The InSb thin films were successfully prepared from binary alloy target by Pulsed Laser Deposition (PLD) onto heated Si/SiO2 substrates at various deposition temperatures (Td) ranging from room temperature to 400 degrees C. The evolutions of structural (XRD, XPS), microstructural (AFM, SEM) and optical (XPS, FTIR, RAMAN) properties as a function of deposition temperature were systematically taken into account. The analyzed results indicate that the films are well crystallized with Zinc Blende (ZB) structure for Td >= RT. Increasing Td induces significant signature of preferentially crystal orientations of (h11) accompanied by distinctive microstructural evolution from continuous fashion (Td <= 300 degrees C) to almost isolated islands feature (Td >= 350 degrees C). Derivations of crystallite sizes, lattice strain, dislocation density, Lotgering orientation factor, and root mean square roughness were correlated with Raman shift and XPS analysis, and optical properties. The developed thin films allow to observe the flex-ibility of optical band gap energy (from 0.18 eV to 0.50 eV), which is directly related to the quantum confinement effect coupled with the band-filling effect of Burstein-Moss shift.

To control ZrC oxidation, one method is to coat the surface with SiC. This work therefore aims at grafting polymeric precursors on functionalized ZrC surfaces en-route to synthesizing ZrC/SiC core/shell composites. The exposed surface on the zirconia side of t-ZrO2(001) (tetragonal ZrO2) on top of a ZrC(100) substrate is first modified in presence of water. Water preferentially adsorbs molecularly and a subsequent functionalization with allylchlorodimethylsilane (ACDMS) in a SN reaction, appeared quite weak. However, the following grafting of a repetitive unit of the polymeric precursor, built from diphenylsilane and 1,4-diethynylbenzene monomers through a hydrosilylation reaction, is a highly favorable and exothermic reaction. As the main problem occurs during the nucleophilic substitution reaction between ACDMS and hydroxyl groups on the surface, two bifunctional organic molecules, but-3-enoic acid as well as glycolic acid, were also exploited. But-3-enoic acid adsorbed strongly to the Zr atoms of the surface, through chelating effects of the carboxylic acid group. The subsequent hydrosilylation reaction with a repetitive unit of the preceramic precursor was also a favorable exothermic reaction, indicating a promising approach for the grafting of organic macromolecules. In parallel, to associate experimental results, methyldiphenylsilane was grafted onto functionalized ZrC using but-3-enoic acid.

In order to achieve future ZrC/SiC core-shell structures, hybrid ZrC-polycarbosilane materials were synthesised. To fabricate these organic coated non-oxide ceramics, the surface was first functionalised with allylchlorodimethylsilane (ACDMS) in a simple procedure. The organic covalent grafting of the carbosilane onto zirconium carbide particles was confirmed by XPS, TEM and TG-MS analyses. The effect of the temperature and of the organosilicon molecule concentration has also been investigated to check their role on the functionalisalon efficiency of zirconium carbide surfaces. The modified surfaces with allyl groups were then subjected to a hydrosilylation reaction to graft a polycarbosilane. XPS, together with TG-MS and TEM images confirmed the presence of an organic coating with a thickness up to 30 nm, indicating the presence of core (ZrC)/shell (polycarbosilane) structures.

A reactor based on the association of a pulsed laser nanoparticle source and a pulsed laser deposition process is presented. This process uses two independent nano-second pulsed lasers. The nanoparticle source, based on a quenching of a plasma plume, is accurately described. Nanoparticles produced by this dedicated laser-based source present intrinsically quasi-monodisperse size in the range of 1–10 nm. This monodispersity is essential to correlate nanoparticle size and related properties. For silver nanoparticles, a change in a characteristic parameter, the opening t-time of the quenching valve, (conditioning the species residence time) from 280 μs to 580 μs, leads to a nanoparticle size increase by a factor of about two (from 2.5 nm to 4.3 nm). Consequently, the size modulation allows the synthesis of nanoparticles and resulting nanocomposites which present drastically different properties. A kinetic model in good agreement with the experiment shows two nanoparticle growth modes, i.e., a monomer accretion and a cluster coagulation. Revealing the potential of the pulsed laser reactor, different nanocomposite materials constituted by Ag nanoparticles associated with oxide thin films (Al2O3, VO2) matrix are optically characterized. A surface plasmon resonance (λSPR) in the visible–near IR regime is evidenced, and huge modulation and tunability are obtained linked to the host matrix nature and nanocomposite architecture. Moreover, the metal insulator transition capacity of a vanadium dioxide matrix makes λSPR tunable as a function of temperature. This type of nanocomposite appears pertinent for their great potential in both nano-photonics and nano-sensors.

Hydrogenated amorphous carbon thin films containing aluminum (a-C:H:Al) have been produced by a hybrid technique using plasma enhanced chemical vapor deposition and magnetron sputtering of an aluminum target. Various sputtering powers were used in order to explore different Al/(Al+C) ratios. Two deposition configurations for the substrates were tested: a dynamic and a static. The dynamic mode led to a multilayered structure made of alternating Al-rich and Al-poor layers with a total thickness of about 40nm for each period. Regardless of the deposition mode, nanoindentation showed that an increase in Al concentration resulted in a decrease in hardness compared to the pure a-C:H coatings. Moreover, the hardness of the dynamic a-C:H:Al films was less affected and seemed to be weighted between the power-equivalent static Al-doped DLC and the pure a-C:H. The results of tribological characterization in dry conditions indicated that the friction coefficient was significantly reduced by the introduction of Al from 0.2 to less than 0.1 for all of the Al-doped films. However, the wear resistance was also affected by the doping. Nevertheless, Al doping compatible with industrial purpose (i.e. dynamic mode) can be considered at moderate sputtering power in order to obtain a-C:H:Al coatings that exhibit low friction coefficient and moderate wear rate in relation with good hardness and H/E ratio.

The effect of stoichiometry (i.e. carbon and oxygen contents) and microstructure (i.e. micro-sized grains) on creep mechanism of zirconium oxycarbide was considered. The synthesis of ZrCxOy powder of controlled stoichiometry and without impurity has been performed via the carboreduction route. Compressive creep experiments were conducted at 1500–1600°C under applied stresses ranging from 60 to 140MPa on fully dense zirconium oxycarbide specimens obtained by spark plasma sintering. The higher oxygen content composition (i.e. ZrC0.79O0.13) reveals low creep resistance in contrary to ZrC0.94O0.05 composition. The analysis of the creep data shows the existence of a linear creep limit (σt). At low stress (i.e. σ≤σt=100MPa, n≈1, m≈1), the creep mechanism seems to be independent of the chemical composition, and is governed by zirconium volume diffusion. At high stress (i.e. σ≥σt=100MPa, n≈3, m≈0), a power law regime of creep appears. However, the nature of the rate-determining step of creep process depends on stoichiometry. The limiting species for volume diffusion are (i) the metal atom for ZrC0.94O0.05; (ii) and the carbon atom for ZrC0.79O0.13 linked to a Rowcliffe dislocation diffusion mechanism.

Starting from core-shell zirconium carbide powders, a covalent grafting was described, using a direct nucleophilic substitution in diethyl ether. Thus, two different organic molecules were attached onto the surface of the ceramic, through Si-O-Zr and C-O-Zr bonds. The materials were characterized by means of TEM and XPS characterizations. These new systems could represent an original route to elaborate zirconium carbide-based hybrid materials. (C) 2013 Elsevier B.V. All rights reserved.

Hydrogenated amorphous carbon thin films containing fluorine (a-C:H:F) have been produced by radio-frequency plasma enhanced chemical vapor deposition by using different F/H ratios in the gas phase. The introduction of fluorine from 0 to 19at.% resulted in a decrease of hydrogen content and to the formation of CF and CF2 bonds. For all the films, Raman analysis showed a typical diamond-like carbon response with an evolution of the structure to larger sp2 clusters with less hydrogen while fluorine content increased. The drop in hardness generally observed in the literature with fluorine introduction was less abrupt here: for a fluorine content up to 6.5at.%, the measured hardness was 28GPa, and for 19at.% of fluorine, value was 20GPa. These are quite high values for a-C:H:F thin films. Moreover, fluorine improved tribological behavior in dry conditions with friction coefficient slightly reduced at low fluorine content and wear rate significantly reduced: divided by two to four than the fluorine free reference coating.

Drug loaded porous calcium phosphate bone substitutes are studied for targeted drug delivery applications. In this study, porous hydroxyapatite and beta-tricalcium phosphate pellets were investigated as anti-inflammatory drug carriers and their ibuprofen adsorption and release properties were compared. While the adsorption equilibrium time of 1 h was obtained for both pellets, hydroxyapatite pellets showed a higher adsorption capacity than beta-tricalcium phosphate. The physico-chemical characterisations of loaded pellets confirmed an ibuprofen reversible physisorption on both hydroxyapatite and beta-tricalcium phosphate pellets. Moreover, higher adsorption capacity of hydroxyapatite was attributed to their physical differences. The in vitro ibuprofen release evaluation showed 100% release of ibuprofen from both hydroxyapatite and beta-tricalcium phosphate pellets which was found to be compatible with the obtained interactions between the pellets and ibuprofen.

The adhesion of plasma-sprayed coating is, to a large extent, controlled by the cleanness and roughness of the surface on which the coating is deposited. So, most of the plasma spray procedures involve surface pretreatment by grit-blasting to adapt the roughness of the surface to the size of the impacting particles. This preparation process brings about compressive stresses that make it inappropriate for thin substrates. The present works aim to elaborate a thick ceramic coating (about 0.5 mm thick) on a thin metal substrate (1 mm thick) with a smooth surface (Ra of about 0.4 μm). The coating system is intended for use in a Generation-IV nuclear energy system. It must exhibit a good adhesion between the ceramic topcoat and the smooth metal substrate to meet the specifications of the application. Our approach consisted of depositing the ceramic topcoat by air plasma spraying on a few micrometers thick ceramic layer made by suspension plasma spraying. This nanostructured layer played the role of a bond coat for the topcoat and made it possible to deposit it on the as-received substrate. The adhesion of the nanostructured layer was measured by the Vickers indentation cracking technique and that of the ceramic duplex coating system by tensile test.

SiO x H y C z nanometric layers are deposited from hexamethyldisiloxane by atmospheric pressuremicrowave plasma torch on Si(100) substrates submitted to temperatures varying on therange [0 °C; 120 °C]. Atomic force microscopy (AFM) characterizations of samples grown atintermediate substrate temperatures (~30 °C) demonstrate a layer-by-layergrowth (Frank van der Merwe growth) leading to smooth flat and compact films while filmsdeposited at lower and higher substrates temperatures show an island-like growth(Volmer-Weber growth) generating a high surface roughness. Concomitantly, a detailedinfrared spectroscopy analysis of the growing films evidences structural modifications dueto changes in the bond types, Si-O-Si conformation and stoichiometry correlated withscanning electron microscopy and AFM characterizations. Then, deposition conditions andspecific microstructure are selected with the aim of generating 3-dimensionalSiO x H y C z nanostructure arrays on nanoindented Si (100) templates. The first results arediscussed.

From the early beginning of the oxidation of 304L stainless steel in carbon dioxide at 1273 K (1 min, for a weight gain of 0.02 mg cm−2), the surface of the alloy was entirely covered by oxides: magnetite Fe3O4, chromia Cr2O3 and traces of wüstite Fe1−xO. Later on, for weight gains approaching 1 mg cm−2, magnetite remained at the outer interface, with traces of hematite (Fe2O3), above a thick layer of wüstite Fe1−xO. Magnetite and wüstite may favour adhesion of thermal plasma protective coatings such as alumina.

A liquid aluminosilazane precursor, with various Al contents, was synthesized by direct reaction between hexamethyldisilazane and trimethylaluminum at room temperature. Mass spectrometry and Fourier-transform infrared spectroscopy showed respectively a methane evolution and the formation of AlN bonds. Thermal-spray pyrolysis of this precursor was realized under different conditions: temperature (1200–1400°C), pyrolysis atmosphere (Ar, Ar/NH3) and gaseous flow rate (1 and 3Lmin−1). SEM micrographs revealed spherical SiCNAl(O) nanopowders which size (20–180nm in diameter) depending on the residence time duration of the product in the furnace. Pyrolysis under argon led to a high C content, and then to the presence of free carbon and amorphous SiC phase detected by XRD and NMR analysis. Introduction of ammonia in the pyrolysis atmosphere induced an important decrease of C content in the pre-alloyed nanopowders, correlated with an increase of N and Al. With this process, multielement nanopowders with an adjustable composition exhibit a higher thermal stability than powders processed by laser-spray pyrolysis with an equivalent precursor.

Carbon fiber based composites exhibit very good thermal and mechanical properties under inert atmospheres but require a protection in oxidising environments. To date, the best candidates for this protection are borides and carbides, despite being difficult to sinter. A new process has been developed for the elaboration of coatings and monoliths in the HfB2-SiC system. The microstructure was characterized using various techniques such as porosimetry, XRD, SEM, TEM, microanalysis and AES. The behaviour of such materials has been studied in the 800-1700degreesC temperature range in flowing O-2/He mixtures (PO2 = 10(2) to 2.10(4) Pa). The good oxidation resistance up to 1700degreesC is explained by the diffusion of oxygen through a protective borosilicate layer when the composition changes with a release of boron species and a progressive dissolution of HfO2.

In order to improve the work of fracture of TiN-TiB2 ceramic composites and suppress catastrophic failure, an architecture has been design consisting of a copper interlayer inserted between two outer ceramic sheets. The TiN-TiB2 ceramic composite was densified to 99.7 % of theoretical density by hot-isostatic pressing of an equimolar mixture of TiN and TiB2 at 1850degreesC under a pressure of 190 MPa. The assembling of the three layered sandwich was performed by uniaxial pressing at 1000degreesC under 40 MPa. The very high malleability of copper results in an excellent intrusion into the surface roughness of the ceramic sheets ensuring a good mechanical interlocking. This mechanical join is supplemented by a chemical inter-diffusion. The stress-strain curves in 3-point bending of SENB samples exhibit a residual strength of 110 N once the ceramic sheets have broken. So, the rupture is not catastrophic. The deflection at rupture is five times greater than that of the monolithic material and the work of rupture is as high as 5450 J/m(2).

This study deals with the understanding of the cadmium uptake mechanism by synthetic stoechiometric hydroxyapatite (Ca-10(PO4)(6)(OH)(2)) in aqueous solution. Three parameters were studied : the powder specific surface (S-BET) the initial Cd2+ concentration ([Cd2+](o)) and the time of the sorption experiments (t(contact)). We have find that the quantity of cadmium immobilized by the hydroxyapatite is mainly controlled by the sample specific surface area. The analyses after the reactions of immobilization, indicate the presence of cadmium adsorbed to the surface of crystallites and a solid solution of the Ca(10-x)Cdx(PO4)(6)(OH)(2) type (with x = 1 + 3y and 1 < x < 4).

Apatitic tricalcium phosphate Ca9(HPO4)(PO4)5(OH) is a calcium orthophosphate that transforms into β-tricalcium phosphate Ca3(PO4)2 by heating above 750°C. This work deals with powder synthesis using a wet precipitation method. An experimental design is applied to precise the influence of the synthesis parameters on the chemical composition (e.g. the Ca/P molar ratio). The Ca/P ratio of the precipitates varies greatly according to the pH value and the temperature of synthesis. A more or less important increase of the Ca/P ratio can occur with the ripening time in dependence on the value of the previous parameters. A reproducible synthesis of pure apatitic tricalcium phosphate (TCP) powders is attained by refinement of the parameters. The study is completed by physicochemical characterizations and the thermal behavior of the powders. X-ray diffractometry and differential thermal analysis are necessary to insure the purity of TCP powders. The decomposition of the apatitic TCP into β-TCP during heating influences the sintering behavior.

Ultrafine SiCN particles with various compositions, synthesised by laser pyrolysis in interaction either with gaseous or liquid reactant, were heat treated at temperatures between 300 and1773 K. Thermogravimetric measurements performed under inert (helium) atmosphere, showed that the best thermal stability was exhibited by nanopowders prepared from gaseous precursors (SiH4, CH3NH2, NH3). Mass spectrometry analysis data revealed that nanopowders derived from a mixture with ammonia and hexamethyldisilazane (HMDS) contained more N-H and C-N groups than those obtained without ammonia. The loss of hydrogen clearly dominated amongst the observed losses in all the examined samples at all temperatures. This study indicates that thermal degradation of such silicon based systems is not a single reaction but the net result of a number of reactions.