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Ceramic Layer (ceramic + layer)
Selected AbstractsMicrostructural and Mechanical Investigations on Porcelain-Fused-to-Metal in Multilayer SystemADVANCED ENGINEERING MATERIALS, Issue 4 2010Adele Carradò Results on porcelain-fused-to-metal (PFM) technique of ceramic films for biomedical applications on metal substrate are reported. The coating of metallic implants with bio-ceramic films (glassy and opaque ceramic) was proposed to be a solution for combining the mechanical properties of the metallic material with the bioactive character of the ceramic layer, leading to a better integration of the entire implant. The aim of this paper is to determine a stress field distribution by a non-destructive method as high-energy synchrotron X-ray diffraction in energy dispersive in the metal and glass ceramic bulk as well as at metal,opaque ceramic interface in PFM three layers sample. Tensile stresses were found in palladium substrate and compressive state in glass ceramic coating. Moreover thermal stresses induced by PFM coating at the interfaces were calculated by analytical mathematical model, confirming that the stresses induced, due to the selection of the materials, are low. Finally, the micro-structural and chemical characteristics of glassy and opaque bio-ceramic coatings on palladium alloy substrate were investigated and no inter-diffusion area between metal and ceramic could be detected as well as non-homogeneity in the interface ceramic. [source] Intermediate Temperature Anode-Supported Fuel Cell Based on BaCe0.9Y0.1O3 Electrolyte with Novel Pr2NiO4 CathodeFUEL CELLS, Issue 1 2010G. Taillades Abstract A proton conducting ceramic fuel cell (PCFC) operating at intermediate temperature has been developed that incorporates electrolyte and electrode materials prepared by flash combustion (yttrium-doped barium cerate) and auto-ignition (praseodymium nickelate) methods. The fuel cell components were assembled using an anode-support approach, with the anode and proton ceramic layers prepared by co-pressing and co-firing, and subsequent deposition of the cathode by screen-printing onto the proton ceramic surface. When the fuel cell was fed with moist hydrogen and air, a high Open Circuit Voltage (OCV,>,1.1,V) was observed at T,>,550,°C, which was stable for 300,h (end of test), indicating excellent gas-tightness of the proton ceramic layer. The power density of the fuel cell increased with temperature of operation, providing more than 130,mW,cm,2 at 650,°C. Symmetric cells incorporating Ni-BCY10 cermet and BCY10 electrolyte on the one hand, and Pr2NiO4,+,, and BCY10 electrolyte on the other hand, were also characterised and area specific resistances of 0.06,,,cm2 for the anode material and 1,2,,,cm2 for the cathode material were obtained at 600,°C. [source] Modeling of water absorption induced cracks in resin-based composite supported ceramic layer structuresJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008Min Huang Abstract 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. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008 [source] Theoretical study of a membrane reactor for the water gas shift reaction under nonisothermal conditionsAICHE JOURNAL, Issue 12 2009María E. Adrover Abstract A simulation of a membrane reactor for the water gas shift reaction is carried out by means of a 1D pseudo-homogeneous nonisothermal mathematical model. The composite membrane consists of a dense layer of Pd (selective to H2) supported over a porous ceramic layer. The effect of temperature, overall heat-transfer coefficient, and mode of operation on the membrane reactor performance and stability are analyzed, and the results obtained are compared with those corresponding to a reactor with no hydrogen permeation. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Thermophysical Properties of Complex Rare-Earth Zirconate Ceramic for Thermal Barrier CoatingsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 7 2008Liu Ling Two complex rare-earth zirconates (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 and (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 for thermal barrier coatings (TBCs) were synthesized by the coprecipitation method. Their phase composition, microstructure, and thermophysical properties were investigated. X-ray diffractometry results revealed that single-phase (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 and (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 with pyrochlore structure were prepared, and the scanning electron microscopy results showed that the microstructures of the products were dense and no other phases existed among the grains. With the temperature increasing, the thermal expansion coefficient (CTE) of the ceramics increased, while the thermal conductivity decreased. The results indicated that the CTE of (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 was slightly higher than that of (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 and the thermal conductivity of (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 was lower than that of (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4. These results imply that the thermophysical properties of (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 are better than that of (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 as the material for the ceramic layer in the TBC system. [source] Intermediate Temperature Anode-Supported Fuel Cell Based on BaCe0.9Y0.1O3 Electrolyte with Novel Pr2NiO4 CathodeFUEL CELLS, Issue 1 2010G. Taillades Abstract A proton conducting ceramic fuel cell (PCFC) operating at intermediate temperature has been developed that incorporates electrolyte and electrode materials prepared by flash combustion (yttrium-doped barium cerate) and auto-ignition (praseodymium nickelate) methods. The fuel cell components were assembled using an anode-support approach, with the anode and proton ceramic layers prepared by co-pressing and co-firing, and subsequent deposition of the cathode by screen-printing onto the proton ceramic surface. When the fuel cell was fed with moist hydrogen and air, a high Open Circuit Voltage (OCV,>,1.1,V) was observed at T,>,550,°C, which was stable for 300,h (end of test), indicating excellent gas-tightness of the proton ceramic layer. The power density of the fuel cell increased with temperature of operation, providing more than 130,mW,cm,2 at 650,°C. Symmetric cells incorporating Ni-BCY10 cermet and BCY10 electrolyte on the one hand, and Pr2NiO4,+,, and BCY10 electrolyte on the other hand, were also characterised and area specific resistances of 0.06,,,cm2 for the anode material and 1,2,,,cm2 for the cathode material were obtained at 600,°C. [source] Microstructure,Property Relationships for Low-Voltage VaristorsINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 2010Wen-Hsuan Pan The low-voltage varistors with various layer thickness are prepared by laminating thin ZnO-based ceramic layers and AgPd electrodes together. The breakdown voltage dose not exhibit linear relationship with layer thickness. It is due to that the presence of the AgPd electrodes enhances the growth of ZnO grains. As some ZnO grains are large enough to touch the upper and lower electrodes, the breakdown voltage of the varistor is only 3.7 V. The nonlinear coefficient of the low-voltage varistor is 33. Such nonlinear current,voltage behavior is mainly contributed by the interface between the AgPd electrode and ZnO grains. [source] Modeling of water absorption induced cracks in resin-based composite supported ceramic layer structuresJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008Min Huang Abstract 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. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008 [source] Fabrication of multilayer ceramic membranesASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2009V.V. Zyryanov Abstract The development of multilayer mixed conducting oxide membranes on macroporous dead-end tubular composite glass/ceramic substrates is presented. Sol modification of glass/ceramic substrate enhances the performance of catalytic membrane reactor (CMR) with reduced thickness of ceramic layers. The shrinkage misfit between support and ceramic layers can be regulated by different processing steps including sol modification of substrate and preliminary annealing of ceramic powders. Nanopowders of compatible complex perovskites as membrane materials were obtained by mechanochemical synthesis. Porous and dense ceramic layers were supported onto the internal wall of substrate by slip casting of slurries comprised of the narrow fractions of agglomerated powders dispersed in organic media with addition of surfactants. For SrFeO3 -based dense perovskite ceramics, both dynamics of oxygen loss at high temperatures and mechanical properties were found to be affected by the presence of SrSO4 surface inclusions formed due to sulfur admixture in starting reactants. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. 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