WorldWideScience

Sample records for integrating ultra-high-temperature ceramic

  1. Multilayer ultra-high-temperature ceramic coatings

    Science.gov (United States)

    Loehman, Ronald E [Albuquerque, NM; Corral, Erica L [Tucson, AZ

    2012-03-20

    A coated carbon-carbon composite material with multiple ceramic layers to provide oxidation protection from ultra-high-temperatures, where if the carbon-carbon composite material is uninhibited with B.sub.4C particles, then the first layer on the composite material is selected from ZrB.sub.2 and HfB.sub.2, onto which is coated a layer of SiC coated and if the carbon-carbon composite material is inhibited with B.sub.4C particles, then protection can be achieved with a layer of SiC and a layer of either ZrB.sub.2 and HfB.sub.2 in any order.

  2. Evaluation of Ultra-High Temperature Ceramics for Aeropropulsion Use

    Science.gov (United States)

    Levine, Stanley R.; Opila, Elizabeth J.; Halbig, Michael C.; Kiser, James D.; Singh, Mrityunjay; Salem, Jonathan A.

    2001-01-01

    Among the ultra-high temperature ceramics (UHTC) are a group of materials consisting of zirconium diboride or hafnium diboride plus silicon carbide, and in some instances, carbon. These materials offer a good combination of properties that make them candidates for airframe leading edges on sharp-bodied reentry vehicles. These UHTC perform well in the environment for such applications, i.e., air at low pressure. The purpose of this study was to examine three of these materials under conditions more representative of a propulsion environment, i.e., higher oxygen partial pressure and total pressure. Results of strength and fracture toughness measurements, furnace oxidation and high velocity thermal shock exposures are presented for ZrB2 plus 20 volume % SiC, ZrB2 plus 14 volume % SiC plus 30 volume % C, and SCS-9a SiC fiber reinforced ZrB2 plus 20 volume % SiC. The poor oxidation resistance of UHTCs is the predominant factor limiting their applicability to propulsion applications.

  3. Design of Ultra-High Temperature Ceramics for Improved Performance

    Science.gov (United States)

    2009-02-28

    Student Speaking Contest (UHTC talks highlighted) Afternoon, May 11 — Yuhua Hall (B) Oral Presentation Competition for Domestic Students...materials (i. Cao •v/’/.i :v< Studi tit ( agliari, Italy) ;S^| (SAOH) Microstructurc and mechanical properties of ZrB.- based 111 If. via...spark plasma sintering J.l... Cao (Beijing Instiiuti >;< ! s-;j (SA016) Abladon rcsistunt ol pressureless sintered /riy-based ceramics /’ Q

  4. Ultra High Temperature and Multifunctional Ceramic Matrix Composite – Coating Systems for Light-Weight Space and Aero Systems

    Data.gov (United States)

    National Aeronautics and Space Administration — Revolutionary ultra-high temperature, high mechanical loading capable, oxidation resistant, durable ceramic coatings and light-weight fiber-reinforced Ceramic Matrix...

  5. Testing and Modeling Ultra-High Temperature Ceramic (UHTC) Materials For Hypersonic Flight

    Science.gov (United States)

    2011-11-30

    Ridge, D. G. Fletcher, C. O. Asma , O. Chazot, and J. Thömel, “Oxidation of ZrB2-SiC Ultra-High Temperature Ceramic Composites in Dissociated Air...Fletcher, C. O. Asma , “Characterization of ZrB2-SiC Ceramics Tested by Plasma Stream Oxidation,” poster, 32 th International Conference...Fahrenholtz, W.G., Hilmas, G.E., Zhu, S.M., Ridge, J., Fletcher, D.G., Asma , C.O., and Thomel, J., "Oxidation of ZrB2-SiC Ultrahigh-Temperature

  6. Assessment of the State of the Art of Ultra High Temperature Ceramics

    Science.gov (United States)

    Johnson, Sylvia; Gasch, Matt; Stackpoole, Mairead

    2009-01-01

    Ultra High Temperature Ceramics (UHTCs) are a family of materials that includes the borides, carbides and nitrides of hafnium-, zirconium- and titanium-based systems. UHTCs are famous for possessing some of the highest melting points of known materials. In addition, they are very hard, have good wear resistance, mechanical strength, and relatively high thermal conductivities (compared to other ceramic materials). Because of these attributes, UHTCs are ideal for thermal protection systems, especially those that require chemical and structural stability at extremely high operating temperatures. UHTCs have the potential to revolutionize the aerospace industry by enabling the development of sharp hypersonic vehicles or atmospheric entry probes capable of the most extreme entry conditions.

  7. Fracture Mechanisms of Zirconium Diboride Ultra-High Temperature Ceramics under Pulse Loading

    Science.gov (United States)

    Skripnyak, Vladimir V.; Bragov, Anatolii M.; Skripnyak, Vladimir A.; Lomunov, Andrei K.; Skripnyak, Evgeniya G.; Vaganova, Irina K.

    2015-06-01

    Mechanisms of failure in ultra-high temperature ceramics (UHTC) based on zirconium diboride under pulse loading were studied experimentally by the method of SHPB and theoretically using the multiscale simulation method. The obtained experimental and numerical data are evidence of the quasi-brittle fracture character of nanostructured zirconium diboride ceramics under compression and tension at high strain rates and the room temperatures. Damage of nanostructured porous zirconium diboride -based UHTC can be formed under stress pulse amplitude below the Hugoniot elastic limit. Fracture of nanostructured ultra-high temperature ceramics under pulse and shock-wave loadings is provided by fast processes of intercrystalline brittle fracture and relatively slow processes of quasi-brittle failure via growth and coalescence of microcracks. A decrease of the shear strength can be caused by nano-voids clusters in vicinity of triple junctions between ceramic matrix grains and ultrafine-grained ceramics. This research was supported by grants from ``The Tomsk State University Academic D.I. Mendeleev Fund Program'' and also N. I. Lobachevski State University of Nizhny Novgorod (Grant of post graduate mobility).

  8. NATO Advanced Research Workshop on Boron Rich Solids Sensors for Biological and Chemical Detection, Ultra High Temperature Ceramics, Thermoelectrics, Armor

    CERN Document Server

    Orlovskaya, Nina

    2011-01-01

    The objective of this book is to discuss the current status of research and development of boron-rich solids as sensors, ultra-high temperature ceramics, thermoelectrics, and armor. Novel biological and chemical sensors made of stiff and light-weight boron-rich solids are very exciting and efficient for applications in medical diagnoses, environmental surveillance and the detection of pathogen and biological/chemical terrorism agents. Ultra-high temperature ceramic composites exhibit excellent oxidation and corrosion resistance for hypersonic vehicle applications. Boron-rich solids are also promising candidates for high-temperature thermoelectric conversion. Armor is another very important application of boron-rich solids, since most of them exhibit very high hardness, which makes them perfect candidates with high resistance to ballistic impact. The following topical areas are presented: •boron-rich solids: science and technology; •synthesis and sintering strategies of boron rich solids; •microcantileve...

  9. Lattice Thermal Conductivity of Ultra High Temperature Ceramics ZrB2 and HfB2 from Atomistic Simulations

    Science.gov (United States)

    Lawson, John W.; Murray, Daw S.; Bauschlicher, Charles W., Jr.

    2011-01-01

    Atomistic Green-Kubo simulations are performed to evaluate the lattice thermal conductivity for single crystals of the ultra high temperature ceramics ZrB2 and HfB2 for a range of temperatures. Recently developed interatomic potentials are used for these simulations. Heat current correlation functions show rapid oscillations which can be identified with mixed metal-Boron optical phonon modes. Agreement with available experimental data is good.

  10. Effect of ultra high temperature ceramics as fuel cladding materials on the nuclear reactor performance by SERPENT Monte Carlo code

    Energy Technology Data Exchange (ETDEWEB)

    Korkut, Turgay; Kara, Ayhan; Korkut, Hatun [Sinop Univ. (Turkey). Dept. of Nuclear Energy Engineering

    2016-12-15

    Ultra High Temperature Ceramics (UHTCs) have low density and high melting point. So they are useful materials in the nuclear industry especially reactor core design. Three UHTCs (silicon carbide, vanadium carbide, and zirconium carbide) were evaluated as the nuclear fuel cladding materials. The SERPENT Monte Carlo code was used to model CANDU, PWR, and VVER type reactor core and to calculate burnup parameters. Some changes were observed at the same burnup and neutronic parameters (keff, neutron flux, absorption rate, and fission rate, depletion of U-238, U-238, Xe-135, Sm-149) with the use of these UHTCs. Results were compared to conventional cladding material zircalloy.

  11. Synthesis of Hafnium-Based Ceramic Materials for Ultra-High Temperature Aerospace Applications

    Science.gov (United States)

    Johnson, Sylvia; Feldman, Jay

    2004-01-01

    This project involved the synthesis of hafnium (Hf)-based ceramic powders and Hf-based precursor solutions that were suitable for preparation of Hf-based ceramics. The Hf-based ceramic materials of interest in this project were hafnium carbide (with nominal composition HE) and hafnium dioxide (HfO2). The materials were prepared at Georgia Institute of Technology and then supplied to research collaborators Dr. Sylvia Johnson and Dr. Jay Feldman) at NASA Ames Research Center.

  12. Spark-plasma sintering of ZrB2 ultra-high-temperature ceramics

    OpenAIRE

    Zamora Rodríguez, Víctor

    2013-01-01

    This work was performed in the context of the research line entitled Processing and Sintering of Advanced Ceramic Materials in the Grupo Especializado de Materiales of the University of Extremadura, and was supported by the Ministerio de Ciencia y Tecnología (Government of Spain) and FEDER funds under the Grant Nº MAT 2007-61609.

  13. Creep and Oxidation of Hafnium Diboride Based Ultra High Temperature Ceramics at 1500C

    Science.gov (United States)

    2015-12-01

    word ceramic comes from the Greek word keramos, meaning pottery, but now refers to many classes of materials, including clays , abrasives......these situations, the viscosity of the grain boundary becomes an important factor for the creep rate. 25 When grain elongation accompanies grain

  14. 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

  15. Theoretical Research on Thermal Shock Resistance of Ultra-High Temperature Ceramics Focusing on the Adjustment of Stress Reduction Factor

    Directory of Open Access Journals (Sweden)

    Daining Fang

    2013-02-01

    Full Text Available The thermal shock resistance of ceramics depends on not only the mechanical and thermal properties of materials, but also the external constraint and thermal condition. So, in order to study the actual situation in its service process, a temperature-dependent thermal shock resistance model for ultra-high temperature ceramics considering the effects of the thermal environment and external constraint was established based on the existing theory. The present work mainly focused on the adjustment of the stress reduction factor according to different thermal shock situations. The influences of external constraint on both critical rupture temperature difference and the second thermal shock resistance parameter in either case of rapid heating or cooling conditions had been studied based on this model. The results show the necessity of adjustment of the stress reduction factor in different thermal shock situations and the limitations of the applicable range of the second thermal shock resistance parameter. Furthermore, the model was validated by the finite element method.

  16. Oxidation Study of an Ultra High Temperature Ceramic Coatings Based on HfSiCN

    Science.gov (United States)

    Sacksteder, Dagny; Waters, Deborah L.; Zhu, Dongming

    2018-01-01

    High temperature fiber-reinforced ceramic matrix composites (CMCs) are important for aerospace applications because of their low density, high strength, and significantly higher-temperature capabilities compared to conventional metallic systems. The use of the SiCf/SiC and Cf/SiC CMCs allows the design of lighter-weight, more fuel efficient aircraft engines and also more advanced spacecraft airframe thermal protection systems. However, CMCs have to be protected with advanced environmental barrier coatings when they are incorporated into components for the harsh environments such as in aircraft engine or spacecraft applications. In this study, high temperature oxidation kinetics of an advanced HfSiCN coating on Cf/SiC CMC substrates were investigated at 1300 C, 1400 C, and 1500 C by using thermogravimetric analysis (TGA). The coating oxidation reaction parabolic rate constant and activation energy were estimated from the experimental results. The oxidation reaction studies showed that the coatings formed the most stable, predominant HfSiO4-HfO2 scales at 1400 C. A peroxidation test at 1400 C then followed by subsequent oxidation tests at various temperatures also showed more adherent scales and slower scale growth because of reduced the initial transient oxidation stage and increased HfSiO4-HfO2 content in the scales formed on the HfSiCN coatings.

  17. Comparison of Reactive and Non-Reactive Spark Plasma Sintering Routes for the Fabrication of Monolithic and Composite Ultra High Temperature Ceramics (UHTC Materials

    Directory of Open Access Journals (Sweden)

    Roberto Orrù

    2013-04-01

    Full Text Available A wider utilization of ultra high temperature ceramics (UHTC materials strongly depends on the availability of efficient techniques for their fabrication as dense bodies. Based on recent results reported in the literature, it is possible to state that Spark Plasma Sintering (SPS technology offers a useful contribution in this direction. Along these lines, the use of two different SPS-based processing routes for the preparation of massive UHTCs is examined in this work. One method, the so-called reactive SPS (R-SPS, consists of the synthesis and densification of the material in a single step. Alternatively, the ceramic powders are first synthesized by Self-propagating High-temperature Synthesis (SHS and then sintered by SPS. The obtained results evidenced that R-SPS method is preferable for the preparation of dense monolithic products, while the sintering of SHS powders requires relatively milder conditions when considering binary composites. The different kinetic mechanisms involved during R-SPS of the monolithic and composite systems, i.e., combustion-like or gradual solid-diffusion, respectively, provides a possible explanation. An important role is also played by the SHS process, particularly for the preparation of composite powders, since stronger interfaces are established between the ceramic constituents formed in situ, thus favoring diffusion processes during the subsequent SPS step.

  18. Phase and Microstructural Correlation of Spark Plasma Sintered HfB2-ZrB2 Based Ultra-High Temperature Ceramic Composites

    Directory of Open Access Journals (Sweden)

    Ambreen Nisar

    2017-07-01

    Full Text Available The refractory diborides (HfB2 and ZrB2 are considered as promising ultra-high temperature ceramic (UHTCs where low damage tolerance limits their application for the thermal protection system in re-entry vehicles. In this regard, SiC and CNT have been synergistically added as the sintering aids and toughening agents in the spark plasma sintered (SPS HfB2-ZrB2 system. Herein, a novel equimolar composition of HfB2 and ZrB2 has shown to form a solid-solution which then allows compositional tailoring of mechanical properties (such as hardness, elastic modulus, and fracture toughness. The hardness of the processed composite is higher than the individual phase hardness up to 1.5 times, insinuating the synergy of SiC and CNT reinforcement in HfB2-ZrB2 composites. The enhanced fracture toughness of CNT reinforced composite (up to a 196% increment surpassing that of the parent materials (ZrB2/HfB2-SiC is attributed to the synergy of solid solution formation and enhanced densification (~99.5%. In addition, the reduction in the analytically quantified interfacial residual tensile stress with SiC and CNT reinforcements contribute to the enhancement in the fracture toughness of HfB2-ZrB2-SiC-CNT composites, mandatory for aerospace applications.

  19. Lattice Thermal Conductivity of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2 from Atomistic Simulations

    Science.gov (United States)

    Lawson, John W.; Daw, Murray S.; Bauschlicher, Charles W.

    2012-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 have a number of properties that make them attractive for applications in extreme environments. One such property is their high thermal conductivity. Computational modeling of these materials will facilitate understanding of fundamental mechanisms, elucidate structure-property relationships, and ultimately accelerate the materials design cycle. Progress in computational modeling of UHTCs however has been limited in part due to the absence of suitable interatomic potentials. Recently, we developed Tersoff style parameterizations of such potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current, in contrast to the more typical monotonic decay seen in monoatomic materials such as Silicon, for example. Results at room temperature and at elevated temperatures will be reported.

  20. Multiscale Modeling of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2: Application to Lattice Thermal Conductivity

    Science.gov (United States)

    Lawson, John W.; Daw, Murray S.; Squire, Thomas H.; Bauschlicher, Charles W.

    2012-01-01

    We are developing a multiscale framework in computational modeling for the ultra high temperature ceramics (UHTC) ZrB2 and HfB2. These materials are characterized by high melting point, good strength, and reasonable oxidation resistance. They are candidate materials for a number of applications in extreme environments including sharp leading edges of hypersonic aircraft. In particular, we used a combination of ab initio methods, atomistic simulations and continuum computations to obtain insights into fundamental properties of these materials. Ab initio methods were used to compute basic structural, mechanical and thermal properties. From these results, a database was constructed to fit a Tersoff style interatomic potential suitable for atomistic simulations. These potentials were used to evaluate the lattice thermal conductivity of single crystals and the thermal resistance of simple grain boundaries. Finite element method (FEM) computations using atomistic results as inputs were performed with meshes constructed on SEM images thereby modeling the realistic microstructure. These continuum computations showed the reduction in thermal conductivity due to the grain boundary network.

  1. Investigations in the mechanism of carbothermal reduction of yttria stabilized zirconia for ultra-high temperature ceramics application and its influence on yttria contained in it

    Science.gov (United States)

    Sondhi, Anchal

    Zirconium carbide (ZrC) is a high modulus ceramic with an ultra-high melting temperature and, consequently, is capable of withstanding extreme environments. Carbon-carbon composites (CCCs) are important structural materials in current commercial and future hypersonic aircraft; however, these materials may be susceptible to degradation when exposed to elevated temperatures during extreme velocities. At speeds of exceeding Mach 5, intense heating of leading edges of the aircraft triggers rapid oxidation of carbon in CCCs resulting in degradation of the structure and probable failure. Environmental/thermal barrier coatings (EBC/TBC) are employed to protect airfoil structures from extreme conditions. Yttria stabilized zirconia (YSZ) is a well-known EBC/TBC material currently used to protect metallic turbine blades and other aerospace structures. In this work, 3 mol% YSZ has been studied as a potential EBC/TBC on CCCs. However, YSZ is an oxygen conductor and may not sufficiently slow the oxidation of the underlying CCC. Under appropriate conditions, ZrC can form at the interface between CCC and YSZ. Because ZrC is a poor oxygen ion conductor in addition to its stability at high temperatures, it can reduce the oxygen transport to the CCC and thus increase the service lifetime of the structure. This dissertation investigates the thermodynamics and kinetics of the YSZ/ZrC/CCC system and the resulting structural changes across multiple size scales. A series of experiments were conducted to understand the mechanisms and species involved in the carbothermal reduction of ZrO2 to form ZrC. 3 mol% YSZ and graphite powders were uniaxially pressed into pellets and reacted in a graphite (C) furnace. Rietveld x-ray diffraction phase quantification determined that greater fractions of ZrC were formed when carbon was the majority mobile species. These results were validated by modeling the process thermochemically and were confirmed with additional experiments. Measurements were

  2. Ultra-high temperature direct propulsion

    International Nuclear Information System (INIS)

    Araj, K.J.; Slovik, G.; Powell, J.R.; Ludewig, H.

    1987-01-01

    Potential advantages of ultra-high exhaust temperature (3000 K - 4000 K) direct propulsion nuclear rockets are explored. Modifications to the Particle Bed Reactor (PBR) to achieve these temperatures are described. Benefits of ultra-high temperature propulsion are discussed for two missions - orbit transfer (ΔV = 5546 m/s) and interplanetary exploration (ΔV = 20000 m/s). For such missions ultra-high temperatures appear to be worth the additional complexity. Thrust levels are reduced substantially for a given power level, due to the higher enthalpy caused by partial disassociation of the hydrogen propellant. Though technically challenging, it appears potentially feasible to achieve such ultra high temperatures using the PBR

  3. Studies on high-performance ceramic heat exchanger for ultra high temperature. 2nd Report. Heat transfer of finned tube bundle immersed in fluidized bed; Chokoon`yo koseino ceramic netsu kokanki ni kansuru kenkyu. 2. Ryudo sonai no rin kangun no netsudentatsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Himeji, Y; Kumada, M [Gifu University, Gifu (Japan). Faculty of Engineering

    1998-03-25

    Studies were carried out to develop a high-performance ceramic heat exchanger for ultra high temperatures using a fluidized bed. In the former study, Heat transfer coefficient had been improved by applying fluidized bed to the heat exchanger for high temperature with smooth ceramic tubes. In this study, finned ceramic tubes were applied instead of smooth tubes for more improvement of heat transfer and experiments were performed on condition that the maximum bed temperature was 1100degC. Fluidization remained stable and the bed temperature uniform in the bed similarly as the case of smooth tube. A heat transfer coefficient of finned tube was evaluated and it was improved about 3 times as large as that of smooth tube. The performance of the heat exchanger was also evaluated using temperature efficiency and exergy efficiency. 4 refs., 11 figs., 1 tab.

  4. Design and Fabrication of a Piezoresistive Pressure Sensor for Ultra High Temperature Environment

    International Nuclear Information System (INIS)

    Zhao, L B; Zhao, Y L; Jiang, Z D

    2006-01-01

    In order to solve the pressure measurement problem in the harsh environment, a piezoresistive pressure sensor has been developed, which can be used under high temperature above 200 deg. C and is able to endure instantaneous ultra high temperature (2000deg. C, duration≤2s) impact. Based on the MEMS (Micro Electro-Mechanical System) and integrated circuit technology, the piezoresistive pressure sensor's sensitive element was fabricated and constituted by silicon substrate, a thin buried silicon dioxide layer, four p-type resistors in the measuring circuit layer by boron ion implantation and photolithography, the top SiO2 layer by oxidation, stress matching Si3N4 layer, and a Ti-Pt-Au beam lead layer for connecting p-type resistors by sputtering. In order to decrease the leak-current influence to sensor in high temperature above 200deg. C, the buried SiO2 layer with the thickness 367 nm was fabricated by the SIMOX (Separation by Implantation of Oxygen) technology, which was instead of p-n junction to isolate the upper measuring circuit layer from Si substrate. In order to endure instantaneous ultra high temperature impact, the mechanical structure with cantilever and diaphragm and transmitting beam was designed. By laser welding and high temperature packaging technology, the high temperature piezoresistive pressure sensor was fabricated with range of 120MPa. After the thermal compensation, the sensor's thermal zero drift k 0 and thermal sensitivity drift k s were easy to be less than 3x10 -4 FS/deg. C. The experimental results show that the developed piezoresistive pressure sensor has good performances under high temperature and is able to endure instantaneous ultra high temperature impact, which meets the requirements of modern industry, such as aviation, oil, engine, etc

  5. Lightweight, Ultra-High-Temperature, CMC-Lined Carbon/Carbon Structures

    Science.gov (United States)

    Wright, Matthew J.; Ramachandran, Gautham; Williams, Brian E.

    2011-01-01

    Carbon/carbon (C/C) is an established engineering material used extensively in aerospace. The beneficial properties of C/C include high strength, low density, and toughness. Its shortcoming is its limited usability at temperatures higher than the oxidation temperature of carbon . approximately 400 C. Ceramic matrix composites (CMCs) are used instead, but carry a weight penalty. Combining a thin laminate of CMC to a bulk structure of C/C retains all of the benefits of C/C with the high temperature oxidizing environment usability of CMCs. Ultramet demonstrated the feasibility of combining the light weight of C/C composites with the oxidation resistance of zirconium carbide (ZrC) and zirconium- silicon carbide (Zr-Si-C) CMCs in a unique system composed of a C/C primary structure with an integral CMC liner with temperature capability up to 4,200 F (.2,315 C). The system effectively bridged the gap in weight and performance between coated C/C and bulk CMCs. Fabrication was demonstrated through an innovative variant of Ultramet fs rapid, pressureless melt infiltration processing technology. The fully developed material system has strength that is comparable with that of C/C, lower density than Cf/SiC, and ultra-high-temperature oxidation stability. Application of the reinforced ceramic casing to a predominantly C/C structure creates a highly innovative material with the potential to achieve the long-sought goal of long-term, cyclic high-temperature use of C/C in an oxidizing environment. The C/C substructure provided most of the mechanical integrity, and the CMC strengths achieved appeared to be sufficient to allow the CMC to perform its primary function of protecting the C/C. Nozzle extension components were fabricated and successfully hot-fire tested. Test results showed good thermochemical and thermomechanical stability of the CMC, as well as excellent interfacial bonding between the CMC liner and the underlying C/C structure. In particular, hafnium-containing CMCs on

  6. Achievement report for fiscal 1998 on research and development of industrial science technologies. Research and development on synergy ceramics (research and development of ultra-high temperature gas turbines for electric power generation); 1998 nendo shinaji ceramics no kenkyu kaihatsu. Hatsuden'yo koon gas turbine no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    This paper describes development of synergy ceramics. In developing a technology to design property fusion processes, studies were made on control of nano-structures by using a high-order nano-structure process, and on evaluation of micro region properties. Such nanocomposite bodies were selected for the object as piezoelectric ceramics PZT group (which increases mechanical characteristics and durability without impeding electric characteristics) and alumina-group YAG (which enhances high-temperature strength). Three-dimensional analyses were performed on particle morphology and crack structures by using focusing ion beams as a study on destruction behavior by means of microscopic and macroscopic particle morphology control. This paper reports the achievements of research and development on control of continuous small pore morphology (uni-directionally pierced pores on a new-type low expansion material used as matrix), intra-particle interface (discusses methods to micronize silicon nitride ceramics tissues), intra-layer interface (oxide-based ceramics are laminated on surface to improve oxidation and heat resistance without impeding high-temperature mechanical properties of non-oxide-based ceramics), intra-layer boundary (Pb-based double composition piezoelectric body having stable layer interface), and boundaries between inorganic and organic matters. (NEDO)

  7. Report on achievements in fiscal 1999. Research and development of synergy ceramics (research and development of ultra-high temperature gas turbine for power generation); 1999 nendo synergy ceramics no kenkyu kaihatsu seika hokokusho. Hatsuden'yo chokoon gas turbine no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    This research and development has been performed on the following themes: (1) high-temperature energy materials, (2) high-function active materials, (3) fundamental member material design technologies, (4) materials to activate specific environmental gases, (5) energy materials having high resistance to silicon groups, (6) porous multi-layer ceramic materials, (7) micro and macro applied analytic technologies, and (8) microscopically destructive analysis technologies. In Item 1, investigations were performed on the relationship of micro columnar particle structure of porous silicon nitride bodies with strength and destruction energy to identify the mechanism for manifestation of these characteristics. In Item 2, catalyst and electrode materials having the selectively separating and cleaning functions were developed, and materials to convert oxides thermo-electrically having high characteristics were discussed. In Item 3, polycrystalline alumina, polycrystalline zirconia, and zirconia particle dispersed alumina were fabricated on the trial basis to give them microscopic and macroscopic evaluations. In Item 4, crystalline hexa-aluminates in single phase were synthesized successfully. In Item 5, a synthesizing experiment was carried out on Ca-{alpha} sialon powder to evaluate and analyze the configuration phase of the product and the particle patterns. In Item 7, the homogenizing method was used to develop a three-dimensional program to analyze the correlation between the microscopic non-homogeneous structure and the macroscopic properties of synergy ceramics. In Item 8, the basic dimensions of porous alumina bodies were discussed based on energy density. (NEDO)

  8. Report on achievements in fiscal 1999. Research and development of synergy ceramics (research and development of ultra-high temperature gas turbine for power generation); 1999 nendo synergy ceramics no kenkyu kaihatsu seika hokokusho. Hatsuden'yo chokoon gas turbine no kenkyu kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    This research and development has been performed on the following themes: (1) high-temperature energy materials, (2) high-function active materials, (3) fundamental member material design technologies, (4) materials to activate specific environmental gases, (5) energy materials having high resistance to silicon groups, (6) porous multi-layer ceramic materials, (7) micro and macro applied analytic technologies, and (8) microscopically destructive analysis technologies. In Item 1, investigations were performed on the relationship of micro columnar particle structure of porous silicon nitride bodies with strength and destruction energy to identify the mechanism for manifestation of these characteristics. In Item 2, catalyst and electrode materials having the selectively separating and cleaning functions were developed, and materials to convert oxides thermo-electrically having high characteristics were discussed. In Item 3, polycrystalline alumina, polycrystalline zirconia, and zirconia particle dispersed alumina were fabricated on the trial basis to give them microscopic and macroscopic evaluations. In Item 4, crystalline hexa-aluminates in single phase were synthesized successfully. In Item 5, a synthesizing experiment was carried out on Ca-{alpha} sialon powder to evaluate and analyze the configuration phase of the product and the particle patterns. In Item 7, the homogenizing method was used to develop a three-dimensional program to analyze the correlation between the microscopic non-homogeneous structure and the macroscopic properties of synergy ceramics. In Item 8, the basic dimensions of porous alumina bodies were discussed based on energy density. (NEDO)

  9. Ultra-high temperature tensile properties of ODS steel claddings under severe accident conditions

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Y., E-mail: yano.yasuhide@jaea.go.jp [Japan Atomic Energy Agency, 4002, Narita-cho, Oarai-machi, Ibaraki, 311-1393 (Japan); Tanno, T.; Oka, H.; Ohtsuka, S.; Inoue, T.; Kato, S.; Furukawa, T.; Uwaba, T.; Kaito, T. [Japan Atomic Energy Agency, 4002, Narita-cho, Oarai-machi, Ibaraki, 311-1393 (Japan); Ukai, S.; Oono, N. [Materials Science and Engineering, Faculty of Engineering, Hokkaido University, N13, W-8, Kita-ku, Sapporo, Hokkaido, 060-8628 (Japan); Kimura, A. [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Hayashi, S. [Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Torimaru, T. [Nippon Nuclear Fuel Development Co., Ltd., 2163, Narita-cho, Oarai-machi, Ibaraki, 311-1313 (Japan)

    2017-04-15

    Ultra-high temperature ring tensile tests were performed to investigate the tensile behavior of oxide dispersion strengthened (ODS) steel claddings and wrapper materials under severe accident conditions with temperatures ranging from room temperature to 1400 °C which is close to the melting point of core materials. The experimental results showed that the tensile strength of 9Cr-ODS steel claddings was highest in the core materials at ultra-high temperatures of 900–1200 °C, but there was significant degradation in the tensile strength of 9Cr-ODS steel claddings above 1200 °C. This degradation was attributed to grain boundary sliding deformation with γ/δ transformation, which is associated with reduced ductility. By contrast, the tensile strength of recrystallized 12Cr-ODS and FeCrAl-ODS steel claddings retained its high value above 1200 °C, unlike the other tested materials.

  10. Ultra-high temperature tensile properties of ODS steel claddings under severe accident conditions

    Science.gov (United States)

    Yano, Y.; Tanno, T.; Oka, H.; Ohtsuka, S.; Inoue, T.; Kato, S.; Furukawa, T.; Uwaba, T.; Kaito, T.; Ukai, S.; Oono, N.; Kimura, A.; Hayashi, S.; Torimaru, T.

    2017-04-01

    Ultra-high temperature ring tensile tests were performed to investigate the tensile behavior of oxide dispersion strengthened (ODS) steel claddings and wrapper materials under severe accident conditions with temperatures ranging from room temperature to 1400 °C which is close to the melting point of core materials. The experimental results showed that the tensile strength of 9Cr-ODS steel claddings was highest in the core materials at ultra-high temperatures of 900-1200 °C, but there was significant degradation in the tensile strength of 9Cr-ODS steel claddings above 1200 °C. This degradation was attributed to grain boundary sliding deformation with γ/δ transformation, which is associated with reduced ductility. By contrast, the tensile strength of recrystallized 12Cr-ODS and FeCrAl-ODS steel claddings retained its high value above 1200 °C, unlike the other tested materials.

  11. Evaluating strength at ultra-high temperatures-Methods and results

    International Nuclear Information System (INIS)

    Voelkl, Rainer; Fischer, Bernd; Beschliesser, Manuel; Glatzel, Uwe

    2008-01-01

    Proprietary equipment for mechanical testing at ultra-high temperatures by ohmic heating is outlined. Strain is measured with a video extensometer with an accuracy of up to Δε-bar∼±0.00025%. Stability and accuracy of the test system are evaluated on Pt- and refractory alloys. These specially designed and built test facilities are compared to commercially available high-vacuum test chambers with tungsten heater

  12. Ultra high temperature latent heat energy storage and thermophotovoltaic energy conversion

    OpenAIRE

    Datas Medina, Alejandro; Ramos Cabal, Alba; Martí Vega, Antonio; Cañizo Nadal, Carlos del; Luque López, Antonio

    2016-01-01

    A conceptual energy storage system design that utilizes ultra high temperature phase change materials is presented. In this system, the energy is stored in the form of latent heat and converted to electricity upon demand by TPV (thermophotovoltaic) cells. Silicon is considered in this study as PCM (phase change material) due to its extremely high latent heat (1800 J/g or 500 Wh/kg), melting point (1410 C), thermal conductivity (~25 W/mK), low cost (less than $2/kg or $4/kWh) and a...

  13. Reactive Fusion Welding for Ultra-High Temperature Ceramic Composite Joining

    Science.gov (United States)

    2015-03-16

    istribution un lim it ed 13. SUPPLEMENTARY NOTES 14. ABSTRACT Plasm a and pulsed plasma arc w eld ing (PAW and PPAW) processes w ere used to fusion...were analyzed using scanning electron microscopy. 3.4 Microscopy Weldment specimens were cut perpendicular to the welding direction using a manual...Nikon; Epiphot 200; Tokyo, Japan) and scanning electron microscopy (Hitachi; S- 570; Tokyo, Japan). ZrB2 grain sizes in the parent material and heat

  14. Testing and Modeling Ultra-High Temperature Ceramic (UHTC) Materials for Hypersonic Flight

    Science.gov (United States)

    2011-11-01

    air flows was investigated in the 1.2 MW Plasmatron facility at the 1 von Kantian Institute for Fluid Dynamics (VKI). Samples manufactured by...surfaces (e.g., oxides) with refractive indices between 1 and 4, electromagnetic theory predicts differences of no more than ~5% between...model of a concept UHTC WLE section is shown in Fig. 1.) While not an achievable design in practice, in the context of supersonic flow theory , a

  15. Non-Contact Tabletop Mechanical Testing of Ultra-High Temperature Ceramics

    Science.gov (United States)

    2012-05-01

    can be treated as a Continuously Stirred Tank Reactor ( CSTR ) problem. The volume (V) of the environmental chamber is 2 xlO*3 m3 and the vacuum pump...shown below. If this arrangement is also considered as a CSTR problem, it is estimated to have an oxygen concentration as a function of time is

  16. Novel Routes for Sintering of Ultra-high Temperature Ceramics and their Properties

    Science.gov (United States)

    2014-10-31

    concentrations. As input components the zirconyl-nitrate ZrО(NO3)2 and cerium nitrate Сe(NO3)3∙6H2O of “pure” grade, nitric acid “pure for analysis...H. Gocmez, Hydrothermal synthesis and properties of Ce1-xGdxO2-δ solid solutions // Solid State Sciences. – 2002. – Vol. 4. – P. 585-590. 19. E...J. Kilner, Ionic conductivity in the CeO2-Gd2O3 system (0.05≤Gd/Ce≤0.4) prepared by oxalate coprecipitation // Solid State Ionics. - 2002. – Vol

  17. Novel Routes for Sintering of Ultra-high Temperature Ceramics and their Properties

    Science.gov (United States)

    2014-10-31

    Structural investigation was carried out on metallographic microscope MIM–10, x-ray phase analysis– x-ray device DRON –2. Microhardness was measured by MPT...high- temperature X-ray diffractometer DRON -UM1 with high-temperature device UVD- 2000 (temperature interval 290-830K) and monochromatic Cu-Kα

  18. Consideration of ultra-high temperature nuclear heat sources for MHD conversion systems

    International Nuclear Information System (INIS)

    Holman, R.R.; Tobin, J.M.; Young, W.E.

    1975-01-01

    The nuclear technology reactors developed and tested in the Nuclear Engine Rocket Vehicle Application (NERVA) program operated with fuel exit gas temperatures in excess of 2600 K. This experience provided a significant ultra-high temperature technology base and design insight for commercial power applications. Design approaches to accommodate fission product retention and other key prevailing requirements are examined in view of the basic overriding functional requirements, and some interesting reconsiderations are suggested. Predicted overall system performance potentials for a 2000 K MHD conversion system and reactor parameter requirements are compared and related to existing technology status. Needed verification and development efforts are suggested. A reconsideration of basic design approaches is suggested that could open the door for immediate development of ultrahigh temperature nuclear heat sources for advanced energy systems

  19. Optical Method for Detecting Displacements and Strains at Ultra-High Temperatures During Thermo-Mechanical Testing

    Science.gov (United States)

    Smith, Russell W. (Inventor); Rivers, H. Kevin (Inventor); Sikora, Joseph G. (Inventor); Roth, Mark C. (Inventor); Johnston, William M. (Inventor)

    2016-01-01

    An ultra-high temperature optical method incorporates speckle optics for sensing displacement and strain measurements well above conventional measurement techniques. High temperature pattern materials are used which can endure experimental high temperature environments while simultaneously having a minimum optical aberration. A purge medium is used to reduce or eliminate optical distortions and to reduce, and/or eliminate oxidation of the target specimen.

  20. 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.

  1. Generation, insulated confinement, and heating of ultra-high temperature plasmas

    International Nuclear Information System (INIS)

    Bass, R.W.

    1986-01-01

    This invention relates to the production and maintenance in steady state of ultra-high temperature confined plasmas, particularly those created by full ionization of a volume of some hydrogenic gas such as deuterium. The target mass is surrounded with an ambient fluid medium at a predetermined pressure. Pulsed energy is projected upon the target mass to bring it to a predetermined temperature and to fully ionize it; this energy may be pulsed photon energy or pulsed particle-beam kinetic energy. An electrostatic double layer is formed spontaneously between the ionized mass and the ambient medium, providing thermal insulation and leaving the dominant energy loss to be bremmstrahlung losses. The bremmstrahlung losses are compensated for completely by supplying additional radiant energy to the ionized mass to maintain its temperature. The frequency range of the additional radiant energy is selected so as to be absorbable by the ionized mass, and its power level is adjusted to maintain the ionized mass in a substantially steady state. The static pressure of the ambient medium is increased, thereby equally increasing the static pressure of the ionized mass so as to enable the mass to absorb more of the radiant energy and increasing its temperature but also increasing its power losses. Simultaneously the radius and temperature of the mass are monitored and the power level of the radiant energy supply is increased to as to compensate for the power losses. The minimum feasible size of the plasma is less than a centimeter in diameter, while there is no constraint on maximum feasible size. This invention may be practiced with commercially-available lasers and microwave beam generators

  2. Enhancing thermal reliability of fiber-optic sensors for bio-inspired applications at ultra-high temperatures

    International Nuclear Information System (INIS)

    Kang, Donghoon; Kim, Heon-Young; Kim, Dae-Hyun

    2014-01-01

    The rapid growth of bio-(inspired) sensors has led to an improvement in modern healthcare and human–robot systems in recent years. Higher levels of reliability and better flexibility, essential features of these sensors, are very much required in many application fields (e.g. applications at ultra-high temperatures). Fiber-optic sensors, and fiber Bragg grating (FBG) sensors in particular, are being widely studied as suitable sensors for improved structural health monitoring (SHM) due to their many merits. To enhance the thermal reliability of FBG sensors, thermal sensitivity, generally expressed as α f + ξ f and considered a constant, should be investigated more precisely. For this purpose, the governing equation of FBG sensors is modified using differential derivatives between the wavelength shift and the temperature change in this study. Through a thermal test ranging from RT to 900 °C, the thermal sensitivity of FBG sensors is successfully examined and this guarantees thermal reliability of FBG sensors at ultra-high temperatures. In detail, α f + ξ f has a non-linear dependence on temperature and varies from 6.0 × 10 −6  °C −1 (20 °C) to 10.6 × 10 −6  °C −1 (650 °C). Also, FBGs should be carefully used for applications at ultra-high temperatures due to signal disappearance near 900 °C. (paper)

  3. Enhancing thermal reliability of fiber-optic sensors for bio-inspired applications at ultra-high temperatures

    Science.gov (United States)

    Kang, Donghoon; Kim, Heon-Young; Kim, Dae-Hyun

    2014-07-01

    The rapid growth of bio-(inspired) sensors has led to an improvement in modern healthcare and human-robot systems in recent years. Higher levels of reliability and better flexibility, essential features of these sensors, are very much required in many application fields (e.g. applications at ultra-high temperatures). Fiber-optic sensors, and fiber Bragg grating (FBG) sensors in particular, are being widely studied as suitable sensors for improved structural health monitoring (SHM) due to their many merits. To enhance the thermal reliability of FBG sensors, thermal sensitivity, generally expressed as αf + ξf and considered a constant, should be investigated more precisely. For this purpose, the governing equation of FBG sensors is modified using differential derivatives between the wavelength shift and the temperature change in this study. Through a thermal test ranging from RT to 900 °C, the thermal sensitivity of FBG sensors is successfully examined and this guarantees thermal reliability of FBG sensors at ultra-high temperatures. In detail, αf + ξf has a non-linear dependence on temperature and varies from 6.0 × 10-6 °C-1 (20 °C) to 10.6 × 10-6 °C-1 (650 °C). Also, FBGs should be carefully used for applications at ultra-high temperatures due to signal disappearance near 900 °C.

  4. Sterilization of liquid foods by pulsed electric fields – an innovative ultra-high temperature process

    Directory of Open Access Journals (Sweden)

    Kai eReineke

    2015-05-01

    Full Text Available The intention of this study was to investigate the inactivation of endospores by a combined thermal and pulsed electric field (PEF treatment. Therefore, self-cultivated spores of Bacillus subtilis and commercial Geobacillus stearothermophilus spores with certified heat resistance were utilized. Spores of both strains were suspended in saline water (5.3 mS cm-1, skim milk (0.3% fat; 5.3 mS cm-1 and fresh prepared carrot juice (7.73 mS cm-1. The combination of moderate preheating (70-90 °C and an insulated PEF-chamber, combined with a holding tube (65 cm and a heat exchanger for cooling, enabled a rapid heat up to 105-140 °C (measured above the PEF chamber within 92.2-368.9 µs. To compare the PEF process with a pure thermal inactivation, each spore suspension was heat treated in thin glass capillaries and D-values from 90 to 130°C and its corresponding z-values were calculated. For a comparison of the inactivation data, F-values for the temperature fields of both processes were calculated by using Comsol Multiphysics combined with a Matlab routine.A preheating of saline water to 70 °C with a flow rate of 5 l h-1, a frequency of 150 Hz and an energy input of 226.5 kJ kg-1, resulted in a measured outlet temperature of 117 °C and a 4.67 log10 inactivation of Bacillus subtilis. The thermal process with identical F-value caused only a 3.71 log10 inactivation. This synergism of moderate preheating and PEF was even more pronounced for Geobacillus stearothermophilus spores in saline water. A preheating to 95 °C and an energy input of 144 kJ kg-1 resulted in an outlet temperature of 126 °C and a 3.28 log10 inactivation, whereas nearly no inactivation (0.2 log10 was achieved during the thermal treatment.Hence, the PEF technology was evaluated as an alternative ultra-high temperature process. However, for an industrial scale application of this process for sterilization, optimization of the treatment chamber design is needed to reduce the occurring

  5. Sterilization of liquid foods by pulsed electric fields–an innovative ultra-high temperature process

    Science.gov (United States)

    Reineke, Kai; Schottroff, Felix; Meneses, Nicolas; Knorr, Dietrich

    2015-01-01

    The intention of this study was to investigate the inactivation of endospores by a combined thermal and pulsed electric field (PEF) treatment. Therefore, self-cultivated spores of Bacillus subtilis and commercial Geobacillus stearothermophilus spores with certified heat resistance were utilized. Spores of both strains were suspended in saline water (5.3 mS cm−1), skim milk (0.3% fat; 5.3 mS cm−1) and fresh prepared carrot juice (7.73 mS cm−1). The combination of moderate preheating (70–90°C) and an insulated PEF-chamber, combined with a holding tube (65 cm) and a heat exchanger for cooling, enabled a rapid heat up to 105–140°C (measured above the PEF chamber) within 92.2–368.9 μs. To compare the PEF process with a pure thermal inactivation, each spore suspension was heat treated in thin glass capillaries and D-values from 90 to 130°C and its corresponding z-values were calculated. For a comparison of the inactivation data, F-values for the temperature fields of both processes were calculated by using computational fluid dynamics (CFD). A preheating of saline water to 70°C with a flow rate of 5 l h−1, a frequency of 150 Hz and an energy input of 226.5 kJ kg−1, resulted in a measured outlet temperature of 117°C and a 4.67 log10 inactivation of B. subtilis. The thermal process with identical F-value caused only a 3.71 log10 inactivation. This synergism of moderate preheating and PEF was even more pronounced for G. stearothermophilus spores in saline water. A preheating to 95°C and an energy input of 144 kJ kg−1 resulted in an outlet temperature of 126°C and a 3.28 log10 inactivation, whereas nearly no inactivation (0.2 log10) was achieved during the thermal treatment. Hence, the PEF technology was evaluated as an alternative ultra-high temperature process. However, for an industrial scale application of this process for sterilization, optimization of the treatment chamber design is needed to reduce the occurring inhomogeneous temperature

  6. Sterilization of liquid foods by pulsed electric fields-an innovative ultra-high temperature process.

    Science.gov (United States)

    Reineke, Kai; Schottroff, Felix; Meneses, Nicolas; Knorr, Dietrich

    2015-01-01

    The intention of this study was to investigate the inactivation of endospores by a combined thermal and pulsed electric field (PEF) treatment. Therefore, self-cultivated spores of Bacillus subtilis and commercial Geobacillus stearothermophilus spores with certified heat resistance were utilized. Spores of both strains were suspended in saline water (5.3 mS cm(-1)), skim milk (0.3% fat; 5.3 mS cm(-1)) and fresh prepared carrot juice (7.73 mS cm(-1)). The combination of moderate preheating (70-90°C) and an insulated PEF-chamber, combined with a holding tube (65 cm) and a heat exchanger for cooling, enabled a rapid heat up to 105-140°C (measured above the PEF chamber) within 92.2-368.9 μs. To compare the PEF process with a pure thermal inactivation, each spore suspension was heat treated in thin glass capillaries and D-values from 90 to 130°C and its corresponding z-values were calculated. For a comparison of the inactivation data, F-values for the temperature fields of both processes were calculated by using computational fluid dynamics (CFD). A preheating of saline water to 70°C with a flow rate of 5 l h(-1), a frequency of 150 Hz and an energy input of 226.5 kJ kg(-1), resulted in a measured outlet temperature of 117°C and a 4.67 log10 inactivation of B. subtilis. The thermal process with identical F-value caused only a 3.71 log10 inactivation. This synergism of moderate preheating and PEF was even more pronounced for G. stearothermophilus spores in saline water. A preheating to 95°C and an energy input of 144 kJ kg(-1) resulted in an outlet temperature of 126°C and a 3.28 log10 inactivation, whereas nearly no inactivation (0.2 log10) was achieved during the thermal treatment. Hence, the PEF technology was evaluated as an alternative ultra-high temperature process. However, for an industrial scale application of this process for sterilization, optimization of the treatment chamber design is needed to reduce the occurring inhomogeneous temperature fields.

  7. Continuous Solvothermal Synthesis and Surface Treatment for Improved and Scalable Processing of Ultra High Temperature Ceramic (UHTC) Nanopowders

    Science.gov (United States)

    2017-06-13

    interface coatings for SiC/SiC composites. This approach was found to be promising and deserves further evaluation in a systematic mode. 15. SUBJECT TERMS...approximately 200 words ) factual summary of the most significant information. 1 S. SUBJECT TERMS. Key words or phrases identifying major concepts in the...improved adhesion, wettability, electroactivity, and water -repellant qualities, among others. In these cases, the reactive bonding sites are already

  8. Advanced processing of gallium nitride and gallium nitride-based devices: Ultra-high temperature annealing and implantation incorporation

    Science.gov (United States)

    Yu, Haijiang

    This dissertation is focused on three fields: ultra-high temperature annealing of GaN, activation of implanted GaN and the implantation incorporation into AlGaN/GaN HEMT processing, with an aim to increase the performance, manufacturability and reliability of AlGaN/GaN HEMTs. First, the ultra high temperature (around 1500°C) annealing of MOCVD grown GaN on sapphire has been studied, and a thermally induced threading dislocation (TD) motion and reaction are reported. Using a rapid thermal annealing (RTA) approach capable of heating 2 inch wafers to around 1500°C with 100 bar N2 over-pressure, evidence of dislocation motion was first observed in transmission electron microscopy (TEM) micrographs of both planar and patterned GaN films protected by an AIN capping layer. An associated decrease in x-ray rocking curve (XRC) full-width-half-maximum (FWHM) was also observed for both the symmetric and asymmetric scans. After annealing, the AIN capping layer remained intact, and optical measurements showed no degradation of the opto-electronic properties of the films. Then activation annealing of Si implants in MOCVD grown GaN has been studied for use in ohmic contacts. Si was implanted in semi-insulating GaN at 100 keV with doses from 5 x 1014 cm-2 to 1.5 x 1016 cm-2. Rapid thermal annealing at 1500°C with 100 bar N2 over-pressure was used for dopant activation, resulting in a minimum sheet resistance of 13.9 O/square for a dose of 7 x 1015 cm-2. Secondary ion mass spectroscopy measurements showed a post-activation broadening of the dopant concentration peak by 20 nm (at half the maximum), while X-Ray triple axis o-2theta scans indicated nearly complete implant damage recovery. Transfer length method measurements of the resistance of Ti/Al/Ni/Au contacts to activated GaN:Si (5 x 1015 cm-2 at 100 keV) indicated lowest contact resistances of 0.07 Omm and 0.02 Omm for as-deposited and subsequently annealed contacts, respectively. Finally, the incorporation of Si implantation

  9. Neutronics and Thermal Hydraulics Analysis of a Conceptual Ultra-High Temperature MHD Cermet Fuel Core for Nuclear Electric Propulsion

    Directory of Open Access Journals (Sweden)

    Jian Song

    2018-04-01

    Full Text Available Nuclear electric propulsion (NEP offers unique advantages for the interplanetary exploration. The extremely high conversion efficiency of magnetohydrodynamics (MHD conversion nuclear reactor makes it a highly potential space power source in the future, especially for NEP systems. Research on ultra-high temperature reactor suitable for MHD power conversion is performed in this paper. Cermet is chosen as the reactor fuel after a detailed comparison with the (U,ZrC graphite-based fuel and mixed carbide fuel. A reactor design is carried out as well as the analysis of the reactor physics and thermal-hydraulics. The specific design involves fuel element, reactor core, and radiation shield. Two coolant channel configurations of fuel elements are considered and both of them can meet the demands. The 91 channel configuration is chosen due to its greater heat transfer performance. Besides, preliminary calculation of nuclear criticality safety during launch crash accident is also presented. The calculation results show that the current design can meet the safety requirements well.

  10. A novel fibre Bragg grating sensor packaging design for ultra-high temperature sensing in harsh environments

    Science.gov (United States)

    Azhari, Amir; Liang, Richard; Toyserkani, Ehsan

    2014-07-01

    The aim of this article is to introduce a novel packaging of conventional Corning SMF-28™ single-mode fibre Bragg grating sensors for ultra-high temperature sensing. The package is in a cylindrical shape made of yttria-stabilized zirconia tubes. The fibre optic sensor is epoxied to one end inside the tube to be protected from high external temperatures and also harsh environments. Highly-oriented pyrolytic graphite tube with an exceptional anisotropic thermal conductivity with higher conductivity in transverse than radial direction is positioned around the fibre to protect it from high temperatures. Air cooling system is also provided from the other end to dissipate the transferred heat from inside the tube. The shift in the Bragg wavelength is influenced by the thermal expansion of the package and internal temperature variations, which translates into thermal expansion of the fibre. The modelling and experimental results revealed that the Bragg wavelength shift increases to 1.4 pm °C-1 at higher temperatures with linear behaviour at temperatures above 600 °C. The finite element modelling and the experimental results are also in good proximity indicating the similar trend for the shift in the Bragg wavelength.

  11. A Delay Time Measurement of ULTRAS (Ultra-high Temperature Ultrasonic Response Analysis System) for a High Temperature Experiment

    International Nuclear Information System (INIS)

    Koo, Kil Mo; Kim, Sang Baik

    2010-01-01

    The temperature measurement of very high temperature core melt is of importance in a high temperature as the molten pool experiment in which gap formation between core melt and the reactor lower head, and the effect of the gap on thermal behavior are to be measured. The existing temperature measurement techniques have some problems, which the thermocouple, one of the contact methods, is restricted to under 2000 .deg. C, and the infrared thermometry, one of the non-contact methods, is unable to measure an internal temperature and very sensitive to the interference from reacted gases. In order to solve these problems, the delay time technique of ultrasonic wavelets due to high temperature has two sorts of stage. As a first stage, a delay time measurement of ULTRAS (Ultra-high Temperature Ultrasonic Response Analysis System) is suggested. As a second stage, a molten material temperature was measured up to 2300 .deg. C. Also, the optimization design of the UTS (ultrasonic temperature sensor) with persistence at the high temperature was suggested in this paper. And the utilization of the theory suggested in this paper and the efficiency of the developed system are performed by special equipment and some experiments supported by KRISS (Korea Research Institute of Standard and Science)

  12. Electrophoretic characterization of protein interactions suggesting limited feasibility of accelerated shelf-life testing of ultra-high temperature milk.

    Science.gov (United States)

    Grewal, Manpreet Kaur; Chandrapala, Jayani; Donkor, Osaana; Apostolopoulos, Vasso; Vasiljevic, Todor

    2017-01-01

    Accelerated shelf-life testing is applied to a variety of products to estimate keeping quality over a short period of time. The industry has not been successful in applying this approach to ultra-high temperature (UHT) milk because of chemical and physical changes in the milk proteins that take place during processing and storage. We investigated these protein changes, applying accelerated shelf-life principles to UHT milk samples with different fat levels and using native- and sodium dodecyl sulfate-PAGE. Samples of UHT skim and whole milk were stored at 20, 30, 40, and 50°C for 28d. Irrespective of fat content, UHT treatment had a similar effect on the electrophoretic patterns of milk proteins. At the start of testing, proteins were bonded mainly through disulfide and noncovalent interactions. However, storage at and above 30°C enhanced protein aggregation via covalent interactions. The extent of aggregation appeared to be influenced by fat content; whole milk contained more fat than skim milk, implying aggregation via melted or oxidized fat, or both. Based on reduction in loss in absolute quantity of individual proteins, covalent crosslinking in whole milk was facilitated mainly by products of lipid oxidation and increased access to caseins for crosslinking reactions. Maillard and dehydroalanine products were the main contributors involved in protein changes in skim milk. Protein crosslinking appeared to follow a different pathway at higher temperatures (≥40°C) than at lower temperatures, making it very difficult to extrapolate these changes to protein interactions at lower temperatures. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  13. Analysis and fabrication of tungsten CERMET materials for ultra-high temperature reactor applications via pulsed electric current sintering

    Science.gov (United States)

    Webb, Jonathan A.

    The optimized development path for the fabrication of ultra-high temperature W-UO2 CERMET fuel elements were explored within this dissertation. A robust literature search was conducted, which concluded that a W-UO 2 fuel element must contain a fine tungsten microstructure and spherical UO2 kernels throughout the entire consolidation process. Combined Monte Carlo and Computational Fluid Dynamics (CFD) analysis were used to determine the effects of rhenium and gadolinia additions on the performance of W-UO 2 fuel elements at refractory temperatures and in dry and water submerged environments. The computational analysis also led to the design of quasi-optimized fuel elements that can meet thermal-hydraulic and neutronic requirements A rigorous set of experiments were conducted to determine if Pulsed Electric Current Sintering (PECS) can fabricate tungsten and W-Ce02 specimens to the required geometries, densities and microstructures required for high temperature fuel elements as well as determine the mechanisms involved within the PECS consolidation process. The CeO2 acts as a surrogate for UO 2 fuel kernels in these experiments. The experiments seemed to confirm that PECS consolidation takes place via diffusional mass transfer methods; however, the densification process is rapidly accelerated due to the effects of current densities within the consolidating specimen. Fortunately the grain growth proceeds at a traditional rate and the PECS process can yield near fully dense W and W-Ce02 specimens with a finer microstructure than other sintering techniques. PECS consolidation techniques were also shown to be capable of producing W-UO2 segments at near-prototypic geometries; however, great care must be taken to coat the fuel particles with tungsten prior to sintering. Also, great care must be taken to ensure that the particles remain spherical in geometry under the influence of a uniaxial stress as applied during PECS, which involves mixing different fuel kernel sizes in

  14. The Integration Method of Ceramic Arts in the Product Design

    Science.gov (United States)

    Shuxin, Wang

    2018-03-01

    As one of the four ancient civilization countries, the firing technology of ceramic invented by China has made a great contribution to the progress and development of human society. In modern life, even the development of technology still needs the ceramics, there are large number of artists who take the ceramics as carrier active in the field of contemporary art. The ceramics can be seen everywhere in our daily life, this paper mainly discusses the integration means of ceramic art in the product design.

  15. Measurement of Creep Properties of Ultra-High-Temperature Materials by a Novel Non-Contact Technique

    Science.gov (United States)

    Hyers, Robert W.; Lee, Jonghyun; Rogers, Jan R.; Liaw, Peter K.

    2007-01-01

    A non-contact technique for measuring the creep properties of materials has been developed and validated as part of a collaboration among the University of Massachusetts, NASA Marshall Space Flight Center Electrostatic Levitation Facility (ESL), and the University of Tennessee. This novel method has several advantages over conventional creep testing. The sample is deformed by the centripetal acceleration from the rapid rotation, and the deformed shapes are analyzed to determine the strain. Since there is no contact with grips, there is no theoretical maximum temperature and no concern about chemical compatibility. Materials may be tested at the service temperature even for extreme environments such as rocket nozzles, or above the service temperature for accelerated testing of materials for applications such as jet engines or turbopumps for liquid-fueled engines. The creep measurements have been demonstrated to 2400 C with niobium, while the test facility, the NASA MSFC ESL, has processed materials up to 3400 C. Furthermore, the ESL creep method employs a distribution of stress to determine the stress exponent from a single test, versus the many tests required by conventional methods. Determination of the stress exponent from the ESL creep tests requires very precise measurement of the surface shape of the deformed sample for comparison to deformations predicted by finite element models for different stress exponents. An error analysis shows that the stress exponent can be determined to about 1% accuracy with the current methods and apparatus. The creep properties of single-crystal niobium at 1985 C showed excellent agreement with conventional tests performed according to ASTM Standard E-139. Tests on other metals, ceramics, and composites relevant to rocket propulsion and turbine engines are underway.

  16. Fiscal 1997 survey report. Subtask 8 (hydrogen utilization worldwide clean energy system technology) (WE-NET) (R and D of hydrogen combustion turbines/development of ultra-high temperature materials); 1997 nendo seika hokokusho. Suiso riyo kokusai clean energy system gijutsu (WE-NET) subtask 8 suiso nensho turbine kenkyu kaihatsu chokoon zairyo no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    For the application to hydrogen combustion turbines, the R and D were continued of heat resistant alloys, ceramic composite materials, and carbonaceous composite materials. In the development of highly efficient super alloy single crystal materials, as to the single crystal alloy (Ni-5.3Al-0.5Ti-6.0Mo-4.8W-6.0Re) and an alloy made by adding 0.15%Si to the above alloy and an alloy made by adding 2.0%Hf to the above alloy, data on high temperature tensile property and creep rupture property were obtained, and it was confirmed that Hf added alloys were excellent in strength. Relating to the development of fiber reinforced ceramics, materials for trial fabrication were fabricated by the CVI method using SiC fiber, and the evaluation test was conducted to obtain the basic data. Besides, the following were carried out: study of coating for heat resistant alloy cooled blades, development of ceramic composite materials, development of ceramic multi-structure materials and analysis of fracture behaviors under the ultra-high composite environment, development of 3D fiber reinforced composite materials, development of technology to evaluate basic properties of ultra-high temperature materials, etc. 46 refs., 217 figs., 43 tabs.

  17. Ultra high-temperature solids-free insulating packer fluid for oil and gas production, steam injection and geothermal wells

    Energy Technology Data Exchange (ETDEWEB)

    Ezell, R.G.; Harrison, D.J. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Halliburton Energy Services, Calgary, AB (Canada)

    2008-10-15

    Uncontrolled heat transfer from production/injection tubing during thermal oil recovery via steam injection can be detrimental to the integrity of the casing and to the quality of the steam that is injected into the reservoir. An aqueous-based insulating packer fluid (IPF) was introduced to improve the steam injection process by controlling the total heat loss from the produced fluids to the surrounding wellbore, internal annuli and formation. The IPF was developed for elevated temperature environments through extensive investigation across multidisciplinary technology. The innovative system delivers performance beyond conventional systems of comparable thermal conductivity. Its density range and conductivity measurements were presented in this paper. High-temperature static aging tests showed superior gel integrity without any phase separation after exposure to temperatures higher than 260 degrees C. The new fluids are hydrate inhibitive, non-corrosive and pass oil and grease testing. They are considered to be environmentally sound by Gulf of Mexico standards. It was concluded that the new ultra high-performance insulating packer fluid (HTIPF) reduced the heat loss significantly by both conduction and convection. Heat transfer within the aqueous-based HTIPF was 97 per cent less than that of pure water. It was concluded that the HTIPF can be substituted for conventional packer fluids without compromising any well control issues. 21 refs., 1 tab., 4 figs.

  18. Integral ceramic superstructure evaluation using time domain optical coherence tomography

    Science.gov (United States)

    Sinescu, Cosmin; Bradu, Adrian; Topala, Florin I.; Negrutiu, Meda Lavinia; Duma, Virgil-Florin; Podoleanu, Adrian G.

    2014-02-01

    Optical Coherence Tomography (OCT) is a non-invasive low coherence interferometry technique that includes several technologies (and the corresponding devices and components), such as illumination and detection, interferometry, scanning, adaptive optics, microscopy and endoscopy. From its large area of applications, we consider in this paper a critical aspect in dentistry - to be investigated with a Time Domain (TD) OCT system. The clinical situation of an edentulous mandible is considered; it can be solved by inserting 2 to 6 implants. On these implants a mesostructure will be manufactured and on it a superstructure is needed. This superstructure can be integral ceramic; in this case materials defects could be trapped inside the ceramic layers and those defects could lead to fractures of the entire superstructure. In this paper we demonstrate that a TD-OCT imaging system has the potential to properly evaluate the presence of the defects inside the ceramic layers and those defects can be fixed before inserting the prosthesis inside the oral cavity. Three integral ceramic superstructures were developed by using a CAD/CAM technology. After the milling, the ceramic layers were applied on the core. All the three samples were evaluated by a TD-OCT system working at 1300 nm. For two of the superstructures evaluated, no defects were found in the most stressed areas. The third superstructure presented four ceramic defects in the mentioned areas. Because of those defects the superstructure may fracture. The integral ceramic prosthesis was send back to the dental laboratory to fix the problems related to the material defects found. Thus, TD-OCT proved to be a valuable method for diagnosing the ceramic defects inside the integral ceramic superstructures in order to prevent fractures at this level.

  19. The Heart of China revisited: II Early Paleozoic (ultra)high-pressure and (ultra)high-temperature metamorphic Qinling orogenic collage

    Science.gov (United States)

    Bader, Thomas; Franz, Leander; Ratschbacher, Lothar; de Capitani, Christian; Webb, A. Alexander G.; Yang, Zhao; Pfänder, Jörg A.; Hofmann, Mandy; Linnemann, Ulf

    2013-07-01

    Orogens with multiple (ultra)high-pressure ((U)HP) and (ultra)high-temperature ((U)HT) metamorphic events provide a complex but telling record of oceanic and continental interaction. The Early Paleozoic history of the "Heart of China," the Qinling orogenic collage, offers snapshots of at least three (U)HP and two (U)HT metamorphic events. The preservation of remnants of both oceanic and continental domains together with a ≥110 Myr record of magmatism allows the reconstruction of the processes that resulted in this disparate metamorphism. Herein, we first illuminate the pressure-temperature-time (P-T-t) evolution of the Early Paleozoic (U)HP and (U)HT events by refining the petrographic descriptions and P-T estimates, assess published, and employ new U/Th-Pb zircon, monazite, and titanite, and 40Ar-39Ar phengite geochronology to date the magmatic and metamorphic events. Then we explore how the metamorphic and magmatic events are related tectonically and how they elucidate the affinities among the various complexes in the Qinling orogenic collage. We argue that a Meso-Neoproterozoic crustal fragment—the Qinling complex—localized subduction-accretion events that involved subduction, oceanic-arc formation, and back-arc spreading along its northern margin, and mtantle-wedge exhumation and spreading-ridge subduction along its southern margin.

  20. Taking water-based mud to extremes : new ultra-high temperature water-based mud development and applications in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Conn, L.; Cullum, D.; Ray, R.; Marinescu, P. [Mi SWACO, Calgary, AB (Canada)

    2008-07-01

    The design, development and field applications of an ultra-high temperature water-based mud used for drilling very deep and hot wells in continental Europe was described. Basin-centred gas production from unconventional tight sands represents a significant resources that may revive exploration and gas production. However, these accumulations lie deep down from normal-pressure reservoirs and the bottom hole static temperatures are greater than 200 degrees C. In addition, they host acid gases such as carbon dioxide and hydrogen sulfide. As such, there are severe limitations on the design and choice of drilling fluids. This paper also described the extensive laboratory work that is needed to optimize the formulation of drilling fluids for high densities and extreme high temperatures. The lessons learned were described with reference to critical engineering guidelines for running a water-based system in such harsh conditions. The effectiveness of new fluids in delivering optimum drilling in extreme high temperature high pressure (HTHP) conditions were demonstrated using a unique software program that predicted the rheological behaviour, pressure losses, equivalent circulating density and equivalent static density. The new water-based system proved to be effective in drilling HTHP wells in areas where invert emulsion drilling fluid systems are not allowed.

  1. Effect of seasonal variation on some physical properties and heat stability of milk subjected to ultra-high temperature and in-container sterilisation.

    Science.gov (United States)

    Chen, Biye; Grandison, Alistair S; Lewis, Michael J

    2015-08-15

    Heat stability was evaluated in bulk raw milk, collected throughout the year and subjected to ultra-high temperature (UHT) or in-container sterilisation, with and without added calcium chloride (2mM), disodium hydrogen phosphate (DSHP, 10mM) and trisodium citrate (TSC, 10mM). More sediment was observed following in-container sterilisation (0.24%) compared with UHT (0.19%). Adding CaCl2 made the milk more unstable to UHT than to in-container sterilisation, while adding DSHP and TSC made the milk more unstable during in-container sterilisation than to UHT processing, although TSC addition increased the sediment formed by UHT processing. Better heat stability was observed in autumn and winter than in spring and summer following UHT. However, following in-container sterilisation, samples with added stabilising salts showed significantly improved heat stability in autumn, whereas with added CaCl2, the best heat stability was observed in spring. No correlation was found between urea and heat stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Mechanical Testing of Ultra-High Temperature Ceramics at 1500 C in Air - Development of an Experimental Facility and Test Method

    Science.gov (United States)

    2015-03-26

    v ~ Dedication With God All Things Are Possible Thank you for my mom and dad . Thank you for the love and support...and manufacture the carbide-based UHTCs to sufficient density [14]. The transition-metal nitrides also displayed poor oxidation resistance. In an... rich layer [32,41,47,49-52]. At temperatures below 1100°C, the oxidation rate of SiC is several orders of magnitude slower than that of diborides

  3. Ceramic Integration Technologies for Advanced Energy Systems: Critical Needs, Technical Challenges, and Opportunities

    Science.gov (United States)

    Singh, Mrityunjay

    2010-01-01

    Advanced ceramic integration technologies dramatically impact the energy landscape due to wide scale application of ceramics in all aspects of alternative energy production, storage, distribution, conservation, and efficiency. Examples include fuel cells, thermoelectrics, photovoltaics, gas turbine propulsion systems, distribution and transmission systems based on superconductors, nuclear power generation and waste disposal. Ceramic integration technologies play a key role in fabrication and manufacturing of large and complex shaped parts with multifunctional properties. However, the development of robust and reliable integrated systems with optimum performance requires the understanding of many thermochemical and thermomechanical factors, particularly for high temperature applications. In this presentation, various needs, challenges, and opportunities in design, fabrication, and testing of integrated similar (ceramic ceramic) and dissimilar (ceramic metal) material www.nasa.gov 45 ceramic-ceramic-systems have been discussed. Experimental results for bonding and integration of SiC based Micro-Electro-Mechanical-Systems (MEMS) LDI fuel injector and advanced ceramics and composites for gas turbine applications are presented.

  4. Integration of semiconductor and ceramic superconductor devices for microwave applications

    NARCIS (Netherlands)

    Klopman, B.B.G.; Klopman, B.B.G.; Wijers, H.W.; Gao, J.; Gao, J.; Gerritsma, G.J.; Rogalla, Horst

    1991-01-01

    Due to the very-low-loss properties of ceramic superconductors, high-performance microwave resonators and filters can be realized. The fact that these devices may be operated at liquid nitrogen temperature facilitates integration with semiconductor devices. Examples are bandpass amplifiers,

  5. Integration Science and Technology of Silicon-Based Ceramics and Composites:Technical Challenges and Opportunities

    Science.gov (United States)

    Singh, M.

    2013-01-01

    Ceramic integration technologies enable hierarchical design and manufacturing of intricate ceramic and composite parts starting with geometrically simpler units that are subsequently joined to themselves and/or to metals to create components with progressively higher levels of complexity and functionality. However, for the development of robust and reliable integrated systems with optimum performance for high temperature applications, detailed understanding of various thermochemical and thermomechanical factors is critical. Different technical approaches are required for the integration of ceramic to ceramic and ceramic to metal systems. Active metal brazing, in particular, is a simple and cost-effective method to integrate ceramic to metallic components. Active braze alloys usually contain a reactive filler metal (e.g., Ti, Cr, V, Hf etc) that promotes wettability and spreading by inducing chemical reactions with the ceramics and composites. In this presentation, various examples of brazing of silicon nitride to themselves and to metallic systems are presented. Other examples of joining of ceramic composites (C/SiC and SiC/SiC) using ceramic interlayers and the resulting microstructures are also presented. Thermomechanical characterization of joints is presented for both types of systems. In addition, various challenges and opportunities in design, fabrication, and testing of integrated similar (ceramic-ceramic) and dissimilar (ceramic-metal) material systems will be discussed. Potential opportunities and need for the development of innovative design philosophies, approaches, and integrated system testing under simulated application conditions will also be presented.

  6. Integration of semiconductor and ceramic superconductor devices for microwave applications

    International Nuclear Information System (INIS)

    Klopman, B.B.G.; Weijers, H.W.; Gao, J.; Gerritsma, G.J.; Rogalla, H.

    1991-01-01

    Due to the very low-loss properties of ceramic superconductors high-performance microwave resonators and filters can be realized. The fact that these devices may be operated at liquid nitrogen temperature, facilitates the integration with semiconductor devices. Examples are bandpass amplifiers, microwave-operated SQUIDs combined with GaAs preamplifiers, detectors, and MOSFET low-frequency amplifiers. This paper discusses the design of such circuits on a single one inch alumina substrate using surface mount techniques. Furthermore data on circuits that have been realized in our laboratory will be presented

  7. Integration Science and Technology of Advanced Ceramics for Energy and Environmental Applications

    Science.gov (United States)

    Singh, M.

    2012-01-01

    The discovery of new and innovative materials has been known to culminate in major turning points in human history. The transformative impact and functional manifestation of new materials have been demonstrated in every historical era by their integration into new products, systems, assemblies, and devices. In modern times, the integration of new materials into usable products has a special relevance for the technological development and economic competitiveness of industrial societies. Advanced ceramic technologies dramatically impact the energy and environmental landscape due to potential wide scale applications in all aspects of energy production, storage, distribution, conservation, and efficiency. Examples include gas turbine propulsion systems, fuel cells, thermoelectrics, photovoltaics, distribution and transmission systems based on superconductors, nuclear power generation, and waste disposal. Robust ceramic integration technologies enable hierarchical design and manufacturing of intricate ceramic components starting with geometrically simpler units that are subsequently joined to themselves and/or to metals to create components with progressively higher levels of complexity and functionality. However, for the development of robust and reliable integrated systems with optimum performance under different operating conditions, the detailed understanding of various thermochemical and thermomechanical factors is critical. Different approaches are required for the integration of ceramic-metal and ceramic-ceramic systems across length scales (macro to nano). In this presentation, a few examples of integration of ceramic to metals and ceramic to ceramic systems will be presented. Various challenges and opportunities in design, fabrication, and testing of integrated similar (ceramic-ceramic) and dissimilar (ceramic-metal) material systems will be discussed. Potential opportunities and need for the development of innovative design philosophies, approaches, and

  8. Microcoil Spring Interconnects for Ceramic Grid Array Integrated Circuits

    Science.gov (United States)

    Strickland, S. M.; Hester, J. D.; Gowan, A. K.; Montgomery, R. K.; Geist, D. L.; Blanche, J. F.; McGuire, G. D.; Nash, T. S.

    2011-01-01

    As integrated circuit miniaturization trends continue, they drive the need for smaller higher input/output (I/O) packages. Hermetically sealed ceramic area array parts are the package of choice by the space community for high reliability space flight electronic hardware. Unfortunately, the coefficient of thermal expansion mismatch between the ceramic area array package and the epoxy glass printed wiring board limits the life of the interconnecting solder joint. This work presents the results of an investigation by Marshall Space Flight Center into a method to increase the life of this second level interconnection by the use of compliant microcoil springs. The design of the spring and its attachment process are presented along with thermal cycling results of microcoil springs (MCS) compared with state-of-the-art ball and column interconnections. Vibration testing has been conducted on MCS and high lead column parts. Radio frequency simulation and measurements have been made and the MCS has been modeled and a stress analysis performed. Thermal cycling and vibration testing have shown MCS interconnects to be significantly more reliable than solder columns. Also, MCS interconnects are less prone to handling damage than solder columns. Future work that includes shock testing, incorporation into a digital signal processor board, and process evaluation of expansion from a 400 I/O device to a device with over 1,100 I/O is identified.

  9. 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

  10. Ultra-High Temperature Distributed Wireless Sensors

    Energy Technology Data Exchange (ETDEWEB)

    May, Russell; Rumpf, Raymond; Coggin, John; Davis, Williams; Yang, Taeyoung; O' Donnell, Alan; Bresnahan, Peter

    2013-03-31

    Research was conducted towards the development of a passive wireless sensor for measurement of temperature in coal gasifiers and coal-fired boiler plants. Approaches investigated included metamaterial sensors based on guided mode resonance filters, and temperature-sensitive antennas that modulate the frequency of incident radio waves as they are re-radiated by the antenna. In the guided mode resonant filter metamaterial approach, temperature is encoded as changes in the sharpness of the filter response, which changes with temperature because the dielectric loss of the guided mode resonance filter is temperature-dependent. In the mechanically modulated antenna approach, the resonant frequency of a vibrating cantilever beam attached to the antenna changes with temperature. The vibration of the beam perturbs the electrical impedance of the antenna, so that incident radio waves are phase modulated at a frequency equal to the resonant frequency of the vibrating beam. Since the beam resonant frequency depends on temperature, a Doppler radar can be used to remotely measure the temperature of the antenna. Laboratory testing of the guided mode resonance filter failed to produce the spectral response predicted by simulations. It was concluded that the spectral response was dominated by spectral reflections of radio waves incident on the filter. Laboratory testing of the mechanically modulated antenna demonstrated that the device frequency shifted incident radio waves, and that the frequency of the re-radiated waves varied linearly with temperature. Radio wave propagation tests in the convection pass of a small research boiler plant identified a spectral window between 10 and 13 GHz for low loss propagation of radio waves in the interior of the boiler.

  11. Characterization of Ultra-high Temperature Ceramics via Transmission Electron Microscopy Relevant ZrB2-based Composites, TaC-based Composites and Oxides Containing SiC Chopped Fibers

    Science.gov (United States)

    2015-03-06

    humidity in the environment. This feature is quite surprising, since B2O3 has low vapor tension and evaporates above 1000°C. The fact that we still see...platelets leaving clean grain boundaries with the matrix. According to the model proposed by Xu et al. 44 α-SiC nucleates heterogeneously at twin...boundaries, stacking faults and twins, as these planar faults resemble local regions of α-SiC and therefore facilitate its nucleation . As thermal

  12. Marginal Integrity of Glass Ionomer and All Ceramic Restorations

    Science.gov (United States)

    2015-06-01

    North Carolina), scanned by the CEREC Omnicam , and milled by CEREC inLab MC XL system. 15 List of Procedures in Chronological Order 1. The...Fuji II LC, GC America, Alsip, Illinois). Forty lithium disilicate porcelain ceramic inlays will be milled from CEREC Block PC (Sirona, Charlotte...evolution of the CEREC system. Journal of the American Dental Association, 137, 7s-13s. Mount G.J. (1991). Adhesion of glass-ionomer cement in the clinical

  13. Hydrogen utilization international clean energy system technology (WE-NET). Subtask 8. Research and development of hydrogen combustion turbines (development of ultra-high temperature materials); Suiso riyo kokusai clean energy system (WE-NET). Subtask 8. Suiso nensho turbine no kenkyu kaihatsu chokoon zairyo no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    The paper described the result of the fiscal 1996 development of ultra-high temperature materials for parts of hydrogen combustion turbines, as part of the hydrogen utilization technology, which have excellent environmental protectivity and remarkably high efficiency. By the optimized solution heat treatment of monocrystal alloy developed in the previous fiscal year, obtained was strength property the same as the existing super alloys. As to FRC, pore size and strength property of SiC organic hybrid were made clear. ODS alloy cooling blades and heat insulation coating were studied, and YSZ was found to be most excellent as coating material. Concerning intermetallic compounds, the applicability to ultra-high temperatures up to 1700degC was not obtained. For improvement of heat resistance and environment resistance, adopted were highly compacting SiC matrix and BN coatings. Al2O3 was excellent in long-time stability. In the 1600degC steam corrosion test on multiplex structural materials with Al2O3 as surface material, chemical stability was confirmed. Three-dimensional woven fiber reinforced composite materials of C/C{center_dot}CMC were trially produced by changing the fiber orientation, and improvement in ultra-high temperature thermal shock resistance was confirmed. A study was made of spot observation of the specimen surface by laser microscope, and development was conducted of a temperature measuring method with no influence of radiant heat. 44 refs., 250 figs., 40 tabs.

  14. Integrated Design Software Predicts the Creep Life of Monolithic Ceramic Components

    Science.gov (United States)

    1996-01-01

    Significant improvements in propulsion and power generation for the next century will require revolutionary advances in high-temperature materials and structural design. Advanced ceramics are candidate materials for these elevated-temperature applications. As design protocols emerge for these material systems, designers must be aware of several innate features, including the degrading ability of ceramics to carry sustained load. Usually, time-dependent failure in ceramics occurs because of two different, delayedfailure mechanisms: slow crack growth and creep rupture. Slow crack growth initiates at a preexisting flaw and continues until a critical crack length is reached, causing catastrophic failure. Creep rupture, on the other hand, occurs because of bulk damage in the material: void nucleation and coalescence that eventually leads to macrocracks which then propagate to failure. Successful application of advanced ceramics depends on proper characterization of material behavior and the use of an appropriate design methodology. The life of a ceramic component can be predicted with the NASA Lewis Research Center's Ceramics Analysis and Reliability Evaluation of Structures (CARES) integrated design programs. CARES/CREEP determines the expected life of a component under creep conditions, and CARES/LIFE predicts the component life due to fast fracture and subcritical crack growth. The previously developed CARES/LIFE program has been used in numerous industrial and Government applications.

  15. Atividade de plasmina e plasminogênio no leite longa vida com alta e baixa contagem de células somáticas durante o armazenamento Activity of plasmin and plasminogen in ultra high temperature milk with high and low somatic cell counts during storage

    Directory of Open Access Journals (Sweden)

    Carlos Humberto Corassin

    2010-12-01

    Full Text Available O objetivo deste estudo foi avaliar o efeito da contagem de células somáticas (CCS do leite na atividade de plasmina e plasminogênio durante o período de armazenamento do leite longa vida integral. Os leites crus foram categorizados em grupos de CCS de baixa (342.000-487.000 células mL-1 e alta contagem (603.000-808.000 células mL-1. Dois lotes de leite longa vida em cada categoria de CCS foram analisados para determinação de plasmina e plasminogênio após 10, 30, 60, 90 e 120 dias de armazenamento em temperatura ambiente. Para a fabricação do leite longa vida, o leite cru foi submetido à pasteurização rápida seguida da esterilização industrial do leite por injeção de vapor pelo método direto e embalagem asséptica do produto. A CCS não apresentou efeitos sobre as características físico-químicas do leite cru, e nem sobre a atividade de plasmina e plasminogênio nos leites cru e longa vida, armazenados por 120 dias. Entretanto, independentemente da CCS, a atividade de plasmina e plasminogênio aumentou no leite longa vida ao longo do armazenamento, indicando a possibilidade de aumento da proteólise no produto durante sua vida de prateleira.This study aimed to evaluate the effect of somatic cell counts (SCC in milk on plasmin and plasminogen activities of ultra high temperature (UHT milk during storage. Raw milks were categorized in SCC groups of low (342,000-487,000 cells mL-1 and high cells (603,000-808,000 cells mL-1. Two replicates of UHT milks within each SCC category were analyzed for plasmin and plasminogen activities after 10, 30, 60, 90 and 120 days of storage at room temperature. For manufacture of UHT milk, raw milk was pasteurized and sterilized by direct vapor injection process, followed by aseptic packaging. SCC had no effect on physical-chemical characteristics of raw milk, and on plasmin or plasminogen activities in raw and UHT milks during 120 days of storage. However, independently of the SCC in raw milk

  16. Architectural integration of energy solar collectors made with ceramic materials and suitable for the Mediterranean climate

    Directory of Open Access Journals (Sweden)

    J. Roviras

    2016-12-01

    Full Text Available The work presented here aims to demonstrate the technical, architectural and energy viability of solar thermal collectors made with ceramic materials and the Mediterranean climate suitable for the production of domestic hot water (DHW and for heating systems in buildings. The design of a ceramic shell formed by panels collectors and panels no sensors, which are part of the same building system that is capable of responding to the basic requirements of a building envelope and capture solar energy is proposed. Ceramics considerably reduced the final cost of the sensor system and offers the new system a variety of compositional and chromatic since, with reduced performance compared to a conventional metallic collector, can occupy the entire surface of front and get a high degree of architectural integration. A tool for assessing the new ceramic solar collector has been defined from a multi-criteria perspective: economic, environmental and social. The tool enables the comparison of the ceramic solar collector with solar collectors on the market under different climatic and demand conditions.

  17. 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.

  18. Improved Fabrication of Ceramic Matrix Composite/Foam Core Integrated Structures

    Science.gov (United States)

    Hurwitz, Frances I.

    2009-01-01

    The use of hybridized carbon/silicon carbide (C/SiC) fabric to reinforce ceramic matrix composite face sheets and the integration of such face sheets with a foam core creates a sandwich structure capable of withstanding high-heatflux environments (150 W/cm2) in which the core provides a temperature drop of 1,000 C between the surface and the back face without cracking or delamination of the structure. The composite face sheet exhibits a bilinear response, which results from the SiC matrix not being cracked on fabrication. In addition, the structure exhibits damage tolerance under impact with projectiles, showing no penetration to the back face sheet. These attributes make the composite ideal for leading edge structures and control surfaces in aerospace vehicles, as well as for acreage thermal protection systems and in high-temperature, lightweight stiffened structures. By tailoring the coefficient of thermal expansion (CTE) of a carbon fiber containing ceramic matrix composite (CMC) face sheet to match that of a ceramic foam core, the face sheet and the core can be integrally fabricated without any delamination. Carbon and SiC are woven together in the reinforcing fabric. Integral densification of the CMC and the foam core is accomplished with chemical vapor deposition, eliminating the need for bond-line adhesive. This means there is no need to separately fabricate the core and the face sheet, or to bond the two elements together, risking edge delamination during use. Fibers of two or more types are woven together on a loom. The carbon and ceramic fibers are pulled into the same pick location during the weaving process. Tow spacing may be varied to accommodate the increased volume of the combined fiber tows while maintaining a target fiber volume fraction in the composite. Foam pore size, strut thickness, and ratio of face sheet to core thickness can be used to tailor thermal and mechanical properties. The anticipated CTE for the hybridized composite is managed by

  19. Joining and Integration of Silicon Nitride Ceramics for Aerospace and Energy Systems

    Science.gov (United States)

    Singh, M.; Asthana, R.

    2009-01-01

    Light-weight, creep-resistant silicon nitride ceramics possess excellent high-temperature strength and are projected to significantly raise engine efficiency and performance when used as turbine components in the next-generation turbo-shaft engines without the extensive cooling that is needed for metallic parts. One key aspect of Si3N4 utilization in such applications is its joining response to diverse materials. In an ongoing research program, the joining and integration of Si3N4 ceramics with metallic, ceramic, and composite materials using braze interlayers with the liquidus temperature in the range 750-1240C is being explored. In this paper, the self-joining behavior of Kyocera Si3N4 and St. Gobain Si3N4 using a ductile Cu-based active braze (Cu-ABA) containing Ti will be presented. Joint microstructure, composition, hardness, and strength as revealed by optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Knoop microhardness test, and offset compression shear test will be presented. Additionally, microstructure, composition, and joint strength of Si3N4/Inconel 625 joints made using Cu-ABA, will be presented. The results will be discussed with reference to the role of chemical reactions, wetting behavior, and residual stresses in joints.

  20. Wireless passive polymer-derived SiCN ceramic sensor with integrated resonator/antenna

    Science.gov (United States)

    Li, Yan; Yu, Yuxi; San, Haisheng; Wang, Yansong; An, Linan

    2013-10-01

    This paper presents a passive wireless polymer-derived silicon carbonitride (SiCN) ceramic sensor based on cavity radio frequency resonator together with integrated slot antenna. The effect of the cavity sensor dimensions on the Q-factor and resonant frequency is investigated by numerical simulation. A sensor with optimal dimensions is designed and fabricated. It is demonstrated that the sensor signal can be wirelessly detected at distances up to 20 mm. Given the high-temperature stability of the SiCN, the sensor is very promising for high-temperature wireless sensing applications.

  1. Development of Solid Ceramic Dosimeters for the Time-Integrative Passive Sampling of Volatile Organic Compounds in Waters.

    Science.gov (United States)

    Bonifacio, Riza Gabriela; Nam, Go-Un; Eom, In-Yong; Hong, Yong-Seok

    2017-11-07

    Time-integrative passive sampling of volatile organic compounds (VOCs) in water can now be accomplished using a solid ceramic dosimeter. A nonporous ceramic, which excludes the permeation of water, allowing only gas-phase diffusion of VOCs into the resin inside the dosimeter, effectively captured the VOCs. The mass accumulation of 11 VOCs linearly increased with time over a wide range of aqueous-phase concentrations (16.9 to 1100 μg L -1 ), and the linearity was dependent upon the Henry's constant (H). The average diffusivity of the VOCs in the solid ceramic was 1.46 × 10 -10 m 2 s -1 at 25 °C, which was 4 orders of magnitude lower than that in air (8.09 × 10 -6 m 2 s -1 ). This value was 60% greater than that in the water-permeable porous ceramic (0.92 × 10 -10 m 2 s -1 ), suggesting that its mass accumulation could be more effective than that of porous ceramic dosimeters. The mass accumulation of the VOCs in the solid ceramic dosimeter increased in the presence of salt (≥0.1 M) and with increasing temperature (4 to 40 °C) but varied only slightly with dissolved organic matter concentration. The solid ceramic dosimeter was suitable for the field testing and measurement of time-weighted average concentrations of VOC-contaminated waters.

  2. Standardization Efforts for Mechanical Testing and Design of Advanced Ceramic Materials and Components

    Science.gov (United States)

    Salem, Jonathan A.; Jenkins, Michael G.

    2003-01-01

    Advanced aerospace systems occasionally require the use of very brittle materials such as sapphire and ultra-high temperature ceramics. Although great progress has been made in the development of methods and standards for machining, testing and design of component from these materials, additional development and dissemination of standard practices is needed. ASTM Committee C28 on Advanced Ceramics and ISO TC 206 have taken a lead role in the standardization of testing for ceramics, and recent efforts and needs in standards development by Committee C28 on Advanced Ceramics will be summarized. In some cases, the engineers, etc. involved are unaware of the latest developments, and traditional approaches applicable to other material systems are applied. Two examples of flight hardware failures that might have been prevented via education and standardization will be presented.

  3. Ceramic inlays and partial ceramic crowns: influence of remaining cusp wall thickness on the marginal integrity and enamel crack formation in vitro.

    Science.gov (United States)

    Krifka, Stephanie; Anthofer, Thomas; Fritzsch, Marcus; Hiller, Karl-Anton; Schmalz, Gottfried; Federlin, Marianne

    2009-01-01

    No information is currently available about what the critical cavity wall thickness is and its influence upon 1) the marginal integrity of ceramic inlays (CI) and partial ceramic crowns (PCC) and 2) the crack formation of dental tissues. This in vitro study of CI and PCC tested the effects of different remaining cusp wall thicknesses on marginal integrity and enamel crack formation. CI (n = 25) and PCC (n = 26) preparations were performed in extracted human molars. Functional cusps of CI and PCC were adjusted to a 2.5 mm thickness; for PCC, the functional cusps were reduced to a thickness of 2.0 mm. Non-functional cusps were adjusted to wall thicknesses of 1) 1.0 mm and 2) 2.0 mm. Ceramic restorations (Vita Mark II, Cerec3 System) were fabricated and adhesively luted to the cavities with Excite/Variolink II. The specimens were exposed to thermocycling and central mechanical loading (TCML: 5000 x 5 degrees C-55 degrees C; 30 seconds/cycle; 500000 x 72.5N, 1.6Hz). Marginal integrity was assessed by evaluating a) dye penetration (fuchsin) on multiple sections after TCML and by using b) quantitative margin analysis in the scanning electron microscope (SEM) before and after TCML. Ceramic- and tooth-luting agent interfaces (LA) were evaluated separately. Enamel cracks were documented under a reflective light microscope. The data were statistically analyzed with the Mann Whitney U-test (alpha = 0.05) and the Error Rates Method (ERM). Crack formation was analyzed with the Chi-Square-test (alpha = 0.05) and ERM. In general, the remaining cusp wall thickness, interface, cavity design and TCML had no statistically significant influence on marginal integrity for both CI and PCC (ERM). Single pairwise comparisons showed that the CI and PCC of Group 2 had a tendency towards less microleakage along the dentin/LA interface than Group 1. Cavity design and location had no statistically significant influence on crack formation, but the specimens with 1.0 mm of remaining wall

  4. Fuel cell integral bundle assembly including ceramic open end seal and vertical and horizontal thermal expansion control

    Science.gov (United States)

    Zafred, Paolo R [Murrysville, PA; Gillett, James E [Greensburg, PA

    2012-04-24

    A plurality of integral bundle assemblies contain a top portion with an inlet fuel plenum and a bottom portion containing a base support, the base supports a dense, ceramic air exhaust manifold having four supporting legs, the manifold is below and connects to air feed tubes located in a recuperator zone, the air feed tubes passing into the center of inverted, tubular, elongated, hollow electrically connected solid oxide fuel cells having an open end above a combustion zone into which the air feed tubes pass and a closed end near the inlet fuel plenum, where the open end of the fuel cells rest upon and within a separate combination ceramic seal and bundle support contained in a ceramic support casting, where at least one flexible cushion ceramic band seal located between the recuperator and fuel cells protects and controls horizontal thermal expansion, and where the fuel cells operate in the fuel cell mode and where the base support and bottom ceramic air exhaust manifolds carry from 85% to all of the weight of the generator.

  5. 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.

  6. Thermomechanical stability and integrability of an embedded ceramic antenna with an integrated sensor element for wireless reading in harsh environments

    Science.gov (United States)

    Sturesson, P.; Khaji, Z.; Knaust, S.; Sundqvist, J.; Klintberg, L.; Thornell, G.

    2013-12-01

    This paper reports on the design, manufacturing and evaluation of a small, wirelessly powered and read resonating antenna circuit with an integrated pressure sensor. The work aims at developing miniature devices suitable for harsh environments, where high temperature prevents the use of conventional, silicon-based microdevices. Here, the device is made of alumina with platinum as conducting material. Ceramic green tapes were structured using high-precision milling, metallized using screen printing, and subsequently laminated to form stacks before they were sintered. The device's frequency shift as a function of temperature was studied up to 900°C. The contributions to the shift both from the thermomechanical deformation of the device at large, and from the integrated and, so far, self-pressurized sensor were sorted out. A total frequency shift of 3200 ppm was observed for the pressure sensor for heating over the whole range. Negligible levels of thermally induced radius of curvature were observed. With three-point bending, a frequency shift of 180 ppm was possible to induce with a curvature of radius of 220 m at a 10 N load. The results indicate that a robust pressure sensor node, which can register pressure changes of a few bars at 900°C and wirelessly transmit the signal, is viable.

  7. Thermomechanical stability and integrability of an embedded ceramic antenna with an integrated sensor element for wireless reading in harsh environments

    International Nuclear Information System (INIS)

    Sturesson, P; Sundqvist, J; Thornell, G; Khaji, Z; Knaust, S; Klintberg, L

    2013-01-01

    This paper reports on the design, manufacturing and evaluation of a small, wirelessly powered and read resonating antenna circuit with an integrated pressure sensor. The work aims at developing miniature devices suitable for harsh environments, where high temperature prevents the use of conventional, silicon-based microdevices. Here, the device is made of alumina with platinum as conducting material. Ceramic green tapes were structured using high-precision milling, metallized using screen printing, and subsequently laminated to form stacks before they were sintered. The device's frequency shift as a function of temperature was studied up to 900°C. The contributions to the shift both from the thermomechanical deformation of the device at large, and from the integrated and, so far, self-pressurized sensor were sorted out. A total frequency shift of 3200 ppm was observed for the pressure sensor for heating over the whole range. Negligible levels of thermally induced radius of curvature were observed. With three-point bending, a frequency shift of 180 ppm was possible to induce with a curvature of radius of 220 m at a 10 N load. The results indicate that a robust pressure sensor node, which can register pressure changes of a few bars at 900°C and wirelessly transmit the signal, is viable

  8. Ultra High Temperature Capacitive Pressure Sensor, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — To improve the working performance, increase efficiency, reduce cost, and track system health status and failure modes of advanced propulsion systems; miniaturized,...

  9. Ultra High Temperature Capacitive Pressure Sensor, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — To improve the working performance, increase efficiency, reduce cost, and track system health status and failure modes of advanced propulsion systems; miniaturized,...

  10. New Oxide Materials for an Ultra High Temperature Environment

    Energy Technology Data Exchange (ETDEWEB)

    Perepezko, John H. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Materials Science and Engineering

    2017-11-13

    In this project, a new oxide material, Hf6Ta2O17 has been successfully synthesized by the controlled oxidization of Hf-Ta alloys. This oxide exhibits good oxidation resistance, high temperature phase stability up to more than 2000°C, low thermal conductivity and thus could serve as a component or a coating material in an ultrahigh temperature environment. We have examined the microstructure evolution and phase formation sequence during the oxidation exposure of Hf-Ta alloys at 1500°C and identified that the oxidation of a Hf-26.7atomic %Ta alloy leads to the formation of a single phase adherent Hf6Ta2O17 with a complex atomic structure i.e. superstructure. The overall reactive diffusion pathway is consistent with the calculated Hf-Ta-O ternary phase diagram. Besides the synthesis of Hf6Ta2O17 superstructure by oxidizing Hf-Ta alloys, we have also developed a synthesis method based upon the reactive sintering of the correct ratios of mixed powders of HfO2 and Ta2O5 and verified the low thermal conductivity of Hf6Ta2O17 superstructure on these samples. We have completed a preliminary analysis of the oxidation kinetics for Hf6Ta2O17, which shows an initial parabolic oxidation kinetics.

  11. Ultra-High Temperature Sensors Based on Optical Property

    Energy Technology Data Exchange (ETDEWEB)

    Nabeel Riza

    2008-09-30

    In this program, Nuonics, Inc. has studied the fundamentals of a new Silicon Carbide (SiC) materials-based optical sensor technology suited for extreme environments of coal-fired engines in power production. The program explored how SiC could be used for sensing temperature, pressure, and potential gas species in a gas turbine environment. The program successfully demonstrated the optical designs, signal processing and experimental data for enabling both temperature and pressure sensing using SiC materials. The program via its sub-contractors also explored gas species sensing using SiC, in this case, no clear commercially deployable method was proven. Extensive temperature and pressure measurement data using the proposed SiC sensors was acquired to 1000 deg-C and 40 atms, respectively. Importantly, a first time packaged all-SiC probe design was successfully operated in a Siemens industrial turbine rig facility with the probe surviving the harsh chemical, pressure, and temperature environment during 28 days of test operations. The probe also survived a 1600 deg-C thermal shock test using an industrial flame.

  12. Improved Creep Measurements for Ultra-High Temperature Materials

    Science.gov (United States)

    Hyers, Robert W.; Ye, X.; Rogers, Jan R.

    2010-01-01

    Our team has developed a novel approach to measuring creep at extremely high temperatures using electrostatic levitation (ESL). This method has been demonstrated on niobium up to 2300 C, while ESL has melted tungsten (3400 C). This method has been extended to lower temperatures and higher stresses and applied to new materials, including a niobium-based superalloy, MASC. High-precision machined spheres of the sample are levitated in the NASA MSFC ESL, a national user facility and heated with a laser. The samples are rotated with an induction motor at up to 30,000 revolutions per second. The rapid rotation loads the sample through centripetal acceleration, producing a shear stress of about 60 MPa at the center, causing the sample to deform. The deformation of the sample is captured on high-speed video, which is analyzed by machine-vision software from the University of Massachusetts. The deformations are compared to finite element models to determine the constitutive constants in the creep relation. Furthermore, the non-contact method exploits stress gradients within the sample to determine the stress exponent in a single test.

  13. DEVELOPMENT OF NOVEL CERAMIC NANOFILM-FIBER INTEGRATED OPTICAL SENSORS FOR RAPID DETECTION OF COAL DERIVED SYNTHESIS GAS

    Energy Technology Data Exchange (ETDEWEB)

    Junhang Dong; Hai Xiao; Xiling Tang; Hongmin Jiang; Kurtis Remmel; Amardeep Kaur

    2012-09-30

    The overall goal of this project is to conduct fundamental studies on advanced ceramic materials and fiber optic devices for developing new types of high temperature (>500{degree}C) fiber optic chemical sensors (FOCS) for monitoring fossil (mainly coal) and biomass derived gases in power plants. The primary technical objective is to investigate and demonstrate the nanocrystalline doped-ceramic thin film enabled FOCS that possess desired stability, sensitivity and selectivity for in-situ, rapid gas detection in the syngas streams from gasification and combustion flue gases. This report summarizes research works of two integrated parts: (1) development of metal oxide solid thin films as sensing materials for detection and measurement of important gas components relevant to the coal- and biomass-derived syngas and combustion gas streams at high temperatures; and (2) development of fiber optic devices that are potentially useful for constructing FOCS in combination with the solid oxide thin films identified in this program.

  14. Integration of ceramic membrane and compressed air-assisted solvent extraction (CASX) for metal recovery.

    Science.gov (United States)

    Li, Chi-Wang; Chiu, Chun-Hao; Lee, Yu-Cheng; Chang, Chia-Hao; Lee, Yu-Hsun; Chen, Yi-Ming

    2010-01-01

    In our previous publications, compressed air-assisted solvent extraction process (CASX) was developed and proved to be kinetically efficient process for metal removal. In the current study, CASX with a ceramic MF membrane integrated for separation of spent solvent was employed to remove and recover metal from wastewater. MF was operated either in crossflow mode or dead-end with intermittent flushing mode. Under crossflow mode, three distinct stages of flux vs. TMP (trans-membrane pressure) relationship were observed. In the first stage, flux increases with increasing TMP which is followed by the stage of stable flux with increasing TMP. After reaching a threshold TMP which is dependent of crossflow velocity, flux increases again with increasing TMP. At the last stage, solvent was pushed through membrane pores as indicated by increasing permeate COD. In dead-end with intermittent flushing mode, an intermittent flushing flow (2 min after a 10-min or a 30-min dead-end filtration) was incorporated to reduce membrane fouling by flush out MSAB accumulated on membrane surface. Effects of solvent concentration and composition were also investigated. Solvent concentrations ranging from 0.1 to 1% (w/w) have no adverse effect in terms of membrane fouling. However, solvent composition, i.e. D(2)EHPA/kerosene ratio, shows impact on membrane fouling. The type of metal extractants employed in CASX has significant impact on both membrane fouling and the quality of filtrate due to the differences in their viscosity and water solubility. Separation of MSAB was the limiting process controlling metal removal efficiency, and the removal efficiency of Cd(II) and Cr(VI) followed the same trend as that for COD.

  15. Study on an integrated process combining ozonation with ceramic ultra-filtration for decentralized supply of drinking water.

    Science.gov (United States)

    Zhu, Jia; Fan, Xiao J; Tao, Yi; Wei, De Q; Zhang, Xi H

    2014-09-19

    An integrated process was specifically developed for the decentralized supply of drinking water from micro-polluted surface water in the rural areas of China. The treatment process combined ozonation with ceramic ultra-filtration (UF), coagulation for pre-treatment and granular activated carbon filtration. A flat-sheet ceramic membrane was used with a cut-off of 60 nm and the measurement of 254 mm (length) × 240 mm (width) × 6 mm (thickness). Ozonation and ceramic UF was set up whthin one reactor. The experimental results showed that the removal efficiencies of the dissolved organic carbon (DOC) and the formation potential of trihalomethanes (THMs), haloacetic acids (HAAs) and ammonia were 80%, 76%, 70% and 90%, respectively; that the turbidity of the product water was below 0.2 NTU and the particle count number (particles larger than 2 μm) was less than 50 counts per mL. The result also showed that all the pathogenic microorganisms were retained by the ceramic and that UF. Ozonation played a critical role in the control of membrane fouling and the removal of contaminants. Exactly, the membrane fouling can be controlled in situ with 3 mg L(-1) ozone at the permeate flux of 80 L m(-2) h(-1), yet the required dosage of ozone was dependent on the quality of the raw water. Therefore, this study is able to provide a highly compacted system for decentralized supply of high-quality drinking water in terms of both chemical and microbiological safety for the rural areas in China.

  16. Structural integrity testing of glass-ceramic/molybdenum vacuum tube frames

    International Nuclear Information System (INIS)

    Spears, R.K.

    1980-01-01

    In this study, vacuum tube subassemblies made of glass-ceramic insulators sealed to inner and outer molybdenum frames were loaded in compression to failure with a tensile test machine. Several factors were varied in processing these subassemblies. These factors included etching and nonetching of molybdenum piece parts, annealing and nonannealing of subassemblies, and vapor and non-vapor honing of insulators after sealing. After failure, the subassemblies were examined for fracture patterns. In most cases, fracture started at points near the lower portion of the inner sleeve-insulator interface. More load was carried by subassemblies having molybdenum piece parts that were acid etched. No difference appeared between the strength of subassemblies having annealed and nonannealed glass-ceramic insulators. Parts with vapor-honed insulators failed at substantially lower loads

  17. Integrated pollution prevention and control for heavy ceramic industry in Galicia (NW Spain).

    Science.gov (United States)

    Barros, M C; Bello, P; Roca, E; Casares, J J

    2007-03-22

    The heavy ceramic industry (building materials and refractory products manufacture) is an important source of pollutants to the environment. For this reason these industrial sub-sectors are included in prevention and control pollution policies, specifically those of the European Union. The IPPC Directive pays particular attention to the mineral industries, not least to the ceramic industry (epigraph 3.5, Annex I). In this paper, a methodology which is being applied to support IPPC installations and the competent administrative authority in Galicia (NW Spain) is presented. For that, the Galician heavy ceramic industry is analysed, as also are the ways to study the Best Available Techniques (BAT) with a view to establishing the emission limit values (ELV) for each specific case. Hence, a technological state of the art has been carried out for both sub-sectors, from the point of view of implementation of the IPPC in Galicia. Following this, the processes are described briefly and an analysis of the consumption and emission levels of the main pollutants is made. An inventory that includes the best environmental practices and the preventive and abatement candidate techniques as BAT was elaborated for both considered sub-sectors. An information data sheet for each candidate BAT is presented as a method to help both the industries and the competent authority to identify a candidate technique of the inventory as BAT. Three illustrative examples of the application of this procedure are presented for different emissions to environmental media for Galician installations.

  18. 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.

  19. 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.

  20. The evaluation of integrity and elasticity of thermally sprayed ceramic coatings by ultrasonics

    Energy Technology Data Exchange (ETDEWEB)

    Kauppinen, P. [VTT Manufacturing Technology, Espoo (Finland). Materials and Structural Integrity

    1997-12-31

    Thermally sprayed ceramic coatings are widely used in industrial applications where the coated component is subject to, e.g. high thermal loads or mechanical wear. The mechanical properties of the coating are finally created in the coating process and the chemical composition of the powder used as raw material can only give some hints about the properties of the final coating. Several non-destructive testing techniques are available for the detection of defects in ceramic materials or for the evaluation of density and density variations. In addition to this, ultrasonic techniques can be used for quantitative evaluation of elastic properties of materials. This evaluation is based on the measurement of sound velocities of different wave modes in the material and is normally applied only to relatively simple-shaped specimens having parallel surfaces. Acoustic microscopy operating at very high (> 100 MHz) frequencies has been used to measure the sound velocities in homogeneous and thin coatings. With this type of equipment, reliable and accurate results have been achieved in laboratory measurements. A lot of development work has been carried out world-wide to develop the measurement techniques and acoustic lenses (transducers) used in acoustic microscopy. However, less attention has been paid on the development of techniques for industrial applications on-site. The present work was focused on the development of measurement techniques for industrial applications. A new type of large-aperture low-frequency transducer was designed and constructed for the measurement of sound velocities in thermally sprayed ceramic coatings. The major difference to the lenses used in acoustic microscopy is that in the new transducer no separate lens is needed for focusing the sound beam. The piezoelectric element in the new transducer is a plastic (PVDF)-film that can be shaped to create the required focus. The practical measurement of the sound velocity is based on a modification of the V

  1. Integrated nitrogen removal biofilter system with ceramic membrane for advanced post-treatment of municipal wastewater.

    Science.gov (United States)

    Son, Dong-Jin; Yun, Chan-Young; Kim, Woo-Yeol; Zhang, Xing-Ya; Kim, Dae-Gun; Chang, Duk; Sunwoo, Young; Hong, Ki-Ho

    2016-12-01

    The pre-denitrification biofilm process for nitrogen removal was combined with ceramic membrane with pore sizes of 0.05-0.1 µm as a system for advanced post-treatment of municipal wastewater. The system was operated under an empty bed hydraulic retention time of 7.8 h, recirculation ratio of 3, and transmembrane pressure of 0.47 bar. The system showed average removals of organics, total nitrogen, and solids as high as 93%, 80%, and 100%, respectively. Rapid nitrification could be achieved and denitrification was performed in the anoxic filter without external carbon supplements. The residual particulate organics and nitrogen in effluent from biofilm process could be also removed successfully through membrane filtration and the removal of total coliform was noticeably improved after membrane filtration. Thus, a system composed of the pre-denitrification biofilm process with ceramic membrane would be a compact and flexible option for advanced post-treatment of municipal wastewater.

  2. 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…

  3. Label-free detection of endocrine disrupting chemicals by integrating a competitive binding assay with a piezoelectric ceramic resonator.

    Science.gov (United States)

    Hu, Liang-sheng; Fong, Chi-Chun; Zou, Lan; Wong, Wing-Leung; Wong, Kwok-Yin; Wu, Rudolf S S; Yang, Mengsu

    2014-03-15

    A piezoelectric biosensor for detection of endocrine disrupting chemicals (EDCs) was developed by incorporating chemical/biochemical recognition elements on the ceramic resonator surface for competitive binding assays. A facile electrodeposition was employed to modify the sensor surface with Au nanoparticles, which increased the surface area and enhanced the binding capacity of the immobilized probes. Thiol-labeled long chain hydrocarbon with bisphenol A (BPA) as head group was synthesized and self-assembled on the Au nanoparticle surface as the sensing probes, which showed a linear response upon the binding of estrogen receptor (ER-α) ranging from 1 to 30 nM. Detection of estrone, 17β-estradiol and BPA was achieved by integrating a competitive binding assay with the piezoelectric sensor. In this detection scheme, different concentrations of EDCs were incubated with 30 nM of ER-α, and the un-bounded ER-α in the solution was captured by the probes immobilized on the ceramic resonator, which resulted in the frequency changes for different EDCs. The biosensor assay exhibited a linear response to EDCs with a low detection limit of 2.4-2.9 nM (S/N=3), and required only a small volume of sample (1.5 µl) with the assay time of 2h. The performance of the biosensor assay was also evaluated for rapid and facile determination of EDCs of environmental relevant concentrations in drinking water and seawater, and the recovery rate was in the range between 94.7% and 109.8%. © 2013 Elsevier B.V. All rights reserved.

  4. Development of Advanced Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites: Path Toward 2700 F Temperature Capability and Beyond

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Good, Brian; Costa, Gustavo; Bhatt, Ramakrishna T.; Fox, Dennis S.

    2017-01-01

    Advanced environmental barrier coating systems for SiC-SiC Ceramic Matrix Composite (CMC) turbine and combustor hot section components are currently being developed to meet future turbine engine emission and performance goals. One of the significant coating development challenges is to achieve prime-reliant environmental barrier coating systems to meet the future 2700F EBC-CMC temperature stability and environmental durability requirements. This presentation will emphasize recent NASA environmental barrier coating system testing and down-selects, particularly the development path and properties towards 2700-3000F durability goals by using NASA hafnium-hafnia-rare earth-silicon-silicate composition EBC systems for the SiC-SiC CMC turbine component applications. Advanced hafnium-based compositions for enabling next generation EBC and CMCs capabilities towards ultra-high temperature ceramic coating systems will also be briefly mentioned.

  5. Substrate Integrated Waveguide Based Phase Shifter and Phased Array in a Ferrite Low Temperature Co-fired Ceramic Package

    KAUST Repository

    Nafe, Ahmed A.

    2014-03-01

    Phased array antennas, capable of controlling the direction of their radiated beam, are demanded by many conventional as well as modern systems. Applications such as automotive collision avoidance radar, inter-satellite communication links and future man-portable satellite communication on move services require reconfigurable beam systems with stress on mobility and cost effectiveness. Microwave phase shifters are key components of phased antenna arrays. A phase shifter is a device that controls the phase of the signal passing through it. Among the technologies used to realize this device, traditional ferrite waveguide phase shifters offer the best performance. However, they are bulky and difficult to integrate with other system components. Recently, ferrite material has been introduced in Low Temperature Co-fired Ceramic (LTCC) multilayer packaging technology. This enables the integration of ferrite based components with other microwave circuitry in a compact, light-weight and mass producible package. Additionally, the recent concept of Substrate Integrated Waveguide (SIW) allowed realization of synthesized rectangular waveguide-like structures in planar and multilayer substrates. These SIW structures have been shown to maintain the merits of conventional rectangular waveguides such as low loss and high power handling capabilities while being planar and easily integrable with other components. Implementing SIW structures inside a multilayer ferrite LTCC package enables monolithic integration of phase shifters and phased arrays representing a true System on Package (SoP) solution. It is the objective of this thesis to pursue realizing efficient integrated phase shifters and phased arrays combining the above mentioned technologies, namely Ferrite LTCC and SIW. In this work, a novel SIW phase shifter in ferrite LTCC package is designed, fabricated and tested. The device is able to operate reciprocally as well as non-reciprocally. Demonstrating a measured maximum

  6. Effect of machining parameters on surface integrity of silicon carbide ceramic using end electric discharge milling and mechanical grinding hybrid machining

    International Nuclear Information System (INIS)

    Ji, Renjie; Liu, Yonghong; Zhang, Yanzhen; Cai, Baoping; Li, Xiaopeng; Zheng, Chao

    2013-01-01

    A novel hybrid process that integrates end electric discharge (ED) milling and mechanical grinding is proposed. The process is able to effectively machine a large surface area on SiC ceramic with good surface quality and fine working environmental practice. The polarity, pulse on-time, and peak current are varied to explore their effects on the surface integrity, such as surface morphology, surface roughness, micro-cracks, and composition on the machined surface. The results show that positive tool polarity, short pulse on-time, and low peak current cause a fine surface finish. During the hybrid machining of SiC ceramic, the material is mainly removed by end ED milling at rough machining mode, whereas it is mainly removed by mechanical grinding at finish machining mode. Moreover, the material from the tool can transfer to the workpiece, and a combination reaction takes place during machining.

  7. Influence of different cusp coverage methods for the extension of ceramic inlays on marginal integrity and enamel crack formation in vitro.

    Science.gov (United States)

    Krifka, Stephanie; Stangl, Martin; Wiesbauer, Sarah; Hiller, Karl-Anton; Schmalz, Gottfried; Federlin, Marianne

    2009-09-01

    No information is available to date about cusp design of thin (1.0 mm) non-functional cusps and its influence upon (1) marginal integrity of ceramic inlays (CI) and partial ceramic crowns (PCC) and (2) crack formation of dental tissues. The aim of this in vitro study was to investigate the effect of cusp coverage of thin non-functional cusps on marginal integrity and enamel crack formation. CI and PCC preparations were performed on extracted human molars. Non-functional cusps were adjusted to 1.0-mm wall thickness and 1.0-mm wall thickness with horizontal reduction of about 2.0 mm. Ceramic restorations (Vita Mark II, Cerec3 System) were adhesively luted with Excite/Variolink II. The specimens were exposed to thermocycling and central mechanical loading. Marginal integrity was assessed by evaluating dye penetration after thermal cycling and mechanical loading. Enamel cracks were documented under a reflective-light microscope. The data were statistically analysed with the Mann-Whitney U test, the Fishers exact test (alpha = 0.05) and the error rates method. PCC with horizontal reduction of non-functional cusps showed statistically significant less microleakage than PCC without such a cusp coverage. Preparation designs with horizontal reduction of non-functional cusps showed a tendency to less enamel crack formation than preparation designs without cusp coverage. Thin non-functional cusp walls of adhesively bonded restorations should be completely covered or reduced to avoid enamel cracks and marginal deficiency.

  8. 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

  9. Integration of Computer Tomography and Simulation Analysis in Evaluation of Quality of Ceramic-Carbon Bonded Foam Filter

    Directory of Open Access Journals (Sweden)

    Karwiński A.

    2013-12-01

    Full Text Available Filtration of liquid casting alloys is used in casting technologies for long time. The large quantity of available casting filters allows using them depending on casting technology, dimensions of casting and used alloys. Technological progress of material science allows of using new materials in production of ceramic filters. In this article the Computed Tomography (CT technique was use in order to evaluate the thickness of branch in cross section of 20ppi ceramic-carbon bonded foam filter. Than the 3D image of foam filter was used in computer simulation of flow of liquid metal thru the running system.

  10. 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.

  11. Ceramic Filter for Small System Drinking Water Treatment: Evaluation of Membrane Pore Size and Importance of Integrity Monitoring

    Science.gov (United States)

    Ceramic filtration has recently been identified as a promising technology for drinking water treatment in households and small communities. This paper summarizes the results of a pilot-scale study conducted at the U.S. Environmental Protection Agency’s (EPA’s) Test & Evaluation ...

  12. 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.

  13. 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....

  14. Domestic Ritual and Identity in the Teotihuacan State: Exploring Regional Processes of Social Integration Through Ceramic Figurines

    OpenAIRE

    Hagerman, Kiri Louise

    2018-01-01

    Teotihuacan was a sprawling urban center that came to rule an eponymous expansive polity in the central Mexican highlands from approximately 200 to 600 CE. The conditions that facilitated its initial expansion, however, are not fully understood. This dissertation examines ceramic figurines from Teotihuacan and the three rural sites of Axotlan, Cerro Portezuelo, and Huixtoco in the Basin of Mexico to investigate ancient social relationships, cultural changes, and political transformations duri...

  15. [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.

  16. 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

  17. 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.

  18. Integrity assessment of the spacecraft subjected to the hypervelocity impact by ceramic and metal projectiles simulating space debris and micrometeoroids

    International Nuclear Information System (INIS)

    Katayama, Masahide; Takeba, Atsushi; Nitta, Kumi; Kawakita, Shirou; Matsumoto, Haruhisa; Kitazawa, Yukihito

    2010-01-01

    In order to establish the guidelines for the protection of unmanned spacecrafts from the space debris and micrometeoroid impacts, the experimental and numerical investigations have been conducted at Japan Aerospace Exploration Agency. This paper presents mainly its numerical methodology, especially from the viewpoint of highly non-linear and dynamic material model: i.e. the equation of state, constitutive model and fracture or failure model, including a brittle material model for ceramics and an equation of state for the shock-induced vaporization accompanied by hypervelocity impact. The experimental results of hypervelocity impact by two-stage light-gas gun and plasma drag gun are compared with corresponding numerical simulation results by using a hydrocode, and both results are demonstrated to be overall in good agreement with each other.

  19. Integrity assessment of the spacecraft subjected to the hypervelocity impact by ceramic and metal projectiles simulating space debris and micrometeoroids

    Energy Technology Data Exchange (ETDEWEB)

    Katayama, Masahide, E-mail: masahide.katayama@ctc-g.co.jp [Science and Engineering Systems Division, ITOCHU Techno-Solutions, 3-2-5, Kasumigaseki, Chiyoda-ku, Tokyo 100-6080 (Japan); Materials and Structures Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori-ku, Yokohama-shi, Kanagawa 226-8503 (Japan); Takeba, Atsushi [Science and Engineering Systems Division, ITOCHU Techno-Solutions, 3-2-5, Kasumigaseki, Chiyoda-ku, Tokyo 100-6080 (Japan); Nitta, Kumi; Kawakita, Shirou; Matsumoto, Haruhisa [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba-city, Ibaraki 305-8505 (Japan); Kitazawa, Yukihito [Aerospace Research and Development Directorate, Japan Aerospace Exploration Agency, 2-1-1, Sengen, Tsukuba-city, Ibaraki 305-8505 (Japan); Aero-Engine and Space Operations, IHI Corporation, 3-1-1, Toyosu, Koto-ku, Tokyo 135-8710 (Japan)

    2010-10-15

    In order to establish the guidelines for the protection of unmanned spacecrafts from the space debris and micrometeoroid impacts, the experimental and numerical investigations have been conducted at Japan Aerospace Exploration Agency. This paper presents mainly its numerical methodology, especially from the viewpoint of highly non-linear and dynamic material model: i.e. the equation of state, constitutive model and fracture or failure model, including a brittle material model for ceramics and an equation of state for the shock-induced vaporization accompanied by hypervelocity impact. The experimental results of hypervelocity impact by two-stage light-gas gun and plasma drag gun are compared with corresponding numerical simulation results by using a hydrocode, and both results are demonstrated to be overall in good agreement with each other.

  20. Development and application of knowledge-based subject group integration platforms:A case study of Shanghai Institute of Ceramics,CAS

    Institute of Scientific and Technical Information of China (English)

    Yu; LIU; Jian; FU; Huijun; ZHENG; Hao; CHEN; Zhiping; YANG

    2014-01-01

    Purpose:According to the different requirements of research group users,we established the knowledge-based subject group integration platforms of Shanghai Institute of Ceramics,the Chinese Academy of Sciences(abbreviated as SIC CAS hereinafter),which were designed and constructed to better meet the needs of CAS research groups for their development,collaboration and communication.Design/methodology/approach:We first identified the requirements of users via preliminary investigation,and then chose CASI1 P,iLibrary and XKE technology,respectively as the building tools compatible with the major demands of users.These steps helped us complete the layout design of SIC CAS integration platforms,as well as its knowledge organization and integration.Findings:According to the need of users,we applied three types of platform construction technologies to five SIC integration platforms,and formulated standard norms for the further construction process,which could provide useful reference for a sustainable development for the extensive construction in CAS institutes.Research limitations:In order to make the SIC integration platforms more intelligent and have more functions,we need to enlarge the scale of the Platforms and upgrade the building tools for the platform construction.Practical implications:The nature of SIC sub-project integration platforms is to construct a content-sensitive environment which can embed knowledge services and knowledge applications seamlessly into scientific activities,so the Platform is expected to be a useful tool to help researchers better understand the recent development of the research field and form collaborations with their peers.Originality/value:SIC integration platforms are the only pilot construction that used 3different platform technologies in the first batch of knowledge-based subject group integration platforms of the Chinese Academy of Sciences.The construction is user-centered throughout the whole process,namely,from the technology

  1. Fiscal 1997 survey report / R and D of important region technology. R and D of technologies giving multi-functional characteristics to C/C composites (development of high-grade surface processing technology for engine members for methane fueled air craft. 1. control technology of micro structures of ultra-high temperature members); 1997 nendo seika hokokusho juyo chiiki gijutsu kenkyu kaihatsu. Fukugo kino buzai kozo seigyo gijutsu no kenkyu kaihatsu (methane nenryo kokukiyo engine buzai no kodo hyomen kako gijutsu kaihatsu). 1. chokoon buzai micro kozo seigyo gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-01

    For the purpose of developing members most suitable for aircraft use engines with methane as fuel, the R and D were conducted of technology to reform surfaces and interfaces of materials. In the R and D, the paper took up carbon fiber reinforced carbon composite materials (C/C composites). In the surface control and reformation technology using the ion engineering method, etc., in the sealing processing of C/C composites, tried was the formation of a C/SiC/Si3N4 composite layer which was formed by Si3N4 much smaller in thermal expansion coefficient than SiC. Further, technologies on ion injection, thin film formation, giving of oxidation resistance/corrosion resistance, improving/giving of thermal shock resistance, etc. In the multi-functional coating formation technology such as high liability and corrosion resistance, the study was carried out of the dense composite functionally-gradient layer as thermal stress relaxation layer and the fiber reinforced layer by carbon fiber using pores. Besides, studies were made of technologies of the micro structure control combination, evaluation of ultra-high temperature resistant environmental characteristics, etc. 61 refs., 198 figs., 44 tabs.

  2. Processing, Structure and High Temperature Oxidation Properties of Polymer-Derived and Hafnium Oxide Based Ceramic Systems

    Science.gov (United States)

    Terauds, Kalvis

    Demands for hypersonic aircraft are driving the development of ultra-high temperature structural materials. These aircraft, envisioned to sustain Mach 5+, are expected to experience continuous temperatures of 1200--1800°C on the aircraft surface and temperatures as high as 2800°C in combustion zones. Breakthroughs in the development of fiber based ceramic matrix composites (CMCs) are opening the door to a new class of high-tech UHT structures for aerospace applications. One limitation with current carbon fiber or silicon carbide fiber based CMC technology is the inherent problem of material oxidation, requiring new approaches for protective environmental barrier coatings (EBC) in extreme environments. This thesis focuses on the development and characterization of SiCN-HfO2 based ceramic composite EBC systems to be used as a protective layer for silicon carbide fiber based CMCs. The presented work covers three main architectures for protection (i) multilayer films, (ii) polymer-derived HfSiCNO, and (iii) composite SiCN-HfO 2 infiltration. The scope of this thesis covers processing development, material characterization, and high temperature oxidation behavior of these three SiCN-HfO2 based systems. This work shows that the SiCN-HfO 2 composite materials react upon oxidation to form HfSiO4, offering a stable EBC in streaming air and water vapor at 1600°C.

  3. Effect of Bacillus cereus Enzymes on Milk Quality following Ultra High Temperature Processing

    Directory of Open Access Journals (Sweden)

    B. Janštová

    2006-01-01

    Full Text Available Using a model case of contamination of long-life semi-skimmed milk with the spores of six B. cereus strains, isolated from the farm environment and raw milk, proteolysis was monitored by measuring changes in protein content by infra-red spectroscopy; free tyrosine was measured by the Lowry method according to Juffs, and the reduction in casein fractions by SDS-PAGE. Lipolysis was monitored by the dilution extractive method. At a storage temperature of 4 °C for 4 months no enzyme processes were observed, whereas at a storage temperature of 24 °C a marked enzyme activity was found during maximum 3 weeks as well as sensory changes of UHT milk. After three weeks of storage, a reduction in protein content from 34.55 g l-1 milk to 29.46 ± 2.00 g l-1 milk, and a reduction in the free tyrosine from 0.65 to 2.13 ± 0.28 mg ml-1 was found, as well as increased molar contents of free fatty acids (FFA from 41.97 to 1617.22 ± 68.17 mmol kg-1 milk fat. After six days of storage, α-casein, β-casein and κ-casein dropped to 69 ± 10%, 56 ± 16% and 43 ± 10%, respectively. Majority of changes in UHT milk depended on the B. cereus strain used, initial microbial counts and the method of heat inactivation of spores.

  4. Phase Stability in Ultra-High Temperature Refractory Metal Alloys and Coatings

    National Research Council Canada - National Science Library

    Perepezko, John

    2002-01-01

    ...) base alloys such as those in the Mo-Si-B system and the evaluation of thermal barrier and oxidation resistant coatings for these systems requires very high temperature annealing furnaces with long...

  5. Sterilization of liquid foods by pulsed electric fields?an innovative ultra-high temperature process

    OpenAIRE

    Reineke, Kai; Schottroff, Felix; Meneses, Nicolas; Knorr, Dietrich

    2015-01-01

    The intention of this study was to investigate the inactivation of endospores by a combined thermal and pulsed electric field (PEF) treatment. Therefore, self-cultivated spores of Bacillus subtilis and commercial Geobacillus stearothermophilus spores with certified heat resistance were utilized. Spores of both strains were suspended in saline water (5.3 mS cm−1), skim milk (0.3% fat; 5.3 mS cm−1) and fresh prepared carrot juice (7.73 mS cm−1). The combination of moderate preheating (70–90°C) ...

  6. Hot stuff : ultra-high temperature ESP system installed in SAGD wells

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2010-10-15

    Ultra-temperature electrical submersible pumping (ESP) systems have been installed in steam-assisted gravity drainage (SAGD) wells for the first time at a thermal project in Christina Lake, Alberta. The Centrilift XP ESP production system that is being field tested can operate at fluid temperatures reaching 250 degrees C, higher than conventional systems, which is expected to result in an increase in production with a larger steam chamber and less viscous oil at higher steaming temperatures. The more robust system is expected to extend run life and lower operating costs. Years of research and development at specialized testing facilities went into creating the system. The unique testing facilities simulated the horizontal orientation and temperature cycling characteristics of SAGD wells and permitted the system to be tested at temperatures up to 300 degrees C. The new system is expected to lower infrastructure costs for SAGD wells that require high temperatures. 1 fig.

  7. Hedonic analysis of ultra-high-temperature-treated milk prices in Italy

    NARCIS (Netherlands)

    Bimbo, Francesco; Bonanno, Alessandro; Liu, Xuan; Viscecchia, Rosaria

    2016-01-01

    The Italian market for UHT milk has been growing thanks to both consumers' interest in products with an extended shelf life and to the lower prices of these products compared with refrigerated, pasteurized milk. However, because the lower prices of UHT milk can hinder producers' margins,

  8. Printed Ultra-High Temperature NDE Sensors for Complex Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — This Phase I SBIR proposal will address the use of innovative additive manufacturing technologies applicable to Non-Destructive Evaluation (NDE) and Structural...

  9. Ultra-high temperature oxidation behavior of chemical vapor deposited silicon carbide layers

    International Nuclear Information System (INIS)

    Goto, Takashi

    2003-01-01

    The active oxidation, passive oxidation and bubble formation of CVD SiC were studied in O 2 and CO 2 at temperatures from 1650 to 2000 K. The active oxidation rates in O 2 increased with increasing oxygen partial pressure (P o2 ); however, those in CO 2 showed the maxima at specific P o2 . The passive oxidation kinetics in O 2 were either linear-parabolic or parabolic depending on temperature and P o2 , whereas that in CO 2 was always parabolic. The activation energies for the parabolic oxidation in O 2 and CO 2 were 210 and 150 kJ/mol, respectively, suggesting different rate-determining process between these atmospheres. The bubble formation was controlled by temperature and P o2 being independent of oxidant gas species. (author)

  10. Sterilization of liquid foods by pulsed electric fields – an innovative ultra-high temperature process

    OpenAIRE

    Kai eReineke; Kai eReineke; Felix eSchottroff; Nicolas eMeneses; Nicolas eMeneses; Dietrich eKnorr

    2015-01-01

    The intention of this study was to investigate the inactivation of endospores by a combined thermal and pulsed electric field (PEF) treatment. Therefore, self-cultivated spores of Bacillus subtilis and commercial Geobacillus stearothermophilus spores with certified heat resistance were utilized. Spores of both strains were suspended in saline water (5.3 mS cm-1), skim milk (0.3% fat; 5.3 mS cm-1) and fresh prepared carrot juice (7.73 mS cm-1). The combination of moderate preheating (70-90 °C)...

  11. Measurement of the Thermal Expansion Coefficient for Ultra-High Temperatures up to 3000 K

    Science.gov (United States)

    Kompan, T. A.; Kondratiev, S. V.; Korenev, A. S.; Puhov, N. F.; Inochkin, F. M.; Kruglov, S. K.; Bronshtein, I. G.

    2018-03-01

    The paper is devoted to a new high-temperature dilatometer, a part of the State Primary Standard of the thermal expansion coefficient (TEC) unit. The dilatometer is designed for investigation and certification of materials for TEC standards in the range of extremely high temperatures. The critical review of existing methods of TEC measurements is given. Also, the design, principles of operation and metrological parameters of the new device are described. The main attention is paid to the system of machine vision that allows accurate measurement of elongation at high temperatures. The results of TEC measurements for graphite GIP-4, single crystal Al2O3, and some other materials are also presented.

  12. Corrosion of Nickel-Based Alloys in Ultra-High Temperature Heat Transfer Fluid

    Science.gov (United States)

    Wang, Tao; Reddy, Ramana G.

    2017-03-01

    MgCl2-KCl binary system has been proposed to be used as high temperature reactor coolant. Due to its relatively low melting point, good heat capacity and excellent thermal stability, this system can also be used in high operation temperature concentrating solar power generation system as heat transfer fluid (HTF). The corrosion behaviors of nickel based alloys in MgCl2-KCl molten salt system at 1,000 °C were determined based on long-term isothermal dipping test. After 500 h exposure tests under strictly maintained high purity argon gas atmosphere, the weight loss and corrosion rate analysis were conducted. Among all the tested samples, Ni-201 demonstrated the lowest corrosion rate due to the excellent resistance of Ni to high temperature element dissolution. Detailed surface topography and corrosion mechanisms were also determined by using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS).

  13. Ultra-high temperature chirped fiber Bragg gratings produced by gradient stretching of viscoelastic silica.

    Science.gov (United States)

    Gao, Shaorui; Canning, John; Cook, Kevin

    2013-12-15

    By applying a suitable quadratic temperature distribution at a temperature within the viscoelastic softening region for silica, a regenerated chirped grating with bandwidth of 9.8 nm is produced from a uniform grating using post strain-tuning under load. Simulated and experimental results are in good agreement.

  14. Novel instrument for high-pressure research at ultra-high temperatures

    International Nuclear Information System (INIS)

    Schiferl, D.; Katz, A.I.; Mills, R.L.

    1985-01-01

    A resistively heated diamond-anvil cell has been used to achieve pressures of 110 kbar at temperatures exceeding 1200 0 C for periods long enough to collect x-ray powder diffraction data with energy-dispersive techniques using ''white'' x-radiation produced at the Stanford Synchrotron Radiation Laboratory. 9 refs., 1 fig

  15. Analysis and Monitoring Results of a Building Integrated Photovoltaic Façade Using PV Ceramic Tiles in Taiwan

    Directory of Open Access Journals (Sweden)

    Yen-Chieh Huang

    2014-01-01

    Full Text Available Single-crystal silicon-based solar cells laminated with tempered-glass and ceramic tiles for use in a building’s façade have been developed. The optical, thermal, and electrical properties of the proposed PV module are first evaluated, and then a wind-resistance test is carried out to evaluate the feasibility of installing it in Taiwan. The electrical and deflection characteristics of the proposed PV module did not change significantly after a 50 thermal cycling test and a 200-hour humidity-freeze test, based on IEC 61215 and a wind-resistance test. Finally, the electrical power generation ability of the proposed BIPV system with 1 kWp electrical power capacity was examined. Building information modeling software tools were used to simulate the BIPV system and carry out the energy analysis. The simulation results show a very consistent trend with regard to the actual monthly electricity production of the BIPV system designed in this work. The BIPV system was able to produce an accumulative electrical power of 185 kWh during the 6-month experimental period. In addition, the exterior temperature of the demonstration house was about 10°C lower than the surface of the BIPV system, which could reduce indoor temperature.

  16. The behaviour of ceramic breeder materials with respect to tritium release and pellet/pebble mechanical integrity

    Science.gov (United States)

    Kwast, H.; Conrad, R.; May, R.; Casadio, S.; Roux, N.; Werle, H.

    1994-09-01

    In situ tritium release experiments from several candidate fusion blanket ceramic breeder materials have been performed in the High Flux Reactor (HFR) at Petten over the last few years. The sixth experiment, EXOTIC-6, contained pellets of LiAlO 2, Li 2XrO 3, Li 6Xr 2O 7 and Li 8ZrO 6 and pebbles of Li 4SiO 4 and Li 2ZrO 3 which were irradiated up to a lithium burnup of 3%. A large number of temperature transients and purge gas composition changes were performed. From the temperature transients tritium residence times have been determined. Some preliminary results were presented at the 17th Symposium on Fusion Technology (SOFT) held in Rome in 1992. In the present paper results of a further analysis of the residence times are presented together with some postirradiation examination results. The LiAlO 2 pellets showed a better mechanical stability than the Li-zirconates pellets. The pebbels remained intact. The tritium residence times determined from the tritium inventories were in good agreement with those previously determined from temperature transients. The tritium release characteristics of the materials investigated remain substantially unchanged up to the maximum lithium burnup achieved in this experiment.

  17. Substrate Integrated Waveguide Based Phase Shifter and Phased Array in a Ferrite Low Temperature Co-fired Ceramic Package

    KAUST Repository

    Nafe, Ahmed A.

    2014-01-01

    that controls the phase of the signal passing through it. Among the technologies used to realize this device, traditional ferrite waveguide phase shifters offer the best performance. However, they are bulky and difficult to integrate with other system components

  18. 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..)

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. An experimental bioactive dental ceramic for metal-ceramic restorations: Textural characteristics and investigation of the mechanical properties.

    Science.gov (United States)

    Goudouri, Ourania-Menti; Kontonasaki, Eleana; Papadopoulou, Lambrini; Manda, Marianthi; Kavouras, Panagiotis; Triantafyllidis, Konstantinos S; Stefanidou, Maria; Koidis, Petros; Paraskevopoulos, Konstantinos M

    2017-02-01

    The aim of this study was the evaluation of the textural characteristics of an experimental sol-gel derived feldspathic dental ceramic, which has already been proven bioactive and the investigation of its flexural strength through Weibull Statistical Analysis. The null hypothesis was that the flexural strength of the experimental and the commercial dental ceramic would be of the same order, resulting in a dental ceramic with apatite forming ability and adequate mechanical integrity. Although the flexural strength of the experimental ceramics was not statistically significant different compared to the commercial one, the amount of blind pores due to processing was greater. The textural characteristics of the experimental ceramic were in accordance with the standard low porosity levels reported for dental ceramics used for fixed prosthetic restorations. Feldspathic dental ceramics with typical textural characteristics and advanced mechanical properties as well as enhanced apatite forming ability can be synthesized through the sol-gel method. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. Mixed Non-Uniform Width / Evanescent Mode Ceramic Resonator Waveguide Filter With Wide Spurious Free Bandwidth

    OpenAIRE

    Afridi, S; Sandhu, M; Hunter, I

    2016-01-01

    This paper presents a method to improve the spurious performance of integrated ceramic waveguide filters. Nonuniform width ceramic waveguide resonator and evanescent mode ceramic resonators are employed together to the resonant frequencies of higher order modes. The proposed designs give 75% improvement in stop band response when compared to uniform width ceramic waveguide filter. Simulated results of two six pole chebyshev filters are presented here with improved stop band performance.

  13. Modeling the effects of electrical and non-electrical parameters on the material removal and surface integrity in case of µEDM of a non-conductive ceramic material using a combined fuzzy-AOM approach

    DEFF Research Database (Denmark)

    Puthumana, Govindan

    2016-01-01

    Micro-EDM is a non-contact process based on the thermoelectric energy between a tool electrode and a workpiece. In μEDM process, the mechanism of material removal is melting and evaporation. The thermal energy in the discharge plasma helps remove material from the workpiece, at the same time...... and surface integrity for a non-conductive ceramic material. The fuzzy logic modeling system is employed for predicting the μEDM process responses. The trends in the material removal rate and hardness values with the chosen electrical and non-electrical parameter for the model and obtained using AOM approach...... are compared. The average deviation between the model predictions and the results obtained using AOM plots is less than 10%. The material removal rate (MRR) decreases linearly with voltage, indicating a difference in material removal mechanism in the μEDM of non-conductive materials....

  14. 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

  15. 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 ...

  16. 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)

  17. [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.

  18. 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)

  19. 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

  20. 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.

  1. 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.

  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. 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.

  4. 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.

  5. 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)

  6. 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.

  7. 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.

  8. Processing and characterization of ceramic superconductor/polymer composites

    International Nuclear Information System (INIS)

    Kander, R.G.; Namboodri, S.L.

    1993-01-01

    One way to more easily process a brittle high-temperature ceramic superconductor into a useful structure is to combine it with a polymer to form a composite material. Processing of polymer-based composites into complex shapes is well established and relatively easy when compared with traditional ceramic processing unit operations. In addition, incorporating a ceramic superconductor into a polymer matrix can improve mechanical performance as compared with a monolithic ceramic. Finally, because ceramic superconductors are susceptible to attack by moisture, a polymer-based composite structure can also provide protection from deleterious environmental effects. This paper focuses on the processing and subsequent characterization of ceramic superconductor/polymer composites designed primarily for electromagnetic shielding and diamagnetic applications. YBa 2 Cu 3 O 7-x [YBCO] ceramic superconductor is combined with poly(methyl methacrylate) [PMMA] to form novel composite structures. Composite structures have been molded with both a discontinuous superconducting phase (i.e., ceramic particulate reinforced polymers) and with a continuous superconducting phase (i.e., polymer infiltrated porous ceramics). Characterization of these composite structures includes the determination of diamagnetic strength, electromagnetic shielding effectiveness, mechanical performance, and environmental resistance. The goal of this program is to produce a composite structure with increased mechanical integrity and environmental resistance at liquid nitrogen temperatures without compromising the electromagnetic shielding and diamagnetic properties of the superconducting phase. Composites structures of this type are potentially useful in numerous magnetic applications including electromagnetic shielding, magnetic sensors, energy storage, magnetic levitation, and motor windings

  9. Ceramic Prototypes – Design, Computation, and Digital Fabrication

    Directory of Open Access Journals (Sweden)

    M. Bechthold

    2016-12-01

    Full Text Available Research in ceramic material systems at Harvard University has introduced a range of novel applications which combine digital manufacturing technologies and robotics with imaginative design and engineering methods. Prototypes showcase the new performative qualities of ceramics and the integration of this material in today’s construction culture. Work ranges from daylight control systems to structural applications and a robotic tile placement system. Emphasis is on integrating novel technologies with tried and true manufacturing methods. The paper describes two distinct studies – one on 3D print-ing of ceramics, the other on structural use of large format thin tiles.

  10. 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.

  11. Acceptance sensory of milk Ultra High Temperature and consumer attitudes of packaging of different brands of the product

    Directory of Open Access Journals (Sweden)

    Marlice Salete Bonacina

    2016-06-01

    Full Text Available The study aimed to evaluate the sensory acceptance of different brands of whole UHT milk; identify and quantify the importance of attributes of the packaging and labeling of milk in the purchase attitude of consumers excure six different brands of whole UHT milk were collect, which were submitted to the acceptance test, using a hybrid hedonic scale of 9 cm. The data were submitted to ANOVA using the Statistical Software 6.0. The packaging and labeling of different brands of milk, were used for application of the focus group technique. From the results, we found that there was no difference (p > 0.05 between the brands of UHT milk, in relation to sensory acceptance. It was also possible to verify the influence frequency of the milk consumption of acceptance of the product, characterized by three clusters of consumers. From the focus group sessions it was found that 61.1% of participants observe the packaging and labeling milk at the time of purchase. However, 38.9% argued that they are faithful consumers excure to a determined brand. As regards the existence of quality certification seals, it was found that 72.2% of participants do not observe the existence of these certifications when buying milk. In addition, 77.8% have not changed their spending habits in relation to milk brand. It is concluded that the milk consumption frequency, influence on sensorial acceptance, and some consumers are unaware of the risk that the tamper carried out in milk can cause to their health.

  12. Stability of phases at high temperatures in CoRe based alloys being developed for ultra-high temperature applications

    Czech Academy of Sciences Publication Activity Database

    Gilles, R.; Strunz, Pavel; Mukherji, D.; Hofmann, M.; Holzel, M.; Rösler, J.

    2012-01-01

    Roč. 340, 012052 (2012), s. 1-9 ISSN 1742-6588. [5th European Conference on Neutron Scattering. Praha, 17.07.2011-21.07.2011] R&D Projects: GA MPO FR-TI1/378 Institutional support: RVO:61389005 Keywords : neutron diffraction * Co-base alloy * electron microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism

  13. Fabrication of Tungsten-Rhenium Cladding materials via Spark Plasma Sintering for Ultra High Temperature Reactor Applications

    Energy Technology Data Exchange (ETDEWEB)

    Charit, Indrajit; Butt, Darryl; Frary, Megan; Carroll, Mark

    2012-11-05

    This research will develop an optimized, cost-effective method for producing high-purity tungsten-rhenium alloyed fuel clad forms that are crucial for the development of a very high-temperature nuclear reactor. The study will provide critical insight into the fundamental behavior (processing-microstructure- property correlations) of W-Re alloys made using this new fabrication process comprising high-energy ball milling (HEBM) and spark plasma sintering (SPS). A broader goal is to re-establish the U.S. lead in the research field of refractory alloys, such as W-Re systems, with potential applications in very high-temperature nuclear reactors. An essential long-term goal for nuclear power is to develop the capability of operating nuclear reactors at temperatures in excess of 1,000K. This capability has applications in space exploration and some special terrestrial uses where high temperatures are needed in certain chemical or reforming processes. Refractory alloys have been identified as being capable of withstanding temperatures in excess of 1,000K and are considered critical for the development of ultra hightemperature reactors. Tungsten alloys are known to possess extraordinary properties, such as excellent high-temperature capability, including the ability to resist leakage of fissile materials when used as a fuel clad. However, there are difficulties with the development of refractory alloys: 1) lack of basic experimental data on thermodynamics and mechanical and physical properties, and 2) challenges associated with processing these alloys.

  14. Comparison of heat stability of goat milk subjected to ultra-high temperature and in-container sterilization.

    Science.gov (United States)

    Chen, B Y; Grandison, A S; Lewis, M J

    2012-03-01

    Goat milk with and without stabilizing salt was subjected to in-container and UHT sterilization. Heat stability was assessed by measuring the amount of sediment in the milk. Without stabilizing salts, goat milk usually produced less sediment when subjected to in-container sterilization compared with UHT processing. Addition of stabilizing salts up to 12.8mM resulted in a progressive increase in sediment for in-container sterilization. In contrast, adding stabilizing salts at 6.4mM initially reduced sediment formation in UHT-treated milk but addition of stabilizing salts at 12.8mM increased sediment formation. Adding stabilizing salts to goat milk increased pH, decreased ionic calcium, and increased ethanol stability. Adding up to 2mM calcium chloride increased sediment formation more after UHT treatment than after in-container sterilization. These results suggest that no single mechanism or set of reactions causes milk to produce sediment during heating and that the favored pathway is different for UHT and in-container sterilization processes. Poor heat stability could be induced both by increasing ionic calcium and by decreasing it. Ethanol stability is not a good indicator of heat stability for in-container sterilization, but it may be for UHT sterilization, if milk does not enter the region of poor heat stability found at low concentrations of ionic calcium. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  15. Ultra high temperature gasification of municipal wastewater primary biosolids in a rotary kiln reactor for the production of synthesis gas.

    Science.gov (United States)

    Gikas, Petros

    2017-12-01

    Primary Fine-Sieved Solids (PFSS) are produced from wastewater by the use of micro-sieves, in place of primary clarification. Biosolids is considered as a nuisance product, however, it contains significant amounts of energy, which can be utilized by biological (anaerobic digestion) or thermal (combustion or gasification) processes. In the present study, an semi-industrial scale UHT rotary kiln gasifier, operating with electric energy, was employed for the gasification of PFSS (at 17% moisture content), collected from a municipal wastewater treatment plant. Two gasification temperatures (950 and 1050 °C) had been tested, with minimal differences, with respect to syngas yield. The system appears to reach steady state after about 30-40 min from start up. The composition of the syngas at near steady state was measured approximately as 62.4% H 2 , 30.0% CO, 2.4% CH 4 and 3.4% CO 2 , plus 1.8% unidentified gases. The potential for electric energy production from the syngas produced is theoretically greater than the electric energy required for gasification. Theoretically, approximately 3.8 MJ/kg PFSS of net electric energy may be produced. However, based on the measured electric energy consumption, and assuming that all the syngas produced is used for electric energy production, addition of excess electric energy (about 0.43 MJ/kg PFSS) is required to break even. The latter is probably due to heat losses to the environment, during the heating process. With the improvement of energy efficiency, the process can be self sustained, form the energy point of view. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. 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.

  17. 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.

  18. Use of sludge as ceramic materials

    International Nuclear Information System (INIS)

    Morais, L.C.; Vianna, R.S.C.; Campos, V.; Rosa, A.H.; Buechler, P.M.

    2009-01-01

    Nowadays, with increase amounts of sludge derived from the treatment of domestic sewage put pressure into research on systems for the adequate use of these materials. The aim of the present work is to study the use of sludge ash, from sintering and calcinated process, as a raw material for the ceramic industry. Using the sewage sludge ashes as ceramic raw material there will be no contamination of soil and underground water. Metals and toxic compounds like Al, Fe, Ba, Cr, Cu, Mn and Zn oxides were analyzed and characterized by X-ray fluorescence (XRF), scanning electron microscopy (SEM) and plasma emission spectroscopy (ICP-OES). The leached material was chemically analyzed where the integration of oxides into the ceramic matrix of sludge ash was observed. Residual decomposition was analyzed by TG, DTG and DTA curves. (author)

  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. NASA/CARES dual-use ceramic technology spinoff applications

    Science.gov (United States)

    Powers, Lynn M.; Janosik, Lesley A.; Gyekenyesi, John P.; Nemeth, Noel N.

    1994-01-01

    NASA has developed software that enables American industry to establish the reliability and life of ceramic structures in a wide variety of 21st Century applications. Designing ceramic components to survive at higher temperatures than the capability of most metals and in severe loading environments involves the disciplines of statistics and fracture mechanics. Successful application of advanced ceramics material properties and the use of a probabilistic brittle material design methodology. The NASA program, known as CARES (Ceramics Analysis and Reliability Evaluation of Structures), is a comprehensive general purpose design tool that predicts the probability of failure of a ceramic component as a function of its time in service. The latest version of this software, CARESALIFE, is coupled to several commercially available finite element analysis programs (ANSYS, MSC/NASTRAN, ABAQUS, COSMOS/N4, MARC), resulting in an advanced integrated design tool which is adapted to the computing environment of the user. The NASA-developed CARES software has been successfully used by industrial, government, and academic organizations to design and optimize ceramic components for many demanding applications. Industrial sectors impacted by this program include aerospace, automotive, electronic, medical, and energy applications. Dual-use applications include engine components, graphite and ceramic high temperature valves, TV picture tubes, ceramic bearings, electronic chips, glass building panels, infrared windows, radiant heater tubes, heat exchangers, and artificial hips, knee caps, and teeth.

  1. 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

  2. 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.

  3. 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

  4. 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 ...

  5. 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.

  6. 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.)

  7. 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...

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Integration

    DEFF Research Database (Denmark)

    Emerek, Ruth

    2004-01-01

    Bidraget diskuterer de forskellige intergrationsopfattelse i Danmark - og hvad der kan forstås ved vellykket integration......Bidraget diskuterer de forskellige intergrationsopfattelse i Danmark - og hvad der kan forstås ved vellykket integration...

  14. 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.

  15. [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.

  16. 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

  17. 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

  18. [Integrity].

    Science.gov (United States)

    Gómez Rodríguez, Rafael Ángel

    2014-01-01

    To say that someone possesses integrity is to claim that that person is almost predictable about responses to specific situations, that he or she can prudentially judge and to act correctly. There is a closed interrelationship between integrity and autonomy, and the autonomy rests on the deeper moral claim of all humans to integrity of the person. Integrity has two senses of significance for medical ethic: one sense refers to the integrity of the person in the bodily, psychosocial and intellectual elements; and in the second sense, the integrity is the virtue. Another facet of integrity of the person is la integrity of values we cherish and espouse. The physician must be a person of integrity if the integrity of the patient is to be safeguarded. The autonomy has reduced the violations in the past, but the character and virtues of the physician are the ultimate safeguard of autonomy of patient. A field very important in medicine is the scientific research. It is the character of the investigator that determines the moral quality of research. The problem arises when legitimate self-interests are replaced by selfish, particularly when human subjects are involved. The final safeguard of moral quality of research is the character and conscience of the investigator. Teaching must be relevant in the scientific field, but the most effective way to teach virtue ethics is through the example of the a respected scientist.

  19. 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...

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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...

  5. Flame-sintered ceramic exoelectron dosimeter samples

    International Nuclear Information System (INIS)

    Petel, M.; Holzapfel, G.

    1979-01-01

    New techniques for the preparation of integrating solid state dosimeters, particularly exoelectron dosimeters, have been initiated. The procedure consists in melting the powdered dosimeter materials in a hot, fast gas stream and depositing the ceramic layer. The gas stream is generated either through a chemical flame or by an electrical arc plasma. Results will be reported on the system Al 2 O 3 /stainless steel as a first step to a usable exoelectron dosimeter

  6. Composite treatment of ceramic tile armor

    Science.gov (United States)

    Hansen, James G. R. [Oak Ridge, TN; Frame, Barbara J [Oak Ridge, TN

    2010-12-14

    An improved ceramic tile armor has a core of boron nitride and a polymer matrix composite (PMC) facing of carbon fibers fused directly to the impact face of the tile. A polyethylene fiber composite backing and spall cover are preferred. The carbon fiber layers are cured directly onto the tile, not adhered using a separate adhesive so that they are integral with the tile, not a separate layer.

  7. 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

  8. 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.

  9. Novel, Ceramic Membrane System For Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    Elangovan, S.

    2012-12-31

    Separation of hydrogen from coal gas represents one of the most promising ways to produce alternative sources of fuel. Ceramatec, teamed with CoorsTek and Sandia National Laboratories has developed materials technology for a pressure driven, high temperature proton-electron mixed conducting membrane system to remove hydrogen from the syngas. This system separates high purity hydrogen and isolates high pressure CO{sub 2} as the retentate, which is amenable to low cost capture and transport to storage sites. The team demonstrated a highly efficient, pressure-driven hydrogen separation membrane to generate high purity hydrogen from syngas using a novel ceramic-ceramic composite membrane. Recognizing the benefits and limitations of present membrane systems, the all-ceramic system has been developed to address the key technical challenges related to materials performance under actual operating conditions, while retaining the advantages of thermal and process compatibility offered by the ceramic membranes. The feasibility of the concept has already been demonstrated at Ceramatec. This project developed advanced materials composition for potential integration with water gas shift rectors to maximize the hydrogenproduction.

  10. Clinical evaluation of prefabricated ceramic inlays

    Directory of Open Access Journals (Sweden)

    H Murali

    2016-01-01

    Full Text Available Background: One of the methods to overcome the problem of polymerization contraction of posterior composites is to use prefabricated ceramic inlays in combination with composites. Several studies have shown that these pre fabricated ceramic inlays act as mega fillers which allow a reduction in resin based composite volume by 50-75% and a concomitant reduction in polymerization shrinkage and marginal micro leakage. Moreover the integration of pre fabricated ceramic inlays into composites reduces the overall coefficient of thermal expansion. Aims and Objectives: The performance of cerena prefabricated inlay system was evaluated. Material and Methods: 20 proximo occlusal cavities were restored with cerana prefabricated inlay system in patients. The performance of cerena pre fabricated inlay system in the oral cavity was recorded at base line follow up using Modified USPHS Ryge criteria at the end of 3, 6, and 12 months. Results: The alpha and Bravo values for the anatomic form, marginal integrity and caries assessment was evaluated. Alpha values were ideal. The Cerena pre- fabricated inlay system showed good fracture resistance, good marginal integrity and maintenance of antomic forms at end of 12 months period. Conclusion: The cerena pre-fabricated inlay system is a good treatment modality and provides a good restorative material at the end of 12 months too.

  11. 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).

  12. 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

  13. 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)

  14. Instrumental neutron activation analysis potentialities in archaeological ceramics studies

    International Nuclear Information System (INIS)

    Paiva, Rosemeire P.; Munita, Casimirio S.; Alves, Marcia A.

    1999-01-01

    In this work, precision and sensitivity of the determination of As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Sb, Sc, Sm, Ta, Tb, Th, U, Yb and Zn in ceramic samples by INAA were evaluated. Two clay samples Brick Clay (NIST-SRM-697 reference material)and Ohio Red Clay (a well known clay sample) were analyzed for this purpose. Archaeological ceramic fragments from Agua Limpa Site, in Monte Alto city, SP were also analyzed. The archaeological ceramics were produced in the quotidian activities of non writing preterite societies, in sedentarization process. The ceramic chemical information are used to identify raw material sources and to study production and distribution models, which allow the reconstruction of the socio-cultural development and integration of extinguished societies. (author)

  15. 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)

  16. 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)

  17. 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.

  18. 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

  19. 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

  20. 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

  1. 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.

  2. KROME Ceramics: color management system for the ceramics industry; KROME: Ceramics Sistema de gestion del color para la industra ceramica

    Energy Technology Data Exchange (ETDEWEB)

    Martin, A.; Luque, J.; Pla, O.; Selvi, S.

    2013-05-01

    Digital Decoration Systems, SL (DIGIT-S) with Unicer, SL, has implemented a system to improve and optimize the process of decorating by inkjet printing for ceramic industry. It provides a comprehensive solution, KROME Ceramics, to improve the cost effectiveness of product and process through the implementation of a working system based on the control of digital decoration process and the synchronization of all elements that make up the decorative modules, including the creation of a work flow, management of files that are generated during the process, a correct color management system, and of course, optimizing and evaluating ink jet inks integrating all elements involved: Lighting, Computer, Software, Monitor, Plotter, Paper, Ink, Ink jet, Body's, Enamels and Oven. (Author)

  3. 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

  4. Investigations on the performance of ultrasonic drilling process with special reference to precision machining of advanced ceramics

    International Nuclear Information System (INIS)

    Adithan, M.; Laroiya, S.C.

    1997-01-01

    Advanced ceramics are assuming an important role in modern industrial technology. The applications and advantages of using advanced ceramics are many. There are several reasons why we should go in for machining of advanced ceramics after their compacting and sintering. These are discussed in this paper. However, precision machining of advanced ceramics must be economical. Critical technological issues to be addressed in cost effective machining of ceramics include design of machine tools, tooling arrangements, improved yield and precision, relationship of part dimensions and finish specifications to functional performance, and on-line inspection. Considering the above ultrasonic drilling is an important process used for the precision machining of advanced ceramics. Extensive studies on tool wear occurring in the ultrasonic machining of advanced ceramics have been carried out. In addition, production accuracy of holes drilled, surface finish obtained and surface integrity aspects in the machining of advanced ceramics have also been investigated. Some specific findings with reference to surface integrity are: a) there were no cracks or micro-cracks developed during or after ultrasonic machining of advanced ceramics, b) while machining Hexoloy alpha silicon carbide a recast layer is formed as a result of ultrasonic machining. This is attributed to the viscous heating resulting from high energy impacts during ultrasonic machining. While machining all other types of ceramics no such formation of recast layer was observed, and , c) there is no change in the microstructure of the advanced ceramics as a result of ultrasonic machining

  5. Microstructure of Matrix in UHTC Composites

    Science.gov (United States)

    Johnson, Sylvia; Stackpoole, Margaret; Gusman, Michael I.; Chavez-Garia Jose; Doxtad, Evan

    2011-01-01

    Approaches to controlling the microstructure of Ultra High Temperature Ceramics (UHTCs) are described.. One matrix material has been infiltrated into carbon weaves to make composite materials. The microstructure of these composites is described.

  6. 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.

  7. 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

  8. 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.

  9. Influence of resin cement shade on the color and translucency of ceramic veneers

    Science.gov (United States)

    HERNANDES, Daiana Kelly Lopes; ARRAIS, Cesar Augusto Galvão; de LIMA, Erick; CESAR, Paulo Francisco; RODRIGUES, José Augusto

    2016-01-01

    ABSTRACT Objective This in vitro study evaluated the effect of two different shades of resin cement (RC- A1 and A3) layer on color change, translucency parameter (TP), and chroma of low (LT) and high (HT) translucent reinforced lithium disilicate ceramic laminates. Material and Methods One dual-cured RC (Variolink II, A1- and A3-shade, Ivoclar Vivadent) was applied to 1-mm thick ceramic discs to create thin RC films (100 µm thick) under the ceramics. The RC was exposed to light from a LED curing unit. Color change (ΔE) of ceramic discs was measured according to CIEL*a*b* system with a standard illuminant D65 in reflectance mode in a spectrophotometer, operating in the light range of 360-740 nm, equipped with an integrating sphere. The color difference between black (B) and white (W) background readings was used for TP analysis, while chroma was calculated by the formula C* ab=(a*2+b*2)½. ΔE of 3.3 was set as the threshold of clinically unacceptable. The results were evaluated by two-way ANOVA followed by Tukey's post hoc test. Results HT ceramics showed higher ΔE and higher TP than LT ceramics. A3-shade RC promoted higher ΔE than A1-shade cement, regardless of the ceramic translucency. No significant difference in TP was noted between ceramic discs with A1- and those with A3-shade cement. Ceramic with underlying RC showed lower TP than discs without RC. HT ceramics showed lower chroma than LT ceramics, regardless of the resin cement shade. The presence of A3-shade RC resulted in higher chroma than the presence of A1-shade RC. Conclusions Darker underlying RC layer promoted more pronounced changes in ceramic translucency, chroma, and shade of high translucent ceramic veneers. These differences may not be clinically differentiable. PMID:27556211

  10. Influence of resin cement shade on the color and translucency of ceramic veneers

    Directory of Open Access Journals (Sweden)

    Daiana Kelly Lopes HERNANDES

    Full Text Available ABSTRACT Objective This in vitro study evaluated the effect of two different shades of resin cement (RC- A1 and A3 layer on color change, translucency parameter (TP, and chroma of low (LT and high (HT translucent reinforced lithium disilicate ceramic laminates. Material and Methods One dual-cured RC (Variolink II, A1- and A3-shade, Ivoclar Vivadent was applied to 1-mm thick ceramic discs to create thin RC films (100 µm thick under the ceramics. The RC was exposed to light from a LED curing unit. Color change (ΔE of ceramic discs was measured according to CIEL*a*b* system with a standard illuminant D65 in reflectance mode in a spectrophotometer, operating in the light range of 360-740 nm, equipped with an integrating sphere. The color difference between black (B and white (W background readings was used for TP analysis, while chroma was calculated by the formula C*ab=(a*2+b*2½. ΔE of 3.3 was set as the threshold of clinically unacceptable. The results were evaluated by two-way ANOVA followed by Tukey's post hoc test. Results HT ceramics showed higher ΔE and higher TP than LT ceramics. A3-shade RC promoted higher ΔE than A1-shade cement, regardless of the ceramic translucency. No significant difference in TP was noted between ceramic discs with A1- and those with A3-shade cement. Ceramic with underlying RC showed lower TP than discs without RC. HT ceramics showed lower chroma than LT ceramics, regardless of the resin cement shade. The presence of A3-shade RC resulted in higher chroma than the presence of A1-shade RC. Conclusions Darker underlying RC layer promoted more pronounced changes in ceramic translucency, chroma, and shade of high translucent ceramic veneers. These differences may not be clinically differentiable.

  11. Influence of resin cement shade on the color and translucency of ceramic veneers.

    Science.gov (United States)

    Hernandes, Daiana Kelly Lopes; Arrais, Cesar Augusto Galvão; Lima, Erick de; Cesar, Paulo Francisco; Rodrigues, José Augusto

    2016-01-01

    This in vitro study evaluated the effect of two different shades of resin cement (RC- A1 and A3) layer on color change, translucency parameter (TP), and chroma of low (LT) and high (HT) translucent reinforced lithium disilicate ceramic laminates. One dual-cured RC (Variolink II, A1- and A3-shade, Ivoclar Vivadent) was applied to 1-mm thick ceramic discs to create thin RC films (100 µm thick) under the ceramics. The RC was exposed to light from a LED curing unit. Color change (ΔE) of ceramic discs was measured according to CIEL*a*b* system with a standard illuminant D65 in reflectance mode in a spectrophotometer, operating in the light range of 360-740 nm, equipped with an integrating sphere. The color difference between black (B) and white (W) background readings was used for TP analysis, while chroma was calculated by the formula C*ab=(a*2+b*2)½. ΔE of 3.3 was set as the threshold of clinically unacceptable. The results were evaluated by two-way ANOVA followed by Tukey's post hoc test. HT ceramics showed higher ΔE and higher TP than LT ceramics. A3-shade RC promoted higher ΔE than A1-shade cement, regardless of the ceramic translucency. No significant difference in TP was noted between ceramic discs with A1- and those with A3-shade cement. Ceramic with underlying RC showed lower TP than discs without RC. HT ceramics showed lower chroma than LT ceramics, regardless of the resin cement shade. The presence of A3-shade RC resulted in higher chroma than the presence of A1-shade RC. Darker underlying RC layer promoted more pronounced changes in ceramic translucency, chroma, and shade of high translucent ceramic veneers. These differences may not be clinically differentiable.

  12. 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.

  13. 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)

  14. 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.

  15. 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.

  16. 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)

  17. 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

  18. 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.

  19. 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 ...

  20. 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.)

  1. 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

  2. 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.

  3. 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

  4. Additive Manufacturing of SiC Based Ceramics and Ceramic Matrix Composites

    Science.gov (United States)

    Halbig, Michael Charles; Singh, Mrityunjay

    2015-01-01

    Silicon carbide (SiC) ceramics and SiC fiber reinforcedSiC ceramic matrix composites (SiCSiC CMCs) offer high payoff as replacements for metals in turbine engine applications due to their lighter weight, higher temperature capability, and lower cooling requirements. Additive manufacturing approaches can offer game changing technologies for the quick and low cost fabrication of parts with much greater design freedom and geometric complexity. Four approaches for developing these materials are presented. The first two utilize low cost 3D printers. The first uses pre-ceramic pastes developed as feed materials which are converted to SiC after firing. The second uses wood containing filament to print a carbonaceous preform which is infiltrated with a pre-ceramic polymer and converted to SiC. The other two approaches pursue the AM of CMCs. The first is binder jet SiC powder processing in collaboration with rp+m (Rapid Prototyping+Manufacturing). Processing optimization was pursued through SiC powder blending, infiltration with and without SiC nano powder loading, and integration of nanofibers into the powder bed. The second approach was laminated object manufacturing (LOM) in which fiber prepregs and laminates are cut to shape by a laser and stacked to form the desired part. Scanning electron microscopy was conducted on materials from all approaches with select approaches also characterized with XRD, TGA, and bend testing.

  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. 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.

  7. 'Integration'

    DEFF Research Database (Denmark)

    Olwig, Karen Fog

    2011-01-01

    , while the countries have adopted disparate policies and ideologies, differences in the actual treatment and attitudes towards immigrants and refugees in everyday life are less clear, due to parallel integration programmes based on strong similarities in the welfare systems and in cultural notions...... of equality in the three societies. Finally, it shows that family relations play a central role in immigrants’ and refugees’ establishment of a new life in the receiving societies, even though the welfare society takes on many of the social and economic functions of the family....

  8. Advanced industrial ceramic heat pipe recuperators

    Energy Technology Data Exchange (ETDEWEB)

    Strumpf, H.J.; Stillwagon, T.L.; Kotchick, D.M.; Coombs, M.G.

    1988-01-01

    This paper summarizes the results of an investigation involving the use of ceramic heat pipe recuperators for high-temperature heat recovery from industrial furnaces. The function of the recuperator is to preheat combustion air with furnace exhaust gas. The heat pipe recuperator comprises a bundle of individual ceramic heat pipes acting in concert, with a partition separating the air and exhaust gas flow streams. Because each heat pipe is essentially an independent heat exchanger, the failure of a single tube does not compromise recuperator integrity, has only a minimal effect on overall heat exchanger performance and enables easier replacement of individual heat pipes. In addition, the heat pipe acts as an essentially isothermal heat transfer device, leading to a high thermodynamic efficiency. Cost estimates developed for heat pipe recuperator systems indicate favorable payback periods. Laboratory studies have demonstrated the feasibility of fabricating the required ceramic tubes, coating the inside of the tubes with CVD tungsten, and sealing the heat pipe with an electron-beam-welded or vacuum-brazed end cap.

  9. 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.

  10. Relative translucency of six all-ceramic systems. Part I: core materials.

    Science.gov (United States)

    Heffernan, Michael J; Aquilino, Steven A; Diaz-Arnold, Ana M; Haselton, Debra R; Stanford, Clark M; Vargas, Marcos A

    2002-07-01

    All-ceramic restorations have been advocated for superior esthetics. Various materials have been used to improve ceramic core strength, but it is unclear whether they affect the opacity of all-ceramic systems. This study compared the translucency of 6 all-ceramic system core materials at clinically appropriate thicknesses. Disc specimens 13 mm in diameter and 0.49 +/- 0.01 mm in thickness were fabricated from the following materials (n = 5 per group): IPS Empress dentin, IPS Empress 2 dentin, In-Ceram Alumina core, In-Ceram Spinell core, In-Ceram Zirconia core, and Procera AllCeram core. Empress and Empress 2 dentin specimens also were fabricated and tested at a thickness of 0.77 +/- 0.02 mm (the manufacturer's recommended core thickness is 0.8 mm). A high-noble metal-ceramic alloy (Porc. 52 SF) served as the control, and Vitadur Alpha opaque dentin was used as a standard. Sample reflectance (ratio of the intensity of reflected light to that of the incident light) was measured with an integrating sphere attached to a spectrophotometer across the visible spectrum (380 to 700 nm); 0-degree illumination and diffuse viewing geometry were used. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white (Yw) backing to give Yb/Yw with CIE illuminant D65 and a 2-degree observer function (0.0 = transparent, 1.0 = opaque). One-way analysis of variance and Tukey's multiple-comparison test were used to analyze the data (P In-Ceram Spinell > Empress, Procera, Empress 2 > In-Ceram Alumina > In-Ceram Zirconia, 52 SF alloy.

  11. 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

  12. 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)

  13. 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:

  14. 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:

  15. Preparation techniques for ceramic waste form powder

    International Nuclear Information System (INIS)

    Hash, M.C.; Pereira, C.; Lewis, M.A.

    1997-01-01

    The electrometallurgical treatment of spent nuclear fuels result in a chloride waste salt requiring geologic disposal. Argonne National Laboratory (ANL) is developing ceramic waste forms which can incorporate this waste. Currently, zeolite- or sodalite-glass composites are produced by hot isostatic pressing (HIP) techniques. Powder preparations include dehydration of the raw zeolite powders, hot blending of these zeolite powders and secondary additives. Various approaches are being pursued to achieve adequate mixing, and the resulting powders have been HIPed and characterized for leach resistance, phase equilibria, and physical integrity

  16. 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...

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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

  3. 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)

  4. 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)

  5. 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

  6. 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.

  7. Ceramic membrane defouling (cleaning) by air Nano Bubbles.

    Science.gov (United States)

    Ghadimkhani, Aliasghar; Zhang, Wen; Marhaba, Taha

    2016-03-01

    Ceramic membranes are among the most promising technologies for membrane applications, owing to their excellent resistance to mechanical, chemical, and thermal stresses. However, membrane fouling is still an issue that hampers the applications at large scales. Air Nano Bubbles (NBs), due to high mass transfer efficiency, could potentially prevent fouling of ceramic membrane filtration processes. In this study, bench and pilot scale ceramic membrane filtration was performed with air NBs to resist fouling. To simulate fouling, humic acid, as an organic foulant, was applied to the membrane flat sheet surface. Complete membrane clogging was achieved in less than 6 h. Membrane defouling (cleaning) was performed by directly feeding of air NBs to the membrane cells. The surface of the ceramic membrane was superbly cleaned by air NBs, as revealed by atomic force microscope (AFM) images before and after the treatment. The permeate flux recovered to its initial level (e.g., 26.7 × 10(-9) m(3)/m(2)/s at applied pressure of 275.8 kPa), which indicated that NBs successfully unclogged the pores of the membrane. The integrated ceramic membrane and air NBs system holds potential as an innovative sustainable technology. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. 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.

  9. 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...

  10. 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

  11. 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

  12. 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.

  13. 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.

  14. 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

  15. 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.)

  16. 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

  17. 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...

  18. 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.

  19. Effect of ceramic calcium-phosphorus ratio on chondrocyte-mediated biosynthesis and mineralization.

    Science.gov (United States)

    Boushell, Margaret K; Khanarian, Nora T; LeGeros, Raquel Z; Lu, Helen H

    2017-10-01

    The osteochondral interface functions as a structural barrier between cartilage and bone, maintaining tissue integrity postinjury and during homeostasis. Regeneration of this calcified cartilage region is thus essential for integrative cartilage healing, and hydrogel-ceramic composite scaffolds have been explored for calcified cartilage formation. The objective of this study is to test the hypothesis that Ca/P ratio of the ceramic phase of the composite scaffold regulates chondrocyte biosynthesis and mineralization potential. Specifically, the response of deep zone chondrocytes to two bioactive ceramics with different calcium-phosphorus ratios (1.35 ± 0.01 and 1.41 ± 0.02) was evaluated in agarose hydrogel scaffolds over two weeks in vitro. It was observed that the ceramic with higher calcium-phosphorus ratio enhanced chondrocyte proliferation, glycosaminoglycan production, and induced an early onset of alkaline phosphorus activity, while the ceramic with lower calcium-phosphorus ratio performed similarly to the ceramic-free control. These results underscore the importance of ceramic bioactivity in directing chondrocyte response, and demonstrate that Ca/P ratio is a key parameter to be considered in osteochondral scaffold design. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2694-2702, 2017. © 2017 Wiley Periodicals, Inc.

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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)

  6. 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.

  7. 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.

  8. Implementation Challenges for Sintered Silicon Carbide Fiber Bonded Ceramic Materials for High Temperature Applications

    Science.gov (United States)

    Singh, M.

    2011-01-01

    During the last decades, a number of fiber reinforced ceramic composites have been developed and tested for various aerospace and ground based applications. However, a number of challenges still remain slowing the wide scale implementation of these materials. In addition to continuous fiber reinforced composites, other innovative materials have been developed including the fibrous monoliths and sintered fiber bonded ceramics. The sintered silicon carbide fiber bonded ceramics have been fabricated by the hot pressing and sintering of silicon carbide fibers. However, in this system reliable property database as well as various issues related to thermomechanical performance, integration, and fabrication of large and complex shape components has yet to be addressed. In this presentation, thermomechanical properties of sintered silicon carbide fiber bonded ceramics (as fabricated and joined) will be presented. In addition, critical need for manufacturing and integration technologies in successful implementation of these materials will be discussed.

  9. 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...

  10. 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

  11. 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.

  12. 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)

  13. 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

  14. Cermet insert high voltage holdoff for ceramic/metal vacuum devices

    Science.gov (United States)

    Ierna, William F.

    1987-01-01

    An improved metal-to-ceramic seal is provided wherein the ceramic body of the seal contains an integral region of cermet material in electrical contact with the metallic member, e.g., an electrode, of the seal. The seal is useful in high voltage vacuum devices, e.g., vacuum switches, and increases the high-voltage holdoff capabilities of such devices. A method of fabricating such seals is also provided.

  15. Cermet insert high voltage holdoff improvement for ceramic/metal vacuum devices

    Science.gov (United States)

    Ierna, W.F.

    1986-03-11

    An improved metal-to-ceramic seal is provided wherein the ceramic body of the seal contains an integral region of cermet material in electrical contact with the metallic member, e.g., an electrode, of the seal. The seal is useful in high voltage vacuum devices, e.g., vacuum switches, and increases the high-voltage holdoff capabilities of such devices. A method of fabricating such seals is also provided.

  16. State of Theory and Computer Simulations of Radiation Effects in Ceramics

    International Nuclear Information System (INIS)

    Corrales, Louis R.; Weber, William J.

    2003-01-01

    This article presents opinions based on the presentations and discussions at a Workshop on Theory and Computer Simulations of Radiation Effects in Ceramics held in August 2002 at Pacific Northwest National Laboratory in Richland, WA, USA. The workshop was focused on the current state-of-the-art of theory, modeling and simulation of radiation effects in oxide ceramics, directions for future breakthroughs, and creating a close integration with experiment

  17. Microstructure and fracture analysis of fully ceramic microencapsulated fuel

    International Nuclear Information System (INIS)

    Lee, H. G.; Kim, D. J.; Park, J. Y.; Kim, W. J.; Lee, S. J.

    2015-01-01

    Nuclear fuel enhancing the accident tolerance is satisfied two parts. First, the performance has to be retained compared to the existing UO 2 nuclear fuel and zircaloy cladding system under the normal operation condition. Second, under the severe accident condition, the high temperature structural integrity has to be kept and the generation rate of hydrogen has to be reduced largely. FCM nuclear fuel is composed of tristructural isotropic(TRISO) fuel particle and SiC ceramic matrix. SiC ceramic matrix play an essential part in protecting fission product. In the FCM fuel concept, fission product is doubly protected by TRISO coating layer and SiC ceramic matrix compared to the current commercial UO 2 fuel system. SiC ceramic has excellent properties for fuel application. SiC ceramic has low neutron absorption cross-section, excellent irradiation resistivity and high thermal conductivity. Additionally, the relative thermal conductivity of the SiC ceramic as compared to UO 2 is quite good, reducing operational release of fission products form the fuel. TRISO coating layer which is deposited on UO 2 kernel is consists of PyC/SiC/PyC trialyer and buffer PyC layer. SiC matrix composite with TRISO particle was fabricated by hot pressing. 3 to 20 wt.% of sintering additives were added to investigate reaction between sintering additives and outer PyC layer of TRISO coating layer. The relative densities of all specimens show above 92%. The reaction between sintering additives and PyC is observed in most TRISO particles, the thickness of reactants shows about ten micrometers. The thermal shock resistance of SiC matrix composite was investigated

  18. 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

  19. 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.

  20. 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.

  1. Hydrodynamic modeling and explosive compaction of ceramics

    International Nuclear Information System (INIS)

    Hoenig, C.; Holt, A.; Finger, M.; Kuhl, W.

    1977-01-01

    High-density ceramics with high-strength microstructure were achieved by explosive compaction. Well-characterized Al 2 O 3 , AlN, and boron powders were explosively compacted in both cylindrical and flat plate geometries. In cylindrical geometries compacted densities between 91 and 98 percent of theoretical were achieved. Microhardness measurements indicated that the strength and integrity of the microstructure were comparable to conventionally fabricated ceramics, even though all samples with densities greater than 90 percent theoretical contained macrocracks. Fractured surfaces evaluated by SEM showed evidence of boundary melting. Equation of state data for porous Al 2 O 3 were used to calculate the irreversible work done on the sample as a function of pressure. This was expressed as a percentage of the total sample which could be melted. Calculations show that very little melting can be expected in samples shocked to less than 3 GPa. Significant melting and grain boundary fusion can be expected in samples shocked to pressures greater than 8 GPa. Hydrodynamic modeling of right cylinder compaction with detonation at one end was attempted by using a two-dimensional computer code. The complications of this analysis led to experiments using plane shock waves. Flat-plate compaction assemblies were designed and analyzed by 2-D hydrodynamic codes. The use of porous shock attenuators was evaluated. Experiments were performed on aluminum oxide powders in plane wave geometry. Microstructure evaluations were made as a function of location in the flat plate samples. 11 figures, 1 table

  2. 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.

  3. 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.

  4. 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)

  5. The post collisional metamorphic evolution from Ultra High Temperature to Amphibolite facies metamorphism in the Odesan area during the Triassic collision between the North and South China cratons.

    Science.gov (United States)

    Lee, Byung Choon; Oh, Chang Whan; Kim, Tae Sung; Yi, Kee Wook

    2015-04-01

    The Odaesan Gneiss Complex (OGC) is the eastern end of the Hongseong-Odesan collision belt in Korean Peninsula which is the extension of the Dabie-Sulu collision belt between the North and South China blocks. The OGC mainly consists of banded and migmatitic gneiss with porphyritic granitoid and amphibolite. The banded gneiss can be subdivided into garnet-biotite and garnet-orthopyroxene banded gneisses. The highest metamorphic P/T conditions of the migmatitic and garnet-biotite banded gneiss were 760-820°C/6.3-7.2kbar and 810-840°C/7.2-7.8kbar respectively. On the other hand, the garnet-orthopyroxene banded gneiss records 940-950°C/10.5-10.7kbar that is corresponded to UHT metamorphic condition. These data indicate that the peak UHT metamorphic condition of the study area was preserved only within the garnet-orthopyroxene banded gneiss because its lower water content than other gneisses and UHT metamorphic mineral assemblage was completely replaced by the granulite facies metamorphism in other gneisses due to their higher water content than the garnet-orthopyroxene banded gneiss. Finally all gneisses experienced amphibolite facies retrograde metamorphism which is observed locally within rocks, such as garnet rim and surrounding area. The peak UHT metamorphism is estimated to occur at ca. 250-230 Ma using SHRIMP zircon U-Pb age dating and was caused by the heat supplied from asthenospheric mantle through the opening formed by slab break-off during early post collision stage. The calculated metamorphic conditions represent that geothermal gradient of the study area during the post collision stage was 86°C/kbar indicating the regional low-P/T metamorphic event. Besides the Triassic metamorphic age, two Paleoproterozoic metamorphic ages of ca. 1930 and 1886 Ma are also recognized by the SHRIMP age dating from the banded gneisses and Paleoproterozoic emplacement age of ca. 1847 Ma is identified from the porphyritic granitoid which formed in the within plate tectonic setting. These ages are well matched with 1880Ma-1885Ma regional post-collision igneous and metamorphic activities in other areas of the GM indicating that the OGC had undergone Paleoproterozoic metamorphic and igneous activities before the Triassic metamorphism. However it is difficult to confirm the Paleoproterozoic activities due to the strong Triassic metamorphism.

  6. Stability of TaC precipitates in a Co-Re-based alloy being developed for ultra-high-temperature applications

    Czech Academy of Sciences Publication Activity Database

    Gilles, R.; Mukherji, D.; Karge, L.; Strunz, Pavel; Beran, Přemysl; Barbier, B.; Kriele, A.; Hofmann, M.; Eckerlebe, H.; Rösler, J.

    2016-01-01

    Roč. 49, č. 4 (2016), s. 1253-1265 ISSN 1600-5767 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389005 Keywords : high-temperature alloys * precipitates * small-angle neutron scattering * phase transformation * X-ray diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.495, year: 2016

  7. Analytical, Numerical, and Experimental Investigation on a Non-Contact Method for the Measurements of Creep Properties of Ultra-High-Temperature Materials

    Science.gov (United States)

    Lee, Jonghyun; Hyers, Robert W.; Rogers, Jan R.; Rathz, Thomas J.; Choo, Hahn; Liaw, Peter

    2006-01-01

    Responsive access to space requires re-use of components such as rocket nozzles that operate at extremely high temperatures. For such applications, new ultra-hightemperature materials that can operate over 2,000 C are required. At the temperatures higher than the fifty percent of the melting temperature, the characterization of creep properties is indispensable. Since conventional methods for the measurement of creep is limited below 1,700 C, a new technique that can be applied at higher temperatures is strongly demanded. This research develops a non-contact method for the measurement of creep at the temperatures over 2,300 C. Using the electrostatic levitator in NASA MSFC, a spherical sample was rotated to cause creep deformation by centrifugal acceleration. The deforming sample was captured with a digital camera and analyzed to measure creep deformation. Numerical and analytical analyses have also been conducted to compare the experimental results. Analytical, numerical, and experimental results showed a good agreement with one another.

  8. Current status of Co-Re-based alloys being developed to supplement Ni-based superalloys for ultra-high temperature applications in gas turbines

    Czech Academy of Sciences Publication Activity Database

    Mukherji, D.; Strunz, Pavel; Gilles, R.; Karge, L.; Rösler, J.

    2015-01-01

    Roč. 53, č. 4 (2015), s. 287-294 ISSN 0023-432X EU Projects: European Commission(XE) 283883 - NMI3-II Institutional support: RVO:61389005 Keywords : Co-base alloy * scanning electron microscopy (SEM) * neutron scattering Subject RIV: JG - Metallurgy Impact factor: 0.365, year: 2015

  9. Improved Spectral Resolution of Long-Period Fiber Grating Sensors for Ultra-High Temperature Environments Using Narrow Interferences between Regenerated Gratings

    DEFF Research Database (Denmark)

    Kristensen, Martin; Russell, J; Gao, Shaorui

    2014-01-01

    The advantages of D-shape fiber in combination with an optical analog of Ramsey fringes using LPGs are presented. The mode-profiles of the sensor were characterized experimentally to provide deeper knowledge about improved functionality.......The advantages of D-shape fiber in combination with an optical analog of Ramsey fringes using LPGs are presented. The mode-profiles of the sensor were characterized experimentally to provide deeper knowledge about improved functionality....

  10. Basic research for alloy design of Nb-base alloys as ultra high temperature structural materials; Chokoon kozoyo niobuki gokin no gokin sekkei no tame no kisoteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Miura, E [Tohoku University, Sendai (Japan); Yoshimi, K; Hanada, S [Tohoku Univ., Sendai (Japan). Research Inst. for Iron, Steel and Other Metals

    1997-02-01

    This paper describes an influence of additional elements on the high temperature deformation behavior of Nb-base solid solution alloys. Highly concentrated solid solution single crystals of Nb-Ta and Nb-Mo alloys were prepared. Compression test and strain rate sudden change test were conducted in the vacuum at temperatures ranging from 77 to 1773 K, to determine the strain rate sensitivity index. Yield stress of the Nb-Ta alloy was similar to that of Nb alloy at temperatures over 0.3{times}T{sub M}, where T{sub M} is fusing point of Nb. While, the yield stress increased with increasing the impurity oxygen concentration at temperatures below 0.3{times}T{sub M}. The yield stress became much higher than that of Nb alloy. The strain rate sensitivity index showed positive values in the whole temperature range. On the other hand, the yield stress of Nb-Mo alloy was higher than that of Nb alloy in the whole temperature range, and increased with increasing the Mo concentration. The strain rate sensitivity index showed negative values at the temperature range from 0.3{times}T{sub M} to 0.4{times}T{sub M}. It was found that serration occurred often for Nb-40Mo alloys. 1 ref., 4 figs., 1 tab.

  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. 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...

  18. 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

  19. 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...

  20. 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.

  1. 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.

  2. 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

  3. 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

  4. 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.)

  5. Ceramic process and plant design for high-level nuclear waste immobilization

    International Nuclear Information System (INIS)

    Grantham, L.F.; McKisson, R.L.; De Wames, R.E.; Guon, J.; Flintoff, J.F.; McKenzie, D.E.

    1983-01-01

    In the last 3 years, significant advances in ceramic technology for high-level nuclear waste solidification have been made. Product quality in terms of leach-resistance, compositional uniformity, structural integrity, and thermal stability promises to be superior to borosilicate glass. This paper addresses the process effectiveness and preliminary designs for glass and ceramic immobilization plants. The reference two-step ceramic process utilizes fluid-bed calcination (FBC) and hot isostatic press (HIP) consolidation. Full-scale demonstration of these well-developed processing steps has been established at DOE and/or commercial facilities for processing radioactive materials. Based on Savannah River-type waste, our model predicts that the capital and operating cost for the solidification of high-level nuclear waste is about the same for the ceramic and glass options. However, when repository costs are included, the ceramic option potentially offers significantly better economics due to its high waste loading and volume reduction. Volume reduction impacts several figures of merit in addition to cost such as system logistics, storage, transportation, and risk. The study concludes that the ceramic product/process has many potential advantages, and rapid deployment of the technology could be realized due to full-scale demonstrations of FBC and HIP technology in radioactive environments. Based on our finding and those of others, the ceramic innovation not only offers a viable backup to the glass reference process but promises to be a viable future option for new high-level nuclear waste management opportunities

  6. ASSESSMENT OF CERAMIC TILE FROST RESISTANCE BY MEANS OF THE FREQUENCY INSPECTION METHOD

    Directory of Open Access Journals (Sweden)

    MICHAL MATYSÍK

    2011-06-01

    Full Text Available The paper presents some results of our experimental analysis of ceramic cladding element frost resistance, particular attention being paid to the application of the frequency inspection method. Three different sets of ceramic tiles of the Ia class to EN 14 411 B standard made by various manufacturers have been analyzed. The ceramic tiles under investigation have been subjected to freeze-thaw-cycle-based degradation in compliance with the relevant ČSN EN ISO 10545-12 standard. Furthermore, accelerated degradation procedure has been applied to selected test specimens, consisting in reducing the temperature of water soaked ceramic tiles in the course of the degradation cycles down –70°C. To verify the correctness of the frequency inspection results, additional physical properties of the ceramic tiles under test have been measured, such as, the ceramic tile strength limit, modulus of elasticity and modulus of deformability, resulting from the flexural tensile strength tests, integrity defect and surface micro-geometry tracking. It has been proved that the acoustic method of frequency inspection is a sensitive indicator of the structure condition and can be applied to the ceramic cladding element frost resistance and service life prediction assessment.

  7. Cementation of Glass-Ceramic Posterior Restorations: A Systematic Review

    Science.gov (United States)

    van den Breemer, Carline R. G.; Gresnigt, Marco M. M.; Cune, Marco S.

    2015-01-01

    Aim. The aim of this comprehensive review is to systematically organize the current knowledge regarding the cementation of glass-ceramic materials and restorations, with an additional focus on the benefits of Immediate Dentin Sealing (IDS). Materials and Methods. An extensive literature search concerning the cementation of single-unit glass-ceramic posterior restorations was conducted in the databases of MEDLINE (Pubmed), CENTRAL (Cochrane Central Register of Controlled Trials), and EMBASE. To be considered for inclusion, in vitro and in vivo studies should compare different cementation regimes involving a “glass-ceramic/cement/human tooth” complex. Results and Conclusions. 88 studies were included in total. The in vitro data were organized according to the following topics: (micro)shear and (micro)tensile bond strength, fracture strength, and marginal gap and integrity. For in vivo studies survival and quality of survival were considered. In vitro studies showed that adhesive systems (3-step, etch-and-rinse) result in the best (micro)shear bond strength values compared to self-adhesive and self-etch systems when luting glass-ceramic substrates to human dentin. The highest fracture strength is obtained with adhesive cements in particular. No marked clinical preference for one specific procedure could be demonstrated on the basis of the reviewed literature. The possible merits of IDS are most convincingly illustrated by the favorable microtensile bond strengths. No clinical studies regarding IDS were found. PMID:26557651

  8. Manganite perovskite ceramics, their precursors and methods for forming

    Science.gov (United States)

    Payne, David Alan; Clothier, Brent Allen

    2015-03-10

    Disclosed are a variety of ceramics having the formula Ln.sub.1-xM.sub.xMnO.sub.3, where 0.Itoreq.x.Itoreq.1 and where Ln is La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu or Y; M is Ca, Sr, Ba, Cd, or Pb; manganite precursors for preparing the ceramics; a method for preparing the precursors; and a method for transforming the precursors into uniform, defect-free ceramics having magnetoresistance properties. The manganite precursors contain a sol and are derived from the metal alkoxides: Ln(OR).sub.3, M(OR).sub.2 and Mn(OR).sub.2, where R is C.sub.2 to C.sub.6 alkyl or C.sub.3 to C.sub.9 alkoxyalkyl, or C.sub.6 to C.sub.9 aryl. The preferred ceramics are films prepared by a spin coating method and are particularly suited for incorporation into a device such as an integrated circuit device.

  9. 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

  10. 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

  11. 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.

  12. 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)

  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. High temperature ceramic-tubed reformer

    Science.gov (United States)

    Williams, Joseph J.; Rosenberg, Robert A.; McDonough, Lane J.

    1990-03-01

    The overall objective of the HiPHES project is to develop an advanced high-pressure heat exchanger for a convective steam/methane reformer. The HiPHES steam/methane reformer is a convective, shell and tube type, catalytic reactor. The use of ceramic tubes will allow reaction temperature higher than the current state-of-the-art outlet temperatures of about 1600 F using metal tubes. Higher reaction temperatures increase feedstock conversion to synthesis gas and reduce energy requirements compared to currently available radiant-box type reformers using metal tubes. Reforming of natural gas is the principal method used to produce synthesis gas (primarily hydrogen and carbon monoxide, H2 and CO) which is used to produce hydrogen (for refinery upgrading), methanol, as well as several other important materials. The HiPHES reformer development is an extension of Stone and Webster's efforts to develop a metal-tubed convective reformer integrated with a gas turbine cycle.

  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. Luminescence and scintillation properties of YAG:Ce single crystal and optical ceramics

    CERN Document Server

    Mihóková, E; Mareš, J A; Beitlerová, A; Vedda, A; Nejezchleb, K; Blažek, K; D’Ambrosio, C

    2007-01-01

    We use various techniques to study optical and scintillation properties of Ce-doped yttrium aluminum garnet, Y3Al5O12 (YAG:Ce), in the form of a high-quality industrial single crystal. This was compared to optical ceramics prepared from YAG:Ce nanopowders. We present experimental data in the areas of optical absorption, radioluminescence, scintillation decay, photoelectron yield, thermally stimulated luminescence and radiation-induced absorption. The results point to an interesting feature—the absence of antisite (YAl, i.e. Y at the Al site) defects in optical ceramics. The scintillation decay of the ceramics is faster than that of the single crystal, but its photoelectron yield (measured with 1 μs integration time) is about 30–40% lower. Apart from the photoelectron yield value the YAG:Ce optical ceramic is fully comparable to a high quality industrial YAG:Ce single crystal and can become a competitive scintillator material.

  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. 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.

  2. 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

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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

  8. 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

  9. [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.

  10. 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)

  11. 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.

  12. 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

  13. 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.

  14. 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).

  15. 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.

  16. Advanced CerMet ceramic composites for medical applications.

    Science.gov (United States)

    Dittmer, Robert; Schaefer, Christian M; Fischer, Jean-Francois; Hausch, Ulrich; Troetzschel, Jens; Specht, Heiko

    2017-11-01

    Implantable active devices such as pacemakers are facing rigorous requirements. Because they reside within the body for years, materials applied in this surrounding must exhibit biocompatibility and extraordinary reliability. They also have to provide a number of functional properties. In this work we present a method that enables the realization of a highly complex profile of properties by means of a dual composite approach. Using multilayer technology, an electrical conductor is embedded into a ceramic matrix, thus, creating conductive paths that are insulated from each other. In addition to this macroscopically hybrid architecture, this approach features a second composite aspect: the conductor is not composed of a single metallic phase, but is a ceramic-metal mixture. Owing to its interpenetrating microstructure, this CerMet allows for a strong and hermetic integration of the conductor into the ceramic matrix otherwise impossible due to mismatch in thermal expansion. In fact, the CerMet ceramic composite exhibits a higher strength than the pure ceramic as revealed by a three-point bending test study. At the same time, the CerMet offers high and virtually metal-like conductor properties, enabling a down-scaling of the conductive paths to 150µm diameter and smaller. Furthermore, the described composite is biocompatible, non-magnetic, and chemically inert, which is vital for the application in active, implantable, medical devices. Beside the general fabrication route, we present the microstructural, functional, and mechanical properties of this newly developed class of dual composites. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. 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.

  18. 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

  19. Relative translucency of six all-ceramic systems. Part II: core and veneer materials.

    Science.gov (United States)

    Heffernan, Michael J; Aquilino, Steven A; Diaz-Arnold, Ana M; Haselton, Debra R; Stanford, Clark M; Vargas, Marcos A

    2002-07-01

    STATEMENT OF PROBLEM All-ceramic core materials with various strengthening compositions have a range of translucencies. It is unknown whether translucency differs when all-ceramic materials are fabricated similarly to the clinical restoration with a veneered core material. This study compared the translucency of 6 all-ceramic materials veneered and glazed at clinically appropriate thicknesses. Core specimens (n = 5 per group) of Empress dentin, Empress 2 dentin, In-Ceram Alumina, In-Ceram Spinell, In-Ceram Zirconia, and Procera AllCeram were fabricated as described in Part I of this study and veneered with their corresponding dentin porcelain to a final thickness of 1.47 +/- 0.01 mm. These specimens were compared with veneered Vitadur Alpha opaque dentin (as a standard), a clear glass disc (positive control), and a high-noble metal-ceramic alloy (Porc. 52 SF) veneered with Vitadur Omega dentin (negative control). Specimen reflectance was measured with an integrating sphere attached to a spectrophotometer across the visible spectrum (380 to 700 nm); 0-degree illumination and diffuse viewing geometry were used. Measurements were repeated after a glazing cycle. Contrast ratios were calculated from the luminous reflectance (Y) of the specimens with a black (Yb) and a white backing (Yw) to give Yb/Yw with CIE illuminant D65 and a 2-degree observer function (0.0 = transparent, 1.0 = opaque). One-way analysis of variance and Tukey's multiple-comparison test were used to analyze the data (P<.05). Significant differences in contrast ratios were found among the ceramic systems tested when they were veneered (P<.0001) and after the glazing cycle (P<.0001). Significant changes in contrast ratios (P<.0001) also were identified when the veneered specimens were glazed. Within the limitations of this study, a range of translucency was identified in the veneered all-ceramic systems tested. Such variability may affect their ability to match natural teeth. The glazing cycle resulted

  20. Continuous flow synthesis of nanoparticles using ceramic microfluidic devices

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-de Pedro, S; Puyol, M; Alonso-Chamarro, J, E-mail: julian.alonso@uab.es [Grup de Sensors i Biosensors, Departament de Quimica, Facultat de Ciencies, Edifici Cn, Universitat Autonoma de Barcelona, Bellaterra 08193 (Spain)

    2010-10-15

    A microfluidic system based on the low-temperature co-fired ceramics technology (LTCC) is proposed to reproducibly carry out a simple one-phase synthesis and functionalization of monodispersed gold nanoparticles. It takes advantage of the LTCC technology, offering a fast prototyping without the need to use sophisticated facilities, reducing significantly the cost and production time of microfluidic systems. Some other interesting advantages of the ceramic materials compared to glass, silicon or polymers are their versatility and chemical resistivity. The technology enables the construction of multilayered systems, which can integrate other mechanical, electronic and fluidic components in a single substrate. This approach allows rapid, easy, low cost and automated synthesis of the gold colloidal, thus it becomes a useful approach in the progression from laboratory scale to pilot-line scale processes, which is currently demanded.

  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. 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.

  3. 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.

  4. 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...

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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)

  14. 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

  15. 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

  16. 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.

  17. 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

  18. 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...

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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

  7. 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.

  8. 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)

  9. 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.

  10. 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

  11. 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...

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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...

  17. 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.

  18. Synthesis and ceramic processing of alumina and zirconia based composites infiltrated with glass phase for dental applications

    International Nuclear Information System (INIS)

    Duarte, Daniel Gomes

    2009-01-01

    microscopy. Vickers impression tests and cytotoxicity essays were performed after glass phase incorporation. Considering the structural integrity of samples, homogeneity of microstructures, high fracture toughness values (3.6 - 4.9 MPa.m 1/ 2) and no cytotoxicity effects, it was verified that alumina based ceramics, prepared from coprecipitated powders, are adequate for production of dental frameworks infiltrated by vitreous phase. (author)

  19. Ultralight and fire-resistant ceramic nanofibrous aerogels with temperature-invariant superelasticity.

    Science.gov (United States)

    Si, Yang; Wang, Xueqin; Dou, Lvye; Yu, Jianyong; Ding, Bin

    2018-04-01

    Ultralight aerogels that are both highly resilient and compressible have been fabricated from various materials including polymer, carbon, and metal. However, it has remained a great challenge to realize high elasticity in aerogels solely based on ceramic components. We report a scalable strategy to create superelastic lamellar-structured ceramic nanofibrous aerogels (CNFAs) by combining SiO 2 nanofibers with aluminoborosilicate matrices. This approach causes the random-deposited SiO 2 nanofibers to assemble into elastic ceramic aerogels with tunable densities and desired shapes on a large scale. The resulting CNFAs exhibit the integrated properties of flyweight densities of >0.15 mg cm -3 , rapid recovery from 80% strain, zero Poisson's ratio, and temperature-invariant superelasticity to 1100°C. The integral ceramic nature also provided the CNFAs with robust fire resistance and thermal insulation performance. The successful synthesis of these fascinating materials may provide new insights into the development of ceramics in a lightweight, resilient, and structurally adaptive form.

  20. Compaction of Ceramic Microspheres, Spherical Molybdenum Powder and Other Materials to 3 GPa

    International Nuclear Information System (INIS)

    Carlson, S R; Bonner, B P; Ryerson, F J; Hart, M M

    2006-01-01

    Pressure-volume relationships were measured at room temperature for eight granular materials and one specimen of epoxy foam. The granular materials included hollow ceramic microspheres, spherical molybdenum powder, Ottawa sand, aluminum, copper, titanium and silicon carbide powders and glassy carbon spheres. Measurements were made to 0.9 GPa in a liquid medium press for all of the granular materials and to 3 GPa in a solid medium press for the ceramic microspheres and molybdenum powder. A single specimen of epoxy foam was compressed to 30 MPa in the liquid medium press. Bulk moduli were calculated as a function of pressure for the ceramic microspheres, the molybdenum powder and three other granular materials. The energy expended in compacting the granular materials was determined by numerically integrating pressure-volume curves. More energy was expended per unit volume in compacting the molybdenum powder to 1 GPa than for the other materials, but compaction of the ceramic microspheres required more energy per gram due to their very low initial density. The merge pressure, the pressure at which all porosity is removed, was estimated for each material by plotting porosity against pressure on a semi-log plot. The pressure-volume curves were then extrapolated to the predicted merge pressures and numerically integrated to estimate the energy required to reach full density for each material. The results suggest that the glassy carbon spheres and the ceramic microspheres would require more energy than the other materials to attain full density

  1. New approach to design of ceramic/polymer material compounds

    International Nuclear Information System (INIS)

    Todt, A; Nestler, D; Trautmann, M; Wagner, G

    2016-01-01

    The damage tolerance of carbon fibre-reinforced ceramic-matrix composite materials depends on their porosity and can be rather significant. Complex structures are difficult to produce. The integration of simple geometric structures of ceramic-matrix composite materials in complex polymer-based hybrid structures is a possible approach of realising those structures. These hybrid material compounds, produced in a cost-efficient way, combine the different advantages of the individual components in one hybrid material compound. In addition the individual parts can be designed to fit a specific application and the resulting forces. All these different advantages result in a significant reduction of not only the production costs and the production time, but also opens up new areas of application, such as the large-scale production of wear-resistant and chemically inert, energy dampening components for reactors or in areas of medicine. The low wettability of the ceramic component however is a disadvantage of this approach. During the course of this contribution, different C/C composite materials with a specific porosity were produced, while adjusting the resin/hardening agent-ratio, as well as the processing parameters. After the production, different penetration tests were conducted with a polymer component. The final part of the article is comprised of the microstructural analysis and the explanation of the mechanical relationships. (paper)

  2. Melter viewing system for liquid-fed ceramic melters

    International Nuclear Information System (INIS)

    Westsik, J.H. Jr.; Brenden, B.B.

    1988-01-01

    Melter viewing systems are an integral component of the monitoring and control systems for liquid-fed ceramic melters. The Pacific Northwest Laboratory (PNL) has designed cameras for use with glass melters at PNL, the Hanford Waste Vitrification Plant (HWVP), and West Valley Demonstration Project (WVDP). This report is a compilation of these designs. Operating experiences with one camera designed for the PNL melter are discussed. A camera has been fabricated and tested on the High-Bay Ceramic Melter (HBCM) and the Pilot-Scale Ceramic Melter (PSCM) at PNL. The camera proved to be an effective tool for monitoring the cold cap formed as the feed pool developed on the molten glass surface and for observing the physical condition of the melter. Originally, the camera was built to operate using the visible light spectrum in the melter. It was later modified to operate using the infrared (ir) spectrum. In either configuration, the picture quality decreases as the size of the cold cap increases. Large cold caps cover the molten glass, reducing the amount of visible light and reducing the plenum temperatures below 600 0 C. This temperature corresponds to the lowest level of blackbody radiation to which the video tube is sensitive. The camera has been tested in melter environments for about 1900 h. The camera has withstood mechanical shocks and vibrations. The cooling system in the camera has proved effective in maintaining the optical and electronic components within acceptable temperature ranges. 10 refs., 15 figs

  3. Elaboration of optical glass-ceramic for frequency doubling

    International Nuclear Information System (INIS)

    Vigouroux, H.

    2012-01-01

    The High power laser development required the need of materials with nonlinear properties. Glass materials can be considered as ideal materials as they can be transparent and elaborated in very large dimension. Precipitation of non-centro symmetric crystalline particles in bulk glass leads to a material with bulk nonlinear properties. This glass-ceramic should be then easily integrated in such laser facilities. In this thesis, the results concerning the precipitation of the phase LiNbO 3 in the glassy-matrix 35 Li 2 O - 25 Nb 2 O 5 - 40 SiO 2 are detailed. The crystallization mechanism of this phase is studied through thermal analysis, optical and electronic microscopy as well as in-situ analyses. These studies reveal glass-ceramics are obtained through a precipitation of the lithium niobate crystalline phase in spherulite shape. The nonlinear optical properties are investigated on this materials and an original, isotropic Second Harmonic Generation Signal (SHG) is registered in the bulk glass-ceramic. A complete study using a multi-scale approach allows the correlation between the spherulite structure and the nonlinear optical properties. A mechanism at the origin of the SHG signal is proposed. This leads to a new approach for transparent inorganic materials development for isotropic SHG conversion. (author) [fr

  4. 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.

  5. 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

  6. 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.

  7. Survival of ceramic veneers made of different materials after a minimum follow-up period of five years: a systematic review and meta-analysis.

    Science.gov (United States)

    Petridis, Haralampos P; Zekeridou, Alkisti; Malliari, Maria; Tortopidis, Dimitrios; Koidis, Petros

    2012-01-01

    The purpose of this systematic review was to compare the survival and complication rates of ceramic veneers produced with different techniques and materials after a minimum follow-up time of 5 years. A literature search was conducted, using electronic databases, relevant references, citations and journal researching, for clinical studies reporting on the survival of ceramic veneers fabricated with different techniques and materials with a mean followup time of at least 5 years. The search period spanned from January 1980 up to October 2010. Event rates were calculated for the following complications associated with ceramic veneers: fracture, debonding, marginal discoloration, marginal integrity, and caries. Summary estimates, and 5-year event rates were reported. Comparison between subgroups of different materials, as well as statistical significance, was calculated using a mixed effects model. Nine studies were selected for final analysis over an initial yield of 409 titles. No study directly compared the incidence of complications between ceramic veneers fabricated from different materials. Four of the included studies reported on the survival of ceramic veneers made out of feldspathic ceramics; four studies were on glass-ceramic veneers and one study included veneers fabricated from both materials. The mean observation time ranged between 5 and 10 years. Overall, the 5-year complication rates were low, with the exception of studies reporting on extended ceramic veneers. The most frequent complication reported was marginal discoloration (9% at 5 years), followed by marginal integrity (3.9-7.7% at 5 years). There was no statistically significant difference in the event rates between the subgroups of different materials (feldspathic vs. glass-ceramic). The results of this systematic review showed that ceramic veneers fabricated from feldspathic or glass-ceramics have an adequate clinical survival for at least 5 years of clinical service, with very low complication

  8. Separators - Technology review: Ceramic based separators for secondary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Nestler, Tina; Schmid, Robert; Münchgesang, Wolfram; Bazhenov, Vasilii; Meyer, Dirk C. [Technische Universität Bergakademie Freiberg, Institut für Experimentelle Physik, Leipziger Str. 23, 09596 Freiberg (Germany); Schilm, Jochen [Fraunhofer-Institut für Keramische Technologien und Systeme IKTS, Winterbergstraße 28, 01277 Dresden (Germany); Leisegang, Tilmann [Fraunhofer-Technologiezentrum Halbleitermaterialien THM, Am St.-Niclas-Schacht 13, 09599 Freiberg (Germany)

    2014-06-16

    Besides a continuous increase of the worldwide use of electricity, the electric energy storage technology market is a growing sector. At the latest since the German energy transition ('Energiewende') was announced, technological solutions for the storage of renewable energy have been intensively studied. Storage technologies in various forms are commercially available. A widespread technology is the electrochemical cell. Here the cost per kWh, e. g. determined by energy density, production process and cycle life, is of main interest. Commonly, an electrochemical cell consists of an anode and a cathode that are separated by an ion permeable or ion conductive membrane - the separator - as one of the main components. Many applications use polymeric separators whose pores are filled with liquid electrolyte, providing high power densities. However, problems arise from different failure mechanisms during cell operation, which can affect the integrity and functionality of these separators. In the case of excessive heating or mechanical damage, the polymeric separators become an incalculable security risk. Furthermore, the growth of metallic dendrites between the electrodes leads to unwanted short circuits. In order to minimize these risks, temperature stable and non-flammable ceramic particles can be added, forming so-called composite separators. Full ceramic separators, in turn, are currently commercially used only for high-temperature operation systems, due to their comparably low ion conductivity at room temperature. However, as security and lifetime demands increase, these materials turn into focus also for future room temperature applications. Hence, growing research effort is being spent on the improvement of the ion conductivity of these ceramic solid electrolyte materials, acting as separator and electrolyte at the same time. Starting with a short overview of available separator technologies and the separator market, this review focuses on ceramic

  9. Separators - Technology review: Ceramic based separators for secondary batteries

    Science.gov (United States)

    Nestler, Tina; Schmid, Robert; Münchgesang, Wolfram; Bazhenov, Vasilii; Schilm, Jochen; Leisegang, Tilmann; Meyer, Dirk C.

    2014-06-01

    Besides a continuous increase of the worldwide use of electricity, the electric energy storage technology market is a growing sector. At the latest since the German energy transition ("Energiewende") was announced, technological solutions for the storage of renewable energy have been intensively studied. Storage technologies in various forms are commercially available. A widespread technology is the electrochemical cell. Here the cost per kWh, e. g. determined by energy density, production process and cycle life, is of main interest. Commonly, an electrochemical cell consists of an anode and a cathode that are separated by an ion permeable or ion conductive membrane - the separator - as one of the main components. Many applications use polymeric separators whose pores are filled with liquid electrolyte, providing high power densities. However, problems arise from different failure mechanisms during cell operation, which can affect the integrity and functionality of these separators. In the case of excessive heating or mechanical damage, the polymeric separators become an incalculable security risk. Furthermore, the growth of metallic dendrites between the electrodes leads to unwanted short circuits. In order to minimize these risks, temperature stable and non-flammable ceramic particles can be added, forming so-called composite separators. Full ceramic separators, in turn, are currently commercially used only for high-temperature operation systems, due to their comparably low ion conductivity at room temperature. However, as security and lifetime demands increase, these materials turn into focus also for future room temperature applications. Hence, growing research effort is being spent on the improvement of the ion conductivity of these ceramic solid electrolyte materials, acting as separator and electrolyte at the same time. Starting with a short overview of available separator technologies and the separator market, this review focuses on ceramic-based separators

  10. 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.

  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. Ceramic membranes with mixed conductivity and their application

    International Nuclear Information System (INIS)

    Kozhevnikov, V L; Leonidov, I A; Patrakeev, M V

    2013-01-01

    Data on the catalytic reactors with ceramic membranes possessing mixed oxygen ion and electronic conductivity that make it possible to integrate the processes of oxygen separation and oxidation are analyzed and generalized. The development of this approach is of interest for the design of energy efficient and environmentally friendly processes for processing natural gas and other raw materials. The general issues concerning the primary processing of light alkanes in reactors with oxygen separating membranes are expounded and general demands to the membrane materials are discussed. Particular attention is paid to the process of oxidative conversion of methane to synthesis gas. The bibliography includes 110 references

  5. 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.

  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. Ceramic membranes for gas processing in coal gasification

    Energy Technology Data Exchange (ETDEWEB)

    Smart, S.; Lin, C.X.C.; Ding, L.; Thambimuthu, K.; da Costa, J.C.D. [University of Queensland, Brisbane, Qld. (Australia)

    2010-07-01

    Pre-combustion options via coal gasification, especially integrated gasification combined cycle (IGCC) processes, are attracting the attention of governments, industry and the research community as an attractive alternative to conventional power generation. It is possible to build an IGCC plant with CCS with conventional technologies however; these processes are energy intensive and likely to reduce power plant efficiencies. Novel ceramic membrane technologies, in particular molecular sieving silica (MSS) and pervoskite membranes, offer the opportunity to reduce efficiency losses by separating gases at high temperatures and pressures. MSS membranes can be made preferentially selective for H{sub 2}, enabling both enhanced production, via a water-gas shift membrane reactor, and recovery of H{sub 2} from the syngas stream at high temperatures. They also allow CO{sub 2} to be concentrated at high pressures, reducing the compression loads for transportation and enabling simple integration with CO{sub 2} storage or sequestration operations. Perovskite membranes provide a viable alternative to cryogenic distillation for air separation by delivering the tonnage of oxygen required for coal gasification at a reduced cost. In this review we examine ceramic membrane technologies for high temperature gas separation and discuss the operational, mechanical, design and process considerations necessary for their successful integration into IGCC with CCS 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. The use of luminescence techniques with ceramic materials for retrospective dosimetry

    International Nuclear Information System (INIS)

    Bailiff, I.K.

    1996-01-01

    Luminescence techniques are being used with ceramic materials to provide evaluations of integrated external gamma dose for dose reconstruction in populated areas contaminated by Chernobyl fallout. A range of suitable ceramics can be found associated with buildings: on the exterior surfaces (tiles), within walls (bricks) and within the interiors (porcelain fittings and tiles). Dose evaluations obtained using such samples provide information concerning the time-averaged incident gamma radiation field, average shielding factors and, with the aid of computational modelling techniques, dose estimates at external reference positions

  14. 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

  15. 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.

  16. 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

  17. 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.

  18. Interface mechanics and histomorphometric analysis of hydroxyapatite-coated and porous glass-ceramic implants in canine bone

    DEFF Research Database (Denmark)

    Nimb, L; Jensen, J S; Gotfredsen, K

    1995-01-01

    A canine study was performed to make a histological and biomechanical evaluation of the interface between bone and two different bioceramic implants. A newly developed glass-ceramic formed by P2O5, CaO, SiO2, and Al2O3, giving a crystal phase composed of CaP2O6-AlPO4-SiP2O7, was compared...... analysis. The ultimate shear strength for the HA-coated implants was significantly higher than in the glass-ceramic group. When these values were related to the histomorphometric measurements, the difference could be explained by the tissue-to-implant contact. The glass-ceramic showed direct contact only...... with nonmineralized, osteoid bone. The HA-coated implants, however, were integrated into the bone. The study indicated that porous glass-ceramic containing AlPO4 causes local osteomalacia and might not be suitable for clinical purposes....

  19. Process description and plant design for preparing ceramic high-level waste forms

    International Nuclear Information System (INIS)

    Grantham, L.F.; McKisson, R.L.; Guon, J.; Flintoff, J.F.; McKenzie, D.E.

    1983-01-01

    The ceramics process flow diagram has been simplified and upgraded to utilize only two major processing steps - fluid-bed calcination and hot isostatic press consolidating. Full-scale fluid-bed calcination has been used at INEL to calcine high-level waste for 18 y; and a second-generation calciner, a fully remotely operated and maintained calciner that meets ALARA guidelines, started calcining high-level waste in 1982. Full-scale hot isostatic consolidation has been used by DOE and commercial enterprises to consolidate radioactive components and to encapsulate spent fuel elements for several years. With further development aimed at process integration and parametric optimization, the operating knowledge of full-scale demonstration of the key process steps should be rapidly adaptable to scale-up of the ceramic process to full plant size. Process flowsheets used to prepare ceramic and glass waste forms from defense and commercial high-level liquid waste are described. Preliminary layouts of process flow diagrams in a high-level processing canyon were prepared and used to estimate the preliminary cost of the plant to fabricate both waste forms. The estimated costs for using both options were compared for total waste management costs of SRP high-level liquid waste. Using our design, for both the ceramic and glass plant, capital and operating costs are essentially the same for both defense and commercial wastes, but total waste management costs are calculated to be significantly less for defense wastes using the ceramic option. It is concluded from this and other studies that the ceramic form may offer important advantages over glass in leach resistance, waste loading, density, and process flexibility. Preliminary economic calculations indicate that ceramics must be considered a leading candidate for the form to immobilize high-level wastes

  20. 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

  1. 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.

  2. 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

  3. 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)

  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. Laser-assisted turning of components made of silicon-nitride ceramics

    International Nuclear Information System (INIS)

    Klocke, F.; Bausch, S.

    2001-01-01

    The manufacture of high-precision parts made of silicon-nitride ceramic, such as roller bearing rings or valves, currently involves finishing in the form of time and cost intensive grinding operations. This has resulted in demands for the development of more efficient machining techniques and for the subsequent provision of these within a manufacturing environment. A prototype of a precision lathe with an integrated high power diode laser for laser-assisted turning has been developed at the Fraunhofer IPT in close co-operation with industrial partners. When the workpiece is heated continuously by the laser, the resultant localized material softening enables the ceramic to be machined using a defined cutting edge. The application of this technique allows complex silicon nitride ceramic parts with surface qualities of up to R a = 0.3 μm to be produced considerably more flexibly than before, with no requirement for cooling lubricant. (author)

  6. PIXE analysis of Moroccan architectural glazed ceramics of 14th-18th centuries

    International Nuclear Information System (INIS)

    Zucchiatti, A.; Azzou, A.; El Amraoui, M.; Haddad, M.; Bejjit, L.; Ait Lyazidi, S.

    2009-01-01

    The PIXE analysis of glazes and ceramic bodies of a set of architectural glazed ceramics (mostly the zellige mosaics), sampled from seven Moroccan monuments from the 14th to the 18th century AD, has been performed. We have identified high lead glazes, opacified with tin-oxide, laid over a calciferous body to produce hard tiles easy to chisel as required by the zellige technique. The analysis has revealed significant differences between the monuments examined: in particular in the formulation of the base glass and in the use of stains to produce coloured glazes. We observed the peculiarity of materials used in Marrakech and we could distinguish, both in terms of glazes and ceramic bodies, the two almost contemporary Madersas dedicated to the sultan Bou Inan, one in Meknes the other in Fez. The PIXE measurements integrate a broad range of spectrometric investigations performed in the past few years. (author)

  7. 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.

  8. 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

  9. 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

  10. 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)

  11. 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)

  12. 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.

  13. Grinding model and material removal mechanism of medical nanometer zirconia ceramics.

    Science.gov (United States)

    Zhang, Dongkun; Li, Changhe; Jia, Dongzhou; Wang, Sheng; Li, Runze; Qi, Xiaoxiao

    2014-01-01

    Many patents have been devoted to developing medical nanometer zirconia ceramic grinding techniques that can significantly improve both workpiece surface integrity and grinding quality. Among these patents is a process for preparing ceramic dental implants with a surface for improving osseo-integration by sand abrasive finishing under a jet pressure of 1.5 bar to 8.0 bar and with a grain size of 30 µm to 250 µm. Compared with other materials, nano-zirconia ceramics exhibit unmatched biomedical performance and excellent mechanical properties as medical bone tissue and dentures. The removal mechanism of nano-zirconia materials includes brittle fracture and plastic removal. Brittle fracture involves crack formation, extension, peeling, and chipping to completely remove debris. Plastic removal is similar to chip formation in metal grinding, including rubbing, ploughing, and the formation of grinding debris. The materials are removed in shearing and chipping. During brittle fracture, the grinding-led transverse and radial extension of cracks further generate local peeling of blocks of the material. In material peeling and removal, the mechanical strength and surface quality of the workpiece are also greatly reduced because of crack extension. When grinding occurs in the plastic region, plastic removal is performed, and surface grinding does not generate grinding fissures and surface fracture, producing clinically satisfactory grinding quality. With certain grinding conditions, medical nanometer zirconia ceramics can be removed through plastic flow in ductile regime. In this study, we analyzed the critical conditions for the transfer of brittle and plastic removal in nano-zirconia ceramic grinding as well as the high-quality surface grinding of medical nanometer zirconia ceramics by ELID grinding.

  14. 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.

  15. 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)

  16. 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

  17. 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)

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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.

  5. 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

  6. 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

  7. Defects level evaluation of LiTiZn ferrite ceramics using temperature dependence of initial permeability

    Science.gov (United States)

    Malyshev, A. V.; Petrova, A. B.; Sokolovskiy, A. N.; Surzhikov, A. P.

    2018-06-01

    The method for evaluating the integral defects level and chemical homogeneity of ferrite ceramics based on temperature dependence analysis of initial permeability is suggested. A phenomenological expression for the description of such dependence was suggested and an interpretation of its main parameters was given. It was shown, that the main criterion of the integral defects level of ferrite ceramics is relation of two parameters correlating with elastic stress value in a material. An indicator of structural perfection can be a maximum value of initial permeability close to Curie point as well. The temperature dependences of initial permeability have analyzed for samples sintered in laboratory conditions and for the ferrite industrial product. The proposed method allows controlling integral defects level of the soft ferrite products and has high sensitivity compare to typical X-ray methods.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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.

  18. 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

  19. 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...

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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...

  5. 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

  6. 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.)

  7. 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.

  8. 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).

  9. 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

  10. 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

  11. 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.

  12. 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.)

  13. 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)

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. A high temperature ceramic heat exchanger element for a solar thermal receiver

    Science.gov (United States)

    Strumpf, H. J.; Kotchick, D. M.; Coombs, M. G.

    1982-01-01

    The development of a high-temperature ceramic heat exchanger element to be integrated into a solar receiver producing heated air was studied. A number of conceptual designs were developed for heat exchanger elements of differing configuration. These were evaluated with respect to thermal performance, pressure drop, structural integrity, and fabricability. The final design selection identified a finned ceramic shell as the most favorable concept. The shell is surrounded by a larger metallic shell. The flanges of the two shells are sealed to provide a leak-tight pressure vessel. The ceramic shell is to be fabricated by a innovative combination of slip casting the receiver walls and precision casting the heat transfer finned plates. The fins are bonded to the shell during firing. The unit is sized to produce 2150 F air at 2.7 atm pressure, with a pressure drop of about 2 percent of the inlet pressure. This size is compatible with a solar collector providing a receiver input of 85 kw(th). Fabrication of a one-half scale demonstrator ceramic receiver was completed.