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Dissimilar linear friction welding of selective laser melted Inconel 718 to forged Ni-based superalloy AD730TM: evolution of strengthening phases
No full textInternational audienceThe continuous growth in the manufacture of aerospace components such as blisks has led to an increase in the application of different hybrid materials fabricating methods, and thus the requirements for joining and strengthening of dissimilar welds. According to this goal, selective laser melted (SLM) Inconel 718 was joined with forged AD730TM Nickel-based superalloy through linear friction welding (LFW) in this study. Microstructure variation, specifically with respect to secondary phases precipitation was investigated. The microhardness and strengthening mechanisms of the weldment were also studied. The precipitation (volume fraction and size of particles) at different regions of both sides of the weld line was characterized. Close to the weld line, the dissolution of γ'/γ" and Laves phases and grain refinement occurred which reveals the effects of both compression strain and high temperature on recrystallization and high degree of elemental diffusion in the weld zone (WZ). It is shown that the size, volume fraction, and shape of secondary phases increased and changed (from spherical to long-striped for Laves particles) as we went from the WZ toward the base metal. However, the measured microhardness indicated that the strength of AD730TM alloy depends significantly on the grain size, while strength in SLM Inconel 718 was dominated by shape (or size) and the presence of secondary phases (γ'/γ" and Laves)
Parametric study via full factorial design for glycerol supercritical gasification
No full textInternational audienceSupercritical water gasification is a promising technology for pollution treatment and syngas pro- duction from biomass. The produced gas is composed of hydrogen, carbon dioxide, methane, car- bon monoxide and traces of ethane and other light hydrocarbons. This work aims to give a comprehensive experimental study of the supercritical water gasification of glycerol using a full factorial design of experiments (DOE). The effect of five factors, namely: temperature [458°C–542°C], residence time [40–90min], pressure [23–27MPa], initial concentration of glycerol [10–19wt%] and KOH catalyst quantity [0.60–1.475wt%], were investigated on several responses such as the gasification efficiency (GE), syngas composition and lower calorific value (LCV) of the produced gas. First order mathematical models correlating each considered response in terms of the considered factors were developed and validated. Also, the significance of the factors effect was validated using analysis of variance. The results showed that the produced gas composition and quality were strongly influenced by temperature and initial concentration. The largest gas pro- duction was detected at a temperature of 542°C, a residence time of 40min, a pressure of 27MPa, a concentration of 10 wt% glycerol and a KOH catalyst percentage of 1.475 wt%
Biocomposites à base de phosphate de calcium, de nanocellulose et de chitosan pour des applications environnementales
No full textBased on the WHO (World Health Organization) reports (2017), around 2.1 billion people do not have any access to a reliable drinking water supply at home. Conventional pollutants like heavy metals, dyes, domestic and industrial wastes along with emerging pollutants like antibiotics, hospital wastes and personal care products end up in water that creating new challenges in purification. Nanocomposites are the most explored material in recent times for water purification. However, nanocomposites combining adsorption and size exclusion capacities have not been well explored so far to optimize the removal of a wide range of pollutants. In this regard, this work focuses on the formulation of a green nanocomposite (GNC) that also excludes the use of any polluting chemicals. The GNC combines calcium phosphate (CaP), an excellent sorbent of conventional and emerging pollutants with biomass-derived nanocellulose (NC) and chitosan (CH) to form a ternary nanocomposite. NC exhibits excellent mechanical property, film-forming capacity and CH has outstanding adsorption capacity and processibility. The mechanical, physical, morphological characterizations and performance evaluations were carried out on the raw materials and different GNCs to identify optimum formulation based on performance and adsorption. Thermal stability and kinetic triplets were outcomes that demonstrated the increase of CaP in the formulation also increase the activation energy and reducted mass loss of the GNCs. Upon filtrating synthetic wastewater having a mix of 10ppm Ni ion and 10 ppm congo red dye, the nanocomposite exhibited pollutant removal up to 99% and 100% respectively for Ni ion and CR dye. Experimental breakthrough data were modelled with empirical models based on pollutant removal studies. Models considering mass balance, membrane fouling, diffusion coefficient, mass flow rate prediction showed that increasing the pollution concentrations in the feed from 10ppm to 150ppm resulted in a reduction in the rate of adsorption whereas increased both membrane fouling and diffusion. The GNC selected was used for pollutants removal from industrial wastewater. The pollutants such as Cd, Mn, Pb, Se, Sr, V were removed 100% whereas Cr, Li, Mg were removed 94%, 78% and 94% respectively from industrial wastewater. A scaled-up purification setup was used to evaluate the performance of the GNCs with both synthetic and industrial wastewater demonstrating similar results. In addition, an economical assessment was proposed. Overall, this work demonstrated that, GNCs can be formulated without using any harmful chemicals or complex modifications which could be efficiently applied in drinking water production.Sur la base des rapports de l'OMS (Organisation Mondiale de la Santé) (2017), environ 2,1 milliards de personnes n'ont aucun accès à un approvisionnement fiable en eau potable à domicile. Les polluants classiques tels que les métaux lourds, les colorants, les déchets domestiques et industriels ainsi que ceux émergents tels que les antibiotiques, les molécules issues des déchets hospitaliers et des produits de soins personnels se retrouvent dans l'eau, ce qui crée de nouveaux défis en matière de purification. Les nanocomposites sont les matériaux les plus explorés pour la purification de l'eau. Cependant, ces derniers combinent des capacités d'adsorption et d'exclusion de taille qui n'ont pas suffisamment été explorées jusqu'à présent. Ces performances pouvant être utilisées afin d’optimiser l'élimination d'une large gamme de polluants. À cet égard, ce travail se concentre sur la formulation d'un nanocomposite durable (GNC) qui exclut également l'utilisation de tout produit chimique polluant. Le GNC combine le phosphate de calcium (CaP), un excellent absorbant des polluants conventionnels et émergents, la nanocellulose (NC) et le chitosan (CH) issus de la biomasse pour former un nanocomposite ternaire. La NC présente d'excellentes propriétés mécaniques et une capacité de formation de films, tandis que le CH possède une capacité d'adsorption et une facilité de traitement. L’identification des caractéristiques mécaniques, physiques, morphologiques et de performance des matières premières et des différents GNC ont permis de faire émerger la formulation la plus optimale basée sur la performance et l'adsorption. Les résultats de l'analyse de la stabilité thermique et des triplets cinétiques ont démontré que l'augmentation du CaP dans la formulation augmente également l'énergie d'activation et réduit la perte de masse des GNC. Lors de la filtration d'eaux usées synthétiques contenant un mélange de 10 ppm d'ions Ni et de 10 ppm de colorant rouge congo, le nanocomposite a montré une élimination des polluants jusqu'à 99% et 100% respectivement pour les ions Ni et le colorant CR. Les données expérimentales ont été modélisées avec des modèles empiriques décrivant l’adsorption des polluants. Les modèles mettant en oeuvre le bilan massique, l'encrassement de la membrane, le coefficient de diffusion, la prédiction du débit massique ont montré que l'augmentation des concentrations de pollution dans l'alimentation de 10ppm à 150ppm a entraîné une réduction du taux d'adsorption alors que l'encrassement de la membrane et la diffusion ont augmenté. La GNC sélectionnée a été utilisée pour l'élimination des polluants des eaux usées industrielles. Les polluants tels que Cd, Mn, Pb, Se, Sr, V ont été éliminés à 100% tandis que Cr, Li, Mg ont été éliminés à 94%, 78% et 94% respectivement. Une installation de purification à grande échelle a été utilisée pour évaluer la performance des GNCs sur des eaux usées synthétiques et industrielles et ont montré des résultats similaires. Une étude économique a également été proposée. Dans l'ensemble, ce travail a démontré que les GNCs peuvent être préparés sans utiliser de produits chimiques nocifs ou de modifications complexes, ce qui pourrait être une application efficace dans la production d'eau potable
Valorisation catalytique des gaz à effet de serre : du CO2 et du CH4 à la synthèse de molécules d'intérêt
No full textSyngas (a mixture of CO and H2), is a versatile feedstock which can be used in several industrial processes: methanol and ethanol synthesis, hydrogen production via water-gas-shift, liquid fuels production etc.. Herein we propose a sequential strategy encompassing two catalytic transformations for the sustainable production of amines starting from CO2 and CH4 via the production of syngas in high yields and controlled CO:H2 composition ratios. Firstly, we present our efforts towards the optimization of the tri-reforming of methane (TRM) reaction using supported Ni-based nanocatalysts. Different key parameters have been studied to enhance the catalytic performance towards the syngas formation, such as the nature of the support, and the engineering of the active phase (small and well-defined nickel nanoparticles, enhancement of the metal-support interaction, etc.), in the search for highly efficient catalysts from abundant sources. A full characterization of the as-prepared catalytic materials is described.Secondly, the new catalytic materials have been evaluated towards the hydrogenation of several functional groups such as alkynes, alkenes, aldehydes, ketones, nitriles, and nitro groups... Depending on the nature of the support and stabilizer, differential catalytic behaviors were found for the different catalysts prepared. Actually, nickel nanoparticles immobilized on halloysite-based supports resulted highly tunable catalysts that enabled the valorization of biomass derived substrates (such as fatty acids, squalene levulinic acid, furfural).Additionally, the syngas generated by TRM has been used in tandem hydroaminomethylation (HAM) reactions catalyzed by an original rhodium/cobalt homogenous system, in combination with bio-sourced substrates, in particular terpenes. This interesting transformation from environmental (atom efficiency, high selectivity avoiding by-products and only producing water as concomitant product) and economic (inexpensive alkenes, energy saving) viewpoints allows not only a direct entry to the synthesis of amines, but it also validates the use of greenhouse gases for future industrial applications to fight against climate change.Le gaz de synthèse (mélange de CO et H2), est une matière première polyvalente qui peut être utilisée dans plusieurs procédés industriels : synthèse de méthanol et d'éthanol, production d'hydrogène par réaction de gaz à l’eau (water-gas-shift), production de carburants liquides, etc... Nous proposons ici une stratégie séquentielle englobant deux transformations catalytiques pour la production durable d'amines à partir de CO2 et CH4 par la production contrôlée de gaz de synthèse (en ratio et à haut rendement).Dans un premier temps, nous prévoyons de présenter nos efforts pour l'optimisation de la réaction de tri-reformage du méthane (TRM) avec des nanocatalyseurs à base de Ni supportés. Différents paramètres clés ont été étudiés pour améliorer les performances catalytiques, comme la nature du support, l'utilisation ou l'ingénierie de la phase active (synthèse de petites nanoparticules de nickel, amélioration de l'interaction métal-support, etc.) dans la recherche de catalyseurs à haut rendement provenant de sources abondantes. Une caractérisation complète des matériaux catalytiques préparés sera présentée.Deuxièmement, les matériaux catalytiques préparés ont été évalués vis-à-vis de l'hydrogénation de plusieurs groupes fonctionnels tels que les alcynes, les alcènes, les aldéhydes, les cétones, les nitriles, les groupes nitro... Selon la nature du support et du stabilisant, un comportement catalytique différent a été trouvé. En fait, les nanoparticules de nickel immobilisées sur des argiles ont donné un catalyseur polyvalent et très efficace, y compris avec des substrats issus de la biomasse.Enfin, le gaz de synthèse a été utilisé dans des réactions d'hydroaminométhylation (HAM) en combinaison à partir de terpènes biosourcés. Cette transformation est intéressante d'un point de vue environnemental (économie d’atomes, haute sélectivité évitant les sous- produits et ne produisant que de l'eau comme produit concomitant) et économique (alcènes peu coûteux, économie d'énergie). Globalement, cette stratégie durable permet non seulement d'entrer directement dans la synthèse des amines, mais également de valider l'utilisation des gaz à effet de serre pour les futures applications industrielles de lutte contre le changement climatique
Développement de formes solides non conventionnelles pour la chimiothérapie orale
No full textThis thesis focuses on the solid state transformation of an anti-cancer pharmaceutical active molecule, Erlotinib (ERL), into two different supersaturated forms (amorphous solid dispersions and co-crystals). To define the 2 solid forms, solid dispersions are based on a formulation technology in which the active ingredient is dispersed in an amorphous carrier. It facilitates the dissolution of poorly water-soluble drugs mainly by presenting the drug in an amorphous form. Co-crystals, on the other hand, are generally composed in a stoichiometric ratio of an active ingredient and a non-toxic molecule called a co-former. These forms aim to limit side effects by improving the bioavailability of the molecule during oral chemotherapy. The parameters of the study were the polymers for the amorphous solid dispersions and the co-formers for the co-crystals and the synthesis processes (spray drying and hot melt extrusion for the amorphous solid dispersions and solution crystallization for the co-crystals). After synthesis and characterization of the two solid forms of ERL, they were compared in terms of solubility in aqueous medium and in vitro dissolution. The amorphous solid dispersions showed a better effect on ERL solubility at pH 6.8 and inhibition of ERL crystallisation during simulated gastric-intestinal transfer.Cette thèse porte sur la transformation de l'état solide d'une molécule active pharmaceutique anti-cancéreuse, Erlotinib (ERL) en deux différentes formes sursaturées (dispersions solides amorphes et co-cristaux). Pour définir les 2 formes solides, les dispersions solides sont basées sur une technologie de formulation dans laquelle le principe actif est dispersé dans un support amorphe. Elle facilite la dissolution des médicaments peu solubles dans l'eau principalement en présentant le médicament sous une forme amorphe. Les co-cristaux, quant à eux, sont généralement composés dans un rapport stœchiométrique d'un ingrédient actif et d'une molécule non toxique appelée co-formeur. Ces formes visent à limiter les effets secondaires en améliorant la biodisponibilité de la molécule lors d'une chimiothérapie orale. Les paramètres de l'étude ont été les polymères pour les dispersions solides amorphes et les co-formers pour les co-cristaux et les procédés de synthèse (séchage par atomisation et extrusion à chaud pour les dispersions solides amorphes et cristallisation en solution pour les co-cristaux). Après un travail de synthèse et caractérisation des deux formes solides d'ERL, elles ont été comparées en termes de solubilité en milieu aqueux et dissolution in vitro. Les dispersions solides amorphes ont montré un meilleur effet sur la solubilité de l'ERL à un pH de 6,8 et l'inhibition de la cristallisation de l'ERL pendant le transfert simulé gastrique-intestinal
Valorisation of Local Residues, By-Products and Wastes into Ceramic Materials for Civil Engineer Application
No full textInternational audienceNatural sand is the primary substance needed in construction field, mainly in concrete formulation, but also to make asphalt and glass. The Global Aggregates Information Network (GAIN) estimated a rise of global aggregates demand from 50 to 60 billion tonnes per annum by 2030; this increase is far from reaching its climax, considering upcoming population increase, urbanisation and economic growth [1]. Even if natural sand is generally considered as an unlimited resource, only less than 5 % (marine sand) of the quantity available on Earth reach properties requirements to be used as building materials. Moreover, overexploitation of the last few available deposits leads to several negative impacts on environment such as degradation of beaches, marine biodiversity troubles and increasing pollution due to import growth [1].Alternative materials such as industrial wastes and by-products present great potential to replace natural sand. For example, it has been proven that glass wastes [2][3] and granite wastes [4] may be used to replace sand as a degreasing agent and enhance fired bricks properties such as water absorption and shrinkage, while improving firing conditions (energy saving). The use of this alternative sands (use of waste, in most case not valorised) could reduce carbon footprint of new building constructions and avoid suffering an upcoming natural sand shortage.The purpose of this work is to experimentally evaluate the potential of six inorganic industrial residues, by-products and wastes from Occitanie region (France) to replace natural sand for the production of local building bricks. The results will allow to develop a circular economy specific to the territory’s industrial wastes. The materials involved here are domestic glass waste, wood pellet combustion ash, granite powder & mud, blast furnace slag and foundry core sand. Visual aspect, firing shrinkage, bulk density, compressive strength and leaching were studied on fired pressed clay bricks containing from 5 to 40 % of by-products.Results showed that glass, granite powder, blast furnace slag and foundry sand can be integrated to brick composition up to 20 % while maintaining satisfying properties. Mixes of glass, slag and foundry by-products also showed promising results and could allow a multi-wastes valorisation into a single brick formulation.Influence of by-products incorporation on complementary parameters such as freeze-thaw stability will have to be investigated before beginning industrial-scale tests and evaluating environmental viability of the new formulations
Localization of plastic strain in Alloy 718 using Digital Image Correlation
No full textInternational audienceHigh Resolution-Digital Image Correlation (HR-DIC) is a powerful tool to assess quantitative kinematic fields across length scales. Recently, HR-DIC was used to identify slip activity at the microstructure scale in different single- or poly-crystalline materials under tensile loading. Identification of slip systems was possible using micrographs from either scanning electron microscopes (SEM) or laser scanning confocal microscopes (LSCM). SEM micrographs provide a high spatial resolution and scanning repeatability while LSCM micrographs provide out-of-plane measurements. Both imaging techniques are therefore complementary to identify crystallographic slip activity at the sub-grain scale. In the present work, HR-DIC paired with ex-situ LSCM observations was used in order to identify strain localization and subsequently slip activity in the Alloy 718 under tensile loading at room temperature. Tensile specimens were subjected to a two-step tensile test, interrupted at 0.1% and 0.4% plastic strain. Full field inplane kinematics fields and height measurements were assessed using the DisOpticalFlow OpenCV library
Microstructure of NiTi superelastic alloy manufactured by selective laser melting
No full textInternational audienceNitinol is used in dental tools for its superelasticity, shape memory and biocompatibility. Selective laser melting(SLM) on a powder bed is a potential process for manufacturing such as dental tools. Microstructural studies areconducted on NiTi-SLM using a parallel strip strategy and 90◦ laser beam rotation. The multi-scale (nano-, micro-and mesoscopic) microstructure is revealed. Similar “cast” type microstructure features are found. The SLM meltis casted in a “micro-mold”. Fine micro-grains with random crystallographic orientation are formed near themold walls and served as seats for the rapid growth of columnar dendritic grains along the 〈0 0 1〉 direction withepitaxial crystallographic relationships. The growth of the columnar grains curves towards the center of the“micro-mold”, coinciding with the center of the laser beam. It is proposed that SLM processing resembles“Metallic Self Micro-Mold Casting” (MSμMC) and/or “Self Micro-Molding” (S2M)
