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Particle Composite (particle + composite)

Distribution by Scientific Domains
Engineering40%

Selected Abstracts

Microstructural Characteristics of an AZ91 Matrix-Glassy Carbon Particle Composite,

ADVANCED ENGINEERING MATERIALS, Issue 7 2010
Anita Olszówka-Myalska
This paper presents the results of a microstructural investigation of a new type of ultralight glassy carbon particles (Cp)-AZ91 magnesium alloy matrix composite manufactured by the powder metallurgy method. Glassy Cp with unmodified surfaces and surfaces modified with SiO2 amorphous nanocoating were used in the experiment. The composite microstructure, with an emphasis given on the interface, was characterized by scanning electron microscope (SEM), TEM, and HRTEM microscopy. Uniform distribution of the particles in the matrix and their good bonding with the metal matrix were observed. A continuous very thin MgO oxide layer containing needle-like Al2MgO4 phase was detected at the glassy carbon,AZ91 interface. An increase of aluminum concentration at the interface as a result of Mg and Al diffusion into the SiO2 nanolayer was observed in the case of particles modified with SiO2. Crystalline phases containing carbon were not detected at the interface. [source]

Computational homogenization of uncoupled consolidation in micro-heterogeneous porous media

INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 14 2010
Fredrik Larsson
Abstract Variationally consistent homogenization is exploited for the analysis of transient uncoupled consolidation in micro-heterogeneous porous solids, whereby the classical approach of first-order homogenization for stationary problems is extended to transient problems. Homogenization is then carried out in the spatial domain on representative volume elements (RVE), which are introduced in quadrature points in standard fashion. Along with the classical averages, a higher-order conservation quantity is obtained. An iterative FE2 -algorithm is devised for the case of nonlinear permeability and storage coefficients, and it is applied to pore pressure changes in asphalt-concrete (particle composite). Various parametric studies are carried out, in particular, with respect to the influence of the ,substructure length scale' that is represented by the size of the RVE's. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Variationally consistent computational homogenization of transient heat flow

INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 13 2010
Fredrik Larsson
Abstract A framework for variationally consistent homogenization, combined with a generalized macro-homogeneity condition, is exploited for the analysis of non-linear transient heat conduction. Within this framework the classical approach of (model-based) first-order homogenization for stationary problems is extended to transient problems. Homogenization is then carried out in the spatial domain on representative volume elements (RVE), which are (in practice) introduced in quadrature points in standard fashion. Along with the classical averages, a higher order conservation quantity is obtained. An iterative FE2 -algorithm is devised for the case of non-linear diffusion and storage coefficients, and it is applied to transient heat conduction in a strongly heterogeneous particle composite. Parametric studies are carried out, in particular with respect to the influence of the ,internal length' associated with the second-order conservation quantity. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Excitons in AgI,oxide particle composites: AgI,SrTiO3

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2006
Fumito Fujishiro
Abstract We fabricated (x)AgI,(1,x)SrTiO3 fine particle composites over a wide composition range of 0,100 mol% AgI. It is found that the dispersion of SrTiO3 fine particles enhances the ionic conductivity and (0.6)AgI,(0.4)SrTiO3 has the highest ionic conductivity (1.68 × 10,4 S/cm which is two hundreds times in comparison with that of pristine AgI), for the first time. In order to clarify such ionic conductivity enhanced by dispersing SrTiO3 fine particles into AgI, the photoluminescence measurements were carried out at different temperatures between 10 K and room temperature under different photoexcitation intensities, together with the structural and morphological studies (X-ray diffractometry, scanning electron microscopy and energy dispersive X-ray fluorescence spectroscopy). The spectra consist of free exciton luminescence band and several broad luminescence bands due to the excitons trapped at crystal defects and residual impurities. The free exciton luminescence band almost disappears at x = 0.6, which may suggest the existence of considerable number of non-radiative traps (crystal defects) at the AgI/SrTiO3 particle interfaces. Such crystal defects may act as ionic pathways. The structural and morphological studies confirm the randomly-stacked ,AgI/,AgI heterostructures at the AgI/SrTiO3 particle interfaces. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]