Academic literature on the topic 'Synthèse des phases MAX'
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Journal articles on the topic "Synthèse des phases MAX"
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Ferrié, Christian. "Max Adler entre Kant et Marx : une synthèse inédite." Austriaca 80, no. 1 (2015): 11–30. http://dx.doi.org/10.3406/austr.2015.5048.
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Intellectuel organique de l’aile gauche du Parti social-démocrate d’Autriche, Max Adler est un marxiste social-révolutionnaire qui s’est engagé contre la guerre et contre le réformisme. Refusant l’hégémonie de la référence hégélienne au sein du marxisme, ce membre du groupe austromarxiste propose au plan philosophique une synthèse originale et paradoxale de Marx et Kant. Avançant en effet que le point de départ apparemment individualiste dans la conscience présuppose une socialité transcendantale, Adler décèle chez Kant une pensée sociale dont les prémisses mènent au socialisme. Au plan politique, il soutient que l’idée kantienne de paix perpétuelle ne relève pas d’un idéalisme utopique du fait de la convergence entre les conceptions kantienne et marxienne de l’histoire : dépourvu de tout sens métaphysique, la causalité efficiente du processus historique engendre un but de l’histoire qui est un idéal à poursuivre consciemment.
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Low, It Meng, and Wei Kong Pang. "Thermal Stability of MAX Phases." Key Engineering Materials 617 (June 2014): 153–58. http://dx.doi.org/10.4028/www.scientific.net/kem.617.153.
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The susceptibility of MAX phases to thermal dissociation at 1300-1550 °C in high vacuum has been studied using in-situ neutron diffraction. Above 1400 °C, MAX phases decomposed to binary carbide (e.g. TiCx) or binary nitride (e.g. TiNx), primarily through the sublimation of A-elements such as Al or Si, which results in a porous surface layer of MXx being formed. Positive activation energies were determined for decomposed MAX phases with coarse pores but a negative activation energy when the pore size was less than 1.0 μm. The insights for tailor-design of MAX phases with controlled thermal stability and intercalated MXenes for energy storage are addressed.
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Zhou, Aiguo, Yi Liu, Shibo Li, et al. "From structural ceramics to 2D materials with multi-applications: A review on the development from MAX phases to MXenes." Journal of Advanced Ceramics 10, no. 6 (2021): 1194–242. http://dx.doi.org/10.1007/s40145-021-0535-5.
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AbstractMAX phases (Ti3SiC2, Ti3AlC2, V2AlC, Ti4AlN3, etc.) are layered ternary carbides/nitrides, which are generally processed and researched as structure ceramics. Selectively removing A layer from MAX phases, MXenes (Ti3C2, V2C, Mo2C, etc.) with two-dimensional (2D) structure can be prepared. The MXenes are electrically conductive and hydrophilic, which are promising as functional materials in many areas. This article reviews the milestones and the latest progress in the research of MAX phases and MXenes, from the perspective of ceramic science. Especially, this article focuses on the conversion from MAX phases to MXenes. First, we summarize the microstructure, preparation, properties, and applications of MAX phases. Among the various properties, the crack healing properties of MAX phase are highlighted. Thereafter, the critical issues on MXene research, including the preparation process, microstructure, MXene composites, and application of MXenes, are reviewed. Among the various applications, this review focuses on two selected applications: energy storage and electromagnetic interference shielding. Moreover, new research directions and future trends on MAX phases and MXenes are also discussed.
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IVANENKO, K. O., та A. M. FAINLEIB. "МАХ PHASE (MXENE) IN POLYMER MATERIALS". Polymer journal 44, № 3 (2022): 165–81. http://dx.doi.org/10.15407/polymerj.44.03.165.
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This article is a review of the Mn+1AXn phases (“MAX phases”, where n = 1, 2 or 3), their MXene derivatives and the reinforcement of polymers with these materials. The MAX phases are a class of hexagonal-structure ternary carbides and nitrides ("X") of the transition metal ("M") and the A-group element. The unique combination of chemical, physical, electrical and mechanical properties that combine the characteristics of metals and ceramics is of interest to researchers in the MAX phases. For example, MAX phases are typically resistant to oxidation and corrosion, elastic, but at the same time, they have high thermal and electrical conductivity and are machinable. These properties stem from an inherently nanolaminated crystal structure, with Mn+1Xn slabs intercalated with pure A-element layers. To date, more than 150 MAX phases have been synthesized. In 2011, a new family of 2D materials, called MXene, was synthesized, emphasizing the connection with the MAX phases and their dimension. Several approaches to the synthesis of MXene have been developed, including selective etching in a mixture of fluoride salts and various acids, non-aqueous etching solutions, halogens and molten salts, which allows the synthesis of new materials with better control over the chemical composition of their surface. The use of MAX phases and MXene for polymer reinforcement increases their thermal, electrical and mechanical properties. Thus, the addition of fillers increases the glass transition temperature by an average of 10%, bending strength by 30%, compressive strength by 70%, tensile strength up to 200%, microhardness by 40%, reduces friction coefficient and makes the composite material self-lubricating, and 1 % wt. MAX phases increases thermal conductivity by 23%, Young’s modulus increases. The use of composites as components of sensors, electromagnetic protection, wearable technologies, in current sources, in aerospace and military applications, etc. are proposed.
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Crasemann, B. "Review/Synthèse Synchrotron radiation in atomic physics." Canadian Journal of Physics 76, no. 4 (1998): 251–72. http://dx.doi.org/10.1139/p98-013.
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Much of present understanding of atomic and molecular structure and dynamicswas gained through studies of photon--atom interactions. In particular,observations of the emission, absorption, and scattering of X rays havecomplemented particle-collision experiments in elucidating the physics ofatomic inner shells. Grounded on Max von Laue's theoretical insight andthe invention of the Bragg spectrometer, the field's potential underwent astep function with the development of synchrotron-radiation sources. Notablycurrent third-generation sources have opened new horizons in atomicand molecular physics by producing radiation of wide tunability andexceedingly high intensity and polarization, narrow energy bandwidth, andsharp time structure. In this review, recent advances insynchrotron-radiation studies in atomic and molecular science are outlined.Some tempting opportunities are surveyed that arise for future studiesof atomic processes, including many-body effects, aspects offundamental photon--atominteractions, and relativistic and quantum-electrodynamic phenomena.PACS Nos.: 32.20J, 32.20R, and 07.65E
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Vassogne, Gaëlle. "La notion de Heimat chez Max Brod." Chroniques allemandes 13, no. 1 (2009): 257–64. http://dx.doi.org/10.3406/chral.2009.932.
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Placés entre deux groupes nationaux, les Juifs pragois se trouvent, au début du XXe siècle, face à la nécessité de redéfinir leur Heimat. Le sionisme pragois, dont Brod est l’un des principaux représentants, constitue une réponse à cette nécessité. Puisque la patrie allemande le rejette, Brod choisit de se tourner vers la terre des pères, Eretz Israël, Heimat mythique qui n’offre aucune solution concrète. Brod reste en effet à Prague jusqu’en 1939 et adopte la nationalité juive mais il continue à écrire en allemand, se définissant comme « écrivain juif de langue allemande ». Le parcours de Max Brod apparaît comme une tentative pour concilier une identité juive, des racines culturelles allemandes et populaires tchèques dans une Heimat spirituelle, personnelle, qui en constituerait une synthèse idéale.
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Zhang, Qiqiang, Yanchun Zhou, Xingyuan San, et al. "Zr2SeB and Hf2SeB: Two new MAB phase compounds with the Cr2AlC-type MAX phase (211 phase) crystal structures." Journal of Advanced Ceramics 11, no. 11 (2022): 1764–76. http://dx.doi.org/10.1007/s40145-022-0646-7.
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AbstractThe ternary or quaternary layered compounds called MAB phases are frequently mentioned recently together with the well-known MAX phases. However, MAB phases are generally referred to layered transition metal borides, while MAX phases are layered transition metal carbides and nitrides with different types of crystal structure although they share the common nano-laminated structure characteristics. In order to prove that MAB phases can share the same type of crystal structure with MAX phases and extend the composition window of MAX phases from carbides and nitrides to borides, two new MAB phase compounds Zr2SeB and Hf2SeB with the Cr2AlC-type MAX phase (211 phase) crystal structure were discovered by a combination of first-principles calculations and experimental verification in this work. First-principles calculations predicted the stability and lattice parameters of the two new MAB phase compounds Zr2SeB and Hf2SeB. Then they were successfully synthesized by using a thermal explosion method in a spark plasma sintering (SPS) furnace. The crystal structures of Zr2SeB and Hf2SeB were determined by a combination of the X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The lattice parameters of Zr2SeB and Hf2SeB are a = 3.64398 Å, c = 12.63223 Å and a = 3.52280 Å, c = 12.47804 Å, respectively. And the atomic positions are M at 4f (1/3, 2/3, 0.60288 [Zr] or 0.59889 [Hf]), Se at 2c (1/3, 2/3, 1/4), and B at 2a (0, 0, 0). And the atomic stacking sequences follow those of the Cr2AlC-type MAX phases. This work opens up the composition window for the MAB phases and MAX phases and will trigger the interests of material scientists and physicists to explore new compounds and properties in this new family of materials.
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Hu, Chunfeng, Haibin Zhang, Fangzhi Li, Qing Huang, and Yiwang Bao. "New phases’ discovery in MAX family." International Journal of Refractory Metals and Hard Materials 36 (January 2013): 300–312. http://dx.doi.org/10.1016/j.ijrmhm.2012.10.011.
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Zhou, Ai Guo, and M. W. Barsoum. "Nonlinear Elastic Deformation of MAX Phases." Key Engineering Materials 434-435 (March 2010): 149–53. http://dx.doi.org/10.4028/www.scientific.net/kem.434-435.149.
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MAX phases, include Ti3SiC2, Ti2AlC etc, are machinable ternary carbides or nitrides with excellent properties. These materials, however, have obvious nonlinear elastic deformation due to nano- layered crystal structure. The stress-strain curves of cyclically load-unload test have obvious hysteretic loops. Because of this mechanical hysteresis, the strain of MAX phases at one time is not determined only by the stress applied to the sample at this time. Here the influence of grain size, chemical composition and porosity on the nonlinear elastic strain was introduced. Because of two properties of this hysteresis: wiping out and congruency, the classic hysteretic mathematic model (Preisach-Mayergoyz model, P-M model) can be applied to calculate the strain of MAX phases after any complex deformation history.
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Jürgens, D., M. Uhrmacher, H. Hofsäss, et al. "First PAC experiments in MAX-phases." Hyperfine Interactions 178, no. 1-3 (2007): 23–30. http://dx.doi.org/10.1007/s10751-008-9651-7.
Full textDissertations / Theses on the topic "Synthèse des phases MAX"
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Magné, Damien. "Synthèse et structure électronique de phases MAX et MXènes." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2284/document.
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Les objectifs de ce travail sont d'une part d'étudier la structure électronique de carbures de titane bidimensionnels appartenant à la famille des MXènes, et d'autre part de synthétiser des films minces pour caractériser certaines de leurs propriétés. L'étude de la structure électronique a été réalisée sur le système Ti3C2T2 avec une attention particulière portée aux groupements de surface T (T=OH, F ou O) en comparant les résultats obtenus par spectroscopie de perte d'énergie des électrons à ceux des calculs ab initio. Cette étude, portée à la fois sur les excitations du gaz d'électrons de valence et des électrons de coeur, a permis de mettre en évidence la localisation des groupements de surface, ainsi que leur influence sur la structure électronique du MXene. La comparaison des simulations et des spectres expérimentaux a également permis de caractériser la nature chimique des groupements de surface. Enfin, la limite d'une telle étude est discutée en considérant les phénomènes d'irradiation responsables de la perte d'atomes d'hydrogène. La synthèse d'échantillons modèles nécessite la synthèse préalable d'un film mince de phase MAX précurseur pour le MXene : nous avons choisi la phase Ti2AlC, précurseur de Ti2C. La synthèse de Ti2AlC a été réalisée par recuit ex-situ de systèmes multicouches déposés à température ambiante. Les films ont été caractérisés par diffraction des rayons X et microscopie électronique en transmission. Au-delà de l'obtention d'un film mince de Ti2AlC texturé, cette étude a permis de montrer que la phase recherchée était obtenue via des mécanismes d'interdiffusions induisant la formation d'une solution solide métastable vers 400°C qui se transforme en phase MAX vers 600°C. Enfin, l'application de ce procédé à la phase V2AlC a permis de montrer l'importance de l'orientation de la phase initiale pour l'obtention d'un film mince texturé<br>The aim of this work is at first to study the electronic structure of bidimensional titanium carbide systems, belonging to the MXene family and also to synthesize thin films of such new materials to characterize their properties. The study of the electronic structure has been performed for the Ti3C2T2 MXene with a special attention to the T surface groups by using a combination of electron energy loss spectroscopy and ab initio calculations. This study, focused on both valence and core electrons excitations, enabled the identification of the surface group localization, their influence on the MXene electronic structure as well as their chemical nature. The limits of our TEM-based study is also discussed in view of irradiation phenomena which induce the loss of hydrogen atoms. The synthesis of a MXene thin film requires, beforehand, that of a MAX phase thin film: we opted for Ti2AlC, the precursor for the Ti2C MXene. The MAX phase thin film synthesis was carried out by ex-situ annealing of a multilayer layers. X-ray diffraction experiments and cross-sectional transmission electron microscopy observations show that a highly textured Ti2AlC thin film is obtained above 600°C after the formation, at 400°C, of a metastable solid solution. Finally, by using the same process for V2AlC, we demonstrate that the initial phase orientation plays a key role for the texture of the thin film so obtained
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Shi, Lu. "Des phases MAX au MXenes : synthèse,caractérisation et propriétés électroniques." Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAI101/document.
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Les phases MAX sont des carbures ou des nitrures ternaires nano-lamellaires comportant un métal de transition (M), un élément des colonnes 13-16 (A), X=C ou N.Ces phases combinent certaines des meilleures propriétés des céramiques à celles des métaux. Leurs propriétés physiques (rigidité, résistance aux chocs mécaniques et thermiques, bonnes conductivités thermique et électrique), associées à la possibilité d’usinage, les rend très attractives en termes d’applications technologiques potentielles.En 2011, il a été établi qu’un traitement à l’acide fluorhydrique (HF) des phases MAX comprenant de l’aluminium permet une élimination sélective des plans d’atomes Al, avec pour résultat la formation de matériaux bi-dimensionnels (2D) appelés MXènes pour souligner la perte des atomes de Al. Ces nouveaux membres de la famille des matériaux 2D sont plus résistants, chimiquement plus polyvalents et possèdent une conductivité supérieure à nombre d’autres matériaux. Ils se révèlent par conséquent très intéressants pour de nouvelles applications, par exemple pour des systèmes de délivrance de médicaments in vivo, le stockage d’hydrogène, ou pour remplacer d’autres matériaux dans des batteries, le traitement des eaux usées ou divers capteurs.Dans cette thèse, nous présentons notre travail sur la synthèse, la caractérisation structurale et le transport électronique dans les phases MAX et leurs dérivés 2D, les MXènes. En ce qui concerne les phases MAX, et motivés par les propriétés fortement anisotropes attendues de tels matériaux nano-lamellaires, produire des monocristaux massifs est le moyen le plus naturel d’obtenir des échantillons où l’anisotropie des propriétés physiques peut être sondée expérimentalement. En utilisant avec succès la méthode de croissance en solution à haute température associée à un refroidissement lent, nous avons obtenu des monocristaux de divereses phases MAX, incluant Cr2AlC, V2AlC, Ti3SiC2, etc.La caractérisation structurale confirme le caractère mono-cristallin des échantillons. Expérimentalement, nous avons acquis un jeu exhaustif de mesures de magnéto-transport de monocristaux en fonction de la température et du champ magnétique. De plus, nous obtenons un rapport d’anisotropie très important entre la résistivité dans le plan ab et celle parallèle à l’axe c, allant de plusieurs centaines à plusieurs milliers. A partir des courbes de magnétorésistance et d’effet Hall, nous avons étudié en détail le comportement du transport dans le plan basal. D’un point de vue théorique, nous avons proposé un modèle général mais simple pour décrire les propriétés de magnéto-transport d’électrons presque libres dans des métaux 2D hexagonaux. Ce modèle a été modifié pour être appliqué aux propriétés de transport des phases MAX nano-lamellaires.En ce qui concerne les MXènes, nous avons synthétisé avec succès des écailles de MXènes V2CTx de grande surface à partir du traitement HF conventionnel de monocristaux de V2AlC. La délamination mécanique de ces écailles multi-couches de V2CTx en échantillons comportant peu de monocouches a aussi été réalisée. Nous avons établi la morphologie typique de ces couches à partir d’images de microscopies MEB ou TEM. A partir d’analyse EDX, nous concluons que les terminaisons -OH dominent et sont les plus stables énergétiquement. Nous détaillons ensuite le procédé de fabrication des dispositifs électriques utilisés pour obtenir les résultats de mesures de transport électrique jusqu’à basse température. Nous avons obtenu avec succès des résultats originaux sur les MXènes V2CTx, avec une valeur moyenne de résistivité de l’ordre de 2 × 10-5 ohmm. La mesure d’effet de champ indique une mobilité de 22.7 cm2/Vs. Du fait de l’intensité des recherches portées actuellement sur les MXènes, nous espérons que ces résultats contribueront de manière significative à une meilleure compréhension de cette classe de matériaux et de la façon dont leurs propriétés peuvent être contrôlées<br>MAX phases are layered early transition metal ternary carbides and nitrides so called because they are composed of M, an early transition metal, A, a group A element and X is C and/or N. MAX phase structure is composed of near close-packed planes of M atoms with the X atoms occupying all the octahedral sites between them. Their physical properties (stiffness, damage and thermal shock resistance, high thermal and electrical conductivity) along with the fact they are readily machinable, make them extremely attractive in terms of the potential technological applications.In 2011, it was discovered that by immersing Al-containing MAX phases in HF acid, it was possible to selectively etch the Al, resulting in two-dimensional (2D) materials, that were labeled MXene to denote the removal of the A-group element and make the connection to another conducting 2D material, graphene. This new member of 2D materials family owns stronger, more chemically versatile, and have higher conductivity than other materials. As such they are highly interesting on new applications, e.g. specialized in vivo drug delivery systems, hydrogen storage, or as replacements of common materials in e.g. batteries, sewage treatment, and sensors.In this thesis, as its self-telling title indicated, we present our work on the synthesis, structural characterization and the electron transport in the MAX phases and their 2D derivatives, MXenes.For MAX phase: motivated by the theoretically expected anisotropic properties of these layered materials, producing bulk single crystals is a natural way to obtain samples where the anisotropy of the physical properties can be experimentally probed. Also, knowledge of low-temperature behavior of single crystal is vital because it can provide insight into MAX intrinsic physical properties. Using high temperature solution growth and slow cooling technique, several MAX phases single crystals have been successfully grown, including Cr2AlC, V2AlC, Ti3SiC2, etc. Structural characterization confirms the single crystalline character of the samples. Experimentally, a set of experimental data was obtained from single crystals of V2AlC and Cr2AlC as a function of temperature and magnetic field. In particular, we obtain a very high ratio between the in-plane and parallel to the c-axis resistivity, which is very substantial, in the range of a few hundreds to thousands. From MR and Hall effect measurement, in-plane transport behaviors of MAX phases have been studied. The extracted mobility is in the range from 50 to 120 cm2/V·s, which is the same order of magnitude of polycrystalline sample. Theoretically, a general, yet simple model was proposed for describing the weak field magneto-transport properties of nearly free electrons in two-dimensional hexagonal metals. It was then modified to be applicable for the transport properties of layered MAX phases.For MXene: Large scale V2CTx MXene flakes was successfully synthesized by conventional HF-etching of V2AlC single crystals. Mechanical delamination of multilayered V2CTx flakes into few layer flakes and transfer on Si/SiO2 substrate was also achieved. Structural characterization demonstrated an enlarged interplane distance, while prior DMSO intercalation seems to have no effect on this type of MXenes. From EDS results, we concluded that -OH terminations on V2CTx is the dominated, and the most energetically favorable, compared to -F and -O functional groups. We then detail the electrical device fabrication process and proceed with electrical measurements results, performed down to low temperature, with the aim to extract useful information on charge carrier behavior. We successfully obtained some first hand transport data on V2CTx MXenes, the average value for the resistivity of V2CTx MXenes is 2 × 10-5 Ω ∙m, which is in consistent with reported other MXene samples. The mobility, 22.7 cm2/V·s , which stays in the same order of magnitude as its parent MAX phase
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Zhang, Shiqi. "Etude de la Réactivité chimique des monocristaux de phase MAX." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI042/document.
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Les phases MAX forment une famille de carbures et de nitrures nano-lamellaires de formule chimique Mn+1AXn, où M est un métal de transition des premières colonnes, A appartient aux colonnes 13-16 et X est soit C, soit N, ou une combinaison des deux éléments. Ces phases combinent les mérites des céramiques et des métaux, comme une bonne stabilité chimique, l’usinabilité, la résistance aux chocs mécaniques, de bonnes conductivités thermique et électrique, etc. Malgré tout, l’étude de leurs propriétés intrinsèques et de leurs anisotropies a été jusqu’à présent limitée par l’indisponibilité de monocristaux. Cette thèse traite de la réactivité de tels monocristaux de phases MAX. Grâce à la large taille des cristaux produits au LMGP, il a été possible d’évaluer directement l’anisotropie de la réactivité chimique et d’obtenir des données originales. Nous avons montré le rôle prépondérant joué par l’élément A pour initier des transformations chimiques menant parfois à la synthèse de matériaux originaux, et nous nous sommes concentrés sur quatre aspects différents : Tout d’abord, nous avons tenté de synthétiser des MXènes de grande taille, en profitant de la grande taille des cristaux disponibles. Un effort particulier a été porté sur la description de la réactivité chimique de phases MAX plongées dans diverses solutions d’attaque, avec un accent particulier mis sur l’utilisation de HF. En second lieu, nous avons étudié la chloruration de phases MAX : l’objectif initial était de former des MXènes, mais nous avons finalement développé une méthode pour synthétiser des carbures de chrome poreux avec des propriétés intéressantes. Troisièmement, nous avons utilisé des cristaux de grande taille pour évaluer l’anisotropie des propriétés électrochimiques. Une anisotropie significative a été trouvée, soit en mesurant le courant durant la polarisation électrochimique, soit par mesure de spectroscopie d’impédance. Divers mécanismes ont été proposés afin d’expliquer cette anisotropie des propriétés de corrosion. Enfin, nous avons montré que les résultats électrochimiques pouvaient être utilisés pour révéler indirectement la présence de défauts structurels récemment identifiés dans la littérature. De tels défauts, appelés « ripplocations », sont spécifiques aux matériaux nano-lamellaires<br>MAX phases are a family of layered ternary carbides and nitrides with chemical formula Mn+1AXn, where M is an early transition element, A is an element of groups 13 to16 and X is either C, N or both. These phases combine the merits of ceramics and metals, such as chemical stability, machinability, shock resistance, good electrical and thermal conductivity, etc. However, the investigation of their intrinsic properties and anisotropies has heretofore been limited by a lack of availability of single crystals. This thesis mainly deals with the chemical reactivity of MAX phase single crystals. Owing to the large size single crystals grown at LMGP, it was possible to directly assess the anisotropy of the chemical reactivity and to obtain original data. We showed that the prominent role played by the A element for initiating chemical transformations could lead to the synthesis of original materials, and we focused on four different aspects. First, we tried to synthesize MXenes from MAX phase single crystals: The purpose was to obtain large-scale MXenes by taking advantage of the large size of the single crystals. Effort was put on describing the chemical reactivity of MAX phases dipped in different etchants, focusing on HF. Secondly, we studied the MAX phase reactivity with chlorination: the initial purpose was to obtain MXenes, but we finally developed a method for synthesizing porous chromium carbides which exhibit several interesting properties. Thirdly, we used large size single crystals in order to assess the anisotropy of the electrochemical properties. A significant anisotropy was found, either by measuring the current during electrochemical polarization or by frequency-dependent impedance measurements. Several mechanisms were proposed in order to explain this anisotropy of the corrosion properties. Eventually, we showed that the electrochemical results could be used to indirectly evidence the presence of structural defects recently identified in the literature. Such defects, called ripplocations, are specific to nano-lamellar materials
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Bugnet, Matthieu. "Synthèse, structure électronique et comportement sous irradiation aux ions de films minces de phases MAX." Poitiers, 2011. http://theses.univ-poitiers.fr/23902/2011-Bugnet-Matthieu-These.pdf.
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L'objectif de ce travail est de réaliser la synthèse de matériaux modèles (films minces épitaxiés) de céramiques ternaires, les phases MAX, afin d'étudier leur comportement sous irradiation aux ions. Les modifications micro-structurales induites par l'irradiation ont été suivies à l'aide des spectroscopies de perte d'énergie des électrons et d'absorption X en complément de la diffraction des rayons X et de la microscopie électronique en transmission. La croissance de films minces épitaxiés de Cr2AlC et de Cr2GeC a été obtenue par pulvérisation magnétron tandis que la synthèse de couches texturées de Ti2AlN a été réalisée par nitruration plasma à haute température de multicouches de stœchiométrie Ti2:Al1:N1. Nous avons ensuite caractérisé la structure électronique avant irradiation de Cr2AlC, Cr2GeC, Ti2AlC, Ti3AlC2 et Ti2AlN en interprétant, à partir de calculs ab initio, les résultats obtenus par des techniques spectroscopiques. Cette étude montre que des informations d'ordre structural sont essentiellement obtenues grâce à l'interprétation des structures fines des seuils d'excitation d'électrons de cœur. Après irradiation, l'étude fine des seuil C-K et Al-K de Ti3AlC2 met en évidence que les couches d'octaèdres Ti6C sont très résistantes à l'endommagement alors que les couches d'atomes d'aluminium sont fortement perturbées. Un comportement similaire est suggéré pour Ti2AlC, Ti2AlN et en partie pour Cr2AlC. Tandis que les composés à base titane restent cristallins après irradiation à haute fluence, une amorphisation est rapidement observée pour les composés à base chrome. Une restauration de la structure initiale lors d'un recuit post-irradiation est mise en évidence<br>The aim of this work is to synthesize model materials (epitaxial thin films) of ternary ceramics called MAX phases, in order to study their behavior under ion irradiation. To follow the microstructural modifications induced by ion irradiation, we used electron energy loss spectroscopy and X-ray absorption spectroscopy in addition to X-ray diffraction and transmission electron microscopy techniques. The growth of Cr2AlC and Cr2GeC epitaxial thin films was achieved by magnetron sputtering whereas the synthesis of textured Ti2AlN layers was obtained by high temperature plasma nitriding of multilayers with an average stœchiometry Ti2:Al1:N1. The electronic structure of unirradiated films of de Cr2AlC, Cr2GeC, Ti2AlC, Ti3AlC2 and Ti2AlN was then characterized. Experimental spectra were interpreted from ab initio simulations. This study shows that structural information may be obtained from fine structures of core electron excitation edges. After irradiation, the study of the C-K and Al-K near-edge fine structures in Ti3AIC2 evidences that Ti6C octahedra layers are very resistant to irradiation damage and on the contrary, aluminium layers are strongly disordered. A similar behavior is suggested for Ti2AlC, Ti2AlN and also partly for Cr2AlC. Though titanium based materials are still crystalline after irradiation at high fluence, chronium based compounds rapidly amorphize. It is evidenced that the initial crystalline structure is recovered after post-irradiation annealing
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Alkazaz, Malaz. "Synthèse de films minces de phases MAX par recuit thermique - Application à la formation de contacts ohmiques sur SiC." Thesis, Poitiers, 2014. http://www.theses.fr/2014POIT2328/document.
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Les phases MAX sont des carbures ou nitrures ternaires dont les propriétés sont généralement décrites comme la combinaison exceptionnelle des meilleures propriétés des métaux et des céramiques. Sous forme de couches minces, ces matériaux sont prometteurs en tant que contact ohmique sur des substrats de SiC pour la microélectronique de puissance. Des approches originales dédiées à l'obtention de films minces épitaxiés des phases MAX Ti2AlN, Ti3SiC2 et Ti3(Si,Ge)C2 sont développées dans ce travail. Des recuits à 750°C de systèmes multicouches (Ti+Al)/AlN permettent ainsi de former des couches de Ti2AlN fortement texturées sur des substrats de SiC ou Al2O3. La seconde approche consiste à recuire à 1000°C des couches de TixAly ou TixGey, déposés sur 4H-SiC, pour obtenir des films minces épitaxiés de Ti3SiC2 et Ti3(Si,Ge)C2. Ces derniers présentent les caractéristiques d'un contact ohmique sur SiC<br>MAX phases are a family of ternary carbides or nitrides which properties are generally described as an exceptional combination of the best properties of metals and ceramics. Thin films of MAX phases being considered as good candidates for ohmic contacts on SiC substrates for power microelectronics devices, thin films of Ti2AlN and Ti3(Si,Ge)C2 were synthesized by using original approaches. Highly textured Ti2AlN thin films were so obtained by thermal annealing at 750°C of (Ti+Al)/AlN multilayers whereas epitaxial thin films of Ti3SiC2 on 4H-SiC were achieved after an annealing at 1000°C of TixAly or TixGey layers. Good ohmic contact behaviors of Ti3SiC2 layers were confirmed in this work whereas Ti2AlN thin films behave as Schottky barriers
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Khan, Abbas. "Tailored oxides and carbides as active materials for high power energy storage devices." Electronic Thesis or Diss., Nantes Université, 2024. http://www.theses.fr/2024NANU4025.
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La conception de matériaux sur mesure utilisant des approches innovantes permettant des processus de charge/décharge plus rapides pourrait être la clé pour l'avancement de la mobilité électrique. Cette thèse examine des matériaux novateurs pour les électrodes négatives de batteries Li-ion, en se concentrant sur les oxydes multicationiques à base de niobium et les carbures de métaux de transition à base de titane. Les travaux de recherche explorent la synthèse, la structure et les propriétés électrochimiques de ces matériaux, avec une attention particulière aux modifications structurales et aux mécanismes de stockage des charges. Les principaux résultats incluent l'étude de l'activation électrochimique in-situ des matériaux et du comportement unique de stockage du Li+ dans les matériaux pérovskite AgNbO 3 et Ag1-3xLa x□2xNbO 3 (avec 0 ≤ x ≤ 0,40 ; □ étant une lacune sur le site A).De plus, cette étude examine l'effet des lacunes du site A sur la structure et sur les propriétés d'insertion du Li+ dans les structures K1- 3xLa x□2xNbO 3 (avec 0 ≤ x ≤ 0,15 ; □ étant une lacune sur le site A). En outre, des informations sur la voie de synthèse polyacrylamide pour les phases MAX à base de Ti et Al sont fournies. Ce travail présente des approches pour ajuster les matériaux de manière à l’échelle atomique, sans sacrifier la phase initiale, suggérant l'utilisation potentielle de pérovskites de type ABO 3 peu étudiées comme électrodes négatives. De plus, il offre des perspectives mécanistiques sur la synthèse chimique en solution des phases MAX pour leur utilisation comme électrodes de batterie lithium-ion<br>Design of tailored materials using innovative approaches that allow faster charging/discharging processes could be the key for advancement of electric mobility. This thesis investigates novel materials for Li-ion battery negative electrodes, focusing on niobium-based multicationic oxides and titanium-based transition metal carbides. This research work explores the synthesis, structure, and electrochemical properties of these materials, with particular emphasis on atomic-scale structural modifications and Li+ storage mechanisms. Key findings include the investigation of in-situ electrochemical activation and unique Li+ storage behavior in AgNbO 3 model perovskite and Ag 1-3xLa x□2xNbO 3 (with 0 ≤ x ≤ 0.40; □ is an A -site vacancy) tailored materials. Additionally, the study examines the effect of A-site deficiency on the structure and Li+ insertion properties of K1-3xLa x□2xNbO 3 (with 0 ≤ x ≤ 0.15; □ is an A -site vacancy). Furthermore, insights into the polyacrylamide synthesis route for Ti and Al-based MAX phases are provided. These work present approaches to atomically tailor the materials without sacrificing the pristine phase, suggesting the potential use of less common ABO 3-type perovskites as negative electrodes. Additionally, it offers mechanistic insights into the wet chemical synthesis of MAX phases for their use as battery electrodes
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Humphrey, Caroline. "Deformation in MAX phases." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610553.
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Liu, Zhongsheng. "Magnetic MAX phases: Itinerant electron magnetism of pure and Mn-doped Cr-based MAX phases." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199312.
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Bououdina, Mohamed. "Étude d'alliages et d'hydrures dérivés des phases de laves ZrCr2(1-x)M2x (M=éléments 3d et molybdène) : Synthèse, études structurale et thermodynamique en relation avec les propriétés de stockage de l'hydrogène." Grenoble 1, 1995. http://www.theses.fr/1995GRE10056.
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Preparation des alliages par induction dans un four hf. Stabilisation des phases par traitements thermiques. Hydrogenation par synthese solide-gaz sous pression. Caracterisation structurale par diffraction aux rayons-x et aux neutrons. Etude des diagrammes p-c-t (pression, composition et temperature). Pour ce faire, un nouveau systeme de controle et de regulation du systeme d'analyse thermogravimetrique completement automatise et assiste par ordinateur a ete mis au point. Modelisation: calcul de la chaleur de formation des solutions solides a partir d'un modele theorique adapte a nos systemes. Ceci nous a permis de discuter la stabilite des phases des alliages et la stabilite des hydrures
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Gupta, Surojit Barsoum M. W. "Tribology of MAX phases and their composites /." Philadelphia, Pa. : Drexel University, 2006. http://dspace.library.drexel.edu/handle/1860%20/875.
Full textBooks on the topic "Synthèse des phases MAX"
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Barsoum, Michel W. MAX Phases. Wiley-VCH Verlag GmbH & Co. KGaA, 2013. http://dx.doi.org/10.1002/9783527654581.
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Low, It-Meng. MAX phases: Microstructure, properties, and applications. Nova Science Publishers, 2011.
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Fisher, David. Mechanical Properties of MAX Phases. Materials Research Forum LLC, 2021. http://dx.doi.org/10.21741/9781644901274.
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MAX Phase Materials are uniquely structured carbide and nitride materials which combine the rigidity, oxidation-resistance and high-temperature strength of ceramic materials with such metallic properties as good machinability, thermal-shock resistance, damage-tolerance and good transport properties. Potential applications include microelectronic layers, coatings for electrical contacts, thermal shock-resistant refractories, high-temperature heating elements, neutron-irradiation resistant nuclear applications, thermal barriers, protective aerospace coatings, and bio-compatible materials. The book reviews theoretical and experimental research up to early 2021 and references 185 original resources with their direct web links for in-depth reading.
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Barsoum, Michel W. MAX Phases: Properties of Machinable Ternary Carbides and Nitrides. Wiley & Sons, Limited, John, 2013.
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Barsoum, Michel W. MAX Phases: Properties of Machinable Ternary Carbides and Nitrides. Wiley & Sons, Incorporated, John, 2013.
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Barsoum, Michel W. MAX Phases: Properties of Machinable Ternary Carbides and Nitrides. Wiley & Sons, Incorporated, John, 2013.
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Barsoum, Michel W. MAX Phases: Properties of Machinable Ternary Carbides and Nitrides. Wiley & Sons, Incorporated, John, 2013.
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MAX Phases: Properties of Machinable Ternary Carbides and Nitrides. Wiley-VCH Verlag GmbH, 2013.
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MAX phases and ultra-high temperature ceramics for extreme environments. Engineering Science Reference, an imprint of IGI Global, 2013.
Find full textBook chapters on the topic "Synthèse des phases MAX"
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Jürgens, D., M. Uhrmacher, H. Hofsäss, et al. "First PAC experiments in MAX-phases." In HFI/NQI 2007. Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-85320-6_41.
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Ahuja, Rajeev. "Nanolayered MAX Phases from Ab Initio Calculations." In Particle and Continuum Aspects of Mesomechanics. ISTE, 2010. http://dx.doi.org/10.1002/9780470610794.ch19.
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Naik Parrikar, Prathmesh, Rogelio Benitez, Miladin Radovic, and Arun Shukla. "Effect of Microstructure on Mechanical Response of MAX Phases." In Conference Proceedings of the Society for Experimental Mechanics Series. Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-41766-0_20.
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Lee, William E., Edoardo Giorgi, Robert Harrison, Alexandre Maître, and Olivier Rapaud. "Nuclear Applications for Ultra-High Temperature Ceramics and MAX Phases." In Ultra-High Temperature Ceramics. John Wiley & Sons, Inc, 2014. http://dx.doi.org/10.1002/9781118700853.ch15.
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Ching, Wai-Yim. "Materials Informatics Using Ab initio Data: Application to MAX Phases." In Information Science for Materials Discovery and Design. Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-23871-5_10.
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Low, I. M., W. K. Pang, S. J. Kennedy, and R. I. Smith. "Study of High-Temperature Thermal Stability of Max Phases in Vacuum." In Strategic Materials and Computational Design. John Wiley & Sons, Inc., 2010. http://dx.doi.org/10.1002/9780470944103.ch17.
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Low, I. M., and W. K. Pang. "A Comparative Study of Decomposition Kinetics in Max Phases at Elevated Temperature." In Advanced Ceramic Coatings and Materials for Extreme Environments II. John Wiley & Sons, Inc., 2012. http://dx.doi.org/10.1002/9781118217474.ch15.
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Rosen, Johanna, Martin Dahlqvist, Quanzheng Tao, and Lars Hultman. "In- and Out-of-Plane Ordered MAX Phases and Their MXene Derivatives." In 2D Metal Carbides and Nitrides (MXenes). Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-19026-2_3.
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Munagala, Sai Priya. "MAX Phases: New Class of Carbides and Nitrides for Aerospace Structural Applications." In Aerospace Materials and Material Technologies. Springer Singapore, 2016. http://dx.doi.org/10.1007/978-981-10-2134-3_20.
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Lanos, Philippe, Jérémy Maestracci, and Luc Sanson. "La gestion des différentes méthodes de datation dans le cas des inhumations de Villenauxe-la-Grande (Aube, 10). L’apport des statistiques bayésiennes et du logiciel ChronoModel." In Rencontre autour des typo-chronologies des tombes à inhumation. Fédération pour l’édition de la Revue archéologique du Centre de la France, 2022. http://dx.doi.org/10.4000/12pha.
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Une partie de la nécropole de Villenauxe-la-Grande (10, Aube) a révélé, en 2014, une cinquantaine de sépultures. Ces tombes appartiennent à deux phases chronologiques distinctes : l’Antiquité tardive et le haut Moyen Âge. L’enjeu de ce travail est de synthétiser les résultats des différentes datations obtenues pourchaque inhumé. Ces dates proviennent de la typologie du mobilier, des analyses radiocarbone, des monnaies et des relations stratigraphiques. La synthèse de toutes ces méthodes de datations a pu être menée via l’utilisation des statistiques bayésiennes et du logiciel ChronoModel. Les intervalles restitués permettent d’obtenir une grande finesse dans les datations et ainsi d’aborder la dynamique d’occupation de la nécropole. La méthode rend possible le dialogue entre les différents intervenants qui travaillent sur les datations.
Conference papers on the topic "Synthèse des phases MAX"
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LUO, W., C. M. FANG, and R. AHUJA. "NANOLAYERED MAX PHASES FROM ab initio CALCULATIONS." In Proceedings of the 31st International Workshop. WORLD SCIENTIFIC, 2008. http://dx.doi.org/10.1142/9789812836625_0021.
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Trache, R., R. Puschmann, C. Leyens, L. M. Berger, B. Matthey, and M. Herrmann. "Thermally Sprayed Ti3SiC2 and Ti2AlC MAX-Phase Coatings." In ITSC2013, edited by R. S. Lima, A. Agarwal, M. M. Hyland, et al. ASM International, 2013. http://dx.doi.org/10.31399/asm.cp.itsc2013p0074.
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Abstract Compounds of the material group known as MAX phases combine metallic and ceramic properties. In this work, MAX-phase coatings are deposited from modified Ti3SiC2 and Ti2AlC commercial feedstock powders using HVOF and atmospheric plasma spraying (APS). Feedstock powders and coatings were studied by microscopy and XRD. Despite the use of unoptimized powders, well adhering and relatively dense coatings were produced. HVOF-sprayed layers had denser microstructures with higher amounts of MAX phases. Optimizing the shape and particle-size distribution of feedstock materials is expected to improve coating properties.
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Burlachenko, Oleksii, and Tetiana Tsymbalista. "Powders produced by the method of mechanochemical synthesis for thermal spraying of coatings containing MAX phases." In IXth INTERNATIONAL SAMSONOV CONFERENCE “MATERIALS SCIENCE OF REFRACTORY COMPOUNDS”. Frantsevich Ukrainian Materials Research Society, 2024. http://dx.doi.org/10.62564/m4-ob1530.
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To produce protective coatings containing MAX phases, methods of thin films deposition such as physical vapour deposition and magnetron sputtering are mainly used [1]. Such coatings are only a few microns thick and do not meet the requirements for operation in extreme conditions. Thermal spraying (TS) makes it possible to form coatings several millimetres thick. This work is dedicated to developing compositions and technology of producing powders using commercially available starting materials for thermal spraying of coatings containing MAX phases. The technology of mechanochemical synthesis (MChS) by processing mixtures of powders of the compositions 60.9TiC+39.1TiAl, 75TiAl-25SiC, 68.5(Ti,Cr)C-31.5Al, 82Cr3C2-18Al (wt.%) in a high-energy planetary ball mill was used to produce powders for TS. The compositions were calculated to form the most promising MAX phases: Ti3SiC2, Ti2AlC, Ti3AlC2 and Cr2AlC. The MChS process was performed in air during 1.5 hours. The produced powders products of MChS have a conglomerate structure with particles size <50 μm. In the powder product of MChS of the TiAl-TiC system, the synthesis of MAX phases Ti3AlC2 and Ti2AlC occurs; in the powder of the TiAl-SiC system, Ti2AlC, Ti3AlC2, and Ti3SiC2 are synthesized; in the powder of the (Ti,Cr)C-Al system, Ti2AlC and Cr2AlC are synthesized; in the powder of the Cr3C2-Al system, Cr2AlC is synthesized. In addition to the MAX phases and the phases of the initial components of powder mixtures, the MChS products also contain phases of Ti3AlC, Ti5Si3 and Cr5Al8. It is preferable to use high velocity thermal spraying methods such as HVOF and cold spraying to preserve MAX phases in coatings. The interaction time with oxygen and the high-temperature jet is reduced, and coatings phase composition corresponds to the phase composition of the sprayed powder. In the case of using plasma spraying methods, the synthesis of MAX phases can occur directly during spraying and the formation of the coating layer.
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Ivashchenko, V. I., and L. A. Ivashchenko. "Stability and Properties of the Solid Solutions Based on Carbides, Borides and MAX Phases." In 2019 IEEE 9th International Conference Nanomaterials: Applications & Properties (NAP). IEEE, 2019. http://dx.doi.org/10.1109/nap47236.2019.219070.
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Ahmed, Nihal, Nzubechukwu Okolie, and Sujan Ghosh. "Novel Polyetheretherketone/Polytetrafluoroethylene Composites Reinforced With Titanium Silicon Carbide for Conveyor Chute." In ASME 2024 Aerospace Structures, Structural Dynamics, and Materials Conference. American Society of Mechanical Engineers, 2024. http://dx.doi.org/10.1115/ssdm2024-121599.
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Abstract The e-commerce industry has witnessed unprecedented growth in recent years, accelerated by the global pandemic and changing consumer behaviors. This demand has placed great strain on traditional conveyor chute materials, causing high friction and wear, leading to high maintenance costs and reduced operational efficiency. In this research, Polyetheretherketone (PEEK) + Polytetrafluoroethylene (PTFE) + MAX phases (Ti3SiC2) nanocomposite materials were tested for conveyor chute applications. The composite was fabricated by mixing the powder in a specific weight ratio, pressing them in a die, and finally sintering the pressed disc at 300°C. Tribological tests were performed in linear reciprocating motion using a Cr-Steel counterface. The nanocomposite materials show a COF of 0.06, lower than the PEEK and PTFE materials. More importantly, when tested under the same condition, the PTFE+PEEK+MAX phases composite showed a one-degree lower wear rate than the PEEK and PTFE materials. The microscope image shows that the physical presence of MAX phases helps the composites to attain better compaction, higher hardness, and better load-carrying capacity. The materials’ better compression and enhanced hardness help improve the composite’s tribological properties. Moreover, the better compaction of the PTFE+PEEK+MAX composite increases the water contact angle of these materials compared to the PTFE and PEEK materials. This novel composite can be an excellent replacement for the current materials used for conveyor chute applications.
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Elsenberg, Andreas, Frank Gärtner, and Thomas Klassen. "Aerosol Deposition of Ti3SiC2-MAX-Phase Coatings." In ITSC2021, edited by F. Azarmi, X. Chen, J. Cizek, et al. ASM International, 2021. http://dx.doi.org/10.31399/asm.cp.itsc2021p0340.
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Abstract In general, similar MAX-Phase coatings are considered as oxidation protection layer for preventing disastrous reactions of the Zircaloy fuel rods during a cooling water failure in a nuclear power plant. For the present study on Aerosol Deposition, Ti3SiC2 was selected as MAX-phase model system due to the availability of property data and commercial powder. The as-received powder was milled to different nominal sizes. For revealing details on coating formation and possible bonding mechanisms, Aerosol Deposition experiments were performed for different particle size batches and process gas pressures. Microstructural analyses reveal that coating formation preferably occurs for particle sizes smaller than two microns. Using such small particle sizes, crack-free, dense layers can be obtained. The individual deposition efficiencies for the different particle sizes, particularly the critical size below which deposition gets prominent, vary with process gas flows and associated pressures. Detailed microstructural analyses of coatings by high resolution scanning electron microscopy reveal plastic deformation and fracture, both attributing to shape adaption to previous spray layers and probably bonding. In correlation to coating thickness or deposition efficiencies, respective results give indications for possible bonding mechanisms and a tentative window of Aerosol Deposition for Ti3SiC2 MAX-phases as spray material.
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Rud, Alexander, Inna Kirian, Andrey Lakhnik, et al. "Synthesis of the Ti3SiC2 MAX-phase by pressureless technique." In IXth INTERNATIONAL SAMSONOV CONFERENCE “MATERIALS SCIENCE OF REFRACTORY COMPOUNDS”. Frantsevich Ukrainian Materials Research Society, 2024. http://dx.doi.org/10.62564/m4-ar1353.
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Recently, the practical interest of researchers has attracted the MAX phase of Ti3SiC2. This phase is characterized by high electrical and thermal conductivities, low density, high Young’s modulus and fracture toughness. The main disadvantage of existing methods for the synthesis of this MAX phase is the presence of impurity phases such as TiC, SiC, Ti5Si3 or TiSi2. The current investigation represents the results of Ti3SiC2 MAX phase synthesis by pressureless sintering. The Ti, Si, and spectrally pure graphite were used to prepare the powder blend. The homogenization of the mixture was carried out at room temperature for duration of 1 hour using a high-energy laboratory planetary mill (Fritsch Pulverisette P-6). Homogenized powder blends were compacted as cylindrical pellets which was sintered at different temperatures in an argon atmosphere for 3 h. The processes of phase formation during synthesis and the structural parameters of individual phases have been studied by SEM, XRD and NMR spectroscopy. The sample sintered at 1300 ºC from Ti3:Si1.1:C2 mixture contained several phase: Ti3SiC2, TiC, SiC and graphite. The percentage of the Ti3SiC2 estimated by full-profile analysis is only about ~ 33 wt.%. An increase in temperature leads to a growth in the content of the phase Ti3SiC2 in the sample. The highest maximum yield of the phase Ti3SiC2 ~ 81 wt.% was achieved for the Ti3:Si1.1:C2 mixture at a temperature of 1385 ºC. In addition, about 19 wt% TiC was also observed in this sample. During the heating of the powder mixture to the synthesis temperature of the MAX phase, partial evaporation of silicon occurs. It results in a significant stoichiometric ratio violation of the elements, which leads to a decrease in the content of the Ti3SiC2 phase in the sample. Increasing the silicon content in the initial mixture to ~ 2 wt.% contributed to the production of the MAX phase with a purity of ~ 95 wt.%.
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Davydov, Denis M., Aleksandr P. Amosov, Evgeniy I. Latukhin, and Emil R. Umerov. "SHS of porous skeletons of Ti3AlC2 and Ti3SiC2 MAX phases using different brands of starting powders." In MATHEMATICS EDUCATION AND LEARNING. AIP Publishing, 2022. http://dx.doi.org/10.1063/5.0098878.
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Gauthier-Brunet, V., A. Zuber, J. Roger, J. Gonzalez-Julian, and S. Dubois. "High-Temperature Oxidation Of Cr2AlC MAX Phase Produced By Different Powder Metallurgy Routes: Study Of The Relationship Between Microstructure And Oxidation Resistance." In Euro Powder Metallurgy 2023 Congress & Exhibition. EPMA, 2023. http://dx.doi.org/10.59499/ep235763879.
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MAX phases are a family of nanolayered carbides and nitrides widely studied for their unique properties cumulating those of ceramics and metals. Cr2AlC is considered as one of the most promising MAX phase for its corrosion resistance properties. In this study, fine and coarse-grained Cr2AlC samples were respectively synthesized using spark plasma sintering and hot isostatic pressing techniques. The operating parameters were varied to optimize the purity and the density of the end-product. Oxidation tests were carried out in dry air on fine and coarse-grained polycrystalline samples in the temperature range 800-1400 ◦C up to 1000h. Thermodynamic calculations were also performed to give further analysis of the experiments and to better understand the oxidation mechanisms. The effect of both the oxidation conditions and the MAX phases microstructural characteristics (grain size) were studied via the observation of the oxide layers morphology, the analysis of the oxidation products and the study of the oxidation kinetics.
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Lester, Brian T., and Dimitris C. Lagoudas. "Modeling of Hybrid Shape Memory Alloy Composites Incorporating MAX Phase Ceramics." In ASME 2012 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/smasis2012-7969.
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A new hybrid shape memory alloy (SMA)-ceramic composite is being developed for use in extreme environments. The proposed composition is intended to address past issues with brittle failure in the ceramic phase by generating a compressive residual stress state in that phase. This biasing load takes advantage of the superior mechanical properties of ceramics when loaded in compression. Past investigations of SMA composites with an elasto-plastic second phase have shown that such a residual stress state may be developed in the second phase through the generation of irrecoverable, plastic strains. To take advantage of this characteristic, a class of ceramics known as the MAX phases are being used. These ceramics have a unique response characterized by the formation of kink bands which can allow for both recoverable and irrecoverable inelastic strains. A model of the hybrid composite incorporating this response and the effects of the microstructure is developed to explore the ability of this material system to generate such stress states. To this end, an approximation of the MAX phase response is introduced to describe the irrecoverable kink band formation. The effects of the microstructure are accounted for through the generation of a finite element mesh from microtomography results of the considered composite. Finite element simulations of the hybrid composite are performed using the assumed MAX phase response and a recent 3D phenomenological SMA constitutive model. The effective stress-temperature response of the composite is determined and the interaction of the different phases is discussed. Specifically, it is shown that composite still exhibits a hysteretic response although with a decreased hysteresis height and shifted transformation temperatures. The effect of the microstructure on the composite response is discussed. Finally, it is shown that through an actuation loading path a compressive residual stress state is developed in the ceramic phase.
Reports on the topic "Synthèse des phases MAX"
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_TCHIBOZO-KEKELE, Chanceline, Rodrigue Castro GBEDOMON, Laurenda TODOME, and Fréjus Thoto. Inventaire et caractérisation des espaces verts dans les localités urbaines de la commune d’Abomey-Calavi au Sud-Bénin. ACED, 2024. http://dx.doi.org/10.61647/aa62333.
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Cette étude se concentre sur l'évaluation des espaces verts (EV) dans la commune d'Abomey-Calavi. Les principaux objectifs étaient d’inventorier les espaces verts existants, de caractériser leur état actuel et de proposer des recommandations pour améliorer et préserver ces espaces. L'approche méthodologique s'est basée sur trois phases principales : consultation des autorités locales pour vérifier l'existence d'un répertoire des EV ; inventaire et caractérisation sur le terrain, incluant la collecte des coordonnées géographiques ; et enfin, une synthèse des connaissances pour analyser les données et formuler des recommandations. L'inventaire a permis d'identifier dix espaces verts d’une superficie moyenne de 8 000 m² dans les localités de Godomey, Akassato et Abomey-Calavi, représentant seulement 0,08 % de la superficie des trois arrondissements et offrant un ratio de 0,46 m² d’EV par habitant, très inférieur à la recommandation de 10 m² par habitant. Parmi les EV identifiés, neuf sont publics et accessibles, mais souvent mal aménagés et sujets à une dégradation rapide. Quarante-quatre espèces d’arbres ont été recensées, avec Khaya senegalensis, Mangifera indica et Cocos nucifera étant les plus fréquentes. De plus, trente réserves administratives dédiées aux EV ont été identifiées sur un total de 55 réserves disponibles. L'étude met en évidence la nécessité
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Barsoum, Michel, Grady Bentzel, Darin J. Tallman, Robert Sindelar, Brenda Garcia-Diaz, and Elizabeth Hoffman. Diffusion, Thermal Properties and Chemical Compatibilities of Select MAX Phases with Materials For Advanced Nuclear Systems. Office of Scientific and Technical Information (OSTI), 2016. http://dx.doi.org/10.2172/1253946.
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Bouchard, Aline, and Christophe Boudry. Utilisation et usages des identifiants numériques chercheurs en France. Synthèse de l’enquête nationale 2023. Ministère de l’enseignement supérieur et de la recherche, 2024. http://dx.doi.org/10.52949/57.
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L’enquête présentée dans ce rapport s’insère dans un projet de recherche composé de quatre phases qualitatives et quantitatives, dont les résultats seront publiés au fur et à mesure de l’avancement du projet. Le présent rapport en constitue la première partie et présente les résultats d’un questionnaire national, conduit entre novembre 2022 et février 2023. Son objectif principal était de faire un état des lieux des usages des identifiants numériques chercheurs (INC), et plus particulièrement d’ORCID, dans la communauté de recherche française, en étudiant leur contexte, leur connaissance et leurs pratiques associées, les moteurs et freins à leur adoption, et les besoins de formation à ces outils. 6 125 personnes ont complété intégralement ce questionnaire national, ce qui correspond à environ 3,2 % de la population nationale des chercheurs. La première partie de ce rapport questionne les répondants sur leur familiarité et leurs connaissances des réseaux sociaux académiques (RSA), outils de visibilité et identifiants numériques chercheurs. Cette partie met en évidence le rôle essentiel de la discipline dans l’appropriation de ces différents outils, de grandes catégories d’usages et différents degrés d’acculturation à ces outils. La deuxième partie de ce rapport concerne spécifiquement l’INC ORCID, et montre globalement une connaissance et une utilisation avant tout concrète et pragmatique de cet identifiant par les chercheurs. Concernant les besoins en formation ou initiation à ces outils, selon les chercheurs interrogés, ils s’avèrent être encore importants, que ce soit en présentiel ou en distanciel.
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L51599 The Significance of Local Hard Zones on Outside of Girth Welds. Pipeline Research Council International, Inc. (PRCI), 1989. http://dx.doi.org/10.55274/r0010097.
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In petrochemical and oil and gas production plant the presence of sour H2S containing environments poses problems with regard to material behavior. The corrosion reaction between H2S and steel produces atomic hydrogen, which enters the steel and may, for example, lead to hydrogen pressure cracking (HPC) if steel quality is such that inclusion levels promote the entrapment of hydrogen gas. Fortunately this problem may be readily controlled by attention to steel cleanliness. A potentially more serious problem relating to sour environments is sulphide stress cracking (SSC), when the presence of hydrogen may lead to stress corrosion cracking in a susceptible material. In carbon-manganese steels, susceptibility to SSC is associated with a hardened microstructure and control of the problem therefore requires limitations on material hardness. This is especially important in welded structures where the rapid cooling associated with welding may lead to a hardened heat affected zone (HAZ), together with significant residual welding stress. To determine to what extent a relaxation in external hardness could be possible, The Welding Institute proposed a program of work to study the influence of hardness and stress levels on the cracking propensity of GMA welds in pipeline steel. The project was to be carried out in two phases: in the first, the hardness limit for internal GMA bead on pipe welds (simulating weld root regions) was to be determined in a sour (NACE) solution; in Phase 2, external bead on pipe welds (simulating weld cap regions) would be assessed, again with the sour environment on the inside of the pipe. This report presents the results of both phases of the study. In order to study the influence of wall thickness on cracking behavior, seamless pipe materials to API-5L-X52 specification were obtained in 408 mm (16 in) diameter with nominal wall thickness of 9.5, 12.7, 19.0 and 25.4 mm (0.37, 0.5, 0.75 and 1.0 in). Chemical analysis results are given. The materials were supplied in accordance with NACE MR-01-75 hardness specifications (22 HRC max), although no additional requirements were specified. Pipe B, which was obtained from a different supplier to the remaining pipes, had significantly higher sulfur content. Some variations existed between parent material microstructures, although all may be considered typical of the grade of steel. This program seeks to determine the threshold hardness level for sour service of as-deposited (un re-heated) weldment regions in the capping pass of girth welds in pipeline steel. Assessment has been made by comparing the cracking behavior in the NACE TM-01-77 test environment of internal and external single pass welds produced with a range of conditions by the GMAW process.