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Multilayer Systems (multilayer + system)
Selected AbstractsMicrostructural and Mechanical Investigations on Porcelain-Fused-to-Metal in Multilayer SystemADVANCED ENGINEERING MATERIALS, Issue 4 2010Adele Carraḍ 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] Joining Strategies for Open Porous Metallic Foams on Iron and Nickel Base Materials,ADVANCED ENGINEERING MATERIALS, Issue 8 2007S. Longerich Within the Collaborative Research Centre (SFB) 561 "Thermally highly loaded, porous and cooled multilayer systems for combined cycle power plants" open porous Ni-based structures are developed for the requirements of an effusion cooling. A two-dimensional cooling strategy for the walls of combustion chambers, that allows the outflow of the cooling medium over the complete wall area of the combustion chamber, could be realized by an open porous metallic foam structure. The challenge is to join the porous foam structure with the solid substrate material. Capacitor discharge welding and laser beam welding/-brazing methods seems to be promising methods due to a minimum input of energy and, connected with this, a small joining zone. [source] Modeling of Thermal Stresses in Joining Two Layers with Multi- and Graded InterlayersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2006C. H. Hsueh The technique of introducing interlayers has been used extensively to mitigate residual thermal stresses in joining dissimilar materials. Finite-element analyses have often been used to quantify thermal stresses in these layered structures in case-by-case studies. Recently, simple analytical models containing only three unknowns have been developed to derive closed-form solutions for elastic thermal stresses in both multilayer systems and two layers joined by a graded junction. The analytical solutions are exact for locations away from the free edges of the system. Application of these solutions is shown here to provide a systematic study of thermal stresses in Si3N4 and Al2O3 layers joined by various sialon polytypoid-based multi- and graded interlayers. The effects of the thickness, stiffness, and coefficient of thermal expansion of the interlayer on thermal stresses in the system are examined. The differences in thermal stresses resulting from multi- and graded interlayers are shown. [source] Analysis of optical and terahertz multilayer systems using microwave and feedback thoeryMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 5 2009Dong-Joon Lee Abstract The principles of microwave and feedback theory are independently applied to the analysis of both optical and terahertz-regime multilayer systems. An analogy between the two approaches is drawn, and useful recursion relations, along with a signal-flow approach, are presented for both reflection and transmission cases. These relations, in terms of S-parameters, allow an exact analytical solution for even arbitrary, active, stratified structures, not only for any wavelength in the radio-frequency spectrum, but also for optical wavelengths. This approach also provides a bridge between the microwave and optical bands and leads to beneficial design solutions for intermediate bands such as the THz regime. Comparisons with conventional methodologies are provided using practical multilayer simulations. In addition, graphical design techniques from microwave theory are used along with examples for efficient design and understanding. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1308,1312, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24301 [source] Studies on structural and optical properties of Cu-Sb-O thin filmsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 9 2010Nadia Chaglabou Abstract We report in this paper the structural and optical properties of Cu-Sb-O thin films systems. Samples were prepared via sequential thermal vacuum deposition of Cu and Sb or Sb and Cu (10 -5 Torr) on glass substrates after what they were heated in vacuum at 200 °C for 1 hour. So, the obtained intermetallic multilayer systems (Cu/Sb)j=1,2,3 and (Sb/Cu)j=1,2,3 were annealed in air atmosphere between 30°C and 400 °C for 3 h for j=1; for 6 h for j=2 and for 9 h for j=3. These films were characterized for their structural, surface morphological, compositional, and optical properties by using X-ray diffraction (XRD) and optical (transmittance and reflectance) measurement techniques. The X-ray diffraction (XRD) patterns revealed the presence of CuO, Sb2O3 and Sb2O4phases. The absorption coefficient of Cu-Sb-O thin films in all cases is in the range104 -105 cm -1. The films after annealing have two direct band gap energies in the ranges 1.48,1.50 eV and 2.20-2.95 eV. The electrical measurements show a conversion from a metallic phase to the semiconductor phase after annealing. The samples exhibit p-type conductivity after annealing in air of the intermetallic multilayer systems (Cu/Sb)j=3 and (Sb/Cu)j=3. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Many-beam dynamical simulation for multilayer structures without a superlattice cellACTA CRYSTALLOGRAPHICA SECTION A, Issue 2 2009Masahiro Ohtsuka A many-beam dynamical theory for plan-view high-resolution transmission electron microscopy (HRTEM) images of multilayer systems without the limitation of a superlattice cell is proposed. The accuracy of our method is examined by comparing convergent-beam electron-diffraction calculations of Si(011) and HRTEM calculations of a system of epitaxial Al(100) on GaAs(100). Furthermore, this method is applied to CdSe clusters embedded in MgO, where it is revealed that the relative shift of their crystal-lattice planes produces moiré-like fringes. [source] | ||||||||||