Belgian Ceramic Research Center

Mons, Belgium

Belgian Ceramic Research Center

Mons, Belgium
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Latka L.,Ecole Nationale Supérieure de Chimie de Lille | Latka L.,University of Lille Nord de France | Pawlowski L.,Ecole Nationale Supérieure 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.


Jaworski R.,Ecole Nationale Supérieure de Chimie de Lille | Pawlowski L.,Ecole Nationale Supérieure de Chimie de Lille | Pierlot C.,Ecole Nationale Supérieure 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.


Demuynck M.,Belgian Ceramic Research Center | Erauw J.-P.,Belgian Ceramic Research Center | Van der Biest O.,Catholic University of Leuven | Delannay F.,EMPA UCLouvain | Cambier F.,Belgian Ceramic Research Center
Journal of the European Ceramic Society | Year: 2012

In this study, the densification of alumina by spark plasma sintering (SPS) was investigated and compared to conventional hot pressing. It was shown that SPS is very effective in the sintering of alumina leading to higher densities and allows to work at lower temperatures and with shorter sintering cycles. The effect of the heating rate is dependent on the heating mode (SPS or HP). The identification of active sintering mechanisms was attempted by an isothermal and an anisothermal methods, showing that other mechanisms probably related to electrical effects enhance the densification. We suggest the higher contribution of surface diffusion mainly during the initial stage of sintering and an influence of the presence of impurities segregated at the grain boundaries. They could create conductive layers and also introduce ions with a lower valence than Al 3+; defects are created in the surface layers and the diffusion of the species is increased. © 2011 Elsevier Ltd.


Muguerra H.,University of Liège | Rivas-Murias B.,University of Liège | 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.


Muguerra H.,University of Liège | Rivas-Murias B.,University of Liège | Traianidis M.,Belgian Ceramic Research Center | Henrist C.,University of Liège | And 2 more authors.
Journal of Solid State Chemistry | Year: 2010

[Bi1.68Ca2O4-δ]RS[CoO2]1.69 has been obtained by different chimie douce methods and uniaxially or isostatically pressed. The influence of these parameters on the thermoelectric properties has been investigated. Contrary to the Seebeck coefficient, which remains unchanged, the electrical conductivity is greatly modified. In particular, spray-drying synthesis followed by uniaxial pressing results in an electrical conductivity two times larger than in the case of conventional solid state synthesis. Our results suggest that a narrow particle size distribution is beneficial to the thermoelectric properties of the layered compounds. The spray-drying technique seems to be promising to improve the electrical conductivity of layered materials. Moreover, this method presents other advantages (homogeneous samples and less energetic processing) which could be interesting to the future manufacturing of thermoelectric devices. © 2010 Elsevier Inc. All rights reserved.


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.


Sarrazin M.,University of Namur | Petit F.,Belgian Ceramic Research Center
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

This paper investigates a new experimental framework to test the braneworld hypothesis. Recent theoretical results have shown the possibility of matter exchange between branes under the influence of suitable magnetic vector potentials. It is shown that the required conditions might be achieved with present-day technology. The experiment uses a source of pulsed and coherent electromagnetic radiation and relies on the Hänsch frequency comb technique well-known in ultrahigh-precision spectroscopy. A good matter candidate for testing the hypothesis is a polarized ultracold neutron gas for which the number of swapped neutrons is measured. © 2011 American Physical Society.


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.


Lopez-Lopez E.,CSIC - Institute of Ceramics and Glass | Lopez-Lopez E.,University of Oxford | Erauw J.P.,Belgian Ceramic Research Center | Moreno R.,CSIC - Institute of Ceramics and Glass | And 2 more authors.
Journal of the European Ceramic Society | Year: 2012

Zirconium titanate (ZrTiO 4) is a well known compound in the field of electroceramics, however, its potential for structural applications has never been analysed. Moreover, it is compatible with zirconia, thus, zirconium titanate-zirconia composites might have potential for structural applications in oxidizing atmospheres. Nevertheless, there are currently no data about elastic properties of zirconium titanate materials in the literature. In view of the importance of these properties for the structural integrity of components subjected to high temperature and mechanical strains, an attempt was done in this work to determine the elastic properties of ZrTiO 4, both at room and high temperature. Young's modulus (161±4GPa), shear modulus (61±1GPa) and Poisson's ratio (0.32±0.01) values at room temperature have been estimated for a fully dense single phase ZrTiO 4 material from experimental data of sintered single phase ZrTiO 4 materials with different porosities (6-19%). Values for room temperature Young's modulus are in agreement with those obtained by nanoindentation. Young's modulus up to 1400°C shows an unusual dependence on temperature with no significant variation up to 500°C an extremely low decrease from 500 to 1000°C (≈0.02-0.03% every 100°C) followed by a larger decrease that can be attributed to grain boundary sliding up to 1400°C. © 2012 Elsevier Ltd.


Juste E.,Belgian Ceramic Research Center | Petit F.,Belgian Ceramic Research Center | Lardot V.,Belgian Ceramic Research Center | Cambier F.,Belgian Ceramic Research Center
Journal of Materials Research | Year: 2014

Laser additive manufacturing allows the production of polymeric or metallic parts with complex shapes. A major advantage of this contactless technology is that it allows reaching very high energy densities with an excellent precision in short times. This is very suitable for processing hard refractory metals for instance. Unfortunately, current results are less satisfactory for ceramics as a consequence of their intrinsic properties such as a low thermal shock resistance and very high refractoriness. Another significant limitation is related to the poor absorptivity of oxide ceramics in the near-infrared region which is typical for most commercial selective laser melting (SLM) machines. This study considers an alternative to overcome the above-mentioned limitations, especially the lack of absorptivity. SLM of oxide ceramics has become possible. Large parts with complex shapes and relative densities up to 90% have been manufactured on a commercial SLM machine. Copyright © 2014 Materials Research Society.

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