.

    Science.gov (United States)

    Mesquita, A M M; Ozcan, M; Souza, R O A; Kojima, A N; Nishioka, R S; Kimpara, E T; Bottino, M A

    2010-01-01

    This study compared the bond strength durability of a feldspathic veneering ceramic to glass-infiltrated reinforced ceramics in dry and aged conditions. Disc shaped (thickness: 4 mm, diameter: 4 mm) of glass-infiltrated alumina (In-Ceram Alumina) and glass-infiltrated alumina reinforced by zirconia (In-Ceram Zirconia) core ceramic specimens (N=48, N=12 per groups) were constructed according to the manufacturers' recommendations. Veneering ceramic (VITA VM7) was fired onto the core ceramics using a mold. The core-veneering ceramic assemblies were randomly divided into two conditions and tested either immediately after specimen preparation (Dry) or following 30000 thermocycling (5-55 ºC±1; dwell time: 30 seconds). Shear bond strength test was performed in a universal testing machine (cross-head speed: 1 mm/min). Failure modes were analyzed using optical microscope (x20). The bond strength data (MPa) were analyzed using ANOVA (α=0.05). Thermocycling did not decrease the bond strength results for both In-Ceram Alumina (30.6±8.2 MPa; P=0.2053) and In-Ceram zirconia (32.6±9 MPa; P=0.3987) core ceramic-feldspathic veneering ceramic combinations when compared to non-aged conditions (28.1±6.4 MPa, 29.7±7.3 MPa, respectively). There were also no significant differences between adhesion of the veneering ceramic to either In-Ceram Alumina or In-Ceram Zirconia ceramics (P=0.3289). Failure types were predominantly a mixture of adhesive failure between the veneering and the core ceramic together with cohesive fracture of the veneering ceramic. Long-term thermocycling aging conditions did not impair the adhesion of the veneering ceramic to the glass-infiltrated alumina core ceramics tested.

  2. Dense high temperature ceramic oxide superconductors

    Science.gov (United States)

    Landingham, Richard L.

    1993-01-01

    Dense superconducting ceramic oxide articles of manufacture and methods for producing these articles are described. Generally these articles are produced by first processing these superconducting oxides by ceramic processing techniques to optimize materials properties, followed by reestablishing the superconducting state in a desired portion of the ceramic oxide composite.

  3. Ceramic component with reinforced protection against radiations

    International Nuclear Information System (INIS)

    Dubuisson, J.; Laville, H.; Le Gal, P.

    1986-01-01

    Ceramic components hardened against radiations are claimed (for example capacitors or ceramic substrates for semiconductors). They are prepared with a sintered ceramic containing a high proportion of heavy atoms (for instance barium titanate and a bismuth salt) provided with a glass layer containing a high proportion of light atoms. The two materials are joined by vitrification producing a diffusion zone at the interface [fr

  4. Study of brazilian market of advanvced ceramics

    International Nuclear Information System (INIS)

    Veiga, M.M.; Soares, P.S.M.; SIlva, A.P. da; Alvarinho, S.B.

    1989-01-01

    The brazilian actual market survey of advanced ceramics, divided in sectors according to their function is described. The electroelectronics, magnetics, optics, mechanics and nuclears ceramics are presented. A forecasting of the brazilian market in advanced ceramics are also mentioned. (C.G.C.) [pt

  5. Polymer-ceramic piezoelectric composites (PZT)

    International Nuclear Information System (INIS)

    Bassora, L.A.; Eiras, J.A.

    1992-01-01

    Polymer-ceramic piezoelectric transducers, with 1-3 of connectivity were prepared with different concentration of ceramic material. Piezoelectric composites, with equal electromechanical coupling factor and acoustic impedance of one third from that ceramic transducer, were obtained when the fractionary volume of PZT reach 30%. (C.G.C.)

  6. Surface treatment of ceramic articles

    International Nuclear Information System (INIS)

    Komvopoulos, K.; Brown, I.G.; Wei, B.; Anders, S.; Anders, A.; Bhatia, C.S.

    1998-01-01

    A process is disclosed for producing an article with improved ceramic surface properties including providing an article having a ceramic surface, and placing the article onto a conductive substrate holder in a hermetic enclosure. Thereafter a low pressure ambient is provided in the hermetic enclosure. A plasma including ions of solid materials is produced the ceramic surface of the article being at least partially immersed in a macroparticle free region of the plasma. While the article is immersed in the macroparticle free region, a bias of the substrate holder is biased between a low voltage at which material from the plasma condenses on the surface of the article and a high negative voltage at which ions from the plasma are implanted into the article. 15 figs

  7. Dynamic properties of ceramic materials

    International Nuclear Information System (INIS)

    Grady, D.E.

    1995-02-01

    The present study offers new data and analysis on the transient shock strength and equation-of-state properties of ceramics. Various dynamic data on nine high strength ceramics are provided with wave profile measurements, through velocity interferometry techniques, the principal observable. Compressive failure in the shock wave front, with emphasis on brittle versus ductile mechanisms of deformation, is examined in some detail. Extensive spall strength data are provided and related to the theoretical spall strength, and to energy-based theories of the spall process. Failure waves, as a mechanism of deformation in the transient shock process, are examined. Strength and equation-of-state analysis of shock data on silicon carbide, boron carbide, tungsten carbide, silicon dioxide and aluminum nitride is presented with particular emphasis on phase transition properties for the latter two. Wave profile measurements on selected ceramics are investigated for evidence of rate sensitive elastic precursor decay in the shock front failure process

  8. Wear and Reactivity Studies of Melt infiltrated Ceramic Matrix Composite

    Science.gov (United States)

    Jarmon, David C.; Ojard, Greg; Brewer, David N.

    2013-01-01

    As interest grows in the use of ceramic matrix composites (CMCs) for critical gas turbine engine components, the effects of the CMCs interaction with the adjoining structure needs to be understood. A series of CMC/material couples were wear tested in a custom elevated temperature test rig and tested as diffusion couples, to identify interactions. Specifically, melt infiltrated silicon carbide/silicon carbide (MI SiC/SiC) CMC was tested in combination with a nickel-based super alloy, Waspaloy, a thermal barrier coating, Yttria Stabilized Zirconia (YSZ), and a monolithic ceramic, silicon nitride (Si3N4). To make the tests more representative of actual hardware, the surface of the CMC was kept in the as-received state (not machined) with the full surface features/roughness present. Test results include: scanning electron microscope characterization of the surfaces, micro-structural characterization, and microprobe analysis.

  9. Superplastic forging nitride ceramics

    Science.gov (United States)

    Panda, P.C.; Seydel, E.R.; Raj, R.

    1988-03-22

    A process is disclosed for preparing silicon nitride ceramic parts which are relatively flaw free and which need little or no machining, said process comprising the steps of: (a) preparing a starting powder by wet or dry mixing ingredients comprising by weight from about 70% to about 99% silicon nitride, from about 1% to about 30% of liquid phase forming additive and from 1% to about 7% free silicon; (b) cold pressing to obtain a preform of green density ranging from about 30% to about 75% of theoretical density; (c) sintering at atmospheric pressure in a nitrogen atmosphere at a temperature ranging from about 1,400 C to about 2,200 C to obtain a density which ranges from about 50% to about 100% of theoretical density and which is higher than said preform green density, and (d) press forging workpiece resulting from step (c) by isothermally uniaxially pressing said workpiece in an open die without initial contact between said workpiece and die wall perpendicular to the direction of pressing and so that pressed workpiece does not contact die wall perpendicular to the direction of pressing, to substantially final shape in a nitrogen atmosphere utilizing a temperature within the range of from about 1,400 C to essentially 1,750 C and strain rate within the range of about 10[sup [minus]7] to about 10[sup [minus]1] seconds[sup [minus]1], the temperature and strain rate being such that surface cracks do not occur, said pressing being carried out to obtain a shear deformation greater than 30% whereby superplastic forging is effected.

  10. Chemical characterization of marajoara ceramics

    International Nuclear Information System (INIS)

    Toyota, Rosimeiri Galbiati

    2009-01-01

    In this study the elemental concentration of Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn were determined by instrumental neutron activation analysis (INAA) in 204 fragments of Marajoara archaeological ceramics, of which 156 were provided by the Archaeology and Ethnology Museum of Sao Paulo University (MAE) and 48 were provided by Dr. Denise Pahl Schaan, Marajo Museum curator. Also, 9 contemporary ceramics produced and marketed at Marajo Island were analyzed. Electron paramagnetic resonance (EPR) analyses were performed in 8 archaeological samples and 1 contemporary sample in order to identify the burning temperature of the samples. X-ray diffraction (XRD) analyses were performed in 13 archaeological samples and 2 contemporary samples for the investigation of their mineralogical composition. Mahalanobis distance was used for the study of outlier while modified filter was used for the study of the temper added to the ceramic paste. Result interpretation was performed using cluster analysis, principal components analysis and discriminant analysis. Procrustes analysis was used for variable selection and it showed that the Ce, Fe, Eu, Hf, K and Th variables are adequate for the characterization of the analyzed samples. The comparative study among the archaeological and contemporary ceramics showed the arrangement of two well-defined and close groups for the archaeological samples and a third, distant group for the contemporary ones. This result indicates that the archaeological and contemporary ceramics differ in their composition. EPR and XRD analysis were inconclusive for the differentiation of archaeological and contemporary ceramics. (author)

  11. Influence of Resin Cements on Color Stability of Different Ceramic Systems.

    Science.gov (United States)

    Rodrigues, Renata Borges; Lima, Erick de; Roscoe, Marina Guimarães; Soares, Carlos José; Cesar, Paulo Francisco; Novais, Veridiana Resende

    2017-01-01

    The purpose of this study was to evaluate color stability of two dental ceramics cemented with two resin cements, assessing the color difference (ΔE00) by the measurement of L*, a*, b*, c* and h* of transmittance. The combination of two ceramic system (feldspathic and lithium disilicate) and two resin cements - color A3 (RelyX ARC and Variolink II) resulted in 4 groups (n=5). Ten disks-shaped specimens were fabricated for each ceramic system (10x1.5 mm), etched with hydrofluoric acid (10%) and silanized prior to cementation. The color analysis was performed 24 h after cementation of the samples and after 6 months of storage in relative humidity by means of spectrophotometry. The ΔE00 values were analyzed statistically by two-way ANOVA followed by the Tukey test (p<0.05). One-way ANOVA were calculated for the means of individual color coordinates (L*, a*, b*, c* and h*). Two-way ANOVA showed that only the ceramic factor was significant (p=0.003), but there was no difference for the cement factor (p=0.275) nor for the ceramic/cement interaction (p=0.161). The feldspathic ceramic showed the highest values of ΔE00. Variations in L*, a*, b*, c* and h* were more significant for feldspathic ceramic. In conclusion, storage alters similarly the optical properties of the resin cements and feldspathic porcelain was more susceptible to cement color change after aging.

  12. Craft Arts and Tourism in Ceramic Art Village of Kasongan in Yogyakarta

    Directory of Open Access Journals (Sweden)

    sp gustami

    2014-03-01

    Full Text Available Yogyakarta is one of Indonesia’s major tourist destinations. This is due to its nature, interesting, unique and fantastic ancient cultural and art sites. Creative industries and the ceramic crafts play an important role in the development of tourism in Yogyakarta. In this paper, ethnographic approach is used to describe the creative process and the ceramic crafts industry in the village of Kasongan, Yogyakarta. Based on the results of the field research, the authors conclude that the ceramic crafts tourist village of Kasongan is moving toward greater commoditization whereby the ceramics centre is now more oriented towards meeting the needs of tourist industry in Yogyakarta. Due to extensive interaction and the positive response from the general public, ceramic crafts practitioners of Kasongan experience unique and characteristic creative period. The crafters manage to negotiate between the old and the new values, in the village one can find both traditional pottery and new, creative and innovative ceramic products of export quality. Today, Kasongan is a trade mark ceramic tourism village that is entering the global era.

  13. Uranium determination in dental ceramics

    International Nuclear Information System (INIS)

    Jacobson, I.; Gamboa, I.; Espinosa, G.; Moreno, A.

    1984-01-01

    There are many reports of high uranium concentration in dental ceramics, so they require to be controlled. The SSNTD is an optional method to determine the uranium concentration. In this work the analysis of several commercial dental ceramics used regularly in Mexico by dentists is presented. The chemical and electrochemical processes are used and the optimal conditions for high sensitivity are determined. CR-39 (allyl diglycol polycarbonate) was used as detector. The preliminary results show some materials with high uranium concentrations. Next step will be the analysis of equivalent dose and the effects in the public health. (author)

  14. Fracture mechanical treatment of bridging stresses in ceramics

    International Nuclear Information System (INIS)

    Fett, T.; Munz, D.

    1993-12-01

    Failure of ceramic materials often starts from cracks which can originate at pores, inclusions or can be generated during surface treatment. Fracture occurs when the stress intensity factor of the most serious crack in a component reaches a critical value K lc , the fracture toughness of the material. In case of ideal brittle materials the fracture toughness is independent of the crack extension and, consequently, identical with the stress intensity factor K l0 necessary for the onset of stable crack growth. It is a well-known fact that failure of several ceramics is influenced by an increasing crack-growth resistance curve. Several effects are responsible for this behaviour. Crack-border interactions in the wake of the advancing crack, residual stress fields in the crack region of transformation-toughened ceramics, the generation of a micro-crack zone ahead the crack tip and crack branching. The effect of increasing crack resistance has consequences on many properties of ceramic materials. In this report the authors discuss the some aspects of R-curve behaviour as the representation by stress intensity factors or energies and the influence on the compliance using the bridging stress model. (orig.) [de

  15. Fracture mechanics of ceramics. Vol. 7

    International Nuclear Information System (INIS)

    Bradt, R.C.; Evans, A.G.; Hasselman, D.P.; Lange, F.F.

    1986-01-01

    This volume, together with volume 8, constitutes the proceedings of an international symposium on the fracture mechanics of ceramics. The topics discussed in this volume include the toughening of ceramics by whisker reinforcement; the mechanical properties of SiCwhisker-reinforced TZP; the fracture of brittle rock and oil shale under dynamic explosive loading; impact damage models of ceramic coatings used in gas turbine and diesel engines; the use of exploratory data analysis for the safety evaluation of structural ceramics; and proof testing methods for the reliability of structural ceramics used in gas turbines

  16. MHD oxidant intermediate temperature ceramic heater study

    Science.gov (United States)

    Carlson, A. W.; Chait, I. L.; Saari, D. P.; Marksberry, C. L.

    1981-09-01

    The use of three types of directly fired ceramic heaters for preheating oxygen enriched air to an intermediate temperature of 1144K was investigated. The three types of ceramic heaters are: (1) a fixed bed, periodic flow ceramic brick regenerative heater; (2) a ceramic pebble regenerative heater. The heater design, performance and operating characteristics under conditions in which the particulate matter is not solidified are evaluated. A comparison and overall evaluation of the three types of ceramic heaters and temperature range determination at which the particulate matter in the MHD exhaust gas is estimated to be a dry powder are presented.

  17. Ceramic nanostructures and methods of fabrication

    Science.gov (United States)

    Ripley, Edward B [Knoxville, TN; Seals, Roland D [Oak Ridge, TN; Morrell, Jonathan S [Knoxville, TN

    2009-11-24

    Structures and methods for the fabrication of ceramic nanostructures. Structures include metal particles, preferably comprising copper, disposed on a ceramic substrate. The structures are heated, preferably in the presence of microwaves, to a temperature that softens the metal particles and preferably forms a pool of molten ceramic under the softened metal particle. A nano-generator is created wherein ceramic material diffuses through the molten particle and forms ceramic nanostructures on a polar site of the metal particle. The nanostructures may comprise silica, alumina, titania, or compounds or mixtures thereof.

  18. Comparison of thermal analysis, micro structural and compositional of archaeological indigenous ceramic (Caninhas site of Canas - SP) with actual clay/ceramic of region

    International Nuclear Information System (INIS)

    Nakano, F.P.; Taguchi, S.P.; Matos, C.C.; Ribeiro, R.B.

    2009-01-01

    The ceramic material found at the archaeological site in Caninhas, shows funerary structures of combustion and various objects of Tupi-Guarani indigenous use. These pieces and fragments were saved and cataloged, in approximately 4000 units. The ceramics present a gradient of color, from ochre to dark gray, when from the surface to the center of the piece, indicating compositional variation caused by inefficient sintering carried out by indigenous people. The goal of this study was to observe the phase transition temperature, decomposition, mass variation and reactions that occur in the archaeological and nowadays ceramics (by DSC/TG), together with micro structural analysis (by SEM), phase analysis (by XRD) and chemical composition (by EDS). Ceramics nowadays are sintered with air, in a temperature ranging between 400-800 °C for one hour, and presents heterogeneous microstructure. The archaeological ceramics were identified by the illite, hydrated alumina, lutecite and quartz phase, and the caulinite, lutecite and quartz phase in clay produced today from that region differs in all characteristics and aspects according to time. The interaction between different areas of expertise is fundamental to aggregate knowledge: the use of ceramic material engineering to archaeological application. (author)

  19. A new classification system for all-ceramic and ceramic-like restorative materials.

    Science.gov (United States)

    Gracis, Stefano; Thompson, Van P; Ferencz, Jonathan L; Silva, Nelson R F A; Bonfante, Estevam A

    2015-01-01

    Classification systems for all-ceramic materials are useful for communication and educational purposes and warrant continuous revisions and updates to incorporate new materials. This article proposes a classification system for ceramic and ceramic-like restorative materials in an attempt to systematize and include a new class of materials. This new classification system categorizes ceramic restorative materials into three families: (1) glass-matrix ceramics, (2) polycrystalline ceramics, and (3) resin-matrix ceramics. Subfamilies are described in each group along with their composition, allowing for newly developed materials to be placed into the already existing main families. The criteria used to differentiate ceramic materials are based on the phase or phases present in their chemical composition. Thus, an all-ceramic material is classified according to whether a glass-matrix phase is present (glass-matrix ceramics) or absent (polycrystalline ceramics) or whether the material contains an organic matrix highly filled with ceramic particles (resin-matrix ceramics). Also presented are the manufacturers' clinical indications for the different materials and an overview of the different fabrication methods and whether they are used as framework materials or monolithic solutions. Current developments in ceramic materials not yet available to the dental market are discussed.

  20. Industrial ceramics in Spain

    Directory of Open Access Journals (Sweden)

    Regueiro, M.

    2000-02-01

    Full Text Available The Spanish ceramic industry has experienced a amazing growth in the last four years. Such expansion has affected all sector, but has been particularly noteworthy in those directly related to construction: tiles. glazes, bricks and roof tiles. A combination of an extraordinary exporting effort, together with a record figure in new housing projects (415 000 houses in 1999, are responsible for such outburst. Other sectors, such as refractories have undergone significant growths due to the high rate of steel production increase, also in historical record figures (15m t in 1999. All this sectors doubled altogether the growing rate of their main European competitors. Raw material production has had an even more effervescent trend, almost doubling 1995 production. Such dynamic growth has been associated to a remarkable quality increase and to an unparalleled technological innovation process.

    La industria española de la cerámica ha experimentado un notable crecimiento en los últimos cuatro años; expansión que ha alcanzado a todos los sectores, pero que ha sido especialmente notable en los mas directamente asociados a la construcción: revestimientos, esmaltes, tejas y ladrillos. La combinación de un extraordinario esfuerzo exportador unido a las cifras récord en la viviendas iniciadas, 415 000 en 1999, justifican este auge. Otros sectores como refractarios han experimentado crecimientos significativos ante el ritmo elevado en la producción de acero, que alcanzó asimismo un récord histórico, 15 Mt en 1999. Para el conjunto de estos sectores el ritmo de crecimiento ha duplicado el de los principales competidores europeos. La producción de materias primas han experimentado un dinamismo aún mas elevado duplicándose prácticamente las cifras respecto a 1995. Este crecimiento ha estado asociado a un notable incremento en la calidad y en los procesos de innovación tecnológica.

  1. Electrophoretic deposition of Mn1.5Co1.5O4 on metallic interconnect and interaction with glass-ceramic sealant for solid oxide fuel cells application

    DEFF Research Database (Denmark)

    Smeacetto, Federico; De Miranda, Auristela; Cabanas Polo, Sandra

    2015-01-01

    Cr-containing stainless steels are widely used as metallic interconnects for SOFCs. Volatile Cr-containing species, which originate from the oxide formed on steel, can poison the cathode material and subsequently cause degradation in the SOFC stack. Mn1.5Co1.5O4 spinel is one of the most promisin...... between Mn1.5Co1.5O4 coated Crofer22APU and a new glass-ceramic sealant, after 500 h of thermal tests in air, thus suggesting that the spinel protection layer can effectively act as a barrier to outward diffusion of Cr. [All rights reserved Elsevier].......Cr-containing stainless steels are widely used as metallic interconnects for SOFCs. Volatile Cr-containing species, which originate from the oxide formed on steel, can poison the cathode material and subsequently cause degradation in the SOFC stack. Mn1.5Co1.5O4 spinel is one of the most promising...... coating materials due to its high electrical conductivity, good CTE match with the stainless steel substrate and an excellent chromium retention capability. In this work Mn1.5Co1.5O4 spinel coatings are deposited on Crofer22APU substrates by cathodic electrophoretic deposition (EPD) followed by sintering...

  2. Translucency and masking properties of two ceramic materials for heat-press technology.

    Science.gov (United States)

    Șoim, Alexandra; Strîmbu, Maria; Burde, Alexandru V; Culic, Bogdan; Dudea, Diana; Gasparik, Cristina

    2018-03-01

    To assess the translucency of two pressable ceramics and to analyze their masking property when placed on different tooth-shaded backgrounds. Thirty discs (1-mm thickness) were fabricated using two pressable ceramics (shade/translucency): 1M1T/HT, 1M2T/HT, 2M2T (VITA PM9), and A1LT/HT, B1LT/HT, A2LT (e.max Press). Color measurements of discs were performed with a dental spectrophotometer on tooth-colored backgrounds (A1/A2/A3/A3.5/A4), and black and white backings. The masking property was calculated as the color difference (CIEDE2000) between parameters of discs on control (A1, A2) and test backgrounds (A3, A3.5, A4). One-way ANOVA was used for assessing differences in translucency parameter (TP) between ceramics. Two-way ANOVA was used for detecting differences among groups when measured over tooth-shaded backgrounds (α = 0.05, Bonferroni correction). TP ranged between 14.96 (B1LT) and 25.18 (1M1HT). A significant difference in TP was found between tested ceramics (F = 949.949, P  .05), 1M1T, A1HT and B1HT (P > .05), 1M2T, 2M2T, and A2HT (P > .05). A significant interaction effect of underlying background on color of ceramic discs was found (F = 107.994, P ceramics. Except A1LT, all ceramic materials evaluated showed poor masking properties on A4 background. Highly translucent ceramics should be wisely used for restoring the appearance of dental structures since background color has a large effect upon these materials. The more recently introduced pressable ceramics showed high levels of translucency. © 2018 Wiley Periodicals, Inc.

  3. Dispersion toughened silicon carbon ceramics

    Science.gov (United States)

    Wei, G.C.

    1984-01-01

    Fracture resistant silicon carbide ceramics are provided by incorporating therein a particulate dispersoid selected from the group consisting of (a) a mixture of boron, carbon and tungsten, (b) a mixture of boron, carbon and molybdenum, (c) a mixture of boron, carbon and titanium carbide, (d) a mixture of aluminum oxide and zirconium oxide, and (e) boron nitride. 4 figures.

  4. Microstructural Design for Tough Ceramics

    Science.gov (United States)

    1994-10-01

    or Rockwell cones) where the contact pressure (i.e. the ’hardness’) is effectively independent of load (Sperisen, Carry and Mocellin 1986, Makino...148. RrrcHM, R. 0., 1988, Mater. Sci. Engng, A, 103, 15. SPERmEN, T., CARRY, C., and MOCELLIN , A, 1986, Fracture Mechanics of Ceramics, Vol. 8, edited

  5. Electrical Degradation in Ceramic Dielectrics

    Science.gov (United States)

    1988-09-09

    and D. M. Smyth, " Positron Annihilation in Calcium-Doped Barium Titanate", in Electro- Ceramics and Solid State Ionsi, H. L. Tuller and D. M. Smyth...2 with the formation of ompensating oxygen vacancies, and this causes an increase in the ioni conductivity: 2CaO CaC + Call + 20 + (5) TiO2 --- V

  6. Natural Radioactivity in Ceramic Materials

    International Nuclear Information System (INIS)

    Abu Khadra, S.A.; Kamel, N.H.

    2005-01-01

    Ceramics are one of the most important types of the industrial building materials. The raw materials of the ceramic are made of a mixture of clay, feldspar, silica, talc kaolin minerals together with zirconium silicates (ZrSiO4).The ceramic raw materials and the final products contain naturally occurring radionuclide mainly U-238 and, Th-232 series, and the radioactive isotope of potassium K-40. Six raw ceramic samples were obtained from the Aracemco Company at Egypt together with a floor tile sample (final product) for measuring radioactive concentration levels., The activity of the naturally U-238, Th-232, and K-40 were determined as (Bq/kg) using gamma spectroscopy (Hyperactive pure germanium detector). Concentration of U and Th were determined in (ppm) using spectrophotometer technique by Arsenazo 111 and Piridy l-Azo -Resorcinol (PAR) indicators. Sequential extraction tests were carried out in order to determine the quantity of the radionuclide associated with various fractions as exchangeable, carbonate, acid soluble and in the residue. The results evaluated were compared to the associated activity indices (AI) that were defined by former USSR and West Germany

  7. Ceramic microspheres for cementing applications

    NARCIS (Netherlands)

    2011-01-01

    A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

  8. Ceramic microspheres for cementing applications

    NARCIS (Netherlands)

    2010-01-01

    A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

  9. Ceramic microspheres for cementing applications

    NARCIS (Netherlands)

    2012-01-01

    A method and apparatus for manufacturing ceramic microspheres from industrial slag. The microspheres have a particle size of about 38 microns to about 150 microns. The microspheres are used to create a cement slurry having a density of at least about 11 lbs/g. The resultant cement slurry may then be

  10. [Posterior ceramic bonded partial restorations].

    Science.gov (United States)

    Mainjot, Amélie; Vanheusden, Alain

    2006-01-01

    Posterior ceramic bonded partial restorations are conservative and esthetic approaches for compromised teeth. Overlays constitute a less invasive alternative for tooth tissues than crown preparations. With inlays and onlays they are also indicated in case of full arch or quadrant rehabilitations including several teeth. This article screens indications and realization of this type of restorations.

  11. GEORGIAN PRODUCTION PREFABRICATED CERAMIC FIREPLACE

    International Nuclear Information System (INIS)

    Gaprindashvili, G.; Chemia, M.; Kartozia, L.

    2006-01-01

    General description and basic working principles of new construction prefabricated ceramic fireplace are given. The presented fireplace represents a unique synthesis of various fireplaces distributed in Georgian and some European countries; however, it is distinguished for its higher efficiency and other advantages. (author)

  12. Monolithic Integrated Ceramic Waveguide Filters

    OpenAIRE

    Hunter, IC; Sandhu, MY

    2014-01-01

    Design techniques for a new class of integrated monolithic high permittivity ceramic waveguide filters are presented. These filters enable a size reduction of 50% compared to air-filled TEM filters with the same unloaded Q-Factor. Designs for both chebyshev and asymmetric generalized chebyshev filter are presented, with experimental results for an 1800 MHz chebyshev filter showing excellent agreement with theory.

  13. Compositionally Graded Multilayer Ceramic Capacitors.

    Science.gov (United States)

    Song, Hyun-Cheol; Zhou, Jie E; Maurya, Deepam; Yan, Yongke; Wang, Yu U; Priya, Shashank

    2017-09-27

    Multilayer ceramic capacitors (MLCC) are widely used in consumer electronics. Here, we provide a transformative method for achieving high dielectric response and tunability over a wide temperature range through design of compositionally graded multilayer (CGML) architecture. Compositionally graded MLCCs were found to exhibit enhanced dielectric tunability (70%) along with small dielectric losses (filters and power converters.

  14. Soft lithography of ceramic patterns

    NARCIS (Netherlands)

    Göbel, Ole; Nedelcu, M.; Steiner, U.

    2007-01-01

    Polymer-based precursor solutions are patterned using a soft-lithographic patterning technique to yield sub-micrometer-sized ceramic patterns. By using a polymer-metal-nitrate solution as a lithographic resist, we demonstrate a micromolding procedure using a simple rubber stamp that yields a

  15. Science and Technology of Ceramics

    Indian Academy of Sciences (India)

    These ceramics are developed by chemical synthesis, in other words, they ... Science in 1980 and was a post doctoral ... complex crystal structures that have anisotropic characteristics. (Box 1) .... is a rare-earth or transition metal ion) and hexagonal ferrites. .... dielectric loss factor and dielectric strength normally determine.

  16. Photovoltaic effect in ferroelectric ceramics

    Science.gov (United States)

    Epstein, D. J.; Linz, A.; Jenssen, H. P.

    1982-01-01

    The ceramic structure was simulated in a form that is more tractable to correlation between experiment and theory. Single crystals (of barium titanate) were fabricated in a simple corrugated structure in which the pedestals of the corrugation simulated the grain while the intervening cuts could be filled with materials simulating the grain boundaries. The observed photovoltages were extremely small (100 mv).

  17. Doubled-ended ceramic thyratron

    CERN Multimedia

    1974-01-01

    The double-ended ceramic thyratron CX 1171 B, with its coaxial voltage divider for the SPS. Such a switch, paralleled by three ignitrons in series forms the "thyragnitron" arrangement, and can switch 10 kA, 25 ms pulses, with very fast rise times.

  18. Ceramic matrix composite article and process of fabricating a ceramic matrix composite article

    Science.gov (United States)

    Cairo, Ronald Robert; DiMascio, Paul Stephen; Parolini, Jason Robert

    2016-01-12

    A ceramic matrix composite article and a process of fabricating a ceramic matrix composite are disclosed. The ceramic matrix composite article includes a matrix distribution pattern formed by a manifold and ceramic matrix composite plies laid up on the matrix distribution pattern, includes the manifold, or a combination thereof. The manifold includes one or more matrix distribution channels operably connected to a delivery interface, the delivery interface configured for providing matrix material to one or more of the ceramic matrix composite plies. The process includes providing the manifold, forming the matrix distribution pattern by transporting the matrix material through the manifold, and contacting the ceramic matrix composite plies with the matrix material.

  19. Ceramic Adhesive and Methods for On-Orbit Repair of Re-Entry Vehicles

    Science.gov (United States)

    Riedell, James A.; Easler, Timothy E.

    2013-01-01

    This adhesive is capable of repairing damaged leading edge components of reentry vehicles while in space, and is novel with regard to its ability to be applied in the vacuum of space, and in a microgravity environment. Once applied, the adhesive provides thermal and oxidation protection to the substrate (in this case, reinforced carbon/carbon composites, RCCs) during re-entry of a space vehicle. Although there may be many formulations for repair adhesives, at the time of this reporting, this is the first known adhesive capable of an on-orbit repair. The adhesive is an engineered ceramic material composed of a pre-ceramic polymer and refractory powders in the form of a paste or putty that can be applied to a scratched, cracked, or fractured composite surface, covering and protecting the damaged area. The adhesive is then "cured" with a heat cycle, thereby cross-linking the polymer into a hardened material and bonding it to the substrate. During the heat of reentry, the material is converted to a ceramic coating that provides thermal and oxidative stability to the repaired area, thus allowing the vehicle to pass safely from space into the upper atmosphere. Ceramic powders such as SiC, ZrB2 and Y2O3 are combined with allylhydridopolycarbosilane (AHPCS) resin, and are mixed to form a paste adhesive. The material is then applied to the damaged area by brush, spatula, trowel, or other means to fill cracks, gaps, and holes, or used to bond patches onto the damaged area. The material is then cured, in a vacuum, preferably at 250F (approximately equal to 121C) for two hours. The re-entry heating of the vehicle at temperatures in excess of 3,000F (approximately equal to 1,650C) then converts this material into a ceramic coating. This invention has demonstrated advantages in resistance to high temperatures, as was demonstrated in more than 100 arc-jet tests in representative environments at NASA. Extensive testing verified oxidation protection for the repaired substrate (RCC

  20. Application of neutron activation analysis in study of ancient ceramics

    International Nuclear Information System (INIS)

    Li Guoxia; Zhao Weijuan; Gao Zhengyao; Xie Jianzhong; Huang Zhongxiang; Jia Xiuqin; Han Song

    2000-01-01

    Trace-elements in ancient ceramics and imitative ancient ceramics were determined by neutron activation analysis (NAA). The NAA data are then analyzed by fuzzy cluster method and the trend cluster diagram is obtained. The raw material sources of ancient ceramics and imitative ancient ceramics are determined. The path for improving quality of imitative ancient ceramics is found

  1. Translucency of dental ceramics with different thicknesses.

    Science.gov (United States)

    Wang, Fu; Takahashi, Hidekazu; Iwasaki, Naohiko

    2013-07-01

    The increased use of esthetic restorations requires an improved understanding of the translucent characteristics of ceramic materials. Ceramic translucency has been considered to be dependent on composition and thickness, but less information is available about the translucent characteristics of these materials, especially at different thicknesses. The purpose of this study was to investigate the relationship between translucency and the thickness of different dental ceramics. Six disk-shaped specimens of 8 glass ceramics (IPS e.max Press HO, MO, LT, HT, IPS e.max CAD LT, MO, AvanteZ Dentin, and Trans) and 5 specimens of 5 zirconia ceramics (Cercon Base, Zenotec Zr Bridge, Lava Standard, Lava Standard FS3, and Lava Plus High Translucency) were prepared following the manufacturers' instructions and ground to a predetermined thickness with a grinding machine. A spectrophotometer was used to measure the translucency parameters (TP) of the glass ceramics, which ranged from 2.0 to 0.6 mm, and of the zirconia ceramics, which ranged from 1.0 to 0.4 mm. The relationship between the thickness and TP of each material was evaluated using a regression analysis (α=.05). The TP values of the glass ceramics ranged from 2.2 to 25.3 and the zirconia ceramics from 5.5 to 15.1. There was an increase in the TP with a decrease in thickness, but the amount of change was material dependent. An exponential relationship with statistical significance (Pceramics and zirconia ceramics. The translucency of dental ceramics was significantly influenced by both material and thickness. The translucency of all materials increased exponentially as the thickness decreased. All of the zirconia ceramics evaluated in the present study showed some degree of translucency, which was less sensitive to thickness compared to that of the glass ceramics. Copyright © 2013 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  2. Surface degradation of glass ceramics after exposure to acidulated phosphate fluoride

    Science.gov (United States)

    CCAHUANA, Vanessa Zulema S.; ÖZCAN, Mutlu; MESQUITA, Alfredo Mikail Melo; NISHIOKA, Renato Sussumo; KIMPARA, Estevão Tomomitsu; BOTTINO, Marco Antonio

    2010-01-01

    Objective This study evaluated the surface degradation effect of acidulated phosphate fluoride (APF) gel exposure on the glassy matrix ceramics as a function of time. Material and methods Disc-shaped ceramic specimens (N = 120, 10/per ceramic material) were prepared in stainless steel molds (inner diameter: 5 mm, height: 2 mm) using 6 dental ceramics: 3 indicated for ceramic-fused-to-metal (Vita Omega 900, Carmen and Vita Titankeramik), 2 for all-ceramic (Vitadur Alpha and Finesse® Low Fusing) and 1 for both types of restorations (IPS d.SIGN). The specimens were wet ground finished, ultrasonically cleaned and auto-glazed. All specimens were subjected to calculation of percentage of mass loss, surface roughness analysis and topographical description by scanning electron microscopy (SEM) before (0 min) and after exposure to 1.23 % APF gel for 4 min and 60 min representing short- and long-term etching effect, respectively. The data were analyzed using two-way ANOVA with repeated measures and Tukey`s test (α=0.05). Results Significant effect of the type of the ceramics (p=0.0000, p=0.0031) and exposure time (p=0.0000) was observed in both surface roughness and percentage of mass loss values, respectively. The interaction factor between both parameters was also significant for both parameters (p=0.0904, p=0.0258). Both 4 min (0.44±0.1 - 0.81±0.2 µm) and 60 min (0.66±0.1 - 1.04±0.3 µm) APF gel exposure created significantly more surface roughness for all groups when compared to the control groups (0.33±0.2 - 0.68±0.2 µm) (p0.05) but at 60 min exposure, IPS d.SIGN showed the highest percentage of mass loss (0.1151±0.11). The mean surface roughness for Vita Titankeramik (0.84±0.2 µm) and Finesse® Low Fusing (0.74.±0.2 µm) was significantly higher than those of the other ceramics (0.59±0.1 µm - 0.49±0.1 µm) and Vita Titankeramik (pcorrosive attack on all of ceramics at varying degrees. Conclusions The ceramics indicated for either metal-ceramic or all-ceramic

  3. Method of forming a ceramic to ceramic joint

    Science.gov (United States)

    Cutler, Raymond Ashton; Hutchings, Kent Neal; Kleinlein, Brian Paul; Carolan, Michael Francis

    2010-04-13

    A method of joining at least two sintered bodies to form a composite structure, includes: providing a joint material between joining surfaces of first and second sintered bodies; applying pressure from 1 kP to less than 5 MPa to provide an assembly; heating the assembly to a conforming temperature sufficient to allow the joint material to conform to the joining surfaces; and further heating the assembly to a joining temperature below a minimum sintering temperature of the first and second sintered bodies. The joint material includes organic component(s) and ceramic particles. The ceramic particles constitute 40-75 vol. % of the joint material, and include at least one element of the first and/or second sintered bodies. Composite structures produced by the method are also disclosed.

  4. Contributions to the R-curve behaviour of ceramic materials

    International Nuclear Information System (INIS)

    Fett, T.

    1994-12-01

    Several ceramic materials show an increase in crack growth resistance with increasing crack extension. Especially, in case of coarse-grained alumina this ''R-curve effect'' is caused by crack-face interactions in the wake of the advancing crack. Similar effects occur for whisker reinforced ceramics. Due to the crack-face interactions so-called ''bridging stresses'' are generated which transfer forces between the two crack surfaces. A second reason for an increase of crack-growth resistance are stress-induced phase transformations in zirconia ceramics with the tetragonal phase changing to the monoclinic phase. These transformations will affect the stress field in the surroundings of crack tips. The transformation generates a crack-tip transformation zone and, due to the stress balance, also residual stresses in the whole crack region which result in a residual stress intensity factor. This additional stress intensity factor is also a reason for the R-curve behaviour. In this report both effects are outlined in detail. (orig.) [de

  5. Ceramic fiber reinforced glass-ceramic matrix composite

    Science.gov (United States)

    Bansal, Narottam P. (Inventor)

    1993-01-01

    A slurry of BSAS glass powders is cast into tapes which are cut to predetermined sizes. Mats of continuous chemical vapor deposition (CVD)-SiC fibers are alternately stacked with these matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite which is heated to burn out organic constituents. The remaining interim material is then hot-pressed to form a BSAS glass-ceramic fiber-reinforced composite.

  6. Evaluation of Monolithic Ceramics and Ceramic Thermal Barrier Coatings for Diesel Engine Applications

    National Research Council Canada - National Science Library

    Swab, Jeffrey J

    2001-01-01

    The Metals and Ceramics Research Branch (MCRB) of the Weapons and Materials Research Directorate is providing ceramic material characterization and evaluation to the Tank Automotive Research, Development, and Engineering Center (TARDEC...

  7. EPR of radiation defects in lithium-oxyfluoride glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Fedotovs, A; Rogulis, U; Sarakovskis, A; Dimitrocenko, L, E-mail: andris-f@navigator.l [Institute of Solid State Physics, University of Latvia, Kengaraga st. 8, LV-1063, Riga (Latvia)

    2010-11-01

    We studied oxyfluoride composites based on lithium silicate glasses with yttrium fluorides and rare-earth dopants. The electron paramagnetic resonance (EPR) has been used to obtain information about radiation induced defects in these materials. Spectra have been measured before and after X-ray irradiation at room temperature and at liquid nitrogen temperature. Fluoride crystallites within samples were created by means of thermal treatment at specific temperatures. EPR spectra of radiation induced defects in oxyfluoride glass ceramics, in which crystallites have not been yet created, show no explicit hfs interaction of fluorine nuclei. However, in glass ceramics, which already contains fluoride crystallites, the hfs characteristic to fluorine nuclei appears in the EPR spectra. EPR hyperfine structure could be explained within a model of an F-type centre in YF{sub 3} crystalline phase.

  8. EPR of radiation defects in lithium-oxyfluoride glass ceramics

    Science.gov (United States)

    Fedotovs, A.; Rogulis, U.; Sarakovskis, A.; Dimitrocenko, L.

    2010-11-01

    We studied oxyfluoride composites based on lithium silicate glasses with yttrium fluorides and rare-earth dopants. The electron paramagnetic resonance (EPR) has been used to obtain information about radiation induced defects in these materials. Spectra have been measured before and after X-ray irradiation at room temperature and at liquid nitrogen temperature. Fluoride crystallites within samples were created by means of thermal treatment at specific temperatures. EPR spectra of radiation induced defects in oxyfluoride glass ceramics, in which crystallites have not been yet created, show no explicit hfs interaction of fluorine nuclei. However, in glass ceramics, which already contains fluoride crystallites, the hfs characteristic to fluorine nuclei appears in the EPR spectra. EPR hyperfine structure could be explained within a model of an F-type centre in YF3 crystalline phase.

  9. A fractographic study of clinically retrieved zirconia–ceramic and metal–ceramic fixed dental prostheses

    OpenAIRE

    Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

    2015-01-01

    A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia-ceramic and metal-ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia-ceramic systems occurred more frequently than those in metal-ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis

  10. Werkstoffwoche 98. Vol. 7. Symposium 9: Ceramics. Symposium 14: Simulation of ceramics

    International Nuclear Information System (INIS)

    Heinrich, J.; Ziegler, G.; Hermel, W.; Riedel, H.

    1999-01-01

    The leading subject of this proceedings volume is ceramic materials, with papers on the following subject clusters: Processing (infiltration, sintering, forming) - Physics and chemistry of ceramics (functional ceramics, SiC, ceramic precursors, microstructural properties) - Novel concepts (composites, damage induced by oxidation and mechanical stress, performance until damage under mechanical and thermal stress, layers, nanocomposites). 28 of the conference papers have been prepared for individual retrieval from the ENERGY database. (orig./CB) [de

  11. Y-TZP ceramic processing from coprecipitated powders: a comparative study with three commercial dental ceramics.

    Science.gov (United States)

    Lazar, Dolores R R; Bottino, Marco C; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H A

    2008-12-01

    (1) To synthesize 3mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. A coprecipitation route was used to synthesize a 3mol% yttria-stabilized zirconia ceramic processed by uniaxial compaction and pressureless sintering. Commercially available alumina or alumina/zirconia ceramics, namely Procera AllCeram (PA), In-Ceram Zirconia Block (CAZ) and In-Ceram Zirconia (IZ) were chosen for comparison. All specimens (6mmx5mmx5mm) were polished and ultrasonically cleaned. Qualitative phase analysis was performed by XRD and apparent densities were measured on the basis of Archimedes principle. Ceramics were also characterized using SEM, TEM and EDS. The hardness measurements were made employing Vickers hardness test. Fracture toughness (K(IC)) was calculated. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's test (alpha=0.05). ANOVA revealed that the Vickers hardness (pceramic materials composition. It was confirmed that the PA ceramic was constituted of a rhombohedral alumina matrix, so-called alpha-alumina. Both CAZ and IZ ceramics presented tetragonal zirconia and alpha-alumina mixture of phases. The SEM/EDS analysis confirmed the presence of aluminum in PA ceramic. In the IZ and CAZ ceramics aluminum, zirconium and cerium in grains involved by a second phase containing aluminum, silicon and lanthanum were identified. PA showed significantly higher mean Vickers hardness values (H(V)) (18.4+/-0.5GPa) compared to vitreous CAZ (10.3+/-0.2GPa) and IZ (10.6+/-0.4GPa) ceramics. Experimental Y-TZP showed significantly lower results than that of the other monophased ceramic (PA) (pceramics (pceramic processing conditions led to ceramics with mechanical properties comparable to commercially available reinforced ceramic materials.

  12. Salt splitting with ceramic membranes

    International Nuclear Information System (INIS)

    Kurath, D.

    1996-01-01

    The purpose of this task is to develop ceramic membrane technologies for salt splitting of radioactively contaminated sodium salt solutions. This technology has the potential to reduce the low-level waste (LLW) disposal volume, the pH and sodium hydroxide content for subsequent processing steps, the sodium content of interstitial liquid in high-level waste (HLW) sludges, and provide sodium hydroxide free of aluminum for recycle within processing plants at the DOE complex. Potential deployment sites include Hanford, Savannah River, and Idaho National Engineering Laboratory (INEL). The technical approach consists of electrochemical separation of sodium ions from the salt solution using sodium (Na) Super Ion Conductors (NaSICON). As the name implies, sodium ions are transported rapidly through these ceramic crystals even at room temperatures

  13. Ceramics: Durability and radiation effects

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, R.C.; Lutze, W. [Univ. of New Mexico, Albuquerque, NM (United States); Weber, W.J. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-05-01

    At present, there are three seriously considered options for the disposition of excess weapons plutonium: (1) incorporation, partial burn-up and direct disposal of MOX-fuel; (2) vitrification with defense waste and disposal as glass {open_quotes}logs{close_quotes}; (3) deep borehole disposal. The first two options provide a safeguard due to the high activity of fission products in the irradiated fuel and the defense waste. The latter option has only been examined in a preliminary manner, and the exact form of the plutonium has not been identified. In this paper, we review the potential for the immobilization of plutonium in highly durable crystalline ceramics apatite, pyrochlore, zirconolite, monazite and zircon. Based on available data, we propose zircon as the preferred crystalline ceramic for the permanent disposition of excess weapons plutonium.

  14. Interfaces in ceramic nuclear fuels

    International Nuclear Information System (INIS)

    Reeve, K.D.

    Internal interfaces in all-ceramic dispersion fuels (such as these for HTGRs) are discussed for two classes: BeO-based dispersions, and coated particles for graphite-based fuels. The following points are made: (1) The strength of a two-phase dispersion is controlled by the weaker dispersed phase bonded to the matrix. (2) Differential expansion between two phases can be controlled by an intermediate buffer zone of low density. (3) A thin ceramic coating should be in compression. (4) Chemical reaction between coating and substrate and mass transfer in service should be minimized. The problems of the nuclear fuel designer are to develop coatings for fission product retention, and to produce radiation-resistant interfaces. 44 references, 18 figures

  15. Silsesquioxane-derived ceramic fibres

    Science.gov (United States)

    Hurwitz, F. I.; Farmer, S. C.; Terepka, F. M.; Leonhardt, T. A.

    1991-01-01

    Fibers formed from blends of silsesquioxane polymers were characterized to study the pyrolytic conversion of these precursors to ceramics. The morphology of fibers pyrolyzed to 1400 C revealed primarily amorphous glasses whose conversion to beta-SiC is a function of both blend composition and pyrolysis conditions. Formation of beta-SiC crystallites within the glassy phase is favored by higher than stoichiometric C/Si ratios, while carbothermal reduction of Si-O bonds to form SiC with loss of SiO and CO occurs at higher methyl/phenylpropyl silsesquioxane (lower C/Si) ratios. As the carbothermal reduction is assumed to be diffusion controlled, the fibers can serve as model systems to gain understanding of the silsesquioxane pyrolysis behavior, and therefore are useful in the development of polysilsesquioxane-derived ceramic matrices and coatings as well.

  16. Microimpurity composition of superconducting ceramics

    International Nuclear Information System (INIS)

    Zhiglov, Yu.S.; Poltoratskij, Yu.B.; Protsenko, A.N.; Tuchin, O.V.

    1989-01-01

    Using laser mass spectrometry, the microimpurity composition of YBa 2 Cu 3 O 7-y superconducting ceramics, prepared by routine solid-phase synthesis from extremely pure yttrium and copper oxides and BaCO 3 , is determined. The presence of F, Na, Al, P, Cl, S, K, Ca impurities, which concentration in specimens varies within 10 -3 +5x10 -3 at.% and also Si, Sr, Fe of about 1x10 -1 at.% is established. It is difficult to determine concentrations of C, N, H 2 O impurities because of the presence of background signals of residual gases in the chamber. Using the method of Auger electron spectroscopy, a surface layer of HTSC ceramics grain is studied. The availability of chlorine impurity, which amount considerably exceeds its volume concentration, is determined in near the surface layer. 2 refs.; 2 figs

  17. Surface treatment of zirconia ceramics

    International Nuclear Information System (INIS)

    1980-01-01

    A method of chemically micropitting and/or microcratering at least a portion of a smooth surface of an impervious zirconia-base ceramic is described, comprising (a) contacting the smooth surface with a liquid leachant selected from concentrated sulphuric acid, ammonium bisulphate, alkali metal bisulphates and mixtures thereof at a temperature of at least 250 0 C for a period of time sufficient to effect micropitting and/or microcratering generally uniformly distributed throughout the microstructure of the resultant leached surface; (b) removing the leached surface from contact with the leachant; (c) contacting the leached surface with hydrochloric acid to effect removal from the leached surface of a residue thereon comprising sulphate of metal elements including zirconium in the ceramic; (d) removing the leached surface from contact with the hydrochloric acid; and (e) rinsing the leached surface with water to effect removal of acid residue from that surface. (author)

  18. Tensile Properties of Open Cell Ceramic Foams

    Czech Academy of Sciences Publication Activity Database

    Dlouhý, Ivo; Řehořek, Lukáš; Chlup, Zdeněk

    2009-01-01

    Roč. 409, - (2009), s. 168-175 ISSN 1013-9826. [Fractography of Advanced Ceramics /3./. Stará Lesná, 07.09.2008-10.09.2008] R&D Projects: GA ČR(CZ) GA106/06/0724; GA ČR GD106/05/H008 Institutional research plan: CEZ:AV0Z20410507 Keywords : tensile test * ceramics foam * open porosity * tensile strength Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  19. Acid-base properties of ceramic powders

    International Nuclear Information System (INIS)

    Bleier, A.

    1983-01-01

    This chapter addresses the fundamental aspects of potentiometric titration, electrokinetics, and conductometric titration in evaluating surface and interfacial thermodynamic behavior. Emphasizes the characterization of aqueous systems which are pertinent to the processing of ceramic powders. Attempts to clarify the role of novel analytical techniques that will increasingly contribute to the advanced characterization of ceramic powders. Evaluates recently developed acid-base and complexation concepts and their applications to the processing of oxide ceramics

  20. Structure and conductivity of nanostructured YBCO ceramics

    Science.gov (United States)

    Palchayev, D. K.; Gadzhimagomedov, S. Kh; Murlieva, Zh Kh; Rabadanov, M. Kh; Emirov, R. M.

    2017-12-01

    Superconducting nanostructured ceramics based on YBa2Cu3O7-δ were made of nanopowder obtained by burning nitrate-organic precursors. The structure, morphology, electrical resistivity, and density of ceramics were studied. Various porosity values of the ceramics were achieved by preliminary heat treatment of the nanopowder. The features of conductivity and the reason for increase of the of the superconducting transition temperature in these materials are discussed.

  1. Advanced ceramics: the present and the perspectives

    International Nuclear Information System (INIS)

    Freitas, C.T. de.

    1990-04-01

    Development in the Brazilian and international areas of advanced ceramics is described, emphasizing its economic perspectivas and industrial applications. Results obtained by national institutions are reviewed, mainly in the context of those that pioneered the required high technology in this ceramic field. The rapid growth of the interest for those special materials, made more evident by ample information related to the superconducting ceramics great pontential for important practical applications, is one of the most significant characteristics of the area. (author) [pt

  2. Piezoelectric ceramic-reinforced metal matrix composites

    OpenAIRE

    2004-01-01

    Composite materials comprising piezoelectric ceramic particulates dispersed in a metal matrix are capable of vibration damping. When the piezoelectric ceramic particulates are subjected to strain, such as the strain experienced during vibration of the material, they generate an electrical voltage that is converted into Joule heat in the surrounding metal matrix, thereby dissipating the vibrational energy. The piezoelectric ceramic particulates may also act as reinforcements to improve the mec...

  3. High temperature fracture of ceramic materials

    International Nuclear Information System (INIS)

    Wiederhorn, S.M.

    1979-01-01

    A review is presented of fracture mechanisms and methods of lifetime prediction in ceramic materials. Techniques of lifetime prediction are based on the science of fracture mechanics. Application of these techniques to structural ceramics is limited by our incomplete understanding of fracture mechanisms in these materials, and by the occurrence of flaw generation in these materials at elevated temperatures. Research on flaw generation and fracture mechanisms is recommended as a way of improving the reliability of structural ceramics

  4. Performance characteristics of porous alumina ceramic structures

    International Nuclear Information System (INIS)

    Latella, B.A.; Liu, T.

    2000-01-01

    Porous ceramics have found a wide range of applications as filters for liquids and gases. The suitability of materials for use in these types of applications depends on the microstructure (grain size, pore size and pore volume fraction) and hence the mechanical and thermal properties. In this study alumina ceramics with different levels of porosity and controlled pore sizes were fabricated and the surface damage and fracture properties were examined. Copyright (2000) The Australian Ceramic Society

  5. Strength and Microstructure of Ceramics

    Science.gov (United States)

    1989-11-01

    Forex - one particular alumina ceramic, I our own detailed crack ample, the relatively large values of r, and c* for the VI observations, and those of...particularly toughness indices, 1i71", indicating that there is sonic the c° , T parameters. However, the indentation mcth- kind of trade -o1Tbetwecn...macroscopic and microsnpic odology takes us closer to the strengths of specimens toughness levels, and that this trade -off is cont’olled by with natural

  6. Flash sintering of ceramic materials

    Science.gov (United States)

    Dancer, C. E. J.

    2016-10-01

    During flash sintering, ceramic materials can sinter to high density in a matter of seconds while subjected to electric field and elevated temperature. This process, which occurs at lower furnace temperatures and in shorter times than both conventional ceramic sintering and field-assisted methods such as spark plasma sintering, has the potential to radically reduce the power consumption required for the densification of ceramic materials. This paper reviews the experimental work on flash sintering methods carried out to date, and compares the properties of the materials obtained to those produced by conventional sintering. The flash sintering process is described for oxides of zirconium, yttrium, aluminium, tin, zinc, and titanium; silicon and boron carbide, zirconium diboride, materials for solid oxide fuel applications, ferroelectric materials, and composite materials. While experimental observations have been made on a wide range of materials, understanding of the underlying mechanisms responsible for the onset and latter stages of flash sintering is still elusive. Elements of the proposed theories to explain the observed behaviour include extensive Joule heating throughout the material causing thermal runaway, arrested by the current limitation in the power supply, and the formation of defect avalanches which rapidly and dramatically increase the sample conductivity. Undoubtedly, the flash sintering process is affected by the electric field strength, furnace temperature and current density limit, but also by microstructural features such as the presence of second phase particles or dopants and the particle size in the starting material. While further experimental work and modelling is still required to attain a full understanding capable of predicting the success of the flash sintering process in different materials, the technique non-etheless holds great potential for exceptional control of the ceramic sintering process.

  7. Metallizing of machinable glass ceramic

    International Nuclear Information System (INIS)

    Seigal, P.K.

    1976-02-01

    A satisfactory technique has been developed for metallizing Corning (Code 9658) machinable glass ceramic for brazing. Analyses of several bonding materials suitable for metallizing were made using microprobe analysis, optical metallography, and tensile strength tests. The effect of different cleaning techniques on the microstructure and the effect of various firing temperatures on the bonding interface were also investigated. A nickel paste, used for thick-film application, has been applied to obtain braze joints with strength in excess of 2000 psi

  8. Stress and Reliability Analysis of a Metal-Ceramic Dental Crown

    Science.gov (United States)

    Anusavice, Kenneth J; Sokolowski, Todd M.; Hojjatie, Barry; Nemeth, Noel N.

    1996-01-01

    Interaction of mechanical and thermal stresses with the flaws and microcracks within the ceramic region of metal-ceramic dental crowns can result in catastrophic or delayed failure of these restorations. The objective of this study was to determine the combined influence of induced functional stresses and pre-existing flaws and microcracks on the time-dependent probability of failure of a metal-ceramic molar crown. A three-dimensional finite element model of a porcelain fused-to-metal (PFM) molar crown was developed using the ANSYS finite element program. The crown consisted of a body porcelain, opaque porcelain, and a metal substrate. The model had a 300 Newton load applied perpendicular to one cusp, a load of 30ON applied at 30 degrees from the perpendicular load case, directed toward the center, and a 600 Newton vertical load. Ceramic specimens were subjected to a biaxial flexure test and the load-to-failure of each specimen was measured. The results of the finite element stress analysis and the flexure tests were incorporated in the NASA developed CARES/LIFE program to determine the Weibull and fatigue parameters and time-dependent fracture reliability of the PFM crown. CARES/LIFE calculates the time-dependent reliability of monolithic ceramic components subjected to thermomechanical and/Or proof test loading. This program is an extension of the CARES (Ceramics Analysis and Reliability Evaluation of Structures) computer program.

  9. Characterization of the alumina-zirconia ceramic system by ultrasonic velocity measurements

    International Nuclear Information System (INIS)

    Carreon, Hector; Ruiz, Alberto; Medina, Ariosto; Barrera, Gerardo; Zarate, Juan

    2009-01-01

    In this work an alumina-zirconia ceramic composites have been prepared with α-Al 2 O 3 contents from 10 to 95 wt.%. The alumina-zirconia ceramic system was characterized by means of precise ultrasonic velocity measurements. In order to find out the factors affecting the variation in wave velocity, the ceramic composite have been examined by X-ray diffraction (XRD) and (SEM) scanning electron microscopy. It was found that the ultrasonic velocity measurements changed considerably with respect to the ceramic composite composition. In particular, we studied the behavior of the physical material property hardness, an important parameter of the ceramic composite mechanical properties, with respect to the variation in the longitudinal and shear wave velocities. Shear wave velocities exhibited a stronger interaction with microstructural and sub-structural features as compared to that of longitudinal waves. In particular, this phenomena was observed for the highest α-Al 2 O 3 content composite. Interestingly, an excellent correlation between ultrasonic velocity measurements and ceramic composite hardness was observed.

  10. Energy storage in ceramic dielectrics

    International Nuclear Information System (INIS)

    Love, G.R.

    1990-01-01

    Historically, multilayer ceramic capacitors (MLC's) have not been considered for energy storage applications for two primary reasons. First, physically large ceramic capacitors were very expensive and, second, total energy density obtainable was not nearly so high as in electrolytic capacitor types. More recently, the fabrication technology for MLC's has improved significantly, permitting both significantly higher energy density and significantly lower costs. Simultaneously, in many applications, total energy storage has become smaller, and the secondary requirements of very low effective series resistance and effective series inductance (which, together, determine how efficiently the energy may be stored and recovered) have become more important. It is therefore desirable to reexamine energy storage in ceramics for contemporary commercial and near-commercial dielectrics. Stored energy is proportional to voltage squared only in the case of paraelectric insulators, because only they have capacitance that is independent of bias voltage. High dielectric constant materials, however, are ferroics (that is ferroelectric and/or antiferroelectric) and display significant variation of effective dielectric constant with bias voltage

  11. The Electrospun Ceramic Hollow Nanofibers

    Directory of Open Access Journals (Sweden)

    Shahin Homaeigohar

    2017-11-01

    Full Text Available Hollow nanofibers are largely gaining interest from the scientific community for diverse applications in the fields of sensing, energy, health, and environment. The main reasons are: their extensive surface area that increases the possibilities of engineering, their larger accessible active area, their porosity, and their sensitivity. In particular, semiconductor ceramic hollow nanofibers show greater space charge modulation depth, higher electronic transport properties, and shorter ion or electron diffusion length (e.g., for an enhanced charging–discharging rate. In this review, we discuss and introduce the latest developments of ceramic hollow nanofiber materials in terms of synthesis approaches. Particularly, electrospinning derivatives will be highlighted. The electrospun ceramic hollow nanofibers will be reviewed with respect to their most widely studied components, i.e., metal oxides. These nanostructures have been mainly suggested for energy and environmental remediation. Despite the various advantages of such one dimensional (1D nanostructures, their fabrication strategies need to be improved to increase their practical use. The domain of nanofabrication is still advancing, and its predictable shortcomings and bottlenecks must be identified and addressed. Inconsistency of the hollow nanostructure with regard to their composition and dimensions could be one of such challenges. Moreover, their poor scalability hinders their wide applicability for commercialization and industrial use.

  12. Silicate bonded ceramics of laterites

    International Nuclear Information System (INIS)

    Wagh, A.S.; Douse, V.

    1989-05-01

    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 the construction industry in the tropical countries, rich in lateritic soils and poor in energy. Also the process has all the potential for further development in arid regions abundant in limestone. (author). 6 refs, 20 figs, 3 tabs

  13. All-ceramic restorations: an overview.

    Science.gov (United States)

    Bassi, F; Carossa, S; Pera, P; Preti, G

    1998-09-01

    Advantages and disadvantages of metal-ceramic and all-ceramic restorations are reviewed particularly from the aesthetic point of view. All-ceramic restorations offer the best results because they let the light through optimally. In constructing all-ceramic crowns on teeth which have been endodontically treated, the material used to rebuild the pin-abutments must be taken into consideration if the best aesthetic results are to be achieved. Materials which, because of their translucent characteristics, are the most aesthetic alternatives to metal alloy pin-abutments in rebuilding teeth which have been endodontically treated, are then described.

  14. Performances of multi-channel ceramic photomultipliers

    International Nuclear Information System (INIS)

    Comby, G.; Karolak, M.; Piret, Y.; Mouly, J.P.

    1995-09-01

    Ceramic electron multipliers with real metal dynodes and independent channels ware constructed using multilayer ceramic technology. Tests of these prototypes show their capability to form sensitive detectors such as photomultipliers or light intensifiers. Here, we present results for the photocathode sensitivity, dynode activation, gain, linearity range and dynamic characteristics as well as the effect of 3-year aging of the main operational functions. The advantages provided by the ceramic components are discussed. These results motivate the development of a compact 256 pixel ceramic photomultiplier. (author)

  15. Ceramic technology for Advanced Heat Engines Project

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, D.R.

    1991-07-01

    Significant accomplishments in fabricating ceramic components for advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and database and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. An assessment of needs was completed, and a five year project plan was developed with extensive input from private industry. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities. This project is managed by ORNL for the Office of Transportation Technologies, Office of Transportation Materials, and is closely coordinated with complementary ceramics tasks funded by other DOE offices, NASA, DOD, and industry.

  16. Portland blended cements: demolition ceramic waste management

    International Nuclear Information System (INIS)

    Trezza, M.A.; Zito, S.; Tironi, A.; Irassar, E.F.; Rahhal, V.F.

    2017-01-01

    Demolition ceramic wastes (DCWs) were investigated in order to determine their potential use as supplementary cementitious materials in Portland Blended Cements (PBCs). For this purpose, three ceramic wastes were investigated. After characterization of the materials used, the effect of ceramic waste replacement (8, 24 and 40% by mass) was analyzed. Pozzolanic activity, hydration progress, workability and compressive strength were determined at 2, 7 and 28 days. The results showed that the ground wastes behave as filler at an early age, but as hydration progresses, the pozzolanic activity of ceramic waste contributes to the strength requirement. [es

  17. Manufacturing of superconductive silver/ceramic composites

    DEFF Research Database (Denmark)

    Seifi, Behrouz; Bech, Jakob Ilsted; Eriksen, Morten

    2000-01-01

    Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured applying the Oxide-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium, and cop......Manufacturing of superconducting metal/ceramic composites is a rather new discipline within materials forming processes. High Temperature SuperConductors, HTSC, are manufactured applying the Oxide-Powder-In-Tube process, OPIT. A ceramic powder containing lead, calcium, bismuth, strontium...

  18. Review of glass ceramic waste forms

    International Nuclear Information System (INIS)

    Rusin, J.M.

    1981-01-01

    Glass ceramics are being considered for the immobilization of nuclear wastes to obtain a waste form with improved properties relative to glasses. Improved impact resistance, decreased thermal expansion, and increased leach resistance are possible. In addition to improved properties, the spontaneous devitrification exhibited in some waste-containing glasses can be avoided by the controlled crystallization after melting in the glass-ceramic process. The majority of the glass-ceramic development for nuclear wastes has been conducted at the Hahn-Meitner Institute (HMI) in Germany. Two of their products, a celsian-based (BaAl 3 Si 2 O 8 ) and a fresnoite-based (Ba 2 TiSi 2 O 8 ) glass ceramic, have been studied at Pacific Northwest Laboratory (PNL). A basalt-based glass ceramic primarily containing diopsidic augite (CaMgSi 2 O 6 ) has been developed at PNL. This glass ceramic is of interest since it would be in near equilibrium with a basalt repository. Studies at the Power Reactor and Nuclear Fuel Development Corporation (PNC) in Japan have favored a glass-ceramic product based upon diopside (CaMgSi 2 O 6 ). Compositions, processing conditions, and product characterization of typical commercial and nuclear waste glass ceramics are discussed. In general, glass-ceramic waste forms can offer improved strength and decreased thermal expansion. Due to typcially large residual glass phases of up to 50%, there may be little improvement in leach resistance

  19. Ceramic Technology For Advanced Heat Engines Project

    Energy Technology Data Exchange (ETDEWEB)

    1990-12-01

    Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. This advanced materials technology is being developed in parallel and close coordination with the ongoing DOE and industry proof of concept engine development programs. To facilitate the rapid transfer of this technology to U.S. industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities. Abstracts prepared for appropriate papers.

  20. Tritium behaviour in ceramic breeder blankets

    International Nuclear Information System (INIS)

    Miller, J.M.

    1989-01-01

    Tritium release from the candidate ceramic materials, Li 2 O, LiA10 2 , Li 2 SiO 3 , Li 4 SiO 4 and Li 2 ZrO 3 , is being investigated in many blanket programs. Factors that affect tritium release from the ceramic into the helium sweep gas stream include operating temperature, ceramic microstructure, tritium transport and solubility in the solid. A review is presented of the material properties studied and of the irradiation programs and the results are summarized. The ceramic breeder blanket concept is briefly reviewed

  1. Emerging ceramic-based materials for dentistry.

    Science.gov (United States)

    Denry, I; Kelly, J R

    2014-12-01

    Our goal is to give an overview of a selection of emerging ceramics and issues for dental or biomedical applications, with emphasis on specific challenges associated with full-contour zirconia ceramics, and a brief synopsis on new machinable glass-ceramics and ceramic-based interpenetrating phase composites. Selected fabrication techniques relevant to dental or biomedical applications such as microwave sintering, spark plasma sintering, and additive manufacturing are also reviewed. Where appropriate, the authors have added their opinions and guidance. © International & American Associations for Dental Research.

  2. Measurement of Emissivity of Porous Ceramic Materials

    OpenAIRE

    BÜYÜKALACA, Orhan

    1998-01-01

    In this study, measurements of spectral and total emissivities of seven different porous ceramic materials and one ceramic fibre material are reported. Measurements were made for wavelength range from 1.2 µm to 20 µm and temperature range from 200 °C to 700 °C. It was found that total emissivity increases with increase of pore size but decreases with increase of temperature. The results showed all the porous ceramic materials tested to be much better than ceramic fibre in terms of total em...

  3. A review of the strength properties of dental ceramics.

    Science.gov (United States)

    Hondrum, S O

    1992-06-01

    New ceramic materials for restorative dentistry have been developed and introduced in recent years. This article reviews advantages and disadvantages of dental ceramics, concentrating on strength properties. Included are factors affecting the strength of dental ceramic materials and the most common mechanisms for increasing the strength of dental ceramics. The properties of presently available materials such as dispersion-strengthened ceramics, cast ceramics, and foil-reinforced materials are discussed. Current research efforts to improve the fracture resistance of ceramic restorative materials are reviewed. A description of methods to evaluate the strength of ceramics is included, as a caution concerning the interpretation of strength data reported in the literature.

  4. Fatigue behavior of an advanced SiC/SiC ceramic composite with a self-healing matrix at 1300 °C in air and in steam

    Energy Technology Data Exchange (ETDEWEB)

    Ruggles-Wrenn, M.B., E-mail: marina.ruggles-wrenn@afit.edu; Lee, M.D.

    2016-11-20

    The fatigue behavior of a non-oxide ceramic composite with a multilayered matrix was investigated at 1300 °C in laboratory air and in steam environment. The composite was produced via chemical vapor infiltration (CVI). The composite had an oxidation inhibited matrix, which consisted of alternating layers of silicon carbide and boron carbide and was reinforced with laminated woven Hi-Nicalon™ fibers. Fiber preforms had pyrolytic carbon fiber coating with boron carbon overlay applied. Tensile stress-strain behavior and tensile properties were evaluated at 1300 °C. Tension-tension fatigue behavior was studied for fatigue stresses ranging from 70 to 160 MPa in air and in steam. The fatigue limit (based on a run-out condition of 2×10{sup 5} cycles) was between 80 and 100 MPa. Presence of steam had little influence on fatigue performance. The retained properties of all specimens that achieved fatigue run-out were characterized. Composite microstructure, as well as damage and failure mechanisms were investigated.

  5. Development of Advanced Ceramic Manufacturing Technology; FINAL

    International Nuclear Information System (INIS)

    Pujari, V.K.

    2001-01-01

    Advanced structural ceramics are enabling materials for new transportation engine systems that have the potential for significantly reducing energy consumption and pollution in automobiles and heavy vehicles. Ceramic component reliability and performance have been demonstrated in previous U.S. DOE initiatives, but high manufacturing cost was recognized as a major barrier to commercialization. Norton Advanced Ceramics (NAC), a division of Saint-Gobain Industrial Ceramics, Inc. (SGIC), was selected to perform a major Advanced Ceramics Manufacturing Technology (ACMT) Program. The overall objectives of NAC's program were to design, develop, and demonstrate advanced manufacturing technology for the production of ceramic exhaust valves for diesel engines. The specific objectives were (1) to reduce the manufacturing cost by an order of magnitude, (2) to develop and demonstrate process capability and reproducibility, and (3) to validate ceramic valve performance, durability, and reliability. I n order to achieve these objectives, NAC, a leading U.S. advanced ceramics component manufacturer, assembled a multidisciplinary, vertically integrated team. This team included: a major diesel engine builder, Detroit Diesel Corporation (DDC); a corporate ceramics research division, SGIC's Northboro R and D Center; intelligent processing system developers, BDM Federal/MATSYS; a furnace equipment company, Centorr/Vacuum Industries; a sintering expert, Wittmer Consultants; a production OEM, Deco-Grand; a wheel manufacturer and grinding operation developer, Norton Company's Higgins Grinding Technology Center (HGTC); a ceramic machine shop, Chand Kare Technical Ceramics; and a manufacturing cost consultant, IBIS Associates. The program was divided into four major tasks: Component Design and Specification, Component Manufacturing Technology Development, Inspection and Testing, and Process Demonstration

  6. Prestresses in bilayered all-ceramic restorations.

    Science.gov (United States)

    Aboushelib, Moustafa N; Feilzer, Albert J; de Jager, Niek; Kleverlaan, Cornelis J

    2008-10-01

    A general trend in all ceramic systems is to use veneering ceramics of slightly lower thermal expansion coefficients compared with that of the framework resulting in a positive mismatch in thermal expansion coefficient (+DeltaTEC). The concept behind this TEC mismatch is to generate compressive stresses in the weaker veneering ceramic and thus enhance the overall strength of the restoration. This technique had excellent results with porcelain fused to metal restorations (PFM). However, there are concerns to apply this concept to all-ceramic restorations. The aim of this research was to determine the stresses in bilayered all-ceramic restorations due to the mismatch in TEC. Two commercial veneering ceramics with a TEC lower than that of zirconia (+DeltaTEC); NobelRondo zirconiatrade mark and Lava Ceramtrade mark, plus one experimental veneering ceramic with an identical TEC that matches that of zirconia (DeltaTEC = 0) were used to veneer zirconia discs. The specimens were loaded in biaxial flexure test setup with the veneer ceramic in tension. The stresses due to load application and TEC mismatch were calculated using fractography, engineering mathematics, and finite element analysis (FEA). In this study, the highest load at failure (64 N) was obtained with the experimental veneer where the thermal mismatch between zirconia and veneering ceramic was minimal. For the two commercial veneer ceramics the magnitude of the thermal mismatch localized at the zirconia veneer interface (42 MPa) exceeded the bond strength between the two materials and resulted in delamination failure during testing (ca. 50 MPa). For all-ceramic zirconia veneered restorations it is recommended to minimize the thermal mismatch as much as possible. (c) 2008 Wiley Periodicals, Inc.

  7. LED and Halogen Light Transmission through a CAD/CAM Lithium Disilicate Glass-Ceramic.

    Science.gov (United States)

    Pereira, Carolina Nemesio de Barros; De Magalhães, Cláudia Silami; Daleprane, Bruno; Peixoto, Rogéli Tibúrcio Ribeiro da Cunha; Ferreira, Raquel da Conceição; Cury, Luiz Alberto; Moreira, Allyson Nogueira

    2015-01-01

    The effect of thickness, shade and translucency of CAD/CAM lithium disilicate glass-ceramic on light transmission of light-emitting diode (LED) and quartz-tungsten-halogen units (QTH) were evaluated. Ceramic IPS e.max CAD shades A1, A2, A3, A3.5, high (HT) and low (LT) translucency were cut (1, 2, 3, 4 and 5 mm). Light sources emission spectra were determined. Light intensity incident and transmitted through each ceramic sample was measured to determine light transmission percentage (TP). Statistical analysis used a linear regression model. There was significant interaction between light source and ceramic translucency (p=0.008) and strong negative correlation (R=-0.845, pceramic thickness and TP. Increasing one unit in thickness led to 3.17 reduction in TP. There was no significant difference in TP (p=0.124) between shades A1 (ß1=0) and A2 (ß1=-0.45) but significant reduction occurred for A3 (ß1=-0.83) and A3.5 (ß1=-2.18). The interaction QTH/HT provided higher TP (ß1=0) than LED/HT (ß1=-2.92), QTH/LT (ß1=-3.75) and LED/LT (ß1=-5.58). Light transmission was more effective using halogen source and high-translucency ceramics, decreased as the ceramic thickness increased and was higher for the lighter shades, A1 and A2. From the regression model (R2=0.85), an equation was obtained to estimate TP value using each variable ß1 found. A maximum TP of 25% for QTH and 20% for LED was found, suggesting that ceramic light attenuation could compromise light cured and dual cure resin cements polymerization.

  8. Characterization techniques to predict mechanical behaviour of green ceramic bodies fabricated by ceramic microstereolithography

    Science.gov (United States)

    Adake, Chandrashekhar V.; Bhargava, Parag; Gandhi, Prasanna

    2018-02-01

    Ceramic microstereolithography (CMSL) has emerged as solid free form (SFF) fabrication technology in which complex ceramic parts are fabricated from ceramic suspensions which are formulated by dispersing ceramic particles in UV curable resins. Ceramic parts are fabricated by exposing ceramic suspension to computer controlled UV light which polymerizes resin to polymer and this polymer forms rigid network around ceramic particles. A 3-dimensional part is created by piling cured layers one over the other. These ceramic parts are used to build microelectromechanical (MEMS) devices after thermal treatment. In many cases green ceramic parts can be directly utilized to build MEMS devices. Hence characterization of these parts is essential in terms of their mechanical behaviour prior to their use in MEMS devices. Mechanical behaviour of these green ceramic parts depends on cross link density which in turn depends on chemical structure of monomer, concentrations of photoinitiator and UV energy dose. Mechanical behaviour can be determined with the aid of nanoindentation. And extent of crosslinking can be verified with the aid of DSC. FTIR characterization is used to analyse (-C=C-) double bond conversion. This paper explains characterization tools to predict the mechanical behaviour of green ceramic bodies fabricated in CMSL

  9. What every surgeon should know about Ceramic-on-Ceramic bearings in young patients.

    Science.gov (United States)

    Hernigou, Philippe; Roubineau, François; Bouthors, Charlie; Flouzat-Lachaniette, Charles-Henri

    2016-04-01

    Based on the exceptional tribological behaviour and on the relatively low biological activity of ceramic particles, Ceramic-on-Ceramic (CoC) total hip arthroplasty (THA) presents significant advantagesCoC bearings decrease wear and osteolysis, the cumulative long-term risk of dislocation, muscle atrophy, and head-neck taper corrosion.However, there are still concerns regarding the best technique for implantation of ceramic hips to avoid fracture, squeaking, and revision of ceramic hips with fracture of a component.We recommend that surgeons weigh the potential advantages and disadvantages of current CoC THA in comparison with other bearing surfaces when considering young very active patients who are candidates for THA. Cite this article: Hernigou P, Roubineau F, Bouthors C, Flouzat-Lachaniette C-H. What every surgeon should know about Ceramic-on-Ceramic bearings in young patients. EFORT Open Rev 2016;1:107-111. DOI: 10.1302/2058-5241.1.000027.

  10. The relationships between ceramic tool life and different machining parameters

    International Nuclear Information System (INIS)

    El-Axir, M.H.; El-Masry, A.A.; Mashal, Y.A.H.

    2001-01-01

    With the increasing use of ceramic tool materials in applications, has come an increasing need for experimental data to assign the behavior of the life of these tool materials. Experimental results during turning operation show that it is possible to increase cutting tool life substantially by a proper variation of the cutting parameters used in this work. The tool lives (tool flank wear land length) of three different ceramic materials, namely; Silicon carbide (SiC), Alumina (Al/sub 2/O/sub 3/) and partially stabilized zirconia (PSZ) in addition to, Titanium carbide and high speed steel tools are investigated in this work. Also, The effect of varying the cutting speed, feed rate and tool rake angle on tool life of each tool material is studied. The experimental work was carried out utilizing one of the experimental design techniques based on response surface methodology. It was found that the SiC cutting tool showed the highest tool life among all materials tested in this work. It was also noticed that increasing the cutting speed has led to an increase in tool life for ceramic tools only. However, increasing the feed rate and tool rake angle resulted in a reduction in tool life in all materials examined in the present study. Further analysis conducted on SiC tool material to examine the effect of the interaction of cutting parameters on the tool life. (author)

  11. Superplasticity in Fine-Grained Ceramics

    Science.gov (United States)

    1994-01-31

    Stabilized, Tetragonal Zirconia," Acta Metall. Mater., 39(12), (1991), pp. 3227-3236. 10. B. Kellett, P. Carry, and A. Mocellin , "Extrusion of Tet-ZrO2...F. Wakai, S. Sakaguchi, and H. Kato, J. Ceram. Soc. Jap., 94, 72 (1986). 8. B. Kellett, P. Carry, and A. Mocellin , J. Amer. Ceram. Soc., 74, 1922

  12. Shock wave fabricated ceramic-metal nozzles

    NARCIS (Netherlands)

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

    1999-01-01

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

  13. New ceramic materials; Nuevos materiales ceramicos

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, R.; Dominguez-Rodriguez, A.

    2010-07-01

    This article is to provide a new ceramic materials in which, with a control of their processing and thus their microstructural properties, you can get ceramic approaching ever closer to a metal, both in its structural behavior at low as at high temperatures. (Author) 30 refs.

  14. Crack growth in thermally sprayed ceramic coatings

    Czech Academy of Sciences Publication Activity Database

    Kroupa, František; Náhlík, Luboš; Knésl, Zdeněk

    2004-01-01

    Roč. 49, č. 2 (2004), s. 149-168 ISSN 0001-7043 R&D Projects: GA ČR GP106/04/P084; GA ČR GA101/03/0331 Institutional research plan: CEZ:AV0Z2043910 Keywords : ceramic coatings, fracture mechanics, crack extension Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  15. Prestresses in bilayered all-ceramic restorations

    NARCIS (Netherlands)

    Aboushelib, M.N.; Feilzer, A.J.; de Jager, N.; Kleverlaan, C.J.

    2008-01-01

    Introduction: A general trend in all ceramic systems is to use veneering ceramics of slightly lower thermal expansion coefficients compared with that of the framework resulting in a positive mismatch in thermal expansion coefficient (+ΔTEC). The concept behind this TEC mismatch is to generate

  16. Yellow cake to ceramic uranium dioxide

    International Nuclear Information System (INIS)

    Zawidzki, T.W.; Itzkovitch, I.J.

    1983-01-01

    This overview article first reviews the processes for converting uranium ore concentrates to ceramic uranium dioxide at the Port Hope Refinery of Eldorado Resources Limited. In addition, some of the problems, solutions, thoughts and research direction with respect to the production and properties of ceramic UO 2 are described

  17. Ceramics for applications in fusion systems

    International Nuclear Information System (INIS)

    Clinard, F.W. Jr.

    1979-01-01

    Six critical applications for ceramics in fusion systems are reviewed, and structural and electrical problem areas discussed. Fusion neutron radiation effects in ceramics are considered in relation to fission neutron studies. A number of candidate materials are proposed for further evaluation

  18. Synthesis of crystalline ceramics for actinide immobilisation

    International Nuclear Information System (INIS)

    Burakov, B.; Gribova, V.; Kitsay, A.; Ojovan, M.; Hyatt, N.C.; Stennett, M.C.

    2007-01-01

    Methods for the synthesis of ceramic wasteforms for the immobilization of actinides are common to those for non-radioactive ceramics: hot uniaxial pressing (HUP); hot isostatic pressing (HIP); cold pressing followed by sintering; melting (for some specific ceramics, such as garnet/perovskite composites). Synthesis of ceramics doped with radionuclides is characterized with some important considerations: all the radionuclides should be incorporated into crystalline structure of durable host-phases in the form of solid solutions and no separate phases of radionuclides should be present in the matrix of final ceramic wasteform; all procedures of starting precursor preparation and ceramic synthesis should follow safety requirements of nuclear industry. Synthesis methods that avoid the use of very high temperatures and pressures and are easily accomplished within the environment of a glove-box or hot cell are preferable. Knowledge transfer between the V. G. Khlopin Radium Institute (KRI, Russia) and Immobilisation Science Laboratory (ISL, UK) was facilitated in the framework of a joint project supported by UK Royal Society. In order to introduce methods of precursor preparation and ceramic synthesis we selected well-known procedures readily deployable in radiochemical processing plants. We accounted that training should include main types of ceramic wasteforms which are currently discussed for industrial applications. (authors)

  19. Atomic imaging and microanalysis of ceramics

    International Nuclear Information System (INIS)

    Thomas, G.; Ramesh, R.

    1988-10-01

    This paper is a short review of electron microscopy techniques, as applied to modern ceramics. Examples: representative of the significance of modern electron microscopy, methods of atomic resolution imaging, diffraction and spectroscopy in the task of characterising, and understanding typical ceramic materials are given. (JL)

  20. Oxygen diffusion in glasses and ceramic materials

    International Nuclear Information System (INIS)

    Kolitsch, A.; Richter, E.; Wolf, M.

    1978-10-01

    A survey is given on the published works to study oxygen diffusion in glasses and ceramic materials in the last years. In the first part methods are described for the measurement of oxygen diffusion coefficients and in the second part the published reports on oxygen diffusion in glasses, ceramic and other oxides are discussed. The most important results are summarized in different tables. (author)

  1. Nature of radiation damage in ceramics

    International Nuclear Information System (INIS)

    Bunch, J.M.

    1976-01-01

    Efforts to determine the equivalence between different sources of radiation damage in ceramics are reviewed. The ways in which ceramics differ from metals are examined and proposed mechanisms for creation and stabilization of defects in insulators are outlined. Work on radiation damage in crystalline oxides is summarized and suggestions for further research are offered

  2. High performance structural ceramics for nuclear industry

    International Nuclear Information System (INIS)

    Pujari, Vimal K.; Faker, Paul

    2006-01-01

    A family of Saint-Gobain structural ceramic materials and products produced by its High performance Refractory Division is described. Over the last fifty years or so, Saint-Gobain has been a leader in developing non oxide ceramic based novel materials, processes and products for application in Nuclear, Chemical, Automotive, Defense and Mining industries

  3. Synthesis and characterization of biomorphic ceramics

    International Nuclear Information System (INIS)

    Rambo, Carlos Renato

    2001-01-01

    Biotemplating represents a recently developed technology for manufacturing of biomorphous ceramics from naturally grown plant structures. This approach allows the production of ceramic materials with cellular structure, where the microstructural features of the ceramic product are similar to the native plant. After processing, the biomorphic ceramic exhibits directed pore morphology in the micrometer range. Biomorphic SiC fibers were produced from bamboo by carbothermal reduction of SiO 2 originally present in the bamboo structure. Bamboo pieces were heated up to 1500 deg C in argon to promote the reaction between carbon and silica. Biomorphic alumina, mullite and zirconia ceramics were manufactured via the sol-gel route by repeated infiltration of low viscous oxide precursors (sols) into rattan, pine and bamboo structures. The raw samples were pyrolyzed at 800 deg C in nitrogen for 1h and subsequently annealed at 1550 deg C in air. The microstructure and physical properties of the biomorphic ceramics were characterized by X-ray diffraction (XRD) and high temperature-XRD, scanning electron microscopy (SEM), porosimetry and picnometry. Thermal analysis (TGA/DTA) was performed on the infiltrated samples in order to evaluate the reactions and the total weight loss during the thermal process. The mechanical properties were evaluated by compressive strength tests. In contrast to conventional processed ceramic foam of similar porosity, the microstructure highly porous biomorphic ceramics shows uniaxial pore morphology with anisotropic properties. These properties are favorable for applications in catalyst support, filters or low-density heat insulation structures, or as biomaterials. (author)

  4. Particle-induced amorphization of complex ceramics. Final report

    International Nuclear Information System (INIS)

    Ewing, R.C.; Wang, L.M.

    1998-01-01

    The crystalline-to-amorphous (c-a) phase transition is of fundamental importance. Particle irradiations provide an important, highly controlled means of investigating this phase transformation and the structure of the amorphous state. The interaction of heavy-particles with ceramics is complex because these materials have a wide range of structure types, complex compositions, and because chemical bonding is variable. Radiation damage and annealing can produce diverse results, but most commonly, single crystals become aperiodic or break down into a polycrystalline aggregate. The authors continued the studies of the transition from the periodic-to-aperiodic state in natural materials that have been damaged by α-recoil nuclei in the uranium and thorium decay series and in synthetic, analogous structures. The transition from the periodic to aperiodic state was followed by detailed x-ray diffraction analysis, in-situ irradiation/transmission electron microscopy, high resolution transmission electron microscopy, extended x-ray absorption fine structure spectroscopy/x-ray absorption near edge spectroscopy and other spectroscopic techniques. These studies were completed in conjunction with bulk irradiations that can be completed at Los Alamos National Laboratory or Sandia National Laboratories. Principal questions addressed in this research program included: (1) What is the process at the atomic level by which a ceramic material is transformed into a disordered or aperiodic state? (2) What are the controlling effects of structural topology, bond-type, dose rate, and irradiation temperature on the final state of the irradiated material? (3) What is the structure of the damaged material? (4) What are the mechanisms and kinetics for the annealing of interstitial and aggregate defects in these irradiated ceramic materials? (5) What general criteria may be applied to the prediction of amorphization in complex ceramics?

  5. FY2015 ceramic fuels development annual highlights

    Energy Technology Data Exchange (ETDEWEB)

    Mcclellan, Kenneth James [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

    2015-09-22

    Key challenges for the Advanced Fuels Campaign are the development of fuel technologies to enable major increases in fuel performance (safety, reliability, power and burnup) beyond current technologies, and development of characterization methods and predictive fuel performance models to enable more efficient development and licensing of advanced fuels. Ceramic fuel development activities for fiscal year 2015 fell within the areas of 1) National and International Technical Integration, 2) Advanced Accident Tolerant Ceramic Fuel Development, 3) Advanced Techniques and Reference Materials Development, and 4) Fabrication of Enriched Ceramic Fuels. High uranium density fuels were the focus of the ceramic fuels efforts. Accomplishments for FY15 primarily reflect the prioritization of identification and assessment of new ceramic fuels for light water reactors which have enhanced accident tolerance while also maintaining or improving normal operation performance, and exploration of advanced post irradiation examination techniques which will support more efficient testing and qualification of new fuel systems.

  6. Light scattering in glass-ceramics

    International Nuclear Information System (INIS)

    Hendy, S.C.

    2002-01-01

    Full text: Glass-ceramic materials with microstructures comprised of dispersed nanocrystallites in a residual glass matrix show promise for many new technological applications. In particular, transparent glass-ceramics offer low thermal expansion and stability, in addition to the prospect of novel non-linear optical properties that can arise from the nanocrystallites. Good transparency requires low optical scattering and low atomic absorption. Light scattering in the glass-ceramic arises primarily from the glass-crystallite interface. The attenuation due to scattering (turbidity) will depend upon the difference in refractive index of the two phases and the size and distribution of nanocrystallites in the glass. Here we consider models of glass-ceramic structure formation and look at scattering in these model structures to increase our understanding of the transparency of glass-ceramics

  7. Polymer and ceramic nanocomposites for aerospace applications

    Science.gov (United States)

    Rathod, Vivek T.; Kumar, Jayanth S.; Jain, Anjana

    2017-11-01

    This paper reviews the potential of polymer and ceramic matrix composites for aerospace/space vehicle applications. Special, unique and multifunctional properties arising due to the dispersion of nanoparticles in ceramic and metal matrix are briefly discussed followed by a classification of resulting aerospace applications. The paper presents polymer matrix composites comprising majority of aerospace applications in structures, coating, tribology, structural health monitoring, electromagnetic shielding and shape memory applications. The capabilities of the ceramic matrix nanocomposites to providing the electromagnetic shielding for aircrafts and better tribological properties to suit space environments are discussed. Structural health monitoring capability of ceramic matrix nanocomposite is also discussed. The properties of resulting nanocomposite material with its disadvantages like cost and processing difficulties are discussed. The paper concludes after the discussion of the possible future perspectives and challenges in implementation and further development of polymer and ceramic nanocomposite materials.

  8. Ceramic Technology for Advanced Heat Engines Project

    Energy Technology Data Exchange (ETDEWEB)

    1989-08-01

    The Ceramic Technology for Advanced Heat Engines Project was developed by the Department of Energy's Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Advanced Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DoD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially.

  9. FY2016 Ceramic Fuels Development Annual Highlights

    Energy Technology Data Exchange (ETDEWEB)

    Mcclellan, Kenneth James [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-01-24

    Key challenges for the Advanced Fuels Campaign are the development of fuel technologies to enable major increases in fuel performance (safety, reliability, power and burnup) beyond current technologies, and development of characterization methods and predictive fuel performance models to enable more efficient development and licensing of advanced fuels. Ceramic fuel development activities for fiscal year 2016 fell within the areas of 1) National and International Technical Integration, 2) Advanced Accident Tolerant Ceramic Fuel Development, 3) Advanced Techniques and Reference Materials Development, and 4) Fabrication of Enriched Ceramic Fuels. High uranium density fuels were the focus of the ceramic fuels efforts. Accomplishments for FY16 primarily reflect the prioritization of identification and assessment of new ceramic fuels for light water reactors which have enhanced accident tolerance while also maintaining or improving normal operation performance, and exploration of advanced post irradiation examination techniques which will support more efficient testing and qualification of new fuel systems.

  10. Fluorescence of ceramic color standards

    International Nuclear Information System (INIS)

    Koo, Annette; Clare, John F.; Nield, Kathryn M.; Deadman, Andrew; Usadi, Eric

    2010-01-01

    Fluorescence has been found in color standards available for use in calibration and verification of color measuring instruments. The fluorescence is excited at wavelengths below about 600 nm and emitted above 700 nm, within the response range of silicon photodiodes, but at the edge of the response of most photomultipliers and outside the range commonly scanned in commercial colorimeters. The degree of fluorescence on two of a set of 12 glossy ceramic tiles is enough to introduce significant error when those tiles have been calibrated in one mode of measurement and are used in another. We report the nature of the fluorescence and the implications for color measurement.

  11. Ceramics for Turbine Engine Applications.

    Science.gov (United States)

    1980-03-01

    permet de travailler en compression. 2 - LES TURBINES CONTRAROTATIVES Connues depuis plus de 50 ans dsns lea turbines A vapeur (A grilles radiales) lea...AD-AO87 594 ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT--ETC F/6 11/2 CERAMICS FOR TURBINE ENGINE APPICATIONS.(U) MAR 8G H M GURTE, J...for Turbine Engine Applications ( X.,, ~LAJ DISTRIBUTION AND AVAILABILITY Ths ai’-t~ ~ru O ACK COVER forp"~ ~So’ 8 6 0 40 NORTH ATLANTIC TREATY

  12. Building ceramic based on sludge

    International Nuclear Information System (INIS)

    Szöke, A-M; Muntean, M; Dumitrescu, O; Bartalis, I

    2013-01-01

    Because of the rapid evolution in the last decade of science and engineering materials, development of new advanced materials, particularly in construction, we must find solutions, namely, new performed materials, with functional and aesthetic qualities. In recent years, there have been made alternative attempts to reuse various types of wastes, including the incorporation of products in ceramic clay. This theme concerning the achievement of some durable, economic and ecological materials represents a high-level preoccupation in this domain, the problems related to the ecosystem being permanent issues of the century

  13. Fibrous-Ceramic/Aerogel Composite Insulating Tiles

    Science.gov (United States)

    White, Susan M.; Rasky, Daniel J.

    2004-01-01

    Fibrous-ceramic/aerogel composite tiles have been invented to afford combinations of thermal-insulation and mechanical properties superior to those attainable by making tiles of fibrous ceramics alone or aerogels alone. These lightweight tiles can be tailored to a variety of applications that range from insulating cryogenic tanks to protecting spacecraft against re-entry heating. The advantages and disadvantages of fibrous ceramics and aerogels can be summarized as follows: Tiles made of ceramic fibers are known for mechanical strength, toughness, and machinability. Fibrous ceramic tiles are highly effective as thermal insulators in a vacuum. However, undesirably, the porosity of these materials makes them permeable by gases, so that in the presence of air or other gases, convection and gas-phase conduction contribute to the effective thermal conductivity of the tiles. Other disadvantages of the porosity and permeability of fibrous ceramic tiles arise because gases (e.g., water vapor or cryogenic gases) can condense in pores. This condensation contributes to weight, and in the case of cryogenic systems, the heat of condensation undesirably adds to the heat flowing to the objects that one seeks to keep cold. Moreover, there is a risk of explosion associated with vaporization of previously condensed gas upon reheating. Aerogels offer low permeability, low density, and low thermal conductivity, but are mechanically fragile. The basic idea of the present invention is to exploit the best features of fibrous ceramic tiles and aerogels. In a composite tile according to the invention, the fibrous ceramic serves as a matrix that mechanically supports the aerogel, while the aerogel serves as a low-conductivity, low-permeability filling that closes what would otherwise be the open pores of the fibrous ceramic. Because the aerogel eliminates or at least suppresses permeation by gas, gas-phase conduction, and convection, the thermal conductivity of such a composite even at

  14. Ceramic Technology for Advanced Heat Engines Project

    Energy Technology Data Exchange (ETDEWEB)

    1990-08-01

    The Ceramic Technology For Advanced Heat Engines Project was developed by the Department of Energy's Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Advanced Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), and Department of Defense (DOD) advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. However, these programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. An assessment of needs was completed, and a five year project plan was developed with extensive input from private industry. The objective of the project is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on structural ceramics for advanced gas turbine and diesel engines, ceramic hearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines.

  15. A fractographic study of clinically retrieved zirconia–ceramic and metal–ceramic fixed dental prostheses

    Science.gov (United States)

    Pang, Zhen; Chughtai, Asima; Sailer, Irena; Zhang, Yu

    2015-01-01

    Objectives A recent 3-year randomized controlled trial (RCT) of tooth supported three- to five-unit zirconia–ceramic and metal–ceramic posterior fixed dental prostheses (FDPs) revealed that veneer chipping and fracture in zirconia–ceramic systems occurred more frequently than those in metal–ceramic systems [1]. This study seeks to elucidate the underlying mechanisms responsible for the fracture phenomena observed in this RCT using a descriptive fractographic analysis. Methods Vinyl-polysiloxane impressions of 12 zirconia–ceramic and 6 metal–ceramic FDPs with veneer fractures were taken from the patients at the end of a mean observation of 40.3 ± 2.8 months. Epoxy replicas were produced from these impressions [1]. All replicas were gold coated, and inspected under the optical microscope and scanning electron microscope (SEM) for descriptive fractography. Results Among the 12 zirconia–ceramic FDPs, 2 had small chippings, 9 had large chippings, and 1 exhibited delamination. Out of 6 metal–ceramic FDPs, 5 had small chippings and 1 had large chipping. Descriptive fractographic analysis based on SEM observations revealed that fracture initiated from the wear facet at the occlusal surface in all cases, irrespective of the type of restoration. Significance Zirconia–ceramic and metal–ceramic FDPs all fractured from microcracks that emanated from occlusal wear facets. The relatively low fracture toughness and high residual tensile stress in porcelain veneer of zirconia restorations may contribute to the higher chipping rate and larger chip size in zirconia–ceramic FDPs relative to their metal–ceramic counterparts. The low veneer/core interfacial fracture energy of porcelain-veneered zirconia may result in the occurrence of delamination in zirconia–ceramic FDPs. PMID:26233469

  16. Factors affecting the shear bond strength of metal and ceramic brackets bonded to different ceramic surfaces.

    Science.gov (United States)

    Abu Alhaija, Elham S J; Abu AlReesh, Issam A; AlWahadni, Ahed M S

    2010-06-01

    The aims of this study were to evaluate the shear bond strength (SBS) of metal and ceramic brackets bonded to two different all-ceramic crowns, IPS Empress 2 and In-Ceram Alumina, to compare the SBS between hydrofluoric acid (HFA), phosphoric acid etched, and sandblasted, non-etched all-ceramic surfaces. Ninety-six all-ceramic crowns were fabricated resembling a maxillary left first premolar. The crowns were divided into eight groups: (1) metal brackets bonded to sandblasted 9.6 per cent HFA-etched IPS Empress 2 crowns; (2) metal brackets bonded to sandblasted 9.6 per cent HFA-etched In-Ceram crowns; (3) ceramic brackets bonded to sandblasted 9.6 per cent HFA-etched IPS Empress 2 crowns; (4) ceramic brackets bonded to sandblasted 9.6 per cent HFA-etched In-Ceram crowns; (5) metal brackets bonded to sandblasted 37 per cent phosphoric acid-etched IPS Empress 2 crowns; (6) metal brackets bonded to sandblasted 37 per cent phosphoric acid-etched In-Ceram crowns; (7) metal brackets bonded to sandblasted, non-etched IPS Empress 2 crowns; and (8) metal brackets bonded to sandblasted, non-etched In-Ceram crowns. Metal and ceramic orthodontic brackets were bonded using a conventional light polymerizing adhesive resin. An Instron universal testing machine was used to determine the SBS at a crosshead speed of 0.1 mm/minute. Comparison between groups was performed using a univariate general linear model and chi-squared tests. The highest mean SBS was found in group 3 (120.15 +/- 45.05 N) and the lowest in group 8 (57.86 +/- 26.20 N). Of all the variables studied, surface treatment was the only factor that significantly affected SBS (P Empress 2 and In-Ceram groups.

  17. Pressure brazing of ceramics to metals with copper solder

    International Nuclear Information System (INIS)

    Pavlova, M.A.; Metelkin, I.I.

    1986-01-01

    The effect on the quality of joints brazed with copper of different non metallized aluminooxide dielectrics with metals and alloys of a series of technological parameters (temperature, pressure, holding, and medium) in the course of pressure brazing is investigated. It is shown that in case of brazing with kovar and nickel the character of dependences is identical, however in all cases the joints with nickel are more durable. For the ceramics - molybdenum system characterized by weak interaction with copper solder kinetic dependences have no maximum and only under holding of more than 20 min the constant strength of 150-190 MPa is attained

  18. Steam Explosions in Slurry-fed Ceramic Melters

    Energy Technology Data Exchange (ETDEWEB)

    Carter, J.T.

    2001-03-28

    This report assesses the potential and consequences of a steam explosion in Slurry Feed Ceramic Melters (SFCM). The principles that determine if an interaction is realistically probable within a SFCM are established. Also considered are the mitigating effects due to dissolved, non-condensable gas(es) and suspended solids within the slurry feed, radiation, high glass viscosity, and the existence of a cold cap. The report finds that, even if any explosion were to occur, however, it would not be large enough to compromise vessel integrity.

  19. Radiopaque strontium fluoroapatite glass-ceramics

    Directory of Open Access Journals (Sweden)

    Wolfram eHöland

    2015-10-01

    Full Text Available The controlled precipitation of strontium fluoroapatite crystals, was studied in four base glass compositions derived from the SiO2 – Al2O3 – Y2O3 – SrO – Na2O – K2O/Rb2O/Cs2O – P2O5 – F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: a Sr5(PO43F – leucite, KAlSi2O6 , b Sr5(PO43F – leucite, KAlSi2O6, and nano-sized NaSrPO4 c Sr5(PO43F – pollucite, CsAlSiO4 , and nano-sized NaSrPO4, d Sr5(PO43F – Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4.The proof of crystal phase formation was possible by X-ray diffraction (XRD. The microstructures, which were studied using scanning electron microscopy (SEM demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needlelike morphology. The study of the crystal growth of needlelike Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism.The formation of leucite, pollucite and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite – pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal

  20. Glass ceramic seals to inconel

    Science.gov (United States)

    McCollister, Howard L.; Reed, Scott T.

    1983-11-08

    A glass ceramic composition prepared by subjecting a glass composition comprising, by weight, 65-80% SiO.sub.2, 8-16%, Li.sub.2 O, 2-8% , Al.sub.2 O.sub.3, 1-8% K.sub.2 O, 1-5% P.sub.2 O.sub.5 and 1.5-7% B.sub.2 O.sub.3, to the following processing steps of heating the glass composition to a temperature sufficient to crystallize lithium metasilicate therein, holding the glass composition at a temperature and for a time period sufficient to dissolve the lithium metasilicate therein thereby creating cristobalite nucleii, cooling the glass composition and maintaining the composition at a temperature and for a time period sufficient to recrystallize lithium metasilicate therein, and thermally treating the glass composition at a temperature and for a time period sufficient to cause growth of cristobalite and further crystallization of lithium metasilicate producing a glass ceramic composition having a specific thermal expansion coefficient and products containing said composition.

  1. Method for producing ceramic bodies

    International Nuclear Information System (INIS)

    Prunier, A.R. Jr.; Spangenberg, S.F.; Wijeyesekera, S.

    1992-01-01

    This patent describes a method for preparing a superconducting ceramic article. It comprises heating a powdered admixture comprising a source of yttria (Y 2 O 3 ), a source of barium monoxide and a source of cupric oxide to a temperature of from about 800 degrees Centigrade to 900 degrees Centigrade to allow the admixture to be densified under pressure to more than about 65 percent of the admixture's theoretical density but low enough to substantially preclude melting of the admixture; applying to the heated admixture isostatic pressure of between about 80,000 psi (5.5 x 10 2 MPa) and about the fracture stress of the heated admixture, for a period of time of from about 0.1 second to about ten minutes to form a densified article with a density of more than about 65 percent of the admixture's theoretical density; and annealing the densified article in the presence of gaseous oxygen under conditions sufficient to convert the densified article to a superconducting ceramic article having a composition comprising YBa 2 Cu 3 O 7 - x where O < x < 0.6

  2. Ceramics like PZT-PMN

    International Nuclear Information System (INIS)

    Droescher, R.E.; Sousa, V.C.; Bergman, C.P.

    2009-01-01

    The goal of this work was to achieve piezoelectric ceramics referring to the system PZT-PMN Pb(Mg 1 / 3 Nb 2 / 3 Zr 0 , 52 Ti 0 , 48 )O 3 . Have been analysed ceramics like 0,65PZT-0,35PMN ((Pb(Mg 0 , 1167 Nb 0 , 2300 Zr 0 , 3380 Ti 0 , 3120 )O 3 ), 0,75PZT-0,25PMN ((Pb(Mg 0 , 083 Nb 0 . 1675 Zr 0 , 3900 Ti 0 , 3600 )O3) and the 0,85PZT-0,15PMN ((Pb(Mg 0,0500 Nb 0 , 1000 Zr 0 , 4420 Ti 0 , 4080 )O 3 ). The influence of the calcination and concentration of PZT on the lattice phases, microstructure and density was evaluated. Then, the method used was the mixed-oxide method, the samples were taken under different temperatures of calcination before the final sinterizing. The DRX and SEM techniques were used to identify the phases formed and analyse the microstructure, respectively. The main result revealed that, the better way is to realize three burns before the final sinterizing at 1200 o C/4 h . Like that, on obtain for sure the average lattice phases, like: perovskite, pyrochlore and PbO and also tend to densify the samples. (author)

  3. Thermomechanical and Environmental Durability of Environmental Barrier Coated Ceramic Matrix Composites Under Thermal Gradients

    Science.gov (United States)

    Zhu, Dongming; Bhatt, Ramakrishna T.; Harder, Bryan

    2016-01-01

    This paper presents the developments of thermo-mechanical testing approaches and durability performance of environmental barrier coatings (EBCs) and EBC coated SiCSiC ceramic matrix composites (CMCs). Critical testing aspects of the CMCs will be described, including state of the art instrumentations such as temperature, thermal gradient, and full field strain measurements; materials thermal conductivity evolutions and thermal stress resistance; NDE methods; thermo-mechanical stress and environment interactions associated damage accumulations. Examples are also given for testing ceramic matrix composite sub-elements and small airfoils to help better understand the critical and complex CMC and EBC properties in engine relevant testing environments.

  4. Ceramic materials on perovskite-type structure for electronic applications

    International Nuclear Information System (INIS)

    Surowiak, Z.

    2003-01-01

    Ceramic materials exhibiting the perovskite-type structure constitute among others, resource base for many fields of widely understood electronics (i.e., piezoelectronics, accustoelectronics, optoelectronics, computer science, tele- and radioelectronics etc.). Most often they are used for fabrication of different type sensors (detectors), transducers, ferroelectric memories, limiters of the electronic current intensity, etc., and hence they are numbered among so-called intelligent materials. Prototype structure of this group of materials is the structure of the mineral called perovskite (CaTiO 3 ). By means of right choice of the chemical composition of ABO 3 and deforming the regular perovskite structure (m3m) more than 5000 different chemical compounds and solid solutions exhibiting the perovskite-type structure have been fabricated. The concept of perovskite functional ceramics among often things ferroelectric ceramics, pyroelectric ceramics, piezoelectric ceramics, electrostrictive ceramics, posistor ceramics, superconductive ceramics and ferromagnetic ceramics. New possibilities of application of the perovskite-type ceramics are opened by nanotechnology. (author)

  5. Ultrahigh piezoelectricity in ferroelectric ceramics by design

    Science.gov (United States)

    Li, Fei; Lin, Dabin; Chen, Zibin; Cheng, Zhenxiang; Wang, Jianli; Li, ChunChun; Xu, Zhuo; Huang, Qianwei; Liao, Xiaozhou; Chen, Long-Qing; Shrout, Thomas R.; Zhang, Shujun

    2018-03-01

    Piezoelectric materials, which respond mechanically to applied electric field and vice versa, are essential for electromechanical transducers. Previous theoretical analyses have shown that high piezoelectricity in perovskite oxides is associated with a flat thermodynamic energy landscape connecting two or more ferroelectric phases. Here, guided by phenomenological theories and phase-field simulations, we propose an alternative design strategy to commonly used morphotropic phase boundaries to further flatten the energy landscape, by judiciously introducing local structural heterogeneity to manipulate interfacial energies (that is, extra interaction energies, such as electrostatic and elastic energies associated with the interfaces). To validate this, we synthesize rare-earth-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), as rare-earth dopants tend to change the local structure of Pb-based perovskite ferroelectrics. We achieve ultrahigh piezoelectric coefficients d33 of up to 1,500 pC N-1 and dielectric permittivity ɛ33/ɛ0 above 13,000 in a Sm-doped PMN-PT ceramic with a Curie temperature of 89 °C. Our research provides a new paradigm for designing material properties through engineering local structural heterogeneity, expected to benefit a wide range of functional materials.

  6. Randomized, Controlled Clinical Trial of Bilayer Ceramic and Metal-Ceramic Crown Performance

    Science.gov (United States)

    Esquivel-Upshaw, Josephine; Rose, William; Oliveira, Erica; Yang, Mark; Clark, Arthur E.; Anusavice, Kenneth

    2013-01-01

    Purpose Analyzing the clinical performance of restorative materials is important, as there is an expectation that these materials and procedures will restore teeth and do no harm. The objective of this research study was to characterize the clinical performance of metal-ceramic crowns, core ceramic crowns, and core ceramic/veneer ceramic crowns based on 11 clinical criteria. Materials and Methods An IRB-approved, randomized, controlled clinical trial was conducted as a single-blind pilot study. The following three types of full crowns were fabricated: (1) metal-ceramic crown (MC) made from a Pd-Au-Ag-Sn-In alloy (Argedent 62) and a glass-ceramic veneer (IPS d.SIGN veneer); (2) non-veneered (glazed) lithium disilicate glass-ceramic crown (LDC) (IPS e.max Press core and e.max Ceram Glaze); and (3) veneered lithia disilicate glass-ceramic crown (LDC/V) with glass-ceramic veneer (IPS Empress 2 core and IPS Eris). Single-unit crowns were randomly assigned. Patients were recalled for each of 3 years and were evaluated by two calibrated clinicians. Thirty-six crowns were placed in 31 patients. A total of 12 crowns of each of the three crown types were studied. Eleven criteria were evaluated: tissue health, marginal integrity, secondary caries, proximal contact, anatomic contour, occlusion, surface texture, cracks/chips (fractures), color match, tooth sensitivity, and wear (of crowns and opposing enamel). Numerical rankings ranged from 1 to 4, with 4 being excellent, and 1 indicating a need for immediate replacement. Statistical analysis of the numerical rankings was performed using a Fisher’s exact test. Results There was no statistically significant difference between performance of the core ceramic crowns and the two veneered crowns at year 1 and year 2 (p > 0.05). All crowns were rated either as excellent or good for each of the clinical criteria; however, between years 2 and 3, gradual roughening of the occlusal surface occurred in some of the ceramic-ceramic crowns

  7. Influence of light curing unit and ceramic thickness on temperature rise during resin cement photo-activation.

    Science.gov (United States)

    Guiraldo, Ricardo Danil; Consani, Simonides; Mastrofrancisco, Sarina; Consani, Rafael Leonardo Xediek; Sinhoreti, Mario Alexandre Coelho; Correr-Sobrinho, Lourenço

    2008-11-01

    The aim of this study was to determine the effect of different ceramic thickness on heat generation during resin cement photo-activation by QTH (quartz-tungsten-halogen), LED (light emitting diode), and PAC (plasma arc-curing) LCUs (light curing units). The resin cement used was Rely X ARC (3M-ESPE), and the ceramic was IPS Empress Esthetic (Ivoclar-Vivadent), of which 0.7-, 1.4- and 2.0-mm thick disks, 0.8 mm in diameter were made. Temperature increase was recorded with a type-K thermocouple connected to a digital thermometer (Iopetherm 46). An acrylic resin base was built to guide the thermocouple and support the 1.0-mm thick dentin disk. A 0.1-mm thick black adhesive paper matrix with a perforation 6 mm in diameter was placed on the dentin to contain the resin cement and support the ceramic disks of different thicknesses. Three LCUs were used: QTH, LED and PAC. Nine groups were formed (n=10) according to the interaction: 3 ceramic thicknesses, 1 resin cement and 3 photo-activation methods. Temperature increase data were submitted to Tukey's test (5%). For all ceramic thicknesses, a statistically significant difference in temperature increase was observed among the LCUs, with the highest mean value for the QTH LCU (p0.05). The interaction of higher energy density with smaller ceramic thickness showed higher temperature increase values.

  8. Ceramic restoration repair: report of two cases

    Directory of Open Access Journals (Sweden)

    Luís Henrique Araújo Raposo

    2009-04-01

    Full Text Available The esthetic and functional rehabilitation of patients with multiple missing teeth can be performed with several techniques and materials. Ceramic restorations provide reliable masticatory function and good esthetics. However, fracture can occur in some cases due to their brittle behavior. In some cases, the replacement of an extensive prosthesis is a problem due to the high treatment cost. In this paper, two cases are presented, in which fractures occurred in extensive metal-ceramic fixed partial dentures, and their replacement was not possible. Ceramic repair was chosen and the sequences of treatment with and without presence of the ceramic fragment are also discussed. The cases illustrate that, in some situations, fractured metal-ceramic partial dentures can be successfully repaired when prosthetic replacement is not a choice. Prosthodontists must use alternatives that allow a reliable repair to extensive metal-ceramic fixed partial dentures. Surface preparation of the ceramic with hydrofluoric acid in conjunction with a silane coupling agent is essential for a predictable bonding of composite resin. The repair performed with composite resin is an esthetic and functional alternative when extensive fixed partial dentures cannot be replaced.

  9. High-temperature materials and structural ceramics

    International Nuclear Information System (INIS)

    1990-01-01

    This report gives a survey of research work in the area of high-temperature materials and structural ceramics of the KFA (Juelich Nuclear Research Center). The following topics are treated: (1) For energy facilities: ODS materials for gas turbine blades and heat exchangers; assessment of the remaining life of main steam pipes, material characterization and material stress limits for First-Wall components; metallic and graphitic materials for high-temperature reactors. (2) For process engineering plants: composites for reformer tubes and cracking tubes; ceramic/ceramic joints and metal/ceramic and metal/metal joints; Composites and alloys for rolling bearing and sliding systems up to application temperatures of 1000deg C; high-temperature corrosion of metal and ceramic material; porous ceramic high-temperature filters and moulding coat-mix techniques; electrically conducting ceramic material (superconductors, fuel cells, solid electrolytes); high-temperature light sources (high-temperature chemistry); oil vapor engines with caramic components; ODS materials for components in diesel engines and vehicle gas turbines. (MM) [de

  10. Microcracking in ceramics and acoustic emission

    International Nuclear Information System (INIS)

    Subbarao, E.C.

    1991-01-01

    One of the limitations in the use of ceramics in critical applications is due to the presence of microcracks, which may arise from differential thermal expansion and phase changes, among others. Acoustic emission signals occur when there are abrupt microdeformations in a material and thus offer a convenient means of non-destructive detection of microcracking. Examples of a study of acoustic emission from microcracking due to anisotropic thermal expansion in low thermal expansion single phase ceramics such as niobia and sodium zirconium phosphate ceramics and due to phase changes in zirconia and superconducting YBa 2 Cu 3 Osub(7-x) ceramics are presented, together with the case of lead titanate ceramics, which exhibits both a phase change (paraelectric to ferroelectric) and an anisotropic thermal expansion. The role of grain size on the extent of microcracking is illustrated in the case of niobia ceramics. Some indirect evidence of healing of microcracks on heating niobia and lead titanate ceramics is presented from the acoustic emission results. (author). 69 refs., 9 figs

  11. Effect of surface acid etching on the biaxial flexural strength of two hot-pressed glass ceramics.

    Science.gov (United States)

    Hooshmand, Tabassom; Parvizi, Shaghayegh; Keshvad, Alireza

    2008-07-01

    The purpose of this study was to assess the effect of surface acid etching on the biaxial flexural strength of two hot-pressed glass ceramics reinforced by leucite or lithium disilicate crystals. Forty glass ceramic disks (14-mm diameter, 2-mm thick) consisting of 20 leucite-based ceramic disks (IPS Empress) and 20 lithia disilicate-based ceramic (IPS Empress 2) were produced by hot-pressing technique. All specimens were polished and then cleaned ultrasonically in distilled water. Ten specimens of each ceramic group were then etched with 9% hydrofluoric (HF) acid gel for 2 minutes and cleaned ultrasonically again. The biaxial flexural strength was measured by the piston-on-three-ball test in a universal testing machine. Data based on ten specimens in each group were analyzed by two-way ANOVA (alpha= 0.05). Microstructure of ceramic surfaces before and after acid etching was also examined by a scanning electron microscope. The mean biaxial flexural strength values for each group tested were (in MPa): nonetched IPS Empress = 118.6 +/- 25.5; etched IPS Empress = 102.9 +/- 15.4; nonetched IPS Empress 2 = 283.0 +/- 48.5; and etched IPS Empress 2 = 250.6 +/- 34.6. The results showed that the etching process reduced the biaxial flexural strengths significantly for both ceramic types (p= 0.025). No significant interaction between the ceramic type and etching process was found (p= 0.407). From the results, it was concluded that surface HF acid etching could have a weakening effect on hot-pressed leucite or lithia disilicate-based glass ceramic systems.

  12. Microstructural and Wear Behavior Characterization of Porous Layers Produced by Pulsed Laser Irradiation in Glass-Ceramics Substrates.

    Science.gov (United States)

    Sola, Daniel; Conde, Ana; García, Iñaki; Gracia-Escosa, Elena; de Damborenea, Juan J; Peña, Jose I

    2013-09-09

    In this work, wear behavior and microstructural characterization of porous layers produced in glass-ceramic substrates by pulsed laser irradiation in the nanosecond range are studied under unidirectional sliding conditions against AISI316 and corundum counterbodies. Depending on the optical configuration of the laser beam and on the working parameters, the local temperature and pressure applied over the interaction zone can generate a porous glass-ceramic layer. Material transference from the ball to the porous glass-ceramic layer was observed in the wear tests carried out against the AISI316 ball counterface whereas, in the case of the corundum ball, the wear volume loss was concentrated in the porous layer. Wear rate and friction coefficient presented higher values than expected for dense glass-ceramics.

  13. Microstructural and Wear Behavior Characterization of Porous Layers Produced by Pulsed Laser Irradiation in Glass-Ceramics Substrates

    Directory of Open Access Journals (Sweden)

    Jose I. Peña

    2013-09-01

    Full Text Available In this work, wear behavior and microstructural characterization of porous layers produced in glass-ceramic substrates by pulsed laser irradiation in the nanosecond range are studied under unidirectional sliding conditions against AISI316 and corundum counterbodies. Depending on the optical configuration of the laser beam and on the working parameters, the local temperature and pressure applied over the interaction zone can generate a porous glass-ceramic layer. Material transference from the ball to the porous glass-ceramic layer was observed in the wear tests carried out against the AISI316 ball counterface whereas, in the case of the corundum ball, the wear volume loss was concentrated in the porous layer. Wear rate and friction coefficient presented higher values than expected for dense glass-ceramics.

  14. Characterization and evaluation of ceramic properties of clay used in structural ceramics

    International Nuclear Information System (INIS)

    Reis, A.S.; Oliveira, J.N.; Della-Sagrillo, V.P.; Valenzuela-Diaz, F.R.

    2014-01-01

    The clay used in the manufacture of structural ceramic products must meet quality requirements that are influenced by their chemical, physical, mineralogical and microstructural characteristics, which control the ceramic properties of the final products. This paper aims to characterize the clay used in the manufacture of ceramic roof tiles and bricks. The clay was characterized through XRF, XRD, thermogravimetry and differential thermal analysis, Atterberg limits and particle size distribution. Specimens were shaped, dried at 110°C, and burned at 900 deg C in an industrial kiln. After that, they were submitted to tests of water absorption, apparent porosity, bulk density and flexural strength. The results show that the chemical composition of clay has significant amount of silica and alumina and adequate levels of kaolinite for use in structural ceramic. The ceramic properties evaluated in the specimens partially meet the requirements of the Brazilian standard-clays for structural ceramics. (author)

  15. Characterization of ceramics used in mass ceramic industry Goianinha/RN

    International Nuclear Information System (INIS)

    Sales Junior, J.C.C.; Nascimento, R.M. do; Andrade, J.C.S.; Saldanha, K.M.; Dutra, R.P.S.

    2011-01-01

    The preparation of the the ceramic mass is one of the most important steps in the manufacture of ceramic products, since the characteristics of the raw materials used, and the proportions that they are added, directly influence the final properties of ceramic products and the operational conditions of processing. The objective of this paper is to present the results of the characterization of a ceramic mass used in the manufacture of sealing blocks by a red ceramic industry of the city of Goianinha / RN. We analyzed the chemical and mineralogical composition; thermogravimetric and differential thermal analysis; granulometric analysis; evaluation of plasticity; and determining the technological properties of specimens used in test firing at 700, 900 and 1100 ° C. The results show that the ceramic body studied has characteristics that allow use in the manufacture of sealing blocks when burned at a temperature of 900 ° C. (author)

  16. Tribology of ceramics: Report of the Committee on Tribology of Ceramics

    Science.gov (United States)

    1988-01-01

    The current state of knowledge of ceramic surface structures, composition, and reactivity is reviewed. The tribological requirements of advanced mechanical systems now being deployed (in particular, heat engines) exceed the capabilities of traditional metallic-based materials because of the high temperatures encountered. Advanced ceramic materials for such applications are receiving intense scrutiny, but there is a lack of understanding of the properties and behavior of ceramic surfaces and the influence of processing on the properties of ceramics is described. The adequacy of models, ranging form atomic to macro, to describe and to predict ceramic friction and wear are discussed, as well as what is known about lubrication at elevated temperatures. From this analysis, recommendations are made for coordination, research, and development that will lead to better performance of ceramic materials in tribological systems.

  17. Flight-vehicle materials, structures, and dynamics - Assessment and future directions. Vol. 3 - Ceramics and ceramic-matrix composites

    Science.gov (United States)

    Levine, Stanley R. (Editor)

    1992-01-01

    The present volume discusses ceramics and ceramic-matrix composites in prospective aerospace systems, monolithic ceramics, transformation-toughened and whisker-reinforced ceramic composites, glass-ceramic matrix composites, reaction-bonded Si3N4 and SiC composites, and chemical vapor-infiltrated composites. Also discussed are the sol-gel-processing of ceramic composites, the fabrication and properties of fiber-reinforced ceramic composites with directed metal oxidation, the fracture behavior of ceramic-matrix composites (CMCs), the fatigue of fiber-reinforced CMCs, creep and rupture of CMCs, structural design methodologies for ceramic-based materials systems, the joining of ceramics and CMCs, and carbon-carbon composites.

  18. Recent research activities on functional ceramics for insulator, breeder and optical sensing systems in fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, S., E-mail: nagata@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Sendai (Japan); Katsui, H.; Hoshi, K. [Institute for Materials Research, Tohoku University, Sendai (Japan); Tsuchiya, B. [Meijo University, Faculty of Science and Technology, Nagoya (Japan); Toh, K. [J-PARC Center Japan Atomic Energy Agency, Tokai (Japan); Zhao, M.; Shikama, T. [Institute for Materials Research, Tohoku University, Sendai (Japan); Hodgson, E.R. [Euratom/CIEMAT Fusion Association, Madrid (Spain)

    2013-11-15

    The paper presents a brief overview of current research activities on functional ceramic materials for insulating components, tritium breeder and optical sensing systems, mainly carried out at Institute for Materials Research (IMR), Tohoku University. Topics include recent experimental results related to the electrical degradation and optical changes in typical oxide ceramics (e.g. Al{sub 2}O{sub 3} and SiO{sub 2}) concerning radiolytic effects. Hydrogen effects on the electrical conductivity in the Perovskite-type oxide ceramics and the interaction between hydrogen and irradiation induced defects in ternary Li oxides used as breeder materials, were dynamically observed under the irradiation environment. Further attention is focused on several challenging qualifications required for an advanced sensing system using optical characteristics (e.g., thermoluminescence in SiO{sub 2} core fiber, neutron-induced long lasting emission from oxides doped with rare-earth elements, and gasochromic coloration phenomenon of WO{sub 3})

  19. Recycling of the reduction sludge of manganese in the production of ceramics

    International Nuclear Information System (INIS)

    Castro, C.G.; Araujo, F.G.S.; Kruger, F.L.

    2011-01-01

    To study the use of manganese reduction residues, from the electric arc furnaces for the production of manganese ferro-alloys, as raw materials for construction bricks, different ceramic compositions were formulated with contents of 0, 2.5, 5 and 10wt% of waste addition to the clay used commercially, and sintered at different temperatures, 850, 950 and 1050°C. After firing, the ceramic samples were studied by optical microscopy, scanning electron microscopy (SEM), x-ray diffraction and by spectrophotometry. Their mechanical properties were evaluated by flexural strength, apparent porosity and specific mass, water absorption, linear shrinkage and loss on ignition. With the help of technics and experiment planning programs, the effects of the variables: temperature, composition and interaction between them over the results were discussed. This work proved that the addition of manganese reduction sludge to the clay, for the production of ceramic construction bricks, is highly feasible, from a technical standpoint. (author)

  20. Vibrational Spectroscopy as a Promising Toolbox for Analyzing Functionalized Ceramic Membranes.

    Science.gov (United States)

    Kiefer, Johannes; Bartels, Julia; Kroll, Stephen; Rezwan, Kurosch

    2018-01-01

    Ceramic materials find use in many fields including the life sciences and environmental engineering. For example, ceramic membranes have shown to be promising filters for water treatment and virus retention. The analysis of such materials, however, remains challenging. In the present study, the potential of three vibrational spectroscopic methods for characterizing functionalized ceramic membranes for water treatment is evaluated. For this purpose, Raman scattering, infrared (IR) absorption, and solvent infrared spectroscopy (SIRS) were employed. The data were analyzed with respect to spectral changes as well as using principal component analysis (PCA). The Raman spectra allow an unambiguous discrimination of the sample types. The IR spectra do not change systematically with functionalization state of the material. Solvent infrared spectroscopy allows a systematic distinction and enables studying the molecular interactions between the membrane surface and the solvent.

  1. High temperature alloys and ceramic heat exchanger

    International Nuclear Information System (INIS)

    Okamoto, Masaharu

    1984-04-01

    From the standpoint of energy saving, the future operating temperatures of process heat and gas turbine plants will become higher. For this purpose, ceramics is the most promissing candidate material in strength for application to high-temperature heat exchangers. This report deals with a servey of characteristics of several high-temperature metallic materials and ceramics as temperature-resistant materials; including a servey of the state-of-the-art of ceramic heat exchanger technologies developed outside of Japan, and a study of their application to the intermediate heat exchanger of VHTR (a very-high-temperature gas-cooled reactor). (author)

  2. Solidification of HLLW into sintered ceramics

    International Nuclear Information System (INIS)

    O-Oka, K.; Ohta, T.; Masuda, S.; Tsunoda, N.

    1979-01-01

    Simulated HLLW from the PNC reprocessing plant at Tokai was solidified into sintered ceramics by normal sintering or hot-pressing with addition of some oxides. Among various ceramic products obtained so far, the most preferable was nepheline-type sintered solids formed with addition of SiO 2 and Al 2 O 3 to the simulated waste calcine. The solid shows advantageous properties in leach rate and mechanical strength, which suggest that the ceramic solids were prepared with additions of ZrO 2 or MnO 2 , and some of them showed good characteristics

  3. High-performance ceramics. Fabrication, structure, properties

    International Nuclear Information System (INIS)

    Petzow, G.; Tobolski, J.; Telle, R.

    1996-01-01

    The program ''Ceramic High-performance Materials'' pursued the objective to understand the chaining of cause and effect in the development of high-performance ceramics. This chain of problems begins with the chemical reactions for the production of powders, comprises the characterization, processing, shaping and compacting of powders, structural optimization, heat treatment, production and finishing, and leads to issues of materials testing and of a design appropriate to the material. The program ''Ceramic High-performance Materials'' has resulted in contributions to the understanding of fundamental interrelationships in terms of materials science, which are summarized in the present volume - broken down into eight special aspects. (orig./RHM)

  4. Properties of textile grade ceramic fibers

    International Nuclear Information System (INIS)

    Pudnos, E.

    1992-01-01

    The availability of textile grade ceramic fibers has sparked great interest for applications in composite reinforcement and high temperature insulation. This paper summarizes the properties of various small diameter textile grade ceramic fibers currently available. Room temperature mechanical and electrical properties of the fibers are discussed for three cases: ambient conditions, after heat aging in argon, and after heat aging in wet air. Dow Corning (R) HPZ Ceramic Fiber, a silicon nitride type fiber, is shown to have improved retention of mechanical and electrical properties above 1200 C

  5. Clay Ceramic Filter for Water Treatment

    Directory of Open Access Journals (Sweden)

    Zereffa Enyew Amare

    2017-05-01

    Full Text Available Ceramic water filters were prepared from different proportions of kaolin and soft wood and sintered at 900 °C, 950 °C, and 1000 °C. The flow rate, conductivity, pH of filtered water and removal efficiency (microbial, water hardness agent’s, nitrite and turbidity were analysed. The ceramic filter with 15 % saw dust, 80 % clay and 5 % grog that was fired at temperature of 950 °C or 1000 °C showed the best removal efficiency. Statistical ANOVA tests showed a significant difference between ceramic filters with various compositions in their removal efficiencies.

  6. Porous ceramic scaffolds with complex architectures

    Science.gov (United States)

    Munch, E.; Franco, J.; Deville, S.; Hunger, P.; Saiz, E.; Tomsia, A. P.

    2008-06-01

    This work compares two novel techniques for the fabrication of ceramic scaffolds for bone tissue engineering with complex porosity: robocasting and freeze casting. Both techniques are based on the preparation of concentrated ceramic suspensions with suitable properties for the process. In robocasting, the computer-guided deposition of the suspensions is used to build porous materials with designed three dimensional geometries and microstructures. Freeze casting uses ice crystals as a template to form porous lamellar ceramic materials. Preliminary results on the compressive strengths of the materials are also reported.

  7. Ceramic sealants prepared by polymer pyrolysis

    Science.gov (United States)

    Hong, Sung Jin; Kim, Deug Joong; Yoo, Young Sung

    2011-02-01

    The formation and properties of ceramic seals for SOFC applications prepared by polymer pyrolysis are investigated. A mixture with polymethylsiloxane and fillers are pyrolyzed in a N2 atmosphere. The coefficient of thermal expansion of the ceramic composites was controlled by fillers with a high coefficient of thermal expansion such as AlCo. The morphology of the ceramic composites derived from the mixture with polymethylsiloxane and fillers is composed of fillers embedded in a Si-O-C glass matrix. The thermal expansion behavior and sealing characteristics are measured and discussed

  8. Multiscale Modeling of Ceramic Matrix Composites

    Science.gov (United States)

    Bednarcyk, Brett A.; Mital, Subodh K.; Pineda, Evan J.; Arnold, Steven M.

    2015-01-01

    Results of multiscale modeling simulations of the nonlinear response of SiC/SiC ceramic matrix composites are reported, wherein the microstructure of the ceramic matrix is captured. This micro scale architecture, which contains free Si material as well as the SiC ceramic, is responsible for residual stresses that play an important role in the subsequent thermo-mechanical behavior of the SiC/SiC composite. Using the novel Multiscale Generalized Method of Cells recursive micromechanics theory, the microstructure of the matrix, as well as the microstructure of the composite (fiber and matrix) can be captured.

  9. Optical effects of different colors of artificial gingiva on ceramic crowns.

    Science.gov (United States)

    Wang, Jian; Lin, Jin; Gil, Mindy; Da Silva, John D; Wright, Robert; Ishikawa-Nagai, Shigemi

    2013-08-01

    The interaction between gingival color and the shade of ceramic restorations has never been fully studied. The purpose of this study is to investigate the optical effects of altering artificial gingival color on the ceramic crown shade in the cervical area. Thirty-one all-ceramic crowns of different shades were used in this study with six different artificial gingival colors. Using a spectrophotometer (Crystaleye(®) Olympus, Japan), we measured the shade of crowns in cervical areas with each of six different artificial gingiva. The crown color measured in the presence of pink artificial gingiva (control) was compared with the crown color with five other artificial gingiva. color difference values ΔE* were calculated and compared between the control group and test groups and the correlation of the artificial gingival color with the crown color was also assessed. Significant differences were found in the mean L* and a* values of all-ceramic crowns at the cervical regions in all six gingival color groups (pcolors of artificial gingiva generated clinically detectable shade differences in the cervical region of ceramic crowns. Copyright © 2013. Published by Elsevier Ltd.

  10. Study of Wettability of Clayey Ceramic and Fluorescent Lamp Glass Waste Powders

    Science.gov (United States)

    Morais, Alline Sardinha Cordeiro; Monteiro, Sergio Neves; Ribeiro, Sebastião; Sardinha, Leonardo Carneiro; Vieira, Carlos Maurício Fontes

    The glass tube of spent fluorescent lamps is contaminated with mercury, which might be a serious hazard in the case of conventional recycling by melting with other glasses. A possible solution could be its incorporation into a clay body to fabricate common fired ceramics such as bricks and tiles. The objective of this work is to characterize a type of fluorescent lamp glass waste to be incorporated into a clayey ceramic. The characterization was performed in terms of wettability tests to evaluate the interaction between the surface of the clayey ceramic and glass waste as a function of the firing temperature. The results showed that the contact angle decreased with increasing temperature, reaching a value of 79°, at a temperature of 1100°C, but not sufficient to completely wet the ceramic. However, compatible chemical composition and reduction of porosity by the flow of soft glass waste between the clay particles favor the consolidation of the ceramics structure above 900°C.

  11. Supramolecular curcumin-barium prodrugs for formulating with ceramic particles.

    Science.gov (United States)

    Kamalasanan, Kaladhar; Anupriya; Deepa, M K; Sharma, Chandra P

    2014-10-01

    A simple and stable curcumin-ceramic combined formulation was developed with an aim to improve curcumin stability and release profile in the presence of reactive ceramic particles for potential dental and orthopedic applications. For that, curcumin was complexed with barium (Ba(2+)) to prepare curcumin-barium (BaCur) complex. Upon removal of the unbound curcumin and Ba(2+) by dialysis, a water-soluble BaCur complex was obtained. The complex was showing [M+1](+) peak at 10,000-20,000 with multiple fractionation peaks of MALDI-TOF-MS studies, showed that the complex was a supramolecular multimer. The (1)H NMR and FTIR studies revealed that, divalent Ba(2+) interacted predominantly through di-phenolic groups of curcumin to form an end-to-end complex resulted in supramolecular multimer. The overall crystallinity of the BaCur was lower than curcumin as per XRD analysis. The complexation of Ba(2+) to curcumin did not degrade curcumin as per HPLC studies. The fluorescence spectrum was blue shifted upon Ba(2+) complexation with curcumin. Monodisperse nanoparticles with size less than 200dnm was formed, out of the supramolecular complex upon dialysis, as per DLS, and upon loading into pluronic micelles the size was remaining in similar order of magnitude as per DLS and AFM studies. Stability of the curcumin was improved greater than 50% after complexation with Ba(2+) as per UV/Vis spectroscopy. Loading of the supramloecular nanoparticles into pluronic micelles had further improved the stability of curcumin to approx. 70% in water. These BaCur supramolecule nanoparticles can be considered as a new class of prodrugs with improved solubility and stability. Subsequently, ceramic nanoparticles with varying chemical composition were prepared for changing the material surface reactivity in terms of the increase in, degradability, surface pH and protein adsorption. Further, these ceramic particles were combined with curcumin prodrug formulations and optimized the curcumin release

  12. Alkaline resistant ceramics; Alkalimotstaandskraftiga keramer

    Energy Technology Data Exchange (ETDEWEB)

    Westberg, Stig-Bjoern [Vattenfall Utveckling AB, Aelvkarleby (Sweden)

    2001-02-01

    Despite durability in several environments, ceramics and refractories can not endure alkaline environments at high temperature. An example of such an environment is when burning biofuel in modern heat and power plants in which the demand for increasing efficiency results in higher combustion temperatures and content of alkaline substances in the flue gas. Some experiences of these environments has been gained from such vastly different equipment as regenerator chambers in the glass industry and MHD-generators. The grains of a ceramic material are usually bonded together by a glassy phase which despite it frequently being a minor constituent render the materials properties and limits its use at elevated temperature. The damage is usually caused by alkaline containing low-melting phases and the decrease of the viscosity of the bonding glass phase which is caused by the alkaline. The surfaces which are exposed to the flue gas in a modern power plant are not only exposed to the high temperature but also a corroding and eroding, particle containing, gas flow of high velocity. The use of conventional refractory products is limited to 1300-1350 deg C. Higher strength and fracture toughness as well as durability against gases, slag and melts at temperatures exceeding 1700 deg C are expected of the materials of the future. Continuous transport of corrosive compounds to the surface and corrosion products from the surface as well as a suitable environment for the corrosion to occur in are prerequisites for extensive corrosion to come about. The highest corrosion rate is therefore found in a temperature interval between the dew point and the melting point of the alkaline-constituent containing compound. It is therefore important that the corrosion resistance is sufficient in the environment in which alkaline containing melts or slag may appear. In environments such as these, even under normal circumstances durable ceramics, such as alumina and silicon carbide, are attacked

  13. Effects of Surface Morphology ZnAl2O4 of Ceramic Materials on Osteoblastic Cells Responses

    International Nuclear Information System (INIS)

    Suarez-Franco, J.L.; Fernandez-Pedrero, J.A.; Ivarez-Perez, M.A.; Garcia-Hipolito, M.; Surarez-Rosales, M.; Fregoso, O.; Juarez-Islas, J.A.; Ivarez-Perez, M.A.

    2013-01-01

    Ceramic scaffolds are widely studied in the tissue engineering field due to their potential in medical applications as bone substitutes or as bone-filling materials. The purpose of this study was to investigate the effect of surface morphology of nano structure thin films of ZnAl 2 O 4 prepared by spray pyrolysis and bulk pellets of polycrystalline ZnAl 2 O 4 prepared by chemical coprecipitation reaction on the in vitro cell adhesion, viability, and cell-material interactions of osteoblastic cells. Our result showed that cell attachment was significantly enhanced from 60 to 80% on the ZnAl 2 O 4 nano structured material surface when compared with bulk ceramic surfaces. Moreover, our results showed that the balance of morphological properties of the thin film nano structure ceramic improves cell-material interaction with enhanced spreading and filopodia with multiple cellular extensions on the surface of the ceramic and enhancing cell viability/proliferation in comparison with bulk ceramic surfaces used as control. Altogether, these results suggest that zinc aluminate nano structured materials have a great potential to be used in dental implant and bone substitute applications.Ceramic scaffolds are widely studied in the tissue engineering field due to their potential in medical applications as bone substitutes or as bone-filling materials. The purpose of this study was to investigate the effect of surface morphology of nano structure thin films of ZnAl 2 O 4 prepared by spray pyrolysis and bulk pellets of polycrystalline ZnAl 2 O 4 prepared by chemical coprecipitation reaction on the in vitro cell adhesion, viability, and cell-material interactions of osteoblastic cells. Our result showed that cell attachment was significantly enhanced from 60 to 80% on the ZnAl 2 O 4 nano structured material surface when compared with bulk ceramic surfaces. Moreover, our results showed that the balance of morphological properties of the thin film nano structure ceramic improves

  14. Archaeometric study of Amazon ceramic

    International Nuclear Information System (INIS)

    Sabino, Claudia de Vilhena Schayer; Amaral, Angela Maria; Poirior, Andre Pierre Prous

    2002-01-01

    There is no evidence of urban civilization in Brazilian prehistory; most inhabitants lived in tribal organization, probably with regional economic integration among several independent tribes. There are few evidences of seasonal migrations between the coast and the inland of southern Brazil. Some specialized horticulturists competed among themselves but other groups lived more isolatedly and probably peacefully, in the upper interfluvial regions. The chiefdom system is supposed to have existed only along the Amazon River. In this region, some pottery makers may have been specialized craftsmen and finest ceramics, that should have been exported from one village/region to another, can be found. In this study we tested some limited possibilities in three different cultural and regional contexts to see if application of analytic analysis in economically and politically 'simple' societies should give any results. (author)

  15. Mechanical behaviour of structural ceramics

    Directory of Open Access Journals (Sweden)

    Bueno, S.

    2007-06-01

    Full Text Available The use of ceramic materials in structural applications is limited by the lack of reliability associated with brittle fracture behaviour. In order to extend the structural use of ceramics, the design of microstructures which exhibit flaw tolerance due to toughening mechanisms which produce an increase in crack growth resistance during crack propagation has been proposed. This work is a review of the mechanical behaviour of structural ceramic materials and its characterisation. Firstly, the basic brittle fracture parameters and the statistical criteria to determine the probability of exceeding the safety factors demanded for a particular application are analysed. Then, the toughening mechanisms which can be developed in the materials through microstructural design as well as the mechanical characterisation of toughened ceramics are discussed. The experimental values of linear elastic fracture toughness parameters (critical stress intensity factor, KIC, and critical energy release rate, GIC are not intrinsic properties for toughened materials and depend on crack length and the loading system. In this work, the different mechanical parameters proposed to characterise such materials are reviewed. The following fracture parameters are analysed: work of fracture (γWOF, critical J-integral value (JIC and R-curve. For the determination, stable fracture tests are proposed in order to ensure that the energy provided during the test is no more than the necessary one for crack propagation.

    El uso de los materiales cerámicos en aplicaciones estructurales está limitado por la falta de fiabilidad asociada a su comportamiento frágil durante la fractura. Para extender su aplicación se ha propuesto el diseño de microestructuras que presenten tolerancia a los defectos debido a la actuación de mecanismos de refuerzo. Este trabajo es una puesta al día sobre el estudio del comportamiento mecánico de los materiales cerámicos estructurales y su

  16. Manufacturing of planar ceramic interconnects

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, B.L.; Coffey, G.W.; Meinhardt, K.D.; Armstrong, T.R. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-31

    The fabrication of ceramic interconnects for solid oxide fuel cells (SOFC) and separator plates for electrochemical separation devices has been a perennial challenge facing developers. Electrochemical vapor deposition (EVD), plasma spraying, pressing, tape casting and tape calendering are processes that are typically utilized to fabricate separator plates or interconnects for the various SOFC designs and electrochemical separation devices. For sake of brevity and the selection of a planar fuel cell or gas separation device design, pressing will be the only fabrication technique discussed here. This paper reports on the effect of the characteristics of two doped lanthanum manganite powders used in the initial studies as a planar porous separator for a fuel cell cathode and as a dense interconnect for an oxygen generator.

  17. Surface characterization of ceramic materials

    International Nuclear Information System (INIS)

    Somorjai, G.A.; Salmeron, M.

    1976-01-01

    In recent years several techniques have become available to characterize the structure and chemical composition of surfaces of ceramic materials. These techniques utilize electron scattering and scattering of ions from surfaces. Low-energy electron diffraction is used to determine the surface structure, Auger electron spectroscopy and other techniques of electron spectroscopy (ultraviolet and photoelectron spectroscopies) are employed to determine the composition of the surface. In addition the oxidation state of surface atoms may be determined using these techniques. Ion scattering mass spectrometry and secondary ion mass spectrometry are also useful in characterizing surfaces and their reactions. These techniques, their applications and the results of recent studies are discussed. 12 figures, 52 references, 2 tables

  18. CERAMIC WASTE FORM DATA PACKAGE

    Energy Technology Data Exchange (ETDEWEB)

    Amoroso, J.; Marra, J.

    2014-06-13

    The purpose of this data package is to provide information about simulated crystalline waste forms that can be used to select an appropriate composition for a Cold Crucible Induction Melter (CCIM) proof of principle demonstration. Melt processing, viscosity, electrical conductivity, and thermal analysis information was collected to assess the ability of two potential candidate ceramic compositions to be processed in the Idaho National Laboratory (INL) CCIM and to guide processing parameters for the CCIM operation. Given uncertainties in the CCIM capabilities to reach certain temperatures throughout the system, one waste form designated 'Fe-MP' was designed towards enabling processing and another, designated 'CAF-5%TM-MP' was designed towards optimized microstructure. Melt processing studies confirmed both compositions could be poured from a crucible at 1600{degrees}C although the CAF-5%TM-MP composition froze before pouring was complete due to rapid crystallization (upon cooling). X-ray diffraction measurements confirmed the crystalline nature and phase assemblages of the compositions. The kinetics of melting and crystallization appeared to vary significantly between the compositions. Impedance spectroscopy results indicated the electrical conductivity is acceptable with respect to processing in the CCIM. The success of processing either ceramic composition will depend on the thermal profiles throughout the CCIM. In particular, the working temperature of the pour spout relative to the bulk melter which can approach 1700{degrees}C. The Fe-MP composition is recommended to demonstrate proof of principle for crystalline simulated waste forms considering the current configuration of INL's CCIM. If proposed modifications to the CCIM can maintain a nominal temperature of 1600{degrees}C throughout the melter, drain, and pour spout, then the CAF-5%TM-MP composition should be considered for a proof of principle demonstration.

  19. Salt splitting using ceramic membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kurath, D.E. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-10-01

    Many radioactive aqueous wastes in the DOE complex have high concentrations of sodium that can negatively affect waste treatment and disposal operations. Sodium can decrease the durability of waste forms such as glass and is the primary contributor to large disposal volumes. Waste treatment processes such as cesium ion exchange, sludge washing, and calcination are made less efficient and more expensive because of the high sodium concentrations. Pacific Northwest National Laboratory (PNNL) and Ceramatec Inc. (Salt Lake City UT) are developing an electrochemical salt splitting process based on inorganic ceramic sodium (Na), super-ionic conductor (NaSICON) membranes that shows promise for mitigating the impact of sodium. In this process, the waste is added to the anode compartment, and an electrical potential is applied to the cell. This drives sodium ions through the membrane, but the membrane rejects most other cations (e.g., Sr{sup +2}, Cs{sup +}). The charge balance in the anode compartment is maintained by generating H{sup +} from the electrolysis of water. The charge balance in the cathode is maintained by generating OH{sup {minus}}, either from the electrolysis of water or from oxygen and water using an oxygen cathode. The normal gaseous products of the electrolysis of water are oxygen at the anode and hydrogen at the cathode. Potentially flammable gas mixtures can be prevented by providing adequate volumes of a sweep gas, using an alternative reductant or destruction of the hydrogen as it is generated. As H{sup +} is generated in the anode compartment, the pH drops. The process may be operated with either an alkaline (pH>12) or an acidic anolyte (pH <1). The benefits of salt splitting using ceramic membranes are (1) waste volume reduction and reduced chemical procurement costs by recycling of NaOH; and (2) direct reduction of sodium in process streams, which enhances subsequent operations such as cesium ion exchange, calcination, and vitrification.

  20. Polymer-Derived Ceramic Fibers

    Science.gov (United States)

    Ichikawa, Hiroshi

    2016-07-01

    SiC-based ceramic fibers are derived from polycarbosilane or polymetallocarbosilane precursors and are classified into three groups according to their chemical composition, oxygen content, and C/Si atomic ratio. The first-generation fibers are Si-C-O (Nicalon) fibers and Si-Ti-C-O (Tyranno Lox M) fibers. Both fibers contain more than 10-wt% oxygen owing to oxidation during curing and lead to degradation in strength at temperatures exceeding 1,300°C. The maximum use temperature is 1,100°C. The second-generation fibers are SiC (Hi-Nicalon) fibers and Si-Zr-C-O (Tyranno ZMI) fibers. The oxygen content of these fibers is reduced to less than 1 wt% by electron beam irradiation curing in He. The thermal stability of these fibers is improved (they are stable up to 1,500°C), but their creep resistance is limited to a maximum of 1,150°C because their C/Si atomic ratio results in excess carbon. The third-generation fibers are stoichiometric SiC fibers, i.e., Hi-Nicalon Type S (hereafter Type S), Tyranno SA, and Sylramic™ fibers. They exhibit improved thermal stability and creep resistance up to 1,400°C. Stoichiometric SiC fibers meet many of the requirements for the use of ceramic matrix composites for high-temperature structural application. SiBN3C fibers derived from polyborosilazane also show promise for structural applications, remain in the amorphous state up to 1,800°C, and have good high-temperature creep resistance.

  1. Compact Ceramic Microchannel Heat Exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Lewinsohn, Charles [Ceramatec, Inc., Salt Lake City, UT (United States)

    2016-10-31

    The objective of the proposed work was to demonstrate the feasibility of a step change in power plant efficiency at a commercially viable cost, by obtaining performance data for prototype, compact, ceramic microchannel heat exchangers. By performing the tasks described in the initial proposal, all of the milestones were met. The work performed will advance the technology from Technology Readiness Level 3 (TRL 3) to Technology Readiness Level 4 (TRL 4) and validate the potential of using these heat exchangers for enabling high efficiency solid oxide fuel cell (SOFC) or high-temperature turbine-based power plants. The attached report will describe how this objective was met. In collaboration with The Colorado School of Mines (CSM), specifications were developed for a high temperature heat exchanger for three commercial microturbines. Microturbines were selected because they are a more mature commercial technology than SOFC, they are a low-volume and high-value target for market entry of high-temperature heat exchangers, and they are essentially scaled-down versions of turbines used in utility-scale power plants. Using these specifications, microchannel dimensions were selected to meet the performance requirements. Ceramic plates were fabricated with microchannels of these dimensions. The plates were tested at room temperature and elevated temperature. Plates were joined together to make modular, heat exchanger stacks that were tested at a variety of temperatures and flow rates. Although gas flow rates equivalent to those in microturbines could not be achieved in the laboratory environment, the results showed expected efficiencies, robust operation under significant temperature gradients at high temperature, and the ability to cycle the stacks. Details of the methods and results are presented in this final report.

  2. Wear mechanisms in ceramic hip implants.

    Science.gov (United States)

    Slonaker, Matthew; Goswami, Tarun

    2004-01-01

    The wear in hip implants is one of the main causes for premature hip replacements. The wear affects the potential life of the prosthesis and subsequent removals of in vivo implants. Therefore, the objective of this article is to review various joints that show lower wear rates and consequently higher life. Ceramics are used in hip implants and have been found to produce lower wear rates. This article discusses the advantages and disadvantages of ceramics compared to other implant materials. Different types of ceramics that are being used are reviewed in terms of the wear characteristics, debris released, and their size together with other biological factors. In general, the wear rates in ceramics were lower than that of metal-on-metal and metal-on-polyethylene combinations.

  3. Screening and classification of ceramic powders

    Science.gov (United States)

    Miwa, S.

    1983-01-01

    A summary is given of the classification technology of ceramic powders. Advantages and disadvantages of the wet and dry screening and classification methods are discussed. Improvements of wind force screening devices are described.

  4. High Temperature Characterization of Ceramic Pressure Sensors

    National Research Council Canada - National Science Library

    Fonseca, Michael A; English, Jennifer M; Von Arx, Martin; Allen, Mark G

    2001-01-01

    This work reports functional wireless ceramic micromachined pressure sensors operating at 450 C, with demonstrated materials and readout capability indicating potential extension to temperatures in excess of 600 C...

  5. Mixed-mode fracture of ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.

    1985-01-01

    The mixed-mode fracture behavior of ceramic materials is of importance for monolithic ceramics in order to predict the onset of fracture under generalized loading conditions and for ceramic composites to describe crack deflection toughening mechanisms. Experimental data on surface flaw mixed-mode fracture in various ceramics indicate that the flaw-plane normal stress at fracture decreases with increasing in-flaw-plane shear stress, although present data exhibit a fairly wide range in details of this sigma - tau relationship. Fracture from large cracks suggests that Mode II has a greater effect on Mode I fracture than Mode III. A comparison of surface flaw and large crack mixed-mode I-II fracture responses indicated that surface flaw behavior is influenced by shear resistance effects.

  6. Scaling up the microwave firing of ceramics

    International Nuclear Information System (INIS)

    Wroe, F.C.R.

    1993-01-01

    EA Technology, through a comprehensive R ampersand D program, is developing new microwave furnace technology focused on the ceramics processing industries. Using a combination of computer modelling, experimentation and feasibility studies, EA Technology has developed processes and procedures for firing large ceramic components. The aim of this work is to describe the investigation of the firing of ceramic products such as bricks, pottery, refractories, and industrial ceramics, using advanced processing techniques to produce and maintain uniformity of temperature throughout the components and kiln environment. This has achieved the goal of producing uniform microstructures and low thermal stress by careful control of the firing cycle. This paper illustrates the feasibility of microwave-assisted firing and shows it to be economically viable in terms of energy costs and process control. 6 refs., 1 fig

  7. Additively Manufactured Ceramic Rocket Engine Components

    Data.gov (United States)

    National Aeronautics and Space Administration — HRL Laboratories, LLC, with Vector Space Systems (VSS) as subcontractor, has a 24-month effort to develop additive manufacturing technology for reinforced ceramic...

  8. Additive manufacturing of polymer-derived ceramics

    Science.gov (United States)

    Eckel, Zak C.; Zhou, Chaoyin; Martin, John H.; Jacobsen, Alan J.; Carter, William B.; Schaedler, Tobias A.

    2016-01-01

    The extremely high melting point of many ceramics adds challenges to additive manufacturing as compared with metals and polymers. Because ceramics cannot be cast or machined easily, three-dimensional (3D) printing enables a big leap in geometrical flexibility. We report preceramic monomers that are cured with ultraviolet light in a stereolithography 3D printer or through a patterned mask, forming 3D polymer structures that can have complex shape and cellular architecture. These polymer structures can be pyrolyzed to a ceramic with uniform shrinkage and virtually no porosity. Silicon oxycarbide microlattice and honeycomb cellular materials fabricated with this approach exhibit higher strength than ceramic foams of similar density. Additive manufacturing of such materials is of interest for propulsion components, thermal protection systems, porous burners, microelectromechanical systems, and electronic device packaging.

  9. Ceramics and glasses for radioactive waste storage

    International Nuclear Information System (INIS)

    Baudin, G.

    1984-06-01

    Borosilicate glasses are mainly choosen for the confinement of fission products; industrial plants are either in operation (AVM) or in construction. Studies of ceramics as a matrix haven't received real application [fr

  10. Celsian Glass-Ceramic Matrix Composites

    Science.gov (United States)

    Bansal, Narottam P.; Dicarlo, James A.

    1996-01-01

    Glass-ceramic matrix reinforced fiber composite materials developed for use in low dielectric applications, such as radomes. Materials strong and tough, exhibit low dielectric properties, and endure high temperatures.

  11. Radiation effects on structural ceramics in fusion

    International Nuclear Information System (INIS)

    Hopkins, G.R.; Price, R.J.; Trester, P.W.

    1986-01-01

    Ceramics are required to serve in a conventional role as electrical and thermal insulators and dielectrics in fusion power reactors. In addition, certain ceramic materials can play a unique structural role in fusion power reactors by virtue of their very low induced radioactivity from fusion neutron capture. The aspects of safety, long-term radioactive waste management, and personnel access for maintenance and repair can all be significantly improved by applying the low-activation ceramics to the structural materials of the first-wall and blanket regions of a fusion reactor. Achievement of long service life at high structural loads and thermal stresses on the materials exposed to high-radiation doses presents a critical challenge for fusion. In this paper, we discuss radiation effects on structural ceramics for fusion application

  12. Toward Modeling Limited Plasticity in Ceramic Materials

    National Research Council Canada - National Science Library

    Grinfeld, Michael; Schoenfeld, Scott E; Wright, Tim W

    2008-01-01

    The characteristic features of many armor-related ceramic materials are the anisotropy on the micro-scale level and the very limited, though non-vanishing, plasticity due to limited number of the planes for plastic slip...

  13. Photon CT scanning of advanced ceramic materials

    International Nuclear Information System (INIS)

    Sawicka, B.D.; Ellingson, W.A.

    1987-02-01

    Advanced ceramic materials are being developed for high temperature applications in advanced heat engines and high temperature heat recovery systems. Small size flaws (10 - 200 μm) and small nonuniformities in density distributions (0.1 -2%) present as long-range density gradients, are critical in most ceramics and their detection is of crucial importance. Computed tomographic (CT) imaging provides a means of obtaining a precise two-dimensional density map of a cross section through an object from which accurate information about small flaws and small density gradients can be obtained. With the use of high energy photon sources high contrast CT images can be obtained for both low and high density ceramics. In the present paper we illustrate the applicability of the photon CT technique to the examination of advanced ceramics. CT images of sintered alumina tiles are presented from which data on high-density inclusions, cracks and density gradients have been extracted

  14. Transparent Ceramic Scintillator Fabrication, Properties and Applications

    International Nuclear Information System (INIS)

    Cherepy, N.J.; Kuntz, J.D.; Roberts, J.J.; Hurst, T.A.; Drury, O.B.; Sanner, R.D.; Tillotson, T.M.; Payne, S.A.

    2008-01-01

    Transparent ceramics offer an alternative to single crystals for scintillator applications such as gamma ray spectroscopy and radiography. We have developed a versatile, scaleable fabrication method, using Flame Spray Pyrolysis (FSP) to produce feedstock which is readily converted into phase-pure transparent ceramics. We measure integral light yields in excess of 80,000 Ph/MeV with Cerium-doped Garnets, and excellent optical quality. Avalanche photodiode readout of Garnets provides resolution near 6%. For radiography applications, Lutetium Oxide offers a high performance metric and is formable by ceramics processing. Scatter in transparent ceramics due to secondary phases is the principal limitation to optical quality, and afterglow issues that affect the scintillation performance are presently being addressed

  15. Microstructure and properties of ceramic materials

    International Nuclear Information System (INIS)

    Yen Tungsheng

    1984-01-01

    Ceramics materials study is an important field in modern materials science. Each side presented 19 papers most of which were recent investigations giving rather extensive coverage of microstructure and properties of new materials. (Auth.)

  16. Composite metal foil and ceramic fabric materials

    Science.gov (United States)

    Webb, Brent J.; Antoniak, Zen I.; Prater, John T.; DeSteese, John G.

    1992-01-01

    The invention comprises new materials useful in a wide variety of terrestrial and space applications. In one aspect, the invention comprises a flexible cloth-like material comprising a layer of flexible woven ceramic fabric bonded with a layer of metallic foil. In another aspect, the invention includes a flexible fluid impermeable barrier comprising a flexible woven ceramic fabric layer having metal wire woven therein. A metallic foil layer is incontinuously welded to the woven metal wire. In yet another aspect, the invention includes a material comprising a layer of flexible woven ceramic fabric bonded with a layer of an organic polymer. In still another aspect, the invention includes a rigid fabric structure comprising a flexible woven ceramic fabric and a resinous support material which has been hardened as the direct result of exposure to ultraviolet light. Inventive methods for producing such material are also disclosed.

  17. Testing Consent Order on Refractory Ceramic Fibers

    Science.gov (United States)

    This notice announces that EPA has signed signed an enforceable testing consent order under the Toxic Substances Control Act (TSCA), 15 U.S.C. section 2601 at seq., with three of the primary producers of refractory ceramic fibers (RCF).

  18. Tensile Behaviour of Open Cell Ceramic Foams

    Czech Academy of Sciences Publication Activity Database

    Řehořek, Lukáš; Dlouhý, Ivo; Chlup, Zdeněk

    2009-01-01

    Roč. 53, č. 4 (2009), s. 237-241 ISSN 0862-5468 R&D Projects: GA ČR GA101/09/1821; GA ČR GD106/09/H035 Institutional research plan: CEZ:AV0Z20410507 Keywords : Tensile test * Ceramics foam * Open porosity * Tensile strength Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.649, year: 2009

  19. Tensile properties of open cell ceramic foams

    Czech Academy of Sciences Publication Activity Database

    Bertolla, Luca; Dlouhý, Ivo; Řehořek, Lukáš; Chlup, Zdeněk

    2013-01-01

    Roč. 3, č. 1 (2013), s. 106-113 ISSN 1338-1660. [FRACTOGRAPHY 2012. Stará Lesná, 21.10.2012-24.10.2012] R&D Projects: GA ČR(CZ) GA101/09/1821 EU Projects: European Commission(XE) 264526 - GLACERCO Institutional support: RVO:68081723 Keywords : tension test * cellular materials * ceramics Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  20. Ceramics for Dental Applications: A Review

    Directory of Open Access Journals (Sweden)

    Julie A. Holloway

    2010-01-01

    Full Text Available Over the past forty years, the technological evolution of ceramics for dental applications has been remarkable, as new materials and processing techniques are steadily being introduced. The improvement in both strength and toughness has made it possible to expand the range of indications to long-span fixed partial prostheses, implant abutments and implants. The present review provides a state of the art of ceramics for dental applications.

  1. Measurement of radiant properties of ceramic foam

    International Nuclear Information System (INIS)

    Hoornstra, J.; Turecky, M.; Maatman, D.

    1994-07-01

    An experimental facility is described for the measurement of the normal spectral and total emissivity and transmissivity of semi-transparent materials in the temperature range of 600 C to 1200 C. The set-up was used for the measurement of radiation properties of highly porous ceramic foam which is used in low NO x radiant burners. Emissivity and transmissivity data were measured and are presented for coated and uncoated ceramic foam of different thicknesses. (orig.)

  2. Small recuperated ceramic microturbine demonstrator concept

    International Nuclear Information System (INIS)

    McDonald, Colin F.; Rodgers, Colin

    2008-01-01

    It has been about a decade since microturbines first entered service in the distributed generation market, and the efficiencies of these turbogenerators rated in the 30-100 kW power range have remained essentially on the order of 30%. In this time frame the cost of fuel (natural gas and oil) has increased substantially, and efforts are now underway to increase the efficiency of microturbines to 40% or higher. Various near-term means of achieving this are underway by utilizing established gas turbine technology, but now based on more complex thermodynamic cycles. A longer-term approach of improving efficiency is proposed in this paper based on the retention of the basic recuperated Brayton cycle, but now operating at significantly higher levels of turbine inlet temperature. However, in small low pressure ratio recuperated microturbines embodying radial flow turbomachinery this necessitates the use of ceramic components, including the turbine, recuperator and combustor. A development approach is proposed to design, fabricate and test a 7.5 kW ceramic microturbine demonstrator concept, which for the first time would involve the coupling of a ceramic radial flow turbine, a ceramic combustor, and a compact ceramic fixed-boundary high effectiveness recuperator. In a period of some three years, the major objectives of the proposed small ceramic microturbine R and D effort would be to establish a technology base involving thermal and stress analysis, design methodology, ceramic component fabrication techniques, and component development, these culminating in the assembly and testing to demonstrate engine structural integrity, and to verify performance. This would provide a benchmark for more confidently advancing to increased size ceramic-based turbogenerators with the potential for efficiencies of over 40%. In addition, the power size of the tested prototype could possibly emerge as a viable product, namely as a natural gas-fired turbogenerator with the capability of

  3. NDE of ceramic insulator blanks by radiography

    International Nuclear Information System (INIS)

    Sarvanan, S.; Venkatraman, B.; Jayakumar, T.; Baldev Raj

    1996-01-01

    The production of ceramic insulators in electrical industry involves a number of steps, one of which is the green blank. The defects such as voids and crack can be present in the extruded green blank. One of the best non-destructive evaluation (NDE) technique radiography. This paper deals with the development of methodology based on theoretical modeling for the examination of ceramics by high sensitivity radiography. (author)

  4. Microstructural characterization of nuclear-waste ceramics

    International Nuclear Information System (INIS)

    Ryerson, F.J.; Clarke, D.R.

    1982-01-01

    Characterization of nuclear waste ceramics requires techniques possessing high spatial and x-ray resolution. XRD, SEM, electron microprobe, TEM and analytical EM techniques are applied to ceramic formulations designed to immobilize both commercial and defense-related reactor wastes. These materials are used to address the strengths and limitations of the techniques above. An iterative approach combining all these techniques is suggested. 16 figures, 2 tables

  5. Machinability of IPS Empress 2 framework ceramic.

    Science.gov (United States)

    Schmidt, C; Weigl, P

    2000-01-01

    Using ceramic materials for an automatic production of ceramic dentures by CAD/CAM is a challenge, because many technological, medical, and optical demands must be considered. The IPS Empress 2 framework ceramic meets most of them. This study shows the possibilities for machining this ceramic with economical parameters. The long life-time requirement for ceramic dentures requires a ductile machined surface to avoid the well-known subsurface damages of brittle materials caused by machining. Slow and rapid damage propagation begins at break outs and cracks, and limits life-time significantly. Therefore, ductile machined surfaces are an important demand for machine dental ceramics. The machining tests were performed with various parameters such as tool grain size and feed speed. Denture ceramics were machined by jig grinding on a 5-axis CNC milling machine (Maho HGF 500) with a high-speed spindle up to 120,000 rpm. The results of the wear test indicate low tool wear. With one tool, you can machine eight occlusal surfaces including roughing and finishing. One occlusal surface takes about 60 min machining time. Recommended parameters for roughing are middle diamond grain size (D107), cutting speed v(c) = 4.7 m/s, feed speed v(ft) = 1000 mm/min, depth of cut a(e) = 0.06 mm, width of contact a(p) = 0.8 mm, and for finishing ultra fine diamond grain size (D46), cutting speed v(c) = 4.7 m/s, feed speed v(ft) = 100 mm/min, depth of cut a(e) = 0.02 mm, width of contact a(p) = 0.8 mm. The results of the machining tests give a reference for using IPS Empress(R) 2 framework ceramic in CAD/CAM systems. Copyright 2000 John Wiley & Sons, Inc.

  6. Bibliography of ceramic extrusion and plasticity

    Energy Technology Data Exchange (ETDEWEB)

    Janney, M.A.; Vance, M.C.; Jordan, A.C.; Kertesz, M.P.

    1987-03-01

    A comprehensive bibliography of ceramic extrusion and plasticity has been compiled. Over 670 abstracts are included covering the period 1932 to 1984. Citations cover a wide range of interests from basic science investigations to engineering ''tips'' and include references to brick and tile, whitewares, technical ceramics, theoretical models, engineering analyses, forming, drying, and raw materials. In addition to the citations, there are numerous indices to make the bibliography easy to use.

  7. Development of Advanced Ceramic Manufacturing Technology

    Energy Technology Data Exchange (ETDEWEB)

    Pujari, V.K.

    2001-04-05

    Advanced structural ceramics are enabling materials for new transportation engine systems that have the potential for significantly reducing energy consumption and pollution in automobiles and heavy vehicles. Ceramic component reliability and performance have been demonstrated in previous U.S. DOE initiatives, but high manufacturing cost was recognized as a major barrier to commercialization. Norton Advanced Ceramics (NAC), a division of Saint-Gobain Industrial Ceramics, Inc. (SGIC), was selected to perform a major Advanced Ceramics Manufacturing Technology (ACMT) Program. The overall objectives of NAC's program were to design, develop, and demonstrate advanced manufacturing technology for the production of ceramic exhaust valves for diesel engines. The specific objectives were (1) to reduce the manufacturing cost by an order of magnitude, (2) to develop and demonstrate process capability and reproducibility, and (3) to validate ceramic valve performance, durability, and reliability. The program was divided into four major tasks: Component Design and Specification, Component Manufacturing Technology Development, Inspection and Testing, and Process Demonstration. A high-power diesel engine valve for the DDC Series 149 engine was chosen as the demonstration part for this program. This was determined to be an ideal component type to demonstrate cost-effective process enhancements, the beneficial impact of advanced ceramics on transportation systems, and near-term commercialization potential. The baseline valve material was NAC's NT451 SiAION. It was replaced, later in the program, by an alternate silicon nitride composition (NT551), which utilized a lower cost raw material and a simplified powder-processing approach. The material specifications were defined based on DDC's engine requirements, and the initial and final component design tasks were completed.

  8. Techniques for ceramic sintering using microwave energy

    International Nuclear Information System (INIS)

    Kimrey, H.D.; Janney, M.A.; Becher, P.F.

    1987-01-01

    The use of microwave energy for ceramic sintering offers exciting new possibilities for materials processing. Based on experience gathered in microwave processing associated with the heating of fusion plasmas, we have developed hardware and methods for uniformly heating ceramic parts of large volume and irregular shape to temperatures in excess of 1600 0 C, in vacuum or pressurized atmosphere. Microwave processing at 28 GHz yields enhanced densification rates with a corresponding reduction in sintering temperatures. 6 refs

  9. Advanced Ceramic Materials for Future Aerospace Applications

    Science.gov (United States)

    Misra, Ajay

    2015-01-01

    With growing trend toward higher temperature capabilities, lightweight, and multifunctionality, significant advances in ceramic matrix composites (CMCs) will be required for future aerospace applications. The presentation will provide an overview of material requirements for future aerospace missions, and the role of ceramics and CMCs in meeting those requirements. Aerospace applications will include gas turbine engines, aircraft structure, hypersonic and access to space vehicles, space power and propulsion, and space communication.

  10. Prospects of ceramic tritium breeder materials

    International Nuclear Information System (INIS)

    Roth, E.; Roux, N.; Conservatoire National des Arts et Metiers; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette

    1989-01-01

    In this paper the authors examine the prospects of the main ceramics proposed as breeder materials for fusion reactors, i.e. Li-2O, Li-2ZrO-3, LiAlO-2, Li-4SiO-4. To do so they review terms of reference of contemplated blankets for NET, ITER and DEMO, and the proposed blanket concepts and materials. Issues respective to the use of each breeder material are examined, and from this review it is concluded that ceramics are the most favorable breeder materials whose use can be contemplated as well for a driver blanket for NET or ITER and for a DEMO blanket. Ceramics are then compared between themselves and it is seen that, subject to the confirmation of recent experimental results, lithium zirconate could be used with advantage in any of the present blanket concepts, except in those employing lithium at its natural isotopic abundance, in which case only Li-2O can be used. However in specific cases, or in parts of a blanket, other ceramics may be profitably employed. As a general conclusion suggestions are made to further improve ceramic breeder performances, and it is recommended to intensify also work on problems that have to be solved in order to operate ceramic breeder blankets e.g. tritium extraction and recovery systems and conditions of beryllium use. (author). 37 refs.; 12 tabs

  11. Ceramics in Restorative and Prosthetic DENTISTRY1

    Science.gov (United States)

    Kelly, J. Robert

    1997-08-01

    This review is intended to provide the ceramic engineer with information about the history and current use of ceramics in dentistry, contemporary research topics, and potential research agenda. Background material includes intra-oral design considerations, descriptions of ceramic dental components, and the origin, composition, and microstructure of current dental ceramics. Attention is paid to efforts involving net-shape processing, machining as a forming method, and the analysis of clinical failure. A rationale is presented for the further development of all-ceramic restorative systems. Current research topics receiving attention include microstructure/processing/property relationships, clinical failure mechanisms and in vitro testing, wear damage and wear testing, surface treatments, and microstructural modifications. The status of the field is critically reviewed with an eye toward future work. Significant improvements seem possible in the clinical use of ceramics based on engineering solutions derived from the study of clinically failed restorations, on the incorporation of higher levels of "biomimicry" in new systems, and on the synergistic developments in dental cements and adhesive dentin bonding.

  12. Structure and properties of interfaces in ceramics

    International Nuclear Information System (INIS)

    Bonnell, D.; Ruehle, M.; Chowdhry, U.

    1995-01-01

    The motivation for the symposium was the observation that interfaces in crystallographically and compositionally complex systems often dictate the performance and reliability of devices that utilize functional ceramics. The current level of understanding of interface-property relations in silicon-based devices required over 30 years of intensive research. Similar issues influence the relationship between atomic bonding at interfaces and properties in functional ceramic systems. The current understanding of these complex interfaces does not allow correlation between atomic structure and interface properties, in spite of their importance to a number of emerging technologies (wireless communications, radar-based positioning systems, sensors, etc.). The objective of this symposium was to focus attention on these fundamental issues by featuring recent theoretical and experimental work from various disciplines that impact the understanding of interface chemistry, structure, and properties. The emphasis was on relating properties of surfaces and interfaces to structure through an understanding of atomic level phenomena. Interfaces of interest include metal/ceramic, ceramic/ceramic, ceramic/vapor, etc., in electronic, magnetic, optical, ferroelectric, piezoelectric, and dielectric applications. Sixty one papers have been processed separately for inclusion on the data base

  13. Adjusting dental ceramics: An in vitro evaluation of the ability of various ceramic polishing kits to mimic glazed dental ceramic surface.

    Science.gov (United States)

    Steiner, René; Beier, Ulrike S; Heiss-Kisielewsky, Irene; Engelmeier, Robert; Dumfahrt, Herbert; Dhima, Matilda

    2015-06-01

    During the insertion appointment, the practitioner is often faced with the need to adjust ceramic surfaces to fit a restoration to the adjacent or opposing dentition and soft tissues. The purpose of this study was to assess the ceramic surface smoothness achieved with various commercially available ceramic polishing kits on different commonly used ceramic systems. The reliability of the cost of a polishing kit as an indicator of improved surface smoothness was assessed. A total of 350 ceramic surfaces representing 5 commonly available ceramic systems (IPS Empress Esthetic, IPS e.max Press, Cergo Kiss, Vita PM 9, Imagine PressX) were treated with 5 types of ceramic polishing systems (Cerapreshine, 94006C, Ceramiste, Optrafine, Zenostar) by following the manufacturers' guidelines. The surface roughness was measured with a profilometer (Taylor Hobson; Precision Taylor Hobson Ltd). The effects of ceramic systems and polishing kits of interest on surface roughness were analyzed by 2-way ANOVA, paired t test, and Bonferroni corrected significance level. The ceramic systems and polishing kits statistically affected surface roughness (Pceramic surface. No correlation could be established between the high cost of the polishing kit and low surface roughness. None of the commonly used ceramic polishing kits could create a surface smoother than that of glazed ceramic (Pceramic polishing kits is not recommended as a reliable indicator of better performance of ceramic polishing kits (P>.30). Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  14. Status quo of ceramic material for metal halide discharge lamps

    International Nuclear Information System (INIS)

    Kappen, Theo G M M

    2005-01-01

    Polycrystalline alumina is an excellent ceramic material for use as the envelope for metal halide discharge lamps. Although this material was introduced in the mid-1960s, and is thus already known for several decades, recent years have seen considerable effort aimed at further development of these ceramic envelope materials. Developments are not only in the field of ceramic shaping technologies, but are also concentrated on the material properties of the ceramic material itself. Optical, mechanical as well as the chemical properties of the ceramic envelope are strongly controlled by the shape as well as the microstructure of the ceramics used

  15. Y-TZP ceramic processing from coprecipitated powders : A comparative study with three commercial dental ceramics

    NARCIS (Netherlands)

    Lazar, Dolores R. R.; Bottino, Marco C.; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H. A.

    2008-01-01

    Objectives. (1) To synthesize 3 mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. Methods.

  16. Strategies for fracture toughness, strength and reliability optimisation of ceramic-ceramic laminates

    Czech Academy of Sciences Publication Activity Database

    Šestáková, L.; Bermejo, R.; Chlup, Zdeněk; Danzer, R.

    2011-01-01

    Roč. 102, č. 6 (2011), s. 613-626 ISSN 1862-5282 Institutional research plan: CEZ:AV0Z20410507 Keywords : Ceramic laminates * Layered ceramics * Residual stress * Fracture toughness * Threshold strength Subject RIV: JL - Materials Fatigue, Friction Mechanics Impact factor: 0.830, year: 2011

  17. Ceramic Foams from Pre-Ceramic Polymer Routes for Reusable Acreage Thermal Protection System Applications

    Science.gov (United States)

    Stackpoole, Mairead; Chien, Jennifer; Schaeffler, Michelle

    2004-01-01

    Contents include the following: Motivation. Current light weight insulation. Advantages of preceramic-polymer-derived ceramic foams. Rigid insulation materials. Tailor foam microstructures. Experimental approach. Results: sacrificial materials, sacrificial fillers. Comparison of foam microstructures. Density of ceramic foams. Phase evolution and properties: oxidation behavior. mechanical properties, aerothermal performance. Impact damage of microcellular foams. Conclusions.

  18. Ceramic fiber-reinforced monoclinic celsian phase glass-ceramic matrix composite material

    Science.gov (United States)

    Bansal, Narottam P. (Inventor); Dicarlo, James A. (Inventor)

    1994-01-01

    A hyridopolysilazane-derived ceramic fiber reinforced monoclinic celsian phase barium aluminum silicate glass-ceramic matrix composite material is prepared by ball-milling an aqueous slurry of BAS glass powder and fine monoclinic celsian seeds. The fibers improve the mechanical strength and fracture toughness and with the matrix provide superior dielectric properties.

  19. Ceramic inlays : effect of mechanical cycling and ceramic type on restoration-dentin bond strength

    NARCIS (Netherlands)

    Trindade, F.Z.; Kleverlaan, C.J.; da Silva, L.H.; Feilzer, A.J.; Cesar, P.F.; Bottino, M.A.; Valandro, L.F.

    2016-01-01

    This study aimed to evaluate the bond strength between dentin and five different ceramic inlays in permanent maxillary premolars, with and without mechanical cycling. One hundred permanent maxillary premolars were prepared and divided into 10 groups (n=10) according to the ceramic system (IPS e.Max

  20. Structural integrity of ceramic multilayer capacitor materials and ceramic multilayer capacitors

    NARCIS (Netherlands)

    With, de G.

    1993-01-01

    An review with 61 refs. is given of the fracture of and stress situation in ceramic capacitor materials and ceramic multilayer capacitors. A brief introduction to the relevant concepts is given first. Next the data for capacitor materials and the data for capacitors are discussed. The materials data