WorldWideScience

Sample records for based glass ceramics

  1. Wastes based glasses and glass-ceramics

    Directory of Open Access Journals (Sweden)

    Barbieri, L.

    2001-12-01

    Full Text Available Actually, the inertization, recovery and valorisation of the wastes coming from municipal and industrial processes are the most important goals from the environmental and economical point of view. An alternative technology capable to overcome the problem of the dishomogeneity of the raw material chemical composition is the vitrification process that is able to increase the homogeneity and the constancy of the chemical composition of the system and to modulate the properties in order to address the reutilization of the waste. Moreover, the glasses obtained subjected to different controlled thermal treatments, can be transformed in semy-cristalline material (named glass-ceramics with improved properties with respect to the parent amorphous materials. In this review the tailoring, preparation and characterization of glasses and glass-ceramics obtained starting from municipal incinerator grate ash, coal and steel fly ashes and glass cullet are described.

    Realmente la inertización, recuperación y valorización de residuos que proceden de los procesos de incineración de residuos municipales y de residuos industriales son metas importantes desde el punto de vista ambiental y económico. Una tecnología alternativa capaz de superar el problema de la heterogeneidad de la composición química de los materiales de partida es el proceso de la vitrificación que es capaz de aumentar la homogeneidad y la constancia de la composición química del sistema y modular las propiedades a fin de la reutilización del residuo. En este artículo se presentan los resultados de vitrificación en que los vidrios fueron sometidos a tratamientos térmicos controlados diferentes, de manera que se transforman en materiales semicristalinos (también denominados vitrocerámicos con mejores propiedades respecto a los materiales amorfos originales. En esta revisión se muestra el diseño, preparación y caracterización de vidrios y vitrocerámicos partiendo de

  2. Crack tip fracture toughness of base glasses for dental restoration glass-ceramics using crack opening displacements.

    Science.gov (United States)

    Deubener, J; Höland, M; Höland, W; Janakiraman, N; Rheinberger, V M

    2011-10-01

    The critical stress intensity factor, also known as the crack tip toughness K(tip), was determined for three base glasses, which are used in the manufacture of glass-ceramics. The glasses included the base glass for a lithium disilicate glass-ceramic, the base glass for a fluoroapatite glass-ceramic and the base glass for a leucite glass-ceramic. These glass-ceramic are extensively used in the form of biomaterials in restorative dental medicine. The crack tip toughness was established by using crack opening displacement profiles under experimental conditions. The crack was produced by Vickers indentation. The crack tip toughness parameters determined for the three glass-ceramics differed quite significantly. The crack tip parameters of the lithium disilicate base glass and the leucite base glass were higher than that of the fluoroapatite base glass. This last material showed glass-in-glass phase separation. The discussion of the results clearly shows that the droplet glass phase is softer than the glass matrix. Therefore, the authors conclude that a direct relationship exists between the chemical nature of the glasses and the crack tip parameter.

  3. Fractographic features of glass-ceramic and zirconia-based dental restorations fractured during clinical function

    OpenAIRE

    Øilo, Marit; Hardang, Anne Dybdahl; Ulsund, Amanda Hembre; Gjerdet, Nils Roar

    2014-01-01

    Fractures during clinical function have been reported as the major concern associated with all-ceramic dental restorations. The aim of this study was to analyze the fracture features of glass-ceramic and zirconia-based restorations fractured during clinical use. Twenty-seven crowns and onlays were supplied by dentists and dental technicians with information about type of cement and time in function, if available. Fourteen lithium disilicate glass-ceramic restorations and 13 zirconia-based res...

  4. Crystallisation Kinetics of a β-Spodumene-Based Glass Ceramic

    Directory of Open Access Journals (Sweden)

    Oscar Rubem Klegues Montedo

    2012-01-01

    Full Text Available LZSA (Li2O-ZrO2-SiO2-Al2O3 glass ceramic system has shown high potential to obtain LTCC laminate tapes at low sintering temperature (<1000°C for several applications, such as screen-printed electronic components. Furthermore, LZSA glass ceramics offer interesting mechanical, chemical, and thermal properties, which make LZSA also a potential candidate for fabricating multilayered structures processed by Laminated Objects Manufacturing (LOM technology. The crystallization kinetics of an LZSA glass ceramic with a composition of 16.9Li2O⋅5.0ZrO2⋅65.1SiO2⋅8.6Al2O3 was investigated using nonisothermal methods by differential thermal analysis and scanning electronic microscopy. Apparent activation energy for crystallization was found to be in the 274–292 kJ⋅mol−1 range, and an Avrami parameter n of 1 was obtained that is compared very favorably with SEM observations.

  5. Diopside-fluorapatite-wollastonite based bioactive glasses and glass-ceramics

    OpenAIRE

    Kansal, Ishu

    2015-01-01

    Bioactive glasses and glass–ceramics are a class of biomaterials which elicit special response on their surface when in contact with biological fluids, leading to strong bonding to living tissue. This particular trait along with good sintering ability and high mechanical strength make them ideal materials for scaffold fabrication. The work presented in this thesis is directed towards understanding the composition-structure-property relationships in potentially bioactive glasses...

  6. Immobilization of gadolinium in iron borophosphate glasses and iron borophosphate based glass-ceramics: Implications for the immobilization of plutonium(Ⅲ)

    Science.gov (United States)

    Wang, Fu; Liao, Qilong; Dai, Yunya; Zhu, Hanzhen

    2016-08-01

    Immobilization of gadolinium (Gd), a nonradioactive surrogate for Pu3+, in iron borophosphate glasses/glass-ceramics (IBP glasses/glass-ceramics) has been investigated. The IBP glass containing 4 mol% Gd2O3 is homogeneously amorphous. At higher Gd2O3 concentrations, additional Gd is retained in the glasses as crystalline inclusions of monazite GdPO4 crystalline phase detected with X-ray diffraction. Moreover, Gd2O3 addition increases the Tg of the IBP glasses in glass formation range, which is consistent with the structural modification of the glasses. The structure of the Gd2O3-loaded IBP glasses/glass-ceramics is mainly based on pyrophosphate units. The chemical durability of Gd2O3-loaded IBP glasses/glass-ceramics is comparable to widely used borosilicate glass waste forms and the existence of monazite GdPO4 crystalline phase does not degrade the aqueous chemical durability of the IBP glasses/glass-ceramics. The Gd-loading results imply that the solubility should not be a limiting factor in processing nuclide Pu3+ if the formed crystalline phase(s) have high chemical durability.

  7. Corrosion Behavior of SnO2-based Electrode Ceramics in Soda-lime Glass Liquid

    International Nuclear Information System (INIS)

    Dense SnO2-based electrode ceramics have extensive application prospect in glass electric-melting industry due to the excellent electrically-conductive and chemical property in high temperatures and oxidation environment. In this paper, dense SnO2-based electrode ceramics doped with MnO2 and Sb2O3 were prepared by pressureless sintering method and the corrosion rate in soda-lime glass liquid as well as the microstructure evolution was mainly investigated. The results suggested that SnO2-based ceramics had good corrosion resistance, and the minimum value was only 2.54x10-4 mm/h when MnO2 content is 1.0% and Sb2O3 content is 0.1%. Composition Elements of Glass liquid were detected in the grain boundary and some intergranular pores. It was found that SnO2 grains remained unchanged, whereas MnO2 was easily dissolved into molten glass liquid. SnO2-based electrode ceramics with dense structure and few amounts of additives had excellent corrosion resistance to the molten glass.

  8. Experimental Study on LTCC Glass-Ceramic Based Dual Segment Cylindrical Dielectric Resonator Antenna

    Directory of Open Access Journals (Sweden)

    Ravi Kumar Gangwar

    2013-01-01

    Full Text Available The measured characteristics in C/X bands, including material properties of a dual segment cylindrical dielectric resonator antenna (CDRA fabricated from glass-ceramic material based on B2O3–La2O3–MgO glass and La(Mg0.5Ti0.5O3 ceramic, are reported. The sintering characteristic of the ceramic in presence of glass is determined from contact angle measurement and DTA. The return loss and input impedance versus frequency characteristics and radiation patterns of CDRA at its resonant frequency of 6.31 GHz are studied. The measured results for resonant frequency and return loss bandwidth of the CDRA are also compared with corresponding theoretical ones.

  9. Nucleation and crystallization of tailing-based glass-ceramics by microwave heating

    Institute of Scientific and Technical Information of China (English)

    Bao-wei Li; Hong-xia Li; Xue-feng Zhang; Xiao-lin Jia; Zhi-chao Sun

    2015-01-01

    The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared from Shandong gold tailings and Guyang iron tailings utilizing a conventional glass melting technique. For comparison, the tailing-based glass samples were crystallized using two different heat-treatment meth-ods:conventional heating and hybrid microwave heating. The nucleation and crystallization temperatures were determined by performing a dif-ferential thermal analysis of the quenched tailing-based glass. The prepared glass-ceramic samples were further characterized by Fourier trans-form infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermal expansion coefficient measurements, and scanning electron micros-copy. The results demonstrated that hybrid microwave heating could be successfully used to crystallize the tailing-based glass, reduce the proc-essing time, and decrease the crystallization temperature. Furthermore, the results indicated that the nucleation and crystallization mechanism of the hybrid microwave heating process slightly differs from that of the conventional heating process.

  10. Nucleation and crystallization of tailing-based glass-ceramics by microwave heating

    Science.gov (United States)

    Li, Bao-wei; Li, Hong-xia; Zhang, Xue-feng; Jia, Xiao-lin; Sun, Zhi-chao

    2015-12-01

    The effect of microwave radiation on the nucleation and crystallization of tailing-based glass-ceramics was investigated using a 2.45 GHz multimode microwave cavity. Tailing-based glass samples were prepared from Shandong gold tailings and Guyang iron tailings utilizing a conventional glass melting technique. For comparison, the tailing-based glass samples were crystallized using two different heat-treatment methods: conventional heating and hybrid microwave heating. The nucleation and crystallization temperatures were determined by performing a differential thermal analysis of the quenched tailing-based glass. The prepared glass-ceramic samples were further characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, thermal expansion coefficient measurements, and scanning electron microscopy. The results demonstrated that hybrid microwave heating could be successfully used to crystallize the tailing-based glass, reduce the processing time, and decrease the crystallization temperature. Furthermore, the results indicated that the nucleation and crystallization mechanism of the hybrid microwave heating process slightly differs from that of the conventional heating process.

  11. Microstructural studies on some silicate and phosphate based glass-ceramics

    International Nuclear Information System (INIS)

    Recent developments have made it possible to make a new class of ceramic materials called glass-ceramics with tailored expansion coefficients and improved thermo-mechanical and corrosion resistance properties. Since these are formed by controlled crystallization in which crystallites are embedded in the glassy matrix, it is possible to make nano glass-ceramics having pronounced effect of particle size on various properties such as transparency, bioactivity, etc. In this talk, some of the recent results on micro-structural properties of a few glass-ceramic-to-metal sealants and bio-glass-ceramics are discussed

  12. Radiopaque strontium fluoroapatite glass-ceramics

    Directory of Open Access Journals (Sweden)

    Wolfram eHöland

    2015-10-01

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

  13. Low thermal expansion glass ceramics

    CERN Document Server

    1995-01-01

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

  14. 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.

  15. Pyrochlore based glass-ceramics for the immobilization of actinide-rich nuclear wastes: From concept to reality

    Science.gov (United States)

    Zhang, Y.; Zhang, Z.; Thorogood, G.; Vance, E. R.

    2013-01-01

    Pyrochlore based glass-ceramics have been developed, from concept to reality, for the immobilization of actinide-rich nuclear wastes. Compared with zirconolite based glass-ceramics, they are less sensitive to the processing redox conditions and can double actinide waste loadings thus decreasing volumes of the consolidated waste forms, and subsequently reducing the interim storage and disposal costs. More importantly, they provide an alternative flexible system to tackle radioactive wastes arising from the advanced nuclear reactors.

  16. 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

  17. Low Thermal Expansion Glass Ceramics

    CERN Document Server

    Bach, Hans

    2005-01-01

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

  18. Reference-based optical characterization of glass-ceramic converter for high-power white LEDs

    Science.gov (United States)

    Engel, A.; Letz, M.; Zachau, T.; Pawlowski, E.; Seneschal-Merz, K.; Korb, T.; Enseling, D.; Hoppe, B.; Peuchert, U.; Hayden, J. S.

    2007-02-01

    Fluorescence techniques are known for their high sensitivity and are widely used as analytical tools and detection methods for product and process control, material sciences, environmental and bio-technical analysis, molecular genetics, cell biology, medical diagnostics and drug screening. According to DIN/ISO 17025 certified standards are used for fluorescence diagnostics having the drawback of giving relative values for fluorescence intensities only. Therefore reference materials for a quantitative characterization have to be related directly to the materials under investigation. In order to evaluate these figures it is necessary to calculate absolute numbers like absorption/excitation cross section and quantum yield. This can be done for different types of dopants in different materials like glass, glass ceramics, crystals or nano crystalline material embedded in polymer matrices. Here we consider a special type of glass ceramic with Ce doped YAG as the main crystalline phase. This material has been developed for the generation of white light realized by a blue 460 nm semiconductor transition using a yellow phosphor or converter material respectively. Our glass ceramic is a pure solid state solution for a yellow phosphor. For the production of such a kind of material a well controlled thermal treatment is employed to transfer the original glass into a glass ceramic with a specific crystalline phase. In our material Ce doped YAG crystallites of a size of several µm are embedded in a matrix of a residual glass. We present chemical, structural and spectroscopic properties of our material. Based on this we will discuss design options for white LED's with respect to heat management, scattering regime, reflection losses, chemical durability and stability against blue and UV radiation, which evolve from our recently developed material. In this paper we present first results on our approaches to evaluate quantum yield and light output. Used diagnostics are

  19. Waste glass and fly ash derived glass-ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, S.D.; Yun, Y.H. [Chonnam National University, Kwangju (Republic of Korea)

    2006-07-15

    Crystallization behavior of a waste-based glass-ceramic was studied by means of X-ray diffraction analysis, and the surface morphological observations and chemical compositions were evaluated by field emission-scanning electron microscopy and energy dispersive X-ray spectrometry. Applying the mechanical milling method, the glass-ceramic was prepared by using fly ash from a thermal power plant mixed with waste glass cullet. Powder mixtures consisting of waste glass powder (70 wt%) and fly ash (30 wt%) were used to make glass-ceramic. Various heat treatment temperatures (900, 925, 950, 975, 1000 and 1025{sup o}C) were used to obtain a glass-ceramic of the optimum crystal phase, mechanical properties and chemical durability. The X-ray diffraction analysis showed that the crystalline phases in the glass-ceramic were diopside (Ca(Mg, Al)(Si, Al){sub 2}O-6), augite (Ca(Mg, Fe)Si{sub 2}O{sub 6}) and wollastonite (CaSiO{sub 3}). The crystallization of an acicular phase in the matrix was achieved in the heat treatment temperature range of 1000-1025{sup o}C, and the acicular type main crystal phase in the glass-ceramic was wollastonite (CaSiO{sub 3}). The heat treatment temperature range (1000-1025{sup o}C) also showed much better mechanical properties.

  20. Structure, solubility and bioactivity in TiO2-doped phosphate-based bioglasses and glass-ceramics

    International Nuclear Information System (INIS)

    Phosphate-based bioactive glasses in addition to TiO2 (x = 0-2.5 mol%) were prepared by melt quenching technique. Glass-ceramics were prepared by controlled two-step thermal treatment of the as-prepared phosphate bioglasses at their nucleation and crystallisation temperatures. X-ray diffraction (XRD) analysis was used to explore the amorphous and crystalline nature of materials. The presence of calcium phosphate crystals like NaPO3, α, β-Ca2P2O7, α,β-Ca3(PO4)2 and Na5Ti(PO4)3 plays a dominant role in glass-ceramics. The structural changes were analyzed by density and Tg measurements. The degradation process in deionised water (DIW) was observed by pH and weight loss measurements. It was interesting to note that the highest solubility phosphate glasses become stiffer to degradation with increasing TiO2 content. Addition of TiO2 leads to densify the glass structure and interconnect the cross-linkages in the network. Chemical durability of glass-ceramics in DIW purely depends on the formed crystalline as well as the residual glassy phases. The formation of a biologically active layer on the surface of glasses and glass-ceramics were investigated by in vitro studies through XRD analysis.

  1. Optical thermometry based on luminescence behavior of Dy3+-doped transparent LaF3 glass ceramics

    International Nuclear Information System (INIS)

    Dy3+-doped transparent LaF3 glass ceramics were fabricated, and its structures of resulting glass ceramics are studied by the X-ray diffraction and transmission electron microscopy. Optical temperature sensing of the resulting glass ceramics in the temperature range from 298 to 523 K is studied based on the down-conversion luminescence of Dy3+ ion. By using fluorescence intensity ratio method, the 4I15/2 and 4F9/2 of Dy3+ ions are verified as thermally coupled levels. A minimum SR = 1.16 x 10-4 K-1 is obtained at T = 294 K. By doping Eu3+ ion, the overall emission color of Eu3+-Dy3+ co-doped transparent glass ceramics can be tuned from white to yellow with the temperature increase through energy transfer between Eu3+ and Dy3+. Additionally, the thermal stability of the Dy3+ single-doped transparent glass ceramics becomes higher after doping Eu3+ ion. (orig.)

  2. Optical thermometry based on luminescence behavior of Dy{sup 3+}-doped transparent LaF{sub 3} glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Bu, Y.Y. [Nanjing University of Posts and Telecommunications, College of Electronic Science and Engineering, Nanjing (China); Nanjing University of Posts and Telecommunications, College of Science, Nanjing (China); Cheng, S.J.; Wang, X.F. [Nanjing University of Posts and Telecommunications, College of Electronic Science and Engineering, Nanjing (China); Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing, Jiangsu (China); Yan, X.H. [Nanjing University of Posts and Telecommunications, College of Electronic Science and Engineering, Nanjing (China); Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing, Jiangsu (China); Nanjing University of Aeronautics and Astronautics, College of Science, Nanjing (China)

    2015-11-15

    Dy{sup 3+}-doped transparent LaF{sub 3} glass ceramics were fabricated, and its structures of resulting glass ceramics are studied by the X-ray diffraction and transmission electron microscopy. Optical temperature sensing of the resulting glass ceramics in the temperature range from 298 to 523 K is studied based on the down-conversion luminescence of Dy{sup 3+} ion. By using fluorescence intensity ratio method, the {sup 4}I{sub 15/2} and {sup 4}F{sub 9/2} of Dy{sup 3+} ions are verified as thermally coupled levels. A minimum S{sub R} = 1.16 x 10{sup -4} K{sup -1} is obtained at T = 294 K. By doping Eu{sup 3+} ion, the overall emission color of Eu{sup 3+}-Dy{sup 3+} co-doped transparent glass ceramics can be tuned from white to yellow with the temperature increase through energy transfer between Eu{sup 3+} and Dy{sup 3+}. Additionally, the thermal stability of the Dy{sup 3+} single-doped transparent glass ceramics becomes higher after doping Eu{sup 3+} ion. (orig.)

  3. Radiopaque Strontium Fluoroapatite Glass-Ceramics

    Science.gov (United States)

    Höland, Wolfram; Schweiger, Marcel; Dittmer, Marc; Ritzberger, Christian

    2015-01-01

    The controlled precipitation of strontium fluoroapatite crystals was studied in four base glass compositions derived from the SiO2–Al2O3–Y2O3–SrO–Na2O–K2O/Rb2O/Cs2O–P2O5–F system. The crystal phase formation of these glasses and the main properties of the glass-ceramics, such as thermal and optical properties and radiopacity were compared with a fifth, a reference glass-ceramic. The reference glass-ceramic was characterized as Ca-fluoroapatite glass-ceramic. The four strontium fluoroapatite glass-ceramics showed the following crystal phases: (a) Sr5(PO4)3F – leucite, KAlSi2O6, (b) Sr5(PO4)3F – leucite, KAlSi2O6, and nano-sized NaSrPO4, (c) Sr5(PO4)3F – pollucite, CsAlSi2O6, and nano-sized NaSrPO4, and (d) Sr5(PO4)3F – Rb-leucite, RbAlSi2O6, and nano-sized NaSrPO4. The proof of crystal phase formation was possible by X-ray diffraction. The microstructures, which were studied using scanning electron microscopy, demonstrated a uniform distribution of the crystals in the glass matrix. The Sr-fluoroapatites were precipitated based on an internal crystallization process, and the crystals demonstrated a needle-like morphology. The study of the crystal growth of needle-like Sr-fluoroapatites gave a clear evidence of an Ostwald ripening mechanism. The formation of leucite, pollucite, and Rb-leucite was based on a surface crystallization mechanism. Therefore, a twofold crystallization mechanism was successfully applied to develop these types of glass-ceramics. The main focus of this study was the controlled development of glass-ceramics exhibiting high radiopacity in comparison to the reference glass-ceramic. This goal could be achieved with all four glass-ceramics with the preferred development of the Sr-fluoroapatite – pollucite-type glass-ceramic. In addition to this main development, it was possible to control the thermal properties. Especially the Rb-leucite containing glass-ceramic showed the highest coefficient of thermal

  4. Sintered gahnite–cordierite glass-ceramic based on raw materials with different fluorine sources

    Indian Academy of Sciences (India)

    Esmat M A Hamzawy; Mohammed A Bin Hussain

    2015-12-01

    Glass-ceramic based on Zn-containing cordierite was prepared from kaolin, silica'sand and commercial ZnO. The addition of AlF3, MgF2 and CaF2 was performed as nucleation catalysts. Dark brown glasses were obtained from the glass batches. The transformation and crystallization temperatures were in the range of 739–773 and 972–1007°C, respectively. Gahnite, cordierite and very little enstatite were the development crystalline phases through the heating and sintering process between 1000 and 1340°C. The microstructure of crystallized samples at 1340°C showed the appearance of dominant euhedral octahedral crystals of gahnite and hexagonal cordierite, in the low micro-scale, disseminated in the glassy matrix. The microanalysis of the crystallized samples indicated that Zn and Mg may replace each other in gahnite and cordierite structure. Densities of the crystallized samples were between 2.2517 and 2.5278 g cm−3. The thermal expansion of the crystallized samples was ranging from 19.22 to 59.30 × 10−7°C−1. However, the higher crystallization of both cordierite and gahnite accompany with the higher values of densities and the lower values of coefficient of thermal expansion.

  5. A new bio-active glass ceramic

    International Nuclear Information System (INIS)

    Since 1960 fine ceramics such as alumina have been used side by side with metallic materials for bone and joint replacement. They have high mechanical strength and are free from corrosion problem faced by metals. However they don't bond to the natural living bone and hence are called bio-inactive. This was followed by the development of bio-active glasses and glass-ceramics which bond to the natural bone but have low mechanical strength. In the present work a new bio-active glass-ceramic, based on CaO-SiO/sub 2/-P/sub 2/O/sub 3/-MgO composition, has been developed which has mechanical strength compared to that of a bio-inactive glass ceramic and also bonds strongly to the natural bone. X-ray diffraction analysis reveals wollastanite and apatite phases in the glass ceramic. A new bio-active cement has also been developed which can be used to join broken pieces of bone or by itself at a filler. (author)

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

    International Nuclear Information System (INIS)

    The interest for the use of ceramic materials for dental applications started due to the good aesthetic appearance promoted by the similarity to natural teeth. However, the fragility of traditional ceramics was a limitation for their use in stress conditions. The development of alumina and zirconia based materials, that associate aesthetic results, biocompatibility and good mechanical behaviour, makes possible the employment of ceramics for fabrication of dental restorations. The incorporation of vitreous phase in these ceramics is an alternative to minimize the ceramic retraction and to improve the adhesion to resin-based cements, necessary for the union of ceramic frameworks to the remaining dental structure. In the dentistry field, alumina and zirconia ceramic infiltrated with glassy phase are represented commercially by the In-Ceram systems. Considering that the improvement of powder's synthesis routes and of techniques of ceramic processing contributes for good performance of these materials, the goal of the present work is the study of processing conditions of alumina and/or 3 mol% yttria-stabilized zirconia ceramics infiltrated with aluminum borosilicate lanthanum glass. The powders, synthesized by hydroxide coprecipitation route, were pressed by uniaxial compaction and pre-sintered at temperature range between 950 and 1650 degree C in order to obtain porous ceramics bodies. Vitreous phase incorporation was performed by impregnation of aluminum borosilicate lanthanum powder, also prepared in this work, followed by heat treatment between 1200 and 1400 degree C .Ceramic powders were characterized by thermogravimetry, X-ray diffraction, scanning and transmission electron microscopy, gaseous adsorption (BET) and laser diffraction. Sinterability of alumina and /or stabilized zirconia green pellets was evaluated by dilatometry. Pre-sintered ceramics were characterized by apparent density measurements (Archimedes method), X-ray diffraction and scanning electron

  7. Crystallization and structural investigation of Eu-doped fluorozirconate-based glass ceramics

    International Nuclear Information System (INIS)

    A series of Eu-doped fluorozirconate-based glass ceramics has been developed for medical and photovoltaic applications. In the first case, the materials can be used as X-ray scintillators or X-ray storage phosphors, in the latter case as down-converting top layers for highly efficient solar cells. The glasses are based on a modified ZBLAN composition, i.e. a mixture of Zr, Ba, La, Al, and Na fluorides. They are additionally doped with chlorine ions to initiate the growth of BaCl2 nanocrystals upon thermal processing. Eu2+ ions are incorporated into the nanocrystals during the annealing procedure enabling a strong fluorescence upon ultraviolet or x-ray excitation. The nanocrystal size and structural phase depend significantly on the heating conditions and Eu doping level. X-ray diffraction patterns show a structural phase change of the BaCl2 nanocrystals from hexagonal to orthorhombic as annealing temperatures are increased. DSC experiments were performed to obtain activation energies, thermal stability parameters and information on the crystal growth mechanisms.

  8. Optical scattering in glass ceramics

    NARCIS (Netherlands)

    Mattarelli, M.; Montagna, M.; Verrocchio, P.

    2008-01-01

    The transparency of glass ceramics with nanocrystals is generally higher than that expected from the theory of Rayleigh scattering. We attribute this ultra-transparency to the spatial correlation of the nanoparticles. The structure factor is calculated for a simple model system, the random sequentia

  9. Correlation between nanostructural and electrical properties of barium titanate-based glass-ceramic nano-composites

    Energy Technology Data Exchange (ETDEWEB)

    Al-Assiri, M.S., E-mail: msassiri@kku.edu.sa [Department of Physics, King Khaled University, P.O. Box 9003, Abha (Saudi Arabia); El-Desoky, M.M., E-mail: mmdesoky@gmail.com [Department of Physics, King Khaled University, P.O. Box 9003, Abha (Saudi Arabia); Department of Physics, Faculty of Science, Suez Canal University, Suez (Egypt)

    2011-09-08

    Highlights: > Glasses have been transformed into nanomaterials by annealing at crystallization temperature. > Glass-ceramic nano-composites are important because of their new physical. > Grain sizes are the most significant structural parameter in electronic nanocrystalline phases. > These phases are very high electrical conductivity. > Hence, glass-ceramic nanocrystals are expected to be used, as gas sensors. - Abstract: Glasses in the system BaTiO{sub 3}-V{sub 2}O{sub 5}-Bi{sub 2}O{sub 3} have been transformed into glass-ceramic nano-composites by annealing at crystallization temperature T{sub cr} determined from DSC thermograms. After annealing they consist of small crystallites embedded in glassy matrix. The crystallization temperature T{sub cr} increases with increasing BaTiO{sub 3} content. XRD and TEM of the glass-ceramic nano-composites show that nanocrystals were embedded in the glassy matrix with an average grain size of 25 nm. The resulting materials exhibit much higher electrical conductivity than the initial glasses. It was postulated that the major role in the conductivity enhancement of these nanomaterials is played by the developed interfacial regions between crystalline and amorphous phases, in which the concentration of V{sup 4+}-V{sup 5+} pairs responsible for electron hopping, has higher than values that inside the glassy matrix. The experimental results were discussed in terms of a model proposed in this work and based on a 'core-shell' concept. From the best fits, reasonable values of various small polaron hopping (SPH) parameters were obtained. The conduction was attributed to non-adiabatic hopping of small polaron.

  10. Heat treatment of pre-hydrolyzed silane increases adhesion of phosphate monomer-based resin cement to glass ceramic

    OpenAIRE

    de Carvalho, Rodrigo Furtado; Caroline COTES; Kimpara, Estevão Tomomitsu; Leite, Fabíola Pessoa Pereira; Özcan, Mutlu

    2015-01-01

    This study evaluated the influence of different forms of heat treatment on a pre-hydrolyzed silane to improve the adhesion of phosphate monomer-based (MDP) resin cement to glass ceramic. Resin and feldspathic ceramic blocks (n=48, n=6 for bond test, n=2 for microscopy) were randomly divided into 6 groups and subject to surface treatments: G1: Hydrofluoric acid (HF) 9.6% for 20 s + Silane + MDP resin cement (Panavia F); G2: HF 9.6% for 20 s + Silane + Heat Treatment (oven) + Panavia F; G3: Sil...

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

    Directory of Open Access Journals (Sweden)

    Inès M. M. M. Ponsot

    2014-07-01

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

  12. Investigation on Structural and Optical Properties of Willemite Doped Mn2+ Based Glass-Ceramics Prepared by Conventional Solid-State Method

    Directory of Open Access Journals (Sweden)

    Nur Farhana Samsudin

    2015-01-01

    Full Text Available Mn-doped willemite (Zn2SiO4:Mn2+ glass-ceramics derived from ZnO-SLS glass system were prepared by a conventional melt-quenching technique followed by a controlled crystallization step employing the heat treatment process. Soda lime silica (SLS glass waste, ZnO, and MnO were used as sources of silicon, zinc, and manganese, respectively. The obtained glass-ceramic samples were characterized using the X-ray diffraction (XRD, Field Emission Scanning Electron Microscopy (FESEM, Fourier Transform Infrared (FTIR, UV-Visible (UV-Vis, and photoluminescence (PL spectroscopy. The results of XRD revealed that ZnO crystal and willemite (β-Zn2SiO4 were presented as major embedded crystalline phases. This observation was consistent with the result of FESEM which showed the presence of irregularity in shape and size of willemite crystallites. FTIR spectroscopy exhibits the structural evolution of willemite based glass-ceramics. The optical band gap shows a decreasing trend as the Mn-doping content increased. Photoluminescent technique was applied to characterize the role of Mn2+ ions when entering the willemite glass-ceramic structure. By measuring the excitation and emission spectra, the main emission peak of the glass-ceramic samples located at a wavelength of 585 nm after subjecting to 260 nm excitations. The following results indicate that the obtained glass-ceramics can be applied as phosphor materials.

  13. In vitro antimicrobial activity of ZnO based glass-ceramics against pathogenic bacteria.

    Science.gov (United States)

    Riaz, Madeeha; Zia, Rehana; Saleemi, Farhat; Ikram, Hafeez; Bashir, Farooq

    2015-12-01

    The antibacterial activity of ZnO (0-15.53 mol%) based SiO2-CaO-P2O5-Na2O-CaF2 bioactive glass-ceramics synthesized by controlled crystallisation were studied against eight micro-organisms using modified Kirby Bauer method. The antibacterial activity of the specimens was statistically evaluated using one-way analysis of variance and P < 0.05 was used as the level of significance. In vitro dissolution tests were performed in stimulated body fluid for 48 h at 37 °C for different time intervals to correlate the dissolution behaviour of test samples with antibacterial effects. The results illustrate that specimen BZn15.53 having the highest concentration of ZnO (15.53 mol%) demonstrated the strongest effect against Staph.aureus, S. epidermidis, B. subtilis and K. pneumonia. The effectiveness of BZn15.53 in inhibiting bacteria was due to accumulation of Zn(+2) ions around the surface of the bacteria cell release that caused the death of the cell, besides the presence of hydroxyapatite phase was also responsible for damaging the cell membrane of bacteria.

  14. In vitro antimicrobial activity of ZnO based glass-ceramics against pathogenic bacteria.

    Science.gov (United States)

    Riaz, Madeeha; Zia, Rehana; Saleemi, Farhat; Ikram, Hafeez; Bashir, Farooq

    2015-12-01

    The antibacterial activity of ZnO (0-15.53 mol%) based SiO2-CaO-P2O5-Na2O-CaF2 bioactive glass-ceramics synthesized by controlled crystallisation were studied against eight micro-organisms using modified Kirby Bauer method. The antibacterial activity of the specimens was statistically evaluated using one-way analysis of variance and P < 0.05 was used as the level of significance. In vitro dissolution tests were performed in stimulated body fluid for 48 h at 37 °C for different time intervals to correlate the dissolution behaviour of test samples with antibacterial effects. The results illustrate that specimen BZn15.53 having the highest concentration of ZnO (15.53 mol%) demonstrated the strongest effect against Staph.aureus, S. epidermidis, B. subtilis and K. pneumonia. The effectiveness of BZn15.53 in inhibiting bacteria was due to accumulation of Zn(+2) ions around the surface of the bacteria cell release that caused the death of the cell, besides the presence of hydroxyapatite phase was also responsible for damaging the cell membrane of bacteria. PMID:26507201

  15. Pressurized heat treatment of glass ceramic

    Science.gov (United States)

    Kramer, D.P.

    1984-04-19

    A method of producing a glass-ceramic having a specified thermal expansion value is disclosed. The method includes the step of pressurizing the parent glass material to a predetermined pressure during heat treatment so that the glass-ceramic produced has a specified thermal expansion value. Preferably, the glass-ceramic material is isostatically pressed. A method for forming a strong glass-ceramic to metal seal is also disclosed in which the glass-ceramic is fabricated to have a thermal expansion value equal to that of the metal. The determination of the thermal expansion value of a parent glass material placed in a high-temperature environment is also used to determine the pressure in the environment.

  16. Optimization of La 2O 3-containing diopside based glass-ceramic sealants for fuel cell applications

    Science.gov (United States)

    Goel, Ashutosh; Tulyaganov, Dilshat U.; Kharton, Vladislav V.; Yaremchenko, Aleksey A.; Eriksson, Sten; Ferreira, José M. F.

    We report on the optimization of La 2O 3-containing diopside based glass-ceramics (GCs) for sealant applications in solid oxide fuel cells (SOFC). Seven glass compositions were prepared by modifying the parent glass composition, Ca 0.8Ba 0.1MgAl 0.1La 0.1Si 1.9O 6. First five glasses were prepared by the addition of different amounts of B 2O 3 in a systematic manner (i.e. 2, 5, 10, 15, 20 wt.%) to the parent glass composition while the remaining two glasses were derived by substituting SrO for BaO in the glasses containing 2 wt.% and 5 wt.% B 2O 3. Structural and thermal behavior of the glasses was investigated by infrared spectroscopy (FTIR), density measurements, dilatometry and differential thermal analysis (DTA). Liquid-liquid amorphous phase separation was observed in B 2O 3-containing glasses. Sintering and crystallization behavior, microstructure, and properties of the GCs were investigated under different heat treatment conditions (800 and 850 °C; 1-300 h). The GCs with ≥5 wt.% B 2O 3 showed an abnormal thermal expansion behavior above 600 °C. The chemical interaction behavior of the glasses with SOFC electrolyte and metallic interconnects, has been investigated in air atmosphere at SOFC operating temperature. Thermal shock resistance and gas-tightness of GC sealants in contact with 8YSZ was evaluated in air and water. The total electrical resistance of a model cell comprising Crofer 22 APU and 8YSZ plates joined by a GC sealant has been examined by the impedance spectroscopy. Good matching of thermal expansion coefficients (CTE) and strong, but not reactive, adhesion to electrolyte and interconnect, in conjunction with a low level of electrical conductivity, indicate that the investigated GCs are suitable candidates for further experimentation as SOFC sealants.

  17. Glass ceramics for high - Tc superconductors

    International Nuclear Information System (INIS)

    Glass formation in the BiO1.5-Ca0.5-Sr0.5O-CuO quasiternary oxide system was examined by the twin-roller and metal-plate quenching techniques. The crystallization process and kinetics were systematically studied by differential thermal and thermogravimetric analysis, X-ray diffraction, and electron microscopy as well as electrical measurements. The route and kinetic properties of crystallization were shown to have a strong compositional dependence. It was found that the growth of crystals in the glasses can be accelerated in the presence of an electrical field. A temperature gradient-related orientation of crystallization was revealed in the Bi-based glasses. This has been ascribed to the large crystallographic anisotropy of the superconducting crystals. The effects of compositions, annealing conditions, and oxygen deficiency on the superconductivity in the Bi-Ca-Sr-Cu-0 glass ceramics are also discussed. 27 refs., 2 tabs., 13 figs

  18. Effect of hydrofluoric acid etching duration on the roughness and flexural strength of a lithium disilicate-based glass ceramic.

    Science.gov (United States)

    Zogheib, Lucas Villaça; Bona, Alvaro Della; Kimpara, Estevão Tomomitsu; McCabe, John F

    2011-01-01

    The aim of this study was to examine the effect of different acid etching times on the surface roughness and flexural strength of a lithium disilicate-based glass ceramic. Ceramic bar-shaped specimens (16 mm x 2 mm x 2 mm) were produced from ceramic blocks. All specimens were polished and sonically cleaned in distilled water. Specimens were randomly divided into 5 groups (n=15). Group A (control) no treatment. Groups B-E were etched with 4.9% hydrofluoric acid (HF) for 4 different etching periods: 20 s, 60 s, 90 s and 180 s, respectively. Etched surfaces were observed under scanning electron microscopy. Surface profilometry was used to examine the roughness of the etched ceramic surfaces, and the specimens were loaded to failure using a 3-point bending test to determine the flexural strength. Data were analyzed using one-way ANOVA and Tukey's test (?=0.05). All etching periods produced significantly rougher surfaces than the control group (p<0.05). Roughness values increased with the increase of the etching time. The mean flexural strength values were (MPa): A=417 ± 55; B=367 ± 68; C=363 ± 84; D=329 ± 70; and E=314 ± 62. HF etching significantly reduced the mean flexural strength as the etching time increased (p=0.003). In conclusion, the findings of this study showed that the increase of HF etching time affected the surface roughness and the flexural strength of a lithium disilicate-based glass ceramic, confirming the study hypothesis.

  19. Characterisation of Nd-doped calcium aluminosilicate parent glasses designed for the preparation of zirconolite-based glass-ceramic waste forms

    International Nuclear Information System (INIS)

    Zirconolite-based (nominally CaZrTi2O7) glass-ceramics belonging to the SiO2Al2O3-CaO- ZrO3-TiO2 system are good waste forms for the specific immobilisation of actinides. The understanding of their crystallisation processes implies to investigate the structure of the glass. Thus, the environment around Ti, Zr (nucleating agents) and Nd (trivalent actinides surrogate) was characterised in parent glasses. Electron spin resonance (ESR) study of the small amount of Ti3+ occurring in the glass enabled to identify two types of sites for titanium: the main one is of C4v or D4h symmetry. EXAFS showed that Zr occupied a quite well defined 6-7-fold coordinated site with second neighbours which could correspond to Ca/Ti and Zr. Nd environment was probed by optical spectroscopies (absorption, fluorescence), ESR and EXAFS. All these techniques demonstrated that the environment around Nd was very constrained by the glassy network. Notably, Nd occupies a highly distorted 8-9-fold coordinated site in the parent glass. (authors)

  20. 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.

  1. Low temperature sintering of fluorapatite glass-ceramics.

    Science.gov (United States)

    Denry, Isabelle; Holloway, Julie A

    2014-02-01

    Fluorapatite glass-ceramics have been shown to be excellent candidates as scaffold materials for bone grafts, however, scaffold production by sintering is hindered by concurrent crystallization of the glass. Objective, our goal was to investigate the effect of Ca/Al ratio on the sintering behavior of Nb-doped fluorapatite-based glasses in the SiO2-Al2O3-P2O5-MgO-Na2O-K2O-CaO-CaF2 system. Methods, glass compositions with Ca/Al ratio of 1 (A), 2 (B), 4 (C) and 19 (D) were prepared by twice melting at 1525°C for 3h. Glasses were either cast as cylindrical ingots or ground into powders. Disk-shaped specimens were prepared by either sectioning from the ingots or powder-compacting in a mold, followed by heat treatment at temperatures ranging between 700 and 1050°C for 1h. The density was measured on both sintered specimens and heat treated discs as controls. The degree of sintering was determined from these measurements. Results and Significance XRD showed that fluorapatite crystallized in all glass-ceramics. A high degree of sintering was achieved at 775°C for glass-ceramic D (98.99±0.04%), and 900°C for glass-ceramic C (91.31±0.10). Glass-ceramics A or B were only partially sintered at 1000°C (63.6±0.8% and 74.1±1.5%, respectively). SEM revealed a unique microstructure of micron-sized spherulitic fluorapatite crystals in glass-ceramics C and D. Increasing the Ca/Al ratio promoted low temperature sintering of fluorapatite glass-ceramics, which are traditionally difficult to sinter.

  2. Bioactivity of mica/apatite glass ceramics

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The bioactivity of mica/apatite glass ceramic composites, including the in vitro behavior in simulated body fluid and the histological appearance of the interface between the mica/apatite glass ceramics and the rabbit mandible defect in vivo under a dynamic condition. The results show that biological apatite layer forms on the surface of the mica/apatite glass ceramics after 1 d of immersion in the simulated body fluid, and becomes dense after 14 d. In vivo tests indicate that bone formation occurs after implantation for 14 d, and strong bonding of bone to the implant occurs after 42 d. No aseptic loosening occurs during 42 d of implantation. The finding shows that mica/apatite glass ceramics have good bioactivity and osteoconductivity for constructing bone graft, and can be promising for biomedical application.

  3. 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

  4. Surface or internal nucleation and crystallization of glass-ceramics

    Science.gov (United States)

    Höland, W.; Rheinberger, V. M.; Ritzberger, C.; Apel, E.

    2013-07-01

    Fluoroapatite (Ca5(PO4)3F) was precipitated in glass-ceramics via internal crystallization of base glasses. The crystals grew with a needle-like morphology in the direction of the crystallographic c-axis. Two different reaction mechanisms were analyzed: precipitation via a disordered primary apatite crystals and a solid state parallel reaction to rhenanite (NaCaPO4) precipitation. In contrast to the internal nucleation used in the formation of fluoroapatite, surface crystallization was induced to precipitate a phosphate-free oxyapatite of NaY9(SiO4)6O2-type. Internal nucleation and crystallization have been shown to be a very useful tool for developing high-strength lithium disilicate (Li2Si2O5) glass-ceramics. A very controlled process was conducted to transform the lithium metasilicate glass-ceramic precursor material into the final product of the lithium disilicate glass-ceramic without the major phase of the precursor material. The combination of all these methods allowed the driving forces of the internal nucleation and crystallization mechanisms to be explained. An amorphous phosphate primary phase was discovered in the process. Nucleation started at the interface between the amorphous phosphate phase and the glass matrix. The final products of all these glass-ceramics are biomaterials for dental restoration showing special optical properties, e.g. translucence and color close to dental teeth.

  5. Hardness of basaltic glass-ceramics

    DEFF Research Database (Denmark)

    Jensen, Martin; Smedskjær, Morten Mattrup; Estrup, Maja;

    2009-01-01

    The dependence of the hardness of basaltic glass-ceramics on their degree of crystallisation has been explored by means of differential scanning calorimetry, optical microscopy, x-ray diffraction, and Vickers indentation. Different degrees of crystallisation in the basaltic glasses were achieved...

  6. Structure and nonlinear optical properties of novel transparent glass-ceramics based on Co2+:ZnO nanocrystals

    Science.gov (United States)

    Loiko, P. A.; Dymshits, O. S.; Vitkin, V. V.; Skoptsov, N. A.; Zhilin, A. A.; Shemchuk, D. V.; Tsenter, M. Ya; Bogdanov, K. V.; Malyarevich, A. M.; Glazunov, I. V.; Mateos, X.; Yumashev, K. V.

    2016-05-01

    Transparent glass-ceramics (GCs) based on Co2+:ZnO nanocrystals (mean diameter, 11 nm) are synthesized on the basis of cobalt-doped glasses of the K2O–ZnO–Al2O3–SiO2 system. For these GCs, the absorption band related to the 4A2(4F)  →  4T1(4F) transition of Co2+ ions in tetrahedral sites spans until ~1.73 μm. Saturation of the absorption is demonstrated at 1.54 μm, with a saturation fluence F s  =  0.8  ±  0.1 Jcm‑2 (σ GSA  =  1.7  ±  0.2  ×  10‑19 cm2) and a recovery time of 890  ±  10 ns. Passive Q-switching of an Er,Yb:glass laser is realized with the synthesized GCs. This laser generated 0.37 mJ/100 ns pulses at 1.54 μm. The developed GCs are promising as saturable absorbers for 1.6–1.7 μm crystalline erbium lasers.

  7. Comparison of Leaching Rates of Glass-Ceramic and Glass

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>With the increase of the burn-up of the nuclear fuel, the amounts of the long-lived radionuclides increase. The solubility of actinides such as plutonium in glass is very limited. Glass-ceramic as the new

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

    Directory of Open Access Journals (Sweden)

    Christian Ritzberger

    2010-06-01

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

  9. Production of glass or glass-ceramic to metal seals with the application of pressure

    Science.gov (United States)

    Kelly, M.D.; Kramer, D.P.

    1985-01-04

    In a process for preparing a glass or glass-ceramic to metal seal comprising contacting the glass with the metal and heat-treating the glass and metal under conditions whereby the glass to metal seal is effected and, optionally, the glass is converted to a glass-ceramic, an improvement comprises carrying out the heat-treating step using hot isostatic pressing.

  10. Development and characterization of basalt-glass ceramics for the immobilization of transuranic wastes

    International Nuclear Information System (INIS)

    Basalt-based waste forms were developed for the immobilization of transuranic (TRU) contaminated wastes. The specific waste studied is a 3:1 blend of process sludge and incinerator ash. Various amounts of TRU blended waste were melted with Pomona basalt powder. The vitreous products were subjected to a variety of heat treatment conditions to form glass ceramics. The total crystallinity of the glass ceramic, ranging from 20 to 45 wt %, was moderately dependent on composition and heat treatment conditions. Three parent glasses and four glass ceramics with varied composition and heat treatment were produced for detailed phase characterization and leaching. Both parent glasses and glass ceramics were mainly composed of a continuous, glassy matrix phase. This glass matrix entered into solution during leaching in both types of materials. The Fe-Ti rich dispersed glass phase was not significantly degraded by leaching. The glass ceramics, however, exhibited four to ten times less elemental releases during leaching than the parent glasses. The glass ceramic matrix probably contains higher Fe and Na and lower Ca and Mg relative to the parent glass matrix. The crystallization of augite in the glass ceramics is believed to contribute to the improved leach rates. Leach rates of the basalt glass ceramic are compared to those of other TRU nuclear waste forms containing 239Pu

  11. Spectral investigations on Dy3+-doped transparent oxyfluoride glasses and nanocrystalline glass ceramics

    International Nuclear Information System (INIS)

    Dysprosium-doped oxyfluoride glasses and nanocrystalline glass ceramics have been synthesized and studied by x-ray diffraction, absorption, and visible and near-infrared emission spectra. The samples emit intense white light when populating the 4F9/2 level with a 451 nm laser light and, from the visible emission spectra, yellow to blue intensity ratios and chromaticity color coordinates have been calculated and their relative variation have been discussed based on the concentration of Dy3+ ions and the heat treatment conditions used to prepare the glass ceramics. Infrared emission has also been observed in glasses and glass ceramics after laser excitation at 800 nm, showing bands at 1.33 and 1.67 μm, useful for optical amplification in fiber amplifiers

  12. Cathodoluminescence of oxyfluoride glass-ceramics

    International Nuclear Information System (INIS)

    Tb, Ce, Eu activated oxyfluoride glass-ceramics with the composition SiO2 · Al2O3 · Li2O · LaF3 have been studied by cathodoluminescence (CL). We compared CL intensities and decay times of the Tb, Ce, Eu activated glass-ceramic samples and observed that the Tb activated sample has the most intense luminescence, but the Ce activated sample has the shortest decay times. Induced optical absorption and thermostimulated luminescence have been observed after X-ray irradiation of samples. -- Highlights: ►We have studied Tb, Ce and Eu activated oxyfluoride glass-ceramics. ► Ce activated sample has the fastest cathodoluminescence decay times. ► X-ray excited luminescence shows, that Tb activated sample is the most intense. ► Intensity of Tb activated sample is 10 times smaller than intensity of CsI(Tl)

  13. Element Partitioning in Glass-Ceramic Designed for Actinides Immobilization

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Glass-ceramics were designed for immobilization of actinides. In order to immobilizing more wastes in the matrix and to develop the optimum formulation for the glass-ceramic, it is necessary to study the

  14. SYNTHESIS OF DENTAL FLUOROAPATITE GLASS-CERAMIC GLAZES

    Directory of Open Access Journals (Sweden)

    G. Aabolfathi

    2011-12-01

    Full Text Available A dental glass-ceramic glaze based on the SiO2–Li2O3–P2O5–CaO system, which is currently used as dentin for lithiumdisilicate glass-ceramic cores, was synthesized. The role of Na2O, CaO and P2O5 in sintering and crystallization of the related glasses were studied by firing at temperatures higher than their dilatometric softening point. Sintering of glasses led to precipitation of needle - like fluoroapatite crystalline particles. However, in spite of current definition about glassceramics, the final synthesized composition and a similar trade mark sample, which was used as reference, did not show considerable amounts of crystalline phases after sintering process. Furthermore, reducing the constituent‘s of fluoroapatite in glass composition led to reduction of sinterability and fusibility of the system.

  15. Preparation of glass-ceramic materials from granitic rocks waste

    OpenAIRE

    Gamal A. Khater

    2012-01-01

    Crystallisation of glasses based on the diopside-anorthite eutectic system, containing increased amount (10–50 wt.%) of wollastonite based on granite quarries waste, was investigated for the preparation of cheap technical glass-ceramic materials. Granite quarries waste consisted of about 52 wt.% of the batch constituents depending on composition. The granite quarries waste composition was sometimes modified by adding other ingredients such as dolomite, limestone and Al2O3. Batches were melted...

  16. Glass-ceramic composition for hermetic seals

    Science.gov (United States)

    Ballard, Jr., Clifford P.

    1979-01-01

    The invention relates to a glass-ceramic composition having a high fracture strength adaptable for hermetically sealing to chromium bearing iron or nickel base alloys at temperatures of between about 950.degree. C to about 1100.degree. C to form a hermetically sealed insulator body, comprising from about 55 to about 65 weight percent SiO.sub.2, from about 0 to about 5 weight percent Al.sub.2 O.sub.3, from about 6 to about 11 weight % Li.sub.2 O, from about 25 to about 32 weight percent BaO, from about 0.5 to about 1.0 weight percent CoO and from about 1.5 to about 3.5 weight percent P.sub.2 O.sub.5.

  17. Spectroscopic investigations on glasses, glass-ceramics and ceramics developed for nuclear waste immobilization

    Science.gov (United States)

    Caurant, D.

    2014-05-01

    Highly radioactive nuclear waste must be immobilized in very durable matrices such as glasses, glass-ceramics and ceramics in order to avoid their dispersion in the biosphere during their radioactivity decay. In this paper, we present various examples of spectroscopic investigations (optical absorption, Raman, NMR, EPR) performed to study the local structure of different kinds of such matrices used or envisaged to immobilize different kinds of radioactive wastes. A particular attention has been paid on the incorporation and the structural role of rare earths—both as fission products and actinide surrogates—in silicate glasses and glass-ceramics. An example of structural study by EPR of a ceramic (hollandite) irradiated by electrons (to simulate the effect of the β-irradiation of radioactive cesium) is also presented.

  18. Glass ceramic-to-metal seals

    Science.gov (United States)

    Not Available

    1982-04-19

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

  19. Lead-barium fluoroborate glass ceramics doped with Nd3+ or Er3+

    Science.gov (United States)

    Petrova, O. B.; Sevostjanova, T. S.; Anurova, M. O.; Khomyakov, A. V.

    2016-02-01

    Lead-barium fluoroborate glasses in the PbF2-BaF2-B2O3, PbF2-BaO-B2O3, and PbO- BaF2-B2O3 systems doped with rare-earth ions (Nd3+ or Er3+) are synthesized and studied. It is shown that, based on these glasses, it is possible to produce transparent glass ceramics with fluoride crystalline phases, including ceramics with one crystalline phase of the fluorite structure. The spectral and luminescent properties of the doped glasses, glass ceramics, and polycrystalline complex fluorides containing Pb, Ba, and rare ions are studied.

  20. Plutonium immobilization in glass and ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Knecht, D.A. [Lockheed Martin Idaho Technologies, Idaho Falls (United States); Murphy, W.M. [Southwest Research Institute, San Antonio, TX (United States)

    1996-05-01

    The Materials Research Society Nineteenth Annual Symposium on the Scientific Basis for Nuclear Waste Management was held in Boston on November 27 to December 1, 1995. Over 150 papers were presented at the Symposium dealing with all aspects of nuclear waste management and disposal. Fourteen oral sessions and on poster session included a Plenary session on surplus plutonium dispositioning and waste forms. The proceedings, to be published in April, 1996, will provide a highly respected, referred compilation of the state of scientific development in the field of nuclear waste management. This paper provides a brief overview of the selected Symposium papers that are applicable to plutonium immobilization and plutonium waste form performance. Waste forms that were described at the Symposium cover most of the candidate Pu immobilization options under consideration, including borosilicate glass with a melting temperature of 1150 {degrees}C, a higher temperature (1450 {degrees}C) lanthanide glass, single phase ceramics, multi-phase ceramics, and multi-phase crystal-glass composites (glass-ceramics or slags). These Symposium papers selected for this overview provide the current status of the technology in these areas and give references to the relevant literature.

  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. The Effect of Sm2O3 on the Chemical Stability of Borosilicate Glass and Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yongqiang; WANG Mitang; LI Mei; WANG Ming; LIU Quansheng

    2014-01-01

    Sm2O3 containing zinc-borosilicate glass and glass ceramics were prepared by melt quenching method, and the effect of Sm2O3 and micro-crystallization on the chemical stability of borosilicate glass was explored. DTA analysis showed that the endothermic peak and exothermic peak of basic glass changed from 635℃and 834℃to 630℃and 828℃respectively as a result of the doping of Sm2O3. XRD analysis showed the promoting effect of Sm2O3 on crystallization ability of this glass. The cumulative mass loss of base glass, Sm2O3 containing glass, glass ceramic and Sm2O3 containing glass ceramic was 0.289, 0.253, 0.329, 0.269 mg/mm2 respectively after 26 days corrosion in alkali solution, and 1.293, 1.290, 0.999, 1.040 mg/mm2 respectively in acidic erosion medium. Micro-crystallization decreased and improved the alkali and acid resistance of borosilicate glass respectively, the addition of Sm2O3 increased the alkali resistance of base glass and glass ceramics, and the slight effect of Sm2O3 on the acid resistance of borosilicate glass was also observed.

  4. Preparation of glass-ceramic materials from granitic rocks waste

    Directory of Open Access Journals (Sweden)

    Gamal A. Khater

    2012-06-01

    Full Text Available Crystallisation of glasses based on the diopside-anorthite eutectic system, containing increased amount (10–50 wt.% of wollastonite based on granite quarries waste, was investigated for the preparation of cheap technical glass-ceramic materials. Granite quarries waste consisted of about 52 wt.% of the batch constituents depending on composition. The granite quarries waste composition was sometimes modified by adding other ingredients such as dolomite, limestone and Al2O3. Batches were melted and then casted into glass, which was then subjected to heat-treatment to induce crystallisation. The resulting glass-ceramic materials (heat-treated at 1000 °C for 3 h were mainly composed of diopside, anorthite, wollastonite and mullite. With increasing temperature (to 1050 °C for 3 h, diopside and anorthite transformed into akermanite and mullite. It has been found that increasing the content of the diopside-anorthite eutectic in the batch constituents, resulted in increased bulk crystallisation. Samples were characterised with different techniques including differential thermal analysis, polarizing microscope, X-ray diffraction and indentation microhardness testing. The obtained glass-ceramic materials possess very high hardness, indicating high abrasion resistance, making them suitable for many applications under aggressive mechanical conditions.

  5. Development of mica glass-ceramic glazes

    OpenAIRE

    Romero, Maximina; Rincón López, Jesús María; Acosta, Anselmo

    2004-01-01

    The effect of iron content on crystallization of a mica glaze as coating for fast firing stoneware substrates has been investi¬gated. Measurements by differential thermal analysis (DTA) combined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) have shown the development of preferential crystal orientation in the mica glass-ceramic glaze. By com¬parison with amorphous and partly crystalline glazes, an enhancement of the mechanical properties of coatings with aligned and inte...

  6. Laser Micromachining of Glass, Silicon, and Ceramics

    OpenAIRE

    L. Rihakova; Chmelickova, H.

    2015-01-01

    A brief review is focused on laser micromachining of materials. Micromachining of materials is highly widespread method used in many industries, including semiconductors, electronic, medical, and automotive industries, communication, and aerospace. This method is a promising tool for material processing with micron and submicron resolution. In this paper micromachining of glass, silicon, and ceramics is considered. Interaction of these materials with laser radiation and recent research held o...

  7. Functional Glasses and Glass-ceramics Derived from Industrial Waste

    OpenAIRE

    Rama Krishna Satish, Chinnam

    2014-01-01

    Wastes from industrial processes and energy generation facilities pose environment and health issues. Diversion of wastes from landfill to favour reuse or recycling options and towards the fabrication of marketable products is of high economic and ecologic interest. Moreover safe recycling of industrial wastes is necessary and even vital to our society because of the increasing volume being generated. Glasses and glass–ceramics (GCs) attract particular interest in waste recycli...

  8. Ceramic and glass radioactive waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Readey, D.W.; Cooley, C.R. (comps.)

    1977-01-01

    This report contains 14 individual presentations and 6 group reports on the subject of glass and polycrystalline ceramic radioactive waste forms. It was the general consensus that the information available on glass as a waste form provided a good basis for planning on the use of glass as an initial waste form, that crystalline ceramic forms could also be good waste forms if much more development work were completed, and that prediction of the chemical and physical stability of the waste form far into the future would be much improved if the basic synergistic effects of low temperature, radiation and long times were better understood. Continuing development of the polycrystalline ceramic forms was recommended. It was concluded that the leach rate of radioactive species from the waste form is an important criterion for evaluating its suitability, particularly for the time period before solidified waste is permanently placed in the geologic isolation of a Federal repository. Separate abstracts were prepared for 12 of the individual papers; the remaining two were previously abstracted.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-11-01

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

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

    International Nuclear Information System (INIS)

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

  11. Enhanced mid-IR emission in Yb3+-Tm3+ co-doped oxyfluoride glass ceramics

    International Nuclear Information System (INIS)

    Graphical abstract: Display Omitted Research highlights: → Tm3+ and Yb3+ ions had been enriched in the nanocrystals of the glass ceramics. → Mid-IR luminescence intensity of the glass ceramics was enhanced. → Judd-Ofelt theory was used to calculate optical parameters. - Abstract: Tm3+-Yb3+ co-doped transparent oxyfluoride glass ceramics were prepared through thermal treatment of the as-prepared glasses. The precipitation of nanocrystals and the incorporation of Tm3+ and Yb3+ into the nanocrystals were confirmed by X-ray diffraction and absorption spectra. Based on the Judd-Ofelt theory, the J-O parameters Ωλ (λ = 2, 4, 6), spontaneous radiative transition rates, radiative lifetimes and fluorescence branching ratios of Tm3+ in both as-prepared glasses and glass ceramics were calculated. Intense mid-IR emission and upconversion luminescence in the Tm3+ and Yb3+ co-doped glass ceramics were observed under 980 nm excitation. Especially, compared with that of the as-prepared glasses, mid-IR luminescence intensity of Tm3+ in the glass ceramics was greatly enhanced. Desirable spectroscopic characteristics suggest that these oxyfluoride glass ceramics may be promising mid-IR laser active medium.

  12. Modelling the crystallisation of alkaline earth boroaluminosilicate glass ceramics

    DEFF Research Database (Denmark)

    Svenson, Mouritz Nolsøe; Agersted, Karsten; Holm, Paul Martin

    2014-01-01

    To investigate the potential use of a thermochemical software package (FactSage 6.2), in the design of alkaline earth boroaluminosilicate glass ceramics, experimental and modelled results on four glass ceramics were compared. Initially large discrepancies were found. These are described and related...... for the topology of multicomponent melts, before accurate prediction of phase relations within boron-containing glass ceramics can be obtained....

  13. Glass ceramic ZERODUR enabling nanometer precision

    Science.gov (United States)

    Jedamzik, Ralf; Kunisch, Clemens; Nieder, Johannes; Westerhoff, Thomas

    2014-03-01

    The IC Lithography roadmap foresees manufacturing of devices with critical dimension of digit nanometer asking for nanometer positioning accuracy requiring sub nanometer position measurement accuracy. The glass ceramic ZERODUR® is a well-established material in critical components of microlithography wafer stepper and offered with an extremely low coefficient of thermal expansion (CTE), the tightest tolerance available on market. SCHOTT is continuously improving manufacturing processes and it's method to measure and characterize the CTE behavior of ZERODUR® to full fill the ever tighter CTE specification for wafer stepper components. In this paper we present the ZERODUR® Lithography Roadmap on the CTE metrology and tolerance. Additionally, simulation calculations based on a physical model are presented predicting the long term CTE behavior of ZERODUR® components to optimize dimensional stability of precision positioning devices. CTE data of several low thermal expansion materials are compared regarding their temperature dependence between - 50°C and + 100°C. ZERODUR® TAILORED 22°C is full filling the tight CTE tolerance of +/- 10 ppb / K within the broadest temperature interval compared to all other materials of this investigation. The data presented in this paper explicitly demonstrates the capability of ZERODUR® to enable the nanometer precision required for future generation of lithography equipment and processes.

  14. CRYSTALLIZATION KINETICS OF GLASS-CERAMICS BY DIFFERENTIAL THERMAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    A. NOZAD

    2011-06-01

    Full Text Available The crystallization behavior of fluorphlogopite, a glass-ceramic in the MgO–SiO2–Al2O3–K2O–B2O3–F system, was studied by substitution of Li2O for K2O in the glass composition. DTA, XRD and SEM were used for the study of crystallization behavior, formed phases and microstructure of the resulting glass-ceramics. Crystallization kinetics of the glass was investigated under non-isothermal conditions, using the formal theory of transformations for heterogeneous nucleation. The crystallization results were analyzed, and both the activation energy of crystallization process as well as the crystallization mechanism were characterized. Calculated kinetic parameters indicated that the appropriate crystallization mechanism was bulk crystallization for base glass and the sample with addition of Li2O. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses was in the range of 234-246 KJ/mol and in the samples with addition of Li2O was changed to the range of 317-322 KJ/mol.

  15. Preparation and Microstructure of Glass-ceramics and Ceramic Composite Materials

    Institute of Scientific and Technical Information of China (English)

    HE Feng; XIE Junlin; HAN Da

    2008-01-01

    The technology and microstructure of glass-ceramics and ceramic composite materials were studied.A suitable ceramic body was chosen on the basis of the sintering temperature of CaO-Al2O3-SiO2 system glass-ceramics.According to the expansion coefficient of the ceramic body,that of CaO-Al2O3-SiO2 system glass-ceramics was adjusted.a-wollastonite was found present as the major crystalline phase in glass-ceramic.The CaO-Al2O3-SiO2 system glass-ceramic layer and ceramic body could be sintered together by adjusting the sintering period.The compositions of glass-ceramic layer and ceramic body diffuse mutually at 1100℃.resulting in an interface between them.To achieve good sintered properties of glass-ceramics and the chosen ceramic body,at least a four-hour sintering time is used.

  16. Glass ceramic toughened with tetragonal zirconia

    Science.gov (United States)

    Keefer, Keith D.; Michalske, Terry A.

    1986-01-01

    A phase transformation-toughened glass ceramic and a process for making it are disclosed. A mixture of particulate network-forming oxide, network-modifying oxide, and zirconium oxide is heated to yield a homogeneous melt, and this melt is then heat-treated to precipitate an appreciable quantity of tetragonal zirconia, which is retained at ambient temperature to form a phase transformation-toughened glass ceramic. Nucleating agents and stabilizing agents may be added to the mixture to facilitate processing and improve the ceramic's properties. Preferably, the mixture is first melted at a temperature from 1200.degree. to 1700.degree. C. and is then heat-treated at a temperature within the range of 800.degree. to 1200.degree. C. in order to precipitate tetragonal ZrO.sub.2. The composition, as well as the length and temperature of the heat-treatment, must be carefully controlled to prevent solution of the precipitated tetragonal zirconia and subsequent conversion to the monoclinic phase.

  17. Crystallization of cerium containing iron borophosphate glasses/glass-ceramics and their spectral properties

    Science.gov (United States)

    Wang, Fu; Liao, Qilong; Zhu, Hanzhen; Dai, Yunya; Wang, Hong

    2016-04-01

    The crystallization behaviors of CeO2 containing 36Fe2O3-10B2O3-54P2O5 glasses/glass-ceramics (IBP glasses/glass-ceramics) and the effect of CeO2 addition on the structure of the IBP glasses/glass-ceramics annealed at 850 °C for 10 h were investigated by XRD, SEM and FTIR. The results show that Fe4(PO4)2O and Fe2(PO4)O phases are detected in the IBP glasses/glass-ceramics annealed at 650 °C for 10 h, and traces of FePO4 crystal is also detected when the CePO4 crystallite pre-exists in the unannealed IBP glass-ceramics. When the glasses/glass-ceramics are heat-treated at 850 °C for 10 h, Fe4(PO4)2O, Fe2(PO4)O and a small amount of FePO4 phase are detected. Meanwhile, CePO4 phase also appears in the crystallized IBP glasses/glass-ceramics containing more than 6 mol% (including 6 mol%) CeO2. Moreover, the main structural units of the crystallized glasses/glass-ceramics are [PO4] and [BO4] tetrahedron. [CeO4] tetrahedron also exists in the structure of the crystallized IBP glasses/glass-ceramics containing CeO2. CeO2 addition and the pre-existing CePO4 crystallite improve the resistance of the IBP glasses/glass-ceramics to crystallization, which makes the infrared bands associated with the vibration of [PO4] group increase in intensity and shift to high wave number.

  18. Fatigue analysis of computer-aided design/computer-aided manufacturing resin-based composite vs. lithium disilicate glass-ceramic.

    Science.gov (United States)

    Ankyu, Shuhei; Nakamura, Keisuke; Harada, Akio; Hong, Guang; Kanno, Taro; Niwano, Yoshimi; Örtengren, Ulf; Egusa, Hiroshi

    2016-08-01

    Resin-based composite molar crowns made by computer-aided design/computer-aided manufacturing (CAD/CAM) systems have been proposed as an inexpensive alternative to metal-ceramic or all-ceramic crowns. However, there is a lack of scientific information regarding fatigue resistance. This study aimed to analyze the fatigue behavior of CAD/CAM resin-based composite compared with lithium disilicate glass-ceramic. One-hundred and sixty bar-shaped specimens were fabricated using resin-based composite blocks [Lava Ultimate (LU); 3M/ESPE] and lithium disilicate glass-ceramic [IPS e.max press (EMP); Ivoclar/Vivadent]. The specimens were divided into four groups: no treatment (NT); thermal cycling (TC); mechanical cycling (MC); and thermal cycling followed by mechanical cycling (TCMC). Thermal cycling was performed by alternate immersion in water baths of 5°C and 55°C for 5 × 10(4) cycles. Mechanical cycling was performed in a three-point bending test, with a maximum load of 40 N, for 1.2 × 10(6) cycles. In addition, LU and EMP molar crowns were fabricated and subjected to fatigue treatments followed by load-to-failure testing. The flexural strength of LU was not severely reduced by the fatigue treatments. The fatigue treatments did not significantly affect the fracture resistance of LU molar crowns. The results demonstrate the potential of clinical application of CAD/CAM-generated resin-based composite molar crowns in terms of fatigue resistance. PMID:27203408

  19. Microtensile bond strength of a resin cement to glass infiltrated zirconia-reinforced ceramic : The effect of surface conditioning

    NARCIS (Netherlands)

    Amaral, R; Ozcan, M; Bottino, MA; Valandro, LF

    2006-01-01

    Objectives. This study evaluated the effect of three surface conditioning methods on the microtensile bond strength of resin cement to a glass-infiltrated zirconia-reinforced alumina-based core ceramic. Methods. Thirty blocks (5 x 5 x 4 mm) of In-Ceram Zirconia ceramics (In-Ceram Zirconia-INC-ZR, VI

  20. Optical properties of Dy3+ doped bismuth zinc borate glass and glass ceramics

    Science.gov (United States)

    Shanmugavelu, B.; Kanth Kumar, V. V. Ravi

    2012-06-01

    Dy3+ doped bismuth zinc borate transparent glasses were prepared by melt quenching technique and these glasses were used precursor to obtain transparent glass ceramics by heat treatment method. XRD pattern of the glass ceramic shows the formation of the β-BiB3O6 and Bi2ZnOB2O6 phases. The visible emission intensity of the glass ceramics is stronger than the glass. This can be due to the formation of nano nonlinear optical crystallites in glass matrix.

  1. 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...

  2. Synthesis and ceramic processing of alumina and zirconia based composites infiltrated with glass phase for dental applications; Sintese e processamento de compositos a base de alumina e zirconia com infiltracao de fase vitrea para aplicacoes odontologicas

    Energy Technology Data Exchange (ETDEWEB)

    Duarte, Daniel Gomes

    2009-07-01

    The interest for the use of ceramic materials for dental applications started due to the good aesthetic appearance promoted by the similarity to natural teeth. However, the fragility of traditional ceramics was a limitation for their use in stress conditions. The development of alumina and zirconia based materials, that associate aesthetic results, biocompatibility and good mechanical behaviour, makes possible the employment of ceramics for fabrication of dental restorations. The incorporation of vitreous phase in these ceramics is an alternative to minimize the ceramic retraction and to improve the adhesion to resin-based cements, necessary for the union of ceramic frameworks to the remaining dental structure. In the dentistry field, alumina and zirconia ceramic infiltrated with glassy phase are represented commercially by the In-Ceram systems. Considering that the improvement of powder's synthesis routes and of techniques of ceramic processing contributes for good performance of these materials, the goal of the present work is the study of processing conditions of alumina and/or 3 mol% yttria-stabilized zirconia ceramics infiltrated with aluminum borosilicate lanthanum glass. The powders, synthesized by hydroxide coprecipitation route, were pressed by uniaxial compaction and pre-sintered at temperature range between 950 and 1650 degree C in order to obtain porous ceramics bodies. Vitreous phase incorporation was performed by impregnation of aluminum borosilicate lanthanum powder, also prepared in this work, followed by heat treatment between 1200 and 1400 degree C .Ceramic powders were characterized by thermogravimetry, X-ray diffraction, scanning and transmission electron microscopy, gaseous adsorption (BET) and laser diffraction. Sinterability of alumina and /or stabilized zirconia green pellets was evaluated by dilatometry. Pre-sintered ceramics were characterized by apparent density measurements (Archimedes method), X-ray diffraction and scanning

  3. Luminescent properties of Tb3+-doped transparent glass ceramics

    International Nuclear Information System (INIS)

    Dense transparent glass ceramics containing BaGdF5 and BaLu2F8 nanocrystals were prepared from the Tb3+-activated SiO2–B2O3–BaF2–Lu2O3–Gd2O3 oxyfluoride scintillating glasses by thermal treatment technology. Glass structure was investigated by X-ray diffraction (XRD) and scanning electron micrograph (SEM); the optical properties including transmission, luminescent properties excited under both ultraviolet light and X-ray excitation, and the decay times of the glass and glass ceramics were also investigated. The coexistence of BaGdF5 and BaLu2F8 nanocrystals in the transparent glass ceramics was confirmed by the XRD results, which plays a key role in the improvement of scintillation performance. The density of glass ceramics is higher compared with the precursor glass, and it increases with the increasing temperature of heat treatment. Moreover, a blue-shift in the excitation spectra and the decreasing decay times of Tb3+ ions are obviously observed in the glass and glass ceramics with the increasing heat treatment temperature. Compared with the precursor glass, the enhanced emission intensity of Tb3+ ions in the glass ceramics is associated with the increasing energy transfer efficiency from Gd3+ to Tb3+ ions, which is due to the precipitation of BaGdF5 and BaLu2F8 nanocrystals in glass ceramics. In addition, the energy transfer efficiency from Gd3+ to Tb3+ ions was also discussed by the stretched exponential function. - Highlights: • The BaGdF5 and BaLu2F8 nanocrystals coexist in glass ceramics. • Density of glass ceramics gets higher with the increasing heat treatment temperature. • Compared with glass, the enhanced emission intensity of Tb3+ ions in glass ceramics. • Discussed the energy transfer efficiency from Gd3+ to Tb3+ ions in glass ceramics

  4. Bone bonding ability of some borate bio-glasses and their corresponding glass-ceramic derivatives

    OpenAIRE

    Fatma H. Margha; Amr M. Abdelghany

    2012-01-01

    Ternary borate glasses from the system Na2O·CaO·B2O3 together with soda-lime-borate samples containing 5 wt.% of MgO, Al2O3, SiO2 or P2O5 were prepared. The obtained glasses were converted to their glass-ceramic derivatives by controlled heat treatment. X-ray diffraction was employed to investigate the separated crystalline phases in glass-ceramics after heat treatment of the glassy samples. The glasses and corresponding glass-ceramics after immersion in water or diluted phosphate solution f...

  5. Structural and spectroscopic study of oxyfluoride glasses and glass-ceramics using europium ion as a structural probe

    Energy Technology Data Exchange (ETDEWEB)

    Bueno, L A; Gouveia-Neto, A S; Costa, E B da [Laboratorio de Fotonica, Departamento de Fisica, Universidade Federal Rural de Pernambuco, Recife 52171-900, PE (Brazil); Messaddeq, Y; Ribeiro, S J L [Instituto de Quimica, UNESP, CP 355, Araraquara 14801-970, SP (Brazil)

    2008-04-09

    Transparent oxyfluoride glasses and {beta}-PbF{sub 2} nanocrystals containing glass-ceramics were prepared with varying Eu{sup 3+} content (0.3, 0.4, 0.5 and 0.6%). The effect of Eu{sup 3+} content on the preparation of glass-ceramics was investigated. From differential scanning calorimetry, the T{sub x}-T{sub g} (T{sub x}-temperature of the onset of crystallization; T{sub g}-glass transition temperature) parameter for glasses has shown slight variation, and an exothermic peak near T{sub g} called the ceramization temperature (T{sub c}) has been observed. Heat treatments were performed at this temperature to obtain transparent glass-ceramics containing {beta}-PbF{sub 2} nanocrystals, identified by x-ray diffraction. Heat treatments for different periods of time were performed and were observed to be very important in the control of the crystal size and of the crystallization rate. Based upon the absorption spectra, the scattering level due to the presence of {beta}-PbF{sub 2} nanocrystals in the glass-ceramics was observed to be similar to that for the mother glasses. Detailed analysis of emission spectra and decay time measurements led to the identification of Eu{sup 3+} ions as the {beta}-PbF{sub 2} crystalline phase. Excitation spectra at 70 K show the interaction of Eu{sup 3+} ions with the fluorogermanate network.

  6. Electronic Conductivity of Vanadium-Tellurite Glass-Ceramics

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Yue, Yuanzheng; Bragatto, Caio B.;

    2013-01-01

    In this paper, we investigate the electronic conductivity of 2TeO2-V2O5 glass-ceramics with crystallinity ranging from 0 to 100 wt.%, i.e., from entirely amorphous to completely crystalline. The glass is prepared by the melt quenching technique, and the crystal is prepared by subsequent heat...... treatment thereof. Glass-ceramics are prepared by mixing glass and crystal powder, followed by a sintering procedure. Activation energies for electronic conduction in the glass and in the crystal are determined by fitting the Mott-Austin equation to the electronic conductivity data obtained by impedance......, and a percolation phenomenon occurs at a glass fraction of 61 wt.%, increasing from a lower conductivity in the crystal to a higher conductivity in the glass. We explain the behavior of electronic conduction in the 2TeO2-V2O5 glass-ceramics by considering constriction effects between particles as well...

  7. Microwave-assisted rapid discharge sintering of a bioactive glass-ceramic.

    Science.gov (United States)

    O'Flynn, Kevin P; Twomey, Barry; Breen, Aidan; Dowling, Denis P; Stanton, Kenneth T

    2011-07-01

    Bioactive glass-ceramics have been developed as successful bone graft materials. Although conventional sintering in an electrically-heated furnace is most commonly used, an alternative microwave plasma batch processing technique, known as rapid discharge sintering (RDS), is examined to crystallise the metastable base glass to form one or more ceramic phases. Apatite-mullite glass-ceramics (AMGC) were examined to elucidate the effects of RDS on the crystallization of a bioactive glass-ceramic. By increasing the fluorine content of the glass, the fluorapatite (FAp) and mullite crystallization onset temperatures can be reduced. Samples were sintered in a hydrogen and hydrogen/nitrogen discharge at temperatures of ≈800 and 1000 °C respectively with the higher sintering temperature required to form mullite. Results show that the material can be densified and crystallised using RDS in a considerably shorter time than conventional sintering due to heating and cooling rates of ≈400 °C/min. PMID:21574014

  8. Bioactive type glass-ceramics within incorporated aluminium; Vitroceramicos del tipo bioactivo con aluminio incorporado

    Energy Technology Data Exchange (ETDEWEB)

    Volzone, C.; Stabile, F.M.; Ortiga, J., E-mail: volzcris@netverk.com.ar [Centro de Tecnologia de Recursos Minerales y Ceramica (CETMIC), Buenos Aires (Argentina)

    2012-07-01

    Bioactive glass-ceramics are used as biomaterials for the reparation of bone tissue. They are prepared, generally, by bioglass of specific composition for each particular use. The aluminium addition in the formulation at very small quantities influences on the structural properties. Two glass-ceramics obtained by P{sub 2}O{sub 5}-Na{sub 2}O-CaO-SiO{sub 2} formulation within aluminium (0.5 % in Al{sub 2}O{sub 3} base) added through a reactive alumina and purified feldspar were analyzed. The results showed structural differences between both glass-ceramics. (author)

  9. A review of glass-ceramics for the immobilization of nuclear fuel recycle wastes

    International Nuclear Information System (INIS)

    This report reviews the status of the Canadian, German, U.S., Japanese, U.S.S.R. and Swedish programs for the development of glass-ceramic materials for immobilizing the high-level radioactive wastes arising from the recycling of used nuclear fuel. The progress made in these programs is described, with emphasis on the Canadian program for the development of sphene-based glass-ceramics. The general considerations of product performance and process feasibility for glass-ceramics as a category of waste form material are discussed. 137 refs

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

    OpenAIRE

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

    2010-01-01

    The main properties (mechanical, thermal and chemical) and clinical application for dental restoration are demonstrated for three types of glass-ceramics and sintered polycrystalline ceramic produced by Ivoclar Vivadent AG. Two types of glass-ceramics are derived from the leucite-type and the lithium disilicate-type. The third type of dental materials represents a ZrO2 ceramic. CAD/CAM technology is a procedure to manufacture dental ceramic restoration. Leucite-type glass-ceramics demonstrate...

  11. Glass Ceramic Waste Forms for Combined CS+LN+TM Fission Products Waste Streams

    Energy Technology Data Exchange (ETDEWEB)

    Crum, Jarrod V.; Turo, Laura A.; Riley, Brian J.; Tang, Ming; Kossoy, Anna; Sickafus, Kurt E.

    2010-09-23

    In this study, glass ceramics were explored as an alternative waste form for glass, the current baseline, to be used for immobilizing alkaline/alkaline earth + lanthanide (CS+LN) or CS+LN+transition metal (TM) fission-product waste streams generated by a uranium extraction (UREX+) aqueous separations type process. Results from past work on a glass waste form for the combined CS+LN waste streams showed that as waste loading increased, large fractions of crystalline phases precipitated upon slow cooling.[1] The crystalline phases had no noticeable impact on the waste form performance by the 7-day product consistency test (PCT). These results point towards the development of a glass ceramic waste form for treating CS+LN or CS+LN+TM combined waste streams. Three main benefits for exploring glass ceramics are: (1) Glass ceramics offer increased solubility of troublesome components in crystalline phases as compared to glass, leading to increased waste loading; (2) The crystalline network formed in the glass ceramic results in higher heat tolerance than glass; and (3) These glass ceramics are designed to be processed by the same melter technology as the current baseline glass waste form. It will only require adding controlled canister cooling for crystallization into a glass ceramic waste form. Highly annealed waste form (essentially crack free) with up to 50X lower surface area than a typical High-Level Waste (HLW) glass canister. Lower surface area translates directly into increased durability. This was the first full year of exploring glass ceramics for the Option 1 and 2 combined waste stream options. This work has shown that dramatic increases in waste loading are achievable by designing a glass ceramic waste form as an alternative to glass. Table S1 shows the upper limits for heat, waste loading (based on solubility), and the decay time needed before treatment can occur for glass and glass ceramic waste forms. The improvements are significant for both combined waste

  12. Precision diamond grinding of ceramics and glass

    Energy Technology Data Exchange (ETDEWEB)

    Smith, S.; Paul, H.; Scattergood, R.O.

    1988-12-01

    A new research initiative will be undertaken to investigate the effect of machine parameters and material properties on precision diamond grinding of ceramics and glass. The critical grinding depth to initiate the plastic flow-to-brittle fracture regime will be directly measured using plunge-grind tests. This information will be correlated with machine parameters such as wheel bonding and diamond grain size. Multiaxis grinding tests will then be made to provide data more closely coupled with production technology. One important aspect of the material property studies involves measuring fracture toughness at the very short crack sizes commensurate with grinding damage. Short crack toughness value`s can be much less than the long-crack toughness values measured in conventional fracture tests.

  13. Crystallization of pyroxene phases and physico-chemical properties of glass-ceramics based on Li{sub 2}O–Cr{sub 2}O{sub 3}–SiO{sub 2} eutectic glass system

    Energy Technology Data Exchange (ETDEWEB)

    Salman, S.M.; Salama, S.N.; Abo-Mosallam, H.A., E-mail: abomosallam@yahoo.com.au

    2015-01-15

    The crystallization characteristics, crystalline phase assemblages and solid solution phases developed due to thermally crystallized glasses based on the Li{sub 2}SiO{sub 3}–Li{sub 2}Si{sub 2}O{sub 5}–LiCrSi{sub 2}O{sub 6} (1028 ± 3 °C) eutectic glass system by replacing some trivalent oxides instead of Cr{sub 2}O{sub 3} were investigated. The microhardness and chemical durability of the glass-ceramics were also determined. Lithium meta and disilicate (Li{sub 2}SiO{sub 3} and Li{sub 2}Si{sub 2}O{sub 5}), lithium gallium silicate (LiGaSiO{sub 4}), and varieties of pyroxene phases, including Cr-pyroxene phase, i.e. lithium-kosmochlor (LiCrSi{sub 2}O{sub 6}), lithium aluminum silicate (LiAlSi{sub 2}O{sub 6}), lithium indium silicate (LiInSi{sub 2}O{sub 6}) and pyroxene solid solution of Li-aegerine type [Li (Fe{sub 0.5}, Cr{sub 0.5}) Si{sub 2}O{sub 6}] were the main crystalline phases formed in the crystallized glasses. There is no evidence for the formation of solid solution or liquid immiscibility gaps between LiAlSi{sub 2}O{sub 6} or LiInSi{sub 2}O{sub 6} phases and LiCrSi{sub 2}O{sub 6} phase. However, LiCrSi{sub 2}O{sub 6} and LiFeSi{sub 2}O{sub 6} components were accommodated in the pyroxene structure under favorable conditions of crystallization to form monomineralic pyroxene solid solution phase of the probably formula [Li (Fe{sub 0.5}, Cr{sub 0.5}) Si{sub 2}O{sub 6}]. The type and compatibility of the crystallized phases are discussed in relation to the compositional variation of the glasses and heat-treatment applied. The microhardness values of the crystalline materials ranged between 5282 and 6419 MPa while, the results showed that the chemical stability of the glass-ceramics was better in alkaline than in acidic media. - Highlights: • Glass ceramics based on Li{sub 2}O–Cr{sub 2}O{sub 3}–SiO{sub 2} eutectic (1028 ± 3 °C) glass were prepared. • LiCrSi{sub 2}O{sub 6} and LiFeSi{sub 2}O{sub 6} phases form monomineralic pyroxene solid

  14. A glass-ceramic material for fixation of radioactive waste

    OpenAIRE

    Bozadzhiev L.S.; Georgiev G.T.; Bozadzhiev R.L.

    2011-01-01

    In this article, a starting mixture for the preparation of glass-ceramic material for radioactive waste (RW), consisting of 85-95 mass % basanite and 5-15 mass % oxides of elements in I-VIII group of the Periodical table of elements imitating RW, is proposed. The glass-ceramic material is obtained by melting the starting mixture in air at 1450°C for 1 hour and by further crystallization of the melts at 950°C for 30 minutes. It has been noticed that the texture of the glass-ceramic mater...

  15. A Novel Technique for the Connection of Ceramic and Titanium Implant Components Using Glass Solder Bonding

    OpenAIRE

    Enrico Mick; Joachim Tinschert; Aurica Mitrovic; Rainer Bader

    2015-01-01

    Both titanium and ceramic materials provide specific advantages in dental implant technology. However, some problems, like hypersensitivity reactions, corrosion and mechanical failure, have been reported. Therefore, the combining of both materials to take advantage of their pros, while eliminating their respective cons, would be desirable. Hence, we introduced a new technique to bond titanium and ceramic materials by means of a silica-based glass ceramic solder. Cylindrical compound samples (...

  16. Resorbable glass-ceramic phosphate-based scaffolds for bone tissue engineering: synthesis, properties, and in vitro effects on human marrow stromal cells.

    Science.gov (United States)

    Vitale-Brovarone, Chiara; Ciapetti, Gabriela; Leonardi, Elisa; Baldini, Nicola; Bretcanu, Oana; Verné, Enrica; Baino, Francesco

    2011-11-01

    Highly porous bioresorbable glass-ceramic scaffolds were prepared via sponge replication method by using an open-cell polyurethane foam as a template and phosphate-based glass powders. The glass, belonging to the P2O5-SiO2-CaO-MgO-Na2O-K2O system, was synthesized by a melting-quenching route, ground, and sieved to obtain powders with a grain size of less than 30 μm. A slurry containing glass powders, polyvinyl alcohol, and water was prepared to coat the polymeric template. The removal of the polymer and the sintering of the glass powders were performed by a thermal treatment, in order to obtain an inorganic replica of the template structure. The structure and properties of the scaffold were investigated from structural, morphological, and mechanical viewpoints by means of X-ray diffraction, scanning electron microscopy, density measurements, image analysis, and compressive tests. The scaffolds exhibited a trabecular architecture that closely mimics the structure of a natural spongy bone. The solubility of the porous structures was assessed by soaking the samples in acellular simulated body fluid (SBF) and Tris-HCl for different time frames and then by assessing the scaffold weight loss. As far as the test in SBF is concerned, the nucleation of hydroxyapatite on the scaffold trabeculae demonstrates the bioactivity of the material. Biological tests were carried out using human bone marrow stromal cells to test the osteoconductivity of the material. The cells adhered to the scaffold struts and were metabolically active; it was found that cell differentiation over proliferation occurred. Therefore, the produced scaffolds, being biocompatible, bioactive, resorbable, and structurally similar to a spongy bone, can be proposed as interesting candidates for bone grafting.

  17. Resorbable glass-ceramic phosphate-based scaffolds for bone tissue engineering: synthesis, properties, and in vitro effects on human marrow stromal cells.

    Science.gov (United States)

    Vitale-Brovarone, Chiara; Ciapetti, Gabriela; Leonardi, Elisa; Baldini, Nicola; Bretcanu, Oana; Verné, Enrica; Baino, Francesco

    2011-11-01

    Highly porous bioresorbable glass-ceramic scaffolds were prepared via sponge replication method by using an open-cell polyurethane foam as a template and phosphate-based glass powders. The glass, belonging to the P2O5-SiO2-CaO-MgO-Na2O-K2O system, was synthesized by a melting-quenching route, ground, and sieved to obtain powders with a grain size of less than 30 μm. A slurry containing glass powders, polyvinyl alcohol, and water was prepared to coat the polymeric template. The removal of the polymer and the sintering of the glass powders were performed by a thermal treatment, in order to obtain an inorganic replica of the template structure. The structure and properties of the scaffold were investigated from structural, morphological, and mechanical viewpoints by means of X-ray diffraction, scanning electron microscopy, density measurements, image analysis, and compressive tests. The scaffolds exhibited a trabecular architecture that closely mimics the structure of a natural spongy bone. The solubility of the porous structures was assessed by soaking the samples in acellular simulated body fluid (SBF) and Tris-HCl for different time frames and then by assessing the scaffold weight loss. As far as the test in SBF is concerned, the nucleation of hydroxyapatite on the scaffold trabeculae demonstrates the bioactivity of the material. Biological tests were carried out using human bone marrow stromal cells to test the osteoconductivity of the material. The cells adhered to the scaffold struts and were metabolically active; it was found that cell differentiation over proliferation occurred. Therefore, the produced scaffolds, being biocompatible, bioactive, resorbable, and structurally similar to a spongy bone, can be proposed as interesting candidates for bone grafting. PMID:20566654

  18. Consolidated waste forms: glass marbles and ceramic pellets

    International Nuclear Information System (INIS)

    Glass marbles and ceramic pellets have been developed at Pacific Northwest Laboratory as part of the multibarrier concept for immobilizing high-level radioactive waste. These consolidated waste forms served as substrates for the application of various inert coatings and as ideal-sized particles for encapsulation in protective matrices. Marble and pellet formulations were based on existing defense wastes at Savannah River Plant and proposed commercial wastes. To produce marbles, glass is poured from a melter in a continuous stream into a marble-making device. Marbles were produced at PNL on a vibratory marble machine at rates as high as 60 kg/h. Other marble-making concepts were also investigated. The marble process, including a lead-encapsulation step, was judged as one of the more feasible processes for immobilizing high-level wastes. To produce ceramic pellets, a series of processing steps are required, which include: spray calcining - to dry liquid wastes to a powder; disc pelletizing - to convert waste powders to spherical pellets; sintering - to densify pellets and cause desired crystal formation. These processing steps are quite complex, and thereby render the ceramic pellet process as one of the least feasible processes for immobilizing high-level wastes

  19. Consolidated waste forms: glass marbles and ceramic pellets

    Energy Technology Data Exchange (ETDEWEB)

    Treat, R.L.; Rusin, J.M.

    1982-05-01

    Glass marbles and ceramic pellets have been developed at Pacific Northwest Laboratory as part of the multibarrier concept for immobilizing high-level radioactive waste. These consolidated waste forms served as substrates for the application of various inert coatings and as ideal-sized particles for encapsulation in protective matrices. Marble and pellet formulations were based on existing defense wastes at Savannah River Plant and proposed commercial wastes. To produce marbles, glass is poured from a melter in a continuous stream into a marble-making device. Marbles were produced at PNL on a vibratory marble machine at rates as high as 60 kg/h. Other marble-making concepts were also investigated. The marble process, including a lead-encapsulation step, was judged as one of the more feasible processes for immobilizing high-level wastes. To produce ceramic pellets, a series of processing steps are required, which include: spray calcining - to dry liquid wastes to a powder; disc pelletizing - to convert waste powders to spherical pellets; sintering - to densify pellets and cause desired crystal formation. These processing steps are quite complex, and thereby render the ceramic pellet process as one of the least feasible processes for immobilizing high-level wastes.

  20. Glass-ceramics as building materials

    Directory of Open Access Journals (Sweden)

    Rincón, J. María

    1996-06-01

    Full Text Available Glass-ceramics are materials composed as any ceramic material by several crystalline phases embedded in an amorphous or vitreous matrix, but their manufacture process implies the controlled devitrification or nucleation and growth of phases from an original glass. The original shape of the original glass molded by conventional methods is carried out by using pressing and sintering followed by crystallization steps. By both processing routes are obtained transparent and/or opaque materials, with or without colours, which after adequate control and design of composition and microstructure have numerous domestic and architectonic applications. They can be used as pavements or wall coatings and in various decorative elements. In fact, their use is very extensive in east-European, American and Asian (Japan countries in constructions for covering large surfaces. The greater advantage of the glass-ceramic process is that due to the own process of vitrification allows the incorporation in their structure of a wide range of compositions from mining and industrial residues, such as red muds, ashes, fangos, scraps... which they can in this way not only be inertizated, but furthermore it be converted without risk for the environment into products useful in construction applications, offering to the architect and to the decorator a new range of "eco-materials" with multiple complementary possibilities of the already existing architectural materials in the market.

    Los productos o materiales vitrocerámicos se componen, como cualquier material de tipo cerámico, de una o varias fases cristalinas embebidas en una matriz amorfa o vítrea, pero cuyo proceso de fabricación implica la desvitrificación o nucleación y cristalización controlada de un vidrio original o de partida. En el proceso de obtención de estos materiales se puede conservar la forma original conferida al vidrio de partida por los métodos convencionales de moldeado de vidrios

  1. CRYSTALLIZATION KINETICS OF GLASS-CERAMICS BY DIFFERENTIAL THERMAL ANALYSIS

    OpenAIRE

    A. NOZAD; Z. HAMNABARD; S. BAGHSHAHI; M. Ghasemzadeh; A. NEMATI

    2011-01-01

    The crystallization behavior of fluorphlogopite, a glass-ceramic in the MgO–SiO2–Al2O3–K2O–B2O3–F system, was studied by substitution of Li2O for K2O in the glass composition. DTA, XRD and SEM were used for the study of crystallization behavior, formed phases and microstructure of the resulting glass-ceramics. Crystallization kinetics of the glass was investigated under non-isothermal conditions, using the formal theory of transformations for heterogeneous nucleation. The crystallization resu...

  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. Cracking phenomena in lithium-di-silicate glass ceramics

    Indian Academy of Sciences (India)

    Rajat Banerjee

    2001-04-01

    Lithium-di-silicate glass ceramic (Li2O, SiO2) with uniformly oriented crystals was placed on a Vickers indentation with extrusion axis horizontally parallel to the base axis. The material was rotated through 0°– 90° and at each angle a 20 N load was applied to ascertain the crack path. It was observed that the crack length decreases and the crack deviates from its original path with increasing angle. The deviation of the crack was correlated with the component of the crack driving force and the theoretical strength of the aligned crystals at different angles.

  4. Letter report on PCT/Monolith glass ceramic corrosion tests

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, Charles L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2015-09-24

    The Savannah River National Laboratory (SRNL) is collaborating with personnel from Pacific Northwest National Laboratory (PNNL) to study advanced waste form glass ceramics for immobilization of waste from Used Nuclear Fuel (UNF) separations processes. The glass ceramic waste forms take advantage of both crystalline and glassy phases where ‘troublesome’ elements (e.g., low solubility in glass or very long-lived) partition to highly durable ceramic phases with the remainder of elements residing in the glassy phase. The ceramic phases are tailored to create certain minerals or unique crystalline structures that can host the radionuclides by binding them in their specific crystalline network while not adversely impacting the residual glass network (Crum et al., 2011). Glass ceramics have been demonstrated using a scaled melter test performed in a pilot scale (1/4 scale) cold crucible induction melter (CCIM) (Crum et al., 2014; Maio et al., 2015). This report summarizes recent results from both Phase I and Phase II bench scale tests involving crucible fabrication and corrosion testing of glass ceramics using the Product Consistency Test (PCT). Preliminary results from both Phase I and Phase II bench scale tests involving statistically designed matrices have previously been reported (Crawford, 2013; Crawford, 2014).

  5. Enhanced mid-IR emission in Yb{sup 3+}-Tm{sup 3+} co-doped oxyfluoride glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Xie Junhua [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Zhang Qiang [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Zhuang Yixi [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Liu Xiaofeng [State Key Laboratory of High Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai 201800 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Guan Miaojia; Zhu Bin; Yang Rong [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Qiu Jianrong, E-mail: qjr@zju.edu.cn [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    2011-02-10

    Graphical abstract: Display Omitted Research highlights: > Tm{sup 3+} and Yb{sup 3+} ions had been enriched in the nanocrystals of the glass ceramics. > Mid-IR luminescence intensity of the glass ceramics was enhanced. > Judd-Ofelt theory was used to calculate optical parameters. - Abstract: Tm{sup 3+}-Yb{sup 3+} co-doped transparent oxyfluoride glass ceramics were prepared through thermal treatment of the as-prepared glasses. The precipitation of nanocrystals and the incorporation of Tm{sup 3+} and Yb{sup 3+} into the nanocrystals were confirmed by X-ray diffraction and absorption spectra. Based on the Judd-Ofelt theory, the J-O parameters {Omega}{sub {lambda}} ({lambda} = 2, 4, 6), spontaneous radiative transition rates, radiative lifetimes and fluorescence branching ratios of Tm{sup 3+} in both as-prepared glasses and glass ceramics were calculated. Intense mid-IR emission and upconversion luminescence in the Tm{sup 3+} and Yb{sup 3+} co-doped glass ceramics were observed under 980 nm excitation. Especially, compared with that of the as-prepared glasses, mid-IR luminescence intensity of Tm{sup 3+} in the glass ceramics was greatly enhanced. Desirable spectroscopic characteristics suggest that these oxyfluoride glass ceramics may be promising mid-IR laser active medium.

  6. Bone bonding ability of some borate bio-glasses and their corresponding glass-ceramic derivatives

    Directory of Open Access Journals (Sweden)

    Fatma H. Margha

    2012-12-01

    Full Text Available Ternary borate glasses from the system Na2O·CaO·B2O3 together with soda-lime-borate samples containing 5 wt.% of MgO, Al2O3, SiO2 or P2O5 were prepared. The obtained glasses were converted to their glass-ceramic derivatives by controlled heat treatment. X-ray diffraction was employed to investigate the separated crystalline phases in glass-ceramics after heat treatment of the glassy samples. The glasses and corresponding glass-ceramics after immersion in water or diluted phosphate solution for extended times were characterized by the grain method (adopted by several authors and recommended by ASTM and Fourier-transform infrared spectra to justify the formation of hydroxyapatite as an indication of the bone bonding ability. The influence of glass composition on bioactivity potential was discussed too.

  7. Long-term behavior of glass-ceramic zirconolite; Etude du comportement a long terme des vitrocristallins a base de zirconolite

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Ch

    2003-07-01

    This work is a part of the investigation of new containment matrices considered for specific conditioning of radionuclides after separation. The aim was to demonstrate the long-term aqueous corrosion resistance of the glass-ceramic zirconolite considered for the conditioning of plutonium and the minor actinides. This material is composed of crystals of zirconolite (CaZrTi{sub 2}O{sub 7}) dispersed in a residual vitreous phase. It appears that glass-ceramic zirconolite presents a better kinetic behavior than the nuclear glass R 7T7. This is mainly due to a more important rate decrease that occurs more rapidly, that induces a quantity of glass altered at least 10 times as small as for R 7T7 glass. This high slowdown of the alteration rate is attributed to the formation of an alteration film that has been the subject of a specific study. We have demonstrated that the rate decrease was controlled as for the R7T7 glass by the amorphous phase of the alteration film forming a diffusion barrier for reactive species. It seems that the porosity is not the single parameter that explains the protective effect of the gel. The main differences compared with R7T7 glass are that silicon does not control the alteration of the material and that the gel is composed of two distinct phases. We have in particular identified a dense phase enriched in titanium and neodymium that probably influences deeply the kinetics. (author)

  8. Crystalline phase responsible for the permanent second-harmonic generation in chalcogenide glass-ceramics

    Science.gov (United States)

    Guignard, Marie; Nazabal, Virginie; Zhang, Xiang-Hua; Smektala, Frédéric; Moréac, Alain; Pechev, Stanislas; Zeghlache, Hassina; Kudlinski, Alexandre; Martinelli, Gilbert; Quiquempois, Yves

    2007-10-01

    Permanent second-harmonic generation (SHG) has been demonstrated in chalcogenide based glass-ceramics containing non-linear micro-crystals with a size of a few micrometers. A glass composition from the Ge-Sb-S system was chosen as the reference glass for its stability against crystallization and atmospheric corrosion. Metallic cadmium was introduced in this matrix to promote crystallite formation resulting in infrared transparent glass-ceramics. A volume crystallization of β-GeS2 phase was obtained within the glass media by heating the glass samples at 370 °C for different durations. The glass-ceramics were then investigated by Raman spectroscopy, X-ray diffraction and NanoSIMS. The second-order non-linear signals were recorded by using Maker fringes experiment and were studied as a function of the crystallized volume fraction. The results indicated a non-linearity in chalcogenide glass-ceramics about one hundred times lower than α-quartz for a 1 mm thick sample heat treated 144 h.

  9. A glass-ceramic material for fixation of radioactive waste

    Directory of Open Access Journals (Sweden)

    Bozadzhiev L.S.

    2011-01-01

    Full Text Available In this article, a starting mixture for the preparation of glass-ceramic material for radioactive waste (RW, consisting of 85-95 mass % basanite and 5-15 mass % oxides of elements in I-VIII group of the Periodical table of elements imitating RW, is proposed. The glass-ceramic material is obtained by melting the starting mixture in air at 1450°C for 1 hour and by further crystallization of the melts at 950°C for 30 minutes. It has been noticed that the texture of the glass-ceramic material is microgranular. The main mineral is pyroxene, while a mixture phases are magnetite, hematite and residual glass. It was shown that the RW elements are fixed in the pyroxene and partly in the admixture phases.

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

    International Nuclear Information System (INIS)

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

  11. Thermal insulation of pipelines by foamed glass-ceramic

    Science.gov (United States)

    Apkaryan, A. S.; Kudyakov, A. I.

    2015-01-01

    Based on broken glass, clay and organic additives granular insulating glass crystalline material and technology of its receipt are developed. The regularities of the effect of composition and firing temperature on the properties of the granules are specified. The resulting granular thermally insulating material is produced with a bulk density of 260-280 kg/m3 pellet strength - 1.74 MPa, thermal conductivity - 0.075 W/m °C, water absorption - 2.6 % by weight. The effect of the basic physical characteristics of the components of the charge on the process of pore formation is studied. According to the research results, basic parameters affecting the sustainability of the swelling glass are specified. Rational charge composition, thermal and gas synthesis mode are chosen so that the partial pressure of gases is below the surface tension of the melt. This enables the formation of granules with small closed pores and vitrified surface. The article is the result of studies on the application of materials for pipe insulation of heating mains with foamed glass ceramics.

  12. A fruitful demonstration in sensors based on upconversion luminescence of Yb3+/Er3+codoped Sb2O3-WO3-Li2O (SWL) glass-ceramic

    Science.gov (United States)

    Prasad Sukul, Prasenjit; Kumar, Kaushal

    2016-07-01

    In this article, erbium and ytterbium doped lithium tungsten antimonate (Yb3+/Er3+:Sb2O3-WO3-Li2O) glass-ceramics (GC) is synthesized and its novel applications in temperature sensing and detection of latent fingerprints is studied. It is also estimated that this material could be useful as a solar cell concentrator. The upconversion emission studies on Yb3+/Er3+:SWL glass-ceramics have shown intense green emission at 525 nm (2H11/2 → 4I15/2) & 545 nm (4s3/2 → 4I15/2). The variation of UC intensities with external temperature have shown a well-fashioned pattern, which suggests that the 2H11/2 and 4S3/2 levels of Er3+ ion are thermally coupled and can act as a temperature sensor in the 300-500 K temperature range. Dry powder of Yb3+/Er3+:SWL glass-ceramic is used to develop latent fingerprint with high contrast in green color on glass slide.

  13. Summary Report: Glass-Ceramic Waste Forms for Combined Fission Products

    Energy Technology Data Exchange (ETDEWEB)

    Crum, Jarrod V.; Riley, Brian J.; Turo, Laura A.; Tang, Ming; Kossoy, Anna

    2011-09-23

    characteristics of the waste form more predictable/flexible. However, in the future, the glass phase still needs to be accurately characterized to determine the effects of waste loading and additives on the glass structure. Initial investigations show a borosilicate glass phase rich in silica. Second, the normalized concentrations of elements leached from the waste form during static leach testing were all below 0.6 g/L after 28d at 90 C, by the Product Consistency Test (PCT), method B. These normalized concentrations are on par with durable waste glasses such as the Low-Activity Reference Material (LRM) glass. The release rates for the crystalline phases (oxyapatite and powellite) appear to be lower (more durable) than the glass phase based on the relatively low release rates of Mo, Ca, and Ln found in the crystalline phases compared to Na and B that are mainly observed in the glass phase. However, further static leach testing on individual crystalline phases is needed to confirm this statement. Third, Ion irradiation and In situ TEM observations suggest that these crystalline phases (such as oxyapatite, ln-borosilicate, and powellite) in silicate based glass ceramic waste forms exhibit stability to 1000 years at anticipated doses (2 x 10{sup 10}-2 x 10{sup 11} Gy). This is adequate for the short lived isotopes in the waste, which lead to a maximum cumulative dose of {approx}7 x 10{sup 9} Gy, reached after {approx}100 yrs, beyond which the dose contributions are negligible. The cumulate dose calculations are based on a glass-ceramic at WL = 50 mass%, where the fuel has a burn-up of 51GWd/MTIHM, immobilized after 5 yr decay from reactor discharge.

  14. Inorganic glasses and glass-ceramics studied by isothermal mechanical spectroscopy

    International Nuclear Information System (INIS)

    This paper describes isothermal mechanical spectroscopy measurements carried out in silicate glasses and LAS (Li2O-Al2O3-SiO2)-type glass-ceramics. Single alkali silicate glass Na2O.3SiO2 exhibits two relaxation peaks. The first one located at a low temperature is generally assigned to the stress-induced diffusion of alkali ions. The second relaxation peak is attributed to the 'non-bridging oxygen'. Mixed alkali silicate glasses (1 - x)Na2O.xLi2O.3SiO2 with x = 0, 0.25, 0.5, 0.75 exhibit the mixed alkali peak. And also the 'non-bridging oxygen' peak. Two LAS-type glass-ceramics having the same chemical composition but different microstructures: 'β-quartz' and 'β-spodumene' type, respectively, and their parent glass have been studied. For the glass which does not contain 'non-bridging oxygen', a single mechanical relaxation peak linked with the stress-induced movement of lithium ions is observed. On the contrary, two peaks occur in the 'β-quartz' and 'β-spodumene' glass-ceramics. The 'low-temperature' peak (∼340 K for 1 Hz) is linked with ion mobility in the respective main crystalline phase. The origin of the 'high-temperature' peak is totally different for the two glass-ceramics; in the 'β-quartz' glass-ceramic, it is due to Mg2+ and Zn2+ ion relaxation in the crystalline phase, whereas in the 'β-spodumene' glass-ceramic, it is linked with a complex entity within the residual vitreous phase

  15. Radiation stability test on multiphase glass ceramic and crystalline ceramic waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Ming; Kossoy, Anna; Jarvinen, G. D.; Crum, Jarrod V.; Turo, Laura A.; Riley, Brian J.; Brinkman, Kyle; Fox, Kevin M.; Amoroso, Jake; Marra, James C.

    2014-02-03

    A radiation stability study was performed on glass ceramic and crystalline ceramic waste forms. These materials are candidate host materials for immobilizing alkali/alkaline earth (Cs/Sr-CS) + lanthanide (LN) + transition metal (TM) fission product waste streams from nuclear fuel reprocessing. In this study, glass ceramics were fabricated using a borosilicate glass as a matrix in which to incorporate CS/LN/TM combined waste streams. The major phases in these multiphase materials are powellite, oxyaptite, pollucite, celsian, and durable residual glass phases. Al2O3 and TiO2 were combined with these waste components to produce multiphase crystalline ceramics containing hollandite-type phases, perovskites, pyrochlores and other minor metal titanate phases. For the radiation stability test, selected glass ceramic and crystalline ceramic samples were exposed to different irradiation environments including low fluxes of high-energy (~1–5 MeV) protons and alpha particles generated by an ion accelerator, high fluxes of low-energy (hundreds of keV) krypton particles generated by an ion implanter, and in-situ electron irradiations in a transmission electron microscope. These irradiation experiments were performed to simulate self-radiation effects in a waste form. Ion irradiation-induced microstructural modifications were examined using X-ray diffraction and transmission electron microscopy. Our preliminary results reveal different radiation tolerance in different crystalline phases under various radiation damage environments. However, their stability may be rate dependent which may limit the waste loading that can be achieved.

  16. Radiation stability test on multiphase glass ceramic and crystalline ceramic waste forms

    Science.gov (United States)

    Tang, Ming; Kossoy, Anna; Jarvinen, Gordon; Crum, Jarrod; Turo, Laura; Riley, Brian; Brinkman, Kyle; Fox, Kevin; Amoroso, Jake; Marra, James

    2014-05-01

    A radiation stability study was performed on glass ceramic and crystalline ceramic waste forms. These materials are candidate host materials for immobilizing alkali/alkaline earth (Cs/Sr-CS) + lanthanide (LN) + transition metal (TM) fission product waste streams from nuclear fuel reprocessing. In this study, glass ceramics were fabricated using a borosilicate glass as a matrix in which to incorporate CS/LN/TM combined waste streams. The major phases in these multiphase materials are powellite, oxyaptite, pollucite, celsian, and durable residual glass phases. Al2O3 and TiO2 were combined with these waste components to produce multiphase crystalline ceramics containing hollandite-type phases, perovskites, pyrochlores and other minor metal titanate phases. For the radiation stability test, selected glass ceramic and crystalline ceramic samples were exposed to different irradiation environments including low fluxes of high-energy (∼1-5 MeV) protons and alpha particles generated by an ion accelerator, high fluxes of low-energy (hundreds of keV) krypton particles generated by an ion implanter, and in-situ electron irradiations in a transmission electron microscope. These irradiation experiments were performed to simulate self-radiation effects in a waste form. Ion irradiation-induced microstructural modifications were examined using X-ray diffraction and transmission electron microscopy. Our preliminary results reveal different radiation tolerance in different crystalline phases under various radiation damage environments. However, their stability may be rate dependent which may limit the waste loading that can be achieved.

  17. Polyphase ceramic and glass-ceramic forms for immobilizing ICPP high-level nuclear waste

    International Nuclear Information System (INIS)

    Polyphase ceramic and glass-ceramic forms have been consolidated from simulated Idaho Chemical Processing Plant wastes by hot isostatic pressing calcined waste and chemical additives by 10000C or less. The ceramic forms can contain over 70 wt% waste with densities ranging from 3.5 to 3.85 g/cm3, depending upon the formulation. Major phases are CaF2, CaZrTi207, CaTiO3, monoclinic ZrO2, and amorphous intergranular material. The relative fraction of the phases is a function of the chemical additives (TiO2, CaO, and SiO2) and consolidation temperature. Zirconolite, the major actinide host, makes the ceramic forms extremely leach resistant for the actinide simulant U238. The amorphous phase controls the leach performance for Sr and Cs which is improved by the addition of SiO2. Glass-ceramic forms were also consolidated by HIP at waste loadings of 30 to 70 wt% with densities of 2.73 to 3.1 g/cm3 using Exxon 127 borosilicate glass frit. The glass-ceramic forms contain crystalline CaF2, Al203, and ZrSi04 (zircon) in a glass matrix. Natural mineral zircon is a stable host for 4+ valent actinides. 17 references, 3 figures, 5 tables

  18. Glass-ceramic materials from electric arc furnace dust.

    Science.gov (United States)

    Kavouras, P; Kehagias, T; Tsilika, I; Kaimakamis, G; Chrissafis, K; Kokkou, S; Papadopoulos, D; Karakostas, Th

    2007-01-31

    Electric arc furnace dust (EAFD) was vitrified with SiO2, Na2CO3 and CaCO3 powders in an electric furnace at ambient atmosphere. Vitreous products were transformed into glass-ceramic materials by two-stage heat treatment, at temperatures determined by differential thermal analysis. Both vitreous and glass-ceramic materials were chemically stable. Wollastonite (CaSiO3) was separated from the parent matrix as the dominant crystalline phase, verified by X-ray diffraction analysis and energy dispersive spectrometry. Transmission electron microscopy revealed that wollastonite crystallizes mainly in its monoclinic form. Knoop microhardness was measured with the static indentation test method in all initial vitreous products and the microhardness values were in the region of 5.0-5.5 GPa. Devitrification resulted in glass-ceramic materials with microhardness values strongly dependent on the morphology and orientation of the separated crystal phase.

  19. Study of the effect of Ca/Mg alkali-oxides ratio on the structure of a glass-ceramic based on an aluminosilicated glass containing 2wt.% of zirconolite crystalline phase

    Directory of Open Access Journals (Sweden)

    Souag R.

    2014-01-01

    Full Text Available New nuclear glass-ceramics are extensively studied for the radioactive waste confinement, due to the double confinement conferred by the glass-ceramics. In this study, a glass-ceramic constituted by an aluminosilicate glass in the system: SiO2-Al2O3-CaO-MgOZrO2-TiO2, containing 2wt.% of Ca0.83Ce0.17ZrTi1.66Al0.34O7 zirconolite, has been synthesized by the discontinuous method. Cerium, an actinide surrogate is introduced both in the glass and ceramic phases. The synthesis is performed by a double melting at 1350°C, followed by a nucleation at 564°C, during 2 h, and a crystal growth at 1010°C during 3 h. Then effect of Ca/Mg ratio on the distribution of the crystalline network in the material was studied for Ca / Mg ratios ranging from 0.4 to 5.5. For the whole of the materials, Archimedes density is about 2.80 g/cm3. X-ray diffraction (XRD analysis shows that the increase of Ca/Mg ratio leads to the increase of aluminosilicated crystalline phases with high Ca contents; the materials molar volumes remaining constant. The zirconolite phase is not affected by these additive aluminosilicated phases. The scanning electron microscopy analysis (SEM coupled with energy dispersive X-ray (EDX analysis confirmed these results; and shows the uniformity of distribution of the ceramics in the bulk of the materials.

  20. Tailored spectroscopic and optical properties in rare earth-activated glass-ceramics planar waveguides

    Science.gov (United States)

    Ristic, Davor; Van Tran, Thi Thanh; Dieudonné, Belto; Cristina, Armellini; Berneschi, Simone; Chiappini, Andrea; Chiasera, Alessandro; Varas, Stefano; Carpentiero, Alessandro; Mazzola, Maurizio; Nunzi Conti, Gualtiero; Pelli, Stefano; Speranza, Giorgio; Feron, Patrice; Duverger Arfuso, Claire; Cibiel, Gilles; Turrell, Sylvia; Tran Ngoc, Khiem; Boulard, Brigitte; Righini, Giancarlo C.; Ferrari, Maurizio

    2013-03-01

    Glass ceramic activated by rare earth ions are nanocomposite systems that exhibit specific morphologic, structural and spectroscopic properties allowing to develop interesting new physical concepts, for instance the mechanism related to the transparency, as well as novel photonic devices based on the enhancement of the luminescence. At the state of art the fabrication techniques based on bottom-up and top-down approaches appear to be viable although a specific effort is required to achieve the necessary reliability and reproducibility of the preparation protocols. In particular, the dependence of the final product on the specific parent glass and on the employed synthesis still remain an important task of the research in material science. Glass-ceramic waveguides overcome some of the efficiency problems experienced with conventional waveguides. These two-phase materials are composed of nanocrystals embedded in an amorphous matrix. The respective volume fractions of the crystalline and amorphous phases determine the properties of the glass ceramic. They also represent a valid alternative to widely used glass hosts such as silica as an effective optical medium for light propagation and luminescence enhancement. Looking to application, the enhanced spectroscopic properties typical of glass ceramic in respect to those of the amorphous structures constitute an important point for the development of integrated optics devices, including optical amplifiers, monolithic waveguide laser, novel sensors, coating of spherical microresonators, and up and down converters for solar energy exploitation.

  1. 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...

  2. The effect of flourine content on crystallization and properites of fluorisilicic mica glass-ceramic

    Institute of Scientific and Technical Information of China (English)

    CAO Xiao-gang; TIAN Jie-mo; QIN Yan-jun

    2001-01-01

    @@ Fluormica glass-ceramics are widely used in dental field because of their high esthetics, excellent biocompatibility, and good mechanical properties and machinability. The main crystalline phase in fluormica glass-ceramics is either fluorophlogopite or fluorosilicic mica. Dicor(r) is the most notable commercialized fluorsilicic mica glass-ceramics.

  3. Transmission Properties of a New Glass Ceramic and Doped with Co2+ as Saturable Absorber for 1.54 μm Er Glass Short Pulse Laser

    Institute of Scientific and Technical Information of China (English)

    YU Chunlei; CHEN Li; FENG Suya; HE Dongbing; WANG Meng; HU Lili

    2012-01-01

    The preparation and characteristics of a new transparent glass ceramic were described.Crystal phase particles with nanometer size were successfully precipitated in glass matrix,which was confirmed to be one of indium aluminum zinc oxide compounds (InxAlyZnzO).The presence of aluminum (Al) and indium (In) impurities in the zinc oxides (ZnO) crystal lattice leads to some changes of the carrier concentration in the material and then promote the sharply changes of transmission spectra in IR range wavelength.And subsequently,the IR cut-off edge blue shifted from 5.5 μm in base glass to 3 μm in transparent glass ceramic sample.Furthermore,passive Q switched 1.54 μm Er glass laser pulses with pulse energy of 10 mJ and pulse width of 800 ns were successfully obtained by using the cobalt doped transparent glass ceramic as a saturable absorber.

  4. Fiber reinforced glasses and glass-ceramics for high performance applications

    Science.gov (United States)

    Prewo, K. M.; Brennan, J. J.; Layden, G. K.

    1986-01-01

    The development of fiber reinforced glass and glass-ceramic matrix composites is described. The general concepts involved in composite fabrication and resultant composite properties are given for a broad range of fiber and matrix combinations. It is shown that composite materials can be tailored to achieve high levels of toughness, strength, and elastic stiffness, as well as wear resistance and dimensional stability.

  5. Luminescence property of Eu-doped fluorochlorozirconate glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    PEI Zhili; WANG Yongsheng; HE Dawei; MENG Xianguo

    2009-01-01

    A series of Eu2+-doped fluorochlorozireonate glass-ceramics were prepared by solid state reaction method. X-ray diffraction, pho-toluminescence, photo-stimulated luminescence (PSL) and the turbidity of fluorozirconate glass containing BaCl2 nano- and micro-crystals were measured for the samples annealed at 290 ℃ for 10 min. The PSL was attributed to the characteristic emission of Eu2+ in nano-crystallites of BaCl2, which formed in the glass upon annealing. The PSL efficiency of the glass ceramic was increased by increasing the concentration of BaCl2, which, however, resulted in the decreasing in the transparency of the sample. The sample turned to a semi-transparent glass ceramic or even an opaque and milky white one from a near-transparent glass. The trade-off between optical trans-parency and PSL intensity over different concentrations of BaCl2 for X-ray imaging plate applications was briefly discussed.

  6. 牙科用云母微晶玻璃的微观结构对其力学性能的影响%Influence of microstructure on mechanical properties of mica-based glass-ceramics for dental restorations.

    Institute of Scientific and Technical Information of China (English)

    秦燕军; 王忠义; 曹小刚; 田杰谟

    2001-01-01

    目的:研究牙科CAD/CAM加工用四硅氟云母微晶玻璃的微观结构对其力学性能的影响。方法:采用K2O-MgO-MgF2-SiO2系统来研制云母微晶玻璃,通过差热分析(DTA)、X射线衍射分析(XRD)、扫描电子显微镜观测(SEM)及力学性能测试,比较了三种不同晶化温度下,四硅氟云母微晶玻璃的微观结构对其力学性能影响。结果:随着晶化温度的逐步升高,四硅氟云母的晶粒大小和径厚比逐步增大,抗弯强度和断裂韧性亦逐渐增高,维氏硬度和脆性指数随温度升高而降低。结论:云母微晶玻璃的微观结构对其力学性能起决定作用,而微观结构与晶化温度密切相关。%Objective:To investigate the influence of microstructure onmechanical properties of mica-based machinable glass-ceramics used for CAD/CAM restorations.Methods:According to the requirements of dental restorative materials, K2O-MgO-MgF2-SiO2 system was chosen to form tetrasilicic fluormica glass-ceramics and three different temperatures were used to finish crystallization process.Differential thermal analysis(DTA),X-ray diffractometer(XRD) and scanning electron microscopy(SEM) were used to observe the crystallization behavior,crystalline phases and microstructures of the glass-ceramics.Influence of microstructure on mechanical properties of the glass-ceramics was compared.Results:Improving crystallization temperature can increase the grain sizes and aspect ratio of mica and improve the three-point bending strength and fracture toughness of the glass-ceramics.Vickers hardness and the index of brittleness decrease with increasing of temperature.Conclusion:The mechanical properties of the glass-ceramic are determined by its microstructure,while the latter has a close relationship with crystallization temperature.

  7. Crystallization Characteristic of Glass-ceramic Made from Electrolytic Manganese Residue

    Institute of Scientific and Technical Information of China (English)

    QIAN Jueshi; HOU Pengkun; WANG Zhi; QU Yanzhao

    2012-01-01

    Electrolytic manganese residue (EMR) is a waste from electrolytic manganese industry that contains high concentration of toxic substances.Since the EMR disposal in landfill sites has a serious environmental impact,new ways of EMR utilization are being sought.Considering the melting of EMR to a glass at high temperature was a relatively less energy-intensive process,EMR was first made into a base glass and then the ground base glass was heat-treated in a certain procedure to make a glass-ceramic and the crystallization process was studied.It was determined by X-ray diffraction (XRD) that the primary crystalline phases of the EMR glass-ceramic were diopside and anorthite,which formed the surface crystallization mechanism with a crystallization activation energy of 429 kJ/mol.Scanning electron microscopy (SEM)observation showed that a layer of small spherical particles with an average size of about 0.5 μm were covered on the glass matrix surface,and among them there were some big particles.The low melting temperature and crystallization activation energy make it promising to reuse EMR for glass-ceramic production.

  8. Characterization and durability testing of a glass-bonded ceramic waste form

    International Nuclear Information System (INIS)

    Argonne National Laboratory is developing a glass bonded ceramic waste form for encapsulating the fission products and transuranics from the conditioning of metallic reactor fuel. This waste form is currently being scaled to the multi-kilogram size for encapsulation of actual high level waste. This paper will present characterization and durability testing of the ceramic waste form. An emphasis on results from application of glass durability tests such as the Product Consistency Test and characterization methods such as X-ray diffraction and scanning electron microscopy. The information presented is based on a suite of tests utilized for assessing product quality during scale-up and parametric testing

  9. Study of structural, electrical, and dielectric properties of phosphate-borate glasses and glass-ceramics

    Science.gov (United States)

    Melo, B. M. G.; Graça, M. P. F.; Prezas, P. R.; Valente, M. A.; Almeida, A. F.; Freire, F. N. A.; Bih, L.

    2016-08-01

    In this work, phosphate-borate based glasses with molar composition 20.7P2O5-17.2Nb2O5-13.8WO3-34.5A2O-13.8B2O3, where A = Li, Na, and K, were prepared by the melt quenching technique. The as-prepared glasses were heat-treated in air at 800 °C for 4 h, which led to the formation of glass-ceramics. These high chemical and thermal stability glasses are good candidates for several applications such as fast ionic conductors, semiconductors, photonic materials, electrolytes, hermetic seals, rare-earth ion host solid lasers, and biomedical materials. The present work endorses the analysis of the electrical conductivity of the as-grown samples, and also the electrical, dielectric, and structural changes established by the heat-treatment process. The structure of the samples was analyzed using X-Ray powder Diffraction (XRD), Raman spectroscopy, and density measurements. Both XRD and Raman analysis confirmed crystals formation through the heat-treatment process. The electrical ac and dc conductivities, σac and σdc, respectively, and impedance spectroscopy measurements as function of the temperature, varying from 200 to 380 K, were investigated for the as-grown and heat-treated samples. The impedance spectroscopy was measured in the frequency range of 100 Hz-1 MHz.

  10. Preparation and Characteristic of Glass-Ceramics with Super Low Thermal Expansion Coefficient

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The preparation technics of glass-ceramics with super low coefficient of thermal expansion containing β-quartz solid solution as a main crystal phase based on the glass in the system Li2O-Al2O3-SiO2 was introduced. The composition of base glass, technics of melting and heat treatment effecting on characteristic of glass-ceramics was described. Specimens were prepared by melting, anneal and controlled two steps heat treatment. Crystal phase, microstructure and elementary distributing were studied by using XRD, SEM and EDS respectively. Prepared specimens show excellent transparency and super low thermal expansion coefficient of 2×10-8 ·K-1, which reaches international advanced level.

  11. Inward Cationic Diffusion and Percolation Transition in Glass-Ceramics

    DEFF Research Database (Denmark)

    Smedsklaer, Morten Mattrup; Yue, Yuanzheng; Mørup, Steen

    2010-01-01

    We show the quantitative correlation between the degree of crystallization and the cationic diffusion extent in iron-containing diopside glass–ceramics at the glass transition temperature. We find a critical degree of crystallization, above which the diffusion extent sharply drops with the degree...

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

    NARCIS (Netherlands)

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

    2015-01-01

    Aim. The aim of this comprehensive review is to systematically organize the current knowledge regarding the cementation of glass-ceramic materials and restorations, with an additional focus on the benefits of Immediate Dentin Sealing (IDS). Materials and Methods. An extensive literature search conce

  13. Bending strength of glass-ceramics based on 3CaO.P{sub 2}O{sub 5}-SiO{sub 2}-MgO glass system; Resistencia a fratura de vitroceramicos do sistema 3CaO.P{sub 2}O{sub 5}-SiO{sub 2}-MgO

    Energy Technology Data Exchange (ETDEWEB)

    Daguano, J.K.M.F.; Suzuki, P.A.; Santos, C. [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Engenharia de Materiais; Fernandes, M.H.V. [Universidade de Aveiro (UAveiro/CECICO), Aveiro (Portugal). Centro de Investigacao em Materiais Ceramicos e Compositos. Dept. de Engenharia Ceramica e do Vidro; Elias, C.N. [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Lab. de Biomateriais

    2009-07-01

    In this work, the Modulus of Rupture of bioactive glass-ceramic based on 3CaO.P{sub 2}O{sub 5}-SiO{sub 2}-MgO system was investigated, aiming its use in bone-restorations. The mechanical property was correlated with microstructural and crystallographic features of this material. High-purity starting-powders, CaCO{sub 3}, SiO{sub 2}, MgO, Ca (H{sub 2}PO{sub 4}).H{sub 2}O, were used in this study. The powders were mixed in a stoichiometric ratio, using planetary ball-mill. The suspensions were dried, sieved and melted at 1600 deg C, for 4h. The casting ones were cooled quickly until annealing temperature 700 deg C, in which remained for 2h, with controlled cooling-rate until ambient temperature. Bulks of glass were heat-treated with temperatures varying between 700 deg C and 1100 deg C, for 4h, being after that, cooled at 3 deg C/min. Bioactive glass and glass-ceramic were characterized by HRXRD (high resolution X-ray diffraction), where whitlockite was main phase. The microstructure was analyzed by scanning electronic microscopy. Modulus of Rupture was determined by four-point bending testing using specimens of 1.5 x 2 x 25 mm and glasses presented strength near to 70MPa, while glass ceramics treated at 975 deg C-4h, presented bending strength of 120MPa. (author)

  14. The influence of glass composition on crystalline phase stability in glass-ceramic wasteforms

    Energy Technology Data Exchange (ETDEWEB)

    Maddrell, Ewan, E-mail: ewan.r.maddrell@nnl.co.uk [National Nuclear Laboratory, Sellafield, Seascale, Cumbria CA20 1PG (United Kingdom); Thornber, Stephanie; Hyatt, Neil C. [Department of Materials Science and Engineering, The University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2015-01-15

    Highlights: • Crystalline phase formation shown to depend on glass matrix composition. • Zirconolite forms as the sole crystalline phase only for most aluminous glasses. • Thermodynamics indicate that low silica activity glasses stabilise zirconolite. - Abstract: Zirconolite glass-ceramic wasteforms were prepared using a suite of Na{sub 2}O–Al{sub 2}O{sub 3}–B{sub 2}O{sub 3}–SiO{sub 2} glass matrices with variable Al:B ratios. Zirconolite was the dominant crystalline phase only for the most alumina rich glass compositions. As the Al:B ratio decreased zirconolite was replaced by sphene, zircon and rutile. Thermodynamic data were used to calculate a silica activity in the glass melt below which zirconolite is the favoured crystalline phase. The concept of the crystalline reference state of glass melts is then utilised to provide a physical basis for why silica activity varies with the Al:B ratio.

  15. Healing of lithographically introduced flaws in glass and glass containing ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ackler, H.D.

    1992-12-01

    The morphological evolution of cylindrical pores or channels'' and crack-like cavities in glass and glass-containing ceramics at elevated temperatures was studied. The systems studied were: Coming 7056 alkali borosilicate glass, soda-lime glass (microscope slides), a commercially available 96% Al[sub 2]O[sub 3]with [approx]5--10% intergranular glass, 96% Al[sub 2]O[sub 3] bonded to sapphire, and a model sapphire/glass/sapphire system fabricated by diffusion bonding etched and unetched pieces of sapphire onto which 30--50 nm of SiO[sub 2] had been sputter deposited. These systems span a broad range of glass contents, and permit observation of healing behavior with varying glass content. The results were compared with analytical models and results of similar studies in completely crystalline systems.

  16. Healing of lithographically introduced flaws in glass and glass containing ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ackler, H.D.

    1992-12-01

    The morphological evolution of cylindrical pores or ``channels`` and crack-like cavities in glass and glass-containing ceramics at elevated temperatures was studied. The systems studied were: Coming 7056 alkali borosilicate glass, soda-lime glass (microscope slides), a commercially available 96% Al{sub 2}O{sub 3}with {approx}5--10% intergranular glass, 96% Al{sub 2}O{sub 3} bonded to sapphire, and a model sapphire/glass/sapphire system fabricated by diffusion bonding etched and unetched pieces of sapphire onto which 30--50 nm of SiO{sub 2} had been sputter deposited. These systems span a broad range of glass contents, and permit observation of healing behavior with varying glass content. The results were compared with analytical models and results of similar studies in completely crystalline systems.

  17. Long-term behavior of glass-ceramic zirconolite

    International Nuclear Information System (INIS)

    This work is a part of the investigation of new containment matrices considered for specific conditioning of radionuclides after separation. The aim was to demonstrate the long-term aqueous corrosion resistance of the glass-ceramic zirconolite considered for the conditioning of plutonium and the minor actinides. This material is composed of crystals of zirconolite (CaZrTi2O7) dispersed in a residual vitreous phase. It appears that glass-ceramic zirconolite presents a better kinetic behavior than the nuclear glass R 7T7. This is mainly due to a more important rate decrease that occurs more rapidly, that induces a quantity of glass altered at least 10 times as small as for R 7T7 glass. This high slowdown of the alteration rate is attributed to the formation of an alteration film that has been the subject of a specific study. We have demonstrated that the rate decrease was controlled as for the R7T7 glass by the amorphous phase of the alteration film forming a diffusion barrier for reactive species. It seems that the porosity is not the single parameter that explains the protective effect of the gel. The main differences compared with R7T7 glass are that silicon does not control the alteration of the material and that the gel is composed of two distinct phases. We have in particular identified a dense phase enriched in titanium and neodymium that probably influences deeply the kinetics. (author)

  18. Glass-ceramics obtained by the crystallization of basalt

    Directory of Open Access Journals (Sweden)

    Cocić M.

    2010-01-01

    Full Text Available The possibility to obtain glass-ceramics from basalt from the locality on Vrelo (Kopaonik mt. is shown in this paper. The parent rock was ground to fraction -0.4 +0.1 mm, and then melted at 1250 - 1300°C. The crystallization melted bazaltic glass at 950°C during the time interval of 3 hours caused synthesis of a glass-ceramic material with a microstructure that has excellent mechanical properties according to the determined dynamic modulus of elasticity and uniaxial compresive strength. The phase composition of the obtained glass ceramic material was determined by XRPD using Rietveld refinement and SEM. Two phases were found: pyroxene which corresponds to omphacite of the composition (Na0.199 K0.180 Ca0.471 Mg0.2491.1(Mg0.271Fe0.299Al0.4301.0(Si1.704Ti0.046Al0.2502.0O6 and glass with an approximate relationship 69:31.

  19. Magnetic behavior of erbium-zinc-borate glasses and glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Borodi, G. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Pascuta, P.; Bosca, M.; Pop, V. [Technical University, 28 Memorandumului, 400114 Cluj-Napoca (Romania); Stefan, R. [Agricultural Science and Veterinary Medicine University, 3-5 Calea Manastur, 400372 Cluj-Napoca (Romania); Tetean, R. [Babes-Bolyai University, 1 Mihail Kogalniceanu, Faculty of Physics, 400084 Cluj Napoca (Romania); Radulescu, D. [University of Medicine and Pharmacy Iuliu Hatieganu, 8 Victor Babes, 400012 Cluj-Napoca (Romania)

    2013-11-13

    Glasses of the system (Er{sub 2}O{sub 3}){sub x}⋅(B{sub 2}O{sub 3}){sub (60−x)}⋅(ZnO){sub 40} (3 ≤ x ≤ 15 mol%) were prepared by conventional melt quenching and subsequently converted to glass ceramics by heat treatment of glass samples at 860 °C for 2 h. The magnetic behaviour of the studied glasses and glass ceramics were investigated using a vibrating sample magnetometer (VSM) and a Faraday-type magnetic balance. Magnetic data show that erbium ions are involved in negative superexchange interactions in all the investigated samples, being antiferromagnetically coupled. For all studied samples the experimental values obtained for the effective magnetic moments are lower than the value corresponding to free Er{sup 3+} ions and decrease with the increasing of Er{sub 2}O{sub 3} content. The decrease is more pronounced in heat treated samples than untreated ones.

  20. Magnetic behavior of erbium-zinc-borate glasses and glass ceramics

    Science.gov (United States)

    Borodi, G.; Pascuta, P.; Bosca, M.; Stefan, R.; Tetean, R.; Pop, V.; Radulescu, D.

    2013-11-01

    Glasses of the system (Er2O3)xṡ(B2O3)(60-x)ṡ(ZnO)40 (3 ≤ x ≤ 15 mol%) were prepared by conventional melt quenching and subsequently converted to glass ceramics by heat treatment of glass samples at 860 °C for 2 h. The magnetic behaviour of the studied glasses and glass ceramics were investigated using a vibrating sample magnetometer (VSM) and a Faraday-type magnetic balance. Magnetic data show that erbium ions are involved in negative superexchange interactions in all the investigated samples, being antiferromagnetically coupled. For all studied samples the experimental values obtained for the effective magnetic moments are lower than the value corresponding to free Er3+ ions and decrease with the increasing of Er2O3 content. The decrease is more pronounced in heat treated samples than untreated ones.

  1. Magnetic behavior of erbium-zinc-borate glasses and glass ceramics

    International Nuclear Information System (INIS)

    Glasses of the system (Er2O3)x⋅(B2O3)(60−x)⋅(ZnO)40 (3 ≤ x ≤ 15 mol%) were prepared by conventional melt quenching and subsequently converted to glass ceramics by heat treatment of glass samples at 860 °C for 2 h. The magnetic behaviour of the studied glasses and glass ceramics were investigated using a vibrating sample magnetometer (VSM) and a Faraday-type magnetic balance. Magnetic data show that erbium ions are involved in negative superexchange interactions in all the investigated samples, being antiferromagnetically coupled. For all studied samples the experimental values obtained for the effective magnetic moments are lower than the value corresponding to free Er3+ ions and decrease with the increasing of Er2O3 content. The decrease is more pronounced in heat treated samples than untreated ones

  2. Selective laser densification of lithium aluminosilicate glass ceramic tapes

    International Nuclear Information System (INIS)

    Highlights: ► Selective laser densification of glass-ceramic tapes has been investigated. ► A possible application to the layerwise-slurry deposition process was evaluated. ► The effect of a few percent organic in the slurry was also studied. ► A range of parameters was identified to densify layers without macroscopic defects. - Abstract: Tapes, cast by blade deposition of a lithium aluminosilicate glass slurry, were sintered using a YAG-fiber laser, with the aim of finding suitable parameters for an additive manufacturing process based on layer-wise slurry deposition and selective laser densification. The influence of the laser parameters (output power and scan velocity) on the sintering was evaluated, by scanning electron microscopy and by X-ray diffraction, on the basis of the quality of the processed layer. Well densified samples could be obtained only in a small window of values for the output power and the scan velocity. The measurement of the width of a set of single scanned lines allowed also to estimate the minimum resolution of the system along the layer plane.

  3. Radiation stability test on multiphase glass ceramic and crystalline ceramic waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Ming, E-mail: mtang@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Kossoy, Anna; Jarvinen, Gordon [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Crum, Jarrod; Turo, Laura; Riley, Brian [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Brinkman, Kyle; Fox, Kevin; Amoroso, Jake; Marra, James [Savannah River National Laboratory, Aiken, SC 29808 (United States)

    2014-05-01

    A radiation stability study was performed on glass ceramic and crystalline ceramic waste forms. These materials are candidate host materials for immobilizing alkali/alkaline earth (Cs/Sr-CS) + lanthanide (LN) + transition metal (TM) fission product waste streams from nuclear fuel reprocessing. In this study, glass ceramics were fabricated using a borosilicate glass as a matrix in which to incorporate CS/LN/TM combined waste streams. The major phases in these multiphase materials are powellite, oxyaptite, pollucite, celsian, and durable residual glass phases. Al{sub 2}O{sub 3} and TiO{sub 2} were combined with these waste components to produce multiphase crystalline ceramics containing hollandite-type phases, perovskites, pyrochlores and other minor metal titanate phases. For the radiation stability test, selected glass ceramic and crystalline ceramic samples were exposed to different irradiation environments including low fluxes of high-energy (∼1–5 MeV) protons and alpha particles generated by an ion accelerator, high fluxes of low-energy (hundreds of keV) krypton particles generated by an ion implanter, and in-situ electron irradiations in a transmission electron microscope. These irradiation experiments were performed to simulate self-radiation effects in a waste form. Ion irradiation-induced microstructural modifications were examined using X-ray diffraction and transmission electron microscopy. Our preliminary results reveal different radiation tolerance in different crystalline phases under various radiation damage environments. However, their stability may be rate dependent which may limit the waste loading that can be achieved.

  4. Up-conversion luminescence of oxyfluoride glasses and nano-glass-ceramics based on them, doped with Er3+ and Er3+/Yb3+ ions: spectral and structural characteristics

    International Nuclear Information System (INIS)

    The paper is devoted to the study of spectral and structural characteristics of up-conversion luminescent (UCL) transparent oxyfluoride glass materials doped with rare earth elements Er3+ and Er3+/Yb3+. Excited with the 980 nm laser, green, red and near IR UCL bands were registered for all samples under study, both before and after their heat treatment. In the heat treated samples the intensity of the up-conversion increased significantly due to the formation of nano-crystalline phase of lead fluoride PbF2 in a glass matrix (nano-glass-ceramics). The structural analysis of the samples conducted with the method of small-angle neutron scattering (SANS) and the X-ray diffraction analysis (XRD) showed the cluster organization of nanocrystals of PbF2 in heat treated samples.

  5. Glass-ceramic hermetic seals to high thermal expansion metals

    Science.gov (United States)

    Kramer, D.P.; Massey, R.T.

    1987-04-28

    A process for forming glass-ceramic materials from an alkaline silica-lithia glass composition comprising 60-72 mole-% SiO/sub 2/, 18-27 mole-% Li/sub 2/O, 0-5 mole-% Al/sub 2/O/sub 3/, 0-6 mole-% K/sub 2/O, 0-3 mole-% B/sub 2/O/sub 3/, and 0.5-2.5 mole-% P/sub 2/O/sub 5/, which comprises heating said glass composition at a first temperature within the 950-1050/degree/C range for 5-60 minutes, and then at a devitrification temperature within the 700-900/degree/C range for about 5-300 minutes to obtain a glass-ceramic having a thermal expansion coefficient of up to 210 x 10/sup /minus/7///degree/C. These ceramics form strong, hermetic seals with high expansion metals such as stainless steel alloys. An intermediate nucleation heating step conducted at a temperature within the range of 675-750/degree/C for 10-120 minutes may be employed between the first stage and the devitrification stage. 1 fig., 2 tabs.

  6. Electrophoretic deposition of mesoporous bioactive glass on glass-ceramic foam scaffolds for bone tissue engineering.

    Science.gov (United States)

    Fiorilli, Sonia; Baino, Francesco; Cauda, Valentina; Crepaldi, Marco; Vitale-Brovarone, Chiara; Demarchi, Danilo; Onida, Barbara

    2015-01-01

    In this work, the coating of 3-D foam-like glass-ceramic scaffolds with a bioactive mesoporous glass (MBG) was investigated. The starting scaffolds, based on a non-commercial silicate glass, were fabricated by the polymer sponge replica technique followed by sintering; then, electrophoretic deposition (EPD) was applied to deposit a MBG layer on the scaffold struts. EPD was also compared with other techniques (dipping and direct in situ gelation) and it was shown to lead to the most promising results. The scaffold pore structure was maintained after the MBG coating by EPD, as assessed by SEM and micro-CT. In vitro bioactivity of the scaffolds was assessed by immersion in simulated body fluid and subsequent evaluation of hydroxyapatite (HA) formation. The deposition of a MBG coating can be a smart strategy to impart bioactive properties to the scaffold, allowing the formation of nano-structured HA agglomerates within 48 h from immersion, which does not occur on uncoated scaffold surfaces. The mechanical properties of the scaffold do not vary after the EPD (compressive strength ~19 MPa, fracture energy ~1.2 × 10(6) J m(-3)) and suggest the suitability of the prepared highly bioactive constructs as bone tissue engineering implants for load-bearing applications.

  7. Alteration kinetics of the glass-ceramic zirconolite and role of the alteration film Comparison with the SON68 glass

    Science.gov (United States)

    Martin, C.; Ribet, I.; Frugier, P.; Gin, S.

    2007-06-01

    The glass-ceramic zirconolite is being considered for specific conditioning of plutonium or the minor actinides. The actinides are distributed throughout the zirconolite crystals and the residual glass phase. Since zirconolite alteration is extremely limited, actinide release from the glass-ceramic material is mainly attributable to alteration of the residual glass. Specimens corresponding to the residual glass phase alone were therefore altered under different conditions to compare their kinetics with the one of the SON68 glass (inactive R7T7 type glass). Glass-ceramic zirconolite presents a more important rate decrease occuring more rapidly and that induces a quantity of glass altered at least 10 times as small as for SON68 glass. This slowdown of the alteration rate is attributed to the formation of an alteration film that has been the subject of a specific study. We have in particular identified a dense phase enriched in titanium and neodymium that probably influences deeply the kinetics.

  8. 晶化温度对牙科用云母微晶玻璃微观结构的影响%Influence of crystallization temperature on microstructures of mica-based glass-ceramics for dental restorations

    Institute of Scientific and Technical Information of China (English)

    秦燕军; 王忠义; 曹小刚; 田杰谟

    2001-01-01

    AIM To investigate the influence of crystallization temperature on microstructures of mica-based machinable glass-ceramics used for CAD/CAM dental restorations. METHODS According to the requirements of dental restorative materials, K2O-MgO-MgF2-SiO2 glass-ceramics system was chosen to make tetrasilicic fluormica glass-ceramics and three different temperatures were used to finish the crystallization procedure. Differential thermal analysis (DTA), X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were used to observe the crystallization behavior, crystalline phases and microstructures of the glass-ceramics. Three point bending strength was also measured. RESULTS Grain shape changes from spherical to platelike as crystallization temperature went up. Improving crystallization temperature was increase the grain size, aspect ratio and flexural strength of the mica, while the crystalline phase is not affected by temperature changes. CONCLUSION Microstructures of the glass-ceramics are determined by crystallization temperature.%目的研究晶化温度对牙科CAD/CAM加工用四硅氟云母微晶玻璃微观结构的影响. 方法选用K2O-MgO-MgF2-SiO2系统来制备云母微晶玻璃,通过差热分析(DTA)、X射线衍射分析(XRD)、扫描电子显微镜观测(SEM)及三点弯曲强度的测试,比较了三种不同晶化温度对四硅氟云母微晶玻璃的晶化特性、微观结构及抗弯强度的影响. 结果随着晶化温度的逐步升高,四硅氟云母晶粒的形态由球形转变为片层状,晶粒尺寸和径厚比逐步增大,微晶玻璃的抗弯强度也逐步升高,但其晶相组成未发生明显变化. 结论晶化温度对四硅氟云母微晶玻璃的微观结构起决定作用.

  9. History and trends of bioactive glass-ceramics.

    Science.gov (United States)

    Montazerian, Maziar; Dutra Zanotto, Edgar

    2016-05-01

    The interest around bioactive glass-ceramics (GCs) has grown significantly over the last two decades due to their appropriate biochemical and mechanical properties. The intense research effort in this field has led to some new commercial products for biomedical applications. This review article begins with the basic concepts of GC processing and development via controlled heat treatments of monolithic pieces or sinter-crystallization of powdered glasses. We then go on to describe the processing, properties, and applications of some commercial bioactive GCs and discuss selected valuable reported researches on several promising types of bioactive GCs. The article finishes with a section on open relevant research directions for bioactive GC development.

  10. A Novel Technique for the Connection of Ceramic and Titanium Implant Components Using Glass Solder Bonding

    Directory of Open Access Journals (Sweden)

    Enrico Mick

    2015-07-01

    Full Text Available Both titanium and ceramic materials provide specific advantages in dental implant technology. However, some problems, like hypersensitivity reactions, corrosion and mechanical failure, have been reported. Therefore, the combining of both materials to take advantage of their pros, while eliminating their respective cons, would be desirable. Hence, we introduced a new technique to bond titanium and ceramic materials by means of a silica-based glass ceramic solder. Cylindrical compound samples (Ø10 mm × 56 mm made of alumina toughened zirconia (ATZ, as well as titanium grade 5, were bonded by glass solder on their end faces. As a control, a two-component adhesive glue was utilized. The samples were investigated without further treatment, after 30 and 90 days of storage in distilled water at room temperature, and after aging. All samples were subjected to quasi-static four-point-bending tests. We found that the glass solder bonding provided significantly higher bending strength than adhesive glue bonding. In contrast to the glued samples, the bending strength of the soldered samples remained unaltered by the storage and aging treatments. Scanning electron microscopy (SEM and energy-dispersive X-ray (EDX analyses confirmed the presence of a stable solder-ceramic interface. Therefore, the glass solder technique represents a promising method for optimizing dental and orthopedic implant bondings.

  11. Thermophysical Properties of Multiphase Borosilicate Glass-Ceramic Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, Andrew T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Crum, Jarrod V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tang, Ming [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rouxel, T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-01-22

    Multiphase borosilicate glass-ceramics represent one candidate to contain radioactive nuclear waste separated from used nuclear fuel. In this work, the thermophysical properties from room temperature to 1273 K were investigated for four different borosilicate glass-ceramic compositions containing waste loadings from 42 to 60 wt% to determine the sensitivity of these properties to waste loading, as-fabricated microstructure, and potential evolutions in microstructure brought about by temperature transients. The thermal expansion, specific heat capacity, thermal diffusivity, and thermal conductivity are presented. The impact of increasing waste loading is shown to have a small but measurable effect on the thermophysical properties between the four compositions, contrasted to a much greater impact observed when transitioning from predominantly crystalline to amorphous systems. Thermal cycling below 1273 K was not found to measurably impact the thermophysical properties of the compositions investigated here.

  12. Experimental Study of Effect of Aging and Self-healing Behavior of Glass/Ceramic Sealant on Glass/Ceramic Sealant Used in SOFC

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenning N.; Sun, Xin; Koeppel, Brian J.; Khaleel, Mohammad A.

    2008-10-09

    High operating temperature of solid oxide fuel cells require that sealant must function at high temperature between 600o and 900oC and in the oxidizing and reducing environments of fuel and air. In this paper, experiment tests were implemented to investigate the effect of aging time and self-healing behavior of the glass ceramic sealant used in solid oxide fuel cells (SOFCs) on its mechanical properties. With longer heat treatment or aging time during operation, further crystallization may reduce the residual glass content while boosting the ceramic crystalline content. Meanwhile, the micro-damage was induced by the cooling down process from the operating temperature to the room temperature, which can potentially degrade the mechanical properties of the glass/ceramic sealant. During the reheat of the SOFC to the operating temperature, the glass/ceramic sealant exhibits the possible self-healing characterization, which can restore the mechanical performance of the glass/ceramic sealant.

  13. Crystalline phase characterization of glass-ceramic glazes

    OpenAIRE

    Rasteiro, M. G.; Gassman, Tiago; Santos, R; Antunes, E

    2007-01-01

    The firing process of five raw crystalline frits was investigated by means of DTA, XRD, heating microscopy and dilatometry. The chemical composition of the frits was determined by FAAS, to define the main glass-ceramic system of each frit. The final crystalline structure detected for the sintered frits conformed to the temperatures for which transformations were obtained during heating. The existence of a relationship between the crystallization process and sintering behaviour was confirmed. ...

  14. Preparation and Luminescence of Er3+ Doped Oxyfluoride Glass Ceramics Containing LaF3 Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Er3+ doped transparent oxyfluoride glass ceramics containing LaF3 nanocrystals were prepared and the up-con-version and near infrared luminescence behavior of Er3+ in glasses and glass ceramics were investigated. With increasing heat-treating time and temperature, the size (varied from 0 to 19 nm) and crystallinity (varied from 0 to 47%) of LaF3 nanocrystals in the glass ceramics are increased. The up-conversion luminescence intensity of Er3+ ions in the glass ceramics is much stronger than that in the glasses and increased significantly with increasing heat-treating time and temperature. The near infrared emission of Er3+ ions in the glass ceramics is found to be similar to that in the glasses.

  15. Experimental maxillary sinus augmentation using a highly bioactive glass ceramic.

    Science.gov (United States)

    Vivan, Rodrigo Ricci; Mecca, Carlos Eduardo; Biguetti, Claudia Cristina; Rennó, Ana Claudia Muniz; Okamoto, Roberta; Cavenago, Bruno Cavalini; Duarte, Marco Húngaro; Matsumoto, Mariza Akemi

    2016-02-01

    Physicochemical characteristics of a biomaterial directly influence its biological behavior and fate. However, anatomical and physiological particularities of the recipient site also seem to contribute with this process. The present study aimed to evaluate bone healing of maxillary sinus augmentation using a novel bioactive glass ceramic in comparison with a bovine hydroxyapatite. Bilateral sinus augmentation was performed in adult male rabbits, divided into 4 groups according to the biomaterial used: BO-particulate bovine HA Bio-Oss(®) (BO), BO+G-particulate bovine HA + particulate autogenous bone graft (G), BS-particulate glass ceramic (180-212 μm) Biosilicate(®) (BS), and BS+G-particulate glass ceramic + G. After 45 and 90 days, animals were euthanized and the specimens prepared to be analyzed under light and polarized microscopy, immunohistochemistry, scanning electron microscopy (SEM), and micro-computed tomography (μCT). Results revealed different degradation pattern between both biomaterials, despite the association with bone graft. BS caused a more intense chronic inflammation with foreign body reaction, which led to a difficulty in bone formation. Besides this evidence, SEM and μCT confirmed direct contact between newly formed bone and biomaterial, along with osteopontin and osteocalcin immunolabeling. Bone matrix mineralization was late in BS group but became similar to BO at day 90. These results clearly indicate that further studies about Biosilicate(®) are necessary to identify the factors that resulted in an unfavorable healing response when used in maxillary sinus augmentation. PMID:26712707

  16. Characterization of Wollastonite Glass-ceramics Made from Waste Glass and Coal Fly Ash

    Institute of Scientific and Technical Information of China (English)

    Soon-Do Yoon; Jong-Un Lee; Jeong-Hwan Lee; Yeon-Hum Yun; Wang-Jung Yoon

    2013-01-01

    The crystallization behavior of wollastonite glass-ceramics was investigated by means of X-ray diffraction (XRD)analysis and surface morphological observations,and the chemical compositions were evaluated by field emission-scanning electron microscopy (FE-SEM) and energy dispersive X-ray spectroscopy (EDS).Various heat treatment temperatures (850,900,950,1000 and 1050 ℃) were used to obtain glass-ceramics of the ideal wollastonite crystal phase as well as optimum mechanical properties and chemical durability.From XRD,FE-SEM and EDS,the crystallization of acicular crystal phase in the matrix was achieved at heat treatment temperature of 1000 and 1050 ℃,and wollastonite (CaSiO3) was found in the acicular type main crystal phase in the glass-ceramics.Various properties,such as density,compressive strength,bending strength and chemical durability were also examined.The mechanical properties of glass-ceramics obtained at the heat treatment temperature of 1000 and 1050 ℃ were superior to those obtained at the heat treatment temperature of 850 ℃.

  17. Machinability of lithium disilicate glass ceramic in in vitro dental diamond bur adjusting process.

    Science.gov (United States)

    Song, Xiao-Fei; Ren, Hai-Tao; Yin, Ling

    2016-01-01

    Esthetic high-strength lithium disilicate glass ceramics (LDGC) are used for monolithic crowns and bridges produced in dental CAD/CAM and oral adjusting processes, which machinability affects the restorative quality. A machinability study has been made in the simulated oral clinical machining of LDGC with a dental handpiece and diamond burs, regarding the diamond tool wear and chip control, machining forces and energy, surface finish and integrity. Machining forces, speeds and energy in in vitro dental adjusting of LDGC were measured by a high-speed data acquisition and force sensor system. Machined LDGC surfaces were assessed using three-dimensional non-contact chromatic confocal optical profilometry and scanning electron microscopy (SEM). Diamond bur morphology and LDGC chip shapes were also examined using SEM. Minimum tool wear but significant LDGC chip accumulations were found. Machining forces and energy significantly depended on machining conditions (pMachining speeds dropped more rapidly with increased removal rates than other glass ceramics (pmachinability indices associated with the hardness, Young's modulus and fracture toughness were derived based on the normal force-removal rate relations, which ranked LDGC the most difficult to machine among glass ceramics. Surface roughness for machined LDGC was comparable for other glass ceramics. The removal mechanisms of LDGC were dominated by penetration-induced brittle fracture and shear-induced plastic deformation. Unlike most other glass ceramics, distinct intergranular and transgranular fractures of lithium disilicate crystals were found in LDGC. This research provides the fundamental data for dental clinicians on the machinability of LDGC in intraoral adjustments.

  18. Zinc containing borate glasses and glass-ceramics: Search for biomedical applications

    Directory of Open Access Journals (Sweden)

    Amr M. Abdelghany

    2014-12-01

    Full Text Available Ternary soda lime borate glass and samples with ZnO replacing CaO up to 10 mol% were prepared and studied for their bone bonding ability. Fourier transform infrared (FTIR absorption spectra of the prepared glasses before and after immersion in simulated body fluid (SBF, for one or two weeks, showed the appearance of calcium phosphate (hydroxyapatite (HA which is an indication of bone bonding ability. X-ray diffraction patterns were measured for the glasses and indicated the presence of small peaks related to hydroxyapatite in the samples immersed in SBF. The glasses were heat treated with controlled two-step regime to convert them to their corresponding glass-ceramic derivatives. FTIR and X-ray diffraction measurements of the glass-ceramic samples (before and after immersion in SBF confirmed the appearance of HA which is influenced by ZnO content. The overall data are explained on the basis of current views about the corrosion behaviour of borate glasses including hydrolysis and direct dissolution mechanism.

  19. Fabrication and characterization of bioactive glass-ceramic using soda–lime–silica waste glass

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Mojtaba; Hashemi, Babak, E-mail: hashemib@shirazu.ac.ir

    2014-04-01

    Soda–lime–silica waste glass was used to synthesize a bioactive glass-ceramic through solid-state reactions. In comparison with the conventional route, that is, the melt-quenching and subsequent heat treatment, the present work is an economical technique. Structural and thermal properties of the samples were examined by X-ray diffraction (XRD) and differential thermal analysis (DTA). The in vitro test was utilized to assess the bioactivity level of the samples by Hanks' solution as simulated body fluid (SBF). Bioactivity assessment by atomic absorption spectroscopy (AAS) and scanning electron microscopy (SEM) was revealed that the samples with smaller amount of crystalline phase had a higher level of bioactivity. - Highlights: • A bioactive glass-ceramic was synthesized using soda–lime–silica waste glass. • Solid-state reaction method was used to synthesize bioactive glass-ceramic. • Ca{sub 2}Na{sub 2}Si{sub 3}O{sub 9} and CaNaPO{sub 4} were formed with a one-step thermal treatment condition. • The amounts of crystalline and amorphous phases influenced the bioactivity. • The sample with a smaller amount of the crystalline phase had a higher bioactivity.

  20. Development of glass-ceramics from combination of industrial wastes together with boron mining waste

    OpenAIRE

    Cicek, Bugra

    2013-01-01

    The utilization of borate mineral wastes with glass-ceramic technology was first time studied and primarily not investigated combinations of wastes were incorporated into the research. These wastes consist of; soda lime silica glass, meat bone and meal ash and fly ash. In order to investigate possible and relevant application areas in ceramics, kaolin clay, an essential raw material for ceramic industry was also employed in some studied compositions. As a result, three different glass-c...

  1. FTIR and optical assessment of zinc doped calcium phospho-borosilicate sol-gel glasses/glass-ceramics

    Science.gov (United States)

    Kumar, V.; Arora, N.; Pandey, O. P.; Kaur, G.

    2015-08-01

    CaO-P2O5-ZnO-SiO2-B2O3 glasses with varying compositions of calcium oxide and phosphorous oxide are synthesized using sol-gel technique. The glasses are heat-treated for a duration of 10 h at 500°C to obtain the glass-ceramics. The glass-ceramics and glasses are characterized using Fourier transform infrared spectroscopy (FTIR) and UV-Visible spectroscopy. Extinction coefficients, attenuation coefficients and dielectric constant have been obtained for all the glasses as well as glass ceramics. The results are discussed in light of non-bridging oxygens (NBO) and heat-treatment of glasses. In addition to this, the effect of calcium and phosphorous on the infra-red spectra has been analysed thoroughly.

  2. Pressurized heat treatment of glass-ceramic to control thermal expansion

    Science.gov (United States)

    Kramer, Daniel P.

    1985-01-01

    A method of producing a glass-ceramic having a specified thermal expansion value is disclosed. The method includes the step of pressurizing the parent glass material to a predetermined pressure during heat treatment so that the glass-ceramic produced has a specified thermal expansion value. Preferably, the glass-ceramic material is isostatically pressed. A method for forming a strong glass-ceramic to metal seal is also disclosed in which the glass-ceramic is fabricated to have a thermal expansion value equal to that of the metal. The determination of the thermal expansion value of a parent glass material placed in a high-temperature environment is also used to determine the pressure in the environment.

  3. Optical and spectroscopic properties of Eu-doped tellurite glasses and glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Stambouli, W. [Laboratoire des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des, Matériaux, Technopole de Borj-Cedria, B.P. 95 Hammam-Lif, 2050 (Tunisia); Elhouichet, H., E-mail: habib.elhouichet@fst.rnu.tn [Laboratoire des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des, Matériaux, Technopole de Borj-Cedria, B.P. 95 Hammam-Lif, 2050 (Tunisia); Département de Physique, Faculté des Sciences de Tunis, Université de Tunis-ElManar, ElManar 2092 (Tunisia); Gelloz, B. [Graduate School of Engineering, Nagoya University, 2-24-16 Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8603 (Japan); Férid, M. [Laboratoire des Matériaux Minéraux et leurs Applications, Centre National de Recherches en Sciences des, Matériaux, Technopole de Borj-Cedria, B.P. 95 Hammam-Lif, 2050 (Tunisia)

    2013-06-15

    Tellurite glasses doped with trivalent europium were prepared by the conventional melt quenching technique, in the chemical composition of (85−x) TeO{sub 2}+5La{sub 2}O{sub 3}+10TiO{sub 2}+xEu{sub 2}O{sub 3} by varying the concentration of the rare-earth ion in the order 0.5, 1 and 1.5 mol%. Using Judd–Ofelt analysis, we calculated intensity parameters (Ω{sub 2} and Ω{sub 4}), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors, the quantum yield of luminescence, and the stimulated emission cross-sections for {sup 5}D{sub 0}→{sup 7}F{sub 2} transition. The change in optical properties with the variation of Eu{sup 3+} ion concentration have been discussed and compared with other glasses. The luminescence intensity ratio, quantum efficiency and emission cross-section values support that the TeEu1.5 tellurite glass is a suitable candidate for red laser source applications. Optical properties for Eu{sup 3+} doped tellurite glass, heated for different temperature, were investigated. Crystalline phases for α-TeO{sub 2}, γ-TeO{sub 2} and TiTe{sub 3}O{sub 8} system were determined by the XRD method. The effect of heat treatment on luminescence properties in the tellurite glass was discussed. By using Eu{sup 3+} as a probe, the local structure of rare-earth ion in tellurite glass, vitro-ceramic and ceramic glass has been investigated. The evaluated J–O intensity parameters have been used to calculate different radiative and laser characteristic parameters of the {sup 5}D{sub 0} excited level. The large magnitudes of stimulated emission cross-section (σ{sub e}), branching ratio (β) and Gain bandwidth (σ{sub e}×Δλ{sub eff}) obtained for {sup 5}D{sub 0}→{sup 7}F{sub 2} (613 nm) transition for ceramic glass indicate that the present glass ceramic is promising host material for Eu{sup 3+}doped fiber amplifiers. The measured lifetime of {sup 5}D{sub 0} excited state increases with increase of the heat treatment which

  4. Creep Behavior of Glass/Ceramic Sealant and its Effect on Long-term Performance of Solid Oxide Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenning N.; Sun, Xin; Koeppel, Brian J.; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2009-10-14

    The creep behavior of glass or glass-ceramic sealant materials used in solid oxide fuel cells (SOFCs) becomes relevant under SOFC operating temperatures. In this paper, the creep of glass-ceramic sealants was experimentally examined, and a standard linear solid model was applied to capture the creep behavior of glass ceramic sealant materials developed for planar SOFCs at high temperatures. The parameters of this model were determined based on the creep test results. Furthermore, the creep model was incorporated into finite-element software programs SOFC-MP and Mentat-FC developed at Pacific Northwest National Laboratory for multi-physics simulation of SOFCs. The effect of creep of glass ceramic sealant materials on the long-term performance of SOFC stacks was investigated by studying the stability of the flow channels and the stress redistribution in the glass seal and on the various interfaces of the glass seal with other layers. Finite element analyses were performed to quantify the stresses in various parts. The stresses in glass seals were released because of creep behavior during operations.

  5. Broadband and High Efficient 1530 nm Emission from Oxyfluoride Glass Ceramics Codoped with Er3+ and Yb3+ Ions

    Institute of Scientific and Technical Information of China (English)

    LIU Bao-Rong; ZHAO Li-Juan; SUN Jian; YU Hua; SONG Jie; XU Jing-Jun

    2007-01-01

    The emission at 1530 nm and its applications in optical communications are discussed. The efficient width of the emission band △eff, which is up to 91 nm, is larger as compared with silica-based glass, bismuth glass and ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) glass doped by Er3+ ions. Under the excitation of 785 nm laser, the emission integral intensity of 1530 nm increases about five times in the glass ceramics higher than that in the glass. This is explained by the quantum cutting process by two-photon emission with phonon assistance. The results indicate that the glass ceramics are a promising candidate for developing broadband optical amplifiers in wavelength-division multiplexed systems.

  6. Series multilayer internal electrodes for high energy density glass-ceramic capacitors

    Institute of Scientific and Technical Information of China (English)

    LUO Jun; DU Jun; TANG Qun; MAO ChangHui

    2009-01-01

    The glass-ceramic dielectrics and internal electrode structures are investigated for improving the general energy storage density of capacitors.Calculation indicates that glass-ceramics acquired from glass matrix annealing at 850℃ for 3 hours can be approximately up to 17 J/cm3 in energy storage density.They are appropriately chosen as the dielectrics for preparing high energy storage density capacitors (HESDCs).A series multilayer structure of internal electrode is developed for the HESDCs,in which each layer is a combination of gold film and silver paste.This electrode structure promises the capacitor immune from the residual porosity defects inevitably brought by electrode paste sintering process,and specifically improves the electrical breakdown strength of the capacitor.Based on this new electrode structure,the energy storage densities of capacitors are increased by more than one order of magnitude compared with those traditional ones with only single layer of internal electrode.Thus,HESDCs based on the optimized glass-ceramic dielectrics can potentially achieve 7.5 J/cm3 in energy storage density,even taking into consideration the enlargement of total capacitor volumes while encapsulating practicable capacitors from dielectrics media.

  7. Production of glass-ceramics from sewage sludge and waste glass

    Science.gov (United States)

    Rozenstrauha, I.; Sosins, G.; Petersone, L.; Krage, L.; Drille, M.; Filipenkov, V.

    2011-12-01

    In the present study for recycling of sewage sludge and waste glass from JSC "Valmieras stikla skiedra" treatment of them to the dense glass-ceramic composite material using powder technology is estimated. The physical-chemical properties of composite materials were identified - density 2.19 g/cm3, lowest water absorption of 2.5% and lowest porosity of 5% for the samples obtained in the temperature range of sintering 1120 - 1140 °C. Regarding mineralogical composition of glass-ceramics the following crystalline phases were identified by XRD analysis: quartz (SiO2), anorthite (CaAl2Si2O8) and hematite (Fe2O3), which could ensure the high density of materials and improve the mechanical properties of material - compressive strength up to 60.31±5.09 - 52.67±19.18 MPa. The physical-chemical properties of novel materials corresponds to dense glass-ceramics composite which eventually could be used as a building material, e.g. for floor covering, road pavement, exterior tiles etc.

  8. Production of glass-ceramics from sewage sludge and waste glass

    International Nuclear Information System (INIS)

    In the present study for recycling of sewage sludge and waste glass from JSC 'Valmieras stikla skiedra' treatment of them to the dense glass-ceramic composite material using powder technology is estimated. The physical-chemical properties of composite materials were identified – density 2.19 g/cm3, lowest water absorption of 2.5% and lowest porosity of 5% for the samples obtained in the temperature range of sintering 1120 – 1140 °C. Regarding mineralogical composition of glass-ceramics the following crystalline phases were identified by XRD analysis: quartz (SiO2), anorthite (CaAl2Si2O8) and hematite (Fe2O3), which could ensure the high density of materials and improve the mechanical properties of material - compressive strength up to 60.31±5.09 – 52.67±19.18 MPa. The physical-chemical properties of novel materials corresponds to dense glass-ceramics composite which eventually could be used as a building material, e.g. for floor covering, road pavement, exterior tiles etc.

  9. Effects of Clear and Amber Cullet on Physical and Mechanical Properties of Glass-Ceramics Containing Zinc Hydrometallurgy Waste

    Science.gov (United States)

    Hanpongpun, Wilasinee; Jiemsirilers, Sirithan; Thavorniti, Parjaree

    The effect of glass cullet on physical and mechanical properties of glass-ceramics developed from zinc hydrometallurgy waste and glass cullet was investigated. The glass-ceramics were prepared by mixing zinc hydrometallurgy waste with glass cullet through vitrification process. Two difference types of glass cullet (clear and amber cullet) were used. The parent glasses were ground and pressed into bars and sintered at low temperature (850°C) for 2 hours. The obtained glass-ceramics had low porosity. The glass-ceramics with clear cullet exhibited higher density and strength, comparing with the glass-ceramics with amber cullet. The type and the amount of the glass cullet present in the glass-ceramics have strong effect on their properties.

  10. Up-Conversion Properties of Er3+:PbF2-CONTAINING Nanophase Glass-Ceramics

    Science.gov (United States)

    Skoptsov, N. A.; Loiko, P. A.; Yumashev, K. V.; Rachkovskaya, G. E.; Zakharevich, G. B.

    2013-05-01

    Transparent Er3+:PbF2-containing nanophase glass-ceramics was synthesized by means of heat-treatment of as-cast erbium-doped oxyfluoride glass. Optical absorption of glass and glass-ceramics was investigated in details. Temporal characteristics of luminescence associated with 4I13/2→4I15/2 transition were studied under diode-pumping that results in the determination of decay times. Intense red and green up-conversion emission was obtained with glass-ceramic samples.

  11. Processing of transparent glass-ceramics by nanocrystallisation of LaF3

    OpenAIRE

    Hémono, Nicolás; Pierre, G.; Muñoz, Francisco

    2011-01-01

    Transparent glass-ceramics have been prepared by heat-treating oxyfluoride glasses in the Na2O–Al2O3–SiO2–LaF3 system. The nanocrystallisation of LaF3 was achieved by controlling time and temperature parameters. Glasses and glass-ceramics were characterised by dilatometry, DTA, XRD and TEM. The mean crystal size (

  12. Upconversion in erbium-doped transparent glass ceramics

    Science.gov (United States)

    Jones, Gina Christine

    2005-11-01

    Transparent glass ceramics (TGCs) are a class of materials that are composed of a robust glass matrix which is densely embedded with nanometer-sized fluoride crystals: In bulk, fluoride materials tend to have poor handling and mechanical properties, and can be expensive to produce. In contrast, the forming and handling properties of the TGC are similar to those of the precursor, glass, and are engineered to be robust and mechanically stable. Rare earth ions can be incorporated into the TGC during manufacture and can become partially segregated into the crystalline phase. There they experience the low-phonon energy environment of the fluoride nanocrystallite, which induces long energy level lifetimes and enhanced frequency upconversion. Therefore, rare earth doped TGCs can have the spectroscopic properties of a crystal with the durability of an aluminosilicate glass. Upconversion fluorescence is studied for an aluminosilicate TGC containing LaF3 nanocrystallites and doped with an erbium density of 1.7 x 1020 CM-3. Time gated fluorescence and excitation spectra as well as photoluminescence decays are used to find the nature and origin of this fluorescence. It is determined that energy transfer upconversion occurs only in the nanocrystallite phase and sequential two-photon absorption upconversion occurs in both glass and crystal phases.

  13. Spectroscopic properties of Er3+ doped glass ceramics containing Sr2GdF7 nanocrystals

    International Nuclear Information System (INIS)

    The Er3+ doped transparent oxyfluoride glass ceramics containing Sr2GdF7 nanocrystals were prepared and their spectroscopic properties were discussed. The formation of Sr2GdF7 nanocrystals in the glass ceramics was confirmed by x-ray diffraction. The split peaks of the upconversion and near infrared emission bands of the Er3+ doped glass ceramics can be observed. The upconversion luminescence intensity of Er3+ in the glass ceramics increased significantly with the increasing heat treated temperature. The luminescence decay curves and time-resolved spectra indicated that the lifetime of the 4S3/2 state of Er3+ in the glass ceramic was longer than that in the glass

  14. Sol-gel technology applied to glass and crystalline ceramics

    International Nuclear Information System (INIS)

    Fixation of high level and transuranium radioactive waste in glass or alternative ceramic forms requires remotely operable processes and equipment, and sol-gel technology developed for reactor fuel refabrication appears to be applicable. Advantages of the sol-gel process are absence of dust, easy pneumatic transfer and sampling of either liquids or free-flowing solid microspheres, excellent sinterability, and equipment amenable to remote operation because of mechanical simplicity. Synthetic rock microspheres and pellets containing up to 25% simulated defense waste have been prepared by the sol-gel process. 26 refs

  15. 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...

  16. Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives.

    Science.gov (United States)

    Abdelghany, A M; Ouis, M A; Azooz, M A; ElBatal, H A; El-Bassyouni, G T

    2016-01-01

    Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass-ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550-680cm(-1) after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content.

  17. Role of SrO on the bioactivity behavior of some ternary borate glasses and their glass ceramic derivatives

    Science.gov (United States)

    Abdelghany, A. M.; Ouis, M. A.; Azooz, M. A.; ElBatal, H. A.; El-Bassyouni, G. T.

    2016-01-01

    Borate glasses containing SrO substituting both CaO and NaO were prepared and characterized for their bioactivity or bone bonding ability. Glass ceramic derivatives were prepared by thermal heat treatment process. FTIR, XRD and SEM measurements for the prepared glass and glass-ceramics before and after immersion in sodium phosphate solution for one and two weeks were carried out. The appearance of two IR peaks within the range 550-680 cm-1 after immersion in phosphate solution indicates the formation of hydroxyapatite or equivalent Sr phosphate layer. X-ray diffraction data agree with the FTIR spectral analysis. The solubility test was carried out for both glasses and glass ceramics derivatives in the same phosphate solution. The introduction of SrO increases the solubility for both glasses and glass ceramics and this is assumed to be due to the formation of Sr phosphate which is more soluble than calcium phosphate (hydroxyapatite). SEM images reveal varying changes in the surfaces of glass ceramics after immersion according to the SrO content.

  18. Structural, thermal, and optical properties of Er3+/Yb3+ co-doped oxyhalide tellurite glasses, glass-ceramics and ceramics

    International Nuclear Information System (INIS)

    Glass-ceramics and ceramics containing nano-crystals of different phases doped with Er3+/Yb3+ ions have been successfully prepared by heat treatment of the precursor oxyhalide glasses synthesized by the melt-quench method. X-ray diffraction patterns and transmission electron microscopy (TEM) images verify the precipitation of nano-crystals. Emission of Er3+ enhances several times when Yb3+ ion is added with the matrix. The Stark splitting and the intensity of different emission bands increase to a great extent when we approach to ceramics from glasses via glass-ceramics. The intensity of the blue and green emission bands increases much faster than the red and NIR emission bands. Intense upconversion emission observed by the naked eye has been quantified in terms of standard chromaticity diagram (CIE). Power dependence study shows that the upconversion of NIR radiation to visible radiation takes place mainly via photon avalanche (PA) process.

  19. A low-temperature process for the denitration of Hanford single-shell tank, nitrate-based waste utilizing the nitrate to ammonia and ceramic (NAC) or nitrate to ammonia and glass (NAG) process: Phase 2 report

    International Nuclear Information System (INIS)

    Continuing benchtop studies using Hanford single-shell tank (SST) simulants and actual Oak Ridge National Laboratory (ORNL) low-level waste (LLW), employing a new denitration process for converting nitrate to ammonia and ceramic (NAC), have conclusively shown that between 85 and 99% of the nitrate can be readily converted to gaseous ammonia. In this process, aluminum powders can be used to convert alkaline, nitrate-based supernate to ammonia and an aluminum oxide-sodium aluminate-based solid. The process may be able to use contaminated aluminum scrap metal from DOE sites to effect the conversion. The final, nitrate-free ceramic product can be pressed and sintered like other ceramics or silica and/or fluxing agents can be added to form a glassy ceramic or a flowable glass product. Based upon the starting volumes of 6.2 and 3.1 M sodium nitrate solution, volume reductions of 50 to 70% were obtained for the waste form produced. Sintered pellets produced from supernate from Melton Valley Storage Tanks (MVSTs) have been leached in accordance with the 16.1 leach test for the radioelements 85Sr and 137Cs. Despite lengthy counting times, 85Sr could not be detected in the leachates. 137Cs was only slightly above background and corresponded to a leach index of 12.2 to 13.7 after 8 months of leaching. Leach testing of unsintered and sintered reactor product spiked with hazardous metals proved that both sintered and unsintered product passed the Toxicity Characteristic Leaching Procedure (TCLP) test. Design of the equipment and flowsheet for a pilot demonstration-scale system to prove the nitrate destruction portion of the NAC process and product formation is under way

  20. Luminescence of Er3+ in Oxyfluoride Transparent Glass-Ceramics

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Erbium doped silicate, germanate, and tellurium-germanate oxyfluoride glasses were prepared in a bulk form. Through appropriate heat treatment of the as-prepared glasses, transparent glass-ceramics (TGCs) were obtained with the formation of β-PbF2∶Er3+ nanocrystals in the glass matrix were confirmed by X-ray diffraction. Well-defined diffraction peaks were observed in the samples after heat-treatment. The average crystal diameter of these precipitated crystals from full-width at half-maximum (FWHM) of the diffraction peak was estimated to be between 8 and 13 nm. Optical absorption, photoluminescence, and upconversion luminescence were measured on as-prepared glass and glass-ceramics. Luminescence spectra in the TGC samples revealed well-resolved, sharp stark-splitting peaks, which indicates that a majority of Er3+ ions has been incorporated into the crystalline phase of the nanocrystals. The intensity of the visible and near infrared luminescence mostly increases in TSG compared to that in the as-prepared glass. In 1.53 μm absorption and emission bands, the maximum absorption peak is blue-shifted from 1531 to 1507 nm, whereas the maximum emission peak is red-shifted from 1535 to 1543 nm in TGC, as compared with that in glass. The bandwidth at half-maximum (BWHM) of the emission band is significantly broader in TGC than in glass, which is beneficial to the erbium-doped fiber amplifier (EDFA). Upconversion luminescence was measured using 800 nm near-infrared light excitation. Drastically increased upconversion luminescence was observed from the TGC as compared to that from their corresponding as-prepared glasses. In addition to a strong green emission centered at 545 nm because of 4S3/2→4I15/2 transition and a weaker red emission centered at 662 nm because of 4F9/2→4I15/2 transition, generally seen from the Er3+ doped glasses, two violet emissions centered at 410 nm because of 2H9/2→4I15/2 transition and centered at 379 nm because of 4G11/2→4I15

  1. Glass ceramics for incinerator ash immobilization

    Science.gov (United States)

    Malinina, G. A.; Stefanovsky, O. I.; Stefanovsky, S. V.

    2011-09-01

    Calcined solid radioactive waste (incinerator slag) surrogate and either Na 2Si 2O 5 or Na 2B 4O 7 (borax) at various mass ratios were melted in silicon carbide crucibles in a resistive furnace at temperatures of up to 1775 K (slag without additives). Portions of the melts were poured onto a metal plate; the residues were slowly cooled in turned-off furnace. Both quenched and slowly cooled materials were composed of the same phases. At high slag contents in silicate-based materials nepheline and britholite were found to be major phases. Britholite formed at higher slag content (85 wt.%) became major phase in the vitrified slag. In the system with borax at low slag contents (25 and 50 wt.%) material are composed of predominant vitreous and minor calcium silicate larnite type phase Ca 2SiO 4 where Ca 2+ ions are replaced by different cations. The materials containing slag in amount of 75 wt.% and more are chemically durable. The changes in the structure of anionic motif of quenched samples depending on slag loading were studied by IR spectroscopy.

  2. Luminescent properties of Tb{sup 3+}-doped transparent glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Bin; Wang, Qian; Zhang, Weihuan; Ouyang, Shaoye [Key Laboratory of Photo-Electronic Material, Ningbo University, Ningbo 315211 (China); Zhang, Yuepin, E-mail: zhangyuepin@nbu.edu.cn [Key Laboratory of Photo-Electronic Material, Ningbo University, Ningbo 315211 (China); Xia, Haiping [Key Laboratory of Photo-Electronic Material, Ningbo University, Ningbo 315211 (China); Sun, Xinyuan [Department of Physics, Jingganshan University, Ji’an 343009 (China)

    2015-02-15

    Dense transparent glass ceramics containing BaGdF{sub 5} and BaLu{sub 2}F{sub 8} nanocrystals were prepared from the Tb{sup 3+}-activated SiO{sub 2}–B{sub 2}O{sub 3}–BaF{sub 2}–Lu{sub 2}O{sub 3}–Gd{sub 2}O{sub 3} oxyfluoride scintillating glasses by thermal treatment technology. Glass structure was investigated by X-ray diffraction (XRD) and scanning electron micrograph (SEM); the optical properties including transmission, luminescent properties excited under both ultraviolet light and X-ray excitation, and the decay times of the glass and glass ceramics were also investigated. The coexistence of BaGdF{sub 5} and BaLu{sub 2}F{sub 8} nanocrystals in the transparent glass ceramics was confirmed by the XRD results, which plays a key role in the improvement of scintillation performance. The density of glass ceramics is higher compared with the precursor glass, and it increases with the increasing temperature of heat treatment. Moreover, a blue-shift in the excitation spectra and the decreasing decay times of Tb{sup 3+} ions are obviously observed in the glass and glass ceramics with the increasing heat treatment temperature. Compared with the precursor glass, the enhanced emission intensity of Tb{sup 3+} ions in the glass ceramics is associated with the increasing energy transfer efficiency from Gd{sup 3+} to Tb{sup 3+} ions, which is due to the precipitation of BaGdF{sub 5} and BaLu{sub 2}F{sub 8} nanocrystals in glass ceramics. In addition, the energy transfer efficiency from Gd{sup 3+} to Tb{sup 3+} ions was also discussed by the stretched exponential function. - Highlights: • The BaGdF{sub 5} and BaLu{sub 2}F{sub 8} nanocrystals coexist in glass ceramics. • Density of glass ceramics gets higher with the increasing heat treatment temperature. • Compared with glass, the enhanced emission intensity of Tb{sup 3+} ions in glass ceramics. • Discussed the energy transfer efficiency from Gd{sup 3+} to Tb{sup 3+} ions in glass ceramics.

  3. In Vitro Evaluation of Some Types of Ferrimagnetic Glass Ceramics

    Directory of Open Access Journals (Sweden)

    S. A. M. Abdel-Hameed

    2014-01-01

    Full Text Available The present study aimed at studying the acceleration of the bioactive layer on the surface of ferrimagnetic glass ceramic with a basic composition 40Fe2O3–15P2O5–20SiO2–5TiO2 through the addition of 20% of different types of metal oxides like MgO or CaO or MnO or CuO or ZnO or CeO2. SEM, EDAX, and ICP were applied to present the results of the study. SEM and EDAX measurements indicated the presence of apatite layer formed on the surface of the prepared glass ceramics after immersion in SBF within 7 to 30 days. The investigation of the results clarified that the addition of CaO or ZnO accelerated the formation of apatite on the surfaces of the samples in the simulated body fluid faster than other metal oxides. Inductive coupled plasma (ICP analysis shows the evolution of ion extraction by the simulated body fluid solution (SBF with time in relation to the elemental composition.

  4. Thermophysical and structural studies on some glass-ceramics and role of nano size crystallites

    Energy Technology Data Exchange (ETDEWEB)

    Kothiyal, G P; A, Arvind; Kumar, Rakesh; Dixit, Anupam; Sharma, Kuldeep; Goswami, Madhumita, E-mail: gpkoth@barc.gov.in [Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Centre, Mumbai 400-085 (India)

    2009-07-15

    In this paper, we present some studies on structure and thermophysical properties of glass and glass-ceramics with possible bio-medical and sealing applications. The glass-ceramics prepared for bio-medical applications include phosphate as well as silico-phosphate compositions. In vitro bio-compatibility/activity of these materials is discussed. The glass-ceramics used for the sealing application are lithium aluminium silicate (LAS) and lithium zinc silicate (LZS). The phase formation and some aspects of thermophysical properties and sealing are discussed.

  5. Thermophysical and structural studies on some glass-ceramics and role of nano size crystallites

    International Nuclear Information System (INIS)

    In this paper, we present some studies on structure and thermophysical properties of glass and glass-ceramics with possible bio-medical and sealing applications. The glass-ceramics prepared for bio-medical applications include phosphate as well as silico-phosphate compositions. In vitro bio-compatibility/activity of these materials is discussed. The glass-ceramics used for the sealing application are lithium aluminium silicate (LAS) and lithium zinc silicate (LZS). The phase formation and some aspects of thermophysical properties and sealing are discussed.

  6. Frequency stabilization based on high finesse glass-ceramic Fabry-Perot cavity for a 632.8-nm He-Ne laser

    Science.gov (United States)

    Fu, Tingting; Yang, Kaiyong; Tan, Zhongqi; Luo, Zhifu; Wu, Suyong

    2014-12-01

    A frequency stabilization technique for a 632.8nm He-Ne laser with a high finesse Fabry-Perot cavity is introduced in this paper. The resonant frequency of the cavity is taken as the frequency standard .In this system the Fabry-Perot cavity is composed of a glass-ceramic spacer, with thermal expansion coefficient smaller than 2×10-8/°C , which means an excellent thermal stabilization which greatly decreases the thermal impacts on the cavity length in the desired constant-temperature environment.The intra-cavity spherical mirror is specially designed, which makes the Fabry-cavity a sensor element in our subsequent experiments for a new practical optical accelerometer .Both cavity mirrors were custom made in our laboratory which have reflectivities greater than 99.995% at 632.8nm, so the Fabry-Perot cavity has a finesse of about 62830. The half-maximum transmission line width is about 55.48 KHz and the free spectral range is 3.5GHz .In the experimental setup, we adopt the frequency stabilization circuit with small dithering .With proper dithering voltage, the laser can be precisely locked to the Fabry-Perot cavity minimum reflection point. Theoretically the frequency stability can reach 10-10 order.

  7. The Production of Advanced Glass Ceramic HLW Forms using Cold Crucible Induction Melter

    Energy Technology Data Exchange (ETDEWEB)

    Veronica J Rutledge; Vince Maio

    2013-10-01

    Cold Crucible Induction Melters (CCIMs) will favorably change how High-Level radioactive Waste (from nuclear fuel recovery) is treated in the 21st century. Unlike the existing Joule-Heated Melters (JHMs) currently in operation for the glass-based immobilization of High-Level Waste (HLW), CCIMs offer unique material features that will increase melt temperatures, increase throughput, increase mixing, increase loading in the waste form, lower melter foot prints, eliminate melter corrosion and lower costs. These features not only enhance the technology for producing HLW forms, but also provide advantageous attributes to the waste form by allowing more durable alternatives to glass. This paper discusses advantageous features of the CCIM, with emphasis on features that overcome the historical issues with the JHMs presently utilized, as well as the benefits of glass ceramic waste forms over borosilicate glass waste forms. These advantages are then validated based on recent INL testing to demonstrate a first-of-a-kind formulation of a non-radioactive ceramic-based waste form utilizing a CCIM.

  8. EFFECTS OF INCORPORATING NATURAL MINERALS ON PRODUCTION AND BIOACTIVITY OF BIOACTIVE GLASS CERAMICS

    Directory of Open Access Journals (Sweden)

    Franco Matias Stabile

    2016-07-01

    Full Text Available Two glass-ceramics composition were produced from natural minerals. Quartzes and feldspars were pre-selected on the basis of their purities studied by X-ray diffraction (XRD and chemical analysis. Prepared compositions of glasses precursors were two different theoretical leucite (KAlSi₂O₆ /Bioglass 45S5 (L/Bg ratios. Transformations of raw materials mixtures and glass precursors were studied by differential thermal analyses. On the basis of thermal analysis results, glass ceramics were produced and characterized by XRD. Glass-ceramics were composed of two major crystalline phases, leucite and sodium calcium silicate. Bioactivity tests were performed submerging the glass-ceramics into simulated body fluid (SBF for different periods (1, 5 and 10 days. Bioactive behavior was monitored by XRD and scanning electron microscopy (SEM. Studied samples were found to be bioactive, in which hydroxyapatite layer was developed within 5 days of contact with SBF.

  9. A new biocompatible and antibacterial phosphate free glass-ceramic for medical applications

    OpenAIRE

    Belén Cabal; Luís Alou; Fabio Cafini; Ramiro Couceiro; David Sevillano; Leticia Esteban-Tejeda; Francisco Guitián; Ramón Torrecillas; Moya, José S.

    2014-01-01

    In the attempt to find valid alternatives to classic antibiotics and in view of current limitations in the efficacy of antimicrobial-coated or loaded biomaterials, this work is focused on the development of a new glass-ceramic with antibacterial performance together with safe biocompatibility. This bactericidal glass-ceramic composed of combeite and nepheline crystals in a residual glassy matrix has been obtained using an antimicrobial soda-lime glass as a precursor. Its inhibitory effects on...

  10. TiO2 effect on crystallization mechanism and physical properties of nano glass-ceramics of MgO-Al2O3-SiO2 glass system.

    Science.gov (United States)

    Jo, Sinae; Kang, Seunggu

    2013-05-01

    The effect of TiO2 on the degree of crystallization, thermal properties and microstructure for MgO-Al2O3-SiO2 glass-ceramics system containing 0-13 wt% TiO2 and 0-1.5 wt% B2O3 in which the cordierite is the main phase was studied. Using Kissinger and Augis-Bennett equations, the activation energy, 510 kJ/mol and Avrami constant, 1.8 were calculated showing the surface-oriented crystallization would be preferred. The alpha-cordierite phase was generated in the glass-ceramics of containing TiO2 of 0-5.6 wt%. However, for the glass-ceramics of TiO2 content above 7 wt%, an alpha-cordierite disappeared and micro-cordierite phase was formed. The glass-ceramics of no TiO2 added had spherical crystals of few tens nanometer size spread in the matrix. As TiO2 content increased up to 5.6 wt%, a lump of dendrite was formed. In the glass-ceramics containing TiO2 7-13 wt%, in which the main phase is micro-cordierite, the dendrite crystal disappeared and a few hundred nanometer sized crystal particles hold tightly each other were generated. The thermal conductivity of glass-ceramics of both a-cordierite and micro-cordierite base decreased with TiO2 contend added. The thermal conductivity of glass-ceramics of 1.5 wt% TiO2 added was 3.4 W/mK which is 36% higher than that of glass-ceramics of no TiO2 added. The sintering temperature for 1.5 wt% TiO2 glass-ceramics was 965 degrees C which could be concluded as to apply to LTCC process for LED packaging. PMID:23858898

  11. Abrasive wear behaviour of bio-active glass ceramics containing apatite

    Indian Academy of Sciences (India)

    I Sevim; M K Kulekci

    2006-06-01

    In this study, abrasive wear behaviour of bio-active glass ceramic materials produced with two different processes is studied. Hot pressing process and conventional casting and controlled crystallization process were used to produce bio-active ceramics. Fracture toughness of studied material was calculated by fracture toughness equations using experimental hardness results of the bio-active glass ceramic material. Two fracture toughness equations in the literature were used to identify the wear behaviour of studied ceramics. Wear resistance results that identified with both of the equations were similar. The results showed that the abrasive wear resistance of the bio-active glass ceramics produced with hot pressing process was found to be higher than that of the ceramics produced by conventional casting and controlled crystallization process.

  12. Lead fluorosilicate glass ceramics doped with Nd3+, Er3+, and Yb3+

    Science.gov (United States)

    Petrova, O. B.; Khomyakov, A. V.

    2013-06-01

    Glasses in the PbF2-PbO-SiO2 system doped with 1 mol % of rare-earth elements (Nd3+, Er3+, or Yb3+) are synthesized and studied. The glasses were heat-treated in order to obtain glass ceramics with a fluoride crystalline phase. The changes in the structure and spectral optical properties of glass ceramics with respect to initial glasses were determined by using X-ray diffraction analysis and by studying the luminescent characteristics of dopant ions.

  13. Preparation of Machinable Bioactive Glass-ceramics by Sol-gel Method

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The purpose of this research was to prepare machinable bioactive glass-ceramics by sol-gel method. A multi-component composite sol with great uniformity and stability was first prepared by a 2-step method.The composite sol was then transformed into gel by aging under different temperatures. The gel was dried finally by super critically drying method and sintered to obtain the machinable bioactive glass-ceramics. Effect of thermal treatment on crystallization of the glass-ceramics was investigated by X-ray diffraction (XRD) analysis. Microstructure of the glass-ceramics was observed by Scanning Electron Microscopy (SEM) and the mechanism of machinability was discussed. Phlogopite and hydroxylapatite were identified as main crystal phases by XRD analysis under thermal treatment at 750 ℃ and 950 ℃ for 1.5 h separately. The relative bulk density could achieve 99%under 1050 ℃ for 4 h. Microstructure of the glass-ceramics showed that the randomly distributed phlogopite and hydroxylapatite phases were favorable to the machinability of the glass-ceramics. A mean bending strength of about 160-180 MPa and a fracture toughness parameter KIC of about 2.1-2.3 were determined for the glass-ceramics.

  14. Er-doped lead borate glasses and transparent glass ceramics for near-infrared luminescence and up-conversion applications.

    Science.gov (United States)

    Pisarski, Wojciech A; Goryczka, Tomasz; Pisarska, Joanna; Ryba-Romanowski, Witold

    2007-03-15

    Lead borate based glasses have been analyzed using Raman and infrared spectroscopy. The formation of different borate groups and the direction of BO3 BO4 conversion strongly depends on the PbO- and/or PbF2-to-B2O3 ratio in chemical composition. PbF2-PbO-B2O3 based glasses containing Er3+ ions have been studied after annealing. The orthorhombic PbF2 crystallites are formed during thermal treatment, which was evidenced by X-ray diffraction analysis. Near-infrared luminescence at 1530 nm and green up-conversion at 545 nm have been registered for samples before and after annealing. The luminescence bands correspond to 4I13/2-4I15/2 and 4S3/2-4I15/2 transitions of Er3+ ions, respectively. In comparison to the precursor glasses, the luminescence intensities are higher in the studied transparent oxyfluoride glass ceramics. Simultaneously, the half-width of the luminescence lines slightly decreases. It can be the evidence that a small amount of the Er3+ ions is incorporated into the orthorhombic PbF2 phase. PMID:17302452

  15. Laser fabricated microchannels inside photostructurable glass-ceramic

    Science.gov (United States)

    Fernández-Pradas, J. M.; Serrano, D.; Serra, P.; Morenza, J. L.

    2009-03-01

    Microchannels have been fabricated by laser direct-write in photostructurable glass-ceramic (Foturan) for their application in 3D-microfluidic systems. A Nd:YAG laser delivering 10 ns pulses at 355 nm wavelength has been used for irradiation. Afterwards, thermal treatment and chemical etching have been required for channel formation. The kinetics of channel formation and the channel morphology have been studied by optical and electron microscopy. A minimum accumulated energy (pulse energy multiplied by the number of pulses in a same site) is required to induce channel formation. Channels with symmetric round apertures at both ends can be obtained when using low pulse energies. On the contrary, irradiation with too high energetic pulses produces direct material damage in Foturan and provokes the formation of non-symmetric channels. One millimetre long channels with a minimum radius of 15 μm can be opened through Foturan slides after 15 min of chemical etching.

  16. Structure of the nanocrystals in oxyfluoride glass ceramics

    International Nuclear Information System (INIS)

    The crystallization of fluoro-silicate glasses obtained using high-purity SiO2, AlO1.5, CdF2, PbF2, ZnF2, and ErF3 has been investigated. Upon heat treatment, PbF2 nanocrystals form which host most of the Er3+ ions. The major peaks obtained by x-ray diffraction suggest that the nanocrystals are fluorite structured, but the low volume fraction of nanocrystals and line broadening due to their small size mean that unambiguous identification of the crystal structure is impossible. Therefore, atomistic simulation techniques have been performed to investigate the mechanism of incorporation of Er3+ in the PbF2 nanocrystals and polycrystalline (1-x)PbF2-xErF3 ceramics have been fabricated to study the expected phase assemblage

  17. Plutonium disposition via immobilization in ceramic or glass

    Energy Technology Data Exchange (ETDEWEB)

    Gray, L.W.; Kan, T.; Shaw, H.F.; Armantrout, A.

    1997-03-05

    The management of surplus weapons plutonium is an important and urgent task with profound environmental, national, and international security implications. In the aftermath of the Cold War, Presidential Policy Directive 13, and various analyses by renown scientific, technical, and international policy organizations have brought about a focused effort within the Department of Energy to identify and implement paths for the long term disposition of surplus weapons- usable plutonium. The central goal of this effort is to render surplus weapons plutonium as inaccessible and unattractive for reuse in nuclear weapons as the much larger and growing stock of plutonium contained in spent fuel from civilian reactors. One disposition option being considered for surplus plutonium is immobilization, in which the plutonium would be incorporated into a glass or ceramic material that would ultimately be entombed permanently in a geologic repository for high-level waste.

  18. XRD and FTIR structural investigations of erbium-doped bismuth-lead-silver glasses and glass ceramics

    International Nuclear Information System (INIS)

    Glasses with the xEr2O3(100 - x)[72Bi2O3.25PbO.3Ag2O] composition where x = 0-20 mol% were prepared and later thermally treated. The local environments characteristic of this system were investigated using X-ray diffraction and FTIR spectroscopy. The results show that the glass or glass ceramic network structure resembles to that of the host matrix, being composed of [BiO3], [BiO6], [PbO3] and [PbO4] structural units. The addition of Er2O3 stabilizes the host glass or glass ceramic structure. The erbium ions play the role of a network modifier in the studied glasses. It was shown that the heat treatment at 650 deg. C leads to the crystallization of the Bi2O3 and PbO1.44 phases.

  19. Preparation of glasses and glass ceramics of heavy metal oxides containing silver: optical, structural and electrochemical properties

    Directory of Open Access Journals (Sweden)

    Bruna A. Bregadiolli

    2012-01-01

    Full Text Available Silver containing heavy metal oxide glasses and glass ceramics of the system WO3-SbPO4-PbO-AgCl with different AgCl contents have been prepared and their thermal, structural and optical properties characterized. Glass ceramics containing metallic silver nanoparticles have been prepared by annealing glass samples at temperatures above the glass transition and analyzed by transmission electron microscopy and energy dispersive X-ray microanalysis. The presence of the metallic clusters has been also confirmed by the observation of a surface plasmon resonance band in the visible range. Cyclic voltammetric measurements indicated the presence of metallic silver into the glasses, even before to perform the thermal treatment.

  20. Effects of ZrO2 on the Microstructure of a Mica Glass-ceramic

    Institute of Scientific and Technical Information of China (English)

    秦小梅; 孙祥云; 修稚萌; 左良

    2004-01-01

    The effects of ZrO2 on the crystallinity of mica and microstructure of a machina- ble glassceramic were studied. It was found that ZrO2 is an effective nucleation agent in mica glass- ceramics. Stabilized by Ca2+, a lot of t--ZrO2 particles precipitate from ZrO2-mica glass-ceramics. The ZrO2 particles can effectively limit [0]the growth of mica crystal and benefit the mechanical properties of glass-ceramics.

  1. The precision of product consistency tests conducted with a glass-bonded ceramic waste form

    Science.gov (United States)

    Ebert, W. L.; Lewis, M. A.; Johnson, S. G.

    2002-09-01

    The product consistency test (PCT) that is used for qualification of borosilicate high-level radioactive waste (HLW) glasses for disposal can be used for the same purpose in the qualification of the glass-bonded sodalite ceramic waste form (CWF). The CWF was developed to immobilize radioactive salt wastes generated during the electrometallurgical treatment of spent sodium-bonded nuclear fuels. An interlaboratory study was conducted to measure the precision of PCTs conducted with the CWF for comparison with the precision of PCTs conducted with HLW glasses. The six independent sets of triplicate PCT results generated in the study were used to calculate the intralaboratory and interlaboratory consistency based on the concentrations of Al, B, Na, and Si in the test solutions. The results indicate that PCTs can be conducted as precisely with the CWF as with HLW glasses. For example, the values of the reproducibility standard deviation for Al, B, Na, and Si were 1.36, 0.347, 3.40, and 2.97 mg/l for PCT with CWF. These values are within the range of values measured for borosilicate glasses, including reference HLW glasses.

  2. DEVELOPMENT OF GLASS AND CRYSTALLINE CERAMIC FORMS FOR DISPOSITION OF EXCESS PLUTONIUM

    Energy Technology Data Exchange (ETDEWEB)

    Marra, James; Cozzi, A; Crawford, C.; Herman, C.; Marra, John; Peeler, D.

    2009-09-10

    In the aftermath of the Cold War, the United States Department of Energy (DOE) has identified up to 50 metric tons of excess plutonium that needs to be dispositioned. The bulk of the material is slated to be blended with uranium and fabricated into a Mixed Oxide (MOX) fuel for subsequent burning in commercial nuclear reactors. Excess plutonium-containing impurity materials making it unsuitable for fabrication into MOX fuel will need to be dispositioned via other means. Glass and crystalline ceramics have been developed and studied as candidate forms to immobilize these impure plutonium feeds. A titanate-based ceramic was identified as an excellent actinide material host. This composition was based on Synroc compositions previously developed for nuclear waste immobilization. These titanate ceramics were found to be able to accommodate extremely high quantities of fissile material and exhibit excellent aqueous durability. A lanthanide borosilicate (LaBS) glass was developed to accommodate high concentrations of plutonium and to be very tolerant of impurities yet still maintain good aqueous durability. Recent testing of alkali borosilicate compositions showed promise of using these compositions to disposition lower concentrations of plutonium using existing high level waste vitrification processes. The developed waste forms all appear to be suitable for Pu disposition. Depending on the actual types and concentrations of the Pu residue streams slated for disposition, each waste form offers unique advantages.

  3. VITRIFICATION OF LIGNITE FLY ASH AND METAL SLAGS FOR THE PRODUCTION OF GLASS AND GLASS CERAMICS

    Institute of Scientific and Technical Information of China (English)

    A.Karamberi; A.Moutsatsou

    2006-01-01

    This work focuses on the production of glass and glass-ceramics by using industrial wastes or by-products,e.g., two fly ashes from the combustion of lignite, a slag from the production of Fe-Ni and a slag from the making of steel.Vitrification took place at 1 350°-1 450℃ and crystallization was achieved by heat treatment at 900, 950 and 1 000℃.The capability of the waste to be vitrified and subsequently devitrified was determined by XRD techniques. The crystalline phase depends greatly on the structure of the by-product and the heat treatment. The final products showed low leachability and good hardness.

  4. Fabrication and characterization of bioactive glass-ceramic using soda-lime-silica waste glass.

    Science.gov (United States)

    Abbasi, Mojtaba; Hashemi, Babak

    2014-04-01

    Soda-lime-silica waste glass was used to synthesize a bioactive glass-ceramic through solid-state reactions. In comparison with the conventional route, that is, the melt-quenching and subsequent heat treatment, the present work is an economical technique. Structural and thermal properties of the samples were examined by X-ray diffraction (XRD) and differential thermal analysis (DTA). The in vitro test was utilized to assess the bioactivity level of the samples by Hanks' solution as simulated body fluid (SBF). Bioactivity assessment by atomic absorption spectroscopy (AAS) and scanning electron microscopy (SEM) was revealed that the samples with smaller amount of crystalline phase had a higher level of bioactivity. PMID:24582266

  5. Predictive Surface Roughness Model for End Milling of Machinable Glass Ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Reddy, M Mohan; Gorin, Alexander [School of Engineering and Science, Curtin University of Technology, Sarawak (Malaysia); Abou-El-Hossein, K A, E-mail: mohan.m@curtin.edu.my [Mechanical and Aeronautical Department, Nelson Mandela Metropolitan University, Port Elegebeth, 6031 (South Africa)

    2011-02-15

    Advanced ceramics of Machinable glass ceramic is attractive material to produce high accuracy miniaturized components for many applications in various industries such as aerospace, electronics, biomedical, automotive and environmental communications due to their wear resistance, high hardness, high compressive strength, good corrosion resistance and excellent high temperature properties. Many research works have been conducted in the last few years to investigate the performance of different machining operations when processing various advanced ceramics. Micro end-milling is one of the machining methods to meet the demand of micro parts. Selecting proper machining parameters are important to obtain good surface finish during machining of Machinable glass ceramic. Therefore, this paper describes the development of predictive model for the surface roughness of Machinable glass ceramic in terms of speed, feed rate by using micro end-milling operation.

  6. Predictive Surface Roughness Model for End Milling of Machinable Glass Ceramic

    International Nuclear Information System (INIS)

    Advanced ceramics of Machinable glass ceramic is attractive material to produce high accuracy miniaturized components for many applications in various industries such as aerospace, electronics, biomedical, automotive and environmental communications due to their wear resistance, high hardness, high compressive strength, good corrosion resistance and excellent high temperature properties. Many research works have been conducted in the last few years to investigate the performance of different machining operations when processing various advanced ceramics. Micro end-milling is one of the machining methods to meet the demand of micro parts. Selecting proper machining parameters are important to obtain good surface finish during machining of Machinable glass ceramic. Therefore, this paper describes the development of predictive model for the surface roughness of Machinable glass ceramic in terms of speed, feed rate by using micro end-milling operation.

  7. A study on microstructure and luminescent properties of oxyfluoride silicate glass-ceramics with (Ho3+,Yb3+):NaYF4 crystallites

    International Nuclear Information System (INIS)

    Highlights: → Oxyfluoride glass-ceramic with NaYF4 nanocrystals content the Ho3+ and Yb3+ ions. → Up-converted green emission in glass-ceramics was observed. → Up-converted red emission occurs in glass samples. → Appropriate up-conversion mechanism is proposed. - Abstract: Glass-ceramics containing NaYF4 nanocrystals were prepared by heat-treatment from oxyfluoride silicate-based glass doped with Ho3+ and Yb3+ ions. The formation of crystalline fluoride phase was confirmed by X-ray diffraction and transmission electron microscopy. Absorption and emission spectra revealed that a fraction of Ho3+ and Yb3+ ions is incorporated into the NaYF4 ordered lattice influencing spectroscopic features of glass-ceramics in comparison with those of precursor glass. Green up-conversion emission (545 nm) originating in the 5S2 level in glass-ceramics and up-converted red emission (650 nm) originating in the 5F5 level in as-melted glass were observed under optical pumping into Yb3+ absorption band and analyzed. Although both emissions in both materials are achieved by two-photon excitations, the relation between green and red emission intensity in glass-ceramics and glass implies that processes relevant to up-conversion phenomena are different. Based on a careful analysis of relaxation dynamics of Ho3+ and Yb3+ excited states, the mechanisms involved in conversion of the infrared radiation into the visible emission in these materials are proposed and discussed.

  8. A study on microstructure and luminescent properties of oxyfluoride silicate glass-ceramics with (Ho{sup 3+},Yb{sup 3+}):NaYF{sub 4} crystallites

    Energy Technology Data Exchange (ETDEWEB)

    Dominiak-Dzik, G., E-mail: G.Dominiak-Dzik@int.pan.wroc.pl [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okolna 2, 50-950 Wroclaw (Poland); Lisiecki, R.; Ryba-Romanowski, W.; Krajczyk, L. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okolna 2, 50-950 Wroclaw (Poland)

    2012-01-15

    Highlights: > Oxyfluoride glass-ceramic with NaYF{sub 4} nanocrystals content the Ho{sup 3+} and Yb{sup 3+} ions. > Up-converted green emission in glass-ceramics was observed. > Up-converted red emission occurs in glass samples. > Appropriate up-conversion mechanism is proposed. - Abstract: Glass-ceramics containing NaYF{sub 4} nanocrystals were prepared by heat-treatment from oxyfluoride silicate-based glass doped with Ho{sup 3+} and Yb{sup 3+} ions. The formation of crystalline fluoride phase was confirmed by X-ray diffraction and transmission electron microscopy. Absorption and emission spectra revealed that a fraction of Ho{sup 3+} and Yb{sup 3+} ions is incorporated into the NaYF{sub 4} ordered lattice influencing spectroscopic features of glass-ceramics in comparison with those of precursor glass. Green up-conversion emission (545 nm) originating in the {sup 5}S{sub 2} level in glass-ceramics and up-converted red emission (650 nm) originating in the {sup 5}F{sub 5} level in as-melted glass were observed under optical pumping into Yb{sup 3+} absorption band and analyzed. Although both emissions in both materials are achieved by two-photon excitations, the relation between green and red emission intensity in glass-ceramics and glass implies that processes relevant to up-conversion phenomena are different. Based on a careful analysis of relaxation dynamics of Ho{sup 3+} and Yb{sup 3+} excited states, the mechanisms involved in conversion of the infrared radiation into the visible emission in these materials are proposed and discussed.

  9. Preparation and properties of CaO-Al2O3-SiO2 glass-ceramics by sintered frits particle from mining wastes

    Directory of Open Access Journals (Sweden)

    He F.

    2014-01-01

    Full Text Available The paper reports on some experimental results obtained from the production of glass-ceramics containing gold tailings powder (GTP. Frits particle sintered technology was used to prepare glass ceramic products. SiO2, CaO, ZnO, BaO and B2O3 were selected to adjust the composition of the glass. Based on the results of differential thermal analysis (DTA, the nucleation and crystallization temperature of parent glass samples with different schedule were identified, respectively. X-ray diffraction (XRD analysis of the produced glass-ceramics materials revealed that the main crystalline phase was β-wollastonite. With the increasing of CaO content, the intensity of crystal diffractive peaks also increases. The formation of β-wollastonite crystal could be accelerated by the increasing of CaO. The glass-ceramics with fine microstructure showed better physical, mechanical properties and chemical resistance. Overall results indicated that it was a feasible attempt to produce glass-ceramics for building and decorative materials from waste materials. The amount of GTP used in the glass batches was more than 65 wt% of the whole raw.

  10. Sol-gel template synthesis of luminescent glass-ceramic rods

    Energy Technology Data Exchange (ETDEWEB)

    Secu, M., E-mail: msecu@infim.ro; Secu, C. E.; Sima, M. [National Institute of Materials Physics, Optical Processes in Nanostructured Materials Department (Romania)

    2012-03-15

    We report an original way to prepare luminescent glass-ceramic microrods containing Eu{sup 3+} doped BaF{sub 2} nanocrystals by sol-gel chemistry within the pores of a polycarbonate template membrane. Structural characterization by scanning electron microscopy and X-ray diffraction has shown the formation of glass-ceramic microrods with 0.8-m diameter of and 10 {mu}m length in which BaF{sub 2} nanocrystals of about 30 nm size are embedded. Photoluminescence measurements have indicated the incorporation of Eu{sup 3+} ions inside the BaF{sub 2} nanocrystals in a broad range of sites with low coordination symmetry. The comparison made with the bulk glass-ceramic indicated an influence of the dimensional constraints imposed by the membrane pores during xerogel formation and subsequent glass ceramization.

  11. Production of coloured glass-ceramics from incinerator ash using thermal plasma technology.

    Science.gov (United States)

    Cheng, T W; Huang, M Z; Tzeng, C C; Cheng, K B; Ueng, T H

    2007-08-01

    Incineration is a major treatment process for municipal solid waste in Taiwan. It is estimated that over 1.5 Mt of incinerator ash are produced annually. This study proposes using thermal plasma technology to treat incinerator ash. Sintered glass-ceramics were produced using quenched vitrified slag with colouring agents added. The experimental results showed that the major crystalline phases developed in the sintered glass-ceramics were gehlenite and wollastonite, but many other secondary phases also appeared depending on the colouring agents added. The physical/mechanical properties, chemical resistance and toxicity characteristic leaching procedure of the coloured glass-ceramics were satisfactory. The glass-ceramic products obtained from incinerator ash treated with thermal plasma technology have great potential for building applications.

  12. Temperature effect on the magnetic properties of the coprecipitation derived ferrimagnetic glass-ceramics

    International Nuclear Information System (INIS)

    Ferrimagnetic glass-ceramic materials are promising candidates for destruction of cancerous cells by hysteresis loss, as a consequence of the increase of the local temperature when an alternating magnetic field is applied. The glass-ceramics prepared in this work contain magnetite and hematite crystals in a glassy matrix. They can be prepared by melting the coprecipitation-derived precursors at temperatures higher than 1400 deg. C. The influence of the melting temperature on the magnetic properties of these glass-ceramics has been analysed. Room temperature hysteresis cycles in quasi-static conditions were performed using two different magnetic field, one of 12 kOe, and the other one of 500 Oe. The heat generation was estimated from calorimetric measurements, using a magnetic induction furnace. The magnetic hysteresis parameters are strongly affected by the glass-ceramics microstructure, which is influenced by the melting temperature

  13. STATIC AND DYNAMIC IN VITRO TEST OF BIOACTIVITY OF GLASS CERAMICS

    Directory of Open Access Journals (Sweden)

    JANA KOZÁNKOVÁ

    2011-06-01

    Full Text Available The bioactivity of glass ceramics from Li2O–SiO2–CaO–P2O5–CaF2 system, with different amount of fluorapatite expressed as P2O5 content, has been tested in vitro under static and dynamic regime. The paper reports the results of bioactivity test of glass ceramics in static and dynamic regime. XRD, SEM and EPMA analysis were used to characterise the sample as well as to detect the presence of new phase onto the surface of glass ceramics. The bioactivity, as demonstrated by the formation of new apatite layer, depends on P2O5 content and testing regime. In static regime, one can observe a fine microstructure of hydroxyapatite layer on the surface on glass ceramics samples. In dynamic regime, the formation rate of this layer seems to be retarded in comparison with that of static regime.

  14. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    CERN Document Server

    Blanc, Wilfried; Nguyen, Luan; Bhaktha, S N B; Sebbah, Patrick; Pal, Bishnu P; Dussardier, Bernard

    2011-01-01

    Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporati...

  15. Effect of Heat Treatment Method on Microstructure of Tailings Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    LIU Jun; OU Yang; XU Changwei; QI Hong

    2008-01-01

    A Cao-Mgo-Al2O3-SiO2 quaternary system was established with the main crystal phase design based on Diopside,and the effect of once-through sintering heat treatment on microstructure of iron tailings glass ceramics was studied by using DTA,SEM along with measurement of microhardness and volume density.The experimental results show that,when the total amount of FeO and Fe2O3 exceeds 10wt%,a large number of fine nuclei are produced in the annealing process,and the phenomenon of nucleus resorption happens during the process of nucleation heat treatment,which is unfavorable for preparing iron tailings glass ceramics through once-through sintering method.When the annealing temperature from 1250 ℃ to 830 ℃,setting crystallization time for 4h,without heat treatment,crystals are well grown with arrangement and interlocking in glass phase.At 830 ℃ the crystals are well developed,well distributed and of good size;with crystallization time of 4 h the crystals with radial shape have high content and regular arrangement.

  16. Development of Glass Ceramics Made From Ferrous Tailings and Slag in China

    Institute of Scientific and Technical Information of China (English)

    LIU Cheng-jun; SHI Pei-yang; ZHANG Da-yong; JIANG Mao-fa

    2007-01-01

    A great amount of ferrous tailings and slag cause severe damage to the ecological environment, which must be reclaimed and utilized. The composition, type, and characteristics of ferrous tailings and slag in China were introduced. The research status and the application outlook of glass ceramics made from ferrous tailings and slag were discussed. Glass ceramics made from ferrous tailings and slag can be applied to various fields, and it will be environmentally conscious materials in the 21st century.

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

    OpenAIRE

    Mahboub, F.; Zarrati, S.

    2010-01-01

    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 fabricated following manufacturer’s instructions and the marginal gap was measured by a stereomicroscope at...

  18. Intense red upconversion luminescence from Tm3+/Yb3+ codoped transparent glass ceramic.

    Science.gov (United States)

    Xu, Wei; Chen, Jianmin; Wang, Peng; Zhang, Zhiguo; Cao, Wenwu

    2012-01-15

    Tm3+/Yb3+ codoped transparent glass ceramic containing β-PbF2 nanocrystals was successfully prepared. After thermal treatment, emissions from the state of Tm3+ excited by 980 nm laser were greatly quenched by cross relaxation and the 700 nm luminescence from Tm3+:3F2,3→3H6 transition was strongly enhanced. A nearly monochromatic red luminescence band was observed. Based on the luminescence decay curves and Judd-Ofelt analysis, the strengthened cross relaxation played an important role in such phenomenon. PMID:22854468

  19. MASBAL: A computer program for predicting the composition of nuclear waste glass produced by a slurry-fed ceramic melter

    Energy Technology Data Exchange (ETDEWEB)

    Reimus, P.W.

    1987-07-01

    This report is a user's manual for the MASBAL computer program. MASBAL's objectives are to predict the composition of nuclear waste glass produced by a slurry-fed ceramic melter based on a knowledge of process conditions; to generate simulated data that can be used to estimate the uncertainty in the predicted glass composition as a function of process uncertainties; and to generate simulated data that can be used to provide a measure of the inherent variability in the glass composition as a function of the inherent variability in the feed composition. These three capabilities are important to nuclear waste glass producers because there are constraints on the range of compositions that can be processed in a ceramic melter and on the range of compositions that will be acceptable for disposal in a geologic repository. MASBAL was developed specifically to simulate the operation of the West Valley Component Test system, a commercial-scale ceramic melter system that will process high-level nuclear wastes currently stored in underground tanks at the site of the Western New York Nuclear Services Center (near West Valley, New York). The program is flexible enough, however, to simulate any slurry-fed ceramic melter system. 4 refs., 16 figs., 5 tabs.

  20. MASBAL: A computer program for predicting the composition of nuclear waste glass produced by a slurry-fed ceramic melter

    International Nuclear Information System (INIS)

    This report is a user's manual for the MASBAL computer program. MASBAL's objectives are to predict the composition of nuclear waste glass produced by a slurry-fed ceramic melter based on a knowledge of process conditions; to generate simulated data that can be used to estimate the uncertainty in the predicted glass composition as a function of process uncertainties; and to generate simulated data that can be used to provide a measure of the inherent variability in the glass composition as a function of the inherent variability in the feed composition. These three capabilities are important to nuclear waste glass producers because there are constraints on the range of compositions that can be processed in a ceramic melter and on the range of compositions that will be acceptable for disposal in a geologic repository. MASBAL was developed specifically to simulate the operation of the West Valley Component Test system, a commercial-scale ceramic melter system that will process high-level nuclear wastes currently stored in underground tanks at the site of the Western New York Nuclear Services Center (near West Valley, New York). The program is flexible enough, however, to simulate any slurry-fed ceramic melter system. 4 refs., 16 figs., 5 tabs

  1. Thermally activated conversion of a silicate gel to an oxyfluoride glass ceramic: Optical study using Eu3+ probe ion

    International Nuclear Information System (INIS)

    Sol–gel route using metal alkoxides precursor and trifluoroacetic acid as in situ fluorination reagent has been used to prepare Eu3+-doped silicate xerogel, followed by thermal annealing to obtain oxyfluoride glass ceramic containing Eu3+-doped BaF2 nanocrystals. We have used Eu3+ as probe ion and we analyzed its characteristic features (photoluminescence, optical absorption and magnetic circular dichroism) to get information about the local environment around the ion during thermally activated evolution of the sol to xerogel and then glass ceramic. As the drying and annealing proceeds silica network is formed accompanied by precipitation of the nanofluoride crystalline phase; Eu3+ coordination changes gradually from a random and assymetric CF3COO- one (in the sol) to a symmetric one (in the BaF2 nanocrystals) given by the fluorine ions. Glass ceramization is based on a homogenous crystallization mechanism with BaF2 nucleation centres resulted from thermal decomposition of Ba-trifluoacetate at around 300 °C followed by subsequent growth into BaF2 nanocrystals above 600 °C; Eu3+-ions are incorporated during the nanocrystals growth. -- Highlights: • Glass ceramization is the result of a homogenous crystallization with BaF2 nucleation centres. • Eu3+-ions are incorporated during nanocrystals growth, above 600 °C. • Eu3+-ions are embedded dominantly in the BaF2 nanocrystals in high symmetry sites

  2. Mechanical performance of a biocompatible biocide soda-lime glass-ceramic.

    Science.gov (United States)

    López-Esteban, S; Bartolomé, J F; Dí Az, L A; Esteban-Tejeda, L; Prado, C; López-Piriz, R; Torrecillas, R; Moya, J S

    2014-06-01

    A biocompatible soda-lime glass-ceramic in the SiO2-Na2O-Al2O3-CaO-B2O3 system containing combeite and nepheline as crystalline phases, has been obtained at 750°C by two different routes: (i) pressureless sintering and (ii) Spark Plasma Sintering. The SPS glass-ceramic showed a bending strength, Weibull modulus, and toughness similar values to the cortical human bone. This material had a fatigue limit slightly superior to cortical bone and at least two times higher than commercial dental glass-ceramics and dentine. The in vitro studies indicate that soda-lime glass-ceramic is fully biocompatible. The in vivo studies in beagle jaws showed that implanted SPS rods presented no inflammatory changes in soft tissues surrounding implants in any of the 10 different cases after four months implantation. The radiological analysis indicates no signs of osseointegration lack around implants. Moreover, the biocide activity of SPS glass-ceramic versus Escherichia coli, was found to be >4log indicating that it prevents implant infections. Because of this, the SPS new glass-ceramic is particularly promising for dental applications (inlay, crowns, etc). PMID:24667693

  3. Standard test method for measuring waste glass or glass ceramic durability by vapor hydration test

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2009-01-01

    1.1 The vapor hydration test method can be used to study the corrosion of a waste forms such as glasses and glass ceramics upon exposure to water vapor at elevated temperatures. In addition, the alteration phases that form can be used as indicators of those phases that may form under repository conditions. These tests; which allow altering of glass at high surface area to solution volume ratio; provide useful information regarding the alteration phases that are formed, the disposition of radioactive and hazardous components, and the alteration kinetics under the specific test conditions. This information may be used in performance assessment (McGrail et al, 2002 (1) for example). 1.2 This test method must be performed in accordance with all quality assurance requirements for acceptance of the data. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practice...

  4. New Co-containing glass ceramics saturable absorbers for 1.5-μm solid state lasers

    Science.gov (United States)

    Malyarevich, Alexander M.; Denisov, Igor A.; Yumashev, Konstantin V.; Chuvaeva, Tamara I.; Dymshits, Olga S.; Onushchenko, Alexei A.; Zhilin, Alexander A.

    2001-03-01

    New saturable absorber Q-switch for 1.54 %mum Er: glass laser is present. The saturable absorber is transparent glass ceramic containing magnesium-aluminum spinel nanocrystallites doped with tetrahedrally coordinated Co2+ ions. Q-switched pulses of up to 5.5 mJ in energy and 80 ns in duration at 1.54 micrometers were achieved. Relaxation time of the 4A2 to 4T1(4F) transition bleaching was measured to be (450+/- 150)ns. Ground-state absorption cross-sections at 1.54 micrometers wavelength were estimated to be (3.2+/- 0.4)*10-19 cm2 and (5.0+/- 0.6)X10-20 cm2, respectively. Results of study absorption and luminescence spectra of different glass ceramics on the base of magnesium-aluminum, zinc-aluminum, lithium-aluminum spinel nanocrystallites doped with tetrahedrally coordinated Co2+ ions are also analyzed.

  5. 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

  6. Thin-film solar cells on perlite glass-ceramic substrates

    Science.gov (United States)

    Petrosyan, Stepan G.; Babayan, Virab H.; Musayelyan, Ashot S.; Harutyunyan, Levon A.; Zalesski, Valery B.; Kravchenko, Vladimir M.; Leonova, Tatyana R.; Polikanin, Alexander M.; Khodin, Alexander A.

    2013-06-01

    For the first time, thin-film CIGS solar cells have been fabricated by co-evaporation on specially developed non-conducting perlite (an aluminum potassium sodium silicate natural mineral of volcanic origin) glass-ceramic substrates to develop a fully integrated photovoltaic and building element. Such glass-ceramic material can meet the physical requirements to solar cells substrates as well as the cost goals. The preliminary data presented show that CIGS solar cells deposited on ceramic substrates can exhibit efficiency higher than 10%.

  7. Wear Behaviour of Pressible Lithium Disilicate Glass Ceramic

    Science.gov (United States)

    Peng, Zhongxiao; Rahman, Muhammad Izzat Abdul; Zhang, Yu; Yin, Ling

    2015-01-01

    This paper reports effects of surface preparation and contact loads on abrasive wear properties of highly aesthetic and high-strength pressible lithium disilicate glass-ceramics (LDGC). Abrasive wear testing was performed using a pin-on-disk device in which LDGC disks prepared with different surface finishes were against alumina pins at different contact loads. Coefficients of friction and wear volumes were measured as functions of initial surface finishes and contact loads. Wear-induced surface morphology changes in both LDGC disks and alumina pins were characterized using 3D laser scanning microscopy, scanning electron microscopy and energy dispersive x-ray spectroscopy. The results show that initial surface finishes of LDGC specimens and contact loads significantly affected the friction coefficients, wear volumes and wear-induced surface roughness changes of the material. Both wear volumes and friction coefficients of LDGC increased as the load increased while surface roughness effects were complicated. For rough LDGC surfaces, three-body wear was dominant while for fine LDGC surfaces, two-body abrasive wear played a key role. Delamination, plastic deformation and brittle fracture were observed on worn LDGC surfaces. The adhesion of LDGC matrix materials to alumina pins was also discovered. This research has advanced our understanding of the abrasive wear behaviour of LDGC and will provide guidelines for better utilisation and preparation of the material for long-term success in dental restorations. PMID:25980530

  8. Progress on glass ceramic ZERODUR enabling nanometer precision

    Science.gov (United States)

    Jedamzik, Ralf; Kunisch, Clemens; Nieder, Johannes; Weber, Peter; Westerhoff, Thomas

    2016-03-01

    The Semiconductor Industry is making continuous progress in shrinking feature size developing technologies and process to achieve systems of exposure or inspection tools need to fulfill ever tighter specification on the coefficient of thermal expansion (CTE). The glass ceramic ZERODUR® is a well-established material in critical components of microlithography wafer stepper and offered with an extremely low coefficient of thermal expansion, the tightest tolerance available on market. SCHOTT is continuously improving manufacturing processes and it's method to measure and characterize the CTE behavior of ZERODUR®. This paper is focusing on the "Advanced Dilatometer" for determination of the CTE developed at SCHOTT in the recent years and introduced into production in Q1 2015. The achievement for improving the absolute CTE measurement accuracy and the reproducibility are described in detail. Those achievements are compared to the CTE measurement accuracy reported by the Physikalische Technische Bundesanstalt (PTB), the National Metrology Institute of Germany. The CTE homogeneity is of highest importance to achieve nanometer precision on larger scales. Additionally, the paper presents data on the short scale CTE homogeneity and its improvement in the last two years. The data presented in this paper will explain the capability of ZERODUR® to enable the extreme precision required for future generation of lithography equipment and processes.

  9. Remedial processing of oil shale fly ash (OSFA) and its value-added conversion into glass-ceramics.

    Science.gov (United States)

    Zhang, Zhikun; Zhang, Lei; Li, Aimin

    2015-12-01

    Recently, various solid wastes such as sewage sludge, coal fly ash and slag have been recycled into various products such as sintered bricks, ceramics and cement concrete. Application of these recycling approaches is much better and greener than conventional landfills since it can solve the problems of storage of industrial wastes and reduce exploration of natural resources for construction materials to protect the environment. Therefore, in this study, an attempt was made to recycle oil shale fly ash (OSFA), a by-product obtained from the extracting of shale oil in the oil shale industry, into a value-added glass-ceramic material via melting and sintering method. The influence of basicity (CaO/SiO2 ratio) by adding calcium oxide on the performance of glass-ceramics was studied in terms of phase transformation, mechanical properties, chemical resistances and heavy metals leaching tests. Crystallization kinetics results showed that the increase of basicity reduced the activation energies of crystallization but did not change the crystallization mechanism. When increasing the basicity from 0.2 to 0.5, the densification of sintering body was enhanced due to the promotion of viscous flow of glass powders, and therefore the compression strength and bending strength of glass-ceramics were increased. Heavy metals leaching results indicated that the produced OSFA-based glass-ceramics could be taken as non-hazardous materials. The maximum mechanical properties of compression strength of 186 ± 3 MPa, bending strength of 78 ± 6 MPa, good chemical resistances and low heavy metals leaching concentrations showed that it could be used as a substitute material for construction applications. The proposed approach will be one of the potential sustainable solutions in reducing the storage of oil shale fly ash as well as converting it into a value-added product. PMID:26387050

  10. Remedial processing of oil shale fly ash (OSFA) and its value-added conversion into glass-ceramics.

    Science.gov (United States)

    Zhang, Zhikun; Zhang, Lei; Li, Aimin

    2015-12-01

    Recently, various solid wastes such as sewage sludge, coal fly ash and slag have been recycled into various products such as sintered bricks, ceramics and cement concrete. Application of these recycling approaches is much better and greener than conventional landfills since it can solve the problems of storage of industrial wastes and reduce exploration of natural resources for construction materials to protect the environment. Therefore, in this study, an attempt was made to recycle oil shale fly ash (OSFA), a by-product obtained from the extracting of shale oil in the oil shale industry, into a value-added glass-ceramic material via melting and sintering method. The influence of basicity (CaO/SiO2 ratio) by adding calcium oxide on the performance of glass-ceramics was studied in terms of phase transformation, mechanical properties, chemical resistances and heavy metals leaching tests. Crystallization kinetics results showed that the increase of basicity reduced the activation energies of crystallization but did not change the crystallization mechanism. When increasing the basicity from 0.2 to 0.5, the densification of sintering body was enhanced due to the promotion of viscous flow of glass powders, and therefore the compression strength and bending strength of glass-ceramics were increased. Heavy metals leaching results indicated that the produced OSFA-based glass-ceramics could be taken as non-hazardous materials. The maximum mechanical properties of compression strength of 186 ± 3 MPa, bending strength of 78 ± 6 MPa, good chemical resistances and low heavy metals leaching concentrations showed that it could be used as a substitute material for construction applications. The proposed approach will be one of the potential sustainable solutions in reducing the storage of oil shale fly ash as well as converting it into a value-added product.

  11. Effect of Crystallisation Degree on Hardness of Basaltic Glass-Ceramics

    DEFF Research Database (Denmark)

    Jensen, Martin; Smedskjær, Morten Mattrup; Yue, Yuanzheng

    The dependence of hardness of basaltic glass-ceramics on their crystallisation degree has been explored by means of differential scanning calorimetry, optical microscopy, X-ray diffraction, and Vickers indentation. Different degrees of crystallisation in the basaltic glasses have been obtained...

  12. 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

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

    Science.gov (United States)

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

    2013-11-01

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

  14. Fluorescent Lamp Glass Waste Incorporation into Clay Ceramic: A Perfect Solution

    Science.gov (United States)

    Morais, Alline Sardinha Cordeiro; Vieira, Carlos Maurício Fontes; Rodriguez, Rubén Jesus Sanchez; Monteiro, Sergio Neves; Candido, Veronica Scarpini; Ferreira, Carlos Luiz

    2016-06-01

    The mandatory use of fluorescent lamps as part of a Brazilian energy-saving program generates a huge number of spent fluorescent lamps (SFLs). After operational life, SFLs cannot be disposed as common garbage owing to mercury and lead contamination. Recycling methods separate contaminated glass tubes and promote cleaning for reuse. In this work, glass from decontaminated SFLs was incorporated into clay ceramics, not only as an environmental solution for such glass wastes and clay mining reduction but also due to technical and economical advantages. Up to 30 wt.% of incorporation, a significant improvement in fired ceramic flexural strength and a decrease in water absorption was observed. A prospective analysis showed clay ceramic incorporation as an environmentally correct and technical alternative for recycling the enormous amount of SFLs disposed of in Brazil. This could also be a solution for other world clay ceramic producers, such as US, China and some European countries.

  15. Fluorescent Lamp Glass Waste Incorporation into Clay Ceramic: A Perfect Solution

    Science.gov (United States)

    Morais, Alline Sardinha Cordeiro; Vieira, Carlos Maurício Fontes; Rodriguez, Rubén Jesus Sanchez; Monteiro, Sergio Neves; Candido, Veronica Scarpini; Ferreira, Carlos Luiz

    2016-09-01

    The mandatory use of fluorescent lamps as part of a Brazilian energy-saving program generates a huge number of spent fluorescent lamps (SFLs). After operational life, SFLs cannot be disposed as common garbage owing to mercury and lead contamination. Recycling methods separate contaminated glass tubes and promote cleaning for reuse. In this work, glass from decontaminated SFLs was incorporated into clay ceramics, not only as an environmental solution for such glass wastes and clay mining reduction but also due to technical and economical advantages. Up to 30 wt.% of incorporation, a significant improvement in fired ceramic flexural strength and a decrease in water absorption was observed. A prospective analysis showed clay ceramic incorporation as an environmentally correct and technical alternative for recycling the enormous amount of SFLs disposed of in Brazil. This could also be a solution for other world clay ceramic producers, such as US, China and some European countries.

  16. An 8-year evaluation of sintered ceramic and glass ceramic inlays processed by the Cerec CAD/CAM system

    DEFF Research Database (Denmark)

    Pallesen, U.; Dijken van, J.W.V.

    2000-01-01

    of a glass ceramic (Dicor MGC) block. The inlays were luted with a dual resin composite and evaluated clinically using modified USPHS criteria at baseline, 8 months, 2, 3, 5, 6 and 8 yr, and indirectly using models. At baseline, 84% of the inlays were estimated as optimal and 16% as acceptable. Postoperative...

  17. Photoactive transparent nano-crystalline glass-ceramic for remazole red dye degradation

    Energy Technology Data Exchange (ETDEWEB)

    Gad-Allah, Tarek A., E-mail: tareqabdelshafy@yahoo.ca [Water Pollution Research Department, National Research Centre, Cairo 12311 (Egypt); Margha, Fatma H. [Department of Glass Research, National Research Centre, Cairo 12311 (Egypt)

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Preparation and characterization of novel transparent nanocrystalline glass-ceramic. ► Precipitation of photoactive phases by using controlled heat-treatment. ► Conservation of transparency along with photoactivity. ► Using the prepared nanocrystalline glass-ceramic in water purification. -- Abstract: Transparent glass ceramic material was prepared from alkali-borosilicate glass containing titania by proper heat treatment scheme. The prepared samples were characterized using differential thermal analysis, X-ray diffraction, transmission electron microscope, selected area electron diffraction and UV–visible spectroscopy. The applied heat treatment program allowed the crystallization of nano-crystalline anatase, rutile, barium titanate, titanium borate and silicate phases while maintaining the transparency. The precipitated nano-crystalline anatase and rutile phases were responsible for the observed high photocatalytic activity of the prepared samples. Samples of 24.29 and 32.39 TiO{sub 2} wt% showed better efficiency for the decolorization of remazole red dye compared with commercial-TiO{sub 2} used in preparation of glass-ceramic. The reuse of prepared glass-ceramic photocatalyst with nearly same efficiency for different times was also proved.

  18. Study of the mechanical stability and bioactivity of Bioglass(®) based glass-ceramic scaffolds produced via powder metallurgy-inspired technology.

    Science.gov (United States)

    Boccardi, Elena; Melli, Virginia; Catignoli, Gabriele; Altomare, Lina; Jahromi, Maryam Tavafoghi; Cerruti, Marta; Lefebvre, Louis-Philippe; De Nardo, Luigi

    2016-02-02

    Large bone defects are challenging to heal, and often require an osteoconductive and stable support to help the repair of damaged tissue. Bioglass-based scaffolds are particularly promising for this purpose due to their ability to stimulate bone regeneration. However, processing technologies adopted so far do not allow for the synthesis of scaffolds with suitable mechanical properties. Also, conventional sintering processes result in glass de-vitrification, which generates concerns about bioactivity. In this work, we studied the bioactivity and the mechanical properties of Bioglass(®) based scaffolds, produced via a powder technology inspired process. The scaffolds showed compressive strengths in the range of 5-40 MPa, i.e. in the upper range of values reported so far for these materials, had tunable porosity, in the range between 55 and 77%, and pore sizes that are optimal for bone tissue regeneration (100-500 μm). We immersed the scaffolds in simulated body fluid (SBF) for 28 d and analyzed the evolution of the scaffold mechanical properties and microstructure. Even if, after sintering, partial de-vitrification occurred, immersion in SBF caused ion release and the formation of a Ca-P coating within 2 d, which reached a thickness of 10-15 μm after 28 d. This coating contained both hydroxyapatite and an amorphous background, indicating microstructural amorphization of the base material. Scaffolds retained a good compressive strength and structural integrity also after 28 d of immersion (6 MPa compressive strength). The decrease in mechanical properties was mainly related to the increase in porosity, caused by its dissolution, rather than to the amorphization process and the formation of a Ca-P coating. These results suggest that Bioglass(®) based scaffolds produced via powder metallurgy-inspired technique are excellent candidates for bone regeneration applications.

  19. Study of the mechanical stability and bioactivity of Bioglass(®) based glass-ceramic scaffolds produced via powder metallurgy-inspired technology.

    Science.gov (United States)

    Boccardi, Elena; Melli, Virginia; Catignoli, Gabriele; Altomare, Lina; Jahromi, Maryam Tavafoghi; Cerruti, Marta; Lefebvre, Louis-Philippe; De Nardo, Luigi

    2016-02-01

    Large bone defects are challenging to heal, and often require an osteoconductive and stable support to help the repair of damaged tissue. Bioglass-based scaffolds are particularly promising for this purpose due to their ability to stimulate bone regeneration. However, processing technologies adopted so far do not allow for the synthesis of scaffolds with suitable mechanical properties. Also, conventional sintering processes result in glass de-vitrification, which generates concerns about bioactivity. In this work, we studied the bioactivity and the mechanical properties of Bioglass(®) based scaffolds, produced via a powder technology inspired process. The scaffolds showed compressive strengths in the range of 5-40 MPa, i.e. in the upper range of values reported so far for these materials, had tunable porosity, in the range between 55 and 77%, and pore sizes that are optimal for bone tissue regeneration (100-500 μm). We immersed the scaffolds in simulated body fluid (SBF) for 28 d and analyzed the evolution of the scaffold mechanical properties and microstructure. Even if, after sintering, partial de-vitrification occurred, immersion in SBF caused ion release and the formation of a Ca-P coating within 2 d, which reached a thickness of 10-15 μm after 28 d. This coating contained both hydroxyapatite and an amorphous background, indicating microstructural amorphization of the base material. Scaffolds retained a good compressive strength and structural integrity also after 28 d of immersion (6 MPa compressive strength). The decrease in mechanical properties was mainly related to the increase in porosity, caused by its dissolution, rather than to the amorphization process and the formation of a Ca-P coating. These results suggest that Bioglass(®) based scaffolds produced via powder metallurgy-inspired technique are excellent candidates for bone regeneration applications. PMID:26836444

  20. UK program: glasses and ceramics for immobilization of radioactive wastes for disposal

    International Nuclear Information System (INIS)

    The UK Research Program on Radioactive Waste Management includes the development of processes for the conversion of high-level-liquid-reprocessing wastes from thermal and fast reactors to borosilicate glasses. The properties of these glasses and their behavior under storage and disposal conditions have been examined. Methods for immobilizing activity from other wastes by conversion to glass or ceramic forms are described. The UK philosophy of final solutions to waste management and disposal is presented

  1. Precipitation of ZnO in Al 2O 3-doped zinc borate glass ceramics

    Science.gov (United States)

    Masai, Hirokazu; Ueno, Takahiro; Takahashi, Yoshihiro; Fujiwara, Takumi

    2011-10-01

    Crystallization behavior of the oxide semiconductor ZnO in zinc borate glass was investigated. The precipitated crystalline phase of glass ceramics containing a small amount of Al 2O 3 was α-Zn 3B 2O 6 whereas that of the glass ceramics containing a large amount of Al 2O 3 was ZnO. It was found that the c-oriented precipitation of ZnO in a glass ceramic was brought about by the in-plane crystal growth of needle-like ZnO crystallites along the a-axis. Amount of Al 2O 3 that can make glass network affected the coordination state of B 2O 3 in the glass, and a three-coordinated BO 3 unit was preferentially formed in the glass containing a higher amount of Al 2O 3. The present results suggest that crystallization of ZnO from multi-component glass is dominated by the local coordination state of the mother glass.

  2. Glass ceramic of high hardness and fracture toughness developed from iron-rich wastes

    Institute of Scientific and Technical Information of China (English)

    Weixin HAN

    2009-01-01

    A study has been carried out on the feasibility of using high iron content wastes, gen-erated during steel making, as a raw material for the production of glass ceramic. The iron-rich wastes were mixed and melted in different proportions with soda-lime glass cullet and sand. The devitrification of the parent glasses produced from the different mixtures was investigated using differential thermal analysis, X-ray diffraction, and scanning electron microscopy. The mechanical properties of the glass-ceramic were assessed by hardness and indentation fracture toughness measurement. A glass ce-ramic with mixture of 60 wt pct iron-rich wastes, 25 wt pct sand, and 15 wt pct glass cullet exhibited the best combination of properties, namely, hardness 7.9 GPa and fracture toughness 3.75 MPa.m1/2, for the sake of containing magnetite in marked dendritic morphology. These new hard glass ceramics are candidate materials for wear resistant tiles and paving for heavy industrial floors.

  3. Thermal analyses to assess diffusion kinetics in the nano-sized interspaces between the growing crystals of a glass ceramics

    International Nuclear Information System (INIS)

    Highlights: → Macroscopic, routine laboratory methods of the 'Thermal Analysis' type (DSC, DMA) allow a rough description of the kinetics in the nano-sized interstitial spaces of glass ceramics. → These macroscopic measurements support the idea of a rigid zone around the crystals which builds up during ceramization and is part of a negative feedback loop which finally stops crystal growth and Ostwald ripening within the time window of observation. → Ostwald ripening may be provoked by thermally softening said rigid zone. Under certain conditions, this gives rise to a characteristic peak in the DSC. - Abstract: According to a hypothesis by Ruessel and coworkers, the absence of Ostwald ripening during isothermal crystallization of lithium aluminosilicate (LAS) and other glass ceramics indicates the existence of a kinetic hindrance of atomic reorganization in the interstitial spaces between the crystals. Methods of Thermal Analysis (Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA)) which are sensitive to the local atomic rearrangements in the interstitial spaces (including viscous flow) are applied to find support for the idea of kinetic hindrance and the formation of a core shell structure acting as diffusion barrier. Both the DSC-measured calorimetric glass transition and the DMA-measured viscoelastic properties indicate an increase in the time constants of atomic rearrangements and diffusion by at least two orders of magnitude during ceramization. This fits to the above idea. Based on these findings, thermo analytic studies have been performed in order to find out how Ostwald ripening may be provoked.

  4. 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.

  5. Glass ceramic foams from coal ash and waste glass: production and characterisation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, J.P.; Boccaccini, A.R.; Lee, P.D.; Kershaw, M.J.; Rawlings, R.D. [University of London at Imperial College of Science Technology & Medicine, London (United Kingdom)

    2006-02-01

    Lightweight glass ceramic foams have been produced from a mixture of silicate wastes, namely 20 wt-% coal pond ash and 80 wt-% bottle glass cullet. A powder sintering route with the incorporation of 2 wt-% SiC as foaming agent was used. The pore morphology achieved under different sintering conditions was investigated in detail using X-ray microtomography. The apparent density of the foams ranged from 0.2 to 0{center_dot}4 g cm{sup -3}, and the porosity ranged from 70 to 90%. Other variables, such as pore wall thickness, pore size and roundness, all behaved consistently with sintering temperature. The optimum sintering temperature was found to be in the range 1000-1050{sup o}C, at which porosity was about 75% and was the most uniform. Foams produced under this condition exhibit satisfactory compressive strength of about 1.5 MPa and show relatively high thermal shock resistance, with compressive strength gradually decreasing as quenching temperature increases.

  6. 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.

  7. Deposition, characterization, and tribological applications of near-frictionless carbon films on glass and ceramic substrates

    International Nuclear Information System (INIS)

    As an element, carbon is rather unique and offers a range of rare opportunities for the design and fabrication of zero-, one-, two-, and three-dimensional nanostructured novel materials and coatings such as fullerenes, nanotubes, thin films, and free-standing nano-to-macroscale structures. Among these, carbon-based two-dimensional thin films (such as diamond and diamond-like carbon (DLC)) have attracted an overwhelming interest in recent years, mainly because of their exceptional physical, chemical, mechanical, electrical, and tribological properties. In particular, certain DLC films were found to provide extremely low friction and wear coefficients to sliding metallic and ceramic surfaces. Since the early 1990s, carbon has been used at Argonne National Laboratory to synthesize a class of novel DLC films that now provide friction and wear coefficients as low as 0.001 and 10-11-10-10 mm3 N-1 m-1, respectively, when tested in inert or vacuum test environments. Over the years, we have optimized these films and applied them successfully to all kinds of metallic and ceramic substrates and evaluated their friction and wear properties under a wide range of sliding conditions. In this paper, we will provide details of our recent work on the deposition, characterization, and tribological applications of near-frictionless carbon films on glass and ceramic substrates. We will also provide chemical and structural information about these films and describe the fundamental tribological mechanisms that control their unusual friction and wear behaviour

  8. BAS系微晶玻璃抗氧化涂层的制备与性能%Preparation and properties of BAS glass-ceramics based anti-oxidation coatings

    Institute of Scientific and Technical Information of China (English)

    芦玉峰; 周萌; 范成洲; 郑晓慧; 吴剑锋; 堵永国; 肖加余

    2011-01-01

    利用2层不同软化温度和不同热膨胀系数的BaO-A12O3-SiO2(BAS)系微晶玻璃,采用浆料涂覆浸渍-多层共烧的方法制备了2种双层同组分和1种双层不同组分的Cf/SiC复合材料抗氧化涂层.3种结构的BAS系微晶玻璃涂层完整、无明显缺陷,涂层与Cf/SiC复合材料的结合状态良好,有助于提高Cf/SiC复合材料的抗氧化性能.双层不同组分的BAS系微晶玻璃涂层在1200~1350℃范围内对提高Cf/SiC复合材料抗氧化性能的作用显著,失重速率和失重量均明显减小.与未包覆涂层的复合材料相比,包覆双层不同组分涂层的复合材料经历600次(每次保温10 min)热冲击后的失重降低了1/2~2/3,保留的强度提高了7~15倍.%Two kinds of BaO-A12O3-SiO2 (BAS) glass-ceramics with different soften points and thermal expansion coefficients were employed to prepare three kinds of gradient coatings for carbon fiber reinforced silicon carbide(Cf/SiC) composite. These coatings were fabricated with slurry deposition combined dipping method and multi-co-firing technology. These BAS glass-ceramics based coatings were integrated and defect-free. The coatings and the composites bind tightly, which can improve the anti-oxidation performance of the coated Cf/SiC composite.All coating systems can protect Cf/SiC composite from oxidation. The graded coatings protect Cf/SiC composite markedly, and the mass loss rate and mass loss of coated composites are reduced greatly within 1200~ 1350 ℃.Compared with uncoated composite, the mass loss of the coated composite is reduced by 1/2~2/3, and the reminant bending strength is enhanced 7~15 times after 600 thermal shock cycles in the experimental range.

  9. Glass-Ceramic Waste Forms for Uranium and Plutonium Residues Wastes - 13164

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Martin W.A.; Moricca, Sam A.; Zhang, Yingjie; Day, R. Arthur; Begg, Bruce D. [Australian Nuclear Science and Technology Organisation (ANSTO), New Illawarra Road, Lucas Heights, NSW 2234 (Australia); Scales, Charlie R.; Maddrell, Ewan R. [National Nuclear Laboratory, Sellafield, Seascale, Cumbria, UK, CA20 1PG (United Kingdom); Hobbs, Jeff [Sellafield Limited, Sellafield, Seascale, Cumbria, UK, CA20 1PG (United Kingdom)

    2013-07-01

    A program of work has been undertaken to treat plutonium-residues wastes at Sellafield. These have arisen from past fuel development work and are highly variable in both physical and chemical composition. The principal radiological elements present are U and Pu, with small amounts of Th. The waste packages contain Pu in amounts that are too low to be economically recycled as fuel and too high to be disposed of as lower level Pu contaminated material. NNL and ANSTO have developed full-ceramic and glass-ceramic waste forms in which hot-isostatic pressing is used as the consolidation step to safely immobilize the waste into a form suitable for long-term disposition. We discuss development work on the glass-ceramic developed for impure waste streams, in particular the effect of variations in the waste feed chemistry glass-ceramic. The waste chemistry was categorized into actinides, impurity cations, glass formers and anions. Variations of the relative amounts of these on the properties and chemistry of the waste form were investigated and the waste form was found to be largely unaffected by these changes. This work mainly discusses the initial trials with Th and U. Later trials with larger variations and work with Pu-doped samples further confirmed the flexibility of the glass-ceramic. (authors)

  10. Influence of glass additives on the microwave dielectric properties of Ca5Nb2TiO12 ceramics

    International Nuclear Information System (INIS)

    Investigation was made to correlate the effect of composition and concentration of glass content on the sintering temperature and microwave dielectric properties of polycrystalline Ca5Nb2TiO12 ceramics. Glass systems, such as B2O3, SiO2, B2O3-SiO2, ZnO-B2O3, Al2O3-SiO2, Al2O3-B2O3-SiO2, BaO-B2O3-SiO2, MgO-B2O3-SiO2, ZnO-B2O3-SiO2, PbO-B2O3-SiO2, and 2MgO-Al2O3-5SiO2 were added to calcined Ca5Nb2TiO12 powder in different weight percentages. The structure and microstructure of the sintered ceramics were studied using powder X-ray diffraction and scanning electron microscopic methods. The specimens were characterized in the microwave frequency range (3-6 GHz). The study revealed that alumina and silica based glasses were more effective in improving the dielectric properties of Ca5Nb2TiO12 ceramics, whereas borate glasses are more suited for lowering the sintering temperature

  11. The effect of colouring agent on the physical properties of glass ceramic produced from waste glass for antimicrobial coating deposition

    Science.gov (United States)

    Juoi, J. M.; Ayoob, N. F.; Rosli, Z. M.; Rosli, N. R.; Husain, K.

    2016-07-01

    Domestic waste glass is utilized as raw material for the production of glass ceramic material (GCM) via sinter crystallisation route. The glass ceramic material in a form of tiles is to be utilized for the deposition of Ag-TiO2 antimicrobial coating. Two types of soda lime glass (SLG) that are non-coloured and green SLG are utilised as main raw materials during the batch formulation in order to study the effect of colouring agent (Fe2O3) on the physical and mechanical properties of glass ceramic produced. Glass powder were prepared by crushing bottles using hammer milled with milling machine and sieved until they passed through 75 µm sieve. The process continues by mixing glass powder with ball clay with ratio of 95:5 wt. %, 90:10 wt. % and 85:15 wt. %. Each batch mixture was then uniaxial pressed and sintered at 800°C, 825 °C and 850 °C. The physical and mechanical properties were then determined and compared between those produced from non-coloured and green coloured SLG in order to evaluate the effect of colouring agent (Fe2O3) on the GCM produced. The optimum properties of non-coloured SLG is produced with smaller ball clay content (10 wt. %) compared to green SLG (15 wt. %). The physical properties (determined thru ASTM C373) of the optimized GCM produced from non-coloured SLG and green SLG are 0.69 % of porosity, 1.92 g/cm3 of bulk density, 0.36 % of water absorption; and 1.96 % of porosity, 2.69 g/cm3 of bulk density, 0.73 % of water absorption; respectively. Results also indicate that the most suitable temperature in producing GCM from both glasses with optimized physical and mechanical properties is at 850 °C.

  12. Rigid bonded glass ceramic seals for high temperature membrane reactors and solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Paulsen, Ove

    2009-05-15

    Solid Oxide Fuel cells (SOFC) and dense gas separation membranes based on mixed ionic and electronic conductors have gained increased interest the resent years due the search for new technologies for clean energy generation. These technologies can be utilized to produce electricity from fossil fuel with low CO{sub 2} emission compared to conventional gas or coal based energy plants. One crucial challenge with high temperature membrane reactors and SOFCs is the sealing of the active membranes/electrolytes to prevent leakage of air to fuel side or vice versa. Due to the high operating temperatures of typical 800-1000 degrees Celsius the selection of reliable sealing materials is limited. The seals have to remain gas tight during the life time of the reactor/SOFC, they need to be chemical compatible with the sealed materials and stable in reducing and oxidizing atmospheres containing water vapour and CO{sub 2}, and finally they should be cheap, readily available and easy to process. The main purpose of the present work was to evaluate rigid bonded glass ceramic seals for dense oxygen ion and proton conducting membranes and electrolytes for SOFCs and high temperature (HT) membrane reactors. First, a review of sealing technologies has been carried out with emphasis on SOFC and ceramic membranes technologies applicable for zero emission power plants. Regarding sealing, the best and cheapest materials at the present time are based on silicate glass and glass ceramics. In the present work aluminate glass without silica is introduced as a new class of seals expanding the material selection for HT membrane sealing technologies. The main reason for studying silica free systems is that silica is known to be unstable in humid atmospheres and/or reducing conditions at elevated temperatures. Two glass systems have been evaluated. The first was based on aluminate glasses in the system RO-CaO-Al{sub 2}O{sub 3} (R=Mg, Ba, Sr) with special focus on the CaO-MgO-Al{sub 2}O{sub 3

  13. Glass-ceramic joining and coating of SiC/SiC for fusion applications

    International Nuclear Information System (INIS)

    The aim of this work is the joining and the coating of SiC/SiC composites by a simple, pressureless, low cost technique. A calcia-alumina glass-ceramic was chosen as joining and coating material, because its thermal and thermomechanical properties can be tailored by changing the composition, it does not contain boron oxide (incompatible with fusion applications) and it has high characteristic temperatures (softening point at about 1400 C). Furthermore, the absence of silica makes this glass-ceramic compatible with ceramic breeder materials (i.e. lithium-silicates, -alluminates or -zirconates). Coatings and joints were successfully obtained with Hi-Nicalon fiber-reinforced CVI silicon carbide matrix composite. Mechanical shear strength tests were performed on joined samples and the compatibility with a ceramic breeder material was examined. (orig.)

  14. Nd3+,Yb3+ and Ho3+ Codoped Oxyfluoride Glass Ceramics with High Efficient Green Upconversion Luminescence

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun-Jie; KAWAMOTO Yoji; DAI Shi-Xun; ZHANG Li-Yan; HU Li-Li

    2004-01-01

    @@ New oxyfluoride glasses and glass ceramic codoped with Nd3+, Yb3+ and Ho3+ were prepared. The x-ray diffraction analysis revealed that the heat treatments of the oxyfluoride glasses could cause the precipitation of (Nd3+, Yb3+, Ho3+)-doped fluorite-type crystals. Very strong green up-conversion luminescence due to the Ho3+: (5F4, 5S2) → 5I8 transition under 800-nm excitation was observed in these transparent glass ceramics.The intensity of the green up-conversion luminescence in a 1-mo1% YbF3-containing glass ceramic was found to be about 120 times stronger than that in the precursor oxyfluoride glass. The reason for the highly efficient Ho3+up-conversion luminescence in the oxyfluoride glass ceramics is discussed.

  15. Cold Crucible Induction Melter Studies for Making Glass Ceramic Waste Forms. A Feasibility Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Crum, Jarrod V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Maio, Vincent [Idaho National Lab. (INL), Idaho Falls, ID (United States); McCloy, John S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Scott, Clark [Idaho National Lab. (INL), Idaho Falls, ID (United States); Riley, Brian J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Benefiel, Bradley [Idaho National Lab. (INL), Idaho Falls, ID (United States); Vienna, John D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Archibald, Kip [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rodriguez, Carmen P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rutledge, Veronica [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zhu, Zihua [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ryan, Joseph V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Olszta, Matthew J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-10-23

    Glass ceramics are being developed to immobilize fission products, separated from used nuclear fuel by aqueous reprocessing, into a stable waste form suitable for disposal in a geological repository. This work documents the glass ceramic formulation at bench scale and for a scaled melter test performed in a pilot-scale (~1/4 scale) cold crucible induction meter (CCIM). Melt viscosity, electrical conductivity, and crystallization behavior upon cooling were measured on a small set of compositions to select a formulation for melter testing. Property measurements also identified a temperature range for melter operation and cooling profiles necessary to crystallize the targeted phases in the waste form. Bench scale and melter run results successfully demonstrate the processability of the glass ceramic using the CCIM melter technology.

  16. Cold crucible induction melter studies for making glass ceramic waste forms: A feasibility assessment

    Science.gov (United States)

    Crum, Jarrod; Maio, Vince; McCloy, John; Scott, Clark; Riley, Brian; Benefiel, Brad; Vienna, John; Archibald, Kip; Rodriguez, Carmen; Rutledge, Veronica; Zhu, Zihua; Ryan, Joe; Olszta, Matthew

    2014-01-01

    Glass ceramics are being developed to immobilize fission products, separated from used nuclear fuel by aqueous reprocessing, into a stable waste form suitable for disposal in a geological repository. This work documents the glass ceramic formulation at bench scale and for a scaled melter test performed in a pilot-scale (∼1/4 scale) cold crucible induction melter (CCIM). Melt viscosity, electrical conductivity, and crystallization behavior upon cooling were measured on a small set of compositions to select a formulation for melter testing. Property measurements also identified a temperature range for melter operation and cooling profiles necessary to crystallize the targeted phases in the waste form. Bench scale and melter run results successfully demonstrate the processability of the glass ceramic using the CCIM melter technology.

  17. Cold crucible induction melter studies for making glass ceramic waste forms: A feasibility assessment

    Energy Technology Data Exchange (ETDEWEB)

    Crum, Jarrod, E-mail: jarrod.crum@pnnl.gov [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA (United States); Maio, Vince [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID (United States); McCloy, John [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA (United States); Scott, Clark [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID (United States); Riley, Brian [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA (United States); Benefiel, Brad [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID (United States); Vienna, John [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA (United States); Archibald, Kip [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID (United States); Rodriguez, Carmen [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA (United States); Rutledge, Veronica [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID (United States); Zhu, Zihua; Ryan, Joe; Olszta, Matthew [Pacific Northwest National Laboratory, P.O. Box 999, Richland, WA (United States)

    2014-01-15

    Glass ceramics are being developed to immobilize fission products, separated from used nuclear fuel by aqueous reprocessing, into a stable waste form suitable for disposal in a geological repository. This work documents the glass ceramic formulation at bench scale and for a scaled melter test performed in a pilot-scale (∼1/4 scale) cold crucible induction melter (CCIM). Melt viscosity, electrical conductivity, and crystallization behavior upon cooling were measured on a small set of compositions to select a formulation for melter testing. Property measurements also identified a temperature range for melter operation and cooling profiles necessary to crystallize the targeted phases in the waste form. Bench scale and melter run results successfully demonstrate the processability of the glass ceramic using the CCIM melter technology.

  18. Cold crucible induction melter studies for making glass ceramic waste forms: A feasibility assessment

    Energy Technology Data Exchange (ETDEWEB)

    Crum, Jarrod [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Maio, Vince [Idaho National Laboratory (INL), Idaho Falls, ID (United States); McCloy, John [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Scott, Clark [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Riley, Brian [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Benefiel, Brad [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Vienna, John [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Archibald, Kip [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Rodriguez, Carmen [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Rutledge, Veronica [Idaho National Laboratory (INL), Idaho Falls, ID (United States); Zhu, Zihua [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Ryan, Joe [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Olszta, Matthew [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

    2014-01-01

    Glass ceramics are being developed to immobilize fission products, separated from used nuclear fuel by aqueous reprocessing, into a stable waste form suitable for disposal in a geological repository. This work documents the glass ceramic formulation at bench scale and for a scaled melter test performed in a pilot-scale (approximately 1/4 scale) cold crucible induction melter (CCIM). Melt viscosity, electrical conductivity, and crystallization behavior upon cooling were measured on a small set of compositions to select a formulation for melter testing. Property measurements also identified a temperature range for melter operation and cooling profiles necessary to crystallize the targeted phases in the waste form. Bench scale and melter run results successfully demonstrate the processability of the glass ceramic using the CCIM melter technology.

  19. Broadband Infrared Luminescence of Ni2+ in Petalite-Type Transparent Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    FENG Gao-Reng; ZHOU Shi-Feng; ZHANG Song-Min; YANG Hu-Cheng; QIU Jian-Rong

    2007-01-01

    Transparent Ni2+-doped magnesium aluminosilicate glass ceramics are prepared.The formation of petalite-type crystallites in the glass ceramics is confirmed by x-ray diffraction.Broadband infrared luminescence centred at around 1235 nm with full width at half maximum (FWHM) of about 300 nm is observed from the Ni2+-doped glass ceramics.The observed infrared emission could be attributed to the 3T2(F)→3A2(F)transition of octahedral Ni2+ ions in petalite-type crystallites.The product of the fluorescence lifetime and the stimulated emission cross sections is 1.2×10-24 cm2s.

  20. Cold crucible induction melter studies for making glass ceramic waste forms: A feasibility assessment

    International Nuclear Information System (INIS)

    Glass ceramics are being developed to immobilize fission products, separated from used nuclear fuel by aqueous reprocessing, into a stable waste form suitable for disposal in a geological repository. This work documents the glass ceramic formulation at bench scale and for a scaled melter test performed in a pilot-scale (approximately 1/4 scale) cold crucible induction melter (CCIM). Melt viscosity, electrical conductivity, and crystallization behavior upon cooling were measured on a small set of compositions to select a formulation for melter testing. Property measurements also identified a temperature range for melter operation and cooling profiles necessary to crystallize the targeted phases in the waste form. Bench scale and melter run results successfully demonstrate the processability of the glass ceramic using the CCIM melter technology

  1. Cold crucible induction melter studies for making glass ceramic waste forms: A feasibility assessment

    International Nuclear Information System (INIS)

    Glass ceramics are being developed to immobilize fission products, separated from used nuclear fuel by aqueous reprocessing, into a stable waste form suitable for disposal in a geological repository. This work documents the glass ceramic formulation at bench scale and for a scaled melter test performed in a pilot-scale (∼1/4 scale) cold crucible induction melter (CCIM). Melt viscosity, electrical conductivity, and crystallization behavior upon cooling were measured on a small set of compositions to select a formulation for melter testing. Property measurements also identified a temperature range for melter operation and cooling profiles necessary to crystallize the targeted phases in the waste form. Bench scale and melter run results successfully demonstrate the processability of the glass ceramic using the CCIM melter technology

  2. Glass and glass–ceramic coatings, versatile materials for industrial and engineering applications

    Indian Academy of Sciences (India)

    Amitava Majumdar; Sunirmal Jana

    2001-02-01

    Among various coating systems for industrial and engineering applications, glass and glass–ceramic coatings have advantages of chemical inertness, high temperature stability and superior mechanical properties such as abrasion, impact etc as compared to other coating materials applied by thermal spraying in its different forms viz. PVD, CVD, plasma, etc. Besides imparting required functional properties such as heat, abrasion and corrosion resistance to suit particular end use requirements, the glass and glass–ceramic coatings in general also provide good adherence, defect free surface and refractoriness. Systematic studies covering the basic science of glass and glass–ceramic coatings, the functional properties required for a particular end-use along with the various fields of application have been reviewed in this paper.

  3. Novel cordierite nanopowders of new crystallization aspects and its cordierite-based glass ceramics of improved mechanical and electrical properties for optimal use in multidisciplinary scopes

    Energy Technology Data Exchange (ETDEWEB)

    Sanad, M.M.S., E-mail: mustafa_sanad2002@yahoo.com [Central Metallurgical R & D Institute, P.O. Box 87, Helwan, Cairo (Egypt); Particle Engineering Research Center, University of Florida, Gainesville, FL 32611 (United States); Rashad, M.M.; Abdel-Aal, E.A. [Central Metallurgical R & D Institute, P.O. Box 87, Helwan, Cairo (Egypt); Powers, K. [Particle Engineering Research Center, University of Florida, Gainesville, FL 32611 (United States)

    2015-07-15

    Nanocrystalline α-cordierite Mg{sub 2}Al{sub 4}Si{sub 5}O{sub 18} powders have been synthesized via a novel and facile co-precipitation method using MgCl{sub 2}.6H{sub 2}O, NaAlO{sub 2}, Na{sub 2}SiO{sub 3}.5H{sub 2}O as starting materials. XRD, SEM, HR-TEM and EDS techniques were employed to investigate the phase structure and crystal morphology of the synthesized powders at various annealing temperatures. The kinetics of cordierite crystallization was studied under non-isothermal conditions using Differential Thermal Analysis (DTA). The apparent activation energy (E{sub a}) of μ-cordierite crystallization, calculated by modified Kissinger model was equal 286.1 K J mol{sup −1} and comparable with the literature. The dielectric measurements revealed that the cordierite ceramic samples sintered at 1300 and 1350 °C could be successfully applied for electronic packaging under the microwave and radiowave frequency regions, respectively. - Highlights: • Novel α-cordierite nanoparticles (13.3–46.7 nm) prepared by co-precipitation route. • The mechanism of μ-cordierite crystallization obeys the surface chemical kinetics. • Phase transformation of μ-to α-cordierite greatly affects densification properties. • The cordierite ceramics show good dielectric performance under GHz or MHz ranges.

  4. 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.

  5. Wide colour gamut generated in triply lanthanide doped sol-gel nano-glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, J. del, E-mail: fjvargas@ull.e [Universidad de La Laguna, Dpto. Fisica Basica (Spain); Mendez-Ramos, J. [Universidad de La Laguna, Dpto. Fisica Fundamental y Experimental, Electronica y Sistemas (Spain); Yanes, A. C. [Universidad de La Laguna, Dpto. Fisica Basica (Spain); Rodriguez, V. D. [Universidad de La Laguna, Dpto. Fisica Fundamental y Experimental, Electronica y Sistemas (Spain)

    2009-05-15

    The generation of a wide colour gamut, based on up-conversion of cheap near-infrared photons into the visible range, is of great importance for general lighting appliances and integrated optical devices. Here, we report for the first time on up-conversion luminescence under infrared excitation at 980 nm in Yb{sup 3+}-Er{sup 3+}-Tm{sup 3+} triply doped sol-gel derived SiO{sub 2}-LaF{sub 3} based nano-glass-ceramics (SOL-YET), containing LaF{sub 3} nanocrystals with a size about 13 nm. Efficient simultaneous up-conversion emission of the three primary colours (blue, green and red) gives rise to a balanced white overall emission. The ratio between up-conversion emission bands can be varied by changing pump power intensity resulting in colour tuneable up-conversion phosphor.

  6. Synthesis and optical properties of transparent glass ceramics with Eu,Yb:PbF2 nanocrystals

    Science.gov (United States)

    Loiko, P. A.; Rachkovskaya, G. E.; Zakharevich, G. B.; Yumashev, K. V.

    2015-02-01

    Transparent oxyfluoride glass ceramics containing Eu,Yb:PbF2 nanocrystals (average diameter 6.5 nm) is synthesized by secondary heat treatment of the initial SiO2-PbO-PbF2-CdF2 glass doped with YbF3 (1 mol %) and Eu2O3 (1 mol %); the optical absorption and the upconversion luminescence of this ceramics are studied. Intense orange luminescence (the CIE color coordinates are x = 0.602, y = 0.398) is obtained under excitation by a laser diode at a wavelength of 960 nm.

  7. Optical absorption and luminescence study of cobalt-doped magnesium aluminosilicate glass ceramics

    Science.gov (United States)

    Malyarevich, A. M.; Denisov, I. A.; Yumashev, K. V.; Dymshits, O. S.; Zhilin, A. A.

    2002-08-01

    Linear and nonlinear optical properties of cobalt-doped magnesium aluminosilicate transparent glass ceramics that were prepared under different conditions have been studied. It has been shown that absorption and luminescence spectra and absorption bleaching of these glass ceramics are defined mainly by tetrahedrally coordinated Co 2+ ions located in magnesium aluminum spinel nanocrystals. The lifetimes of the 4 T 1 ( 4 F) and 4 T 2 ( 4 F) excited states of the tetrahedral Co 2+ ions were found to be in the ranges 2540 and 120450 ns, respectively, depending on the Co concentration. 2002 Optical Society of America

  8. Ultraviolet to visible frequency-conversion properties of rare earths doped glass ceramics

    Institute of Scientific and Technical Information of China (English)

    Y. Hatefi; N. Shahtahmasebi; A. Moghimi; E. Attaran

    2011-01-01

    Nd3+, Eu3+ and Tb3+ ions doped transparent chlorophosphate glass ceramics were prepared and their fiequency-conversion properties were studied. X-ray diffraction (XRD) patterns evidenced the formation of expected halide nanocrystals. The absorption, excitation and emission spectra investigation indicated that some of rare earth (RE) ions were trapped in low phonon energy halide nanocrystals, and therefore an efficient down frequency-conversion was observed. The comparative spectroscopic studies of RE doped samples suggested that the glass ceramics systems are potentially applicable as efficient ultraviolet to visible frequency-conversion photonics materials.

  9. Intense Green Upconversion Luminescence in Er3+:Yb3+ Codoped Fluorophosphate Glass Ceramic Containing SrTe5O11 Nanocrystals

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-Yan; XU Shi-Qing; HU Li-Li

    2007-01-01

    Er3+ :Yb3+ codoped tellurite-fluorophosphate (TFP) glass ceramic exhibits much stronger upconversion luminescence. The intensity of the 540nm green light and 651 nm red light of the TFP glass ceramic is 120 times and 44 times stronger than that of the fluorophospahte (FP) glass, respectively. XRD analysis shows that the nanocrystal in TFP glass ceramic is SrTesO11. TFP glass ceramic alsc displays much higher upconversion fluorescence lifetime and crystallization stability. The narrow and strong peak at 540 nm is very ideal for practical upconversion luminescence realization. This work is a new trial for exploring non-PbF2 involved nanocrystal upconversion glass ceramics.

  10. Fabrication of porous ceramic via recycling of glass with paper fiber as sacrificial fugitive

    Science.gov (United States)

    Badarulzaman, N. A.; Hamidon, A.; Nor, M. A. A. M.

    2015-05-01

    Recycled glass powder was added with ball clay and feldspar using ratio 90:5:5. The blend were mixed into different amount of paper fiber and cast into porous ceramic. Samples prepared with different compositions (2, 4, 6, 8, and 10 wt % of paper fiber) were heat treated at constant temperature (750 °C) for an hour. Samples with high percentage of paper fiber gave the largest pore size in the ceramic body, meanwhile lower percentage of paper fiber produced ceramic body with smaller pore size.

  11. 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).

  12. Luminescence study of mixed valence Eu-doped nanocrystalline glass-ceramics

    Science.gov (United States)

    Bagga, Ruchika; Achanta, Venu Gopal; Goel, Ashutosh; Ferreira, José M. F.; Singh, Narinder Pal; Singh, Davinder Paul; Contini, Vittoria; Falconieri, Mauro; Sharma, Gopi

    2013-12-01

    Eu-doped nanocrystalline NaAlSiO4/NaY9Si6O26 glass-ceramics have been prepared by controlled crystallization of melt quenched bulk glasses. XRD, SEM and FTIR spectroscopy techniques were employed to characterize the crystallization process and the structural properties of the precursor glass and corresponding glass-ceramics. The formation of divalent europium (Eu2+) from Eu3+ ions during high temperature synthesis under ambient atmosphere was analyzed by photoluminescence spectroscopy and is discussed using the optical basicity model. The observed luminescence properties of Eu: NaY9Si6O26 are compared with that of Eu: β-PbF2 nanocrystals and their marked differences are discussed.

  13. Fibre-matrix bond strength studies of glass, ceramic, and metal matrix composites

    Science.gov (United States)

    Grande, D. H.; Mandell, J. F.; Hong, K. C. C.

    1988-01-01

    An indentation test technique for compressively loading the ends of individual fibers to produce debonding has been applied to metal, glass, and glass-ceramic matrix composites; bond strength values at debond initiation are calculated using a finite-element model. Results are correlated with composite longitudinal and interlaminar shear behavior for carbon and Nicalon fiber-reinforced glasses and glass-ceramics including the effects of matrix modifications, processing conditions, and high-temperature oxidation embrittlement. The data indicate that significant bonding to improve off-axis and shear properties can be tolerated before the longitudinal behavior becomes brittle. Residual stress and other mechanical bonding effects are important, but improved analyses and multiaxial interfacial failure criteria are needed to adequately interpret bond strength data in terms of composite performance.

  14. Medical imaging scintillators from glass-ceramics using mixed rare-earth halides

    Science.gov (United States)

    Beckert, M. Brooke; Gallego, Sabrina; Ding, Yong; Elder, Eric; Nadler, Jason H.

    2016-10-01

    Recent years have seen greater interest in developing new luminescent materials to replace scintillator panels currently used in medical X-ray imaging systems. The primary areas targeted for improvement are cost and image resolution. Cost reduction is somewhat straightforward in that less expensive raw materials and processing methods will yield a less expensive product. The path to improving image resolution is more complex because it depends on several properties of the scintillator material including density, transparency, and composition, among others. The present study focused on improving image resolution using composite materials, known as glass-ceramics that contain nanoscale scintillating crystallites formed within a transparent host glass matrix. The small size of the particles and in-situ precipitation from the host glass are key to maintaining transparency of the composite scintillator, which ensures that a majority of the light produced from absorbed X-rays can actually be used to create an image of the patient. Because light output is the dominating property that determines the image resolution achievable with a given scintillator, it was used as the primary metric to evaluate performance of the glass-ceramics relative to current scintillators. Several glass compositions were formulated and then heat treated in a step known as "ceramization" to grow the scintillating nanocrystals, whose light output was measured in response to a 65 kV X-ray source. Performance was found to depend heavily on the thermal history of the glass and glass-ceramic, and so additional studies are required to more precisely determine optimal process temperatures. Of the compositions investigated, an alumino-borosilicate host glass containing 56mol% scintillating rare-earth halides (BaF2, GdF3, GdBr3, TbF3) produced the highest recorded light output at nearly 80% of the value recorded using a commercially-available GOS:Tb panel as a reference.

  15. Nucleation and crystallization of Ca doped basaltic glass for the production of a glass-ceramic material

    Science.gov (United States)

    Tarrago, Mariona; Royo, Irene; Garcia-Valles, Maite; Martínez, Salvador

    2016-04-01

    Sewage sludge from wastewater treatment plants is a waste with a composition roughly similar to that of a basalt. It may contain potentially toxic elements that can be inertized by vitrification. Using a glass-ceramic process, these elements will be emplaced in newly formed mineral phases. Glass-ceramic production requires an accurate knowledge of the temperatures of nucleation (TN) and crystal growth of the corresponding minerals. This work arises from the study of the addition of ions to a basaltic matrix in order to establish a model of vitrification of sewage sludge. In this case a glass-ceramic is obtained from a glass made with a basalt that has been doped with 16% CaO. Two glasses which underwent different cooling processes have been produced and compared. The first was annealed at 650oC (AG) and the second was quenched (QG). The chemical composition of the glasses is SiO2 36.11 wt%, Al2O312.19 wt%, CaO 24.44 wt%, FeO 10.06 wt%, MgO 9.19 wt%, Na2O 2.28 wt%, TiO2 2.02 wt%, K2O 1.12 wt%, P2O5 0.46 wt%. Glass transition temperature obtained by dilatometry varies from 640 oC (AG) to 700 oC (QG). The temperatures of nucleation and crystal growth of the glass have been determined by Differential Thermal Analysis (DTA). The phases formed after these treatments were identified by X-Ray Diffraction. The temperatures of exothermic and endothermic peaks measured in the quenched glass are, in average, 10 oC higher than those found for the annealed glass. The exothermic peaks provide crystallization temperatures for different phases: a first event at 857 oC corresponds to the growth of magnetite, pyroxene and nepheline, whereas a second event at 1030 oC is due to the crystallization of melilite from the reaction between previous minerals and a remaining amorphous phase. The complete melting of this system occurs at 1201 oC. This glass has been nucleated inside the DTA furnace (500-850° C/3 hours) and then heated up to 1300 oC using the fraction between 400-500μm. TN

  16. Experimental Study of the Aging and Self-Healing of Glass/Ceramic Sealant Used in SOFCs

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenning N.; Sun, Xin; Koeppel, Brian J.; Khaleel, Mohammad A.

    2010-01-01

    High operating temperatures of solid oxide fuel cells (SOFCs) require that sealant must function at a high temperature between 600oC and 900oC and in the oxidizing and reducing environments of fuel and air. This paper describes tests to investigate the temporal evolution of the volume fraction of ceramic phases, the evolution of micro-damage, and the self-healing behavior of the glass ceramic sealant used in SOFCs. It was found that after the initial sintering process, further crystallization of the glass ceramic sealant does not stop, but slows down and reduces the residual glass content while boosting the ceramic crystalline content. Under the long-term operating environment, distinct fibrous and needle-like crystals in the amorphous phase disappeared, and smeared/diffused phase boundaries between the glass phase and ceramic phase were observed. Meanwhile, the micro-damage was induced by the cooling-down process from the operating temperature to the room temperature, which can potentially degrade the mechanical properties of the glass/ceramic sealant. The glass/ceramic sealant self-healed upon reheating to the SOFC operating temperature, which can restore the mechanical performance of the glass/ceramic sealant.

  17. Photoluminescence of Eu3+, Tb3+ and Tm3+-doped transparent SiO2-Al2O3-LiF-GdF3 glass ceramics

    International Nuclear Information System (INIS)

    In this paper, we present the photoluminescence properties of Eu3+, Tb3+ and Tm3+-doped oxyfluoride alumino-silicate glasses and glass ceramics. The X-ray diffraction (XRD) and differential thermal analysis (DTA) profiles of these glasses have been carried out, to confirm their structure and thermal stability. Compared to Eu3+, Tb3+ and Tm3+-doped glasses, their respective glass ceramics have shown stronger emissions due to the presence of LiGdF4 crystalline phase. For Eu3+-doped glass and glass ceramics, five emission bands centered at 578 nm (5D0 → 7F0), 592 nm (5D0 → 7F1), 614 nm (5D0 → 7F2), 652 nm (5D0 → 7F3) and 698 nm (5D0 → 7F4) have been observed with 394 nm (5D0 → 7L6) excitation wavelength. Of them, 614 nm (5D0 → 7F2) has shown bright reddish-orange emission. With regard to the Tb3+-doped glass and glass ceramic, four emission bands centered at 491 nm (5D4 → 7F6), 545 nm (5D4 → 7F5), 587 nm (5D4 → 7F4) and 622 nm (5D4 → 7F3) have been observed with an excitation at 377 nm (3F6 → 5G6) wavelength. Of them, 545 nm (5D4 → 7F5) has shown bright green emission. Emission bands of 1G4 → 3F4 (650 nm) and 3F3 → 3H6 (708 nm) transitions for the Tm3+:glass and glass ceramic, with an excitation at 3H6 → 1G4 (469 nm) have been observed. The stimulated emission cross-sections of all the emission bands of Eu3+, Tb3+ and Tm3+:glasses and glass ceramics have been computed based on their measured full-width at half maximum (FWHM, Δλ) and lifetimes (τm).

  18. Continuing the Validation of CCIM Processability for Glass Ceramic HLLW Forms: Plan for Test AFY14CCIM-GC1

    Energy Technology Data Exchange (ETDEWEB)

    Vince Maio

    2014-04-01

    This test plan covers test AFY14CCIM-GC1which is the first of two scheduled FY-2014 test runs involving glass ceramic waste forms in the Idaho National Laboratory’s Cold Crucible Induction Melter Pilot Plant. The test plan is based on the successes and challenges of previous tests performed in FY-2012 and FY-2013. The purpose of this test is to continue to collect data for validating the glass ceramic High Level Liquid Waste form processability advantages using Cold Crucible Induction Melter technology. The major objective of AFYCCIM-GC1 is to complete additional proposed crucible pouring and post tapping controlled cooling experiments not completed during previous tests due to crucible drain failure. This is necessary to qualify that no heat treatments in standard waste disposal canisters are necessary for the operational scale production of glass ceramic waste forms. Other objectives include the production and post-test analysis of surrogate waste forms made from separate pours into the same graphite mold canister, testing the robustness of an upgraded crucible bottom drain and drain heater assembly, testing the effectiveness of inductive melt initiation using a resistive starter ring with a square wave configuration, and observing the tapped molten flow behavior in pans with areas identical to standard High Level Waste disposal canisters. Testing conditions, the surrogate waste composition, key testing steps, testing parameters, and sampling and analysis requirements are defined.

  19. Crystallisation of a zirconium-based glaze for ceramic tiles coatings

    OpenAIRE

    Romero, Maximina; Rincón López, Jesús María; Acosta, Anselmo

    2003-01-01

    The effect of iron oxide content on the crystallisation of a zirconium-based glass-ceramic glaze was investigated using a glass-ceramic “white of zirconium” frit and a granite waste glass. Measurements by X-ray diffraction (XRD) combined with scanning electron microscopy (SEM) and EDX microanalysis showed that Fe2O3 gives rise to the crystallisation of an iron-zinc ferrite, which is acting as nucleating agent of feather-like crystals of pyroxene while granite frit enhances the partial dissolu...

  20. A modeling study on the thermomechanical behavior of glass-ceramic and self-healing glass seals at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Govindaraju, Nirmal; Liu, Wenning N.; Sun, Xin; Singh, Prabhakar; Singh, R.

    2009-05-15

    Hermetic gas seals are critical components for planar solid oxide fuel cells. This article focuses on comparative evaluation of a glass-ceramic developed by the Pacific Northwest National Laboratory (PNNL) and a self-healing glass seal developed by the University of Cincinnati. The stress and strain levels in the Positive electrode-Electrolyte-Negative electrode (PEN) seal in one cell stack are evaluated using a multi-physics simulation package developed at PNNL. Simulations were carried out with and without consideration of clamping force and stack body force, respectively. The results indicate that the overall stress and strain levels are dominated by the thermal expansion mismatches between the different cell components. Further, compared with glass-ceramic seal, the self-healing glass seal results in much lower steady state stress due to its much lower stiffness at the operating temperature of SOFC, and also exhibits much shorter relaxation times due to high creep rate. It is also noted that the self-healing glass seal will experience continuing creep deformation under the operating temperature of SOFC therefore resulting in possible overflow of the sealing materials. Further stopper material may need to be added to maintain its geometric stability during operation.

  1. A modeling study on the thermomechanical behavior of glass-ceramic and self-healing glass seals at elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Govindaraju, N.; Singh, R.N. [Department of Chemical and Materials Engineering, University of Cincinnati, Cincinnati, OH 45221 (United States); Liu, W.N.; Sun, X.; Singh, P. [Pacific Northwest National Laboratory, Richland, WA 99354 (United States)

    2009-05-15

    Hermetic gas seals are critical components of planar Solid Oxide Fuel Cells (SOFCs). This article focuses on the comparative evaluation of a glass-ceramic seal developed by the Pacific Northwest National Laboratory (PNNL) and a self-healing glass seal developed by the University of Cincinnati. The stress and strain levels in the Positive electrode-Electrolyte-Negative electrode (PEN) seal in a single-cell stack are evaluated using a multi-physics simulation package developed at PNNL. Simulations were carried out with and without consideration of a clamping force and a stack body force, respectively. The results indicate that the overall stress and strain levels are dominated by the thermal expansion mismatches between the different cell components. Further, compared with the glass-ceramic, the self-healing glass results in a much lower steady state stress value due to its much lower stiffness at the operating temperature of the SOFC. It also exhibits much shorter relaxation times due to a high creep rate. It is also noted that the self-healing glass seal will experience continuing creep deformation at the operating temperature of a SOFC therefore resulting in possible overflow of the sealant material. Therefore, a stopper material may be required to maintain its geometric stability during operation. (author)

  2. Characterization of ceramic/glass composite seals for solid oxide fuel cells

    Science.gov (United States)

    Dev, Bodhayan

    Solid oxide fuel cells (SOFCs) require seals that can function in harsh, elevated temperature environments. Comprehensive characterization and understanding of seals is needed for commercially viable SOFCs. The present research focuses on a novel ceramic/glass composite seal that is produced by roller compaction or tape casting of glass and ceramic powders and a proprietary organic binder. Upon heat treatment, micro-voids and surface anomalies are formed. Increased heating and cooling rates during the heat treatment resulted in more and larger voids. The first goal of the current research is to suggest an appropriate heating and cooling rate to minimize the formation of microstructural defects. After identifying an appropriate cure cycle, seals were thermally cycled and then characterized with laser dilatometry, X-Ray diffraction, and sonic resonance. From these experiments the crystalline phases, thermal expansion, and elastic properties were determined. Subsequently compression testing with an acoustic emission (AE) sensor and post-test microstructural analysis were used to identify the formation of damage. The research also focuses on the study of Weibull statistics and thermal responses for cured seals. The green seal was initially cured for 1 thermal cycle based on the aforementioned appropriate thermal cycle. The cycled seal was then characterized with a laser dilatometer to identify the glass transition, softening temperature and thermal expansion properties. High temperature ring-on-ring tests were also performed to study the effect of glass transition and softening temperatures on mechanical responses. In addition, Weibull statistics were conducted to determine the cumulative probability of failure/damage in seals. The third part of the research focuses on the construction and use of a controlled leak testing facility for investigating different interfaces involved in sealing electrolyte-supported cells. Simultaneous leak testing with an acoustic emission

  3. Irradiation conditions for fiber laser bonding of HAp-glass ceramics with bovine cortical bone.

    Science.gov (United States)

    Tadano, Shigeru; Yamada, Satoshi; Kanaoka, Masaru

    2014-01-01

    Orthopedic implants are widely used to repair bones and to replace articulating joint surfaces. It is important to develop an instantaneous technique for the direct bonding of bone and implant materials. The aim of this study was to develop a technique for the laser bonding of bone with an implant material like ceramics. Ceramic specimens (10 mm diameter and 1 mm thickness) were sintered with hydroxyapatite and MgO-Al2O3-SiO2 glass powders mixed in 40:60 wt% proportions. A small hole was bored at the center of a ceramic specimen. The ceramic specimen was positioned onto a bovine bone specimen and a 5 mm diameter area of the ceramic specimen was irradiated using a fiber laser beam (1070-1080 nm wavelength). As a result, the bone and the ceramic specimens bonded strongly under the irradiation conditions of a 400 W laser power and a 1.0 s exposure time. The maximum shear strength was 5.3 ± 2.3 N. A bonding substance that penetrated deeply into the bone specimen was generated around the hole in the ceramic specimen. On using the fiber laser, the ceramic specimen instantaneously bonded to the bone specimen. Further, the irradiation conditions required for the bonding were investigated.

  4. Glass ceramic obtained by tailings and tin mine waste reprocessing from Llallagua, Bolivia

    Science.gov (United States)

    Arancibia, Jony Roger Hans; Villarino, Cecilia; Alfonso, Pura; Garcia-Valles, Maite; Martinez, Salvador; Parcerisa, David

    2014-05-01

    In Bolivia Sn mining activity produces large tailings of SiO2-rich residues. These tailings contain potentially toxic elements that can be removed into the surface water and produce a high environmental pollution. This study determines the thermal behaviour and the viability of the manufacture of glass-ceramics from glass. The glass has been obtained from raw materials representative of the Sn mining activities from Llallagua (Bolivia). Temperatures of maximum nucleation rate (Tn) and crystallization (Tcr) were calculated from the differential thermal analyses. The final mineral phases were determined by X-ray diffraction and textures were observed by scanning electron microscopy. Crystalline phases are nefeline occurring with wollastonite or plagioclase. Tn for nepheline is between 680 ºC and 700 ºC, for wollastonite, 730 ºC and for plagioclase, 740 ºC. Tcr for nefeline is between 837 and 965 ºC; for wollastonite, 807 ºC and for plagioclase, 977 ºC. In order to establish the mechanical characteristics and efficiency of the vitrification process in the fixation of potentially toxic elements the resistance to leaching and micro-hardness were determined. The obtained contents of the elements leached from the glass ceramic are well below the limits established by the European legislation. So, these analyses confirm that potentially toxic elements remain fixed in the structure of mineral phases formed in the glass-ceramic process. Regarding the values of micro-hardness results show that they are above those of a commercial glass. The manufacture of glass-ceramics from mining waste reduces the volume of tailings produced for the mining industry and, in turn enhances the waste, transforming it into a product with industrial application. Acknowledgements: This work was partly financed by the project AECID: A3/042750/11, and the SGR 2009SGR-00444.

  5. Luminescence properties of Pr{sup 3+}-doped transparent oxyfluoride glass-ceramics containing BaYF{sub 5} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Gu Mu, E-mail: mgu@mail.tongji.edu.cn [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Department of Physics, Tongji University, Shanghai 200092 (China); Gao Qingchun [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Department of Physics, Tongji University, Shanghai 200092 (China); Huang Shiming, E-mail: smhuang2008@yahoo.com.cn [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Department of Physics, Tongji University, Shanghai 200092 (China); Liu Xiaolin; Liu Bo; Ni Chen [Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, Department of Physics, Tongji University, Shanghai 200092 (China)

    2012-10-15

    Transparent oxyfluoride glass-ceramics containing BaYF{sub 5} nanocrystals were successfully synthesized by appropriate heat-treatment on the SiO{sub 2}-Al{sub 2}O{sub 3}-Na{sub 2}O-BaF{sub 2}-Y{sub 2}O{sub 3}-Pr{sub 6}O{sub 11} precursor glass. The structure and luminescence properties of the precursor glass and glass-ceramics were investigated by DSC, XRD, TEM, optical transmission, photoluminescence, decay time and radioluminescence spectra. The XRD results indicate that the BaYF{sub 5} nanocrystals can percitated in the precursor glass and the sharper emission peaks of Pr{sup 3+} in glass ceramic suggests that Pr{sup 3+} ions are incorporated into the BaYF{sub 5} nanocrystals. The higher the heat-treatment temperature is, the more the Pr{sup 3+} ions are centered into BaYF{sub 5} nanocrystals, which results in the optimal concentration of Pr{sup 3+} in glass ceramic changes on heat-treatment temperature. It is notable that the emission intensity of both photoluminescence and radioluminescence for 0.1 mol% Pr{sup 3+} in the glass ceramic (GC665) are stronger than those in the precursor glass. The mechanism of enhanced luminescence is also discussed. - Highlights: Black-Right-Pointing-Pointer The Pr{sup 3+} ions have been incorporated into BaYF{sub 5} nanocrystals. Black-Right-Pointing-Pointer The optimal concentration of Pr{sup 3+} in glass ceramic changes on temperature. Black-Right-Pointing-Pointer The lifetime of Pr{sup 3+} in the glass ceramic is slightly shorter than that in glass. Black-Right-Pointing-Pointer The luminescence intensity of Pr{sup 3+} in nanocrystals is stronger than that in glass.

  6. Preliminary study in development of glass-ceramic based on SiO{sub 2}-LiO{sub 2} system, starting of different SiO{sub 2} starting powders; Um estudo preliminar do desenvolvimento de materiais vitroceramicos do sistema SiO{sub 2}-LiO{sub 2} obtidos a partir de diferentes fontes de silica

    Energy Technology Data Exchange (ETDEWEB)

    Daguano, J.K.M.F.; Santos, F.A.; Santos, C.; Marton, L.F.M.; Conte, R.A.; Rodrigues Junior, D. [Universidade de Sao Paulo (EEL/USP), Lorena, SP (Brazil). Escola de Engenharia de Lorena. Dept. de Materiais; Melo, F.C.L. [Centro Tecnico Aeroespacial (AMR/CTA/IAE), Sao Jose dos Campos, SP (Brazil). Instituto de Aeronautica e Espaco. Div. de Materiais

    2009-07-01

    In this work, lithium disilicate glass-ceramics were developed starting of the rice ash- SiO{sub 2} and Li{sub 2}CO{sub 3} powders. The results were compared with glass ceramics based on the lithium disilicate obtained by commercial SiO{sub 2} powders. Glass were melted at 1580 deg C, and annealed at 850 deg C. X-Ray diffraction and scanning electron microscopy were used for characterization of the materials, and hardness and fracture toughness were evaluated using Vickers indentation method. Glasses with amorphous structure were obtained in both materials. After annealing, 'rice-ash' samples presented Li{sub 2}SiO{sub 3} and residual SiO{sub 2} as crystalline phases. On the other side, commercial SiO{sub 2}- Samples presented only Li{sub 2}Si{sub 2}O{sub 5} as crystalline phases and the better results of hardness and fracture toughness. (author)

  7. Transparent glass-ceramics containing Eu3+ and Dy3+ ions for visible optoelectronics

    Science.gov (United States)

    Pisarska, Joanna; Żur, Lidia; Pisarski, Wojciech A.

    2011-06-01

    Selected oxyfluoride glasses containing Eu3+ and Dy3+ were heat treated in order to obtain transparent glass-ceramics. Visible emission spectra corresponding to 5D0 - 7FJ (J = 0, 1, 2, 3, 4) transitions of Eu3+ and 4F9/2 - 6HJ/2 (J = 11, 13, 15) transitions of Dy3+ in glass samples before and after heat treatment were registered. The luminescence intensity ratios R (Eu3+) and Y/B (Dy3+) have been analyzed in details. Their values are reduced due to part incorporation of rare earth ions into cubic β-PbF2 crystalline phase.

  8. Effect of the CaF2-fraction in the glass-ceramic with abrasion resistance on crystallization

    Institute of Scientific and Technical Information of China (English)

    HU Bin-liang; Zhao Yun-cai

    2005-01-01

    Investigated the effect of an addition of CaF2 on the crystallization of a glass-ceramic with abrasion resistance. X-ray diffraction, differential thermal analysis and scanning electron microscopy were used to determine the effect. The results showed that a suitable addition of CaF2 promoted crystallization by forming an intermediate crystalline phase. CaF2 can decrease the temperature and active energy of the base-glass for crystallization. When 4 mass-% of CaF2-fraction is added in the glass, the crystallization temperature and active energy is 936℃and 172.75 k J/mol respectively.When CaF2 is increased to 6 mass-%, the temperature and active energy decrease to 890℃ and 88.81 kJ/mol. CaF2 is an efficient nucleating agent for the glass-ceramics with abrasion resistant, the optimal content of CaF2 is about 6 mass-%.

  9. Nanostructured bioactive glass-ceramic coatings deposited by the liquid precursor plasma spraying process

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Yanfeng; Song Lei; Liu Xiaoguang; Huang Yi; Huang Tao; Wu Yao; Chen Jiyong [National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road Chengdu, Sichuan 610064 (China); Wu Fang, E-mail: fwu@scu.edu.cn [National Engineering Research Center for Biomaterials, Sichuan University, 29 Wangjiang Road Chengdu, Sichuan 610064 (China)

    2011-01-01

    Bioactive glass-ceramic coatings have great potential in dental and orthopedic medical implant applications, due to its excellent bioactivity, biocompatibility and osteoinductivity. However, most of the coating preparation techniques either produce only thin thickness coatings or require tedious preparation steps. In this study, a new attempt was made to deposit bioactive glass-ceramic coatings on titanium substrates by the liquid precursor plasma spraying (LPPS) process. Tetraethyl orthosilicate, triethyl phosphate, calcium nitrate and sodium nitrate solutions were mixed together to form a suspension after hydrolysis, and the liquid suspension was used as the feedstock for plasma spraying of P{sub 2}O{sub 5}-Na{sub 2}O-CaO-SiO{sub 2} bioactive glass-ceramic coatings. The in vitro bioactivities of the as-deposited coatings were evaluated by soaking the samples in simulated body fluid (SBF) for 4 h, 1, 2, 4, 7, 14, and 21 days, respectively. The as-deposited coating and its microstructure evolution behavior under SBF soaking were systematically analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP), and Fourier transform infrared (FTIR) spectroscopy. The results showed that P{sub 2}O{sub 5}-Na{sub 2}O-CaO-SiO{sub 2} bioactive glass-ceramic coatings with nanostructure had been successfully synthesized by the LPPS technique and the synthesized coatings showed quick formation of a nanostructured HCA layer after being soaked in SBF. Overall, our results indicate that the LPPS process is an effective and simple method to synthesize nanostructured bioactive glass-ceramic coatings with good in vitro bioactivity.

  10. Nanostructured bioactive glass-ceramic coatings deposited by the liquid precursor plasma spraying process

    Science.gov (United States)

    Xiao, Yanfeng; Song, Lei; Liu, Xiaoguang; Huang, Yi; Huang, Tao; Wu, Yao; Chen, Jiyong; Wu, Fang

    2011-01-01

    Bioactive glass-ceramic coatings have great potential in dental and orthopedic medical implant applications, due to its excellent bioactivity, biocompatibility and osteoinductivity. However, most of the coating preparation techniques either produce only thin thickness coatings or require tedious preparation steps. In this study, a new attempt was made to deposit bioactive glass-ceramic coatings on titanium substrates by the liquid precursor plasma spraying (LPPS) process. Tetraethyl orthosilicate, triethyl phosphate, calcium nitrate and sodium nitrate solutions were mixed together to form a suspension after hydrolysis, and the liquid suspension was used as the feedstock for plasma spraying of P 2O 5-Na 2O-CaO-SiO 2 bioactive glass-ceramic coatings. The in vitro bioactivities of the as-deposited coatings were evaluated by soaking the samples in simulated body fluid (SBF) for 4 h, 1, 2, 4, 7, 14, and 21 days, respectively. The as-deposited coating and its microstructure evolution behavior under SBF soaking were systematically analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), inductively coupled plasma (ICP), and Fourier transform infrared (FTIR) spectroscopy. The results showed that P 2O 5-Na 2O-CaO-SiO 2 bioactive glass-ceramic coatings with nanostructure had been successfully synthesized by the LPPS technique and the synthesized coatings showed quick formation of a nanostructured HCA layer after being soaked in SBF. Overall, our results indicate that the LPPS process is an effective and simple method to synthesize nanostructured bioactive glass-ceramic coatings with good in vitro bioactivity.

  11. Agricultural wastes as a resource of raw materials for developing low-dielectric glass-ceramics

    Science.gov (United States)

    Danewalia, Satwinder Singh; Sharma, Gaurav; Thakur, Samita; Singh, K.

    2016-04-01

    Agricultural waste ashes are used as resource materials to synthesize new glass and glass-ceramics. The as-prepared materials are characterized using various techniques for their structural and dielectric properties to check their suitability in microelectronic applications. Sugarcane leaves ash exhibits higher content of alkali metal oxides than rice husk ash, which reduces the melting point of the components due to eutectic reactions. The addition of sugarcane leaves ash in rice husk ash promotes the glass formation. Additionally, it prevents the cristobalite phase formation. These materials are inherently porous, which is responsible for low dielectric permittivity i.e. 9 to 40. The presence of less ordered augite phase enhances the dielectric permittivity as compared to cristobalite and tridymite phases. The present glass-ceramics exhibit lower losses than similar materials synthesized using conventional minerals. The dielectric permittivity is independent to a wide range of temperature and frequency. The glass-ceramics developed with adequately devitrified phases can be used in microelectronic devices and other dielectric applications.

  12. Calcium phosphate glass-ceramics for bioactive coating on a β-titanium alloy

    International Nuclear Information System (INIS)

    The formation of a porous coating is the decisive feature for the bio-compatibility of silica-free calcium phosphate glass ceramics on alloy surfaces like the β-Ti structured Ti-29Nb-13Ta-4.6Zr used in this work. The ceramic composition is highly important: 50CaO-40P2O5-7Na2O-3TiO2 glass powder produces a pore-free coating unable to bind hydroxyapatite, whereas 60CaO-30P2O5-7Na2O-3TiO2 glass incorporates pores from which a crystalline hydroxyapatite phase can grow over the surface from simulated body fluid (see Figure). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  13. Radiation effects in glass and glass-ceramic waste forms for the immobilization of CANDU UO2 fuel reprocessing waste

    International Nuclear Information System (INIS)

    AECL has investigated three waste forms for the immobilization of high-level liquid wastes that would arise if used CANDU fuels were reprocessed at some time in the future to remove fissile materials for the fabrication of new power reactor fuel. These waste forms are borosilicate glasses, aluminosilicate glasses and titanosilicate glass-ceramics. This report discusses the potential effects of alpha, beta and gamma radiation on the releases of radionuclides from these waste forms as a result of aqueous corrosion by groundwaters that would be present in an underground waste disposal vault. The report discusses solid-state damage caused by radiation-induced atomic displacements in the waste forms as well as irradiation of groundwater solutions (radiolysis), and their potential effects on waste-form corrosion and radionuclide release. The current literature on radiation effects on borosilicate glasses and in ceramics is briefly reviewed, as are potential radiation effects on specialized waste forms for the immobilization of 129I, 85Kr and 14C. (author). 104 refs., 9 tabs., 5 figs

  14. The microstructure of erbium-ytterbium co-doped oxyfluoride glass-ceramic optical fibers

    Science.gov (United States)

    Augustyn, Elżbieta; Żelechower, Michał; Stróż, Danuta; Chrapoński, Jacek

    2012-04-01

    Oxyfluoride transparent glass-ceramics combine some features of glasses (easier shaping or lower than single crystals cost of fabrication) and some advantages of rare-earth doped single crystals (narrow absorption/emission lines and longer lifetimes of luminescent levels). Since the material seems to be promising candidate for efficient fiber amplifiers, the manufacturing as well as structural and optical examination of the oxyfluoride glass-ceramic fibers doped with rare-earth ions seems to be a serious challenge. In the first stage oxyfluoride glasses of the following compositions 48SiO2-11Al2O3-7Na2CO3-10CaO-10PbO-11PbF2-3ErF3 and 48SiO2-11Al2O3-7Na2CO3-10CaO-10PbO-10PbF2-3YbF3-1ErF3 (in molar%) were fabricated from high purity commercial chemicals (Sigma-Aldrich). The fabricated glass preforms were drawn into glass fibers using the mini-tower. Finally, the transparent Er3+ doped and Er3+/Yb3+ co-doped oxyfluoride glass-ceramic fibers were obtained by controlled heat treatment of glass fibers. The preceding differential thermal analysis (DTA) studies allowed estimating both the fiber drawing temperature and the controlled crystallization temperature of glass fibers. X-ray diffraction examination (XRD) at each stage of the glass-ceramic fibers fabrication confirmed the undesirable crystallization of preforms and glass fibers has been avoided. The fibers shown their mixed amorphous-crystalline microstructure with nano-crystals of size even below 10 nm distributed in the glassy host. The crystal structure of the grown nano-crystals has been determined by XRD and confirmed by electron diffraction (SAED). Results obtained by both techniques seem to be compatible: Er3FO10Si3 (monoclinic; ICSD 92512), Pb5Al3F19 (triclinic; ICSD 91325) and Er4F2O11Si3 (triclinic; ICSD 51510) against to initially expected PbF2 crystals.

  15. Nanoparticles size effects in thermoluminescence of oxyfluoride glass-ceramics containing Sm3+-doped CaF2 nanocrystals

    International Nuclear Information System (INIS)

    Oxyfluoride glass-ceramic in the system SiO2–Al2O3–CaF2–SmF3 containing Sm3+-doped CaF2 nanocrystals in the range from 15 to 150 nm size were produced by using the controlled ceramization of the precursor glass. The incorporation of the Sm3+-dopant ion in the glass ceramic creates new electron-trapping centers and thermoluminescence (TL) method has been used in order to trace their evolution during glass ceramization. The 370 °C TL peak observed in precursor glass has been assigned to the recombination of the electrons released from the Sm2+-traps in the amorphous glass network. In the glass-ceramic sample containing nanocrystals with about 15 nm size the new weak TL peaks at 270, 290, and 310 °C were attributed to the recombination of the electrons released from the Sm2+-traps located mainly at the surface of the CaF2 nanocrystals. In the glass-ceramic sample containing nanocrystals with about 150 nm size, the new TL peaks at 232, 270, and 302 °C size have been assigned to the recombination of the electrons released from the Sm2+-traps located inside the CaF2 nanocrystals.

  16. Fabrication and characterization of Er+3 doped SiO2/SnO2 glass-ceramic thin films for planar waveguide applications

    Science.gov (United States)

    Guddala, S.; Chiappini, A.; Armellini, C.; Turell, S.; Righini, G. C.; Ferrari, M.; Narayana Rao, D.

    2015-02-01

    Glass-ceramics are a kind of two-phase materials constituted by nanocrystals embedded in a glass matrix and the respective volume fractions of crystalline and amorphous phase determine the properties of the glass-ceramics. Among these properties transparency is crucial in particular when confined structures, such as, dielectric optical waveguides, are considered. Moreover, the segregation of dopant rare-earth ions, like erbium, in low phonon energy crystalline medium makes these structures more promising in the development of waveguide amplifiers. Here we are proposing a new class of low phonon energy tin oxide semiconductor medium doped silicate based planar waveguides. Er3+ doped (100-x) SiO2-xSnO2 (x= 10, 20, 25 and 30mol%), glass-ceramic planar waveguide thin films were fabricated by a simple sol-gel processing and dip coating technique. XRD and HRTEM studies indicates the glass-ceramic phase of the film and the dispersion of ~4nm diameter of tin oxide nanocrystals in the amorphous phase of silica. The spectroscopic assessment indicates the distribution of the dopant erbium ions in the crystalline medium of tin oxide. The observed low losses, 0.5±0.2 dB/cm, at 1.54 μm communication wavelength makes them a quite promising material for the development of high gain integrated optical amplifiers.

  17. Neodymium Partitioning in Glass-Ceramic Designed for Actinides Immobilization

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>In the backend of nuclear fuel cycle, plutonium-containing wastes are inevitable to be produced. Glass as the matrix for HLLW is not appropriate for immobilize the plutonium waste due the poor solubility of

  18. Floor tile glass-ceramic glaze for improvement of the resistance to surface abrasion

    Energy Technology Data Exchange (ETDEWEB)

    Gajek, M; Lis, J; Partyka, J; Wojczyk, M, E-mail: mgajek@agh.edu.pl [AGH University of Science and Technology, Faculty of Materials Science and Ceramic, al. Mickiewicza 30, 30-059 Cracow (Poland)

    2011-10-29

    The results of research aimed at the study on frits and glass-ceramic glazes for floor tiles, based on compositions located in the primary field of cordierite crystallization within the system MgO-Al{sub 2}O{sub 3}-SiO{sub 2}, have been presented. The results comprise investigations on the frits crystallization abilities, stability of the crystallizing phase under conditions of single-stage a fast firing cycle (time below 60 minutes) depending on their chemical composition and the influence of the nucleation agents. The influence of the nucleating agents namely TiO{sub 2}, ZrO{sub 2}, V{sub 2}O{sub 5} on phase composition of obtained crystalline glazes, mechanical parameters and microstructure, has been examined. The strength tests proved increased mechanical resistance of crystalline glazes. Obtained glazes are characterized by high microhardness in range 6{approx}8 GPa, as well as the increased wear resistance measured by the loss of weight below 100 mg / 55 cm{sup 2} (PN-EN ISO 10545-7). Significant increase of these parameters as compared with non-crystalline glazes, where micro-hardness values range between 5{approx}6 GPa and the wear resistance values range from 120 to 200 mg, has been proved. Starting glasses (frits) and glazes of the ternary system MgO-SiO{sub 2}-Al{sub 2}O{sub 3}, were examined with use of DTA, XRD and SEM methods.

  19. Floor tile glass-ceramic glaze for improvement of the resistance to surface abrasion

    Science.gov (United States)

    Gajek, M.; Lis, J.; Partyka, J.; Wójczyk, M.

    2011-10-01

    The results of research aimed at the study on frits and glass-ceramic glazes for floor tiles, based on compositions located in the primary field of cordierite crystallization within the system MgO-Al2O3-SiO2, have been presented. The results comprise investigations on the frits crystallization abilities, stability of the crystallizing phase under conditions of single-stage a fast firing cycle (time below 60 minutes) depending on their chemical composition and the influence of the nucleation agents. The influence of the nucleating agents namely TiO2, ZrO2, V2O5 on phase composition of obtained crystalline glazes, mechanical parameters and microstructure, has been examined. The strength tests proved increased mechanical resistance of crystalline glazes. Obtained glazes are characterized by high microhardness in range 6~8 GPa, as well as the increased wear resistance measured by the loss of weight below 100 mg / 55 cm2 (PN-EN ISO 10545-7). Significant increase of these parameters as compared with non-crystalline glazes, where micro-hardness values range between 5~6 GPa and the wear resistance values range from 120 to 200 mg, has been proved. Starting glasses (frits) and glazes of the ternary system MgO-SiO2-Al2O3, were examined with use of DTA, XRD and SEM methods.

  20. Waveguides in Ni-doped glass and glass-ceramic written with a 1 kHz femtosecond laser

    Science.gov (United States)

    Hughes, M. A.; Homewood, K. P.; Curry, R. J.; Ohishi, Y.; Suzuki, T.

    2014-07-01

    We report waveguides in Ni-doped Li2O-Ga2O3-SiO2 (Ni:LGS) glass and glass-ceramic (GC) fabricated with a femtosecond (fs) laser with repetition rate of 1 kHz. When the glass is annealed to form a GC, the waveguides are erased. However, in the GC the waveguides are not erased by annealing. In Ni:LGS GC a 415 nm absorption band was created by fs laser waveguide writing due to the creation of Ni nanoparticles with an estimated diameter of a few nm. Raman and photoluminescence spectra of the bulk and waveguide structures were indistinguishable; however, fluorescence decay profiles indicated more long lifetime components in the waveguide compared to the bulk.

  1. Properties and crystallization phenomena in Li2Si2O5-Ca5(PO43F and Li2Si2O5-Sr5(PO43F glass-ceramics via twofold internal crystallization

    Directory of Open Access Journals (Sweden)

    Markus eRampf

    2015-09-01

    Full Text Available The combination of specific mechanical, esthetic and chemical properties is decisive for the application of materials in prosthodontics. Controlled twofold crystallization provides a powerful tool to produce special property combinations for glass-ceramic materials. The present study outlines the potential of precipitating Ca5(PO43F as well as Sr5(PO43F as minor crystal phases in Li2Si2O5 glass-ceramics. Base glasses with different contents of CaO/SrO, P2O5 and F- were prepared within the glasses of the SiO2-Li2O-K2O-CaO/SrO-Al2O3-P2O5 system. Preliminary studies of nucleation by means of XRD and SEM of the nucleated base glasses revealed X-ray amorphous phase separation phenomena. Qualitative and quantitative crystal phase analyses after crystallization were conducted using XRD in combination with Rietveld refinement. As a main result, a direct proportional relationship between the content of apatite-forming components in the base glasses and the content of apatite in the glass ceramics was established. The microstructures of the glass-ceramics were investigated using SEM. Microstructural and mechanical properties were found to be dominated by Li2Si2O5 crystals and quite independent of the content of the apatite present in the glass-ceramics. Biaxial strengths of up to 540 MPa were detected. Ca5(PO43F and Sr5(PO43F influence the translucency of the glass-ceramics and hence, help to precisely tailor the properties of Li2Si2O5 glass-ceramics. The authors conclude that the twofold crystallization of Li2Si2O5-Ca5(PO43F or Li2Si2O5-Sr5(PO43F glass-ceramics involves independent solid state reactions which can be controlled via the chemical composition of the base glasses. The influence of the minor apatite phase on the optical properties helps to achieve new combinations of features of the glass-ceramics and hence, displays new potential for dental applications.

  2. Preparation and studies on surface modifications of calcium-silico-phosphate ferrimagnetic glass-ceramics in simulated body fluid

    International Nuclear Information System (INIS)

    The structure and magnetic behaviour of 34SiO2-(45 - x) CaO-16P2O5-4.5 MgO-0.5 CaF2 - x Fe2O3 (where x = 5, 10, 15, 20 wt.%) glasses have been investigated. Ferrimagnetic glass-ceramics are prepared by melt quench followed by controlled crystallization. The surface modification and dissolution behaviour of these glass-ceramics in simulated body fluid (SBF) have also been studied. Phase formation and magnetic behaviour have been studied using XRD and SQUID magnetometer. The room temperature Moessbauer study has been done to monitor the local environment around Fe cations and valence state of Fe ions. X-ray photoelectron spectroscopy (XPS) was used to study the surface modification in glass-ceramics when immersed in simulated body fluid. Formation of bioactive layer in SBF has been ascertained using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The SBF solutions were analyzed using an absorption spectrophotometer. The magnetic measurements indicated that all these glasses possess paramagnetic character and the [Fe2+/Fe3+] ions ratio depends on the composition of glass and varied with Fe2O3 concentration in glass matrix. In glass-ceramics saturation magnetization increases with increase in amount of Fe2O3. The nanostructure of hematite and magnetite is formed in the glass-ceramics with 15 and 20 wt.% Fe2O3, which is responsible for the magnetic property of these glass-ceramics. Introduction of Fe2O3 induces several modifications at the glass-ceramics surface when immersed in SBF solution and thereby affecting the surface dissolution and the formation of the bioactive layer.

  3. Luminescent properties of Eu{sup 3+}-Tb{sup 3+}-doped SiO{sub 2}-SnO{sub 2}-based nano-glass-ceramics prepared by sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, J. del [Departamento de Fisica Basica, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain)], E-mail: fjvargas@ull.es; Yanes, A.C. [Departamento de Fisica Basica, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain); Velazquez, J.J.; Mendez-Ramos, J.; Rodriguez, V.D. [Departamento de Fisica Fundamental y Experimental, Electronica y Sistemas, Universidad de La Laguna, 38206 La Laguna, Tenerife (Spain)

    2009-04-03

    Transparent nano-glass-ceramics of composition 95SiO{sub 2}-5SnO{sub 2} mol%, single doped with 0.4 mol% of Tb{sup 3+} and co-doped with 0.4 mol% of Eu{sup 3+} and Tb{sup 3+} have been obtained by thermal treatment of precursor sol-gel glasses. The segregated SnO{sub 2} nanocrystals, precipitated in the insulator SiO{sub 2} glass matrix during heat treatment, constitute a wide band gap quantum-dot system with mean radius of nanocrystals around 2.2-2.8 nm, comparable to the bulk exciton Bohr radius. A fraction of the rare earth ions is incorporated to the SnO{sub 2} nanocrystals and can be excited by energy transfer from the semiconductor host. The efficiency of this energy transfer process is strongly dependent on the nanocrystal radius in the case of the Tb{sup 3+} ions, whereas the dependence is not appreciable in the case of Eu{sup 3+} ions. These results can be explained taking into account the variations of the overlap of the SnO{sub 2} broad visible emission due to oxygen vacancies with the rare earth excitation spectra.

  4. Development and testing of matrices for the encapsulation of glass and ceramic nuclear waste forms

    International Nuclear Information System (INIS)

    This report details the results of research on the matrix encapsulation of high level wastes at PML over the past few years. The demonstrations and tests described were designed to illustrate how the waste materials are effected when encapsulated in an inert matrix. Candidate materials evaluated for potential use as matrices for encapslation of pelletized ceramics or glass marbles were categorized into four groups: metals, glasses, ceramics, and graphite. Two processing techniques, casting and hot pressing, were investigated as the most promising methods of formation or densification of the matrices. The major results reported deal with the development aspects. However, chemical durability tests (leach tests) of the matrix materials themselves and matrix-waste form composites are also reported. Matrix waste forms can provide a low porosity, waste-free barrier resulting in increased leach protection, higher impact strength and improved thermal conductivity compared to unencapsulated glass or ceramic waste materials. Glass marbles encapsulated in a lead matrix offer the most significant improvement in waste form stability of all combinations evaluated. This form represents a readily demonstrable process that provides high thermal conductivity, mechanical shock resistance, radiation shielding and increased chemical durability through both a chemical passivation mechanism and as a physical barrier. Other durable matrix waste forms evaluated, applicable primarily to ceramic pellets, involved hot-pressed titanium or TiO2 materials. In the processing of these forms, near 100% dense matrices were obtained. The matrix materials had excellent compatibility with the waste materials and superior potential chemical durability. Cracking of the hot-pressed ceramic matrix forms, in general, prevented the realization of their optimum properties

  5. Sintered glass ceramic composites from vitrified municipal solid waste bottom ashes.

    Science.gov (United States)

    Aloisi, Mirko; Karamanov, Alexander; Taglieri, Giuliana; Ferrante, Fabiola; Pelino, Mario

    2006-09-01

    A glass ceramic composite was obtained by sinter-crystallisation of vitrified municipal solid waste bottom ashes with the addition of various percentages of alumina waste. The sintering was investigated by differential dilatometry and the crystallisation of the glass particles by differential thermal analysis. The crystalline phases produced by the thermal treatment were identified by X-ray diffraction analysis. The sintering process was found to be affected by the alumina addition and inhibited by the beginning of the crystal-phase precipitation. Scanning electron microscopy was performed on the fractured sintered samples to observe the effect of the sintering. Young's modulus and the mechanical strength of the sintered glass ceramic and composites were determined at different heating rates. The application of high heating rate and the addition of alumina powder improved the mechanical properties. Compared to the sintered glass ceramic without additives, the bending strength and the Young's modulus obtained at 20 degrees C/min, increased by about 20% and 30%, respectively. PMID:16730889

  6. Sintered glass ceramic composites from vitrified municipal solid waste bottom ashes

    Energy Technology Data Exchange (ETDEWEB)

    Aloisi, Mirko [Department of Chemistry, Chemical Engineering and Materials, University of L' Aquila, Monteluco di Roio 67040 (Italy); Karamanov, Alexander [Department of Chemistry, Chemical Engineering and Materials, University of L' Aquila, Monteluco di Roio 67040 (Italy)]. E-mail: karama@ing.univaq.it; Taglieri, Giuliana [Department of Chemistry, Chemical Engineering and Materials, University of L' Aquila, Monteluco di Roio 67040 (Italy); Ferrante, Fabiola [Department of Chemistry, Chemical Engineering and Materials, University of L' Aquila, Monteluco di Roio 67040 (Italy); Pelino, Mario [Department of Chemistry, Chemical Engineering and Materials, University of L' Aquila, Monteluco di Roio 67040 (Italy)]. E-mail: pelino@ing.univaq.it

    2006-09-01

    A glass ceramic composite was obtained by sinter-crystallisation of vitrified municipal solid waste bottom ashes with the addition of various percentages of alumina waste. The sintering was investigated by differential dilatometry and the crystallisation of the glass particles by differential thermal analysis. The crystalline phases produced by the thermal treatment were identified by X-ray diffraction analysis. The sintering process was found to be affected by the alumina addition and inhibited by the beginning of the crystal-phase precipitation. Scanning electron microscopy was performed on the fractured sintered samples to observe the effect of the sintering. Young's modulus and the mechanical strength of the sintered glass ceramic and composites were determined at different heating rates. The application of high heating rate and the addition of alumina powder improved the mechanical properties. Compared to the sintered glass ceramic without additives, the bending strength and the Young's modulus obtained at 20 deg. C/min, increased by about 20% and 30%, respectively.

  7. Enhanced upconversion in Ho3+-doped transparent glass ceramics containing BaYbF5 nanocrystals

    International Nuclear Information System (INIS)

    Novel Ho3+-doped transparent oxyfluoride SiO2–Al2O3–Na2CO3–CaO–BaF2–YbF3 glass ceramics (GC) containing BaYbF5 nanocrystals were fabricated via melt-quenching technique with subsequent heat treatment. The formation of crystalline fluoride phase was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Compared to precursor glasses, the greatly enhanced green emission (40-fold), new emission band at ultraviolet-blue region and stark splittings of emission in GC, indicate that Ho3+ enters into BaYbF5 nanocrystals with low phonon energy. Besides, the origin of the previously unconfirmed emission band at 440–460 nm is clearly identified by measuring spectra from thermally coupled luminescent levels at various temperatures. The outstanding upconversion properties of Ho3+ in GC may present potential application in all-solid-state upconversion lasers operating in the visible and ultraviolet range. - Highlights: • Novel transparent glass ceramics containing BaYbF5 nanocrystals were fabricated. • The green upconversion intensity increases greatly (40-fold) in glass ceramics. • The origin of the previously unconfirmed emission is clearly identified in our work

  8. Properties of sintered glass-ceramics prepared from plasma vitrified air pollution control residues

    Energy Technology Data Exchange (ETDEWEB)

    Roether, J.A.; Daniel, D.J. [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Amutha Rani, D. [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom); Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ (United Kingdom); Deegan, D.E. [Tetronics Ltd., Swindon, Wiltshire SN3 4DE (United Kingdom); Cheeseman, C.R., E-mail: c.cheeseman@imperial.ac.uk [Department of Civil and Environmental Engineering, Imperial College London, London SW7 2AZ (United Kingdom); Boccaccini, A.R., E-mail: a.boccaccini@imperial.ac.uk [Department of Materials, Imperial College London, London SW7 2AZ (United Kingdom)

    2010-01-15

    Air pollution control (APC) residues, obtained from a major UK energy from waste (EfW) plant, processing municipal solid waste, have been blended with silica and alumina and melted using DC plasma arc technology. The glass produced was crushed, milled, uni-axially pressed and sintered at temperatures between 750 and 1150 deg. C, and the glass-ceramics formed were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Mechanical properties assessed included Vickers's hardness, flexural strength, Young's modulus and thermal shock resistance. The optimum sintering temperature was found to be 950 deg. C. This produced a glass-ceramic with high density ({approx}2.58 g/cm{sup 3}), minimum water absorption ({approx}2%) and relatively high mechanical strength ({approx}81 {+-} 4 MPa). Thermal shock testing showed that 950 deg. C sintered samples could withstand a 700 deg. C quench in water without micro-cracking. The research demonstrates that glass-ceramics can be readily formed from DC plasma treated APC residues and that these have comparable properties to marble and porcelain. This novel approach represents a technically and commercially viable treatment option for APC residues that allow the beneficial reuse of this problematic waste.

  9. A New Technology of Microcrystallizing Leucite to Reinforce Dental Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; PENG Bin; DUAN Xing-long; QIAN Fa-tang; WU Bo-lin

    2004-01-01

    The key technology and the main mechanism of microcrystallizing leucite to reirforce dentalglass ceramics were investigated. The feedstock powders were selected, mixed according to the ratios of the theoreti-cal composition of leucite, ball - milled, melted at 1600℃ and then cooled to room temperature quickly. Thecooled clinkers were ball - milled again to 4 μm. After cold - isostatic pressure molded and air sintered at 1 500℃for 1 h, the dental glass ceramics were fabricated. They have following characteristics: excellent mechanical prop-erties ( mean compressive strength is 206.6 MPa ), low sintering temperature and good reoccurrence to keep steadyquality.

  10. Transformation Mechanism of Fluormica to Fluoramphibole in Fluoramphibole Glass Ceramics

    Directory of Open Access Journals (Sweden)

    Wei Si

    2016-01-01

    Full Text Available During isothermal sintering at 820°C, the transformation mechanism of fluormica to fluoramphibole in powder compacts of fluormica and soda-lime glass was investigated using differential thermal analysis, infrared reflection spectrometry, X-ray diffraction, scanning electron microscopy, and so forth. Results show that an interaction between fluormica and glass occurred during isothermal heating; O2−, Na+, and Ca2+ ions were diffused from glass to fluormica. This diffusion facilitates the transformation of the sheet structures of fluormica crystals to double-chain structures by the breakage of bridge oxygen bonds in the sheet. Subsequently, the broken two parallel double chains were rearranged by relative displacement along the c-axis direction of the fluormica crystal and were linked by Na+ and Ca2+ ions to form fluoramphibole. A crystallography model of fluormica-fluoramphibole transformation was established in this study.

  11. Improving adhesion between luting cement and zirconia-based ceramic with an alternative surface treatment.

    Science.gov (United States)

    Martins, Aurealice Rosa Maria; Gotti, Valéria Bisinoto; Shimano, Marcos Massao; Borges, Gilberto Antônio; Gonçalves, Luciano de Souza

    2015-01-01

    This study evaluated the influence of an alternative surface treatment on the microshear bond strength (μsbs) of zirconia-based ceramic. Thirty-five zirconia disks were assigned to five groups according to the following treatments: Control (CO), glass and silane were not applied to the zirconia surface; G1, air blasted with 100μm glass beads + glaze + silane; G2, a gel containing 15% (by weight) glass beads applied to the ceramic surface + glaze + silane; G3, a gel containing 25% (by weight) glass beads applied to the ceramic surface + glaze + silane; and G4, a gel containing 50% (by weight) glass beads applied to the ceramic surface + glaze + silane. The specimens were built up using RelyX ARC®, according to the manufacturer's recommendations, and inserted in an elastomeric mold with an inner diameter of 0.8 mm. The μsbs test was performed using a testing machine at a crosshead speed of 0.5 mm/min. ANOVA and Tukey's test (p ceramic and the luting cement. PMID:25859635

  12. Study of glass ceramic material on the base of ash group simulating slag of plasma shaft furnace for high temperature reprocessing of radioactive wastes

    International Nuclear Information System (INIS)

    Using the methods of X-ray diffraction, differential thermal and micro-probe analysis it is shown that the processes of minerals formation and homogenization in ash residue based charge under the heating up to 1450 deg C take place with a high rate and completely finish during 10 minutes. Homogeneous materials containing besides glassy phase crystalline phases and metallic shots are formed in this process. The products obtained with fluxes (dolomite and clay) additions are more homogeneous than a flux-less fused slag. Losses of α-radioactive nuclides during the melting of ash residue at 1300 deg C do not exceed 1.5% and is likely attributed with the products of uranium decay. Hydrolytic stability of the slags estimated from the rate of α-radioactive elements lixiviation is on the level of (1.4-5.7)x10-4 g/(cm2 x day) at 95 deg C

  13. Structural and physical characteristics of CeO2-GeO2-PbO glasses and glass ceramics

    International Nuclear Information System (INIS)

    Samples of the xCeO2(100 - x)[GeO2.PbO] system with 0 ≤ x ≤ 15 mol% were prepared and characterized by X-ray diffraction, FT-IR spectroscopy and magnetic measurements. The X-ray diffraction (XRD) investigation revealed the presence of a crystalline phase for samples with x ≥ 3 mol%, namely that of Ce1.88Pb2.12O6.53. The structural role of germanium, lead and cerium ions was discussed. The presence of the CeO4, GeO4, GeO6 and PbO4 structural units was evidenced by FT-IR spectrocopy in the studied glasses and glass ceramics. It was shown that the ratio of the mentioned structural units depends on the CeO2 content of the xCeO2(100 - x)[GeO2.PbO] system. As a part of an on-going investigation of the physical properties of xCeO2(100 - x)[GeO2.PbO] glass ceramics, the magnetic behavior of this system was studied. The fractions of the cerium ions in the 3+ and 4+ valence states were determined.

  14. Crystallization and dielectric properties of lead-free glass-ceramic composites with Gd_2O_3 addition

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Lead-free glass-ceramic composites in barium sodium niobate silica system with Gd2O3 addition were synthesized through melt-casting fol-lowed by controlled crystallization technique. Crystallization and dielectric properties of the Gd2O3 adding glass-ceramic composites were investigated. With the increase in the concentration of Gd2O3, the glass transition temperature and the crystallization temperature of the pre-cursor glass shift towards the higher temperature. The crystallization behavior that occurred ...

  15. Microstructural and Wear Behavior Characterization of Porous Layers Produced by Pulsed Laser Irradiation in Glass-Ceramics Substrates

    Directory of Open Access Journals (Sweden)

    Jose I. Peña

    2013-09-01

    Full Text Available In this work, wear behavior and microstructural characterization of porous layers produced in glass-ceramic substrates by pulsed laser irradiation in the nanosecond range are studied under unidirectional sliding conditions against AISI316 and corundum counterbodies. Depending on the optical configuration of the laser beam and on the working parameters, the local temperature and pressure applied over the interaction zone can generate a porous glass-ceramic layer. Material transference from the ball to the porous glass-ceramic layer was observed in the wear tests carried out against the AISI316 ball counterface whereas, in the case of the corundum ball, the wear volume loss was concentrated in the porous layer. Wear rate and friction coefficient presented higher values than expected for dense glass-ceramics.

  16. Microstructural characterization of glass and ceramic simulated waste forms

    International Nuclear Information System (INIS)

    The microstructures of three nonradioactive glass samples simulating three Hanford process waste forms were characterized. Two samples of iodine sodalite which simulate the fixation of radioactive iodine were also characterized. X-ray diffraction, electron microscopy + x-ray energy dispersive spectrometry, and electron microprobe analysis were used in the characterization

  17. Effect of ZnO on phase emergence, microstructure and surface modifications of calcium phosphosilicate glass/glass-ceramics having iron oxide

    International Nuclear Information System (INIS)

    The effect of ZnO on phase emergence and microstructure properties of glass and glass-ceramics with composition 25SiO2-50CaO-15P2O5-(10 - x)Fe2O3-xZnO (where x = 0, 2, 5, 7 mol%) has been studied. They have been characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Surface modifications of these glass-ceramics in simulated body fluid have been studied using Fourier transform infrared reflection spectroscopy (FTIR), XPS and SEM. Results have shown a decrease in the fraction of non-bridging oxygen with increase in zinc oxide content. Emergence of crystalline phases in glass-ceramics at different heat treatment temperatures was studied using XRD. When glass is heat treated at 800 deg. C calcium phosphate, hematite and magnetite are developed as major phases in the glass-ceramics samples with ZnO up to 5 mol%. In addition to these, calcium silicate (Ca3Si2O7) phase is also observed when glass is heat treated at 1000 deg. C. The microstructure of the glass-ceramics heat treated at 800 deg. C exhibits the formation of nano-size (40-50 nm) grains. On heat treatment at 1000 deg. C crystallites grow to above 50 nm size and more than one phase are observed in the microstructure. The formation of thin flake-like structure with coarse particles is observed at high zinc oxide concentration (x = 7 mol%). In vitro studies have shown the surface modifications and formation of Ca-P-rich layer on the glass-ceramics when immersed in simulated body fluids (SBF) for different durations. The bioactive response was found to depend on ZnO content.

  18. Effect of Ti(+4) on in vitro bioactivity and antibacterial activity of silicate glass-ceramics.

    Science.gov (United States)

    Riaz, Madeeha; Zia, Rehana; Saleemi, Farhat; Hussain, Tousif; Bashir, Farooq; Ikhram, Hafeez

    2016-12-01

    A novel glass-ceramic series in (48-x) SiO2-36 CaO-4 P2O5-12 Na2O-xTiO2 (where x=0, 3.5, 7, 10.5 and 14mol %) system was synthesized by crystallization of glass powders, obtained by melt quenching technique. The differential scanning calorimetric analysis (DSC) was used to study the non-isothermal crystallization kinetics of the as prepared glasses. The crystallization behaviour of glasses was analyzed under non-isothermal conditions, and qualitative phase analysis of glass-ceramics was made by X-ray diffraction. The in vitro bioactivity of synthesized glass-ceramics was studied in stimulated body fluid at 37°C under static condition for 24days. The formation of hydroxyl-carbonated apatite layer; evident of bioactivity of the material, was elucidated by XRD, FTIR, AAS, SEM and EDX analysis. The result showed that partial substitution of TiO2 with SiO2 negatively influenced bioactivity; it decreased with increase in concentration of TiO2. As Ti(+4) having stronger field strength as compared to Si(+4) so its replacement became the cause for reduction in degradation that in turn improved the chemical stability. The compressive strength was also enhanced with progress addition of TiO2 in the system. The antibacterial properties were examined against Staphylococcus Epidermidis. Strong antibacterial efficacy was observed with the addition of TiO2 in the system. PMID:27612803

  19. Mapping of rare earth elements in nuclear waste glass-ceramic using micro laser-induced breakdown spectroscopy

    Science.gov (United States)

    Wang, X.; Motto-Ros, V.; Panczer, G.; De Ligny, D.; Yu, J.; Benoit, J. M.; Dussossoy, J. L.; Peuget, S.

    2013-09-01

    A micro-LIBS system was set up based on a quadruple Nd:YAG laser at 266 nm coupled with a microscope. Elemental mapping was performed on a Mo-rich glass-ceramic sample containing CaMoO4 crystallites hundreds of microns in length and about 25 μm in section diameter. The topography of single-shot laser-induced craters was characterized using an atomic force microscope (AFM), which revealed a crater size less than 7 μm. Mappings of Mo, Ca, Sr, Al, Fe, Zr and rare earth elements such as Eu, Nd, Pr and La were undertaken. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was conducted to validate the micro-LIBS analysis. Principal components analysis calculation was used to investigate the correlation of elements in the two phases of glass-ceramic. Correlation between Ca, Sr, rare earth elements and Mo indicates their preferential incorporation into the calcium molybdate crystalline phase. Anti-correlation between Fe, Zr, Al and Mo revealed their affinity to the glass phase.

  20. Cooperative Quantum Cutting of Nano-Crystalline BaF2:Tb3+, Yb3+ in Oxyfluoride Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    CHEN Jing-Xin; YE Song; WANG Xi; QIU Jian-Rong

    2008-01-01

    We report on cooperative quantum cutting in Tb3+-Yb3+ codoped glass ceramics. Precipitation of BaF2 nano-crystals is confirmed by XRD and HRTEM analysis. Near-infrared emission due to transition of Yb3+ ions under 485nm excitation indicates cooperative energy transfer from Tb3+ to Yb3+. The quantum efficiency of this process reaches 145%. The realization of quantum cutting in glass ceramics may have promising applications in solar cells.

  1. High infrared radiance glass-ceramics obtained from fly ash and titanium slag.

    Science.gov (United States)

    Wang, Shuming; Liang, Kaiming

    2007-11-01

    A new glass-ceramic was synthesized by crystal growth from a homogenous glass obtained by melting a mixture of fly ash collected from a power plant in Hebei province of China, titanium slag collected from a titanium factory in Sichuan province of China, and MgCO(3) as an additive. According to the measurement results of differential thermal analysis, a thermal treatment of nucleating at 850 degrees C for 2h and crystallizing at 985 degrees C for 1.5h was used to obtain the crystallized glass. X-ray diffraction and scanning electron microscopy measurements showed that the main crystalline phase of this material was iron-ion substituted cordierite, (Mg,Fe)(2)Al(4)Si(5)O(18), which is homogeneously dispersed within the parent glass matrix. The infrared radiance and thermal expansion coefficient of this material have been examined, and the results demonstrate that this glass-ceramic material has potential for application in a wide range of infrared heating and drying materials. PMID:17640707

  2. Influence of local phonon energy on quantum efficiency of Tb3+-Yb3+co-doped glass ceramics containing fluoride nanocrystals

    Institute of Scientific and Technical Information of China (English)

    王慧云; 叶松; 刘天华; 李松; 胡荣璇; 王德平

    2015-01-01

    The Tb3+single-doped and Tb3+-Yb3+co-doped glass ceramics with the precipitation of CaF2, CaF2-SrF2 solid state solu-tion and SrF2 nanocrystals were designed and prepared by taking different amounts of CaF2 and SrF2 as the starting fluorides to inves-tigate the influence of the crystalline phase on the total quantum efficiency. The formation of the fluoride nanocrystals and the incor-poration of the doped rare earth ions into the fluoride nanocrystals were proved by the XRD measurement. The energy transfer from Tb3+to Yb3+was studied by the steady and time resolved spectra. The total internal quantum efficiencies were calculated based on the measured Tb3+lifetime, which was about 10.5%improved in the SrF2 nanocrystals precipitated glass ceramics compared with that in the CaF2 nanocrystals precipitated glass ceramics mainly due to the lower phonon energy environment. Meanwhile, the total external quantum efficiencies were evaluated with the integrating sphere measurement system, which were 18.6%, 19.3%and 24.4%, respec-tively, for the CaF2, CaF2-SrF2 and SrF2 nanocrystals precipitated glass ceramics. Additionally, obvious difference between the calcu-lated total internal quantum efficiency and the measured total external quantum efficiency was also discussed.

  3. A method for developing design diagrams for ceramic and glass materials using fatigue data

    Science.gov (United States)

    Heslin, T. M.; Magida, M. B.; Forrest, K. A.

    1986-01-01

    The service lifetime of glass and ceramic materials can be expressed as a plot of time-to-failure versus applied stress whose plot is parametric in percent probability of failure. This type of plot is called a design diagram. Confidence interval estimates for such plots depend on the type of test that is used to generate the data, on assumptions made concerning the statistical distribution of the test results, and on the type of analysis used. This report outlines the development of design diagrams for glass and ceramic materials in engineering terms using static or dynamic fatigue tests, assuming either no particular statistical distribution of test results or a Weibull distribution and using either median value or homologous ratio analysis of the test results.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Byung-Gil; Park, Hwan-Seo; Kim, Hwan-Young; Kim, In-Tae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-05-15

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

  5. Structural investigations on Eu-doped fluorobromozirconate glass ceramics.

    Energy Technology Data Exchange (ETDEWEB)

    Wiegand, Marie-Christin [Department of Physics, University of Paderborn, Warburger Str. 100, 33100 Paderborn (Germany); Ahrens, Bernd [Fraunhofer Center for Silicon Photovoltaics, Walter-Huelse-Str. 1, 06120 Halle (Saale) (Germany); Henke, Bastian; Schweizer, Stefan [Fraunhofer Center for Silicon Photovoltaics, Walter-Huelse-Str. 1, 06120 Halle (Saale) (Germany); Centre for Innovation Competence SiLi-nano, Martin Luther University of Halle-Wittenberg, Halle (Saale) (Germany)

    2011-07-01

    Modified Eu-doped fluorozirconate glasses are regarded as promising materials for photovoltaic and medical applications. In these glasses, a substantial fraction of the fluorine ions was replaced by bromine ions resulting in the formation of BaBr{sub 2} nanocrystals upon subsequent thermal treatment of the as-made glass. Interestingly, the metastable hexagonal phase of BaBr{sub 2} is always formed first before further annealing leads to the formation of orthorhombic phase BaBr{sub 2}, i.e., a phase transition from hexagonal to orthorhombic phase BaBr{sub 2} occurs upon annealing. During the annealing a part of the doped Eu{sup 2+} is incorporated into the BaBr{sub 2} nanocrystals enabling fluorescent transitions of Eu{sup 2+} in hexagonal and orthorhombic BaBr{sub 2}, respectively, upon ultraviolet excitation. The nanocrystal size and the structural phase depend on the addition of InF{sub 3} and YF{sub 3} and on the Br/(F+Br)-ratio, which was investigated by differential scanning calorimetry and x-ray diffraction. In addition, photoluminescence experiments were performed to monitor the phase transition by optical means.

  6. Cubic to tetragonal phase transition of Tm3+ doped nanocrystals in oxyfluoride glass ceramics

    OpenAIRE

    Yiming Li; Lijuan Zhao; Yuting Fu; Yahui Shi; Xiaoyu Zhang; Hua Yu

    2016-01-01

    Tm3+ ions doped β-PbF2 nanocrystals in oxyfluoride glass ceramics with different doping concentrations and thermal temperatures are prepared by a traditional melt-quenching and thermal treatment method to investigate the structure and the phase transition of Tm3+ doped nanocrystals. The structures are characterized by X-ray diffraction Rietveld analysis and confirmed with numerical simulation. The phase transitions are proved further by the emission spectra. Both of the doping concentration a...

  7. Primary Research of MSCs on AW Glass Ceramic with Different Surface Roughness

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    1 IntroductionTissue engineering can be defined as the use of composite of cells and materials to promote a replace new tissue formation. The surface topography of the composite including surface texture and surface roughness, can directly influence cellular adsorb, attachment, proliferation differentiation and migradtion. Roughened surfaces were achieved through processes such as machining, particle blasting, chemical/electrochemical etching.Apatite-wallastonite glass-ceramic(AW GC) was developed in 1982 b...

  8. Erbium environment in glass-ceramics investigated by atom probe tomography

    OpenAIRE

    Blanc, Wilfried; François Saint-Cyr, Hugues; Martin, Isabelle,; Le Coustumer, Philippe; Hombourger, Chystel; Neuville, D. R.; Larson, D.J.; Prosa, T.J.; Guillermier, Christelle

    2014-01-01

    Glass-ceramics (considered here as a glassy host containing crystalline or amorphous nanoparticles) are of interest for luminescent properties as they can combine the sturdiness and low cost of a matrix host with particular spectroscopic behavior that would not appear in this host [1]. Ideally, nanoparticles would fully encapsulate luminescent ions to produce engineered spectroscopic properties. This approach is particularly promising for optical fibers. Indeed, silica is the most common glas...

  9. Use of vitrified urban incinerator waste as raw material for production of sintered glass-ceramics

    OpenAIRE

    Romero, Maximina; Rincón López, Jesús María; Rawlings, Rees D.; Boccaccini, A. R.

    2001-01-01

    The crystallisation behaviour of vitrified industrial waste (fly ash from domiciliary solid waste incineration) was examined by differential thermal analysis, X-ray diffractometry and scanning electron microscopy. It was demonstrated that powder processing route was required to transform the vitrified industrial waste into glass-ceramics products. Time-Temperature-Transformation (TTT) diagrams were drawn for the two main crystalline phases, diopside and wollastonite. The wollastonite existed...

  10. Effects of surface treatments on bond strength of glass-infiltrated ceramic.

    Science.gov (United States)

    Lu, Y C; Tseng, H; Shih, Y H; Lee, S Y

    2001-09-01

    The purpose of this study was to evaluate the effects of various surface treatments on the bond strength at the In-Ceram/resin composite interface. Ninety-eight In-Ceram specimens were divided into seven groups and exposed to various surface treatments as follows: (A) control (B) saliva contamination (C) saliva contamination plus aluminum oxide sandblasting (D) glove powder contamination (E) glove powder contamination plus aluminum oxide sandblasting (F) rough aluminum oxide sandblasting and (G) excess glass infiltration. A resin composite cylinder was cemented to each In-Ceram specimen with Panavia 21 resin luting cement. Half of the cemented specimens in each group were stored in water for 24 h, and the other half were stored in water for 2 weeks and then were thermo-cycled for 2000 cycles. Shear bond strengths (SBS) of seven specimens in each subgroup were determined and analysed using analysis of variance (ANOVA) and Tukey HSD test as well as Student's t-test. Scanning electronic microscopy was used to identify the type of bond failure. Shear bond strength was significantly decreased by saliva and glove powder contaminations (P contaminated specimens. However, the glove powder plus sandblasting group showed no significant difference in SBS compared with the control group. There was no significant difference in SBS between the excess glass-infiltrating group and the control group. The SBS was significantly decreased by rough aluminum oxide sandblasting (P contaminants may significantly influence the bond strength of In-Ceram restorative in clinical use. PMID:11580818

  11. Crack propagation and the material removal mechanism of glass-ceramics by the scratch test.

    Science.gov (United States)

    Qiu, Zhongjun; Liu, Congcong; Wang, Haorong; Yang, Xue; Fang, Fengzhou; Tang, Junjie

    2016-12-01

    To eliminate the negative effects of surface flaws and subsurface damage of glass-ceramics on clinical effectiveness, crack propagation and the material removal mechanism of glass-ceramics were studied by single and double scratch experiments conducted using an ultra-precision machine. A self-manufactured pyramid shaped single-grit tool with a small tip radius was used as the scratch tool. The surface and subsurface crack propagations and interactions, surface morphology and material removal mechanism were investigated. The experimental results showed that the propagation of lateral cracks to the surface and the interaction between the lateral cracks and radial cracks are the two main types of material peeling, and the increase of the scratch depth increases the propagation angle of the radial cracks and the interaction between the cracks. In the case of a double scratch, the propagation of lateral cracks and radial cracks between paired scratches results in material peeling. The interaction between adjacent scratches depends on the scratch depth and separation distance. There is a critical separation distance where the normalized material removal volume reaches its peak. These findings can help reduce surface flaws and subsurface damage induced by the grinding process and improve the clinical effectiveness of glass-ceramics used as biological substitute and repair materials.

  12. Experimental Study on Layered Ice Bonded Abrasive Polishing of Glass-ceramics

    Directory of Open Access Journals (Sweden)

    Yuli SUN

    2014-12-01

    Full Text Available Layered ice bonded abrasive tools (LIBAT is a new kind of one which not only has the ability of lapping and polishing but also has the effect of self-dressing. In this paper, two kinds of layered ice bonded abrasive tools were designed and manufactured. Experimental studies on layered ice bonded abrasive (LIBA polishing of glass-ceramics were conducted. The results show that the surface topography of glass-ceramics polished by micro α-Al2O3-nano α-Al2O3 LIBAT is better than that of polished by micro α-Al2O3-nano SiO2 LIBAT. The surface roughness Sa of glass-ceramics polished by the two kinds of LIBAT is at the nanometer scale. The reasons of this phenomenon were analyzed. The experimental results illustrate that the LIBAT shows good effect and can be used in production practice. DOI: http://dx.doi.org/10.5755/j01.ms.20.4.6149

  13. XRD and FTIR structural investigation of gadolinium-zinc-borate glass ceramics

    Science.gov (United States)

    Borodi, G.; Pascuta, P.; Stefan, R.; Dan, V.; Pop, V.; Radulescu, D.

    2013-11-01

    X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements have been employed to investigate the (Gd2O3)xṡ(B2O3)(60-x)ṡ(ZnO)40 glass ceramics system, with 0 ≤ x ≤ 15 mol%. After heat treatment applied at 860 °C for 2 h, some structural changes were observed and new crystalline phases appeared in the structure of the samples. In these glass ceramics four crystalline phases were identified using powder diffraction files (PDF 2), namely ZnB4O7, Zn4O(B6O12), Zn3(BO3)2 and GdBO3. From the XRD data, the average unit-cell parameter and the quantitative ratio of the crystallographic phases in the studied samples were evaluated. FTIR data revealed that the BO3, BO4 and ZnO4 are the main structural units of these glass ceramics network. The compositional dependence of the different structural units which appear in the studied samples was followed.

  14. XRD and FTIR structural investigation of gadolinium-zinc-borate glass ceramics

    International Nuclear Information System (INIS)

    X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements have been employed to investigate the (Gd2O3)x⋅(B2O3)(60−x)⋅(ZnO)40 glass ceramics system, with 0 ≤ x ≤ 15 mol%. After heat treatment applied at 860 °C for 2 h, some structural changes were observed and new crystalline phases appeared in the structure of the samples. In these glass ceramics four crystalline phases were identified using powder diffraction files (PDF 2), namely ZnB4O7, Zn4O(B6O12), Zn3(BO3)2 and GdBO3. From the XRD data, the average unit-cell parameter and the quantitative ratio of the crystallographic phases in the studied samples were evaluated. FTIR data revealed that the BO3, BO4 and ZnO4 are the main structural units of these glass ceramics network. The compositional dependence of the different structural units which appear in the studied samples was followed

  15. XRD and FTIR structural investigation of gadolinium-zinc-borate glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Borodi, G. [National Institute for Research and Development of Isotopic and Molecular Technologies, 65-103 Donath, 400293 Cluj-Napoca (Romania); Pascuta, P.; Dan, V.; Pop, V. [Technical University, 28 Memorandumului, 400114 Cluj-Napoca (Romania); Stefan, R. [Agricultural Science and Veterinary Medicine University, 3-5 Calea Manastur, 400372 Cluj-Napoca (Romania); Radulescu, D. [University of Medicine and Pharmacy Iuliu Hatieganu, 8 Victor Babes, 400012 Cluj-Napoca (Romania)

    2013-11-13

    X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy measurements have been employed to investigate the (Gd{sub 2}O{sub 3}){sub x}⋅(B{sub 2}O{sub 3}){sub (60−x)}⋅(ZnO){sub 40} glass ceramics system, with 0 ≤ x ≤ 15 mol%. After heat treatment applied at 860 °C for 2 h, some structural changes were observed and new crystalline phases appeared in the structure of the samples. In these glass ceramics four crystalline phases were identified using powder diffraction files (PDF 2), namely ZnB{sub 4}O{sub 7}, Zn{sub 4}O(B{sub 6}O{sub 12}), Zn{sub 3}(BO{sub 3}){sub 2} and GdBO{sub 3}. From the XRD data, the average unit-cell parameter and the quantitative ratio of the crystallographic phases in the studied samples were evaluated. FTIR data revealed that the BO{sub 3}, BO{sub 4} and ZnO{sub 4} are the main structural units of these glass ceramics network. The compositional dependence of the different structural units which appear in the studied samples was followed.

  16. Magnetic glass ceramics for sustained 5-fluorouracil delivery: characterization and evaluation of drug release kinetics.

    Science.gov (United States)

    Abdel-Hameed, S A M; El-Kady, A M; Marzouk, M A

    2014-11-01

    In the present study, magnetic glass ceramics in the system Fe2O3 ∙ TiO2 ∙ P2O5 ∙ SiO2 ∙ MO (M=Mg, Ca, Mn, Cu, Zn or Ce) are prepared. The effect of adding different cations on the thermal behavior, developed phases, microstructure and magnetic properties is studied using differental thermal analysis (DTA), X-ray diffraction analysis (XRD), transmission electron microscope (TEM), FT-infrared transmission (FT-IR) and vibrating sample magnetometer (VSM) respectively. The magnetic glass ceramics are tested as delivery systems for 5-fluorouracil. Modeling and analysis of release kinetics are addressed. The application of Higuchi square root of time model and the first order release model indicated that, 5-FU is released by diffusion controlled mechanisms, and that its released rate depends greatly on the concentration of loaded drug during the loading stage. The obtained results suggested that, the prepared magnetic glass ceramics can be used for cancer treatment by hyperthermia and/or by localized delivery of therapeutic doses of 5-fluorouracil.

  17. Flexural Strength of Preheated Resin Composites and Bonding Properties to Glass-Ceramic and Dentin

    Directory of Open Access Journals (Sweden)

    Matthias Richard Kramer

    2016-01-01

    Full Text Available To test the impact of preheating (25, 37, 54, or 68 °C of TetricEvoCeram (TEC, FiltekSupremeXT (FSXT, and Venus (V on flexural strength (FS, shear bond strength (SBS and interfacial tension (IFT. FS was tested with TEC and FSXT. For SBS, glass-ceramic and human dentin substrate were fabricated and luted with the preheated resin composite (RC. SBSs of 1500 thermal cycled specimens were measured. For IFT, glass slides covered with the non-polymerized RC were prepared and contact angles were measured. Data were analyzed using 2/1-way ANOVA with Scheffé-test, and t-test (p < 0.05. Preheated TEC (37–68 °C showed higher FS compared to the control-group (25 °C (p < 0.001. FSXT presented higher FS than TEC (p < 0.001. For SBS to dentin higher values for FSXT than TEC were found. The preheating temperature showed no impact on SBS to dentin. SBS to glass-ceramic revealed a positive influence of temperature for TEC 25–68 °C (p = 0.015. TEC showed higher values than V and FSXT (p < 0.001. IFT values increased with the preheating temperature. A significant difference could be observed in every RC group between 25 and 68 °C (p < 0.001.

  18. Bioactivity of Sodium Free Fluoride Containing Glasses and Glass-Ceramics

    Directory of Open Access Journals (Sweden)

    Xiaojing Chen

    2014-07-01

    Full Text Available The bioactivity of a series of fluoride-containing sodium-free calcium and strontium phosphosilicate glasses has been tested in vitro. Glasses with high fluoride content were partially crystallised to apatite and other fluoride-containing phases. The bioactivity study was carried out in Tris and SBF buffers, and apatite formation was monitored by XRD, FTIR and solid state NMR. Ion release in solutions has been measured using ICP-OES and fluoride-ion selective electrode. The results show that glasses with low amounts of fluoride that were initially amorphous degraded rapidly in Tris buffer and formed apatite as early as 3 h after immersion. The apatite was identified as fluorapatite by 19F MAS-NMR after 6 h of immersion. Glass degradation and apatite formation was significantly slower in SBF solution compared to Tris. On immersion of the partially crystallised glasses, the fraction of apatite increased at 3 h compared to the amount of apatite prior to the treatment. Thus, partial crystallisation of the glasses has not affected bioactivity significantly. Fast dissolution of the amorphous phase was also indicated. There was no difference in kinetics between Tris and SBF studies when the glass was partially crystallised to apatite before immersion. Two different mechanisms of apatite formation for amorphous or partially crystallised glasses are discussed.

  19. Modeling of water absorption induced cracks in resin-based composite supported ceramic layer structures.

    Science.gov (United States)

    Huang, Min; Thompson, V P; Rekow, E D; Soboyejo, W O

    2008-01-01

    Cracking patterns in the top ceramic layers of the modeled dental multilayers with polymer foundation are observed when they are immersed in water. This article developed a model to understand this cracking mechanism. When water diffuses into the polymer foundation of dental restorations, the foundation will expand; as a result, the stress will build up in the top ceramic layer because of the bending and stretching. A finite element model based on this mechanism is built to predict the stress build-up and the slow crack growth in the top ceramic layers during the water absorption. Our simulations show that the stress build-up by this mechanism is high enough to cause the cracking in the top ceramic layers and the cracking patterns predicted by our model are well consistent with those observed in experiments on glass/epoxy/polymer multilayers. The model is then used to discuss the life prediction of different dental ceramics. PMID:17497681

  20. Effect of Heat Treatment Conditions on Properties of Lead-Free Bi2GeO5 Ferroelectric Glass Ceramics

    International Nuclear Information System (INIS)

    Nowadays, lead-free ferroelectric materials have attracted much interest among materials scientists as a result of environmental concern. The bismuth germanate (Bi2GeO5) phase, one of the lead-free ferroelectric crystals, is of particular interest as its composition already contains good glass former (GeO2) and can be prepared by an alternative glass ceramic route. In this work, the conventional melt-quenching method was used to produce the parent glass with composition of 60 mol% BiO1.5:20 mol% GeO2:20 mol% BO1.5. The as-received glass pieces were subjected to the heat treatment schedule at various crystallization temperatures and dwell-times. The glass and glass ceramics samples were then investigated by XRD, Raman spectroscopy and their dielectric properties were also measured. The XRD and Raman spectroscopy showed that the crystallinity of the prepared glass ceramics depended very much on crystallization temperature and dwell-time. The larger dielectric constant and lower dielectric loss were obtained as crystallinity of the glass ceramics enhanced. The highest dielectric constant (εr) was found at 77 with a low dielectric loss of about 0.005.

  1. Structural analysis of Fe–Mn–O nanoparticles in glass ceramics by small angle scattering

    Energy Technology Data Exchange (ETDEWEB)

    Raghuwanshi, Vikram Singh, E-mail: vikram.raghuwanshi@helmholtz-berlin.de [Helmholtz Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, D-14109 Berlin (Germany); Harizanova, Ruzha [University of Chemical Technology and Metallurgy, 8 Kl. Ohridski Blvd, 1756 Sofia (Bulgaria); Tatchev, Dragomir [Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev Str. Bl. 11, 1113 Sofia (Bulgaria); Hoell, Armin [Helmholtz Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, D-14109 Berlin (Germany); Rüssel, Christian [Friedrich Schiller University, Fraunhoferstr. 6, 07743 Jena (Germany)

    2015-02-15

    Magnetic nanocrystals containing Fe and Mn were obtained by annealing of silicate glasses with the composition 13.6Na{sub 2}O–62.9SiO{sub 2}–8.5MnO–15.0Fe{sub 2}O{sub 3−x} (mol%) at 580 °C for different periods of time. Here, we present Small Angle Neutron Scattering using Polarized neutrons (SANSPOL) and Anomalous Small Angle X-ray Scattering (ASAXS) investigation on these glass ceramic samples. Analysis of scattering data from both methods reveals the formation of spherical core–shell type of nanoparticles with mean sizes between 10 nm and 100 nm. ASAXS investigation shows the particles have higher concentration of iron atoms and the shell like region surrounding the particles is enriched in SiO{sub 2}. SANSPOL investigation shows the particles are found to be magnetic and are surrounded by a non-magnetic shell-like region. - Graphical abstract: Magnetic spherical core–shell nanoparticles in glass ceramics: SANSPOL and ASAXS investigations. - Highlights: • Formation and growth mechanisms of magnetic nanoparticles in silicate glass. • SANSPOL and ASAXS methods employed to evaluate quantitative information. • Analyses showed formation of nanoparticles with spherical core–shell structures. • Core of the particle is magnetic and surrounded by weak magnetic shell like region.

  2. Improved densification and properties of pressureless-sintered lithium disilicate glass-ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Ting; Qin, Yi; Wang, Bo, E-mail: wangbo_1@mail.xjtu.edu.cn; Yang, Jian-Feng, E-mail: yang155@mail.xjtu.edu.cn

    2015-01-03

    Lithium disilicate glass-ceramics were pressureless sintered with glass powders derived from the SiO{sub 2}–Li{sub 2}O–P{sub 2}O{sub 5}–ZrO{sub 2}–Al{sub 2}O{sub 3}–K{sub 2}O–CeO{sub 2} system. The effects of sintering temperature near the melting point of Li{sub 2}Si{sub 2}O{sub 5} crystalline phases and particle size on the sintering behavior, microstructure, flexural strength and translucency of the Li{sub 2}Si{sub 2}O{sub 5} glass-ceramics were studied. The specimens obtained from the coarse-glass powder with particle size of 50 μm (S50) presented much higher relative density, improved flexural strength and translucency. Melting of Li{sub 2}Si{sub 2}O{sub 5} crystals and crystallization of the melted liquids took place in the sintering temperature range. The melting increased the relative density while it decreased the crystallinity. The crystallization of the melted liquids played an opposite role. Due to the proper crystals size, crystallinity (70.47±3.02%) and higher relative density (97.68±0.22%), good flexural strength (282±14 MPa) and comparable translucency as the commercially used Emax{sup ®} materials were achieved for the S50 specimens sintered at 910 °C.

  3. Formation of nanostructures in Eu3+ doped glass-ceramics: an XAS study

    Science.gov (United States)

    Pellicer-Porres, J.; Segura, A.; Martínez-Criado, G.; Rodríguez-Mendoza, U. R.; Lavín, V.

    2013-01-01

    We describe the results of x-ray absorption experiments carried out to deduce structural and chemical information in Eu3+ doped, transparent, oxyfluoride glass and nanostructured glass-ceramic samples. The spectra were measured at the Pb and Eu-LIII edges. The Eu environment in the glass samples is observed to be similar to that of EuF3. Complementary x-ray diffraction experiments show that thermal annealing creates β-PbF2 type nanocrystals. X-ray absorption indicates that Eu ions act as seeds in the nanocrystal formation. There is evidence of interstitial fluorine atoms around Eu ions as well as Eu dimers. X-ray absorption at the Pb-LIII edge shows that after the thermal treatment most lead atoms form a PbO amorphous phase and that only 10% of the lead atoms remain available to form β-PbF2 type nanocrystals. Both x-ray diffraction and absorption point to a high Eu content in the nanocrystals. Our study suggests new approaches to the oxyfluoride glass-ceramic synthesis in order to further improve their properties.

  4. Structural and magnetic properties of glass-ceramics containing silver and iron oxide

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, K., E-mail: ksharma_iit@yahoo.co.in [Glass and Advanced Ceramics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Meena, Sher Singh [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Saxena, Sudhanshu [Food Technology Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Yusuf, S.M. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Srinivasan, A. [Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039 (India); Kothiyal, G.P., E-mail: gpkoth@barc.gov.in [Glass and Advanced Ceramics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer The particles of 20-30 nm size are obtained in glassy matrix. Black-Right-Pointing-Pointer Relaxation of magnetic particles is observed. Black-Right-Pointing-Pointer Magnetic properties are improved by Ag addition. Black-Right-Pointing-Pointer Materials show silver release and antibacterial activity against E. coli. - Abstract: Glass-ceramics with a nominal composition of 25SiO{sub 2}-(50 - x)CaO-15P{sub 2}O{sub 5}-8Fe{sub 2}O{sub 3}-2ZnO-xAg (where x = 0, 2 and 4 mol%) have been prepared. Structural features of glass-ceramics have been investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques. Magnetic properties were studied using vibrating sample magnetometer and Moessbauer spectroscopy. Ca{sub 3}(PO{sub 4}){sub 2}, hematite and magnetite are formed as major crystalline phases. The microstructure reveals the formation of 25-30 nm size particles. Moessbauer spectroscopy has shown the relaxation of magnetic particles. Saturation magnetization value is increased with an increase of Ag content up to 4 mol%, which has been attributed to the formation of magnetically ordered particles. The antibacterial response was found to depend on Ag ions concentration in the glass matrix and samples with 4 mol% Ag in glass matrix have shown effective antibacterial activity against Escherichia coli.

  5. Development of Glass and Ceramic Matrices for the Immobilization of High-level Radioactive Waste from Fast Reactors

    Energy Technology Data Exchange (ETDEWEB)

    Govindan Kutty, K.V.; Kitheri, Joseph; Asuvathraman, R.; Raja Madhavan, R.; Vasudeva Rao, P.R.; Baldev, Raj [Liquid Metals And Structural Chemistry Division, Indira Gandhi Centre For Atomic Research - IGCAR, Kalpakkam, Tamil Nadu 603 102 (India)

    2009-06-15

    Borosilicate glass is a favoured matrix worldwide for the immobilization of high-level waste (HLW). The HLW from the reprocessing of fast reactor fuels contains higher concentrations of actinide elements and noble metals than that from thermal reactors. These elements have poor solubility in borosilicate glass, leading to phase segregation and consequent loss of chemical durability. Alternate glass and crystalline ceramic matrices thus need to be developed for the long-term disposal of fast reactor HLW. In this context, we have undertaken work on simulated waste forms based on three different systems, viz., iron phosphate glass (IPG), SYNROC, and monazites. IPG is known to be a versatile host matrix for radioactive wastes. An IPG waste form with 20 wt% simulated HLW expected from the FBTR after a burnup of 150 GWD/T, was found to form readily at 1323 K in air. The glass transition temperature of the waste-loaded glass was found to be similar to that of bare IPG. The ease of glass formation and favourable physico-chemical properties make IPG a candidate matrix for fixing radioactive wastes of fast reactor origin. Among the crystalline ceramic matrices for HLW immobilization, SYNROC is a well known system. The flexibility of the conventional titanate phase assemblage to incorporate fast reactor wastes was investigated. SYNROC precursor powders were synthesized using an inexpensive nano-anatase reagent as the main ingredient. High-density simulated waste forms were then fabricated by hot pressing or hot isostatic pressing at 1373-1473 K. Monoliths of near-theoretical density were obtained, and thermophysical and chemical durability measurements were carried out on them. In contrast to the poly-phase SYNROC, monazite is known to be a single-phase orthophosphate waste form. Monazite (CePO{sub 4}) can accommodate widely different elements in its crystal structure due to the irregular oxygen coordination around the metal ions. The phase can be formed at low temperatures

  6. Infrared-to-green upconversion luminescence and mechanism of Ho3+, Nd3+ and Yb3+ ions in oxyfluoride glass ceramics

    Institute of Scientific and Technical Information of China (English)

    Zhang Jun-Jie; Kawamoto Yoji; Dai Shi-Xun

    2004-01-01

    New oxyfluoride glasses and glass ceramics co-doped with Nd3+, Yb3+ and Ho3+ were prepared. The upconversion of infrared radiation into green fluorescence has been studied for Nd3+, Yb3+ and Ho3+ in the transparent oxyfluoride glass ceramics. At room temperature very strong green upconversion luminescence due to the Ho3+: (5F4, 5S2) →5I8transition under 800 nm excitation was observed in the glass ceramics. The intensity of the green upconversion luminescence in a 1mol% YbF3-containing glass ceramic was found to be about 120 times stronger than that in the precursor oxyfluoride glass. The reason for the highly efficient Ho3+ upconversion luminescence in the oxyfluoride glass ceramics is discussed. The upconversion mechanism is also investigated.

  7. Crystallization kinetics and spectroscopic investigations on Tb3+ and Yb3+ codoped glass ceramics containing CaF2 nanocrystals

    International Nuclear Information System (INIS)

    Transparent Tb3+ and Yb3+ codoped oxyfluoride glass ceramics containing CaF2 nanocrystals were prepared by melt quenching and subsequent heat treatment. Crystallization kinetics of CaF2 nanocrystals was investigated by differential scanning calorimetric method. The average apparent activation energy Ea of the crystallization was ∼498 kJ/mol. Moreover, the value of the Avrami exponent n was 1.01. These results suggest that the crystallization mechanism of CaF2 is a diffusion controlled growth process of needles and plates of finite long dimensions. X-ray diffraction patterns and transmission electron microscopy image confirmed the CaF2 nanocrystals in the glass ceramic. Ultraviolet (UV) and visible emission spectra of the as-made glass and the glass ceramic with an excitation of a 974 nm laser diode were recorded at room temperature. An intense UV emission at 381 nm was observed in the glass ceramic. The origin of the enhancement of the emission at 381 nm was investigated using spectroscopic technique and Judd-Ofelt analysis. The enhancement of the emission at 381 nm could be attributed to the change of the ligand field of Tb3+ ions due to the incorporation of some Tb3+ and Yb3+ ions into CaF2 nanocrystals in the glass ceramic

  8. Progress in rare-earth-doped nanocrystalline glass-ceramics for laser cooling

    Science.gov (United States)

    Venkata Krishnaiah, Kummara; Ledemi, Yannick; Soares de Lima Filho, Elton; Loranger, Sebastien; Nemova, Galina; Messaddeq, Younes; Kashyap, Raman

    2016-03-01

    Laser cooling with anti-Stokes fluorescencewas predicted by Pringsheim in 1929, but for solids was only demonstrated in 1995. There are many difficulties which have hindered laser assisted cooling, principally the chemical purity of a sample and the availability of suitable hosts. Recent progress has seen the cooled temperature plummet to 93K in Yb:YLF. One of the challenges for laser cooling to become ubiquitous, is incorporating the rare-earthcooling ion in a more easily engineered material, rather than a pure crystalline host. Rare-earth-doped nanocrystalline glass-ceramics were first developed by Wang and Ohwaki for enhanced luminescence and mechanical properties compared to their parent glasses. Our work has focused on creating a nanocrystalline environment for the cooling ion, in an easy to engineer glass. The glasses with composition 30SiO2-15Al2O3-27CdF2-22PbF2-4YF3-2YbF3 (mol%), have been prepared by the conventional melt-quenching technique. By a simple post fabrication thermal treatment, the rare-earth ions are embedded in the crystalline phase within the glass matrix. Nanocrystals with various sizes and rare-earth concentrations have been fabricated and their photoluminescence properties assessed in detail. These materials show close to unity photoluminescence quantum yield (PLQY) when pumped above the band. However, they exhibit strong up-conversion into the blue, characteristic of Tm trace impurity whose presence was confirmed. The purification of the starting materials is underway to reduce the background loss to demonstrate laser cooling. Progress in the development of these nano-glass-ceramics and their experimental characterization will be discussed.

  9. Recent progress on upconversion luminescence enhancement in rare-earth doped transparent glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    邱建备; 焦清; 周大成; 杨正文

    2016-01-01

    The upconversion (UC) of the rare earth doped glass-ceramics has been extensively investigated due to their potential ap-plications in many fields, such as color display, high density memories, optical data storage, sensor and energy solar cell, etc. Many series of them, especially the oxyfluorides glasses containing Ba2LaF7 nanocrystals were studied in this review work, due to the ther-mal and mechanical toughness, high optical transmittance from the ultraviolet to the infrared regions, and a low nonlinear refractive index compared to the other commercial laser glasses. Moreover, the energy transfer (ET) between the rare earth ions and transition metals plays an important role in the upconversion process. The cooperative ET has been researched very activly in UC glasses due to applications in the fields of solar cells, such as in the Er/Yb, Tm/Yb, Tb/Yb, Tb/Er/Yb and Tm/Er/Yb couples. The present article re-views on the recent progress made on: (i) upconversion materials with fluoride microcrystals in glasses and the mechanisms involved, including the UC in double and tri-dopant RE ions activated fluoride microcrystal, energy transfer process; and (ii) the effect of the metal Mn and nanoparticles of Au, Ag, Cu on the enhancement of UC emissions. Discussions have also been made on materials, ma-terial synthesis, the structural and emission properties of glass-ceramics. Additionally, the conversion efficiency is still a challenge for the spectra conversion materials and application; challenge and future advances have also been demonstrated.

  10. Glasses and Glass-Ceramic Components from Inorganic Waste and Novel Processing

    OpenAIRE

    Ponsot, Inès

    2015-01-01

    Thanks to European environmental rules and regulations establishment, waste recycling has become a more and more relevant problematic. For manufacturing plants, especially those producing hazardous wastes, expenses linked to waste production have drastically increased over the last decades. In the proposed work, various hazardous and non-hazardous wastes, among: soda-lime and borosilicate glass cullet, cathode ray tubes glass, exhausted lime from fume abatement systems residues, sludge and sl...

  11. Bioactivity of Sodium Free Fluoride Containing Glasses and Glass-Ceramics

    OpenAIRE

    Xiaojing Chen; Xiaohui Chen; Brauer, Delia S.; Rory M. Wilson; Hill, Robert G.; Natalia Karpukhina

    2014-01-01

    The bioactivity of a series of fluoride-containing sodium-free calcium and strontium phosphosilicate glasses has been tested in vitro. Glasses with high fluoride content were partially crystallised to apatite and other fluoride-containing phases. The bioactivity study was carried out in Tris and SBF buffers, and apatite formation was monitored by XRD, FTIR and solid state NMR. Ion release in solutions has been measured using ICP-OES and fluoride-ion selective electrode. The results show that...

  12. Improving adhesion between luting cement and zirconia-based ceramic with an alternative surface treatment

    Directory of Open Access Journals (Sweden)

    Aurealice Rosa Maria MARTINS

    2015-01-01

    Full Text Available This study evaluated the influence of an alternative surface treatment on the microshear bond strength (μsbs of zirconia-based ceramic. Thirty-five zirconia disks were assigned to five groups according to the following treatments: Control (CO, glass and silane were not applied to the zirconia surface; G1, air blasted with 100μm glass beads + glaze + silane; G2, a gel containing 15% (by weight glass beads applied to the ceramic surface + glaze + silane; G3, a gel containing 25% (by weight glass beads applied to the ceramic surface + glaze + silane; and G4, a gel containing 50% (by weight glass beads applied to the ceramic surface + glaze + silane. The specimens were built up using RelyX ARC®, according to the manufacturer’s recommendations, and inserted in an elastomeric mold with an inner diameter of 0.8 mm. The μsbs test was performed using a testing machine at a crosshead speed of 0.5 mm/min. ANOVA and Tukey’s test (p < 0.05 were applied to the bond strength values (in MPa. CO (15.6 ± 4.1 showed the lowest μsbs value. There were no statistical differences between the G1 (24.9 ± 7.4, G2 (24.9 ± 2.3, G3 (35.0 ± 10.3 and G4 (35.3 ± 6.0 experimental groups. Those groups submitted to surface treatments with higher concentrations of glass showed a lower frequency of adhesive failures. In conclusion, the glass application improved the interaction between the ceramic and the luting cement.

  13. Stress Analysis of CaO-Al2O3-SiO2 System Glass-ceramic with Different Thickness

    Institute of Scientific and Technical Information of China (English)

    CHENG Jinshu; XIE Jun; HE Feng; YANG Shuzhen

    2005-01-01

    In order to study the relationship between thickness and residual stress in CaO-Al2O3-SiO2 glass-ceramics. The residual stress was measured in CaO-Al2 O3-SiO2 system glass-ceramic with different thickness, and the formation mechanism and characterization of residual stress in CAS system Glass-ceramic were analyzed by the X-ray diffraction analysis. The experimental results show the compressive residual stress increases with thickness of glass-ceramic increasing

  14. Mixed polaronic-ionic conduction in lithium borate glasses and glass-ceramics containing copper oxide

    Science.gov (United States)

    Khalil, M. M. I.

    2007-03-01

    The effect of electric field strength on conduction in lithium borate glasses doped with CuO with different concentration was studied and the value of the jump distance of charge carrier was calculated. The conductivity measurements indicate that the conduction is due to non-adiabatic hopping of polarons and the activation energies are found to be temperature and concentration dependent. Lithium borate glasses are subjected to carefully-programmed thermal treatments which cause the nucleation and growth of crystalline phases. X-ray diffraction analysis confirmed the amorphous nature for the investigated glass sample and the formation of crystalline phase for annealed samples at 650 °C. The main separated crystalline phase is Li2B8O13. The scanning electron micrographs of some selected glasses showed a significant change in the morphology of the films investigated due to heat treatment of the glass samples. It was found that the dc-conductivity decreases with an increase of the HT temperature. The decrease of dc conductivity, with an increase of the HT temperature, can be related to the decrease in the number of free ions in the glass matrix. There is deviation from linearity at high temperature regions in the logσ-1/T plots for all investigated doped samples at a certain temperature at which the transition from polaronic to ionic conduction occurs. The hopping of small polarons is dominant at low temperatures, whereas the hopping of Li+ ions dominates at high temperatures.

  15. Mixed polaronic-ionic conduction in lithium borate glasses and glass-ceramics containing copper oxide

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, M.M.I. [National Center for Radiation Research and Technology, Radiation Physics Department, Cairo (Egypt)

    2007-03-15

    The effect of electric field strength on conduction in lithium borate glasses doped with CuO with different concentration was studied and the value of the jump distance of charge carrier was calculated. The conductivity measurements indicate that the conduction is due to non-adiabatic hopping of polarons and the activation energies are found to be temperature and concentration dependent. Lithium borate glasses are subjected to carefully-programmed thermal treatments which cause the nucleation and growth of crystalline phases. X-ray diffraction analysis confirmed the amorphous nature for the investigated glass sample and the formation of crystalline phase for annealed samples at 650 C. The main separated crystalline phase is Li{sub 2}B{sub 8}O{sub 13}. The scanning electron micrographs of some selected glasses showed a significant change in the morphology of the films investigated due to heat treatment of the glass samples. It was found that the dc-conductivity decreases with an increase of the HT temperature. The decrease of dc conductivity, with an increase of the HT temperature, can be related to the decrease in the number of free ions in the glass matrix. There is deviation from linearity at high temperature regions in the log{sigma}-1/T plots for all investigated doped samples at a certain temperature at which the transition from polaronic to ionic conduction occurs. The hopping of small polarons is dominant at low temperatures, whereas the hopping of Li{sup +} ions dominates at high temperatures. (orig.)

  16. 锌硼玻璃基低温共烧陶瓷的微波介电性能研究%Microwave dielectric properties of zinc borate glass-based low temperature co-fired ceramics

    Institute of Scientific and Technical Information of China (English)

    周东祥; 孙荣光; 胡云香

    2011-01-01

    Zinc borate glass/ceramic composites for low temperature co-fired ceramics (LTCC) were prepared from the mixtures of zinc borate glass, Al203 and TiO2. The effects of the mass ratio of TiO2 to Al203 on the phase evolution and dielectric properties of prepared composites were investigated. The results show that the content of ZnAl2O4, TiO2 and 4ZnO · 3B203 in the composites increases, decreases,remains essentially unchanged respectively with the decrease of the mass ratio of TiO2 to Al203. The permittivity and dielectric loss of these composites increase significantly with the increase of the mass ratio of TiO2 to Al203. A near-zero temperature coefficient of resonant frequency of the composite is obtained when the mass fraction ofTiO2 is 8%.%采用3ZnO-2B2O3玻璃与Al2O3和TiO2复合烧结制备了锌硼玻璃基低温共烧陶瓷复合材料,研究了TiO2/Al2O3质量比对所制复合材料相组成和微波介电性能的影响.结果表明:随着TiO2/Al2O3质量比减少,复合材料中ZnAl2O4相含量增多,TiO2相含量减少,4ZnO·3B2O3相的含量基本不变.随着TiO2/Al2O3质量比增大,复合材料的介电常数和介质损耗增大.当TiO2的质量分数为8%时,复合材料的谐振频率温度系数接近于零.

  17. Microstructure and leach rates of apatite glass-ceramics as a host for Sr high-level liquid waste

    Science.gov (United States)

    He, Yong; Bao, Weimin; Song, Chongli

    2002-10-01

    An apatite glass-ceramic wasteform with 21 wt% SrO loading was fabricated for immobilizing Sr high-level liquid waste. The normalized leach rates of Sr, K, Mo, Al, P, Si are 6.9×10 -4, 1.09×10 -1, 2.7×10 -3, 3.22×10 -2, 2.84×10 -2, 3.26×10 -2 g/m 2 day, respectively. Component Fe in all leachates is not detectable in the 28-day static leaching test procedure in MCC-1. Instead of leaching, component Ca is adsorbed by testing samples. All the component Mo concentrates in the glass matrix of the well crystallized apatite glass-ceramics. For an apatite glass-ceramic wasteform, the optimum microstructure should be one in which poorly crystallized apatite crystallites distribute evenly in the glass phase. Perfect crystallization makes the crystal phase more stoichiometric and significantly changes the composition of the coexisting glass phase in the system, which, in our case, decreases the chemical stability of the apatite glass-ceramics.

  18. AFM Surface Roughness and Topography Analysis of Lithium Disilicate Glass Ceramic

    Directory of Open Access Journals (Sweden)

    M. Pantić

    2015-12-01

    Full Text Available The aim of this study is presenting AFM analysis of surface roughness of Lithium disilicate glass ceramic (IPS e.max CAD under different finishing procedure (techniques: polishing, glazing and grinding. Lithium disilicate glass ceramics is all-ceramic dental system which is characterized by high aesthetic quality and it can be freely said that properties of material provide all prosthetic requirements: function, biocompatibility and aesthetic. Experimental tests of surface roughness were investigated on 4 samples with dimensions: 18 mm length, 14 mm width and 12 mm height. Contact surfaces of three samples were treated with different finishing procedure (polishing, glazing and grinding, and the contact surface of the raw material is investigated as a fourth sample. Experimental measurements were done using the Atomic Force Microscopy (AFM of NT-MDT manufacturers, in the contact mode. All obtained results of different prepared samples are presented in the form of specific roughness parameters (Rа, Rz, Rmax, Rq and 3D surface topography.

  19. Luminescence property and phase-separation texture of phase-separated glasses and glass-ceramics in Mn-doped ZnO-SiO2 system

    International Nuclear Information System (INIS)

    In order to achieve fine phosphor materials with high efficiency, phase-separated glasses and glass-ceramics in Mn-doped ZnO-SiO2 system, of which composition was xZnO-(100-x) SiO2 mol% (x=10, 20, 30) in the immiscibility region, were prepared by melting and subsequent heat-treatment process. All the melt-quenched glasses were phase-separated into two phases, i.e. a ZnO-rich phase and a SiO2-rich one. The SiO2-rich particles were formed into the ZnO-rich phase in the composition of x=20 and x=30, while the ZnO-rich particles were formed in the SiO2-rich phase in the composition of x=10. The melt-quenched glass showed the orange-emission at around 625 nm of its peak wavelength. After the heat-treatment on the melt-quenched glasses, the Zn2SiO4 (willemite) phase were precipitated, and the glass-ceramics gave strong green-emission at around 525 nm. The intensity of the green-emission of the glass-ceramics in the composition of x=10 was higher than those in the composition of x=20 and x=30 in spite of the same amount of precipitated Zn2SiO4 phase. (author)

  20. Final report of experimental laboratory-scale brittle fracture studies of glasses and ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jardine, L.J.; Mecham, W.J.; Reedy, G.T.; Steindler, M.J.

    1982-10-01

    An experimental program was conducted to characterize the fragments generated when brittle glasses and ceramics are impacted. The direct application of the results is to radioactive waste forms for which the effects of accidental impacts must be known or predictable. Two major measurable experimental responses used for characterization of these effects are (1) the size distribution of the fragments, including the sizes that are respirable, and (2) the increase in surface area of the brittle test specimen. This report describes the glass and ceramic materials characterized, the procedures and techniques used for the characterization of size distributions and surface areas, and the results of the two key responses of the impact tests. Five alternative methods of determining size distributions were compared. Also examined were the effects of diametral and axial specimen impact configurations and the use of mechanical stops to eliminate secondary crushing during testing. Microscopic characterizations of Pyrex and SRL 131 simulated waste glass and SYNROC fragments were also performed. Preliminary correlations of impact energy with key size-distribution parameters, fragment surface areas, and respirable fines were proposed as useful for future verification and for use with modeling and scale-up studies of brittle fracture of larger realistic waste forms. The impact fragments of all specimens could be described by lognormal size distributions.

  1. Archaeometric investigation of medieval Bulgarian glasses and sgraffito ceramics by neutron activation analysis

    International Nuclear Information System (INIS)

    Instrumental neutron activation analysis was used to determine the content of Au, Ba, Ca, Ce, Cl, Cr, Co, Cs, Cu, Eu, Fe, Hf, La, Lu, Mn, Na, Rb, Sc, Sm, Sr, Ta, Tb, Th, Ti, U, Sb, V and Yb in glass samples excavated from medieval glassworkshops in Pliska and Preslav and in 20 glass finds from Preslav. Sgraffito ceramic samples excavated in Veliko Tarnovo were also analysed and the elements Al, As, Au, Ba, Br, Ce, Co, Cr, Cs, Dy, Eu, Fe, Hf, K, La, Lu, Mg, Mn, Na, Nd, Rb, Sb, Sc, Si, Sm, Ta, Tb, Th, Ti, U, V and Yb were determined. In order to localize the production site of the archaeological finds, the results from the analysis were subjected to cluster analysis, and stepwise discriminant analysis using the program package BMDP. A variety of the production of the medieval glass workshop in Preslav was identified and evaluated. It was proved that a part of the sgraffito ceramics samples have been produced in one and the same place and that the chemical composition might be successfully used to differentiate between the production of two workshops

  2. Photostimulated luminescence from a fluorobromozirconate glass-ceramic and the effect of crystallite size and phase

    CERN Document Server

    Secu, M; Spaeth, J M; Edgar, A; Williams, G V M; Rieser, U

    2003-01-01

    We report a systematic study of the photoluminescence (PL), photostimulated luminescence (PSL) and thermostimulated luminescence (TSL) from europium-and bromine-doped fluorozirconate glass-ceramics. Eu sup 2 sup + ions in the as-prepared glass show no PL, but after suitable thermal annealing hexagonal phase and orthorhombic phase barium bromide crystallites are precipitated and PL is observed from Eu sup 2 sup + ions in these crystallites. Room temperature PSL is observed from the orthorhombic phase, with an efficiency which is up to 9% of the well known crystalline storage phosphor BaFBr:Eu sup 2 sup +. The emission is at 404 nm, and there is a maximum in the stimulation at 580 nm. We associate the PSL with an optically quenchable peak in the glow curve, which has an activation energy of 1.20 eV and attribute this feature to a perturbed F centre. Room temperature PSL from glass-ceramics containing predominantly the hexagonal phase of BaBr sub 2 has a relative efficiency of less than 0.07%. The resultant trap...

  3. Treatment of copper industry waste and production of sintered glass-ceramic.

    Science.gov (United States)

    Coruh, Semra; Ergun, Osman Nuri; Cheng, Ta-Wui

    2006-06-01

    Copper waste is iron-rich hazardous waste containing heavy metals such as Cu, Zn, Co, Pb. The results of leaching tests show that the concentration of these elements exceeds the Turkish and EPA regulatory limits. Consequently, this waste cannot be disposed of in its present form and therefore requires treatment to stabilize it or make it inert prior to disposal. Vitrification was selected as the technology for the treatment of the toxic waste under investigation. During the vitrification process significant amounts of the toxic organic and inorganic chemical compounds could be destroyed, and at the same time, the metal species are immobilized as they become an integral part of the glass matrix. The copper flotation waste samples used in this research were obtained from the Black Sea Copper Works of Samsun, Turkey. The samples were vitrified after being mixed with other inorganic waste and materials. The copper flotation waste and their glass-ceramic products were characterized by X-ray analysis (XRD), scanning electron microscopy and by the toxicity characteristic leaching procedure test. The products showed very good chemical durability. The glass-ceramics fabricated at 850 degrees C/2 h have a large application potential especially as construction and building materials. PMID:16784166

  4. Structure and distortion of lead fluoride nanocrystals in rare earth doped oxyfluoride glass ceramics.

    Science.gov (United States)

    Ge, Jin; Zhao, Lijuan; Guo, Hui; Lan, Zijian; Chang, Lifen; Li, Yiming; Yu, Hua

    2013-10-28

    A series of rare earth (RE) doped oxyfluoride glasses with the composition of (45-x) SiO2-5Al2O3-40PbF2-10CdF2-xRe2O3 (x = 1, 5, 10, 15) (mol%) were prepared by a traditional melt-quenching method. Glass ceramics (GCs) were obtained after thermal treatment and characterized by X-ray diffraction (XRD) to investigate the nanocrystal structure and distortion. Both the dopant type and the doping level play an important role in the distortion of the PbF2-RE lattice. It is found that a cubic Pb3REF9 phase forms in low doping GCs, a tetragonal PbREF5 phase forms in middle doping GCs and cubic PbRE3F11 forms in high doping GCs. Accordingly, the site symmetry of RE(3+) dopants in β-PbF2 nanocrystal undergoes a transition of Oh···D4h···Oh with the increase of doping level. The change in the ligands coordinating the RE(3+) ions was further illustrated by the optical changes in Yb-doped GCs. This paper provides insights on the nanocrystal structure of RE at the atomic level and tries to make a complete description of the nanocrystal structure and distortion in these glass-ceramic materials, which will benefit the optimization of optical properties. PMID:24019159

  5. Final report of experimental laboratory-scale brittle fracture studies of glasses and ceramics

    International Nuclear Information System (INIS)

    An experimental program was conducted to characterize the fragments generated when brittle glasses and ceramics are impacted. The direct application of the results is to radioactive waste forms for which the effects of accidental impacts must be known or predictable. Two major measurable experimental responses used for characterization of these effects are (1) the size distribution of the fragments, including the sizes that are respirable, and (2) the increase in surface area of the brittle test specimen. This report describes the glass and ceramic materials characterized, the procedures and techniques used for the characterization of size distributions and surface areas, and the results of the two key responses of the impact tests. Five alternative methods of determining size distributions were compared. Also examined were the effects of diametral and axial specimen impact configurations and the use of mechanical stops to eliminate secondary crushing during testing. Microscopic characterizations of Pyrex and SRL 131 simulated waste glass and SYNROC fragments were also performed. Preliminary correlations of impact energy with key size-distribution parameters, fragment surface areas, and respirable fines were proposed as useful for future verification and for use with modeling and scale-up studies of brittle fracture of larger realistic waste forms. The impact fragments of all specimens could be described by lognormal size distributions

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

    DEFF Research Database (Denmark)

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

    1995-01-01

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

  7. Natural radioactivity in zirconia-based dental ceramics

    International Nuclear Information System (INIS)

    Zirconia-based ceramics are being increasingly used in dental prosthetics in substitution of metal cores, which are known to induce local toxic reactions and delayed allergic responses in the oral tissues. Some concerns have been however raised about the use of zirconia, since it is known that unpurified zirconia materials may contain non negligible levels of natural radionuclides of the U/Th series. Combined measurements of alpha and gamma spectrometry as well as beta dosimetry were conducted on zirconia samples used for dental applications. Samples were available in form of powder and/or solid blocks. The results showed that the beta dose rate in zirconia ceramics was on average only slightly higher than the levels measured in natural teeth, and generally lower than the values measured in feldspatic and glass ceramics. These materials are indeed known to deliver a beta dose significantly higher than that measured from natural teeth, due to the relatively high levels of 40K (between 2 and 3 kBq·kg-1). The content of radionuclides of the U/Th series in the zirconia sample was estimated to be lower than 15 Bq·kg-1, i.e. doubtlessly below the exclusion level of 1 kBq·kg-1 recommended by IAEA in the Safety Standard Series. Beta dosimetry measurements, however, gave indications of possible inhomogeneous clusters of radioactivity, which might give rise to local doses above the background. (author)

  8. Fabrication and Crystallization of ZnO-SLS Glass Derived Willemite Glass-Ceramics as a Potential Material for Optics Applications

    Directory of Open Access Journals (Sweden)

    Mohd Hafiz Mohd Zaid

    2016-01-01

    Full Text Available Willemite glass-ceramics were successfully derived from conventional melt-quench ZnO-SLS precursor glass by an isothermal heat treatment process. The effect of heat treatment temperatures on the physical properties was investigated by Archimedes principle and linear shrinkage. The generation of willemite crystal phase and morphology with increase in heat treatment temperature was examined by X-ray diffraction (XRD, Fourier transform infrared (FTIR, and field emission scanning electron microscopy (FESEM techniques. X-ray diffraction revealed that the metastable β-Zn2SiO4 and thermodynamically stable zinc orthosilicate α-Zn2SiO4 phases can be observed at temperatures above 700°C. The experimental results indicated that the density and shrinkage of the glass-ceramic vary with increasing the sintering temperature. FTIR studies showed that the structure of glass-ceramic consists of SiO2 and ZnO4 units and exhibits the structural evolution of willemite glass-ceramics. The characteristic of strong vibrational bands can be related to the SiO44- tetrahedron corresponding to reference spectra of willemite.

  9. Directly photoinscribed refractive index change and Bragg gratings in Ohara WMS-15 glass ceramic.

    Science.gov (United States)

    Krug, Peter A; Rogojan, Rodica Matei; Albert, Jacques

    2009-06-20

    We inscribed thick volume gratings in WMS-15 glass ceramic by ultraviolet light at 193 and 248 nm. Unlike earlier work in ceramic materials, the inscription process modified the optical properties of the material without the need for any additional chemical or thermal processing. Experimental evidence from measurements of grating growth, thermal annealing, and spectral absorption indicates that two distinct physical mechanisms are responsible for the grating formation. Weak, easily thermally bleached gratings resulted from exposure fluences below 0.3 kJ/cm2. Optical absorption measurements suggest that these low fluence gratings are predominantly absorption gratings. More thermally stable gratings, found to be refractive index gratings with unsaturated refractive index modulation amplitude as large as 6 x 10(-5) were formed at cumulative fluences of 1 kJ/cm2 and above.

  10. 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.

  11. Excitation wavelength-sensitive multi-colour fluorescence in Eu/Tb ions doped yttrium aluminium garnet glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jie [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Chen, Baojie; Bun Pun, Edwin Yue [Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong (China); Zhai, Bin [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Lin, Hai, E-mail: lhai8686@yahoo.com [School of Textile and Material Engineering, Dalian Polytechnic University, Dalian 116034 (China); Department of Electronic Engineering, City University of Hong Kong, Kowloon, Hong Kong (China)

    2013-02-15

    Eu/Tb doped yttrium aluminium garnet (YAG) glass ceramics, containing single phase of YAG micro-crystals with an excellent orientation (1 1 1) in the matrix, have been prepared by heat-treating lithium-yttrium-aluminium-silicate (LYAS) precursor glasses. A group of dynamic-colour white fluorescences with different colour temperatures are achieved in Eu/Tb codoped YAG glass ceramics, attributing to the simultaneous generation of three primary colour (RGB) emissions from Eu{sup 3+} (red), Eu{sup 2+} (blue), and Tb{sup 3+} (green) by varying the UV radiation wavelength. The favourable bright white light with the colour coordinate (0.360, 0.308) close to the equal energy point is obtained under 365 nm excitation. These admirable results indicate that the Eu/Tb codoped YAG glass ceramics are a promising candidate to develop white light sources under the excitation of commercial UV-LEDs. - Highlights: Black-Right-Pointing-Pointer RE doped glass ceramics (GC) have been derived by heat-treating LYAS mother glasses. Black-Right-Pointing-Pointer Single phase of YAG crystals has determined in RE doped GC. Black-Right-Pointing-Pointer YAG micro-crystals grow with an excellent orientation (1 1 1) in RE doped GC. Black-Right-Pointing-Pointer Two distinct luminescence centres of Eu in YAG GC have been identified. Black-Right-Pointing-Pointer Excitation wavelength-sensitive white light has been achieved in Eu/Tb doped YAG GC.

  12. Excitation wavelength-sensitive multi-colour fluorescence in Eu/Tb ions doped yttrium aluminium garnet glass ceramics

    International Nuclear Information System (INIS)

    Eu/Tb doped yttrium aluminium garnet (YAG) glass ceramics, containing single phase of YAG micro-crystals with an excellent orientation (1 1 1) in the matrix, have been prepared by heat-treating lithium–yttrium–aluminium–silicate (LYAS) precursor glasses. A group of dynamic-colour white fluorescences with different colour temperatures are achieved in Eu/Tb codoped YAG glass ceramics, attributing to the simultaneous generation of three primary colour (RGB) emissions from Eu3+ (red), Eu2+ (blue), and Tb3+ (green) by varying the UV radiation wavelength. The favourable bright white light with the colour coordinate (0.360, 0.308) close to the equal energy point is obtained under 365 nm excitation. These admirable results indicate that the Eu/Tb codoped YAG glass ceramics are a promising candidate to develop white light sources under the excitation of commercial UV-LEDs. - Highlights: ► RE doped glass ceramics (GC) have been derived by heat-treating LYAS mother glasses. ► Single phase of YAG crystals has determined in RE doped GC. ► YAG micro-crystals grow with an excellent orientation (1 1 1) in RE doped GC. ► Two distinct luminescence centres of Eu in YAG GC have been identified. ► Excitation wavelength-sensitive white light has been achieved in Eu/Tb doped YAG GC.

  13. Immobilization of Pu-containing wastes into glass and ceramics: Results of US-Russia collaboration

    Science.gov (United States)

    Anderson, E. B.; Aloy, A. S.; Burakov, B. E.; Jardine, L. J.

    2000-07-01

    This continuing collaboration between the V.G. Khlopin Radium Institute (KRI) in St. Petersberg, Russia, and Lawrence Livermore National Laboratory (LLNL) in the United States was initiated in 1997. The collaboration is focused on plutonium immobilization to support the disposition of excess weapons plutonium in the US and Russia. Our work consists primarily of laboratory-scale experiments and studies of borosilicate and phosphate Pu-doped glasses and zircon/zirconia, mono-zirconia, and pyrochlore ceramics. The results were used to compare and evaluate the use of these various materials in Pu immobilization.

  14. Experimental and theoretical approaches on thermal and structural properties of Zn doped BSCCO glass ceramics

    OpenAIRE

    Koralay H.; Hicyilmaz O.; Cavdar S.; Ozturk O.; Tasci A.T.

    2016-01-01

    Thermal properties of Cu–Zn partially substituted Bi1.8Sr2Ca2Cu3.2-xZnxO10+δ (x = 0, 0.1 and 0.5) glass-ceramic systems have been investigated with the help of a differential thermal analyzer (DTA) by using Johnson-Mehl-Avrami-Kolmogorov (JMAK) approximation. Non-isothermal crystallization kinetics of the samples has been tested. The calculated values of activation energy of crystallization (E) and Avrami parameter (n) ranged between 306.1 and 338.3 kJ.mol-1 and 1.29 and 3.59, respectively. C...

  15. Class II direct composite resin restorations with beta-quartz glass-ceramic inserts.

    Science.gov (United States)

    Rada, R E

    1993-11-01

    With the increasing demand for esthetic posterior restorations, numerous techniques have been developed. The direct resin restoration has probably been used most extensively in Class II situations. Problems with Class II direct resin restorations include difficulty in developing proximal contact, occlusal wear, and polymerization shrinkage. Beta-quartz glass-ceramic inserts have been developed in an attempt to reduce the incidence of these potential problems. They can be placed in a one-appointment technique, are relatively inexpensive, and can readily be utilized by the clinician adept in placing Class II composite resin restorations.

  16. Intense cooperative upconversion emission in Yb/Er: TeO{sub 2}–Li{sub 2}O–WO{sub 3} oxyfluoride glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Ghizal F.; Mahajan, S.K., E-mail: sachin_k_mahajan@rediffmail.com

    2014-12-15

    Novel oxyfluoride glass ceramics based on Yb{sup 3+}-doped TeO{sub 2}–Li{sub 2}O–WO{sub 3}–ErF{sub 3} (TWLE) were prepared using the two-stage heat-treatment method. The structural characterisation of these materials with X-ray diffraction indicated that crystalline phases of LiYbErF{sub 4} nanocrystals grew in the glass ceramics. Upon excitation with a 980 nm laser diode the Yb{sup 3+} doped (2 mol%) TWLE glass-ceramic produced intense blue emission at 487 nm, weak green emission at 525 nm and 550 nm, and red emission at 650 nm at room temperature. The mechanism of the blue emission, which is attributed to cooperative upconversion from pairs of excited Yb{sup 3+} ions to ground-state Er{sup 3+} ions, and the weak red and green emissions, which are attributed to energy transfer from Yb{sup 3+} to Er{sup 3+} ions, were investigated. The results of a pump-power dependence measurement suggested that the blue cooperative emission is a two-photon process. A rate equation was used to describe the cooperative energy-transfer process among the donor and acceptor ions. The observed results were compared to the behavior of another glass materials that exhibits blue cooperative emission, revealing the considerable advantage of TWLE:2Yb glass ceramics for optical devices. - Highlights: • The transparent glass-ceamics based on Yb doped TeO{sub 2}–Li{sub 2}O–WO{sub 3}–ErF{sub 3} (TWLE) have been prepared. • XRD confirm crystalline phase of LiYbErF{sub 4} nanocrystals are grown in glass ceramics. • Under 980 nm LD excitation of TWLE:2Yb produced intense blue emission due to cooperative upconversion process exists. • Pump power excitation confirms cooperative upconvesion is two-photon process. • The quadratic dependence of pump intensity determined by mean of the rate equations. • Comparative studies of blue cooperative for TWLE:2Yb with other Yb doped materials described.

  17. Development of a sintering process for recycling oil shale fly ash and municipal solid waste incineration bottom ash into glass ceramic composite

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhikun; Zhang, Lei; Li, Aimin, E-mail: leeam@dlut.edu.cn

    2015-04-15

    Highlights: • Glass ceramic composite is prepared from oil shale fly ash and MSWI bottom ash. • A novel method for the production of glass ceramic composite is presented. • It provides simple route and lower energy consumption in terms of recycling waste. • The vitrified slag can promote the sintering densification process of glass ceramic. • The performances of products decrease with the increase of oil shale fly ash content. - Abstract: Oil shale fly ash and municipal solid waste incineration bottom ash are industrial and municipal by-products that require further treatment before disposal to avoid polluting the environment. In the study, they were mixed and vitrified into the slag by the melt-quench process. The obtained vitrified slag was then mixed with various percentages of oil shale fly ash and converted into glass ceramic composites by the subsequent sintering process. Differential thermal analysis was used to study the thermal characteristics and determine the sintering temperatures. X-ray diffraction analysis was used to analyze the crystalline phase compositions. Sintering shrinkage, weight loss on ignition, density and compressive strength were tested to determine the optimum preparation condition and study the co-sintering mechanism of vitrified amorphous slag and oil shale fly ash. The results showed the product performances increased with the increase of sintering temperatures and the proportion of vitrified slag to oil shale fly ash. Glass ceramic composite (vitrified slag content of 80%, oil shale fly ash content of 20%, sintering temperature of 1000 °C and sintering time of 2 h) showed the properties of density of 1.92 ± 0.05 g/cm{sup 3}, weight loss on ignition of 6.14 ± 0.18%, sintering shrinkage of 22.06 ± 0.6% and compressive strength of 67 ± 14 MPa. The results indicated that it was a comparable waste-based material compared to previous researches. In particular, the energy consumption in the production process was reduced

  18. Development of a sintering process for recycling oil shale fly ash and municipal solid waste incineration bottom ash into glass ceramic composite

    International Nuclear Information System (INIS)

    Highlights: • Glass ceramic composite is prepared from oil shale fly ash and MSWI bottom ash. • A novel method for the production of glass ceramic composite is presented. • It provides simple route and lower energy consumption in terms of recycling waste. • The vitrified slag can promote the sintering densification process of glass ceramic. • The performances of products decrease with the increase of oil shale fly ash content. - Abstract: Oil shale fly ash and municipal solid waste incineration bottom ash are industrial and municipal by-products that require further treatment before disposal to avoid polluting the environment. In the study, they were mixed and vitrified into the slag by the melt-quench process. The obtained vitrified slag was then mixed with various percentages of oil shale fly ash and converted into glass ceramic composites by the subsequent sintering process. Differential thermal analysis was used to study the thermal characteristics and determine the sintering temperatures. X-ray diffraction analysis was used to analyze the crystalline phase compositions. Sintering shrinkage, weight loss on ignition, density and compressive strength were tested to determine the optimum preparation condition and study the co-sintering mechanism of vitrified amorphous slag and oil shale fly ash. The results showed the product performances increased with the increase of sintering temperatures and the proportion of vitrified slag to oil shale fly ash. Glass ceramic composite (vitrified slag content of 80%, oil shale fly ash content of 20%, sintering temperature of 1000 °C and sintering time of 2 h) showed the properties of density of 1.92 ± 0.05 g/cm3, weight loss on ignition of 6.14 ± 0.18%, sintering shrinkage of 22.06 ± 0.6% and compressive strength of 67 ± 14 MPa. The results indicated that it was a comparable waste-based material compared to previous researches. In particular, the energy consumption in the production process was reduced compared

  19. Influence of acid-etching and ceramic primers on the repair of a glass ceramic.

    Science.gov (United States)

    Queiroz, J R C; Souza, Rodrigo O A; Nogueira Junior, L; Ozcan, M; Bottino, M A

    2012-01-01

    The objective of this study was to evaluate the influence of different primers on the microtensile bond strength (μTBS) between a feldspathic ceramic and two composites. Forty blocks (6.0 x 6.0 x 5.0 mm³) were prepared from Vita Mark II . After polishing, they were randomly divided into 10 groups according to the surface treatment: Group 1, hydrofluoric acid 10% (HF) + silane; Group 2, CoJet + silane; Group 3, HF + Metal/Zirconia Primer; Group 4, HF + Clearfil Primer; Group 5, HF + Alloy Primer; Group 6, HF + V-Primer; Group 7, Metal/Zirconia Primer; Group 8, Clearfil Primer; Group 9, Alloy Primer; Group 10, V-Primer. After each surface treatment, an adhesive was applied and one of two composite resins was incrementally built up. The sticks obtained from each block (bonded area: 1.0 mm² ± 0.2 mm) were stored in distilled water at 37 degrees C for 30 days and submitted to thermocycling (7,000 cycles; 5 degrees C/55 degrees C ± 1 degree C). The μTBS test was carried out using a universal testing machine (1.0 mm/min). Data were analyzed using ANOVA and a Tukey test (a = 0.05). The surface treatments significantly affected the results (P 0.05). The bond strength means (MPa) were as follows: Group 1a = 29.6; Group 1b = 33.7; Group 2a = 28.9; Group 2b = 27.1; Group 3a = 13.8; Group 3b = 14.9; Group 4a = 18.6; Group 4b = 19.4; Group 5a = 15.3; Group 5b = 16.5; Group 6a = 11; Group 6b = 18; Groups 7a to 10b = 0. While the use of primers alone was not sufficient for adequate bond strengths to feldspathic ceramic, HF etching followed by any silane delivered higher bond strength.

  20. Influence of acid-etching and ceramic primers on the repair of a glass ceramic.

    Science.gov (United States)

    Queiroz, J R C; Souza, Rodrigo O A; Nogueira Junior, L; Ozcan, M; Bottino, M A

    2012-01-01

    The objective of this study was to evaluate the influence of different primers on the microtensile bond strength (μTBS) between a feldspathic ceramic and two composites. Forty blocks (6.0 x 6.0 x 5.0 mm³) were prepared from Vita Mark II . After polishing, they were randomly divided into 10 groups according to the surface treatment: Group 1, hydrofluoric acid 10% (HF) + silane; Group 2, CoJet + silane; Group 3, HF + Metal/Zirconia Primer; Group 4, HF + Clearfil Primer; Group 5, HF + Alloy Primer; Group 6, HF + V-Primer; Group 7, Metal/Zirconia Primer; Group 8, Clearfil Primer; Group 9, Alloy Primer; Group 10, V-Primer. After each surface treatment, an adhesive was applied and one of two composite resins was incrementally built up. The sticks obtained from each block (bonded area: 1.0 mm² ± 0.2 mm) were stored in distilled water at 37 degrees C for 30 days and submitted to thermocycling (7,000 cycles; 5 degrees C/55 degrees C ± 1 degree C). The μTBS test was carried out using a universal testing machine (1.0 mm/min). Data were analyzed using ANOVA and a Tukey test (a = 0.05). The surface treatments significantly affected the results (P 0.05). The bond strength means (MPa) were as follows: Group 1a = 29.6; Group 1b = 33.7; Group 2a = 28.9; Group 2b = 27.1; Group 3a = 13.8; Group 3b = 14.9; Group 4a = 18.6; Group 4b = 19.4; Group 5a = 15.3; Group 5b = 16.5; Group 6a = 11; Group 6b = 18; Groups 7a to 10b = 0. While the use of primers alone was not sufficient for adequate bond strengths to feldspathic ceramic, HF etching followed by any silane delivered higher bond strength. PMID:22414522

  1. Tb3+-activated SiO2-Al2O3-CaO-CaF2 oxyfluoride scintillating glass ceramics

    International Nuclear Information System (INIS)

    In this paper, transparent glass ceramics containing CaF2 nanocrystals were synthesized by heat-treating as-made Tb3+/Gd3+-codoped 45SiO2-20Al2O3-10CaO-25CaF2 oxyfluoride glass. The precipitated crystalline phase in the glass ceramics is CaF2 nanocrystals identified by X-ray diffraction (XRD) patterns. Both photoluminescence (PL) and X-ray excited luminescence (XEL) results show that enhancement of Tb3+ 542 nm emission intensity by a factor of about 2-3 is achieved in glass ceramics with respect to the as-made glass. XEL intensity of the investigated glass ceramics is comparable to that of the commercial glass sciltillatior (LHK-6 type), which suggests its potential for scintillation application.

  2. Mid-infrared emission in Yb3+-Er3+-Tm3+ co-doped oxyfluoride glass-ceramics

    International Nuclear Information System (INIS)

    Mid-infrared emission in the range between 1.5 and 1.9 μm with a lifetime of about 9 ms is reported in Yb3+-Er3+-Tm3+ co-doped transparent oxyfluoride nano-glass-ceramics 32(SiO2)9(AlO1.5)31.5(CdF2)18.5(PbF2)5.5(ZnF2):3.5(Yb-Er-TmF3), mol%, in which the Yb3+, Er3+ and Tm3+ co-dopants partition in PbF2-based nano-crystals embedded in the glass network. Due to short distance between the co-dopants in the nano-crystals, after excitation in Yb3+ an efficient energy transfer has been observed between the co-dopants resulting in fast depopulation of their excited levels and subsequent feeding of the emission bands 4I13/2 → 4I15/2 of the Er3+ (centred at 1.55 μm) and 3F4 → 3H6 of the Tm3+ (centred at 1.80 μm). These bands overlap due to the 1.64 μm shoulder of the 3F4 → 3H6 band of the Tm3+, which uniquely appears in the emission band of the Tm3+ in this nano-glass-ceramics. The entire emission band from 1.5 to 1.9 μm provides a potential for application in respective mid-infrared tuneable lasers/amplifiers

  3. Infrared quantum cutting in Tb3+,Yb3+ codoped transparent glass ceramics containing CaF2 nanocrystals

    International Nuclear Information System (INIS)

    Tb3+-Yb3+ codoped transparent oxyfluoride glass ceramics containing CaF2 nanocrystals were synthesized. The formation of CaF2 nanocrystals in the glass ceramics was confirmed by x-ray diffraction and high resolution transmission electron microscopy. The incorporation of Tb3+ and Yb3+ into CaF2 nanocrystal lattice was confirmed by energy dispersive spectroscopy. Infrared quantum cutting involving Yb3+ 950-1100 nm (2F5/2→2F7/2) emission was achieved upon the excitation of 5D4 energy level of Tb3+ at 484 nm. The photoluminescence properties have been studied for these glass ceramics. Yb3+ concentration dependent quantum efficiency was calculated, and the maximum efficiency approaches 155% before reaching concentration quenching threshold

  4. Erosion Resistance of CaO-Al2O3-SiO2 System Glass-Ceramics

    Institute of Scientific and Technical Information of China (English)

    HE Feng; NIU Feng; LOU Guang-hui; DENG Zhi-guo

    2004-01-01

    The erosion resistance tests were used to research the erosion wear behavior of CaO-Al2O3-SiO2 system glass-ceramic. With the orthogonal test method, the factors that affect the erosion wear of CaO-Al2O3-SiO2 system glass-ceramic such as particles property, impact angle, impact time, size of particles were discussed.The results show that erosion rate rises along a straight line at the early period of erosion wear.With the impact time increased,the erosion rate deviates from original staight line,tendency of the erosion rate increases.With the size of paricle increased,it will have more kinetic energy,the erosion rate of the surface of glass-ceramics ploate rises.

  5. Flexural strength and translucent characteristics of lithium disilicate glass-ceramics with different P2O5 content

    International Nuclear Information System (INIS)

    Lithium disilicate glass-ceramics derived from the SiO2-Li2O-K2O-Al2O3-ZrO2-P2O5 system with different P2O5 content (from 0.5 mol.% to 2.0 mol.% at a step of 0.5 mol.%) were prepared for dental restorative application. Flexural strength of final glass-ceramics and translucent characteristics expressed in term of contrast ratio (CR) were measured. The interrelations between P2O5 content, microstructure and properties were discussed. Glass-ceramic with a P2O5 content of 1.0 mol.%, in which elongated rod-like Li2Si2O5 crystals formed an interlocking microstructure, showed the highest flexural strength and suitable contrast ratio for dental restorative application.

  6. Effect of CaO content on residual stress of CAS glass-ceramic

    Institute of Scientific and Technical Information of China (English)

    XIE Jun; CHENG Jin-shu; LONG Xin-jiang; YANG Shu-zhen

    2006-01-01

    The mismatch in thermal expansion coefficient between crystalline phase and glass phase can result in large thermal stresses during thermal processing,as well as the low thermal conductivity,which is the most troublesome in the production of the CaO-Al2O3-SiO2 glass-ceramic. CaO content may influence the residual stress in the system. Therefore X-ray diffraction (XRD) 'sin2ψ' method was used to calculate the residual stress in samples containing various contents of CaO. The relationship between CaO content and residual stress in CAS system was investigated. Finally reasons causing such residual stress were analyzed.

  7. Effect of sintering temperature on structure and properties of highly porous glass-ceramics

    Directory of Open Access Journals (Sweden)

    Artem Iatsenko

    2015-06-01

    Full Text Available Highly porous biomaterials with a structure close to that of cancellous bone have been prepared using biogenic hydroxyapatite and glass of the SiO2-Na2O-CaO system by a replication of the polymer template structure. It has been established that during sintering of the samples the hydroxyapatite decomposes, which involves the formation of glass-ceramics containing phases of renanit NaCaPO4, calcium phosphate silicate Ca5(PO42SiO4, calcium pyrophosphate Ca2P2O7 and impurities of hydroxyapatite Ca5(PO43(OH. Structural characteristics and mechanical properties of the obtained materials are promising for the replacement of defective cancellous bone.

  8. Effectiveness of high temperature innovative geometry fixed ceramic matrix regenerators used in glass furnaces

    Directory of Open Access Journals (Sweden)

    Wołkowycki Grzegorz

    2016-03-01

    Full Text Available The paper presents the effectiveness of waste heat recovery regenerators equipped with innovative ceramic matrix forming an integral part of a real glass furnace. The paper full description of the regenerators’ matrix structure with its dimensions, thermo-physical properties and operating parameters is included experimentally determined was the effectiveness of the regenerators has been descrbed using the obtained experimental data such as the operating temperature, gas flows as well as the gases generated during the liquid glass manufacturing process. The effectiveness values refer not only to the heating cycle when the regenerator matrix is heated by combustion gases but also to the cooling cycle in which the matrix is cooled as a result of changes in the direction of the flowing gas. On the basis of the determined effectiveness values for both cycles and measurement uncertainties it was possible, to calculate the weighted average efficiency for each of the regenerators.

  9. Effectiveness of high temperature innovative geometry fixed ceramic matrix regenerators used in glass furnaces

    Science.gov (United States)

    Wołkowycki, Grzegorz

    2016-03-01

    The paper presents the effectiveness of waste heat recovery regenerators equipped with innovative ceramic matrix forming an integral part of a real glass furnace. The paper full description of the regenerators' matrix structure with its dimensions, thermo-physical properties and operating parameters is included experimentally determined was the effectiveness of the regenerators has been descrbed using the obtained experimental data such as the operating temperature, gas flows as well as the gases generated during the liquid glass manufacturing process. The effectiveness values refer not only to the heating cycle when the regenerator matrix is heated by combustion gases but also to the cooling cycle in which the matrix is cooled as a result of changes in the direction of the flowing gas. On the basis of the determined effectiveness values for both cycles and measurement uncertainties it was possible, to calculate the weighted average efficiency for each of the regenerators.

  10. Standard test methods for determining chemical durability of nuclear, hazardous, and mixed waste glasses and multiphase glass ceramics: The product consistency test (PCT)

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2002-01-01

    1.1 These product consistency test methods A and B evaluate the chemical durability of homogeneous glasses, phase separated glasses, devitrified glasses, glass ceramics, and/or multiphase glass ceramic waste forms hereafter collectively referred to as “glass waste forms” by measuring the concentrations of the chemical species released to a test solution. 1.1.1 Test Method A is a seven-day chemical durability test performed at 90 ± 2°C in a leachant of ASTM-Type I water. The test method is static and conducted in stainless steel vessels. Test Method A can specifically be used to evaluate whether the chemical durability and elemental release characteristics of nuclear, hazardous, and mixed glass waste forms have been consistently controlled during production. This test method is applicable to radioactive and simulated glass waste forms as defined above. 1.1.2 Test Method B is a durability test that allows testing at various test durations, test temperatures, mesh size, mass of sample, leachant volume, a...

  11. Effect of nanocrystals on up-conversion luminescence of Er3+,Yb3+ co-doped glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    Hua Yu; Lijuan Zhao; Jie Meng; Qin Liang; Xuanyi Yu; Baiquan Tang; Jingjun Xu

    2005-01-01

    @@ Different up-conversion luminescent spectra of Er3+ ions were observed in the oxyfluoride glass-ceramics.The ratio of two fluorides in the original compositions was modified in order to form different nanocrystals.The intensity of up-conversion luminescence increased sharply when the ratio of PbF2 and CdF2 was 40:10.The data of differential thermal analysis and X-ray diffraction were used to explain the optimization fluoride ratio. The intensity of up-conversion luminescence is not only decided by the crystallizability but also mainly related with the stoichiometric proportion of fluoride nanocrystals in the glass-ceramics.

  12. Cooperative Quantum Cutting of Nano-Crystalline BaF2:Tb3+, Yb3+ in Oxyfluoride Glass Ceramics

    International Nuclear Information System (INIS)

    We report on cooperative quantum cutting in Tb3+-Yb3+ codoped glass ceramics. Precipitation of BaF2 nano-crystals is confirmed by XRD and HRTEM analysis. Near-infrared emission due to transition of Yb3+ ions under 485 nm excitation indicates cooperative energy transfer from Tb3+ to Yb3+. The quantum efficiency of this process reaches 145%. The realization of quantum cutting in glass ceramics may have promising applications in solar cells. (fundamental areas of phenomenology (including applications))

  13. Effect of surface conditioning methods on the bond strength of luting cement to ceramics

    NARCIS (Netherlands)

    Ozcan, M; Vallittu, PK; Özcan, Mutlu; Vallittu, Pekka K.

    2003-01-01

    Objectives. This study evaluated the effect of three different surface conditioning methods on the bond strength of a Bis-GMA based luting cement to six commercial dental ceramics. Methods. Six disc shaped ceramic specimens (glass ceramics, glass infiltrated alumina, glass infiltrated zirconium diox

  14. Experimental and theoretical approaches on thermal and structural properties of Zn doped BSCCO glass ceramics

    Directory of Open Access Journals (Sweden)

    Koralay H.

    2016-03-01

    Full Text Available Thermal properties of Cu–Zn partially substituted Bi1.8Sr2Ca2Cu3.2-xZnxO10+δ (x = 0, 0.1 and 0.5 glass-ceramic systems have been investigated with the help of a differential thermal analyzer (DTA by using Johnson-Mehl-Avrami-Kolmogorov (JMAK approximation. Non-isothermal crystallization kinetics of the samples has been tested. The calculated values of activation energy of crystallization (E and Avrami parameter (n ranged between 306.1 and 338.3 kJ.mol-1 and 1.29 and 3.59, respectively. Crystallization kinetics was compared following the partial substitution, before and after Zn doping of the sample. In addition, by using a scanning electron microscope (SEM and X-ray powder diffractometer (XRD, structural properties of Zn doped BSCCO glass-ceramic samples were determined. Surface morphology of the samples was studied by SEM measurements. Lattice parameters and volume of the samples were calculated from the XRD measurements.

  15. Surface engineering glass-metal coatings designed for induction heating of ceramic components

    Science.gov (United States)

    Khan, Amir Azam; Labbe, Jean Claude

    2014-06-01

    The term Surface Engineering is of relatively recent origin and use, however, the use of coatings and treatments to render surfaces of materials more suitable for certain application or environment is not new. With the advent of Vacuum Technology, Surface Engineering has gained a whole new impetus, whereby expensive materials with adequate mechanical, chemical and thermal properties are being coated or treated on their surfaces in order to achieve what is called as Surface Engineered materials. The present paper presents an overview of recent achievements in Surface Engineering and gives a detailed view of a specific application where glass-metal composite coatings were deposited on ceramic components in order to render them sensitive to induction heating. Sintered glaze coatings containing silver particles in appropriate concentration can be used for the induction heating of porcelain. Mixtures of glass ceramic powders with silver are used to prepare self-transfer patterns, which are deposited over porcelain. Several configurations of these coatings, which are aesthetic to start with, are employed and heating patterns are recorded. The microstructure of these coatings is discussed in relation to the heating ability by a classical household induction system. The results show that this technique is practical and commercially viable.

  16. Surface engineering glass-metal coatings designed for induction heating of ceramic components

    International Nuclear Information System (INIS)

    The term Surface Engineering is of relatively recent origin and use, however, the use of coatings and treatments to render surfaces of materials more suitable for certain application or environment is not new. With the advent of Vacuum Technology, Surface Engineering has gained a whole new impetus, whereby expensive materials with adequate mechanical, chemical and thermal properties are being coated or treated on their surfaces in order to achieve what is called as Surface Engineered materials. The present paper presents an overview of recent achievements in Surface Engineering and gives a detailed view of a specific application where glass-metal composite coatings were deposited on ceramic components in order to render them sensitive to induction heating. Sintered glaze coatings containing silver particles in appropriate concentration can be used for the induction heating of porcelain. Mixtures of glass ceramic powders with silver are used to prepare self-transfer patterns, which are deposited over porcelain. Several configurations of these coatings, which are aesthetic to start with, are employed and heating patterns are recorded. The microstructure of these coatings is discussed in relation to the heating ability by a classical household induction system. The results show that this technique is practical and commercially viable

  17. Preliminary Technology Maturation Plan for Immobilization of High-Level Waste in Glass Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Vienna, John D.; Crum, Jarrod V.; Sevigny, Gary J.; Smith, G L.

    2012-09-30

    A technology maturation plan (TMP) was developed for immobilization of high-level waste (HLW) raffinate in a glass ceramics waste form using a cold-crucible induction melter (CCIM). The TMP was prepared by the following process: 1) define the reference process and boundaries of the technology being matured, 2) evaluate the technology elements and identify the critical technology elements (CTE), 3) identify the technology readiness level (TRL) of each of the CTE’s using the DOE G 413.3-4, 4) describe the development and demonstration activities required to advance the TRLs to 4 and 6 in order, and 5) prepare a preliminary plan to conduct the development and demonstration. Results of the technology readiness assessment identified five CTE’s and found relatively low TRL’s for each of them: • Mixing, sampling, and analysis of waste slurry and melter feed: TRL-1 • Feeding, melting, and pouring: TRL-1 • Glass ceramic formulation: TRL-1 • Canister cooling and crystallization: TRL-1 • Canister decontamination: TRL-4 Although the TRL’s are low for most of these CTE’s (TRL-1), the effort required to advance them to higher values. The activities required to advance the TRL’s are listed below: • Complete this TMP • Perform a preliminary engineering study • Characterize, estimate, and simulate waste to be treated • Laboratory scale glass ceramic testing • Melter and off-gas testing with simulants • Test the mixing, sampling, and analyses • Canister testing • Decontamination system testing • Issue a requirements document • Issue a risk management document • Complete preliminary design • Integrated pilot testing • Issue a waste compliance plan A preliminary schedule and budget were developed to complete these activities as summarized in the following table (assuming 2012 dollars). TRL Budget Year MSA FMP GCF CCC CD Overall $M 2012 1 1 1 1 4 1 0.3 2013 2 2 1 1 4 1 1.3 2014 2 3 1 1 4 1 1.8 2015 2 3 2 2 4 2 2.6 2016 2 3 2 2 4 2 4

  18. Crystallization and thermo-mechanical properties of Li2O-ZnO-CaOSiO2 glass-ceramics with In2O3 and Fe2O3 additives

    Directory of Open Access Journals (Sweden)

    Saad M. Salman

    2015-12-01

    Full Text Available Li2O-ZnO-CaO-SiO2 based glasses were prepared by the conventional melting technique and subsequently converted to glass-ceramics by controlled crystallization. The nucleation and crystallization temperatures were determined by differential thermal analysis (DTA. The effects of adding In2O3 and Fe2O3 addition on the crystallization behaviour and thermo-mechanical properties of the prepared glass-ceramics were investigated. A study on the microstructure, close to the internal phases of the resulting glass-ceramics, was followed by using scanning electron microscope (SEM. The dilatometric thermal expansion and Vickers’ microhardness of the crystalline products were also evaluated. The crystalline phases that can be found in the resulting glass-ceramics, identified by X-ray diffraction (XRD analysis, are α-quartz-[SiO2], lithium zinc silicate-[Li2ZnSiO4], lithium disilicate-[Li2Si2O5], wollastonite-[CaSiO3], wollastonite containing iron, ferrobustamite-[(Ca0.79Fe0.21SiO3], and lithium indium silicate of pyroxene type-[LiInSi2O6]. Average thermal expansion coefficient (in the temperature range 25–700 °C decreased from 191×10-7 1/°C to 115×10-7 1/°C and the Vickers’ microhardness increased from 3.56 to 5.44 GPa with the increase of In2O3 and Fe2O3 contents in the glass-ceramics. The changes in the obtained expansion coefficient and microhardness were due to the formation of different phases which in turn influenced the rigidity/bonding and microstructure in the resultant glass-ceramics.

  19. Influence of fluoride additions on biological and mechanical properties of Na2O-CaO-SiO2-P2O5 glass-ceramics.

    Science.gov (United States)

    Li, H C; Wang, D G; Hu, J H; Chen, C Z

    2014-02-01

    Two series of Na2O-CaO-SiO2-P2O5 glass-ceramics doped with NH4HF2 (G-NH4HF2) or CaF2 (G-CaF2) have been prepared by sol-gel method. The glass-ceramic phase composition and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS). The mechanical properties and thermal expansion coefficient were measured by a microhardness tester, an electronic tensile machine and a thermal expansion coefficient tester. The structure difference between these two glass-ceramics was investigated by Fourier transform infrared spectroscopy (FTIR), and the in vitro bioactivity of the glass-ceramics was determined by in vitro simulated body fluid (SBF) immersion test. The hemolysis test, in vitro cytotoxicity test, systemic toxicity test and the implanted experiment in animals were used to evaluate the biocompatibility of the glass-ceramics. The mechanical properties of sample G-NH4HF2 are lower than that of sample G-CaF2, and the bioactivity of sample G-NH4HF2 is better than that of sample G-CaF2. The thermal expansion coefficients of these two glass-ceramics are all closer to that of Ti6Al4V. After 7 days of SBF immersion, apatites were induced on glass-ceramic surface, indicating that the glass-ceramics have bioactivity. The hemolysis test, in vitro cytotoxicity test and systemic toxicity test demonstrate that the glass-ceramics do not cause hemolysis reaction, and have no toxicity to cell and living animal. The implanted experiment in animals shows that bone tissue can form a good osseointegration with the implant after implantation for two months, indicating that the glass-ceramics are safe to serve as implants.

  20. Pb-Free Glass Paste: A Metallization-Free Die-Attachment Solution for High-Temperature Application on Ceramic Substrates

    Science.gov (United States)

    Sharif, Ahmed; Lim, Jun zhang; Made, Riko I.; Lau, Fu Long; Phua, Eric Jian Rong; Lim, Ju Dy; Wong, Chee Cheong; Gan, Chee Lip; Chen, Zhong

    2013-08-01

    A lead-free glass frit paste as a die-attach material for high-temperature microelectronic application is proposed in this study. The glass paste containing Bi-based powder with a moderate amount of solvent was used for joining Si dice on ceramic substrates without any metallization preparation for either of the bonding surfaces. The die was bonded to a ceramic substrate at 430°C for 10 min. The study focuses on the mechanical and microstructural characterization of the joints with Si dice on two different types of ceramic substrate. Shear strength measurements were carried out at both ambient and 250°C to evaluate room- and high-temperature performance. Furthermore, the effect of aging at 300°C for 500 h on the mechanical properties is presented. The results of the mechanical and microstructural characterization demonstrate that low-temperature glass frit bonding is an effective die-attach method for harsh-environment electronic packaging.

  1. Charge Carrier Relaxation Study in Glass-Added Barium Titanate Ceramics Using Thermally Stimulated Depolarization Current

    Science.gov (United States)

    Zhang, Qian; Zhang, Yong; Liu, Xiaolin; Song, Xiaozhen; Zhu, Jia; Baturin, Ivan

    2016-08-01

    The depolarization process of glass-added barium titanate (BaTiO3) ceramics with two different glass concentrations was investigated using a thermally stimulated depolarization current (TSDC) technique. The TSDC spectra of the glass-added BaTiO3 ceramics show three peaks. The first sharp peak near the Curie temperature is due to pyroelectric current associated with ferroelectric-paraelectric phase transition. The middle temperature peak at about 200°C showed no dependence on the depolarization current peak position in the polarization field, and the activation energies of this peak were between 0.43 eV and 0.55 eV, which are attributed to the behavior of defect dipoles related to oxygen vacancies within the BaTiO3 grains. Moreover, the high temperature peak at around 300°C indicated that the depolarization current peak position depends on the polarization temperature and decreases with increasing polarization field. The activation energy of this high temperature peak was between 0.78 eV and 0.98 eV, which is similar to the activation energy for the motion of oxygen vacancies in perovskite oxides. The high temperature peak could be attributed to the migration of oxygen vacancies across grain boundaries. In this work we developed a model in which oxygen vacancies that originated from the defect within grains migrated from the anode to the cathode and some were trapped at the grain boundaries. It is presented here and successfully interprets the appearance and behavior of these peaks.

  2. In vitro solubility and bioactivity of Sr and Mg co-doped calcium phosphate glass-ceramics derived from different heat-treatment temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Cai Shu, E-mail: caishu@tju.edu.cn [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Li Jianxin [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Xu Guohua [Shanghai Changzheng Hospital, Shanghai 200003 (China); Li, Xudong [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China); Ye Xiaojian [Shanghai Changzheng Hospital, Shanghai 200003 (China); Jiang Wei [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer Porous glass ceramics were prepared by controlled heat treatment process. Black-Right-Pointing-Pointer A fast release of Mg ions has a great influence on the Ca/P ratio of the deposits. Black-Right-Pointing-Pointer The chemical stability of the deposited apatite directly affects cell behavior. Black-Right-Pointing-Pointer The glass ceramics heat-treated at 760 Degree-Sign C and 780 Degree-Sign C show less glass. Black-Right-Pointing-Pointer The degradation rates are both compatible with cell growth and differentiation. - Abstract: CaO-P{sub 2}O{sub 5}-Na{sub 2}O-SrO-MgO glass-ceramic system was prepared by controlled heat treatment process. Solubility and bioactivity of glass-ceramics were measured and evaluated in simulated body fluid (SBF) and cell culture medium respectively. The dissolution behavior of these glass-ceramics strongly depends on the amount and microstructure of the crystals precipitated by sintering treatment. Concerning the bioactivity, the onset of the apatite formation on the glass-ceramic system was directly dependent on the amount of bioactive glass amount which can be controlled using different temperatures of heat treatment. After immersing glass-ceramic in SBF, Mg ion as one of system composition can be released from residual glass and provides a high impact on the Ca/P ratio and chemical stability of the deposited apatite layer that directly affects cell attachment and proliferation in in vitro cell culture system. The glass ceramics heat-treated at 760 Degree-Sign C and 780 Degree-Sign C show less glass amount, and their degradation rates are both compatible with cell growth and differentiation.

  3. Synthesis of nano-bioactive glass-ceramic powders and its in vitro bioactivity study in bovine serum albumin protein

    Science.gov (United States)

    Nabian, Nima; Jahanshahi, Mohsen; Rabiee, Sayed Mahmood

    2011-07-01

    Bioactive glasses and ceramics have proved to be able to chemically bond to living bone due to the formation of an apatite-like layer on its surface. The aim of this work was preparation and characterization of bioactive glass-ceramic by sol-gel method. Nano-bioglass-ceramic material was crushed into powder and its bioactivity was examined in vitro with respect to the ability of hydroxyapatite layer to form on the surface as a result of contact with bovine serum albumin (BSA) protein. The obtained nano-bioactive glass-ceramic was analyzed before and after contact with BSA solution. This study used scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis to examine its morphology, crystallinity and composition. The TEM images showed that the NBG particles size were 10-40 nm. Bioactivity of nanopowder was confirmed by SEM and XRD due to the presence of a rich bone-like apatite layer. Therefore, this nano-BSA-bioglass-ceramic composite material is promising for medical applications such as bone substitutes and drug carriers.

  4. EFFECT OF SINTERING TEMPERATURE ON MICROSTRUCTURE AND IN-VITRO BEHAVIOR OF BIOACTIVE GLASS-CERAMICS

    Directory of Open Access Journals (Sweden)

    Hashmi M. U.

    2013-12-01

    Full Text Available In this work, powders of the composition (CaO 46- SiO2 34- P2O5 14.5- MgO 4- CaF2 1- MgF2 0.5 (wt. % were thoroughly mixed and melted in a muffle furnace. The melt was quenched in water to form glass. Three glass-ceramics were prepared by sintering glass samples at three different temperatures 850, 900 and 950°C according to the exothermal peaks of DTA. The DTA peaks correspond to the bioactive crystalline phases hydroxyapatite (HA and wollastonite as confirmed by the XRD data. Study of diameter-shrinkage co-efficient and bulk-density of samples revealed higher densification rate for the range 900 - 950°C than that for the range 850 - 900°C.SEM and optical microscope results illustrated a tendency towards closely packed structure and increasing grain size with the increase of sintering temperature. The samples were immersed in SBF for 30 days at room temperature for in-vitro evaluation.EDS analysis, showing the presence of carbon (C along with calcium (Ca and phosphorus (P suggests the formation of hydroxycarbonate-apatite (HCA phase that indicates the bioactivity of the material which increases with the increase of sintering temperature.

  5. Transparent oxyfluoride glass ceramics co-doped with Er3+ and Yb3+ - Crystallization and upconversion spectroscopy

    International Nuclear Information System (INIS)

    Transparent glass ceramics in the system SiO2-B2O3-PbO-CdO-PbF2-CdF2-YbF3-ErF3 showing infrared to visible anti-Stokes (upconversion) luminescence are studied in the present work. The glass compositions have been optimized in order to reduce the melting temperature and, hence, to obtain laboratory scale samples with good optical quality. Erbium-doped nanoscale Pb4Yb3F17 crystals are precipitated in the precursor glasses during annealing at temperatures 30-40 K above Tg. A kinetically self-constrained growth explains the nano sizes of the crystals. Both the Stokes and anti-Stokes luminescence spectra of glasses could be explained with clustering of the Yb3+ and Er3+ ions in fluorine-rich regions. At the annealing temperature these regions act as nucleation precursors. The crystal growth further enhances the local concentration of these ions. Consequently, a series of energy transfer and energy cross relaxation processes occurs between adjacent rare earth ions leading to the observed luminescence spectra of the glass ceramics studied. -- Graphical abstract: A highly viscous shell (shown in the picture in dark blue) is build around the growing crystal (white circles). When the shell's Tg approaches the annealing temperature, the crystal growth is fully suppressed for kinetic reasons. The upconversion luminescence, resulting from the simultaneous absorption of two and even three infrared photons, is depicted schematically in the right part of the figure. Display Omitted Highlights: → New oxyfluoride glass compositions with reduced melting temperature are formulated. → The phase Pb4Yb3F17 doped with Er3+ ions crystallizes in these glasses. → A kinetically self-constrained growth explains the nano sizes of the crystals. → Clustering of Yb3+, Er3+ and Pb2+ ions into fluorine-rich glass regions is observed. → The luminescence of glass-ceramics is consistent with its structure.

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

    Science.gov (United States)

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

    2015-06-01

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

  7. Transient and residual stresses in a pressable glass-ceramic before and after resin-cement coating determined using profilometry.

    LENUS (Irish Health Repository)

    2011-05-01

    The effect of heat-pressing and subsequent pre-cementation (acid-etching) and resin-cementation operative techniques on the development of transient and residual stresses in different thicknesses of a lithium disilicate glass-ceramic were characterised using profilometry prior to biaxial flexure strength (BFS) determination.

  8. The effect of silane applied to glass ceramics on surface structure and bonding strength at different temperatures

    Science.gov (United States)

    Eraslan, Oguz

    2016-01-01

    PURPOSE To evaluate the effect of various surface treatments on the surface structure and shear bond strength (SBS) of different ceramics. MATERIALS AND METHODS 288 specimens (lithium-disilicate, leucite-reinforced, and glass infiltrated zirconia) were first divided into two groups according to the resin cement used, and were later divided into four groups according to the given surface treatments: G1 (hydrofluoric acid (HF)+silane), G2 (silane alone-no heat-treatment), G3 (silane alone-then dried with 60℃ heat-treatment), and G4 (silane alone-then dried with 100℃ heat-treatment). Two different adhesive luting systems were applied onto the ceramic discs in all groups. SBS (in MPa) was calculated from the failure load per bonded area (in N/mm2). Subsequently, one specimen from each group was prepared for SEM evaluation of the separated-resin–ceramic interface. RESULTS SBS values of G1 were significantly higher than those of the other groups in the lithium disilicate ceramic and leucite reinforced ceramic, and the SBS values of G4 and G1 were significantly higher than those of G2 and G3 in glass infiltrated zirconia. The three-way ANOVA revealed that the SBS values were significantly affected by the type of resin cement (Pacid etching. The surface topography of ceramics was affected by surface treatments. PMID:27141250

  9. Technical evaluation panel summary report. Ceramic and glass immobilization options fissile materials disposition program

    Energy Technology Data Exchange (ETDEWEB)

    Myers, B. R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Brummond, W. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Armantrout, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Shaw, H. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jantzen, C. M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Jostons, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); McKibben, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Strachan, D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Vienna, J. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    1997-12-23

    This report documents the results of a technical evaluation of the merits of ceramic and glass immobilization forms for the disposition of surplus weapons-useable plutonium. The evaluation was conducted by a Technical Evaluation Panel (TEP), whose members were selected to cover a relevant range of scientific and technical expertise and represented each of the technical organizations involved in the Plutonium Immobilization Program. The TEP held a formal review at Lawrence Liver-more National Laboratory (LLNL) from July 2%August 1, 1997. Following this review, the TEP documented the review and its evaluation of the two immobilization technologies in this report to provide a technical basis for a recommendation by LLNL to the Department of Energy (DOE) for the preferred immobilization form. The comparison of the glass and ceramic forms and manufacturing processes was a tremendous challenge to the TEP. The two forms and their processes are similar in many ways. The TEP went to great effort to accurately assess what were, in many cases, fine details of the processes, unit operations, and the glass and ceramic forms themselves. The set of criteria used by the Fissile Materials Disposition Program (FMDP) in past screenings and down-selections was used to measure-the two options. One exception is that the TEP did not consider criteria that were largely nontechnical (namely international impact, public acceptance, and effects on other : DOE programs). The TEP' s measures and assessments are documented in detail. Care was taken to ensure that the data used were well documented and traceable to their source. Although no final conclusion regarding the preferred form was reached or explicitly stated in this report (this was not within the TEP' s charter), no "show stoppers" were identified for either form. Both forms appear capable of satisfying all the criteria, as interpreted by the TEP. The TEP identified a number of distinct and quantifiable differences between

  10. Spectroscopic and structural characterization of transparent fluorogermanate glass ceramics with LaF3:Tm3+ nanocrystals for optical amplifications

    International Nuclear Information System (INIS)

    Highlights: • Transparent fluorogermanate GC containing LaF3 nanocrystals have been fabricated. • The reduced Ω2 (3.79) in GC indicates the change in ligand environment around Tm3+. • The GC has potential applications for lasers and amplifiers at 1.2 and 1.46 μm. - Abstract: Transparent Tm3+-activated glass ceramics (GC) with ∼26% LaF3 nanocrystallites were developed from the 50GeO2–22Al2O3201313LaF3–15LiF (mol%) glass system. Upon excitation at 468 and 688 nm, GC with 0.3 mol% Tm3+-doping (GC0.3Tm) reveals remarkably enhanced luminescence within 600–850 nm range. This could be ascribed to the change in ligand environment around Tm3+ as evidenced by the decrease of Ω2 from 4.32 (PG0.3Tm) to 3.79 (GC0.3Tm) after ceramming. The concurrent intense infrared emission at ∼1.2 and 1.46 μm exhibits a respective full width at half maximum of 76 and 106 nm, mean decay time of 229 and 467 μs. The stimulated emission cross sections and gain parameters were evaluated using radiative parameters derived from Judd–Ofelt (J–O) analysis. Further discussions on the local structure around rare earth ions are based on Eu3+ as a probe. For GC with 0.05 mol% Eu3+-doping (GC0.05Eu), the obvious stark splitting and significantly (6-fold) enhanced emission originating from the excited Eu3+:5D3→1 states is consistent with the red shift of diffraction peaks, revealing the partition of Eu3+ into LaF3 nanocrystals

  11. Investigating in vitro bioactivity and magnetic properties of the ferrimagnetic bioactive glass-ceramic fabricated using soda-lime-silica waste glass

    Science.gov (United States)

    Abbasi, M.; Hashemi, B.; Shokrollahi, H.

    2014-04-01

    The main purpose of the current research is the production and characterization of a ferrimagnetic bioactive glass-ceramic prepared through the solid-state reaction method using soda-lime-silica waste glass as the main raw material. In comparison with the conventional route, that is, the melt-quenching and subsequent heat treatment, the present work is an economical technique. Structural, thermal and magnetic properties of the samples were examined by X-ray diffraction (XRD), differential thermal analysis (DTA) and vibrating sample magnetometer (VSM). The in vitro test was utilized to assess the bioactivity level of the samples by Hanks' solution as simulated body fluid (SBF). The apatite surface layer formation was examined by the scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). The calcium ion concentration in the solutions was measured by atomic absorption spectroscopy (AAS). VSM results revealed that with the addition of 5-20 wt% strontium hexaferrite to bioactive glass-ceramics, the ferrimagnetic bioactive glass-ceramics with hysteresis losses between 7024 and 75,852 erg/g were obtained. The in vitro test showed that the onset formation time of hydroxyapatite layer on the surface of the samples was 14 days and after 30 days, this layer was completed.

  12. Glass-based confined structures enabling light control

    Energy Technology Data Exchange (ETDEWEB)

    Chiappini, Andrea; Normani, Simone; Chiasera, Alessandro [IFN–CNR CSMFO Lab., and FBK Photonics Unit via alla Cascata 56/C Povo, 38123 Trento (Italy); Lukowiak, Anna [Institute of Low Temperature and Structure Research PAS, Okolna St. 2, 50-422 Wroclaw (Poland); Vasilchenko, Iustyna [IFN–CNR CSMFO Lab., and FBK Photonics Unit via alla Cascata 56/C Povo, 38123 Trento (Italy); Dipartimento di Fisica, Università di Trento, via Sommarive 14 Povo, 38123Trento (Italy); Ristic, Davor [Institut Ruđer Bošković, Bijenička cesta 54, 10000 Zagreb (Croatia); Boulard, Brigitte [IMMM, CNRS Equipe Fluorures, Université du Maine, Av. Messiaen, 72085 Le Mans cedex 9 (France); Dorosz, Dominik [Department of Power Engineering, Photonics and Lighting Technology, Bialystok University of Technology, Wiejska Street 45D, 15-351 Bialystok (Poland); Scotognella, Francesco [Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Giovanni Pascoli, 70/3, 20133, Milan (Italy); Politecnico di Milano, Dipartimento di Fisica and Istituto di Fotonica e Nanotecnologie CNR, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Vaccari, Alessandro [FBK -CMM, ARES Unit, 38123 Trento (Italy); Taccheo, Stefano [College of Engineering, Swansea University, Singleton Park, SA2 8PP, Swansea (United Kingdom); Pelli, Stefano; Righini, Giancarlo C. [IFAC - CNR, MiPLab., 50019 Sesto Fiorentino (Italy); Museo Storico della Fisica e Centro di Studi e Ricerche “Enrico Fermi”, Piazza del Viminale 1, 00184 Roma (Italy); Conti, Gualtiero Nunzi [IFAC - CNR, MiPLab., 50019 Sesto Fiorentino (Italy); Ramponi, Roberta [Politecnico di Milano, Dipartimento di Fisica and Istituto di Fotonica e Nanotecnologie CNR, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); and others

    2015-04-24

    When a luminescent ion is confined in a system characterized by one or more specific properties such as spatial size, geometrical dimension and shape, refractive index, local crystal field, cut-off vibrational energy and so on, it's possible to control its emission. The control of branching ratios as a function of the composition, the luminescence enhancement induced by a photonic crystal, or the laser action in a microresonator, are well known examples of light control. Photonic glass-based structures are extremely viable systems to exploit the above mentioned properties and in our research team we have successfully fabricated luminescent photonic structures by different techniques, including sol-gel, rf sputtering, drawing, melting, and physical vapour deposition. Here we will discuss some of them with the aim to make the reader aware of the chemical-physical properties related to each specific system. We will demonstrate that glass ceramic waveguides in some cases present superior spectroscopic properties in respect to the parent glass, that compositional properties can play a positive role in reducing luminescence quenching and in developing novel planar waveguides and fibers, that colloids allow to obtain high internal quantum efficiency and that photonic crystals, microcavities and microresonators can enable the handling of the rare earth luminescence. Finally, the pros and cons of the systems and of the different techniques employed for their fabrication will be discussed and some perspectives concerning the glass photonics will be proposed looking at both possible applications and investigation of physical properties.

  13. Effect of calcium fluoride on sintering behaviour of SiO2-CaO-Na2O-MgO glass-ceramic system

    Directory of Open Access Journals (Sweden)

    Bahman Mirhadi

    2012-09-01

    Full Text Available The crystallization characteristics of glasses based on the SiO2-CaO-Na2O-MgO (SCNM system containing calcium fluoride (CaF2 have been investigated by differential thermal analysis (DTA, X-ray diffraction (XRD and scanning electron microscopy (SEM. The partial replacement of CaO by CaF2 in the studied glass-ceramics led to the development of different crystalline phase assemblages, including wollastonite and diopside using various heat-treatment processes. With the increase of CaF2 content, the crystallization temperature of the glass and the strength of the crystallization peak temperature decreases. Addition of CaF2 up to 6.0 mol%, as expected, improved the sinterability. This sample reached to maximum density by sintering at 950 °C.

  14. An Insulating Glass Knowledge Base

    Energy Technology Data Exchange (ETDEWEB)

    Michael L. Doll; Gerald Hendrickson; Gerard Lagos; Russell Pylkki; Chris Christensen; Charlie Cureija

    2005-08-01

    This report will discuss issues relevant to Insulating Glass (IG) durability performance by presenting the observations and developed conclusions in a logical sequential format. This concluding effort discusses Phase II activities and focuses on beginning to quantifying IG durability issues while continuing the approach presented in the Phase I activities (Appendix 1) which discuss a qualitative assessment of durability issues. Phase II developed a focus around two specific IG design classes previously presented in Phase I of this project. The typical box spacer and thermoplastic spacer design including their Failure Modes and Effect Analysis (FMEA) and Fault Tree diagrams were chosen to address two currently used IG design options with varying components and failure modes. The system failures occur due to failures of components or their interfaces. Efforts to begin quantifying the durability issues focused on the development and delivery of an included computer based IG durability simulation program. The focus/effort to deliver the foundation for a comprehensive IG durability simulation tool is necessary to address advancements needed to meet current and future building envelope energy performance goals. This need is based upon the current lack of IG field failure data and the lengthy field observation time necessary for this data collection. Ultimately, the simulation program is intended to be used by designers throughout the current and future industry supply chain. Its use is intended to advance IG durability as expectations grow around energy conservation and with the growth of embedded technologies as required to meet energy needs. In addition the tool has the immediate benefit of providing insight for research and improvement prioritization. Included in the simulation model presentation are elements and/or methods to address IG materials, design, process, quality, induced stress (environmental and other factors), validation, etc. In addition, acquired data

  15. Equivalent thermal history reconstruction from a partially crystallized glass-ceramic sensor array

    Science.gov (United States)

    Heeg, Bauke

    2015-11-01

    The basic concept of a thermal history sensor is that it records the accumulated exposure to some unknown, typically varying temperature profile for a certain amount of time. Such a sensor is considered to be capable of measuring the duration of several (N) temperature intervals. For this purpose, the sensor deploys multiple (M) sensing elements, each with different temperature sensitivity. At the end of some thermal exposure for a known period of time, the sensor array is read-out and an estimate is made of the set of N durations of the different temperature ranges. A potential implementation of such a sensor was pioneered by Fair et al. [Sens. Actuators, A 141, 245 (2008)], based on glass-ceramic materials with different temperature-dependent crystallization dynamics. In their work, it was demonstrated that an array of sensor elements can be made sensitive to slight differences in temperature history. Further, a forward crystallization model was used to simulate the variations in sensor array response to differences in the temperature history. The current paper focusses on the inverse aspect of temperature history reconstruction from a hypothetical sensor array output. The goal of such a reconstruction is to find an equivalent thermal history that is the closest representation of the true thermal history, i.e., the durations of a set of temperature intervals that result in a set of fractional crystallization values which is closest to the one resulting from the true thermal history. One particular useful simplification in both the sensor model as well as in its practical implementation is the omission of nucleation effects. In that case, least squares models can be used to approximate the sensor response and make reconstruction estimates. Even with this simplification, sensor noise can have a destabilizing effect on possible reconstruction solutions, which is evaluated using simulations. Both regularization and non-negativity constrained least squares

  16. Glass-Ceramic Material from the SiO2-Al2O3-CaO System Using Sugar-Cane Bagasse Ash (SCBA)

    International Nuclear Information System (INIS)

    Brazil is the world's largest producer of alcohol and sugar from sugarcane. Currently, sugarcane bagasse is burned in boilers to produce steam and electrical energy, producing a huge volume of ash. The major component of the ash is SiO2, and among the minor components there are some mineralizing agents or fluxing. Published works have shown the potential of transforming silicate-based residues into glass-ceramic products of great utility. This work reports the research results of SCBA use to produce glass-ceramics with wollastonite, rankinite and gehlenite as the major phases. These silicates have important applications as building industry materials, principally wollastonite, due to their special properties: high resistance to weathering, zero water absorption, and hardness among others. The glasses (frits) were prepared mixing ash, calcium carbonate and sodium or potassium carbonates as flux agents, in different concentrations. X-ray fluorescence was used to determine the chemical composition of the glasses and their crystallization was assessed by using thermal analysis (DTA/DSC/TGA) and X-ray diffraction. The crystallization kinetics was evaluated using the Kissinger method, giving activation energies ranging from 200 to 600 kJ/mol.

  17. Enhanced upconversion emission in crystallization-controllable glass-ceramic fiber containing Yb3+-Er3+ codoped CaF2 nanocrystals

    Science.gov (United States)

    Peng, Wencai; Fang, Zaijin; Ma, Zhijun; Qiu, Jianrong

    2016-10-01

    Functional nanocrystal-containing materials have been a hot topic in recent years. However, few researches have focused on functional nanocrystals contained in optical glass fibers. In this research, transparent CaF2 glass-ceramic was prepared by a melt-quenching method. Greatly enhanced upconversion luminescence was observed after heat treatment. By applying a novel method called melt-in-tube, precursor fiber free of crystals was fabricated at the drawing temperature where the clad was softened while the core was melted. Glass-ceramic fiber with fiber core containing Yb3+-Er3+ codoped CaF2 nanocrystals was obtained after heat treatment at a relatively low temperature. Electron probe micro-analyzer measurement shows no obvious element diffusion between the core and clad. Greatly enhanced upconversion emission was detected in the glass-ceramic fiber excited by a 980 nm laser, suggesting the developed glass-ceramic fiber is a promising material for upconversion laser.

  18. Intense blue up-conversion luminescence in Tm3+/Yb3+ codoped oxyfluoride glass-ceramics containing beta-PbF2 nanocrystals.

    Science.gov (United States)

    Zhang, Junjie; Duan, Zhongchao; He, Dongbing; Dai, Shixun; Zhang, Liyan; Hu, Lili

    2005-12-01

    Up-conversion luminescence properties of a Tm3+/Yb3+ codoped oxyfluoride glass-ceramics under 980 nm excitation are investigated. Intense blue emission centered at 476 nm, corresponding to 1G4-->3H6 transitions of Tm3+ was simultaneously observed in the transparent oxyfluoride glass ceramics at room temperature. The intensity of the blue up-conversion luminescence in a 1 mol% YbF3-containing glass-ceramic was found to be about 40 times stronger than that in the precursor oxyfluoride glass. The reason for the intense Tm3+ up-conversion luminescence in the oxyfluoride glass-ceramics is discussed. The dependence of up-conversion intensities on excitation power and possible up-conversion mechanism are also evaluated. PMID:16095958

  19. Ultraviolet-to-visible downconversion luminescence in solgel oxyfluoride glass ceramics containing Eu³⁺:GdF₃ nanocrystals.

    Science.gov (United States)

    Szpikowska-Sroka, Barbara; Zur, Lidia; Czoik, Rozalia; Goryczka, Tomasz; Ządło, Maria; Pisarski, Wojciech A

    2014-06-01

    GdF3 nanocrystals doped with Eu3+ ions in oxyfluoride glass ceramics were prepared by a solgel method. The structural properties were examined by x-ray diffraction measurements. The effects of gadolinium codoping on europium emission in the prepared solgel glasses and glass ceramics have been studied. The emission bands originating from the 5D0 state of Eu3+ ions are enhanced under excitation of Gd3+ ions by 273 nm line. The electric dipole 5D0→7F2 transitions were dominant in the samples before heat treatment, whereas magnetic dipole 5D0→7F1 transitions had a higher probability in the samples after annealing. The luminescence lifetime for the 5D0 level of Eu3+ ions in the samples after excitation at 273 nm is long lived in comparison to excitation at 393 nm and increased to 190%. Energy transfer from Gd3+ to Eu3+ was observed. PMID:24876007

  20. Effect of TiO2 on Crystallization,Microstructure and Mechanical Properties of Glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    Jian YANG; Shen-gen ZHANG; Bo LIU; De-an PAN; Chun-li WU; Alex AVOLINSKY

    2015-01-01

    The effect of TiO2 addition to the stainless steel slag glass-ceramics was studied.Different mass percenta-ges of TiO2 were added to four samples of the parent glass made from stainless steel slag and cullet.The tempera-tures of nucleation and crystallization were determined by differential scanning calorimetry (DSC).According to X-ray diffraction (XRD)and scanning electron microscopy (SEM)analysis,adding TiO2 refined grains and restricted the formation of the akermanite phase by capturing Ca2+ to form the perovskite phase.Diopside was the main crystal phase of the glass-ceramics.The bending strength and Vickers hardness increased with the addition of TiO2 .The op-timal amount of TiO2 was 7 mass%,and the highest bending strength and Vickers hardness were 144.6 MPa and 6.26 GPa,respectively.

  1. Cubic to tetragonal phase transition of Tm{sup 3+} doped nanocrystals in oxyfluoride glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yiming; Fu, Yuting; Shi, Yahui; Zhang, Xiaoyu; Yu, Hua, E-mail: zhaolj@nankai.edu.cn, E-mail: yuhua@nankai.edu.cn [The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics, Nankai University, Tianjin 300071 (China); Zhao, Lijuan, E-mail: zhaolj@nankai.edu.cn, E-mail: yuhua@nankai.edu.cn [The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics, Nankai University, Tianjin 300071 (China); Applied Physics School of TEDA, Nankai University, Tianjin 300457 (China)

    2016-02-15

    Tm{sup 3+} ions doped β-PbF{sub 2} nanocrystals in oxyfluoride glass ceramics with different doping concentrations and thermal temperatures are prepared by a traditional melt-quenching and thermal treatment method to investigate the structure and the phase transition of Tm{sup 3+} doped nanocrystals. The structures are characterized by X-ray diffraction Rietveld analysis and confirmed with numerical simulation. The phase transitions are proved further by the emission spectra. Both of the doping concentration and thermal temperature can induce an O{sub h} to D{sub 4h} site symmetry distortion and a cubic to tetragonal phase transition. The luminescence of Tm{sup 3+} doped nanocrystals at 800 nm was modulated by the phase transition of the surrounding crystal field.

  2. Cubic to tetragonal phase transition of Tm3+ doped nanocrystals in oxyfluoride glass ceramics

    Directory of Open Access Journals (Sweden)

    Yiming Li

    2016-02-01

    Full Text Available Tm3+ ions doped β-PbF2 nanocrystals in oxyfluoride glass ceramics with different doping concentrations and thermal temperatures are prepared by a traditional melt-quenching and thermal treatment method to investigate the structure and the phase transition of Tm3+ doped nanocrystals. The structures are characterized by X-ray diffraction Rietveld analysis and confirmed with numerical simulation. The phase transitions are proved further by the emission spectra. Both of the doping concentration and thermal temperature can induce an Oh to D4h site symmetry distortion and a cubic to tetragonal phase transition. The luminescence of Tm3+ doped nanocrystals at 800 nm was modulated by the phase transition of the surrounding crystal field.

  3. Enhanced broadband near-infrared luminescence from Ni in Bi/Ni-doped transparent glass ceramics

    International Nuclear Information System (INIS)

    Spectral properties of Bi/Ni-doped transparent MgO-Al2O3-Ga2O3-SiO2-TiO2 glass ceramics (GCs) containing spinel solution nanocrystals were investigated. The emission intensity of Ni in Bi/Ni-doped GCs was about 4 times stronger than that of Ni-doped GCs due to energy transfer from Bi to Ni. The Bi/Ni-doped GCs with 0.75 mol% Bi2O3 concentration exhibited a near-infrared emission with full width at half maximum of about 270 nm and a fluorescent lifetime of about 350 μs, making them very promising for applications in broadband optical amplifiers and tunable lasers.

  4. Enhanced broadband near-infrared luminescence from Ni in Bi/Ni-doped transparent glass ceramics

    Science.gov (United States)

    Wu, Botao; Ruan, Jian; Qiu, Jianrong; Zeng, Heping

    2009-07-01

    Spectral properties of Bi/Ni-doped transparent MgO-Al2O3-Ga2O3-SiO2-TiO2 glass ceramics (GCs) containing spinel solution nanocrystals were investigated. The emission intensity of Ni in Bi/Ni-doped GCs was about 4 times stronger than that of Ni-doped GCs due to energy transfer from Bi to Ni. The Bi/Ni-doped GCs with 0.75 mol% Bi2O3 concentration exhibited a near-infrared emission with full width at half maximum of about 270 nm and a fluorescent lifetime of about 350 µs, making them very promising for applications in broadband optical amplifiers and tunable lasers.

  5. Enhanced broadband near-infrared luminescence from Ni in Bi/Ni-doped transparent glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wu Botao; Zeng Heping [State Key Laboratory of Precision Spectroscopy and Department of Physics, East China Normal University, Shanghai 200062 (China); Ruan Jian [Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China) and Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Qiu Jianrong, E-mail: botao.wu@yahoo.com.c [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China)

    2009-07-07

    Spectral properties of Bi/Ni-doped transparent MgO-Al{sub 2}O{sub 3}-Ga{sub 2}O{sub 3}-SiO{sub 2}-TiO{sub 2} glass ceramics (GCs) containing spinel solution nanocrystals were investigated. The emission intensity of Ni in Bi/Ni-doped GCs was about 4 times stronger than that of Ni-doped GCs due to energy transfer from Bi to Ni. The Bi/Ni-doped GCs with 0.75 mol% Bi{sub 2}O{sub 3} concentration exhibited a near-infrared emission with full width at half maximum of about 270 nm and a fluorescent lifetime of about 350 mus, making them very promising for applications in broadband optical amplifiers and tunable lasers.

  6. Glass-ceramic sealant for solid oxide fuel cells application: Characterization and performance in dual atmosphere

    Science.gov (United States)

    Sabato, A. G.; Cempura, G.; Montinaro, D.; Chrysanthou, A.; Salvo, M.; Bernardo, E.; Secco, M.; Smeacetto, F.

    2016-10-01

    A glass-ceramic composition was designed and tested for use as a sealant in solid oxide fuel cell (SOFC) planar stack design. The crystallization behaviour was investigated by calculating the Avrami parameter (n) and the activation energy for crystallization (Ec) was obtained. The calculated values for n and Ec were 3 and 413.5 kJ/mol respectively. The results of thermal analyses indicate that this composition shows no overlap between the sintering and crystallization stages and thus an almost pore-free sealant can be deposited and sintered at 850 °C in air for 30 min. A gas tightness test has been carried out at 800 °C for 1100 h in dual atmosphere (Ar-H2 and air) without recording any leakage. Morphological and crystalline phase analyses were conducted prior and following tests in dual atmospheres in order to assess the compatibility of the proposed sealant with the metallic interconnect.

  7. Cubic to tetragonal phase transition of Tm3+ doped nanocrystals in oxyfluoride glass ceramics

    Science.gov (United States)

    Li, Yiming; Zhao, Lijuan; Fu, Yuting; Shi, Yahui; Zhang, Xiaoyu; Yu, Hua

    2016-02-01

    Tm3+ ions doped β-PbF2 nanocrystals in oxyfluoride glass ceramics with different doping concentrations and thermal temperatures are prepared by a traditional melt-quenching and thermal treatment method to investigate the structure and the phase transition of Tm3+ doped nanocrystals. The structures are characterized by X-ray diffraction Rietveld analysis and confirmed with numerical simulation. The phase transitions are proved further by the emission spectra. Both of the doping concentration and thermal temperature can induce an Oh to D4h site symmetry distortion and a cubic to tetragonal phase transition. The luminescence of Tm3+ doped nanocrystals at 800 nm was modulated by the phase transition of the surrounding crystal field.

  8. Kinetic neutron diffraction and SANS studies of phase formation in bioactive machinable glass ceramics

    International Nuclear Information System (INIS)

    Bioactive fluormica-fluorapatite glass-ceramic materials offer a very encouraging solution to the problem of efficient restoration and reconstruction of hard tissues. To produce material with the desired crystalline phases, a five-stage heat treatment must be performed. This thermal processing has a large impact on the microstructure and ultimately the final mechanical properties of the materials. We have examined the thermal processing of one of our most promising machinable biomaterials, using time-resolved small angle neutron scattering and neutron diffraction to study the nucleation and growth of crystallites. The processing route had already been optimized by studying the properties of quenched samples using x-ray diffraction, mechanical measurements and differential thermal analysis. However these results show that the heat treatment can be further optimized in terms of crystal nucleation, and we show that these techniques are the only methods by which a truly optimized thermal processing route may be obtained

  9. Gel-cast glass-ceramic tissue scaffolds of controlled architecture produced via stereolithography of moulds.

    Science.gov (United States)

    Chopra, K; Mummery, P M; Derby, B; Gough, J E

    2012-12-01

    Two glass-ceramic scaffolds with a simple cubic structure of 500 µm square ligaments and square channels of width 400 or 600 µm have been fabricated by gel-casting into moulds produced by stereolithography, followed by mould removal, polymer burnout and sintering. The scaffolds have crushing strengths of 41 ± 14 and 17 ± 5 Mpa, respectively. Using a method of assembling discrete slices of scaffold, we are able to study cell behaviour within a scaffold by disassembly. Both scaffold structures were seeded with primary human osteoblasts and these penetrate, adhere, spread and proliferate on the scaffold structure. The larger channel diameter scaffold shows a greater cell population (despite its smaller surface area) and more pronounced production of ECM components (collagen and mineralization) with increased time in culture. Studies of sectioned scaffolds show that cell density and ECM production decrease with depth and that the difference between the two scaffold architectures is maintained.

  10. The recycling of incinerated sewage sludge ash as a raw material for CaO-Al2O3-SiO2-P2O5 glass-ceramic production.

    Science.gov (United States)

    Zhang, Zhikun; Zhang, Lei; Yin, Yulei; Liang, Xuanye; Li, Aimin

    2015-01-01

    In this paper, the recycling of incinerated sewage sludge ash (ISSA) into glass-ceramic materials by a two-stage sintering cycle of nucleation stage and crystallization stage without any pressure and binder is presented. The parent glasses were subjected to the following nucleation/crystallization temperature and time level: (A) 790°C, 1.0 h/870°C, 1.0-3.0 h; (B) 790°C, 1.0 h/945°C, 1.0-3.0 h and (C) 790°C, 1.0 h/1065°C, 1.0-3.0 h. X-ray power diffraction analysis results revealed that multiple crystalline phases coexisted in the glass-ceramic materials and the crystalline phase compositions were more affected by crystallization temperature than crystallization time. Scanning electron microscopy analysis showed an interlocking microstructure of glass phases and crystals with different sizes and spatial distribution. The glass-ceramics crystallized at 945°C for 2.0 h exhibited optimal properties of density of 2.88±0.08 g/cm3, compression strength of 247±12 MPa, bending strength of 118±14 MPa and water absorption of 0.42±0.04. The leaching concentrations of heavy metals were far lower than the limits required by the regulatory standard of EPA. This paper provides a feasible, low-cost and promising method to produce ISSA-based glass-ceramics and highlights the principal characteristics that must be taken into account to use ISSA correctly in glass-ceramics. PMID:25358410

  11. Autoradiographic determination of marginal leakage of a pressed glass ceramic inlay.

    Science.gov (United States)

    Canay, R S; Hersek, N E; Uzun, G; Ercan, M T

    1997-09-01

    The marginal integrity and microleakage of pressed glass ceramic inlays were evaluated using autoradiography. IPS/Empress ceramic inlays were fabricated for 10 human molar mandibular teeth. After adjusting the inlays, they were etched with 37% phosphoric acid gel for 30 s and silanized with Monobond S for 30 s. Before cementation with dual cure resin cement the inlays and cavity walls were gently covered with a thin layer of bonding agent. When the cementation process was completed the samples were cycled 300 times between a 55 degrees C hot bath and a 5 degrees C cold bath. The samples were placed in each bath for 60 s, with 5 s intervals between immersions, then the specimens were immersed in an aqueous solution of Ca-45. After 24 h the inlay and tooth assemblies were removed, rinsed with water and placed in cold-cured acrylic resin, then sectioned through the long axis for autoradiographic analysis. According to the penetration of Ca-45, the microleakage level was scored for each section. The results indicated slight penetration of Ca-45 on autoradiographic films.

  12. Process for strengthening aluminum based ceramics and material

    Energy Technology Data Exchange (ETDEWEB)

    Moorhead, Arthur J.; Kim, Hyoun-Ee

    1998-12-01

    A process for strengthening aluminum based ceramics is provided. A gaseous atmosphere consisting essentially of silicon monoxide gas is formed by exposing a source of silicon to an atmosphere consisting essentially of hydrogen and a sufficient amount of water vapor. The aluminum based ceramic is exposed to the gaseous silicon monoxide atmosphere for a period of time and at a temperature sufficient to produce a continuous, stable silicon-containing film on the surface of the aluminum based ceramic that increases the strength of the ceramic.

  13. Use of thin film transistor liquid crystal display (TFT-LCD) waste glass in the production of ceramic tiles.

    Science.gov (United States)

    Lin, Kae-Long

    2007-09-01

    In this study, we employ the following operating conditions: varied pressure (25 kgf/cm(2)), sintering temperature (900-1200 degrees C), sintering time (6h), percentage of thin film transistor liquid crystal display (TFT-LCD) waste glass by weight (0-50%) and temperature rising at a rate of 5 degrees C/min, to fabricate clay tiles. The sintering characteristics of the clay blended with TFT-LCD waste glass tiles are examined to evaluate the feasibility of the reuse of TFT-LCD waste glass. TFT-LCD waste glass contains large amounts of glass. The TCLP leaching concentrations all met the ROC EPAs current regulatory thresholds. The addition of TFT-LCD waste glass to the mixture, increased the apparent weight loss. The incorporation of 50% TFT-LCD waste glass resulted in a significant increase in the porosity ratio of the specimens compared to the porosity ratio of the ceramic tile containing TFT-LCD waste glass. The main constituent in both the clay tile and the clay with TFT-LCD waste glass samples is quartz. Increasing the temperature resulted in an increase in the flexural strength and resistance to abrasion in the tiles. The porosity ratio decreases as shrinkage increases. The relation between the porosity ratio and the hardness of the tiles used in the study is also shown.

  14. The effect of hydrothermal hot-pressing parameters on the fabrication of porous ceramics using waste glass

    Science.gov (United States)

    Matamoros-Veloza, Z.; Yanagisawa, K.; Rendón-Angeles, J. C.; Oishi, S.

    2004-04-01

    The effect of varying hydrothermal hot-pressing (HHP) parameters on the expansion of waste glass powder was investigated by conventional heat treatment. Glass ceramic porous materials were prepared by hydrothermal hot pressing under standard conditions at 200 °C, for 2 h at a constant uniaxial pressure of 20 MPa, while varying experimental variables such as glass particle size, water content, reaction interval, temperature and heating rate. SEM investigation showed the presence of a new glass phase, which incorporated water in its structure. The degree of reactivity attainable between glass particles and water seems to control the expansion process during heating of HHP glass compacts. It was found that the expansion process is independent of experimental parameters such as reaction time, temperature and heating rate, but does depend on the particle size and water content. During the heat treatment, the glass foaming process was preceded by decomposition of the new glass phase in the HHP compacts. A minimum apparent density of 0.40 g cm-3 was obtained on specimens prepared with low water content (5 wt%) and medium particle size (39-45 µm). X-ray diffraction patterns of the expanded glasses revealed the formation of SiO2 (agr-cristobalite and quartz) and CaSiO3 (wollastonite).

  15. Use of thin film transistor liquid crystal display (TFT-LCD) waste glass in the production of ceramic tiles.

    Science.gov (United States)

    Lin, Kae-Long

    2007-09-01

    In this study, we employ the following operating conditions: varied pressure (25 kgf/cm(2)), sintering temperature (900-1200 degrees C), sintering time (6h), percentage of thin film transistor liquid crystal display (TFT-LCD) waste glass by weight (0-50%) and temperature rising at a rate of 5 degrees C/min, to fabricate clay tiles. The sintering characteristics of the clay blended with TFT-LCD waste glass tiles are examined to evaluate the feasibility of the reuse of TFT-LCD waste glass. TFT-LCD waste glass contains large amounts of glass. The TCLP leaching concentrations all met the ROC EPAs current regulatory thresholds. The addition of TFT-LCD waste glass to the mixture, increased the apparent weight loss. The incorporation of 50% TFT-LCD waste glass resulted in a significant increase in the porosity ratio of the specimens compared to the porosity ratio of the ceramic tile containing TFT-LCD waste glass. The main constituent in both the clay tile and the clay with TFT-LCD waste glass samples is quartz. Increasing the temperature resulted in an increase in the flexural strength and resistance to abrasion in the tiles. The porosity ratio decreases as shrinkage increases. The relation between the porosity ratio and the hardness of the tiles used in the study is also shown. PMID:17367925

  16. Use of glass ceramic as a structural material for a high-precision space telescope

    Science.gov (United States)

    Juranek, Hans J.; Kleer, G.; Doell, W.

    1994-09-01

    SILEX is the acronym for Satellite InterLink EXperiment. By this experiment ESA (European Space Agency) starts the optical communication technique in space. Similar to the usual RF-communication technique the optical technique requires antennas for transmitting and receiving signals. Such antennas are telescopes. For Silex a two mirror telescope of an aperture of 250 mm was specified. To gain the benefits of optical communication such a telescope must fulfil extreme optical performances, especially concerning the wavefront quality which is strongly governed by the stability of the telescope structure. Thus the structure of SILEX telescope must guarantee a stability of +/- 2 microns over 320 mm in length. This figure must be maintained for 10 years under extreme environmental conditions, this especially concerns temperature, irradiation, ageing and above all launch loads. Looking at this area the glass ceramic ZERODUR was a very promising material to be used as a structural material provided one overcomes the justified concern on its mechanical reliability due to the fact that it is a brittle material similar to glass. This contribution presents solutions of the basic problems in structural design, the means of material and process qualification, and final qualification against launch loads of the critical structural item.

  17. Influence of Waste Ceramics on Melting Behavior of Glass-ceramics%废瓷掺料对微晶玻璃熔融结晶的影响

    Institute of Scientific and Technical Information of China (English)

    林少敏; 王勃; 刘贵深

    2011-01-01

    利用瓷土尾矿、废瓷、粉煤灰等工业废料作为主要原料制备微晶玻璃,不仅能够有效解决工业废弃物的环境污染问题,而且能够实现废弃物的资源化利用。在配方设计中,瓷土尾矿、粉煤灰等固体废料的用量可达原料总量的75%以上。但废瓷粉的掺入会破坏微晶玻璃表层的析晶效果,由于废瓷的种类繁多,其化学组成、所含杂质及烧结温度具有很大的差异性,会对微晶玻璃的熔融结晶产生较大影响。%Using industrial wastes and tailings as main raw materials to manufacturing glass-ceramics,not only can solve the problem of environment pollution,but also can realize the resource utilization of waste materials.In the formula design,the dosage of porcelain clay tailings and fly ash can reach more than 75 % of the total amount of raw materials.Waste ceramics powder can destroy the crystal of crystallite glass surface layer.Because of the chemical composition,impurities and sintering temperature of different kind of waste ceramics have great difference,that has great influence on melting behavior of glass-ceramics.

  18. Enhanced upconversion in Ho{sup 3+}-doped transparent glass ceramics containing BaYbF{sub 5} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Sha [Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Guo, Hai, E-mail: ghh@zjnu.cn [Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004 (China); Wei, Xiantao; Duan, Changkui [Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Yin, Min, E-mail: yinmin@ustc.edu.cn [Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

    2014-08-01

    Novel Ho{sup 3+}-doped transparent oxyfluoride SiO{sub 2}–Al{sub 2}O{sub 3}–Na{sub 2}CO{sub 3}–CaO–BaF{sub 2}–YbF{sub 3} glass ceramics (GC) containing BaYbF{sub 5} nanocrystals were fabricated via melt-quenching technique with subsequent heat treatment. The formation of crystalline fluoride phase was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Compared to precursor glasses, the greatly enhanced green emission (40-fold), new emission band at ultraviolet-blue region and stark splittings of emission in GC, indicate that Ho{sup 3+} enters into BaYbF{sub 5} nanocrystals with low phonon energy. Besides, the origin of the previously unconfirmed emission band at 440–460 nm is clearly identified by measuring spectra from thermally coupled luminescent levels at various temperatures. The outstanding upconversion properties of Ho{sup 3+} in GC may present potential application in all-solid-state upconversion lasers operating in the visible and ultraviolet range. - Highlights: • Novel transparent glass ceramics containing BaYbF{sub 5} nanocrystals were fabricated. • The green upconversion intensity increases greatly (40-fold) in glass ceramics. • The origin of the previously unconfirmed emission is clearly identified in our work.

  19. Surface phenomena in gel-derived glasses and glass-ceramics materials of the CaO-P2O5-SiO2 system

    International Nuclear Information System (INIS)

    Three types of glass ceramics materials of the CaO-P2O-SiO2 system were obtained using the sol gel method and applying calcium nitrate, tetraethyl orthosilicate, and triethyl phosphate as precursors of the respective oxides. The base materials were also modified the addition of 5 mole % Al2O3, using aluminium tri-sec-butoxide as its precursors. Gels were heated up to the temperature 700 grad C. It has been found that after heating these materials contain a glassy phase, hydroxyapatite and wollastonite; there were important differences in the phase compositions as well as in the pore structure of these materials. Materials after treatment were put into simulated body fluid. After a difference time periods the surface changes of these materials were examined using FTIR, scanning electron microscopy (SEM), and X-ray fluorescence analysis in micro-regions (EDAX) methods. It has been found, that the bone-like hydroxyapatite is formed on the surface of gel-derived materials and the time necessary to forming the continual layer of this compound is depend upon the chemical composition of the base materials. On the basis of conducted examinations the attempt of the explanation of the hydroxyapatite formation mechanism was undertaken. The results of our experiments can be interpreted as indicating the bio-activity of obtained gel-derived materials. This means that these materials used as bone implants can be permanently joined to the bone. (authors)

  20. Near-infrared frequency down-conversion and cross-relaxation in Eu2+/Eu3+–Yb3+ doped transparent oxyfluoride glass and glass–ceramics

    International Nuclear Information System (INIS)

    Highlights: • In situ formation of Eu2+ in Eu–Yb3+:SiO2–K2O–BaF2–La2O3–Sb2O3 oxyfluoride glasses. • Demonstrated cooperative energy transfer based UV to NIR frequency down-conversion. • Enhancement of frequency down-conversion is evidenced in glass ceramic counterparts. • Eu3+ reduction to Eu2+ upon ceramization leads an enhancement in Eu2+ → Yb3+ CET. • Eu3+ excitation contribution has been attributed to the cross-relaxation process. - Abstract: In the present work, Eu2+/Eu3+–Yb3+ co-doped SiO2–K2O–BaF2–La2O3–Sb2O3 oxyfluoride glasses were synthesized by conventional melt quenching method to elucidate the cooperative energy transfer (CET) based frequency down conversion from Yb3+ ions under UV excitation. The in situ formation of divalent europium (Eu2+) along with Eu3+ during high temperature synthesis of these glasses under ambient atmosphere has been perceived and was explained through optical basicity model. Frequency down-conversion due to emission of two near infrared photons at around 1 μm from Yb3+ ions has been realized upon excitation of Eu2+ ions under 286 nm and further enhancement of this frequency down-conversion has been observed upon ceramization of these glasses. The precipitation of BaF2 nano-crystals in glass–ceramics causes reduction of Eu3+ ions to Eu2+ ions resulting in an enhancement in the cooperative energy transfer from Eu2+ to Yb3+. The weak contribution of Eu3+ excitation towards Yb3+ emission has been attributed to the cross-relaxation process via 5D0 → 7F6 (Eu3+):2F5/2 → 2F7/2 (Yb3+) route. The donor (Eu2+/Eu3+)–acceptor (Yb3+) concentration has been optimized at 0.5 mol% Eu2O3 and 1.0 mol% Yb2O3 to achieve maximum down-conversion intensity near 1 μm

  1. Interaction study between nuclear waste-glass melt and ceramic melter bellow liner materials

    Science.gov (United States)

    Sengupta, Pranesh

    2011-04-01

    Identification of proper materials for plant scale vitrification furnaces, engaged in immobilization of high level nuclear waste has always been a great challenge. Fast degradation of pour spout materials very often cause problem towards smooth pouring of waste-glass melt in canister and damages bellow kept in between. The present experimental study describes the various reaction products that form due to interaction between waste-glass melt and potential bellow liner materials such as copper, stainless steel and nickel based Superalloys (Alloy 690, 625). The results indicate that copper based material has lesser tendency to form adherent glassy layer.

  2. Interaction study between nuclear waste-glass melt and ceramic melter bellow liner materials

    Energy Technology Data Exchange (ETDEWEB)

    Sengupta, Pranesh, E-mail: praneshsengupta@gmail.com [Materials Science Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2011-04-15

    Identification of proper materials for plant scale vitrification furnaces, engaged in immobilization of high level nuclear waste has always been a great challenge. Fast degradation of pour spout materials very often cause problem towards smooth pouring of waste-glass melt in canister and damages bellow kept in between. The present experimental study describes the various reaction products that form due to interaction between waste-glass melt and potential bellow liner materials such as copper, stainless steel and nickel based Superalloys (Alloy 690, 625). The results indicate that copper based material has lesser tendency to form adherent glassy layer.

  3. FOAM GLASS-CERAMICS AND CYCLIC UTILIZATION OF SOLID WASTE%微晶泡沫玻璃与固体废弃物的循环利用

    Institute of Scientific and Technical Information of China (English)

    张雪峰; 张明星; 李保卫; 贾晓林; 赵鸣; 邓磊波

    2012-01-01

    概述了微晶泡沫玻璃的制备工艺原理及流程,从结构方面讨论了微晶泡沫玻璃的性能及应用,介绍了废玻璃、粉煤灰、尾矿、冶炼渣、硼泥、煤矸石、陶瓷废料等固体废弃物在微晶泡沫玻璃中的应用。%The preparation principle and process flow of foam glass-ceramics is introduced. The properties and applications of foam glass-ceramics are discussed from structure. Using solid waste such as glass waste, fly ash, tailings, metallurgy slag, boron sludge, coal gangue and ceramic waste to produce foam glass-ceramics as raw material is also presented.

  4. From Selenium- to Tellurium-Based Glass Optical Fibers for Infrared Spectroscopies

    Directory of Open Access Journals (Sweden)

    Jacques Lucas

    2013-05-01

    Full Text Available Chalcogenide glasses are based on sulfur, selenium and tellurium elements, and have been studied for several decades regarding different applications. Among them, selenide glasses exhibit excellent infrared transmission in the 1 to 15 µm region. Due to their good thermo-mechanical properties, these glasses could be easily shaped into optical devices such as lenses and optical fibers. During the past decade of research, selenide glass fibers have been proved to be suitable for infrared sensing in an original spectroscopic method named Fiber Evanescent Wave Spectroscopy (FEWS. FEWS has provided very nice and promising results, for example for medical diagnosis. Then, some sophisticated fibers, also based on selenide glasses, were developed: rare-earth doped fibers and microstructured fibers. In parallel, the study of telluride glasses, which can have transmission up to 28 µm due to its atom heaviness, has been intensified thanks to the DARWIN mission led by the European Space Agency (ESA. The development of telluride glass fiber enables a successful observation of CO2 absorption band located around 15 µm. In this paper we review recent results obtained in the Glass and Ceramics Laboratory at Rennes on the development of selenide to telluride glass optical fibers, and their use for spectroscopy from the mid to the far infrared ranges.

  5. From selenium- to tellurium-based glass optical fibers for infrared spectroscopies.

    Science.gov (United States)

    Cui, Shuo; Chahal, Radwan; Boussard-Plédel, Catherine; Nazabal, Virginie; Doualan, Jean-Louis; Troles, Johann; Lucas, Jacques; Bureau, Bruno

    2013-01-01

    Chalcogenide glasses are based on sulfur, selenium and tellurium elements, and have been studied for several decades regarding different applications. Among them, selenide glasses exhibit excellent infrared transmission in the 1 to 15 µm region. Due to their good thermo-mechanical properties, these glasses could be easily shaped into optical devices such as lenses and optical fibers. During the past decade of research, selenide glass fibers have been proved to be suitable for infrared sensing in an original spectroscopic method named Fiber Evanescent Wave Spectroscopy (FEWS). FEWS has provided very nice and promising results, for example for medical diagnosis. Then, some sophisticated fibers, also based on selenide glasses, were developed: rare-earth doped fibers and microstructured fibers. In parallel, the study of telluride glasses, which can have transmission up to 28 µm due to its atom heaviness, has been intensified thanks to the DARWIN mission led by the European Space Agency (ESA). The development of telluride glass fiber enables a successful observation of CO₂ absorption band located around 15 µm. In this paper we review recent results obtained in the Glass and Ceramics Laboratory at Rennes on the development of selenide to telluride glass optical fibers, and their use for spectroscopy from the mid to the far infrared ranges. PMID:23666005

  6. Surface treatments for repair of feldspathic, leucite - and lithium disilicate-reinforced glass ceramics using composite resin.

    Science.gov (United States)

    Neis, Christian Alencar; Albuquerque, Nadine Luísa Guimarães; Albuquerque, Ivo de Souza; Gomes, Erica Alves; Souza-Filho, Celso Bernardo de; Feitosa, Victor Pinheiro; Spazzin, Aloisio Oro; Bacchi, Atais

    2015-01-01

    The aim of this study was to evaluate the efficacy of different surface conditioning methods on the microtensile bond strength of a restorative composite repair in three types of dental ceramics: lithium disilicate-reinforced, leucite-reinforced and feldspathic. Twelve blocks were sintered for each type of ceramic (n=3) and stored for 3 months in distilled water at 37 °C. The bonding surface of ceramics was abraded with 600-grit SiC paper. Surface treatments for each ceramic were: GC (control) - none; GDB - diamond bur #30 µm; GHF - hydrofluoric acid (10%); GT- tribochemical silica coating (45-μm size particles). Treatments were followed by cleaning with phosphoric acid 37% for 20 s + silane + adhesive. The composite resin was used as restorative material. After repair, samples were subjected to thermocycled ageing (10,000 cycles between 5 °C and 55 °C for 30 s). Thereafter, the samples were sectioned into 1.0 mm2 sticks and tested for microtensile bond strength with 0.5 mm/min crosshead speed. Data were compared by two-way ANOVA and Tukey's test (α=0.05). The superficial wear with diamond bur proved to be suitable for feldspathic porcelain and for leucite-reinforced glass ceramic while hydrofluoric acid-etching is indicated for repairs in lithium disilicate-reinforced ceramic; tribochemical silica coating is applicable to leucite-reinforced ceramic. Predominance of adhesive failures was observed (>85% in all groups). In conclusion, the success of surface treatments depends on the type of ceramic to be repaired.

  7. Applications of High Energy Ion Beam Techniques in Environmental Science: Investigation Associated with Glass and Ceramic Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Thevuthasan, Suntharampillai; Shutthanandan, V; Zhang, Yanwen

    2006-02-01

    High energy ion beam capabilities including Rutherford backscattering spectrometry (RBS) and nuclear reaction analysis (NRA) have been very effectively used in environmental science to investigate the ion exchange mechanisms in glass waste forms and the effects of irradiation in glass and ceramic waste forms in the past. In this study, RBS and NRA along with SIMNRA simulations were used to monitor the Na depletion and D and 18O uptake in alumina silicate glasses, respectively, after the glass coupons were exposed to aqueous solution. These results show that the formation of a reaction layer and an establishment of a region where diffusion limited ion exchange occur in these glasses during exposure to silica-saturated solutions. Different regions including reaction and diffusion regions were identified on the basis of the depth distributions of these elements. In the case of ceramics, damage accumulation was studied as a function of ion dose at different irradiation temperatures. A sigmoidal dependence of relative disorder on the ion dose was observed. The defect dechanneling factors were calculated for two irradiated regions in SrTiO? using the critical angles determined from the angular yield curves. The dependence of defect dechanneling parameter on the incident energy was investigated and it was observed that the generated defects are mostly interstitial atoms and amorphous clusters. Thermal recovery experiments were performed to study the damage recovery processes up to a maximum temperature of 870 K.

  8. Analysis of nanostructure and nanochemistry by ASAXS: Accessing phase composition of oxyfluoride glass ceramics doped with Er3+/Yb3+

    Science.gov (United States)

    Haas, Sylvio; Hoell, Armin; Wurth, Roman; Rüssel, Christian; Boesecke, Peter; Vainio, Ulla

    2010-05-01

    Here, we describe the analysis of the nanostructure and average chemical compositions of each phase present in an oxyfluoride glass ceramic, which is composed of fluoride nanocrystals and an oxide glass matrix. The overall composition of the oxyfluoride glass ceramic as prepared is 21.1%SiO26.5%B2O37.0%Al2O321.0%PbF214.3%CdF211.0%YbF30.5%ErF311.0%PbO7.6%CdO(mole%) . Nanocrystals begin to grow at temperatures above the glass transformation temperature at 678 K as observed by x-ray diffraction. We report results from anomalous small-angle x-ray scattering taken at energies of x-ray absorption edges of Er, Yb, Pb, and Cd. By nonlinear regression of the scattering curves obtained from different edges simultaneously, the nanocrystals were found to be describable as polydisperse spheroids. The length of the smaller axis was found to be 6.4±1.4nm while the larger axis was found to be 17.7±3.9nm . By analyzing the scattering contrast as a function of the x-ray energy we found cadmium only in the glass matrix.

  9. Analysis of nanostructure and nanochemistry by ASAXS: Accessing phase composition of oxyfluoride glass ceramics doped with Er3+/Yb3+

    International Nuclear Information System (INIS)

    Here, we describe the analysis of the nanostructure and average chemical compositions of each phase present in an oxyfluoride glass ceramic, which is composed of fluoride nanocrystals and an oxide glass matrix. The overall composition of the oxyfluoride glass ceramic as prepared is 21.1%SiO2 6.5%B2O3 7.0%Al2O3 21.0%PbF2 14.3%CdF2 11.0%YbF3 0.5%ErF3 11.0%PbO 7.6%CdO(mole %). Nanocrystals begin to grow at temperatures above the glass transformation temperature at 678 K as observed by x-ray diffraction. We report results from anomalous small-angle x-ray scattering taken at energies of x-ray absorption edges of Er, Yb, Pb, and Cd. By nonlinear regression of the scattering curves obtained from different edges simultaneously, the nanocrystals were found to be describable as polydisperse spheroids. The length of the smaller axis was found to be 6.4±1.4 nm while the larger axis was found to be 17.7±3.9 nm. By analyzing the scattering contrast as a function of the x-ray energy we found cadmium only in the glass matrix.

  10. Effects of soda-lime-silica waste glass on mullite formation kinetics and micro-structures development in vitreous ceramics.

    Science.gov (United States)

    Marinoni, Nicoletta; D'Alessio, Daniela; Diella, Valeria; Pavese, Alessandro; Francescon, Ferdinando

    2013-07-30

    The effects of soda-lime waste glass, from the recovery of bottle glass cullet, in partial replacement of Na-feldspar for sanitary-ware ceramic production are discussed. Attention is paid to the mullite growth kinetics and to the macroscopic properties of the final output, the latter ones depending on the developed micro-structures and vitrification grade. Measurements have been performed by in situ high temperature X-ray powder diffraction, scanning electron microscopy, thermal dilatometry, water absorption and mechanical testing. Glass substituting feldspar from 30 to 50 wt% allows one (i) to accelerate the mullite growth reaction kinetics, and (ii) to achieve macroscopic features of the ceramic output that comply with the latest technical requirements. The introduction of waste glass leads to (i) a general saving of fuel and reduction of the CO2-emissions during the firing stage, (ii) a preservation of mineral resources in terms of feldspars, and (iii) an efficient management of the bottle glass refuse by readdressing a part of it in the sanitary-ware manufacturing. PMID:23624427

  11. Multi-color persistent luminescence in transparent glass ceramics containing spinel nano-crystals with Mn2+ ions

    Science.gov (United States)

    Zhuang, Yixi; Ueda, Jumpei; Tanabe, Setsuhisa

    2014-11-01

    Transparent inorganic materials showing persistent luminescence can act as cover layer and emergency lighting for security signs in the dark. Herein, we report a Mn2+-activated glass and transparent glass ceramics containing spinel-type Zn1+xGa2-2xGexO4 (0 ≤ x ≤ 1) nano-crystals, which show multi-color persistent luminescence for more than 10 min. The color of persistent luminescence showed a remarkable change from red, to orange, greenish, and green with respect to the increase of annealing temperature. The effect has been explained due to the variation of crystal field strength surrounding the Mn2+ ions.

  12. Effect of glass-ceramic-processing cycle on the metallurgical properties of candidate alloys for actuator housings

    Energy Technology Data Exchange (ETDEWEB)

    Weirick, L.J.

    1982-01-01

    This report summarizes the results from an investigation on the effect of a glass ceramic processing cycle on the metallurgical properties of metal candidates for actuator housings. The cycle consists of a 980/sup 0/C sealing step, a 650/sup 0/C crystallization step and a 475/sup 0/C annealing step. These temperatue excursions are within the same temperature regime as annealing and heat treating processes normally employed for metals. Therefore, the effect of the processing cycle on metallurgical properties of microstructure, strength, hardness and ductility were examined. It was found that metal candidates which are single phase or solid solution alloys (such as 21-6-9, Hastelloy C-276 and Inconel 625) were not affected whereas multiphase or precipitation hardened alloys (such as Inconel 718 and Titanium ..beta..-C) were changed by the processing cycle for the glass ceramic.

  13. Predicting Young’s Modulus of Glass/Ceramic Sealant for Solid Oxide Fuel Cell Considering the Combined Effects of Aging, Micro-Voids and Self-Healing

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenning N.; Sun, Xin; Khaleel, Mohammad A.

    2008-12-01

    We study the temperature dependent Young’s modulus for the glass/ceramic seal material used in Solid Oxide Fuel Cells (SOFCs). With longer heat treatment or aging time during operation, further devitrification may reduce the residual glass content in the seal material while boosting the ceramic crystalline content. In the meantime, micro-voids induced by the cooling process from the high operating temperature to room temperature can potentially degrade the mechanical properties of the glass/ceramic sealant. Upon reheating to the SOFC operating temperature, possible self-healing phenomenon may occur in the glass/ceramic sealant which can potentially restore some of its mechanical properties. A phenomenological model is developed to model the temperature dependent Young’s modulus of glass/ceramic seal considering the combined effects of aging, micro-voids, and possible self-healing. An aging-time-dependent crystalline content model is first developed to describe the increase of the crystalline content due to the continuing devitrification under high operating temperature. A continuum damage mechanics (CDM) model is then adapted to model the effects of both cooling induced micro-voids and reheating induced self-healing. This model is applied to model the glass-ceramic G18, a candidate SOFC seal material previously developed at PNNL. Experimentally determined temperature dependent Young’s modulus is used to validate the model predictions

  14. Ceramics based on calcium pyrophosphate nanopowders

    Directory of Open Access Journals (Sweden)

    Tatiana V. Safronova

    2013-03-01

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

  15. Inorganic wastes in manufacturing of glass-ceramics. Slurry of phosphorous fertilizer production and oil shale ash

    Energy Technology Data Exchange (ETDEWEB)

    Gorokhovsky, A.V.; Mendez-Nonell, J.; Escalante-Garcia, J.I.; Pech-Canul, M.I.; Vargas-Gutierrez, G. [Department of Engineering Ceramics of CINVESTAV-IPN, Unidad Saltillo-Monterrey, km 13.5, Apartado Postal 663, CP 25000, Saltillo, Coahuila (Mexico); Gorokhovsky, V.A.; Mescheryakov, D.V. [Department of Building Materials of Saratov State Technical University, Saratov (Russian Federation)

    2001-11-01

    The use of bicomponent raw material mixtures of industrial wastes to produce pyroxene glass ceramics was investigated. It is shown that oil shale ash from heat power stations can promote the production of crystalline phases and the slurry from phosphorous fertilizer production can provide sufficient concentration of nucleating agents. Mechanical and chemical properties, as well as the structure and crystallization mechanism were characterized. An increase of phosphorous oxide and fluorine concentrations leads to a change of the crystallization mechanism.

  16. Replacement of missing lateral incisors with lithium disilicate glass-ceramic veneer-fixed dental prostheses: a clinical report

    OpenAIRE

    Bissasu, Sami M; Al-houri, Nabil A

    2014-01-01

    Key Clinical Message This report describes the use of lithium disilicate glass-ceramic veneer-fixed dental prostheses in replacing congenitally missing maxillary lateral incisors. This kind of prosthesis has an advantage over a lingual-retainer resin-bonded fixed dental prosthesis in its capability of changing the color and shape of the abutment teeth. The prostheses provided an acceptable esthetics and comfort for the patient.

  17. Flexural strength and microstructure of two lithium disilicate glass ceramics for CAD/CAM restoration in the dental clinic

    OpenAIRE

    Kang, Suk-Ho; Chang, Juhea; Son, Ho-Hyun

    2013-01-01

    Objectives There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent) and Rosetta SM (Hass), and to observe their crystalline structures. Materials and Methods Biaxial flexural strength was tested according to ISO...

  18. 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.

  19. Influence of lead and cadmium fluoride variation on white light emission characteristics in oxyfluoride glasses and glass–ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Gopi, E-mail: sharmagopi28@yahoo.com [Department of Physics, Kanya Maha Vidyalaya, Jalandhar, Punjab 144004 (India); Bagga, Ruchika; Mahendru, Nancy [Department of Physics, Kanya Maha Vidyalaya, Jalandhar, Punjab 144004 (India); Falconieri, Mauro [ENEA, UTAPRAD, C.R.Casaccia, via Anguillarese 301, 00123 Rome (Italy); Achanta, Venu Gopal [Department of Condensed Matter Physics, TIFR, Mumbai (India); Goel, Ashutosh [Department of Material Science and Engineering, Rutgers-The State University of New Jersey, NJ (United States); Rasool, Shaik Nayab; Vijaya, Navooru [Department of Physics, Sri Venkateswara University, Tirupati (India)

    2015-03-15

    The radiative properties of Dy-doped glasses and glass–ceramic phosphors with varying lead and cadmium fluoride content are investigated in the present study for white light emitting applications. The precipitation of cubic lead fluoride phase of 10–18 nm crystallites was determined with the help of x-ray diffraction studies and the nanocrystalline nature was confirmed with scanning electron microscopy studies. The small size of the nanocrystallites enables the fabrication of transparent glass–ceramics which is verified by UV–vis spectroscopic study. The photoluminescence and lifetime measurements indicate towards progressive changes in the Dy{sup 3+} ion surroundings and propose enhanced energy transfers taking place post-heat treatments. Finally, CIE chromaticity coordinates are found to lie in the white region proposing the suitability of the present studied materials for color display devices. - Highlights: • Enhanced energy transfer in glass ceramics. • Depolymerization of network with variation in heavy metal fluoride. • Radiative properties of Dy{sup 3+} doped glass as W-LED.

  20. Effect of Al2O3 Content on Residual Stress and Properties of CAS Glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    XIE Jun; LONG Xinjiang; CHENG Jinshu; LI Hong

    2008-01-01

    The structure and properties of the glass-ceramics were tested with X-ray diffraction testing instrument,correlative software,and other modern testing means.Then the effect of Al2O3 content on internal stresses in CaO-Al2O3-SiO2 glass-ceramics was studied deeply.In order to study the relationship of Al2O3 to the residual stress of CaO-Al2O3-SiO2 glass-ceramics,X-ray diffraction"sin2 ψ"was used.The means utilized the x radial incidence produced from cathode radial tube,and took the space between crystals as measurement of strain.When the stresses produced,the space between crystals changed and the diffraction peak moved during Bragg diffraction.The magnitude of movement is related to the stresses.The experimental results show the residual stress is considerably high and Al2O3 can influence the mechanical properties of this material hugely.

  1. Creep rupture of the joint of a solid oxide fuel cell glass-ceramic sealant with metallic interconnect

    Science.gov (United States)

    Lin, Chih-Kuang; Lin, Kun-Liang; Yeh, Jing-Hong; Wu, Si-Han; Lee, Ruey-Yi

    2014-01-01

    Creep properties of sandwich joint specimens made of a newly developed BaO-B2O3-Al2O3-SiO2 glass-ceramic sealant (GC-9) and a ferritic-stainless-steel interconnect (Crofer 22 H) for planar solid oxide fuel cells (pSOFCs) are investigated at 800 °C under constant shear and tensile loadings. The creep rupture time of Crofer 22 H/GC-9/Crofer 22 H joint specimens is increased with a decrease in applied load for both shear and tensile loading modes. The given metal/sealant/metal joint has a greater degradation of joint strength at 800 °C under prolonged, constant tensile loading as compared to shear loading. The tensile creep strength at a rupture time of 1000 h is about 9% of the average tensile joint strength, while the shear creep strength at 1000 h is about 23% of the average shear joint strength. Failure patterns of both shear and tensile joint specimens are similar regardless of the creep rupture time. In general, creep cracks initiate at the interface between the (Cr,Mn)3O4 spinel layer and the BaCrO4 chromate layer, penetrate through the BaCrO4 layer, and propagate along the interface between the chromate layer and glass-ceramic substrate until final fracture. Final, fast fracture occasionally takes place within the glass-ceramic layer.

  2. Chemical adhesion rather than mechanical retention enhances resin bond durability of a dental glass-ceramic with leucite crystallites

    Energy Technology Data Exchange (ETDEWEB)

    Meng, X F [Department of Prosthodontics, The Stomatological Hospital Affiliated Medical School, Nanjing University, Nanjing 210008 (China); Yoshida, K [Division of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588 (Japan); Gu, N, E-mail: mengsoar@nju.edu.c [Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China)

    2010-08-01

    This study aims to evaluate the effect of chemical adhesion by a silane coupler and mechanical retention by hydrofluoric acid (HFA) etching on the bond durability of resin to a dental glass ceramic with leucite crystallites. Half of the ceramic plates were etched with 4.8% HFA (HFA group) for 60 s, and the other half were not treated (NoHFA group). The scale of their surface roughness and rough area was measured by a 3D laser scanning microscope. These plates then received one of the following two bond procedures to form four bond test groups: HFA/cement, NoHFA/cement, HFA/silane/cement and NoHFA/silane/cement. The associated micro-shear bond strength and bond failure modes were tested after 0 and 30 000 thermal water bath cycles. Four different silane/cement systems (Monobond S/Variolink II, GC Ceramic Primer/Linkmax HV, Clearfil Ceramic Primer/Clearfil Esthetic Cement and Porcelain Liner M/SuperBond C and B) were used. The data for each silane/cement system were analyzed by three-way ANOVA. HFA treatment significantly increased the surface R{sub a} and R{sub y} values and the rough area of the ceramic plates compared with NoHFA treatment. After 30 000 thermal water bath cycles, the bond strength of all the test groups except the HFA/Linkmax HV group was significantly reduced, while the HFA/Linkmax HV group showed only adhesive interface failure. The other HFA/cement groups and all NoHFA/cement groups lost bond strength completely, and all NoHFA/silane/cement groups with chemical adhesion had significantly higher bond strength and more ceramic cohesive failures than the respective HFA/cement groups with mechanical retention. The result of the HFA/silane/cement groups with both chemical adhesion and mechanical retention revealed that HFA treatment could enhance the bond durability of resin/silanized glass ceramics, which might result from the increase of the chemical adhesion area on the ceramic rough surface and subsequently reduced degradation speed of the silane

  3. Chemical adhesion rather than mechanical retention enhances resin bond durability of a dental glass-ceramic with leucite crystallites

    International Nuclear Information System (INIS)

    This study aims to evaluate the effect of chemical adhesion by a silane coupler and mechanical retention by hydrofluoric acid (HFA) etching on the bond durability of resin to a dental glass ceramic with leucite crystallites. Half of the ceramic plates were etched with 4.8% HFA (HFA group) for 60 s, and the other half were not treated (NoHFA group). The scale of their surface roughness and rough area was measured by a 3D laser scanning microscope. These plates then received one of the following two bond procedures to form four bond test groups: HFA/cement, NoHFA/cement, HFA/silane/cement and NoHFA/silane/cement. The associated micro-shear bond strength and bond failure modes were tested after 0 and 30 000 thermal water bath cycles. Four different silane/cement systems (Monobond S/Variolink II, GC Ceramic Primer/Linkmax HV, Clearfil Ceramic Primer/Clearfil Esthetic Cement and Porcelain Liner M/SuperBond C and B) were used. The data for each silane/cement system were analyzed by three-way ANOVA. HFA treatment significantly increased the surface Ra and Ry values and the rough area of the ceramic plates compared with NoHFA treatment. After 30 000 thermal water bath cycles, the bond strength of all the test groups except the HFA/Linkmax HV group was significantly reduced, while the HFA/Linkmax HV group showed only adhesive interface failure. The other HFA/cement groups and all NoHFA/cement groups lost bond strength completely, and all NoHFA/silane/cement groups with chemical adhesion had significantly higher bond strength and more ceramic cohesive failures than the respective HFA/cement groups with mechanical retention. The result of the HFA/silane/cement groups with both chemical adhesion and mechanical retention revealed that HFA treatment could enhance the bond durability of resin/silanized glass ceramics, which might result from the increase of the chemical adhesion area on the ceramic rough surface and subsequently reduced degradation speed of the silane coupler

  4. Dielectric Properties of La2O3 Doped Composite (PbxSr1−xTiO3 Borosilicate Glass Ceramic

    Directory of Open Access Journals (Sweden)

    C. R. Gautam

    2013-01-01

    Full Text Available Ferroelectric (PbxSr1−xTiO3 (PST perovskite phase has been crystallized in borosilicate glassy matrix with a suitable choice of composition and heat treatment schedule. La2O3 is a donor dopant for PST and can make it semiconducting. Dispersion of semiconducting perovskite phase in insulating glassy matrix in glass-ceramic samples may lead to the formation of space charge polarization around crystal-glass interface, leading to a high value of effective dielectric constant, εr. Therefore, with the aim of the developing glass ceramics with high dielectric constant, glasses in the system 64[(PbxSr1−xO·TiO2]-25[2SiO2·B2O3]-5[K2O]-5[BaO]-1[La2O3] have been prepared (0.5≤x≤1. It is found that the addition of La2O3 strongly affected the crystallization and dielectric behavior of glass-ceramic with PST perovskite phase. All glass ceramic samples show a diffuse broad Curie peak in their εr versus T plots. Curie peak temperature, Tc, depends on compositions of the glass-ceramic samples as well as frequency of measurements.

  5. Highly matched spectrum needed for photosynthesis in Ce{sup 3+}/Er{sup 3+}/Yb{sup 3+} tri-doped oxyfluoride glass ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Weirong; Gao, Huiping [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Institute for Computational Materials Science, Henan University, Kaifeng 475004 (China); Mao, Yanli, E-mail: ylmao@henu.edu.cn [School of Physics and Electronics, Henan University, Kaifeng 475004 (China); Institute for Computational Materials Science, Henan University, Kaifeng 475004 (China)

    2015-11-05

    A series of oxyfluoride glass ceramics containing CaF{sub 2} nano-crystals tri-doped with Ce{sup 3+}/Er{sup 3+}/Yb{sup 3+} ions were prepared by high temperature melting method and subsequent heat treatment. The structural properties were examined by X-ray diffraction measurements. The absorption, excitation, and emission spectra of the glass ceramics were investigated. Difference in erbium emission spectra between glass and glass ceramics had been studied. The emission bands originating from the {sup 4}F{sub 9/2} state of Er{sup 3+} were enhanced when the CaF{sub 2} nano-crystal created. By down-converting the ultraviolet wavelength region (280∼400 nm) light and up-converting the near-infrared wavelength region (900∼1100 nm) light, the glass ceramics can also emit strong reddish orange emission. The emission spectra consisting of bluish violet (400∼500 nm) and reddish orange (640∼680 nm) bands match well with the action spectrum of photosynthesis and absorption spectra of chlorophylls. Our materials will be favored to promote the development of glass greenhouses for green plant. - Highlights: • Ce{sup 3+}/Er{sup 3+}/Yb{sup 3+} tri-doped oxyfluoride glass ceramics were prepared by high temperature melting method. • 668 nm red emission was obtained under 320 nm, 380 nm and 980 nm excitation, respectively. • The emission of samples matched well with the spectrum for photosynthesis.

  6. X-ray absorption fine structure of aged, Pu-doped glass and ceramic waste forms

    Science.gov (United States)

    Hess, N. J.; Weber, W. J.; Conradson, S. D.

    1998-04-01

    X-ray absorption spectroscopic (XAS) studies were performed on three compositionally identical, Pu-doped, borosilicate glasses prepared 15 years ago at different α-activities by varying the 239Pu/ 238Pu isotopic ratio. The resulting α-activities ranged from 1.9×10 7 to 4.2×10 9 Bq/g and have current, accumulated doses between 8.8×10 15 to 1.9×10 18 α-decays/g. Two ceramic, polycrystalline zircon (ZrSiO 4) samples prepared 16 years ago with 10.0 wt% Pu was also investigated. Varying the 239Pu/ 238Pu isotopic ratio in these samples resulted in α-activities of 2.5×10 8 and 5.6×10 10 Bq/g and current, accumulated doses of 1.2×10 17 and 2.8×10 19 α-decays/g. The multicomponent composition of the waste forms permitted XAS investigations at six absorption edges for the borosilicate glass and at three absorption edges for the polycrystalline zircons. For both waste forms, analysis of extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectra indicates that the local environment around the cations exhibits different degrees of disorder as a result of the accumulated α-decay dose. In general, cations with short cation-oxygen bonds show little effect from self-radiation whereas cations with long cation-oxygen bonds show a greater degree of disorder with accumulated α-decay dose.

  7. [Microstructure and spectral property of Er3+ doped transparent oxyfluoride glass ceramics with high fluorine contents].

    Science.gov (United States)

    Lin, Le-Jing; Ren, Guo-Zhong; Chen, Min-Peng; Liu, Yang

    2009-12-01

    The microstructure and spectral properties of Er3+ doped transparent oxyfluoride glass ceramics with high fluorine content were reported. Two samples with the same initial contents (50SiO2-45PbF2-5PbO-1ErF3) were prepared under the different preparation parameters. The final fluorine contents were detected by a fluoride ion selective electrode. The results shows that the final fluorine contents increase by covering crucibles with corundum lid during melt. The samples were characterized by X-ray diffraction, transmission electron microscopy (TEM), absorption spectra and upconversion luminescence spectra. The results show that PbF2 crystals were precipitated in the sample with high fluorine content before heat treatment. And the PbF2 crystals precipitated inside the glass matrix are spherical with diameters of approximately 10-15 nm in size from the high resolution TEM micrograph. The absorption spectra, J-O parameters and the upconversion spectra show that the Er3+ ions were located in crystalline and vitreous mixed states. It is different from the sample with low fluorine content which is completely amorphous. After heat treatment, Er3+ ions that remain in the glassy phase entered into fluoride nanocrystals in the sample with high fluorine content. The fluorine environment decreases non-radiative transfer which eases the upconversion processes. Hence, the upconversion luminescence intensity of Er3+ ions in the high fluorine content sample after heat treatment is much stronger than that in the precursor sample. PMID:20210134

  8. Evaluation of the reuse of glass and ceramic blocks in the development of a ceramic products; Avaliacao do reaproveitamento de blocos ceramicos e de vidro no desenvolvimento de um produto ceramico

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, R.A.; Silva, L.A.; Martins, B.E.D.B.S.; Felippe, C.E.C.; Almeida, V.C., E-mail: valeria@eq.ufrj.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Escola de Quimica

    2010-07-01

    The ceramic industry has enormous potential to absorb wastes. The main objective of this study was to evaluate the feasibility of reusing leftovers ceramic blocks, from construction and, with shards of glass in the development of a ceramic product. The ceramic pieces were prepared with different compositions of glass by the method of pressing conformation and heating at 1000 and 1100 deg C. The conformed pieces were tested for linear shrinkage, water absorption, porosity, and tensile strength. The techniques for characterization were X-ray fluorescence, X-ray diffraction and scanning electron microscopy, the results show that the ceramic material produced has a high flexural strength and low values of water absorption. (author)

  9. Development of a sintering process for recycling oil shale fly ash and municipal solid waste incineration bottom ash into glass ceramic composite.

    Science.gov (United States)

    Zhang, Zhikun; Zhang, Lei; Li, Aimin

    2015-04-01

    Oil shale fly ash and municipal solid waste incineration bottom ash are industrial and municipal by-products that require further treatment before disposal to avoid polluting the environment. In the study, they were mixed and vitrified into the slag by the melt-quench process. The obtained vitrified slag was then mixed with various percentages of oil shale fly ash and converted into glass ceramic composites by the subsequent sintering process. Differential thermal analysis was used to study the thermal characteristics and determine the sintering temperatures. X-ray diffraction analysis was used to analyze the crystalline phase compositions. Sintering shrinkage, weight loss on ignition, density and compressive strength were tested to determine the optimum preparation condition and study the co-sintering mechanism of vitrified amorphous slag and oil shale fly ash. The results showed the product performances increased with the increase of sintering temperatures and the proportion of vitrified slag to oil shale fly ash. Glass ceramic composite (vitrified slag content of 80%, oil shale fly ash content of 20%, sintering temperature of 1000 °C and sintering time of 2h) showed the properties of density of 1.92 ± 0.05 g/cm(3), weight loss on ignition of 6.14 ± 0.18%, sintering shrinkage of 22.06 ± 0.6% and compressive strength of 67 ± 14 MPa. The results indicated that it was a comparable waste-based material compared to previous researches. In particular, the energy consumption in the production process was reduced compared to conventional vitrification and sintering method. Chemical resistance and heavy metals leaching results of glass ceramic composites further confirmed the possibility of its engineering applications. PMID:25649918

  10. Development of a sintering process for recycling oil shale fly ash and municipal solid waste incineration bottom ash into glass ceramic composite.

    Science.gov (United States)

    Zhang, Zhikun; Zhang, Lei; Li, Aimin

    2015-04-01

    Oil shale fly ash and municipal solid waste incineration bottom ash are industrial and municipal by-products that require further treatment before disposal to avoid polluting the environment. In the study, they were mixed and vitrified into the slag by the melt-quench process. The obtained vitrified slag was then mixed with various percentages of oil shale fly ash and converted into glass ceramic composites by the subsequent sintering process. Differential thermal analysis was used to study the thermal characteristics and determine the sintering temperatures. X-ray diffraction analysis was used to analyze the crystalline phase compositions. Sintering shrinkage, weight loss on ignition, density and compressive strength were tested to determine the optimum preparation condition and study the co-sintering mechanism of vitrified amorphous slag and oil shale fly ash. The results showed the product performances increased with the increase of sintering temperatures and the proportion of vitrified slag to oil shale fly ash. Glass ceramic composite (vitrified slag content of 80%, oil shale fly ash content of 20%, sintering temperature of 1000 °C and sintering time of 2h) showed the properties of density of 1.92 ± 0.05 g/cm(3), weight loss on ignition of 6.14 ± 0.18%, sintering shrinkage of 22.06 ± 0.6% and compressive strength of 67 ± 14 MPa. The results indicated that it was a comparable waste-based material compared to previous researches. In particular, the energy consumption in the production process was reduced compared to conventional vitrification and sintering method. Chemical resistance and heavy metals leaching results of glass ceramic composites further confirmed the possibility of its engineering applications.

  11. Effect of ZrO(2) additions on the crystallization, mechanical and biological properties of MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics.

    Science.gov (United States)

    Li, H C; Wang, D G; Meng, X G; Chen, C Z

    2014-06-01

    A series of ZrO(2) doped MgO-CaO-SiO(2)-P(2)O(5)-CaF(2) bioactive glass-ceramics were obtained by sintering method. The crystallization behavior, phase composition, morphology and structure of glass-ceramics were characterized. The bending strength, elastic modulus, fracture toughness, micro-hardness and thermal expansion coefficient (TEC) of glass-ceramics were investigated. The in vitro bioactivity and cytotoxicity tests were used to evaluate the bioactivity and biocompatibility of glass-ceramics. The sedimentation mechanism and growth process of apatites on sample surface were discussed. The results showed that the mainly crystalline phases of glass-ceramics were Ca(5)(PO4)3F (fluorapatite) and β-CaSiO(3). (β-wollastonite). m-ZrO(2) (monoclinic zirconia) declined the crystallization temperatures of glasses. t-ZrO(2) (tetragonal zirconia) increased the crystallization temperature of Ca(5)(PO4)(3)F and declined the crystallization temperature of β-CaSiO(3). t-ZrO(2) greatly increased the fracture toughness, bending strength and micro-hardness of glass-ceramics. The nanometer apatites were induced on the surface of glass-ceramic after soaking 28 days in SBF (simulated body fluid), indicating the glass-ceramic has good bioactivity. The in vitro cytotoxicity test demonstrated the glass-ceramic has no toxicity to cell.

  12. Commercial high-level-waste management: options and economics. A comparative analysis of the ceramic and glass waste forms

    Energy Technology Data Exchange (ETDEWEB)

    McKisson, R.L.; Grantham, L.F.; Guon, J.; Recht, H.L.

    1983-02-25

    Results of an estimate of the waste management costs of the commercial high-level waste from a 3000 metric ton per year reprocessing plant show that the judicious use of the ceramic waste form can save about $2 billion during a 20-year operating campaign relative to the use of the glass waste form. This assumes PWR fuel is processed and the waste is encapsulated in 0.305-m-diam canisters with ultimate emplacement in a BWIP-type horizontal-borehole repository. The estimated total cost (capital and operating) of the management in the ceramic form is $2.0 billion, and that of the glass form is $4.0 billion. Waste loading and waste form density are the driving factors in that the low-waste loading (25%) and relatively low density (3.1 g/cm/sup 3/) characteristic of the glass form require several times as many canisters to handle a given waste throughput than is needed for the ceramic waste form whose waste loading capability exceeds 60% and whose waste density is nominally 5.2 g/cm/sup 3/) characteristic of the glass form requires several times as many canisters to handle a given waste throughput than is needed for the ceramic waste form whose waste loading capability exceeds 60% and whose waste density is nominally 5.2 g/cm/sup 3/. The minimum-cost ceramic waste form has a 60 wt. % waste loading of commercial high-level waste and requires 25 years storage before emplacement in basalt with delayed backfill. Because of the process flexibility allowed by the availability of the high-waste loading of the ceramic form, the intermediate-level liquid waste stream can be mixed with the high-level liquid waste stream and economically processed and emplaced. The cost is greater by $0.3 billion than that of the best high-level liquid waste handling process sequence ($2.3 billion vs $2.0 billion), but this difference is less than the cost of the separate disposal of the intermediate-level liquid waste.

  13. Commercial high-level-waste management: options and economics. A comparative analysis of the ceramic and glass waste forms

    International Nuclear Information System (INIS)

    Results of an estimate of the waste management costs of the commercial high-level waste from a 3000 metric ton per year reprocessing plant show that the judicious use of the ceramic waste form can save about $2 billion during a 20-year operating campaign relative to the use of the glass waste form. This assumes PWR fuel is processed and the waste is encapsulated in 0.305-m-diam canisters with ultimate emplacement in a BWIP-type horizontal-borehole repository. The estimated total cost (capital and operating) of the management in the ceramic form is $2.0 billion, and that of the glass form is $4.0 billion. Waste loading and waste form density are the driving factors in that the low-waste loading (25%) and relatively low density (3.1 g/cm3) characteristic of the glass form require several times as many canisters to handle a given waste throughput than is needed for the ceramic waste form whose waste loading capability exceeds 60% and whose waste density is nominally 5.2 g/cm3) characteristic of the glass form requires several times as many canisters to handle a given waste throughput than is needed for the ceramic waste form whose waste loading capability exceeds 60% and whose waste density is nominally 5.2 g/cm3. The minimum-cost ceramic waste form has a 60 wt. % waste loading of commercial high-level waste and requires 25 years storage before emplacement in basalt with delayed backfill. Because of the process flexibility allowed by the availability of the high-waste loading of the ceramic form, the intermediate-level liquid waste stream can be mixed with the high-level liquid waste stream and economically processed and emplaced. The cost is greater by $0.3 billion than that of the best high-level liquid waste handling process sequence ($2.3 billion vs $2.0 billion), but this difference is less than the cost of the separate disposal of the intermediate-level liquid waste

  14. Cooperative Quantum Cutting in Er3+/Yb3+ Codoped Oxyfluoride Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    LUO Shi-Qiang; ZHAO Li-Juan; HU Nan; ZHANG Ming; ZHANG Pan; WANG Ya-Zhou; YU Hua

    2011-01-01

    Oxvfluoride glass ceramic doped with doped with Era+/Yb3+ was synthesized.Rare earth ions are doped into fluoride nanocrystals according to x-ray diffractive patterns. The enhanced red emission of Er3+/Yb3+ in the fluoride nanocrystals, excited by xenon lamp ta 449nm,is investigated and analyzed by cooperative quantum cutting mode.the cross relaxation appears from 4F5/2→4F9/2 to 4I15/2→4I13/2 because of the nearer distance of rare earth ions and the larger absorption section of 4I15/2→4I13/2 in the quantum cutting. It results in two emissions of 4F9/2→4I15/2 and 4I13/2→4I15/2. This implies that a 449nm photon could dissolve into two emiswith wavelength 665nm and 1530nm. This could be an effective way to obtain 1530nm emission for optical communication.

  15. Mechanical properties and porosity of dental glass-ceramics hot-pressed at different temperatures

    Directory of Open Access Journals (Sweden)

    Carla Castiglia Gonzaga

    2008-09-01

    Full Text Available The objective of this work was to evaluate biaxial-flexural-strength (σf, Vickers hardness (HV, fracture toughness (K Ic, Young's modulus (E, Poisson's ratio (ν and porosity (P of two commercial glass-ceramics, Empress (E1 and Empress 2 (E2, as a function of the hot-pressing temperature. Ten disks were hot-pressed at 1065, 1070, 1075 and 1080 °C for E1; and at 910, 915, 920 and 925 °C for E2. The porosity was measured by an image analyzer software and s f was determined using the piston-on-three-balls method. K Ic and HV were determined by an indentation method. Elastic constants were determined by the pulse-echo method. For E1 samples treated at different temperatures, there were no statistical differences among the values of all evaluated properties. For E2 samples treated at different temperatures, there were no statistical differences among the values of σf, E, and ν, however HV and K Ic were significantly higher for 910 and 915 °C, respectively. Regarding P, the mean value obtained for E2 for 925 °C was significantly higher compared to other temperatures.

  16. Development of Alternative Glass Ceramic Seal for a Planar Solid Oxide Fuel Cell

    Directory of Open Access Journals (Sweden)

    P. Lemes-Rachadel

    2012-01-01

    Full Text Available LZSA glass ceramic (LiO2-ZrO2-SiO2-Al2O3 was tested for its thermomechanical compatibility as a sealing material with a stainless steel interconnect (AISI 430 of a planar SOFC. With this purpose, the densification and crystallization behavior of LZSA were investigated initially. It was observed that the material reached maximum relative density and shrinkage, respectively 95% and 17%, at 800°C, which corresponded approximately to the crystallization temperature of the material as evidenced by DTA analysis. In the next step, LZSA tapes were cast from slurries and prepared either as LZSA laminates or LZSA-steel bilayers. The densification behavior and microstructural features of cofired LZSA laminates and LZSA-steel bilayers were analyzed at 800 and 900°C. Maximum relative density and defect-free interfaces were observed for laminates and bi-layers cofired at 800°C, whereas increased porosity and detached bi-layer were the characteristics of the samples fired at 900°C.

  17. Glass-(nAg, nCu biocide coatings on ceramic oxide substrates.

    Directory of Open Access Journals (Sweden)

    Leticia Esteban-Tejeda

    Full Text Available The present work was focused on obtaining biocide coatings constituted by a glassy soda-lime matrix containing silver or copper nanoparticles on ceramic (alumina and zirconia based substrates. Both glassy coatings showed a high biocide activity against Gram-, Gram+ bacteria and yeast, reducing cell numbers more than three logarithms. Silver nanoparticles had a significantly higher biocide activity than copper nanoparticles, since the lixiviation levels required to reduce cell numbers more than 3 logarithms was of almost 1-2 µg/cm(2 in the case of silver nanoparticles, and 10-15 µg/cm(2 for the copper nanoparticles.

  18. Glass-(nAg, nCu) Biocide Coatings on Ceramic Oxide Substrates

    Science.gov (United States)

    Esteban-Tejeda, Leticia; Malpartida, Francisco; Díaz, Luis Antonio; Torrecillas, Ramón; Rojo, Fernando; Moya, José Serafín

    2012-01-01

    The present work was focused on obtaining biocide coatings constituted by a glassy soda-lime matrix containing silver or copper nanoparticles on ceramic (alumina and zirconia based) substrates. Both glassy coatings showed a high biocide activity against Gram−, Gram+ bacteria and yeast, reducing cell numbers more than three logarithms. Silver nanoparticles had a significantly higher biocide activity than copper nanoparticles, since the lixiviation levels required to reduce cell numbers more than 3 logarithms was of almost 1–2 µg/cm2 in the case of silver nanoparticles, and 10–15 µg/cm2 for the copper nanoparticles. PMID:22427967

  19. Damage Accumulation in Cyclically-Loaded Glass-Ceramic Matrix Composites Monitored by Acoustic Emission

    Science.gov (United States)

    Aggelis, D. G.; Dassios, K. G.; Kordatos, E. Z.; Matikas, T. E.

    2013-01-01

    Barium osumilite (BMAS) ceramic matrix composites reinforced with SiC-Tyranno fibers are tested in a cyclic loading protocol. Broadband acoustic emission (AE) sensors are used for monitoring the occurrence of different possible damage mechanisms. Improved use of AE indices is proposed by excluding low-severity signals based on waveform parameters, rather than only threshold criteria. The application of such improvements enhances the accuracy of the indices as accumulated damage descriptors. RA-value, duration, and signal energy follow the extension cycles indicating moments of maximum or minimum strain, while the frequency content of the AE signals proves very sensitive to the pull-out mechanism. PMID:24381524

  20. Calcium-borosilicate glass-ceramics wasteforms to immobilize rare-earth oxide wastes from pyro-processing

    Science.gov (United States)

    Kim, Miae; Heo, Jong

    2015-12-01

    Glass-ceramics containing calcium neodymium(cerium) oxide silicate [Ca2Nd8-xCex(SiO4)6O2] crystals were fabricated for the immobilization of radioactive wastes that contain large portions of rare-earth ions. Controlled crystallization of alkali borosilicate glasses by heating at T ≥ 750 °C for 3 h formed hexagonal Ca-silicate crystals. Maximum lanthanide oxide waste loading was >26.8 wt.%. Ce and Nd ions were highly partitioned inside Ca-silicate crystals compared to the glass matrix; the rare-earth wastes are efficiently immobilized inside the crystalline phases. The concentrations of Ce and Nd ions released in a material characterization center-type 1 test were below the detection limit (0.1 ppb) of inductively coupled plasma mass spectroscopy. Normalized release values performed by a product consistency test were 2.64·10-6 g m-2 for Ce ion and 2.19·10-6 g m-2 for Nd ion. Results suggest that glass-ceramics containing calcium neodymium(cerium) silicate crystals are good candidate wasteforms for immobilization of lanthanide wastes generated by pyro-processing.

  1. Influence of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    HE Feng; NIU Feng; LOU Guang-hui

    2005-01-01

    ZrO2 was added into CaO-Al2O3-SiO2 glass-ceramics and the effect of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass ceramics was investigated. The results show that the sintering shrinkage ratio of glass particles decreases with the increase of the content of ZrO2. ZrO2 has an unfavourable effect on sintering shrinkage ratio of glass particles. The sintering shrinkage ratio of glass particles increases with the increase of sintering temperature. The increase of sintering temperature favors the decrease of the liquid phase viscosity of glass particles. ZrO2 has little effect on crystallization of main crystalline phase (β-wollastonite). However, it promotes the crystallization at relatively low temperature.

  2. Preparation of glasses and glass ceramics of heavy metal oxides containing silver: optical, structural and electrochemical properties; Preparacao de vidros e vitroceramicas de oxidos de metais pesados contendo prata: propriedades opticas, estruturais e eletroquimicas

    Energy Technology Data Exchange (ETDEWEB)

    Bregadiolli, Bruna A. [Departamento de Fisica, Faculdade de Ciencias, Universidade Estadual Paulista, Bauru - SP (Brazil); Souza, Ernesto R.; Sigoli, Fernando A. [Instituto de Quimica, Universidade Estadual de Campinas, Campinas - SP (Brazil); Caiut, Jose M.A. [Departamento de Quimica, Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto - SP (Brazil); Alencar, Monica A.S.; Benedetti, Assis V. [Instituto de Quimica, Universidade Estadual Paulista, Araraquara - SP (Brazil); Nalin, Marcelo, E-mail: mnalin@ufscar.br [Departamento de Quimica, Universidade Federal de Sao Carlos, SP, (Brazil)

    2012-07-01

    Silver containing heavy metal oxide glasses and glass ceramics of the system WO{sub 3}-SbPO{sub 4} -PbO-AgCl with different AgCl contents have been prepared and their thermal, structural and optical properties characterized. Glass ceramics containing metallic silver nanoparticles have been prepared by annealing glass samples at temperatures above the glass transition and analyzed by transmission electron microscopy and energy dispersive X-ray microanalysis. The presence of the metallic clusters has been also confirmed by the observation of a surface plasmon resonance band in the visible range. Cyclic voltammetric measurements indicated the presence of metallic silver into the glasses, even before to perform the thermal treatment. (author)

  3. Novel resorbable glass-ceramic scaffolds for hard tissue engineering: from the parent phosphate glass to its bone-like macroporous derivatives.

    Science.gov (United States)

    Bretcanu, Oana; Baino, Francesco; Verné, Enrica; Vitale-Brovarone, Chiara

    2014-05-01

    One of the major challenges of hard tissue engineering research focuses on the development of scaffolds that can match the mechanical properties of the host bone and resorb at the same rate as the bone is repaired. The aim of this work was the synthesis and characterization of a resorbable phosphate glass, as well as its application for the fabrication of three dimensional (3-D) scaffolds for bone regeneration. The glass microstructure and behaviour upon heating were analysed by X-ray diffraction, differential scanning calorimetry and hot stage microscopy. The glass solubility was investigated according to relevant ISO standards using distilled water, simulated body fluid (SBF) and Tris-HCl as testing media. The glass underwent progressive dissolution over time in all three media but the formation of a hydroxyapatite-like layer was also observed on the samples soaked in SBF and Tris-HCl, which demonstrated the bioactivity of the material. The glass powder was used to fabricate 3-D macroporous bone-like glass-ceramic scaffolds by adopting polyethylene particles as pore formers: during thermal treatment, the polymer additive was removed and the sintering of glass particles was allowed. The obtained scaffolds exhibited high porosity (87 vol.%) and compressive strength around 1.5 MPa. After soaking for 4 months in SBF, the scaffolds mass loss was 76 wt.% and the pH of the solution did not exceed the 7.55 value, thereby remaining in a physiological range. The produced scaffolds, being resorbable, bioactive, architecturally similar to trabecular bone and exhibiting interesting mechanical properties, can be proposed as promising candidates for bone repair applications.

  4. Study of glass preforms for glass fiber optics applications (study of space processing of ceramic materials). [light transmission

    Science.gov (United States)

    Wang, F. F. Y.

    1974-01-01

    The feasibility, and technical and economic desirability was studied of space processing of glass preforms for optical fiber transmission applications. The results indicate that space processing can produce glass preforms of equal quality at lower cost than earth bound production, and can produce diameter modulation in the glass preform which promotes mode coupling and lowers the dispersion. The glass composition can be modified through the evaporative and diffusion processes, and graded refractive index profiles can be produced. A brief summary of the state of the art in optical fiber transmission is included.

  5. Bulk glass ceramics containing Yb3+/Er3+: β-NaGdF4 nanocrystals: Phase-separation-controlled crystallization, optical spectroscopy and upconverted temperature sensing behavior

    International Nuclear Information System (INIS)

    Highlights: • Hexagonal NaGdF4 nanocrystals embedded bulk glass ceramics were fabricated. • The incorporation of Ln3+ dopants into the β-NaGdF4 lattice was demonstrated. • Upconversion luminescence was highly intensified after glass crystallization. • Such glass ceramics had possible application in the optical temperature sensors. - Abstract: Lanthanide doped hexagonal β-NaGdF4 nanocrystals embedded transparent bulk glass ceramics were successfully fabricated via a phase-separation-controlled crystallization route. Elemental mapping in the scanning transmission electron microscope and optical spectroscopy analysis demonstrated the partition of the active centers into the β-NaGdF4 crystalline lattice. As a result, upconversion luminescence of the glass ceramic co-doped with Yb3+ and Er3+ is about 60 times as high as that of the precursor glass, attributing to the modification of Yb3+/Er3+ surrounding from phase-separated amorphous nanoparticle to β-NaGdF4 crystalline lattice with low phonon energy and high crystallinity after crystallization. Furthermore, the temperature-dependent green upconversion emissions assigned to 2H11/2 → 4I15/2 (520 nm) and 4S3/2 → 4I15/2 (540 nm) transitions were investigated, and the corresponding fluorescence intensity ratio of these two thermally coupled emitting-states greatly enhanced with increase of temperature. Using such fabricated glass ceramic as an optical thermometric medium, the maximum sensitivity reached as high as 0.0037 K−1 at 580 K. It is expected that the investigated Er3+/Yb3+ codoped glass ceramic might be a very promising candidate for accurate optical temperature sensors

  6. Fabrication of hexagonal boron nitride based ceramics by combustion synthesis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Pure h-BN (hexagonal boron nitride) and h-BN based ceramic parts were fabricated by combustion synthesis technique, i.e. self-propagating high-temperature synthesis (SHS). Components were manufactured by the combustion reaction of 80  MPa nitrogen and the compact made by cool isostatic pressing. In h-BN based ceramic parts, h-BN powder was used as diluent and SiO2 powder as reinforcing phase. The density of pure h-BN and h-BN-based ceramic parts were 58% and 78% of theoretical density, respectively. With XRD and SEM, phases and microstructures of ceramic parts were analyzed. Mechanical properties were also tested.

  7. Sealing of ceramic SOFC-components with glass seals; Fuegen von keramischen Komponenten der Hochtemperatur-Brennstoffzellen mittels Glas- und Glaskeramikloten

    Energy Technology Data Exchange (ETDEWEB)

    Schillig, Cora

    2012-07-10

    The solid oxide fuel cell (SOFC) converts chemical energy of a fuel directly into electrical energy. However, for the implementation of SOFC-technology in competition to conventional power plants costs have to be reduced. The use of an alternative tubular cell design without closed end would allow reducing costs during cell manufacturing. However, this change in design makes a gastight sealing inside the generator near the gas inlet necessary. Different ceramic materials with varying coefficients of thermal expansion have to be sealed gastight and electrical insulating at temperatures between 850 C and 1000 C to prevent the gases from mixing and an electrical shortcut between the cells. This work comprises analysis of commercially available glass and glass-ceramic systems manufactured by Schott Electronic Packaging, Areva T and D and Ferro Corporation. Additionally new developed sealing glass and glass-ceramic systems were investigated and all systems were characterized fundamentally for the use as sealing material in SOFC generators. Therefore different test assemblies and series were conducted. Essential characteristics of a suitable sealing system are a thermal expansion coefficient between 9,5 and 12 . 10{sup -6}K{sup -1}, a viscosity in the range between 10{sup 4} to 10{sup 6} dPa{sup *}s and a wetting angle smaller than 90 during the sealing process. Also unwanted chemical side reactions between the sealing partners must be prevented, because a change in the phase composition or the creation of new phases in the sealing material could endanger the stability of the seal. Heat cycles, particularly those during generator operation, cause deterioration of the sealing material and subsequent reduction in its ability to prevent mixing of the gases. Sealant leaks can drastically impact efficiency of the generator. In order to ensure optimum operation low leak rates around 2,3 . 10{sup -4} mbar l/sec/cm{sup 2} must be maintained. Especially glass and glass-ceramics

  8. Microstructure and fracture behavior of SiO_2 glass ceramic and TC4 alloy joint brazed with TiZrNiCu alloy

    Institute of Scientific and Technical Information of China (English)

    LIU Duo; ZHANG Li-xia; FENG Ji-cai; LIU Hong-bin; HE Peng

    2009-01-01

    Vacuum brazing of SiO_2 glass ceramic and TC4 alloy using a commercially available TiZrNiCu foil was investigated. The interfaciai microstructure and the fractures were examined with an optical microscope (OM) and an S-4700 scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS) and an electron probe X-ray microanalyzer (EPMA). The structure of joint interface was identified by XRD (JDX-3530M). Meanwhile, the fracture paths of the joints were comprehensively studied. The results show that processing parameters, especially the brazing temperature, have a significant effect on the microstructurc and mechanical properties of joints. The typical interface structure is SiO_2/Ti_2O+Zr_3Si_2+Ti_5Si_3/(Ti,Zr)+Ti_2O+ TiZrNiCu/Ti(s.s)/TiZrNiCu+Ti(s.s)+Ti_2(Cu,Ni)/TC4 from SiO_2 glass ceramic to TC4 alloy side. Based on the mechanical property tests, the joints brazed at 880℃ for 5 min has the maximum shear strength of 23 MPa.

  9. Fast-ion conducting glass and glass-ceramics for the pH sensor Ionic conductivity

    CERN Document Server

    Niyompan, A

    2002-01-01

    Fast-ion conducting glasses of the compositions Na sub 1 sub + sub x M sub 2 sub - sub x sub / sub 3 Si sub x P sub 3 sub - sub x O sub 1 sub 2 sub - sub 2 sub x sub / sub 3 (0<= x <=3), where M = Zr, Ti, were studied to determine their structural arrangement, physical properties and ionic conductivity. Glass samples were prepared using the conventional melt-quench method in the melting temperature range, 1550 deg C to 1650 deg C. Glass products were characterised by XRD, DTA, dilatometry and density measurement. Solid state MAS NMR experiments of three accessible nuclei, sup 2 sup 3 Na, sup 2 sup 9 Si and sup 3 sup 1 P were used to determine short-range order arrangement in the glasses. XRD confirms the amorphicity of glasses for the compositions of x in range 0-3. Glass transition temperatures, T sub g , TEC, and molar volume are controlled by glass composition. The MAS NMR results suggest that glass structure could be visualised as the silicate network modified by Na sup + and Zr sup 4 sup + or Ti su...

  10. Diopside (CaO-MgO-2SiO2)-fluorapatite (9CaO-3P2O5-CaF2) glass-ceramics: Potential materials for bone tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Kansal, Ishu; Goel, Ashutosh; Tulyaganov, Dilshat U.; Pascual, Maria J.; Lee, Hye-Young; Kim, Hae-Won; Ferreira, Jose M.

    2011-08-18

    Glass-ceramics in the diopside (CaMgSi2O6) - fluorapatite [Ca5(PO4)3F] system are potential candidates for restorative dental and bone implant materials. In the present study, a series of glasses along diopside - fluorapatite binary system have been prepared with varying diopside/fluorapatite ratios for their potential applications in bone tissue engineering. The glasses were obtained from compositions with fluorapatite contents varying between 0-40 wt.%. The sintering ability and crystallization kinetics of as obtained amorphous glasses have been studied through hot-stage microscopy (HSM) and differential thermal analysis (DTA), respectively while crystalline phase evolution in sintered GCs has been followed by X-ray diffraction (XRD) adjoined with Rietveld-R.I.R. technique and scanning electron microscopy (SEM). Further, biodegradation and apatite forming ability of glass-ceramics were investigated by immersion of glass-ceramic discs in simulated body fluid (SBF) solution while chemical degradation and weight loss of glass-ceramics were studied by immersion in Tris-HCl in accordance with standard ISO 10993-14. The addition of fluorapatite (10-25 wt.%) in diopside glass system significantly enhanced the sintering ability of glass-ceramics and improved their apatite forming ability along with their biodegradation behaviour. Moreover, the in vitro cellular responses to glass-ceramics showed good cell viability and significant stimulation of osteoblastic differentiation, suggesting the possible use of the glass-ceramics for bone regeneration.

  11. Effect of heat-treatment on the electrical and dielectric properties of a TiO2-containing lithia-calcia-silica glass and glass ceramics

    International Nuclear Information System (INIS)

    Highlights: · Lithia calcium silicate glass with and without TiO2. · Glass ceramic. · Heat treatment. · DTA, XRD and IR measurements and discussions. · Dielectric constant (ε'), dielectric loss (ε'') and conductivity σac measurements and discussions. - Abstract: The glass 65 SiO2, 20 CaO, 15 Li2O (mol%) containing 4 g TiO2/100 g glass was prepared. Samples of this glass were heat treated at temperatures pre-determined by DTA to produce crystalline samples which were characterized by IR, XRD and SEM. The dielectric constant (ε'), dielectric loss (ε'') and conductivity σac over a wide range of frequency and temperatures were measured. Optical absorption and values of the absorption edge were also determined for the transparent samples. Li-calcium silicate was found to crystallize at 964 deg. C as the main phase with lithium disilicate and quartz as minor phases. An enhancement in conductivity of about 1-3 orders of magnitude was obtained in the heat treated samples as compared to parent glass. Conduction takes place through an electronic mechanism in the low temperature region. In crystalline samples, the electronic conduction is extended to high temperature regions. Crystallized samples show high ε' values, particularly at low frequencies. The values of (ε') reached 60-300 at 300 deg. C. The capacitance results indicated that these materials can be used in capacitors. Dielectric loss bands appeared in the range 0.32-5 MHz and the conduction relaxation times were calculated.

  12. Characterization of Er{sup 3+}-doped fluoride glass ceramics waveguides containing LaF{sub 3} nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Boulard, Brigitte, E-mail: brigitte.boulard@univ-lemans.f [Laboratoire des Oxydes et Fluorures, UMR CNRS 6010, Universite du Maine, Av. O. Messiaen, 72085 Le Mans (France); Peron, O. [Laboratoire des Oxydes et Fluorures, UMR CNRS 6010, Universite du Maine, Av. O. Messiaen, 72085 Le Mans (France); Jestin, Y.; Ferrari, M. [CNR-IFN, Istituto di Fotonica e Nanotecnologie, CSMFO Group, via alla Cascata 56/C, 38050 Povo (Italy); Duverger-Arfuso, C. [Laboratoire des Oxydes et Fluorures, UMR CNRS 6010, Universite du Maine, Av. O. Messiaen, 72085 Le Mans (France)

    2009-12-15

    Highly Er{sup 3+}-doped fluoride glass ceramics planar waveguides containing LaF{sub 3} nanocrystals have been fabricated by physical vapor deposition (PVD). The solubility of Er{sup 3+} in the segregated nanocrystals can reach 30 mol% which is much larger than the value found in LaF{sub 3}-oxide glass ceramics. A quantitative analysis of the photoluminescence of the 1.54 {mu}m emission band of Er{sup 3+} ions has demonstrated that erbium ions are partitioned in both crystals and vitreous phase. The short lifetime (2.2 ms) measured for erbium incorporated in LaF{sub 3} crystal lattice is a consequence of concentration quenching while the lifetime is close to 10 ms in the glassy phase. The emission bandwidth has been found to be greater than that of the precursor glass (71 nm at the half-height width). The high Er{sup 3+} concentration and spectral width could make this nanostructured fluoride material suitable for planar amplifier in the C telecommunication band.

  13. A Study on Nucleation, Crystallization Kinetics, Microstructure and Mechanical Properties of Ru-Bi Partial Substituted BSCCO Glass Ceramics

    Science.gov (United States)

    Tasci, Ahmet Tolga; Ozturk, Ozgur; Gokcen, Tugba; Cavdar, Sukru; Koralay, Haluk; Senol, Abdulkadir

    2015-03-01

    This study deals with, the effects of Ru-Bi partial substitutions on the thermal, structural and mechanical properties of Bi1 . 8 - xRuxPb0.2Sr2CaCu2O10+δ (x =0.0, 0.025, 0.050, 0.075), produced with glass-ceramics method have been investigated. The effects of Ru-Bi Partial substitutions on glass transition, nucleation and crystallization temperature are analyzed by differential thermal analyzer (DTA). Furthermore, micro-structure and micro-mechanical properties of Ru-Bi partial substituted BSCCO glass ceramics have been investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Vickers microhardness measurements. From the DTA results, nucleation kinetics have been obtained by using Ozawa, Augis-Bennett, Takher and Kissinger equations. Also activation energies and Avrami parameters have been found. Oxidation amount is seen to be increased with increasing Ru concentration in consequence of thermogravimetric analyses results. Moreover, Lattice parameters, volume fractions and surface morphologies of the samples are obtained from XRD and SEM measurements, respectively.

  14. The Effect of Different Finishing Lines on the Marginal Fitness of Full Contour Zirconia and Glass Ceramic CAD/CAM Crowns (An in-vitro study

    Directory of Open Access Journals (Sweden)

    ZAK Al-Zubaidi

    2015-09-01

    Full Text Available Purpose: The aim of this study was to evaluate the effect of two gingival finishing lines (90° shoulder and deep chamfer on the marginal fitness of two types of full anatomic all-ceramic crowns; zirconia crowns (Zikonzhan and glass ceramic crowns (IPS e-max CAD milled with CAD/CAM system. Materials and Methods: Two dentoform teeth of left maxillary first molar were prepared with chamfer finishing line (CFL and shoulder finishing line (SFL, respectively and duplicated to Nickel-Chromium master dies. Thirty two crowns were fabricated and grouped as follows: Group I: 8 zirconia crowns on CFL; Group II: 8 zirconia crowns on SFL; Group III: 8 glass ceramic crowns on CFL and Group IV: 8 glass ceramic crowns on SFL. Marginal gaps were measured at 4 indentations, each one was at center of each tooth surface and collectively 16 points were measured by using stereomicroscope (160X. The data were analyzed by One-way ANOVA and student t-tests. Results: Group I produced the least marginal gap (73.55µm; followed by Group II (92.60µm, and Group III (151.45µm and the highest marginal gap was recorded by Group IV (162.34µm. Statistical analysis of the data showed that SFL produced significantly greater marginal gap on zirconia crowns in comparison with CFL. However, in glass ceramic crowns, CFL revealed less marginal gap compared to SFL but statistically was not significant. On the other hand, glass ceramic crowns significantly produced a greater marginal gap in comparison to zirconia crowns regardless type of finishing line. Conclusions: deep chamfer margin could be more preferable finishing line than 90° shoulder especially for zirconia full crowns. Furthermore, zirconia crowns could be more advisable than glass ceramic crowns in respect to marginal adaptation.

  15. 硅灰石型LTCC微晶玻璃的研究进展%The Research Progress on Wollastonite LTCC Glass-ceramics

    Institute of Scientific and Technical Information of China (English)

    武祥

    2012-01-01

      The history of LTCC technology, background of glass-ceramics and its process features are reviewed. The structure, properties and application of wollastonite LTCC glass-ceramics are investigated. The recent progress for CaO-B2O3-SiO2 glass-ceramics is introduced. The key problems for the application of LTCC glass-ceramics are presented and hence the research methods are proposed.%  文章评述了低温共烧陶瓷(LTCC)技术的发展历程、微晶玻璃发展背景和工艺特点,总结了硅灰石型LTCC微晶玻璃(Glass Ceramics)材料的结构、性能及应用特征。根据现有文献资料概述了研究人员对CaO-B2O3-SiO2系玻璃陶瓷的研究进展,分析了当前研究的不足之处,讨论了需要关注的重点方向。文章最后提出了今后开展LTCC技术研究的思路。

  16. Quenched/unquenched nano bioactive glass-ceramics: Synthesis and in vitro bioactivity evaluation in Ringer’s solution with BSA

    Directory of Open Access Journals (Sweden)

    Nabian Nima

    2013-01-01

    Full Text Available The paper reports the first attempt at changing cooling treatment of synthesizing method in order to investigate its effect on the physical properties of sol-gel derived nano bioactive glass-ceramic in the system 58SiO2-33CaO-9P2O5 (wt.%. We hypothesized that the method of cooling may affect the properties of nano bioactive glass-ceramic. To test this hypothesis, two different method of cooling treatment was applied after calcinations in synthesizing method. Both quenched and unquenched nano bioactive glass-ceramics were soaked in Ringer’s solution with bovine serum albumin (BSA for bioactivity evaluation. The obtained samples were analyzed for their composition, crystalinity and morphology through X-ray powder diffraction (XRD, Fourier transform infrared spectroscopy (FTIR, surface electron microscope (SEM and transmission electron microscope (TEM. The SEM images showed that the morphology of nano bioactive glass-ceramics was completely changed by quenching process. Results of in vitro bioactivity evaluation revealed that the unquenched attains faster apatite formation ability than the quenched sample. Other properties of these two morphologically different nano bioactive glass-ceramics were strongly discussed.

  17. Enhanced energy storage performance of glass added 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 ferroelectric ceramics

    Directory of Open Access Journals (Sweden)

    Satyanarayan Patel

    2015-12-01

    Full Text Available In the present work, lead-free ferroelectric 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 (BNT-BT-ST bulk ceramics with 3BaO-3TiO2-B2O3 (BTBO glass additive were fabricated by conventional solid state reaction route. The effect of glass content on microstructure and energy storage properties of BNT-BT-ST ceramics was investigated. The maximum energy storage of ∼203 kJ/m3 was achieved for BNT-BT-ST ceramic with addition of 4 wt.% glass. The 4 wt.% glass addition improves energy storage density and energy storage efficiency by ∼15% and ∼52% higher than that of the pure BNT-BT-ST, respectively. The effect of temperature on the energy storage was also estimated. It was observed the temperature has similar effect on energy storage improvement in all compositions. The energy storage density (U dependent scaling behavior on remnant polarization (Pr, maximum polarization (Pmax, electric field (E and temperature (T was also studied. The results of this study are expected to largely benefit the field of ferroelectric based capacitors in discerning the dependency of U on hysteresis parameters (Pr, Pmax, and E and T.

  18. Integrated thick-film nanostructures based on spinel ceramics

    OpenAIRE

    Klym, Halyna; Hadzaman, Ivan; Shpotyuk, Oleh; Brunner, Michael

    2014-01-01

    Integrated temperature-humidity-sensitive thick-film structures based on spinel-type semiconducting ceramics of different chemical compositions and magnesium aluminate ceramics were prepared and studied. It is shown that temperature-sensitive thick-film structures possess good electrophysical characteristics in the region from 298 to 358 K. The change of electrical resistance in integrated thick-film structures is 1 order, but these elements are stable in time and can be successfully used for...

  19. Integrated thick-film nanostructures based on spinel ceramics.

    Science.gov (United States)

    Klym, Halyna; Hadzaman, Ivan; Shpotyuk, Oleh; Brunner, Michael

    2014-03-26

    Integrated temperature-humidity-sensitive thick-film structures based on spinel-type semiconducting ceramics of different chemical compositions and magnesium aluminate ceramics were prepared and studied. It is shown that temperature-sensitive thick-film structures possess good electrophysical characteristics in the region from 298 to 358 K. The change of electrical resistance in integrated thick-film structures is 1 order, but these elements are stable in time and can be successfully used for sensor applications.

  20. Excited state absorption and energy-transfer mechanisms of up-conversion luminescence in Er{sup 3+}-doped oxyfluoride glass ceramics at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Sarakovskis, A., E-mail: anatoly@cfi.lu.l [Institute of Solid State Physics University of Latvia, Kengaraga str. 8, LV-1063, Riga Latvia (Latvia); Grube, J.; Doke, G.; Springis, M. [Institute of Solid State Physics University of Latvia, Kengaraga str. 8, LV-1063, Riga Latvia (Latvia)

    2010-05-15

    Oxyfluoride silicate glass SiO{sub 2}-Al{sub 2}O{sub 3}-Na{sub 2}CO{sub 3}-NaF-LaF{sub 3}-ErF{sub 3} was synthesized. The glass transition and crystallization temperatures were determined by differential thermal analysis. Glass ceramics containing LaF{sub 3}:Er{sup 3+} crystallites of size approx20 nm were formed in the glass matrix after the heat treatment of the precursor glass in the vicinity of the crystallization temperature. Up-conversion luminescence, excitation spectra as well as time-resolved up-conversion luminescence of the glass and glass ceramics were studied at different temperatures. The up-conversion transients showed that at room temperature the dominant mechanism of the up-conversion luminescence in the glass ceramics is excited state absorption while at lower temperatures energy-transfer mechanism prevails. The origins of these differences are discussed in terms of the transitions between Stark manifolds of {sup 4}I{sub 15/2}, {sup 4}I{sub 11/2} and {sup 4}F{sub 7/2} states in Er{sup 3+} ions.