WorldWideScience

Sample records for ceramic composite material

  1. Glasses, ceramics, and composites from lunar materials

    Science.gov (United States)

    Beall, George H.

    1992-02-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

  2. Glasses, ceramics, and composites from lunar materials

    Science.gov (United States)

    Beall, George H.

    1992-01-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

  3. Ceramic nanostructure materials, membranes and composite layers

    OpenAIRE

    Burggraaf, A.J.; Keizer, K.; Hassel, van, E Edwin

    1989-01-01

    Synthesis methods to obtain nanoscale materials will be briefly discussed with a focus on sol-gel methods. Three types of nanoscale composites (powders, membranes and ion implanted layers) will be discussed and exemplified with recent original research results. Ceramic membranes with a thickness of 1–10 μm consist of a packing of elementary particles with a size of 3–7 nm. The mean pore size is about 2.5–3 nm. The preparation routes are based on sol and sol-gel technologies. The pores can be ...

  4. INTELLIGENT MATERIALS BASED ON CERAMIC COMPOSITES

    OpenAIRE

    Maximov, Y.; Merzlikin, V.; Sidorov, O.; Suttugin, V.

    2010-01-01

    The paper examines the possibility to design intellectual materials based on film composites. Ferroelectric composites are offered to use as the film composites. The authors discuss ferroelectric composites of different structures. Sensors and intellectual materials on the basis of the obtained composites are considered.

  5. Tribology of ceramics and composites materials science perspective

    CERN Document Server

    Basu, Bikramjit

    2011-01-01

    This book helps students and practicing scientists alike understand that a comprehensive knowledge about the friction and wear properties of advanced materials is essential to further design and development of new materials. With important introductory chapters on the fundamentals, processing, and applications of tribology, the book then examines in detail the nature and properties of materials, the friction and wear of structural ceramics, bioceramics, biocomposites, and nanoceramics, as well as lightweight composites and the friction and wear of ceramics in a cryogenic environment.

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

    International Nuclear Information System (INIS)

    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

  7. Ceramic fiber-reinforced monoclinic celsian phase glass-ceramic matrix composite material

    Science.gov (United States)

    Bansal, Narottam P. (Inventor); Dicarlo, James A. (Inventor)

    1994-01-01

    A hyridopolysilazane-derived ceramic fiber reinforced monoclinic celsian phase barium aluminum silicate glass-ceramic matrix composite material is prepared by ball-milling an aqueous slurry of BAS glass powder and fine monoclinic celsian seeds. The fibers improve the mechanical strength and fracture toughness and with the matrix provide superior dielectric properties.

  8. 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.

  9. Actively Cooled Ceramic Composite Nozzle Material Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Phase I Project demonstrated the capability of the Pyrowave? manufacturing process to produce fiber-reinforced ceramics (FRCs) with integral metal features,...

  10. Nondestructive evaluation of a ceramic matrix composite material

    Science.gov (United States)

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

    1992-01-01

    Monolithic ceramic materials have proven their usefulness in many applications, yet, their potential for critical structural applications is limited because of their sensitivity to small imperfections. To overcome this extreme sensitivity to small imperfections, ceramic matrix composite materials have been developed that have the ability to withstand some distributed damage. A borosilicate glass reinforced with several layers of silicon-carbide fiber mat has been studied. Four-point flexure and tension tests were performed not only to determine some of the material properties, but also to initiate a controlled amount of damage within each specimen. Acousto-ultrasonic (AU) measurements were performed periodically during mechanical testing. This paper will compare the AU results to the mechanical test results and data from other nondestructive methods including acoustic emission monitoring and X-ray radiography. It was found that the AU measurements were sensitive to the damage that had developed within the material.

  11. Calcium phosphate-based ceramic and composite materials for medicine

    International Nuclear Information System (INIS)

    The topical problems in chemistry and technology of materials based on calcium phosphates aimed at both the replacement of damaged bone tissue and its regeneration are discussed. Specific features of the synthesis of nanocrystalline powders and the fabrication of ceramic implants are described. Advances in the development of porous scaffolds from resorbable and osteoconductive calcium phosphates and of hybrid composites that form the basis of bone tissue engineering are considered.

  12. Processing and Material Characterization of Continuous Basalt Fiber Reinforced Ceramic Matrix Composites Using Polymer Derived Ceramics.

    Science.gov (United States)

    Cox, Sarah B.

    2014-01-01

    The need for high performance vehicles in the aerospace industry requires materials which can withstand high loads and high temperatures. New developments in launch pads and infrastructure must also be made to handle this intense environment with lightweight, reusable, structural materials. By using more functional materials, better performance can be seen in the launch environment, and launch vehicle designs which have not been previously used can be considered. The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Polymer matrix composites can be used for temperatures up to 260C. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in the composites. In this study, continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. The oxyacetylene torch testing and three point bend testing have been performed on test panels and the test results are presented.

  13. Ceramic composition

    International Nuclear Information System (INIS)

    Improved ceramic compositions useful for cutting tools and the like are described. They are composed of an essentially homogeneous admixture of sintered powders of an aluminum oxide base material with other refractories including zirconium oxide, titanium oxide, hafnium oxide, titanium nitride, zirconium nitride, and tungsten or molybdenum carbide. In addition to their common and improved properties of hardness and strength, many of these compositions may be made by simple cold-pressing and sintering procedures. This avoids the known drawbacks of conventional hot press production

  14. New toughening concepts for ceramic composites from rigid natural materials.

    Science.gov (United States)

    Mayer, George

    2011-07-01

    The mechanisms underlying the toughening in rigid natural composites exhibited by the concentric cylindrical composites of spicules of hexactinellid sponges, and by the nacre (brick-and-mortar) structure of mollusks such as Haliotis rufescens (red abalone), as well as the crossed-lamellar structure of Strombus gigas (queen conch) show commonalities in the manner in which toughening takes place. It is proposed that crack diversion, a new kind of crack bridging, resulting in retardation of delamination, creation of new surface areas, and other energy-dissipating mechanisms occur in both natural systems. However, these are generally different from the toughening mechanisms that are utilized for other classes of structural materials. Complementary to those mechanisms found in rigid natural ceramic/organic composites, special architectures and thin viscoelastic organic layers have been found to play controlling roles in energy dissipation in these structures. PMID:21565715

  15. Application of Technogenic-Raw Material and Burning Out Additive in Composite Ceramic System

    OpenAIRE

    Viktor KIZINIEVIČ; Ramunė ŽURAUSKIENĖ; Kizinievič, Olga; Liudas TUMONIS; Rimvydas ŽURAUSKAS

    2012-01-01

    The investigation of the composite ceramic system containing easily fusible hydro-micous clay, technogenic finely dispersed raw material, and burning out waste additive is presented in the article. The properties of the raw materials used are described in the paper. The obtained ceramic bodies were burned at 1000 °C and 1050 °C temperatures, keeping at the highest burning temperature for 4 h. The analysis of physical-mechanical properties of composite ceramics (density, compressive strength, ...

  16. Continuous Fiber Ceramic Composites

    Energy Technology Data Exchange (ETDEWEB)

    None

    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.

  17. The Influence of Tool Composite's Structure During Process of Diamond Grinding of Ceramic Materials

    OpenAIRE

    Gawlik Józef; Niemczewska-Wójcik Magdalena; Krajewska Joanna; Sokhan Serghej V.; Paščenko E.A.; Žuk T.S.

    2014-01-01

    This paper presents the results of the tests performed during the grinding process of the ceramic materials: – polycrystalline ceramics (Zirconium ZrO2) and mono-crystalline ceramics (sapphire α-Al2O3) by the diamond tools. Studies have shown that the concentration (thickening) of the tool composite changes the tool's pore structure when using suitable wetted adamantine additives. Such modified composite has positive impact on tribological properties of the subsurface layer of the machined co...

  18. Effect of Rare Earth Composite Ceramic Materials on Oil Combustion of Oil-Burning Boiler

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The rare earth composite ceramic materials were prepared using rare earths and far infrared natural mineral. The effects of the as-prepared ceramic materials on the oil consumption and air pollutants emissions of oil-burning boiler were investigated. The results show that the composite ceramic materials can radiate higher intensity of far infrared. The molecular movement is strengthened and the chemical bonds of the molecules are easily ruptured when the diesel oil is dealt with the composite materials. The oil-saving rate of the RBS·VH-1.5 boiler dealt with the rare earth composite ceramic materials is 3.49%, and the reducing rates of CO and NO in the exhaust gas are 25.4% and 9.7%, respectively.

  19. Composite materials based on porous ceramic preform infiltrated by aluminium alloy

    Directory of Open Access Journals (Sweden)

    A. Nagel

    2007-01-01

    Full Text Available Purpose: The goal of this project is the optimization of manufacturing technology of the ceramic preforms basedon Al2O3 powder manufactured by the pressure infiltration method with liquid metal alloy.Design/methodology/approach: Ceramic preforms were manufactured by the method of sintering of ceramicpowder. The preform material consists of powder Condea Al2O3 CL 2500, however, as the forming factor ofthe structure of canals and pores inside the ceramic agglomerated framework the carbon fibers Sigrafil C10M250 UNS were used. Then ceramic preforms were infiltrated with liquid EN AC – AlSi12 aluminum alloy.Stereological and structure investigations of obtained composite materials were made on light microscope.Findings: It was proved that developed technology of manufacturing of composite materials with the pore ceramicAl2O3 infiltration ensures expected structure and can be used in practice.Practical implications: The developed technology allows to obtain method’s elements locally reinforced andcomposite materials with precise shape mapping.Originality/value: The received results show the possibility of obtaining the new composite materials being thecheaper alternative for other materials based on the ceramic fibers.

  20. Characterization of composite materials based on cement-ceramic powder blended binder

    Science.gov (United States)

    Kulovaná, Tereza; Pavlík, Zbyšek

    2016-06-01

    Characterization of newly developed composite mortars with incorporated ceramic powder coming from precise brick cutting as partial Portland cement replacement up to 40 mass% is presented in the paper. Fine ceramic powder belongs to the pozzolanic materials. Utilization of pozzolanic materials is accompanied by lower request on energy needed for Portland clinker production which generally results in lower production costs of blended binder and lower CO2 emission. In this paper, the ceramic powder is used in cement based mortar composition in amount of 8, 16, 24, 32, and 40 mass% of cement. Chemical composition of ceramic powder is analyzed by X-Ray Fluorescence and X-Ray Diffraction. The particle size distribution of ceramics is accessed on laser diffraction principle. For 28 days cured mortar samples, basic physical and mechanical properties are experimentally determined. The obtained results demonstrate that ceramic powder has potential to replace a part of Portland cement in composition of cement based composites and to reduce negative environmental impact of their production.

  1. Reinforcement of ceramic materials

    International Nuclear Information System (INIS)

    In the commercial field, greater reproduceability of ceramic materials was achieved by systematic process control of the steps in manufacture. By improvement of the microstructure design, the strength and toughness against tearing of the materials were increased. The articles give a survey of theoretical and experimental results in manufacture and of the composition of ceramics with reinforced structure. Preferred materials are zirconium-, aluminium- and yttrium oxide, silicon oxide and -nitride and titanium- and silicon carbide. (DG)

  2. Environmental durability of ceramics and ceramic composites

    Science.gov (United States)

    Fox, Dennis S.

    1992-01-01

    An account is given of the current understanding of the environmental durability of both monolithic ceramics and ceramic-matrix composites, with a view to the prospective development of methods for the characterization, prediction, and improvement of ceramics' environmental durability. Attention is given to the environmental degradation behaviors of SiC, Si3N4, Al2O3, and glass-ceramic matrix compositions. The focus of corrosion prevention in Si-based ceramics such as SiC and Si3N4 is on the high and low sulfur fuel combustion-product effects encountered in heat engine applications of these ceramics; sintering additives and raw material impurities are noted to play a decisive role in ceramics' high temperature environmental response.

  3. Structural ceramic coatings in composite microtruss cellular materials

    Energy Technology Data Exchange (ETDEWEB)

    Bele, E.; Bouwhuis, B.A.; Codd, C. [Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario (Canada); Hibbard, G.D., E-mail: glenn.hibbard@utoronto.ca [Department of Materials Science and Engineering, University of Toronto, 184 College Street, Toronto, Ontario (Canada)

    2011-09-15

    Graphical abstract: The compressive strength increase per unit sleeve thickness of Al cores reinforced with Al{sub 2}O{sub 3} sleeves is lower than the corresponding strength increase when the same cores are reinforced with nanocrystalline Ni (n-Ni) sleeves (left). However, because anodizing is a transformative surface treatment, the Al{sub 2}O{sub 3} coating was able to achieve this performance increase with little overall weight penalty (right). Display Omitted Highlights: {yields} A new type of metal/ceramic microtruss cellular composite has been created. {yields} Reinforcing sleeves of Al{sub 2}O{sub 3} were deposited on low density Al microtruss cores. {yields} Significant compressive strength increases were seen at virtually no weight penalty. {yields} Failure mechanisms were studied by electron microscopy and finite element analysis. {yields} Buckling, sleeve wrinkling, and coating fracture dictated the compressive strength. - Abstract: In the present study, anodizing was used to produce Al{sub 2}O{sub 3} coatings in a conventional 3003 aluminum alloy microtruss core; a 38.5 {mu}m thick anodic coating provided a 143% increase in compressive strength. Finite-element analyses were used to illustrate the dependence of the compressive strength and failure mechanism on the thickness of the anodic coating. At low thicknesses the microtruss strength is dictated by global bucking of the internal struts. However, at higher thicknesses the compressive strength is controlled by coating fracture and local deformation in the hinge region of the struts. Regardless of the failure mechanism, the compressive strength of the composite microtruss increased with increasing anodic coating thickness, with very little corresponding weight penalty.

  4. Structural ceramic coatings in composite microtruss cellular materials

    International Nuclear Information System (INIS)

    Graphical abstract: The compressive strength increase per unit sleeve thickness of Al cores reinforced with Al2O3 sleeves is lower than the corresponding strength increase when the same cores are reinforced with nanocrystalline Ni (n-Ni) sleeves (left). However, because anodizing is a transformative surface treatment, the Al2O3 coating was able to achieve this performance increase with little overall weight penalty (right). Display Omitted Highlights: → A new type of metal/ceramic microtruss cellular composite has been created. → Reinforcing sleeves of Al2O3 were deposited on low density Al microtruss cores. → Significant compressive strength increases were seen at virtually no weight penalty. → Failure mechanisms were studied by electron microscopy and finite element analysis. → Buckling, sleeve wrinkling, and coating fracture dictated the compressive strength. - Abstract: In the present study, anodizing was used to produce Al2O3 coatings in a conventional 3003 aluminum alloy microtruss core; a 38.5 μm thick anodic coating provided a 143% increase in compressive strength. Finite-element analyses were used to illustrate the dependence of the compressive strength and failure mechanism on the thickness of the anodic coating. At low thicknesses the microtruss strength is dictated by global bucking of the internal struts. However, at higher thicknesses the compressive strength is controlled by coating fracture and local deformation in the hinge region of the struts. Regardless of the failure mechanism, the compressive strength of the composite microtruss increased with increasing anodic coating thickness, with very little corresponding weight penalty.

  5. Research on toughening mechanisms of alumina matrix ceramic composite materials improved by rare earth additive

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xihua; LIU Changxia; LI Musen; ZHANG Jianhua

    2008-01-01

    Mixed rare earth elements were incorporated into alumina ceramic materials. Hot-pressing was used to fabricate alumina matrix composites in nitrogen atmosphere protection. Microstructures and mechanical properties of the composites were tested. It was indicated that the bending strength and fracture toughness of alumina matrix ceramic composites sintered at 1550℃ and 28 Mpa for 30 min were improved evidently. Besides mixed rare earth elements acting as a toughening phase, AlTiC master alloys were also added in as sintering assistants, which could prompt the formation of transient liquid phase, and thus nitrides of rare earth elements were produced. All of the above were beneficial for improving the mechanical properties of alumina matrix ceramic composites.

  6. Toward virtual ceramic composites

    OpenAIRE

    Genet, Martin; LADEVEZE, Pierre; LUBINEAU, Gilles

    2016-01-01

    A first step toward a multi-scale and multi-physic model --a virtual material-- for self-healing ceramic matrix composites is presented. Each mechanism --mechanical, chemical-- that act on the material's lifetime at a given scale --fibre, yarn-- is introduced in a single modeling framework, aimed at providing powerful prediction tools.

  7. The Influence of Tool Composite's Structure During Process of Diamond Grinding of Ceramic Materials

    Directory of Open Access Journals (Sweden)

    Gawlik Józef

    2014-12-01

    Full Text Available This paper presents the results of the tests performed during the grinding process of the ceramic materials: – polycrystalline ceramics (Zirconium ZrO2 and mono-crystalline ceramics (sapphire α-Al2O3 by the diamond tools. Studies have shown that the concentration (thickening of the tool composite changes the tool's pore structure when using suitable wetted adamantine additives. Such modified composite has positive impact on tribological properties of the subsurface layer of the machined components. This is manifested by the reduction of the surface roughness and reduction of the vibration amplitude of the coefficient of friction. The possibilities of the positive effects when using wetted additives on the tool's composite during the pressing (briquetting stage confirm the study results.

  8. Application of Technogenic-Raw Material and Burning Out Additive in Composite Ceramic System

    Directory of Open Access Journals (Sweden)

    Olga KIZINIEVIČ

    2012-09-01

    Full Text Available The investigation of the composite ceramic system containing easily fusible hydro-micous clay, technogenic finely dispersed raw material, and burning out waste additive is presented in the article. The properties of the raw materials used are described in the paper. The obtained ceramic bodies were burned at 1000 °C and 1050 °C temperatures, keeping at the highest burning temperature for 4 h. The analysis of physical-mechanical properties of composite ceramics (density, compressive strength, water absorption, its structural parameters (effective and total open porosity, reserve of pore volume, relative wall thickness of the pores and capillaries, and X-ray diffraction analysis was performed. The interdependencies between some structural parameters are described by empirical equations. DOI: http://dx.doi.org/10.5755/j01.ms.18.3.2443

  9. Tensile behavior of glass/ceramic composite materials at elevated temperatures

    Science.gov (United States)

    Mandell, J. F.; Grande, D. H.; Jacobs, J.

    1987-01-01

    This paper describes the tensile behavior of high-temperature composite materials containing continuous Nicalon ceramic fiber reinforcement and glass and glass/ceramic matrices. The longitudinal properties of these materials can approach theoretical expectations for brittle matrix composites, failing at a strength and ultimate strain level consistent with those of the fibers. The brittle, high-modulus matrices result in a nonlinear stress-strain curve due to the onset of stable matrix cracking at 10 to 30 percent of the fiber strain to failure, and at strains below this range in off-axis plies. Current fibers and matrices can provide attractive properties well above 1000 C, but composites experience embrittlement in oxidizing atmospheres at 800 to 1000 C due to oxidation of a carbon interface reaction layer.The oxidation effect greatly increases the interface bond strength, causing composite embrittlement.

  10. Preparation and Photocatalytic Property of TiO2/Diatomite-Based Porous Ceramics Composite Materials

    Directory of Open Access Journals (Sweden)

    Shuilin Zheng

    2012-01-01

    Full Text Available The diatomite-based porous ceramics was made by low-temperature sintering. Then the nano-TiO2/diatomite-based porous ceramics composite materials were prepared by hydrolysis deposition method with titanium tetrachloride as the precursor of TiO2 and diatomite-based porous as the supporting body of the nano-TiO2. The structure and microscopic appearance of nano-TiO2/diatomite-based porous ceramics composite materials was characterized by XRD and SEM. The photocatalytic property of the composite was investigated by the degradation of malachite green. Results showed that, after calcination at 550°C, TiO2 thin film loaded on the diatomite-based porous ceramics is anatase TiO2 and average grain size of TiO2 is about 10 nm. The degradation ratio of the composite for 5 mg/L malachite green solution reached 86.2% after irradiation for 6 h under ultraviolet.

  11. A bulk metal/ceramic composite material with a cellular structure

    Institute of Scientific and Technical Information of China (English)

    ZHAO Zhankui; YAO Kefu; LI Jingfeng

    2006-01-01

    A bulk metal/ceramic composite material with a honeycomb-like micro-cell structure has been prepared by sintering the spherical Al90Mn9Ce1 alloy powders clad by Al2O3 nano-powder with the spark plasma sintering (SPS) technique. The as-prepared material consists of Al90Mn9Ce1 alloy cell and closed Al2O3 ceramic cell wall. The diameter of the cells is about 20―40 μm, while a thickness of the cell wall is about 1―2 μm. The ultimate compressive strength of the as-sintered materials is about 514 MPa, while its fracture strain is up to about 0.65 %. This composite material might possess good anti-corrosion, thermal endurance and other potential properties due to its unique microstructure. The result shows that the Al90Mn9Ce1/Al2O3 composite powders can be sintered by spark plasma sintering technique despite the large difference in their sintering temperature. This work offers a way of designing and preparing metal/ceramic composite material with functional property.

  12. Influence of Composite Phosphate Inorganic Antibacterial Materials Containing Rare Earth on Activated Water Property of Ceramics

    Institute of Scientific and Technical Information of China (English)

    梁金生; 梁广川; 祁洪飞; 吴子钊; 冀志江; 金宗哲

    2004-01-01

    Antibacterial ceramic was prepared by doping enamel slurry with composite phosphate inorganic antibacterial materials containing rare earth (inorganic antibacterial additives), and then the mechanisms for activating water and improving seed germinative property were tested by nuclear magnetic resonance (NMR) and the method of testing oxygen dissolved in activated water. Results show that the half peak width of 17O-NMR for tap water activated by the antibacterial ceramic drops from 115.36 to 99.15 Hz, and oxygen concentrations of activated water increase by 20%, germinate rate of horsebean and earthnut seeds increases by 12.5% and 7.5%, respectively. Therefore antibacterial ceramic doped enamel slurry with inorganic antibacterial additives containing rare earth can reduce the volume of clusters of water molecules, improve activation of tap water, and promote plant seeds germinate.

  13. Synthesis of steel slag ceramics:chemical composition and crystalline phases of raw materials

    Institute of Scientific and Technical Information of China (English)

    Li-hua Zhao; Wei Wei; Hao Bai; Xu Zhang; Da-qiang Cang

    2015-01-01

    Two types of porcelain tiles with steel slag as the main raw material (steel slag ceramics) were synthesized based on the CaO–Al2O3–SiO2 and CaO–MgO–SiO2 systems, and their bending strengths up to 53.47 MPa and 99.84 MPa, respectively, were obtained. The presence of anorthite,α-quartz, magnetite, and pyroxene crystals (augite and diopside) in the steel slag ceramics were very different from the composition of traditional ceramics. X-ray diffraction (XRD) and electron probe X-ray microanalysis (EPMA) results illustrated that the addition of steel slag reduced the temperature of extensive liquid generation and further decreased the firing temperature. The considerable contents of glass-modifying oxide liquids with rather low viscosities at high temperature in the steel slag ceramic adobes promoted element diffusion and crystallization. The results of this study demonstrated a new approach for extensive and effective recycling of steel slag.

  14. 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.

  15. Surface properties of ceramic/metal composite materials for thermionic converter applications

    International Nuclear Information System (INIS)

    Ceramic/metal composite electrode materials are of interest for thermionic energy conversion (TEC) applications for several reasons. These materials consist of submicron metal fibers or islands in an oxide matrix and therefore provide a basis for fabricating finely structured electrodes, with projecting or recessed metallic regions for more efficient electron emission or collection. Furthermore, evaporation and surface diffusion of matrix oxides may provide oxygen enhancement of cesium adsorption and work function lowering at both the collecting and emitting electrode surfaces of the TEC. Finally, the high work function oxide matrix or oxide-metal interfaces may provide efficient surface ionization of cesium for space-charge reduction in the device. The authors are investigating two types of ceramic/metal composite materials. One type is a directionally solidified eutectic consisting of a bulk oxide matrix such as UO2 or stabilized ZrO2 with parallel metal fibers (W) running through the oxide being exposed at the surface by cutting perpendicular to the fiber direction. The second type of material, called a surface eutectic, consists of a refractory substrate (Mo) with a thin layer of deposited and segregated material (Mo-Cr2O3-A12O3) on the surface. The final configuration of this layer is an oxide matrix with metallic islands scattered throughout

  16. Low-Activation structural ceramic composites for fusion power reactors: materials development and main design issues

    International Nuclear Information System (INIS)

    This paper is devoted to the development of advanced Low-Activation Materials (LAMs) with favourable short-term activation characteristics for the use as structural materials in a fusion power reactor (in order to reduce the risk associated with a major accident, in particular those related with radio-isotopes release in the environment), and to try to approach the concept of an inherently safe reactor. LA Ceramics Composites (LACCs) are the most promising LAMs because of their relatively good thermo-mechanical properties. At present, SiC/SiC composite is the only LACC considered by the fusion community, and therefore is the one having the most complete data base. The preliminary design of a breeding blanket using SiC/SiC as structural material indicated that significant improvement of its thermal conductivity is required. (orig.)

  17. Low-activation structural ceramic composites for fusion power reactors: materials development and main design issues

    International Nuclear Information System (INIS)

    Development of advanced Low-Activation Materials (LAMs) with favourable short-term activation characteristics is discussed, for the use as structural materials in a fusion power reactor (in order to reduce the risk associated with a major accident, in particular those related with radio-isotopes release in the environment), and to try to approach the concept of an inherently safe reactor. LA Ceramics Composites (LACCs) are the most promising LAMs because of their relatively good thermo-mechanical properties. At present, SiC/SiC composite is the only LACC considered by the fusion community, and therefore is the one having the most complete data base. The preliminary design of a breeding blanket using SiC/SiC as structural material indicated that significant improvement of its thermal conductivity is required. (author) 11 refs.; 3 figs

  18. Tauro: a ceramic composite structural material self-cooled Pb-17Li breeder blanket concept

    International Nuclear Information System (INIS)

    The use of a low-activation (LA) ceramic composite (CC) as structural material appears essential to demonstrate the potential of fusion power reactors for being inherently or, at least, passively safe. Tauro is a self-cooled Pb-17Li breeder blanket with a SiC/SiC composite as structure. This study determines the required improvements for existing industrial LA composites (mainly SiC/SiC) in order to render them acceptable for blanket operating conditions. 3D SiC/SiC CC, recently launched on the market, is a promising candidate. A preliminary evaluation of a possible joining technique for SiC/SiC is also described. (orig.)

  19. The diametral tensile strength and hydrostability of polymer-ceramic nano-composite (pcnc) material prototypes

    Science.gov (United States)

    Yepez, Johanna

    Statement of the problem: There is a weak connection between the filler and the resin matrix of dental composites caused primarily by hydrolysis of silane coupling agent, therefore, jeopardizing the mechanical properties of the dental restorations. Purpose: The purpose of this study was to compare the diametral tensile strength (DTS) of a nano-mechanically bonded polymer ceramic nano composite (pcnc) versus the chemically bonding prototype polymer ceramic nano composite (pcnc) fabricated by using hydrolytically stable interphase. Materials and Methods: Composites were made with 60wt % filler, 38% triethyleneglycol dimethacrylate (TEDGMA), 1% camphorquinone (CQ) and 1% 2-(dimethylamino) ethyl methacrylate (DMAEMA). Tests for DTS were performed using a universal testing machine. The disk-shaped specimens were loaded in compression between two supporting plates at a crosshead speed of 0.5 mm/min until fracture. The samples, measuring 3 mm in height and 6 mm in diameter, were produced in a round stainless steel (SS) mold. A total of 144 samples were created. Groups of 48 samples were made for each of three different fillers. Specimens were soaked in artificial saliva at 37° for four time periods, dry(t=0), 1 day, 7 days, 28 days). At the end of each soaking time DTS tests were performed. Results: There where statistically significant differences in the DTS between the filler groups and the soaking times (p=dental composites is a detrimental factor in the mechanical behavior. The silanation of the filler particles have a positive influence on the mechanical properties of dental composites but the hydrolysis of the silane coupling agent can dramatically reduce the average lifetime of dental composites.

  20. Calcium phosphate/microgel composites for 3D powderbed printing of ceramic materials.

    Science.gov (United States)

    Birkholz, Mandy-Nicole; Agrawal, Garima; Bergmann, Christian; Schröder, Ricarda; Lechner, Sebastian J; Pich, Andrij; Fischer, Horst

    2016-06-01

    Composites of microgels and calcium phosphates are promising as drug delivery systems and basic components for bone substitute implants. In this study, we synthesized novel composite materials consisting of pure β-tricalcium phosphate and stimuli-responsive poly(N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate-co-vinylimidazole) microgels. The chemical composition, thermal properties and morphology for obtained composites were extensively characterized by Fourier transform infrared, X-ray photoelectron spectroscopy, IGAsorp moisture sorption analyzer, thermogravimetric analysis, granulometric analysis, ESEM, energy dispersive X-ray spectroscopy and TEM. Mechanical properties of the composites were evaluated by ball-on-three-balls test to determine the biaxial strength. Furthermore, initial 3D powderbed-based printing tests were conducted with spray-dried composites and diluted 2-propanol as a binder to evaluate a new binding concept for β-tricalcium phosphate-based granulates. The printed ceramic bodies were characterized before and after a sintering step by ESEM. The hypothesis that the microgels act as polymer adhesive agents by efficient chemical interactions with the β-tricalcium phosphate particles was confirmed. The obtained composites can be used for the development of new scaffolds. PMID:25870955

  1. Data on post irradiation experiments of heat resistant ceramic composite materials. PIE for 97M-13A

    International Nuclear Information System (INIS)

    The research on the radiation damage mechanism of heat resistant ceramic composite materials is one of the research subjects of the innovative basic research in the field of high temperature engineering, using the High Temperature engineering Test Reactor (HTTR). Three series of irradiation tests on the heat resistant ceramic composite materials, first to third irradiation test program, were carried out using the Japan Material Testing Reactor (JMTR). This is a summary report on the first irradiation test program; irradiation induced dimensional change, thermal expansion coefficient, X-ray diffraction and γ-ray spectrum are reported. (author)

  2. Data on post irradiation experiments of heat resistant ceramic composite materials. PIE for 97M-13A

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Shin-ichi; Ishihara, Masahiro; Souzawa, Shizuo [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Sekino, Hajime [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The research on the radiation damage mechanism of heat resistant ceramic composite materials is one of the research subjects of the innovative basic research in the field of high temperature engineering, using the High Temperature engineering Test Reactor (HTTR). Three series of irradiation tests on the heat resistant ceramic composite materials, first to third irradiation test program, were carried out using the Japan Material Testing Reactor (JMTR). This is a summary report on the first irradiation test program; irradiation induced dimensional change, thermal expansion coefficient, X-ray diffraction and {gamma}-ray spectrum are reported. (author)

  3. Mechanical Properties of a new Dental all-ceramic Material-zirconia Toughened Nanometer-ceramic Composite

    Institute of Scientific and Technical Information of China (English)

    CHAI Feng; XU Ling; CHAO Yong-lie; LIAO Yun-mao; ZHAO Yi-min

    2003-01-01

    Objectives:All-ceramic dental restorations are attractive to the dental community because of their advantages.But they're also challenged by relatively low flexural strength and intrinsic poor resistance to fracture.This paper aims to investigate mechanical properties of a new dental all-ceramic material, i.e. zirconia toughened nanometer-ceramic composite (α-Al2O3/nZrO2).Methods:α-Al2O3/nZrO2 ceramics powder (W) was processed with combined methods of chemical co-precipitation method and ball milling. Scanning electron microscopy (SEM)was used to determine the particle size distribution and to characterize the particle morphology of the powders. Four kinds of powders with different ZrO2 content (5wt%, 10wt%, 15wt% and 20wt%) were prepared by using α-Al2O3 powder to dilute the higher ZrO2 content powder (W). The ceramic matrix compacts were made by slip-casting technique and sintering to 1 200~1 600 ℃. The flexural strength and the fracture toughness of the matrix materials were measured via three-point bending test and single-edge notch beam methods, respectively.Results:1) The particle distribution of the Al2O3/nZrO2 powder ranged from 0.02~3.0 μm, with the superfine particles almost accounting for 20%;2) There is a significant difference of flexural strength (P<0.05) between the groups with 1 450 ℃ and 1 600 ℃ sintering temperature and 1 200 ℃;3) There is a significant difference of flexural strength (P<0.05) between different zirconia volume fraction groups with the same sintering temperature, the ceramic matrix samples with higher nZrO2 (W) content had much better mechanical properties than those of pure α-Al2O3 ceramics.Conclusions:The studied nanometer α-Al2O3/nZrO2 powder was homogeously distributed within the matrix and had reasonable powder-size gradation to improve mechanical properties of ceramics.%目的:口腔全瓷修复体以其独特优越性受到医患青睐,但脆性问题一直限制其应用范围及使用可靠性.本研

  4. Nondestructive evaluation of ceramic and metal matrix composites for NASA's HITEMP and enabling propulsion materials programs

    Science.gov (United States)

    Generazio, Edward R.

    1992-01-01

    In a preliminary study, ultrasonic, x-ray opaque, and fluorescent dye penetrants techniques were used to evaluate and characterize ceramic and metal matrix composites. Techniques are highlighted for identifying porosity, fiber alignment, fiber uniformity, matrix cracks, fiber fractures, unbonds or disbonds between laminae, and fiber-to-matrix bond variations. The nondestructive evaluations (NDE) were performed during processing and after thermomechanical testing. Specific examples are given for Si3N4/SiC (SCS-6 fiber), FeCrAlY/Al2O3 fibers, Ti-15-3/SiC (SCS-6 fiber) materials, and Si3N4/SiC (SCS-6 fiber) actively cooled panel components. Results of this study indicate that the choice of the NDE tools to be used can be optimized to yield a faithful and accurate evaluation of advanced composites.

  5. Composite materials based on porous ceramic preform infiltrated by aluminium alloy

    OpenAIRE

    Nagel, A.; A. J. Nowak; M. Kremzer; L.A. Dobrzański

    2007-01-01

    Purpose: The goal of this project is the optimization of manufacturing technology of the ceramic preforms basedon Al2O3 powder manufactured by the pressure infiltration method with liquid metal alloy.Design/methodology/approach: Ceramic preforms were manufactured by the method of sintering of ceramicpowder. The preform material consists of powder Condea Al2O3 CL 2500, however, as the forming factor ofthe structure of canals and pores inside the ceramic agglomerated framework the carbon fibers...

  6. Ceramic Laser Materials

    OpenAIRE

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

    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,...

  7. Investigation of Effects of Material Architecture on the Elastic Response of a Woven Ceramic Matrix Composite

    Science.gov (United States)

    Goldberg, Robert K.; Bonacuse, Peter J.; Mital, Subodh K.

    2012-01-01

    To develop methods for quantifying the effects of the microstructural variations of woven ceramic matrix composites on the effective properties and response of the material, a research program has been undertaken which is described in this paper. In order to characterize and quantify the variations in the microstructure of a five harness satin weave, CVI SiC/SiC, composite material, specimens were serially sectioned and polished to capture images that detailed the fiber tows, matrix, and porosity. Open source quantitative image analysis tools were then used to isolate the constituents and collect relevant statistics such as within ply tow spacing. This information was then used to build two dimensional finite element models that approximated the observed section geometry. With the aid of geometrical models generated by the microstructural characterization process, finite element models were generated and analyses were performed to quantify the effects of the microstructure and its variation on the effective stiffness and areas of stress concentration of the material. The results indicated that the geometry and distribution of the porosity appear to have significant effects on the through-thickness modulus. Similarly, stress concentrations on the outer surface of the composite appear to correlate to regions where the transverse tows are separated by a critical amount.

  8. Prediction of the functional properties of ceramic materials from composition using artificial neural networks

    OpenAIRE

    Scott, D. J.; Coveney, P. V.; Kilner, J. A.; Rossiny, J. C. H.; Alford, N. Mc N.

    2007-01-01

    We describe the development of artificial neural networks (ANN) for the prediction of the properties of ceramic materials. The ceramics studied here include polycrystalline, inorganic, non-metallic materials and are investigated on the basis of their dielectric and ionic properties. Dielectric materials are of interest in telecommunication applications where they are used in tuning and filtering equipment. Ionic and mixed conductors are the subjects of a concerted effort in the search for new...

  9. Alumina-based ceramic composite

    Science.gov (United States)

    Alexander, Kathleen B.; Tiegs, Terry N.; Becher, Paul F.; Waters, Shirley B.

    1996-01-01

    An improved ceramic composite comprising oxide ceramic particulates, nonoxide ceramic particulates selected from the group consisting of carbides, borides, nitrides of silicon and transition metals and mixtures thereof, and a ductile binder selected from the group consisting of metallic, intermetallic alloys and mixtures thereof is described. The ceramic composite is made by blending powders of the ceramic particulates and the ductile to form a mixture and consolidating the mixture of under conditions of temperature and pressure sufficient to produce a densified ceramic composite.

  10. A compact square loop patch antenna on high dielectric ceramic-PTFE composite material

    Science.gov (United States)

    Ullah, M. Habib; Islam, M. T.

    2013-10-01

    Design and prototyping of a low profile, compact square loop microstrip line fed miniature patch antenna on 1.9 mm thick ceramic-polytetrafluoroethylene (PTFE) high dielectric composite material substrate is presented in this paper. The measured -10 dB return loss bandwidths of the antenna are 300 MHz (0.75-1.05 GHz) and 800 MHz (2.4-3.2 GHz) with 3.4 dBi, 8.86 dBi and 7.42 dBi at 900 MHz, 2.5 GHz and 3.0 GHz, respectively. The measured symmetric and almost stable radiation pattern makes the proposed antenna suitable for RFID, GSM, ZIGBEE, WBAN, LR-WPAN etc. integrated mobile devices.

  11. Some metal-graphite and metal-ceramic composites for use as high energy brake lining materials

    Science.gov (United States)

    Bill, R. C.

    1974-01-01

    Materials were studied as candidates for development as potential new aircraft brake lining materials. These families were (1) copper-graphite composites; (2) nickel-graphite composites; (3) copper - rare-earth-oxide (gadolinium oxide (Gd2O3) or lanthanum oxide (La2O3)) composites and copper - rare-earth-oxide (La2O3) - rare-earth-fluoride (lanthanum fluoride (LaF3)) composites; (4) nickel - rare-earth-oxide composites and nickel - rare-earth-oxide - rare-earth-fluoride composites. For comparison purposes, a currently used metal-ceramic composite was also studied. Results showed that the nickel-Gd2O3 and nickel-La2O3-LaF3 composites were comparable or superior in friction and wear performance to the currently used composite and therefore deserve to be considered for further development.

  12. 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.

  13. Tantalum-Based Ceramics for Refractory Composites

    Science.gov (United States)

    Stewart, David A.; Leiser, Daniel; DiFiore, Robert; Kalvala, Victor

    2006-01-01

    A family of tantalum-based ceramics has been invented as ingredients of high-temperature composite insulating tiles. These materials are suitable for coating and/or permeating the outer layers of rigid porous (foam-like or fibrous) ceramic substrates to (1) render the resulting composite ceramic tiles impervious to hot gases and (2) enable the tiles to survive high heat fluxes at temperatures that can exceed 3,000 F ( 1,600 C).

  14. Ceramic materials for energy and environmental applications: Functionalizing of properties by tailored compositions

    DEFF Research Database (Denmark)

    Ivanova, Mariya; Ricote, Sandrine; Baumann, Stefan;

    2013-01-01

    protons, oxygen ions and/or electronic carriers, stability, etc. The present chapter will therefore consider the structural features of selected material classes, as well as the principles of transport in bulk and microporous solids. It will furthermore illustrate and discuss the effects of selected...... separation and ion/electron transport at the relevant operating conditions and stability ranges, improved electrical or ionic conductivities and permeation rates are required. That can be achieved by doping and substitution which are actors on a nano-scale that usually lead to macroscopic impacts. This...... additives and substituents on sinterability, electrical/electrochemical properties and stability of selected ceramic materials for energy and environmental applications. The material variety will cover ceramic materials with different crystal structures like fluorites, perovskites, pyrochlores, fergusonites...

  15. 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.

  16. Paper pulp waste—A new source of raw material for the synthesis of a porous ceramic composite

    Indian Academy of Sciences (India)

    Subrata Dasgupta; Swapan Kumar Das

    2002-10-01

    A synthetic porous ceramic composite material consisting of the mullite, cordierite and cristobalite phases is produced from a mixture of paper pulp waste and clay by reaction sintering at 1400°C. Physicomechanical properties such as bulk density, porosity, cold crushing strength and cold modulus of rupture have been studied. The presence of mullite, cordierite, cristobalite and quartz as major phases and montellecite, tatanite, forsterite and anorthite as minor phases have been confirmed by X-ray diffraction pattern. SEM studies revealed the presence of well developed needle shaped mullite and quartz crystals. The paper also discusses the possible uses of this type of porous composite material.

  17. Polymer-derived-SiCN ceramic/graphite composite as anode material with enhanced rate capability for lithium ion batteries

    Science.gov (United States)

    Graczyk-Zajac, M.; Fasel, C.; Riedel, R.

    2011-08-01

    We report on a new composite material in view of its application as a negative electrode in lithium-ion batteries. A commercial preceramic polysilazane mixed with graphite in 1:1 weight ratio was transformed into a SiCN/graphite composite material through a pyrolytic polymer-to-ceramic conversion at three different temperatures, namely 950 °C, 1100 °C and 1300 °C. By means of Raman spectroscopy we found successive ordering of carbon clusters into nano-crystalline graphitic regions with increasing pyrolysis temperature. The reversible capacity of about 350 mAh g-1 was measured with constant current charging/discharging for the composite prepared at 1300 °C. For comparison pure graphite and pure polysilazane-derived SiCN ceramic were examined as reference materials. During fast charging and discharging the composite material demonstrates enhanced capacity and stability. Charging and discharging in half an hour lead to about 200 and 10 mAh g-1, for the composite annealed at 1300 °C and pure graphite, respectively. A clear dependence between the final material capacity and pyrolysis temperature is found and discussed with respect to possible application in batteries, i.e. practical discharging potential limit. The best results in terms of capacity recovered under 1 V and high rate capability were also obtained for samples synthesized at 1300 °C.

  18. Small-angle scattering in materials science - a short review of applications in alloys, ceramics and composite materials

    International Nuclear Information System (INIS)

    Since the early days of small-angle scattering (SAS), this technique has been used to characterize the structure of solid materials on the nanometer scale. Some recent developments in this field will be reviewed, focusing on alloys, ceramics and (nano-) composite materials. The large field of SAS from polymeric systems will not be covered. Classical applications of SAS are the characterization of pores or precipitates in alloys, for instance. In more recent years, a range of new applications for X-ray SAS has emerged owing to the availability of more and more brilliant (synchrotron) X-ray sources. Examples include grazing-incidence SAXS, used increasingly to characterize nano-structured surfaces on semiconductors and also on other materials. The use of a narrow X-ray beam also allows the investigation of extremely inhomogeneous or hierarchically structured materials by scanning SAXS. In this approach, the specimen is moved step by step across an X-ray beam with a diameter of a few micrometers (or even less), collecting a SAXS pattern at each step. In neutron SAS, the systematic use of magnetic cross-sections has brought considerable progress in the study of magnetic nano-particles or nano-composites. Single crystalline or textured materials are being studied under several orientations with respect to the primary beam to yield three-dimensional (neutron or X-ray) SAS patterns. In many cases, SAS is combined with other techniques, such as electron microscopy, spectroscopy or mechanical characterization, the most elegant being an in-situ combination. A number of recent examples for the above-mentioned approaches will be given. (orig.)

  19. Study on Low Resistance PTC Ceramic Material

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The low resistance PTC ceramic thermistor material with excellent eleectrical properties are successfully fabricated by raw materials at industrial range made in our country on the study of its composition expression and fabrication process by using the addition of Nb, La, Y, Ta , microstructure regulator BN and ASTL phase .The composition and its fabrication method are studied.The relation of electrical properties of the PTC ceramic material to its composition expression and its related electrical properties are discussed.

  20. 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.

  1. Simplex Ceramic Matrix Composite Turbine Blisk Testing

    Science.gov (United States)

    Mash, Matt; McConnaughey, Helen V. (Technical Monitor)

    2001-01-01

    The purpose of this presentation is to discuss the testing and demonstration of the Ceramic Matrix Composite Turbine Blisk. Also discussed are material damping, fatigue life, damage to trailing edges, performance, unsteady blade loading, and stress.

  2. Recycling of glass fibers from fiberglass polyester waste composite for manufacture glass-ceramic materials

    OpenAIRE

    López Gómez, Félix Antonio; Martín, M. Isabel; García Díaz, Irene; Rodríguez, O.; Alguacil, Francisco José; Romero, M.

    2012-01-01

    This work presents the feasibility of reusing a glass fiber resulting from the thermolysis and gasification of waste composites to obtain glass-ceramic tiles. Polyester fiberglass (PFG) waste was treated at 550˚C for 3 h in a 9.6 dm3 thermolytic reactor. This process yielded an oil (≈24 wt%), a gas (≈8 wt%) and a solid residue (≈68 wt%). After the polymer has been removed, the solid residue is heated in air to oxidize residual char and remove surface contamination. The cleaning fibers were co...

  3. Studying the sintering behavior of BeOx-SiC1-x Composite ceramic Material

    Science.gov (United States)

    Issa, Tarik Talib

    2011-12-01

    The sintering behavior for BeO-SiC compacts composite ceramic at different sintering temperatures in air were conducted, resulting data indicated that the percentage of SiC (Wt% 5) sintered at 800 C° lead to higher sintering density of (1.80 gm/cm3). The x-ray diffraction pattern analysis indicated nothing change concerning the crystal structure. Microstructure development has been studied as a function SiC content. Silicon carbide found to be suppressed the sinter ability of the matrix BeO powder.

  4. In vitro degradation and cell response of calcium carbonate composite ceramic in comparison with other synthetic bone substitute materials

    International Nuclear Information System (INIS)

    The robust calcium carbonate composite ceramics (CC/PG) can be acquired by fast sintering calcium carbonate at a low temperature (650 °C) using a biocompatible, degradable phosphate-based glass (PG) as sintering agent. In the present study, the in vitro degradation and cell response of CC/PG were assessed and compared with 4 synthetic bone substitute materials, calcium carbonate ceramic (CC), PG, hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) ceramics. The degradation rates in decreasing order were as follows: PG, CC, CC/PG, β-TCP, and HA. The proliferation of rat bone mesenchymal stem cells (rMSCs) cultured on the CC/PG was comparable with that on CC and PG, but inferior to HA and β-TCP. The alkaline phosphatase (ALP) activity of rMSCs on CC/PG was lower than PG, comparable with β-TCP, but higher than HA. The rMSCs on CC/PG and PG had enhanced gene expression in specific osteogenic markers, respectively. Compared to HA and β-TCP, the rMSCs on the CC/PG expressed relatively lower level of collagen I and runt-related transcription factor 2, but showed more considerable expression of osteopontin. Although CC, PG, HA, and β-TCP possessed impressive performances in some specific aspects, they faced extant intrinsic drawbacks in either degradation rate or mechanical strength. Based on considerable compressive strength, moderate degradation rate, good cell response, and being free of obvious shortcoming, the CC/PG is promising as another choice for bone substitute materials. - Highlights: • A calcium carbonate composite ceramic (CC/PG) was acquired. • The in vitro degradation and cell response of CC/PG were compared to 4 materials. • The CC/PG showed moderate degradation rate. • The CC/PG exhibited good cell response. • The CC/PG was free of obvious drawback compared to other materials

  5. In vitro degradation and cell response of calcium carbonate composite ceramic in comparison with other synthetic bone substitute materials

    Energy Technology Data Exchange (ETDEWEB)

    He, Fupo [Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182 (China); Zhang, Jing [School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Yang, Fanwen; Zhu, Jixiang; Tian, Xiumei [Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182 (China); Chen, Xiaoming, E-mail: xmchenw@126.com [Department of Biomedical Engineering, School of Basic Sciences, Guangzhou Medical University, Guangzhou 510182 (China)

    2015-05-01

    The robust calcium carbonate composite ceramics (CC/PG) can be acquired by fast sintering calcium carbonate at a low temperature (650 °C) using a biocompatible, degradable phosphate-based glass (PG) as sintering agent. In the present study, the in vitro degradation and cell response of CC/PG were assessed and compared with 4 synthetic bone substitute materials, calcium carbonate ceramic (CC), PG, hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) ceramics. The degradation rates in decreasing order were as follows: PG, CC, CC/PG, β-TCP, and HA. The proliferation of rat bone mesenchymal stem cells (rMSCs) cultured on the CC/PG was comparable with that on CC and PG, but inferior to HA and β-TCP. The alkaline phosphatase (ALP) activity of rMSCs on CC/PG was lower than PG, comparable with β-TCP, but higher than HA. The rMSCs on CC/PG and PG had enhanced gene expression in specific osteogenic markers, respectively. Compared to HA and β-TCP, the rMSCs on the CC/PG expressed relatively lower level of collagen I and runt-related transcription factor 2, but showed more considerable expression of osteopontin. Although CC, PG, HA, and β-TCP possessed impressive performances in some specific aspects, they faced extant intrinsic drawbacks in either degradation rate or mechanical strength. Based on considerable compressive strength, moderate degradation rate, good cell response, and being free of obvious shortcoming, the CC/PG is promising as another choice for bone substitute materials. - Highlights: • A calcium carbonate composite ceramic (CC/PG) was acquired. • The in vitro degradation and cell response of CC/PG were compared to 4 materials. • The CC/PG showed moderate degradation rate. • The CC/PG exhibited good cell response. • The CC/PG was free of obvious drawback compared to other materials.

  6. Ceramic Laser Materials

    Energy Technology Data Exchange (ETDEWEB)

    Soules, T F; Clapsaddle, B J; Landingham, R L; Schaffers, K I

    2005-02-15

    Transparent ceramic materials have several major advantages over single crystals in laser applications, not the least of which is the ability to make large aperture parts in a robust manufacturing process. After more than a decade of working on making transparent YAG:Nd, Japanese workers have recently succeeded in demonstrating samples that performed as laser gain media as well as their single crystal counterparts. Since then several laser materials have been made and evaluated. For these reasons, developing ceramic laser materials is the most exciting and futuristic materials topic in today's major solid-state laser conferences. We have established a good working relationship with Konoshima Ltd., the Japanese producer of the best ceramic laser materials, and have procured and evaluated slabs designed by us for use in our high-powered SSHCL. Our measurements indicate that these materials will work in the SSHCL, and we have nearly completed retrofitting the SSHCL with four of the largest transparent ceramic YAG:Nd slabs in existence. We have also begun our own effort to make this material and have produced samples with various degrees of transparency/translucency. We are in the process of carrying out an extensive design-of-experiments to establish the significant process variables for making transparent YAG. Finally because transparent ceramics afford much greater flexibility in the design of lasers, we have been exploring the potential for much larger apertures, new materials, for example for the Mercury laser, other designs for SSHL, such as, edge pumping designs, slabs with built in ASE suppression, etc. This work has just beginning.

  7. Structural properties of a bone-ceramic composite as a promising material in spinal surgery

    International Nuclear Information System (INIS)

    The paper describes the results of in vitro tests of composite bone-ceramic implants and procedures for modifying implant surfaces to enhance osteogenesis. Analysis of CBCI ESs demonstrated that they have a porous structure with the mean longitudinal pore size of 70 µm and the mean transverse pore size of 46 µm; surface pores are open, while inner pores are closed. Elemental analysis of the CBCI surface demonstrates that CBCIs are composed of aluminum and zirconium oxides and contain HA inclusions. Profilometry of the CBCI ES surface revealed the following deviations: the maximum deviation of the profile in the sample center is 15 µm and 16 µm on the periphery, while the arithmetical mean and mean square deviations of the profile are 2.65 and 3.4 µm, respectively. In addition, CBCI biodegradation products were pre-examined; a 0.9% NaCl solution was used as a comparison group. Potentially toxic and tissue accumulated elements, such as cadmium, cobalt, mercury, and lead, are present only in trace amounts and have no statistically significant differences with the comparison group, which precludes their potential toxic effects on the macroorganism. Ceramic-based CBCI may be effective and useful in medicine for restoration of the anatomic integrity and functions of the bone tissue

  8. Structural properties of a bone-ceramic composite as a promising material in spinal surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kirilova, I. A., E-mail: IKirilova@mail.ru; Sadovoy, M. A.; Podorozhnaya, V. T., E-mail: VPodorognaya@niito.ru; Taranov, O. S. [Novosibirsk Research Institute of Traumatology and Orthopedics n.a. Ya.L. Tsivyan, Novosibirsk (Russian Federation); Klinkov, S. V.; Kosarev, V. F. [Christianovich Institute of Theoretical and Applied Mechanics, SB RAS, Novosibirsk (Russian Federation); Shatskaya, S. S. [Institute of Solid State Chemistry and Mechanochemistry, SB RAS, Novosibirsk (Russian Federation)

    2015-11-17

    The paper describes the results of in vitro tests of composite bone-ceramic implants and procedures for modifying implant surfaces to enhance osteogenesis. Analysis of CBCI ESs demonstrated that they have a porous structure with the mean longitudinal pore size of 70 µm and the mean transverse pore size of 46 µm; surface pores are open, while inner pores are closed. Elemental analysis of the CBCI surface demonstrates that CBCIs are composed of aluminum and zirconium oxides and contain HA inclusions. Profilometry of the CBCI ES surface revealed the following deviations: the maximum deviation of the profile in the sample center is 15 µm and 16 µm on the periphery, while the arithmetical mean and mean square deviations of the profile are 2.65 and 3.4 µm, respectively. In addition, CBCI biodegradation products were pre-examined; a 0.9% NaCl solution was used as a comparison group. Potentially toxic and tissue accumulated elements, such as cadmium, cobalt, mercury, and lead, are present only in trace amounts and have no statistically significant differences with the comparison group, which precludes their potential toxic effects on the macroorganism. Ceramic-based CBCI may be effective and useful in medicine for restoration of the anatomic integrity and functions of the bone tissue.

  9. Glass, Ceramics, and Composites

    International Nuclear Information System (INIS)

    Many studies of plutonium in glass and ceramics have taken place in the thirty years covered by this book. These studies have led to a substantial understanding, arising from fundamental research of actinides in solids and research and development in three technical fields: immobilization of the high level wastes (HLW) from commercial nuclear power plants and processing of nuclear weapons materials, environmental restoration in the nuclear weapons complex and, most recently, the immobilization of weapons-grade plutonium as a result of disarmament activities

  10. Glass and Glass-Ceramic Materials from Simulated Composition of Lunar and Martian Soils: Selected Properties and Potential Applications

    Science.gov (United States)

    Ray, C. S.; Sen, S.; Reis, S. T.; Kim, C. W.

    2005-01-01

    In-situ resource processing and utilization on planetary bodies is an important and integral part of NASA's space exploration program. Within this scope and context, our general effort is primarily aimed at developing glass and glass-ceramic type materials using lunar and martian soils, and exploring various applications of these materials for planetary surface operations. Our preliminary work to date have demonstrated that glasses can be successfully prepared from melts of the simulated composition of both lunar and martian soils, and the melts have a viscosity-temperature window appropriate for drawing continuous glass fibers. The glasses are shown to have the potential for immobilizing certain types of nuclear wastes without deteriorating their chemical durability and thermal stability. This has a direct impact on successfully and economically disposing nuclear waste generated from a nuclear power plant on a planetary surface. In addition, these materials display characteristics that can be manipulated using appropriate processing protocols to develop glassy or glass-ceramic magnets. Also discussed in this presentation are other potential applications along with a few selected thermal, chemical, and structural properties as evaluated up to this time for these materials.

  11. Characterization and thermal performance of nitrate mixture/SiC ceramic honeycomb composite phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    The composite phase change material (PCM) comprised of the nitrate mixture KNO3/NaNO3 (50:50 mol%) and SiC ceramic honeycomb (SCH) was prepared by vacuum infiltration. The SEM (scanning electron microscope) images indicated that the nitrate mixture was dispersed and embedded in the porous structures of the SiC wall. The DSC (differential scanning calorimeter) results showed that the melting and freezing temperatures of composite PCM shifted slightly compared with those of pure PCM, and the melting and freezing latent heats of composite PCM were 72.8 J/g and 70.3 J/g, respectively. The thermal performances of the pure PCM and the composite PCMs with different mass fractions of SCH were experimentally investigated. The results showed that the heat storage and release rates increased with the increase of the mass fraction of SCH in the composite PCM. In comparison with the pure PCM, the heat storage and release time of the composite PCM with 30 wt% SCH were reduced by 52.8% and 58.3%, respectively. - Highlights: • Nitrate mixture/SCH composite PCM was prepared by vacuum infiltration. • PCM was embedded and dispersed in the porous structure of SiC wall. • SCH induced slight shift of the melting and freezing temperature of PCM. • The heat storage and release rates of PCM were improved by SCH

  12. Metal-Matrix/Hollow-Ceramic-Sphere Composites

    Science.gov (United States)

    Baker, Dean M.

    2011-01-01

    A family of metal/ceramic composite materials has been developed that are relatively inexpensive, lightweight alternatives to structural materials that are typified by beryllium, aluminum, and graphite/epoxy composites. These metal/ceramic composites were originally intended to replace beryllium (which is toxic and expensive) as a structural material for lightweight mirrors for aerospace applications. These materials also have potential utility in automotive and many other terrestrial applications in which there are requirements for lightweight materials that have high strengths and other tailorable properties as described below. The ceramic component of a material in this family consists of hollow ceramic spheres that have been formulated to be lightweight (0.5 g/cm3) and have high crush strength [40.80 ksi (.276.552 MPa)]. The hollow spheres are coated with a metal to enhance a specific performance . such as shielding against radiation (cosmic rays or x rays) or against electromagnetic interference at radio and lower frequencies, or a material to reduce the coefficient of thermal expansion (CTE) of the final composite material, and/or materials to mitigate any mismatch between the spheres and the matrix metal. Because of the high crush strength of the spheres, the initial composite workpiece can be forged or extruded into a high-strength part. The total time taken in processing from the raw ingredients to a finished part is typically 10 to 14 days depending on machining required.

  13. Lightweight high performance ceramic material

    Science.gov (United States)

    Nunn, Stephen D [Knoxville, TN

    2008-09-02

    A sintered ceramic composition includes at least 50 wt. % boron carbide and at least 0.01 wt. % of at least one element selected from the group consisting of Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy Ho, Er, Tm, Yb, and Lu, the sintered ceramic composition being characterized by a density of at least 90% of theoretical density.

  14. 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.

  15. Properties of modified polysiloxane based ceramic matrix for long fibre reinforced composite materials

    Czech Academy of Sciences Publication Activity Database

    Chlup, Zdeněk; Černý, Martin; Strachota, Adam; Kozák, Vladislav

    2011-01-01

    Roč. 40, 6-7 (2011), s. 380-385. ISSN 1465-8011 R&D Projects: GA ČR GA106/09/1101 Institutional research plan: CEZ:AV0Z20410507; CEZ:AV0Z30460519; CEZ:AV0Z40500505 Keywords : Polysiloxane resin * Pyrolysis * Indentation Subject RIV: JI - Composite Materials Impact factor: 0.597, year: 2011

  16. Manufacturing of superconductive silver/ceramic composites

    DEFF Research Database (Denmark)

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

    2000-01-01

    . After the mechanical deformation the tapes are heat treated at approximately 835C whereby the powder-cores by phase diffusion and grain growth are converted into superconducting, ceramic fibres. The geometry, density and texture of the powder cores before heat treatment is essential for the quality and......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...

  17. Processing and characterization of an Al2O3/WC/TiC micro- nano-composite ceramic tool material

    International Nuclear Information System (INIS)

    An Al2O3-based composite ceramic tool material reinforced with WC microparticles and TiC nano-particles was fabricated by using hot-pressing technique with MgO and NiO as sintering aids. The experimental results showed that optimal mechanical properties were achieved for the composite with the addition of 24 vol.% TiC nano-particles and 16 vol.% WC microparticles, with the flexural strength, fracture toughness and Vicker's hardness being 842 MPa, 6.82 MPa m1/2 and 22.19 GPa, respectively. The microstructure and phase composition of the composites were characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The fracture surface of the Al2O3/16 vol.%WC/24 vol.%TiC micro- nano-composite was characterized by a mix of intergranular and transgranular fracture as a result of the presence of both intergranular and intragranular secondary phase particles. It is believed that inhibition of matrix grain growth by intergranular secondary phase particles, sub-grain boundaries and dislocations pinning inside Al2O3 grains induced by intragranular TiC nano-particles contribute to the strengthening of the composite. Meanwhile, the dislocations and microcracks inside the matrix grains can also increase the flaw-tolerance leading to high toughness of the composite. Additionally, some extrinsic processes including crack deflection, crack bridging and crack branching caused by the microstructural discontinuities and local stress state can absorb a great amount of fracture energy, which are beneficial for the toughening of the composite. However, future research will need to quantitatively understand the synergistic effect of TiC nano-particles and WC microparticles on strengthening and toughening mechanisms.

  18. A comparison of the wear resistance and hardness of two different indirect composite resins with a ceramic material, opposed to human enamel

    OpenAIRE

    Ahmet Kursad Culhaoglu; Joonge Park

    2013-01-01

    Objectives: The aim of this study was to compare the two-body wear resistance of two different indirect composites and lithium disilicate porcelain versus human enamel antagonists. Materials and Methods: Ten specimens of each material (BelleGlass NG, Kerr Corp.; SR Adoro, Ivoclar Vivadent AG; IPS e.max, Ivoclar Vivadent AG) were fabricated. Indirect dental composites and all-ceramic restoration were compared by an in vitro tribological test against human teeth antagonist. Wear loss of antagon...

  19. Composite Materials

    DEFF Research Database (Denmark)

    Nielsen, Lauge Fuglsang

    This book deals with the mechanical and physical behavior of composites as influenced by composite geometry. "Composite Materials" provides a comprehensive introduction for researchers and students to modern composite materials research with a special emphasis on the significance of phase geometry....... The book enables the reader to a better understanding of the behavior of natural composites, improvement of such materials, and design of new materials with prescribed properties. A number of examples are presented: Special composite properties considered are stiffness, shrinkage, hygro...

  20. Wear resistance of PM composite materials reinforced with the Ti(C,N ceramic particles

    Directory of Open Access Journals (Sweden)

    A. Włodarczyk-Fligier

    2008-10-01

    Full Text Available Purpose: of the project was evaluation of the effect of heat treatment and of the reinforcing Ti(C,N particles in the EN AW-AlCu4Mg1(A aluminium alloy on the mechanical properties, wear resistance.Design/methodology/approach: some of the composite materials were hyperquenched for 0.5 h at the temperature of 495ºC with the subsequent cooling in water, and were quench aged next for 6 h at 200°C. Hardness tests were made on HAUSER hardness tester with the Vickers method at 10 N. Abrasion resistance wear tests were carried out with the constant number of cycles of 5000 (120 m at various loads: 4, 5, 6, 7, and 8 N. Test pieces were rinsed in the ultrasonic washer to clean them and next were weighed on the analytical balance with the accuracy of 0.0001 g to check the mass loss.Findings: Besides visible improvement of mechanical properties and wear resistance there were also observed the influence of heat treatment.Practical implications: Tested composite materials can be applied among others in automotive industry but it requires additional researches.Originality/value: It was demonstrated that the mechanical properties, as well as the wear resistance of the investigated composite materials with the EN AW-Al Cu4Mg1(A alloy matrix may be formed by the dispersion hardening with the Ti(C,N particles in various portions and by the precipitation hardening of the matrix.

  1. 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.

  2. Recent development of ceria-based (nano)composite materials for low temperature ceramic fuel cells and electrolyte-free fuel cells

    OpenAIRE

    Fan, Liangdong; Wang, Chengyang; Chen, Mingming; Zhu, Bin

    2013-01-01

    In the last ten years, the research of solid oxide fuel cells (SOFCs) or ceramic fuel cells (CFC) had focused on reducing the working temperature through the development of novel materials, especially the high ionic conductive electrolyte materials. Many progresses on single-phase electrolyte materials with the enhanced ionic conductivity have been made, but they are still far from the criteria of commercialization. The studies of ceria oxide based composite electrolytes give an alternative s...

  3. Surface characterization of ceramic materials

    International Nuclear Information System (INIS)

    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

  4. High-temperature bending strength and microstructure of Al2O3/ZrO2 ceramics composite materials. Al2O3/ZrO2 ceramics fukugo zairyo no koon mage kyodo to bisai kozo

    Energy Technology Data Exchange (ETDEWEB)

    Hisamori, N.; Kimura, Y. (Kogakuin University, Tokyo (Japan))

    1998-05-21

    A high-temperature strength test was carried out on Al2O3/ZrO2 ceramics composite materials to discuss correlation between high-temperature strength and microstructure thereof. The experiment used as a test material Al2O3/ZrO2 ceramics composite material sinters, in which Al2O3 is used as a base material, and tetragonal stabilized ZrO2 particles are dispersed in three kinds of ratios, 5, 15 and 30% by weight. The sintering temperatures were 1500, 1550, 1600 and 1650 degC. The high-temperature bending test was performed for three-point bending in atmosphere at room temperature, 600, 800 and 1000 degC. The following conclusions were obtained as a result of the discussions: Al2O3/ZrO2 ceramics composite material sinters can be improved of their strength even at elevated temperatures by adding ZrO2 particles while suppressing the addition to an extent that no strength deterioration would occur due to high-temperature corrosion and by sintering the materials at low temperatures to achieve microstructure; and, according to the result of observing the microstructure, single Al2O3 materials having lower strength than composite materials may have relatively large pores and inclusions inside the sinters and in the vicinity of the surface cause to work as fracture paths. 3 figs.

  5. Metallic and intermetallic-bonded ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Plucknett, K.P.; Tiegs, T.N.; Alexander, K.B. [Oak Ridge National Laboratory, TN (United States)] [and others

    1995-05-01

    The purpose of this task is to establish a framework for the development and fabrication of metallic-phase-reinforced ceramic matrix composites with improved fracture toughness and damage resistance. The incorporation of metallic phases that plastically deform in the crack tip region, and thus dissipate strain energy, will result in an increase in the fracture toughness of the composite as compared to the monolithic ceramic. It is intended that these reinforced ceramic matrix composites will be used over a temperature range from 20{degrees}C to 800-1200{degrees}C for advanced applications in the industrial sector. In order to systematically develop these materials, a combination of experimental and theoretical studies must be undertaken.

  6. Ceramic catalyst materials

    Energy Technology Data Exchange (ETDEWEB)

    Sault, A.G.; Gardner, T.J. [Sandia National Laboratories, Albuquerque, NM (United States); Hanprasopwattanna, A.; Reardon, J.; Datye, A.K. [Univ. of New Mexico, Albuquerque, NM (United States)

    1995-08-01

    Hydrous titanium oxide (HTO) ion-exchange materials show great potential as ceramic catalyst supports due to an inherently high ion-exchange capacity which allows facile loading of catalytically active transition metal ions, and an ability to be cast as thin films on virtually any substrate. By coating titania and HTO materials onto inexpensive, high surface area substrates such as silica and alumina, the economics of using these materials is greatly improved, particularly for the HTO materials, which are substantially more expensive in the bulk form than other oxide supports. In addition, the development of thin film forms of these materials allows the catalytic and mechanical properties of the final catalyst formulation to be separately engineered. In order to fully realize the potential of thin film forms of titania and HTO, improved methods for the deposition and characterization of titania and HTO films on high surface area substrates are being developed. By varying deposition procedures, titania film thickness and substrate coverage can be varied from the submonolayer range to multilayer thicknesses on both silica and alumina. HTO films can also be formed, but the quality and reproducibility of these films is not nearly as good as for pure titania films. The films are characterized using a combination of isopropanol dehydration rate measurements, point of zero charge (PZC) measurements, BET surface area, transmission electron microscopy (TEM), and elemental analysis. In order to assess the effects of changes in film morphology on catalytic activity, the films are being loaded with MoO{sub 3} using either incipient wetness impregnation or ion-exchange of heptamolybdate anions followed by calcining. The MoO{sub 3} is then sulfided to form MOS{sub 2}, and tested for catalytic activity using pyrene hydrogenation and dibenzothiophene (DBT) desulfurization, model reactions that simulate reactions occurring during coal liquefaction.

  7. Investigation of properties and performance of ceramic composite components

    Energy Technology Data Exchange (ETDEWEB)

    Stinchcomb, W.W.; Reifsnider, K.L.; Dunyak, T.J. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Engineering Science and Mechanics)

    1992-06-15

    The objective of the work reported herein is to develop an understanding of the mechanical behavior of advanced ceramic composites subjected to elevated temperature and dynamic (cyclic) loading, to develop a test system and test methods to obtain the properties and performance information required to design engineering components made from ceramic composite materials, and to provide critical and comprehensive evaluations of such materials to material synthesizers and developers to support and enhance progress in ceramic composite material development. The accomplishments of the investigation include the design, development, and demonstration of a high temperature, biaxial mechanical test facility for ceramic composite tubes and the development and validation of a performance simulation model (MRLife) for ceramic composites.

  8. A comparison of the wear resistance and hardness of two different indirect composite resins with a ceramic material, opposed to human enamel

    Directory of Open Access Journals (Sweden)

    Ahmet Kursad Culhaoglu

    2013-01-01

    Full Text Available Objectives: The aim of this study was to compare the two-body wear resistance of two different indirect composites and lithium disilicate porcelain versus human enamel antagonists. Materials and Methods: Ten specimens of each material (BelleGlass NG, Kerr Corp.; SR Adoro, Ivoclar Vivadent AG; IPS e.max, Ivoclar Vivadent AG were fabricated. Indirect dental composites and all-ceramic restoration were compared by an in vitro tribological test against human teeth antagonist. Wear loss of antagonist was calculated using an image analyzer (Leica Wear behavior of restorative materials was investigated with a profilometer after each individual tribological test. A scanning microscope was used to examine the crystal morphology of the samples; the crystal phases were identified by an X-ray diffractometer. Microhardness test results were analyzed using ANOVA. Kruskal Wallis multi-comparison test was used for evaluating the corrosion data. In order to understand whether there is a relationship between mean friction co-efficients, wear rate, and hardness, the statistical non-parametric relation test was used. Results: The indirect composites showed lower wear rate and friction co-efficient than all-ceramic dental materials against enamel. As for the wear loss of the enamel antagonists, the all-ceramic restorations were more harmful to human teeth than the dental composites. Conclusion: Indirect dental composite is relatively more wear-friendly than all-ceramic restoration. Furthermore, indirect composites are favorable and less offensive. Therefore, the second generation of indirect composites is promising in long-life dental restorations.

  9. Ceramic based lightweight composites with extreme dynamic strength

    International Nuclear Information System (INIS)

    On the basis of several years experiments in development of high performance technical ceramics and in investigation of hetero-modulus and hetero-viscous materials and ceramic matrix composites the authors successfully developed a new family of ceramic reinforced lightweight composites with extreme dynamic strength. To obtain these lightweight composites first the matrix materials were developed from different sort of sintered ceramics with high porosity and after the prepared items were re-sintered using reactive sintering methods or were impregnated with nanoparticles of Si3N4, SiAlON ceramics or light metal alloys having excellent mechanical strength and properties. Where it was necessary the pores and material structures of ceramic matrix materials anchored excellent wetting for a wide range of metal alloys, so it was possible to develop several types of ceramic reinforced hetero-modulus light metal composites with extreme dynamic strength of different density. In this work the authors present the c-Si3N4 diamond particles reinforced corundum matrix composite shield plate structures and some of the specially developed low density ceramic foams and high porosity ceramic matrix materials for lightweight metallic composites

  10. Assessment of ceramic composites for MMW space nuclear power systems

    International Nuclear Information System (INIS)

    Proposed multimegawatt nuclear power systems which operate at high temperatures, high levels of stress, and in hostile environments, including corrosive working fluids, have created interest in the use of ceramic composites as structural materials. This report assesses the applicability of several ceramic composites in both Brayton and Rankine cycle power systems. This assessment considers an equilibrium thermodynamic analysis and also a nonequilibrium assessment. (FI)

  11. High Temperature Tolerant Ceramic Composites Having Porous Interphases

    Energy Technology Data Exchange (ETDEWEB)

    Kriven, Waltraud M. (Champaign, IL); Lee, Sang-Jin (Chonnam, KR)

    2005-05-03

    In general, this invention relates to a ceramic composite exhibiting enhanced toughness and decreased brittleness, and to a process of preparing the ceramic composite. The ceramic composite comprises a first matrix that includes a first ceramic material, preferably selected from the group including alumina (Al2O3), mullite (3Al2O3.2SiO2), yttrium aluminate garnet (YAG), yttria stabilized zirconia (YSZ), celsian (BaAl2Si2O8) and nickel aluminate (NiAl2O4). The ceramic composite also includes a porous interphase region that includes a substantially non-sinterable material. The non-sinterable material can be selected to include, for example, alumina platelets. The platelets lie in random 3-D orientation and provide a debonding mechanism, which is independent of temperature in chemically compatible matrices. The non-sinterable material induces constrained sintering of a ceramic powder resulting in permanent porosity in the interphase region. For high temperature properties, addition of a sinterable ceramic powder to the non-sinterable material provides sufficiently weak debonding interphases. The ceramic composite can be provided in a variety of forms including a laminate, a fibrous monolith, and a fiber-reinforced ceramic matrix. In the laminated systems, intimate mixing of strong versus tough microstructures were tailored by alternating various matrix-to-interphase thickness ratios to provide the bimodal laminate.

  12. The corrosion of ceramic-matrix composites

    International Nuclear Information System (INIS)

    Ceramic matrix composites could replace existing metals and alloys in aircraft, naval engine parts or heat exchanged systems because of their low density and high thermostability. These composites are promising materials for long-life applications if the metastable state of the composite is preserved during the synthesis and on working atmospheres without deletorious evolution of the fibre, the matrix and of the fibre-matrix interface. The review begins with a brief recall on the corrosion of ceramics able to be used in composites (SiC, Si3N4, AlN, BN, aluminosilicates, C). The main sources of corrosion in combustion environment (proton, sodium ion) are discussed. A comparison is made with long-term corrosion at room-temperature. Examples of the different corrosion mechanisms observed for Nicalon NLM202 fibre glass-ceramic or ceramic (LAS, CAS, celsian, cordierite, Al2TiO5, mullite, Nasicon) matrix composites developed at ONERA are presented : ion exchange, grain boundary dissolution, fluxing, favourable and unfavourable fibre-matrix reaction, enhanced corrosion by prior fibre-matrix reaction. (orig.)

  13. The corrosion of ceramic-matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Colomban, P. [ONERA, Chatillon (France)]|[CNRS, LASIR, Thiais (France)

    1997-12-31

    Ceramic matrix composites could replace existing metals and alloys in aircraft, naval engine parts or heat exchanged systems because of their low density and high thermostability. These composites are promising materials for long-life applications if the metastable state of the composite is preserved during the synthesis and on working atmospheres without deletorious evolution of the fibre, the matrix and of the fibre-matrix interface. The review begins with a brief recall on the corrosion of ceramics able to be used in composites (SiC, Si{sub 3}N{sub 4}, AlN, BN, aluminosilicates, C). The main sources of corrosion in combustion environment (proton, sodium ion) are discussed. A comparison is made with long-term corrosion at room-temperature. Examples of the different corrosion mechanisms observed for Nicalon NLM202 fibre glass-ceramic or ceramic (LAS, CAS, celsian, cordierite, Al{sub 2}TiO{sub 5}, mullite, Nasicon) matrix composites developed at ONERA are presented : ion exchange, grain boundary dissolution, fluxing, favourable and unfavourable fibre-matrix reaction, enhanced corrosion by prior fibre-matrix reaction. (orig.) 39 refs.

  14. A new ceramic material for shielding pulsed neutron scattering instruments

    International Nuclear Information System (INIS)

    We propose a new ceramic composite, based on boron carbide, to use as a shielding material for pulsed neutron scattering instrumentation. The measured transmission data show characteristics equivalent to crispy mix, a common shielding material used at ISIS (UK)

  15. Development of high-density ceramic composites for ballistic applications

    International Nuclear Information System (INIS)

    The application of ceramic composites for ballistic application has been generally developed with ceramics of low density, between 2.5 and 4.5 g/cm2. These materials have offered good performance in defeating small-caliber penetrators, but can suffer time-dependent degradation effects when thicker ceramic tiles are needed to defeat modem, longer, heavy metal penetrators that erode rather than break up. This paper addresses the ongoing development, fabrication procedures, analysis, and ballistic evaluation of thinner, denser ceramics for use in armor applications. Nuclear Metals Incorporated (NMI) developed a process for the manufacture of depleted uranium (DU) ceramics. Samples of the ceramics have been supplied to the US Army Research Laboratory (ARL) as part of an unfunded cooperative study agreement. The fabrication processes used, characterization of the ceramic, and a ballistic comparison between the DU-based ceramic with baseline Al2O3 will be presented

  16. Nanostructured composite reinforced material

    Science.gov (United States)

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  17. Impact of Material and Architecture Model Parameters on the Failure of Woven Ceramic Matrix Composites (CMCs) via the Multiscale Generalized Method of Cells

    Science.gov (United States)

    Liu, Kuang C.; Arnold, Steven M.

    2011-01-01

    It is well known that failure of a material is a locally driven event. In the case of ceramic matrix composites (CMCs), significant variations in the microstructure of the composite exist and their significance on both deformation and life response need to be assessed. Examples of these variations include changes in the fiber tow shape, tow shifting/nesting and voids within and between tows. In the present work, the effects of many of these architectural parameters and material scatter of woven ceramic composite properties at the macroscale (woven RUC) will be studied to assess their sensitivity. The recently developed Multiscale Generalized Method of Cells methodology is used to determine the overall deformation response, proportional elastic limit (first matrix cracking), and failure under tensile loading conditions. The macroscale responses investigated illustrate the effect of architectural and material parameters on a single RUC representing a five harness satin weave fabric. Results shows that the most critical architectural parameter is weave void shape and content with other parameters being less in severity. Variation of the matrix material properties was also studied to illustrate the influence of the material variability on the overall features of the composite stress-strain response.

  18. Catalyzed Ceramic Burner Material

    Energy Technology Data Exchange (ETDEWEB)

    Barnes, Amy S., Dr.

    2012-06-29

    Catalyzed combustion offers the advantages of increased fuel efficiency, decreased emissions (both NOx and CO), and an expanded operating range. These performance improvements are related to the ability of the catalyst to stabilize a flame at or within the burner media and to combust fuel at much lower temperatures. This technology has a diverse set of applications in industrial and commercial heating, including boilers for the paper, food and chemical industries. However, wide spread adoption of catalyzed combustion has been limited by the high cost of precious metals needed for the catalyst materials. The primary objective of this project was the development of an innovative catalyzed burner media for commercial and small industrial boiler applications that drastically reduce the unit cost of the catalyzed media without sacrificing the benefits associated with catalyzed combustion. The scope of this program was to identify both the optimum substrate material as well as the best performing catalyst construction to meet or exceed industry standards for durability, cost, energy efficiency, and emissions. It was anticipated that commercial implementation of this technology would result in significant energy savings and reduced emissions. Based on demonstrated achievements, there is a potential to reduce NOx emissions by 40,000 TPY and natural gas consumption by 8.9 TBtu in industries that heavily utilize natural gas for process heating. These industries include food manufacturing, polymer processing, and pulp and paper manufacturing. Initial evaluation of commercial solutions and upcoming EPA regulations suggests that small to midsized boilers in industrial and commercial markets could possibly see the greatest benefit from this technology. While out of scope for the current program, an extension of this technology could also be applied to catalytic oxidation for volatile organic compounds (VOCs). Considerable progress has been made over the course of the grant

  19. Synergistically toughening effect of SiC whiskers and nanoparticles in Al2O3-based composite ceramic cutting tool material

    Science.gov (United States)

    Liu, Xuefei; Liu, Hanlian; Huang, Chuanzhen; Wang, Limei; Zou, Bin; Zhao, Bin

    2016-06-01

    In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al2O3-based ceramic cutting tool materials. Among them, SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties. While no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening effects of them have not been studied. An Al2O3-SiCw-SiCnp advanced ceramic cutting tool material is fabricated by adding both one-dimensional SiC whiskers and zero-dimensional SiC nanoparticles into the Al2O3 matrix with an effective dispersing and mixing process. The composites with 25 vol% SiC whiskers and 25 vol% SiC nanoparticles alone are also investegated for comparison purposes. Results show that the Al2O3-SiCw-SiCnp composite with both 20 vol% SiC whiskers and 5 vol% SiC nanoparticles additives have much improved mechanical properties. The flexural strength of Al2O3-SiCw-SiCnp is 730±95 MPa and fracture toughness is 5.6±0.6 MPa·m1/2. The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination. It is indicated that when SiC whiskers and nanoparticles are added together, the grains are further refined and homogenized, so that the microstructure and fracture mode ratio is modified. The SiC nanoparticles are found helpful to enhance the toughening effects of the SiC whiskers. The proposed research helps to enrich the types of ceramic cutting tool and is benefit to expand the application range of ceramic cutting tool.

  20. 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.

  1. Novel polymer derived ceramic hard materials

    Energy Technology Data Exchange (ETDEWEB)

    Kaindl, A.; Lehner, W.; Greil, P. [Erlangen-Nuernberg Univ., Erlangen (Germany). Dept. of Mater. Sci.; Kim, D.J. [Sung Kyun Kwan Univ., Dept. of Materials Science, Suwon (Korea, Republic of)

    1997-12-31

    Manufacturing, microstructure and properties of novel ceramic hard materials derived from polymer/reactive filler mixtures were investigated. Carbide forming metal powders of Mo were used as fillers to react with the carbon bearing decomposition products of polymethylsiloxanes during pyrolysis in nitrogen atmosphere. Microcrystalline composites with the filler reaction product Mo{sub 2}C embedded in an amorphous SiOC-matrix could be formed with complex geometry due to near-netshape polymer/ceramic conversion. Depending on the filler and the pyrolysis conditions ceramic hard materials with Vickers hardness up to 10 GPa, fracture toughness of 5.1 MPa{radical}(m), a flexural strength of 330 MPa and a Youngs modulus of 280 GPa were obtained. (orig.) 8 refs.

  2. Fundamental alloy design of oxide ceramics and their composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, I.W.

    1992-01-01

    The main research was on microstructural development of oxide ceramics. Projects were completed and the publications given. Abstracts are given on: Reactive CeO[sub 2]powders by homogeneous precipitation, SiC whisker-reinforced lithium aluminosilicate composite, solute drag on grain boundary in ionic solids (space charge effect), in-situ alumina/aluminate platelet composites, exaggerated texture and grain growth of superplastic silicon nitride (SiAlON), hot extrusion of ceramics, control of grain boundary pinning in Al[sub 2]O[sub 3]/ZrO[sub 2] composites with Ce[sup 3+]/Ce[sup 4+] doping, superplastic forming of ceramic composites, computer simulation of final stage sintering (model, kinetics, microstructure, effect of initial pore size), development of superplastic structural ceramics, and superplastic flow of two-phase ceramics containing rigid inclusions (zirconia/mullite composites). A proposed research program is outlined: materials, solute drag, densification and coarsening, and grain boundary electrical behavior.

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

    Directory of Open Access Journals (Sweden)

    Roberto Orrù

    2013-04-01

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

  4. High Strain Rate Compression Testing of Ceramics and Ceramic Composites.

    Energy Technology Data Exchange (ETDEWEB)

    Blumenthal, W. R. (William R.)

    2005-01-01

    The compressive deformation and failure behavior of ceramics and ceramic-metal composites for armor applications has been studied as a function of strain rate at Los Alamos National Laboratory since the late 1980s. High strain rate ({approx}10{sup 3} s{sup -1}) uniaxial compression loading can be achieved using the Kolsky-split-Hopkinson pressure bar (SHPB) technique, but special methods must be used to obtain valid strength results. This paper reviews these methods and the limitations of the Kolsky-SHPB technique for this class of materials. The Kolsky-split-Hopkinson pressure bar (Kolsky-SHPB) technique was originally developed to characterize the mechanical behavior of ductile materials such as metals and polymers where the results can be used to develop strain-rate and temperature-dependent constitutive behavior models that empirically describe macroscopic plastic flow. The flow behavior of metals and polymers is generally controlled by thermally-activated and rate-dependent dislocation motion or polymer chain motion in response to shear stresses. Conversely, the macroscopic mechanical behavior of dense, brittle, ceramic-based materials is dominated by elastic deformation terminated by rapid failure associated with the propagation of defects in the material in response to resolved tensile stresses. This behavior is usually characterized by a distribution of macroscopically measured failure strengths and strains. The basis for any strain-rate dependence observed in the failure strength must originate from rate-dependence in the damage and fracture process, since uniform, uniaxial elastic behavior is rate-independent (e.g. inertial effects on crack growth). The study of microscopic damage and fracture processes and their rate-dependence under dynamic loading conditions is a difficult experimental challenge that is not addressed in this paper. The purpose of this paper is to review the methods that have been developed at the Los Alamos National Laboratory to

  5. Ferrites and ceramic composites

    CERN Document Server

    Jotania, Rajshree B

    2013-01-01

    The Ferrite term is used to refer to all magnetic oxides containing iron as major metallic component. Ferrites are very attractive materials because they simultaneously show high resistivity and high saturation magnetization, and attract now considerable attention, because of the interesting physics involved. Typical ferrite material possesses excellent chemical stability, high corrosion resistivity, magneto-crystalline anisotropy, magneto-striction, and magneto-optical properties. Ferrites belong to the group of ferrimagnetic oxides, and include rare-earth garnets and ortho-ferrites. Several

  6. Analysis of crack initiation in the vicinity of an interface in brittle materials. Applications to ceramic matrix composites and nuclear fuels

    International Nuclear Information System (INIS)

    In this study, criterions are proposed to describe crack initiation in the vicinity of an interface in brittle bi-materials. The purpose is to provide a guide for the elaboration of ceramic multi-layer structures being able to develop damage tolerance by promoting crack deflection along interfaces. Several cracking mechanisms are analyzed, like the competition between the deflection of a primary crack along the interface or its penetration in the second layer. This work is first completed in a general case and is then used to describe the crack deviation at the interface in ceramic matrix composites and nuclear fuels. In this last part, experimental tests are carried out to determine the material fracture properties needed to the deflection criteria. An optimization of the fuel coating can be proposed in order to increase its toughness. (author)

  7. Continuous fiber ceramic matrix composites for heat engine components

    Science.gov (United States)

    Tripp, David E.

    1988-01-01

    High strength at elevated temperatures, low density, resistance to wear, and abundance of nonstrategic raw materials make structural ceramics attractive for advanced heat engine applications. Unfortunately, ceramics have a low fracture toughness and fail catastrophically because of overload, impact, and contact stresses. Ceramic matrix composites provide the means to achieve improved fracture toughness while retaining desirable characteristics, such as high strength and low density. Materials scientists and engineers are trying to develop the ideal fibers and matrices to achieve the optimum ceramic matrix composite properties. A need exists for the development of failure models for the design of ceramic matrix composite heat engine components. Phenomenological failure models are currently the most frequently used in industry, but they are deterministic and do not adequately describe ceramic matrix composite behavior. Semi-empirical models were proposed, which relate the failure of notched composite laminates to the stress a characteristic distance away from the notch. Shear lag models describe composite failure modes at the micromechanics level. The enhanced matrix cracking stress occurs at the same applied stress level predicted by the two models of steady state cracking. Finally, statistical models take into consideration the distribution in composite failure strength. The intent is to develop these models into computer algorithms for the failure analysis of ceramic matrix composites under monotonically increasing loads. The algorithms will be included in a postprocessor to general purpose finite element programs.

  8. Improved ceramic heat exchange material

    Science.gov (United States)

    Mccollister, H. L.

    1977-01-01

    Improved corrosion resistant ceramic materials that are suitable for use as regenerative heat exchangers for vehicular gas turbines is reported. Two glass-ceramic materials, C-144 and C-145, have superior durability towards sulfuric acid and sodium sulfate compared to lithium aluminosilicate (LAS) Corning heat exchange material 9455. Material C-144 is a leached LAS material whose major crystalline phase is silica keatite plus mullite, and C-145 is a LAS keatite solid solution (S.S.) material. In comparison to material 9455, material C-144 is two orders of magnitude better in dimensional stability to sulfuric acid at 300 C, and one order of magnitude better in stability to sodium sulfate at 1000 C. Material C-145 is initially two times better in stability to sulfuric acid, and about one order of magnitude better in stability to sodium sulfate. Both C-144 and C-145 have less than 300 ppm delta L/L thermal expansion from ambient to 1000 C, and good dimensional stability of less than approximately 100 ppm delta L/L after exposure to 1000 C for 100 hours. The glass-ceramic fabrication process produced a hexagonal honeycomb matrix having an 85% open frontal area, 50 micrometer wall thickness, and less than 5% porosity.

  9. Composite material

    Energy Technology Data Exchange (ETDEWEB)

    Hutchens, Stacy A. (Knoxville, TN); Woodward, Jonathan (Solihull, GB); Evans, Barbara R. (Oak Ridge, TN); O' Neill, Hugh M. (Knoxville, TN)

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  10. Composite material

    Science.gov (United States)

    Hutchens, Stacy A.; Woodward, Jonathan; Evans, Barbara R.; O'Neill, Hugh M.

    2012-02-07

    A composite biocompatible hydrogel material includes a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa. A calcium comprising salt is disposed in at least some of the pores. The porous polymer matrix can comprise cellulose, including bacterial cellulose. The composite can be used as a bone graft material. A method of tissue repair within the body of animals includes the steps of providing a composite biocompatible hydrogel material including a porous polymer matrix, the polymer matrix including a plurality of pores and providing a Young's modulus of at least 10 GPa, and inserting the hydrogel material into cartilage or bone tissue of an animal, wherein the hydrogel material supports cell colonization in vitro for autologous cell seeding.

  11. Effects of sintering processes on mechanical properties and microstructure of TiB2–TiC + 8 wt% nano-Ni composite ceramic cutting tool material

    International Nuclear Information System (INIS)

    Highlights: ► TiB2–TiC + 8 wt% nano-Ni ceramic tool material was sintered by six processes. ► The properties of material depended mainly on the holding stages and duration. ► SP1 process was involved with the multiple holding stages and longer duration. ► SP1 process led to many pores, and coarsening and brittle rupture of grains. ► Tool material sintered by SP6 process exhibited the optimum mechanical properties. - Abstract: TiB2–TiC composite powder was prepared by ball-milled with ethanol and vacuum dry, and TiB2–TiC + 8 wt% nano-Ni composite ceramic cutting tool material was sintered using vacuum hot-pressed sintering technique by six processes which included the different holding stages and times. The effects of sintering processes on the mechanical properties and microstructure were investigated. The polished surface and fracture surface of TiB2–TiC + 8 wt% nano-Ni ceramics sintered by the different sintering processes were observed by scanning electron microscope (SEM), X-ray diffraction (XRD) and energy-dispersive spectrometry (EDS), and the relationships between mechanical properties and microstructure were discussed. The mechanical properties and microstructure depended mainly on the total holding time and the different holding stages. The longer holding time and multiple holding stages led to coarsening of TiB2 and TiC grains, formation of pores and the brittle rupture of grains, which deteriorated the mechanical properties of TiB2–TiC + 8 wt% nano-Ni ceramic. TiB2–TiC + 8 wt% nano-Ni composite ceramic cutting tool material sintered by SP6 process exhibited the optimum resultant mechanical properties because of its finer microstructure and higher relative density, and its flexural strength, fracture toughness and hardness were 916.8 MPa, 7.80 MPa m1/2 and 22.54 GPa, respectively.

  12. Fabrication of Bulk Nanocrystalline Ceramic Materials

    Czech Academy of Sciences Publication Activity Database

    Chráska, Tomáš; Neufuss, Karel; Dubský, Jiří; Ctibor, Pavel; Klementová, Mariana

    2008-01-01

    Roč. 17, 5-6 (2008), s. 872-877. ISSN 1059-9630 R&D Projects: GA AV ČR KAN300430651 Institutional research plan: CEZ:AV0Z20430508; CEZ:AV0Z40320502 Keywords : thermal spraying * nanocrystalline composites * wear Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.200, year: 2008

  13. RESEARCH STATUS OF SELF- LUBRICATION OF CERAMIC AND CERAMIC COMPOSITE MATERIALS AT HIGH TEMPERATURES%陶瓷及其复合材料高温自润滑的研究现状

    Institute of Scientific and Technical Information of China (English)

    陈晓虎

    2001-01-01

    The research status of self- lubricating ceramic composite materials and self- lubrication of structural ceramics are briefly introduced in this paper. The effect of solid lubricant characteristics, the properties of interface and the effect of tribochemical reaction films are also discussed upon the efficiency of self- lubrication. The current insufficiency about the research of selflubricating ceramic composite materials is summarized and the possible problems are pointed out for the following study.%本文就固态润滑组元性质、与陶瓷基体界面特性以及摩擦化学反应膜层等几方面因素对陶瓷自润滑效应的影响,简要介绍了当前自润滑金属陶瓷材料、自润滑陶瓷复合材料和结构陶瓷自身润滑功效的一些研究情况。总结了自润滑陶瓷材料研究中存在的不足,并提出了今后研究应注意的问题。

  14. Corrosion of ceramic matrix composites

    OpenAIRE

    Scanu, T.; Colomban, Ph.

    1993-01-01

    Air stable ceramic matrix composites are promising for thermostructural applications such as aircraft engine parts. Turbine parts are subject to both sulphuric acid and sodium molten salts corrosion due to sulphate traces in engine fuel and to the NaCl air content. The chemical stability is a very important criterion but this point has not received much attention to date. We report here a study of acidic and sodium corrosion of various aluminosilicate matrices : LAS matrices (Li2OAl2O32-6SiO2...

  15. Preparation and Easy-Cleaning Property of Rare Earth Composite Ceramic

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Rare earth and far-infrared mineral composite materials were added to ceramic glazes to prepare easy-cleaning ceramic. The morphology of easy-cleaning ceramic was observed by SEM. The influence of easy-cleaning ceramic on water surface tension and contact angles of water were investigated. Through calculation of ceramic surface free energy and observation of oil drop on ceramic surface in water, the easy-cleaning mechanism of rare earth composite ceramic was studied. It is found that the rare earth composite ceramic can make water surface tension decrease. The surface free energy and the polar component of rare earth composite ceramic are increased. The rare earth composite ceramics have the easy-cleaning property.

  16. Natural Radioactivity in Ceramic Materials

    International Nuclear Information System (INIS)

    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

  17. Ceramic materials testing and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Wilfinger, K. R., LLNL

    1998-04-30

    corrosion by limiting the transport of water and oxygen to the ceramic-metal interface. Thermal spray techniques for ceramic coating metallic structures are currently being explored. The mechanics of thermal spray resembles spray painting in many respects, allowing large surfaces and contours to be covered smoothly. All of the relevant thermal spray processes use a high energy input to melt or partially melt a powdered oxide material, along with a high velocity gas to impinge the molten droplets onto a substrate where they conform, quench, solidify and adhere mechanically. The energy input can be an arc generated plasma, an oxy-fuel flame or an explosion. The appropriate feed material and the resulting coating morphologies vary with technique as well as with application parameters. To date on this project, several versions of arc plasma systems, a detonation coating system and two variations of high velocity oxy-fuel (HVOF) fired processes have been investigated, operating on several different ceramic materials.

  18. CVD COATING OF CERAMIC LAYERS ON CERAMIC CUTTING TOOL MATERIALS

    OpenAIRE

    Porat, R.

    1991-01-01

    When forming cutting tool materials based on ceramic components, one must take into considration the combination of wear resistance and mechanical properties which can withstand unfavorable cutting conditions at the same time maintaining high strength and fracture toughness. Ceramic cutting tools which are designed for machining at high cutting speeds and which have high strength and fracture toughness can be formed by applying a thin layer of ceramic materials on the substrate in order to in...

  19. Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material

    Science.gov (United States)

    Sancakli, Hande Sar; Sancakli, Erkan; Eren, Meltem Mert; Ozel, Sevda; Yucel, Taner; Yildiz, Esra

    2014-01-01

    PURPOSE The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of 6 mm × 4 mm and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with 30 µm silica oxide particles (Cojet™ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at α=.05. RESULTS Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used. PMID:25551002

  20. Improved Internal Reference Oxygen Sensors with Composite Ceramic Electrodes

    DEFF Research Database (Denmark)

    Hu, Qiang; Jacobsen, Torben; Hansen, Karin Vels;

    2012-01-01

    Potentiometric oxygen sensors with an internal reference electrode, which uses the equilibrium pO2 of the binary mixture of Ni/NiO as the reference, are demonstrated. The cells employ Pt or composite ceramics as the sensing electrode. The cells are fabricated by a flexible and potentially low cost...... performance are highly reproducible. The composite ceramics, based on strontium doped manganite and yttria doped zirconia, are proven superior over Pt to serve as the electrode material....

  1. Emerging Ceramic-based Materials for Dentistry

    OpenAIRE

    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 appr...

  2. 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

  3. Corrosion of ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Scanu, T. (ONERA-OM, 92 Chatillon (France) LASIR, CNRS, 94 Thiais (France)); Colomban, P. (ONERA-OM, 92 Chatillon (France) LASIR, CNRS, 94 Thiais (France))

    1993-11-01

    Air stable ceramic matrix composites are promising for thermostructural applications such as aircraft engine parts. Turbine parts are subject to both sulphuric acid and sodium molten salts corrosion due to sulphate traces in engine fuel and to the NaCl air content. The chemical stability is a very important criterion but this point has not received much attention to date. We report here a study of acidic and sodium corrosion of various aluminosilicate matrices : LAS matrices (Li[sub 2]OAl[sub 2]O[sub 3]2-6SiO[sub 2],nP[sub 2]O[sub 5]) in the amorphous, [beta] eucryptite and [beta] spodumene forms, BAS matrix (BaOAl[sub 2]O[sub 3]2SiO[sub 2]) in the form of monoclinic and hexagonal celsian, NASICON matrix (Na[sub 3]Zr[sub 2]Si[sub 2]PO[sub 12]) and mullite matrix. Microstructure damages and ion exchange have been analysed by X-ray diffraction, IR absorption, scanning electron microscopy and Raman microprobe. Drastic corrosion is observed for [beta] spodumene containing composites with the formation of strong hydrogen bond or with the cell expansion due to Li/Na[sup +] exchange. Medium acidic attack occurs for glassy LAS, [beta] eucryptite, BAS and NASICON matrix composites. On the other hand, [beta] eucryptite, NASICON and monoclinic celsian resist to alkaline melts. Mullite matrix composites are never corroded. (orig.).

  4. Corrosion of ceramic matrix composites

    International Nuclear Information System (INIS)

    Air stable ceramic matrix composites are promising for thermostructural applications such as aircraft engine parts. Turbine parts are subject to both sulphuric acid and sodium molten salts corrosion due to sulphate traces in engine fuel and to the NaCl air content. The chemical stability is a very important criterion but this point has not received much attention to date. We report here a study of acidic and sodium corrosion of various aluminosilicate matrices : LAS matrices (Li2OAl2O32-6SiO2,nP2O5) in the amorphous, β eucryptite and β spodumene forms, BAS matrix (BaOAl2O32SiO2) in the form of monoclinic and hexagonal celsian, NASICON matrix (Na3Zr2Si2PO12) and mullite matrix. Microstructure damages and ion exchange have been analysed by X-ray diffraction, IR absorption, scanning electron microscopy and Raman microprobe. Drastic corrosion is observed for β spodumene containing composites with the formation of strong hydrogen bond or with the cell expansion due to Li/Na+ exchange. Medium acidic attack occurs for glassy LAS, β eucryptite, BAS and NASICON matrix composites. On the other hand, β eucryptite, NASICON and monoclinic celsian resist to alkaline melts. Mullite matrix composites are never corroded. (orig.)

  5. Laminated alumina/zirconia ceramic composites prepared by electrophoretic deposition

    Czech Academy of Sciences Publication Activity Database

    Hadraba, Hynek; Drdlík, D.; Chlup, Zdeněk; Maca, K.; Dlouhý, Ivo

    Bratislava : VEDA, 2011 - (Pavol Šajgalík, Zoltán Lenčéš). s. 70 ISBN 978-80-970657-4-4. [Advanced Research Workshop Engineering Ceramics 2011 from Materials to Components. 08.05.2011-12.05.2011, Smolenice Castle] R&D Projects: GA ČR(CZ) GAP108/11/1644 Institutional research plan: CEZ:AV0Z20410507 Keywords : Ceramic laminates * Electrophoretic deposition * Hardness Subject RIV: JI - Composite Materials

  6. Method of making multilayered titanium ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, George T., II; Hansen; Jeffrey S.; Oden; Laurance L.; Turner; Paul C.; Ochs; Thomas L.

    1998-08-25

    A method making a titanium ceramic composite involves forming a hot pressed powder body having a microstructure comprising at least one titanium metal or alloy layer and at least one ceramic particulate reinforced titanium metal or alloy layer and hot forging the hot pressed body follwed by hot rolling to substantially reduce a thickness dimension and substantially increase a lateral dimension thereof to form a composite plate or sheet that retains in the microstructure at least one titanium based layer and at least one ceramic reinforced titanium based layer in the thickness direction of the composite plate or sheet.

  7. Use of the Materials Genome Initiative (MGI approach in the design of improved-performance fiber-reinforced SiC/SiC ceramic-matrix composites (CMCs

    Directory of Open Access Journals (Sweden)

    Mica Grujicic

    2016-07-01

    Full Text Available New materials are traditionally developed using costly and time-consuming trial-and-error experimental efforts. This is followed by an even lengthier material-certification process. Consequently, it takes 10 to 20 years before a newly-discovered material is commercially employed. An alternative approach to the development of new materials is the so-called materials-by-design approach within which a material is treated as a complex hierarchical system, and its design and optimization is carried out by employing computer-aided engineering analyses, predictive tools and available material databases. In the present work, the materials-by-design approach is utilized to design a grade of fiber-reinforced (FR SiC/SiC ceramic matrix composites (CMCs, the type of materials which are currently being used in stationary components, and are considered for use in rotating components, of the hot sections of gas-turbine engines. Towards that end, a number of mathematical functions and numerical models are developed which relate CMC constituents’ (fibers, fiber coating and matrix microstructure and their properties to the properties and performance of the CMC as a whole. To validate the newly-developed materials-by-design approach, comparisons are made between experimentally measured and computationally predicted selected CMC mechanical properties. Then an optimization procedure is employed to determine the chemical makeup and processing routes for the CMC constituents so that the selected mechanical properties of the CMCs are increased to a preset target level.

  8. Characterization of CVI densification of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L.; Stock, S.R.; Lee, S. [Georgia Institute of Technology, Atlanta, GA (United States)

    1995-05-01

    Ceramic matrix composites promise higher operating temperature and better thermodynamic efficiency in many enregy conversion systems. In particular, composites fabricated by the chemical vapor infiltration (CVI) process have excellent mechanical properties and, using the forced flow-thermal gradient variation, good processing economics in small scale demonstrations. Scale-up to larger, more complex shapes requires understanding of gas flow through the fiber preform and of the relationship between fiber architecture and densification behavior. This understanding is needed for design of preforms for optimum infiltration. The objective of this research is to observe the deposition of matrix material in the pores of a ceramic fiber preform at various stages of the CVI process. These observations allow us to relate local deposition rates in various regions of the composite to the connectivity of the surrounding network of porosity and to better model the relationship between gas transport and fiber architecture in CVI preforms. Our observation of the CVI process utilizes high resolution X-ray tomographic microscopy (XTM) in collaboration with Dr. John Kinney at Lawrence Livermore National Laboratory with repeated imaging of a small preform specimens after various processing times. We use these images to determine geometry and dimensions of channels between and through layers in cloth lay-up preform during CVI densification and relate these to a transport model.

  9. Continuous Fiber Ceramic Composite (CFCC) Program: Gaseous Nitridation

    Energy Technology Data Exchange (ETDEWEB)

    R. Suplinskas G. DiBona; W. Grant

    2001-10-29

    Textron has developed a mature process for the fabrication of continuous fiber ceramic composite (CFCC) tubes for application in the aluminum processing and casting industry. The major milestones in this project are System Composition; Matrix Formulation; Preform Fabrication; Nitridation; Material Characterization; Component Evaluation

  10. Preparation and characterization of porous alumina-zirconia composite ceramics

    Czech Academy of Sciences Publication Activity Database

    Pabst, W.; Gregorová, E.; Sedlářová, I.; Černý, Martin

    2011-01-01

    Roč. 31, č. 14 (2011), s. 2721-2731. ISSN 0955-2219. [International Conference on Ceramic Processing Science /11./. Zürich, 29.08.2010-01.09.2010] Institutional research plan: CEZ:AV0Z30460519 Keywords : sintering * slip casting * composites Subject RIV: JI - Composite Materials Impact factor: 2.353, year: 2011

  11. Development and characterization of Textron continuous fiber ceramic composite hot gas filter materials. Final report, September 30, 1994--October 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    DiPietro, S.G.; Alvin, M.A.

    1997-12-31

    Uncertainties about the long-term ability of monolithic ceramics to survive in the IGCC or PFBC hot gas filter environment led DOE/METC to consider the merits of using continuous fiber reinforced ceramic composites (CFCCs) as potential next-generation high temperature filter elements. This seems to be a logical strategy to pursue in light of the fact that properly-engineered CFCC materials have shown much-improved damage tolerance and thermal shock behavior as compared to existing monolithic ceramic materials. Textron`s Advanced Hot Gas Filter Development Program was intended to be a two year, two phase program which transitioned developmental materials R and D into prototype filter element fabrication. The first phase was to demonstrate the technical feasibility of fabricating CFCC hot gas filter elements which could meet the pressure drop specifications of less than ten inches of water (iwg) at a face velocity of ten feet per minute (fpm), while showing sufficient integrity to survive normal mechanical loads and adequate environmental resistance to steam/alkali corrosion conditions at a temperature of approximately 870 C (1600 F). The primary objective of the second phase of the program was to scale up fabrication methods developed in Phase 1 to produce full-scale CFCC candle filters for validation testing. Textron encountered significant process-related and technical difficulties in merely meeting the program permeability specifications, and much effort was expended in showing that this could indeed be achieved. Thus, by the time the Phase 1 program was completed, expenditure of program funds precluded continuing on with Phase 2, and Textron elected to terminate their program after Phase 1. This allowed Textron to be able to focus technical and commercialization efforts on their largely successful DOE CFCC Program.

  12. Thermal Performance of Ablative/ Ceramic Composite

    Directory of Open Access Journals (Sweden)

    Adriana STEFAN

    2014-12-01

    Full Text Available A hybrid thermal protection system for atmospheric earth re-entry based on ablative materials on top of ceramic matrix composites is investigated for the protection of the metallic structure in oxidative and high temperature environment of the space vehicles. The paper focuses on the joints of ablative material (carbon fiber based CALCARB® or cork based NORCOAT TM and Ceramic Matrix Composite (CMC material (carbon fibers embedded in silicon carbide matrix, Cf/SiC, SICARBON TM or C/C-SiC using commercial high temperature inorganic adhesives. To study the thermal performance of the bonded materials the joints were tested under thermal shock at the QTS facility. For carrying out the test, the sample is mounted into a holder and transferred from outside the oven at room temperature, inside the oven at the set testing temperature (1100°C, at a heating rate that was determined during the calibration stage. The dwell time at the test temperature is up to 2 min at 1100ºC at an increasing rate of temperature up to ~ 9,5°C/s. Evaluating the atmospheric re-entry real conditions we found that the most suited cooling method is the natural cooling in air environment as the materials re-entering the Earth atmosphere are subjected to similar conditions. The average weigh loss was calculated for all the samples from one set, without differentiating the adhesive used as the weight loss is due to the ablative material consumption that is the same in all the samples and is up to 2%. The thermal shock test proves that, thermally, all joints behaved similarly, the two parts withstanding the test successfully and the assembly maintaining its integrity.

  13. Residual stress in ceramics and ceramic composites

    International Nuclear Information System (INIS)

    Residual stresses in Si3N4 and SiC have been measured with X-ray diffraction after grinding and thermal shock. The produced surface stresses are compressive after both treatments. The stresses show a strong dependence on the quenching temperature up to a certain temperature when cracks relax the stresses. The influence of the amount of reinforcing phase on the residual stress state in a Al2O3/SiC whisker composite was investigated and correlated to a modified Eshelby model. The agreement is excellent. The composite was quenched in liquid He (4K) and the stress state measured after show no relaxation of stresses, indicating elastic behaviour. An in situ strain measurement as a function of temperature conducted on a Al2O3/SiC whisker composite and a SiC/TiB2 particle composite show very good agreement with the Eshelby model for the Al2O3/SiC system but not agreement for the SiC/TiB2 system. The reason is believed to be stress relaxation during sample preparation. (au) (53 refs., 24 figs., 14 tabs.)

  14. High temperature fracture of ceramic materials

    International Nuclear Information System (INIS)

    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

  15. Effect of surface treatments on shear bond strength of resin composite bonded to CAD/CAM resin-ceramic hybrid materials

    Science.gov (United States)

    Güngör, Merve Bankoğlu; Bal, Bilge Turhan; Ünver, Senem; Doğan, Aylin

    2016-01-01

    PURPOSE The purpose of this study was to assess the effect of surface treatments on shear bond strength of resin composite bonded to thermocycled and non-thermocycled CAD/CAM resin-ceramic hybrid materials. MATERIALS AND METHODS 120 specimens (10×10×2 mm) from each material were divided into 12 groups according to different surface treatments in combination with thermal aging procedures. Surface treatment methods were airborne-particle abrasion (abraded with 50 micron alumina particles), dry grinding (grinded with 125 µm grain size bur), and hydrofluoric acid (9%) and silane application. According to the thermocycling procedure, the groups were assigned as non-thermocycled, thermocycled after packing composites, and thermocycled before packing composites. The average surface roughness of the non-thermocycled specimens were measured after surface treatments. After packing composites and thermocycling procedures, shear bond strength (SBS) of the specimens were tested. The results of surface roughness were statistically analyzed by 2-way Analysis of Variance (ANOVA), and SBS results were statistically analyzed by 3-way ANOVA. RESULTS Surface roughness of GC were significantly lower than that of LU and VE (P<.05). The highest surface roughness was observed for dry grinding group, followed by airborne particle abraded group (P<.05). Comparing the materials within the same surface treatment method revealed that untreated surfaces generally showed lower SBS values. The values of untreated LU specimens showed significantly different SBS values compared to those of other surface treatment groups (P<.05). CONCLUSION SBS was affected by surface treatments. Thermocycling did not have any effect on the SBS of the materials except acid and silane applied GC specimens, which were subjected to thermocycling before packing of the composite resin.

  16. Development of Ceramic Solid-State Laser Host Material

    Science.gov (United States)

    Prasad, Narasimha S.; Trivedi, Sudhir; Kutcher, Susan; Wang, Chen-Chia; Kim, Joo-Soo; Hommerich, Uwe; Shukla, Vijay; Sadangi, Rajendra

    2009-01-01

    Polycrystalline ceramic laser materials are gaining importance in the development of novel diode-pumped solid-state lasers. Compared to single-crystals, ceramic laser materials offer advantages in terms of ease of fabrication, shape, size, and control of dopant concentrations. Recently, we have developed Neodymium doped Yttria (Nd:Y2O3) as a solid-state ceramic laser material. A scalable production method was utilized to make spherical non agglomerated and monodisperse metastable ceramic powders of compositions that were used to fabricate polycrystalline ceramic material components. This processing technique allowed for higher doping concentrations without the segregation problems that are normally encountered in single crystalline growth. We have successfully fabricated undoped and Neodymium doped Yttria material up to 2" in diameter, Ytterbium doped Yttria, and erbium doped Yttria. We are also in the process of developing other sesquioxides such as scandium Oxide (Sc2O3) and Lutesium Oxide (Lu2O3) doped with Ytterbium, erbium and thulium dopants. In this paper, we present our initial results on the material, optical, and spectroscopic properties of the doped and undoped sesquioxide materials. Polycrystalline ceramic lasers have enormous potential applications including remote sensing, chem.-bio detection, and space exploration research. It is also potentially much less expensive to produce ceramic laser materials compared to their single crystalline counterparts because of the shorter fabrication time and the potential for mass production in large sizes.

  17. Study on Microstructure of Alumina Based Rare Earth Ceramic Composite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Analysis techniques such as SEM, TEM and EDAX were used to investigate the microstructure of rare earth reinforced Al2O3/(W, Ti)C ceramic composite. Chemical and physical compatibility of the composite was analyzed and interfacial microstructure was studied in detail. It is found that both Al2O3 and (W, Ti)C phases are interlaced with each other to form the skeleton structure in the composite. A small amount of pores and glass phases are observed inside the material which will inevitably influence the physical and mechanical property of the composite. Thermal residual stresses resulted from thermal expansion mismatch can then lead to the emergence of dislocations and microcracks. Interfaces and boundaries of different types are found to exist inside the Al2O3/(W, Ti)C rare earth ceramic composite, which is concerned with the addition of rare earth element and the extent of solid solution of ceramic phases.

  18. Composite materials based on EN AW-Al Cu4Mg1(A aluminum alloy reinforced with the BN ceramic particles

    Directory of Open Access Journals (Sweden)

    P. Bała

    2010-03-01

    Full Text Available Purpose: The concept of new tool materials, based on Ni alloys strengthened by intermetallic compounds, intended for operations in high temperatures is presented in the hereby paper. The proposed chemical composition and the results of microstructure investigations as well as hardness testing in as-cast condition – are given.Design/methodology/approach: A test melt of a mass of approximately 1 kg was done in a vacuum furnace, and cast into a ceramic mould. The microstructure of the investigated material was examined by a light microscope Axiovert 200 MAT and the scanning electron microscope FIB Zeiss NEON 40EsB CrossBeam. Dilatometric experiment was performed by means of the Adamel Lhomargy DT 1000 dilatometer .Findings: The main components of the microstructure of the nickel-base investigated alloy are: the γ phase, which constitutes the matrix and the γ’ phase. This γ’ phase occurs as fine globular precipitates as well as in a form of primary Ta carbides of MC type. Primary carbides of irregular shapes are uniformly distributed not forming agglomerates. The assumed volume fraction of the primary carbides was achieved.Research limitations/implications: Identification of microstructure components on Ni-based materials strengthened by particles of intermetallic phases of a high carbon content.Practical implications: New tool material for hot-working.Originality/value: The new chemical compositions of tool materials based on Ni alloys strengthened by intermetallic compounds with high carbon content.

  19. Investigation of properties and performance of ceramic composite components. Final report on Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    Curtin, W.A.; Reifsnider, K.L.; Oleksuk, L.L.S.; Stinchcomb, W.W. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

    1994-10-31

    The purpose of Phase 2 of the Investigation of Properties and Performance of Ceramic Composite Components has been to build on and extend the work completed during Phase 1 to further advance the transition from properties of ceramic composite materials to performance of ceramic composite components used in fossil energy environments. The specific tasks of Phase 2 were: (1) develop and validate reliable and accurate high temperature, biaxial mechanical tests methods for structural ceramic composite components; (2) test and evaluate ceramic composite components, specifically tubes; (3) characterize long-term, mechanical performance of ceramic composite tubes at high temperatures; (4) develop a fundamental understanding of the mechanical degradation and performance limitations of ceramic composite components under service conditions; (5) develop predictive models for damage tolerance and reliability; and (6) relate component performance to microstructure and, thereby, provide feedback to the associated process-development effort, to improve performance. Accomplishments for each task are given.

  20. Calculation of thermal stresses in glass-ceramic composites

    OpenAIRE

    Ganghoffer, Jean-François

    2015-01-01

    Opto-electronics make intensive use of composite materials based on amorphous materials, which can be considered as smart materials since they are capable of high performances in their final state. Particularly, glass-ceramic composites involved in welding operations for microelectronics applications are subjected to important thermal stresses during their production, which can deteriorate their properties at room temperature, until the failure stage is reached. It is then essential to be abl...

  1. Materials characteristics of uncoated/ceramic-coated implant materials.

    Science.gov (United States)

    Lacefield, W R

    1999-06-01

    In this paper, the biocompatibility of dental implant materials is discussed in the context of both the mechanical characteristics of the materials and the type of surface presented to the surrounding tissues. The proper functioning of the implant depends on whether it possesses the strength necessary to withstand loading within the expected range, with other properties such as elongation being of importance in some instances. A suitable modulus of elasticity may be of major importance in situations when optimum load transmission from the implant into the surrounding bone is key to the successful functioning of the device. Dental implants present a wide range of surfaces to the surrounding tissues based on surface composition, texture, charge energy, and cleanliness (sterility). Metallic implants are characterized by protective oxide layers, but ion release is still common with these materials, and is a function of passivation state, composition, and corrosion potential. An effective surface treatment for titanium appears to be passivation or anodization in a suitable solution prior to implantation. Inert ceramic surfaces exhibit minimal ion release, but are similar to metals in that they do not form a high energy bond to the surrounding bone. Some of the newly developed dental implant alloys such as titanium alloys, which contain zirconium and niobium, and high-strength ceramics such as zirconia may offer some advantages (such as lower modulus of elasticity) over the conventional materials. Calcium phosphate ceramic coatings are commonly used to convert metallic surfaces into a more bioactive state and typically cause faster bone apposition. There is a wide range of ceramic coatings containing calcium and phosphorus, with the primary difference in many of these materials being in the rate of ion release. Although their long-term success rate is unknown, the calcium phosphate surfaces seem to have a higher potential for attachment of osteoinductive agents than do

  2. Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2007-01-01

    A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells. The goal in formulating the glass/ ceramic composite materials was to (1) retain the physical and chemical advantages that led to the prior selection of the barium calcium aluminosilicate glass as the sealant while (2) increasing strength and fracture toughness so as to reduce the tendency toward cracking. Each of the composite formulations consists of the glass plus either of two ceramic reinforcements in a proportion between 0 and 30 mole percent. One of the ceramic reinforcements consists of alumina platelets; the other one consists of particles of yttria-stabilized zirconia wherein the yttria content is 3 mole percent (3YSZ). In preparation for experiments, panels of the glass/ceramic composites were hot-pressed and machined into test bars.

  3. Directly susceptible, noncarbon metal ceramic composite crucible

    Energy Technology Data Exchange (ETDEWEB)

    Holcombe, Jr., Cressie E. (Farragut, TN); Kiggans, Jr., James O. (Oak Ridge, TN); Morrow, S. Marvin (Kingston, TN); Rexford, Donald (Pattersonville, NY)

    1999-01-01

    A sintered metal ceramic crucible suitable for high temperature induction melting of reactive metals without appreciable carbon or silicon contamination of the melt. The crucible comprises a cast matrix of a thermally conductive ceramic material; a perforated metal sleeve, which serves as a susceptor for induction heating of the crucible, embedded within the ceramic cast matrix; and a thermal-shock-absorber barrier interposed between the metal sleeve and the ceramic cast matrix to allow for differential thermal expansions between the matrix and the metal sleeve and to act as a thermal-shock-absorber which moderates the effects of rapid changes of sleeve temperature on the matrix.

  4. Directly susceptible, noncarbon metal ceramic composite crucible

    Energy Technology Data Exchange (ETDEWEB)

    Holcombe, C.E. Jr.; Kiggans, J.O. Jr.; Morrow, S.M.; Rexford, D.

    1999-12-07

    A sintered metal ceramic crucible suitable for high temperature induction melting of reactive metals without appreciable carbon or silicon contamination of the melt is disclosed. The crucible comprises a cast matrix of a thermally conductive ceramic material; a perforated metal sleeve, which serves as a susceptor for induction heating of the crucible, embedded within the ceramic cast matrix; and a thermal-shock-absorber barrier interposed between the metal sleeve and the ceramic cast matrix to allow for differential thermal expansions between the matrix and the metal sleeve and to act as a thermal-shock-absorber which moderates the effects of rapid changes of sleeve temperature on the matrix.

  5. 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...

  6. Ceramic Materials and Color in Dentistry

    OpenAIRE

    Volpato, Claudia; Fredel, Márcio; Philippi, Analúcia; PETTER, Carlos

    2010-01-01

    Since the introduction of metal ceramic crowns, clinicians and researchers have been looking for a restorative system that can associate beauty, strength and durability, but without the presence of a metallic infrastructure. Indeed, dental ceramics are materials that come aesthetically closest to natural teeth. With the improvement of ceramic systems, it has been possible to combine the excellent aesthetic characteristics of this material with a considerable resistance to fracture. It is impe...

  7. Insights on Ceramics as Dental Materials. Part I: Ceramic Material Types in Dentistry

    OpenAIRE

    Ho, GW; Matinlinna, JP

    2011-01-01

    Ceramics are widely used biomaterials in prosthetic dentistry due to their attractive clinical properties. They are aesthetically pleasing with their color, shade and luster, and they are chemically stable. The main constituents of dental ceramic are Si-based inorganic materials, such as feldspar, quartz, and silica. Traditional feldspar-based ceramics are also referred to as "Porcelain". The crucial difference between a regular ceramic and a dental ceramic is the proportion of feldspar, quar...

  8. Characterization of composite ceramic high level waste forms

    International Nuclear Information System (INIS)

    Argonne National Laboratory has developed a composite ceramic waste form for the disposition of high level radioactive waste produced during electrometallurgical conditioning of spent nuclear fuel. The electrorefiner LiCl/KCl eutectic salt, containing fission products and transuranics in the chloride form, is contacted with a zeolite material which removes the fission products from the salt. After salt contact, the zeolite is mixed with a glass binder. The zeolite/glass mixture is then hot isostatic pressed (HIPed) to produce the composite ceramic waste form. The ceramic waste form provides a durable medium that is well suited to incorporate fission products and transuranics in the chloride form. Presented are preliminary results of the process qualification and characterization studies, which include chemical and physical measurements and product durability testing, of the ceramic waste form

  9. Glass-ceramic frits for porcelain stoneware bodies: effects on sintering, phase composition and technological properties

    OpenAIRE

    Zanelli, Chiara; Baldi, Giovanni; Dondi, Michele; Ercolani, Giampaolo; Guarini, Guia; Raimondo, Maria Rosa

    2008-01-01

    In the present work, the effects of glass-ceramic frits (10wt%) added to a porcelain stoneware body in replacement of non-plastic raw materials, were evaluated simulating the tile-making process. Each glass-ceramic frit plays its own peculiar effect on the compositional properties and only some precursors behave as real glass ceramic materials. The positive influence of glass-ceramic precursors in promoting the sintering stands out when temperature onset densification and sintering rate are c...

  10. An irradiation test of heat-resistant ceramic composite materials. Interim report on post-irradiation examinations of the first preliminary irradiation test: 97M-13A

    International Nuclear Information System (INIS)

    The Japan Atomic Energy Research Institute (JAERI) has been carrying out the research on radiation damage mechanism of heat-resistant ceramic composite materials, as one of the subjects of the innovative basic research on high temperature engineering using the High Temperature Engineering Test Reactor (HTTR). A series of preliminary irradiation tests is being made using the Japan Materials Testing Reactor (JMTR). The present report describes results of post-irradiation examinations (PIE) so far on specimens irradiated in the first capsule, designated 97M-13A, to fast neutron fluences of 1.2-1.8x1024 m-2 (E>1 MeV) at temperatures of 573, 673 and 843 K. In the PIE, measurements were made on (1) dimensional changes, (2) thermal expansions, (3) X-ray parameters and (4) γ-ray spectra. The results for the carbon/carbon and SiC/SiC composites were similar to those in existing literatures. The temperature monitor effect was observed both for SiC fiber- and particle-reinforced SiC composites as in the case of monolithic SiC. Namely, the curve of the coefficient of thermal expansion (CTE) of these specimens showed a rapid drop above a temperature around the irradiation temperature +100 K in the first ramp (ramp rate: 10 K/min), while in the second ramp the CTE curves were almost the same as those of un-irradiated SiC specimens. (author)

  11. An irradiation test of heat-resistant ceramic composite materials. Interim report on post-irradiation examinations of the first preliminary irradiation test: 97M-13A

    Energy Technology Data Exchange (ETDEWEB)

    Baba, Shin-ichi; Takahashi, Tsuneo; Ishihara, Masahiro; Hayashi, Kimio; Sozawa, Shizuo; Saito, Takashi [Japan Atomic Energy Research Inst., Oarai, Ibaraki (Japan). Oarai Research Establishment; Suzuki, Yoshio [Nuclear Engineering, Co. Ltd., Osaka (Japan); Saito, Tamotsu; Sekino, Hajime [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2001-03-01

    The Japan Atomic Energy Research Institute (JAERI) has been carrying out the research on radiation damage mechanism of heat-resistant ceramic composite materials, as one of the subjects of the innovative basic research on high temperature engineering using the High Temperature Engineering Test Reactor (HTTR). A series of preliminary irradiation tests is being made using the Japan Materials Testing Reactor (JMTR). The present report describes results of post-irradiation examinations (PIE) so far on specimens irradiated in the first capsule, designated 97M-13A, to fast neutron fluences of 1.2-1.8x10{sup 24} m{sup -2} (E>1 MeV) at temperatures of 573, 673 and 843 K. In the PIE, measurements were made on (1) dimensional changes, (2) thermal expansions, (3) X-ray parameters and (4) {gamma}-ray spectra. The results for the carbon/carbon and SiC/SiC composites were similar to those in existing literatures. The temperature monitor effect was observed both for SiC fiber- and particle-reinforced SiC composites as in the case of monolithic SiC. Namely, the curve of the coefficient of thermal expansion (CTE) of these specimens showed a rapid drop above a temperature around the irradiation temperature +100 K in the first ramp (ramp rate: 10 K/min), while in the second ramp the CTE curves were almost the same as those of un-irradiated SiC specimens. (author)

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

    International Nuclear Information System (INIS)

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

  13. Use of SiCf/SiC ceramic composites as structure material of a fusion reactor toroid internal components

    International Nuclear Information System (INIS)

    The use of low neutron-induced activation structural materials seems necessary in order to improve safety in future fusion power reactors. Among them, SiCf/SiC composites appear as a very promising solution because of their low activation characteristics coupled with excellent mechanical properties at high temperatures. With the main objective of evaluating the limit of present-day composites, a tritium breeding blanket using SiCf/SiC as structural material (the TAURO blanket) has been developed in the last years by the Commissariat a l'Energie Atomique (CEA). The purpose of this thesis was to modify the available design tools (computer codes, design criteria), normally used for the analyses of metallic structures, in order to better take into account the mechanical behaviour of SiCf/SiC. Alter a preliminary improvement of the calculation methods, two main topics of study could be identified: the modelling of the mechanical behaviour of the composite and the assessment of appropriate design criteria. The different behavioural models available in literature were analysed in order to find the one that was the best suited to the specific problems met in the field of fusion power. The selected model was then implemented in the finite elements code CASTEM 2000 used within the CEA for the thermo-mechanical analyses of the TAURO blanket. For the design of the blanket, we proposed a new resistance criterion whose main advantage, with respect to the other examined, lies in the easiness of identification. The suggested solutions were then applied in the design studies of the TAURO blanket. We then could show that the use of appropriate calculation methodologies is necessary in order to achieve a correct design of the blanket and a more realistic estimate of the limits of present day composites. The obtained results can also be extended to all nuclear components making use of SiCf/SiC structures. (author)

  14. Batch compositions for cordierite ceramics

    Science.gov (United States)

    Hickman, David L.

    1994-07-26

    Ceramic products consisting principally of cordierite and a method for making them are provided, the method employing batches comprising a mineral component and a chemical component, the mineral component comprising clay and talc and the chemical component consisting essentially of a combination of the powdered oxides, hydroxides, or hydrous oxides of magnesium, aluminum and silicon. Ceramics made by extrusion and firing of the batches can exhibit low porosity, high strength and low thermal expansion coefficients.

  15. Transport properties of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L. [Georgia Inst. of Technology, Atlanta, GA (United States)

    1995-08-01

    This project involves experimental and modeling investigation of the transport properties of chemical vapor infiltration (CVI) preforms and densified composites, with particular emphasis on gas permeability and mass diffusivity. The results of this work will be useful both for on-going CVI process development and for evaluation and optimization of composite materials for fossil energy applications. With preforms made with 500 filaments/tow Nicalon at 40 vol% fiber loading, permeability values are similar for square-weave cloth layup and 3-D weave at low density. At greater densification the 3-D weave permeability is lower and approaches zero with significantly more closed porosity than the cloth layup. For filament wound preforms we were unable to make reliable measurements with the available materials. A model for gas transport in these materials utilizes percolation theory concepts. The ultimate achievable density is related to the closing of a continuous gas path through the preform. As the density approaches this limit the gas permeability and diffusivity vanish exponentially. The value of this limit is controlled primarily by the preform fiber architecture. The observed difference between the cloth layup and 3-D weave materials is due to the larger pores at tow crossing points found in the 3-D weave.

  16. Transport properties of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Starr, T.L.; Hablutzel, N. [Georgia Institute of Technology, Atlanta, GA (United States)

    1996-08-01

    Instrumentation and procedures have been completed for measurement of gas permeability and mass diffusivity of fiber preforms and porous materials. Results are reported for composites reinforced with Nicalon fiber in cloth lay-up and 3-D weave and with Nextel fiber in multi-layer braid. Measured permeability values range from near 100 to less than 0.1 darcies. Mass diffusivity is reported as a structure factor relating the diffusion through the porous material to that in free space. This measure is independent of the diffusing species and depends only on the pore structure of the material. Measurements are compared to predictions of a node-bond model for gas transport. Model parameters adjusted to match measured transport properties relate to physical microstructure features of the different architectures. Combination of this transport model with the CVI process model offers a predictive method to evaluate the densification behavior of various fiber preforms.

  17. Rare earths in ceramic materials technology

    International Nuclear Information System (INIS)

    Rare earth elements are mainly exploited for electronic devices, but far from negligible is their importance in materials for structural applications, i.e. for their mechanical properties, useful in modern technologies. For example, widely renown is the role of rare earth oxides in the study of zirconia (zirconium dioxide, ZrO2), by far the most interesting ceramic material for structural applications. Among rare earth oxides, ceria (cerium dioxide, CeO2) has played a fundamental role because at room temperature it stabilizes the tetragonal phase of zirconia, which is the most interesting phase from a mechanical point of view. In this presentation the main characteristics of the system CeO2-ZrO2 are outlined, along with the mechanical properties of binary alloys of the two oxides; these properties are evaluated as a function of their composition and microstructure. Some of these alloys exhibited behaviour completely unexpected for ceramic materials, e.g. the Shape Memory Effect (SME) and the Gorsky Effect. (orig.)

  18. Investigating Compositional Variation of Ceramic Materials during the Late Neolithic on the Great Hungarian Plain - Preliminary LA-ICP-MS Results

    Science.gov (United States)

    Riebe, Danielle J.; Niziolek, Lisa C.

    2015-10-01

    Investigations have been undertaken to assess the extent to which compositional analysis can be used to determine trade and interaction on the Great Hungarian Plain during the Late Neolithic. Ceramic and clay samples in the Körös and Berettyó River Basins were analyzed at the Elemental Analysis Facilities (EAF) at The Field Museum of Natural History in Chicago, IL, USA. With the use of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), the aim of the project was to ascertain if micro-regional or site-specific compositional signatures could be determined in a region that is typically characterized as highly geologically homogenous. Identifying site-specific signatures enables archaeologists to model prehistoric interactions and, in turn, determine the relationship between interaction and various socio-cultural changes. This paper focuses on the preliminary compositional results of materials analyzed from three different sites across the Plain and the methodological implications for future anthropological research in the region.

  19. Modification of composite ceramics properties via different preparation techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.A., E-mail: moala47@hotmail.com [Materials Science Laboratory (1) Physics Department, Faculty of Science, Cairo University, Giza (Egypt); Okasha, N. [Physics Department, Faculty of Girls, Ain Shams University, Cairo (Egypt); Imam, N.G. [Experimental Physics Department, Nuclear Research Center, Atomic Energy Authority, Cairo (Egypt)

    2012-12-15

    Modifying the proportion of the base composition by substituting with suitable dopents and improving the preparation conditions is expected to change the performance of composites. In the present study, 0.5(Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4})/0.5(BaTiO{sub 3}) composite was prepared by, the conventional ceramic technique and the citrate method. Ceramic particles, when prepared via different routes, would demonstrate different properties, even with the same starting compositions. With the help of X-ray diffraction, scanning electron microscope (SEM), magnetic properties, and electric properties of the composites have been compared. A critical comparison of those methods is needed to make the best choice for given boundary conditions of targeted eventual material properties, raw materials, investment, processing and waste disposal costs. - Highlights: Black-Right-Pointing-Pointer NZF/BT nanocomposite is successfully produced by citrate and ceramic techniques. Black-Right-Pointing-Pointer XRD found that, particle size and lattice constant of citrate are smaller than ceramic technique. Black-Right-Pointing-Pointer Excellent magnetic and dielectric properties in a wide range of frequency. Black-Right-Pointing-Pointer Citrate method offer preparation at lower temperatures. Black-Right-Pointing-Pointer Citrate method is less cumbersome, more versatile, and cost effective to obtain nano composites.

  20. Metal-ceramic composites for hostile environment applications

    International Nuclear Information System (INIS)

    The authors have developed a new metal-ceramic composite made from vanadium metal (V) and a non-stoichiometric magnesio-aluminate spinel ceramic. Three vanadium-spinel compositions, 40-60, 50-50, and 60-40 (by volume) were prepared by hot pressing mixtures of commercial powders. The properties of these composites were determined by measuring coefficient of thermal expansion, hardness, elastic constants, and fracture toughness. Radiation damage studies were performed on 50-50 vanadium-spinel composite samples using 1.5 MeV Xe+ ions, with samples held both at 20 K and at room temperature. Room temperature irradiated samples exhibited very little change in microstructure, indicating that this composite has radiation damage resistance qualities such as resistance to volume swelling under particle bombardment. This feature, as well as other properties reviewed in this paper, suggest that vanadium-spinel composites are attractive structural materials for fusion reactor design

  1. Oxygen diffusion in glasses and ceramic materials

    International Nuclear Information System (INIS)

    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)

  2. 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.

  3. Laminated alumina/zirconia ceramic composites prepared by electrophoretic

    Czech Academy of Sciences Publication Activity Database

    Hadraba, Hynek; Drdlík, D.; Chlup, Zdeněk; Maca, K.; Dlouhý, Ivo; Cihlář, J.

    2012-01-01

    Roč. 32, č. 9 (2012), s. 2053-2056. ISSN 0955-2219. [ Engineering Ceramics 2011 - from Materials to Components. Smolenice, 09.05.2011-12.05.2011] R&D Projects: GA ČR(CZ) GAP108/11/1644 Institutional research plan: CEZ:AV0Z20410507 Institutional support: RVO:68081723 Keywords : electrophoretic deposition * composites * hardness * Al2O3 * ZrO2 Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.360, year: 2012

  4. Support Services for Ceramic Fiber-Ceramic Matrix Composites

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, J.P.

    2000-06-06

    Structural and functional materials used in solid- and liquid-fueled energy systems are subject to gas- and condensed-phase corrosion and erosion by entrained particles. For a given material, its temperature and the composition of the corrodents determine the corrosion rates, while gas flow conditions and particle aerodynamic diameters determine erosion rates. Because there are several mechanisms by which corrodents deposit on a surface, the corrodent composition depends not only on the composition of the fuel, but also on the temperature of the material and the size range of the particles being deposited. In general, it is difficult to simulate under controlled laboratory conditions all of the possible corrosion and erosion mechanisms to which a material may be exposed in an energy system. Therefore, with funding from the Advanced Research Materials Program, the University of North Dakota Energy & Environmental Research Center (EERC) is coordinating with NCC Engineering and the National Energy Technology Laboratory (NETL) to provide researchers with no-cost opportunities to expose materials in pilot-scale systems to conditions of corrosion and erosion similar to those occurring in commercial power systems. The EERC has two pilot-scale solid-fuel systems available for exposure of materials coupons. The slagging furnace system (SFS) was built under the DOE Combustion 2000 Program as a testing facility for advanced heat exchanger subsystems. It is a 2.5-MMBtu/hr (2.6 x 10{sup 6} kJ/hr) solid-fuel combustion system with exit temperatures of 2700 to 2900 F to ensure that the ash in the main combustor is molten and flowing. Sample coupons may be exposed in the system either within the slagging zone or near the convective air heater at 1800 F (980 C). In addition, a pilot-scale entrained-bed gasifier system known as the transport reactor development unit (TRDU) is available. Also operating at approximately 2.5 MMBtu/hr (2.6 x 10{sup 6} kJ/hr), it is a pressurized unit

  5. Elaboration of new ceramic composites containing glass fibre production wastes

    International Nuclear Information System (INIS)

    Two main by-products or waste from the production of glass fibre are following: sewage sludge containing montmorillonite clay as sorbent material and ca 50 % of organic matter as well as waste glass from aluminium borosilicate glass fibre with relatively high softening temperature (> 600 degree centigrade). In order to elaborate different new ceramic products (porous or dense composites) the mentioned by-products and illicit clay from two different layers of Apriki deposit (Latvia) with illite content in clay fraction up to 80-90 % was used as a matrix. The raw materials were investigated by differential-thermal (DTA) and XRD analysis. Ternary compositions were prepared from mixtures of 15 - 35 wt % of sludge, 20 wt % of waste glass and 45 - 65 wt % of clay and the pressed green bodies were thermally treated in sintering temperature range from 1080 to 1120 degree centigrade in different treatment conditions. Materials produced in temperature range 1090 - 1100 degree centigrade with the most optimal properties - porosity 38 - 52 %, water absorption 39 - 47 % and bulk density 1.35 - 1.67 g/cm3 were selected for production of porous ceramics and materials showing porosity 0.35 - 1.1 %, water absorption 0.7 - 2.6 % and bulk density 2.1 - 2.3 g/cm3 - for dense ceramic composites. Obtained results indicated that incorporation up to 25 wt % of sewage sludge is beneficial for production of both ceramic products and glass-ceramic composites according to the technological properties. Structural analysis of elaborated composite materials was performed by scanning electron microscopy(SEM). By X-ray diffraction analysis (XRD) the quartz, diopside and anorthite crystalline phases were detected. (Author) 16 refs.

  6. Rapid Prototyping of Continuous Fiber Reinforced Ceramic Matrix Composites

    Science.gov (United States)

    Vaidyanathan, R.; Green, C.; Phillips, T.; Cipriani, R.; Yarlagadda, S.; Gillespie, J. W., Jr.; Effinger, M.; Cooper, K. C.

    2003-01-01

    For ceramics to be used as structural components in high temperature applications, their fracture toughness is improved by embedding continuous ceramic fibers. Ceramic matrix composite (CMC) materials allow increasing the overall operating temperature, raising the temperature safety margins, avoiding the need for cooling, and improving the damping capacity, while reducing the weight at the same time. They also need to be reliable and available in large quantities as well. In this paper, an innovative rapid prototyping technique to fabricate continuous fiber reinforced ceramic matrix composites is described. The process is simple, robust and will be widely applicable to a number of high temperature material systems. This technique was originally developed at the University of Delaware Center for Composite Materials (UD-CCM) for rapid fabrication of polymer matrix composites by a technique called automated tow placement or ATP. The results of mechanical properties and microstructural characterization are presented, together with examples of complex shapes and parts. It is believed that the process will be able to create complex shaped parts at an order of magnitude lower cost than current chemical vapor infiltration (CVI) and polymer impregnation and pyrolysis (PIP) processes.

  7. Silicone Resin Applications for Ceramic Precursors and Composites

    Directory of Open Access Journals (Sweden)

    Masaki Narisawa

    2010-06-01

    Full Text Available This article reviews the applications of silicone resins as ceramic precursors. The historical background of silicone synthesis chemistry is introduced to explain the production costs and supply availability of various silicones. Thermal degradation processes of silicones are classified in terms of the main chain structure and cyclic oligomer expulsion process, which determine the resulting ceramic yield and the chemical composition. The high temperature decomposition of Si-O-C beyond 1,400 °C in an inert atmosphere and formation of a protective silica layer on material surfaces beyond 1,200 °C in an oxidative atmosphere are discussed from the viewpoints of the wide chemical composition of the Si-O-C materials. Applications of the resins for binding agents, as starting materials for porous ceramics, matrix sources with impregnation, fiber spinning and ceramic adhesions are introduced. The recent development of the process of filler or cross-linking agent additions to resin compounds is also introduced. Such resin compounds are useful for obtaining thick coatings, MEMS parts and bulk ceramics, which are difficult to obtain by pyrolysis of simple organometallic precursors without additives.

  8. Multi-length-scale Material Model for SiC/SiC Ceramic-Matrix Composites (CMCs): Inclusion of In-Service Environmental Effects

    Science.gov (United States)

    Grujicic, M.; Galgalikar, R.; Snipes, J. S.; Ramaswami, S.

    2016-01-01

    In our recent work, a multi-length-scale room-temperature material model for SiC/SiC ceramic-matrix composites (CMCs) was derived and parameterized. The model was subsequently linked with a finite-element solver so that it could be used in a general room-temperature, structural/damage analysis of gas-turbine engine CMC components. Due to its multi-length-scale character, the material model enabled inclusion of the effects of fiber/tow (e.g., the volume fraction, size, and properties of the fibers; fiber-coating material/thickness; decohesion properties of the coating/matrix interfaces; etc.) and ply/lamina (e.g., the 0°/90° cross-ply versus plain-weave architectures, the extent of tow crimping in the case of the plain-weave plies, cohesive properties of the inter-ply boundaries, etc.) length-scale microstructural/architectural parameters on the mechanical response of the CMCs. One of the major limitations of the model is that it applies to the CMCs in their as-fabricated conditions (i.e., the effect of prolonged in-service environmental exposure and the associated material aging-degradation is not accounted for). In the present work, the model is upgraded to include such in-service environmental-exposure effects. To demonstrate the utility of the upgraded material model, it is used within a finite-element structural/failure analysis involving impact of a toboggan-shaped turbine shroud segment by a foreign object. The results obtained clearly revealed the effects that different aspects of the in-service environmental exposure have on the material degradation and the extent of damage suffered by the impacted CMC toboggan-shaped shroud segment.

  9. Multilayer Electroactive Polymer Composite Material

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2011-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  10. 3rd Workshop on metal ceramic materials for functional applications

    International Nuclear Information System (INIS)

    This workshop contains contributions about materials and processing, characterization and modeling of properties and applications of metallic ceramics and composite structures. It was held on behalf of the Taiwan-Austrian scientific collaboration in Vienna, June 4th - 6th 1997. (Suda)

  11. Method of producing a ceramic fiber-reinforced glass-ceramic matrix composite

    Science.gov (United States)

    Bansal, Narottam P. (Inventor)

    1994-01-01

    A fiber-reinforced composite composed of a BaO-Al2O3-2SiO2 (BAS) glass ceramic matrix is reinforced with CVD silicon carbide continuous fibers. A slurry of BAS glass powders is prepared and celsian seeds are added during ball melting. The slurry is cast into tapes which are cut to the proper size. Continuous CVD-SiC fibers are formed into mats of the desired size. The matrix tapes and the fiber mats are alternately stacked in the proper orientation. This tape-mat stack is warm pressed to produce a 'green' composite. The 'green' composite is then heated to an elevated temperature to burn out organic constituents. The remaining interim material is then hot pressed to form a silicon carbide fiber-reinforced celsian (BAS) glass-ceramic matrix composite which may be machined to size.

  12. A study of ceramic-lined composite steel pipes prepared by SHS centrifugal-thermite process

    OpenAIRE

    Li Yuxin; Jiang Letao; Lu Qing; Bai Peikang; Liu Bin; Wang Jianhong

    2016-01-01

    Al2O3 ceramic-lined steel pipe was produced by self-propagating high-temperature synthesis centrifugal thermite process (SHS C-T process) from Fe2O3 and Al as the raw materials. The composition, phase separation and microstructures were investigated. The result showed the ceramic lined pipe is composed of the three main layers of various compositions, which were subsequently determined to be Fe layer, the transition layer and the ceramic layer. Fe layer is ...

  13. Robocasting of Ceramics and Composites Using Fine Particle Suspensions

    International Nuclear Information System (INIS)

    Solid freeform fabrication is the near-net-shape manufacturing of components by sequentially stacking thin layers of material until complicated three dimensional shapes are produced. The operation is computer controlled and requires no molds. This exciting new field of technology provides engineers with the ability to rapidly produce prototype parts directly from CAD drawings and oftentimes little or no machining is necessary after fabrication. Techniques for freeform fabrication with several types of plastics and metals are already quite advanced and maybe reviewed in references 1 and 2. Very complicated plastic models can be fabricated by stereolithography, selective laser sintering, fused deposition modeling, or three-dimensional ink jet printing. Metals may be freeformed by the LENS(trademark) technique and porous ceramic bodies by three dimensional printing into a porous powder bed. However, methods for freeform fabrication that utilize particulate slurries to build dense ceramics and composites are not as well developed. The techniques that are being developed for the freeform fabrication of dense structural ceramics primarily revolve around the sequential layering of ceramic loaded polymers or waxes. Laminated Object Manufacturing and CAM-LEM processing use controlled stacking and laser cutting of ceramic tapes[2,3]. Similar to fused deposition modeling, ceramic loaded polymer/wax filaments are being used for the fused deposition of ceramics[2,4]. Extrusion freeform fabrication uses high pressure extrusion to deposit layers of ceramic loaded polymer/wax systems[1]. Modified stereolithographic techniques are also being developed using ceramic loaded ultraviolet curable resins[2]. Pre-sintered parts made with any of these techniques typically have 40-55 vol.% polymeric binder. In this regard, these techniques are analogous to powder injection molding of ceramics. Very long and complicated burnout heat treatments are necessary to produce a dense ceramic, free

  14. Robocasting of Ceramics and Composites Using Fine Particle Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    CESARANO III,JOSEPH

    1999-10-28

    Solid freeform fabrication is the near-net-shape manufacturing of components by sequentially stacking thin layers of material until complicated three dimensional shapes are produced. The operation is computer controlled and requires no molds. This exciting new field of technology provides engineers with the ability to rapidly produce prototype parts directly from CAD drawings and oftentimes little or no machining is necessary after fabrication. Techniques for freeform fabrication with several types of plastics and metals are already quite advanced and maybe reviewed in references 1 and 2. Very complicated plastic models can be fabricated by stereolithography, selective laser sintering, fused deposition modeling, or three-dimensional ink jet printing. Metals may be freeformed by the LENS{trademark} technique and porous ceramic bodies by three dimensional printing into a porous powder bed. However, methods for freeform fabrication that utilize particulate slurries to build dense ceramics and composites are not as well developed. The techniques that are being developed for the freeform fabrication of dense structural ceramics primarily revolve around the sequential layering of ceramic loaded polymers or waxes. Laminated Object Manufacturing and CAM-LEM processing use controlled stacking and laser cutting of ceramic tapes [2,3]. Similar to fused deposition modeling, ceramic loaded polymer/wax filaments are being used for the fused deposition of ceramics [2,4]. Extrusion freeform fabrication uses high pressure extrusion to deposit layers of ceramic loaded polymer/wax systems[1]. Modified stereolithographic techniques are also being developed using ceramic loaded ultraviolet curable resins [2]. Pre-sintered parts made with any of these techniques typically have 40-55 vol.% polymeric binder. In this regard, these techniques are analogous to powder injection molding of ceramics. Very long and complicated burnout heat treatments are necessary to produce a dense ceramic

  15. Oxidation-resistant interfacial coatings for continuous fiber ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Stinton, D.P.; Besmann, T.M.; Bleier, A. [Oak Ridge National Lab., TN (United States); Shanmugham, S.; Liaw, P.K. [Univ. of Tennessee, Knoxville, TN (United States)

    1995-08-01

    Continuous fiber ceramic composites mechanical behavior are influenced by the bonding characteristics between the fiber and the matrix. Finite modeling studies suggest that a low-modulus interfacial coating material will be effective in reducing the residual thermal stresses that are generated upon cooling from processing temperatures. Nicalon{trademark}/SiC composites with carbon, alumina and mullite interfacial coatings were fabricated with the SiC matrix deposited using a forced-flow, thermal gradient chemical vapor infiltration process. Composites with mullite interfacial coatings exhibited considerable fiber pull-out even after oxidation and have potential as a composite system.

  16. Material Constitutive Models for Creep and Rupture of SiC/SiC Ceramic-Matrix Composites (CMCs) Under Multiaxial Loading

    Science.gov (United States)

    Grujicic, Mica; Galgalikar, R.; Snipes, J. S.; Ramaswami, S.

    2016-05-01

    Material constitutive models for creep deformation and creep rupture of the SiC/SiC ceramic-matrix composites (CMCs) under general three-dimensional stress states have been developed and parameterized using one set of available experimental data for the effect of stress magnitude and temperature on the time-dependent creep deformation and rupture. To validate the models developed, another set of available experimental data was utilized for each model. The models were subsequently implemented in a user-material subroutine and coupled with a commercial finite element package in order to enable computational analysis of the performance and durability of CMC components used in high-temperature high-stress applications, such as those encountered in gas-turbine engines. In the last portion of the work, the problem of creep-controlled contact of a gas-turbine engine blade with the shroud is investigated computationally. It is assumed that the blade is made of the SiC/SiC CMC, and that the creep behavior of this material can be accounted for using the material constitutive models developed in the present work. The results clearly show that the blade-tip/shroud clearance decreases and ultimately becomes zero (the condition which must be avoided) as a function of time. In addition, the analysis revealed that if the blade is trimmed at its tip to enable additional creep deformation before blade-tip/shroud contact, creep-rupture conditions can develop in the region of the blade adjacent to its attachment to the high-rotational-speed hub.

  17. Material Constitutive Models for Creep and Rupture of SiC/SiC Ceramic-Matrix Composites (CMCs) Under Multiaxial Loading

    Science.gov (United States)

    Grujicic, Mica; Galgalikar, R.; Snipes, J. S.; Ramaswami, S.

    2016-04-01

    Material constitutive models for creep deformation and creep rupture of the SiC/SiC ceramic-matrix composites (CMCs) under general three-dimensional stress states have been developed and parameterized using one set of available experimental data for the effect of stress magnitude and temperature on the time-dependent creep deformation and rupture. To validate the models developed, another set of available experimental data was utilized for each model. The models were subsequently implemented in a user-material subroutine and coupled with a commercial finite element package in order to enable computational analysis of the performance and durability of CMC components used in high-temperature high-stress applications, such as those encountered in gas-turbine engines. In the last portion of the work, the problem of creep-controlled contact of a gas-turbine engine blade with the shroud is investigated computationally. It is assumed that the blade is made of the SiC/SiC CMC, and that the creep behavior of this material can be accounted for using the material constitutive models developed in the present work. The results clearly show that the blade-tip/shroud clearance decreases and ultimately becomes zero (the condition which must be avoided) as a function of time. In addition, the analysis revealed that if the blade is trimmed at its tip to enable additional creep deformation before blade-tip/shroud contact, creep-rupture conditions can develop in the region of the blade adjacent to its attachment to the high-rotational-speed hub.

  18. Overview: Damage resistance of graded ceramic restorative materials

    OpenAIRE

    Zhang, Yu

    2012-01-01

    Improving mechanical response of materials is of great interest in a wide range of disciplines, including biomechanics, tribology, geology, optoelectronics, and nanotechnology. It has been long recognized that spatial gradients in surface composition and structure can improve the mechanical integrity of a material. This review surveys recent results of sliding-contact, flexural, and fatigue tests on graded ceramic materials from our laboratories and elsewhere. Although our findings are examin...

  19. Whisker-reinforced ceramic composites for heat engine components

    Science.gov (United States)

    Duffy, Stephen F.

    1988-01-01

    Much work was undertaken to develop techniques of incorporating SiC whiskers into either a Si3N4 or SiC matrix. The result was the fabrication of ceramic composites with ever-increasing fracture toughness and strength. To complement this research effort, the fracture behavior of whisker-reinforced ceramics is studied so as to develop methodologies for the analysis of structural components fabricated from this toughened material. The results, outlined herein, focus on the following areas: the use of micromechanics to predict thermoelastic properties, theoretical aspects of fracture behavior, and reliability analysis.

  20. Experimental Investigation on Active Cooling for Ceramic Matrix Composite

    Institute of Scientific and Technical Information of China (English)

    PENG Li-na; HE Guo-qiang; LIU Pei-jin

    2009-01-01

    Compared with conventional materials, the active cooling ceramic matrix composite used in ramjet or scramjet makes their structures lighter in mass and better in performance. In this paper, an active and a passive cooling refractory composite specimens are designed and tested with an experimental facility composed of multilayer smale scale cooling penel which consists of a water cooling system and a ceramic matrix composite specimen, and a gas generator used for providing lower and higher transfer rate gases to simulate the temperatures in combustion chamber of ramjst. The active cooling specimen can continuously suffer high surface temperature of 2 000K for 30s and that of 3 000 K for 9.3 s, respectively. The experiment results show that the active cooling composite structure is available for high-temperature condition in ramjet.

  1. Environmental Barrier Coatings for Ceramics and Ceramic Composites

    Science.gov (United States)

    Lee, Kang N.; Fox, Dennis; Eldridge, Jeffrey; Robinson, R. Craig; Bansal, Narottam

    2004-01-01

    One key factor that limits the performance of current gas turbine engines is the temperature capability of hot section structural components. Silicon-based ceramics, such as SiC/SiC composites and monolithic Si3N4, are leading candidates to replace superalloy hot section components in the next generation gas turbine engines due to their excellent high temperature properties. A major stumbling block to realizing Si-based ceramic hot section components is the recession of Si-based ceramics in combustion environments due to the volatilization of silica scale by water vapor. An external environmental barrier coating (EBC) is the most promising approach to preventing the recession. Current EBCs are based on silicon, mullite (3A12O3-2SiO2) and BSAS (barium strontium aluminum silicate with celsian structure). Volatility of BSAS, BSAS-silica chemical reaction, and low melting point of silicon limit the durability and temperature capability of current EBCs. Research is underway to develop EBCs with longer life and enhanced temperature capability. Understanding key issues affecting the performance of current EBCs is necessary for successful development of advanced EBCs. These issues include stress, chemical compatibility, adherence, and water vapor stability. Factors that affect stress are thermal expansion mismatch, phase stability, chemical stability, elastic modulus, etc. The current understanding on these issues will be discussed.

  2. Effects of superfine refractory carbide additives on microstructure and mechanical properties of TiB2–TiC+Al2O3 composite ceramic cutting tool materials

    International Nuclear Information System (INIS)

    Highlights: • The superfine carbides determined the mechanical properties of composites. • Superfine HfC or TaC caused some oxide impurities in composites. • Superfine VC or NbC refined and homogenized the microstructure. • Failure of composites containing HfC or TaC was produced by larger grains. • Composite containing VC exhibited more bridging and transcrystalline failure. -- Abstract: A study to increase the mechanical properties of TiB2–TiC+Al2O3 composite ceramic cutting tool material by using superfine refractory carbide additives is presented. Four superfine refractory carbides are considered to investigate their effects on the phase composition, element distribution, grain size, fracture surface, crack propagation of the metal ceramic. The physicochemical properties of superfine carbides, such as chemical activities and atom radius, were found to have the significant effects on the microstructure and mechanical properties of the metal ceramic. Hafnium carbide (HfC) and Tantalum carbide (TaC) reduced the mechanical properties of the metal ceramic because of their poor solubility with the Ni binder phase and the formation of oxides. The mechanical properties of the metal ceramic were increased by the addition of superfine niobium carbide (NbC) and vanadium carbide (VC), and their optimum values were a flexural strength of 1100 ± 62 MPa, fracture toughness of 8.5 ± 0.8 MPa.m1/2 and hardness of 21.53 ± 0.36 GPa, respectively, when 3.2 wt% superfine VC was used

  3. Effects of superfine refractory carbide additives on microstructure and mechanical properties of TiB{sub 2}–TiC+Al{sub 2}O{sub 3} composite ceramic cutting tool materials

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Bin, E-mail: zou20011110@163.com [Centre for Advanced Jet Engineering Technologies (CaJET), School of Mechanical Engineering, Shandong University, Jinan 250061 (China); Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Shandong University, Ministry of Education (China); Ji, Wenbin; Huang, Chuanzhen; Wang, Jun [Centre for Advanced Jet Engineering Technologies (CaJET), School of Mechanical Engineering, Shandong University, Jinan 250061 (China); Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Shandong University, Ministry of Education (China); Li, Shasha [Shandong Special Equipment Inspection Institute, Jinan 250013 (China); Xu, Kaitao [Centre for Advanced Jet Engineering Technologies (CaJET), School of Mechanical Engineering, Shandong University, Jinan 250061 (China); Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Shandong University, Ministry of Education (China)

    2014-02-05

    Highlights: • The superfine carbides determined the mechanical properties of composites. • Superfine HfC or TaC caused some oxide impurities in composites. • Superfine VC or NbC refined and homogenized the microstructure. • Failure of composites containing HfC or TaC was produced by larger grains. • Composite containing VC exhibited more bridging and transcrystalline failure. -- Abstract: A study to increase the mechanical properties of TiB{sub 2}–TiC+Al{sub 2}O{sub 3} composite ceramic cutting tool material by using superfine refractory carbide additives is presented. Four superfine refractory carbides are considered to investigate their effects on the phase composition, element distribution, grain size, fracture surface, crack propagation of the metal ceramic. The physicochemical properties of superfine carbides, such as chemical activities and atom radius, were found to have the significant effects on the microstructure and mechanical properties of the metal ceramic. Hafnium carbide (HfC) and Tantalum carbide (TaC) reduced the mechanical properties of the metal ceramic because of their poor solubility with the Ni binder phase and the formation of oxides. The mechanical properties of the metal ceramic were increased by the addition of superfine niobium carbide (NbC) and vanadium carbide (VC), and their optimum values were a flexural strength of 1100 ± 62 MPa, fracture toughness of 8.5 ± 0.8 MPa.m1/2 and hardness of 21.53 ± 0.36 GPa, respectively, when 3.2 wt% superfine VC was used.

  4. Dynamic properties of ceramic materials

    International Nuclear Information System (INIS)

    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

  5. Microstructure and mechanical properties of TiB2–TiC–WC composite ceramic tool materials

    International Nuclear Information System (INIS)

    Highlights: ►Effect of sintering parameters on TiB2–TiC–WC composites has been investigated. ► Ni element was dispersed in the interface between WC and matrix grains. ► The fracture mode changed from intergranular fracture to transgranular fracture. ► The microstructure and mechanical properties of the composite were improved. -- Abstract: TiB2–TiC–WC composites with Ni as a sintering aid were fabricated by a hot-press technique at 1700 °C and 1650 °C for 1 h, respectively. The microstructure and mechanical properties were investigated. The composites were analyzed by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectrometry (EDS). The matrix phases consisted of TiB2 and TiC. No severe chemical reactions happened between the additive and matrix. The microstructure consisted of the fine WC grains and uniform matrix grains. When the proper WC content added to TiB2–TiC composites, the growth of matrix grains was inhibited and the mechanical properties of the composites were improved. The interface energy was strengthened by Ni that dispersed in the interfaces among WC grains and matrix grains, which made the fracture mode change from intergranular fracture to transgranular fracture. The transgranular fracture and the pulling out of WC grains played a predominant role in the propagating of cracks when WC content was 20 wt.% in TiB2–TiC–WC composites. The optimal mechanical properties of TiB2–TiC–20 wt.%WC composite were 955.71 MPa of flexural strength, 7.5 MPa m1/2 of fracture toughness and 23.5 GPa of Vickers hardness.

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

    Science.gov (United States)

    Singh, M.

    2013-01-01

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

  7. Numerical Homogenization of Protective Ceramic Composite Layers using the Hybrid Finite-Discrete Element Methods

    Directory of Open Access Journals (Sweden)

    Zainorizuan Mohd Jaini

    2013-12-01

    Full Text Available Innovative technologies have resulted in more effective ceramic composite as high rate loading-resistance and protective layer. The ceramic composite layer consists of ceramic frontal plate that bonded by softer-strong reinforced polymer network, consequently gains the heterogeneous condition. These materials serve specific purposes of defeating high rate loading and maintaining the structural integrity of the layer. Further due to the lack of a constituent material and tedious problem in heterogonous material modelling, a numerical homogenization is employed to analyse the isotropic material properties of ceramic composite layer in homogenous manner. The objective of this study is to derive a constitutive law of the ceramic composite using the multi-scale analysis. Two-dimensional symmetric macrostructure of the ceramic composite was numerically modelled using the hybrid finite-discrete element method to investigate the effective material properties and strength profile. The macrostructure was modelled as brittle material with nonlinear material properties. The finite element method is incorporated with a Rankine-Rotating Crack approach and discrete element to model the fracture onset. The prescribed uniaxial and biaxial loadings were imposed along the free boundaries to create different deformations. Due to crack initiation on the macrostructure, the averaged stresses were calculated to plot the stress-strain curves and the effective yield stress surface. From the multi-scale analysis, the rate-dependency of Mohr-Coulomb constitutive law was derived for the ceramic composite layer.

  8. XRD applied to the determination of pigments and composition of lithic materials and ceramics from archaeological pre-hispanic sites of the Rio de la Plata

    Energy Technology Data Exchange (ETDEWEB)

    Beovide, Laura [Department of Archeology, National Museum of Anthropology, Montevideo, (Uruguay); Pardo, Helena; Faccio, Ricardo; Mombru, Alvaro [Centro NanoMat, Polo Tecnologico de Pando, Facultad de Quimica, Universidad de la Republica, Pando, Canelones (Uruguay); Crystallography, Solid State and Materials Laboratory (Cryssmat-Lab), DETEMA, Facultad de Quimica, Universidad de la Republica, Gral, Montevideo (Uruguay); Piston, Mariela, E-mail: mpiston@fq.edu.u [Analytical Chemistry, Estrella Campos Department, Facultad de Quimica, Universidad de la Republica, Montevideo (Uruguay)

    2011-07-01

    Full text: The earliest records of human occupation on the lower basin of Santa Lucia River are dated ca. 4800 {sup 14}C years BP, in the area of one of the major tributaries of the Rio de la Plata on the Uruguayan coast. These societies were basically hunters and gatherers until ca. 3000 {sup 14}C years BP when they incorporated the horticulture. In this multidisciplinary work, two cases of application of XRD analysis of archaeological materials are presented to provide new perspectives in solving various problems related to the technological organization of these societies. In the first case, ceramics and pigments from an archaeological context prior to the hispanic-indian contact were analyzed. The X-ray powder diffraction patterns were obtained using a RIGAKU, Ultima IV with CBO monochromator, CuK{sub {alpha}} radiation was at 40 kV and 20 mA tube power at 0.02 deg/seg, operating in the range from 2{theta}=5.00 to 60.00 deg. According the comparison between the experimental recorded X-ray diffraction pattern to those stored in a X-ray powder diffraction database reveals that the piece of pottery is mainly constitute of quartz (SiO{sub 2}) and hematite (Fe{sub 2}O{sub 3}) while the mineral sample is probably composed mainly of quartz (SiO{sub 2}) and goethite (FeO{sub 3}.H{sub 2}O). The results allow a first approximation to know the inorganic pigments that were part of the decoration of the pottery and pigments used in the archaeological context. In the second case an amphibolite instrument from ca. 2700 {sup 14}C years BP related to a shell midden was analyzed and compared with amphibolites located 15 km of the archaeological site to assess if they were the raw materials for these instruments. Compositional XRD mineralogical analysis shows that the both samples seem to have similar mineral composition, which is mainly quartz (SiO{sub 2}) and a mixed sodium magnesium and calcium silicate (NaCa{sub 2}(Mg{sub 4}Ti)Si{sub 6}Al{sub 2}O{sub 23}(OH){sub 2}). This

  9. XRD applied to the determination of pigments and composition of lithic materials and ceramics from archaeological pre-hispanic sites of the Rio de la Plata

    International Nuclear Information System (INIS)

    Full text: The earliest records of human occupation on the lower basin of Santa Lucia River are dated ca. 4800 14C years BP, in the area of one of the major tributaries of the Rio de la Plata on the Uruguayan coast. These societies were basically hunters and gatherers until ca. 3000 14C years BP when they incorporated the horticulture. In this multidisciplinary work, two cases of application of XRD analysis of archaeological materials are presented to provide new perspectives in solving various problems related to the technological organization of these societies. In the first case, ceramics and pigments from an archaeological context prior to the hispanic-indian contact were analyzed. The X-ray powder diffraction patterns were obtained using a RIGAKU, Ultima IV with CBO monochromator, CuKα radiation was at 40 kV and 20 mA tube power at 0.02 deg/seg, operating in the range from 2θ=5.00 to 60.00 deg. According the comparison between the experimental recorded X-ray diffraction pattern to those stored in a X-ray powder diffraction database reveals that the piece of pottery is mainly constitute of quartz (SiO2) and hematite (Fe2O3) while the mineral sample is probably composed mainly of quartz (SiO2) and goethite (FeO3.H2O). The results allow a first approximation to know the inorganic pigments that were part of the decoration of the pottery and pigments used in the archaeological context. In the second case an amphibolite instrument from ca. 2700 14C years BP related to a shell midden was analyzed and compared with amphibolites located 15 km of the archaeological site to assess if they were the raw materials for these instruments. Compositional XRD mineralogical analysis shows that the both samples seem to have similar mineral composition, which is mainly quartz (SiO2) and a mixed sodium magnesium and calcium silicate (NaCa2(Mg4Ti)Si6Al2O23(OH)2). This suggests that most likely the source of supply for the amphibolites instruments come from the sources of raw

  10. High temperature resistant cermet and ceramic compositions

    Science.gov (United States)

    Phillips, W. M. (Inventor)

    1978-01-01

    Cermet compositions having high temperature oxidation resistance, high hardness and high abrasion and wear resistance, and particularly adapted for production of high temperature resistant cermet insulator bodies are presented. The compositions are comprised of a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Also disclosed are novel ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride.

  11. Exposure of Ceramics and Ceramic Matrix Composites in Simulated and Actual Combustor Environments

    Energy Technology Data Exchange (ETDEWEB)

    Brentnall, W.D.; Ferber, M.K.; Keiser, j.R.; Miriyala, N.; More, K.L.; Price, J.R.; Tortorelli, P.F.; Walker, L.R.

    1999-06-07

    A high-temperature, high-pressure, tube furnace has been used to evaluate the long term stability of different monolithic ceramic and ceramic matrix composite materials in a simulated combustor environment. All of the tests have been run at 150 psia, 1204 degrees C, and 15% steam in incremental 500 h runs. The major advantage of this system is the high sample throughput; >20 samples can be exposed in each tube at the same time under similar exposure conditions. Microstructural evaluations of the samples were conducted after each 500 h exposure to characterize the extent of surface damage, to calculate surface recession rates, and to determine degradation mechanisms for the different materials. The validity of this exposure rig for simulating real combustor environments was established by comparing materials exposed in the test rig and combustor liner materials exposed for similar times in an actual gas turbine combustor under commercial operating conditions.

  12. Novel low temperature processing techniques for apatite ceramics and chitosan polymer composite bulk materials and its mechanical properties

    International Nuclear Information System (INIS)

    Highlights: ► CHI and DCPD were mixed in nano-scale by co-precipitation method. ► Bulk CHI/HA materials derived from the CHI/DCPD hybrid material were obtained by hydrothermal hot-pressing. ► Fracture toughness of the obtained bulk materials was enhanced from 0.30 to 0.40 MPam1/2 by the CHI hybridization. - Abstract: A co-precipitation method was used for processing chitosan (CHI)/calcium hydrogen phosphate dehydrate (DCPD) hybrid material. CHI solution was mixed into 1.0-M calcium nitrate solution. CHI/DCPD hybrid material was prepared by the above explained addition of CHI and Ca ion source to 1.0-M diammonium hydrogen phosphate solution. It was observed by transmission electron microscopy that CHI and DCPD were mixed within submicron meter scale. CHI/HA bulk materials derived from the CHI/DCPD hybrid materials were obtained by using a hydrothermal hot-pressing (HHP) method. A pressure of 40 MPa was initially applied to the sample. An HHP autoclave was heated up to 150 °C for 2 h. Modified 3-point bending tests were conducted to obtain an easy estimate of the fracture toughness for the CHI/HA bulk materials made with the HHP method. The critical stress intensity factor Kc of the fabricated CHI/HA bulk materials was enhanced from 0.30 to 0.40 MPam1/2 by the hybridization of CHI into DCPD.

  13. Clay materials for ceramic tiles from the Sassuolo District (Northern Apennines, Italy). Geology, composition and echnological properties

    OpenAIRE

    Dondi, M.

    1999-01-01

    In the Sassuolo area (northern Italy) there is the largest tilemaking district in the world, which has practically served over the past years as an industrial scale laboratory for assessing the technological properties of clays and their suitability for the production of wall and floor tiles. The local clays are recovered from different geological units and distinguished in mio principal types, with clearly differentiated compositions and technological properties: "marly clays" and "red shale...

  14. Continuous Fiber Ceramic Composites (CFCC)

    Energy Technology Data Exchange (ETDEWEB)

    R. A. Wagner

    2002-12-18

    This report summarizes work to develop CFCC's for various applications in the Industries of the Future (IOF) and power generation areas. Performance requirements range from relatively modest for hot gas filters to severe for turbine combustor liners and infrared burners. The McDermott Technology Inc. (MTI) CFCC program focused on oxide/oxide composite systems because they are known to be stable in the application environments of interest. The work is broadly focused on dense and porous composite systems depending on the specific application. Dense composites were targeted at corrosion resistant components, molten aluminum handling components and gas turbine combustor liners. The development work on dense composites led to significant advances in fiber coatings for oxide fibers and matrix densification. Additionally, a one-step fabrication process was developed to produce low cost composite components. The program also supported key developments in advanced oxide fibers that resulted in an improved version of Nextel 610 fiber (commercially available as Nextel 650) and significant progress in the development of a YAG/alumina fiber. Porous composite development focused on the vacuum winding process used to produce hot gas filters and infrared burner components.

  15. Novel low temperature processing techniques for apatite ceramics and chitosan polymer composite bulk materials and its mechanical properties

    Science.gov (United States)

    Onoki, Takamasa; Nakahira, Atsushi; Tago, Tomoyuki; Hasegawa, Yoshiyuki; Kuno, Tomoaki

    2012-12-01

    A co-precipitation method was used for processing chitosan (CHI)/calcium hydrogen phosphate dehydrate (DCPD) hybrid material. CHI solution was mixed into 1.0-M calcium nitrate solution. CHI/DCPD hybrid material was prepared by the above explained addition of CHI and Ca ion source to 1.0-M diammonium hydrogen phosphate solution. It was observed by transmission electron microscopy that CHI and DCPD were mixed within submicron meter scale. CHI/HA bulk materials derived from the CHI/DCPD hybrid materials were obtained by using a hydrothermal hot-pressing (HHP) method. A pressure of 40 MPa was initially applied to the sample. An HHP autoclave was heated up to 150 °C for 2 h. Modified 3-point bending tests were conducted to obtain an easy estimate of the fracture toughness for the CHI/HA bulk materials made with the HHP method. The critical stress intensity factor Kc of the fabricated CHI/HA bulk materials was enhanced from 0.30 to 0.40 MPam1/2 by the hybridization of CHI into DCPD.

  16. Valorization of rice straw waste: an alternative ceramic raw material

    Directory of Open Access Journals (Sweden)

    Á. Guzmán A

    2015-03-01

    Full Text Available In the production of rice a large amount of solid residue is produced, for which alternative utilizations are scarce or are not commonly applied in industry. Rice straw (RS is a waste product of rice harvest that is generated in equal or greater quantities than the rice itself. RS is frequently burned in open air, which makes it a significant source of pollution. In the search for possible uses of RS, it should be noted that its ash (RSA is particularly rich in silica, alkaline and alkaline earth metals and may be used as a source of alkalis and silica for the production of triaxial ceramics. The present research work proposes the production of a ceramic raw material from RS for its use in the fabrication of ceramic materials for the construction industry. Based on the chemical and mineralogical composition of RSA created under different thermal conditions, the most suitable RSA for this purpose was that obtained from treating RS at a temperature of 800 ºC for a time of 2 h. The resulting RSA presented high contents of SiO2 (79.62%, alkaline oxides (K2O (10.53% and alkaline earth oxides (CaO (2.80%. It is concluded that RSA is a new alternative ceramic raw material that can be used as a replacement for the fluxing (mainly feldspar and inert (quartz materials that are used in the production of triaxial ceramics.

  17. Photon CT scanning of advanced ceramic materials

    International Nuclear Information System (INIS)

    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

  18. FRACTURAL PROCESS AND TOUGHENING MECHANISM OF LAMINATED CERAMIC COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Based on the model of multi-layer beam and the assumption of micro-inhomogeneity of material, the 3D fractural characteristics of laminated ceramic composites have been studied with numerical simulation. Under three-point bending load, crack initiation, coalescence, propagation, tuning off in the weak interface and final rupture have been simulated. The spatial distribution and evolution process of acoustic emission are also presented in the paper. The simulation verifies the primary mechanism of the weak interface inducing the crack to expand along there and absorbing the fractural energy. The disciplinary significance of the effect of strength and properties of material on the toughness and strength of laminated ceramic composites is, therefore,discussed in this paper.

  19. Ceramic matrix and resin matrix composites - A comparison

    Science.gov (United States)

    Hurwitz, Frances I.

    1987-01-01

    The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.

  20. Ceramic matrix and resin matrix composites: A comparison

    Science.gov (United States)

    Hurwitz, Frances I.

    1987-01-01

    The underlying theory of continuous fiber reinforcement of ceramic matrix and resin matrix composites, their fabrication, microstructure, physical and mechanical properties are contrasted. The growing use of organometallic polymers as precursors to ceramic matrices is discussed as a means of providing low temperature processing capability without the fiber degradation encountered with more conventional ceramic processing techniques. Examples of ceramic matrix composites derived from particulate-filled, high char yield polymers and silsesquioxane precursors are provided.

  1. Current Issues with Environmental Barrier Coatings for Ceramics and Ceramic Composites

    Science.gov (United States)

    Lee, Kang N.

    2004-01-01

    The environmental barrier coating (EBC) for SiC/SiC ceramic matrix composites and Si3N4 ceramics is an emerging field as the application of silicon-based ceramics in the gas turbine engine hot section is on the horizon, both for aero and industrial gas turbines. EBC is an enabling technology for silicon-based ceramics because these materials without an EBC cannot be used in combustion environments due to rapid surface recession. Significant progress in EBC development has been made during the last decade through various government-sponsored programs. Current EBCs are based on silicon, mullite (3Al2O3-2SiO2) and BSAS (barium strontium aluminum silicate with celsian structure). Volatility of BSAS, BSAS-silica chemical reaction, and low melting point of silicon limit temperature capability of current EBCs to about 1350 C for long-term applications. There is a need for higher temperature EBCs as the temperature capability of silicon-based ceramics continue to increase. Therefore, research is underway to develop EBCs with improved temperature capability compared to current EBCs. The current status and issues with the advanced EBC development efforts will be discussed.

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

    Science.gov (United States)

    Halbig, Michael Charles; Singh, Mrityunjay

    2015-01-01

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

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

    Science.gov (United States)

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

    2016-03-01

    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.

  4. Improved Foreign Object Damage Performance for 3D Woven Ceramic Matrix Composites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As the power density of advanced engines increases, the need for new materials that are capable of higher operating temperatures, such as ceramic matrix composites...

  5. Improved Foreign Object Damage Performance for 2D Woven Ceramic Matrix Composites Project

    Data.gov (United States)

    National Aeronautics and Space Administration — As the power density of advanced engines increases, the need for new materials that are capable of higher operating temperatures, such as ceramic matrix composites...

  6. Ceramic Composite Mechanical Fastener System for High-Temperature Structural Assemblies Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Hot structures fabricated from ceramic composite materials are an attractive design option for components of future high-speed aircraft, re-entry vehicles and...

  7. An Investigation of Reliability Models for Ceramic Matrix Composites and their Implementation into Finite Element Codes

    Science.gov (United States)

    Duffy, Stephen F.

    1998-01-01

    The development of modeling approaches for the failure analysis of ceramic-based material systems used in high temperature environments was the primary objective of this research effort. These materials have the potential to support many key engineering technologies related to the design of aeropropulsion systems. Monolithic ceramics exhibit a number of useful properties such as retention of strength at high temperatures, chemical inertness, and low density. However, the use of monolithic ceramics has been limited by their inherent brittleness and a large variation in strength. This behavior has motivated material scientists to reinforce the monolithic material with a ceramic fiber. The addition of a second ceramic phase with an optimized interface increases toughness and marginally increases strength. The primary purpose of the fiber is to arrest crack growth, not to increase strength. The material systems of interest in this research effort were laminated ceramic matrix composites, as well as two- and three- dimensional fabric reinforced ceramic composites. These emerging composite systems can compete with metals in many demanding applications. However, the ongoing metamorphosis of ceramic composite material systems, and the lack of standardized design data has in the past tended to minimize research efforts related to structural analysis. Many structural components fabricated from ceramic matrix composites (CMC) have been designed by "trial and error." The justification for this approach lies in the fact that during the initial developmental phases for a material system fabrication issues are paramount. Emphasis is placed on demonstrating feasibility rather than fully understanding the processes controlling mechanical behavior. This is understandable during periods of rapid improvements in material properties for any composite system. But to avoid the ad hoc approach, the analytical methods developed under this effort can be used to develop rational structural

  8. Thermophysical properties and elastic moduli of alumina-zirconia composite ceramics

    Czech Academy of Sciences Publication Activity Database

    Hostaša, J.; Pabst, W.; Matějíček, Jiří; Gregorová, E.; Malangré, D.

    Stockholm : City Conference Centre(CCC), 2011, s. 722-722. [Conference of the European Ceramic Society (ECerS XII)/12th./. Stockholm (SE), 19.06.2011-23.06.2011] Institutional research plan: CEZ:AV0Z20430508 Keywords : alumina * zirconia * composites * thermal diffusivity * elastic modulus Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  9. Smart Energy Materials of PZT Ceramics

    Directory of Open Access Journals (Sweden)

    Mitsuhiro Okayasu

    2015-10-01

    Full Text Available To better understand the material properties of lead zirconate titanate (PZT ceramics, the domain-switching characteristics and electric power generation characteristics have been investigated during loading and unloading by using various experimental techniques. Furthermore, the influence of oscillation condition on the electrical power generation properties of lead zirconate titanate (PZT piezoelectric ceramics has been investigated. It is found that the power generation is directly attributed to the applied load and wave mode. The voltage rises instantly to the maximum level under square-wave mode, although the voltage increases gradually under triangular-wave mode. After this initial increase, there is a rapid fall to zero, followed by generation of increasingly negative voltage as the applied load is removed for all wave modes. Variation of the electric voltage is reflected by the cyclic loading at higher loading frequencies. On the basis of the obtained experimental results for the wave modes, the electrical power generation characteristics of PZT ceramics are proposed, and the voltages generated during loading and unloading are accurately estimated. The electric generation value is decrease with increasing the cyclic number due to the material failure, e.g., domain switching and crack. The influence of domain switching on the mechanical properties PZT piezoelectric ceramics is clarified, and 90 degree domain switching occurs after the load is applied to the PZT ceramic directly. Note that, in this paper, our experimental results obtained in our previous works were introduced [1,2].

  10. Stereological characterization of crack path transitions in ceramic matrix composites

    Indian Academy of Sciences (India)

    Parag Bhargava; B R Patterson

    2001-04-01

    All ceramic composites involve a mismatch in physical properties the extent of which differs from one composite to another. Mismatch in thermal expansion ( ) and elastic modulus (E) is known to produce stresses that influence the path of a propagating crack. Thus, the relative effect of thermal and elastic mismatch on the crack path is expected to change with change in stress intensity. We propose that the crack path in ceramic composites should undergo a transition with the crack being strongly influenced by the thermal mismatch stresses at low stress intensity and elastic mismatch stresses at high stress intensities. Thus, a material in use under different applications each with its own loading conditions is expected to exhibit different crack propagation tendencies which may be reflected in the – characteristics of the composite material. In the present work several model composites with different combinations of thermal and elastic mismatch have been considered. Cracks propagating at different sub-critical stress intensities (velocities) were generated by a novel indentation technique. Each indentation was performed at a constant displacement rate and a peak load. A range of displacement rates were used to produce cracks propagating at different velocities. The indentations were made using a Vickers indentor fitted in a universal mechanical testing machine. The crack paths in composites were quantified by stereological technique and the proposed theory was verified.

  11. Mechanical properties of dense to porous alumina/lanthanum hexaaluminate composite ceramics

    International Nuclear Information System (INIS)

    For development of new composite materials based on lanthanum hexaaluminate and alumina ceramics, a better understanding of the microstructure-properties relationship is essential. In this paper, attention was focused on the evaluation of mechanical properties of lanthanum hexaaluminate/alumina particulate composite. It was found out that the lanthanum hexaaluminate content plays a critical role in determination of the microstructure and mechanical properties of the composite ceramics. In situ formation of plate-like lanthanum hexaaluminate in the ceramic matrix was accompanied with formation of pores so that the microstructure shifted from dense to porous. Increasing the lanthanum hexaaluminate content up to a certain value enhanced the fracture toughness, increased the hardness, and increased the elastic modulus of the composite materials. Further increase in the lanthanum hexaaluminate content degraded the hardness as well as the elastic modulus of composite ceramics. The influence of lanthanum hexaaluminate on mechanical properties was described by means of microstructure, porosity, and intrinsic characteristics of lanthanum hexaaluminate.

  12. Magnetic Resonance Imaging of Gel-cast Ceramic Composites

    Science.gov (United States)

    Dieckman, S. L.; Balss, K. M.; Waterfield, L. G.; Jendrzejczyk, J. A.; Raptis, A. C.

    1997-01-16

    Magnetic resonance imaging (MRI) techniques are being employed to aid in the development of advanced near-net-shape gel-cast ceramic composites. MRI is a unique nondestructive evaluation tool that provides information on both the chemical and physical properties of materials. In this effort, MRI imaging was performed to monitor the drying of porous green-state alumina - methacrylamide-N.N`-methylene bisacrylamide (MAM-MBAM) polymerized composite specimens. Studies were performed on several specimens as a function of humidity and time. The mass and shrinkage of the specimens were also monitored and correlated with the water content.

  13. Summary of workshop on ceramic composite interface coatings

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-08-01

    Commercialization of fiber-reinforced composites has been limited because of the stability of the interface coatings that control the mechanical properties of the composites. Typical materials are currently manufactured with pyrolytic carbon interface coatings that perform well in inert atmospheres or when stresses are kept very low (<70 MPa). Unfortunately, carbon coatings are not stable at high temperatures in air or oxidizing conditions which results in degradation of the mechanical properties of the composites. The problem of oxidation resistant interface coatings is not unique to the Fossil Program. Such coatings are also a concern to the United States Air Force, the Continuous Fiber-reinforced Ceramic Composites Program, the Fusion Energy Materials Program, and to the European Community. This workshop was organized to compare and discuss the need for and development of oxidation-resistant interface coatings in each of these programs.

  14. PREPARATION OF Al₂O₃-CaAl₁₂O₁₉-ZrO₂ COMPOSITE CERAMIC MATERIAL BY THE HYDRATION AND SINTERING OF Ca₇ZrAl₆O₁₈-REACTIVE ALUMINA MIXTURE

    Directory of Open Access Journals (Sweden)

    Dominika Madej

    2016-03-01

    Full Text Available Ceramic material of composition belonging to the Al₂O₃-CaAl₁₂O₁₉-ZrO₂ compatibility field was obtained as a result of hydration and sintering of the mixture of Al₂O₃ and Ca₇ZrAl₆O₁₈ powders. The hydrated Al₂O₃- Ca₇ZrAl₆O₁₈ mixture products were studied by XRD, DTA-TG-EGA and FT-IR after 14 days of curing and hydration at 50°C. C₃AH₆, Al(OH₃ and CaZrO₃ compounds were formed upon hydration. CaZrO₃ and the lime-rich calcium aluminates formed as transient phases during hydration and dehydration processes were converted to CA6 and ZrO₂ in the presence of an excess of Al₂O₃ during sintering at 1500°C. The Al₂O₃-based dense refractory composite material was investigated by XRD, FT-IR, SEM-EDS and mercury porosimetry. The sintered ceramic microstructure consists of a homogeneous distribution of zirconia grains in an alumina matrix reinforced with the calcium hexaaluminate phase. The presence of Al₂O₃, CaAl₁₂O₁₉ and ZrO₂ in the synthesized material was confirmed by XRD and FT-IR techniques. By applying the mercury intrusion porosimetry technique, the heterogeneous pore size distribution of the refractory composite material was determined.

  15. Melt Infiltrated Ceramic Composites (Hipercomp) for Gas Turbine Engine Applications

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Corman; Krishan Luthra

    2005-09-30

    This report covers work performed under the Continuous Fiber Ceramic Composites (CFCC) program by GE Global Research and its partners from 1994 through 2005. The processing of prepreg-derived, melt infiltrated (MI) composite systems based on monofilament and multifilament tow SiC fibers is described. Extensive mechanical and environmental exposure characterizations were performed on these systems, as well as on competing Ceramic Matrix Composite (CMC) systems. Although current monofilament SiC fibers have inherent oxidative stability limitations due to their carbon surface coatings, the MI CMC system based on multifilament tow (Hi-Nicalon ) proved to have excellent mechanical, thermal and time-dependent properties. The materials database generated from the material testing was used to design turbine hot gas path components, namely the shroud and combustor liner, utilizing the CMC materials. The feasibility of using such MI CMC materials in gas turbine engines was demonstrated via combustion rig testing of turbine shrouds and combustor liners, and through field engine tests of shrouds in a 2MW engine for >1000 hours. A unique combustion test facility was also developed that allowed coupons of the CMC materials to be exposed to high-pressure, high-velocity combustion gas environments for times up to {approx}4000 hours.

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

    International Nuclear Information System (INIS)

    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)

  17. Silicon nitride ceramic material having an in-situ continuous gradient function, process for manufacture, properties and applications thereof

    OpenAIRE

    Belmonte, Manuel; González Julián, Jesús; Miranzo López, Pilar; Osendi, María Isabel

    2008-01-01

    [EN] The present invention relates to a silicon mitride ceramic material having a continuous gradient in the microstructural characteristics thereof and in the properties thereof, from one extremity to the other of the ceramic component. Furthermore a method is described for the manufacture in situ of said ceramic materials having a gradient function from a single homogenous composition of ceramic powders and employing a sintering process through electric discharge modifying the temperatu...

  18. Plasma etching a ceramic composite. [evaluating microstructure

    Science.gov (United States)

    Hull, David R.; Leonhardt, Todd A.; Sanders, William A.

    1992-01-01

    Plasma etching is found to be a superior metallographic technique for evaluating the microstructure of a ceramic matrix composite. The ceramic composite studied is composed of silicon carbide whiskers (SiC(sub W)) in a matrix of silicon nitride (Si3N4), glass, and pores. All four constituents are important in evaluating the microstructure of the composite. Conventionally prepared samples, both as-polished or polished and etched with molten salt, do not allow all four constituents to be observed in one specimen. As-polished specimens allow examination of the glass phase and porosity, while molten salt etching reveals the Si3N4 grain size by removing the glass phase. However, the latter obscures the porosity. Neither technique allows the SiC(sub W) to be distinguished from the Si3N4. Plasma etching with CF4 + 4 percent O2 selectively attacks the Si3N4 grains, leaving SiC(sub W) and glass in relief, while not disturbing the pores. An artifact of the plasma etching reaction is the deposition of a thin layer of carbon on Si3N4, allowing Si3N4 grains to be distinguished from SiC(sub W) by back scattered electron imaging.

  19. Conductive ceramic composition and method of preparation

    Science.gov (United States)

    Smith, J.L.; Kucera, E.H.

    1991-04-16

    A ceramic anode composition is formed of a multivalent metal oxide or oxygenate such as an alkali metal, transition metal oxygenate. The anode is prepared as a non-stoichiometric crystalline structure by reaction and conditioning in a hydrogen gas cover containing minor proportions of carbon dioxide and water vapor. The structure exhibits a single phase and substantially enhanced electrical conductivity over that of the corresponding stoichiometric structure. Unexpectedly, such oxides and oxygenates are found to be stable in the reducing anode fuel gas of a molten carbonate fuel cell. 4 figures.

  20. Description of strengthening mechanism in layered ceramic composites

    Czech Academy of Sciences Publication Activity Database

    Štegnerová, Kateřina; Náhlík, Luboš; Hutař, Pavel

    Zurich: Trans Tech Publications, 2016 - (Bajić, D.; Tonković, Z.; Aliabadi, F.), s. 93-96. (Key Engineering Materials. 665). ISBN 978-3-03835-541-0. ISSN 1013-9826. [FDM 2015 International Conference on Fracture and Damage /14./. Budva (ME), 21.09.2015-23.09.2015] R&D Projects: GA ČR(CZ) GA15-09347S Institutional support: RVO:68081723 Keywords : layered ceramic composite s * residual stresses * crack propagation * strain energy density factor Subject RIV: JL - Materials Fatigue, Friction Mechanics www.scientific.net/KEM.665.93

  1. Fluorine 18 in tritium generator ceramic materials

    International Nuclear Information System (INIS)

    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 LiAlO2 and the Li2O. 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)

  2. Materials Research Society Proceedings: Interfaces in Composites, volume 170

    Science.gov (United States)

    Pantano, Carlo G.; Chen, Eric J. H.

    1990-11-01

    Reports on the following topics are presented: (1) micromechanics of interfaces; (2) characterization of interfaces; (3) interface reactions in ceramic and metal systems; (4) interface effects in ceramic and metal matrix composites; and (5) interface effects in polymer matrix composites. A list of the materials research society symposium proceedings is also presented.

  3. Improved C/SiC Ceramic Composites Made Using PIP

    Science.gov (United States)

    Easler, Timothy

    2007-01-01

    Improved carbon-fiber-reinforced SiC ceramic-matrix composite (C/SiC CMC) materials, suitable for fabrication of thick-section structural components, are producible by use of a combination of raw materials and processing conditions different from such combinations used in the prior art. In comparison with prior C/SiC CMC materials, these materials have more nearly uniform density, less porosity, and greater strength. The majority of raw-material/processing-condition combinations used in the prior art involve the use of chemical vapor infiltration (CVI) for densifying the matrix. In contrast, in synthesizing a material of the present type, one uses a combination of infiltration with, and pyrolysis of, a preceramic polymer [polymer infiltration followed by pyrolysis (PIP)]. PIP processing is performed in repeated, tailored cycles of infiltration followed by pyrolysis. Densification by PIP processing takes less time and costs less than does densification by CVI. When one of these improved materials was tested by exposure to a high-temperature, inert-gas environment that caused prior C/SiC CMCs to lose strength, this material did not lose strength. (Information on the temperature and exposure time was not available at the time of writing this article.) A material of the present improved type consists, more specifically, of (1) carbon fibers coated with an engineered fiber/matrix interface material and (2) a ceramic matrix, containing SiC, derived from a pre-ceramic polymer with ceramic powder additions. The enhancements of properties of these materials relative to those of prior C/SiC CMC materials are attributable largely to engineering of the fiber/ matrix interfacial material and the densification process. The synthesis of a material of this type includes processing at an elevated temperature to a low level of open porosity. The approach followed in this processing allows one to fabricate not only simple plates but also more complexly shaped parts. The carbon fiber

  4. Federal Aviation Administration (FAA) airworthiness certification for ceramic matrix composite components in civil aircraft systems

    OpenAIRE

    Gonczy Stephen T.

    2015-01-01

    Ceramic matrix composites (CMCs) are being designed and developed for engine and exhaust components in commercial aviation, because they offer higher temperature capabilities, weight savings, and improved durability compared to metals. The United States Federal Aviation Administration (FAA) issues and enforces regulations and minimum standards covering the safe manufacture, operation, and maintenance of civil aircraft. As new materials, these ceramic composite components will have to meet the...

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

    Science.gov (United States)

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

    2013-01-01

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

  6. Design Concepts for Cooled Ceramic Matrix Composite Turbine Vanes

    Science.gov (United States)

    Boyle, Robert

    2014-01-01

    This project demonstrated that higher temperature capabilities of ceramic matrix composites (CMCs) can be used to reduce emissions and improve fuel consumption in gas turbine engines. The work involved closely coupling aerothermal and structural analyses for the first-stage vane of a high-pressure turbine (HPT). These vanes are actively cooled, typically using film cooling. Ceramic materials have structural and thermal properties different from conventional metals used for the first-stage HPT vane. This project identified vane configurations that satisfy CMC structural strength and life constraints while maintaining vane aerodynamic efficiency and reducing vane cooling to improve engine performance and reduce emissions. The project examined modifications to vane internal configurations to achieve the desired objectives. Thermal and pressure stresses are equally important, and both were analyzed using an ANSYS® structural analysis. Three-dimensional fluid and heat transfer analyses were used to determine vane aerodynamic performance and heat load distributions.

  7. Toughening and strengthening of ceramics composite through microstructural refinement

    Science.gov (United States)

    Anggraini, Lydia; Isonishi, Kazuo; Ameyama, Kei

    2016-04-01

    Silicon carbide with 50 mass% zirconia ceramic matrix composites were processed by mechanical milling (MM) followed by spark plasma sintering (SPS). By controlling the parameters of MM and SPS, an ultra-fine ZrO2 grain was homogeneously dispersed and refined on the surface of a fine SiC powder, forming a harmonic microstructure. The mechanical properties and the densification behavior of the SiC-ZrO2 composites were investigated. The effects of the milling time on the microstructure and on the mechanical properties of the composite are discussed. The results indicate that the composite mechanically milled for 144 ks and sintered at 1773 K had the highest relative density of 98 %, along with a fracture toughness of 10.7 MPa.m1/2 and a bending strength of 1128 MPa. These superior mechanical properties were influenced by the microstructure characteristics such as the homogeneous grain dispersion. Thus, the microstructural refinement forming harmonic dispersion can be considered a remarkable design tool for improving the mechanical properties of SiC-ZrO2, as well as other ceramic composite materials.

  8. Perspectives of development of ceramic materials with luminescent applications

    International Nuclear Information System (INIS)

    The science and technology of materials believes and it applies the knowledge that allow to relate the composition, it structures and the one processed with those properties that those they make capable for each one of the applications. The ceramic materials are inorganic materials not metallic, constituted by metallic elements and not metallic. In general, they usually behave, as good insulating electric and thermal due to the absence of conductive electrons. Usually, they possess relatively high coalition temperatures and, also, a chemical stability relatively high. Due to these properties, they are indispensable for many of those designs in engineering. The ceramic materials for luminescent applications are constituted typically by pure compounds (Al2O3, TiO2, SiO2 and ZrO2) or cocktails with some sludges giving as a result (Al2O3:TR, TiO2:Eu, Si:ZrO2, ZrO2:TR). Presently work describes the panorama to big features on the development of ceramic materials in the CICATA Unit it would Bequeath, which can be characterized by the photoluminescence techniques and thermoluminescence mainly. (Author)

  9. Fusion ceramic materials and components

    International Nuclear Information System (INIS)

    Present-day approach for the radiation hardness assurance of components and materials for the International Thermonuclear Experimental Reactor ITER is based on extensive testing under representative conditions. Those conditions include radiation, temperature and vacuum and the possibility of in-situ monitoring of radiation-induced changes in characteristics of interest. The resistive bolometers are an example of an ITER component currently tested at SCK-CEN. Bolometers will be used for the plasma emission monitoring in high-radiation and high-temperature locations such as the divertor region. Previous tests with bolometers having gold strips on mica substrates were performed in the JMTR (Japan) and revealed problems of adhesion of the strips on the mica surface, which naturally has a very low roughness. A new type of the resistive bolometer based on platinum meander on alumina or aluminum-nitride (AlN) substrates have to be tested at a high neutron flux (0.01 dpa), high temperature (400 C) and in vacuum (10-3 mBar)- conditions appropriate for the ITER. Another illustration of on-going radiation testing for the ITER is the investigation of the Radiation-Induced Electrical Degradation (RIED). RIED is degradation of electrical insulation under the combined effect of radiation, temperature, vacuum and a strong electric field. It may be an issue to be dealt with in the design phase. Our objective is to develop instrumentation capabilities, which can provide in-situ data on the radiation hardness of materials and components intended for the use in the ITER. These capabilities will allow assessment of the performance parameters under conditions representative in terms of radiation load, temperature and vacuum, and will include on-line electric measurements

  10. Randomized Clinical Trial of Indirect Resin Composite and Ceramic Veneers : Up to 3-year Follow-up

    NARCIS (Netherlands)

    Gresnigt, Marco M. M.; Kalk, Warner; Ozcan, Mutlu

    2013-01-01

    Purpose: This randomized controlled split-mouth clinical trial evaluated the short-term survival rate of indirect resin composite and ceramic laminate veneers. Materials and Methods: A total of 10 patients (mean age: 48.6 years) received 46 indirect resin composite (Estenia; n = 23) and ceramic lami

  11. Microstructure characteristics of FeMo-Sialon ceramic composite

    International Nuclear Information System (INIS)

    A new metal-Sialon based ceramic composite of FeMo-Sialon has been processed using Si3N4, α-Al2O3 and FeMo70 alloy powders as the main raw materials. To explain why this composite has excellent mechanical properties, microstructure characterizations are carried out using the transmission electron microscopy (TEM) and selected area electron diffraction (SAED). The results show that FeMo, FeSi2 and Mo have formed an alloy mixture of Mo-Fe-Si in the FeMo-Sialon ceramic composite. Elongated β-Sialon crystals, interlacing with each other, vary in size. The Y-SiAlON glass, as an inter-granular phase, surrounds the grain boundaries of β-Sialon crystals. Some of β-Sialon crystals are semi-surrounded by dumbbell-like Mo-Fe-Si particles. The good mechanical properties of FeMo-Sialon composite are greatly dependent on the elongated Sialon grains and Mo-Fe-Si particles with interlocking structures.

  12. A study of ceramic-lined composite steel pipes prepared by SHS centrifugal-thermite process

    Directory of Open Access Journals (Sweden)

    Li Yuxin

    2016-01-01

    Full Text Available Al2O3 ceramic-lined steel pipe was produced by self-propagating high-temperature synthesis centrifugal thermite process (SHS C-T process from Fe2O3 and Al as the raw materials. The composition, phase separation and microstructures were investigated. The result showed the ceramic lined pipe is composed of the three main layers of various compositions, which were subsequently determined to be Fe layer, the transition layer and the ceramic layer. Fe layer is composed of austenite and ferrite, the transition layer consisted of Al2O3 ceramic and Fe, the ceramic layer consisted of the dendritic-shaped Al2O3 and the spinel-shaped structured FeAl2O4.

  13. Nano-composite materials

    Science.gov (United States)

    Lee, Se-Hee; Tracy, C. Edwin; Pitts, J. Roland

    2010-05-25

    Nano-composite materials are disclosed. An exemplary method of producing a nano-composite material may comprise co-sputtering a transition metal and a refractory metal in a reactive atmosphere. The method may also comprise co-depositing a transition metal and a refractory metal composite structure on a substrate. The method may further comprise thermally annealing the deposited transition metal and refractory metal composite structure in a reactive atmosphere.

  14. Ceramic matrix composites in simulated SSME environments

    Science.gov (United States)

    Herbell, Thomas P.; Eckel, Andrew J.

    1988-01-01

    Future Space Shuttle Main Engine (SSME)-type rocket engines can benefit from the use of fiber-reinforced ceramix matrix composites (FRCMC). Ceramics reinforced with long continuous fibers exhibit improved tolerance to severe thermomechanical and environmental exposures. An in-house NASA-Lewis program to evaluate the durability of FRCMC in simulated SSME environments is described. Primary tests involve multiple (one second) exposures of FRCMC specimens in a hydrogen/oxygen rocket test rig. This rig generates surface heating rates of 1000 to 2500 C/second. The FRCMC durability evaluation involves measurement of retained strength as a function of thermal shock severity and number of upshock cycles. Preliminary test results for monolithic silicon nitride (Si3N4) and silicon carbide (SiC), and one type of silicon based FRCMC, are presented. The test data are examined in terms of simple thermal shock theory.

  15. Theory and experimental technique for nondestructive evaluation of ceramic composites

    Science.gov (United States)

    Generazio, Edward R.

    1990-01-01

    The important ultrasonic scattering mechanisms for SiC and Si3N4 ceramic composites were identified by examining the interaction of ultrasound with individual fibers, pores, and grains. The dominant scattering mechanisms were identified as asymmetric refractive scattering due to porosity gradients in the matrix material, and symmetric diffractive scattering at the fiber-to-matrix interface and at individual pores. The effect of the ultrasonic reflection coefficient and surface roughness in the ultrasonic evaluation was highlighted. A new nonintrusive ultrasonic evaluation technique, angular power spectrum scanning (APSS), was presented that is sensitive to microstructural variations in composites. Preliminary results indicate that APSS will yield information on the composite microstructure that is not available by any other nondestructive technique.

  16. Preparation of nano-segmented SiOC, SiONC and related ceramics and their optimization as composite matrices

    Czech Academy of Sciences Publication Activity Database

    Strachota, Adam; Depa, Katarzyna; Brus, Jiří; Pleštil, Josef; Černý, Martin; Sucharda, Z.; Chlup, Zdeněk

    Gothenburg: Division for Surface and Material Chemistry of the Swedish Chemical Society, 2012. P4. [ Material s for Tomorrow 2012. 23.10.2012-25.10.2012, Gothenburg] R&D Projects: GA ČR GAP107/12/2445 Institutional support: RVO:61389013 ; RVO:67985891 ; RVO:68081723 Keywords : silicon oxycarbide * ceramics * nano composites Subject RIV: JI - Composite Material s; JH - Ceramics, Fire-Resistant Material s and Glass (USMH-B)

  17. Addition of alternative materials to ceramic slabs

    Directory of Open Access Journals (Sweden)

    E. O. B. Nara

    2014-09-01

    Full Text Available The construction market is very growing, leading to the emergence of new technologies and materials, and a growing need for sustainable products for the construction process, and the call for quality of life we present the description of a new option alternative materials for environments that require careful with the acoustics. The research covers the development and incorporation of new material in construction, with the potential acoustic, from tests and measurements with calibrated decibel meter called. We also used the ceramic tiles pre-molded, used for making floors or ceilings in buildings and homes. The methodology used for the development of this research was characterized as literature, exploratory, descriptive, qualitative and quantitative, alternative and affordable. How after the analysis results of the tests performed it can be seen that the incorporation of rice hulls of agglomerated to form ceramic tiles, possible reductions in noise levels on the order of 8 dB (A than the traditional construction of the buildings, and then an excellent material. This research contributes to the construction so that presented a description of a new product developed from a conventional material, originating in agriculture, waste rice husk and its incorporation during the construction of buildings and home, with the potential acoustic observed from tests and measurements with calibrated decibel meter called.

  18. Multifunctional Composite Materials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Polymeric composite materials that are currently utilized in aircraft structures are susceptible to significant damage from lightning strikes. Enhanced electrical...

  19. In-situ Formation of Reinforcement Phases in Ultra High Temperature Ceramic Composites

    Science.gov (United States)

    Stackpoole, Margaret M (Inventor); Gasch, Matthew J (Inventor); Olson, Michael W (Inventor); Hamby, Ian W. (Inventor); Johnson, Sylvia M (Inventor)

    2013-01-01

    A tough ultra-high temperature ceramic (UHTC) composite comprises grains of UHTC matrix material, such as HfB.sub.2, ZrB.sub.2 or other metal boride, carbide, nitride, etc., surrounded by a uniform distribution of acicular high aspect ratio reinforcement ceramic rods or whiskers, such as of SiC, is formed from uniformly mixing a powder of the UHTC material and a pre-ceramic polymer selected to form the desired reinforcement species, then thermally consolidating the mixture by hot pressing. The acicular reinforcement rods may make up from 5 to 30 vol % of the resulting microstructure.

  20. Uses of Advanced Ceramic Composites in the Thermal Protection Systems of Future Space Vehicles

    Science.gov (United States)

    Rasky, Daniel J.

    1994-01-01

    Current ceramic composites being developed and characterized for use in the thermal protection systems (TPS) of future space vehicles are reviewed. The composites discussed include new tough, low density ceramic insulation's, both rigid and flexible; ultra-high temperature ceramic composites; nano-ceramics; as well as new hybrid ceramic/metallic and ceramic/organic systems. Application and advantage of these new composites to the thermal protection systems of future reusable access to space vehicles and small spacecraft is reviewed.

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

    International Nuclear Information System (INIS)

    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)

  2. Composite materials based on EN AW-Al Cu4Mg1(A aluminum alloy reinforced with the BN ceramic particles

    Directory of Open Access Journals (Sweden)

    A. Włodarczyk-Fligier

    2010-03-01

    Full Text Available Purpose: the aim of the project was to evaluate of the effect of heat treatment and the reinforcing BN particles content on the mechanical properties, abrasive wear and corrosion resistance in the NaCl water solution environment on the EN AW-AlCu4Mg1(A aluminium alloy matrix composite.Design/methodology/approach: Some of the composite materials were hyperquenched for 0.5 h at the temperature of 495ºC with the subsequent cooling in water, and were quench aged next for 6 h at 200°C. Hardness tests were made on HAUSER hardness tester with the Vickers method at 10 N. Static compression and tensile tests of the fabricated composite materials were made on the ZWICK 100 type testing machine at room temperature. Abrasion resistance wear tests were carried out with the constant number of cycles of 5000 (120 m at various loads: 4, 5, 6, 7, and 8 N. Test pieces were rinsed in the ultrasonic washer to clean them and next were weighed on the analytical balance with the accuracy of 0.0001 g to check the mass loss. Corrosion tests were made in 5% water NaCl solution.Findings: Besides visible improvement of mechanical properties: hardness, compression strength and tensile strength, wear resistance there were also observed the influence of heat treatment on the corrosion resistance of composite materials in 3% NaCl solution.Practical implications: Tested composite materials can be applicate among the others in automotive industry but it requires additional researches.Originality/value: It was demonstrated that the mechanical properties, as well as the wear and corrosion resistance of the extruded composite materials with the EN AW-Al Cu4Mg1(A alloy matrix may be formed by the dispersion hardening with the BN particles in various portions and by the precipitation hardening of the matrix.

  3. Processes for fabricating composite reinforced material

    Energy Technology Data Exchange (ETDEWEB)

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2015-11-24

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  4. ThermophysicalProperties of Cellular Aluminium andCeramic Particulate / Aluminium Composites

    Directory of Open Access Journals (Sweden)

    Khalid Almadhoni

    2015-10-01

    Full Text Available In this paper, the thermophysical properties of cellular Al and Ceramic Particulate / Al Composites were explored. Thermophysical properties are defined as material properties that vary with temperature without altering the material's chemical identity including thermal conductivity (TC, coefficient of thermal expansion (CTE, energy absorption, porosity and relative density. The significance of cellular Al and AMMCs reinforced by ceramic particles lies in their propertieswhich are difficult to be available combined in other engineering materials. New cellular AMMCs that meet the needs of the required engineering applications could be synthesized by selection an appropriate reinforcements. Different kinds of ceramic particles such as oxides, carbides, nitrides, as well as carbon nanotubes can be utilized as reinforcements for manufacturing of cellular AMMCs. Thermophysicalproperties of cellular AMMCs consisting of Al as continuous matrix phase and ceramic particles as reinforcements are directly influenced by type, size, and geometry of dispersions, also the RVR. In addition, the constituents of ceramic particulate / aluminium composites characterized by different heat transfer mechanisms, wherethe TC mechanism in metals is attributed to free electrons, while phonons are primarily responsible for TC in nonmetallic materials, as well as an interfacial thermal barrier resistance influence effectively on heat transfer inside the composite and thus the thermophysical properties. In this paper, based on the literature review, thermophysical properties of cellular Al and AMMCs reinforced by ceramic particles were discussed.

  5. Laser hearth melt processing of ceramic materials

    Science.gov (United States)

    Richard Weber, J. K.; Felten, J. J.; Nordine, Paul C.

    1996-02-01

    A new technique for synthesizing small batches of oxide-based ceramic and glass materials from high purity powders is described. The method uses continuous wave CO2 laser beam heating of material held on a water-cooled copper hearth. Contamination which would normally result during crucible melting is eliminated. Details of the technique are presented, and its operation and use are illustrated by results obtained in melting experiments with a-aluminum oxide, Y-Ba-Cu-O superconductor material, and the mixtures, Al2O3-SiO2, Bi2O3-B2O3, Bi2O3-CuO. Specimen masses were 0.05-1.5 g.

  6. Friction Material Composites Materials Perspective

    CERN Document Server

    Sundarkrishnaa, K L

    2012-01-01

    Friction Material Composites is the first of the five volumes which strongly educates and updates engineers and other professionals in braking industries, research and test labs. It explains besides the formulation of design processes and its complete manufacturing input. This book gives an idea of mechanisms of friction and how to control them by designing .The book is  useful for designers  of automotive, rail and aero industries for designing the brake systems effectively with the integration of friction material composite design which is critical. It clearly  emphasizes the driving  safety and how serious designers should  select the design input. The significance of friction material component like brake pad or a liner as an integral part of the brake system of vehicles is explained. AFM pictures at nanolevel illustrate broadly the explanations given.

  7. An irradiation test of heat-resistant ceramic composite materials (2). Interim report on post-irradiation examinations of the second and third preliminary test: 98M-41A, 99M-30A

    International Nuclear Information System (INIS)

    The Japan Atomic Energy Research Institute (JAERI) has been carrying out the research on radiation damage mechanism of heat-resistant ceramic composite materials, as one of the subjects of the innovative basic research on high temperature engineering using the High Temperature Engineering Test Reactor (HTTR). A series of preliminary irradiation tests is being made using the Japan Materials Testing Reactor (JMTR). The present report describes results of post-irradiation examinations (PIE) so far on specimens irradiated in the second and third capsule, designated 98M-41A and 99M-30A, to fast neutron fluencies of 1.0x1025 m-2 (E > 1 MeV) at temperatures of 973-1173K and 1273-1473K. The PIE were conducted as the fundamental statistic index of the diametral dimensions for irradiated specimen, irradiation induced dimensional change rate and thermal expansion rate. (author)

  8. Modeling oxidation damage of continuous fiber reinforced ceramic matrix composites

    Institute of Scientific and Technical Information of China (English)

    Cheng-Peng Yang; Gui-Qiong Jiao; Bo Wang

    2011-01-01

    For fiber reinforced ceramic matrix composites (CMCs), oxidation of the constituents is a very important damage type for high temperature applications. During the oxidizing process, the pyrolytic carbon interphase gradually recesses from the crack site in the axial direction of the fiber into the interior of the material. Carbon fiber usually presents notch-like or local neck-shrink oxidation phenomenon, causing strength degradation. But, the reason for SiC fiber degradation is the flaw growth mechanism on its surface. A micromechanical model based on the above mechanisms was established to simulate the mechanical properties of CMCs after high temperature oxidation. The statistic and shearlag theory were applied and the calculation expressions for retained tensile modulus and strength were deduced, respectively. Meanwhile, the interphase recession and fiber strength degradation were considered. And then, the model was validated by application to a C/SiC composite.

  9. Design Concepts for Cooled Ceramic Matrix Composite Turbine Vanes Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The work proposed herein is to demonstrate that the higher temperature capabilities of Ceramic Matrix Composites (CMC) can be fully utilized to reduce emissions and...

  10. Cement-based piezoelectric ceramic composites for sensor applications in civil engineering

    Science.gov (United States)

    Dong, Biqin

    The objectives of this thesis are to develop and apply a new smart composite for the sensing and actuation application of civil engineering. Piezoelectric ceramic powder is incorporated into cement-based composite to achieve the sensing and actuation capability. The research investigates microstructure, polarization and aging, material properties and performance of cement-based piezoelectric ceramic composites both theoretically and experimentally. A hydrogen bonding is found at the interface of piezoelectric ceramic powder and cement phase by IR (Infrared Ray), XPS (X-ray Photoelectron Spectroscopy) and SIMS (Secondary Ion Mass Spectroscopy). It largely affects the material properties of composites. A simple first order model is introduced to explain the poling mechanism of composites and the dependency of polarization is discussed using electromechanical coupling coefficient kt. The mechanisms acting on the aging effect is explored in detail. Dielectrical, piezoelectric and mechanical properties of the cement-based piezoelectric ceramic composites are studied by experiment and theoretical calculation based on modified cube model (n=1) with chemical bonding . A complex circuit model is proposed to explain the unique feature of impedance spectra and the instinct of high-loss of cement-based piezoelectric ceramic composite. The sensing ability of cement-based piezoelectric ceramic composite has been evaluated by using step wave, sine wave, and random wave. It shows that the output of the composite can reflects the nature and characteristics of mechanical input. The work in this thesis opens a new direction for the current actuation/sensing technology in civil engineering. The materials and techniques, developed in this work, have a great potential in application of health monitoring of buildings and infrastructures.

  11. Temperature Rise during Resin Composite Polymerization under Different Ceramic Restorations

    OpenAIRE

    Yondem, Isa; Altintas, Subutay Han; Usumez, Aslihan

    2011-01-01

    Objectives: The purpose of this study was to measure temperature increase induced by various light polymerizing units during resin composite polymerization beneath one of three types of ceramic restorations. Methods: The resin composite (Variolink II) was polymerized between one of three different ceramic specimens (zirconium oxide, lithium disilicate, feldspathic) (diameter 5 mm, height 2 mm) and a dentin disc (diameter 5 mm, height 1 mm) with a conventional halogen light, a high intensity h...

  12. Tough hybrid ceramic-based material with high strength

    International Nuclear Information System (INIS)

    This study describes a tough and strong hybrid ceramic material consisting of platelet-like zirconium compounds and metal. A mixture of boron carbide and excess zirconium powder was heated to 1900 °C using a liquid-phase reaction sintering technique to produce a platelet-like ZrB2-based hybrid ceramic bonded by a thin zirconium layer. The platelet-like ZrB2 grains were randomly present in the as-sintered hybrid ceramic. Relative to non-hybrid ceramics, the fracture toughness and flexural strength of the hybrid ceramic increased by approximately 2-fold.

  13. Corrosion resistance of the sintered composite materials with the EN AW-AlCu4Mg1(a alloy matrix reinforced with ceramic particles

    Directory of Open Access Journals (Sweden)

    A. Włodarczyk-Fligier

    2010-09-01

    Full Text Available Purpose: the aim of the project was to evaluate of the effect of heat treatment and the reinforcing Al2O3 and Ti(C,N particles content on the corrosion resistance in the NaCl water solution environment on the EN AW-AlCu4Mg1(A aluminium alloy matrix composite.Design/methodology/approach: Powders of the starting materials were wet mixed in the laboratory vibratory ball mill to obtain the uniform distribution of the reinforcement particles in the matrix. The mixed powders were then dried in the air. The components were initially compacted at cold state in a die with the diameter of Ø 26 mm in the laboratory vertical unidirectional press – with a capacity of 350 kN. The selected compacting load was sufficient to obtain prepregs which would not crumble and at the same time would not be deformed too much, which would also have the adverse effect on their quality, as the excessive air pressure in the closed pores causes breaking the prepreg up when it is taken out from the die. The obtained PM compacts were heated to a temperature of 480-500˚C and finally extruded – with the extrusion pressure of 500 kN. Some of the composite materials were hyperquenched for 0.5 h at the temperature of 495ºC with the subsequent cooling in water, and were quench aged next for 6 h at 200°C. Corrosion tests were made in 5% water NaCl solution.Findings: Composite materials were examined without heat treatment and after heat treatment carried out to improve their corrosion resistance. The corrosion susceptibility of the investigated composite materials determined using the potentiodynamic method in the 3% water solution of NaCl depends on the volume fraction of the reinforcing particles and also on the heat treatment status.Practical implications: Tested composite materials can be applicate among the others in automotive industry but it requires additional researches.Originality/value: It was demonstrated corrosion resistance of the extruded composite materials with

  14. High temperature deformation of ZrB2-SiC-AlN ceramic composite

    International Nuclear Information System (INIS)

    ZrB2 ceramic composites are powerful candidates for use in ultra-high temperature structural materials given their strength under high temperatures, superb ablation resistance, and good oxidation resistance. Unfortunately, ZrB2 ceramic composites are difficult to deform due to inherent brittle property, which impedes large-scale application. High temperature deformation of ZrB2-SiC-AlN ceramic composite at 1900 deg. C with inert gas protection is investigated using deep drawing technique. The deformation behavior under biaxial stress and the microstructure characteristics are analyzed using scanning electron microscopy (SEM) along with energy dispersive spectroscopy (EDS). The results indicate that the fine grain ZrB2-SiC-AlN ceramic composites have excellent high temperature deformation property at 1900 deg. C. The effects of inducting AlN into ZrB2-SiC ceramic and punch rate on high temperature deformation are discussed. The deformation mechanism of ceramic composites is proposed correspondingly.

  15. UV laser micromachining of ceramic materials: formation of columnar topographies

    International Nuclear Information System (INIS)

    Laser machining is increasingly appearing as an alternative for micromachining of ceramics. Using ceramic materials using excimer lasers can result in smooth surfaces or in the formation of cone-like or columnar topography. Potential applications of cone-shaped or columnar surface topography include, for example, light trapping in anti-reflection coatings and improvement of adhesion bonding between ceramic materials. In this communication results of a comparative study of surface topography change during micromachining of several ceramic materials with different ablation behaviors are reported. (orig.)

  16. High-temperature testing of glass/ceramic matrix composites

    Science.gov (United States)

    Mandell, John F.; Grande, Dodd H.; Dannemann, Kathryn A.

    1989-01-01

    Recent advances in ceramic and other high-temperature composites have created a need for test methods that can be used at 1000 C and above. Present test methods usually require adhesively bonded tabs that cannot be used at high temperatures. This paper discusses some of the difficulties with high-temperature test development and describes several promising test methods. Stress-strain data are given for Nicalon ceramic fiber reinforced glass and glass-ceramic matrix composites tested in air at temperatures up to 1000 C.

  17. Factors Affecting Fiber Design and Selection for Advanced Ceramic Composites

    Science.gov (United States)

    DiCarlo, James A.

    1998-01-01

    Structural Ceramic Matrix Composites (CMC) have the potential for application in the hot sections of a variety of advanced propulsion and power systems. It is therefore necessary to have a general understanding of the key properties of CMC and Reinforcing Fibers. This need is complicated by the wide variety of application conditions and structural requirements for which CMC's will be used, and the proprietary concerns of the design engineers. CMC's, to be successful, must display properties which are competitive with the currently used high temperature structural materials: (i.e., Iron and Nickel based superalloys, tough monolithic ceramics, and carbon/carbon composites.) Structural CMC offers several areas of competition: (1) performance, (i.e., strength and strength retention, creep resistance, and thermal conductivity), (2) reliability (i.e., environmental durability, and damage tolerance) and (3) processing (i.e., capability for varying sizes and shapes, and cost effective fabrication). The presentation further discusses, and illustrates with fiber and CMC data the key fiber properties and processes which strongly affect each CMC area of competition. The presentation further discusses the current knowledge of the important factors which control the key fiber properties. A design guidelines for the optimum fiber characteristics is developed, and the currently available fibers are compared against those guidelines.

  18. Synthesis of TiN/AlON composite ceramics

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The synthesis process of TiN/AlON composite ceramics was studied, the thermodynamics, mechanical properties and microstructures of TiN/AlON have also been investigated. The TiN/AlON composite ceramics has been synthesized by both hot-pressing and pressureless sintering. The characterizations of the material synthesized were analyzed with XRD (X-ray diffraction) and TEM (transmission electronic microscope). The density and toughness strength of TiN/AlON are 3.57 g/cm3 and 4.74 MPa@ m1/2, respectively. The bending strength was measured at both room temperature and high temperatures and the results are 399 MPa (room temperature), 406 MPa (1 073 K), 417 MPa (1 273 K) and 323 MPa (1 573 K). Pattern Recognition (PR) and Artificial Neural Network (ANN) were used to optimize the parameters and to predict the expected values. A proper parameter for pressureless sintering of TiN/AlON has been obtained and testified, the parameters are temperature (1978 K), AlN / (AlN + Al2O3) ratio (0.22), MgO (4.7%) and TiO2 (7.2%).

  19. Hoop Tensile Properties of Ceramic Matrix Composite Cylinders

    Science.gov (United States)

    Verrilli, Michael J.; DiCarlo, James A.; Yun, HeeMan; Barnett, Terry

    2004-01-01

    Tensile stress-strain properties in the hoop direction were obtained for 100-mm diameter SiC/SiC ceramic matrix composite cylinders using ring specimens machined form the cylinder ends. The cylinders were fabricated from 2D balanced SiC fabric with several material variants, including wall thickness (6,8, and 12 plies), SiC fiber type (Sylramic, Sylramic-iBN, Hi-Nicalon, and Hi-Nicalon S), fiber sizing type, and matrix type (full CVI SiC, and partial CVI SiC plus slurry cast + melt-infiltrated SiC-Si). Fiber ply splices existed in all the hoops. Tensile hoop measurements are made at room temperature and 1200 C using hydrostatic ring test facilities. The failure mode of the hoops, determined through microstructural examination, is presented. The hoop properties are compared with in-plane data measured on flat panels using same material variants, but containing no splices.

  20. Mechanical properties of ceramic composite tubes

    Energy Technology Data Exchange (ETDEWEB)

    Curtin, W.A.; Oleksuk, L.L.; Reifsnider, K.L. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States); Stinton, D.P. [Oak Ridge National Lab., TN (United States)

    1995-08-01

    Results of axial tension tests on SiC/SiC tubular ceramic composite components fabricated by a forced-M technique are presented. Axial elastic modulus measurements on a number of tubes show that the Young`s modulus varies along the length of the tube, with occasional very stiff or very soft regions. Tests to failure on a few tubes show the initiation of non-linear stress-strain behavior to be in the range of 3-9 ksi, followed by extensive non-linear deformation up to failure. For one tube, the failure stress obtained was 20.1 ksi, but the strains to failure at various axial locations varies from 0.19%to 0.24%. The correlation between modulus and proportional limit is considered within the ACK matrix cracking theory and within a model in which matrix cracking between fiber tows occurs, both modified to account for matrix porosity. The crack size required to cause stress concentrations large enough to cause failure at the observed strength is considered. Predictions for both matrix cracking and strength suggest that the current generation of tubes are controlled by microstructural defects.

  1. Comparison of the microstructure and composition of aboriginal ceramics, from indigenous site Caninhas, with the obtained ones in the region

    International Nuclear Information System (INIS)

    The archaeological site of Caninhas is made of funeral and combustion structures and various objects of aboriginal daily use. These parts and fragments were safe and inventoried, constituting approximately 4000 units. The objective of this project was to analyze the microstructure and composition of archaeological ceramics, and ceramics made of argil current of the zone. The crystalline phases were identified by X-Rays Diffraction (XRD), elementary composition was obtained by X-Rays Fluorescence (XRF) and Energy Dispersive Spectrometry (EDS), and the microstructure was evaluated by Scanning Electron Microscope (SEM). Composition and microstructure of archaeological ceramics are different of current ceramics, indicating the effect of lixiviation in function of the time and the microstructural evolution due different ceramic processing. These results are valuable for the archaeological area studies, mainly for the cultural denoting which represents. The relation between some studies is basic to add knowledge: use of the ceramic materials engineering for archaeology application. (author)

  2. Comparison and simulation of salt-ceramic composites for use in high temperature concentrated solar power

    Science.gov (United States)

    Fossile, Lauren Michelle

    Due to the inherently intermittent nature of solar energy caused by cloud cover among other sources, thermal storage systems are needed to make solar energy more consistent. This same technology could be used to prolong the daily number of useful hours of solar energy power plants. Salt-ceramic materials are a relatively new prospect for heat storage, but have been researched mostly with magnesium oxide and several different carbonate salts. Salt ceramics are a phase change material where the salt changes phase inside the ceramic structure allowing for the system to use the sensible heat of both materials and the latent heat of the salt to store thermal energy. Capillary forces within the ceramic structure hold in the salt when the salt melts. The focus here is on the possibility of creating a low-cost salt-ceramic storage material for high temperature solar energy applications. A theoretical analysis of the resulting materials is performed. While most of the existing salt ceramics have been made from magnesium oxide, aluminum oxide is more readily available from various companies in the area. Magnesium oxide is often considered a custom ceramic, so it is more expensive. A cost and material property comparison has been completed between these two materials to determine which is better suited for solar storage. Many of the existing salt-ceramics use carbonate salts, but nitrate salts are commonly used in graphite/salt composites. Therefore, a cost and theoretical performance comparison is between these materials also. For comparisons' sake, zirconia and graphite have also been analyzed as the filler in the composite. Each combination of salt and ceramic or graphite has been analyzed. In order to make the use of salt-ceramics more cost-effective and available to Nevada's energy providers, research has been done into which ceramics have high availability in Nevada, low cost, and the best material properties for this application. The thermal properties and cost of

  3. Elastic properties of various ceramic materials

    International Nuclear Information System (INIS)

    The Young's modulus and the Poisson's ratio of various ceramics have been investigated at room temperature and compared with data from the literature. The ceramic materials investigated are Al2O3, Al2O3-ZrO2, MgAl2O4, LiAlO2, Li2SiO3, Li4SiO4, UO2, AlN, SiC, B4C, TiC, and TiB2. The dependence of the elastic moduli on porosity and temperature have been reviewed. Measurements were also performed on samples of Al2O3, AlN, and SiC, which had been irradiated to maximum neutron fluences of 1.6.1026 n/m2 (E>0.1 MeV) at different temperatures. The Young's modulus is nearly unaffected at fluences up to about 4.1024 n/m2. However, it decreases with increasing neutron fluence and seems to reach a saturation value depending upon the irradiation temperature. The reduction of the Young's modulus is lowest in SiC. (orig.)

  4. Bioactivity of thermal plasma synthesized bovine hydroxyapatite/glass ceramic composites

    International Nuclear Information System (INIS)

    Bone injuries and failures often require the inception of implant biomaterials. Research in this area is receiving increasing attention worldwide. A variety of artificial bone materials, such as metals, polymeric materials, composites and ceramics, are being explored to replace diseased bones. Calcium phosphate ceramics are currently used as biomaterials for many applications in both dentistry and orthopedics. Bioactive silicate-based glasses show a higher bioactive behaviour than calcium phosphate materials. It is very interesting to study the mixtures of HA and silicate-based glasses. In the present study; natural bovine hydroxyapatite / SiO2-CaO-MgO glass composites were produced using the Transferred arc plasma (TAP) melting method. TAP melting route is a brisk process of preparation of glass-ceramics in which the raw materials are melted in the plasma and crystallization of the melt occurs while cooling down at a much faster rate in relatively short processing times compared to the conventional methods of manufacture of glass ceramics/composites. It is well known that; one essential step to the understanding of the biological events occurring at the bone tissue/material interface is the biological investigation by in vitro tests. Cell lines are commonly used for biocompatibility tests, and are very efficient because of their reproducibility and culture facility. In this study, we report the results of a study on the response of primary cultures of human fibroblast cells to TAP melted bioactive glass ceramics.

  5. Calculation of the bio-ceramic material parameters

    Czech Academy of Sciences Publication Activity Database

    Fuis, Vladimír; Janíček, Přemysl

    Berlin : Springer, 2014, s. 855-861. ISBN 978-3-319-02293-2. [Mechatronics 2013 /10./. Brno (CZ), 07.10.2013-09.10.2013] R&D Projects: GA ČR GA13-34632S Institutional support: RVO:61388998 Keywords : ceramics * material parameters * weibull Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  6. A novel biomimetic approach to the design of high-performance ceramic/metal composites

    Energy Technology Data Exchange (ETDEWEB)

    Launey, Maximilien E.; Munch, Etienne; Alsem, Daan Hein; Saiz, Eduardo; Tomsia, Antoni P.; Ritchie, Robert O.

    2009-08-01

    The prospect of extending natural biological design to develop new synthetic ceramic-metal composite materials is examined. Using ice-templating of ceramic suspensions and subsequent metal infiltration, we demonstrate that the concept of ordered hierarchical design can be applied to create fine-scale laminated ceramic-metal (bulk) composites that are inexpensive, lightweight and display exceptional damage-tolerance properties. Specifically, Al{sub 2}O{sub 3}/Al-Si laminates with ceramic contents up to approximately 40 vol% and with lamellae thicknesses down to 10 {micro}m were processed and characterized. These structures achieve an excellent fracture toughness of 40 MPa{radical}m at a tensile strength of approximately 300 MPa. Salient toughening mechanisms are described together with further toughening strategies.

  7. Structure recognition from high resolution images of ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Ushizima, Daniela; Perciano, Talita; Krishnan, Harinarayan; Loring, Burlen; Bale, Hrishikesh; Parkinson, Dilworth; Sethian, James

    2015-01-05

    Fibers provide exceptional strength-to-weight ratio capabilities when woven into ceramic composites, transforming them into materials with exceptional resistance to high temperature, and high strength combined with improved fracture toughness. Microcracks are inevitable when the material is under strain, which can be imaged using synchrotron X-ray computed micro-tomography (mu-CT) for assessment of material mechanical toughness variation. An important part of this analysis is to recognize fibrillar features. This paper presents algorithms for detecting and quantifying composite cracks and fiber breaks from high-resolution image stacks. First, we propose recognition algorithms to identify the different structures of the composite, including matrix cracks and fibers breaks. Second, we introduce our package F3D for fast filtering of large 3D imagery, implemented in OpenCL to take advantage of graphic cards. Results show that our algorithms automatically identify micro-damage and that the GPU-based implementation introduced here takes minutes, being 17x faster than similar tools on a typical image file.

  8. Modern composite materials manufactured by pressure infiltration method

    OpenAIRE

    L.A. Dobrzański; M. Kremzer; M. Drak

    2008-01-01

    Purpose: The purpose of this paper is to present the technique of manufacturing the composite materials based on porous ceramic preforms infiltrated by liquid aluminium alloy and examination of the structure and corrosion resistance of those materials.Design/methodology/approach: The material for investigations was manufactured by pressure infiltration method of ceramic porous preforms. The eutectic aluminium alloy EN AC – AlSi12 was use as a matrix while as reinforcement were used...

  9. Ceramic materials for fission and fusion nuclear reactors

    International Nuclear Information System (INIS)

    A general survey on the ceramics for nuclear applications is presented. For the fission nuclear reactor, the ceramics materials are almost totally used as fuel e.g. (U,Pu)O2; other types of ceramics, e.g. Uranium-Plutonium carbide and nitride, have been investigated as potential nuclear fuels. The (U,Pu)N compound is to be the fuel for the space nuclear power reactor in the U.S.A. For the fusion nuclear reactor, the ceramics should be the fundamental materials for many components: first wall, breeder, RF heating systems, insulant and shielding parts, etc. In recent years many countries are involved on the research and development of ceramic compounds with the principal purpose of being used in the fusion powerplant (year 2010-2020 ?). An effort has been even made to verify if it is possible to use more ceramic components in the fission nuclear plant (probably differntly disigned) to improve the safety level

  10. GdAlO3-ZrO2: A ductile ceramic composite

    International Nuclear Information System (INIS)

    A ceramic with a high fracture toughness KIC that is close to the respective values of cast iron and Mg alloys has been fabricated by microwave sintering of GdAlO3 and ZrO2 into composite materials of different molar fractions; for the 80/20 composite KIC reaches the remarkable value of 17.5 Mpa m1/2. Such composites may become extremely valuable for structural applications in advanced technologies. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  11. Marginal Adaptation of Indirect Composite, Glass-Ceramic Inlays and Direct Composite: An In Vitro Evaluation

    Directory of Open Access Journals (Sweden)

    F. Mahboub

    2010-06-01

    Full Text Available Objective: This experimental in vitro study compared marginal adaptation of indirect composite, glass-ceramic inlays and direct composite.Materials and Methods: Seventy-five recently extracted human molars were randomly divided into three groups (n=25 and mesio-occluso-distal cavities with the same dimensions were prepared in the teeth. Indirect composite and glass-ceramic inlays were fabricatedfollowing manufacturer's instructions and the marginal gap was measured by a stereomicroscope at magnification 40× before cementation. After cementation of inlays and restoring the third group by direct composite, all the specimens were thermocycled and the marginal gaps were measured exactly as previously described. Repeated measure ANOVA and post-hoc Tukey test were used for pairwise comparison of occlusal, proximal, and gingival marginal gaps in each group. One-way ANOVA and post-hoc Tukey test wereused for comparison of mean marginal gap in the three groups and for comparison of marginal gap before and after cementation in inlays, paired T-test was used.Results: The marginal gap of direct composite (19.96 μm was significantly lower than that of indirect composite inlay (48.47 μm, which in itself was significantly lower than that of glass-ceramic inlay (60.96 μm. In all the restorations, marginal gap in the gingival margin was significantly higher than occlusal and proximal margins. The marginal gap of inlays did not change after cementation and thermocycling.Conclusion: This study indicated that the marginal gaps of the evaluated restorations are less than 100 μm, which is clinically acceptable.

  12. Continuous fiber ceramic composites for energy related applications. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-07

    The US Department of Energy has established the Continuous Fiber Ceramic Composites (CFCC) program to develop technology for the manufacture of CFCC`s for use in industrial applications where a reduction in energy usage or emissions could be realized. As part of this program, the Dow Chemical Company explored the manufacture of a fiber reinforced/self reinforced silicon nitride for use in industrial chemical processing. In Dow`s program, CFCC manufacturing technology was developed around traditional, cost effective, tape casting routes. Formulations were developed and coupled with unique processing procedures which enabled the manufacture of tubular green laminates of the dimension needed for the application. An evaluation of the effect of various fibers and fiber coatings on the properties of a fiber reinforced composites was also conducted. Results indicated that fiber coatings could provide composites exhibiting non-catastrophic failure and substantially improved toughness. However, an evaluation of these materials in industrial process environments showed that the material system chosen by Dow did not provide the required performance improvements to make replacement of current metallic components with CFCC components economically viable.

  13. Analysis of crack initiation in the vicinity of an interface in brittle materials. Applications to ceramic matrix composites and nuclear fuels; Analyse de la fissuration au voisinage d'une interface dans les materiaux fragiles. Applications aux composites a matrice ceramique et aux combustibles nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Poitou, B

    2007-11-15

    In this study, criterions are proposed to describe crack initiation in the vicinity of an interface in brittle bi-materials. The purpose is to provide a guide for the elaboration of ceramic multi-layer structures being able to develop damage tolerance by promoting crack deflection along interfaces. Several cracking mechanisms are analyzed, like the competition between the deflection of a primary crack along the interface or its penetration in the second layer. This work is first completed in a general case and is then used to describe the crack deviation at the interface in ceramic matrix composites and nuclear fuels. In this last part, experimental tests are carried out to determine the material fracture properties needed to the deflection criteria. An optimization of the fuel coating can be proposed in order to increase its toughness. (author)

  14. Superconducting composites materials

    International Nuclear Information System (INIS)

    The new superconductor materials with a high critical current own a large importance as well in the electronic components or in the electrotechnical devices fields. The deposit of such materials with the thick films technology is to be more and more developed in the years to come. Therefore, we tried to realize such thick films screen printed on alumina, and composed mainly of the YBa2Cu3O7-δ material. We first realized a composite material glass/YBa2Cu3O7-δ, by analogy with the classical screen-printed inks where the glass ensures the bonding with the substrate. We thus realized different materials by using some different classes of glass. These materials owned a superconducting transition close to the one of the pure YBa2Cu3O7-δ material. We made a slurry with the most significant composite materials and binders, and screen-printed them on an alumina substrate preliminary or not coated with a diffusion barrier layer. After firing, we studied the thick films adhesion, the alumina/glass/composite material interfaces, and their superconducting properties. 8 refs.; 14 figs.; 9 tabs

  15. Porous ceramic - metal composites obtained by infiltration methods

    OpenAIRE

    A. Boczkowska; Chabera, P.; Dolata, A. J.; M. Dyzia; Oziębło, A.

    2013-01-01

    A pressure-vacuum infiltration (T = 720 ºC, p = 15 MPa, t = 15 min) and gas-pressure infiltration (GPI) in an autoclave (T = 700ºC, p=4 MPa, t=5 min) were applied for infiltration of porous Al2O3 ceramics by cast aluminum alloy. Effect of the method of the infiltration on the microstructure and mechanical properties of ceramic-metal composites, was studied. Ceramic preforms were formed by method of copying the cellular structure of the polymer matrix. The results of the X-ray tomography prove...

  16. Silicone Resin Applications for Ceramic Precursors and Composites

    OpenAIRE

    Masaki Narisawa

    2010-01-01

    This article reviews the applications of silicone resins as ceramic precursors. The historical background of silicone synthesis chemistry is introduced to explain the production costs and supply availability of various silicones. Thermal degradation processes of silicones are classified in terms of the main chain structure and cyclic oligomer expulsion process, which determine the resulting ceramic yield and the chemical composition. The high temperature decomposition of Si-O-C beyond 1,400 °...

  17. Ceramic compositional analysis in archaeological perspective

    Energy Technology Data Exchange (ETDEWEB)

    Bishop, R.L.; Rands, R.L.; Holley, G.R.

    1980-01-01

    The primary significance of compositional analysis in archaeology lies on the spatial dimension, in distinguishing products made by locally or regionally-based groups. If compositional analysis is to be carried beyond the descriptive recording of similarities and differences, the resource procurement zone (and its geographical relationship to inferred places of manufacture) is a basic operational concept (Rands and Bishop 1980). A zonal concept is clearly indicated in the case of pottery, which frequently is derived from raw materials, clay and temper, that do not necessarily coincide in their place of procurement. Moreover, depending on geomorphological and geochemical variables, these materials may show considerable homogeneity over a fairly extended area. On the other hand, unless there is strong, selective patterning in the exploitation of resources, great heterogeneity within a restricted region may result in fragmented procurement zones that are difficult to equate with the products of specific manufacturing centers. Under favorable circumstances, however, it appears that methods of compositional analysis are approaching the point at which microzones of limited geographical extent can be recognized and assigned heuristically useful boundaries.

  18. The effect of filler on the temperature coefficient of the relative permittivity of PTFE/ceramic composites

    Science.gov (United States)

    Rajesh, S.; Murali, K. P.; Jantunen, H.; Ratheesh, R.

    2011-11-01

    High permittivity and low-loss ceramic fillers have been prepared by means of the solid state ceramic route. Ceramic-filled composites were prepared by the Sigma Mixing, Extrusion, Calendering, which was followed by the Hot pressing (SMECH) process. The microwave dielectric properties of the composites were studied using X-band waveguide cavity perturbation technique. The temperature coefficient of the relative permittivity of the composites was investigated in the 0-100 °C temperature range using a hot and cold chamber coupled with an impedance analyzer. The temperature coefficient of the relative permittivity of the composites showed strong dependence on the temperature coefficient of the relative permittivity of the filler material. In the present study, a high-permittivity polymer/ceramic composite, having τεr ∼63 ppm/K, has been realized. This composite is suitable for outdoor wireless applications.

  19. Composite materials for fusion applications

    International Nuclear Information System (INIS)

    Ceramic matrix composites, CMCs, are being considered for advanced first-wall and blanket structural applications because of their high-temperature properties, low neutron activation, low density and low coefficient of expansion coupled with good thermal conductivity and corrosion behavior. This paper presents a review and analysis of the hermetic, thermal conductivity, corrosion, crack growth and radiation damage properties of CMCs. It was concluded that the leak rates of a gaseous coolant into the plasma chamber or tritium out of the blanket could exceed design criteria if matrix microcracking causes existing porosity to become interconnected. Thermal conductivities of unirradiated SiC/SiC and C/SiC materials are about 1/2 to 2/3 that of Type 316 SS whereas the thermal conductivity for C/C composites is seven times larger. The thermal stress figure-of-merit value for CMCs exceeds that of Type 316 SS for a single thermal cycle. SiC/SiC composites are very resistant to corrosion and are expected to be compatible with He or Li coolants if the O2 concentrations are maintained at the appropriate levels. CMCs exhibit subcritical crack growth at elevated temperatures and the crack velocity is a function of the corrosion conditions. The radiation stability of CMCs will depend on the stability of the fiber, microcracking of the matrix, and the effects of gaseous transmutation products on properties. 23 refs., 14 figs., 1 tab

  20. Characterization of silicon-silicon carbide ceramic derived from carbon-carbon silicon carbide composites

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Vijay K. [Indian Institute of Technology, Varanasi (India). Dept. of Mechanical Engineering; Krenkel, Walter [Univ. of Bayreuth (Germany). Dept. of Ceramic Materials Engineering

    2013-04-15

    The main objective of the present work is to process porous silicon - silicon carbide (Si - SiC) ceramic by the oxidation of carboncarbon silicon carbide (C/C - SiC) composites. Phase studies are performed on the oxidized porous composite to examine the changes due to the high temperature oxidation. Further, various characterization techniques are performed on Si- SiC ceramics in order to study the material's microstructure. The effects of various parameters such as fiber alignment (twill weave and short/chopped fiber) and phenolic resin type (resol and novolak) are characterized.

  1. Thixoforming of SiC ceramic matrix composites in pseudo-semi-solid state

    Institute of Scientific and Technical Information of China (English)

    CHENG Yuan-sheng; LUO Shou-jing; DU Zhi-ming

    2005-01-01

    A new forming process, ceramic matrix composites thixoforming in pseudo-semi-solid state, was proposed based on powder metallurgy technology combined with the semi-solid metal forming process. The satellite angle-frames were prepared by this technology with Alp and SiCp materials mixed with different volume fractions. It is proved that it is feasible for the forming of the ceramic matrix composites by this technology through metallographic analyses and tensile tests. The results also show that the microstructures of samples are homogeneous and they have high hardness and certain plasticity.

  2. Elastic properties of silica-silica continuous fibre-reinforced, ceramic matrix composites

    International Nuclear Information System (INIS)

    Ambient and elevated temperature elastic properties of silica-silica ceramic fibre-reinforced, ceramic-matrix composites (silica-silica CFCCs), obtained using resonance beam technique, have been reported and discussed. The composite exhibits in-plane isotropy and through-thickness anisotropy in the elastic properties at ambient temperatures and increasing elastic moduli with increasing test temperature. The latter results are attributable to the change in the nature of atomic bonding of the silica material up to about 1173 K and further increase in moduli with temperature is due to the combined effects of devitrification and densification due to sintering

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

    Science.gov (United States)

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

    2016-01-01

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

  4. Hot corrosion of ceramic engine materials

    Science.gov (United States)

    Fox, Dennis S.; Jacobson, Nathan S.; Smialek, James L.

    1988-01-01

    A number of commercially available SiC and Si3N4 materials were exposed to 1000 C in a high velocity, pressurized burner rig as a simulation of a turbine engine environment. Sodium impurities added to the burner flame resulted in molten Na2SO4 deposition, attack of the SiC and Si4N4 and formation of substantial Na2O-x(SiO2) corrosion product. Room temperature strength of the materials decreased. This was a result of the formation of corrosion pits in SiC, and grain boundary dissolution and pitting in Si3N4. Corrosion regimes for such Si-based ceramics have been predicted using thermodynamics and verified in rig tests of SiO2 coupons. Protective mullite coatings are being investigated as a solution to the corrosion problem for SiC and Si3N4. Limited corrosion occurred to cordierite (Mg2Al4Si5O18) but some cracking of the substrate occurred.

  5. Ceramic core–shell composites with modified mechanical properties prepared by thermoplastic co-extrusion

    Czech Academy of Sciences Publication Activity Database

    Kaštyl, J.; Chlup, Zdeněk; Clemens, F.; Trunec, M.

    2015-01-01

    Roč. 35, č. 10 (2015), s. 2873-2881. ISSN 0955-2219 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Alumina * Zirconia toughened alumina * Co-extrusion * Composite * Mechanical properties1 Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.947, year: 2014

  6. Thermal Conductivity of Al2O3–ZrO2 Composite Ceramics

    Czech Academy of Sciences Publication Activity Database

    Hostaša, J.; Pabst, W.; Matějíček, Jiří

    2011-01-01

    Roč. 94, č. 12 (2011), s. 4404-4409. ISSN 1551-2916 Institutional research plan: CEZ:AV0Z20430508 Keywords : alumina * zirconia * composites * thermal conductivity * model Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  7. Glass matrix composite material prepared with waste foundry sand

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhao-shu; XIA Ju-pei; ZHU Xiao-qin; LIU Fan; HE Mao-yun

    2006-01-01

    The technology of glass matrix of the composite material manufactured through a sintering process and using waste foundry sand and waste glass as the main raw materials was studied. The effects of technological factors on the performance of this material were studied. The results showed that this composite material is formed with glass as matrix, core particulate as strengthening material, it has the performance of glass and ceramics, and could be used to substitute for stone.

  8. Modified PZT ceramics as a material that can be used in micromechatronics

    Science.gov (United States)

    Zachariasz, Radosław; Bochenek, Dariusz

    2015-11-01

    Results on investigations of the PZT type ceramics with the following chemical composition: Pb0.94Sr0.06(Zr0.50 Ti0.50)0.99 Cr0.01O3 (PSZTC) which belongs to a group of multicomponent ceramic materials obtained on basis of the PZT type solid solution, are presented in this work. Ceramics PSZTC was obtained by a free sintering method under the following conditions: Tsint = 1250 °C and tsint = 2 h. Ceramic compacts of specimens for the sintering process were made from the ceramic mass consisting of a mixture of the synthesized PSZTC powder and 3% polyvinyl alcohol while wet. The PSZTC ceramic specimens were subjected to poling by two methods: low temperature and high temperature. On the basis of the examinations made it has been found that the ceramics obtained belongs to ferroelectric-hard materials and that is why it may be used to build resonators, filters and ultrasonic transducers. Contribution to the Topical Issue "Materials for Dielectric Applications" edited by Maciej Jaroszewski and Sabu Thomas.

  9. Industrial ceramics - Properties, forming and applications

    International Nuclear Information System (INIS)

    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

  10. Advanced Measurements of Silicon Carbide Ceramic Matrix Composites

    Energy Technology Data Exchange (ETDEWEB)

    Farhad Farzbod; Stephen J. Reese; Zilong Hua; Marat Khafizov; David H. Hurley

    2012-08-01

    Silicon carbide (SiC) is being considered as a fuel cladding material for accident tolerant fuel under the Light Water Reactor Sustainability (LWRS) Program sponsored by the Nuclear Energy Division of the Department of Energy. Silicon carbide has many potential advantages over traditional zirconium based cladding systems. These include high melting point, low susceptibility to corrosion, and low degradation of mechanical properties under neutron irradiation. In addition, ceramic matrix composites (CMCs) made from SiC have high mechanical toughness enabling these materials to withstand thermal and mechanical shock loading. However, many of the fundamental mechanical and thermal properties of SiC CMCs depend strongly on the fabrication process. As a result, extrapolating current materials science databases for these materials to nuclear applications is not possible. The “Advanced Measurements” work package under the LWRS fuels pathway is tasked with the development of measurement techniques that can characterize fundamental thermal and mechanical properties of SiC CMCs. An emphasis is being placed on development of characterization tools that can used for examination of fresh as well as irradiated samples. The work discuss in this report can be divided into two broad categories. The first involves the development of laser ultrasonic techniques to measure the elastic and yield properties and the second involves the development of laser-based techniques to measurement thermal transport properties. Emphasis has been placed on understanding the anisotropic and heterogeneous nature of SiC CMCs in regards to thermal and mechanical properties. The material properties characterized within this work package will be used as validation of advanced materials physics models of SiC CMCs developed under the LWRS fuels pathway. In addition, it is envisioned that similar measurement techniques can be used to provide process control and quality assurance as well as measurement of

  11. Effect of silica sol on the properties of alumina-based ceramic core composites

    International Nuclear Information System (INIS)

    A series of alumina-based ceramic cores sintered at 1300 deg. C, 1400 deg. C, and 1500 deg. C for 5 h were prepared, and the phases and microstructures were characterized by X-ray diffraction and scanning electron microscopy. The effect of colloidal silica sols on the properties of ceramic core was discussed. The properties of these materials were determined. The microstructure of the core formed on the substantially un-reacted coarse Al2O3 particles was predominantly a polycrystalline composition consisting essentially of in situ synthesized 3Al2O3.2SiO2. The colloidal silica sol contents do not have an appreciable effect on the densification and shrinkage of alumina ceramic core. The ceramic cores of 5 wt% colloidal silica sol contents sintered at 1500 deg. C for 5 h showed the smallest creep deformation in the present research.

  12. Research study for gel precursors as glass and ceramic starting materials for space processing applications research

    Science.gov (United States)

    Downs, R. L.; Miller, W. J.

    1983-01-01

    The development of techniques for the preparation of glass and ceramic starting materials that will result in homogeneous glasses or ceramic products when melted and cooled in a containerless environment is described. Metal-organic starting materials were used to make compounds or mixtures which were then decomposed by hydrolysis reactions to the corresponding oxides. The sodium tungstate system was chosen as a model for a glass with a relatively low melting temperature. The alkoxide tungstates also have interesting optical properties. For all the compositions studied, comparison samples were prepared from inorganic starting materials and submitted to the same analyses.

  13. Fracture Behavior of Alumina-based Prismatic Ceramic Composites

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The fracture toughness and fracture work of Al2O3/SiC prismatic ceramic composites was evaluated in this paper, which showed the fracture energy was improved greatly. Based on the observation for crack propagation and fracture morphology, the fracture behavior of the prismatic composites was analyzed. In the bending test, the composites displayed a non-catastrophic behavior and a graceful failure with reasonable load-carrying capability.

  14. Monitoring Damage Accumulation in Ceramic Matrix Composites Using Electrical Resistivity

    Science.gov (United States)

    Smith, Craig E.; Morscher, Gregory N.; Xia, Zhenhai H.

    2008-01-01

    The electric resistance of woven SiC fiber reinforced SiC matrix composites were measured under tensile loading conditions. The results show that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance. Such self-sensing capability provides the possibility of on-board/in-situ damage detection and accurate life prediction for high-temperature ceramic matrix composites. Woven silicon carbide fiber-reinforced silicon carbide (SiC/SiC) ceramic matrix composites (CMC) possess unique properties such as high thermal conductivity, excellent creep resistance, improved toughness, and good environmental stability (oxidation resistance), making them particularly suitable for hot structure applications. In specific, CMCs could be applied to hot section components of gas turbines [1], aerojet engines [2], thermal protection systems [3], and hot control surfaces [4]. The benefits of implementing these materials include reduced cooling air requirements, lower weight, simpler component design, longer service life, and higher thrust [5]. It has been identified in NASA High Speed Research (HSR) program that the SiC/SiC CMC has the most promise for high temperature, high oxidation applications [6]. One of the critical issues in the successful application of CMCs is on-board or insitu assessment of the damage state and an accurate prediction of the remaining service life of a particular component. This is of great concern, since most CMC components envisioned for aerospace applications will be exposed to harsh environments and play a key role in the vehicle s safety. On-line health monitoring can enable prediction of remaining life; thus resulting in improved safety and reliability of structural components. Monitoring can also allow for appropriate corrections to be made in real time, therefore leading to the prevention of catastrophic failures. Most conventional nondestructive

  15. Alumina matrix ceramic-nickel composites formed by centrifugal slip casting

    Directory of Open Access Journals (Sweden)

    Justyna Zygmuntowicz

    2015-12-01

    Full Text Available The paper is focused on the possibility of fabricating the alumina matrix ceramic-nickel composites with gradient concentration of metal particles. Centrifugal slip casting method was chosen for the composite fabrication. This method allows fabrication of the graded distribution of nickel particles in the hollow cylinder composites. The horizontal rotation axis was applied. The samples were characterized by XRD, SEM and quantitative description of the microstructure. The macroscopic as well as SEM observations of the prepared composites confirmed the gradient concentration of Ni particles in the composite materials. The application of the centrifugal slip casting method allows for the graded distribution of metal particles in the samples.

  16. Preliminary study of chemical compositional data from Amazon ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Toyota, Rosimeiri G.; Munita, Casimiro S.; Luz, Fabio A. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)]. E-mail: rosimeiritoy@yahoo.com.br; Neves, Eduardo G. [Museu de Arqueologia e Etnolgia, Sao Paulo, SP (Brazil)]. E-mail: egneves@usp.br; Oliveira, Paulo M.S. [Sao Paulo Univ., SP (Brazil). Escola Politecnica. Inst. de Matematica e Estatistica]. E-mail: poliver@usp.br

    2005-07-01

    Eighty seven ceramic samples from Acutuba, Lago Grande and Osvaldo archaeological sites located in the confluence of the rivers Negro and Solimoes were submitted to chemical analysis using instrumental neutron activation analysis to determine As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Rb, Na, Nd, Sb, Sc, Sm, Ta, Tb, Th, Yb, Zn, and U. The database were studied using the Mahalanobis distance, and discriminant analysis. The results showed that the ceramics of each site differ from each other in chemical composition and that they form three different groups. Chemical classification of the ceramics suggests that vessels were made locally, as only ceramics from the same area show homogeneity of data. (author)

  17. Preliminary study of chemical compositional data from Amazon ceramics

    International Nuclear Information System (INIS)

    Eighty seven ceramic samples from Acutuba, Lago Grande and Osvaldo archaeological sites located in the confluence of the rivers Negro and Solimoes were submitted to chemical analysis using instrumental neutron activation analysis to determine As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Rb, Na, Nd, Sb, Sc, Sm, Ta, Tb, Th, Yb, Zn, and U. The database were studied using the Mahalanobis distance, and discriminant analysis. The results showed that the ceramics of each site differ from each other in chemical composition and that they form three different groups. Chemical classification of the ceramics suggests that vessels were made locally, as only ceramics from the same area show homogeneity of data. (author)

  18. 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. PMID:27524006

  19. High efficiency tantalum-based ceramic composite structures

    Science.gov (United States)

    Stewart, David A. (Inventor); Leiser, Daniel B. (Inventor); DiFiore, Robert R. (Inventor); Katvala, Victor W. (Inventor)

    2010-01-01

    Tantalum-based ceramics are suitable for use in thermal protection systems. These composite structures have high efficiency surfaces (low catalytic efficiency and high emittance), thereby reducing heat flux to a spacecraft during planetary re-entry. These ceramics contain tantalum disilicide, molybdenum disilicide and borosilicate glass. The components are milled, along with a processing aid, then applied to a surface of a porous substrate, such as a fibrous silica or carbon substrate. Following application, the coating is then sintered on the substrate. The composite structure is substantially impervious to hot gas penetration and capable of surviving high heat fluxes at temperatures approaching 3000.degree. F. and above.

  20. Exotic development of ceramic tritium breeding materials

    International Nuclear Information System (INIS)

    In the near future fusion reactors will be based on the tritium-deuterium plasma reaction. As such the production of tritium, a non-natural element, becomes of crucial importance in fusion technology. An experimental programme, EXOTIC, is in progress since 1983 in which the laboratories of SNL-Springfields, ECN-Petten, JRC-Petten and SCK-CEN Mol work in close collaboration within the framework of the manufacture, characterization and irradiation of ceramic lithium compounds. This programme must result in the understanding of the tritium release processes and the effect of material characteristics on this release. Up to now three irradiation experiments in the High Flux Reactor-Petten were scheduled (EXOTIC I, II and III). The Annual Progress Report 1985 summarizes information on these experiments during the period of 1985. The reader is also referred to the previous Annual Progress Report 1984. During the EXOTIC I experiment lithium silicate pellets and lithium aluminate pellets were irradiated. The resulting tritium release data are still to be interpreted in full detail. Some preliminary observations are presented in this Report. In the EXOTIC II experiment lithium oxide, lithium aluminate and lithium silicate pellets were used. In the EXOTIC III experiment lithium oxide, lithium zirconate and lithium silicate pellets were used. (Author)

  1. High-temperature behaviour of ceramic materials

    International Nuclear Information System (INIS)

    This volume contains 7 papers presented at the DFG Colloquium in Munich on 16 September 1991. The subjects of the individual papers are: 1) High-Temperature Failure of Gas-Phase Containing Aluminum Oxide; 2) High-Temperature Behavior of Aluminum Oxides of Different Compositions; 3) Effect of Processing Parameters on Mechanical Properties of Platelet-Reinforced Mullite Composites; 4) Tensile Creep Investigations On Silicon Nitride Materials Using a Newly Developed Tensile Creep Facility; 5) Influence of Material and Process Technological Parameters On the High-Temperature Characteristics of Gas-Pressure Sintered Silicon Nitride; 6) The Influence of Age Hardening On the Mechanical Behavior and Microstructure of Y-doped Si3N4; 7) Application of a Crack Growth Model to Silicon Nitride. (orig./MM)

  2. Mechanochemically synthesized kalsilite based bioactive glass-ceramic composite for dental vaneering

    Science.gov (United States)

    Kumar, Pattem Hemanth; Singh, Vinay Kumar; Kumar, Pradeep

    2015-08-01

    Kalsilite glass-ceramic composites have been prepared by a mechanochemical synthesis process for dental veneering application. The aim of the present study is to prepare bioactive kalsilite composite material for application in tissue attachment and sealing of the marginal gap between fixed prosthesis and tooth. Mechanochemical synthesis is used for the preparation of microfine kalsilite glass-ceramic. Low temperature frit and bioglass have been prepared using the traditional quench method. Thermal, microstructural and bioactive properties of the composite material have been examined. The feasibility of the kalsilite to be coated on the base commercial opaque as well as the bioactive behavior of the coated specimen has been confirmed. This study indicates that the prepared kalsilite-based composites show similar structural, morphological and bioactive behavior to that of commercial VITA VMK95 Dentin 1M2.

  3. Micromechanics of Composite Materials

    CERN Document Server

    Dvorak, George

    2013-01-01

    This book presents a broad exposition of analytical and numerical methods for modeling composite materials, laminates, polycrystals and other heterogeneous solids, with emphasis on connections between material properties and responses on several length scales, ranging from the nano and microscales to the macroscale. Many new results and methods developed by the author are incorporated into a rich fabric of the subject, which has been explored by several researchers over the last 40 years.   The first  part of the book reviews anisotropic elasticity theory, and then it describes the frequently used procedures and theorems for bounding and estimating overall properties, local fields and energy changes in elastic inhomogeneities, heterogeneous media, fiber composites and functionally graded materials.  Those are caused by mechanical loads and by phase eigenstrains, such as thermal, transformation and inelastic strains, and also by cavities and cracks.    Worked examples show that the eigendeformations may...

  4. Thick film polymer-ceramic composites for pyroelectric applications

    Science.gov (United States)

    Dietze, M.; Krause, J.; Solterbeck, C.-H.; Es-Souni, M.

    2007-03-01

    Thick films of 0-3 composites of lead-zirconate-titanate ceramic and polyvinylidene-trifluorethylene copolymer have been produced by spin coating on gold-coated silicon wafers. The dielectric properties were investigated as a function of ceramic volume fraction and temperature. Pyroelectric measurements were undertaken by temperature modulation with a Peltier element. Additionally, the pyroelectric response has been investigated up to 3000Hz using a modulated laser. The piezoelectric response of the composites obtained by using a laser vibrometer are also reported. It is shown that the dielectric constant increases with increasing volume fraction of ceramic and that it reaches a maximum at a temperature in the range of 65-70°C due to the ferroelectric-paraelectric phase transition of the polymer matrix. The pyroelectric coefficient increases to 92μCm-2K-1 at a ceramic volume fraction of 20%. Furthermore the effective piezoelectric charge coefficient d33 of the composite almost vanishes at this composition. This composites show relatively high pyroelectric figures of merit and may be a potential candidate for pyroelectric sensor applications.

  5. Aerogel/polymer composite materials

    Science.gov (United States)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Roberson, Luke B. (Inventor); Clayton, LaNetra M. (Inventor)

    2010-01-01

    The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

  6. Composite materials having thiol groups

    International Nuclear Information System (INIS)

    A composite material having thiol groups comprises a rigid support material. The composite material may comprise a deformable gel (eg agarose) having thiol groups retained within the pore structure of a porous rigid support material (e.g. Kieselghur). The particles of composite material are used to prepare a radioactive gold isotope from a mercury 'parent' isotope. (author)

  7. Sealing ceramic material in low melting point glass

    Science.gov (United States)

    Moritoki, M.; Fujikawa, T.; Miyanaga, J.

    1984-01-01

    A structured device placed in an aerated crucible to pack ceramics molding substance that is to be processed was designed. The structure is wrapped by sealing material made of pyrex glass and graphite foil or sheet with a weight attached on top of it. The crucible is made of carbon; the ceramics material to be treated through heat intervenient press process is molding substance consisting mainly of silicon nitride.

  8. Aluminium nitrate ceramics: A potential UV dosemeter material

    DEFF Research Database (Denmark)

    Trinkler, L.; Bøtter-Jensen, L.; Berzina, B.

    The ceramic material AIN-Y2O3 is proposed as a potential ultraviolet radiation (UVR) dosemeter using optically stimulated luminescence (OSL) and thermally stimulated luminescence (TL). Experimental studies have shown that AIN ceramics exhibit attractive characteristics suitable for practical UV...... Al2O3:C; and (4) a large dynamic range TL signal (5 orders of magnitude). Although there is relatively high fading, it is demonstrated that AIN is a feasible material for UVR dosimetry using short integration times....

  9. Nondestructive characterization of advanced composite materials

    International Nuclear Information System (INIS)

    A comprehensive review of nondestructive characterization (NDC) techniques and their application to metal-matrix, polymer-matrix and ceramic-matrix composites is presented. Particular attention is given to the identification of critical materials properties and defects in these advanced composites. NDC is required: (i) to detect discrete defects, such as delaminations and cracking, and (ii) to measure distributed material properties, such as density, resistivity and elastic constants. Ultrasonic and eddy-current characterization are described in detail, along with new NDC results obtained at the Aeronautical and Maritime Research Laboratory. These include a method for the determination of fibre volume fraction in continuous fibre reinforced metal-matrix composites using eddy-current NDC, and the use of eddy-current methods to complement ultrasonic testing for characterization of impact damage in graphite-epoxy laminates. Future problem areas and possible solutions in NDC of advanced composites are also discussed. 90 refs., 1 tab., 6 figs

  10. Wear characteristics of polished and glazed lithium disilicate ceramics opposed to three ceramic materials.

    Science.gov (United States)

    Saiki, Osamu; Koizumi, Hiroyasu; Akazawa, Nobutaka; Kodaira, Akihisa; Okamura, Kentaro; Matsumura, Hideo

    2016-01-01

    This study compared the wear characteristics of a heat-pressed lithium disilicate ceramic material opposed to feldspathic porcelain, a lithium disilicate glass ceramic, and zirconia materials. Ceramic plate specimens were prepared from feldspathic porcelain (EX-3 nA1B), lithium disilicate glass ceramics (e.max CAD MO1/C14), and zirconia (Katana KT 10) and then ground or polished. Rounded rod specimens were fabricated from heat-pressed lithium disilicate glass ceramic (e.max press LT A3) and then glazed or polished. A sliding wear testing apparatus was used for wear testing. Wear of glazed rods was greater than that of polished rods when they were abraded with ground zirconia, ground porcelain, polished porcelain, or polished lithium disilicate ceramics. For both glazed and polished rods, wear was greater when the rods were abraded with ground plates. The findings indicate that application of a polished surface rather than a glazed surface is recommended for single restorations made of heat-pressed lithium disilicate material. In addition, care must be taken when polishing opposing materials, especially those used in occlusal contact areas. (J Oral Sci 58, 117-123, 2016). PMID:27021548

  11. Production of Ti-Fe Based MgAl2O4 Composite Material by Pressureless Infiltration Method

    OpenAIRE

    Bilici, İbrahim; GÜRÜ, Metin; Tekeli, Süleyman

    2015-01-01

    In spite of their high temperature and corrosion resistance, ceramics show a brittle nature under applied loads and this limits their usage areas. In order to compensate the weakness of ceramics with metals, which have high ductility, the production of ceramic-metal composite materials has been recently started. In the present study, a ceramic-metal composite material was produced by means of pressureless infiltration method using spinel oxide (MgAl2O4) and Ti-Fe alloy. Atmospheric conditions...

  12. Support Services for Ceramic Fiber-Ceramic Matrix Composites

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, J.P.; Nowok, J.W.

    1999-06-30

    The Facility for the Analysis of Chemical Thermodynamics (FACT) computer code was used to calculate the vaporization and condensation behavior of germanium (Ge) and lead (Pb) in coal gasification systems. Since condensation occurs at specific temperatures, the elements can concentrate in deposits that foul or corrode structures within an integrated gasification combined-cycle system or form very small particles that may be sticky in particle filter systems or be difficult to collect in a particulate-control cyclone. The calculations were performed in two steps: (1) vaporization from ash constitutents at 1600C at a system pressure of 22.9 atm and (2) condensation of GeX and PbX components at lower temperatures. The calculations indicate that Ge vaporizes as GeS and GeO and condenses through chemical vapor deposition as solid GeO2, Pb vaporizes primarily as PbS, with some Pb metal, and condenses as PbS as high as 880C for concentrations in the feed of 100 ppm on a mass basis. Although these concentrations would never be expected in the raw fuel, such levels could be reached if by-product dusts are recirculated into the gasifier feed material. Therefore, the calculations are useful in determining the maximum amount of recirculated material that can be allowed in the feed material to prevent formation of condensates at specific temperatures. The calculations also indicate that chlorine in the fuel has little effect on the behavior of Ge, but increases the concentration of vapor phase Pb as PbCl4 at temperatures below 800F, most significantly near 400F, at which temperature approximately 1/10 of the lead may be in the vapor phase as PbCl4. It is expected that this vapor would be collected in the system's scrubber.

  13. Research and development status of ceramic breeder materials

    International Nuclear Information System (INIS)

    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 also recognized by the International Thermonuclear Experimental Reactor (ITER) design team in its selection of ceramics as the first option breeder material. Blanket design studies have indicated areas in the properties data base that need further investigation. Current studies are focusing on issues such as tritium release behavior at high burnup, changes in thermophysical properties with burnup, compatibility between ceramic breeder and beryllium multiplier, and phase changes with burnup. Laboratory and in-reactor tests are underway, some as part of an international collaboration for development of ceramic breeder materials. 36 refs

  14. Assessment of damage in ceramics and ceramic matrix composites using ultrasonic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Rokhlin, S.I.; Chu, Y.C. [Ohio State Univ., Columbus, OH (United States). Dept. of Welding Engineering; Baaklini, G.Y. [NASA Lewis Research Center, Cleveland, OH (United States)

    1995-07-01

    This paper addresses the application of ultrasonic methods to damage assessment in ceramics and ceramic matrix composites. It focuses on damage caused by thermal shock and oxidation at elevated temperatures. The damage-induced changes in elastic constant and elastic anisotropy are determined by measuring the velocities of ultrasonic waves in different propagation directions within the sample. Thermal shock damage measurement is performed in ceramic samples of reaction bonded silicon nitride (RBSN) and aluminum oxide. Thermal shock treatment from different temperatures up to 1,000 C is applied to produce the microcracks. Both surface and bulk ultrasonic wave methods are used to correlate the change of elastic constants to microstructural degradation and to determine the change in elastic anisotropy induced by microcrack damage. Oxidation damage is studied in silicon carbide fiber/reaction bonded silicon nitride matrix (SCS-6/RBSN) composites. The oxidation is done by exposing the samples in a flowing oxygen environment at elevated temperatures, up to 1,400 C, for 100 hours. Significant changes of ultrasonic velocities were observed for composites before and after oxidation. The elastic constants of the composites were determined from the measured velocity data. The Young`s modulus in the fiber direction as obtained from ultrasonic measurements decreases significantly at 600 C but retains its original value at temperatures above 1,200 C. This agrees well with the results of destructive tests by other authors. The transverse longitudinal and shear moduli obtained from ultrasonic measurements decrease continually until 1,200 C. The results of this work show that the damage-induced anisotropy in both ceramics and ceramic matrix composites can be determined successfully by ultrasonic methods. This suggests the possibility of assessing damage severity using ultrasonic techniques.

  15. Composite definition features using the eastern ornament in ceramic tiles

    OpenAIRE

    Uss, V. F.; National Aviation University, Kyiv, Ukraine; Sahno, K. S.; National Aviation University, Kyiv

    2013-01-01

    This paper was asked a series of questions for the study of composition of the artistic shaping of ceramic tile with oriental ornaments and how to use in interior design. Particular attention is paid to individual elements of ornament and use them in areas such as kitchens, bathrooms, hookah area, cafe and more.

  16. Testing and Characterizing of Continuous Fiber Ceramic Composites

    Science.gov (United States)

    Lowden, Richard M.; Moore, Karren L.; Tortorelli, Pete F.; Lara-Curzio, Edgar

    1996-01-01

    Understanding interfacial microstructural evolution during environmental testing and use is critical to the development of stable continuous fiber ceramic composites (CFCC's) for their use in 'corrosive' environments. The use of advanced characterization techniques is required to track subtle microstructural changes. These techniques must be coordinated with other CFCC tasks to completely evaluate their interfacial behavior.

  17. Fatigue and frictional heating in ceramic matrix composites

    DEFF Research Database (Denmark)

    Jacobsen, T.K.; Sørensen, B.F.; Brøndsted, P.

    1997-01-01

    This paper describes an experimental technique for monitoring the damage evolution in ceramic matrix composites during cyclic testing. The damage is related to heat dissipation, which may be measured as radiated heat from the surface of the test specimen. In the present experimental set-up an iso...

  18. Ion sputtering erosion mechanisms of h-BN composite ceramics with textured microstructures

    International Nuclear Information System (INIS)

    Highlights: • Textured h-BN ceramics were made by hot press sintering using mullite as additives. • Sintering pressures play important role on ions sputtering resistance properties. • Textured microstructures lead to various surface morphologies by ion sputtering. • Sputtering erosion mechanisms include B–N bonds breaking and BN layers delamination. - Abstract: Since the hexagonal boron nitride (h-BN) grain shows typical lamellar structures, textured materials can be obtained by arranging h-BN grains along one direction. In this work, textured h-BN composite ceramics with the c-axis orientation arranged along the pressure direction are manufactured by hot-press sintering using mullite as the sintering additive. The results show that sintering pressures not only play a major role in the density and the textured degrees of composite ceramics, but also influence Xe ion erosion resistance performances. After Xe ion sputtering, compositions of both h-BN and mullite stay stable, while the elemental compositions have changed due to the so-called “preferential sputtering”. Sputtered surfaces along different orientations show diverse morphologies attributed to the textured microstructures. The erosion mechanisms of h-BN grains during Xe ion sputtering are breaking of B–N bonds and delamination of BN layers. While the mass loss of composite ceramics is due to the erosion of h-BN grains and mullite coupled with partial detachment of h-BN grains from the surface

  19. Numerical Analysis of Sub-Critical Crack Growth in Particulate Ceramic Composites

    Czech Academy of Sciences Publication Activity Database

    Majer, Zdeněk; Pletz, M.; Krautgasser, C.; Náhlík, Luboš; Hutař, Pavel; Bermejo, R.

    Amsterdam: Elsevier, 2014, s. 2071-2076. (Procedia Materials Science. 3). ISSN 2211-8128. [European Conference on Fracture /20./. Trondheim (NO), 30.06.2014-04.07.2014] Grant ostatní: GA MŠk(CZ) EE2.3.30.0039 Institutional support: RVO:68081723 Keywords : Fracture Mechanics * Low Temperature Co-fired Ceramics * Micro-crack Propagation * Finite Element Method * Lifetime Estimation Subject RIV: JI - Composite Materials

  20. Creep Forming of Carbon-Reinforced Ceramic-Matrix Composites

    Science.gov (United States)

    Vaughn, Wallace L.; Scotti, Stephan J.; Ashe, Melissa P.; Connolly, Liz

    2007-01-01

    A set of lecture slides describes an investigation of creep forming as a means of imparting desired curvatures to initially flat stock plates of carbon-reinforced ceramic-matrix composite (C-CMC) materials. The investigation is apparently part of a continuing effort to develop improved means of applying small CCMC repair patches to reinforced carbon-carbon leading edges of aerospace vehicles (e.g., space shuttles) prior to re-entry into the atmosphere of the Earth. According to one of the slides, creep forming would be an intermediate step in a process that would yield a fully densified, finished C-CMC part having a desired size and shape (the other steps would include preliminary machining, finish machining, densification by chemical vapor infiltration, and final coating). The investigation included experiments in which C-CMC disks were creep-formed by heating them to unspecified high temperatures for time intervals of the order of 1 hour while they were clamped into single- and double-curvature graphite molds. The creep-formed disks were coated with an oxidation- protection material, then subjected to arc-jet tests, in which the disks exhibited no deterioration after exposure to high-temperature test conditions lasting 490 seconds.

  1. High resolution energy loss research: Si compound ceramics and composites. [1990 annual progress report

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, R W; Lin, S H

    1990-12-31

    This report discusses proposed work on silicon compound ceramics and composites. High resolution composition and structure analysis of interfaces in ceramic and metal matrix composites and certain grain boundaries in silicon and its interfaces with oxides and nitrides is proposed. Composition and bonding analysis will be done with high spatial resolution (20 Angstroms or better) parallel electron energy loss spectroscopy using a field emission analytical electron microscope. Structural analysis will be done at the 1.8 Angstrom resolution level at 200kV by HREM. Theoretical electron energy loss cross section computations will be used to interpret electronic structure of these materials. Both self-consistent field MO and multiple scattering computational methods are being done and evaluated.

  2. Processing and characterization of pure cordierite and zirconia-doped cordierite ceramic composite by precipitation technique

    Indian Academy of Sciences (India)

    M Senthil Kumar; A Elaya Perumal; T R Vijayaram; Govindan Senguttuvan

    2015-06-01

    Pure cordierite and cordierite–ZrO2 composite (5–20 wt%) ceramics for various stoichiometric compositions were synthesized from standard raw materials by a novel precipitation technique. The analytical techniques such as X-ray diffraction, simultaneous thermogravimetric and differential thermal analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and bulk density were employed to evaluate the properties and microstructure. Results show that the ceramic composites consist of cordierite and zircon phases. The cordierite–zirconia (20 wt%) increased the fracture toughness value from 3.38 to 3.94 MPa, which is mainly due to martensitic transformation present in zirconia. The flexural strength of composite was found to increase from 126.46 to 297.62 MPa. The thermal expansion coefficients of cordierite and cordierite–zirconia (20 wt%) were 4.08 × 10−6 and 4.42 × 10−6 ° C−1 which may be due to the addition of zirconia.

  3. Phase composition of murataite ceramics for excess weapons plutonium immobilization

    Science.gov (United States)

    Sobolev, I. A.; Stefanovsky, S. V.; Myasoedov, B. F.; Kullako, Y. M.; Yudintsev, S. V.

    2000-07-01

    Among the host phases for actinides immobilization, murataite (cubic, space group Fm3m) with the general formula A4B2C7O22-x (A=Ca, Mn, Na, Ln, An; B=Mn, Ti, Zr, AnIV; C=Ti, Al, Fe; 0ceramics in detail has shown occurrence of several murataite varieties with three-, five-, and eight-fold fluorite unit cells. [1-3] The goal of the present step of work is to study an effect of waste elements on phase composition of murataite ceramic and isomorphic capacity of waste elements.

  4. Combustion Synthesis of h-BN-SiC Ceramic Composites

    Institute of Scientific and Technical Information of China (English)

    LI Hong-bo; ZHENG Yong-ting; ZHOU Li-juan; HAN Jie-cai

    2006-01-01

    The feasibility was demonstrated to fabricate h-BN-SiC ceramics through combustion synthesis of the mixture of boron carbide and silicon powders under 100 MPa nitrogen pressure. The mass fraction of BN and SiC in the combustion products were found to be 72 % and 28 % respectively. The thermodynamics of the synthesis reaction and the adiabatic combustion temperature were calculated on the theoretical ground. The bending strengths of the ceramics were measured to be 65.2 MPa at room temperature and 55 MPa at 1350 ℃. The phase composition and microstructure of the combustion products were identified by X-ray diffraction (XRD) and scanning electron microscopy (SEM).

  5. Ceramic nanotubes for polymer composites with stable anticorrosion properties

    Science.gov (United States)

    Fakhrullin, R. F.; Tursunbayeva, A.; Portnov, V. S.; L'vov, Yu. M.

    2014-12-01

    The use of natural halloysite clay tubes 50 nm in diameter as nanocontainers for loading, storing, and slowly releasing organic corrosion inhibitors is described. Loaded nanotubes can be mixed well with many polymers and dyes in amounts of 5-10 wt % to form a ceramic framework (which increases the strength of halloysite composites by 30-50%), increase the adhesion of these coatings to metals, and allow for the slow release of corrosion inhibitors in defects of coatings. A significant improvement of protective anticorrosion properties of polyacryl and polyurethane coatings containing ceramic nanotubes loaded with benzotriazole and hydroxyquinoline is demonstrated.

  6. Additive Manufacturing of Reactive In Situ Zr Based Ultra-High Temperature Ceramic Composites

    Science.gov (United States)

    Sahasrabudhe, Himanshu; Bandyopadhyay, Amit

    2016-03-01

    Reactive in situ multi-material additive manufacturing of ZrB2-based ultra-high-temperature ceramics in a Zr metal matrix was demonstrated using LENS™. Sound metallurgical bonding was achieved between the Zr metal and Zr-BN composites with Ti6Al4V substrate. Though the feedstock Zr power had α phase, LENS™ processing of the Zr powder and Zr-BN premix powder mixture led to the formation of some β phase of Zr. Microstructure of the Zr-BN composite showed primary grains of zirconium diboride phase in zirconium metal matrix. The presence of ZrB2 ceramic phase was confirmed by X-ray diffraction (XRD) analysis. Hardness of pure Zr was measured as 280 ± 12 HV and, by increasing the BN content in the feedstock, the hardness was found to increase. In Zr-5%BN composite, the hardness was 421 ± 10 HV and the same for Zr-10%BN composite was 562 ± 10 HV. It is envisioned that such multi-materials additive manufacturing will enable products in the future that cannot be manufactured using traditional approaches particularly in the areas of high-temperature metal-ceramic composites with compositional and functional gradation.

  7. Reactivity of ceramic coating materials with uranium and uranium trichlorid

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sung Ho; Cho, Choon Ho; Lee, Yoon Sang; Lee, Han Soo; Kim, Jeong Guk [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-05-15

    Uranium and uranium alloys are typically induction melted in graphite crucibles under a vacuum. The graphite crucible is used for the manufacturing of uranium ingots in the casting equipment. But, due to the chemical reactivity of uranium and most alloying elements with carbon, a protective ceramic coating is generally applied to the crucibles. In this study, to investigate the most suitable ceramic coating material applied to graphite melting crucibles and ingot moldsused in the melting and casting of uranium in the casting equipment, firstly, the thermodynamic analysis was performed by using HSC software to investigate the reactivity between uranium and several ceramic materials and the experiments on the reaction of ceramic coated crucibles in molten uranium were carried out at 1300 .deg. C

  8. Reactivity of ceramic coating materials with uranium and uranium trichlorid

    International Nuclear Information System (INIS)

    Uranium and uranium alloys are typically induction melted in graphite crucibles under a vacuum. The graphite crucible is used for the manufacturing of uranium ingots in the casting equipment. But, due to the chemical reactivity of uranium and most alloying elements with carbon, a protective ceramic coating is generally applied to the crucibles. In this study, to investigate the most suitable ceramic coating material applied to graphite melting crucibles and ingot moldsused in the melting and casting of uranium in the casting equipment, firstly, the thermodynamic analysis was performed by using HSC software to investigate the reactivity between uranium and several ceramic materials and the experiments on the reaction of ceramic coated crucibles in molten uranium were carried out at 1300 .deg. C

  9. High Temperature Mechanical Characterization of Ceramic Matrix Composites

    Science.gov (United States)

    Gyekenyesi, John Z.

    1998-01-01

    A high temperature mechanical characterization laboratory has been assembled at NASA Lewis Research Center. One contribution of this work is to test ceramic matrix composite specimens in tension in environmental extremes. Two high temperature tensile testing systems were assembled. The systems were assembled based on the performance and experience of other laboratories and meeting projected service conditions for the materials in question. The systems use frames with an electric actuator and a center screw. A PC based data acquisition and analysis system is used to collect and analyze the data. Mechanical extensometers are used to measure specimen strain. Thermocouples, placed near the specimen, are used to measure the specimen gage section temperature. The system for testing in air has a resistance element furnace with molybdenum disilicide elements and pneumatic grips with water cooling attached to hydraulic alignment devices. The system for testing in an inert gas has a graphite resistance element furnace in a chamber with rigidly mounted, water cooled, hydraulically actuated grips. Unidirectional SiC fiber reinforced reaction bonded Si3N4 and triaxially woven, two dimensional, SiC fiber reinforced enhanced SiC composites were tested in unidirectional tension. Theories for predicting the Young's modulus, modulus near the ultimate strength, first matrix cracking stress, and ultimate strength were applied and evaluated for suitability in predicting the mechanical behavior of SiC/RBSN and enhanced SiC/SiC composites. The SiC/RBSN composite exhibited pseudo tough behavior (increased area under the stress/strain curve) from 22 C to 1500 C. The rule of mixtures provides a good estimate of the Young's modulus of the SiC/RBSN composite using the constituent properties from room temperature to 1440 C for short term static tensile tests in air or nitrogen. The rule of mixtures significantly overestimates the secondary modulus near the ultimate strength. The ACK theory

  10. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    Science.gov (United States)

    Cox, Sarah B.; Lui, Donovan; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200C, beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

  11. Development of a ceramic material to cover walls to be applied in diagnostic radiological protection

    International Nuclear Information System (INIS)

    This study aims to formulate a ceramic composition for wall coating seeking to contribute to the optimization of diagnosis rooms' shielding. The work was based on experimental measures of X-radiation attenuation (80 and 100 kV) using ceramic coating materials containing different ceramic bases (red, white, gres, stoneware porcelain tiles, etc). Among the appraised ceramic bases, the white gres presented better attenuation properties and it was considered the most suitable material for the targets of this work. Different formulations of white gres were studied and altered in order to obtain better attenuation properties. Simulations of ceramic compositions using gres coating were made maintaining the percentages of 12-20% clay; 6-18% kaolin; 12-25% phyllite; 8-14% quartz; 1018% feldspar; 32-40% pegmatite and 6-8% talc in the composition of the necessary raw-material. The quantitative and qualitative chemical compositions of these materials were also evaluated and the most common representative elements are SiO2, Fe2O3, Al2O3, CaO and Ti2O3. Formulations containing Pb and Ba oxides were studied, considering that CaO can be replaced by PbO or BaO. The attenuation properties for X-radiation were investigated by computer simulations considering the incident and transmitted X-ray spectra for the different studied compositions and they were compared to the properties of the reference materials Pb, Ba and BaSO4 (barite). The results obtained with the simulations indicated the formulated composition of gres ceramic base that presented better attenuation properties considering the X-ray energies used in diagnosis (80, 100 and 150 kV). Ceramic plates based on the formulated compositions that presented lower percentage differences related to Pb were experimentally produced and physically tested as wall coating and protecting barrier. Properties as flexion resistance module, density, load rupture, water absorption and X radiation attenuation were evaluated for all produced

  12. Improvements in the processing of Yb:YAG ceramic materials

    OpenAIRE

    Serantoni, Marina; Esposito, Laura; Piancastelli, Andreana; Alderighi, Daniele; Pirri, Angela

    2010-01-01

    Laser ceramics can attain a significant role in the frame of the generation of high peak power, high energy laser pulses at high repetition rate, applications where fiber lasers or single crystals undergo fundamental or technological limitations. A ceramic material in order to be used as a laser amplifier, needs to fulfil strict requirements in terms of properties, in particular microstructure, purity level, porosity. The important role played by the production process on the transparency of ...

  13. Compact pulse forming line using barium titanate ceramic material

    Science.gov (United States)

    Kumar Sharma, Surender; Deb, P.; Shukla, R.; Prabaharan, T.; Shyam, A.

    2011-11-01

    Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO3) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 Ω load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber.

  14. Compact pulse forming line using barium titanate ceramic material.

    Science.gov (United States)

    Kumar Sharma, Surender; Deb, P; Shukla, R; Prabaharan, T; Shyam, A

    2011-11-01

    Ceramic material has very high relative permittivity, so compact pulse forming line can be made using these materials. Barium titanate (BaTiO(3)) has a relative permittivity of 1200 so it is used for making compact pulse forming line (PFL). Barium titanate also has piezoelectric effects so it cracks during high voltages discharges due to stresses developed in it. Barium titanate is mixed with rubber which absorbs the piezoelectric stresses when the PFL is charged and regain its original shape after the discharge. A composite mixture of barium titanate with the neoprene rubber is prepared. The relative permittivity of the composite mixture is measured to be 85. A coaxial pulse forming line of inner diameter 120 mm, outer diameter 240 mm, and length 350 mm is made and the composite mixture of barium titanate and neoprene rubber is filled between the inner and outer cylinders. The PFL is charged up to 120 kV and discharged into 5 Ω load. The voltage pulse of 70 kV, 21 ns is measured across the load. The conventional PFL is made up of oil or plastics dielectrics with the relative permittivity of 2-10 [D. R. Linde, CRC Handbook of Chemistry and Physics, 90th ed. (CRC, 2009); Xia et al., Rev. Sci. Instrum. 79, 086113 (2008); Yang et al., Rev. Sci. Instrum. 81, 43303 (2010)], which increases the length of PFL. We have reported the compactness in length achieved due to increase in relative permittivity of composite mixture by adding barium titanate in neoprene rubber. PMID:22129008

  15. Optical ceramics for fast scintillator materials

    Czech Academy of Sciences Publication Activity Database

    Nikl, Martin; Yanagida, T.; Yagi, H.; Yanagitani, T.; Mihóková, Eva; Yoshikawa, A.

    New York: Nova Science Publishers, 2013 - (Roa Rovira, J.; Rubi, M.), s. 127-176 ISBN 9781624177293 R&D Projects: GA MŠk LH12150; GA AV ČR KAN300100802 Institutional support: RVO:68378271 Keywords : scintillators * ceramics * oxides * halides * nanocomposites Subject RIV: BM - Solid Matter Physics ; Magnetism

  16. High-Temperature, Lightweight, Self-Healing Ceramic Composites for Aircraft Engine Applications

    Science.gov (United States)

    Raj, Sai V.; Bhatt, Ramkrishna

    2013-01-01

    The use of reliable, high-temperature, lightweight materials in the manufacture of aircraft engines is expected to result in lower fossil and biofuel consumption, thereby leading to cost savings and lower carbon emissions due to air travel. Although nickel-based superalloy blades and vanes have been successfully used in aircraft engines for several decades, there has been an increased effort to develop high-temperature, lightweight, creep-resistant substitute materials under various NASA programs over the last two decades. As a result, there has been a great deal of interest in developing SiC/SiC ceramic matrix composites (CMCs) due to their higher damage tolerance compared to monolithic ceramics. Current-generation SiC/SiC ceramic matrix composites rely almost entirely on the SiC fibers to carry the load, owing to the premature cracking of the matrix during loading. Thus, the high-temperature usefulness of these CMCs falls well below their theoretical capabilities. The objective of this work is to develop a new class of high-temperature, lightweight, self-healing, SiC fiber-reinforced, engineered matrix ceramic composites.

  17. Comparison of shear bond strengths of conventional orthodontic composite and nano-ceramic restorative composite: An in vitro study

    Directory of Open Access Journals (Sweden)

    Namit Nagar

    2013-01-01

    Full Text Available Objectives: To compare the shear bond strength of a nano-ceramic restorative composite Ceram-X MonoTM♦, a restorative resin with the traditional orthodontic composite Transbond XTTM† and to evaluate the site of bond failure using Adhesive Remnant Index. Materials and Methods: Sixty extracted human premolars were divided into two groups of 30 each. Stainless steel brackets were bonded using Transbond XTTM† (Group I and Ceram-X MonoTM♦ (Group II according to manufacturer′s protocol. Shear bond strength was measured on Universal testing machine at crosshead speed of 1 mm/minute. Adhesive Remnant Index scores were assigned to debonded brackets of each group. Data was analyzed using unpaired ′t′ test and Chi square test. Results: The mean shear bond strength of Group I (Transbond XTTM† was 12.89 MPa ± 2.19 and that of Group II (Ceram-X MonoTM was 7.29 MPa ± 1.76. Unpaired ′t′ test revealed statistically significant differences amongst the shear bond strength of the samples measured. Chi-square test revealed statistically insignificant differences amongst the ARI scores of the samples measured. Conclusions: Ceram-X MonoTM♦ had a lesser mean shear bond strength when compared to Transbond XTTM† which was statistically significant difference. However, the mean shear bond of Ceram X Mono was within the clinically acceptable range for bonding. Ceram-X MonoTM† and Transbond XTTM† showed cohesive fracture of adhesive in 72.6% and 66.6% of the specimens, respectively.

  18. Assessment of damage in ceramics and ceramic matrix composites using ultrasonic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Y.C.; Baaklini, G.Y.; Rokhlin, S.I.

    1993-05-01

    This paper addresses the application of ultrasonic sensing to damage assessment in ceramics and ceramic matrix composites. It focuses on damage caused by thermal shock or oxidation at elevated temperatures, which often results in elastic anisotropy. This damaged-induced anisotropy is determined by measuring the velocities of ultrasonic waves in different propagation directions. Thermal shock damage is assessed in ceramic samples of reaction bonded silicon nitride (RBSN). Thermal shock treatment from different temperatures up to 1000 C is applied to produce the microcracks. Results indicate that most microcracks produced by thermal shock are located near sample surfaces. Ultrasonic measurements using the surface wave method are found to correlate well with measurements of degradation of mechanical properties obtained independently by other authors using destructive methods. Oxidation damage is assessed in silicon carbide fiber/reaction bonded silicon nitride matrix (SCS-6/RBSN) composites. The oxidation is done by exposing the samples in a flowing oxygen environment at elevated temperatures, up to 1400 C, for 100 hr. The Youngs' modulus in the fiber direction as obtained from ultrasonic measurements decreases significantly at 600 C but retains its original value at temperatures above 1200 C. This agrees well with the results of destructive tests by other authors. On the other hand, the transverse moduli obtained from ultrasonic measurements decrease continually until 1200 C. Measurements on the shear stiffnesses show behavior similar to the transverse moduli. The results of this work show that the damage-induced anisotropy in both ceramics and ceramic matrix composites can be determined successfully by ultrasonic methods. This suggests the possibility of assessing damage severity using ultrasonic techniques.

  19. Assessment of damage in ceramics and ceramic matrix composites using ultrasonic techniques

    Science.gov (United States)

    Chu, Y. C.; Baaklini, G. Y.; Rokhlin, S.I.

    1993-01-01

    This paper addresses the application of ultrasonic sensing to damage assessment in ceramics and ceramic matrix composites. It focuses on damage caused by thermal shock or oxidation at elevated temperatures, which often results in elastic anisotropy. This damaged-induced anisotropy is determined by measuring the velocities of ultrasonic waves in different propagation directions. Thermal shock damage is assessed in ceramic samples of reaction bonded silicon nitride (RBSN). Thermal shock treatment from different temperatures up to 1000 C is applied to produce the microcracks. Results indicate that most microcracks produced by thermal shock are located near sample surfaces. Ultrasonic measurements using the surface wave method are found to correlate well with measurements of degradation of mechanical properties obtained independently by other authors using destructive methods. Oxidation damage is assessed in silicon carbide fiber/reaction bonded silicon nitride matrix (SCS-6/RBSN) composites. The oxidation is done by exposing the samples in a flowing oxygen environment at elevated temperatures, up to 1400 C, for 100 hr. The Youngs' modulus in the fiber direction as obtained from ultrasonic measurements decreases significantly at 600 C but retains its original value at temperatures above 1200 C. This agrees well with the results of destructive tests by other authors. On the other hand, the transverse moduli obtained from ultrasonic measurements decrease continually until 1200 C. Measurements on the shear stiffnesses show behavior similar to the transverse moduli. The results of this work show that the damage-induced anisotropy in both ceramics and ceramic matrix composites can be determined successfully by ultrasonic methods. This suggests the possibility of assessing damage severity using ultrasonic techniques.

  20. Evaluation of a Variable-Impedance Ceramic Matrix Composite Acoustic Liner

    Science.gov (United States)

    Jones, M. G.; Watson, W. R.; Nark, D. M.; Howerton, B. M.

    2014-01-01

    As a result of significant progress in the reduction of fan and jet noise, there is growing concern regarding core noise. One method for achieving core noise reduction is via the use of acoustic liners. However, these liners must be constructed with materials suitable for high temperature environments and should be designed for optimum absorption of the broadband core noise spectrum. This paper presents results of tests conducted in the NASA Langley Liner Technology Facility to evaluate a variable-impedance ceramic matrix composite acoustic liner that offers the potential to achieve each of these goals. One concern is the porosity of the ceramic matrix composite material, and whether this might affect the predictability of liners constructed with this material. Comparisons between two variable-depth liners, one constructed with ceramic matrix composite material and the other constructed via stereolithography, are used to demonstrate this material porosity is not a concern. Also, some interesting observations are noted regarding the orientation of variable-depth liners. Finally, two propagation codes are validated via comparisons of predicted and measured acoustic pressure profiles for a variable-depth liner.

  1. Effect of ceramic thickness and composite bases on stress distribution of inlays--a finite element analysis.

    Science.gov (United States)

    Durand, Letícia Brandão; Guimarães, Jackeline Coutinho; Monteiro Junior, Sylvio; Baratieri, Luiz Narciso

    2015-01-01

    The purpose of this study was to determine the effect of cavity depth, ceramic thickness, and resin bases with different elastic modulus on von Mises stress patterns of ceramic inlays. Tridimensional geometric models were developed with SolidWorks image software. The differences between the models were: depth of pulpal wall, ceramic thickness, and presence of composite bases with different thickness and elastic modulus. The geometric models were constrained at the proximal surfaces and base of maxillary bone. A load of 100 N was applied. The stress distribution pattern was analyzed with von Mises stress diagrams. The maximum von Mises stress values ranged from 176 MPa to 263 MPa and varied among the 3D-models. The highest von Mises stress value was found on models with 1-mm-thick composite resin base and 1-mm-thick ceramic inlay. Intermediate values (249-250 MPa) occurred on models with 2-mm-thick composite resin base and 1-mm-thick ceramic inlay and 1-mm-thick composite resin base and 2-mm-thick ceramic inlay. The lowest values were observed on models restored exclusively with ceramic inlay (176 MPa to 182 MPa). It was found that thicker inlays distribute stress more favorably and bases with low elastic modulus increase stress concentrations on the internal surface of the ceramic inlay. The increase of ceramic thickness tends to present more favorable stress distribution, especially when bonded directly onto the cavity without the use of supporting materials. When the use of a composite base is required, composite resin with high elastic modulus and reduced thickness should be preferred. PMID:25831105

  2. Ancient ceramics and glass compositional studies using nuclear methods

    International Nuclear Information System (INIS)

    relative error. The detection limits are in the range of 30 (Ni, As, Sb) to 200 ppm (Ti, Fe, Zn, Sn, Ba, Pb) for trace elements and in the range of 0.2 to 1percent for major lights elements. These detection limits were tested using NBS geological standards (W1, BM, KH). Some compositional results on various archaeological ceramics objects from Romanian sites ( glaze and painting agents for neolithic Cucuteni and blue Iznik Turkish ceramics but also clay elemental analyses) are presented. For glasses, chemical differences that occur during preparation of materials will affect the elemental composition and could be used for the identification of technologies and workshops involved. The problem is to identify colouring agents, decolorants, opacifiers and fining agents. The XRF and FNAA techniques were used. Some results on Byzantine (XIII Century) glass bracelets and XVIII Century vessel samples founded in South-Eastern Romania are presented

  3. Properties and Performance of Ceramic Composite Components

    Energy Technology Data Exchange (ETDEWEB)

    Case, S.W.; Halverson, H.G.; Carter, R.H.; Wone, M.; Reifsnider, K.L.

    1999-08-09

    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. These needs have prompted research aimed toward a better understanding of material behavior in fossil energy environments and the development of new materials capable of substantial enhancement of plant operations, reliability, and efficiency.

  4. Measuring Fracture Times Of Ceramics

    Science.gov (United States)

    Shlichta, Paul J.; Bister, Leo; Bickler, Donald G.

    1989-01-01

    Electrical measurements complement or replace fast cinematography. Electronic system measures microsecond time intervals between impacts of projectiles on ceramic tiles and fracture tiles. Used in research on ceramics and ceramic-based composite materials such as armor. Hardness and low density of ceramics enable them to disintegrate projectiles more efficiently than metals. Projectile approaches ceramic tile specimen. Penetrating foil squares of triggering device activate display and recording instruments. As ceramic and resistive film break oscilloscope plots increase in electrical resistance of film.

  5. Low Cost Fabrication of Silicon Carbide Based Ceramics and Fiber Reinforced Composites

    Science.gov (United States)

    Singh, M.; Levine, S. R.

    1995-01-01

    A low cost processing technique called reaction forming for the fabrication of near-net and complex shaped components of silicon carbide based ceramics and composites is presented. This process consists of the production of a microporous carbon preform and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture with very good control of pore volume and pore size thereby yielding materials with tailorable microstructure and composition. Mechanical properties (elastic modulus, flexural strength, and fracture toughness) of reaction-formed silicon carbide ceramics are presented. This processing approach is suitable for various kinds of reinforcements such as whiskers, particulates, fibers (tows, weaves, and filaments), and 3-D architectures. This approach has also been used to fabricate continuous silicon carbide fiber reinforced ceramic composites (CFCC's) with silicon carbide based matrices. Strong and tough composites with tailorable matrix microstructure and composition have been obtained. Microstructure and thermomechanical properties of a silicon carbide (SCS-6) fiber reinforced reaction-formed silicon carbide matrix composites are discussed.

  6. Intraoral repair of all ceramic fixed partial denture utilizing preimpregnated fiber reinforced composite.

    Science.gov (United States)

    Turkaslan, Süha; Tezvergil-Mutluay, Arzu

    2008-01-01

    All ceramic fixed partial dentures (FPD)s exhibit enhanced biocompatibility and esthetics as compared to metal-ceramic restorations. However, framework fractures are frequently reported especially when the connector dimensions are inadequate to withstand the high tensile stresses. The repair of the failed connector would be desirable rather than the complete removal and renewal since the latter is an expensive and time consuming procedure. Furthermore, the replacement or removal of the restoration for extra-oral repair purposes might increase the risk of destroying the entire restoration or damaging the abutment teeth during the removal. This article presents a direct intra-oral method that may be used to repair the connector fractures of all-ceramic FPDs which are otherwise clinically satisfactory. In the present technique, the connector is reconstructed intraorally utilizing composite resin restorative material reinforced with E-glass-fiber. PMID:19212511

  7. 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.

  8. Progress in the characterisation of structural oxide/oxide ceramic matrix composites fabricated by electrophoretic deposition (EPD)

    Czech Academy of Sciences Publication Activity Database

    Stoll, E.; Mahr, P.; Kruger, H. G.; Kern, H.; Dlouhý, Ivo; Boccaccini, A. R.

    2006-01-01

    Roč. 8, č. 4 (2006), s. 282-285. ISSN 1438-1656 R&D Projects: GA ČR(CZ) GA106/05/0495 Institutional research plan: CEZ:AV0Z20410507 Keywords : electorphoretic deposition * oxid/oxid ceramic matrix composites * flexural strength Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.402, year: 2006 http://www3.interscience.wiley.com/cgi-bin/jissue/112579545

  9. Water reservoir as resource of raw material for ceramic industry

    Science.gov (United States)

    Irie, M.; Tarhouni, J.

    2015-04-01

    The industries related to the ceramics such as construction bricks, pottery and tile are the important sectors that cover the large part of the working population in Tunisia. The raw materials, clay or silt are excavated from opencast site of limestone clay stratum. The opencast site give the negative impact on landscape and environment, risks of landslide, soil erosion etc. On the other hand, a most serious problem in water resource management, especially in arid land such as Tunisia, is sedimentation in reservoirs. Sediment accumulation in the reservoirs reduces the water storage capacity. The authors proposed the exploitation of the sediment as raw material for the ceramics industries in the previous studies because the sediment in Tunisia is fine silt. In this study, the potential of the water reservoirs in Tunisia as the resource of the raw material for the ceramics industries is estimated from the sedimentation ratio in the water reservoirs.

  10. Composite materials for thermal energy storage: enhancing performance through microstructures.

    Science.gov (United States)

    Ge, Zhiwei; Ye, Feng; Ding, Yulong

    2014-05-01

    Chemical incompatibility and low thermal conductivity issues of molten-salt-based thermal energy storage materials can be addressed by using microstructured composites. Using a eutectic mixture of lithium and sodium carbonates as molten salt, magnesium oxide as supporting material, and graphite as thermal conductivity enhancer, the microstructural development, chemical compatibility, thermal stability, thermal conductivity, and thermal energy storage performance of composite materials are investigated. The ceramic supporting material is essential for preventing salt leakage and hence provides a solution to the chemical incompatibility issue. The use of graphite gives a significant enhancement on the thermal conductivity of the composite. Analyses suggest that the experimentally observed microstructural development of the composite is associated with the wettability of the salt on the ceramic substrate and that on the thermal conduction enhancer. PMID:24591286

  11. NANOSTRUCTURED CERAMICS AND COMPOSITES FOR REFRACTORY APPLICATIONS IN COAL GASIFICATION

    Energy Technology Data Exchange (ETDEWEB)

    Paul Brown

    2005-01-31

    A class of ceramics, capable of exhibiting low coefficients of thermal expansion and catalytic properties was investigated. Investigations were directed towards nanoengineering of NZP ceramics and NZP-based composites by chemical means by controlling their compositions and processing variables. NaZr{sub 2}(PO{sub 4}){sub 3} (NZP) was synthesized by combining water-soluble precursors leading to the precipitation of a gel that was dried, calcined, pressed into pellets, then fired at 850 C. Without chemical additives, the resulting ceramic comprised pores ranging in size from approximately 25 to 50 nm and a surface area of about 30m{sup 2}/g. Hydroxyapatite, which has a needle-like morphology, was mechanically mixed with the calcined gel to template NZP crystallization. What resulted was a coarsening of the pore structure and a decrease in surface area. When copper nitrate was added to the solution during synthesis, the resulting ceramic underwent shrinkage upon firing as well as an increase in strength. HAp and copper additions combined resulted in 40% volume shrinkage and a doubling of the tensile strength to 16MPa. A very different type of porosity was achieved when silica was partly substituted for phosphorous in the NZP structure. Na{sub 3}Zr{sub 2}(Si{sub 2}P)O{sub 12} (NASCION) was synthesized in the same manner as NZP, but the fired ceramic possessed a reticulated pore structure comprising large cavities ranging in size from 5 to 50 {micro}m. The NASCION ceramic either shrank or expanded upon firing depending on when the silica was added during synthesis. When the silica precursor (amorphous, precipitated silica) was added before the calcining step, the pressed pellets expanded during firing, whereas they shrank when the silica was added after the gel was calcined. The observed dilation increased with increasing calcining temperature and particle size, up to 26%. The contraction of the ceramic when fired increased with increasing calcining temperature and a

  12. Method of producing a silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    Science.gov (United States)

    Bansal, Narottam P. (Inventor)

    1995-01-01

    A SrO-Al2O3-2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  13. Silicon carbide fiber reinforced strontium aluminosilicate glass-ceramic matrix composite

    Science.gov (United States)

    Bansal, Narottam (Inventor)

    1992-01-01

    A SrO-Al2O3 - 2SrO2 (SAS) glass ceramic matrix is reinforced with CVD SiC continuous fibers. This material is prepared by casting a slurry of SAS glass powder into tapes. Mats of continuous CVD-SiC fibers are alternately stacked with the matrix tapes. This tape-mat stack is warm-pressed to produce a 'green' composite. Organic constituents are burned out of the 'green' composite, and the remaining interim material is hot pressed.

  14. Potential assisted fabrication of metal-ceramic composite coatings

    International Nuclear Information System (INIS)

    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.)

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

    International Nuclear Information System (INIS)

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

  16. The effect of various primers on shear bond strength of zirconia ceramic and resin composite

    Directory of Open Access Journals (Sweden)

    Sasiwimol Sanohkan

    2013-01-01

    Full Text Available Aims: To determine the in vitro shear bond strengths (SBS of zirconia ceramic to resin composite after various primer treatments. Materials and Methods: Forty zirconia ceramic (Zeno, Wieland Dental specimens (10 mm in diameter and 2 mm thick were prepared, sandblasted with 50 μm alumina, and divided into four groups (n = 10. Three experimental groups were surface treated with three primers; CP (RelyX Ceramic Primer, 3M ESPE, AP (Alloy Primer, Kuraray Medical, and MP (Monobond Plus, Ivoclar Vivadent AG. One group was not treated and served as the control. All specimens were bonded to a resin composite (Filtek Supreme XT, 3M ESPE cylinder with an adhesive system (Adper Scotchbond Multi-Purpose Plus Adhesive, 3M ESPE and then stored in 100% humidity at 37°C for 24 h before SBS testing in a universal testing machine. Mean SBS (MPa were analyzed with one-way analysis of variance (ANOVA and the Tukey′s Honestly Significant Difference (HSD test (α = 0.05. Results: Group AP yielded the highest mean and standard deviation (SD value of SBS (16.8 ± 2.5 MPa and Group C presented the lowest mean and SD value (15.4 ± 1.6 MPa. The SBS did not differ significantly among the groups (P = 0.079. Conclusions: Within the limitations of this study, the SBS values between zirconia ceramic to resin composite using various primers and untreated surface were not significantly different.

  17. Novel Hybrid Ablative/Ceramic Layered Composite for Earth Re-entry Thermal Protection: Microstructural and Mechanical Performance

    OpenAIRE

    Triantou, K.; Mergia, K.; Marinou, A.; Vekinis, G.; Bárcena, Jorge; Florez, S; Perez, B; Pinaud, G.; Bouilly, J.M.; Fischer, W.P.P.

    2015-01-01

    In view of spacecraft re-entry applications into planetary atmospheres, hybrid thermal protection systems based on layered composites of ablative materials and ceramic matrix composites are investigated. Joints of ASTERM (TM) lightweight ablative material with C-f/SiC (SICARBON (TM)) were fabricated using commercial high temperature inorganic adhesives. Sound joints without defects are produced and very good bonding of the adhesive with both base materials is observed. Mechanical shear tests ...

  18. Ceramic-metal composite formation by reactive metal penetration

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E.; Ewsuk, K.G. [Sandia National Labs., Albuquerque, NM (United States); Fahrenholtz, W.G. [New Mexico Univ., Albuquerque, NM (United States). Advanced Materials Lab.; Lakshman, B.B. [Sandia National Labs., Albuquerque, NM (United States)

    1996-11-01

    Ceramic-metal composites can be made to near-net-shape by reactive penetration of dense ceramic preforms by molten metals. Reactive metal penetration is driven by a strongly negative Gibbs energy for reaction. For Al, the general form of the reaction is (x+2) Al + (3/y) MO[sub y] yields Al[sub 2]O[sub 3] + M[sub 3/y]Al[sub x], where MO[sub y] is an oxide that is wet by molten Al. In low PO[sub 2] atmospheres and at temperatures above about 900 degrees C, molten Al reduces mullite to produce Al[sub 2]O[sub 3] and Si. The Al/mullite reaction has a delta G[sub r] degree(927 degrees C) of -338 per mole of mullite and, for fully dense mullite, the theoretical volume change on reaction is less than 1%. Experiments with commercial mullite containing a silicate grain boundary phase average less than 2% volume change on reaction. In the Al/mullite system, reactive metal penetration produces a fine-grained alumina skeleton with an interspersed metal phase. With > or =15 vol.% excess aluminum, mutually interpenetrating ceramic-metal composites are produced. Properties measurements show that ceramic-metal composites produced by reactive metal penetration of mullite by Al have a Young`s modulus and hardness similar to that of Al[sub 2]O[sub 3], with improved fracture toughness. Other compositions also are candidates for in- situ reaction synthesis, but they exhibit differences in reaction kinetics, most probably due to different wetting behavior.

  19. Failure of Ceramic Composites in Non-Uniform Stress Fields

    OpenAIRE

    Rajan, Varun

    2014-01-01

    Continuous-fiber ceramic matrix composites (CMCs) are of interest as hot-section components in gas turbine engines due to their refractoriness and low density relative to metallic alloys. In service, CMCs will be subjected to spatially inhomogeneous temperature and stress fields. Robust tools that enable prediction of deformation and fracture under these conditions are therefore required for component design and analysis. Such tools are presently lacking. The present work helps to address thi...

  20. Approach to microstructure-behavior relationships for ceramic matrix composites reinforced by continuous fibers

    OpenAIRE

    Lamon Jacques

    2015-01-01

    Ceramic matrix composites (CMCs) reinforced with continuous fibers exhibit several features that differentiate them from homogeneous unreinforced materials. The microstructure consists of various distinct constituents: fibres, matrix, and fiber/matrix interfaces or interphases. Several entities at micro- and mesoscopic length scales can be defined depending on fiber arrangement. Furthermore, the CMCs contain flaw populations that govern matrix cracking and fiber failures. The paper describes ...

  1. Composite Coatings of Alumina-based Ceramics and Stainless Steel Manufactured by Plasma Spraying

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Ageorges, H.; Neufuss, Karel; Zahálka, F.

    2009-01-01

    Roč. 15, č. 2 (2009), s. 108-114. ISSN 1392-1320 R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Cermet * plasma spraying * microstructure * elastic modulus * wear resistance Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.299, year: 2009 http://internet.ktu.lt/en/science/journals/medz/medz0-97.html#Composite_Coatings_

  2. Effect of Load Rate on Ultimate Tensile Strength of Ceramic Matrix Composites at Elevated Temperatures

    Science.gov (United States)

    Choi, Sung R.; Gyekenyesi, John P.

    2001-01-01

    The strengths of three continuous fiber-reinforced ceramic composites, including SiC/CAS-II, SiC/MAS-5 and SiC/SiC, were determined as a function of test rate in air at 1100 to 1200 C. All three composite materials exhibited a strong dependency of strength on test rate, similar to the behavior observed in many advanced monolithic ceramics at elevated temperatures. The application of the preloading technique as well as the prediction of life from one loading configuration (constant stress-rate) to another (constant stress loading) suggested that the overall macroscopic failure mechanism of the composites would be the one governed by a power-law type of damage evolution/accumulation, analogous to slow crack growth commonly observed in advanced monolithic ceramics. It was further found that constant stress-rate testing could be used as an alternative to life prediction test methodology even for composite materials, at least for short range of lifetimes and when ultimate strength is used as the failure criterion.

  3. Materials Development Program: Ceramic Technology Project bibliography, 1984--1992

    Energy Technology Data Exchange (ETDEWEB)

    1994-03-01

    The Ceramic Technology [for Advanced Heat Engines] Project was begun in 1983 to meet the ceramic materials needs of the companion DOE automotive engine program, the Advanced Gas Turbine (AGT) project, and the Heavy Duty Transport (low-heat-rejection, heavy-duty diesel) project. Goal is to develop an industry technology base for reliable and cost effective ceramics for applications in advanced automotive gas turbine and diesel engines. Research areas were identified following extensive input from industry and academia. Majority of research is done by industry (60%); work is also done at colleges and universities, in-house, and at other national laboratories and government agencies. In the beginning, reliability of ceramic components was the key issue. The reliability issues have largely been met and, at the present time, cost is the driving issue, especially in light of the highly cost-sensitive automotive market. Emphasis of the program has now been shifted toward developing cost-effective ceramic components for high-performance engines in the near-term. This bibliography is a compilation of publications done in conjunction with the Ceramic Technology Project since its beginning. Citations were obtained from reports done by participants in the project. We have tried to limit citations to those published and easily located. The end date of 1992 was selected.

  4. Ceramics reinforced metal base composite coatings produced by CO II laser cladding

    Science.gov (United States)

    Yang, Xichen; Wang, Yu; Yang, Nan

    2008-03-01

    Due to the excellent performance in high strength, anti-temperature and anti-wear, ceramics reinforced metal base composite material was used in some important fields of aircraft, aerospace, automobile and defense. The traditional bulk metal base composite materials are the expensive cost, which is limited in its industrial application. Development of laser coating of ceramics reinforced metal base composite is very interesting in economy. This paper is focused on three laser cladding ceramics coatings of SiC particle /Al matrix , Al IIO 3 powder/ Al matrix and WC + Co/mild steel matrix. Powder particle sizes are of 10-60μm. Chemical contents of aluminum matrix are of 3.8-4.0% Cu, 1.2-1.8% Mg, 0.3-0.99% Mn and balance Al. 5KW CO II laser, 5 axes CNC table, JKF-6 type powder feeder and co-axis feeder nozzle are used in laser cladding. Microstructure and performance of laser composite coatings have been respectively examined with OM,SEM and X-ray diffraction. Its results are as follows : Microstructures of 3C-,6H- and 5H- SiC particles + Al + Al 4SiC 4 + Si in SiC/Al composite, hexagonal α-Al IIO 3 + cubic γ-Al IIO 3 + f.c.c Al in Al IIO 3 powder/ Al composite and original WC particles + separated WC particles + eutectic WC + γ-Co solid solution + W IIC particles in WC + Co/steel coatings are respectively recognized. New microstructures of 5H-SiC in SiC/Al composite, cubic γ-Al IIO 3 in Al IIO 3 composite and W IIC in WC + Co/ steel composite by laser cladding have been respectively observed.

  5. Vibrational Damping of Composite Materials

    OpenAIRE

    Biggerstaff, Janet M.

    2006-01-01

    The purpose of this research was to develop new methods of vibrational damping in polymeric composite materials along with expanding the knowledge of currently used vibrational damping methods. A new barrier layer technique that dramatically increased damping in viscoelastic damping materials that interacted with the composite resin was created. A method for testing the shear strength of damping materials cocured in composites was developed. Directional damping materials, where the loss facto...

  6. Metals and Ceramics Division materials science annual progress report for period ending June 30, 1977

    International Nuclear Information System (INIS)

    Progress is reported for research programs in the metals and ceramics division of ORNL. In structure of materials, theoretical research, x-ray diffraction studies, studies of erosion of ceramics, preparation and synthesis of high temperature and special service materials, and studies of stabilities of microphases in high-temperature structural materials. Research into deformation and mechanical properties included physical metallurgy, and grain boundary segregation and embrittlement. Physical properties and transport phenomena were studied and included mechanisms of surface and solid state reactions, and properties of superconducting materials. The radiation effects program, directed at understanding the effects of composition and microstructure on the structure and properties of materials irradiated at elevated temperatures, is also described

  7. Metals and Ceramics Division materials science annual progress report for period ending June 30, 1977

    Energy Technology Data Exchange (ETDEWEB)

    McHargue, C.J. (comp.)

    1977-09-01

    Progress is reported for research programs in the metals and ceramics division of ORNL. In structure of materials, theoretical research, x-ray diffraction studies, studies of erosion of ceramics, preparation and synthesis of high temperature and special service materials, and studies of stabilities of microphases in high-temperature structural materials. Research into deformation and mechanical properties included physical metallurgy, and grain boundary segregation and embrittlement. Physical properties and transport phenomena were studied and included mechanisms of surface and solid state reactions, and properties of superconducting materials. The radiation effects program, directed at understanding the effects of composition and microstructure on the structure and properties of materials irradiated at elevated temperatures, is also described. (GHT)

  8. Boron carbide whisker and platelet reinforced ceramic matrix composites

    International Nuclear Information System (INIS)

    Boron carbide whisker and platelet-reinforced alumina and boron-carbide-whisker-reinforced silicon carbide composites were prepared by hot-pressing. The mechanical properties of hot-pressed boron carbide platelet and whisker-reinforced composites are better than the inherent ceramic matrix. A maximum fracture toughness, K(lc), of 9.5 MPa sq rt m is achieved for alumina/boron carbide whisker composites, 8.6 MPa sq rt m is achieved for alumina/boron carbide platelet composites, and 3.8 MPa sq rt m is achieved for silicon carbide/boron carbide whisker composites. The fracture toughness is dependent on the volume fraction of the platelets and whiskers. 12 refs

  9. The Increasing of Bentonite Quality as a Composite of B-3 Waste CeramicSolidification Process

    International Nuclear Information System (INIS)

    The ceramic composite from local material of bentonite Nanggulan wascarried out. The material were grinded, sieved to get through 100 mesh,rinsed with aquadest, dried at the temperature of 60 oC and putted in theexecutor, then were calcinate (physical activated) at 300 oC and chemicalactivated with NaCl 1.0 to 5.0 M. The activated bentonite were contacted withlead concentration of 150 to 500 ppm and then were dried at 60 oC.Bentonite-Pb which obtained was made to pellet by adding weak cullet withcomposition variation of bentonite-Pb to cullet = 20:80, 25:75, 30:70, 35:65,and 40:60%, and ignited on furnace at the the temperature of 850 oC, 900oC, and 1000 oC for composite ceramic production. The chemical compositionand mineral test for original local material and ceramic composite ofoptimization result were done by using AAS and X-ray diffraction, whereas theleaching test, pressure and porosity test were done only for ceramiccomposite. The experiment results were reported in this paper. (author)

  10. Recent advances in understanding the reinforcing ability and mechanism of carbon nanotubes in ceramic matrix composites

    International Nuclear Information System (INIS)

    Since the discovery of carbon nanotubes (CNTs), commonly referred to as ultimate reinforcement, the main purpose for fabricating CNT–ceramic matrix composites has been mainly to improve the fracture toughness and strength of the ceramic matrix materials. However, there have been many studies reporting marginal improvements or even the degradation of mechanical properties. On the other hand, those studies claiming noticeable toughening measured using indentation, which is an indirect/unreliable characterization method, have not demonstrated the responsible mechanisms applicable to the nanoscale, flexible CNTs; instead, those studies proposed those classical methods applicable to microscale fiber/whisker reinforced ceramics without showing any convincing evidence of load transfer to the CNTs. Therefore, the ability of CNTs to directly improve the macroscopic mechanical properties of structural ceramics has been strongly questioned and debated in the last ten years. In order to properly discuss the reinforcing ability (and possible mechanisms) of CNTs in a ceramic host material, there are three fundamental questions to our knowledge at both the nanoscale and macroscale levels that need to be addressed: (1) does the intrinsic load-bearing ability of CNTs change when embedded in a ceramic host matrix?; (2) when there is an intimate atomic-level interface without any chemical reaction with the matrix, could one expect any load transfer to the CNTs along with effective load bearing by them during crack propagation?; and (3) considering their nanometer-scale dimensions, flexibility and radial softness, are the CNTs able to improve the mechanical properties of the host ceramic matrix at the macroscale when individually, intimately and uniformly dispersed? If so, how? Also, what is the effect of CNT concentration in such a defect-free composite system? Here, we briefly review the recent studies addressing the above fundamental questions. In particular, we discuss the new

  11. Carbon–ceramic composites for enzyme immobilization

    OpenAIRE

    Lathouder, Karen de; Lozano Castelló, Dolores; Linares Solano, Ángel; Wallin, Sten A.; Kapteijn, Freek; Moulijn, Jacob

    2006-01-01

    Tunable carbon nanofiber-coated monoliths as carriers for enzyme adsorption are presented. Carbon-nanofibers (CNFs) were grown on monoliths with different microstructure. ‘‘Classical’’ cordierite monoliths were compared to novel acicular mullite (ACM) monoliths, with a more open wall structure. This open structure allows for a higher CNF-loading without affecting the open structure of the monoliths. The composites were used as a carrier for lactase from Aspergillus oryzae. ACM monoli...

  12. Mechanical behavior of ceramic composite hot-gas filters after exposure to severe environments

    Energy Technology Data Exchange (ETDEWEB)

    Pysher, D.J.; Weaver, B.L.; Smith, R.G. [Ceramic Technology Center, St. Paul, MN (United States)] [and others

    1995-08-01

    A novel type of hot-gas filter based on a ceramic fiber reinforced ceramic matrix has been developed, as reported at previous Fossil Energy Materials Conferences, through research activities at Oak Ridge National Laboratory (ORNL) and at the 3M Company. Simulated testing has been done at the Westinghouse Science and Technology Center. This filter technology has been extended to full size, 60 mm OD by 1.5 meter long candle filters and a commercially viable process for producing the filters has been developed filters are undergoing testing and demonstration use throughout the world for applications in pressurized fluidized-bed combustion (PFBC) and integrated gasification combined cycle (IGCC) plants. Demonstration tests of this ceramic composite filter along with other filters are in progress at the Tidd PFBC plant Mechanical tests were performed on the 3 M brand Ceramic Composite Candle Filter after exposure to various corrosive environments in order to assess its ability to function as a hot gas filter in coal-fired applications. Due to the different construction of ceramic composite filters and the thin composite wall versus the typical thick-walled monolithic filter, standard mechanical property tests had to be refined or modified to accurately determine the filters properties. These tests and filter property results will be described Longitudinal tensile and diametral O-ring compression tests were performed on as-produced candle filters as well as on filters which had been exposed to various environments. The exposures were for 1000 hrs at 850{degrees}C in wet air, in wet air containing Na{sub 2}CO{sub 3}, and in wet air containing NaCl. In addition, a filter which bad been coated with ash (Old Grimethorpe) was exposed to wet air at 850{degrees}C for 1000 hours.

  13. The possibility of giant dielectric materials for multilayer ceramic capacitors

    OpenAIRE

    Ishii, Tatsuya; Endo, Makoto; Masuda, Kenichiro; Ishida, Keisuke

    2013-01-01

    There have been numerous reports on discovery of giant dielectric permittivity materials called internal barrier layer capacitor in the recent years. We took particular note of one of such materials, i.e., BaTiO3 with SiO2 coating. It shows expressions of giant electric permittivity when processed by spark plasma sintering. So we evaluated various electrical characteristics of this material to find out whether it is applicable to multilayer ceramic capacitors. Our evaluation revealed that the...

  14. Ceramic material which absorbs neutrons and its uses

    International Nuclear Information System (INIS)

    A ceramic material, which absorbs thermal and epithermal neutrons even at high temperatures, consists of a basic material absorbing neutrons and 5 to 50% by weight relative to the total weight of the material of at least one of the hydrides of zirconium, yttrium and/or at least one of the rare earth elements, and possibly a binder, and the usual fillers and auxiliaries. (orig.)

  15. Thermal/chemical degradation of ceramic cross-flow filter materials

    Energy Technology Data Exchange (ETDEWEB)

    Alvin, M.A.; Lane, J.E.; Lippert, T.E.

    1989-11-01

    This report summarizes the 14-month, Phase 1 effort conducted by Westinghouse on the Thermal/Chemical Degradation of Ceramic Cross-Flow Filter Materials program. In Phase 1 expected filter process conditions were identified for a fixed-bed, fluid-bed, and entrained-bed gasification, direct coal fired turbine, and pressurized fluidized-bed combustion system. Ceramic cross-flow filter materials were also selected, procured, and subjected to chemical and physical characterization. The stability of each of the ceramic cross-flow materials was assessed in terms of potential reactions or phase change as a result of process temperature, and effluent gas compositions containing alkali and fines. In addition chemical and physical characterization was conducted on cross-flow filters that were exposed to the METC fluid-bed gasifier and the New York University pressurized fluidized-bed combustor. Long-term high temperature degradation mechanisms were proposed for each ceramic cross-flow material at process operating conditions. An experimental bench-scale test program is recommended to be conducted in Phase 2, generating data that support the proposed cross-flow filter material thermal/chemical degradation mechanisms. Papers on the individual subtasks have been processed separately for inclusion on the data base.

  16. BN interphase in composite materials with nicalon Si-C-O fibers and with vitro ceramic matrix of MAS type; L`interphase BN dans les materiaux composites a fibres Si-C-O nicalon et a matrice vitroceramique de type MAS

    Energy Technology Data Exchange (ETDEWEB)

    Ricca, N.

    1994-03-14

    BN has been suggested as an interphase in silica-based glass-ceramic matrix composites with a view to use these materials in oxidizing atmospheres at medium or high temperatures. The matrix had a boron-doped MAS (MgO-Al{sub 2}O{sub 3}-SiO{sub 2}) composition and was prepared from an hydrosol precursor. Pseudo-ID composites were prepared according to a sol impregnations/calcination/hot-pressing route. Chemical and microstructural characterizations of the fiber/matrix interfacial area were conducted by mean of TEM/EELS and AES analyses. The efficiency of BN as a coupling interphase for this particular composite system was successfully demonstrated through tensile tests performed on either as-processed or aged specimens (100 hours at 1000 deg C in air or under argon). In addition, composites maintained in air at 600 deg C, 800 deg C and 900 deg C while simultaneously loaded did not fail after 150 hours or more. Thus, a BN interphase appeared to be compatible with an oxidizing environment (i.e. the oxide matrix and/or air from 600 to 1000 deg C) and should therefore successfully replace the usual carbon interphase at least for use at medium temperatures. (author)

  17. Composite materials design and applications

    CERN Document Server

    Gay, Daniel; Tsai, Stephen W

    2002-01-01

    PART ONE. PRINCIPLES OF CONSTRUCTIONCOMPOSITE MATERIALS, INTEREST AND PROPERTIESWhat is Composite Material Fibers and MatrixWhat can be Made Using Composite Materials?Typical Examples of Interest on the Use of Composite MaterialsExamples on Replacing Conventional Solutions with CompositesPrincipal Physical PropertiesFABRICATION PROCESSESMolding ProcessesOther Forming ProcessesPractical Hints in the Manufacturing ProcessesPLY PROPERTIESIsotropy and AnisotropyCharacteristics of the Reinforcement-Matrix MixtureUnidirectional PlyWoven FabricsMats and Reinforced MatricesMultidimensional FabricsMetal Matrix CompositesTestsSANDWICH STRUCTURES:What is a Sandwich Structure?Simplified FlexureA Few Special AspectsFabrication and Design ProblemsNondestructive Quality ControlCONCEPTION AND DESIGNDesign of a Composite PieceThe LaminateFailure of LaminatesSizing of LaminatesJOINING AND ASSEMBLYRiveting and BoltingBondingInsertsCOMPOSITE MATERIALS AND AEROSPACE CONSTRUCTIONAircraftHelicoptersPropeller Blades for AirplanesTur...

  18. The Influence of the Particle Size on the Adhesion Between Ceramic Particles and Metal Matrix in MMC Composites

    Science.gov (United States)

    Jarzabek, Dariusz M.; Chmielewski, Marcin; Dulnik, Judyta; Strojny-Nedza, Agata

    2016-05-01

    This study investigated the influence of the particle size on the adhesion force between ceramic particles and metal matrix in ceramic-reinforced metal matrix composites. The Cu-Al2O3 composites with 5 vol.% of ceramic phase were prepared by a powder metallurgy process. Alumina oxide powder as an electrocorundum (Al2O3) powder with different particle sizes, i.e., fine powder materials and carried out the experiments with the use of the self-made tensile tester. We have observed that the interface strength is higher for the sample with coarse particles and is equal to 74 ± 4 MPa and it is equal to 68 ± 3 MPa for the sample with fine ceramic particles.

  19. Numerical study of internal load transfer in metal/ceramic composites based on freeze-cast ceramic preforms and experimental validation

    International Nuclear Information System (INIS)

    The elastic–plastic deformation and internal load transfer in metal/ceramic composites are studied in this work both numerically and experimentally. The composite was fabricated by squeeze-casting AlSi12 melt in an open porous preform made by freeze-casting and drying of alumina suspension. Such composites exhibit a complex microstructure composed of lamellar domains. Single-domain samples were extracted from bulk material. Uniaxial compression tests were carried out parallel to the direction of the alternating metallic alloy and ceramic lamellae in the plane normal to the direction of freeze-casting. This loading mode is selected as highest load transfer occurs when loaded along the ceramic lamellae. Numerical modeling was done using the finite element method using quasi-3D microstructure based on metallographic 2D section and a modified Voigt homogenization technique assuming plastic behavior of the metallic alloy, absence of any damage and ideal interface between the phases. Internal load transfer mechanism was predicted for composites with different ceramic volume fractions. Results show that at any applied stress, as the ceramic content increases, the phase stress in alumina along the loading direction continuously decreases. Experimental validation of the numerical results is carried out by in-situ compression test along with energy dispersive synchrotron X-ray diffraction in one sample with 41 vol% ceramic. Results show that both the numerical techniques yield similar results, which match well with the experimental measurements. The ratio of the phase stress to the applied stress in alumina reaches a highest value between 2 and 2.5 up to a compressive stress of about 300 MPa. At higher applied stresses both the experimentally determined lattice microstrain and the phase stress along the loading direction in alumina decrease due to the initiation of possible damage. This study shows that the applied economic and more flexible homogenization technique is a

  20. Processing and properties of ceramic matrix-polymer composites for dental applications

    Science.gov (United States)

    Huang, Hsuan Yao

    The basic composite structure of natural hard tissue was used to guide the design and processing of dental restorative materials. The design incorporates the methodology of using inorganic minerals as the main structural phase reinforced with a more ductile but tougher organic phase. Ceramic-polymer composites were prepared by slip casting a porous ceramic structure, heating and chemical treating the porous preform, infiltrating with monomer and then curing. The three factors that determined the mechanical properties of alumina-polymer composites were the type of polymer used, the method of silane treatments, and the type of bond between particles in the porous preforms. Without the use of silane coupling agents, the composites were measured to have a lower strength. The composite with a more "flexible" porous alumina network had a greater ability to plastically dissipate the energy of propagating cracks. However, the aggressive nature of the alumina particles on opposing enamel requires that these alumina-polymer composites have a wear compatible coating for practical application. A route to dense bioactive apatite wollastonite glass ceramics (AWGC)-polymer composites was developed. The problems associated with glass dissolution into the aqueous medium for slip casting were overcome with the use of silane. The role of heating rate and development of ceramic compact microstructure on composite properties was explored. In general, if isothermal heating was not applied, decreasing heating rate increased glass crystallinity and particle-particle fusion, but decreased pore volume. Also composite strength and fracture toughness decreased while modulus and hardness increased with decreasing heating rate. If isothermal heating was applied, glass crystallinity, pore content, and composite mechanical properties showed relatively little change regardless of the initial heating rate. The potential of AWGC-polymer composites for dental and implant applications was explored

  1. Composite materials derived from geopolymers reinforced by polymer fibers

    Czech Academy of Sciences Publication Activity Database

    Benešová, Lenka

    Novi Sad : Faculty of Technology, University of Novi Sad, 2009 - (Srdic, V.; Ranogajec, J.). s. 78 ISBN 978-86-80995-77-9. [Students Meeting, Processing and Application of Ceramics . 02.12.2009-05.12.2009, Novi Sad] Institutional research plan: CEZ:AV0Z40500505 Keywords : geopolymers * short polymer fibers * composite material Subject RIV: CF - Physical ; Theoretical Chemistry

  2. SHS/PHIP of ceramic composites using ilmenite concentrate

    Energy Technology Data Exchange (ETDEWEB)

    Kholghy, M. [Yerevan State University and Isfahan University of Technology, Dept. of Materials Eng (Iran, Islamic Republic of); Kharatyan, S. [Yerevan State University, Yerevan, A. Manukyan str. 1, AM-0025 (Armenia); Edris, H., E-mail: h-edris@cc.iut.ac.i [Isfahan University of Technology, Dept. of Materials Eng. Isfahan, 8415683111 (Iran, Islamic Republic of)

    2010-07-23

    Self-propagating high-temperature synthesis (SHS) process in the mixture of ilmenite, boron carbide and aluminum combined with a pseudo hot isostatic pressing (PHIP) is used in this research to produce a compact multi-ceramic composite Al{sub 2}O{sub 3}/TiB{sub 2}/TiC with Fe as a binder. Several tests were performed to identify the optimum partial weight percent of the ilmenite, boron carbide and aluminum to produce a suitable amount of each components of the product. On the other hand, a number of tests were performed to measure the delay time, optimum compaction time and optimum compaction force to produce a compact high toughness samples. The results of phase analysis using XRD tests and microstructure using SEM and EDS show that the product is a multi-ceramic composite of the Al{sub 2}O{sub 3}/TiB{sub 2}/TiC with Fe as a binder. It was shown that there are no primary reactants in the product. In this work, the combustion characteristics (combustion wave propagation velocity and temperature) of the process, as well as density and hardness of the combustion product were measured. The fracture toughness of the product was measured using Vickers indenter and Brazilian test. This shows that the samples have a high toughness in comparison to conventional ceramics.

  3. Composite material and method for production of improved composite material

    Science.gov (United States)

    Farley, Gary L. (Inventor)

    1996-01-01

    A laminated composite material with improved interlaminar strength and damage tolerance having short rods distributed evenly throughout the composite material perpendicular to the laminae. Each rod is shorter than the thickness of the finished laminate, but several times as long as the thickness of each lamina. The laminate is made by inserting short rods in layers of prepreg material, and then stacking and curing prepreg material with rods inserted therethrough.

  4. Influence of Inclusion Shape on Thermoelasto-Plastic Optimun Design of Ceramic Metal Functionally Graded Materials

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A nonlinear finite element method is applied to observe how inclusion shape influence the thermal response of a ceramic-metal functionally graded material (FGM).The elastic and plastic behaviors of the layers which are two-phase isotropic composites consisting of randomly oriented elastic spheroidal inclusions and a ductile matrix are predicted by a mean field method.The prediction results show that inclusion shape has remarkable influence on the overall behavior of the composite.The consequences of the thermal response analysis of the FGM are that the response is dependent on inclusion shape and its composition profile cooperatively and that the plastic behavior of each layer should be taken into account in optimum design of a ceramic-metal FGM.

  5. The Uniaxial Tensile Response of Porous and Microcracked Ceramic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Amit [ORNL; Shyam, Amit [ORNL; Watkins, Thomas R [ORNL; Lara-Curzio, Edgar [ORNL; Lara-Curzio, Edgar [ORNL; Stafford, Randall [Cummins, Inc; Hemker, Kevin J [Johns Hopkins University

    2014-01-01

    The uniaxial tensile stress-strain behavior of three porous ceramic materials was determined at ambient conditions. Test specimens in the form of thin beams were obtained from the walls of diesel particulate filter honeycombs and tested using a microtesting system. A digital image correlation technique was used to obtain full-field 2D in-plane surface displacement maps during tensile loading, and in turn, the 2D strains obtained from displacement fields were used to determine the Secant modulus, Young s modulus and initial Poisson s ratio of the three porous ceramic materials. Successive unloading-reloading experiments were performed at different levels of stress to decouple the linear elastic, anelastic and inelastic response in these materials. It was found that the stress-strain response of these materials was non-linear and that the degree of nonlinearity is related to the initial microcrack density and evolution of damage in the material.

  6. Comparative study on in vivo response of porous calcium carbonate composite ceramic and biphasic calcium phosphate ceramic.

    Science.gov (United States)

    He, Fupo; Ren, Weiwei; Tian, Xiumei; Liu, Wei; Wu, Shanghua; Chen, Xiaoming

    2016-07-01

    In a previous study, robust calcium carbonate composite ceramics (CC/PG) were prepared by using phosphate-based glass (PG) as an additive, which showed good cell response. In the present study the in vivo response of porous CC/PG was compared to that of porous biphasic calcium phosphate ceramics (BCP), using a rabbit femoral critical-size grafting model. The materials degradation and bone formation processes were evaluated by general observation, X-ray radiography, micro-computed tomography, and histological examination. The results demonstrated excellent biocompatibility and osteoconductivity, and progressive degradation of CC/PG and BCP. Although the in vitro degradation rate of CC/PG was distinctly faster than that of BCP, at 4week post-implantation, the bone generation and material degradation of CC/PG were less than those of BCP. Nevertheless, at postoperative week 8, the increment of bone formation and material degradation of CC/PG was pronouncedly larger than that of BCP. These results show that CC/PG is a potential resorbable bone graft aside from the traditional synthetic ones. PMID:27127035

  7. Neural network applied to elemental archaeological Marajoara ceramic compositions

    International Nuclear Information System (INIS)

    In the last decades several analytical techniques have been used in archaeological ceramics studies. However, instrumental neutron activation analysis, INAA, employing gamma-ray spectrometry seems to be the most suitable technique because it is a simple analytical method in its purely instrumental form. The purpose of this work was to determine the concentration of Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb, and Zn in 160 original marajoara ceramic fragments by INAA. Marajoara ceramics culture was sophisticated and well developed. This culture reached its peak during the V and XIV centuries in Marajo Island located on the Amazon River delta area in Brazil. The purpose of the quantitative data was to identify compositionally homogeneous groups within the database. Having this in mind, the data set was first converted to base-10 logarithms to compensate for the differences in magnitude between major elements and trace elements, and also to yield a closer to normal distribution for several trace elements. After that, the data were analyzed using the Mahalanobis distance and using the lambda Wilks as critical value to identify the outliers. The similarities among the samples were studied by means of cluster analysis, principal components analysis and discriminant analysis. Additional confirmation of these groups was made by using elemental concentration bivariate plots. The results showed that there were two very well defined groups in the data set. In addition, the database was studied using artificial neural network with unsupervised learning strategy known as self-organizing maps to classify the marajoara ceramics. The experiments carried out showed that self-organizing maps artificial neural network is capable of discriminating ceramic fragments like multivariate statistical methods, and, again the results showed that the database was formed by two groups. (author)

  8. Neural network applied to elemental archaeological Marajoara ceramic compositions

    Energy Technology Data Exchange (ETDEWEB)

    Toyota, Rosimeiri G.; Munita, Casimiro S., E-mail: rosimeiritoy@yahoo.com.b, E-mail: camunita@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Boscarioli, Clodis, E-mail: boscarioli@gmail.co [Universidade Estadual do Oeste do Parana, Cascavel, PR (Brazil). Centro de Ciencias Exatas e Tecnologicas. Colegiado de Informatica; Hernandez, Emilio D.M., E-mail: boscarioli@gmail.co [Universidade de Sao Paulo (USP), SP (Brazil). Escola Politecnica; Neves, Eduardo G.; Demartini, Celia C., E-mail: eduardo@pq.cnpq.b [Museu de Arqueologia e Etnologia (MAE/USP), Sao Paulo, SP (Brazil)

    2009-07-01

    In the last decades several analytical techniques have been used in archaeological ceramics studies. However, instrumental neutron activation analysis, INAA, employing gamma-ray spectrometry seems to be the most suitable technique because it is a simple analytical method in its purely instrumental form. The purpose of this work was to determine the concentration of Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb, and Zn in 160 original marajoara ceramic fragments by INAA. Marajoara ceramics culture was sophisticated and well developed. This culture reached its peak during the V and XIV centuries in Marajo Island located on the Amazon River delta area in Brazil. The purpose of the quantitative data was to identify compositionally homogeneous groups within the database. Having this in mind, the data set was first converted to base-10 logarithms to compensate for the differences in magnitude between major elements and trace elements, and also to yield a closer to normal distribution for several trace elements. After that, the data were analyzed using the Mahalanobis distance and using the lambda Wilks as critical value to identify the outliers. The similarities among the samples were studied by means of cluster analysis, principal components analysis and discriminant analysis. Additional confirmation of these groups was made by using elemental concentration bivariate plots. The results showed that there were two very well defined groups in the data set. In addition, the database was studied using artificial neural network with unsupervised learning strategy known as self-organizing maps to classify the marajoara ceramics. The experiments carried out showed that self-organizing maps artificial neural network is capable of discriminating ceramic fragments like multivariate statistical methods, and, again the results showed that the database was formed by two groups. (author)

  9. Ceramic waste materials – source for the geopolymer technology

    Czech Academy of Sciences Publication Activity Database

    Perná, Ivana; Hanzlíček, Tomáš; Straka, Pavel; Steinerová, Michaela

    Hammamed: SDST, 2008 - (Darve, F.), s. 735-740 ISBN 978-9973-0-0299-0. [Second Euro Mediterranean Symposium in Advances on Geomaterials and Structures. Hammamet (TN), 05.05.2008-08.05.2008] Institutional research plan: CEZ:AV0Z30460519 Keywords : ceramic waste material * white waters * geopolymer Subject RIV: DM - Solid Waste and Recycling

  10. Polymer derived ceramic composites as environmental barrier coatings on steel

    Science.gov (United States)

    Torrey, Jessica D.

    Polymer derived ceramics have shown promise as a novel way to process low-dimensional ceramics such as fibers and coatings. They offer advantages over traditional ceramic processing routes including lower pyrolysis temperatures and the ability to employ polymeric processing techniques. The main drawback to preceramic polymers is that they undergo a shrinkage during pyrolysis that can be greater than 50-volume%. One way to overcome this shrinkage is to add filler particles, usually elemental or binary metals, which will expand upon reaction with the pyrolysis atmosphere, thereby compensating for the shrinkage of the polymer. The aim of this study is to develop a polymer derived ceramic composite coating on steel as a barrier to oxidation and carburization, while concurrently gaining insight as to the fundamental mechanisms for compositional and microstructural evolution within the system. A systematic approach to selecting the preceramic polymer and expansion agents was taken. Six commercially available poly(silsesquioxane) polymers and a polysiloxane were studied. Several metals and an intermetallic were considered as potential expansion agents. The most desirable polymer/expansion agent combination was achieved with poly(hydridomethylsiloxane) as the matrix and titanium disilicide as the filler. Processing parameters have been optimized and a relationship derived to predict final coating thickness based on slurry viscosity and dip coating withdrawal speed. Microstructural analysis reveals an amorphous composite coating of oxidized filler particles in a silica matrix. A diffusion layer is visible at the coating-steel interface, indicating good bonding. The optimized coatings are ˜18mum thick, have some residual porosity and a density of 2.57g/cm3. A systematic study of the phase transformations and microstructural changes in the coating and its components during pyrolysis in air is also presented. The system evolves from a polymer filled with a binary metal at

  11. Electrostatic Assembly Preparation of High-Toughness Zirconium Diboride-Based Ceramic Composites with Enhanced Thermal Shock Resistance Performance.

    Science.gov (United States)

    Zhang, Baoxi; Zhang, Xinghong; Hong, Changqing; Qiu, Yunfeng; Zhang, Jia; Han, Jiecai; Hu, PingAn

    2016-05-11

    The central problem of using ceramic as a structural material is its brittleness, which associated with rigid covalent or ionic bonds. Whiskers or fibers of strong ceramics such as silicon carbide (SiC) or silicon nitride (Si3N4) are widely embedded in a ceramic matrix to improve the strength and toughness. The incorporation of these insulating fillers can impede the thermal flow in ceramic matrix, thus decrease its thermal shock resistance that is required in some practical applications. Here we demonstrate that the toughness and thermal shock resistance of zirconium diboride (ZrB2)/SiC composites can be improved simultaneously by introducing graphene into composites via electrostatic assembly and subsequent sintering treatment. The incorporated graphene creates weak interfaces of grain boundaries (GBs) and optimal thermal conductance paths inside composites. In comparison to pristine ZrB2-SiC composites, the toughness of (2.0%) ZrB2-SiC/graphene composites exhibited a 61% increasing (from 4.3 to 6.93 MPa·m(1/2)) after spark plasma sintering (SPS); the retained strength after thermal shock increased as high as 74.8% at 400 °C and 304.4% at 500 °C. Present work presents an important guideline for producing high-toughness ceramic-based composites with enhanced thermal shock properties. PMID:27031536

  12. Dielectric properties of BST/MZO ceramic composites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Ba0.6Sr0.4TiO3/Mg1-xZnxO (MZO, x = 0, 0.05, 0.10, 0.15 and 0.20) ceramic composites were prepared by traditional ceramic processing. The crystal structure, fracture surface morphology, and dielectric properties were investigated. The samples with x = 0, 0.05 and 0.10 exhibited favorable sintering behavior, and homogeneous diphase microstructure was obtained. Nevertheless, the microstructure of the samples with x = 0.15 and 0.20 was inhomogeneous and abnormal grain growth could be observed, and the abnormal grain growth induced the degradation of dielectric strength. The sample with x = 0.10 has relatively low dielectric loss (1.26×10-3) and the optimal FOM value (about 174).

  13. Radioactive waste immobilization using ion-exchange materials which form glass-ceramics

    International Nuclear Information System (INIS)

    This invention provides a process for the production of a glass-ceramic composite product in which the crystalline phase is thermodynamically stable and compatible with the host rock. The process comprises: (a) passing liquid radioactive waste materials through an inorganic ion exchange medium; (b) heating the ion exchange materials with sufficient glass-forming materials to form a melt; (c) cooling the melt to form a glass; and (d) heat treating the glass to crystallize sphene crystallites in a protective glassy matrix that contains the radioactive materials. There is also provided a cartridge containing the ion exchange medium

  14. Neutron irradiation of candidate ceramic breeder materials of fusion reactors

    International Nuclear Information System (INIS)

    In the context of the European programs for the future fusion reactors, the Process Chemistry Department of ENEA, Casaccia Center (Rome), has been involved in preparing ceramic blanket materials as tritium breeders; a special consideration has been addressed to the nuclear characterization of LiAlO2 and Li2ZrO3. In this paper are reported neutron irradiation of ceramic specimens in TRIGA reactor and γ-spectrometric measurements for INAA purposes; and isothermal annealing of the irradiated samples and tritium extraction, by using an 'out of pile' system. (author) 3 refs.; 4 figs.; 4 tabs

  15. Layered ceramic composites via control of electrophoretic deposition kinetics

    Czech Academy of Sciences Publication Activity Database

    Hadraba, Hynek; Drdlík, D.; Chlup, Zdeněk; Maca, K.; Dlouhý, Ivo; Cihlář, J.

    2013-01-01

    Roč. 33, č. 12 (2013), s. 2305-2312. ISSN 0955-2219 R&D Projects: GA ČR(CZ) GAP108/11/1644; GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Alumina * Zirconia * Laminates * Electrophoretic deposition Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.307, year: 2013

  16. Resin composite or ceramic inlays/onlays in posterior permanent teeth : a review of the literature

    OpenAIRE

    Breistrand, Joakim Lund; Juliussen, Øyvind

    2011-01-01

    Objective: To compare the clinical survival and long-term costs of extensive composite restorations to ceramic inlays and onlays. The hypothesis was that ceramic inlays and onlays can be more tooth substance saving and long-term economic for the patient than composite restorations. Methods: The dental literature, predominantly since 1990, was reviewed for prospective clinical studies of longevity of ceramic inlays/onlays and direct composite restorations in permanent posterior teeth. Only ...

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

    International Nuclear Information System (INIS)

    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

  18. Glass-ceramics: A class of nanostructured materials for photonics

    International Nuclear Information System (INIS)

    Glass-ceramics (GCs) are constituted by nanometer–to–micron-sized crystals embedded in a glass matrix; usually, their structural or functional elements (clusters, crystallites or molecules) have dimensions in the 1 to 100 nm range. As the name says, GCs must be considered an intermediate material between inorganic glasses and ceramics; in most cases the crystallinity is between 30 and 50%. GCs share many properties with both glasses and ceramics, offering low defects, extra hardness, high thermal shock resistance (typical of ceramics) together with the ease of fabrication and moulding (typical of glasses). The embedded crystalline phase, however, can enhance the existing properties of the matrix glass or lead to entirely new properties. GCs are produced by controlled crystallization of certain glasses, generally induced by nucleating additives; they may result opaque or transparent. Transparent GCs are now gaining a competitive advantage with respect to amorphous glasses and, sometimes, to crystals too. The aim of the present paper is to introduce the basic characteristics of transparent glass-ceramics, with particular attention to the relationship between structure and transparency and to the mechanism of crystallization, which may also be induced by selective laser treatments. Their applications to the development of guided-wave structures are also briefly described.

  19. Glass-ceramics: A class of nanostructured materials for photonics

    Science.gov (United States)

    de Pablos-Martin, A.; Ferrari, M.; Pascual, M. J.; Righini, G. C.

    2015-07-01

    Glass-ceramics (GCs) are constituted by nanometer-to-micron-sized crystals embedded in a glass matrix; usually, their structural or functional elements (clusters, crystallites or molecules) have dimensions in the 1 to 100nm range. As the name says, GCs must be considered an intermediate material between inorganic glasses and ceramics; in most cases the crystallinity is between 30 and 50%. GCs share many properties with both glasses and ceramics, offering low defects, extra hardness, high thermal shock resistance (typical of ceramics) together with the ease of fabrication and moulding (typical of glasses). The embedded crystalline phase, however, can enhance the existing properties of the matrix glass or lead to entirely new properties. GCs are produced by controlled crystallization of certain glasses, generally induced by nucleating additives; they may result opaque or transparent. Transparent GCs are now gaining a competitive advantage with respect to amorphous glasses and, sometimes, to crystals too. The aim of the present paper is to introduce the basic characteristics of transparent glass-ceramics, with particular attention to the relationship between structure and transparency and to the mechanism of crystallization, which may also be induced by selective laser treatments. Their applications to the development of guided-wave structures are also briefly described.

  20. Colloidal processing of Fe-based metal ceramic composites with high content of ceramic reinforcement

    International Nuclear Information System (INIS)

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition. (Author)

  1. Characterization of Ceramic Material Produced From a Cold Crucible Induction Melter Test

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-30

    This report summarizes the results from characterization of samples from a melt processed surrogate ceramic waste form. Completed in October of 2014, the first scaled proof of principle cold crucible induction melter (CCIM) test was conducted to process a Fe-hollandite-rich titanate ceramic for treatment of high level nuclear waste. X-ray diffraction, electron microscopy, inductively coupled plasma-atomic emission spectroscopy (and inductively coupled plasma-mass spectroscopy for Cs), and product consistency tests were used to characterize the CCIM material produced. Core samples at various radial locations from the center of the CCIM were taken. These samples were also sectioned and analyzed vertically. Together, the various samples were intended to provide an indication of the homogeneity throughout the CCIM with respect to phase assemblage, chemical composition, and chemical durability. Characterization analyses confirmed that a crystalline ceramic with desirable phase assemblage was produced from a melt using a CCIM. Hollandite and zirconolite were identified in addition to possible highly-substituted pyrochlore and perovskite. Minor phases rich in Fe, Al, or Cs were also identified. Remarkably only minor differences were observed vertically or radially in the CCIM material with respect to chemical composition, phase assemblage, and durability. This recent CCIM test and the resulting characterization in conjunction with demonstrated compositional improvements support continuation of CCIM testing with an improved feed composition and improved melter system.

  2. Application of ceramic short fiber reinforced Al alloy matrix composite on piston for internal combustion engines

    Directory of Open Access Journals (Sweden)

    Wu Shenqing

    2010-11-01

    Full Text Available The preparation and properties of ceramic short fiber reinforced Al-Si alloy matrix composite and it’s application on the piston for internal combustion engines are presented. Alumina or aluminosilicate fibers reinforced Al-Si alloy matrix composite has more excellent synthetical properties at elevated temperature than the matrix alloys. A partially reinforced Al-Si alloy matrix composite piston produced by squeeze casting technique has a firm interface between reinforced and unreinforced areas, low reject rate and good technical tolerance. As a new kind of piston material, it has been used for mass production of about 400,000 pieces of automobile engines piston. China has become one of a few countries in which aluminum alloy matrix composite materials have been used in automobile industry and attained industrialization.

  3. Durable, High Thermal Conductivity Melt Infiltrated Ceramic Composites for Turbine Engine Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Durable, creep-resistant ceramic composites are necessary to meet the increased operating temperatures targeted for advanced turbine engines. Higher operating...

  4. Advanced SiC/SiC Ceramic Composites For Gas-Turbine Engine Components

    Science.gov (United States)

    Yun, H. M.; DiCarlo, J. A.; Easler, T. E.

    2004-01-01

    NASA Glenn Research Center (GRC) is developing a variety of advanced SiC/SiC ceramic composite (ASC) systems that allow these materials to operate for hundreds of hours under stress in air at temperatures approaching 2700 F. These SiC/SiC composite systems are lightweight (approximately 30% metal density) and, in comparison to monolithic ceramics and carbon fiber-reinforced ceramic composites, are able to reliably retain their structural properties for long times under aggressive gas-turbine engine environments. The key for the ASC systems is related first to the NASA development of the Sylramic-iBN Sic fiber, which displays higher thermal stability than any other SiC- based ceramic fibers and possesses an in-situ grown BN surface layer for higher environmental durability. This fiber is simply derived from Sylramic Sic fiber type that is currently produced at ATK COI Ceramics (COIC). Further capability is then derived by using chemical vapor infiltration (CVI) and/or polymer infiltration and pyrolysis (PIP) to form a Sic-based matrix with high creep and rupture resistance as well as high thermal conductivity. The objectives of this study were (1) to optimize the constituents and processing parameters for a Sylramic-iBN fiber reinforced ceramic composite system in which the Sic-based matrix is formed at COIC almost entirely by PIP (full PIP approach), (2) to evaluate the properties of this system in comparison to other 2700 F Sylramic-iBN systems in which the matrix is formed by full CVI and CVI + PIP, and (3) to examine the pros and cons of the full PIP approach for fabricating hot-section engine components. A key goal is the development of a composite system with low porosity, thereby providing high modulus, high matrix cracking strength, high interlaminar strength, and high thermal conductivity, a major property requirement for engine components that will experience high thermal gradients during service. Other key composite property goals are demonstration at

  5. Study of Using Certain Composition of Bismuth Silicate Glass and Glass Ceramic for Gamma Radiation Processing

    International Nuclear Information System (INIS)

    Bismuth silicate glass with composition 20, 80 wt. % respectively was prepared. Electron Paramagnetic Resonance (EPR) measurements show that this glass has a very good stability when exposed to γ irradiation, which encourage the assumption of using it as a shielding material. Many properties should be investigated to fulfill this application. Study of density and molar volume to understand the structural properties, also the mechanical properties are verified by measuring microhardness, while the chemical resistance was identified by testing its durability in a base solution. The EPR results were supported by measuring electrical conductivity of the glass samples at different temperatures ranging from 295 - 553 K, which proved that this glass has very low conductivity even at high temperatures. The corresponding glass ceramic was prepared by means of heat treatment, and the formed phases were demonstrated by means of X-ray diffraction (XRD). Also the probability of using this glass ceramic as a shielding material was investigated

  6. Melt Infiltrated Ceramic Composites (Hipercomp) for Gas Turbine Engine Applications

    Energy Technology Data Exchange (ETDEWEB)

    Gregory Corman; Krishan Luthra

    2005-09-30

    This report covers work performed under the Continuous Fiber Ceramic Composites (CFCC) program by GE Global Research and its partners from 1994 through 2005. The processing of prepreg-derived, melt infiltrated (MI) composite systems based on monofilament and multifilament tow SiC fibers is described. Extensive mechanical and environmental exposure characterizations were performed on these systems, as well as on competing Ceramic Matrix Composite (CMC) systems. Although current monofilament SiC fibers have inherent oxidative stability limitations due to their carbon surface coatings, the MI CMC system based on multifilament tow (Hi-Nicalon ) proved to have excellent mechanical, thermal and time-dependent properties. The materials database generated from the material testing was used to design turbine hot gas path components, namely the shroud and combustor liner, utilizing the CMC materials. The feasibility of using such MI CMC materials in gas turbine engines was demonstrated via combustion rig testing of turbine shrouds and combustor liners, and through field engine tests of shrouds in a 2MW engine for >1000 hours. A unique combustion test facility was also developed that allowed coupons of the CMC materials to be exposed to high-pressure, high-velocity combustion gas environments for times up to {approx}4000 hours.

  7. Actively Cooled Ceramic Composite Nozzle Material Project

    Data.gov (United States)

    National Aeronautics and Space Administration — For Next Generation Launch Vehicles (NGLV), Either a Rocket-based or Turbine-based Combined Cycle (RBCC or TBCC) engine will power the Next Generation Launch...

  8. Composite Materials in Overhead Lines

    DEFF Research Database (Denmark)

    Sørensen, Thomas Kjærsgaard; Holbøll, Joachim

    2009-01-01

    The use of composite materials, e.g. fibreglass materials, in overhead transmission line systems is nothing new. Composite based insulators have been applied to transmission lines for over 30 years, mainly as suspension and post insulators and often as an option for special applications. Also...... respect to solved and persisting known failures/problems of both mechanical and electrical nature. Major challenges related to extensive use of composite materials in an overhead line system are identified, as are possible benefits - both when using standard as well as customised composite components, e...... towers and recently conductors based on composite materials are available at transmission levels. In this paper it is investigated which composite based solutions are available in connection with complete overhead line systems including insulators, towers and conductors. The components are reviewed with...

  9. Reinforcing and toughening alumina/titania ceramic composites with nano-dopants from nanostructured composite powders

    International Nuclear Information System (INIS)

    Nanostructured alumina/titania composite powders were prepared using nanosized alumina and titania doped with nanosized zirconia and ceria through ball-milling, spray drying and heat treating. The nanostructured reconstituted powders were then cool isostatic pressed and pressureless sintered into bulk ceramic composites. The phase constitution and microstructures of as-prepared ceramic composites were characterized by using X-ray diffractometer and scanning electron microscope. The mechanical properties of the ceramic composites were evaluated by Vickers hardness test, flexural strength test and fracture toughness test. The effects of nano-dopants and sintering temperatures on the microstructures and mechanical properties of the composites were investigated. It was found that nano-dopants had the effects of lowering sintering temperature, accelerating densification, reinforcing and toughening the composites. The maximum flexural strength, fracture toughness and Vickers hardness of the composites with nano-dopants were 51, 20 and 56% higher than that of the composites without nano-dopants. The reinforcing and toughening mechanisms are discussed in detail.

  10. Does the bracket composition material influence initial biofilm formation?

    OpenAIRE

    Gustavo Antônio Martins Brandão; Antonio Carlos Pereira; Ana Maria Martins Brandão; Haroldo Amorim de Almeida; Rogério Heládio Lopes Motta

    2015-01-01

    Context: Orthodontic treatment has been reported to contribute to the development and accumulation of dental biofilm, which is commonly found on bracket and adjacent surfaces. Aims: The aim of this work is to test the hypothesis if there are differences in dental biofilm formation on the surface of orthodontic brackets according to the type of composition material. Subjects and Methods: Three bracket types (metallic, composite, and ceramic) had been evaluated. Subjects wore acrylic pa...

  11. Reuse of sugarcane bagasse ash (SCBA) to produce ceramic materials.

    Science.gov (United States)

    Souza, A E; Teixeira, S R; Santos, G T A; Costa, F B; Longo, E

    2011-10-01

    Sugarcane bagasse ash (SCBA) is a residue resulting from the burning of bagasse in boilers in the sugarcane/alcohol industry. SCBA has a very high silica concentration and contains aluminum, iron, alkalis and alkaline earth oxides in smaller amounts. In this work, the properties of sintered ceramic bodies were evaluated based on the concentration of SCBA, which replaced non-plastic material. The ash was mixed (up to 60 wt%) with a clayed raw material that is used to produce roof tiles. Prismatic probes were pressed and sintered at different temperatures (up to 1200 °C). Technological tests of ceramic probes showed that the addition of ash has little influence on the ceramic properties up to 1000 °C. X-ray diffraction and thermal analysis data showed that, above this temperature the ash participates in the sintering process and in the formation of new important phases. The results reported show that the reuse of SCBA in the ceramic industry is feasible. PMID:21733619

  12. Analytical Micromechanics Modeling Technique Developed for Ceramic Matrix Composites Analysis

    Science.gov (United States)

    Min, James B.

    2005-01-01

    Ceramic matrix composites (CMCs) promise many advantages for next-generation aerospace propulsion systems. Specifically, carbon-reinforced silicon carbide (C/SiC) CMCs enable higher operational temperatures and provide potential component weight savings by virtue of their high specific strength. These attributes may provide systemwide benefits. Higher operating temperatures lessen or eliminate the need for cooling, thereby reducing both fuel consumption and the complex hardware and plumbing required for heat management. This, in turn, lowers system weight, size, and complexity, while improving efficiency, reliability, and service life, resulting in overall lower operating costs.

  13. Analysis of Damage in a Ceramic Matrix Composite

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Talreja, Ramesh

    1993-01-01

    Mechanisms of damage and the associated mechanical response are stud ied for a unidirectionally fiber-reinforced ceramic matrix composite subjected to uniaxial tensile loading parallel to fibers. A multi-stage development of damage is identified, and for each stage the governing mechanisms are...... discussed. For distributed matrix micro cracking a continuum damage model is used as the basis for describing the associated stress-strain behavior. A simplified analysis of frictional sliding at the fiber/matrix inter face is made to elucidate its effect on the stress-strain response....

  14. Fabrication Routes for Continuous Fiber-Reinforced Ceramic Composites (CFCC)

    Science.gov (United States)

    DiCarlo, James A.; Bansal, Narottam P.

    1998-01-01

    The primary approaches used for fabrication of continuous fiber-reinforced ceramic composite (CFCC) components have been reviewed. The CFCC fabrication issues related to fiber, interface, and matrix have been analyzed. The capabilities, advantages and limitations of the five matrix-infiltration routes have been compared and discussed. Today, the best fabrication route for the CFCC end-user is not clear and compromises need to be made depending on the details of the CFCC application. However, with time, this problem should be reduced as research continues to develop advanced CFCC constituents and fabrication routes.

  15. Ultimate Tensile Strength as a Function of Test Rate for Various Ceramic Matrix Composites at Elevated Temperatures

    Science.gov (United States)

    Choi, Sung R.; Bansal, Narottam P.; Gyekenyesi, John P.

    2002-01-01

    Ultimate tensile strength of five different continuous fiber-reinforced ceramic composites, including SiC/BSAS (2D 2 types), SiC/MAS-5 (2D), SiC/SiC (2D enhanced), and C/SiC(2D) was determined as a function of test rate at I 100 to 1200 'C in air. All five composite materials exhibited a significant dependency of ultimate strength on test rate such that the ultimate strength decreased with decreasing test rate, similar to the behavior observed in many advanced monolithic ceramics at elevated temperatures. The application of the preloading technique as well as the prediction of life from one loading configuration (constant stress rate) to another (constant stress loading) for SiC/BSAS suggested that the overall macroscopic failure mechanism of the composites would be the one governed by a power-law type of damage evolution/accumulation, analogous to slow crack growth commonly observed in advanced monolithic ceramics.

  16. FEAMAC/CARES Stochastic-Strength-Based Damage Simulation Tool for Ceramic Matrix Composites

    Science.gov (United States)

    Nemeth, Noel; Bednarcyk, Brett; Pineda, Evan; Arnold, Steven; Mital, Subodh; Murthy, Pappu; Bhatt, Ramakrishna

    2016-01-01

    Reported here is a coupling of two NASA developed codes: CARES (Ceramics Analysis and Reliability Evaluation of Structures) with the MAC/GMC (Micromechanics Analysis Code/ Generalized Method of Cells) composite material analysis code. The resulting code is called FEAMAC/CARES and is constructed as an Abaqus finite element analysis UMAT (user defined material). Here we describe the FEAMAC/CARES code and an example problem (taken from the open literature) of a laminated CMC in off-axis loading is shown. FEAMAC/CARES performs stochastic-strength-based damage simulation response of a CMC under multiaxial loading using elastic stiffness reduction of the failed elements.

  17. Marginal adaptation of 1 fiber-reinforced composite and 2 all-ceramic inlay fixed partial denture systems

    OpenAIRE

    Monaco, Carlo; Krejci, Ivo; Bortolotto Ibarra, Tissiana; Perakis, Nikolaos; Ferrari,Marco; Scotti, Roberto

    2006-01-01

    The aim of this in vitro study was to evaluate the marginal adaptation and retention of inlay fixed partial dentures (IFPDs) made with 1 fiber-reinforced composite and 2 different ceramic materials using quantitative scanning electron microscope analysis after thermal cycling and mechanical loading, which simulated approximately 5 years of oral service.

  18. Advanced ceramic materials for next-generation nuclear applications

    Science.gov (United States)

    Marra, John

    2011-10-01

    The nuclear industry is at the eye of a 'perfect storm' with fuel oil and natural gas prices near record highs, worldwide energy demands increasing at an alarming rate, and increased concerns about greenhouse gas (GHG) emissions that have caused many to look negatively at long-term use of fossil fuels. This convergence of factors has led to a growing interest in revitalization of the nuclear power industry within the United States and across the globe. Many are surprised to learn that nuclear power provides approximately 20% of the electrical power in the US and approximately 16% of the world-wide electric power. With the above factors in mind, world-wide over 130 new reactor projects are being considered with approximately 25 new permit applications in the US. Materials have long played a very important role in the nuclear industry with applications throughout the entire fuel cycle; from fuel fabrication to waste stabilization. As the international community begins to look at advanced reactor systems and fuel cycles that minimize waste and increase proliferation resistance, materials will play an even larger role. Many of the advanced reactor concepts being evaluated operate at high-temperature requiring the use of durable, heat-resistant materials. Advanced metallic and ceramic fuels are being investigated for a variety of Generation IV reactor concepts. These include the traditional TRISO-coated particles, advanced alloy fuels for 'deep-burn' applications, as well as advanced inert-matrix fuels. In order to minimize wastes and legacy materials, a number of fuel reprocessing operations are being investigated. Advanced materials continue to provide a vital contribution in 'closing the fuel cycle' by stabilization of associated low-level and high-level wastes in highly durable cements, ceramics, and glasses. Beyond this fission energy application, fusion energy will demand advanced materials capable of withstanding the extreme environments of high

  19. Advanced ceramic materials for next-generation nuclear applications

    International Nuclear Information System (INIS)

    The nuclear industry is at the eye of a 'perfect storm' with fuel oil and natural gas prices near record highs, worldwide energy demands increasing at an alarming rate, and increased concerns about greenhouse gas (GHG) emissions that have caused many to look negatively at long-term use of fossil fuels. This convergence of factors has led to a growing interest in revitalization of the nuclear power industry within the United States and across the globe. Many are surprised to learn that nuclear power provides approximately 20% of the electrical power in the US and approximately 16% of the world-wide electric power. With the above factors in mind, world-wide over 130 new reactor projects are being considered with approximately 25 new permit applications in the US. Materials have long played a very important role in the nuclear industry with applications throughout the entire fuel cycle; from fuel fabrication to waste stabilization. As the international community begins to look at advanced reactor systems and fuel cycles that minimize waste and increase proliferation resistance, materials will play an even larger role. Many of the advanced reactor concepts being evaluated operate at high-temperature requiring the use of durable, heat-resistant materials. Advanced metallic and ceramic fuels are being investigated for a variety of Generation IV reactor concepts. These include the traditional TRISO-coated particles, advanced alloy fuels for 'deep-burn' applications, as well as advanced inert-matrix fuels. In order to minimize wastes and legacy materials, a number of fuel reprocessing operations are being investigated. Advanced materials continue to provide a vital contribution in 'closing the fuel cycle' by stabilization of associated low-level and high-level wastes in highly durable cements, ceramics, and glasses. Beyond this fission energy application, fusion energy will demand advanced materials capable of withstanding the extreme environments of high

  20. The mechanical properties and microstructure of the bionic alloy-ceramic laminated composite

    International Nuclear Information System (INIS)

    Highlights: → The bionic alloy-ceramic laminated composite was fabricated by EB-PVD. → Mechanical properties and microstructure of laminated composite were investigated. → Laminated composite was heat treated in order to improve the tensile strength. -- Abstract: In the present work, the bionic alloy-ceramic laminated composite was fabricated by electron beam-physical vapor deposition method. The ingots of Ni-20Co-12Cr-4Al (wt.%) and ZrO2-8 mol%Y2O3 were used as the sources of the alloy layer and ceramic layer, respectively. The laminated composite was generally destroyed within the ceramic layer when the interlaminar strength was determined, which revealed that the excellent interface bonding between the ceramic layer and the alloy layer. The obvious diffusion interfaces between the ceramic and alloy layers were readily detected, which was favorable to the mechanical properties of the laminated composite. In the heat treatment process, the diffusion of the flaws within the ceramic layer and/or alloy layer to the interface between the ceramic layer and alloy layer was easier compared with the occurrence of interlaminar diffusion. It was confirmed by the X-ray diffractometer that the reaction of the ceramic layer with alloy layer was simple physical diffusion. The tensile strength of the laminated composite increased first and then decreased as the heat treatment time increased, which was attributed to the mutual reaction of the increase in the relative density with the formation of the flaws located at the interface.

  1. Failure of Ceramic Composites in Non-Uniform Stress Fields

    Science.gov (United States)

    Rajan, Varun P.

    Continuous-fiber ceramic matrix composites (CMCs) are of interest as hot-section components in gas turbine engines due to their refractoriness and low density relative to metallic alloys. In service, CMCs will be subjected to spatially inhomogeneous temperature and stress fields. Robust tools that enable prediction of deformation and fracture under these conditions are therefore required for component design and analysis. Such tools are presently lacking. The present work helps to address this deficiency by developing models for CMC mechanical behavior at two length scales: that of the constituents and that of the components. Problems of interest are further divided into two categories: '1-D loadings,' in which the stresses are aligned with the fiber axes, and '2-D loadings,' in which the stress state is more general. For the former class of problems, the major outstanding issue is material fracture, not deformation. A fracture criterion based on the attainment of a global load maximum is developed, which yields results for pure bending of CMCs in reasonable agreement with available experimental data. For the latter class of problems, the understanding of both the micro-scale and macro-scale behavior is relatively immature. An approach based upon analysis of a unit cell (a single fiber surrounded by a matrix jacket) is pursued. Stress fields in the constituents of the composite are estimated using analytical models, the accuracy of which is confirmed using finite element analysis. As part of a fracture mechanics analysis, these fields enable estimation of the steady-state matrix cracking stress for arbitrary in-plane loading of a unidirectional ply. While insightful at the micro-scale, unit cell models are difficult to extend to coarser scales. Instead, material deformation is typically predicted using phenomenological constitutive models. One such model for CMC laminates is investigated and found to predict material instability where none should exist. Remedies to

  2. Fracture toughness determination of ceramic and resin-based dental composites.

    Science.gov (United States)

    Kvam, K

    1992-01-01

    A new method has been developed for Klc determinations of brittle materials with precracks introduced by indentations. A reference glass, five ceramic materials, and one resin-based composite were tested. Knoop hardness indentations were made with a load of 49 N in a line from edge to edge vertical to the long axis on one surface of four-point flexure bars, to make a continuous crack under the indentations. Five specimens of each material were fractured in a four-point bend test with the line of indentations placed in the zone of constant and maximum tensile stress. Separate unfractured specimens were ground and polished to expose and measure the preformed continuous crack. The mean of six crack-depth measurements was used together with the fracture load and the dimensions of the bend specimens to calculate the fracture toughness, Klc of each material. The determined Klc value (x +/- SD) for the reference glass was 0.81 +/- .24 MPa m1/2 and corresponds to previous studies. The resin-based composite material, Silux Plus, had a value of 1.04 +/- 0.14 MPa m1/2. The Klc values (MPa m1/2) were 0.94 +/- 0.31 for Dicor, 1.41 +/- 0.18 for Cerestore, 1.50 +/- 0.29 for NBK-1000, 1.60 +/- 0.17 for Vitadur-N and 2.14 +/- 0.14 for Hi-Ceram. Hi-Ceram had significantly higher Klc values than the other materials. The new method seemed to be of value in determining the fracture toughness of non-metallic dental materials. PMID:1550892

  3. Fracture toughness and reliability in high-temperature structural ceramics and composites: Prospects and challenges for the 21st Century

    Indian Academy of Sciences (India)

    Sunil Dutta

    2001-04-01

    The importance of high fracture toughness and reliability in Si3N4, and SiC-based structural ceramics and ceramic matrix composites is reviewed. The potential of these ceramics and ceramic matrix composites for high temperature applications in defence and aerospace applications such as gas turbine engines, radomes, and other energy conversion hardware have been well recognized. Numerous investigations were pursued to improve fracture toughness and reliability by incorporating various reinforcements such as particulate-, whisker-, and continuous fibre into Si3N4 and SiC matrices. All toughening mechanisms, e.g. crack deflection, crack branching, crack bridging, etc essentially redistribute stresses at the crack tip and increase the energy needed to propagate a crack through the composite material, thereby resulting in improved fracture toughness and reliability. Because of flaw insensitivity, continuous fibre reinforced ceramic composite (CFCC) was found to have the highest potential for higher operating temperature and longer service conditions. However, the ceramic fibres should display sufficient high temperature strength and creep resistance at service temperatures above 1000°C. The greatest challenge to date is the development of high quality ceramic fibres with associate coatings able to maintain their high strength in oxidizing environment at high temperature. In the area of processing, critical issues are preparation of optimum matrix precursors, precursor infiltration into fibre array, and matrix densification at a temperature, where grain crystallization and fibre degradation do not occur. A broad scope of effort is required for improved processing and properties with a better understanding of all candidate composite systems.

  4. Fracture Toughness and Reliability in High-Temperature Structural Ceramics and Composites: Prospects and Challenges for the 21st Century

    Science.gov (United States)

    Dutta, Sunil

    1999-01-01

    The importance of high fracture toughness and reliability in Si3N4, and SiC-based structural ceramics and ceramic matrix composites is reviewed. The potential of these ceramics and ceramic matrix composites for high temperature applications in defense and aerospace applications such as gas turbine engines, radomes, and other energy conversion hardware have been well recognized. Numerous investigations were pursued to improve fracture toughness and reliability by incorporating various reinforcements such as particulate-, whisker-, and continuous fiber into Si3N4 and SiC matrices. All toughening mechanisms, e.g. crack deflection, crack branching, crack bridging, etc., essentially redistribute stresses at the crack tip and increase the energy needed to propagate a crack through the composite material, thereby resulting in improved fracture toughness and reliability. Because of flaw insensitivity, continuous fiber reinforced ceramic composite (CFCC) was found to have the highest potential for higher operating temperature and longer service conditions. However, the ceramic fibers should display sufficient high temperature strength and creep resistance at service temperatures above 1000 'C. The greatest challenge to date is the development of high quality ceramic fibers with associate coatings able to maintain their high strength in oxidizing environment at high temperature. In the area of processing, critical issues are, preparation of optimum matrix precursors, precursor infiltration into fiber array, and matrix densification at a temperature, where grain crystallization and fiber degradation do not occur. A broad scope of effort is required for improved processing and properties with a better understanding of all candidate composite systems.

  5. Federal Aviation Administration (FAA airworthiness certification for ceramic matrix composite components in civil aircraft systems

    Directory of Open Access Journals (Sweden)

    Gonczy Stephen T.

    2015-01-01

    Full Text Available Ceramic matrix composites (CMCs are being designed and developed for engine and exhaust components in commercial aviation, because they offer higher temperature capabilities, weight savings, and improved durability compared to metals. The United States Federal Aviation Administration (FAA issues and enforces regulations and minimum standards covering the safe manufacture, operation, and maintenance of civil aircraft. As new materials, these ceramic composite components will have to meet the certification regulations of the FAA for “airworthiness”. The FAA certification process is defined in the Federal Aviation Regulations (Title 14 of the Code of Federal Regulations, FAA policy statements, orders, advisory circulars, technical standard orders, and FAA airworthiness directives. These regulations and documents provide the fundamental requirements and guidelines for design, testing, manufacture, quality assurance, registration, operation, inspection, maintenance, and repair of aircraft systems and parts. For metallic parts in aircraft, the FAA certification and compliance process is well-established for type and airworthiness certification, using ASTM and SAE standards, the MMPDS data handbook, and FAA advisory circulars. In a similar manner for polymer matrix composites (PMC, the PMC industry and the FAA have jointly developed and are refining parallel guidelines for polymer matrix composites (PMCs, using guidance in FAA circulars and the CMH-17 PMC handbook. These documents discuss design methods and codes, material testing, property data development, life/durability assessment, production processes, QA procedures, inspection methods, operational limits, and repairs for PMCs. For ceramic composites, the FAA and the CMC and aerospace community are working together (primarily through the CMH-17 CMC handbook to define and codify key design, production, and regulatory issues that have to be addressed in the certification of CMC components in

  6. Properties and performance of polysiloxane-derived ceramic matrix in heat resistant composites reinforced with R-glass or fine ceramic fibres

    Czech Academy of Sciences Publication Activity Database

    Černý, Martin; Glogar, Petr; Sucharda, Zbyněk; Machovič, V.

    2005-01-01

    Roč. 49, č. 3 (2005), s. 145-152. ISSN 0862-5468 R&D Projects: GA ČR(CZ) GA106/02/0177; GA ČR(CZ) GP106/02/P025 Institutional research plan: CEZ:AV0Z30460519 Keywords : polysiloxane resin * fibre-reinforced composite * mechanical properties Subject RIV: JH - Ceramic s, Fire-Resistant Materials and Glass Impact factor: 0.463, year: 2005

  7. Evaluation Of Shielding Efficacy Of A Ferrite Containing Ceramic Material

    Energy Technology Data Exchange (ETDEWEB)

    Verst, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-10-12

    The shielding evaluation of the ferrite based Mitsuishi ceramic material has produced for several radiation sources and possible shielding sizes comparative dose attenuation measurements and simulated projections. High resolution gamma spectroscopy provided uncollided and scattered photon spectra at three energies, confirming theoretical estimates of the ceramic’s mass attenuation coefficient, μ/ρ. High level irradiation experiments were performed using Co-60, Cs-137, and Cf-252 sources to measure penetrating dose rates through steel, lead, concrete, and the provided ceramic slabs. The results were used to validate the radiation transport code MCNP6 which was then used to generate dose rate attenuation curves as a function of shielding material, thickness, and mass for photons and neutrons ranging in energy from 200 keV to 2 MeV.

  8. MATERIAL AND ENVIRONMENTAL SUSTAINABILITY IN CERAMIC PROCESSING

    Science.gov (United States)

    Materials Characterization The density of 3124 Ferro Frit and Mason Chrome Free Black Pigment was measured to be 2.4911 g/cm3 and 5.0703 g/cm3 respectively. The single point, BET and Langmuir surface area of 3124 Ferro Frit was deter...

  9. Fatigue in Composite Materials

    Science.gov (United States)

    1984-01-01

    The deformation and failure behavior of graphite/epoxy tubes under biaxial loading was investigated. The increase of basic understanding of and provide design information for the bi-axial response of graphite/epoxy composites to fatigue loads are considered.

  10. Synthesis of (Zn, Mg)TiO3-TiO2 composite ceramics for multilayer ceramic capacitors

    International Nuclear Information System (INIS)

    (Zn0.8Mg0.2)TiO3-xTiO2 composite ceramics has been prepared via the solid-phase synthesis method. TiO2 was employed to tone temperature coefficient of resonant frequency (τf) and stabilize hexagonal (Zn, Mg)TiO3 phase. 3ZnO-B2O3 was effective to promote sintering. The movement of grain boundary was obvious because of the liquid phase sintering. The scanning electron microscope (SEM) photographs and energy dispersive spectrometer (EDS) patterns showed that segregation and precipitation of dissociative (Zn, Mg)TiO3 grains occurred at grain boundary during sintering. SnO2 was used as inhibitor to prevent the grain boundary from moving. The dielectric behaviors of specimen strongly depended on structural transition and microstructure. We found that 1.0 wt.% 3ZnO-B2O3 doped (Zn, Mg)TiO3-0.25TiO2 ceramics with 0.1 wt.% SnO2 additive displayed excellent dielectric properties (at 1000 deg. C): εr = 27.7, Q x f = 65,490 GHz (at 6.07 GHz) and τf = -8.88 ppm deg. C-1. The above-mentioned material was applied successfully to make multilayer ceramic capacitors (MLCCs), which exhibited an excellent electrical property. The self-resonance frequency (SRF) and equivalent series resistance (ESR) of capacitor decreased with capacitance increasing, and the quality factor (Q) of capacitor reduced as frequency or capacity increased.

  11. Preparation of Ceramic Composite Pipes Through Paste Extrusion

    Institute of Scientific and Technical Information of China (English)

    Zhongchun Chen; Takenobu Takeda; Keisuke Kikuchi

    2000-01-01

    An experimental investigation was carried out in order to prepare ceramic composite pipes used for tubular solid oxide fuel cells by using a multi-billet extrusion technique. Particular emphasis was given to the forming possibility and extrusion behavior of a two-layer pipe consisting of NiO-YSZ(PSZ) (anode) and YSZ (electrolyte). It is shown that the extrusion pressure and binder content required decrease with increasing the fraction of nickel oxide in the anode layers. The porosity in the anode layers depends on the binder content in pastes. It is feasible to prepare anode/electrolyte composite pipes by means of co-extrusion of different pastes.Furthermore, it is possible to obtain sound sintered pipes even under pressureless sintering conditions.

  12. Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

    Science.gov (United States)

    Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

    2009-01-01

    An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

  13. Assessment of ceramic raw materials in Uganda for electrical porcelain

    OpenAIRE

    Olupot, Peter Wilberforce

    2006-01-01

    Clay, quartz and feldspar are widely available in Uganda. The location and properties of various clay deposits are reported in the literature, but little is reported on feldspar and quartz deposits. In this work an extended literature on ceramics and porcelains in particular, is documented. Samples from two deposits of feldspar and two deposits of quartz are characterised and found to possess requisite properties for making porcelain insulators. Sample porcelain bodies are made from materials...

  14. Rugometric and microtopographic non-invasive inspection in dental-resin composites and zirconia ceramics

    Science.gov (United States)

    Fernández-Oliveras, Alicia; Costa, Manuel F. M.; Pecho, Oscar E.; Rubiño, Manuel; Pérez, María. M.

    2013-11-01

    Surface properties are essential for a complete characterization of biomaterials. In restorative dentistry, the study of the surface properties of materials meant to replace dental tissues in an irreversibly diseased tooth is important to avoid harmful changes in future treatments. We have experimentally analyzed the surface characterization parameters of two different types of dental-resin composites and pre-sintered and sintered zirconia ceramics. We studied two shades of both composite types and two sintered zirconia ceramics: colored and uncolored. Moreover, a surface treatment was applied to one specimen of each dental-resin. All the samples were submitted to rugometric and microtopographic non-invasive inspection with the MICROTOP.06.MFC laser microtopographer in order to gather meaningful statistical parameters such as the average roughness (Ra), the root-mean-square deviation (Rq), the skewness (Rsk), and the kurtosis of the surface height distribution (Rku). For a comparison of the different biomaterials, the uncertainties associated to the surface parameters were also determined. With respect to Ra and Rq, significant differences between the composite shades were found. Among the dental resins, the nanocomposite presented the highest values and, for the zirconia ceramics, the pre-sintered sample registered the lowest ones. The composite performance may have been due to cluster-formation variations. Except for the composites with the surface treatment, the sample surfaces had approximately a normal distribution of heights. The surface treatment applied to the composites increased the average roughness and moved the height distribution farther away from the normal distribution. The zirconia-sintering process resulted in higher average roughness without affecting the height distribution.

  15. Fatigue-crack propagation behavior in monolithic and composite ceramics and intermetallics

    Energy Technology Data Exchange (ETDEWEB)

    Ritchie, R.O.; Dauskardt, R.H.; Venkateswara Rao, K.T. [Lawrence Berkeley Lab., CA (United States)

    1994-11-01

    We study microstructural mechanisms of fatigue crack growth in advanced monolithic and composite ceramics and intermetallics. Much attention is devoted to the contribution of cycling loading to the hindrance of mechanisms that lead to a considerable increase in toughness (crack-tip shielding) of these materials. For example, in intermetallics with a ductile phase, such as {Beta}-TiNb-reinforced {gamma}-TiAl or Nb-reinforced Nb{sub 3}Al, a significant increase in toughness caused by the presence of uncracked ductile phase inside a crack is retarded under cyclic loading because ductile particles immediately fail by fatigue. Similarly, in monolithic ceramics, e.g., in alumina (aluminum oxide) or silicon nitride, the significant plasticization appearing under monotonic loading is greatly diminished under cyclic loading due to gradual wear at the grain-matrix interface. In fact, the nature of fatigue in such low-plasticity materials differs essentially from the well-known mechanisms of fatigue in metals and is governed, first of all, by a decrease in shielding, which depends on the loading cycle and time. The susceptibility of intermetallics and ceramics to fatigue degradation under cyclic loading affects seriously the possibility of structural use of these materials in practice. In particular, in this case, it is difficult to apply strength calculation methods that take into account the presence of defects and to implement life-prediction procedures.

  16. Preparation and Properties of Orthogonal Piezoelectric Composite Materials

    Institute of Scientific and Technical Information of China (English)

    Liu Jun; Lu Ying; Zhang Xingguo; Shen Yi; Chen Chun

    2004-01-01

    . PZT piezoelectric ceramic with La2O3, SrCO3, BaO and Sb2O5 was prepared. It has high value of the piezoelectric strain constant d33 ( -681 PC/N) and high value of-d33/d31 (2.65). Orthogonal piezoelectric composite materials was designed and prepared by PZT, DAD- 40 electric conductive adhesive and E51 epoxy resin. The OPCM shows obvious orthogonal anisotropy. The matching property of the interface between piezoelectric ceramic and polymer of OPCM relies on the defects of interface. The proper conductive mid-layer could improve the matching property of the interface.

  17. Ceramic composites derived from poly(phenylsilsesquioxane)/Al2O3/Nb

    International Nuclear Information System (INIS)

    Active filler controlled reaction pyrolysis of polymers (AFCOP) is a recent method for obtaining near-net shaped ceramic bodies from a mixture of polymers, reactive filler and inert filler. Samples containing 60 wt.% of poly(phenylsilsesquioxane) (PPS) and 40 wt.% of metallic niobium and alumina powders were homogenized, uniaxially warm pressed and subsequently pyrolyzed in flowing argon at 1200, 1400 and 1600 deg. C. Ceramic bodies were characterized by X-ray diffraction (XRD), thermogravimetry (TGA), differential thermal analysis (DTA), fourier transform infrared (FTIR), porosity measurements and scanning electron microscopy (SEM). The results indicated that the AFCOP process is potentially very suitable for obtaining multiphase composite materials of the Al2O3-Nb system at low temperatures

  18. Continuous Fiber Ceramic Composite (CFCC) Program. Inventory of federally funded CFCC R&D projects

    Energy Technology Data Exchange (ETDEWEB)

    Richlen, S. [USDOE Assistant Secretary for Energy Efficiency and Renewable Energy, Washington, DC (United States). Office of Industrial Technologies; Caton, G.M.; Karnitz, M.A.; Cox, T.D. [Oak Ridge National Lab., TN (United States); Hong, W. [Institute for Defense Analyses, Alexandria, VA (United States)

    1993-05-01

    Continuous Fiber Ceramic Composites (CFCC) are a new class of materials that are lighter, stronger, more corrosion resistant, and capable of performing at elevated temperatures. This new type of material offers the potential to meet the demands of a variety of industrial, military, and aerospace applications. The Department of Energy Office of Industrial Technologies (OIT) has a new program on CFCCs for industrial applications and this program has requested an inventory of all federal projects on CFCCs that relate to their new program. The purpose of this project is to identify all other ongoing CFCC research to avoid redundancy in the OIT Program. The inventory will be used as a basis for coordinating with the other ongoing ceramic composite projects. The inventory is divided into two main parts. The first part is concerned with CFCC supporting technologies projects and is organized by the categories listed below. (1) Composite Design; (2) Materials Characterization; (3) Test Methods; (4) Non-Destructive Evaluation; (5) Environmental Effects; (6) Mechanical Properties; (7) Database Life Prediction; (8) Fracture/Damage; and (9) Joining. The second part has information on component development, fabrication, and fiber-related projects.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-03-30

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

  20. Structure modification of 0-3 piezoelectric ceramic/polymer composites through dielectrophoresis

    International Nuclear Information System (INIS)

    Anisotropic material properties can be induced in ceramic/polymer composites by applying an alternating electric field of moderate strength during processing. Under suitable conditions, particles of a ceramic filler material that are randomly dispersed in a liquid polymer or pre-polymer can be polarized and they then exhibit a collective response to localized gradients in the electric field. Typically, the particles experience a mutually attractive force which causes them to form 'pearl-chains' or columnar structures spanning the gap between electrodes. If the fluid is solidified, for example by curing the polymer resin, then the newly formed structures can be fixed in place to produce a composite with directional electrical and mechanical properties. Direct visual observations were made for low volume fraction dispersions of pure lead titanate in an epoxy pre-polymer under the influence of an electric field. The observed interaction was correlated with low-field dielectric measurements and existing theory to identify optimum assembly conditions. The dielectric properties of the fluid are predominant and the formation of chain-like structures is found to be both field strength and field frequency dependent. The dielectric permittivities of a range of structurally modified composites were measured and compared with existing theoretical models of di-phasic materials

  1. Ceramic Composite Mechanical Fastener System for High-Temperature Structural Assemblies Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Under Phase I, the feasibility of a novel thermal stress-free ceramic composite mechanical fastener system suitable for assembly of high-temperature composite...

  2. Manufacturing technologies for nanocomposite ceramic structural materials and coatings

    International Nuclear Information System (INIS)

    The new material class of ceramic nanocomposites, containing at least one phase in nanometric dimension, has achieved special interest in previous years. While earlier research was focused on materials science and microstructural details in laboratory scale the subject of developing suitable manufacturing technologies in technical scale is the challenge for the manufacturing engineer. The same high-performance features which make the nanocomposite materials so interesting in their properties are absolutely detrimental if it comes to production of these materials. Extreme hardness, toughness and abrasion resistance make the state of the art cutting-and-machining operations extremely cost intensive so that, from a manufacturing point of view, true near-net-shape manufacturing is mandatory to accomplish reasonable cost targets. Ceramic feedstocks with both, high solid content to reduce shrinkage and warping and stable processing conditions are required to accomplish this aim of near-net-shape processing. Stable and reproducible processing conditions, e.g. favourable rheological properties for injection moulding are essentials for the manufacturing engineer. These prerequisites of ceramic production technologies cannot be reached with pure nanopowders in the 10-20 nm range but materials with a micro-nano architecture can fulfill these requirements, using a mixture of a submicron-sized matrix in the 100-200 nm range and smaller nanosized additives in <20% content which contribute the desired functionality. By using these micro-nanocomposites near-net-shape ceramic forming technologies such as injection moulding, gel casting and slip casting have been developed which lead to high-performance materials at affordable production cost. Advanced surface technologies include nanoceramic coatings made by thermokinetic deposition processes. Modern ceramic processing, i.e. spray drying leads to fine granulated nanopowders with appropriate flowability for subsequent APS plasma or

  3. Liquid-assisted laser ablation of advanced ceramics and glass-ceramic materials

    Science.gov (United States)

    Garcia-Giron, A.; Sola, D.; Peña, J. I.

    2016-02-01

    In this work, results obtained by laser ablation of advanced ceramics and glass-ceramic materials assisted by liquids are reported. A Q-switched Nd:YAG laser at its fundamental wavelength of 1064 nm with pulse-width in the nanosecond range was used to machine the materials, which were immersed in water and ethylene glycol. Variation in geometrical parameters, morphology, and ablation yields were studied by using the same laser working conditions. It was observed that machined depth and removed volume depended on the thermal, optical, and mechanical features of the processed materials as well as on the properties of the surrounding medium in which the laser processing was carried out. Variation in ablation yields was studied in function of the liquid used to assist the laser process and related to refractive index and viscosity. Material features and working conditions were also related to the obtained results in order to correlate ablation parameters with respect to the hardness of the processed materials.

  4. DOE Automotive Composite Materials Research: Present and Future Efforts

    Energy Technology Data Exchange (ETDEWEB)

    Warren, C.D.

    1999-08-10

    One method of increasing automotive energy efficiency is through mass reduction of structural components by the incorporation of composite materials. Significant use of glass reinforced polymers as structural components could yield a 20--30% reduction in vehicle weight while the use of carbon fiber reinforced materials could yield a 40--60% reduction in mass. Specific areas of research for lightweighting automotive components are listed, along with research needs for each of these categories: (1) low mass metals; (2) polymer composites; and (3) ceramic materials.

  5. ELASTIC BEHAVIOR ANALYSIS OF 3D ANGLE-INTERLOCK WOVEN CERAMIC COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    Chang Yanjun; Jiao Guiqiong; Wang Bo; Liu Wei

    2006-01-01

    A micromechanical model for elastic behavior analysis of angle-interlock woven ceramic composites is proposed in this paper. This model takes into account the actual fabric structure by considering the fiber undulation and continuity in space, the cavities between adjacent yarns and the actual cross-section geometry of the yarn. Based on the laminate theory, the elastic properties of 3D angle-interlock woven ceramic composites are predicted. Different numbers of interlaced wefts have almost the same elastic moduli. The thickness of ceramic matrix has little effect on elastic moduli. When the undulation ratio increases longitudinal modulus decreases and the other Young's moduli increase. Good agreement between theoretical predictions and experimental results demonstrates the feasibility of the proposed model in analyzing the elastic properties of3D angle-interlock woven ceramic composites. The results of this paper verify the fact that the method of analyzing polyester matrix composites is suitable for woven ceramic composites.

  6. Robocast Pb(Zr0.95Ti0.05)O3 Ceramic Monoliths and Composites

    International Nuclear Information System (INIS)

    Robocasting, a computer controlled slurry deposition technique, was used to fabricate ceramic monoliths and composites of chemically prepared Pb(Zr0.95Ti0.05)O3 (PZT 95/5) ceramics. Densities and electrical properties of the robocast samples were equivalent to those obtained for cold isostatically pressed (CIP) parts formed at 200 MPa. Robocast composites consisting of alternate layers of the following sintered densities: (93.9%--96.1%--93.9%), were fabricated using different levels of organic pore former additions. Modification from a single to a multiple material deposition robocaster was essential to the fabrication of composites that could withstand repeated cycles of saturated polarization switching under 30 kV/cm fields. Further, these composites withstood 500 MPa hydrostatic pressure induced poled ferroelectric (FE) to antiferroelectric (AFE) phase transformation during which strain differences on the order of 0.8% occurred between composite elements

  7. Microstructural, compositional and mechanical properties of the archaeological indigenous ceramics of Caninhas, Sao Paulo,Brazil

    International Nuclear Information System (INIS)

    Archaeological ceramics contain infinity of data about social and cultural indigenous site Caninhas/SP. The ceramics present a gradient of color (ochre to dark gray), when from the surface to the center of the piece, indicating compositional variability caused by inefficient sintering carried out by indigenous peoples. It was analyzed the composition phases by X-rays diffraction (XRD) and mapping by EDS, identifying the illite, quartz and lutecite phases (ochre region) and illite, quartz, hydrated alumina and lutecite phases (dark gray region). The results of EDS confirmed the stages identified by X-rays diffraction and suggesting the presence of roots and scrap of ceramics sintered in the composition of indigenous ceramics, when compared by optical microscope and scanning electron microscope. Vickers hardness identified as fragile and heterogeneous are archaeological ceramics, reaching approximately 203 HV in the grains of silica and 16 HV in the ceramic matrix. (author)

  8. Micromechanics Fatigue Damage Analysis Modeling for Fabric Reinforced Ceramic Matrix Composites

    Science.gov (United States)

    Min, J. B.; Xue, D.; Shi, Y.

    2013-01-01

    A micromechanics analysis modeling method was developed to analyze the damage progression and fatigue failure of fabric reinforced composite structures, especially for the brittle ceramic matrix material composites. A repeating unit cell concept of fabric reinforced composites was used to represent the global composite structure. The thermal and mechanical properties of the repeating unit cell were considered as the same as those of the global composite structure. The three-phase micromechanics, the shear-lag, and the continuum fracture mechanics models were integrated with a statistical model in the repeating unit cell to predict the progressive damages and fatigue life of the composite structures. The global structure failure was defined as the loss of loading capability of the repeating unit cell, which depends on the stiffness reduction due to material slice failures and nonlinear material properties in the repeating unit cell. The present methodology is demonstrated with the analysis results evaluated through the experimental test performed with carbon fiber reinforced silicon carbide matrix plain weave composite specimens.

  9. Effect of melting pressure and superheating on chemical composition and contamination of yttria coated ceramic crucible induction melted titanium alloys

    OpenAIRE

    Gomes, Fernando; Puga, Hélder; Barbosa, J; Ribeiro, Carlos Silva

    2011-01-01

    When melting reactive alloys, chemical composition and alloy homogeneity strongly depend on processing conditions, especially if melting is performed in ceramic crucibles. In this case, the nature of crucible materials, the melting stock composition and the melting parameters (atmosphere, pressure, superheating time and temperature) are critical processing variables. In this work, a Ti–48Al alloy was induction melted in a ZrO2 SiO2-based crucible with Y2O3 inner layer ...

  10. Syntheses and Characterizations of Polymer-Ceramic Composites Having Increased Hydrophilicity, Air-Permeability, and Anti-Fungal Property

    International Nuclear Information System (INIS)

    Generally, polymer materials are not air-permeable and hydrophilic. In addition, they do not possess anti-fungal property. Hydrophilicity, air-permeability, and anti-fungal properties of new composites consisting of polymer, ceramic nanoparticles, and silver ion were investigated by contact angle measurements, air permeation time, and cell culture. The hydrophilic, air-permeable, and anti-fungal composites can be used in health care industry

  11. Microstructure-electrical properties relation of zirconia based ceramic composites

    International Nuclear Information System (INIS)

    The electrical properties of zirconia based ceramic composites were studied by impedance spectroscopy. Three materials were prepared with different relative compositions of the conducting and insulating phases: (ZrO2:8 mol% Y2)3) + MgO, (ZrO2:8 mol% Y2O3) + Y2O3 and ZrO2 + 8 mol% Y2O3. All specimens were analyzed by X-ray diffraction and scanning electron microscopy for microstructural characterization and for correlation of microstructural aspects with electrical properties. For (ZrO2:8 mol% Y2O3) + MgO the main results show that the dependence of the different (microstructural constituents) contributions to the electrical resistivity on the magnesia content follows two stages: one below and another above the solubility limit of magnesia in Yttria-stabilized zirconia. The same dependence is found for the lattice parameter determined by X-ray diffraction measurements. The impedance diagrams of the composites have been resolved allowing the identification of contributions due to the presence of each microstructural constituent in both stages. Magnesia as a second phase is found to inhibit grain growth in Yttria-stabilized zirconia and the solubility limit for magnesia in the zirconia matrix is around 10 mol%. For (ZrO2:8 mol% Y2O3) + Y2O3 the main results show that: Yttria is present as a second phase for 1350 deg C /0.1 h sintering; the addition of 2 mol% of Yttria does not modify significantly the electrical properties; the solubility limit for Yttria is around 2 mol% according to electrical measurements. Similarly to magnesia, Yttria inhibits grain growth on Yttria-stabilized zirconia. The general effective medium theory was used to analyze the percolation of the insulating phase; the percolation threshold is different if one considers separately the total, bulk and grain boundary contributions to the electrical conductivity: 32.0, 38.5 and 27.8 vol% for total, intra and intergranular contributions, respectively. The increase of the activation energy for ionic

  12. Poly(borosiloxanes as precursors for carbon fiber ceramic matrix composites

    Directory of Open Access Journals (Sweden)

    Renato Luiz Siqueira

    2007-06-01

    Full Text Available Ceramic matrix composites (CMCs, constituted of a silicon boron oxycarbide (SiBCO matrix and unidirectional carbon fiber rods as a reinforcement phase, were prepared by pyrolysis of carbon fiber rods wrapped in polysiloxane (PS or poly(borosiloxane (PBS matrices. The preparation of the polymeric precursors involved hydrolysis/condensation reactions of alkoxysilanes in the presence and absence of boric acid, with B/Si atomic ratios of 0.2 and 0.5. Infrared spectra of PBS showed evidence of Si-O-B bonds at 880 cm-1, due to the incorporation of the crosslinker trigonal units of BO3 in the polymeric network. X ray diffraction analyses exhibited an amorphous character of the resulting polymer-derived ceramics obtained by pyrolysis up to 1000 °C under inert atmosphere. The C/SiBCO composites showed better thermal stability than the C/SiOC materials. In addition, good adhesion between the carbon fiber and the ceramic phase was observed by SEM microscopy

  13. The suitability of XRF analysis for compositional classification of archaeological ceramic fabric: A comparison with a previous NAA study

    International Nuclear Information System (INIS)

    The main drawbacks of EDXRF techniques, restricting its more frequent use for the specific purpose of compositional analysis of archaeological ceramic fabric, have been the insufficient sensitivity to determine some important elements (like Cr, REE, among others), a somewhat worse precision and the inability to perform standard-less quantitative procedures in the absence of suitable certified reference materials (CRM) for ceramic fabric. This paper presents the advantages of combining two energy dispersive X-ray fluorescence methods for fast and non-destructive analysis of ceramic fabric with increased sensitivity. Selective polarized excitation using secondary targets (EDPXRF) and radioisotope excitation (R-XRF) using a 241Am source. The analytical performance of the methods was evaluated by analyzing several CRM of sediment type, and the fitness for the purpose of compositional classification was compared with that obtained by using Instrumental Neutron Activation Analysis in a previous study of Cuban aborigine pottery

  14. The suitability of XRF analysis for compositional classification of archaeological ceramic fabric: A comparison with a previous NAA study

    Energy Technology Data Exchange (ETDEWEB)

    Padilla, R. [Centro de Aplicaciones Tecnologicas y Desarrollo Nuclear (CEADEN), Laboratorio de Analisis Quimico, Calle 30 no. 502, Playa, Ciudad Habana (Cuba)]. E-mail: roman.padilla@infomed.sld.cu; Espen, P. van [University of Antwerp (Belgium); Torres, P.P. Godo [Centro de Antropologia, Havana (Cuba)

    2006-02-03

    The main drawbacks of EDXRF techniques, restricting its more frequent use for the specific purpose of compositional analysis of archaeological ceramic fabric, have been the insufficient sensitivity to determine some important elements (like Cr, REE, among others), a somewhat worse precision and the inability to perform standard-less quantitative procedures in the absence of suitable certified reference materials (CRM) for ceramic fabric. This paper presents the advantages of combining two energy dispersive X-ray fluorescence methods for fast and non-destructive analysis of ceramic fabric with increased sensitivity. Selective polarized excitation using secondary targets (EDPXRF) and radioisotope excitation (R-XRF) using a {sup 241}Am source. The analytical performance of the methods was evaluated by analyzing several CRM of sediment type, and the fitness for the purpose of compositional classification was compared with that obtained by using Instrumental Neutron Activation Analysis in a previous study of Cuban aborigine pottery.

  15. Encapsulation of spent nuclear fuel in ceramic materials

    International Nuclear Information System (INIS)

    The international situation with regard to deposition of spent nuclear fuel is surveyed, with emphasis on encapsulation in ceramic materials. The feasibility and advantages of ceramic containers, thermodynamic stable in groundwater, are discussed as well as the possibility to ensure that stability for longevity by engineered measures. The design prerequisite are summarized and suggestions are made for a conceptual design, comprising rutile containers with stacks of coiled fuel pins. A novel technique is suggested for the homogeneous sealing of rutile containers at low temperatures. acceptable also for the fuel pin package. Key points are given for research, demonstration and verifications of the design foundations and for future improvements. Of which a few ideas are exemplified. (author)

  16. Influence of different post core materials on the color of Empress 2 full ceramic crowns

    Institute of Scientific and Technical Information of China (English)

    GE Jing; WANG Xin-zhi; FENG Hai-lan

    2006-01-01

    Background For esthetic consideration, dentin color post core materials were normally used for all-ceramic crown restorations. However, in some cases, clinicians have to consider combining a full ceramic crown with a metal post core. Therefore, this experiment was conducted to test the esthetical possibility of applying cast metal post core in a full ceramic crown restoration.Methods The color of full ceramic crowns on gold and Nickel-Chrome post cores was compared with the color of the same crowns on tooth colored post cores. Different try-in pastes were used to imitate the influence of a composite cementation on the color of different restorative combinations. The majority of patients could not detect any color difference less than △E 1.8 between the two ceramic samples. So, △E 1.8 was taken as the objective evaluative criterion for the evaluation of color matching and patients' satisfaction.Results When the Empress 2 crown was combined with the gold alloy post core, the color of the resulting material was similar to that of a glass fiber reinforced resin post core (△E = 0.3). The gold alloy post core and the try-in paste did not show a perceptible color change in the full ceramic crowns, which indicated that the color of the crowns might not be susceptible to change between lab and clinic as well as during the process of composite cementation. Without an opaque covering the Ni-Cr post core would cause an unacceptable color effect on the crown (△E = 2.0), but with opaque covering, the color effect became more clinically satisfactory (△E=1.8).Conclusions It may be possible to apply a gold alloy post core in the Empress 2 full ceramic crown restoration when necessary. If a non-extractible Ni-Cr post core exists in the root canal, it might be possible to restore the tooth with an Empress 2 crown after coveting the labial surface of the core with one layer of opaque resin cement.

  17. Mechanical behaviour of new zirconia-hydroxyapatite ceramic materials

    Energy Technology Data Exchange (ETDEWEB)

    Delgado, J.A.; Morejon, L. [La Habana Univ. (Cuba). Centro de Biomateriales; Martinez, S. [Barcelona Univ. (Spain). Dept. Cristallografia, Mineralogia; Ginebra, M.P.; Carlsson, N.; Fernandez, E.; Planell, J.A. [Universidad Politecnica de Cataluna, Barcelona (Spain). CREB; Clavaguera-Mora, M.T.; Rodriguez-Viejo, J. [Universitat Autonoma de Barcelona (Spain). Dept. de Fisica

    2001-07-01

    In this work a new zirconia-hydroxyapatite ceramic material was obtained by uniaxial pressing and sintering in humid environment. The powder X-ray diffraction (XRD) patterns and infrared spectra (FT-IR) showed that the hydroxyapatite (HA) is the only calcium phosphate phase present. The fracture toughness for HA with 20 wt.% of magnesia partially stabilised zirconia (Mg-PSZ) was around 2.5 times higher than those obtained for HA pure, also the highest value of bending strength (160 MPa) was obtained for material reinforced with Mg-PSZ. For the MgPSZ-HA (20%) the fracture mechanism seems to be less transgranular. (orig.)

  18. Ultrasonic assessment of interfacial oxidation damage in ceramic matrix composites

    Science.gov (United States)

    Chu, Y. C.; Rokhlin, S. I.; Baaklini, G. Y.

    1993-01-01

    A new approach to characterizing oxidation damage in ceramic matrix composites using ultrasonic techniques is proposed. In this approach, the elastic constants of the composite are determined nondestructively by measuring the angular dependence of both longitudinal and transverse wave velocities. A micromechanical model for composites with anisotropic constituents is used to find the anisotropic properties of an effective fiber, which is a combination of the fiber and the interface. Interfacial properties are extracted from the properties of this effective fiber by analyzing the difference between effective and actual fiber properties. Unidirectional /0/28 SiC/Si3N4 composites with 30 percent fiber volume fraction and 30 percent matrix porosity are used. The samples are exposed in a flowing oxygen environment at elevated temperatures, up to 1400 C, for 100 hours and then measured by ultrasonic methods at room temperature. The Young's modulus in the fiber direction of the sample oxidized at 600 C decreased significantly but it was unchanged for samples oxidized at temperatures above 1200 C. The transverse moduli obtained from ultrasonic measurements decrease continuously up to 1200 C. The shear stiffnesses show behavior similar to the transverse moduli. The effective elastic moduli of the interfacial carbon coating are determined from the experimental data, and their change due to thermal oxidation is discussed.

  19. 15th annual conference on composites and advanced ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Baaklini, G.Y.; Bhatt, R.T.

    1991-01-01

    The room-temperature tensile testing of silicon carbide fiber reinforced reaction-bonded silicon nitride (SiC/RBSN) composite specimens was monitored by using in-situ x ray film radiography. Radiographic evaluation before, during, and after loading provided data on the effect of preexisting volume flaws (high density impurities, and local density variations) on the fracture behavior of composites. Results from (0)1, (0)3, (0)5, and (0)8 composite specimens, showed that x ray film radiography can monitor damage accumulations during tensile loading. Matrix cracking, fiber-matrix debonding, and fiber pullout were imaged throughout the tensile loading history of the specimens. Further, in-situ film radiography was found to be a helpful and practical technique for estimating interfacial shear strength between the SiC fiber and the RBSN matrix by the matrix crack spacing method. It is concluded that pretest, in-situ, and post-test radiography can provide for a greater understanding of ceramic matrix composite mechanical behavior, a verification of related experimental procedures, and a validation and development of related analytical models.

  20. Coating material composition

    International Nuclear Information System (INIS)

    A polyester composition is provided for forming a hard and weather-proof coating easily hardened by irradiation with active energy, particularly electron beams, using a mixture of a polyester component containing a dimer of methacrylate as an acid group with an oligomer having at least two vinyl radicals in one molecule. The composition consists of 10%-90% by weight of at least one (a) methacrylic dimer or unsaturated polyester containing its methyl ester as an acid group, (b) telomerized diacrylpolyester or (c) telomerized fiberous polyester having at its distal end a dimer of methacrylate residue, and 90%-10% of a low molecular weight compound having at least two polymerizable unsaturated radicals. The low molecular weight compound is produced by reacting at first saturated cyclic carboxylic anhydride and/or alpha-, beta-ethylenic unsaturated carboxylic anhydride and secondarily a vinyl monomer containing epoxy-radicals with hydroxyl radical-containing vinyl monomer and/or polyhydric alcohol. The aforesaid methacrylic acid dimer dimethyl ester is a byproduct of methyl methacrylate synthesis. This produces monoester monocarboxylic acid or dicarboxylic acid by hydrolysis. In one example, a polyester (a-1) was produced by reacting 0.5 moles of methacrylic acid dimer, 0.5 mol of adipic acid, 1,25 mole of ethylene glycol and 0.005 mol of hydroquinone monomethyl ether. On the other hand, an orgomer (d) is obtained from 1 mol of 2-hydroxyl ethyl methacrylate, 1 mol of maleic anhydride, 0.005 mol of hydroquinon monomethyl ether and 1 mol of glycidyl methacrylate. Next, 80 parts of (a-1) and 20 parts of (d) were mixed. (Iwakiri, K.)

  1. Damage analysis of the ceramic reinforced steel matrix composites sheets: experimental and numerical study

    Directory of Open Access Journals (Sweden)

    E. Bayraktar

    2011-11-01

    Full Text Available Purpose: of this paper reports damage analysis of TiB2 (ceramic particles reinforced steel matrix composite sheets. This new steel composite receives much attention as potential structural materials due to their high specific strength and stiffness. The goal of the research described in this paper is to study the usage of this new steel family in the manufacture of light structures.Design/methodology/approach: therefore in this study is focused to the titanium diboride TiB2 reinforced steel matrix composite sheets that they were characterized by optical and scanning electron microscopes after the mechanical tests carried out on the base metal and welded specimens under dynamic and static test conditions.Findings: The non homogeneity of the structure in this type of composites makes deeply complexity of their numerical and analytical modelling to predict their damage during the loading. For example, the interfaces essentially play a key role in determining mechanical and physical properties. For this reason, a Finite Element (FEM analysis is used for modelling to simulate the macroscopic behaviour of this material, taking into account the relevant microscopic scales.Practical implications: defined in this research is based on the impact dynamic behaviour of this steel sheets by using a special impact tensile test developed formerly that all details were published in this journal. This type of test gives more comprehensible information about special steel sheets (welded or base metal in case of dynamic crash conditions.Originality/value: The present research gives detail information on the new steel matrix composite sheets reinforced TiB2 ceramic particles. This new composite was developed by ARCELOR research group and impact dynamic behaviour and weldability of the welded parts and base metals from this composite steel are discussed here in order to give practical and useful solution for industrial applications.

  2. The Fabrication and Characterization of PCL/Rice Husk Derived Bioactive Glass-Ceramic Composite Scaffolds

    OpenAIRE

    2014-01-01

    The present study was conducted to fabricate a 3D scaffold using polycaprolactone (PCL) and silicate based bioactive glass-ceramic (R-SBgC). Different concentrations of R-SBgC prepared from rice husk ash (RHA) were combined with PCL to fabricate a composite scaffold using thermally induced phase separation (TIPS) method. The products were then characterized using SEM and EDX. The results demonstrated that R-SBgC in PCL matrix produced a bioactive material which has highly porous structure wit...

  3. WEARPROOFNESS OF TITANIC ALLOY, FIXED CERAMIC COMPOSITION COVERAGE IN THE CONDITIONS OF FRETTAGE

    OpenAIRE

    Лабунець, В. Ф.; Національний авіаційний університет; Бурбела, Ю.Б.; Національний авіаційний університет

    2013-01-01

    In this article the wearproofness of titanic alloy of ВТЗ-1 is considered under conditions of a contact load-ing. The situation analysis and needs in such work have been carried out. The research of the surface strength-ening of this alloy with ceramic composition coverages is also described. The tests results under conditions of frettage at a friction without lubricating material out on the air in the systems „coverage-coverage” and „cov-erage-steel 45” are shown here.

  4. The effects of residual stress, viscoelastic and thermodynamic parameters on apparent fracture toughness of dental bilayer ceramic composites

    Science.gov (United States)

    Taskonak, Burak

    Bilayer dental ceramic composites used for fixed partial dentures are becoming more widely used in dental practices because of their biocompatibility, aesthetic properties, and chemical durability. However, large statistical variations in the strength of ceramics are associated with the structural flaws as a result of processing and complex stress states within the surfaces of the materials because of thermal properties of each layer. In addition, partial delaminations of the veneer layer and connector fractures of bilayer ceramic fixed partial dentures (FPDs) have been observed in a clinical study which is a part of this dissertation. Analysis of fracture surfaces of failed FPDs reveals that such fractures of the veneering ceramic are most likely caused by lateral crack growth. Global residual stresses associated with the coefficient of thermal expansion differences between core and veneering ceramics can cause lateral crack initiation. Also, rapid cooling of bilayer ceramics from the sintering temperature of the glass veneer may not allow the interfacial stresses in the viscoelastic glass to relax to equilibrium values. This can further contribute to the propagation of lateral cracks. Furthermore, local residual stresses that develop in the plastic deformation zone below sharp contact areas on the occlusal surface are another contributor to lateral crack growth. Superposition of global residual stresses and a Boussinesq stress field can incrementally increase the possibility of lateral crack growth. The long-range goals of this study are to critically analyze the lateral crack growth mechanisms associated with residual stresses, to modify residual tensile stress distributions by controlled heat treatment, and to minimize the probability of veneering ceramic fractures. Four approaches were used to accomplish these goals: (1) clinical evaluation of a bilayer ceramic fixed partial denture system; (2) fracture surface analysis of clinically failed FPDs; (3

  5. Elevated-temperature fracture resistances of monolithic and composite ceramics using chevron-notched bend tests

    Science.gov (United States)

    Ghosh, Asish; Jenkins, Michael G.; Ferber, Mattison K.; Peussa, Jouko; Salem, Jonathan A.

    1992-01-01

    The quasi-static fracture behaviors of monolithic ceramics (SiC, Si3N4, MgAl2O4), self-reinforced monoliths (acicular grained Si3N4, acicular grained mullite), and ceramic matrix composites (SiC whisker/Al2O3 matrix, TiB2 particulate/SiC matrix, SiC fiber/CVI SiC matrix, Al2O3 fiber/CVI SiC matrix) were measured over the temperature range of 20 to 1400 C. The chevron notched, bend bar test geometry was essential for characterizing the elevated temperature fracture resistances of this wide range of quasi-brittle materials during stable crack growth. Fractography revealed the differences in the fracture behavior of the different materials at the various temperatures. The fracture resistances of the self-reinforced monoliths were comparable to those of the composites and the fracture mechanisms were found to be similar at room temperature. However at elevated temperatures the differences of the fracture behavior became apparent where the superior fracture resistance of the self-reinforced monoliths were attributed to the minor amounts of glassy, intergranular phases which were often more abundant in the composites and affected the fracture behavior when softened by elevated temperatures.

  6. The Effect of adding pore formers on the microstructure of NiO-YSZ ceramic composite

    International Nuclear Information System (INIS)

    The ceramic composite of nickel oxide (NiO) with zirconium stabilized with 8 mol% yttria (8-YSZ) is the most employed material for use as anode for solid oxide fuel cells (SOFC). The nickel oxide in the composite is reduced to metallic nickel and this result in a 15% of porosity although the porosity needed to a proper function of an anode is about 30%, demanding the use of a pore former. In this work, NiO-YSZ composite powders were synthesized by a combustion process with urea as fuel, and the effect of the addition of carbon black and corn and rice starch as pore former were investigated. Powders were pressed as cylindrical pellets, sintered at 1350 °C for 60 minutes and density were measured by an immersion method and microstructure were observed by scanning electron microscopy. Results showed that ceramic composite has homogeneous microstructure and pores have different morphology and size depending on the kind of the pore former employed. (author)

  7. The behaviour of fibrous composite materials under nuclear radiations exposure

    International Nuclear Information System (INIS)

    The main feature of fibrous composite materials are briefly described, which are constitued by a netwoek of ceramic high performance fiber embebed in a ductile matrix material. These composite materials show such a kind of anisotropic strength that their uses has been widely spreaded in the last times. This philosophy of strengthening was used by the Nature, where are abundant examples of fibrous composites like horn, bamboo tissues, etc. In this paper are collected the published results about behaviour of reinforced dibers and fibrous composites under nuclear radiation exposure. The results show a very wide sort of fenomenae depending on many factors. Are fibers, like the boron one, which shows an inconvenient behaviour and another like graphite fibers which appears to improve its features. Is is concluded that was not achieved enough information about the behaviour of the interface under irradiation in order to build up a theory about the behaviour of the full composite under irradiation exposure. (author)

  8. Powder metallurgical fabrication of metal/ceramic functionally graded materials for high temperature use

    International Nuclear Information System (INIS)

    Powder metallurgical fabrication of metal/ceramic functionally graded material (FGM) has been described. The first part of this paper briefly shows the concept of FGM with the special reference to the large progress of research works on thermal barrier materials where the role of thermal stress relaxation function has been emphasized. Then, powder metallurgical processing of this type of FGM is reviewed on the basis of recent activities. Graded structures may be found in ordinary engineering materials from former days; however, if one has begun to tailor the intentional gradient of composition and/or microstructure in a material in order to achieve the desired functions and properties, the material shall possess the concept of Functionally Graded Material (FGM). The FGM has the great potential of applications in many fields by using gradient on chemical, biochemical, physical and mechanical properties. (author)

  9. Ceramic Identity Contributes to Mechanical Properties and Osteoblast Behavior on Macroporous Composite Scaffolds

    Directory of Open Access Journals (Sweden)

    J. Kent Leach

    2012-05-01

    Full Text Available Implants formed of metals, bioceramics, or polymers may provide an alternative to autografts for treating large bone defects. However, limitations to each material motivate the examination of composites to capitalize on the beneficial aspects of individual components and to address the need for conferring bioactive behavior to the polymer matrix. We hypothesized that the inclusion of different bioceramics in a ceramic-polymer composite would alter the physical properties of the implant and the cellular osteogenic response. To test this, composite scaffolds formed from poly(lactide-co-glycolide (PLG and either hydroxyapatite (HA, β-tricalcium phosphate (TCP, or bioactive glass (Bioglass 45S®, BG were fabricated, and the physical properties of each scaffold were examined. We quantified cell proliferation by DNA content, osteogenic response of human osteoblasts (NHOsts to composite scaffolds by alkaline phosphatase (ALP activity, and changes in gene expression by qPCR. Compared to BG-PLG scaffolds, HA-PLG and TCP-PLG composite scaffolds possessed greater compressive moduli. NHOsts on BG-PLG substrates exhibited higher ALP activity than those on control, HA-, or TCP-PLG scaffolds after 21 days, and cells on composites exhibited a 3-fold increase in ALP activity between 7 and 21 days versus a minimal increase on control scaffolds. Compared to cells on PLG controls, RUNX2 expression in NHOsts on composite scaffolds was lower at both 7 and 21 days, while expression of genes encoding for bone matrix proteins (COL1A1 and SPARC was higher on BG-PLG scaffolds at both time points. These data demonstrate the importance of selecting a ceramic when fabricating composites applied for bone healing.

  10. Economical Fabrication of Thick-Section Ceramic Matrix Composites

    Science.gov (United States)

    Babcock, Jason; Ramachandran, Gautham; Williams, Brian; Benander, Robert

    2010-01-01

    A method was developed for producing thick-section [>2 in. (approx.5 cm)], continuous fiber-reinforced ceramic matrix composites (CMCs). Ultramet-modified fiber interface coating and melt infiltration processing, developed previously for thin-section components, were used for the fabrication of CMCs that were an order of magnitude greater in thickness [up to 2.5 in. (approx.6.4 cm)]. Melt processing first involves infiltration of a fiber preform with the desired interface coating, and then with carbon to partially densify the preform. A molten refractory metal is then infiltrated and reacts with the excess carbon to form the carbide matrix without damaging the fiber reinforcement. Infiltration occurs from the inside out as the molten metal fills virtually all the available void space. Densification to 41 ksi (approx. 283 MPa) flexural strength.

  11. Diode-pumped multilayer Yb:YAG composite ceramic laser

    International Nuclear Information System (INIS)

    All-ceramic multilayer composite ytterbium doped yttrium aluminum garnet (Yb:YAG) laser gain medium with doping concentration distribution of 0-5-10-15-20-15-10-5-0 at.% Yb ions was successfully fabrication by the technique of tape casting and simple vacuum sintering process. Full dense microstructure is achieved, and excellent optical properties are gained. The obtained result shows that the optical transmittance of >80% is reached when the wavelength is larger than 500 nm. The emission cross section is 4.03×10-20 cm2 at the wavelength of 1030 nm. Continuous wave (CW) laser performance is further demonstrated when the sample is pumped by 940 nm fiber-coupler diode laser. The threshold absorbed pump power is 5.9 W, and the slope efficiency attains to 27% with transmission of output coupler of 6%

  12. Composite Coatings with Ceramic Matrix Including Nanomaterials as Solid Lubricants for Oil-Less Automotive Applications

    Directory of Open Access Journals (Sweden)

    Posmyk A.

    2016-06-01

    Full Text Available The paper presents the theoretical basis of manufacturing and chosen applications of composite coatings with ceramic matrix containing nanomaterials as a solid lubricant (AHC+NL. From a theoretical point of view, in order to reduce the friction coefficient of sliding contacts, two materials are required, i.e. one with a high hardness and the other with low shear strength. In case of composite coatings AHC+NL the matrix is a very hard and wear resistant anodic oxide coating (AHC whereas the solid lubricant used is the nanomaterial (NL featuring a low shear strength such as glassy carbon nanotubes (GC. Friction coefficient of cast iron GJL-350 sliding against the coating itself is much higher (0.18-0.22 than when it slides against a composite coating (0.08-0.14. It is possible to reduce the friction due to the presence of carbon nanotubes, or metal nanowires.

  13. Microstructures and Composition of Ceramic Coatings on Aluminum Produced by Micro-Arc Oxidation

    Institute of Scientific and Technical Information of China (English)

    SHEN De-jiu; WANG Yu-lin; GU Wei-chao; XING Guang-zhong

    2004-01-01

    Microstructures and phase composition of the ceramic coatings formed on pure aluminum by heteropolar pulsed current ceramic synthesizing system for different periods were investigated by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Results show that the amount of the discharge channels in the ceramic coating sminish while the aperture largen in the micro-arc oxidation process, and the surface of the ceramic coatingmelted and solidified in the process.XRD studies of ceramic coatings deposited for different time show that these coatings consist mainly of α-Al2 O3, γ-Al2 O3 , θ-Al2 O3 and a little amorphous phase, and phase composition of compact and porous ceramic coatings don' t have much difference but have a little change of the content of α-Al2 O3 and amorphous phase.

  14. The Fabrication and Characterization of PCL/Rice Husk Derived Bioactive Glass-Ceramic Composite Scaffolds

    Directory of Open Access Journals (Sweden)

    Farnaz Naghizadeh

    2014-01-01

    Full Text Available The present study was conducted to fabricate a 3D scaffold using polycaprolactone (PCL and silicate based bioactive glass-ceramic (R-SBgC. Different concentrations of R-SBgC prepared from rice husk ash (RHA were combined with PCL to fabricate a composite scaffold using thermally induced phase separation (TIPS method. The products were then characterized using SEM and EDX. The results demonstrated that R-SBgC in PCL matrix produced a bioactive material which has highly porous structure with interconnected porosities. There appears to be a relationship between the increase in R-SBgC concentration and increased material density and compressive modulus; however, increasing R-SBgC concentration result in reduced scaffold porosity. In conclusion, it is possible to fabricate a PCL/bioactive glass-ceramic composite from processed rice husk. Varying the R-SBgC concentrations can control the properties of this material, which is useful in the development of the ideal scaffold intended for use as a bone substitute in nonload bearing sites.

  15. Synthesizing Smart Polymeric and Composite Materials

    Science.gov (United States)

    Gong, Chaokun

    Smart materials have been widely investigated to explore new functionalities unavailable to traditional materials or to mimic the multifunctionality of biological systems. Synthetic polymers are particularly attractive as they already possess some of the attributes required for smart materials, and there are vast room to further enhance the existing properties or impart new properties by polymer synthesis or composite formulation. In this work, three types of smart polymer and composites have been investigated with important new applications: (1) healable polymer composites for structural application and healable composite conductor for electronic device application; (2) conducting polymer polypyrrole actuator for implantable medical device application; and (3) ferroelectric polymer and ceramic nanoparticles composites for electrocaloric effect based solid state refrigeration application. These application entail highly challenging materials innovation, and my work has led to significant progress in all three areas. For the healable polymer composites, well known intrinsically healable polymer 2MEP4F (a Diels-Alder crosslinked polymer formed from a monomer with four furan groups and another monomer with two maleimide groups) was first chosen as the matrix reinforced with fiber. Glass fibers were successfully functionalized with maleimide functional groups on their surface. Composites from functionalized glass fibers and 2MEP4F healable polymer were made to compare with composites made from commercial carbon fibers and 2MEP4F polymer. Dramatically improved short beam shear strength was obtained from composite of functionalized glass fibers and 2MEP4F polymer. The high cost of 2MEP4F polymer can potentially limit the large-scale application of the developed healable composite, we further developed a new healable polymer with much lower cost. This new polymer was formed through the Diels-Alder crosslinking of poly(furfuryl alcohol) (PFA) and 1,1'-(Methylenedi-4

  16. Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic: Leaching, bioactivity and cytocompatibility

    Energy Technology Data Exchange (ETDEWEB)

    Verné, Enrica, E-mail: enrica.verne@polito.it [Institute of Materials Physics and Engineering, Applied Science and Technology Department, Politecnico di Torino, C. so Duca degli Abruzzi 24, 10129 Torino (Italy); Bruno, Matteo [Institute of Materials Physics and Engineering, Applied Science and Technology Department, Politecnico di Torino, C. so Duca degli Abruzzi 24, 10129 Torino (Italy); Miola, Marta [Institute of Materials Physics and Engineering, Applied Science and Technology Department, Politecnico di Torino, C. so Duca degli Abruzzi 24, 10129 Torino (Italy); Department of Health Sciences, Università del Piemonte Orientale “Amedeo Avogadro”, Via Solaroli 17, 28100 Novara (Italy); Maina, Giovanni; Bianco, Carlotta [Traumatology Orthopedics and Occupational Medicine Dept., Università di Torino, Via G. Zuretti 29, 10126 Torino (Italy); Cochis, Andrea [Department of Health Sciences, Università del Piemonte Orientale “Amedeo Avogadro”, Via Solaroli 17, 28100 Novara (Italy); Rimondini, Lia [Department of Health Sciences, Università del Piemonte Orientale “Amedeo Avogadro”, Via Solaroli 17, 28100 Novara (Italy); Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti, 9, 50121 Firenze (Italy)

    2015-08-01

    In this work, composite bone cements, based on a commercial polymethylmethacrylate matrix (Palamed®) loaded with ferrimagnetic bioactive glass-ceramic particles (SC45), were produced and characterized in vitro. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO{sub 2}–Na{sub 2}O–CaO–P{sub 2}O{sub 5}–FeO–Fe{sub 2}O{sub 3} and contains magnetite (Fe{sub 3}O{sub 4}) crystals into a residual amorphous bioactive phase. Three different formulations (containing 10, 15 and 20 wt.% of glass-ceramic particles respectively) have been investigated. These materials are intended to be applied as bone fillers for the hyperthermic treatment of bone tumors. The morphological, compositional, calorimetric and mechanical properties of each formulation have been already discussed in a previous paper. The in vitro properties of the composite bone cements described in the present paper are related to iron ion leaching test (by graphite furnace atomic absorption spectrometer), bioactivity (i.e. the ability to stimulate the formation of a hydroxyapatite – HAp – layer on their surface after soaking in simulated body fluid SBF) and cytocompatibility toward human osteosarcoma cells (ATCC CRL-1427, Mg63). Morphological and chemical characterizations by scanning electron microscopy and energy dispersion spectrometry have been performed on the composite samples after each test. The iron release was negligible and all the tested samples showed the growth of HAp on their surface after 28 days of immersion in a simulated body fluid (SBF). Cells showed good viability, morphology, adhesion, density and the ability to develop bridge-like structures on all investigated samples. A synergistic effect between bioactivity and cell mineralization was also evidenced. - Highlights: • An in vitro biological characterization was carried out on ferromagnetic and bioactive composite cements. • No release of iron was revealed in the physiological solution. • Bioactivity tests

  17. Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic: Leaching, bioactivity and cytocompatibility

    International Nuclear Information System (INIS)

    In this work, composite bone cements, based on a commercial polymethylmethacrylate matrix (Palamed®) loaded with ferrimagnetic bioactive glass-ceramic particles (SC45), were produced and characterized in vitro. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO2–Na2O–CaO–P2O5–FeO–Fe2O3 and contains magnetite (Fe3O4) crystals into a residual amorphous bioactive phase. Three different formulations (containing 10, 15 and 20 wt.% of glass-ceramic particles respectively) have been investigated. These materials are intended to be applied as bone fillers for the hyperthermic treatment of bone tumors. The morphological, compositional, calorimetric and mechanical properties of each formulation have been already discussed in a previous paper. The in vitro properties of the composite bone cements described in the present paper are related to iron ion leaching test (by graphite furnace atomic absorption spectrometer), bioactivity (i.e. the ability to stimulate the formation of a hydroxyapatite – HAp – layer on their surface after soaking in simulated body fluid SBF) and cytocompatibility toward human osteosarcoma cells (ATCC CRL-1427, Mg63). Morphological and chemical characterizations by scanning electron microscopy and energy dispersion spectrometry have been performed on the composite samples after each test. The iron release was negligible and all the tested samples showed the growth of HAp on their surface after 28 days of immersion in a simulated body fluid (SBF). Cells showed good viability, morphology, adhesion, density and the ability to develop bridge-like structures on all investigated samples. A synergistic effect between bioactivity and cell mineralization was also evidenced. - Highlights: • An in vitro biological characterization was carried out on ferromagnetic and bioactive composite cements. • No release of iron was revealed in the physiological solution. • Bioactivity tests show hydroxyapatite precipitates on the cement

  18. Colour variations in graffiti-proofed ceramic materials

    Directory of Open Access Journals (Sweden)

    García Santos, A.

    2005-06-01

    Full Text Available The investigation analyses the variation of superficial properties, COLOUR and LUMINOSITY, hat the ceramic support protected by the incorporation of a protection with transparent painting undergoes, antigraffiti. The test pieces were analysed by digital procedures, obtaining quantifiable values of each ceramic sample by means of computer programs (modifications of colour taking itself as it bases the same type of ceramics without protection. In the surface of the pieces ceramics dealt with painting antigraffiti, tones different from the original ones were observed from the piece without painting. The type of painting and the material of base, obtaining itself the following results, determine this variation: - The rustic ceramics is much more susceptible to modify its characteristics of colour that the industrialists. - In both types of analysed industrial ceramics in the investigation, the variation of the tone independently took place with the same characteristics or parameters of quantification of the type of painting. - In all the analysed types of ceramics dealt with painting antigraffiti, the colour modifies its tonality tending towards the called tones «cold», violates, by the presence of blue and the loss of the red one. Before a same painting, it was observed a greater alteration of tones and luminosity in the rustic ceramics in comparison with the industrialists.

    Se analiza la variación de propiedades superficiales, COLOR Y LUMINOSIDAD, que sufre el soporte cerámico protegido por la incorporación de una protección con pintura transparente, antigraffiti. Las probetas fueron analizadas por procedimientos digitales, obteniéndose valores cuantificables de cada muestra cerámica mediante programas de ordenador (modificaciones de color, tomándose como base el mismo tipo de cerámica sin protección. En la superficie de las piezas cerámicas tratadas con pintura antigraffiti, se observaron tonos distintos a los originales de la

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

    International Nuclear Information System (INIS)

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

  20. 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.

  1. Preparation of metal-ceramic composites by sonochemical synthesis of metallic nano-particles and in-situ decoration on ceramic powders.

    Science.gov (United States)

    Poulia, A; Sakkas, P M; Kanellopoulou, D G; Sourkouni, G; Legros, C; Argirusis, Chr

    2016-07-01

    Copper and nickel nanoparticles were synthesized using reducing agents in the presence of direct high energy ultra-sonication. The metallic nanoparticles were decorated on various ceramic substrates (e.g. α-Al2O3, and TiO2) leading to metal reinforced ceramics with up to 45% metallic content. Different parameters, such as the amount of precursor material or the substrate, as well as the intensity of ultrasound were examined, in order to evaluate the percentage of final metallic decoration on the composite materials. All products were characterized by means of Inductively Coupled Plasma Spectroscopy in order to investigate the loading with metallic particles. X-ray Diffraction and Scanning Electron Microscopy were also used for further sample characterization. Selected samples were examined using Transmission Electron Microscopy, while finally, some of the powders synthesized, were densified by means of Spark Plasma Sintering, followed by a SEM/EDX examination and an estimation of their porosity. PMID:26964967

  2. Composite bone cements loaded with a bioactive and ferrimagnetic glass-ceramic: Leaching, bioactivity and cytocompatibility.

    Science.gov (United States)

    Verné, Enrica; Bruno, Matteo; Miola, Marta; Maina, Giovanni; Bianco, Carlotta; Cochis, Andrea; Rimondini, Lia

    2015-08-01

    In this work, composite bone cements, based on a commercial polymethylmethacrylate matrix (Palamed®) loaded with ferrimagnetic bioactive glass-ceramic particles (SC45), were produced and characterized in vitro. The ferrimagnetic bioactive glass-ceramic belongs to the system SiO2-Na2O-CaO-P2O5-FeO-Fe2O3 and contains magnetite (Fe3O4) crystals into a residual amorphous bioactive phase. Three different formulations (containing 10, 15 and 20 wt.% of glass-ceramic particles respectively) have been investigated. These materials are intended to be applied as bone fillers for the hyperthermic treatment of bone tumors. The morphological, compositional, calorimetric and mechanical properties of each formulation have been already discussed in a previous paper. The in vitro properties of the composite bone cements described in the present paper are related to iron ion leaching test (by graphite furnace atomic absorption spectrometer), bioactivity (i.e. the ability to stimulate the formation of a hydroxyapatite - HAp - layer on their surface after soaking in simulated body fluid SBF) and cytocompatibility toward human osteosarcoma cells (ATCC CRL-1427, Mg63). Morphological and chemical characterizations by scanning electron microscopy and energy dispersion spectrometry have been performed on the composite samples after each test. The iron release was negligible and all the tested samples showed the growth of HAp on their surface after 28 days of immersion in a simulated body fluid (SBF). Cells showed good viability, morphology, adhesion, density and the ability to develop bridge-like structures on all investigated samples. A synergistic effect between bioactivity and cell mineralization was also evidenced. PMID:26042695

  3. Seleção de matérias-primas no desenvolvimento de formulações de massas cerâmicas Selection of raw materials in the development of ceramic bodies compositions

    Directory of Open Access Journals (Sweden)

    L. Sánchez-Muñoz

    2002-06-01

    Full Text Available A partir de argilas de uso industrial, foram estudadas por ATD, ATG, MEV e DRX as alterações mineralógicas, microestruturais e dimensionais ocorridas com o incremento da temperatura. Com os dados de absorção de água e de retração linear foram obtidos diagramas de gresificação, propondo uma metodologia de seleção de matérias-primas para aplicação a novas massas cerâmicas.Starting from clays of industrial use, the mineralogical, microestrutural and dimensional alterations for increasing temperatures were studied by Differential Thermal Analysis, Thermogravimetric Analysis, Scanning Electron Microscopy and X-Ray Diffraction. Vitrification diagrams were obtained from water absorption and linear shrinkage data, a methodology of selection of raw materials for application to new ceramic bodies being proposed.

  4. Composite magnetostrictive materials for advanced automotive magnetomechanical sensors

    International Nuclear Information System (INIS)

    In this paper we present the development of a composite magnetostrictive material for automotive applications. The material is based on cobalt ferrite, CoO centre dot Fe2O3, and contains a small fraction of metallic matrix phase that serves both as a liquid phase sintering aid during processing and enhances the mechanical properties over those of a simple sintered ferrite ceramic. In addition the metal matrix makes it possible to braze the material making the assembly of a sensor relatively simple. The material exhibits good sensitivity and should have high corrosion resistance while at the same time it is low cost

  5. Aluminium EN AC-AlSi12 alloy matrix composite materials reinforced by Al2O3 porous preforms

    OpenAIRE

    Nagel, A.; M. Kremzer; L.A. Dobrzański,

    2007-01-01

    Purpose: The purpose of this work is to elaborate the method of manufacturing of composite materials based on porous ceramic preforms infiltrated by eutectic aluminium alloy.Design/methodology/approach: The material for investigations was fabricated by pressure infiltration method of ceramic porous preforms. The eutectic aluminium alloy EN AC – AlSi12 was use as a matrix while as reinforcement were used ceramic preforms fabricated by sintering of Al2O3 Alcoa CL 2500 powder with addition of po...

  6. Genetic Homogenization of Composite Materials

    Directory of Open Access Journals (Sweden)

    P. Tobola

    2009-04-01

    Full Text Available The paper is focused on numerical studies of electromagnetic properties of composite materials used for the construction of small airplanes. Discussions concentrate on the genetic homogenization of composite layers and composite layers with a slot. The homogenization is aimed to reduce CPU-time demands of EMC computational models of electrically large airplanes. First, a methodology of creating a 3-dimensional numerical model of a composite material in CST Microwave Studio is proposed focusing on a sufficient accuracy of the model. Second, a proper implementation of a genetic optimization in Matlab is discussed. Third, an association of the optimization script and a simplified 2-dimensional model of the homogeneous equivalent model in Comsol Multiphysics is proposed considering EMC issues. Results of computations are experimentally verified.

  7. Validation of new ceramic materials from tungsten mining wastes. Mechanical properties; Validacion de nuevos materiales ceramicos a partir de rocas de desecho de mineria. Propiedades mecanicas

    Energy Technology Data Exchange (ETDEWEB)

    Duran Suarez, J. A.; Montoya Herrera, J.; Silva, A. P.; Peralbo Cano, R.; Castro-Gomes, J. P.

    2014-07-01

    New ceramic materials obtained from tungsten mining wastes, from region of Beira Interior in Portugal, with no commercial use, responsible for landscape and environmental problems are presented. These preshaped new ceramic products, prepared in a wide thermal range (800 degree centigrade to 1300 degree centigrade) was evaluated by mechanical test, but also was characterized the starting raw materials: tungsten wastes mining and industrial kaolin. Results, which also include a mineralogical characterization of ceramic products and morphologic evaluation of neoformed by scanning electron microscopy, show firstly, the feasibility of converting a large number of these wastes in marketable ceramics. Thanks to the experimentation carried out, the ability to generate ceramic materials is emphasized, without the presence of mineral clay, due to the particular composition of these waste of mining with content of acid, neutral and basic oxides. (Author)

  8. Sintered composite gradient tool materials

    OpenAIRE

    J. Mikuła; G. Matula; K. Gołombek; L.A. Dobrzański

    2008-01-01

    Purpose: Development of a new generation of the composite gradient tool materials with the core sintered withthe matrix obtained using the powder metallurgy of the chemical composition corresponding to the HS6-5-2 highspeedsteel reinforced with the WC and TiC type hard carbide phases with the growing portions of these phases inthe outward direction from the core to the surface.Design/methodology/approach: Powder Metallurgy, SEM, X-Ray Microanalysis.Findings: Powder metallurgy processes were u...

  9. Fracture problems in composite materials

    Science.gov (United States)

    Erdogan, F.

    1972-01-01

    A series of fracture problems in composite materials are identified, their methods of solution are briefly discussed, and some sample results are presented. The main problem of interest is the determination of the stress state in the neighborhood of localized imperfections such as cracks and inclusions which may exist in the composite. Particular emphasis is placed on the evaluation of quantities such as the stress intensity factors, the power of the stress singularity, and the strain energy release rate, which may be used directly or indirectly in connection with an appropriate fracture criterion for the prediction of fracture initiation and propagation load levels. The topics discussed include a crack in layered composites, a crack terminating at and going through a bi-material interface, a penny-shaped crack in a filament-reinforced elastic matrix, and inclusion problems in bonded materials.

  10. Effects of neutron irradiation on glass ceramics as pressure-less joining materials for SiC based components for nuclear applications

    Czech Academy of Sciences Publication Activity Database

    Ferraris, M.; Casalegno, V.; Rizzo, S.; Salvo, M.; Van Staveren, T.O.; Matějíček, Jiří

    2012-01-01

    Roč. 429, 1-3 (2012), s. 166-172. ISSN 0022-3115 R&D Projects: GA MPO 2A-1TP1/101 Institutional research plan: CEZ:AV0Z20430508 Keywords : glass-ceramic * joining * SiC composites * fusion materials Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.211, year: 2012 http://www.sciencedirect.com/science/article/pii/S0022311512002668

  11. Fast, Contactless Monitoring of the Chemical Composition of Raw Materials

    Science.gov (United States)

    Ivanov, O.; Stoyanov, Zh.; Stoyanov, B.; Nadoliisky, M.; Vaseashta, Ashok

    A technique to monitor chemical composition of materials during manufacturing of ceramic products, in particular - of bricks, is investigated. The technique of monitoring is likely to offset environmental pollution and save energy. For this purpose, we use the Surface photo charge effect, which is generated for each solid body interacting with electromagnetic field. The measurement is express and can be performed in-situ in production conditions. The experimental work has shown that different samples of the investigated materials with different compositions produce different signals specific to each sample. For the same material, the signal varies with the change in chemical composition. More specifically, it is shown that for the material from which the bricks are fired, the signal is a function of the percentage of coal sludge. The results indicate that the characterization technique as a viable technique for control of incoming raw materials.

  12. Life Prediction/Reliability Data of Glass-Ceramic Material Determined for Radome Applications

    Science.gov (United States)

    Choi, Sung R.; Gyekenyesi, John P.

    2002-01-01

    Brittle materials, ceramics, are candidate materials for a variety of structural applications for a wide range of temperatures. However, the process of slow crack growth, occurring in any loading configuration, limits the service life of structural components. Therefore, it is important to accurately determine the slow crack growth parameters required for component life prediction using an appropriate test methodology. This test methodology also should be useful in determining the influence of component processing and composition variables on the slow crack growth behavior of newly developed or existing materials, thereby allowing the component processing and composition to be tailored and optimized to specific needs. Through the American Society for Testing and Materials (ASTM), the authors recently developed two test methods to determine the life prediction parameters of ceramics. The two test standards, ASTM 1368 for room temperature and ASTM C 1465 for elevated temperatures, were published in the 2001 Annual Book of ASTM Standards, Vol. 15.01. Briefly, the test method employs constant stress-rate (or dynamic fatigue) testing to determine flexural strengths as a function of the applied stress rate. The merit of this test method lies in its simplicity: strengths are measured in a routine manner in flexure at four or more applied stress rates with an appropriate number of test specimens at each applied stress rate. The slow crack growth parameters necessary for life prediction are then determined from a simple relationship between the strength and the applied stress rate. Extensive life prediction testing was conducted at the NASA Glenn Research Center using the developed ASTM C 1368 test method to determine the life prediction parameters of a glass-ceramic material that the Navy will use for radome applications.

  13. Radiation Facilities for Composite Materials Formation

    Science.gov (United States)

    Popov, G. F.; Zalubovsky, I. I.; Avilov, A. M.; Rudychev, V. G.

    1997-05-01

    The radiation facilities on the base of linac for polymer composite materials (PCM) formation was designed. The general technological scheme of PCM production consists in impregnations by synthetic monomers or oligomers of wares made of capillaryporous materials such as wood, qypsum, concrete, ceramic, paper, waste of papermaking, textile and woodworking production which are further treated by relativistic electron or breamsstruhglung beams. The facilities encorporates a linac with scanning electron beams, microwave chamber for drying of materials, a system for vacuum impregnating of materials with synthetic origomers, test bench for irradiations of samples, precise monitoring system for measuring of three-dimentional dose distribution in irradiated samples, and control processing system. The main beam parameters of linac are: electron energy 5--8 MeV; mean beam power up to 5 kW, pulse duration 1--4 mcs; scanning frequency of electromagnetic scanner 1--8 Hz; the irradiation is possible both with electron and with breamsstrahglung beams. The facilities were used for radiation processing investigation and production of new high-strength and corrosian-resistant PCM.

  14. Lightweight, Thermally Conductive Composite Material

    Science.gov (United States)

    Sharp, G. Richard; Loftin, Timothy A.

    1990-01-01

    Aluminum reinforced with carbon fibers superior to copper in some respects. Lightweight composite material has high thermal conductivity. Consists of aluminum matrix containing graphite fibers, all oriented in same direction. Available as sheets, tubes, and bars. Thermal conductivity of composite along fibers rises above that of pure copper over substantial range of temperatures. Graphite/aluminum composite useful in variety of heat-transfer applications in which reduction of weight critical. Used to conduct heat in high-density, high-speed integrated-circuit packages for computers and in base plates for electronic equipment. Also used to carry heat away from leading edges of wings in high-speed airplanes.

  15. Lightweight Ablative and Ceramic Thermal Protection System Materials for NASA Exploration Systems Vehicles

    Science.gov (United States)

    Valentine, Peter G.; Lawrence, Timothy W.; Gubert, Michael K.; Milos, Frank S.; Kiser, James D.; Ohlhorst, Craig W.; Koenig, John R.

    2006-01-01

    As a collaborative effort among NASA Centers, the "Lightweight Nonmetallic Thermal Protection Materials Technology" Project was set up to assist mission/vehicle design trade studies, to support risk reduction in thermal protection system (TPS) material selections, to facilitate vehicle mass optimization, and to aid development of human-rated TPS qualification and certification plans. Missions performing aerocapture, aerobraking, or direct aeroentry rely on advanced heatshields that allow reductions in spacecraft mass by minimizing propellant requirements. Information will be presented on candidate materials for such reentry approaches and on screening tests conducted (material property and space environmental effects tests) to evaluate viable candidates. Seventeen materials, in three classes (ablatives, tiles, and ceramic matrix composites), were studied. In additional to physical, mechanical, and thermal property tests, high heat flux laser tests and simulated-reentry oxidation tests were performed. Space environmental effects testing, which included exposures to electrons, atomic oxygen, and hypervelocity impacts, was also conducted.

  16. Synthesis and mechanical characterization of PZT/Sr based composite ceramics with addition of Si3N4

    International Nuclear Information System (INIS)

    In the Underwater Acoustics field, piezoelectric ceramics are the most usually employed materials for the conversion of mechanical energy (acoustic signal) into electric energy (electric signal) and vice-versa, in sensors (hydrophones) or hydroacoustic projectors. In the development of new compositions for these applications, piezoelectric performance is generally prioritized, to the expense of its mechanical properties. With this in mind, the object of this work was to study the effects of the addition of Si3N4 in the mechanical properties of PZT-Sr based electronic ceramics. Thus, a novel piezoelectric ceramic with the addition of small percentages in weight (0;0.1;1;3 and 5) of the structural ceramic Si3N4 was successfully processed by the oxide mixing route ; the compounds were sintered in a conventional at 1200 deg C for 2h. The densities of the compounds thus obtained for the different percentages of Si3N4 ranged from 55 to 97% and decreased with the increase of the content of Si3N4. Presence of equiaxial grains with normal growth was observed in all samples. MEV/EDS analysis of the micro-structures of the compositions detected the presence of a second phase rich in Zr, confirmed by DRX, which is a result of large quantities of volatilized PbO; the sintered pieces had their mechanical properties investigated by ultra-sonic inspection. It was observed that, among the sintered compositions, the PZT-Sr ceramic with 0.1% Si3N4 presented the smallest value for Young's Modulus E and Shear Modulus G, 75 Gpa and 28 Gpa, respectively. The Poisson's Coefficients ν tended to decrease with the increase of Si3N4 added to the PZT-Sr ceramic, indicating, thus, that the added compound may be used to adjust the mechanical properties of the material. (author)

  17. The role of characterization in emerging high performance ceramic materials

    International Nuclear Information System (INIS)

    Since the early 70's research and development efforts focusing on nitride, oxynitride, and carbide based ceramic materials have created renewed optimism concerning their potential application in severe high temperature structural applications. Cost and reliability, however, still remain as major obstacles in achieving the final successful large scale utilization of these materials. The ceramics community must now devote an appreciable effort on the less ''glamorous'' areas of those needs concerned with the maturing of an emerging technology. These aspects consist of achieving demonstrated reliability in larger scale production activities. In order to accomplish this much effort should be devoted to establishing processing optimization, design property data bases, and nondestructive or semidestructive property evaluation (NPE) procedures. As reiterated recently by Stein pull factors of need and economic gain, in general, are much more important in a free market than the technologic push factors of perceived or research scale demonstration of improved performance; analogous to pulling or pushing on a rope. Therefore, there is a strong temptation during this phase of the development to ignore this aspect and to return to more fundamental work on other, less developed, emerging materials

  18. Influence of Alumina Addition on the Optical Property of Zirconia/Alumina Composite Dental Ceramics

    Institute of Scientific and Technical Information of China (English)

    JIANG Li; LIAO Yunmao; LI Wei; WAN Qianbing; ZHAO Yongqi

    2011-01-01

    The influence of various alumina additions on the optical property of zirconia/alumina composite ceramics was investigated.The relative sintered densities,transmittances,color and the microstructure of the composite ceramics were studied.The experimental results showed that the relative sintered densities and transmittances decreased with alumina addition.The lightness increased obviously but the chroma change was small.Pure zirconia nanopowders sintered densely could obtain the relatively high transmittance,while the transmittance and the lightness of slight addition changed significantly.The zirconia/alumina composite ceramics with alumina addition less than 7.5wt% could achieve the relatively stable and reliable optical properties.

  19. Production of AlN-Si-Al Ceramic-Metal Composites via Pressurless Infiltration Method

    OpenAIRE

    KALEMTAŞ, Ayşe; ARSLAN, Gürsoy; KARA, Ferhat

    2014-01-01

    In this work, the production of light (∼2,9 g/cm3) and dense (> 99 %) AlN based ceramic metal composites was conducted by the pressureless melt infiltration method. These composites contain a high ceramic volume fraction (> 50 vol %) which is the result of the reaction between Si3N4 and Al in the Si3N4-Al system. The production of the ceramic-metal composites was achieved via infiltrating 2024 Al alloys at different temperatures and holding times into the porous pellets which were prepared us...

  20. Lightweight Ceramic Composition of Carbon Silicon Oxygen and Boron

    Science.gov (United States)

    Leiser, Daniel B. (Inventor); Hsu, Ming-Ta (Inventor); Chen, Timothy S. (Inventor)

    1997-01-01

    Lightweight, monolithic ceramics resistant to oxidation in air at high temperatures are made by impregnating a porous carbon preform with a sol which contains a mixture of tetraethoxysilane, dimethyldiethoxysilane and trimethyl borate. The sol is gelled and dried on the carbon preform to form a ceramic precursor. The precursor is pyrolyzed in an inert atmosphere to form the ceramic which is made of carbon, silicon, oxygen and boron. The carbon of the preform reacts with the dried gel during the pyrolysis to form a component of the resulting ceramic. The ceramic is of the same size, shape and form as the carbon precursor. Thus, using a porous, fibrous carbon precursor, such as a carbon felt, results in a porous, fibrous ceramic. Ceramics of the invention are useful as lightweight tiles for a reentry spacecraft.