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Mons-lez-Liège, Belgium

Muguerra H.,University of Liege | Rivas-Murias B.,University of Liege | Rivas-Murias B.,University of Santiago de Compostela | Traianidis M.,Belgian Ceramic Research Center | And 5 more authors.
Journal of Alloys and Compounds | Year: 2011

We report the high temperature thermoelectric properties of Ca 1-xDyxMn1-yNbyO3-δ (x = 0, 0.02, 0.1 and y = 0, 0.02) synthesized by spray-drying method. A maximum power factor (PF) value of 2.65 μW K-2 cm-1 is obtained at 1100 K for CaMn0.98Nb0.02O 3-δ. This represents an improvement of about 75% with respect to undoped CaMnO3-δ sample at the same temperature. We also provide a complete structural characterization of the samples. © 2011 Elsevier B.V. All Rights Reserved. Source


Maury N.,University of Mons | Cambier F.,Belgian Ceramic Research Center | Gonon M.,University of Mons
Journal of Non-Crystalline Solids | Year: 2011

This paper shows that glass-ceramics containing highly surface and bulk preferentially oriented fresnoite Sr2TiSi2O8 crystals can be synthesised by a simple isothermal heat treatment of suitable glass compositions in the Sr-Ti-Si-K-B-O system. For all tested compositions, crystallisation starts from the free surfaces of the specimens and propagates to bulk with time. If most of these compositions lead to (00l) preferential orientation at the specimens' surfaces, bulk crystal texture is very composition dependent. The effects of variation in K2O and B2O 3 contents on the crystallisation have been studied. It is shown that low K2O and high B2O3 contents are required to keep the (00l) orientation from the surface into the bulk. This result seems to be explained by the viscosities of the initial and residual glasses at the temperature of crystallisation: a low viscosity leads to a fine and homogeneous microstructure with small and strongly (00l) bulk oriented crystals. © 2010 Elsevier B.V. All rights reserved. Source


Latka L.,Ecole Nationale Superieure de Chimie de Lille | Latka L.,University of Lille Nord de France | Pawlowski L.,Ecole Nationale Superieure de Chimie de Lille | Pawlowski L.,University of Lille Nord de France | And 5 more authors.
Surface and Coatings Technology | Year: 2010

Home synthesized (HA) powder was formulated with water and alcohol to obtain a suspension used to plasma spray coatings onto titanium substrate. The deposition process was optimized and the resulting coatings were soaked in simulated body fluid (SBF) for the periods of 3, 7, 14, 28, and 60. days at controlled temperature of 37 °C. The microstructural research enabled to find in the as-sprayed deposits two characteristic zones: (i) dense zone corresponding to the lamellas, observed usually in thermally sprayed coatings; (ii) sintered zone containing fine hydroxyapatite grains corresponding to the fine solids from initial suspension. The sintered zone disappears after soaking in SBF and the pores get filled by the reprecipitated calcium phosphates. The adhesion of the soaked coatings to the substrate was characterized by the critical load in the scratch test and was about 10 to 12. N. The Young modules of the coatings were determined with help of depth-sensing indentation test by the use of the technique developed by Oliver and Pharr. The modules were not depending on the time of soaking and their mean values were 15.6 and 28.4. GPa, depending on the coating operational parameters. The scratch test enables to determine the hardness of the coatings, which remained fairly constant during the time of soaking in the range of 3 to 5. GPa. This hardness was compared to that the Martens microhardness which doubled with time of soaking to reach up to 1. GPa. © 2010 Elsevier B.V. Source


Sarrazin M.,University of Namur | Sarrazin M.,Laboratoire Of Physique Du Solide Lps | Petit F.,Belgian Ceramic Research Center
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We report a mathematical equivalence between certain models of the Universe relying on domain walls and noncommutative geometries. It is shown that a two-braneworld made of two domain walls can be seen as a " noncommutative" two-sheeted spacetime under certain assumptions. This equivalence also implies a model-independent phenomenology, which is presently studied. Matter swapping between the two branes (or sheets) is predicted through fermionic oscillations induced by magnetic vector potentials. This phenomenon, which might be experimentally studied, could reveal the existence of extra dimensions in a new and accessible way. © 2010 The American Physical Society. Source


Jaworski R.,Ecole Nationale Superieure de Chimie de Lille | Pawlowski L.,Ecole Nationale Superieure de Chimie de Lille | Pierlot C.,Ecole Nationale Superieure de Chimie de Lille | Roudet F.,Lille University of Science and Technology | And 2 more authors.
Journal of Thermal Spray Technology | Year: 2010

The paper aims at reviewing of the recent studies related to the development of suspension plasma sprayed TiO 2 and Ca 5(PO 4) 3OH (hydroxyapatite, HA) coatings as well as their multilayer composites obtained onto stainless steel, titanium and aluminum substrates. The total thickness of the coatings was in the range 10 to 150 μm. The suspensions on the base of distilled water, ethanol and their mixtures were formulated with the use of fine commercial TiO 2 pigment crystallized as rutile and HA milled from commercial spray-dried powder or synthesized from calcium nitrate and ammonium phosphate in an optimized reaction. The powder was crystallized as hydroxyapatite. Pneumatic and peristaltic pump liquid feeders were applied. The injection of suspension to the plasma jet was studied carefully with the use of an atomizer injector or a continuous stream one. The injectors were placed outside or inside of the anode-nozzle of the SG-100 plasma torch. The stream of liquid was tested under angle right or slightly backwards with regard to the torch axis. The sprayed deposits were submitted to the phase analysis by the use of x-ray diffraction. The content of anatase and rutile was calculated in the titanium oxide deposits as well as the content of the decomposition phases in the hydroxyapatite ones. The micro-Raman spectroscopy was used to visualize the area of appearance of some phases. Scratch test enabled to characterize the adhesion of the deposits, their microhardness and friction coefficient. The electric properties including electron emission, impedance spectroscopy, and dielectric properties of some coatings were equally tested. © 2009 ASM International. Source

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