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Sample records for nzp ceramics final

  1. Prototype development and testing of ultrafine grain NZP ceramics. Final report, July 28, 1995--April 27, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Brown, J.J.

    1997-08-04

    The goal of this project was to demonstrate that a new low-expanding ceramic (Ca{sub 0.6},Mg{sub 0.4})Zr{sub 4}(PO{sub 4}){sub 6}, hereafter referred to as CMZP, could be used as an exhaust manifold liner in off-road diesel engines and provide improved engine efficiency (by permitting higher engine operating temperature). This study has successfully demonstrated this improvement and further engine testing (and possible manufacturing) is presently underway at Caterpillar Inc. Laboratories. Basically this program involved two subcontracts: one to Virginia Tech to develop sintering procedures for CMZP, and one to Caterpillar, Inc. to develop slip casting procedures for CMZP. Nearly 100kg of CMZP were prepared by MATVA, Inc. and Virginia Tech for use by Caterpillar. Virginia Tech developed detailed sintering procedures for CMZP and Caterpillar developed slip casting procedures and manufactured several exhaust manifold elbows. These elbows have been cast into prototype cylinder heads and have been shown to be acceptable replacements for metal manifolds. (Caterpillar advises that a new component may require up to 6 years of testing and qualification before acceptance as standard diesel engine part).

  2. Development of NZP ceramic based {open_quotes}cast-in-place{close_quotes} diesel engine port liners

    Energy Technology Data Exchange (ETDEWEB)

    Nagaswaran, R.; Limaye, S.Y.

    1996-02-01

    BSX (Ba{sub 1+x}Zr{sub 4}P{sub 6-2x}Si{sub 2x}O{sub 24}) and CSX (Ca{sub l-x}Sr{sub x}Zr{sub 4}P{sub 6}O{sub 24}) type NZP ceramics were fabricated and characterized for: (i) thermal properties viz., thermal conductivity, thermal expansion, thermal stability and thermal shock resistance; (ii) mechanical properties viz., flexure strength and elastic modulus; and (iii) microstructures. Results of these tests and analysis indicated that the BS-25 (x=0.25 in BSX) and CS-50 (x=0.50 in CSX) ceramics had the most desirable properties for casting metal with ceramic in place. Finite element analysis (FEA) of metal casting (with ceramic in place) was conducted to analyze thermomechanical stresses generated and determine material property requirements. Actual metal casting trials were also conducted to verify the results of finite element analysis. In initial trials, the ceramic cracked because of the large thermal expansion mismatch (hoop) stresses (predicted by FEA also). A process for introduction of a compliant layer between the metal and ceramic to alleviate such destructive stresses was developed. The compliant layer was successful in preventing cracking of either the ceramic or the metal. In addition to these achievements, pressure slip casting and gel-casting processes for fabrication of NZP components; and acoustic emission and ultrasonics-based NDE techniques for detection of microcracks and internal flaws, respectively, were successfully developed.

  3. The immobilisation of nuclear waste materials containing different alkali elements into single-phase NZP based ceramics

    International Nuclear Information System (INIS)

    Pet'kov, V.I.; Orlova, A.I.; Trubach, I.G.; Demarin, T.; Kurazhkovskaya, V.S.

    2002-01-01

    The NZP matrix, which is based on NaZr 2 (PO 4 ) 3 , is a viable candidate for nuclear waste immobilisation. We examined the possibilities of incorporating of alkali elements into the NZP host structure, investigated the conditions of the crystalline solution formation, and determined the regions of the NZP structure compositional stability for a series of complex orthophosphates of titanium or zirconium and alkali elements A m-x A' x M 2-(m-1)/4 (PO 4 ) 3 with m = 1, 3, or 5 and 0 ≤ x ≤ m, where A and A' are mutually different alkali elements and M is Ti or Zr. The phosphates containing Li-Na, Li-K, Li-Rb, Li-Cs, Na-K, Na-Rb, Na-Cs, K-Rb, K-Cs and Rb-Cs pairs were prepared and studied by X-ray powder analysis, IR spectroscopy, simultaneous DTA-TG measurements and electron microprobe analyses. In the systems studied, wide ranges of crystalline phosphate solutions with tailored alkali metal substitutions were formed owing to the large number of sites available for substitution and high degree of flexibility in the NZP structure. It was found that introduction of the less expensive and lighter Ti in the host phase in place of the commonly used Zr permits cheaper ceramics, having in some cases larger alkali element contents, to be obtained. The phases containing alkali metals can be formed, for instance, during phosphate solidification of molten alkali chlorides with radioactive nuclides from the pyroelectrochemical technologies of nuclear fuel recycling

  4. Sodium zirconium phosphate (NZP) as a host structure for nuclear waste immobilization: A review

    International Nuclear Information System (INIS)

    Scheetz, B.E.; Agrawal, D.K.; Breval, E.; Roy, R.

    1994-01-01

    Sodium zirconium phosphate [NZP] structural family, of which NaZr 2 P 3 O 12 is the parent composition, has been reviewed as a host ceramic waste form for nuclear waste immobilization. NZP compounds are characterized for their ionic conductivity, low thermal expansion and structural flexibility to accommodate a large number of multivalent ions. This latter property of the [NZP] structure allows the incorporation of almost all 42 nuclides present in a typical commercial nuclear waste. The leach studies of simulated waste forms based on NZP have shown reasonable resistance for the release of its constituents. The calculation of dissolution rates of NZP structure has demonstrated that it would take 20,000 times longer to dissolved NZP than quartz

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

  6. Site preferences of actinide cations in [NZP] compounds

    Science.gov (United States)

    Hawkins, H. T.; Spearing, D. R.; Smith, D. M.; Hampel, F. G.; Veirs, D. K.; Scheetz, B. E.

    2000-07-01

    Compounds adopting the sodium dizirconium tris(phosphate) (NaZr2(PO4)3) structure type belong to the [NZP] structural family of compounds. [NZP] compounds possess desirable properties that would permit their application as hosts for the actinides. These properties include compositional flexibility (i.e., three structural sites that can accommodate a variety of different cations), high thermal stability, negligible thermal expansion, and resistance to radiation damage. Experimental data indicate that [NZP] compounds resist dissolution and release of constituents over a wide range of experimental conditions. Moreover, [NZP] compounds may be synthesized by both conventional and novel methods and may be heat treated or sintered at modest temperatures (800 °C-1350 °C) in open or restricted systems.

  7. The dissociation of NZP (Ca{sub 0.5}Sr{sub 0.5}Zr{sub 4}P{sub 6}O{sub 24}) during plasma spraying[Sodium Zirconium Phosphate

    Energy Technology Data Exchange (ETDEWEB)

    Trice, R.W.; Brewer, L.N.; Faber, K.T.

    2000-04-01

    Sodium zirconium phosphate (NaZr{sub 2}P{sub 3}O{sub 12} or NZP) was first systematically evaluated in the early 1980s by Roy and co-workers, who demonstrated its extremely low coefficient of thermal expansion (CTE). It was later shown that other group IA and IIA atoms can be ionically substituted into the NZP crystal structure to adjust the CTE. As a result of their low and tailorable CTEs, NZP's have potential use as a protective coating for silicon-based ceramics and carbon-carbon composites. One technique for the application of ceramic coatings employs plasma-spraying. In this process, powders are injected into a plasma flame, melted, and propelled onto a substrate. The resulting coating microstructure is typically composed of thin lamellae (from each melted particle) stacked on top of one another during each pass of the torch. In the current research, NZP has been plasma-sprayed using the recently patented small particle plasma-spray process. The microstructure was then analyzed using transmission electron microscopy and x-ray diffraction to identify the phases in the complex coating that resulted.

  8. Solid ceramic based on mixed-frame titanium phosphate and calcium synthesized in solar furnace

    International Nuclear Information System (INIS)

    Salikhov, T. P.; Kan, V. V.; Urazaeva, Eh. M.; Savatyugina, T. V.; Arushanov, G. M.

    2012-01-01

    The authors synthesized of mixed orthophosphates Ca 0 . 5 Ti 2 (PO 4 ) 3 using concentrated solar radiation. We obtained a porous ceramic filter with the given type of NZP structure and high thermal and hydrolytic stability. (authors)

  9. 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

  10. Structure and short time degradation studies of sodium zirconium phosphate ceramics loaded with simulated fast breeder (FBR) waste

    Energy Technology Data Exchange (ETDEWEB)

    Ananthanarayanan, A., E-mail: arvinda@barc.gov.in [Process Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Ambashta, R.D., E-mail: aritu@barc.gov.in [Process Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sudarsan, V. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Ajithkumar, T. [Applied Catalysis Unit, National Chemical Laboratory, Pune 411008 (India); Sen, D.; Mazumder, S. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Wattal, P.K. [Process Development Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2017-04-15

    Sodium zirconium phosphate (NZP) ceramics have been prepared using conventional sintering and hot isostatic pressing (HIP) routes. The structure of NZP ceramics, prepared using the HIP route, has been compared with conventionally sintered NZP using a combination of X-ray diffraction (XRD) and ({sup 31}P and {sup 23}Na) nuclear magnetic resonance (NMR) spectroscopy techniques. It is observed that NZP with no waste loading is aggressive toward the steel HIP-can during hot isostatic compaction and significant fraction of cations from the steel enter the ceramic material. Waste loaded NZP samples (10 wt% simulated FBR waste) show significantly low can-interaction and primary NZP phase is evident in this material. Upon exposure of can-interacted and waste loaded NZP to boiling water and steam, {sup 31}P NMR does not detect any major modifications in the network structure. However, the {sup 23}Na NMR spectra indicate migration of Na{sup +} ions from the surface and possible re-crystallization. This is corroborated by Small-Angle Neutron Scattering (SANS) data and Scanning Electron Microscopy (SEM) measurements carried out on these samples.

  11. Ion beam irradiation effects in strontium zirconium phosphate with NZP-structure type

    International Nuclear Information System (INIS)

    Gregg, Daniel J.; Karatchevtseva, Inna; Thorogood, Gordon J.; Davis, Joel; Bell, Benjamin D.C.; Jackson, Matthew; Dayal, Pranesh; Ionescu, Mihail; Triani, Gerry; Short, Ken; Lumpkin, Gregory R.; Vance, Eric R.

    2014-01-01

    Ceramics with the sodium zirconium phosphate or NZP type structure have potential as nuclear waste form and inert matrix materials. For both applications the material will be subjected to self-radiation damage from α-decay of the incorporated actinides. In this study, ion-beam irradiation using Au- and He-ions has been used to simulate the consequences of α-decay and the effects of irradiation on the structural and macroscopic properties (density and hardness) have been investigated. Irradiation by Au-ions resulted in a significant volume contraction of ∼7%, a reduction in hardness of ∼30% and a loss in long-range order at fluences above 10 14 Au-ions/cm 2 . In contrast, little effect on the material properties was noted for samples irradiated with He-ions up to a fluence of 10 17 ions/cm 2 . Thermal annealing was investigated for the highest fluence Au-ion irradiated sample and significant decomposition was observed

  12. Insulating Structural Ceramics Program, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, Mark J.; Tandon, Raj; Ott, Eric; Hind, Abi Akar; Long, Mike; Jensen, Robert; Wheat, Leonard; Cusac, Dave; Lin, H. T.; Wereszczak, Andrew A.; Ferber, Mattison K.; Lee, Sun Kun; Yoon, Hyung K.; Moreti, James; Park, Paul; Rockwood, Jill; Boyer, Carrie; Ragle, Christie; Balmer-Millar, Marilou; Aardahl, Chris; Habeger, Craig; Rappe, Ken; Tran, Diana; Koshkarian, Kent; Readey, Michael

    2005-11-22

    New materials and corresponding manufacturing processes are likely candidates for diesel engine components as society and customers demand lower emission engines without sacrificing power and fuel efficiency. Strategies for improving thermal efficiency directly compete with methodologies for reducing emissions, and so the technical challenge becomes an optimization of controlling parameters to achieve both goals. Approaches being considered to increase overall thermal efficiency are to insulate certain diesel engine components in the combustion chamber, thereby increasing the brake mean effective pressure ratings (BMEP). Achieving higher BMEP rating by insulating the combustion chamber, in turn, requires advances in material technologies for engine components such as pistons, port liners, valves, and cylinder heads. A series of characterization tests were performed to establish the material properties of ceramic powder. Mechanical chacterizations were also obtained from the selected materials as a function of temperature utilizing ASTM standards: fast fracture strength, fatique resistance, corrosion resistance, thermal shock, and fracture toughness. All ceramic materials examined showed excellent wear properties and resistance to the corrosive diesel engine environments. The study concluded that the ceramics examined did not meet all of the cylinder head insert structural design requirements. Therefore we do not recommend at this time their use for this application. The potential for increased stresses and temperatures in the hot section of the diesel engine combined with the highly corrosive combustion products and residues has driven the need for expanded materials capability for hot section engine components. Corrosion and strength requirements necessitate the examination of more advanced high temperture alloys. Alloy developments and the understanding of processing, structure, and properties of supperalloy materials have been driven, in large part, by the gas

  13. Phosphate bonded ceramics as candidate final-waste-form materials

    International Nuclear Information System (INIS)

    Singh, D.; Wagh, A.S.; Cunnane, J.; Sutaria, M.; Kurokawa, S.; Mayberry, J.

    1994-04-01

    Room-temperature setting phosphate-bonded ceramics were studied as candidate materials for stabilization of DOE low-level problem mixed wastes which cannot be treated by other established stabilization techniques. Phosphates of Mg, Mg-Na, Al and Zr were studied to stabilize ash surrogate waste containing RCRA metals as nitrates and RCRA organics. We show that for a typical loading of 35 wt.% of the ash waste, the phosphate ceramics pass the TCLP test. The waste forms have high compression strength exceeding ASTM recommendations for final waste forms. Detailed X-ray diffraction studies and differential thermal analyses of the waste forms show evidence of chemical reaction of the waste with phosphoric acid and the host matrix. The SEM studies show evidence of physical bonding. The excellent performance in the leaching tests is attributed to a chemical solidification and physical as well as chemical bonding of ash wastes in these phosphate ceramics

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

    International Nuclear Information System (INIS)

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

    1998-01-01

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

  15. Americium and plutonium in phosphates of trigonal structure (NZP type) Am1/3[Zr2(PO4)3] and Pu1/4[Zr2(PO4)3

    International Nuclear Information System (INIS)

    Bykov, D.M.; Orlova, A.I.; Tomilin, S.V.; Lizin, A.A.; Lukinykh, A.N.

    2006-01-01

    Am 1/3 [Zr 2 (PO 4 ) 3 ] and Pu 1/4 [Zr 2 (PO 4 ) 3 ] phosphates are synthesized and are investigated by X-ray diffraction method. Compounds have triclinic lattices and lattice parameters are determined. Possibility of actinide inclusion into hollows of framework of NZP type is shown for the first time. It is proposed that inclusion of Pu and Am highly-charged cations into framework hollows decreases crystal structure symmetry up to primitive trigonal one. Rate of Pu leaching from ceramics on Pu 1/4 [Zr 2 (PO 4 ) 3 ] basis are measured [ru

  16. [Effect of ceramic thickness and resin cement shades on final color of heat-pressed ceramic veneers].

    Science.gov (United States)

    Ren, D F; Zhan, K R; Chen, X D; Xing, W Z

    2017-02-09

    Objective: To analyze the effect of ceramic materials thickness and resin cement shades on the final color of ceramic veneers in the discolored teeth, and to investigate the color agreement of try-in pastes to the corresponding resin cements. Methods: Sixty artificial maxillary central incisor teeth (C2 shade) were used to simulate the natural discolored teeth and prepared according to veneer tooth preparation protocol. Veneers of different thickness in the body region (0.50 and 0.75 mm) were fabricated using ceramic materials (LT A2 shade, IPS e.max Press). The ceramic veneer specimens were bonded to the artificial teeth using the 6 shades of resin cements (Variolink Veneer: shades of LV-3, LV-2, HV+3; RelyX™ Veneer: shades of TR, A3, WO) ( n= 5). A clinical spectrophotometer was used to measure the color parameters of ceramic veneers at the cervical, body and incisal regions. Color changes of veneers before and after cementation were calculated and registered as ΔE1, and the changes between try-in paste and the corresponding resin cements were registered as ΔE2. Results: Three-way ANOVA indicated that ΔE1 and ΔE2 values were significantly affected by the ceramic thickness, resin cement shades and measuring regions ( Pceramic veneers were cemented with resin cements in shades of HV+3 and WO. The ΔE2 values of six shades ranged from 0.60-2.56. The shades of HV+3, WO and A3 resin cements were more than 1.60. Conclusions: Different thickness of ceramic materials, resin cement shades and measuring regions could affect the final color of ceramic veneers. The color differences of some resin cements and corresponding try-in pastes might be observed in clinical practice.

  17. Engine testing of ceramic cam-roller followers. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kalish, Y. [Detroit Diesel Corp., MI (United States)

    1992-04-01

    For several years, DDC has been developing monolithic ceramic heat engine components. One of the components, developed for an application in our state-of-the-art on-highway, heavy-duty diesel engine, the Series 60, is a silicon nitride cam-roller follower. Prior to starting this program, each valve train component in the Series 60 was considered for conversion to a ceramic material. Many advantages and disadvantages (benefits and risks) were considered. From this effort, one component was selected, the cam-roller follower. Using a system design approach, a ceramic cam-roller follower offered functional improvement at a reasonable cost. The purpose of the project was to inspect and test 100 domestically produced silicon nitride cam-roller followers built to the requirements of the DDC series 60 engine.

  18. Ceramic stationary gas turbine development. Final report, Phase 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-09-01

    This report summarizes work performed by Solar Turbines Inc. and its subcontractors during the period September 25, 1992 through April 30, 1993. The objective of the work is to improve the performance of stationary gas turbines in cogeneration through implementation of selected ceramic components.

  19. Application of the final flotation waste for obtaining the glass-ceramic materials

    Directory of Open Access Journals (Sweden)

    Cocić Mira

    2017-01-01

    Full Text Available This work describes the investigation of the final flotation waste (FFW, originating from the RTB Bor Company (Serbia, as the main component for the production of glass-ceramic materials. The glass-ceramics was synthesized by the sintering of FFW, mixtures of FFW with basalt (10%, 20%, and 40%, and mixtures of FFW with tuff (20% and 40%. The sintering was conducted at the different temperatures and with the different time duration in order to find the optimal composition and conditions for crystallization. The increase of temperature, from 1100 to 1480°C, and sintering time, from 4 to 6h resulted in a higher content of hematite crystal in the obtained glass-ceramic (up to 44%. The glass-ceramics sintered from pure FFW (1080°C/36h has good mechanical properties, such as high propagation speed (4500 m/s and hardness (10800 MPa, as well as very good thermal stability. The glass-ceramics obtained from mixtures shows weaker mechanical properties compared to that obtained from pure FFW. The mixtures of FFW with tuff have a significantly lower bulk density compared to other obtained glass-ceramics. Our results indicate that FFW can be applied as a basis for obtaining the construction materials. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 176010: Composition, genesis, application, and contribution to the environmental sustainability

  20. An Exploratory Study: Assessment of Modeled Dioxin Exposure in Ceramic Art Studios (Final Report, 2008)

    Science.gov (United States)

    EPA announced the availability of the final report, An Exploratory Study: Assessment of Modeled Dioxin Exposure in Ceramic Art Studios. This report investigates the potential dioxin exposure to artists/hobbyists who use ball clay to make pottery and related products. Derm...

  1. Effect of esthetic core shades on the final color of IPS Empress all-ceramic crowns.

    Science.gov (United States)

    Azer, Shereen S; Ayash, Ghada M; Johnston, William M; Khalil, Moustafa F; Rosenstiel, Stephen F

    2006-12-01

    Clinically relevant assessment of all-ceramic crowns supported by esthetic composite resin foundations has not been evaluated with regard to color reproducibility. This in vitro study quantitatively evaluated the influence of different shades of composite resin foundations and resin cement on the final color of a leucite-reinforced all-ceramic material. A total of 128 disks were fabricated; 64 (20 x 1 mm) were made of all-ceramic material (IPS Empress) and 64 (20 x 4 mm) of 4 different shades composite resin (Tetric Ceram). The ceramic and composite resin disks were luted using 2 shades (A3 and Transparent) of resin cement (Variolink II). Color was measured using a colorimeter configured with a diffuse illumination/0-degree viewing geometry, and Commission Internationale de l'Eclairage (CIE) L( *)a( *)b( *) values were directly calculated. Descriptive statistical analysis was performed, and color differences (DeltaE) for the average L( *), a( *) and b( *) color parameters were calculated. Repeated measures analysis of variance (ANOVA) was used to compare mean values and SDs between the different color combinations (alpha=.05). The CIE L( *)a( *)b( *) color coordinate values showed no significant differences for variation in color parameters due to the effect of the different composite resin shades (P=.24) or cement shades (P=.12). The mean color difference (DeltaE) value between the groups was 0.8. Within the limitations of this study, the use of different shades for composite resin cores and resin cements presented no statistically significant effect on the final color of IPS Empress all-ceramic material.

  2. High-speed, low-damage grinding of advanced ceramics Phase 1. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kovach, J.A. [Eaton Corp., Willoughby Hills, OH (United States). Mfg. Technologies Center; Malkin, S. [Univ. of Massachusetts (United States)

    1995-03-01

    In manufacture of structural ceramic components, grinding costs can comprise up to 80% of the entire manufacturing cost. Most of these costs arise from the conventional multi-step grinding process with numerous grinding wheels and additional capital equipment, perishable dressing tools, and labor. In an attempt to reduce structural ceramic grinding costs, a feasibility investigation was undertaken to develop a single step, roughing-finishing process suitable for producing high-quality silicon nitride ceramic parts at high material removal rates at lower cost than traditional, multi-stage grinding. This feasibility study employed combined use of laboratory grinding tests, mathematical grinding models, and characterization of resultant material surface condition. More specifically, this Phase 1 final report provides a technical overview of High-Speed, Low-Damage (HSLD) ceramic grinding and the conditions necessary to achieve the small grain depths of cut necessary for low damage grinding while operating at relatively high material removal rates. Particular issues addressed include determining effects of wheel speed and material removal rate on resulting mode of material removal (ductile or brittle fracture), limiting grinding forces, calculation of approximate grinding zone temperatures developed during HSLD grinding, and developing the experimental systems necessary for determining HSLD grinding energy partition relationships. In addition, practical considerations for production utilization of the HSLD process are also discussed.

  3. Microwave assisted low temperature synthesis of sodium zirconium phosphate (NZP) and the leachability of some selected fission products incorporated in its structure

    International Nuclear Information System (INIS)

    Dharwadkar, S.R.

    2008-01-01

    Full text: Microwave assisted procedure for low temperature solid state synthesis of sodium zirconium phosphate (NZP), a material with the potential for immobilization and disposal of high level nuclear waste, was developed. Four selected fission products, namely cesium, strontium, tellurium and ruthenium were introduced (substituted) in the NZP matrix during its synthesis at 450 deg C. More than 85% of these elements incorporated at this temperature could be retained in the NZP compacts, sintered in air at 1000 deg C to nearly 90% of the theoretical density of pure sodium zirconium phosphate. Leaching studies were carried out on the fission product substituted sintered NZP compacts in pure de-ionized water and 80% saturated brine solution at the ambient temperatures of 30 deg C and 90 deg C for four weeks. The major part of leaching in all the cases was observed in the first week. The maximum amount of the substituted element leached in the liquid media after four weeks, however did not exceed 12% of the total amount originally present in the sample before leaching. No significant leaching was observed for any of the dopant elements after four weeks. Among the substituted elements maximum leaching was observed for tellurium followed by cesium and strontium. Ruthenium showed virtually no leaching under the conditions employed. Leaching was found to decrease considerably in multiple element substituted NZP. The effect of temperature on the leaching rate was marginal but substantial difference was observed when the leachant was changed from pure de-ionized water to brine solution. Tellurium and strontium exhibited three and two fold decrease in the leaching rate respectively on changing the leachant from pure de-ionized water to 80% saturated brine solution. The leach rate of Cs however remained virtually unaffected by this change. The SEM and EDX analysis of the surfaces of the leached pellets showed virtual absence of the dopants introduced in the NZP matrix

  4. Ceramic High Efficiency Particulate Air (HEPA) Filter Final Report CRADA No. TC02160.0

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Bergman, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-08-25

    The technical objective of this project was to develop a ceramic HEPA filter technology, by initially producing and testing coupon ceramics, small scale prototypes, and full scale prototype HEPA filters, and to address relevant manufacturing and commercialization technical issues.

  5. Development of abrasion resistant glass-ceramics from industrial waste products. Final report

    Energy Technology Data Exchange (ETDEWEB)

    von Roode, M.

    1983-05-26

    Slag-ceramics were produced from glass compositions using pelletized slag as the major ingredient. The abrasion resistance, fracture toughness and microstructure of the prepared glass and glass-ceramics were evaluated. Glas-ceramics with good abrasion resistance were obtained when iron oxide in conjunction with carbon was used as a nucleating agent. 5 figs., 11 tabs.

  6. Effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations: in vitro study of color masking ability.

    Science.gov (United States)

    Oh, Seon-Hee; Kim, Seok-Gyu

    2015-10-01

    The aim of the study was to evaluate the effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations. Three different types of disk-shaped zirconia coping specimens (Lava, Cercon, Zirkonzahn: ø10 mm × 0.4 mm) were fabricated and veneered with IPS e.max Press Ceram (shade A2), for total thicknesses of 1 and 1.5 mm. A total of sixty zirconia restoration specimens were divided into six groups based on their coping types and thicknesses. The abutment specimens (ø10 mm × 7 mm) were prepared with gold alloy, base metal (nickel-chromium) alloy, and four different shades (A1, A2, A3, A4) of composite resins. The average L*, a*, b* values of the zirconia specimens on the six abutment specimens were measured with a dental colorimeter, and the statistical significance in the effects of three variables was analyzed by using repeated measures analysis of variance (α=.05).The average shade difference (ΔE) values of the zirconia specimens between the A2 composite resin abutment and other abutments were also evaluated. The effects of zirconia specimen thickness (Pabutment shade (Pabutments was higher (close to the acceptability threshold of 5.5 ΔE) than th ose between the A2 composite resin and other abutments. This in-vitro study demonstrated that abutment shade, ceramic thickness, and coping type affected the resulting shade of zirconia restorations.

  7. Stress relief of ceramic components in high voltage assemblies. Final report

    International Nuclear Information System (INIS)

    Heinen, R.J.

    1979-02-01

    Two types of ceramic packages were evaluated to determine the effectiveness of encapsulating the ceramic components in beta eucryptite filled epoxy. The requirements (no high voltage breakdown, no ceramic cracking, and no encapsulant cracking) were met by the spark gap assembly, but the sprytron assembly had cracking in the encapsulant after thermal cycling. The encapsulation of the ceramic component in beta eucryptite filled epoxy with a stress decoupling material selectively applied in the stress concentrated areas were used to prevent cracking in the sprytron encapsulant. This method is proposed as the standard encapsulation process for high voltage ceramic components

  8. Effect of translucence of engineering ceramics on heat transfer in diesel engines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Wahiduzzaman, S.; Morel, T. [Integral Technologies, Inc., Westmont, IL (United States)

    1992-04-01

    This report describes the experimental portion of a broader study undertaken to assess the effects of translucence of ceramic materials used as thermal barrier coatings in diesel engines. In an earlier analytical work a parametric study was performed, varying several radiative properties over ranges typical of engineering ceramics, thereby identifying the most important radiative properties and their impact on in-cylinder heat transfer. In the current study these properties were experimentally determined for several specific zirconia coatings considered for thermal barrier applications in diesel engines. The methodology of this study involved formulation of a model capable of describing radiative transfer through a semitransparent medium as a function of three independent model parameters, ie, absorption coefficient, scattering coefficient and refractive index. For the zirconia-based ceramics investigated in this study, it was concluded that for usual coating thicknesses (1.5--2.5 mm) these ceramics are optically thick and hence, are effective as radiative heat transfer barriers. These ceramics possess high scattering coefficients and low absorption coefficients causing them to be highly reflective (60-80%) in the spectral region where thermal radiation is important. The performance of the investigated ceramics and the mechanism of heat transfer were found to depend on surface condition, specifically on soot deposition. Thus, to insure the optimum thermal barrier operation for either clean or heavily sooted surfaces, a ceramic material with high scattering coefficient provides the best choice.

  9. Life prediction methodology for ceramic components of advanced heat engines. Phase 1: Volume 1, Final report

    Energy Technology Data Exchange (ETDEWEB)

    Cuccio, J.C.; Brehm, P.; Fang, H.T. [Allied-Signal Aerospace Co., Phoenix, AZ (United States). Garrett Engine Div.] [and others

    1995-03-01

    Emphasis of this program is to develop and demonstrate ceramics life prediction methods, including fast fracture, stress rupture, creep, oxidation, and nondestructive evaluation. Significant advancements were made in these methods and their predictive capabilities successfully demonstrated.

  10. The development and testing of ceramic components in piston engines. Final report

    Energy Technology Data Exchange (ETDEWEB)

    McEntire, B.J. [Norton Co., Northboro, MA (United States). Advanced Ceramics Div.; Willis, R.W.; Southam, R.E. [TRW, Inc., Cleveland, OH (United States)

    1994-10-01

    Within the past 10--15 years, ceramic hardware has been fabricated and tested in a number of piston engine applications including valves, piston pins, roller followers, tappet shims, and other wear components. It has been shown that, with proper design and installation, ceramics improve performance, fuel economy, and wear and corrosion resistance. These results have been obtained using rig and road tests on both stock and race engines. Selected summaries of these tests are presented in this review paper.

  11. A continuing study of electrically conducting ceramics. Final report, August 9, 1978 - March 31, 1979

    Energy Technology Data Exchange (ETDEWEB)

    1979-01-01

    A series of 36 perovskite ceramics based on SrZrO/sub 3/ has been prepared and investigated as potential materials for electrodes for MHD systems using hydrogen as a fuel. All ceramics prepared were found to be relatively dark in color, indicating optical absorptions associated with the existence of conduction electrons. Many were found to be soft and crumbly after firing at 1400/sup 0/ or 1500/sup 0/C, but became hard and often quite shiny when fired at 1650/sup 0/C using a special graphite induction furnace. In most cases, this increase in hardness was also accompanied by a significant density increase. Most ceramics were found to be composed of second perovskite structures, i.e. manganates of Ba, Ca, Sr or La, in addition to the zirconate phase. Their room temperature electrical resistivity was determined by the van der Paaw method. Results show that resistivity falls below 100 ohm-cm (the value acceptable for MHD electrodes) for certain ceramics of the types tested. The resistivity value was found to vary significantly with firing temperature; this can be correlated with the crystal structures and number of phases within the ceramic. Weight loss measurements done at 1440/sup 0/C have enabled three ceramics to be identified as potential materials for thermoelectric converters requiring high temperature structural and chemical stability in oxidizing atmospheres. An appendix reviews the current status of the basis for development of perovskite ceramics and specific materials are discussed on the basis of relevant thermoelectric properties. Also included is a review of semiconductor thermocouples and of materials selection for insulators and electrodes for use in MHD systems. 91 refs., 3 figs., 10 tabs.

  12. Innovative grinding wheel design for cost-effective machining of advanced ceramics. Phase I, final report

    Energy Technology Data Exchange (ETDEWEB)

    Licht, R.H.; Ramanath, S.; Simpson, M.; Lilley, E.

    1996-02-01

    Norton Company successfully completed the 16-month Phase I technical effort to define requirements, design, develop, and evaluate a next-generation grinding wheel for cost-effective cylindrical grinding of advanced ceramics. This program was a cooperative effort involving three Norton groups representing a superabrasive grinding wheel manufacturer, a diamond film manufacturing division and a ceramic research center. The program was divided into two technical tasks, Task 1, Analysis of Required Grinding Wheel Characteristics, and Task 2, Design and Prototype Development. In Task 1 we performed a parallel path approach with Superabrasive metal-bond development and the higher technical risk, CVD diamond wheel development. For the Superabrasive approach, Task 1 included bond wear and strength tests to engineer bond-wear characteristics. This task culminated in a small-wheel screening test plunge grinding sialon disks. In Task 2, an improved Superabrasive metal-bond specification for low-cost machining of ceramics in external cylindrical grinding mode was identified. The experimental wheel successfully ground three types of advanced ceramics without the need for wheel dressing. The spindle power consumed by this wheel during test grinding of NC-520 sialon is as much as to 30% lower compared to a standard resin bonded wheel with 100 diamond concentration. The wheel wear with this improved metal bond was an order of magnitude lower than the resin-bonded wheel, which would significantly reduce ceramic grinding costs through fewer wheel changes for retruing and replacements. Evaluation of ceramic specimens from both Tasks 1 and 2 tests for all three ceramic materials did not show evidence of unusual grinding damage. The novel CVD-diamond-wheel approach was incorporated in this program as part of Task 1. The important factors affecting the grinding performance of diamond wheels made by CVD coating preforms were determined.

  13. Development of low-expansion ceramics with strength retention to elevated temperatures. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hirschfeld, D.A.; Brown, J.J. Jr. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

    1994-09-01

    The development of advanced engines has resulted in the need for new ceramic compositions which exhibit thermo-mechanical properties suitable for the engine environment, e.g., low thermal expansion, stability to 1,200 C, and thermal shock resistance. To meet these goals, a two phase research program was instituted. In the first phase, new oxide ceramics were identified in the AlPO{sub 4}-{beta}-eucryptite, {beta}-cristobalite, mullite and zircon systems. This research focused on screening and property characterization of ceramics in the four systems. The most promising compositions in the AlPO{sub 4}-{beta}-eucryptite and zircon systems were then further evaluated and developed in the second phase with the goal of being ready for prototype testing in actual engines. Of the compositions, calcium magnesium zirconium phosphate (zircon system) exhibits the most desirable properties and is presently being developed for commercialization.

  14. Electric-Loading Enhanced Kinetics in Oxide Ceramics: Pore Migration, Sintering and Grain Growth: Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Chen, I-Wei [Univ. of Pennsylvania, Philadelphia, PA (United States). Dept. of Materials Science & Engineering

    2018-02-02

    Solid oxide fuel cells and solid oxide electrolysis cells rely on solid electrolytes in which a large ionic current dominates. This project was initiated to investigate microstructural changes in such devices under electrochemical forces, because nominally insignificant processes may couple to the large ionic current to yield non-equilibrium phenomena that alter the microstructure. Our studies had focused on yttria-stabilized cubic zirconia (YSZ) widely used in these devices. The experiments have revealed enhanced grain growth at higher temperatures, pore and gas bubble migration at all temperatures, and the latter also lead to enhanced sintering of highly porous ceramics into fully dense ceramics at unprecedentedly low temperatures. These results have shed light on kinetic processes that fall completely outside the realm of classical ceramic processing. Other fast-oxygen oxide ceramics closely related to, and often used in conjunction with zirconia ceramics, have also be investigated, as are closely related scientific problems in zirconia ceramics. These include crystal structures, defects, diffusion kinetics, oxygen potentials, low temperature sintering, flash sintering, and coarsening theory, and all have resulted in greater clarity in scientific understanding. The knowledge is leveraged to provide new insight to electrode kinetics and near-electrode mixed conductivity and to new materials. In the following areas, our research has resulted in completely new knowledge that defines the state-of-the-art of the field. (a) Electrical current driven non-equilibrium phenomena, (b) Enhanced grain growth under electrochemically reducing conditions, (c) Development of oxygen potential polarization in electrically loaded electrolyte, (d) Low temperature sintering and grain growth, and (e) Structure, defects and cation kinetics of fluorite-structured oxides. Our research has also contributed to synthesis of new energy-relevant electrochemical materials and new understanding

  15. Mechanical behavior of a ceramic matrix composite material. M.S. Thesis Final Report

    Science.gov (United States)

    Grosskopf, Paul P.; Duke, John C., Jr.

    1991-01-01

    Monolithic ceramic materials have been used in industry for hundreds of years. These materials have proven their usefulness in many applications, yet, their potential for critical structural applications is limited. The existence of an imperfection in a monolithic ceramic on the order of several microns in size may be critical, resulting in catastrophic failure. To overcome this extreme sensitivity to small material imperfections, reinforced ceramic materials were developed. A ceramic matrix which has been reinforced with continuous fibers is not only less sensitive to microscopic flaws, but is also able to sustain significant damage without suffering catastrophic failure. A borosilicate glass reinforced with several layers of plain weave silicon carbide cloth (Nicalon) was studied. The mechanical testing which was performed included both flexural and tensile loading configurations. This testing was done not only to determine the material properties, but also to initiate a controlled amount of damage within each specimen. Several nondestructive testing techniques, including acousto-ultrasonics (AU), were performed on the specimens periodically during testing. The AU signals were monitored through the use of an IBM compatible personal computer with a high speed data acquisition board. Software was written which manipulates the AU signals in both the time and frequency domains, resulting in quantitative measures of the mechanical response of the material. The measured AU parameters are compared to both the mechanical test results and data from other nondestructive methods including ultrasonic C-scans and penetrant enhanced x ray radiography.

  16. Superplasticity in fine-grained ceramics. Final report, 1 July 1993--31 December 1993

    Energy Technology Data Exchange (ETDEWEB)

    Nieh, T.G.

    1994-01-31

    Progress has been summarized in three papers: biaxial gas-pressure forming of a superplastic Al{sub 2}O{sub 3}/YTZP; mechanical properties of a 20 vol% SiC whisker-reinforced yttria-stabilized, tetragonal zirconia composite at elevated temperatures; and gas- pressure forming of ceramic sheet.

  17. Facilitated transport ceramic membranes for high-temperature gas cleanup. Final report, February 1990--April 1994

    Energy Technology Data Exchange (ETDEWEB)

    Quinn, R.; Minford, E.; Damle, A.S.; Gangwal, S.K.; Hart, B.A.

    1994-04-01

    The objective of this program was to demonstrate the feasibility of developing high temperature, high pressure, facilitated transport ceramic membranes to control gaseous contaminants in Integrated Gasification Combined Cycle (IGCC) power generation systems. Meeting this objective requires that the contaminant gas H{sub 2}S be removed from an IGCC gas mixture without a substantial loss of the other gaseous components, specifically H{sub 2} and CH{sub 4}. As described above this requires consideration of other, nonconventional types of membranes. The solution evaluated in this program involved the use of facilitated transport membranes consisting of molten mixtures of alkali and alkaline earth carbonate salts immobilized in a microporous ceramic support. To accomplish this objective, Air Products and Chemicals, Inc., Golden Technologies Company Inc., and Research Triangle Institute worked together to develop and test high temperature facilitated membranes for the removal of H{sub 2}S from IGCC gas mixtures. Three basic experimental activities were pursued: (1) evaluation of the H{sub 2}S chemistry of a variety of alkali and alkaline earth carbonate salt mixtures; (2) development of microporous ceramic materials which were chemically and physically compatible with molten carbonate salt mixtures under IGCC conditions and which could function as a host to support a molten carbonate mixture and; (3) fabrication of molten carbonate/ceramic immobilized liquid membranes and evaluation of these membranes under conditions approximating those found in the intended application. Results of these activities are presented.

  18. Microwave Sintering of Ceramic Materials for Industrial Application Final Report CRADA No. TC-1116-95

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Tandon, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Callis, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-10-19

    The goal of this project was to develop the commercial capability in the US to sinter alumina oxide ceramic parts for the semiconductor manufacturing equipment industry. We planned to use the millimeter microwave (30 GHz) sintering system first developed by IAP in Russia.

  19. 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....

  20. Radiation Damage Effects in Candidate Ceramics for Plutonium Immobilization: Final Report

    International Nuclear Information System (INIS)

    Strachan, Denis M.; Scheele, Randall D.; Icenhower, Jonathan P.; Buck, Edgar C.; Kozelisky, Anne E.; Sell, Rachel L.; Elovich, Robert J.; Buchmiller, William C.

    2004-01-01

    In this document, we summarize our study of the effects of radiation induced damage to the titanate ceramics that were to be the immobilization form for surplus weapons-grade Pu. In this study, we made five ceramic materials: pure-phase pyrochlore, pure-phase zirconolite, pyrochlore-rich baseline, zirconolite-rich baseline, and impurity baseline. Two-hundred specimens were made of which 130 contained approximately 10 mass% 238Pu and 70 contained 10 mass% 239Pu. The specimens containing 239Pu served as materials against which the behavior of the 238Pu-bearing specimens could be compared. In our studies, we measured the true density (density exclusive of surface connected porosity), bulk density, crystalline-phase composition with X-ray diffraction (XRD), and dissolution rates as radiation induced damage accumulated in the 238Pu-bearing specimens. We routinely took photographs of the specimens during each characterization period. From our studies, we determined that these materials swell less than 10% and generally less than 5%. As the material swells, some open porosity can be converted to closed porosity, often causing the true density to decrease more rapidly than the bulk density. In general, 3?1018 a/g of damage accumulation were required for the materials to become amorphous as determined with the XRD method. The order in which the phases became amorphous was brannerite, pyrochlore, and zirconolite with brannerite being the most susceptible to radiation induced damage. However, we also show that Pu is not evenly distributed amongst the phases when multiple phases are present. We were unsuccessful in making a pure brannerite to study. Therefore, the brannerite was always present with other phases. For a material containing about 10 mass% 239Pu, 3?1018 a/g represent about 500 years in the geologic repository. At no time in our studies was there evidence for microcracking in these materials, even upon close examination in a scanning-electron microscope . Upon

  1. Life prediction methodology for ceramic components of advanced vehicular heat engines: Volume 1. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Khandelwal, P.K.; Provenzano, N.J.; Schneider, W.E. [Allison Engine Co., Indianapolis, IN (United States)

    1996-02-01

    One of the major challenges involved in the use of ceramic materials is ensuring adequate strength and durability. This activity has developed methodology which can be used during the design phase to predict the structural behavior of ceramic components. The effort involved the characterization of injection molded and hot isostatic pressed (HIPed) PY-6 silicon nitride, the development of nondestructive evaluation (NDE) technology, and the development of analytical life prediction methodology. Four failure modes are addressed: fast fracture, slow crack growth, creep, and oxidation. The techniques deal with failures initiating at the surface as well as internal to the component. The life prediction methodology for fast fracture and slow crack growth have been verified using a variety of confirmatory tests. The verification tests were conducted at room and elevated temperatures up to a maximum of 1371 {degrees}C. The tests involved (1) flat circular disks subjected to bending stresses and (2) high speed rotating spin disks. Reasonable correlation was achieved for a variety of test conditions and failure mechanisms. The predictions associated with surface failures proved to be optimistic, requiring re-evaluation of the components` initial fast fracture strengths. Correlation was achieved for the spin disks which failed in fast fracture from internal flaws. Time dependent elevated temperature slow crack growth spin disk failures were also successfully predicted.

  2. Hollow ceramic block: containment of water for thermal storage in passive solar design. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Winship, C.T.

    1983-12-27

    The project activity has been the development of designs, material compositions and production procedures to manufacture hollow ceramic blocks which contain water (or other heat absorptive liquids). The blocks are designed to serve, in plurality, a dual purpose: as an unobtrusive and efficient thermal storage element, and as a durable and aesthetically appealing surface for floors and walls of passive solar building interiors. Throughout the grant period, numerous ceramic formulas have been tested for their workabilty, thermal properties, maturing temperatures and color. Blocks have been designed to have structural integrity, and textured surfaces. Methods of slip-casting and extrusion have been developed for manufacturing of the blocks. The thermal storage capacity of the water-loaded block has been demonstrated to be 2.25 times greater than that of brick and 2.03 times greater than that of concrete (taking an average of commonly used materials). Although this represents a technical advance in thermal storage, the decorative effects provided by application of the blocks lend them a more significant advantage by reducing constraints on interior design in passive solar architecture.

  3. Continuous fiber ceramic composite. Phase I final report, April 1992--April 1993

    Energy Technology Data Exchange (ETDEWEB)

    Goettler, R.W.

    1995-04-01

    Babcock and Wilcox assembled a team to develop the Continuous Fiber Ceramic Composite (CFCC) processing technology, identify the industrial applications, generate design and life prediction software, and to begin the necessary steps leading to full commercialization of CFCC components. Following is a summary of Phase I activities on this program. B&W has selected an oxide-oxide composite system for development and optimization in this program. This selection was based on the results of exposure tests in combustion environments typical of the boiler and heat exchanger applications. Aluminum oxide fiber is the selected reinforcement, and both aluminum oxide and zirconium oxide matrices were selected, based on their superior resistance to chemical attack in hostile industrial service.

  4. Ceramic High Efficiency Particulate Air (HEPA) Filter Final Report CRADA No. TC02102.0

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Morse, T. [Flanders Corp., Washington, DC (United States)

    2017-09-06

    This was a collaborative effort between Lawrence Livermore National Security, LLC (formerly The Regents of the University of California)/Lawrence Livermor e National Laboratory (LLNL) and Flanders-Precisionaire (Flanders), to develop ceramic HEP A filters under a Thrust II Initiative for Proliferation Prevention (IPP) project. The research was conducted via the IPP Program at Commonwe alth of Independent States (CIS) Institutes, which are handled under a separate agreement. The institutes (collectively referred to as "CIS Institutes") involved with this project were: Bochvar: Federal State Unitarian Enterprise All-Russia Scientific and Research Institute of Inorganic Materials (FSUE VNIINM); Radium Khlopin: Federal State Unitarian Enterprise NPO Radium Institute named (FSUE NPO Radium Institute); and Bakor: Science and Technology Center Bakor (STC Bakor).

  5. Investigation of properties and performance of ceramic composite components: Final report on Phases 3 and 4

    Energy Technology Data Exchange (ETDEWEB)

    Curtin, W.A.; Halverson, H.; Carter, R.H.; Miraj, N.; Reifsnider, K.L. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

    1998-01-15

    The objective of the Fossil Energy Advanced Research and Technology Development (AR and TD) Materials Program is to conduct research and development on materials for longer-term fossil energy applications as well as for generic needs of various fossil fuel technologies. The research program of the Materials Response Group at Virginia Tech addresses the need for reliable and durable structural ceramic composites to perform in high temperature environments. The research effort provides an experimental and analytical basis for the transition from properties of materials to performance of actual component structures. Phases 1 and 2 of the present program focused on the development of test capabilities, initial studies of component mechanical response under various conditions and the development of a life prediction methodology. These efforts have been described in previous reports. This report summarizes the major tasks completed under Phases 3 and 4 of the project. Overall, the authors have made significant progress in a broad spectrum of tasks in this program. Their efforts have encompassed component evaluation, assessment of new SiC-based composites with improved high-temperature potential, development of oxide coating materials for SiC, and the extension and development of new models for predicting the durability of composite components under specific operating conditions for various CMC applications. Each of these areas of work is an important area for achieving the ultimate goal of usable SiC-based composites in high-temperature corrosive environments typical of fossil energy applications.

  6. Development of materials for open-cycle magnetohydrodynamics (MHD): ceramic electrode. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Bates, J.L.; Marchant, D.D.

    1986-09-01

    Pacific Northwest Laboratory, supported by the US Department of Energy, developed advanced materials for use in open-cycle, closed cycle magnetohydrodynamics (MHD) power generation, an advanced energy conversion system in which the flow of electrically conducting fluid interacts with an electric field to convert the energy directly into electricity. The purpose of the PNL work was to develop electrodes for the MHD channel. Such electrodes must have: (1) electrical conductivity above 0.01 (ohm-cm)/sup -1/ from near room temperature to 1900/sup 0/K, (2) resistance to both electrochemical and chemical corrosion by both slag and potassium seed, (3) resistance to erosion by high-velocity gases and particles, (4) resistance to thermal shock, (5) adequate thermal conductivity, (6) compatibility with other channel components, particularly the electrical insulators, (7) oxidation-reduction stability, and (8) adequate thermionic emission. This report describes the concept and development of high-temperature, graded ceramic composite electrode materials and their electrical and structural properties. 47 refs., 16 figs., 13 tabs.

  7. Effect of ceramic thickness and cement shade on the final shade after bonding using the 3D master system: a laboratory study.

    Science.gov (United States)

    Montero, Javier; Gómez-Polo, Cristina

    2016-06-01

    The final color of a ceramic restoration is influenced by both the ceramic thickness and the cement shade. This study aims to evaluate the color stability according to the 3D Master System of e.max ceramic discs after bonding with different shades of luting agents. A total of 120 e.max.Press 2M1 HT ceramic discs (60 discs of 1-mm thick and 60 discs of 0.5 mm thick) and three different values of Variolink Veneer cement were used (-3, 0, +3) for the cementation process. An Easyshade compact device was used to measure color shade tabs, according to the 3D Master System, on the discs both before and after the cementation protocols. Bivariate and multivariate analyses were carried out with the spss v.21. After bonding with the different luting agents, only 30% remained as 2M1: specifically, 22% of the thinner discs and 37.3% of the thicker discs. In general, the effect of bonding increased the value and the chroma of the shade to a significant extent. Regression analyses revealed that the most significant predictor for all color parameters was cement shade, the thinner disc group bonded with -3 cement being the most unstable subgroup. According to the 3D Master System, the shade of the luting agent was the main predictor of the final color. However, the final color seems to be somewhat unpredictable, at least according to the modulating factors evaluated in the present study.

  8. Effect of metal opaquer on the final color of 3 ceramic crown types on 3 abutment configurations.

    Science.gov (United States)

    Arif, Rabia; Yilmaz, Burak; Mortazavi, Aras; Ozcelik, Tuncer B; Johnston, William M

    2018-04-30

    data, a 1-way ANOVA and subsequent Tukey testing for pairwise comparisons were used. The statistical significance of the analysis of color coordinates was found to be P≤.002. Although 3-way interaction was not found to be significant (P=.335), all three 2-way interactions of the main effects were found to be significant (P≤.002). All crown types on the Zir abutment revealed color differences from the control group. The color differences of the crown types on the Op and Zir abutment configurations compared with the control (LDL/Zir) were not (P>.05) statistically different. Colors of tested crown systems on Ti backing were each unacceptably different from the control group. Colors of these systems on zirconia backing were not perceivably different. Use of opaquer on titanium backing resulted in a small color difference from the control group (P>.05) for each crown system, demonstrating that it may be used to prevent the unfavorable metal show-through that can influence the final color of all ceramic crown systems tested. Copyright © 2018 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  9. Systematic investigation of the strontium zirconium phosphate ceramic form for nuclear waste immobilization

    Science.gov (United States)

    Pet'kov, Vladimir; Asabina, Elena; Loshkarev, Vladimir; Sukhanov, Maksim

    2016-04-01

    We have summarized our data and literature ones on the thermophysical properties and hydrolytic stability of Sr0.5Zr2(PO4)3 compound as a host NaZr2(PO4)3-type (NZP) structure for immobilization of 90Sr-containing radioactive waste. Absence of any polymorphic transformations on the temperature dependence of its heat capacity between 7 and 665 K is caused by the stability of crystalline Sr0.5Zr2(PO4)3. Calculated values of thermal conductivity coefficients at zero porosity in the range 298-673 K were 1.86-2.40 W·m-1 K-1. The compound may be classified as low thermal expanding material due to its average linear thermal expansion coefficient. Study of the hydrolytic stability in acid and alkaline media has shown that the relative mass fraction of Sr2+ ions, released into aggressive leaching media, didn't exceed 1% of the mass of sample. Soxhlet leaching studies have shown substantial resistance towards the release of Sr2+ ions into distilled water. Feeble sinterability constrains practical applications of NZP substances, that is why known in literature methods of Sr0.5Zr2(PO4)3 dense ceramics obtaining have been reviewed.

  10. Final Air Toxics Standards for Clay Ceramics Manufacturing, Glass Manufacturing, and Secondary Nonferrous Metals Processing Area Sources Fact Sheet

    Science.gov (United States)

    This page contains a December 2007 fact sheet with information regarding the National Emissions Standards for Hazardous Air Pollutants (NESHAP) for Clay Ceramics Manufacturing, Glass Manufacturing, and Secondary Nonferrous Metals Processing Area Sources

  11. Final Project Report CFA-14-6357: A New Paradigm for Understanding Multiphase Ceramic Waste Form Performance

    Energy Technology Data Exchange (ETDEWEB)

    Brinkman, Kyle [Clemson Univ., SC (United States); Bordia, Rajendra [Clemson Univ., SC (United States); Reifsnider, Kenneth [Univ. of South Carolina, Columbia, SC (United States); Chiu, Wilson [Univ. of Connecticut, Storrs, CT (United States); Amoroso, Jake [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-12-28

    This project fabricated model multiphase ceramic waste forms with processing-controlled microstructures followed by advanced characterization with synchrotron and electron microscopy-based 3D tomography to provide elemental and chemical state-specific information resulting in compositional phase maps of ceramic composites. Details of 3D microstructural features were incorporated into computer-based simulations using durability data for individual constituent phases as inputs in order to predict the performance of multiphase waste forms with varying microstructure and phase connectivity.

  12. Development of Advanced Materials for Electro-Ceramic Application Final Report CRADA No. TC-1331-96

    Energy Technology Data Exchange (ETDEWEB)

    Caplan, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Olstad, R. [General Atomics, San Diego, CA (United States); McMillan, L. [Symetrix International, Inc., Colorado Springs, CO (United States); Tulupov, A. [Soliton-NTT, Moscow (Russia)

    2017-10-19

    The goal of this project was to further develop and characterize the electrochemical methods originating in Russia for producing ultra high purity organometallic compounds utilized as precursors in the production of high quality electro-ceramic materials. Symetrix planned to use electro-ceramic materials with high dielectric constant for microelectronic memory circuit applications. General Atomics planned to use the barium titanate type ceramics with low loss tangent for producing a high power ferroelectric tuner used to match radio frequency power into their Dill-D fusion machine. Phase I of the project was scheduled to have a large number of organometallic (alkoxides) chemical samples produced using various methods. These would be analyzed by LLNL, Soliton and Symetrix independently to determine the level of chemical impurities thus verifying each other's analysis. The goal was to demonstrate a cost-effective production method, which could be implemented in a large commercial facility to produce high purity organometallic compounds. In addition, various compositions of barium-strontium-titanate ceramics were to be produced and analyzed in order to develop an electroceramic capacitor material having the desired characteristics with respect to dielectric constant, loss tangent, temperature characteristics and non-linear behavior under applied voltage. Upon optimizing the barium titanate material, 50 capacitor preforms would be produced from this material demonstrating the ability to produce, in quantity, the pills ultimately required for the ferroelectric tuner (approx 2000-3000 ceramic pills).

  13. Characterization of ceramics and semiconductors using nuclear techniques. Final report of a co-ordinated research project

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-03-01

    With the aim of promoting research and facilitating more extensive application of nuclear techniques for material development, the IAEA established in 1994 a Co-ordinated Research Project (CRP) on Characterization of Ceramics and Semiconductors using Nuclear Techniques. This publication reviews and summarizes recent developments in this field and includes an assessment of the current status and trends in nuclear techniques in characterization of inorganic materials of technological importance. The TECDOC presents new achievements on ceramic superconductor behaviour under neutron induced defects, optimization of structure of mineral gels,m low temperature preparation of fine particles of ferrites, crystal luminescence of ceramic composites with improved plastic properties, thin film defects and detoxification of asbestos. The investigation of chemical composition, phase transitions and magnetic properties of ferrites by Moessbauer spectroscopy is largely developed. The document includes 18 individual contributions, each of them has been indexed and provided with an abstract Refs, figs, tabs

  14. Characterization of ceramics and semiconductors using nuclear techniques. Final report of a co-ordinated research project

    International Nuclear Information System (INIS)

    1999-03-01

    With the aim of promoting research and facilitating more extensive application of nuclear techniques for material development, the IAEA established in 1994 a Co-ordinated Research Project (CRP) on Characterization of Ceramics and Semiconductors using Nuclear Techniques. This publication reviews and summarizes recent developments in this field and includes an assessment of the current status and trends in nuclear techniques in characterization of inorganic materials of technological importance. The TECDOC presents new achievements on ceramic superconductor behaviour under neutron induced defects, optimization of structure of mineral gels,m low temperature preparation of fine particles of ferrites, crystal luminescence of ceramic composites with improved plastic properties, thin film defects and detoxification of asbestos. The investigation of chemical composition, phase transitions and magnetic properties of ferrites by Moessbauer spectroscopy is largely developed. The document includes 18 individual contributions, each of them has been indexed and provided with an abstract

  15. A Glass-Ceramic Waste Forms for the Immobilization of Rare Earth Oxides from the Pyroprocessing Waste salt

    International Nuclear Information System (INIS)

    Ahn, Byung-Gil; Park, Hwan-Seo; Kim, Hwan-Young; Kim, In-Tae

    2008-01-01

    The fission product of rare earth (RE) oxide wastes are generates during the pyroprocess . Borosilicate glass or some ceramic materials such as monazite, apatite or sodium zirconium phosphate (NZP) have been a prospective host matrix through lots of experimental results. Silicate glasses have long been the preferred waste form for the immobilization of HLW. In immobilization of the RE oxides, the developed process on an industrial scale involves their incorporation into a glass matrix, by melting under 1200 ∼ 1300 .deg. C. Instead of the melting process, glass powder sintering is lower temperature (∼ 900 .deg. C) required for the process which implies less demanding conditions for the equipment and a less evaporation of volatile radionuclides. This study reports the behaviors, direct vitrification of RE oxides with glass frit, glass powder sintering of REceramic with glass frit, formation of RE-apatite (or REmonazite) ceramic according to reaction temperature, and the leach resistance of the solidified waste forms

  16. Final technical report to Department of Energy, Basic Energy Sciences. ''Oxide ceramic alloys and microlaminates'' (1996-1999) and ''Low temperature processing and kinetics of ceramics and ceramic matrix composites with large interfacial areas'' (1999-2000)

    Energy Technology Data Exchange (ETDEWEB)

    Chen, I-Wei

    2001-03-26

    We have discovered a novel two-step sintering method that opened up a low temperature processing window within which fully dense nanocrystalline yttrium oxide was obtained with no concurrent grain growth during final-stage sintering. We have developed a new method of processing laminate ceramics using deformation processing in the green state. We have lastly developed a colloidal processing technique to encapsulate biomolecules at ambient, neutral-pH, aqueous conditions.

  17. Commercialization of Ultra-Hard Ceramics for Cutting Tools Final Report CRADA No. TC0279.0

    Energy Technology Data Exchange (ETDEWEB)

    Landingham, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Neumann, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2017-08-15

    This was a collaborative effort between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and Greenleaf Corporation (Greenleaf) to develop the technology for forming unique precursor nano-powders process that can be consolidated into ceramic products for industry. LLNL researchers have developed a solgel process for forming nano-ceramic powders. The nano powders are highly tailorable, allowing the explicit design of desired properties that lead to ultra hard materials with fine grain size. The present CRADA would allow the two parties to continue the development of the sol-gel process and the consolidation process in order to develop an industrially sound process for the manufacture of these ultra-hard materials.

  18. Fabrication of large-volume, low-cost ceramic lanthanum halide scintillators for gamma ray detection : final report for DHS/DNDO/TRDD project TA-01-SL01.

    Energy Technology Data Exchange (ETDEWEB)

    Boyle, Timothy J.; Ottley, Leigh Anna M.; Yang, Pin; Chen, Ching-Fong; Sanchez, Margaret R.; Bell, Nelson Simmons

    2008-10-01

    This project uses advanced ceramic processes to fabricate large, optical-quality, polycrystalline lanthanum halide scintillators to replace small single crystals produced by the conventional Bridgman growth method. The new approach not only removes the size constraint imposed by the growth method, but also offers the potential advantages of both reducing manufacturing cost and increasing production rate. The project goal is to fabricate dense lanthanum halide ceramics with a preferred crystal orientation by applying texture engineering and solid-state conversion to reduce the thermal mechanical stress in the ceramic and minimize scintillation light scattering at grain boundaries. Ultimately, this method could deliver the sought-after high sensitivity and <3% energy resolution at 662 keV of lanthanum halide scintillators and unleash their full potential for advanced gamma ray detection, enabling rapid identification of radioactive materials in a variety of practical applications. This report documents processing details from powder synthesis, seed particle growth, to final densification and texture development of cerium doped lanthanum bromide (LaBr{sub 3}:Ce{sup +3}) ceramics. This investigation demonstrated that: (1) A rapid, flexible, cost efficient synthesis method of anhydrous lanthanum halides and their solid solutions was developed. Several batches of ultrafine LaBr{sub 3}:Ce{sup +3} powder, free of oxyhalide, were produced by a rigorously controlled process. (2) Micron size ({approx} 5 {micro}m), platelet shape LaBr{sub 3} seed particles of high purity can be synthesized by a vapor phase transport process. (3) High aspect-ratio seed particles can be effectively aligned in the shear direction in the ceramic matrix, using a rotational shear-forming process. (4) Small size, highly translucent LaBr{sub 3} (0.25-inch diameter, 0.08-inch thick) samples were successfully fabricated by the equal channel angular consolidation process. (5) Large size, high density

  19. Research & Development of Materials/Processing Methods for Continuous Fiber Ceramic Composites (CFCC) Phase 2 Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Szweda, A.

    2001-01-01

    The Department of Energy's Continuous Fiber Ceramic Composites (CFCC) Initiative that begun in 1992 has led the way for Industry, Academia, and Government to carry out a 10 year R&D plan to develop CFCCs for these industrial applications. In Phase II of this program, Dow Corning has led a team of OEM's, composite fabricators, and Government Laboratories to develop polymer derived CFCC materials and processes for selected industrial applications. During this phase, Dow Corning carried extensive process development and representative component demonstration activities on gas turbine components, chemical pump components and heat treatment furnace components.

  20. High-performance ceramic filters for energy engineering. Final report; Filter aus Hochleistungskeramik fuer die Energietechnik. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Westerheide, R. [Fraunhofer-Institut fuer Werkstoffmechanik (IWM), Freiburg im Breisgau (Germany); Adler, J. [Fraunhofer-Institut fuer Keramische Technologien und Sinterwerkstoffe (IKTS), Dresden (Germany); Buhl, H. [ESK-SIC GmbH, Frechen-Grefrath (Germany); Fister, D. [H.C. Starck GmbH, Laufenburg (Germany); Krein, J. [LLB Lurgi Lentjes Energietechnik GmbH, Frankfurt (Germany); Voelker, W. [Annawerk GmbH, Roedental (Germany); Walch, A. [eds.] [USF Schumacher Umwelt- und Trenntechnik GmbH, Crailsheim (Germany)

    1999-09-30

    The hot gas particulate removal of many advanced coal fired power generation technologies works at temperatures above 800 C. The filter elements for these applications are often based on ceramic materials, e.g. silicon carbide. However, the mostly clay bonded silicon carbide is subject to creep and oxidation due to probable changes of the binder phase. In this work the development of new ceramic filter materials based on silicon carbide and alumina is described. The goal of the development was to increase the potential application temperature. To obtain the goal, the work was performed together with ceramic powder manufacturers, developers of ceramic materials and components as well as with companies who operate test facilities. Different routes were chosen to increase the high temperature resistance in consideration of corrosion resistance, fracture strength and pressure loss of the filter materials. One of these routes was the optimization of the binder phase of the silicon carbide materials. Other routes were concentrated on the base material and the investigation of other possibilities for the silicon carbide bonding, i.e. a recrystallization process of SiC (RSiC) or a self bonding of granulated small grained silicon carbide powder. Additionally filter materials based on alumina were developed. The report covers these material development oriented topics as well as the additional work in materials reliability, coating development and modeling of microstructure. (orig.) [German] In der Kombikraftwerkstechnik wird insbesondere bei Kohlefeuerung die Heissgasreinigung oft bei Temperaturen ueber 800 C eingesetzt. Die Filterelemente fuer diese Anwendungen bestehen oft aus keramischen Materialien. Das haeufig eingesetzte tongebundene Siliciumcarbid unterliegt jedoch besonders aufgrund der Beschaffenheit der Bindephase Kriech- und Oxidationsschaedigungen. In diesem Bericht wird die Entwicklung von neuen keramischen Filtermaterialien, die auf Siliciumcarbid oder

  1. 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…

  2. Technical and economic feasibility of thermal energy storage. Thermal energy storage application to the brick/ceramic industry. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Glenn, D.R.

    1976-10-01

    An initial project to study the technical and economic feasibility of thermal energy storage (TES) in the three major consumer markets, namely, the residential, commercial and industrial sectors is described. A major objective of the study was to identify viable TES applications from which a more concise study could be launched, leading to a conceptual design and in-depth validation of the TES energy impacts. This report documents one such program. The brick/ceramic industries commonly use periodic kilns which by their operating cycle require time-variant energy supply and consequently variable heat rejection. This application was one of the numerous TES opportunities that emerged from the first study, now available from the ERDA Technical Information Center, Oak Ridge, Tennessee, identified as Report No. COO-2558-1.

  3. Advanced ceramic coating development for industrial/utility gas turbines. Final report, 11 Mar 1979-1 Sep 1981

    International Nuclear Information System (INIS)

    Vogan, J.W.; Stetson, A.R.

    1982-01-01

    A program was conducted with the objective of developing advanced thermal barrier coating (TBC) systems. Coating application was by plasma spray. Duplex, triplex and graded coatings were tested. Coating systems incorporated both NiCrAly and CoCrAly bond coats. Four ceramic overlays were tested: ZrO 2 .82O 3 , CaO.TiO 2 , 2CaO.SiO 2 , and MgO.Al 2 O 3 . The best overall results were obtained with a CaO.TiO 2 coating applied to a NiCrAly bond coat. This coating was less sensitive than the ZrO 2 .8Y 2 O 3 coating to process variables and part geometry. Testing with fuels contaminated with compounds containing sulfur, phosphorus and alkali metals showed the zirconia coatings were destabilized. The calcium titanate coatings were not affected by these contaminants. However, when fuels were used containing 50 ppm of vanadium and 150 ppm of magnesium, heavy deposits were formed on the test specimens and combustor components that required frequent cleaning of the test rig. During the program Mars engine first-stage turbine blades were coated and installed for an engine cyclic endurance run with the zirconia, calcium titanate, and calcium silicate coatings. Heavy spalling developed with the calcium silicate system. The zirconia and calcium titanate systems survived the full test duration. It was concluded that these two TBC's showed potential for application in gas turbines

  4. Performance of Transuranic-Loaded Fully Ceramic Micro-Encapsulated Fuel in LWRs Final Report, Including Void Reactivity Evaluation

    International Nuclear Information System (INIS)

    Pope, Michael A.; Sen, R. Sonat; Boer, Brian; Ougouag, Abderrafi M.; Youinou, Gilles

    2011-01-01

    The current focus of the Deep Burn Project is on once-through burning of transuranics (TRU) in light-water reactors (LWRs). The fuel form is called Fully-Ceramic Micro-encapsulated (FCM) fuel, a concept that borrows the tri-isotropic (TRISO) fuel particle design from high-temperature reactor technology. In the Deep Burn LWR (DB-LWR) concept, these fuel particles are pressed into compacts using SiC matrix material and loaded into fuel pins for use in conventional LWRs. The TRU loading comes from the spent fuel of a conventional LWR after 5 years of cooling. Unit cell and assembly calculations have been performed using the DRAGON-4 code to assess the physics attributes of TRU-only FCM fuel in an LWR lattice. Depletion calculations assuming an infinite lattice condition were performed with calculations of various reactivity coefficients performed at each step. Unit cells and assemblies containing typical UO2 and mixed oxide (MOX) fuel were analyzed in the same way to provide a baseline against which to compare the TRU-only FCM fuel. Then, assembly calculations were performed evaluating the performance of heterogeneous arrangements of TRU-only FCM fuel pins along with UO2 pins.

  5. Development of improved processing and evaluation methods for high reliability structural ceramics for advanced heat engine applications, Phase 1. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Pujari, V.K.; Tracey, D.M.; Foley, M.R.; Paille, N.I.; Pelletier, P.J.; Sales, L.C.; Wilkens, C.A.; Yeckley, R.L. [Norton Co., Northboro, MA (United States)

    1993-08-01

    The program goals were to develop and demonstrate significant improvements in processing methods, process controls and non-destructive evaluation (NDE) which can be commercially implemented to produce high reliability silicon nitride components for advanced heat engine applications at temperatures to 1,370{degrees}C. The program focused on a Si{sub 3}N{sub 4}-4% Y{sub 2}O{sub 3} high temperature ceramic composition and hot-isostatic-pressing as the method of densification. Stage I had as major objectives: (1) comparing injection molding and colloidal consolidation process routes, and selecting one route for subsequent optimization, (2) comparing the performance of water milled and alcohol milled powder and selecting one on the basis of performance data, and (3) adapting several NDE methods to the needs of ceramic processing. The NDE methods considered were microfocus X-ray radiography, computed tomography, ultrasonics, NMR imaging, NMR spectroscopy, fluorescent liquid dye penetrant and X-ray diffraction residual stress analysis. The colloidal consolidation process route was selected and approved as the forming technique for the remainder of the program. The material produced by the final Stage II optimized process has been given the designation NCX 5102 silicon nitride. According to plan, a large number of specimens were produced and tested during Stage III to establish a statistically robust room temperature tensile strength database for this material. Highlights of the Stage III process demonstration and resultant database are included in the main text of the report, along with a synopsis of the NCX-5102 aqueous based colloidal process. The R and D accomplishments for Stage I are discussed in Appendices 1--4, while the tensile strength-fractography database for the Stage III NCX-5102 process demonstration is provided in Appendix 5. 4 refs., 108 figs., 23 tabs.

  6. Processing development for ceramic structural components: the influence of a presintering of silicon on the final properties of reaction bonded silicon nitride. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    1982-03-01

    The influence of a presintering of silicon on the final properties of reaction bonded silicon nitride has been studied using scanning electron and optical microscopy, x-ray diffraction analysis, 4 pt. bend test, and mecury intrusion porosimetry. It has been shown that presintering at 1050/sup 0/C will not affect the final nitrided properties. At 1200/sup 0/C, the oxide layer is removed, promoting the formation of B-phase silicon nitride. Presintering at 1200/sup 0/C also results in compact weight loss due to the volatilization of silicon, and the formation of large pores which severely reduce nitrided strength. The development of the structure of sintered silicon compacts appears to involve a temperature gradient, with greater sintering observed near the surface.

  7. Material Performance of Fully-Ceramic Micro-Encapsulated Fuel under Selected LWR Design Basis Scenarios: Final Report

    International Nuclear Information System (INIS)

    Boer, B.; Sen, R.S.; Pope, M.A.; Ougouag, A.M.

    2011-01-01

    The extension to LWRs of the use of Deep-Burn coated particle fuel envisaged for HTRs has been investigated. TRISO coated fuel particles are used in Fully-Ceramic Microencapsulated (FCM) fuel within a SiC matrix rather than the graphite of HTRs. TRISO particles are well characterized for uranium-fueled HTRs. However, operating conditions of LWRs are different from those of HTRs (temperature, neutron energy spectrum, fast fluence levels, power density). Furthermore, the time scales of transient core behavior during accidents are usually much shorter and thus more severe in LWRs. The PASTA code was updated for analysis of stresses in coated particle FCM fuel. The code extensions enable the automatic use of neutronic data (burnup, fast fluence as a function of irradiation time) obtained using the DRAGON neutronics code. An input option for automatic evaluation of temperature rise during anticipated transients was also added. A new thermal model for FCM was incorporated into the code; so-were updated correlations (for pyrocarbon coating layers) suitable to estimating dimensional changes at the high fluence levels attained in LWR DB fuel. Analyses of the FCM fuel using the updated PASTA code under nominal and accident conditions show: (1) Stress levels in SiC-coatings are low for low fission gas release (FGR) fractions of several percent, as based on data of fission gas diffusion in UO 2 kernels. However, the high burnup level of LWR-DB fuel implies that the FGR fraction is more likely to be in the range of 50-100%, similar to Inert Matrix Fuels (IMFs). For this range the predicted stresses and failure fractions of the SiC coating are high for the reference particle design (500 (micro)mm kernel diameter, 100 (micro)mm buffer, 35 (micro)mm IPyC, 35 (micro)mm SiC, 40 (micro)mm OPyC). A conservative case, assuming 100% FGR, 900K fuel temperature and 705 MWd/kg (77% FIMA) fuel burnup, results in a 8.0 x 10 -2 failure probability. For a 'best-estimate' FGR fraction of 50

  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. 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.

  10. 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.

  11. 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

  12. [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.

  13. 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

  14. 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

  15. Effects of internal gas pressure and microstructure on the mechanisms of hot-pressing and swelling in ceramics. Final report, June 1, 1979-May 31, 1980

    International Nuclear Information System (INIS)

    Solomon, A.A.

    1980-08-01

    The results of the study of the effects of internal and external gas pressures on ceramics are summarized. The new experimental systems for studying these phenomena are described. The study has shown that the rate of volume change in ZnO is linearly related to the total pressure driving force. Swelling and hot-pressing can be described on a consistent basis in terms of this driving force. For ZnO, Ni and UO 2 the rate of volume change is dependent on bulk diffusion. The porosity evolution during swelling is described and the resintering phenomenon is identified. Various models for pore growth and shrinkage are considered and related to the behavior of the different systems

  16. 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.

  17. 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.

  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. Development of a ceramic heat exchanger for a combined cycle plant with pressurized coal dust combustion. Final report; Entwicklung eines keramischen Waermeaustauschers fuer eine Kombianlage mit Kohlenstaubdruckfeuerung. Schlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Leithner, R.; Ehlers, C.

    2001-12-01

    State of Research: The Pressurized Pulverized Coal Combustion Combined Cycle (PPCCCC) with a directly fired gas turbine can reach electrical efficiencies beyond 50%. The required gas quality upstream the gas turbine has not been reached yet at temperatures above 1000 C. One approach tested is the precipitation of ash and alkalines at temperatures above the ash melting point. This principle contains problems concerning the remaining content of ash and alkalines in the flue gas and damages to the refractory materials due to corrosion. Goal of the Investigation: An alternative process had to be investigated in which the flue gas is cleaned according to the state of the art, i.e. below the ash fusion temperature. This principle requires cooling down the flue gas and heating it up again after cleaning in a high temperature heat exchanger. Method: A ceramic tube-and-shell heat exchanger in a model scale was designed and was operated at realistic conditions in an atmospheric test plant in connection with a high temperture precipitation. Result: The heat exchanger showed a good performance concerning design and material. The expected temperatures were not reached totally because of untight joints. Clogging occurred in the tube entrances at high temperatures because of sintered ash agglomerates. First tests to clean the entrances during operation showed positive results. The ash precipitation by means of a cyclone and ceramic filter candles was performed without difficulties. Conclusion: Avoiding and improving joints will help to achieve higher temperatures. A process of cleaning the tubes in-line has to be introduced to prevent the clogging effects. If this is successfully done for high temperatures, an attractive principle for a PPCCCC-process is available which reaches the gas purity required. (orig.) [German] Derzeitiger Stand der Forschung: Der Kohlenstaubdruckfeuerungs-Kombiprozess mit direkt befeuerter Gasturbine verspricht elektrische Wirkungsgrade ueber 50%. Die

  20. 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)

  1. 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)

  2. 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)

  3. 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

  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. Melt processed crystalline ceramic waste forms for advanced nuclear fuel cycles: CRP T21027 1813: Processing technologies for high level waste, formulation of matrices and characterization of waste forms, Task 17208: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Amoroso, J. W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Marra, J. C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-08-26

    A multi-phase ceramic waste form is being developed at the Savannah River National Laboratory (SRNL) for treatment of secondary waste streams generated by reprocessing commercial spent nuclear. The envisioned waste stream contains a mixture of transition, alkali, alkaline earth, and lanthanide metals. Ceramic waste forms are tailored (engineered) to incorporate waste components as part of their crystal structure based on knowledge from naturally found minerals containing radioactive and non-radioactive species similar to the radionuclides of concern in wastes from fuel reprocessing. The ability to tailor ceramics to mimic naturally occurring crystals substantiates the long term stability of such crystals (ceramics) over geologic timescales of interest for nuclear waste immobilization [1]. A durable multi-phase ceramic waste form tailored to incorporate all the waste components has the potential to broaden the available disposal options and thus minimize the storage and disposal costs associated with aqueous reprocessing. This report summarizes results from three years of work on the IAEA Coordinated Research Project on “Processing technologies for high level waste, formulation of matrices and characterization of waste forms” (T21027), and specific task “Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles” (17208).

  7. Melt processed crystalline ceramic waste forms for advanced nuclear fuel cycles: CRP T21027 1813: Processing technologies for high level waste, formulation of matrices and characterization of waste forms, task 17208: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Amoroso, J. W. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Marra, J. C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-08-26

    A multi-phase ceramic waste form is being developed at the Savannah River National Laboratory (SRNL) for treatment of secondary waste streams generated by reprocessing commercial spent nuclear. The envisioned waste stream contains a mixture of transition, alkali, alkaline earth, and lanthanide metals. Ceramic waste forms are tailored (engineered) to incorporate waste components as part of their crystal structure based on knowledge from naturally found minerals containing radioactive and non-radioactive species similar to the radionuclides of concern in wastes from fuel reprocessing. The ability to tailor ceramics to mimic naturally occurring crystals substantiates the long term stability of such crystals (ceramics) over geologic timescales of interest for nuclear waste immobilization [1]. A durable multi-phase ceramic waste form tailored to incorporate all the waste components has the potential to broaden the available disposal options and thus minimize the storage and disposal costs associated with aqueous reprocessing. This report summarizes results from three years of work on the IAEA Coordinated Research Project on “Processing technologies for high level waste, formulation of matrices and characterization of waste forms” (T21027), and specific task “Melt Processed Crystalline Ceramic Waste Forms for Advanced Nuclear Fuel Cycles” (17208).

  8. Properties and Clinical Application of Three Types of Dental Glass-Ceramics and Ceramics for CAD-CAM Technologies

    Science.gov (United States)

    Ritzberger, Christian; Apel, Elke; Höland, Wolfram; Peschke, Arnd; Rheinberger, Volker M.

    2010-01-01

    The main properties (mechanical, thermal and chemical) and clinical application for dental restoration are demonstrated for three types of glass-ceramics and sintered polycrystalline ceramic produced by Ivoclar Vivadent AG. Two types of glass-ceramics are derived from the leucite-type and the lithium disilicate-type. The third type of dental materials represents a ZrO2 ceramic. CAD/CAM technology is a procedure to manufacture dental ceramic restoration. Leucite-type glass-ceramics demonstrate high translucency, preferable optical/mechanical properties and an application as dental inlays, onlays and crowns. Based on an improvement of the mechanical parameters, specially the strength and toughness, the lithium disilicate glass-ceramics are used as crowns; applying a procedure to machine an intermediate product and producing the final glass-ceramic by an additional heat treatment. Small dental bridges of lithium disilicate glass-ceramic were fabricated using a molding technology. ZrO2 ceramics show high toughness and strength and were veneered with fluoroapatite glass-ceramic. Machining is possible with a porous intermediate product.

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Reinforcements for high temperature ceramics. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kyriacou, C.I.; Sepulveda, J.L.; Watson, M.A. [Keramont Corp., Tucson, AZ (United States)

    1992-04-01

    A method has been investigated and developed to grow TiB{sub 2} whiskers by the VLS mechanism. The reaction was carried out in a quartz tube 3 in. in diameter, 30 in. long at about 1150{degrees}C in the presence of a catalyst. The basic experimental parameters, a substrate, and a catalyst, for the growth of the whiskers have been defined. The whiskers produced have shown variable size and morphology depending on the experimental conditions, and location of the whiskers from the input port. The corrosion of the catalyst by the gas environment, and the gas distribution profile in the furnace had a serious effect on the reproducibility of the experimental results, and the overall yield of whiskers.

  16. 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.

  17. 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

  18. 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 ...

  19. 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)

  20. [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.

  1. 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)

  2. 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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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)

  8. 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.

  9. 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

  10. 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.

  11. Final/Progress Report for Instrumentation Grant

    International Nuclear Information System (INIS)

    None

    1997-01-01

    The major piece of equipment was a Furnace Model 1000 used during the Nitrate to Ammonia and Ceramic (NAC) process to sinter the ceramic final product. NAC is a new technology to immobilize liquid radioactive waste simulants. The grant also funded related control and measuring equipment

  12. 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.

  13. 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.

  14. 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.

  15. Ceramics radiation effects issues for ITER

    International Nuclear Information System (INIS)

    Zinkle, S.J.

    1993-01-01

    The key radiation effects issues associated with the successful operation of ceramic materials in components of the planned International Thermonuclear Experimental Reactor (ITER) are discussed. Radiation-induced volume changes and degradation of the mechanical properties should not be a serious issue for the fluences planned for ITER. On the other hand, radiation-induced electrical degradation effects may severely limit the allowable exposure of ceramic insulators. Degradation of the loss tangent and thermal conductivity may also restrict the location of some components such as ICRH feedthrough insulators to positions far away from the first wall. In-situ measurements suggest that the degradation of physical properties in ceramics during irradiation is greater than that measured in postirradiation tests. Additional in-situ data during neutron irradiation are needed before engineering designs for ITER can be finalized

  16. 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)

  17. 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

  18. Manufacture of a ceramic paper for art applications

    Science.gov (United States)

    Dölle, K.; Honig, A.; Piatkowski, J.; Kuempel, C.

    2018-01-01

    Ceramic paper products are mostly used as high temperature ceramic insulation products. They offer an effective solution for most demanding heat management and insulation applications. The objective for this research project was to create a ceramic paper like product that combines the advantages of paper fibers, ceramic filler, and a clay product into one product, which can be produced on a continuous base with a paper machine. The produced ceramic paper product had a ceramic filler level between 59.68% and 78.8% with a basis weight between 322.9 g/m² and 693.7 g/m², and a final moisture content of 58.6% to 44.7% respectively. The wooden fiber served as a support medium for the ceramic filler material during production on the paper machine and during the conversion process into art pieces. During firing in a kiln, the fiber material combusted and the ceramic filler material mixture acts as common pottery clay, holding the desired shape of the art pieces produced.

  19. Sol-gel applications for ceramic membrane preparation

    Science.gov (United States)

    Erdem, I.

    2017-02-01

    Ceramic membranes possessing superior properties compared to polymeric membranes are more durable under severe working conditions and therefore their service life is longer. The ceramic membranes are composed of some layers. The support is the layer composed of coarser ceramic structure and responsible for mechanical durability under filtration pressure and it is prepared by consolidation of ceramic powders. The top layer is composed of a finer ceramic micro-structure mainly responsible for the separation of components present in the fluid to be filtered and sol-gel method is a versatile tool to prepare such a tailor-made ceramic filtration structure with finer pores. Depending on the type of filtration (e.g. micro-filtration, ultra-filtration, nano-filtration) aiming separation of components with different sizes, sols with different particulate sizes should be prepared and consolidated with varying precursors and preparation conditions. The coating of sol on the support layer and heat treatment application to have a stable ceramic micro-structure are also important steps determining the final properties of the top layer. Sol-gel method with various controllable parameters (e.g. precursor type, sol formation kinetics, heat treatment conditions) is a practical tool for the preparation of top layers of ceramic composite membranes with desired physicochemical properties.

  20. Comparative characterization of a novel cad-cam polymer-infiltrated-ceramic-network.

    Science.gov (United States)

    Albero, Alberto; Pascual, Agustín; Camps, Isabel; Grau-Benitez, María

    2015-10-01

    The field of dental ceramics for CAD-CAM is enriched with a new innovative material composition having a porous three-dimensional structure of feldspathic ceramic infiltrated with acrylic resins.The aim of this study is to determine the mechanical properties of Polymer-Infiltrated-Ceramic-Network (PICN) and compare its performance with other ceramics and a nano-ceramic resin available for CAD-CAM systems. In this study a total of five different materials for CAD-CAM were investigated. A polymer-infiltrated ceramic (Vita Enamic), a nano-ceramic resin (Lava Ultimate), a feldspathic ceramic (Mark II), a lithium disilicate ceramic (IPS-e max CAD) and finally a Leucite based ceramic (Empress - CAD). From CAD-CAM blocks, 120 bars (30 for each material cited above) were cut to measure the flexural strength with a three-point-bending test. Strain at failure, fracture stress and Weibull modulus was calculated. Vickers hardness of each material was also measured. IPS-EMAX presents mechanical properties significantly better from the other materials studied. Its strain at failure, flexural strength and hardness exhibited significantly higher values in comparison with the others. VITA ENAMIC and LAVA ULTIMATE stand out as the next most resistant materials. The flexural strength, elastic modulus similar to a tooth as well as having less hardness than ceramics make PICN materials an option to consider as a restorative material. Ceramic infiltrated with resin, CAD-CAM, Weibull modulus, flexural strength, micro hardness.

  1. Sol-gel coatings of ceramic fibres for composites with ceramic matrix

    International Nuclear Information System (INIS)

    Maier, B.; Grathwohl, G.; Spallek, M.; Pannhorst, W.

    1992-01-01

    The aim of this work was to show the feasibility in principle of sol-gel coating of ceramic reinforcement components for composites from technical aspects as well. The complexity of the coating task rises with the transition from individual fibres to bundles of fibres of different thickness to weaves, and finally to composites. (orig.) [de

  2. 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

  3. 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.

  4. 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

  5. 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 ...

  6. 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.

  7. 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.)

  8. 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...

  9. 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

  10. 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.

  11. Bioactive and inert dental glass-ceramics.

    Science.gov (United States)

    Montazerian, Maziar; Zanotto, Edgar Dutra

    2017-02-01

    The global market for dental materials is predicted to exceed 10 billion dollars by 2020. The main drivers for this growth are easing the workflow of dentists and increasing the comfort of patients. Therefore, remarkable research projects have been conducted and are currently underway to develop improved or new dental materials with enhanced properties or that can be processed using advanced technologies, such as CAD/CAM or 3D printing. Among these materials, zirconia, glass or polymer-infiltrated ceramics, and glass-ceramics (GCs) are of great importance. Dental glass-ceramics are highly attractive because they are easy to process and have outstanding esthetics, translucency, low thermal conductivity, high strength, chemical durability, biocompatibility, wear resistance, and hardness similar to that of natural teeth, and, in certain cases, these materials are bioactive. In this review article, we divide dental GCs into the following two groups: restorative and bioactive. Most restorative dental glass-ceramics (RDGCs) are inert and biocompatible and are used in the restoration and reconstruction of teeth. Bioactive dental glass-ceramics (BDGCs) display bone-bonding ability and stimulate positive biological reactions at the material/tissue interface. BDGCs are suggested for dentin hypersensitivity treatment, implant coating, bone regeneration and periodontal therapy. Throughout this paper, we elaborate on the history, processing, properties and applications of RDGCs and BDGCs. We also report on selected papers that address promising types of dental glass-ceramics. Finally, we include trends and guidance on relevant open issues and research possibilities. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 619-639, 2017. © 2016 Wiley Periodicals, Inc.

  12. 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

  13. 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.

  14. 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.

  15. 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.

  16. 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.

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

    Science.gov (United States)

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

    2012-01-10

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

  18. Mid-term results of the BIOLOX delta ceramic-on-ceramic total hip arthroplasty.

    Science.gov (United States)

    Lee, Y K; Ha, Y C; Yoo, J-I; Jo, W L; Kim, K-C; Koo, K H

    2017-06-01

    We conducted a prospective study of a delta ceramic total hip arthroplasty (THA) to determine the rate of ceramic fracture, to characterise post-operative noise, and to evaluate the mid-term results and survivorship. Between March 2009 and March 2011, 274 patients (310 hips) underwent cementless THA using a delta ceramic femoral head and liner. At each follow-up, clinical and radiological outcomes were recorded. A Kaplan-Meier analysis was undertaken to estimate survival. Four patients (four hips) died and 18 patients (20 hips) were lost to follow-up within five years. The remaining 252 patients (286 hips) were followed for a mean of 66.5 months (60 to 84). There were 144 men (166 hips) and 108 women (120 hips) with a mean age of 49.7 years (16 to 83) at surgery. The mean pre-operative Harris Hip Score of 47.1 points improved to 93.8 points at final follow-up. Six patients reported squeaking in seven hips; however, none were audible. Radiolucent lines involving Gruen zones one and/or seven were seen in 52 hips (18.2%). No hip had detectable wear, focal osteolysis or signs of loosening. One hip was revised because of fracture of the ceramic liner, which occurred due to an undetected malseating of the ceramic liner at the time of surgery. One hip was revised for a periprosthetic fracture of the femur, and one hip was treated for periprosthetic joint infection. The six-year survivorship with re-operation for any reason as the endpoint was 99.0% (95% confidence interval 97.8% to 100%). The rate of delta ceramic fracture was 0.3% (one of 286). While ceramic head fracture was dominant in previous ceramic-on-ceramic THA, fracture of the delta ceramic liner due to malseating is a concern. Cite this article: Bone Joint J 2017;99-B:741-8. ©2017 The British Editorial Society of Bone & Joint Surgery.

  19. [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.

  20. Preparation of novel ceramics with high CaO content from steel slag

    International Nuclear Information System (INIS)

    Zhao, Lihua; Li, Yu; Zhou, Yuanyuan; Cang, Daqiang

    2014-01-01

    Highlights: • Efficiently utilize such solid waste with high CaO content. • A novel ceramics was put forward by traditional ceramic process. • The novel ceramics attained high strength. • Sintering mechanisms of the novel ceramics were discussed. - Abstract: Steel slag, an industrial waste discharged from steelmaking process, cannot be extensively used in traditional aluminosilicate based ceramics manufacturing for its high content of calcium oxide. In order to efficiently utilize such solid waste, a method of preparing ceramics with high CaO content was put forward. In this paper, steel slag in combination with quartz, talcum, clay and feldspar was converted to a novel ceramic by traditional ceramic process. The sintering mechanism, microstructure and performances were studied by scanning electron microscope (SEM), X-ray diffraction (XRD) techniques, combined experimenting of linear shrinkage, water absorption and flexural strength. The results revealed that all crystal phases in the novel ceramic were pyroxene group minerals, including diopsite ferrian, augite and diopsite. Almost all raw materials including quartz joined the reaction and transformed into pyroxene or glass phase in the sintering process, and different kinds of clays and feldspars had no impact on the final crystal phases. Flexural strength of the ceramic containing 40 wt.% steel slag in raw materials can reach 143 MPa at sintering temperature of 1210 °C and its corresponding water absorption, weight loss, linear shrinkage were 0.02%, 8.8%, 6.0% respectively. Pyroxene group minerals in ceramics would contribute to the excellent physical and mechanical properties

  1. 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

  2. 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

  3. Influência de defeitos e diferentes processos de fabricação nas propriedades mecânicas finais de cerâmicas Influence of defects and different processes of manufacture on the final mechanical properties of ceramics

    Directory of Open Access Journals (Sweden)

    D. Schuller

    2008-12-01

    Full Text Available Os materiais cerâmicos são atualmente cada vez utilizados como opção na engenharia mundial. Por se tratar de materiais com alta resistência mecânica, possuem muitas aplicações em diversas áreas, como por exemplo a de mancais, a automotiva (sensores, isoladores, catalisadores, pistões, válvulas, revestimentos, a de implantes biocompatíveis (dentário, substituição óssea, válvulas cardíacas, a de produtos sujeitos ao desgaste (guias, a de refratários (revestimento de equipamento bélico, componentes de fornos, a eletrônica, e outras. Nos processos de fabricação da cerâmica há uma gama de fatores que contribuem para as características do produto final. Devido a isso, muitos pesquisadores têm trabalhado no estudo da influência de determinados defeitos e técnicas de produção de cerâmicas nas características do produto final. Este trabalho tem como objetivo fazer uma revisão bibliográfica de recentes artigos que analisam a influência de fatores como velocidade de queima, surgimento de trincas, porosidade, fases cristalinas, e tamanho de partículas, nas propriedades mecânicas finais das cerâmicas. Pode-se concluir que é possível aperfeiçoar o processo de fabricação da cerâmica a fim de promover as melhores propriedades mecânicas possíveis, conhecendo-se fatores prejudiciais e métodos adequados para se obter o melhor produto final.Currently, the ceramic materials are widely used as options in the engineering world. Because they are materials with high mechanical strength, they have many applications in several areas like: bearings components, automotive (sensors, insulators, catalysts, pistons, valves, coatings, biocompatible implants (dental, replacement bone, heart valves, products subject to wear (guides, refractories (coating of military equipment, components of ovens, electronics, and others. In ceramic manufacturing there are many factors that contribute to the final features of the product. In this

  4. 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...

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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...

  10. Coating system to permit direct brazing of ceramics

    Science.gov (United States)

    Cadden, Charles H.; Hosking, F. Michael

    2003-01-01

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

  11. Development of small ceramic gas turbines for cogeneration

    International Nuclear Information System (INIS)

    1998-01-01

    Details of the project at NEDO to develop 300 kW ceramic gas turbines with a thermal efficiency of ≥42% at a turbine inlet temperature (TIT) of 1,350 o C. The project is part of the 'New Sunshine Projects' promoted by Japan's Agency of Industrial Science and Technology and the Ministry of International Trade and Industry. So far, a thermal efficiency of 37% at a TIT of 1,280 o C has been achieved by a basic ceramic gas turbine (CGT). Work to develop pilot CGTs to achieve the final target is being carried out alongside research and development of ceramic parts and improved performance of ceramic components for CGTs. One group of engine and ceramic manufacturers is developing a single shaft regenerative cycle CGT (CGT 301) and a second group a double shaft type (CGT 302). The heat-resistant ceramic parts, nitrogen oxide emissions and performance of these two prototypes are outlined and the properties of the ceramic materials used are indicated. Market estimates and economics are noted

  12. Development of ceramics for heavy-duty roller bearings in key sectors of future technologies. Ceramic bearings for turbomolecular pumps in semiconductor industry. Final report; Entwicklung von Hochleistungskeramiken fuer Keramikwaelzlager unter extremen Belastungen in Schluesselbereichen von Zukunftstechnologien. Keramikwaelzlager fuer Turbomolekularpumpen in der Halbleiterindustrie. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Stueber, H.G.; Adamietz, R.; Binninger, M. [and others

    1999-09-01

    The examined ceramic material shows high resistance against aggressive gases used in the semiconductor industry. In the test rigs for emergency bearings the full ceramic bearings without any lubricant didn't reach the requested life. Bearings with ZrO{sub 2}-rings reached higher life time compared to bearings with Si{sub 3}N{sub 4}-rings. The life of the emergency bearings increased when using C-ion implanted rings. By using this method the friction ratio decreased. In this case, bearings with ZrO{sub 2}-rings get nearly the life of the old standard hybrid emergency bearings. But they can't reach the life time of the latest state of development of hybrid bearings. A two row paired angular contact bearing seems to be a most promising modification. But this design shows problems while manufacturing. The so called pin-bush-bearing (a sliding friction bearing solution) shows good test results. It will be possible to optimise this bearing for different pumps. Tests with ceramic bearings in a conventional levitated pump were planned. It was not possible to start the tests because of the higher priority of the 'emergency bearing project'. (orig.) [German] Der untersuchte keramische Werkstoff weist eine hohe Bestaendigkeit gegenueber den in der Halbleiterindustrie verwendeten aggressiven Gasen auf. In den Fanglagerversuchen wurde deutlich, dass die untersuchten Vollkeramik-Waelzlager ohne Schmierstoff nicht die geforderten Standzeiten erreichen. Im Vergleich zwischen Si{sub 3}N{sub 4}-Ringen zur ZrO{sub 2}-Ringen lassen die Oxidringe eine hoehere Lebensdauer erwarten. Eine Verbesserung der Standzeiten konnte durch mit C-Ionen implantierten Ringe erzielt werden. Mit dieser Reibwertverbesserung konnten die Lager mit ZrO{sub 2}-Ringen zwar den alten Serienstandard mit Hybridlagern in etwa erreichen, andererseits sind zum jetzigen Serienstandard noch deutliche Unterschiede zu beobachten. Eine vielversprechende Modifikation des Lagers in Richtung eines

  13. Anisotropic and Hierarchical Porosity in Multifunctional Ceramics

    Science.gov (United States)

    Lichtner, Aaron Zev

    The performance of multifunctional porous ceramics is often hindered by the seemingly contradictory effects of porosity on both mechanical and non-structural properties and yet a sufficient body of knowledge linking microstructure to these properties does not exist. Using a combination of tailored anisotropic and hierarchical materials, these disparate effects may be reconciled. In this project, a systematic investigation of the processing, characterization and properties of anisotropic and isotropic hierarchically porous ceramics was conducted. The system chosen was a composite ceramic intended as the cathode for a solid oxide fuel cell (SOFC). Comprehensive processing investigations led to the development of approaches to make hierarchical, anisotropic porous microstructures using directional freeze-casting of well dispersed slurries. The effect of all the important processing parameters was investigated. This resulted in an ability to tailor and control the important microstructural features including the scale of the microstructure, the macropore size and total porosity. Comparable isotropic porous ceramics were also processed using fugitive pore formers. A suite of characterization techniques including x-ray tomography and 3-D sectional scanning electron micrographs (FIB-SEM) was used to characterize and quantify the green and partially sintered microstructures. The effect of sintering temperature on the microstructure was quantified and discrete element simulations (DEM) were used to explain the experimental observations. Finally, the comprehensive mechanical properties, at room temperature, were investigated, experimentally and using DEM, for the different microstructures.

  14. 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

  15. 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.

  16. 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).

  17. Dolomite addition effects on the thermal expansion of ceramic tiles

    International Nuclear Information System (INIS)

    Marino, Luis Fernando Bruno; Boschi, Anselmo Ortega

    1997-01-01

    The thermal expansion of ceramic tiles is of greater importance in engineering applications because the ceramics are relatively brittle and cannot tolerate large internal strain imposed by thermal expansion. When ceramic bodies are produced for glazed ties the compatibility of this property of the components should be considered to avoid damage in the final products. Carbonates are an important constituent of ceramic wall-title bodies and its presence in formulations and the reactions that occur between them and other components modify body properties. The influence in expansivity by additions of calcium magnesium carbonate in a composition of wall tile bodies has been investigated. The relative content of mineralogical components was determined by X-ray diffraction and thermal expansion by dilatometric measurements. The results was indicated that with the effect of calcium-magnesium phases and porosity on thermal expansion of wall tile bodies. (author)

  18. Material characteristics and tribolotical characteristics of finished boundary layers of heavy-duty ceramics under tribological load. Final report; Werkstoffmechanische und tribologische Charakterisierung bearbeiteter und tribologisch beanspruchter Randschichten von Hochleistungskeramiken. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Zeller, R.; Pfeiffer, W.; Hollstein, T.

    2000-04-01

    Test pieces of heavy-duty ceramics (SSiC, SiSiC, Si{sub 3}N{sub 4}) were worked by different finishing processes and then analyzed for their material characteristics and tested in sliding and rolling wear tests. It was found that in case of coarse treatment, the influence of strength-increasing intrinsic stresses from finishing may exceed the influence of damage caused by finishing. The same applies to the tribological characteristics of ceramic components in case of preferential mechanical wear on the boundary layer. While polished surfaces of SiC, owing to a lack of microhydrodynamic lubricating effects, have catastrophic adhesive wear in sliding wear tests, fine lapping has advantages especially in the run-in phase. Coarse-lapped surfaces have a less pronounced lubricating effect in the early stages than fine-lapped surfaces, but the high and deep intrinsic stresses with pressure character induced by the finishing process can reduce wear. [German] Die 'Oberflaechenbewertung' wurde im Rahmen des DFG-Schwerpunktprogramms 'Bearbeitungsbedingte Oberflaechenausbildung und tribologische Eigenschaften keramischer Bauteile' innerhalb des Forschungsverbundes 'BOT' (Bearbeitung - Oberflaeche - Tribologie) in Zusammenarbeit mit Projektpartnern durchgefuehrt. Proben aus Hochleistungskeramiken (SSiC, SiSiC, Si{sub 3}N{sub 4}) die von den Projektpartnern mit unterschiedlichen Verfahren (Schleifen, Polieren, Laeppen, Ultraschall-Schwinglaeppen, Funkenerosion und Laserstrahl-Formabtrag) bearbeitet worden waren, wurden im IWM werkstoffmechanisch charakterisiert und im Gleit- bzw. Waelzverschleissversuch geprueft. Die roentgenographische Ermittlung der bearbeitungsbedingten Randschichtveraenderungen und deren Bewertung mittels bruchmechanischer Methoden hat gezeigt, dass bei groben Bearbeitungsverfahren der Einfluss festigkeitssteigernder Bearbeitungs-Eigenspannungen (mit Druckcharakter) den Einfluss bearbeitungsbedingter Schaedigungen ueberwiegen

  19. 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

  20. Production of defect-poor nanostructured ceramics of yttria-zirconia

    NARCIS (Netherlands)

    Sagel-Ransijn, C.D.; Sagel-Ransijn, C.D.; Winnubst, Aloysius J.A.; Kerkwijk, B.; Burggraaf, Anthonie; Burggraaf, A.J.; Verweij, H.

    1997-01-01

    For the production of nanostructured ceramics of yttria-zirconia four powders differing in agglomerate strength, agglomerate size and crystallite size are compared. An ultra-fine-grained ceramic with a final density of 98% and a grain size of 0.18 μm could be produced from a hydrothermally

  1. 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.

  2. 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)

  3. 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)

  4. 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.

  5. 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

  6. 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

  7. 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.

  8. Fabrication and properties of La2-xGdxHf2O7 transparent ceramics

    International Nuclear Information System (INIS)

    Wang, Zhengjuan; Zhou, Guohong; Zhang, Fang; Qin, Xianpeng; Ai, Jianping; Wang, Shiwei

    2016-01-01

    La 2-x Gd x Hf 2 O 7 (x=0–2.0) transparent ceramics were fabricated through vacuum sintering from nano-powders synthesized by a simple combustion method. The phase composition of the powders and final ceramics, the in-line transmittance, microstructures and density of the ceramics were investigated. With the increasing of Gd content, the ceramics maintained the cubic pyrochlore structure, and the lattice parameters decreased, whilst the densities increased linearly. All the ceramics were transparent. The highest in-line transmittance was 76.1% at 800 nm (x=1.2). With high density (7.91–8.88 g/cm 3 ) and effective atomic number, some of the La 2-x Gd x Hf 2 O 7 (x=0–2.0) transparent ceramics are promising candidates for scintillator hosts. - Highlights: • A new series of La 2-x Gd x Hf 2 O 7 transparent ceramics were fabricated by vacuum sintering using combustion-synthesized powders. • All the ceramics are transparent and the in-line transmittance can reach to 76.1% at 800 nm when x=1.2. • The Gd content has effects on the crystal structure, in-line transmittance, microstructures and densities of the ceramics. • With high density (7.91~8.88 g/cm3) and effective atomic number, some of the La2-xGdxHf2O7 transparent ceramics are promising candidates for scintillator hosts.

  9. 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.

  10. 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.

  11. 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.

  12. Ceramic ware waste as coarse aggregate for structural concrete production.

    Science.gov (United States)

    García-González, Julia; Rodríguez-Robles, Desirée; Juan-Valdés, Andrés; Morán-Del Pozo, Julia M; Guerra-Romero, M Ignacio

    2015-01-01

    The manufacture of any kind of product inevitably entails the production of waste. The quantity of waste generated by the ceramic industry, a very important sector in Spain, is between 5% and 8% of the final output and it is therefore necessary to find an effective waste recovery method. The aim of the study reported in the present article was to seek a sustainable means of managing waste from the ceramic industry through the incorporation of this type of waste in the total replacement of conventional aggregate (gravel) used in structural concrete. Having verified that the recycled ceramic aggregates met all the technical requirements imposed by current Spanish legislation, established in the Code on Structural Concrete (EHE-08), then it is prepared a control concrete mix and the recycled concrete mix using 100% recycled ceramic aggregate instead of coarse natural aggregate. The concretes obtained were subjected to the appropriate tests in order to conduct a comparison of their mechanical properties. The results show that the concretes made using ceramic sanitary ware aggregate possessed the same mechanical properties as those made with conventional aggregate. It is therefore possible to conclude that the reuse of recycled ceramic aggregate to produce recycled concrete is a feasible alternative for the sustainable management of this waste.

  13. Synthetic flux as a whitening agent for ceramic tiles

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-12-05

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

  14. The energy efficiency and environmental impacts in the ceramic industry: the case of ceramic coatings segment; A eficiencia energetica e os impactos na industria ceramica: o caso do segmento de revestimentos ceramicos

    Energy Technology Data Exchange (ETDEWEB)

    Berni, Mauro Donizeti [Universidade Estadual de Campinas (NIPE/UNICAMP), SP (Brazil). Nucleo Interdisciplinar de Planejamento Energetico], email: mauro_berni@yahoo.com.br; Bajay, Sergio Valdir [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Mecanica. Dept. de Energia

    2010-07-01

    The Brazilian ceramic industry has great importance for the country, with a stake of more than 1.0% of GDP, or approximately $ 6 billion. The segment of ceramic coatings due to the higher revenues, production, employment, value of manufacturing and penetration in foreign markets, has been the highlight of the ceramic sector. Besides most representative in economic terms, the ceramic coatings segment presents with the largest final energy consumption and volume of emissions. This work shows the evolution of the final energy consumption of the ceramic sector, showing that the segment of ceramic coatings can be successful harnessing of potential energy conservation with reflections on the mitigation of greenhouse gas emissions. Therefore, the study evaluates: the process and energy sources; reducing impacts along the entire life cycle of products and the management actions providing a new corporate culture and social and environmental responsibility.

  15. 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.

  16. 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)

  17. 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.

  18. 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.

  19. 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)

  20. 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

  1. 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.

  2. 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 ...

  3. 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.)

  4. 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

  5. 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.

  6. 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

  7. Preparation of basalt-based glass ceramics

    Directory of Open Access Journals (Sweden)

    MIHOVIL LOGAR

    2003-06-01

    Full Text Available Local and conventional raw materials–massive basalt from the Vrelo locality on Kopaonik mountain–have been used as starting materials to test their suitability for the production of glass-ceramics. Crystallization phenomena of glasses of the fused basalt rocks were studied by X-ray phase analysis, optical microscopy and other techniques. Various heat treatments were used, and their influences, on controlling the microstructures and properties of the products were studied with the aim of developing high strength glass-ceramic materials. Diopside CaMg(SiO32 and hypersthene ((Mg,FeSiO3 were identifies as the crystalline phases. The final products contained considerable amounts of a glassy phase. The crystalline size was in range of 8–480 mm with plate or needle shape. Microhardness, crashing strength and wears resistence of the glass-ceramics ranged from 6.5–7.5, from 2000–6300 kg/cm2 and from 0.1–0.2 g/cm, respectively.

  8. 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.

  9. Compatibility tests between Solar Salt and thermal storage ceramics from inorganic industrial wastes

    International Nuclear Information System (INIS)

    Motte, Fabrice; Falcoz, Quentin; Veron, Emmanuel; Py, Xavier

    2015-01-01

    Highlights: • ESEM and XRD characterizations have been performed. • Compatibility of these ceramics with the conventional binary Solar Salt is tested at 500 °C. • Tested ceramics have relevant properties to store thermal energy up to 1000 °C. • Feasibility of using ceramics as filler materials in thermocline is demonstrated. - Abstract: This paper demonstrates the feasibility of using several post-industrial ceramics as filler materials in a direct thermocline storage configuration. The tested ceramics, coming from several industrial processes (asbestos containing waste treatment, coal fired power plants or metallurgic furnaces) demonstrate relevant properties to store thermal energy by sensible heat up to 1000 °C. Thus, they represent at low-cost a promising, efficient and sustainable approach for thermal energy storage. In the present study, the thermo-chemical compatibility of these ceramics with the conventional binary Solar Salt is tested at medium temperature (500 °C) under steady state. In order to determine the feasibility of using such ceramics as filler material, Environmental Scanning Electron Microscopy (ESEM) and X-Ray Diffraction (XRD) characterizations have been performed to check for their chemical and structural evolution during corrosion tests. The final objective is to develop a molten salt thermocline direct storage system using low-cost shaped ceramic as structured filler material. Most of the tested ceramics present an excellent corrosion resistance in molten Solar Salt and should significantly decrease the current cost of concentrated solar thermal energy storage system

  10. Fluorine 18 in tritium generator ceramic materials

    International Nuclear Information System (INIS)

    Jimenez-Becerril, J.; Bosch, P.; Bulbulian, S.

    1992-01-01

    At present time, the ceramic materials generators of tritium are very interesting mainly by the necessity of to found an adequate product for its application as fusion reactor shielding. The important element that must contain the ceramic material is the lithium and especially the isotope with mass=6. The tritium in these materials is generated by neutron irradiation, however, when the ceramic material contains oxygen, then is generated too fluorine 18 by the action of energetic atoms of tritium in recoil on the 16 O, as it is showed in the next reactions: 1) 6 Li (n, α) 3 H ; 2) 16 O( 3 H, n) 18 F . In the present work was studied the LiAlO 2 and the Li 2 O. The first was prepared in the laboratory and the second was used such as it is commercially expended. In particular the interest of this work is to study the chemical behavior of fluorine-18, since if it would be mixed with tritium it could be contaminate the fusion reactor fuel. The ceramic materials were irradiated with neutrons and also the chemical form of fluorine-18 produced was studied. It was determined the amount of fluorine-18 liberated by the irradiated materials when they were submitted to extraction with helium currents and argon-hydrogen mixtures and also it was investigated the possibility about the fluorine-18 was volatilized then it was mixed so with the tritium. Finally it was founded that the liberated amount of fluorine-18 depends widely of the experimental conditions, such as the temperature and the hydrogen amount in the mixture of dragging gas. (Author)

  11. 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.

  12. STRUCTURAL CHARACTERIZATION OF LITHIUM DOPED NZP Na1

    African Journals Online (AJOL)

    DR. AMIN

    2011-06-01

    Jun 1, 2011 ... belong to the rhombohedral crystal system and were indexed based on hexagonal lattice structure. The density of the ... compounds have special structural features such that .... equation , in comparison with published data.

  13. 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

  14. 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)

  15. 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:

  16. 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:

  17. 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...

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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

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

    Science.gov (United States)

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

    2016-01-01

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

  5. Process and device for forming imprints on ceramic tubes

    International Nuclear Information System (INIS)

    1985-01-01

    The purpose of the present invention is a process and a device for making imprints on ceramic tubes and these ceramic tubes with imprints. It is known that in uranium enrichment processes by gaseous diffusion, microporous tubes are used to made the diffuser units used for the application of this isotope enrichment process. It is known that these microporous tubes are generally made in two stages. In a first stage, a macroporous ceramic tube called a ''support'' is made. In a second stage, an internal microporous deposit is made which makes it possible to obtain a tube called a ''barrier'' finally having the required porosity to apply the gaseous diffusion enrichment process. The present invention involves the first stage of the manufacturing process of the barriers and, more precisely, a step in the manufacturing process of the supports that makes it possible to improve the efficiency of these barriers

  6. Piezoelectric textured ceramics: Effective properties and application to ultrasonic transducers.

    Science.gov (United States)

    Levassort, Franck; Pham Thi, Mai; Hemery, Henry; Marechal, Pierre; Tran-Huu-Hue, Louis-Pascal; Lethiecq, Marc

    2006-12-22

    Piezoelectric textured ceramics obtained by homo-template grain growth (HTGG) were recently demonstrated. A simple model with several assumptions has been used to calculate effective parameters of these new materials. Different connectivities have been simulated to show that spatial arrangements between the considered phases have little influence on the effective parameters, even through the 3-0 connectivity delivers the highest electromechanical thickness factor. A transducer based on a textured ceramic sample has been fabricated and characterised to show the efficiency of these piezoelectric materials. Finally, in a single element transducer configuration, simulation shows an improvement of 2 dB sensitivity for a transducer made with textured ceramic in comparison with a similar transducer design based on standard soft PZT (at equivalent bandwidths).

  7. Sintering and annealing effects on undoped yttria transparent ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Letue, Laetitia; Petit, Johan, E-mail: johan.petit@onera.fr; Ritti, Marie-Hélène; Lalanne, Sylvie; Landais, Stéphane

    2017-06-15

    Transparent yttrium oxide (Y{sub 2}O{sub 3}) ceramics were processed by several densifications steps without any doping species. The green bodies were obtained by the aqueous way and sintered at high temperature under vacuum and then under high pressure. We studied the effects of different sintering cycles and air annealing at different steps of the process on the density and the grain growth. We also focused on the reaction between yttria ceramics and BN-coated graphite crucible which occurs during HIP. We noted that a low heating rate and two annealing steps are necessary to improve our samples’ transparency. - Highlights: • The quality of transparent ceramics is compared with the tested process parameters. • Air annealing is critical when using a carbon environment in the process. • Intra-granular pores, and so the final transparency, are directly linked to the sintering heating rates.

  8. 76 FR 11275 - In the Matter of Certain Ceramic Capacitors and Products Containing Same; Notice of Commission...

    Science.gov (United States)

    2011-03-01

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-692] In the Matter of Certain Ceramic Capacitors and Products Containing Same; Notice of Commission Determination To Review in Part A Final Initial... importation of certain ceramic capacitors and products containing the same by reason of infringement of...

  9. Nano-ceramics and its molding technologies

    International Nuclear Information System (INIS)

    Liu Jian; Xu Yunshu

    2007-01-01

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

  10. Preparation of 147Pm ceramic source core

    International Nuclear Information System (INIS)

    Mielcarski, M.

    1989-01-01

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

  11. Development of new ceramic materials from the waste of serpentinite and red clay

    International Nuclear Information System (INIS)

    Presotto, P.; Mymrine, V.

    2012-01-01

    The objective of this work is to develop new ceramic materials using serpentine and glass waste and clay red. The raw materials were characterized through morphological, granulometric, mineralogical and chemical analysis. Six formulations have been developed based on the serpentine and red clay, which three of the six compositions have been adjusted with the addition of residual glass. The ceramic bodies were formed by uniaxial pressing and subjected to burn in an electric oven at temperatures of 1100 ° C, 1200 ° C, 1250 ° C and 1300 ° C. The ceramic samples obtained this way were characterized according to their physical properties (specific mass and linear retraction) and the mechanical (three points bending strength). The final properties varied according to the proportions of raw materials and firing temperature. In general, the different formulations fit the standards for traditional ceramics such as tiles and ceramic blocks. (author)

  12. Optimization of the injection molding process for development of high performance calcium oxide -based ceramic cores

    Science.gov (United States)

    Zhou, P. P.; Wu, G. Q.; Tao, Y.; Cheng, X.; Zhao, J. Q.; Nan, H.

    2018-02-01

    The binder composition used for ceramic injection molding plays a crucial role on the final properties of sintered ceramic and to avoid defects on green parts. In this study, the effects of binder compositions on the rheological, microstructures and the mechanical properties of CaO based ceramic cores were investigated. It was found that the optimized formulation for dispersant, solid loading was 1.5 wt% and 84 wt%, respectively. The microstructures, such as porosity, pore size distribution and grain boundary density were closely related to the plasticizer contents. The decrease of plasticizer contents can enhance the strength of the ceramic cores but with decreased shrinkage. Meanwhile, the creep resistance of ceramic cores was enhanced by decreasing of plasticizer contents. The flexural strength of the core was found to decrease with the increase of the porosity, the improvement of creep resistance is closely related to the decrease of porosity and grain boundary density.

  13. Modeling of thermal explosion under pressure in metal ceramic systems

    International Nuclear Information System (INIS)

    Shapiro, M.; Dudko, V.; Skachek, B.; Matvienko, A.; Gotman, I.; Gutmanas, E.Y.

    1998-01-01

    The process of reactive in situ synthesis of dense ceramic matrix composites in Ti-B-C, Ti-B-N, Ti-Si-N systems is modeled. These ceramics are fabricated on the basis of compacted blends of ceramic powders, namely Ti-B 4 C and/or Ti-BN. The objectives of the project are to identify and investigate the optimal thermal conditions preferable for production of fully dense ceramic matrix composites. Towards this goal heat transfer and combustion in dense and porous ceramic blends are investigated during monotonous heating at a constant rate. This process is modeled using a heat transfer-combustion model with kinetic parameters determined from the differential thermal analysis of the experimental data. The kinetic burning parameters and the model developed are further used to describe the thermal explosion synthesis in a restrained die under pressure. It is shown that heat removal from the reaction zone affects the combustion process and the final phase composition

  14. Ceramic/polymer functionally graded material (FGM) lightweight armor system

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, J.J.; McClellan, K.J.

    1998-12-31

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Functionally graded material is an enabling technology for lightweight body armor improvements. The objective was to demonstrate the ability to produce functionally graded ceramic-polymer and ceramic-metal lightweight armor materials. This objective involved two aspects. The first and key aspect was the development of graded-porosity boron-carbide ceramic microstructures. The second aspect was the development of techniques for liquid infiltration of lightweight metals and polymers into the graded-porosity ceramic. The authors were successful in synthesizing boron-carbide ceramic microstructures with graded porosity. These graded-porosity boron-carbide hot-pressed pieces were then successfully liquid-infiltrated in vacuum with molten aluminum at 1,300 C, and with liquid polymers at room temperature. Thus, they were able to demonstrate the feasibility of producing boron carbide-aluminum and boron carbide-polymer functionally graded materials.

  15. LSA glass-ceramic tiles made by powder pressing

    International Nuclear Information System (INIS)

    Figueira, F.C.; Bertan, F.M.; Riella, H.G.; Uggioni, E.; Bernardin, A.M.

    2009-01-01

    A low cost alternative for the production of glass-ceramic materials is the pressing of the matrix glass powders and its consolidation simultaneously with crystallization in a single stage of sintering. The main objective of this work was to obtain LSA glass ceramics with low thermal expansion, processed by pressing and sintering a ceramic frit powder. The raw materials were homogenized and melted (1480 deg C, 80min), and the melt was poured in water. The glass was chemically (XRF and AAS) and thermally (DTA, 10 deg C/min, air) characterized, and then ground (60min and 120min). The ground powders were characterized (laser diffraction) and compressed (35MPa and 45MPa), thus forming four systems. The compacts were dried (150 deg C, 24h) and sintered (1175 deg C and 1185 deg C, 10 deg C/min). Finally, the glass-ceramics were characterized by microstructural analysis (SEM and XRD), mechanical behavior (σbending) and thermal analysis (α). The best results for thermal expansion were those for the glass-ceramics processed with smaller particle size and greater compaction pressure. (author)

  16. 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

  17. 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.

  18. Survival of all-ceramic restorations after a minimum follow-up of five years: A systematic review.

    Science.gov (United States)

    Araujo, Nara Santos; Moda, Mariana Dias; Silva, Ebele Adaobi; Zavanelli, Adriana Cristina; Mazaro, José Vitor Quinelli; Pellizzer, Eduardo Piza

    2016-01-01

    The purpose of this systematic review was to compare the survival and complication rates of all-ceramic restorations after a minimum follow-up time of 5 years. A comprehensive search of studies published from 2005 to November 2015 and listed in the PubMed/MEDLINE, Scopus, and Cochrane Library databases was performed in accordance with the PRISMA statement. Two reviewers independently analyzed the abstracts. Relevant studies were selected according to predetermined inclusion criteria. Twenty-nine studies were selected for the final analysis from an initial yield of 514. Only four studies fulfilled the requirement of having a randomized design, and 25 studies were prospective with a mean follow-up period of 5 to 16 years. Overall, the 5-year complication rates were low. The most frequent complications were secondary caries, endodontic problems, ceramic fractures, ceramic chipping, and loss of retention. This systematic review showed that all-ceramic restorations fabricated using the correct clinical protocol have an adequate clinical survival for at least 5 years of clinical service with very low complication rates. Minor ceramic chipping and debonding did not affect the longevity of the restorations. Long-term clinical performance of all-ceramic restorations manufactured using various ceramic systems provides clinical evidence of complications and long-term management of these restorations. Available evidence indicates the effectiveness of many ceramic systems for numerous clinical applications. Correct planning and a rigorous technical execution protocol increase clinical success. Studies of ceramic prostheses indicate more problems with ceramic failure and debonding.

  19. 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.

  20. 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...

  1. 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

  2. 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

  3. Sintered ceramics having controlled density and porosity

    International Nuclear Information System (INIS)

    Brassfield, H.C.; DeHollander, W.R.; Nivas, Y.

    1980-01-01

    A new method was developed for sintering ceramic uranium dioxide powders, in which ammonium oxalate is admixed with the powder prior to being pressed into a cylindrical green body, so that the end-point density of the final nuclear-reactor fuel product can be controlled. When the green body is heated, the ammonium oxalate decomposes and leaves discrete porosity in the sintered body, which corresponds to the ammonium oxalate regions in the green body. Thus the end-point density of the sintered body is a function of the amount of ammonium oxalate added. The final density of the sintered product is about 90-97% of the theoretical. The addition of ammonium oxalate also allows control of the pore size and distribution throughout the fuel. The process leaves substantially no impurities in the sintered strucuture. (DN)

  4. Fabrication and testing of ceramic UO{sub 2} fuel - I-III. Part II, Fabrication of sintered pressed samples UO{sub 2} (Final report); Izrada i ispitivanje keramickog goriva na bazi UO{sub 2}- I-III, II Deo - Dobijanje sinterovanih ispresaka UO{sub 2} (zavrsni izvestaj)

    Energy Technology Data Exchange (ETDEWEB)

    Novakovic, M; Ristic, M M [Institute of Nuclear Sciences Boris Kidric, Laboratorija za termotehniku reaktora, Vinca, Beograd (Serbia and Montenegro)

    1961-12-15

    Procedure for fabrication of sintered ceramic UO{sub 2} pellets was developed in the Department of reactor materials. The tasks described in this report deal with design and construction of laboratory equipment for treatment of ceramic materials, and fabrication of UO{sub 2} pellets. The procedure was based on cold pressing of appropriately prepared powder and sintering of the of thus obtained pressed samples.

  5. Ceramic matrix composites -- Advanced high-temperature structural materials

    International Nuclear Information System (INIS)

    Lowden, R.A.; Ferber, M.K.; DiPietro, S.G.

    1995-01-01

    This symposium on Ceramic Matrix Composites: Advanced High-Temperature Structural Materials was held at the 1994 MRS Fall Meeting in Boston, Massachusetts on November 28--December 2. The symposium was sponsored by the Department of Energy's Office of Industrial Technology's Continuous Fiber Ceramic Composites Program, the Air Force Office of Scientific Research, and NASA Lewis Research Center. Among the competing materials for advanced, high-temperature applications, ceramic matrix composites are leading candidates. The symposium was organized such that papers concerning constituents--fibers and matrices--were presented first, followed by composite processing, modeling of mechanical behavior, and thermomechanical testing. More stable reinforcements are necessary to enhance the performance and life of fiber-reinforced ceramic composites, and to ensure final acceptance of these materials for high-temperature applications. Encouraging results in the areas of polymer-derived SiC fibers and single crystal oxide filaments were given, suggesting composites with improved thermomechanical properties and stability will be realized in the near future. The significance of the fiber-matrix interface in the design and performance of these materials is evident. Numerous mechanical models to relate interface properties to composite behavior, and interpret test methods and data, were enthusiastically discussed. One issue of great concern for any advanced material for use in extreme environments is stability. This theme arose frequently throughout the symposium and was the topic of focus on the final day. Fifty nine papers have been processed separately for inclusion on the data base

  6. 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.

  7. 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.

  8. 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

  9. Innovative grinding wheel design for cost-effective machining of advanced ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Licht, R.H.; Kuo, P.; Liu, S.; Murphy, D.; Picone, J.W.; Ramanath, S.

    2000-05-01

    This Final Report covers the Phase II Innovative Grinding Wheel (IGW) program in which Norton Company successfully developed a novel grinding wheel for cost-effective cylindrical grinding of advanced ceramics. In 1995, Norton Company successfully completed the 16-month Phase I technical effort to define requirements, design, develop, and evaluate a next-generation grinding wheel for cost-effective cylindrical grinding of advanced ceramics using small prototype wheels. The Phase II program was initiated to scale-up the new superabrasive wheel specification to larger diameters, 305-mm to 406-mm, required for most production grinding of cylindrical ceramic parts, and to perform in-house and independent validation grinding tests.

  10. Stabilization of low-level mixed waste in chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A.S.; Singh, D.; Sarkar, A.V.

    1994-06-01

    Mixed waste streams, which contain both chemical and radioactive wastes, are one of the important categories of DOE waste streams needing stabilization for final disposal. Recent studies have shown that chemically bonded phosphate ceramics may have the potential for stabilizing these waste streams, particularly those containing volatiles and pyrophorics. Such waste streams cannot be stabilized by conventional thermal treatment methods such as vitrification. Phosphate ceramics may be fabricated at room temperature into durable, hard and dense materials. For this reason room-temperature-setting phosphate ceramic waste forms are being developed to stabilize these to ''problem waste streams.''

  11. Development of ceramic composites from mixture of alumina and ceramic precursor polymer poly (silsesquioxane))

    International Nuclear Information System (INIS)

    Machado, Glauson Aparecido Ferreira

    2009-01-01

    Processing of ceramics materials, by polymer precursors pyrolysis, has been intensively researched over the past decades, due to advantages that this path provides, such as: lower temperature process compared to conventional techniques; structure control at molecular level; synthesis possibility of a wide range of ceramic compounds; obtaining parts with dimensions of the final product etc. The active filler controlled polymer pyrolysis (AFCOP) process, enables the synthesis of ceramic composites, by reaction between added filler (oxides, metals, intermetallic etc.) and solid and gaseous products, from polymer decomposition. In this study, based on this process, samples of alumina, with addition of 10 and 20 mass% of poly silsesquioxane polymer precursor, were manufactured. These samples were pyrolyzed at 900 degree C and thermal treated at temperatures of 1100, 1300 and 1500 degree C. The samples were characterized for bulk density, porosity and hardness, after each stage of thermal treatment. Structural transformations were analyzed by X-ray diffraction, scanning electron microscopy and infrared spectroscopy. Samples treated until 1300 degree C resulted in composites of alumina and silicon oxycarbide, while those treated at 1500 degree C, formed composites of mullite and alumina. The samples with 20% of polymer added started to density around 800 degree C and high retraction rate was observed at 1400 degree C. (author)

  12. 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.)

  13. 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

  14. 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...

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. 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)

  2. 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.

  3. 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.

  4. 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...

  5. Lithium ceramics: sol-gel preparation and tritium release

    International Nuclear Information System (INIS)

    Renoult, O.

    1994-04-01

    Ceramics based on lithium aluminate (LiA1O 2 ), lithium zirconate (Li 2 ZrO 3 ) and lithium titanate (Li 2 TiO 3 ) are candidates as tritium breeder blanket materials for forthcoming nuclear fusion reactors. Lithium silico-aluminate Li 4+x A1 4-3x Si 2x O 8 (0 ≤ x ≤ 0,25) powders were synthetized from alkoxyde-hydroxyde sol-gel route. By direct sintering at 850-1100 deg C (without prior calcination), ceramics with controlled stoichiometry and homogenous microstructure were obtained. We have also prepared, using a comparable method, Li 2 Zr 1-x Ti x O 3 (x = 0, x = 0,1 et x = 1) materials. All these ceramics, with different microstructures and compositions, have been tested in out-of-reactor experiments. Concerning lithium aluminate microporous ceramics, the silicon substitution leads to a significant improvement of the tritrium release. Classical models taking into account independent surface mechanisms are not able to describe correctly the observed tritium release kinetics. We show, using a simple model, that the release kinetics is in fact limited by an intergranular diffusion followed by a desorption. The delay in tritium release, which occurs when the ceramic compacity increases, is explained in terms of an enhancement of the ionic T + diffusion path length. The energy required for desorption includes a leading term independent of hydrogen contained in the sweep gas. This term is attributed to the limiting recombination step of T + in molecular species HTO. For similar microstructures, the facility of tritium release for the different studied materials is explained by three properties: the crystal structure of the ceramic, the acidity of oxides and finally the presence of electronic non-stoichiometric defects. (author). 89 refs., 50 figs., 2 tabs., 1 annexe

  6. 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

  7. 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)

  8. 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

  9. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants

    Energy Technology Data Exchange (ETDEWEB)

    Gryshkov, Oleksandr, E-mail: gryshkov@imp.uni-hannover.de [Institute for Multiphase Processes, Leibniz Universität Hannover, 30167 Hannover (Germany); Klyui, Nickolai I., E-mail: klyuini@ukr.net [College of Physics, Jilin University, 130012 Changchun (China); V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Temchenko, Volodymyr P., E-mail: tvp@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Kyselov, Vitalii S., E-mail: kyselov@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Chatterjee, Anamika, E-mail: chatterjee@imp.uni-hannover.de [Institute for Multiphase Processes, Leibniz Universität Hannover, 30167 Hannover (Germany); Belyaev, Alexander E., E-mail: belyaev@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Lauterboeck, Lothar, E-mail: lauterboeck@imp.uni-hannover.de [Institute for Multiphase Processes, Leibniz Universität Hannover, 30167 Hannover (Germany); Iarmolenko, Dmytro, E-mail: iarmolenko.dmytro@isp.kiev.ua [V. Lashkaryov Institute of Semiconductor Physics, National Academy of Science of Ukraine, 03028 Kyiv (Ukraine); Glasmacher, Birgit, E-mail: glasmacher@imp.uni-hannover.de [Institute for Multiphase Processes, Leibniz Universität Hannover, 30167 Hannover (Germany)

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO{sub 2}) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO{sub 2} using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO{sub 2} to the initial HA powder resulted in significant decomposition of the final HA/ZrO{sub 2} coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO{sub 2} coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. - Highlights: • Synthesis and characterization of porous biomorphic SiC ceramics derived from wood • Successful deposition of bioactive calcium phosphate coatings using gas detonation deposition • Porosity and pore size of Si

  10. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants

    International Nuclear Information System (INIS)

    Gryshkov, Oleksandr; Klyui, Nickolai I.; Temchenko, Volodymyr P.; Kyselov, Vitalii S.; Chatterjee, Anamika; Belyaev, Alexander E.; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-01-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO 2 ) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO 2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO 2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO 2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO 2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. - Highlights: • Synthesis and characterization of porous biomorphic SiC ceramics derived from wood • Successful deposition of bioactive calcium phosphate coatings using gas detonation deposition • Porosity and pore size of SiC ceramics depend on wood

  11. Elevated Temperature Testing and Modeling of Advanced Toughened Ceramic Materials

    Science.gov (United States)

    Keith, Theo G.

    2005-01-01

    The purpose of this report is to provide a final report for the period of 12/1/03 through 11/30/04 for NASA Cooperative Agreement NCC3-776, entitled "Elevated Temperature Testing and Modeling of Advanced Toughened Ceramic Materials." During this final period, major efforts were focused on both the determination of mechanical properties of advanced ceramic materials and the development of mechanical test methodologies under several different programs of the NASA-Glenn. The important research activities made during this period are: 1. Mechanical properties evaluation of two gas-turbine grade silicon nitrides. 2) Mechanical testing for fuel-cell seal materials. 3) Mechanical properties evaluation of thermal barrier coatings and CFCCs and 4) Foreign object damage (FOD) testing.

  12. Metallized ceramic vacuum pipe for particle beams

    International Nuclear Information System (INIS)

    Butler, B.L.; Featherby, M.

    1990-01-01

    A ceramic vacuum chamber segment in the form of a long pipe of rectangular cross section has been assembled from standard shapes of alumina ceramic using glass bonding techniques. Prior to final glass bonding, the internal walls of the pipe are metallized using an electroplating technology. These advanced processes allow for precision patterning and conductivity control of surface conducting films. The ability to lay down both longitudinal and transverse conductor patterns separated by insulating layers of glass give the accelerator designer considerable freedom in tailoring longitudinal and transverse beam pipe impedances. Assembly techniques of these beam pipes are followed through two iterations of semi-scale pipe sections made using candidate materials and processes. These demonstrate the feasibility of the concepts and provide parts for electrical characterization and for further refinement of the approach. In a parallel effort, a variety of materials, joining processes and assembly procedures have been tried to assure flexibility and reliability in the construction of 10-meter long sections to any required specifications

  13. Antibacterial Functionalization of PVD Coatings on Ceramics

    Directory of Open Access Journals (Sweden)

    Javier Osés

    2018-05-01

    Full Text Available The application of surface treatments that incorporate silver or copper as antibacterial elements has become a common practice for a wide variety of medical devices and materials because of their effective activity against nosocomial infections. Ceramic tiles are choice materials for cladding the floors and walls of operation rooms and other hospital spaces. This study is focused on the deposition of biocide physical vapor deposition (PVD coatings on glazed ceramic tiles. The objective was to provide antibacterial activity to the surfaces without worsening their mechanical properties. Silver and copper-doped chromium nitride (CrN and titanium nitride (TiN coatings were deposited on samples of tiles. A complete characterization was carried out in order to determine the composition and structure of the coatings, as well as their topographical and mechanical properties. The distribution of Ag and Cu within the coating was analyzed using glow discharge optical emission spectrometry (GD-OES and field emission scanning electron microscope (FE-SEM. Roughness, microhardness, and scratch resistance were measured for all of the combinations of coatings and dopants, as well as their wettability. Finally, tests of antibacterial efficacy against Staphylococcus aureus and Escherichia coli were carried out, showing that all of the doped coatings had pronounced biocide activity.

  14. Mechanical properties of ion implanted ceramic surfaces

    International Nuclear Information System (INIS)

    Burnett, P.J.

    1985-01-01

    This thesis investigates the mechanisms by which ion implantation can affect those surface mechanical properties of ceramics relevant to their tribological behaviour, specifically hardness and indentation fracture. A range of model materials (including single crystal Si, SiC, A1 2 0 3 , Mg0 and soda-lime-silica glass) have been implanted with a variety of ion species and at a range of ion energies. Significant changes have been found in both low-load microhardness and indentation fracture behaviour. The changes in hardness have been correlated with the evolution of an increasingly damaged and eventually amorphous thin surface layer together with the operation of radiation-, solid-solution- and precipitation-hardening mechanisms. Compressive surface stresses have been shown to be responsible for the observed changes in identation fracture behaviour. In addition, the levels of surface stress present have been correlated with the structure of the surface layer and a simple quantitative model proposed to explain the observed stress-relief upon amorphisation. Finally, the effects of ion implantation upon a range of polycrystalline ceramic materials has been investigated and the observed properties modifications compared and contrasted to those found for the model single crystal materials. (author)

  15. 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

  16. Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rajendra Bordia

    2009-07-31

    processing techniques for these coatings. In addition, we investigated the effect of microstructure on the mechanical properties and oxidation protection ability of the coatings. Coatings were developed to provide oxidation protection to both ferritic and austentic alloys and Ni-based alloys. The coatings that we developed are based on low viscosity pre-ceramic polymers. Thus they can be easily applied to any shape by using a variety of techniques including dip-coating, spray-coating and painting. The polymers are loaded with a variety of nanoparticles. The nanoparticles have two primary roles: control of the final composition and phases (and hence the properties); and control of the shrinkage during thermal decomposition of the polymer. Thus the selection of the nanoparticles was the most critical aspect of this project. Based on the results of the processing studies, the performance of selected coatings in oxidizing conditions (both static and cyclic) was investigated.

  17. Rotating Beam Fatigue Testing and Hybrid Ceramic Bearings.

    Science.gov (United States)

    1994-07-01

    Runout and Fast Fracture ......... 20 FIG.7 Stress-life Plots of Rotating Beam Fatigue Testing ............. 23 FIG.8 Fractograph of Rotating Beam...Chand-Kare Engineering Ceramics, Worcester, MA. Diamond wheels of 600 grits were used with longitudinal grinding applied for the final finishing of...stress in the range of 600-850 MPa. Three test completion modes were encountered, i.e. fast fracture at setup, fatigue fracture and runout (no failure

  18. Interactive Industrial Robot Programming for the Ceramic Industry

    OpenAIRE

    Germano Veiga; Pedro Malaca; Rui Cancela

    2013-01-01

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

  19. Glasses and ceramics for immobilisation of radioactive wastes for disposal

    International Nuclear Information System (INIS)

    Johnson, K.D.B.; Marples, J.A.C.

    1979-05-01

    The U.K. Research Programme on Radioactive Waste Management includes the development of processes for the conversion of high level liquid reprocessing wastes from thermal and fast reactors to borosilicate glasses. The properties of these glasses and their behaviour under storage and disposal conditions have been examined. Methods for immobilising activity from other wastes by conversion to glass or ceramic forms is described. The U.K. philosophy of final solutions to waste management and disposal is presented. (author)

  20. 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.

  1. 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.

  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. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Assessment and evaluation of ceramic filter cleaning techniques: Task Order 19

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.; Zaharchuk, R.; Harbaugh, L.B.; Klett, M.

    1994-10-01

    The objective of this study was to assess and evaluate the effectiveness, appropriateness and economics of ceramic barrier filter cleaning techniques used for high-temperature and high-pressure particulate filtration. Three potential filter cleaning techniques were evaluated. These techniques include, conventional on-line pulse driven reverse gas filter cleaning, off-line reverse gas filter cleaning and a novel rapid pulse driven filter cleaning. These three ceramic filter cleaning techniques are either presently employed, or being considered for use, in the filtration of coal derived gas streams (combustion or gasification) under high-temperature high-pressure conditions. This study was divided into six subtasks: first principle analysis of ceramic barrier filter cleaning mechanisms; operational values for parameters identified with the filter cleaning mechanisms; evaluation and identification of potential ceramic filter cleaning techniques; development of conceptual designs for ceramic barrier filter systems and ceramic barrier filter cleaning systems for two DOE specified power plants; evaluation of ceramic barrier filter system cleaning techniques; and final report and presentation. Within individual sections of this report critical design and operational issues were evaluated and key findings were identified.

  10. Preparation of Biomorphic TiO2 Ceramics from Rattan Templates

    Directory of Open Access Journals (Sweden)

    Liangcun Qian

    2015-05-01

    Full Text Available In this work, biomorphic ceramics were produced from various rattan templates, and sol infiltration was used with vacuum/positive pressure technology. Finally, the samples were sintered to form TiO2 ceramics with a rattan microstructure. Through X-ray diffraction (XRD, thermogravimetric (TG data, dimensional variation analysis, and scanning electron microscopy (SEM images of biomorphic ceramics, the results of this experiment showed that the times of sol-gel infiltration were decreased due to use of the vacuum/positive pressure technology. In order to further supply the TiO2 content and fill the pyrolysis gaps in the charcoal/TiO2 composites sintered at 800 °C, it was necessary to repeat the sol-gel process. In the transverse section, ceramics for the rattan templates without the rattan edge, more perfect biomorphic features were achieved. Conversely, deformations occurred along the transverse section of the ceramics for the templates made with the rattan edge. Meanwhile, the fracture phenomenon took place along the ceramic axial section. The main reason for deformation and fracture was that the anisotropic structure of the template was stressed during the sintering process. Furthermore, the micrometer-sized pores were found in the ceramics along the axial section because of the removal of the charcoal templates.

  11. 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

  12. 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

  13. 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.

  14. 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...

  15. 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

  16. Development of laundry drainage treatment system with ceramic ultra filter

    International Nuclear Information System (INIS)

    Kanda, Masanori; Kurahasi, Takafumi

    1995-01-01

    A compact laundry drainage treatment system (UF system hereafter) with a ceramic ultra filter membrane (UF membrane hereafter) has been developed to reduce radioactivity in laundry drainage from nuclear power plants. The UF membrane is made of sintered fine ceramic. The UF membrane has 0.01 μm fine pores, resulting in a durable, heat-resistant, and corrosion-resistant porous ceramic filter medium. A cross-flow system, laundry drainage is filtrated while it flows across the UF membrane, is used as the filtration method. This method creates less caking when compared to other methods. The UF membrane is back washed at regular intervals with permeated water to minimize caking of the filter. The UF membrane and cross-flow system provides long stable filtration. The ceramic UF membrane is strong enough to concentrate suspended solids in laundry drainage up to a weight concentration of 10%. The final concentrated laundry drainage can be treated in an incinerator. The performance of the UF system was checked using radioactive laundry drainage. The decontamination factor of the UF system was 25 or more. The laundry drainage treatment capacity and concentration ratio of the UF system, as well as the service life of the UF membrane were also checked by examination using simulated non-radioactive laundry drainage. Even though laundry drainage was concentrated 1000 times, the UF system showed good permeated water quality and permeated water flux. (author)

  17. Fracture Toughness (KIC) of Lithography Based Manufactured Alumina Ceramic

    Science.gov (United States)

    Nindhia, T. G. T.; Schlacher, J.; Lube, T.

    2018-04-01

    Precision shaped ceramic components can be obtained by an emerging technique called Lithography based Ceramic Manufacturing (LCM). A green part is made from a slurry consisting of a ceramic powder in a photocurable binder with addition of dispersant and plasticizer. Components are built in a layer–by-layer way by exposing the desired cross- sections to light. The parts are subsequently sintered to their final density. It is a challenge to produce ceramic component with this method that yield the same mechanical properties in all direction. The fracture toughness (KIc) of of LCM-alumina (prepared at LITHOZ GmbH, Austria) was tested by using the Single-Edge-V-Notched Beam (SEVNB) method. Notches are made into prismatic bend-bars in all three direction X, Y and Z to recognize the value of fracture toughness of the material in all three directions. The microstructure was revealed with optical microscopy as well as Scanning Electron Microscopy (SEM). The results indicate that the fracture toughness in Y-direction has the highest value (3.10 MPam1/2) that is followed by the one in X-direction which is just a bit lower (2.90 MPam1/2). The Z-direction is found to have a similar fracture toughness (2.95 MPam1/2). This is supported by a homogeneous microstructure showing no hint of the layers used during production.

  18. Comparison of mechanical properties of three machinable ceramics with an experimental fluorophlogopite glass ceramic.

    Science.gov (United States)

    Leung, Brian T W; Tsoi, James K H; Matinlinna, Jukka P; Pow, Edmond H N

    2015-09-01

    Fluorophlogopite glass ceramic (FGC) is a biocompatible, etchable, and millable ceramic with fluoride releasing property. However, its mechanical properties and reliability compared with other machinable ceramics remain undetermined. The purpose of this in vitro study was to compare the mechanical properties of 3 commercially available millable ceramic materials, IPS e.max CAD, Vitablocs Mark II, and Vita Enamic, with an experimental FGC. Each type of ceramic block was sectioned into beams (n=15) of standard dimensions of 2×2×15 mm. Before mechanical testing, specimens of the IPS e.max CAD group were further fired for final crystallization. Flexural strength was determined by the 3-point bend test with a universal loading machine at a cross head speed of 1 mm/min. Hardness was determined with a hardness tester with 5 Vickers hardness indentations (n=5) using a 1.96 N load and a dwell time of 15 seconds. Selected surfaces were examined by scanning electron microscopy and energy-dispersive x-ray spectroscopy. Data were analyzed by the 1-way ANOVA test and Weibull analysis (α=.05). Weibull parameters, including the Weibull modulus (m) as well as the characteristic strength at 63.2% (η) and 10.0% (B10), were obtained. A significant difference in flexural strength (PVita Enamic (145.95 ±12.65 MPa)>Vitablocs Mark II (106.67 ±18.50 MPa), and FGC (117.61 ±7.62 MPa). The Weibull modulus ranged from 6.93 to 18.34, with FGC showing the highest Weibull modulus among the 4 materials. The Weibull plot revealed that IPS e.max CAD>Vita Enamic>FGC>Vitablocs Mark II for the characteristic strength at both 63.2% (η) and 10.0% (B10). Significant difference in Vickers hardness among groups (PVitablocs Mark II (594.74 ±25.22 H(V))>Vita Enamic (372.29 ±51.23 H(V))>FGC (153.74 ±23.62 H(V)). The flexural strength and Vickers hardness of IPS e.max CAD were significantly higher than those of the 3 materials tested. The FGC's flexural strength was comparable with Vitablocs Mark II

  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. Ceramics based on calcium pyrophosphate nanopowders

    Directory of Open Access Journals (Sweden)

    Tatiana V. Safronova

    2013-03-01

    Full Text Available Present work is aimed at the fabrication of resorbable bioceramics based on calcium pyrophosphate (CPP from the synthesized powders of amorphous hydrated calcium pyrophosphate (AHCPP. Amorphous hydratedcalcium pyrophosphate in the form of nanopowders was precipitated from Ca(NO3 2 and (NH4 4P2O7 solutions at room temperature in the presence of PO3– ions. Crystalline CPP powder was fabricated from AHCPP by its thermal decomposition at 600 °C and consisted of β- and α- phase. Small particles, with the size less than 200 nm, were formed promoting sintering of the ceramic material. The final sample, sintered at 900 °C, exhibits microstructure with submicron grains, apparent density of 87% of theoretical density (TD and demonstrates tensile strength of 70 MPa.

  6. Surface treatment of ceramic articles

    International Nuclear Information System (INIS)

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

    1998-01-01

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

  7. Dynamic properties of ceramic materials

    International Nuclear Information System (INIS)

    Grady, D.E.

    1995-02-01

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

  8. Microstructure of SiC ceramics fabricated by pyrolysis of electron beam irradiated polycarbomethylsilane containing precursors

    International Nuclear Information System (INIS)

    Xu Yunshu; Tanaka, Shigeru

    2003-01-01

    A modified gel-casting method was developed to form the ceramics precursor matrix by using polycarbomehylsilane (PCMS) and SiC powder. The polymer precursor was mixed with SiC powder in toluene, and then the slurry samples were cast into designed shapes. The pre-ceramic samples were then irradiated by 2.0 MeV electron beam generated by a Cockcroft-Walton type accelerator in He gas flow to about 15 MGy. The cured samples were pyrolyzed and sintered into SiC ceramics at 1300degC in Ar gas. The modified gel-casting method leaves almost no internal stress in the pre-ceramic samples, and the electron beam curing not only diminished the amount of pyrolysis gaseous products but also enhanced the interface binding of the polymer converted SiC and the grains of SiC powder. Optical microscope, AFM and SEM detected no visible internal or surface cracks in the final SiC ceramics matrix. A maximum value of 122 MPa of flexural strength of the final SiC ceramics was achieved. (author)

  9. 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)

  10. Low frequency modelling of hysteresis behaviour and dielectric permittivity in ferroelectric ceramics under electric field

    International Nuclear Information System (INIS)

    Ducharne, B; Guyomar, D; Sebald, G

    2007-01-01

    The properties of ferroelectric ceramics strongly depend on the electromechanical loading and their measurement conditions. In this paper, a nonlinear phenomenological one-dimensional model based on the dry friction concept is presented to describe the hysteretic polarization behaviour. Dielectric permittivities versus dc electric field (or capacitance C versus voltage V) loops are determined for the characterization of ferroelectric material. The ε 33 coefficient is used for the ceramic characterization because it is strongly correlated with the ceramic quality. The purpose of this paper is to develop a model of reversal polarization behaviour close to physical realities, able to provide good performances on the simulation of dielectric permittivity loop ε 33 (E dc ). Simulated behaviours are finally compared with experimental results on a typically soft PZT ferroelectric ceramic

  11. Modelling of fluid flow in tape casting of thin ceramics: Analytical approaches and numerical investigations

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Hattel, Jesper Henri

    2016-01-01

    Tape casting has been used to produce thin layers of ceramics that can be used as single layers or can be stacked and laminated into multilayered structures. Many startup products such as multilayered inductors, multilayered varistors, piezoelectrics, ceramic fuel cells and lithium ion battery...... components are dependent upon tape casting technology. One of the growing sciences in the processing of ceramics by tape casting is the use of fluid flow analysis to control and enhance the final tapes. The fluid dynamics analysis of the ceramic slurries during tape casting is an efficient mean to elucidate...... the physical parameters crucial to the process. A review of the development of the tape casting process with particular focus on modelling the material flow is presented and in this context the current status is examined and future potential discussed....

  12. 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)

  13. Association of soil cadmium contamination with ceramic industry: A case study in a Chinese town

    International Nuclear Information System (INIS)

    Liao, Q. Lin; Liu, Cong; Wu, H. Yun; Jin, Yang; Hua, Ming; Zhu, B. Wan; Chen, Kai; Huang, Lei

    2015-01-01

    Soil cadmium (Cd) contamination is attributable to many sources, among which the ceramic industry is probably an important contributor whose relationship will be explored in this study. Upon studying a town in southeastern China that is quite famous for its ceramics, we observed that the soil Cd distribution agreed with the local ceramic industry's distribution in space and time from 2004 to 2014. Ceramic and pigment samples from a typical factory were selected in a case study, and a sediment core from a nearby river was collected. First, an application of the geo-accumulation index suggested that the sediment was very strongly polluted by Cd (mean 1874 mg/kg). Second, sediment dating indicated that the Cd concentration surge and the establishment of the factory were proximate in time (2002–2004). Third, principal component analysis showed high loading of Cd (0.947) solely, suggesting that the factory was most likely responsible for the Cd pollution found in the sediments of a nearby river. Finally, we infer that the soil cadmium pollution in the whole area may be related to the region's prosperous ceramic industry. Local government should reinforce controls of the ceramic industry and implement effective countermeasures. - Highlights: • The sediment is strongly polluted by Cd in a Chinese town. • Cd concentration surged when the nearby ceramic factory was established. • Cd is solely loaded in a principal component and abundant in the ceramic pigments. • The local ceramic industry may be responsible for the soil Cd contamination

  14. Association of soil cadmium contamination with ceramic industry: A case study in a Chinese town

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Q. Lin [Geological Survey of Jiangsu Province, Nanjing 210018 (China); Liu, Cong [Jiangsu Provincial Department of Land Resources, Nanjing 210017 (China); Wu, H. Yun [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Xianlin Campus, Box 624, 163 Xianlin Avenue, Nanjing 210023 (China); Jin, Yang; Hua, Ming; Zhu, B. Wan [Geological Survey of Jiangsu Province, Nanjing 210018 (China); Chen, Kai [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Xianlin Campus, Box 624, 163 Xianlin Avenue, Nanjing 210023 (China); Huang, Lei, E-mail: huanglei@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Xianlin Campus, Box 624, 163 Xianlin Avenue, Nanjing 210023 (China)

    2015-05-01

    Soil cadmium (Cd) contamination is attributable to many sources, among which the ceramic industry is probably an important contributor whose relationship will be explored in this study. Upon studying a town in southeastern China that is quite famous for its ceramics, we observed that the soil Cd distribution agreed with the local ceramic industry's distribution in space and time from 2004 to 2014. Ceramic and pigment samples from a typical factory were selected in a case study, and a sediment core from a nearby river was collected. First, an application of the geo-accumulation index suggested that the sediment was very strongly polluted by Cd (mean 1874 mg/kg). Second, sediment dating indicated that the Cd concentration surge and the establishment of the factory were proximate in time (2002–2004). Third, principal component analysis showed high loading of Cd (0.947) solely, suggesting that the factory was most likely responsible for the Cd pollution found in the sediments of a nearby river. Finally, we infer that the soil cadmium pollution in the whole area may be related to the region's prosperous ceramic industry. Local government should reinforce controls of the ceramic industry and implement effective countermeasures. - Highlights: • The sediment is strongly polluted by Cd in a Chinese town. • Cd concentration surged when the nearby ceramic factory was established. • Cd is solely loaded in a principal component and abundant in the ceramic pigments. • The local ceramic industry may be responsible for the soil Cd contamination.

  15. Porous biomorphic silicon carbide ceramics coated with hydroxyapatite as prospective materials for bone implants.

    Science.gov (United States)

    Gryshkov, Oleksandr; Klyui, Nickolai I; Temchenko, Volodymyr P; Kyselov, Vitalii S; Chatterjee, Anamika; Belyaev, Alexander E; Lauterboeck, Lothar; Iarmolenko, Dmytro; Glasmacher, Birgit

    2016-11-01

    Porous and cytocompatible silicon carbide (SiC) ceramics derived from wood precursors and coated with bioactive hydroxyapatite (HA) and HA-zirconium dioxide (HA/ZrO2) composite are materials with promising application in engineering of bone implants due to their excellent mechanical and structural properties. Biomorphic SiC ceramics have been synthesized from wood (Hornbeam, Sapele, Tilia and Pear) using a forced impregnation method. The SiC ceramics have been coated with bioactive HA and HA/ZrO2 using effective gas detonation deposition approach (GDD). The surface morphology and cytotoxicity of SiC ceramics as well as phase composition and crystallinity of deposited coatings were analyzed. It has been shown that the porosity and pore size of SiC ceramics depend on initial wood source. The XRD and FTIR studies revealed the preservation of crystal structure and phase composition of in the HA coating, while addition of ZrO2 to the initial HA powder resulted in significant decomposition of the final HA/ZrO2 coating and formation of other calcium phosphate phases. In turn, NIH 3T3 cells cultured in medium exposed to coated and uncoated SiC ceramics showed high re-cultivation efficiency as well as metabolic activity. The recultivation efficiency of cells was the highest for HA-coated ceramics, whereas HA/ZrO2 coating improved the recultivation efficiency of cells as compared to uncoated SiC ceramics. The GDD method allowed generating homogeneous HA coatings with no change in calcium to phosphorus ratio. In summary, porous and cytocompatible bio-SiC ceramics with bioactive coatings show a great promise in construction of light, robust, inexpensive and patient-specific bone implants for clinical application. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. 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

  17. 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.

  18. 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.

  19. Interactive Industrial Robot Programming for the Ceramic Industry

    Directory of Open Access Journals (Sweden)

    Germano Veiga

    2013-10-01

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

  20. A high temperature testing system for ceramic composites

    Science.gov (United States)

    Hemann, John

    1994-01-01

    Ceramic composites are presently being developed for high temperature use in heat engine and space power system applications. The operating temperature range is expected to be 1090 to 1650 C (2000 F to 3000 F). Very little material data is available at these temperatures and, therefore, it is desirable to thoroughly characterize the basic unidirectional fiber reinforced ceramic composite. This includes testing mainly for mechanical material properties at high temperatures. The proper conduct of such characterization tests requires the development of a tensile testing system includes unique gripping, heating, and strain measuring devices which require special considerations. The system also requires an optimized specimen shape. The purpose of this paper is to review various techniques for measuring displacements or strains, preferably at elevated temperatures. Due to current equipment limitations it is assumed that the specimen is to be tested at a temperature of 1430 C (2600F) in an oxidizing atmosphere. For the most part, previous high temperature material characterization tests, such as flexure and tensile tests, have been performed in inert atmospheres. Due to the harsh environment in which the ceramic specimen is to be tested, many conventional strain measuring techniques can not be applied. Initially a brief description of the more commonly used mechanical strain measuring techniques is given. Major advantages and disadvantages with their application to high temperature tensile testing of ceramic composites are discussed. Next, a general overview is given for various optical techniques. Advantages and disadvantages which are common to these techniques are noted. The optical methods for measuring strain or displacement are categorized into two sections. These include real-time techniques. Finally, an optical technique which offers optimum performance with the high temperature tensile testing of ceramic composites is recommended.

  1. Radiance limits of ceramic phosphors under high excitation fluxes

    Science.gov (United States)

    Lenef, Alan; Kelso, John; Zheng, Yi; Tchoul, Maxim

    2013-09-01

    Ceramic phosphors, excited by high radiance pump sources, offer considerable potential for high radiance conversion. Interestingly, thermodynamic arguments suggest that the radiance of the luminescent spot can even exceed that of the incoming light source. In practice, however, thermal quenching and (non-thermal) optical saturation limit the maximum attainable radiance of the luminescent source. We present experimental data for Ce:YAG and Ce:GdYAG ceramics in which these limits have been investigated. High excitation fluxes are achieved using laser pumping. Optical pumping intensities exceeding 100W/mm2 have been shown to produce only modest efficiency depreciation at low overall pump powers because of the short Ce3+ lifetime, although additional limitations exist. When pump powers are higher, heat-transfer bottlenecks within the ceramic and heat-sink interfaces limit maximum pump intensities. We find that surface temperatures of these laser-pumped ceramics can reach well over 150°C, causing thermal-quenching losses. We also find that in some cases, the loss of quantum efficiency with increasing temperature can cause a thermal run-away effect, resulting in a rapid loss in converted light, possibly over-heating the sample or surrounding structures. While one can still obtain radiances on the order of many W/mm2/sr, temperature quenching effects ultimately limit converted light radiance. Finally, we use the diffusion-approximation radiation transport models and rate equation models to simulate some of these nonlinear optical pumping and heating effects in high-scattering ceramics.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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

  7. Radiation Effects in Nuclear Ceramics

    Directory of Open Access Journals (Sweden)

    L. Thomé

    2012-01-01

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

  8. 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

  9. 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

  10. 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

  11. [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.

  12. 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)

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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).

  18. 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.

  19. Leaching behavior of phosphate-bonded ceramic waste forms

    International Nuclear Information System (INIS)

    Singh, D.; Wagh, A.S.; Jeong, S.Y.; Dorf, M.

    1996-04-01

    Over the last few years, Argonne National Laboratory has been developing room-temperature-setting chemically bonded phosphate ceramics for solidifying and stabilizing low-level mixed wastes. This technology is crucial for stabilizing waste streams that contain volatile species and off-gas secondary waste streams generated by high-temperature treatment of such wastes. We have developed a magnesium phosphate ceramic to treat mixed wastes such as ash, salts, and cement sludges. Waste forms of surrogate waste streams were fabricated by acid-base reactions between the mixtures of magnesium oxide powders and the wastes, and phosphoric acid or acid phosphate solutions. Dense and hard ceramic waste forms are produced in this process. The principal advantage of this technology is that the contaminants are immobilized by both chemical stabilization and subsequent microencapsulation of the reaction products. This paper reports the results of durability studies conducted on waste forms made with ash waste streams spiked with hazardous and radioactive surrogates. Standard leaching tests such as ANS 16.1 and TCLP were conducted on the final waste forms. Fates of the contaminants in the final waste forms were established by electron microscopy. In addition, stability of the waste forms in aqueous environments was evaluated with long-term water-immersion tests

  20. Fabrication of silica ceramic membrane via sol-gel dip-coating method at different nitric acid amount

    Science.gov (United States)

    Kahlib, N. A. Z.; Daud, F. D. M.; Mel, M.; Hairin, A. L. N.; Azhar, A. Z. A.; Hassan, N. A.

    2018-01-01

    Fabrication of silica ceramics via the sol-gel method has offered more advantages over other methods in the fabrication of ceramic membrane, such as simple operation, high purity homogeneous, well defined-structure and complex shapes of end products. This work presents the fabrication of silica ceramic membrane via sol-gel dip-coating methods by varying nitric acid amount. The nitric acid plays an important role as catalyst in fabrication reaction which involved hydrolysis and condensation process. The tubular ceramic support, used as the substrate, was dipped into the sol of Tetrethylorthosilicate (TEOS), distilled water and ethanol with the addition of nitric acid. The fabricated silica membrane was then characterized by (Field Emission Scanning Electron Microscope) FESEM and (Fourier transform infrared spectroscopy) FTIR to determine structural and chemical properties at different amount of acids. From the XRD analysis, the fabricated silica ceramic membrane showed the existence of silicate hydrate in the final product. FESEM images indicated that the silica ceramic membrane has been deposited on the tubular ceramic support as a substrate and penetrate into the pore walls. The intensity peak of FTIR decreased with increasing of amount of acids. Hence, the 8 ml of acid has demonstrated the appropriate amount of catalyst in fabricating good physical and chemical characteristic of silica ceramic membrane.

  1. 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.

  2. 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

  3. Potential assisted fabrication of metal-ceramic composite coatings

    International Nuclear Information System (INIS)

    Knote, A.; Schindler, U.; Krueger, H.G.; Kern, H.

    2003-01-01

    A possibility to produce uniform metal-ceramic composite coatings with a high content of ceramic particles up to 60 vol.% will be presented in this study. This method includes a combination of electrophoretic deposition and electrolytic deposition by several steps. A yttria-stabilized zirconia coating (Tosoh TZ-8Y) was first electrophoretically deposited on a ferritic steel plate and then sintered by 1100 C to an open porous layer. In the next step nickel was electrodeposited into the pores of the layer. By a final annealing step it was possible to improve the bonding of the composit coating on the substrate by diffusion of the metal components. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [de

  4. Electrophysical properties of PMN-PT-PS-PFN:Li ceramics

    Directory of Open Access Journals (Sweden)

    R. Skulski

    2013-01-01

    Full Text Available We present the technology of obtaining and the electrophysical properties of a multicomponent material 0.61PMN-0.20PT-0.09PS-0.1PFN:Li (PMN-PT-PS-PFN:Li. The addition of PFN into PMN-PT decreases the temperature of final sintering which is very important during technological process (addition of Li decreases electric conductivity of PFN. Addition of PS i.e., PbSnO3 (which is unstable in ceramic form permits to shift the temperature of the maximum of dielectric permittivity. One-step method of obtaining ceramic samples from oxides and carbonates has been used. XRD, microstructure, scanning calorimetry measurements and the main dielectric, ferroelectric and electromechanical properties have been investigated for the obtained samples.

  5. 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

  6. Bioactive glasses and glass-ceramics

    Directory of Open Access Journals (Sweden)

    de Aza, P. N.

    2007-04-01

    Full Text Available Since the late 1960´s, a great interest in the use of bioceramic materials for biomedical applications has been developed. In a previous paper, the authors reviewed crystalline bioceramic materials “sensus stricto”, it is to say, those ceramic materials, constituted for non-metallic inorganic compounds, crystallines and consolidates by thermal treatment of powders at high temperature. In the present review, the authors deal with those called bioactive glasses and glassceramics. Although all of them are also obtained by thermal treatment at high temperature, the first are amorphous and the second are obtained by devitrification of a glass, although the vitreous phase normally prevails on the crystalline phases. After an introduction to the concept of bioactive materials, a short historical review of the bioactive glasses development is made. Its preparation, reactivity in physiological media, mechanism of bonding to living tissues and mechanical strength of the bone-implant interface is also reported. Next, the concept of glass-ceramic and the way of its preparation are exposed. The composition, physicochemical properties and biological behaviour of the principal types of bioactive glasses and glass-ceramic materials: Bioglass®, Ceravital®, Cerabone®, Ilmaplant® and Bioverit® are also reviewed. Finally, a short review on the bioactive-glass coatings and bioactive-composites and most common uses of bioactive-glasses and glass-ceramics are carried out too.

    Desde finales de los años sesenta, se ha despertado un gran interés por el uso de los materiales biocerámicos para aplicaciones biomédicas. En un trabajo previo, los autores hicieron una revisión de los denominados materiales biocerámicos cristalinos en sentido estricto, es decir, de aquellos materiales, constituidos por compuestos inorgánicos no metálicos, cristalinos y consolidados mediante tratamientos térmicos a altas temperaturas. En el presente trabajo, los autores

  7. Development of nano-structured silicon carbide ceramics: from synthesis of the powder to sintered ceramics

    International Nuclear Information System (INIS)

    Reau, A.

    2008-12-01

    The materials used inside future nuclear reactors will be subjected to very high temperature and neutrons flux. Silicon carbide, in the form of SiC f /SiC nano-structured composite is potentially interesting for this type of application. It is again necessary to verify the contribution of nano-structure on the behaviour of this material under irradiation. To verify the feasibility and determine the properties of the matrix, it was envisaged to produce it by powder metallurgy from SiC nanoparticles. The objective is to obtain a fully dense nano-structured SiC ceramic without additives. For that, a parametric study of the phases of synthesis and agglomeration was carried out, the objective of which is to determine the active mechanisms and the influence of the key parameters. Thus, studying the nano-powder synthesis by laser pyrolysis allowed to produce, with high production rates, homogeneous batches of SiC nanoparticles whose size can be adjusted between 15 and 90 nm. These powders have been densified by an innovating method: Spark Plasma Sintering (SPS). The study and the optimization of the key parameters allowed the densification of silicon carbide ceramic without sintering aids while preserving the nano-structure of material. The thermal and mechanical properties of final materials were studied in order to determine the influence of the microstructure on their properties. (author)

  8. 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.

  9. 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.

  10. Effect of binder burnout on the sealing performance of glass ceramics for solid oxide fuel cells

    Science.gov (United States)

    Ertugrul, Tugrul Y.; Celik, Selahattin; Mat, Mahmut D.

    2013-11-01

    The glass ceramics composite sealants are among few materials suitable for the solid oxide fuel cells (SOFC) due to their high operating temperatures (600 °C-850 °C). The glass ceramics chemically bond to both the metallic interconnector and the ceramic electrolyte and provide a gas tight connection. A careful and several stages manufacturing procedure is required to obtain a gas tight sealing. In this study, effects of binder burnout process on the sealing performance are investigated employing commercially available glass ceramic powders. The glass ceramic laminates are produced by mixing glass ceramic powders with the organic binders and employing a tape casting method. The laminates are sandwiched between the metallic interconnectors of an SOFC cell. The burnout and subsequent sealing quality are analyzed by measuring leakage rate and final macrostructure of sealing region. The effects of heating rate, dead weight load, solid loading, carrier gas and their flow rates are investigated. It is found that sealing quality is affected from all investigated parameters. While a slower heating rate is required for a better burnout, the mass flow rate of sweep gas must be adequate for removal of the burned gas. The leakage rate is reduced to 0.1 ml min-1 with 2 °C min-1 + 1 °C min-1 heating rate, 86.25% solid loading, 200 N dead weight load and 500 ml min-1 sweep gas flow rate.

  11. 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.

  12. Fabrication of ceramic components for fluidics with green machining and reaction binding of Al-containing precursor mixes - component design and testing. Final report; Fertigung von keramischen Bauteilen fuer die Fluidtechnik mit Gruenbearbeitung und Reaktionsbinden von Al-haltigen Precursormischungen - Bauteilgestaltung und Erprobung. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Skirde, E.; Esders, H.; Ivantysyn, J.

    2003-03-05

    The Sauer-Danfoss project covered the testing of ceramic pistons and bushings in oil-hydraulic swash plate axial piston pumps. Both components move relative to each other while transmitting very high forces. This results in high component stresses and in high tribological loads of the contact surface. If the ceramic components can withstand both types of stress, the range of permissible operating parameters can be extended, especially the maximum speed as ceramics have a much lower specific mass than metals, which result in much lower inertial forces. In conventional systems of steel piston and metal bushing, high speed and high temperatures will result in poor lubrication and cause freezing of the piston. This is not the case with ceramics because of their great hardness, heat resistance, and chemical inertness. (orig.) [German] Das Teilprojekt von Sauer-Danfoss befasste sich mit der Erprobung keramischer Kolben und Buchsen in oelhydraulischen Schraegscheiben-Axialkolbenpumpen. Beide Bauteile (die sogenannten Leitteile) bewegen sich relativ zueinander und uebertragen dabei sehr hohe Betriebskraefte. Daraus resultieren nicht nur grosse Spannungen in den Teilen, sondern auch hohe tribologische Beanspruchungen in der Kontaktflaeche. Wenn die keramischen Bauteile beiden Beanspruchungsarten gewachsen sind, dann ist eine Ausdehnung des Bereichs erlaubter Betriebsparameter moeglich. Insbesondere ist hier die maximale Drehzahl zu nennen, da aus der im Vergleich zu metallischen Werkstoffen sehr geringen spezifischen Masse von Keramik weitaus geringere Traegheitskraefte resultieren. Bei der konventionellen Werkstoffpaarung (gehaerteter Stahlkolben-Messingbuchse) besteht ausserdem bei hohen Drehzahlen und Temperaturen wegen der damit verbundenen schlechten Schmierung die Gefahr des Festfressens. Diese ist bei keramischen Werkstoffen aufgrund der hohen Haerte, Waermebestaendigkeit und chemischen Inertheit nicht zu erwarten. (orig.)

  13. 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...

  14. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Gurney, Kevin R. [Arizona Univ., Mesa, AZ (United States)

    2015-01-12

    This document constitutes the final report under DOE grant DE-FG-08ER64649. The organization of this document is as follows: first, I will review the original scope of the proposed research. Second, I will present the current draft of a paper nearing submission to Nature Climate Change on the initial results of this funded effort. Finally, I will present the last phase of the research under this grant which has supported a Ph.D. student. To that end, I will present the graduate student’s proposed research, a portion of which is completed and reflected in the paper nearing submission. This final work phase will be completed in the next 12 months. This final workphase will likely result in 1-2 additional publications and we consider the results (as exemplified by the current paper) high quality. The continuing results will acknowledge the funding provided by DOE grant DE-FG-08ER64649.

  15. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    DeTar, Carleton [P.I.

    2012-12-10

    This document constitutes the Final Report for award DE-FC02-06ER41446 as required by the Office of Science. It summarizes accomplishments and provides copies of scientific publications with significant contribution from this award.

  16. Morphologies, Processing and Properties of Ceramic Foams and Their Potential as TPS Materials

    Science.gov (United States)

    Stackpoole, Mairead; Simoes, Conan R.; Johnson, Sylvia M.

    2002-01-01

    The current research is focused on processing ceramic foams with compositions that have potential as a thermal protection material. The use of pre-ceramic polymers with the addition of sacrificial blowing agents or sacrificial fillers offers a viable approach to form either open or closed cell insulation. Our work demonstrates that this is a feasible method to form refractory ceramic foams at relatively low processing temperatures. It is possible to foam complex shapes then pyrolize the system to form a ceramic while retaining the shape of the unfired foam. Initial work focused on identifying suitable pre-ceramic polymers with desired properties such as ceramic yield and chemical make up of the pyrolysis product after firing. We focused on making foams in the Si system (Sic, Si02, Si-0-C), which is in use in current acreage TPS systems. Ceramic foams with different architectures were formed from the pyrolysis of pre-ceramic polymers at 1200 C in different atmospheres. In some systems a sacrificial polyurethane was used as the blowing agent. We have also processed foams using sacrificial fillers to introduce controlled cell sizes. Each sacrificial filler or blowing agent leads to a unique morphology. The effect of different fillers on foam morphologies and the characterization of these foams in terms of mechanical and thermal properties are presented. We have conducted preliminary arc jet testing on selected foams with the materials being exposed to typical re-entry conditions for acreage TPS and these results will be discussed. Foams processed using these approaches have bulk densities ranging from 0.15 to 0.9 g/cm3 and cell sizes ranging from 5 to 500 pm. Compression strengths ranged from 2 to 7 MPa for these systems. Finally, preliminary oxidation studies have been conducted on selected systems and will be discussed.

  17. 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

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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)

  6. 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

  7. 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

  8. 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.

  9. 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

  10. 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...

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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

  16. Detoxification and immobilization of chromite ore processing residue in spinel-based glass-ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Chang-Zhong [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region (China); Tang, Yuanyuan [School of Environmental Science and Engineering, South University of Science and Technology of China, Shenzhen 518055 (China); Lee, Po-Heng [Department of Civil & Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong Special Administrative Region (China); Liu, Chengshuai, E-mail: csliu@soil.gd.cn [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China); State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550009 (China); Shih, Kaimin, E-mail: kshih@hku.hk [Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong Special Administrative Region (China); Li, Fangbai [Guangdong Key Laboratory of Agricultural Environment Pollution Integrated Control, Guangdong Institute of Eco-Environmental and Soil Sciences, Guangzhou 510650 (China)

    2017-01-05

    Graphical abstract: Schematic illustration of detoxification and immobilization of chromite ore processing residue in spinel-based glass-ceramic matrix. All Cr(VI) species is reduced to Cr(III) and most chromium contents are incorporated into spinel structure where the residual chromium are resided in the glass networks. - Highlights: • COPR was detoxified and immobilized in a spinel-based glass-ceramic matrix. • Cr-rich crystalline phase was determined to be MgCr{sub 1.32}Fe{sub 0.19}Al{sub 0.49}O{sub 4} spinel. • The partitioning ratio of Cr into spinel in the glass-ceramic can be up to 77%. • No Cr(VI) was observed after conversion of COPR into a glass-ceramic. • TCLP results demonstrate the superiority of the final product in immobilizing Cr. - Abstract: A promising strategy for the detoxification and immobilization of chromite ore processing residue (COPR) in a spinel-based glass-ceramic matrix is reported in this study. In the search for a more chemically durable matrix for COPR, the most critical crystalline phase for Cr immobilization was found to be a spinel solid solution with a chemical composition of MgCr{sub 1.32}Fe{sub 0.19}Al{sub 0.49}O{sub 4}. Using Rietveld quantitative X-ray diffraction analysis, we identified this final product is with the phases of spinel (3.5 wt.%), diopside (5.2 wt.%), and some amorphous contents (91.2 wt.%). The partitioning ratio of Cr reveals that about 77% of the Cr was incorporated into the more chemically durable spinel phase. The results of Cr K-edge X-ray absorption near-edge spectroscopy show that no Cr(VI) was observed after conversion of COPR into a glass-ceramic, which indicates successful detoxification of Cr(VI) into Cr(III) in the COPR-incorporated glass-ceramic. The leaching performances of Cr{sub 2}O{sub 3} and COPR-incorporated glass-ceramic were compared with a prolonged acid-leaching test, and the results demonstrate the superiority of the COPR-incorporated glass-ceramic matrix in the

  17. Detoxification and immobilization of chromite ore processing residue in spinel-based glass-ceramic

    International Nuclear Information System (INIS)

    Liao, Chang-Zhong; Tang, Yuanyuan; Lee, Po-Heng; Liu, Chengshuai; Shih, Kaimin; Li, Fangbai

    2017-01-01

    Graphical abstract: Schematic illustration of detoxification and immobilization of chromite ore processing residue in spinel-based glass-ceramic matrix. All Cr(VI) species is reduced to Cr(III) and most chromium contents are incorporated into spinel structure where the residual chromium are resided in the glass networks. - Highlights: • COPR was detoxified and immobilized in a spinel-based glass-ceramic matrix. • Cr-rich crystalline phase was determined to be MgCr 1.32 Fe 0.19 Al 0.49 O 4 spinel. • The partitioning ratio of Cr into spinel in the glass-ceramic can be up to 77%. • No Cr(VI) was observed after conversion of COPR into a glass-ceramic. • TCLP results demonstrate the superiority of the final product in immobilizing Cr. - Abstract: A promising strategy for the detoxification and immobilization of chromite ore processing residue (COPR) in a spinel-based glass-ceramic matrix is reported in this study. In the search for a more chemically durable matrix for COPR, the most critical crystalline phase for Cr immobilization was found to be a spinel solid solution with a chemical composition of MgCr 1.32 Fe 0.19 Al 0.49 O 4 . Using Rietveld quantitative X-ray diffraction analysis, we identified this final product is with the phases of spinel (3.5 wt.%), diopside (5.2 wt.%), and some amorphous contents (91.2 wt.%). The partitioning ratio of Cr reveals that about 77% of the Cr was incorporated into the more chemically durable spinel phase. The results of Cr K-edge X-ray absorption near-edge spectroscopy show that no Cr(VI) was observed after conversion of COPR into a glass-ceramic, which indicates successful detoxification of Cr(VI) into Cr(III) in the COPR-incorporated glass-ceramic. The leaching performances of Cr 2 O 3 and COPR-incorporated glass-ceramic were compared with a prolonged acid-leaching test, and the results demonstrate the superiority of the COPR-incorporated glass-ceramic matrix in the immobilization of Cr. The overall results suggest that

  18. 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

  19. 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.

  20. 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

  1. 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.

  2. 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)

  3. 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.

  4. 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

  5. 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...

  6. 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

  7. 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.

  8. 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

  9. 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.

  10. 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...

  11. Narrative Finality

    Directory of Open Access Journals (Sweden)

    Armine Kotin Mortimer

    1981-01-01

    Full Text Available The cloturai device of narration as salvation represents the lack of finality in three novels. In De Beauvoir's Tous les hommes sont mortels an immortal character turns his story to account, but the novel makes a mockery of the historical sense by which men define themselves. In the closing pages of Butor's La Modification , the hero plans to write a book to save himself. Through the thrice-considered portrayal of the Paris-Rome relationship, the ending shows the reader how to bring about closure, but this collective critique written by readers will always be a future book. Simon's La Bataille de Pharsale , the most radical attempt to destroy finality, is an infinite text. No new text can be written. This extreme of perversion guarantees bliss (jouissance . If the ending of De Beauvoir's novel transfers the burden of non-final world onto a new victim, Butor's non-finality lies in the deferral to a future writing, while Simon's writer is stuck in a writing loop, in which writing has become its own end and hence can have no end. The deconstructive and tragic form of contemporary novels proclaims the loss of belief in a finality inherent in the written text, to the profit of writing itself.

  12. 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.

  13. 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)

  14. Recycling ceramic industry wastes in sound absorbing materials

    Directory of Open Access Journals (Sweden)

    C. Arenas

    2016-10-01

    Full Text Available The scope of this investigation is to develop a material mainly composed (80% w/w of ceramic wastes that can be applied in the manufacture of road traffic noise reducing devices. The characterization of the product has been carried out attending to its acoustic, physical and mechanical properties, by measuring the sound absorption coefficient at normal incidence, the open void ratio, density and compressive strength. Since the sound absorbing behavior of a porous material is related to the size of the pores and the thickness of the specimen tested, the influence of the particle grain size of the ceramic waste and the thickness of the samples tested on the properties of the final product has been analyzed. The results obtained have been compared to a porous concrete made of crushed granite aggregate as a reference commercial material traditionally used in similar applications. Compositions with coarse particles showed greater sound absorption properties than compositions made with finer particles, besides presenting better sound absorption behavior than the reference porous concrete. Therefore, a ceramic waste-based porous concrete can be potentially recycled in the highway noise barriers field.

  15. Radiation-disorder and aperiodicity in irradiated ceramics

    International Nuclear Information System (INIS)

    Hobbs, L.W.

    1992-01-01

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

  16. Ceramic grade (U,Pu)O2 powder fabrication

    International Nuclear Information System (INIS)

    Cristallini, O.A.; Villegas de Maroto, Marina; De Pino, J.I.; Osuna, H.A.

    1980-01-01

    Ceramic grade UO 2 powder was obtained by the homogeneous precipitation method. This procedure was afterwards applied to the fabrication of ceramic grade (U,Pu)O 2 powders, and mixed oxide powders with Pu content ranging from 0.7 to 16% were obtained. The obtainment of mixed ceramic oxides as well as the recuperation of fabrication scraps were developed in three steps: 1)study of the process of homogeneous precipitation of ammonium diuranate (ADU); 2) co-precipitation of ADU/PuO 2 .H 2 O for Pu concentrations of 0.6 and 6.8; 3) the thermal conditioning to mixed oxide (U,Pu)O 2 powders. The experimental procedure involves the following steps: preparation of the PuO 2 (NO 3 ) 4 solution; co-precipitation of the PuO 2 (NO 3 ) 2 solution with an UO 2 (NO 3 ) 2 solution; filtration and drying of the precipitate, thermal treatment and finally, mixing, pressing and sintering of the (U,Pu)O 2 and Nukem UO 2 powder with a 0. of zinc stearate. Different controls were made by means of physical, chemical and ceramographic tests. This method can be used for the fabrication of fast reactor fuels or, previous mechanical dispersion in UO 2 powder, for the fabrication of thermal reactors fuels. (M.E.L.) [es

  17. Improvement of the stability of hydroxyapatite through glass ceramic reinforcement.

    Science.gov (United States)

    Ha, Na Ra; Yang, Zheng Xun; Hwang, Kyu Hong; Kim, Tae Suk; Lee, Jong Kook

    2010-05-01

    Hydroxyapatite has achieved significant application in orthopedic and dental implants due to its excellent biocompatibility. Sintered hydroxyapatites showed significant dissolution, however, after their immersion in water or simulated body fluid (SBF). This grain boundary dissolution, even in pure hydroxyapatites, resulted in grain separation at the surfaces, and finally, in fracture. In this study, hydroxyapatite ceramics containing apatite-wollastonite (AW) or calcium silicate (SG) glass ceramics as additives were prepared to prevent the dissolution. AW and SG glass ceramics were added at 0-7 wt% and powder-compacted uniaxially followed by firing at moisture conditions. The glass phase was incorporated into the hydroxyapatite to act as a sintering aid, followed by crystallization, to improve the mechanical properties without reducing the biocompatibility. As seen in the results of the dissolution test, a significant amount of damage was reduced even after more than 14 days. TEM and SEM showed no decomposition of HA to the secondary phase, and the fracture toughness increased, becoming even higher than that of the commercial hydroxyapatite.

  18. Achievement report for fiscal 1998. Research and development of ceramic gas turbine (Regenerative single-shaft ceramic gas turbine for cogeneration); 1998 nendo ceramic gas turbine no kenkyu kaihatsu seika hokokusho. Cogeneration yo saiseishiki ichijiku ceramic gas turbine

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-05-01

    Efforts are exerted to develop a 300kW-class ceramic gas turbine with a turbine inlet temperature of 1350 degrees C and thermal efficiency of 42% or higher. The soundness in strength of the ceramic rotor blades and their fastening structure is confirmed. Rotor blade cushion thickness is found to decrease in start-and-stop repetitions in the initial period, but not thereafter. The exhaust diffuser and exhaust path shape are studied and improved for an increase in output, which improves turbine efficiency by 1.7%. Under the operating conditions of 1350 degrees C and full load, NOx emissions and combustion efficiency prove to be 5.6ppm and 99.9%. Even in the case using a large-diameter liner with its combustion efficiency under light load improved, the ultimate target value is achieved. Studies are further conducted on centrifugal stage loss reduction towards the ultimate goal set for the compressor. The diffuser shape is improved and the shroud clearance is reduced, and insulation efficiency of 81.1% is attained at the designing stage. In a test run of a pilot ceramic gas turbine in which temperature finally arrives at 1350 degrees C, engine thermal efficiency of 35% and shaft output of 282kW are achieved. (NEDO)

  19. Ceramic Technology Project data base: September 1992 summary report

    Energy Technology Data Exchange (ETDEWEB)

    Keyes, B.L.P.

    1993-06-01

    Data presented in this report represent an intense effort to improve processing methods, testing methods, and general mechanical properties (rupture modulus, tensile, creep, stress-rupture, dynamic and cyclic fatigue, fracture toughness) of candidate ceramics for use in advanced heat engines. This work was performed by many facilities and represents only a small part of the data generated by the Ceramic Technology Project (CTP) since 1986. Materials discussed include GTE PY6, GN-10, NT-154, NT-164, SN-260, SN-251, SN-252, AY6, silicon nitride combined with rare-earth oxides, Y-TZP, ZTA, NC-433, NT-230, Hexoloy SA, MgO-PSZ-to-MgO-PSZ joints, MgO-PSZ-to-cast iron, and a few whisker/fiber-reinforced ceramics. Information in this report was taken from the project`s semiannual and bimonthly progress reports and from final reports summarizing the results of individual studies. Test results are presented in tabular form and in graphs. All data, including test rig descriptions and material characterizations, are stored in the CTP data base and are available to all project participants on request. The objective of this report is to make available the test results from these studies but not to draw conclusions from those data.

  20. Progress in tritium retention and release modeling for ceramic breeders

    International Nuclear Information System (INIS)

    Raffray, A.R.; Federici, G.; Billone, M.C.; Tanaka, S.

    1994-01-01

    Tritium behavior in ceramic breeder blankets is a key design issue for this class of blanket because of its impact on safety and fuel self-sufficiency. Over the past 10-15 years, substantial theoretical and experimental efforts have been dedicated world-wide to develop a better understanding of tritium transport in ceramic breeders. Models that are available today seem to cover reasonably well all the key physical transport and trapping mechanisms. They have allowed for reasonable interpretation and reproduction of experimental data and have helped in pointing out deficiencies in material property data base, in providing guidance for future experiments, and in analyzing blanket tritium behavior. This paper highlights the progress in tritium modeling over the last decade. Key tritium transport mechanisms are briefly described along with the more recent and sophisticated models developed to help understand them. Recent experimental data are highlighted and model calibration and validation discussed. Finally, example applications to blanket cases are shown as illustration of progress in the prediction of ceramic breeder blanket tritium inventory

  1. Grinding damage assessment on four high-strength ceramics.

    Science.gov (United States)

    Canneto, Jean-Jacques; Cattani-Lorente, Maria; Durual, Stéphane; Wiskott, Anselm H W; Scherrer, Susanne S

    2016-02-01

    ceramic framework post sintering should be avoided with final diamond grits of 75 μm as a general rule. For alumina and the glass-infiltrated alumina, using a 54 μm diamond still induces chip damage which may affect strength. Removal of such damage from a reshaped framework is mandatory by using sequentially finer diamonds prior to the application of veneering ceramics especially in critical areas such as margins, connectors and inner surfaces. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  2. 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.

  3. Final Report

    DEFF Research Database (Denmark)

    Heiselberg, Per; Brohus, Henrik; Nielsen, Peter V.

    This final report for the Hybrid Ventilation Centre at Aalborg University describes the activities and research achievement in the project period from August 2001 to August 2006. The report summarises the work performed and the results achieved with reference to articles and reports published...

  4. 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

  5. Fast densification processes for carbon and ceramic composites

    International Nuclear Information System (INIS)

    Delhaes, P.; Robin-Brosse, C.; David, P.

    2006-01-01

    A general introduction of the different vapour infiltration processes developed to prepare carbon-carbon composites is presented. Then a novel method with a liquid precursor, called film boiling or calefaction technique is described and compared with the usual ones. It is shown how this technique is very attractive to prepare carbon and ceramic composites within a short processing time together with a higher carbon yield. Finally the pertinent parameters of this process to evaluate its advantages and drawbacks for a further industrial development are analysed. (authors)

  6. Thermal properties of lithium ceramics for fusion applications

    International Nuclear Information System (INIS)

    Hollenberg, G.W.; Baker, D.E.

    1982-03-01

    Specific heat, thermal diffusivity and thermal conductivity were measured on Li 2 O, Li 4 SiO 4 , Li 2 ZrO 3 and LiAlO 2 . Data on these properties were needed for design of an irradiation experiment to be performed on these materials. In general, the specific heat of a ceramic is primarily enrichment-dependent, but the thermal diffusivity and thermal expansion coefficient may be influenced by microstructure. Hence, it will be necessary to duplicate these measurements on the engineering materials finally selected for a particular design

  7. 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.

  8. Description of a ceramic waste form and canister for Savannah River Plant high-level waste

    International Nuclear Information System (INIS)

    Butler, J.L.; Allender, J.S.; Gould, T.H. Jr.

    1982-04-01

    A canistered ceramic waste form for possible immobilization of Savannah River Plant (SRP) high-level radioactive wastes is described. Characteristics reported for the form include waste loading, chemical composition, heat content, isotope inventory, mechanical and thermal properties, and leach rates. A conceptual design of a potential production process for making this canistered form are also described. The ceramic form was selected in November 1981 as the primary alternative to the reference waste form, borosilicate glass, for making a final waste form decision for SRP waste by FY-1983. 11 tables

  9. 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.

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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)

  18. 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)

  19. 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

  20. 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

  1. 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)

  2. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Stinis, Panos [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-08-07

    This is the final report for the work conducted at the University of Minnesota (during the period 12/01/12-09/18/14) by PI Panos Stinis as part of the "Collaboratory on Mathematics for Mesoscopic Modeling of Materials" (CM4). CM4 is a multi-institution DOE-funded project whose aim is to conduct basic and applied research in the emerging field of mesoscopic modeling of materials.

  3. Single-source-precursor Synthesis and High-temperature Behavior of SiC Ceramics Containing Boron

    Science.gov (United States)

    Gui, Miaomiao; Fang, Yunhui; Yu, Zhaoju

    2014-12-01

    In this paper, a hyperbranched polyborocarbosilane (HPBCS) was prepared by a one-pot synthesis with Cl2Si(CH3)CH2Cl, Cl3SiCH2Cl and BCl3 as the starting materials. The obtained HPBCS was characterized by GPC, FT-IR and NMR, and was confirmed to have hyperbranched structures. The thermal property of the resulting HPBCS was investigated by TGA. The ceramic yield of the HPBCS is about 84% and that of the counterpart hyperbranched hydridopolycarbosilane is only 45%, indicating that the introduction of boron into the preceramic polymer significantly improved the ceramic yield. With the polymer-derived ceramic route, the final ceramics were annealed at 1800 °C in argon atmosphere for 2 h in order to characterize the microstructure and to evaluate the high-temperature behavior. The final ceramic microstructure was studied by XRD and SEM, indicating that the introduction of boron dramatically inhibits SiC crystallization. The boron-containing SiC ceramic shows excellent high-temperature behavior against decomposition and crystallization at 1800 °C.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. Physicochemical analysis of clays and ceramics of the regional state of Calakmul: production models, distribution and consumption

    International Nuclear Information System (INIS)

    Dominguez C, M.R.; Folan, W.J.; Espinosa P, M.E.; Rodriguez L, V.

    2005-01-01

    This work presents the final results of the research project 'Sources, production and consumption of ceramics in the regional state of Calakmul: a socio-political approach', with the proposal of models of production and ceramic specialization as well as of distribution and consumption of these goods in the territory that occupied the regional state of Calakmul, with base in the typological analysis of the ceramics of Calakmul and 72 sites registered in its environs as well as in comparative studies with ceramics of other greater sites near Calakmul and complemented with the application of analytical techniques in the study of clays and sherds diagnoses of the Mayan Classic period. These models were proposed also, according to a socio-political approach based on the social and political relations that Calakmul maintained with other political entities of diverse ranks derived from the obtained epigraphic evidences. (Author)

  13. Influence of implant abutment material and ceramic thickness on optical properties.

    Science.gov (United States)

    Jirajariyavej, Bundhit; Wanapirom, Peeraphorn; Anunmana, Chuchai

    2018-05-01

    Anterior shade matching is an essential factor influencing the esthetics of a ceramic restoration. Dentists face a challenge when the color of an implant abutment creates an unsatisfactory match with the ceramic restoration or neighboring teeth. The purpose of this in vitro study was to evaluate the influence of abutment material and ceramic thickness on the final color of different ceramic systems. Four experimental and control ceramic specimens in shade A3 were cut from IPS e.max CAD, IPS Empress CAD, and VITA Suprinity PC blocks. These specimens had thicknesses of 1.0 mm, 1.5 mm, 2.0 mm, and 2.5 mm, respectively, for the experimental groups, and 4 mm for the controls. Background abutment specimens were fabricated to yield 3 different shades: white zirconia, yellow zirconia, and titanium at a 3-mm thickness. All 3 ceramic specimens in each thickness were placed in succession on different abutment backgrounds with glycerin optical fluid in between, and the color was measured. A digital spectrophotometer was used to record the specimen color value in the Commission Internationale De L'éclairage (CIELab) color coordinates system and to calculate the color difference (ΔE) between the control and experimental groups. The Kruskal-Wallis test was used to analyze the effect of ceramic thickness on different abutments, and the pair-wise test was used to evaluate within the group (α=.05). The color differences between the test groups and the control decreased with increasing ceramic thickness for every background material. In every case, significant differences were found between 1.0- and 2.5-mm ceramic thicknesses. Only certain 2.5-mm e.max CAD, VITA Suprinity PC, and Empress CAD specimens on yellow-shade zirconia or VITA Suprinity PC on titanium were identified as clinically acceptable (ΔEabutment background decreased the color mismatch. Increasing the thickness of ceramic on a yellow-shaded zirconia abutment rather than on titanium or white zirconia yielded a more

  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. Convertible shielding to ceramic breeding blanket

    International Nuclear Information System (INIS)

    Furuya, Kazuyuki; Kurasawa, Toshimasa; Sato, Satoshi; Nakahira, Masataka; Togami, Ikuhide; Hashimoto, Toshiyuki; Takatsu, Hideyuki; Kuroda, Toshimasa.

    1995-05-01

    Four concepts have been studied for the ITER convertible blanket: 1)Layered concept 2)BIT(Breeder-Inside-Tube)concept 3)BOT(Breeder-Out of-Tube)concept 4)BOT/mixed concept. All concepts use ceramic breeder and beryllium neutron multiplier, both in the shape of small spherical pebbles, 316SS structure, and H 2 O coolant (inlet/outlet temperatures : 100/150degC, pressure : 2 MPa). During the BPP, only beryllium pebbles (the primary pebble in case of BOT/mixed concept) are filled in the blanket for shielding purpose. Then, before the EPP operation, breeder pebbles will be additionally inserted into the blanket. Among possible conversion methods, wet method by liquid flow seems expecting for high and homogeneous pebble packing. Preliminary 1-D neutronics calculation shows that the BOT/mixed concept has the highest breeding and shielding performance. However, final selection should be done by R and D's and more detail investigation on blanket characteristics and fabricability. Required R and D's are also listed. With these efforts, the convertible blanket can be developed. However, the following should be noted. Though many of above R and D's are also necessary even for non-convertible blanket, R and D's on convertibility will be one of the most difficult parts and need significant efforts. Besides the installation of convertible blanket with required structures and lines for conversion will make the ITER basic machine more complicated. (author)

  17. EXOTIC: Development of ceramic tritium breeding materials

    International Nuclear Information System (INIS)

    Flipot, A.J.; Kennedy, P.; Conrad, R.

    1989-03-01

    As part of the joint European Programme on fusion blanket technology three laboratories, Northern Research Laboratories (NRL), Springfields in the UK, SCK/CEN-Mol in Belgium and ECN-Petten in conjunction with JRC-Petten in the Netherlands have worked closely together since 1983 on the development of ceramic breeder materials, the programme being codenamed EXOTIC. Lithium oxides, aluminates, silicates and zirconates have been produced, characterised and irradiated in the HFR-Petten in experiments EXOTIC-1, -2 and -3. EXOTIC-4 is in preparation. In this fourth annual progress report the work achieved in 1987 is reported. For EXOTIC-1 to -3 mainly post irradiation examinations have been carried out like: visual inspection, puncturing of closed capsules, tritium retention measurements and material characterisation. Moreover, tritium release experiments on small specimens have started. SCK/CEN performed a general study on lithium silicates, in particular on the thermal stability. Finally, the fabrication and the characterisation of the materials to be irradiated in experiment EXOTIC-4 are presented. The eight capsules of EXOTIC-4 will be loaed with samples of Li 2 SiO 3 , Li 2 O, Li 2 ZrO 3 , Li 6 Zr 2 O 7 and Li 8 ZrO 6 . The irradiation will last 4 reactor cycles or about 100, Full Power Day, FPD. The main objective is to determine the tritium residence time of the various lithium zirconates. 18 figs., 8 refs., 15 tabs

  18. Fracture toughness measurements on zirconia toughened ceramics

    International Nuclear Information System (INIS)

    El Sayed Ali, M.; Toft Soerensen, O.

    1986-12-01

    Three techniques for fracture toughness measurements on zirconia toughened ceramics were evaluated: the notched beam (NB) technique, the indentation fracture (IF) technique and the indentation strength in bending (ISB) technique. Using these techniques comparative measurements were performed on samples prepared by pressing (uniaxial) and sintering of four commercially available powder types. These were: Toya Soda (Japan) powders with the designations TZ3Y (2.86 mole% Y 2 O 3 ), TZ3YA (2.77 mole% Y 2 O 3 , 0.1 wt% Al 2 O 3 ) and TZ3Y20A (2.88 mole% Y 2 O 3 , 20 wt.% Al 2 O 3 ) and a powder supplied by Viking Chemicals (Denmark) designated as YP5Z-2.5 (2.5 mole% Y 2 O 3 ). The measurements showed that similar K Ic values were obtained with the IF- and ISB-techniques, which therefore are recommended for K Ic measurements. Too high values were, however, obtained with the NB-technique which therefore cannot be recommended. Finally, the measurements showed that a high temperature annealing is recommended prior to testing for the IF-technique. (author)

  19. Ultrastructural Analysis on the Osteogenesis and Transformation of Calcium Phosphate Ceramics in Vivo

    Institute of Scientific and Technical Information of China (English)

    Honglian DAI; Shipu LI; Yuhua YAN; Xianying CAO; Xuehui LU; Yang LENG

    2004-01-01

    To study the osteogenesis and transformation process of calcium phosphate bioceramic in vivo, biodegradable porous β-tricalcium phosphate ceramics (β-TCP, φ5×8 mm) were implanted in the tibia of rabbits. β-TCP ceramics with surrounding bone tissue were retrieved and observed by SEM, TEM and EPMA every month after implantation.The results showed that osteogenesis was active and β-TCP ceramics bonded to bones directly. The new bones were forming and maturing as materials were continuously degrading, and materials were finally replaced by new bone. Parts of the materials were degraded, absorbed and recrystallized, while the rest were dispersed to the spongy bone and the Haversian lamella in an irregular arrangement, becoming incorporated into bone formation directly by remodeling the structure. Some β-TCP crystals cleaved along its (001) rhombohedral plane and formed lath-like crystals in vivo.

  20. Ceramics baking temperature influence on the dosimetric parameters essential in TL dating

    International Nuclear Information System (INIS)

    Krumpschmid, K.R.

    1986-11-01

    Thermoluminescence in quartz is used for dating of ceramics. The main problem is the 'intercept', i.e. the deviation from linearity in the relationship thermoluminescence versus absorbed dose of natural radiation. This deviation is most probably dependent on the fabrication method of the ceramics. In the present work the hypothesis is tested that the most important parameter, in this respect, is the baking temperature. Four types of ceramic bricks were fabricated, with four burning cycles of end temperatures of 550 0 C, 650 0 C, 900 0 C and 1200 0 C respectively, then irradiated and finally underwent the TL-procedure. The results are discussed with regard of the maximum of glow curve, intensity, fading, sensitivity to beta radiation and to additional alpha radiation and the intercept. (qui)

  1. Characterization of Al2O3-Co ceramic composite obtained by high energy mill

    International Nuclear Information System (INIS)

    Souza, J.L.; Assis, R.B. de; Carlos, E.M.; Oliveira, T.P.; Costa, F.A. da

    2014-01-01

    This work aims to characterize the ceramic composite Al 2 O3-Co obtained by high energy grinding. The composites were obtained by milling Al 2 O 3 and Co in a high energy mill at a speed of 400 rpm, in proportions of 5 to 20% Cobalt (Co). Ceramic composites with 5 and 20% cobalt were sintered at 1200 and 1300 ° C, with a 60-minute plateau and a heating rate of 10 ° C / min. The samples were characterized by X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG / DSC) and scanning electron microscopy (SEM). The results show the significant effect of cobalt percentage and high energy grinding on the final properties of the Al 2 O 3 - Co ceramic composite, presenting satisfactory values for the composite with a 20% cobalt percentage, showing to be a promising material for application in cutting tools

  2. Physical properties and microstructures of La_{1-{x}}Pr_{{x}}PO_4 monazite-ceramics

    Science.gov (United States)

    Thust, Anja; Hirsch, Antje; Haussühl, Eiken; Schrodt, Nadine; Loison, Lise; Schott, Petra; Peters, Lars; Roth, Georg; Winkler, Björn

    2018-04-01

    Synthetic La_{1-{x}}Pr_{{x}}PO_4 monazite-type powders and ceramics with 0 ≤ x ≤ 1 were analysed by scanning electron microscopy, high-temperature powder X-ray diffraction, dilatometry, and plane wave ultrasound spectroscopy. Ceramics were synthesised in a two-step sintering process at 1273 and 1573 K. Final densities were up to 99.3% of the theoretical densities. Each sample shows a homogeneous distribution of grain sizes, which increase with increasing sintering temperature. Grain sizes also depend on composition, with intermediate compositions yielding the largest grains. In-situ high-temperature powder X-ray diffraction shows that the volumetric thermal expansion coefficients of the monazite powders decrease with increasing Pr content. This behavior is not observed in dilatometry measurements of the bulk samples (ceramics) because their thermal expansion mainly depends on their density. Elastic properties show the same dependence on the density.

  3. The preparation of HfC/C ceramics via molecular design.

    Science.gov (United States)

    Inzenhofer, Kathrin; Schmalz, Thomas; Wrackmeyer, Bernd; Motz, Günter

    2011-05-07

    Polymer derived ceramics have received lots of attention throughout the last few decades. Unfortunately, only a few precursor systems have been developed, focusing on silicon based polymers and ceramics, respectively. Herein, the synthesis of novel hafnium containing organometallic polymers by two different approaches is reported. Dialkenyl substituted hafnocene monomers were synthesized and subsequently polymerized via a free radical mechanism. Salt metathesis reactions of hafnocene dichloride with bifunctional linkers led to the formation of polymeric materials. NMR spectroscopic methods--in solution as well as in the solid state--were used to characterize the organometallic polymers. Ceramics were finally obtained after cross-linking and thermal treatment under argon (T(max) = 1800 °C). SEM investigations, elemental analyses, Raman spectroscopy and XRD investigations identified the pyrolyzed products as partially crystalline HfC/C mixed phases.

  4. The Effect of Modeling Qualities, Tones and Gages in Ceramic Supply Chains' Master Planning

    Directory of Open Access Journals (Sweden)

    Isabel MUNDI

    2012-01-01

    Full Text Available Ceramic production processes are characterized by providing quantities of the same finished goods that differ in qualities, tones and gages. This aspect becomes a problem for ceramic supply chains (SCs that should promise and serve customer orders with homogeneous quantities of the same finished good. In this paper a mathematical programming model for the cen-tralized master planning of ceramic SC is proposed. Inputs to the master plan include demand forecasts in terms of customer order classes based on their order size and splitting percentages of a lot into homogeneous sub-lots. Then, the master plan defines the size and loading of lots to production lines and their distribution with the aim of maximizing the number of customer orders fulfilled with homogeneous quantities in the most efficient manner for the SC. Finally, the effect of modeling qualities, tones and gages in master planning is assessed.

  5. Layered Manufacturing of Dental Ceramics: Fracture Mechanics, Microstructure, and Elemental Composition of Lithography-Sintered Ceramic.

    Science.gov (United States)

    Uçar, Yurdanur; Aysan Meriç, İpek; Ekren, Orhun

    2018-02-11

    To compare the fracture mechanics, microstructure, and elemental composition of lithography-based ceramic manufacturing with pressing and CAD/CAM. Disc-shaped specimens (16 mm diameter, 1.2 mm thick) were used for mechanical testing (n = 10/group). Biaxial flexural strength of three groups (In-Ceram alumina [ICA], lithography-based alumina, ZirkonZahn) were determined using the "piston on 3-ball" technique as suggested in test Standard ISO-6872. Vickers hardness test was performed. Fracture toughness was calculated using fractography. Results were statistically analyzed using Kruskal-Wallis test followed by Dunnett T3 (α = 0.05). Weibull analysis was conducted. Polished and fracture surface characterization was made using scanning electron microscope (SEM). Energy dispersive spectroscopy (EDS) was used for elemental analysis. Biaxial flexural strength of ICA, LCM alumina (LCMA), and ZirkonZahn were 147 ± 43 MPa, 490 ± 44 MPa, and 709 ± 94 MPa, respectively, and were statistically different (P ≤ 0.05). The Vickers hardness number of ICA was 850 ± 41, whereas hardness values for LCMA and ZirkonZahn were 1581 ± 144 and 1249 ± 57, respectively, and were statistically different (P ≤ 0.05). A statistically significant difference was found between fracture toughness of ICA (2 ± 0.4 MPa⋅m 1/2 ), LCMA (6.5 ± 1.5 MPa⋅m 1/2 ), and ZirkonZahn (7.7 ± 1 MPa⋅m 1/2 ) (P ≤ 0.05). Weibull modulus was highest for LCMA (m = 11.43) followed by ZirkonZahn (m = 8.16) and ICA (m = 5.21). Unlike LCMA and ZirkonZahn groups, a homogeneous microstructure was not observed for ICA. EDS results supported the SEM images. Within the limitations of this in vitro study, it can be concluded that LCM seems to be a promising technique for final ceramic object manufacturing in dental applications. Both the manufacturing method and the material used should be improved. © 2018 by the American College of Prosthodontists.

  6. 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

  7. 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.

  8. 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

  9. Ceramic waste forms for fuel-containing masses at Chernobyl

    International Nuclear Information System (INIS)

    Oversby, V.M.

    1994-05-01

    The fuel materials originally in the core of the Chernobyl Unit 4 reactor are now present within the Ukrytie in three major forms: (1) very fine particles of fuel dispersed as dust (about 10 tonnes), (2) fragments of the destroyed core, and (3) lavas containing fuel, cladding, and other materials. All of these materials will need to be immobilized into waste forms suitable for final disposal. We propose a ceramic waste form system that could accommodate all three waste types with a single set of processing equipment. The waste form would include the mineral zirconolite for immobilization of actinide materials (including uranium), perovskite, nepheline, spinel, and other phases as dictated by the chemistry of the lava masses. Waste loadings as high as 50% U can be achieved if pyrochlore, a close relative of zirconolite, is used as the U host. The ceramic immobilization could be achieved with low additions of inert chemicals to minimize the final disposal volume while ensuring a durable product. The sequence of processing would be to collect and immobilize the fuel dust first. This material will require minimal preprocessing and will provide experience in the handling of the fuel materials. Core fragments would be processed next, using a cryogenic crushing stage to reduce the size prior to adding ceramic additives. The lavas would be processed last, which is compatible with the likely sequence of availability of materials and with the complexity of the operations. The lavas will require more adjustment of chemical additive composition than the other streams to ensure that the desired phases are produced in the waste form

  10. Fabrication and characterisation of a novel biomimetic anisotropic ceramic/polymer-infiltrated composite material.

    Science.gov (United States)

    Al-Jawoosh, Sara; Ireland, Anthony; Su, Bo

    2018-04-10

    To fabricate and characterise a novel biomimetic composite material consisting of aligned porous ceramic preforms infiltrated with polymer. Freeze-casting was used to fabricate and control the microstructure and porosity of ceramic preforms, which were subsequently infiltrated with 40-50% by volume UDMA-TEGDMA polymer. The composite materials were then subjected to characterisation, namely density, compression, three-point bend, hardness and fracture toughness testing. Samples were also subjected to scanning electron microscopy and computerised tomography (Micro-CT). Three-dimensional aligned honeycomb-like ceramic structures were produced and full interpenetration of the polymer phase was observed using micro-CT. Depending on the volume fraction of the ceramic preform, the density of the final composite ranged from 2.92 to 3.36g/cm 3 , compressive strength ranged from 206.26 to 253.97MPa, flexural strength from 97.73 to 145.65MPa, hardness ranged from 1.46 to 1.62GPa, and fracture toughness from 3.91 to 4.86MPam 1/2 . Freeze-casting provides a novel method to engineer composite materials with a unique aligned honeycomb-like interpenetrating structure, consisting of two continuous phases, inorganic and organic. There was a correlation between the ceramic fraction and the subsequent, density, strength, hardness and fracture toughness of the composite material. Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

  11. 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.

  12. Shade evaluation of ceramic laminates according to different try-in materials.

    Science.gov (United States)

    Lopes, Lawrence Gonzaga; Vaz, Maysa Magalhaes; de Magalhaes, Ana Paula Rodrigues; Cardoso, Paula Carvalho; de Souza, Joao Batista; de Torres, Erica Miranda

    2014-01-01

    The porcelain laminate replaces the visible portion of enamel with a ceramic, which is attached to the dental surface. To enhance cosmetic results, a preliminary color matching procedure is performed prior to cementing the veneers. This procedure can be performed using water, water-soluble gel, or try-in paste. The different shades of cement and try-in pastes are intended to obtain better color and esthetics of the final restoration. This study sought to evaluate the shade of ceramic veneers produced by different try-in materials. Forty bovine teeth and 40 ceramic discs (0.6 mm thick) were prepared. The samples were divided into 4 groups (n = 10). For Group 1 samples, no material was used between the tooth and the ceramic, Group 2 interposed samples with water, Group 3 used a water-soluble gel, and Group 4 used try-in paste (value 0). The color was measured with a spectrophotometer, obtaining L*, a*, and b* values to calculate the color difference (ΔE*). The data were subjected to normality tests and 1-way ANOVA. No significant statistical differences were found among the groups, indicating that the different try-in materials had similar effects on the color of the ceramic laminates.

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

    Science.gov (United States)

    Singh, Mrityunjay

    2003-01-01

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

  14. Structural Ceramic Nanocomposites: A Review of Properties and Powders’ Synthesis Methods

    Science.gov (United States)

    Palmero, Paola

    2015-01-01

    Ceramic nanocomposites are attracting growing interest, thanks to new processing methods enabling these materials to go from the research laboratory scale to the commercial level. Today, many different types of nanocomposite structures are proposed in the literature; however, to fully exploit their exceptional properties, a deep understanding of the materials’ behavior across length scales is necessary. In fact, knowing how the nanoscale structure influences the bulk properties enables the design of increasingly performing composite materials. A further key point is the ability of tailoring the desired nanostructured features in the sintered composites, a challenging issue requiring a careful control of all stages of manufacturing, from powder synthesis to sintering. This review is divided into four parts. In the first, classification and general issues of nanostructured ceramics are reported. The second provides basic structure–property relations, highlighting the grain-size dependence of the materials properties. The third describes the role of nanocrystalline second-phases on the mechanical properties of ordinary grain sized ceramics. Finally, the fourth part revises the mainly used synthesis routes to produce nanocomposite ceramic powders, underlining when possible the critical role of the synthesis method on the control of microstructure and properties of the sintered ceramics. PMID:28347029

  15. Systematic approach to preparing ceramic-glass composites with high translucency for dental restorations.

    Science.gov (United States)

    Yoshimura, Humberto N; Chimanski, Afonso; Cesar, Paulo F

    2015-10-01

    Ceramic composites are promising materials for dental restorations. However, it is difficult to prepare highly translucent composites due to the light scattering that occurs in multiphase ceramics. The objective of this work was to verify the effectiveness of a systematic approach in designing specific glass compositions with target properties in order to prepare glass infiltrated ceramic composites with high translucency. First it was necessary to calculate from literature data the viscosity of glass at the infiltration temperature using the SciGlass software. Then, a glass composition was designed for targeted viscosity and refractive index. The glass of the system SiO2-B2O3-Al2O3-La2O3-TiO2 prepared by melting the oxide raw materials was spontaneously infiltrated into porous alumina preforms at 1200°C. The optical properties were evaluated using a refractometer and a spectrophotometer. The absorption and scattering coefficients were calculated using the Kubelka-Munk model. The light transmittance of prepared composite was significantly higher than a commercial ceramic-glass composite, due to the matching of glass and preform refractive indexes which decreased the scattering, and also to the decrease in absorption coefficient. The proposed systematic approach was efficient for development of glass infiltrated ceramic composites with high translucency, which benefits include the better aesthetic performance of the final prosthesis. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. 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.

  17. 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

  18. 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)

  19. 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

  20. Influence of clay mineralogy on clay based ceramic products

    International Nuclear Information System (INIS)

    Radzali Othman; Tuan Besar Tuan Sarif; Zainal Arifin Ahmad; Ahmad Fauzi Mohd Noor; Abu Bakar Aramjat

    1996-01-01

    Clay-based ceramic products can either be produced directly from a suitable clay source without the need further addition or such products can be produced from a ceramic body formulated by additions of other raw materials such as feldspar and silica sand. In either case, the mineralogical make-up of the clay component plays a dominating role in the fabrication and properties of the ceramic product. This study was sparked off by a peculiar result observed in one of five local ball clay samples that were used to reformulate a ceramic body. Initial characterisation tests conducted on the clays indicated that these clays can be classified as kaolinitic. However, one of these clays produced a ceramic body that is distinctively different in terms of whiteness, smoothness and density as compared to the other four clays. Careful re-examination of other characterisation data, such as particle size distribution and chemical analysis, failed to offer any plausible explanation. Consequently, the mineralogical analysis by x-ray diffraction was repeated by paying meticulous attention to specimen preparation. Diffraction data for the clay with anomalous behaviour indicated the presence of a ∼ 10A peak that diminished when the same specimen was re-tested after heating in an oven at 12O degree C whilst the other four clays only exhibit the characteristic kaolinite (Al sub 2 O sub 3. 2SiO sub 2. 2H sub 2 0) and muscovite peaks at ∼ 7A and ∼ 10A before and after heat treatment. This suggests the presence of the mineral halloysite (A1 sub 2 0 sub 3. 2SiO sub 2.4H sub 2 0) in that particular clay. This difference in mineralogy can be attributed to account for the variations in physical properties of the final product. Consequently, this paper reviews in general the precautionary measures that must be adhered to during any mineralogical investigation of clay minerals or clay-based materials. The common pitfalls during specimen preparation, machine settings and interpretation of

  1. Processing of porous zirconia ceramics by direct consolidation with starch

    International Nuclear Information System (INIS)

    Garrido, Liliana B; Albano, Maria P

    2008-01-01

    Porous ceramics are used especially for those environments with high temperatures, heavy wear and in a corrosive medium. Zirconium-based materials are useful for such applications as sensors, filters, support for catalytic reactions, porous components for sofc and in biomedical applications. A conventional method for producing porous ceramics consists of the addition and later decomposition by calcination (pyrolisis) of different organic materials that act as pore formers. Several wet processing possibilities have been developed. Among these is a technique of direct consolidation with starch. This process begins with the preparation of an aqueous suspension of the ceramic with the dispersants needed to stabilize it, to which the starch is added. After casting in a waterproof mold, the suspension thermally hardens into the desired shape. The dry compacts undergo the sintering cycle to obtain pieces almost in their final form. This study aims to optimize the processing of porous zirconium ceramics using starch as a pore and binder forming agent. Zirconium with 3% yttrium molar stabilized in tetragonal phase was used. The aqueous suspensions (52-55% vol) of the zirconium-starch mixtures with different compositions were stabilized with a commercial solution of ammonium polyacrylate as a dispersant and were hardened in plastic molds at 90 o C for 30 min. The influence of added volume of starch on the physical characteristics of the pieces in green state was established while maintaining the temperature, the gelling time and the conditions of constant drying. The sintering was carried out at 1000-1500 o C-2h. The characteristics of the sintered product were evaluated by measuring density, volumetric contraction, intrusion of Hg and the evolution of the crystalline phases by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The microstructural properties of ceramic (pore volume, the relation between open and closed porosity, size distribution, morphology of

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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.

  7. 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.

  8. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Jarillo-Herrero, Pablo [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

    2017-02-07

    This is the final report of our research program on electronic transport experiments on Topological Insulator (TI) devices, funded by the DOE Office of Basic Energy Sciences. TI-based electronic devices are attractive as platforms for spintronic applications, and for detection of emergent properties such as Majorana excitations , electron-hole condensates , and the topological magneto-electric effect . Most theoretical proposals envision geometries consisting of a planar TI device integrated with materials of distinctly different physical phases (such as ferromagnets and superconductors). Experimental realization of physics tied to the surface states is a challenge due to the ubiquitous presence of bulk carriers in most TI compounds as well as degradation during device fabrication.

  9. 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)

  10. 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

  11. 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)

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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.

  19. Shape-forming and densification of ceramic superconductors

    International Nuclear Information System (INIS)

    Prakash, Om; Thomas, C.A.; Magadum, A.P.; Anklekar, R.M.; Khosla, N.K.; Kumar, Sunil; Chaudhuri, B.; Ramesh, M.; Rao, B.T.; Rama Mohan, T.R.

    1991-01-01

    Processing studies on varied shape-forming and densification of bulk ceramic superconductor, YBa 2 Cu 3 Osub(7-δ), are reported in this paper. Polyvinyl butyral-polyethylene glycol-trichloroethylene has been found to be the best binder-plasticizer-solvent system in plastic shape-forming. The effect of initial particle morphology on final densification has been the most sensitive single parameter as compared to compaction pressure and final sintering durations at ∼930degC. 1-2-3 powders of mean particle size ∼1.94μm have yielded sintered densities ∼92%T.D. albeit with lower oxygen intake Osub(6.7). (author). 8 refs., 8 figs

  20. 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

  1. Three-Point Bending Tests of Zirconia Core/Veneer Ceramics for Dental Restorations

    Directory of Open Access Journals (Sweden)

    Massimo Marrelli

    2013-01-01

    Full Text Available Introduction. The mechanical strength and the surface hardness of commercially available yttrium-doped zirconia were investigated. Furthermore, a comparative study of eight different ceramic veneers, to be used for the production of two-layered all-ceramic restorative systems, was carried out. Materials and Methods. Four types of zirconia specimens were analyzed, according to a standard ISO procedure (ISO 6872. Besides, two-layered zirconia-veneer specimens were prepared for three-point bending tests. Results. A strong effect of the surface roughness on the mechanical strength of zirconia specimens was observed. Finally, a comparative study of eight commercially available veneering ceramics shows different modes of failure between the selected veneers. Conclusion. The results indicate that close attention should be paid to the preparation of zirconia-based crowns and bridges by CAD/CAM process, because surface roughness has an important effect on the mechanical strength of the material. Finally, the results of the mechanical tests on two-layered specimens represent an important support to the choice of the veneering ceramic.

  2. 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)

  3. 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

  4. 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.

  5. 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

  6. Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Webb, Robert C. [Texas A& M University; Kamon, Teruki [Texas A& M University; Toback, David [Texas A& M University; Safonov, Alexei [Texas A& M University; Dutta, Bhaskar [Texas A& M University; Dimitri, Nanopoulos [Texas A& M University; Pope, Christopher [Texas A& M University; White, James [Texas A& M University

    2013-11-18

    Overview The High Energy Physics Group at Texas A&M University is submitting this final report for our grant number DE-FG02-95ER40917. This grant has supported our wide range of research activities for over a decade. The reports contained here summarize the latest work done by our research team. Task A (Collider Physics Program): CMS & CDF Profs. T. Kamon, A. Safonov, and D. Toback co-lead the Texas A&M (TAMU) collider program focusing on CDF and CMS experiments. Task D: Particle Physics Theory Our particle physics theory task is the combined effort of Profs. B. Dutta, D. Nanopoulos, and C. Pope. Task E (Underground Physics): LUX & NEXT Profs. R. Webb and J. White(deceased) lead the Xenon-based underground research program consisting of two main thrusts: the first, participation in the LUX two-phase xenon dark matter search experiment and the second, detector R&D primarily aimed at developing future detectors for underground physics (e.g. NEXT and LZ).

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. 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.

  14. 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

  15. 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...

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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...

  1. 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

  2. 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

  3. 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.)

  4. 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.

  5. 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).

  6. 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

  7. 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

  8. 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.

  9. 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.)

  10. 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

  11. 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)

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. Prospects of ceramic tritium breeder materials

    International Nuclear Information System (INIS)

    Roth, E.; Roux, N.; Conservatoire National des Arts et Metiers; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette

    1989-01-01

    In this paper the authors examine the prospects of the main ceramics proposed as breeder materials for fusion reactors, i.e. Li-2O, Li-2ZrO-3, LiAlO-2, Li-4SiO-4. To do so they review terms of reference of contemplated blankets for NET, ITER and DEMO, and the proposed blanket concepts and materials. Issues respective to the use of each breeder material are examined, and from this review it is concluded that ceramics are the most favorable breeder materials whose use can be contemplated as well for a driver blanket for NET or ITER and for a DEMO blanket. Ceramics are then compared between themselves and it is seen that, subject to the confirmation of recent experimental results, lithium zirconate could be used with advantage in any of the present blanket concepts, except in those employing lithium at its natural isotopic abundance, in which case only Li-2O can be used. However in specific cases, or in parts of a blanket, other ceramics may be profitably employed. As a general conclusion suggestions are made to further improve ceramic breeder performances, and it is recommended to intensify also work on problems that have to be solved in order to operate ceramic breeder blankets e.g. tritium extraction and recovery systems and conditions of beryllium use. (author). 37 refs.; 12 tabs

  18. Ceramics in Restorative and Prosthetic DENTISTRY1

    Science.gov (United States)

    Kelly, J. Robert

    1997-08-01

    This review is intended to provide the ceramic engineer with information about the history and current use of ceramics in dentistry, contemporary research topics, and potential research agenda. Background material includes intra-oral design considerations, descriptions of ceramic dental components, and the origin, composition, and microstructure of current dental ceramics. Attention is paid to efforts involving net-shape processing, machining as a forming method, and the analysis of clinical failure. A rationale is presented for the further development of all-ceramic restorative systems. Current research topics receiving attention include microstructure/processing/property relationships, clinical failure mechanisms and in vitro testing, wear damage and wear testing, surface treatments, and microstructural modifications. The status of the field is critically reviewed with an eye toward future work. Significant improvements seem possible in the clinical use of ceramics based on engineering solutions derived from the study of clinically failed restorations, on the incorporation of higher levels of "biomimicry" in new systems, and on the synergistic developments in dental cements and adhesive dentin bonding.

  19. Structure and properties of interfaces in ceramics

    International Nuclear Information System (INIS)

    Bonnell, D.; Ruehle, M.; Chowdhry, U.

    1995-01-01

    The motivation for the symposium was the observation that interfaces in crystallographically and compositionally complex systems often dictate the performance and reliability of devices that utilize functional ceramics. The current level of understanding of interface-property relations in silicon-based devices required over 30 years of intensive research. Similar issues influence the relationship between atomic bonding at interfaces and properties in functional ceramic systems. The current understanding of these complex interfaces does not allow correlation between atomic structure and interface properties, in spite of their importance to a number of emerging technologies (wireless communications, radar-based positioning systems, sensors, etc.). The objective of this symposium was to focus attention on these fundamental issues by featuring recent theoretical and experimental work from various disciplines that impact the understanding of interface chemistry, structure, and properties. The emphasis was on relating properties of surfaces and interfaces to structure through an understanding of atomic level phenomena. Interfaces of interest include metal/ceramic, ceramic/ceramic, ceramic/vapor, etc., in electronic, magnetic, optical, ferroelectric, piezoelectric, and dielectric applications. Sixty one papers have been processed separately for inclusion on the data base

  20. Adjusting dental ceramics: An in vitro evaluation of the ability of various ceramic polishing kits to mimic glazed dental ceramic surface.

    Science.gov (United States)

    Steiner, René; Beier, Ulrike S; Heiss-Kisielewsky, Irene; Engelmeier, Robert; Dumfahrt, Herbert; Dhima, Matilda

    2015-06-01

    During the insertion appointment, the practitioner is often faced with the need to adjust ceramic surfaces to fit a restoration to the adjacent or opposing dentition and soft tissues. The purpose of this study was to assess the ceramic surface smoothness achieved with various commercially available ceramic polishing kits on different commonly used ceramic systems. The reliability of the cost of a polishing kit as an indicator of improved surface smoothness was assessed. A total of 350 ceramic surfaces representing 5 commonly available ceramic systems (IPS Empress Esthetic, IPS e.max Press, Cergo Kiss, Vita PM 9, Imagine PressX) were treated with 5 types of ceramic polishing systems (Cerapreshine, 94006C, Ceramiste, Optrafine, Zenostar) by following the manufacturers' guidelines. The surface roughness was measured with a profilometer (Taylor Hobson; Precision Taylor Hobson Ltd). The effects of ceramic systems and polishing kits of interest on surface roughness were analyzed by 2-way ANOVA, paired t test, and Bonferroni corrected significance level. The ceramic systems and polishing kits statistically affected surface roughness (Pceramic surface. No correlation could be established between the high cost of the polishing kit and low surface roughness. None of the commonly used ceramic polishing kits could create a surface smoother than that of glazed ceramic (Pceramic polishing kits is not recommended as a reliable indicator of better performance of ceramic polishing kits (P>.30). Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.