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Статті в журналах з теми "Graphene liquid interface"
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Chen, Xianjue, and Colin L. Raston. "Liquid interface evolution of polyhedral-like graphene." Chemical Communications 51, no. 78 (2015): 14609–12. http://dx.doi.org/10.1039/c5cc05888k.
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Peng, Xiaoyi, Pengfei Jiang, Yulou Ouyang, Shuang Lu, Weijun Ren, and Jie Chen. "Reducing Kapitza resistance between graphene/water interface via interfacial superlattice structure." Nanotechnology 33, no. 3 (October 29, 2021): 035707. http://dx.doi.org/10.1088/1361-6528/ac2f5c.
Повний текст джерелаАнотація:
Abstract The control of thermal transport across solid/liquid interface has attracted great interests for efficient thermal management in the integrated devices. Based on molecular dynamics simulations, we study the effect of interfacial superlattice structure on the Kapitza resistance between graphene/water interface. Compared to the original interface, introducing interfacial superlattice structure can result in an obvious reduction of Kapitza resistance by as large as 40%, exhibiting a decreasing trend of Kapitza resistance with the decrease of superlattice period. Surprisingly, by analyzing the structure of water block and atomic vibration characteristics on both sides of the interface, we find the interfacial superlattice structure has a minor effect on the water structure and overlap in the vibrational spectrum, suggesting that the improved interfacial heat transfer is not mainly originated from the liquid block. Instead, the spectral energy density analysis reveals that phonon scattering rate in the interfacial graphene layer is significantly enhanced after superlattice decoration, giving rise to the increased thermal resistance between the interfacial graphene layer and its nearest neighboring layer. As this thermal resistance is coupled to the Kapitza resistance due to the local nature of interfacial superlattice decoration, the enhanced thermal resistance in the solid segment indirectly reduces the Kapitza resistance between graphene/water interface, which is supported by the enhancement of the spectral interfacial thermal conductance upon superlattce decoration at microscopic level. Our study uncovers the physical mechanism for controlling heat transfer across solid/liquid interface via interfacial superlattice structure, which might provide valuable insights for designing efficient thermal interfaces.
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Kam, Kevin, Brianne Tengan, Cody Hayashi, Richard Ordonez, and David Garmire. "Polar Organic Gate Dielectrics for Graphene Field-Effect Transistor-Based Sensor Technology." Sensors 18, no. 9 (August 23, 2018): 2774. http://dx.doi.org/10.3390/s18092774.
Повний текст джерелаАнотація:
We have pioneered the use of liquid polar organic molecules as alternatives to rigid gate-dielectrics for the fabrication of graphene field-effect transistors. The unique high net dipole moment of various polar organic molecules allows for easy manipulation of graphene’s conductivity due to the formation of an electrical double layer with a high-capacitance at the liquid and graphene interface. Here, we compare the performances of dimethyl sulfoxide (DMSO), acetonitrile, propionamide, and valeramide as polar organic liquid dielectrics in graphene field-effect transistors (GFETs). We demonstrate improved performance for a GFET with a liquid dielectric comprised of DMSO with high electron and hole mobilities of 154.0 cm2/Vs and 154.6 cm2/Vs, respectively, and a Dirac voltage <5 V.
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Shao, Jiao-Jing, Si-Da Wu, Shao-Bo Zhang, Wei Lv, Fang-Yuan Su, and Quan-Hong Yang. "Graphene oxide hydrogel at solid/liquid interface." Chemical Communications 47, no. 20 (2011): 5771. http://dx.doi.org/10.1039/c1cc11166c.
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Xin, Jing, Beibei Xie, Ya Li, Juanjuan Shang, Yujiao Qiu, Libing Liu, Shaofu Zhao, Lidan Fan, and Renjie Zhang. "Formation of graphene oxide films at the liquid/liquid interface." Composite Interfaces 21, no. 7 (May 19, 2014): 623–30. http://dx.doi.org/10.1080/15685543.2014.918789.
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Wehrhold, Michel, Tilmann J. Neubert, Anur Yadav, Martin Vondráček, Rodrigo M. Iost, Jan Honolka, and Kannan Balasubramanian. "pH sensitivity of interfacial electron transfer at a supported graphene monolayer." Nanoscale 11, no. 31 (2019): 14742–56. http://dx.doi.org/10.1039/c9nr05049c.
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Patil, Sagar H., Bihag Anothumakkool, Shivaram D. Sathaye, and Kashinath R. Patil. "Architecturally designed Pt–MoS2 and Pt–graphene composites for electrocatalytic methanol oxidation." Physical Chemistry Chemical Physics 17, no. 39 (2015): 26101–10. http://dx.doi.org/10.1039/c5cp04141d.
Повний текст джерелаАнотація:
Pt particles (2–3 nm) deposited using a liquid–liquid interface reaction technique are used to construct LbL architectures to form MoS2/graphene composites for efficient methanol oxidation.
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Chen, Long, Liangliang Huang, and Jiahua Zhu. "Stitching graphene oxide sheets into a membrane at a liquid/liquid interface." Chem. Commun. 50, no. 100 (October 21, 2014): 15944–47. http://dx.doi.org/10.1039/c4cc07558g.
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Allaire, Ryan H., Abhijeet Dhakane, Reece Emery, P. Ganesh, Philip D. Rack, Lou Kondic, Linda Cummings, and Miguel Fuentes-Cabrera. "Surface, Interface, and Temperature Effects on the Phase Separation and Nanoparticle Self Assembly of Bi-Metallic Ni0.5Ag0.5: A Molecular Dynamics Study." Nanomaterials 9, no. 7 (July 21, 2019): 1040. http://dx.doi.org/10.3390/nano9071040.
Повний текст джерелаАнотація:
Classical molecular dynamics (MD) simulations were used to investigate how free surfaces, as well as supporting substrates, affect phase separation in a NiAg alloy. Bulk samples, droplets, and droplets deposited on a graphene substrate were investigated at temperatures that spanned regions of interest in the bulk NiAg phase diagram, i.e., miscible and immiscible liquid, liquid-crystal, and crystal-crystal regions. Using MD simulations to cool down a bulk sample from 3000 K to 800 K, it was found that phase separation below 2400 K takes place in agreement with the phase diagram. When free surface effects were introduced, phase separation was accompanied by a core-shell transformation: spherical droplets created from the bulk samples became core-shell nanoparticles with a shell made mostly of Ag atoms and a core made of Ni atoms. When such droplets were deposited on a graphene substrate, the phase separation was accompanied by Ni layering at the graphene interface and Ag at the vacuum interface. Thus, it should be possible to create NiAg core-shell and layer-like nanostructures by quenching liquid NiAg samples on tailored substrates. Furthermore, interesting bimetallic nanoparticle morphologies might be tuned via control of the surface and interface energies and chemical instabilities of the system.
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Rodgers, Andrew N. J., and Robert A. W. Dryfe. "Oxygen Reduction at the Liquid-Liquid Interface: Bipolar Electrochemistry through Adsorbed Graphene Layers." ChemElectroChem 3, no. 3 (October 22, 2015): 472–79. http://dx.doi.org/10.1002/celc.201500343.
Повний текст джерелаДисертації з теми "Graphene liquid interface"
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Rodgers, Andrew Norman John. "Dispersion, assembly and electrochemistry of graphene at the liquid-liquid interface." Thesis, University of Manchester, 2015. https://www.research.manchester.ac.uk/portal/en/theses/dispersion-assembly-and-electrochemistry-of-graphene-at-the-liquidliquid-interface(c2ffd27a-cf5f-45c2-a471-60dcab788e12).html.
Повний текст джерелаАнотація:
The dispersion of graphene in 1,2-dichloroethane (DCE), its subsequent attachment at the water-DCE interface and the reduction of oxygen at the water-DCE interface proceeding via interfacial graphene have been investigated. Using addition of an electrolyte which screens surface charge, it was found that electrostatic repulsions play a significant role in determining the kinetic stability of lyophobic non-aqueous graphene dispersions. The onset of aggregation was determined and it was found that dispersions prepared from higher-oxygen content graphite were more stable than those prepared from lower-oxygen content graphite, indicating that oxygen content is important in determining the surface charge on graphene in non-aqueous dispersion. The presence of organic electrolyte was also found to promote assembly of graphene into a coherent film at the liquid-liquid interface. Measurement of the liquid-liquid interfacial tension and three-phase contact angle revealed that the energetics of particle attachment did not change in the presence of organic electrolyte, thus indicating a mechanism of inter-particle electrostatic repulsion minimisation through surface charge screening. Interfacial graphene was found to display a catalytic effect toward the oxygen reduction reaction at the water-DCE interface. A bipolar cell was developed which showed that this reaction occurs heterogeneously, with graphene acting as a conduit for electrons across the water-DCE interface.
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Bordes, Emilie. "Graphène dans des liquides ioniques : interactions aux interfaces, exfoliation, stabilisation." Thesis, Université Clermont Auvergne (2017-2020), 2017. http://www.theses.fr/2017CLFAC052.
Повний текст джерелаАнотація:
L'exfoliation en phase liquide du graphite est l'une des méthodes les plus prometteuses pour augmenter la production et la disponibilité commerciale du graphène. Le processus d'exfoliation peut être décrit, de manière conceptuelle, en quatre étapes: le contact du graphite avec le liquide, l'intercalation du solvant entre les feuillets de graphène, la dispersion du matériau à deux dimension et sa stabilisation en phase liquide. Comme les liquides ioniques peuvent être facilement obtenus avec différentes structures moléculaires et donc des propriétés physicochimiques modulables, ils ont été utilisés dans cette thèse comme milieux liquides pour l'exfoliation du graphite. Notre objectif est d'optimiser l'exfoliation du graphite à travers la compréhension des mécanismes moléculaires et des interactions impliquées dans chaque étape du processus. Les énergies interfaciale graphite-liquide ont été calculées à partir de tensions de surface et d'angles de contact mesurées entre des liquides ioniques et du graphite pour déterminer l'affinité de différents liquides à la surface du graphite. Afin d'étudier cette interface liquide - solide, des simulations en dynamique moléculaire ont été menées pour analyser l'organisation des liquides ioniques à la surface du graphite. De même, l'énergie libre nécessaire pour créer des cavités au sein du liquide ionique a été calculée.Des simulations moléculaires ont également été réalisées pour modéliser l'exfoliation d'un feuillet de graphène à partir de graphite en apportant une vue microscopique de l'intercalation des molécules de solvant. L'énergie nécessaire à l'exfoliation a pu être calculée en présence de différents liquides. Des composés polyaromatiques ont été considérés comme des modèles pour le graphène car ils peuvent être facilement obtenus purs, sans variabilité de structure, défauts ou groupes fonctionnels non contrôlés. Les enthalpies de dissolution du naphtalène, anthracène et pyrène dans différents liquides ioniques ont été mesurées par calorimétrie en solution et liées à leur solubilité. L'organisation des ions autour de ces composés modèles a été étudiée par simulation moléculaire et spectroscopie Infra-Rouge.Après l'exfoliation, les échantillons de graphène en suspension dans différents liquides ioniques ont été caractérisés expérimentalement en termes de taille de feuillets (microscopie électronique à transmission et microscopie à force atomique), nombre de couches de graphène (microscopie à force atomique, spectroscopie Raman), concentration totale (spectroscopie UV-visible) et pureté du matériau exfolié (spectroscopie de photoélectrons~X). Vingt liquides ioniques différents à base de cations imidazolium, pyrrolidinium et ammonium et d'anions bis (trifluorométhylsulfonyl)imide, triflate, dicyanamide, tricyanométhanide et méthylsulfate ont été testés. Les interactions moléculaires permettant d'établir de règles de conception pour les liquides ioniques capables d'exfolier les matériaux carbonés ont été identifiées. Le cation pyrrolidinium a montré des résultats prometteurs dans toutes les étapes du processus d'exfoliation, par rapport au cation imidazolium ou ammonium. La sélection d'un grand anion flexible a réduit l'énergie interfaciale avec le graphite, dispersé les nanocarbones en augmentant l'entropie du système et stabilisé le graphite exfolié en plus grande quantité. Un petit anion tel que le triflate semble être favorable à l'obtention de graphène, même si la taille des couches et leur quantité sont réduites. Un liquide ionique ayant une partie apolaire importante facilitera l'insertion et la dispersion du nanomatériau de carbone. Pour la stabilisation du graphite, les interactions alkyle-π et π- π sont décisivesThe liquid-phase exfoliation of graphite is one of the most promising methods to increase production and commercial availability of graphene. The exfoliation process can be conceptually described in four steps: the contact of the graphite with liquid, the intercalation of the solvent between layers, the dispersion of the two dimensional material, and its stabilization in the liquid-phase. Because ionic liquids can be easily obtained with chosen molecular structures and tunable physicochemical properties, they were used in this study as liquid media for the exfoliation of graphite. Our aim is to optimize the exfoliation of graphite through the understanding of the molecular mechanisms and of the interactions involved in each step of the process.The liquid-graphite interfacial energies from measured surface tensions and contact angles, between ionic liquids and pristine graphite surface, were used to determine the affinity of different liquids at the surface of graphite. In order to investigate this interface, molecular dynamics simulations were conducted to analyse the ordering of ionic liquids at the surface of graphite. The free energies necessary to create cavities inside the bulk ionic liquid have also been studied.Molecular simulations were also used to study the exfoliation of one graphene layer from a stack of graphite and hence provide a microscopic view of the intercalation of solvent molecules. The energies involved in the process have been calculated.Polyaromatic compounds were regarded as models for graphene as they can be easily obtained pure, without structure variability, defects or uncontrolled functional groups. Enthalpies of dissolution of polyaromatic hydrocarbons (naphthalene, anthracene and pyrene) in different ionic liquids were measured by solution calorimetry and related with their solubility. The ordering of the ions around this model compounds were studied by molecular simulation and spectroscopy Infra-Red.After exfoliation, samples of suspended graphene in different ionic liquids have been characterized experimentally in terms of flake size (using transmission electron microscopy and atomic force microscopy), number of layers (atomic force microscopy, spectroscopy Raman), total concentration (UV-visible spectroscopy) and purity of the exfoliated material (X-ray photoelectron spectrometry).Twenty different ionic liquids based on imidazolium, pyrrolidinium and ammonium cations and on bis(trifluoromethylsulfonyl)imide, triflate, dicyanamide, tricyanomethanide, and methyl sulfate have been tested. The molecular interactions have been identified thus allowing the establishment of design rules for ionic liquids capable of exfoliating carbon materials. The pyrrolidinium cation has shown promising results in all the steps of exfoliation process, compared to the imidazolium or ammonium cation. Selecting a large and flexible anion reduced the interfacial energy with graphite, dispersed the nanocarbons by increasing the entropy of the system and stabilized the exfoliated graphite in larger quantity. A small anion such as triflate appears to be favorable for obtaining graphene, whereas the size of the layers and their quantity is reduced. An ionic liquid having an important apolar portion will facilitate the insertion and dispersion of graphene layers. For the stabilization of graphite, the alkyl-π et π -π interactions are decisive
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Rakotozafy, Samuel. "Étude de films mixtes formés par physisorption sur les plans de base du graphite de deux adsorbats de propriétés de condensation très différentes : transition de déplacement : solutions bidimensionnelles." Nancy 1, 1993. http://www.theses.fr/1993NAN10226.
Повний текст джерелаАнотація:
L'étude thermodynamique, effectuée entre 77 et 84 k, du déplacement par adsorption de krypton d'une couche de cyclohexane pré-déposé sur graphite a permis de déterminer la température critique de déplacement, soit 80,5 k. L'étude du film mixte dichloromethane-xenon (ch#2cl#2-xe) adsorbé sur graphite a pour préalable celle du film pur de ch#2cl#2 sur le même substrat, caractérisé par volumétrie d'adsorption entre 180 et 217 k, et par diffraction de neutrons entre 110 et 170 k. Ch#2cl#2 formé sur le graphite une seule couche monomoléculaire dense de structure rectangulaire centree commensurable 35, qui fond a environ 159 k. La température critique bidimensionnelle (2d) est 201 k. Une seconde couche peu dense pourrait également se former. La caractérisation thermodynamique du film ch#2cl#2-xe montre que l'adsorption de xénon entre 95 et 115 k sur graphite pré-recouvert de ch#2cl#2 donne lieu, avant adsorption du xenon sur lui-même, au déplacement partiel de la couche pré-déposée et a la formation d'une solution 2d (ch#2cl#2-xe). L'organisation de la couche fait apparaitre des difficultés de germination. La solution 2d, bien que correspondant à une phase bien définie est métastable, et on observe sa demixion partielle lorsque l'on adsorbe des quantités croissantes de xenon. La caractérisation structurale de ce système par diffraction de neutrons a donné lieu a l'observation de la compression unidirectionnelle de ch#2cl#2 pré-déposé par adsorption de xenon. Elle a permis de confirmer l'hypothèse de l'existence d'une solution 2d (xe-ch#2cl#2) sous forme de bicouche dans laquelle au moins ch#2cl#2 présente un arrangement périodique
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Bickerstaffe, Anna Kristina. "Crystallisation at the solid/liquid interface : carboxylic acids on graphite and ice crystals in solution." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613988.
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Pavlov, Aleksey D. "Improvement of Electromagnetic Railgun Barrel Performance and Lifetime by Method of Interfaces and Augmented Projectiles." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/986.
Повний текст джерелаАнотація:
Several methods of increasing railgun barrel performance and lifetime are investigated. These include two different barrel-projectile interface coatings: a solid graphite coating and a liquid eutectic indium-gallium alloy coating. These coatings are characterized and their usability in a railgun application is evaluated. A new type of projectile, in which the electrical conductivity varies as a function of position in order to condition current flow, is proposed and simulated with FEA software. The graphite coating was found to measurably reduce the forces of friction inside the bore but was so thin that it did not improve contact. The added contact resistance of the graphite was measured and gauged to not be problematic on larger scale railguns. The liquid metal was found to greatly improve contact and not introduce extra resistance but its hazardous nature and tremendous cost detracted from its usability. The simulated resistivity augmented projectiles were able to mitigate harmful current build-up on the back of a projectile using different conductivity gradients. Within the range of conductivity of aluminum alloys no simulated gradient was able to fully level the current density, however, once the range was expanded to include the lower conductivity of titanium, nearly uniform current density was achieved.
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Parker, Julia Elizabeth. "Adsorption at the solid/liquid interface : adsorption and mixing behaviour of fluorinated alkyl species on the surface of graphite." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611213.
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Yang, Jing. "Phosphonium ionic liquids : Versatile nanostructuration and interfacial agents for poly(vinylidene fluoride-chlorotrifluoroethylene)." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEI072/document.
Повний текст джерелаАнотація:
Ce travail de thèse porte sur la compréhension du rôle polyvalent des liquides ioniques (LIs) phosphonium comme agents de nanostructuration et interfaciaux pour la matrice polymère fluorée poly(fluorure de vinylidène-chlorotrifluoroéthylène) (P(VDF-CTFE)). Dans un premier temps, deux LIs phosphonium avec des fonctionnalités différentes générant un encombrement stérique et des fonctions dipolaire additionnelles sont tout d'abord incorporés dans la matrice P(VDF-CTFE) pour préparer des films de polymère additives. La structure de la phase cristalline, la morphologie issue de la dispersion et le comportement de cristallisation sont finement caractérisés dans le but de fournir une compréhension fuie et complète du rôle joué par le LI sur la nanostructuration. Dans un second temps, le rôle d’agent interfacial du LI est étudié avec un LI phosphonium fluoré comprenant un cation combinant trois phényles et une chaîne fluorée courte.Ce LI est utilise pour modifier la surface de l'oxyde de graphène (GO) et de l'oxyde de graphène réduit (rGO) afin de rendre ces nanocharges fonctionnelles et les incorporer dans la matrice P(VDF-CTFE). Ainsi, des films composites de P(VDF-CTFE)/graphène avec différentes teneurs en nanocharges sont préparés et une caractérisation fuie de la structure et des propriétés est entreprise afin de mieux comprendre les mécanisme d’interaction interfaciale et leurs influences sur les films composites, tels que la structure de la phase cristalline, le comportement de cristallisation, la relaxation des chaînes, la morphologie et les propriétés diélectriques finalesThis thesis work deals with an understanding of the versatile roles of phosphonium ionic liquids (ILs) as nanostructuration and interfacial agents for the fluorinated polymer matrix, i.e.,poly(vinylidene fluoride-chlorotrifluoroethylene) (P(VDF-CTFE)). In this context, two phosphonium ILs with different functionalities in steric hindrance and extra dipolar groups are firstly incorporated in P(VDF-CTFE) matrix to prepare polymer films. The crystalline phase structure, dispersion morphology and crystallization behavior are finely characterized with the goal of providing a full and deep understanding of the versatile and tunable nanostructuration effect of phosphonium ILs. Subsequently, in order to elucidate the mechanism of interfacial influence of IL, a fluorinated phosphonium IL with a cation structure combining three phenyls and a short fluorinated chain is added on the surface of graphene oxide (GO) and reduced graphene oxide (rGO), making them as functional nanofillers to be incorporated into P(VDF-CTFE) matrix. Thus,P(VDF-CTFE)/graphene composite films with different filler contents are prepared in order to investigate the mechanism of interfacial interaction and its influence on the composite films, such as crystalline phase structure, crystallization behavior, chain segmental relaxation behavior, dispersion morphology and the final dielectric properties
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Bonatout, Nathalie. "Etude des films de Langmuir d'oxyde de graphène, de liquides ioniques et des systèmes mixtes." Thesis, Paris 6, 2017. http://www.theses.fr/2017PA066291/document.
Повний текст джерелаАнотація:
Les liquides ioniques et le graphène sont intensivement étudiés, respectivement en tant qu’électrolyte et électrode, pour le développement des supercondensateurs. Dans ce cadre, il est primordial de caractériser l’interface entre les deux espèces. Pour ce faire, nous avons réalisé ce type d’interface par la procédure des films de Langmuir que nous avons observés à différentes échelles via des mesures d’isothermes, de microscopies à angle de Brewster et à force atomique ainsi que par diffusion des rayons X de surface. Nous avons étudié des films formés par des liquides ioniques, de l’oxyde de graphène et enfin d’un mélange de ces deux espèces. L’étude sur les liquides ioniques purs montre que le cation joue un rôle non négligeable sur l’organisation des films à l’interface air-eau, aussi bien en monocouche que lors du passage en phase tridimensionnelle. Par ailleurs, nous avons montré que les films d’oxyde de graphène forment spontanément une bicouche de feuillets à l’interface eau-air même pour de faibles densités superficielles. Enfin concernant les films mixtes, nous avons observé une ségrégation verticale des espèces quand la pression de surface devient suffisamment élevée. Le film est alors composé d’une première couche en contact avec l'eau, majoritairement composée de feuillets d’oxyde de graphène parallèles à l’interface, sur laquelle se superpose une seconde couche formée des domaines de liquide ionique désorganiséGraphene and ionic liquids are intensively studied, respectively as electrolyte and as electrode materials, for the development of supercapacitors. In this framework, the characterization between the two species is essential. We realized such kind of interfaces through the Langmuir film procedure and characterized them at different scales, using isotherm measurements, Brewster Angle and Atomic Force Microscopies, and surface X-ray scattering. We studied films formed by different ionic liquids, by graphene oxide and finally by a mixture of the two species. The study on the pure ionic liquids evidences the role of the cation on the film organization at the air-water interface, for the monolayer as well as for the tridimensional phase. Moreover, we showed that the graphene oxide films are composed of a bilayer of sheets à the interface, even at low surface densities. Finally, regarding the mixed film, we observed a vertical segregation of the species for high enough surface pressures. The film is formed by a first layer in contact with the water surface, mostly composed of graphene oxide sheets parallel to the interface, on which a second layer is superimposed, composed of disorganized ionic liquid domains
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Nguyen, Doan Chau Yen. "Role of deposition temperature and concentration on the self-assembly and reaction of organic molecules at the solution-graphite interface." Doctoral thesis, Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-223658.
Повний текст джерелаАнотація:
Das Hauptthema dieser Dissertation ist die Untersuchung der Selbstorganisation organischer Moleküle an der Flüssig-Fest-Grenzfläche (LSI). Besondere Betonung liegt auf der Kontrolle der Selbstassemblierung durch geeignete Parameter: die Substrattemperatur während der Abscheidung, die Konzentration der gelösten Moleküle, und die chemische Natur der gelösten Stoffe und Lösungsmittel. Die Untersuchungen wurden unter Verwendung der Rastertunnelmikroskopie (STM) durchgeführt. Der erste Schwerpunkt dieser Arbeit ist die systematische Untersuchung der Auswirkung erhöhter Substrattemperatur während der Abscheidung aus der Lösung auf die Selbstorganisation komplexer molekularer Architekturen an der LSI. Diese Untersuchungen wurden mit dem planaren Molekül Trimesinsäure (TMA), sowie dem nicht-planaren Molekül Benzen-1,3,5-triphosphonsäure (BTP) durchgeführt. Es wird gezeigt, dass der Polymorphismus der Adsorbatstrukturen von TMA und BTP durch die Substrattemperatur während der Abscheidung der Moleküle aus der Lösung für verschiedene Lösungsmitteln unterschiedlicher Polarität, wie Phenyloctan, Octansäure und Undecanol, kontrolliert werden kann. Durch die Erhöhung der Temperatur des vorgeheiztem Graphitsubstrates kann die spezifische 2D supramolekulare Struktur and die entsprechende Packungsdichte der Moleküle in der Adsorbatschicht für jedes der untersuchten Lösungsmittel präzise eingestellt werden. Weiterhin wird der Einfluss der Konzentration auf die resultierende Anordnung der TMA Moleküle an der LSI durch ein weiteres Experiment abgeschätzt, bei welchem Rühren (von 0 h bis 40 h) der Lösungen mit verschiedenen Lösungsmitteln eingesetzt wurde. Diese Ergebnisse zeigen, dass die verschiedenen Präparationsmethoden (Erhöhung der Abscheidetemperatur oder Rühren) zu derselben Tendenz der Änderung der geordneten Strukturen sowie der Packungsdichte führt, weswegen man schlussfolgern kann, dass die Erhöhung der Konzentration an der LSI bei erhöhter Abscheidetemperatur ebenso der Hauptgrund für die beobachteten Änderungen ist. Der zweite Schwerpunkt dieser Dissertation ist die Untersuchung von chemischen Reaktionen der selbstassemblierenden Moleküle. Eine Veresterungsreaktion von TMA mit Undecanol wurde gefunden. Weiterhin wurde, als ein erster Schritt zur Untersuchung der Zwillingspolymerisation, die Oligomerisation des Zwillingsmonomers 2,2’-spirobi [4H-1,3,2-benzo-dioxasiline] (SBS) mit STM an der Grenzfläche zwischen der SBS-Undecanol-Lösung und einer Graphitoberfläche untersucht. Erstens wurde durch Ultraschallbehandlung der SBS Lösung in Undecanol für verschieden lange Zeiten die Oligomerisation der SBS Monomere ohne einen Katalysator an der LSI beobachtet. Zweitens konnte die Oligomerisation auch durch Erhöhung der Substrattemperatur während der Abscheidung der Moleküle aus der Lösung initiiert werden. Durch die schrittweise Erhöhung der Temperatur des vorgeheizten Substrates konnten mehrere, verschiedene, periodische Anordnungen von Phenol‒Dimeren, ‒Trimeren, und –Pentameren u.s.w. gefunden werden. Weiterhin wird die Auswirkung der Abscheidetemperatur auf die Selbstorganisation an der LSI nur der Lösungsmittelmoleküle aus dem reinen Lösungsmittel beschrieben. Dies ist wichtig, da die Undecanol‒Moleküle stets mit den gelösten, in dieser Arbeit verwendeten Stoffen (TMA, BTP, SBS) koadsorbieren und lineare Muster bildenThe main aim of this thesis is to study the self-assembly of organic molecules at the liquid-solid interface (LSI). Special emphasis is given to controlling the process of self-assembly via suitable parameters such as: the substrate temperature during the initial deposition, the concentration of dissolved molecules, or the chemical nature of solutes and solvents. The investigations are performed using scanning tunneling microscopy (STM). The first focus of this work is the systematic investigation of the effect of the substrate temperature during the deposition out of the solution on the self-assembly of complex molecular architectures at the LSI. These investigations have been done with the planar molecule trimesic acid (TMA), and the non-planar molecule benzene 1,3,5-triphosphonic acid (BTP). We show that the polymorphism of the adsorbate structures of TMA (also with BTP) can be controlled by the substrate temperature during the deposition of the molecules out of the solution for various solvents of different polarity such as phenyloctane, octanoic acid, and undecanol. By increasing the temperature of the pre-heated graphite substrate, the specific 2D supramolecular structure and the corresponding packing density in the adsorbate layer can be precisely tuned for each kind of the solvents studied. Furthermore, the influence of the concentration on the resulting self-assembly of TMA molecules at the LSI is estimated by another experiment using stirring (from 0 h to 40 h) of the solutions of different kinds of solvents. These results demonstrate that choosing different preparation methods (increasing deposition temperatures or stirring) lead to the same tendency in the change of the self-assembled structures as well as the tuning of the packing density from which it can also be concluded that the increase of the concentration at increased deposition temperatures is also the main reason for the observed changes. The second focus of this work is the investigation of chemical reactions of self-assembling molecules. The esterification of TMA with undecanol was observed. Moreover as a first step to study twin polymerization, the oligomerization of the twin monomer 2,2’-spirobi [4H-1,3,2-benzo-dioxasiline] (SBS) was investigated by STM at the SBS-undecanol solution/graphite interface. Firstly, by ultrasonicating the solution of SBS in undecanol for different times the oligomerization of SBS monomer without any catalyst has been observed at the LSI. Secondly, the oligomerization of SBS monomer can also be initiated by the substrate temperature during the deposition of the molecules out of the solution. By stepwise increasing the temperature of the pre-heated substrate, various periodic assemblies of phenolic dimer, trimer, pentamer resin, and so on were observed. Furthermore, the effect of deposition temperature on the self-assembly of solely solvent molecules from the pure liquid at the LSI is described, which is important because the undecanol solvent molecules are always co-adsorbed with the solutes used in this work (TMA, BTP, SBS) to form linear patterns
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Arrigoni, Claire. "Monocouches nanoporeuses auto-assemblées sur graphite : contrôle et modulation des propriétés de tamis moléculaire." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00623515.
Повний текст джерелаАнотація:
Un des objectifs des récentes études concernant la fonctionnalisation de surface à l'échelle nanométrique est de contrôler les propriétés d'auto-assemblages formés sur des surfaces. Des molécules ont étés synthétisées, capables d'interagir via une unité fonctionnelle dite " clip ", fondée sur l'interdigitation de chaînes alkyles en épitaxie sur le graphite. Ceci a permis la formation d'un auto-assemblage nanoporeux capable d'agir comme matrice hôte pour des molécules invitées. La dynamique de diffusion de molécules invitées a été étudiée en temps réel. La nature des molécules invitées influe sur la diffusion. Ainsi, le système présente des propriétés de tamis moléculaire. L'objectif du présent travail est d'étendre les propriétés de tamis moléculaire de ce type de structure nanoporeuse. Tout d'abord, les moyens de favoriser la formation du réseau nanoporeux ont été étudiés. Ensuite, différentes approches ont été proposées dans le but de moduler les propriétés de tamis moléculaire de la structure en nid d'abeilles. Pour cela, de nouvelles molécules ont été synthétisées afin d'agir sur certaines caractéristiques du réseau formé : taille des cavités en jouant sur la longueur des chaînes périphériques des molécules, géométrie en utilisant les effets liés à la parité des chaînes ou encore affinité chimique des pores pour des applications dans le domaine de la biologie.
Частини книг з теми "Graphene liquid interface"
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Mohamed, M., M. N. B. Omar, A. I. M. Shaiful, R. Rahman, M. F. Hamid, P. S. Kataraki, and A. B. M. Azhar. "Thermal Properties of the Graphene Oxide (GO) Reinforced Epoxy Composites (Thermal Adhesive Liquid Type): Application of Thermal Interface Materials." In Lecture Notes in Mechanical Engineering, 933–40. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0866-7_81.
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Weilandt, E., A. Menck, M. Binggeli, and O. Marti. "Friction Force Measurements on Graphite Steps under Potential Control." In Nanoscale Probes of the Solid/Liquid Interface, 307–15. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-015-8435-7_17.
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Sohrabi, Beheshteh. "Amphiphiles." In Self-Assembly of Materials and Supramolecular Structures [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.107880.
Повний текст джерелаАнотація:
Amphiphiles form a large group of supramolecular structures can aggregate and be adsorbed spontaneously at the interface. Amphiphilicity is a feature of polar contrast between the groups that make up a molecule and their spatial separation. The most important classes of amphiphiles are surfactants, lipoproteins, and polymers that have hydrophilic and hydrophobic chemical moieties covalently bonded and spatially separated. Since surfactants are widely used in various industrial fields, we decide to focus on surfactants in addition to a brief review of the other amphiphiles. Surfactants are used in industrial applications and consumer products, from medical to cosmetics and food industry. Various industries require new surfactants from sustainable and renewable raw materials with improved performance, biocompatibility and minimal environmental impact. For example, liquid phase exfoliation and dispersion methods using surfactants in the solvent media have recently gained lots of attention because of their great potential for large-scale production. Notably, an ideal exfoliation for reaching desired graphene and CNTs may be achievable by molecular engineering of surfactants to improve the quality of molecular interactions. This chapter experimentally and theoretically highlighted physico-chemical characteristic parameters, and interactions of the components, which are essential to design and discover efficient exfoliation and dispersion systems.
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Bussetti, Gianlorenzo, Rossella Yivlialin, Franco Ciccacci, Lamberto Duó, and Alessandro Podestá. "Blistering at the solid-liquid interface: the graphite case-study." In Reference Module in Chemistry, Molecular Sciences and Chemical Engineering. Elsevier, 2023. http://dx.doi.org/10.1016/b978-0-323-85669-0.00063-5.
Повний текст джерелаТези доповідей конференцій з теми "Graphene liquid interface"
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Lopes, Michele Lima, and Douglas Santos Monteiro. "GRAPHENE OXIDE BEHAVIOUR AT AIR-LIQUID INTERFACE." In V Congresso Online Nacional de Química. Congresse.me, 2023. http://dx.doi.org/10.54265/kosm3582.
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Ordonez, Richard C., Noah Acosta, Jordan Melcher, Nackieb Kamin, and David Garmire. "Investigation of Liquid Metal Ohmic Contacts for Graphene Photonic Devices." In ASME 2015 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems collocated with the ASME 2015 13th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/ipack2015-48567.
Повний текст джерелаАнотація:
We demonstrate the first contact resistance measurements of graphene–galinstan (g-g) ohmic contacts in an effort to improve the performance of graphene photonic devices. The nobility of carbon materials provide an interesting graphene sensor application to explore an oxidation free liquid metal - semimetal interface that can be used to lower contact resistance at source/drain terminals of a standard graphene phototransistor. Our methods utilize photopolymerization of the reactive monomer Trimethlylolpropane Triacrylate (TMPTA) in order to fabricate micro structures necessary to overlay liquid metal contacts on graphene. With the use of an industry standard transfer length method (TLM), a contact resistance of −124±28Ω was measured at both standard temperature and pressure. The results from our study suggest that liquid metals such as galinstan are comparable alternatives to rigid semiconductor interfaces and demonstrates interesting boundary characteristics that may lead to heavy chemical doping and associated low resistance contacts that are required to increase sensitivity in graphene photonic devices.
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Bramhaiah, K., and Neena S. John. "Reduced graphene oxide based silver sulfide hybrid films formed at a liquid/liquid interface." In SOLID STATE PHYSICS: Proceedings of the 58th DAE Solid State Physics Symposium 2013. AIP Publishing LLC, 2014. http://dx.doi.org/10.1063/1.4872604.
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Babaei, Hasan, Pawel Keblinski, and J. M. Khodadadi. "Molecular Dynamics Study of the Interfacial Thermal Conductance at the Graphene/Paraffin Interface in Solid and Liquid Phases." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17478.
Повний текст джерелаАнотація:
By utilizing molecular dynamics (MD) simulations, we study the interfacial thermal conductance at the interface of graphene and paraffin. In doing so, we conduct non-equilibrium heat source and sink simulations on systems of parallel and perpendicular configurations in which the heat flow is parallel and perpendicular to the surface of graphene, respectively. For the perpendicular configuration, graphene with different number of layers are considered. The results show that the interfacial thermal conductance decreases with the number of layers and converges to a value which is equal to the obtained conductance by using the parallel configuration. We also study the conductance for the solid phase paraffin. The results indicate that solid paraffin-graphene interfaces have higher conductance values with respect to the corresponding liquid phase systems.
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Wang, Wei, Sehoon Chang, and Gawain Thomas. "Scale-Up Fabrication and Microfluidic Evaluation of Janus Graphene Nanofluids as Novel EOR Agent." In Middle East Oil, Gas and Geosciences Show. SPE, 2023. http://dx.doi.org/10.2118/213484-ms.
Повний текст джерелаАнотація:
Abstract Nanofluid flooding is an emerging enhanced oil recovery (EOR) technique whereby injection fluids containing nanoparticles or nanocomposites are utilized for the oil displacement or injectivity improvement in oil reservoirs. However, current nanofluids with conventional nanoparticles have relatively low efficiency for EOR at simulated reservoir conditions, especially at low concentrations of nanoparticles. This research reported a new cost-effective method for scale-up synthesis of Janus graphene nanosheets and demonstrated a new type of nanomaterials, Janus nanofluids, as highly effective alternative nano-agents for EOR applications. A lyotropic liquid crystal phase as a novel "interfacial nano-reactor" system has been developed for fabricating Janus nanomaterials at nano-scaled liquid-liquid interfaces. Compared to interfacial reaction in a conventional bi-phase system, the new "interfacial nano-reactors" could tremendously enlarge the interfacial area by more than million times for chemical reactions at the interface, and thus allow production of Janus nanomaterials in mass quantity economically for industrial applications. Janus graphene nanosheets synthesized via this method have been characterized and confirmed by multiple techniques including scanning electron microscopy (SEM), Langmuir-Blodgett (LB) isotherm, contact angle, and interfacial tension (IFT) measurements. Interfacial tension measurements have shown that the Janus graphene nanosheets could significantly lower the IFTs between brine and crude oil at simulated reservoir conditions. With low concentration of Janus graphene nanosheets in nanofluid formula, microfluidic flooding experiments have been performed to evaluate the efficiency of the nanofluids for oil displacement in carbonate reservoirs. The results have demonstrated improved efficiency of oil recovery by the novel Janus graphene nanofluids at ultra-low concentration (0.01 wt%).
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Hossain, Mohammad K., Md Mahmudur R. Chowdhury, Mahesh Hosur, Shaik Jeelani, and Nydeia W. Bolden. "Enhanced Properties of Epoxy Composite Reinforced With Amino-Functionalized Graphene Nanoplatelets." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-51483.
Повний текст джерелаАнотація:
A systematic study has been conducted on processing and characterization of epoxy polymer composite to enhance its mechanical, viscoelastic, and thermal properties through optimization of graphene nanoplatelets (GNP). GNP having a two dimensional structure is composed of several layers of graphite nanocrystals stacked together. GNP is expected to provide better reinforcing effect in polymer matrix composites as a nanofiller along with greatly improved mechanical and thermal properties due to its planar structure and ultrahigh aspect ratio. GNP is also considered to be the novel nanofiller due to its exceptional functionalities, high mechanical strength, chemical stability, abundance in nature, and cost effectiveness. Moreover, it possesses an extremely high-specific surface area which carries a high level of transferring stress across the interface and provides higher reinforcement than carbon nanotubes (CNT) in polymer composites. Hence, this research has been focused on the reinforcing effect of the amine-functionalized GNP on mechanical, viscoelastic, and thermal properties of the epoxy resin-EPON 828 composite. Amine functionalized GNP was infused in EPON 828 at different loadings including 0, 0.1, 0.2, 0.3, 0.4, and 0.5 wt% as a reinforcing agent. GNP was infused into epoxy resin Epon 828 Part-A using a high intensity ultrasonic liquid processor followed by a three roll milling processor for better dispersion. The GNP/epoxy mixture was then mixed with the curing agent Epikure 3223 according to the stoichiometric ratio (Part A: Part B = 12:1). The mixture was then placed in a vacuum oven at 40 °C for 10 m to ensure the complete removal of entrapped bubbles and thus reduce the chance of void formation. The as-prepared resin mixture was then poured in rubber molds to prepare samples for mechanical, viscoelastic, and thermal characterization according to ASTM standards. Molds containing liquid epoxy nanocomposites were then kept in the vacuum oven at room temperature for seven days to confirm full curing of the samples according to the manufacturer’s suggestion. Similarly, neat epoxy samples were fabricated to obtain its baseline properties through mechanical, viscoelastic, and thermal characterization and compare these properties with those of nanophased ones. The reinforcing effect of the amine-functionalized GNP on the epoxy was characterized through mechanical, viscoelastic, and thermal analyses. Fracture morphology of mechanically tested samples was evaluated through scanning electronic microscopy (SEM) study. The mechanical properties were determined through flexure test according to the ASTM standard. Dynamic mechanical analysis (DMA) and thermo-mechanical analysis (TMA) were performed to analyze viscoelastic and thermal performances of the composite. In all cases, the 0.4 wt% GNP infused epoxy nanocomposite exhibited the best properties. The 0.4 wt% GNP-loaded epoxy sample showed 20% and 40% improvement in flexure strength and modulus, respectively. Moreover, 16% improvement in the storage modulus and 37% decrease in the coefficient of thermal expansion were observed due to the integration of GNP reinforcement into the epoxy system. Scanning electronic micrographs exhibited smooth fracture surface for the neat sample, whereas the roughness of surface increased due to the GNP incorporation. This is an indication of change in the crack propagation during loading and a higher energy requirement to fracture the GNP-loaded sample.
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McGonigal, G. C., R. H. Bernhardt, Y. H. Yeo, and D. J. Thomson. "STM Imaging of Physisorbed Molecules at the Liquid/Graphite Interface." In Scanned probe microscopy. AIP, 1991. http://dx.doi.org/10.1063/1.41411.
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Barisik, Murat, Ziyuan Shi, and Ali Beskok. "Heat Conduction and Interface Thermal Resistance in Liquid Argon Filled Silver and Graphite Nanochannels." In ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75231.
Повний текст джерелаАнотація:
Heat conduction between two parallel solid walls separated by liquid argon is investigated using three-dimensional molecular dynamics (MD) simulations. Liquid argon molecules confined in silver and graphite nano-channels are examined separately. Heat flux and temperature distribution within the nano-channels are calculated by maintaining a fixed temperature difference between the two solid surfaces. Temperature profiles are linear sufficiently away from the walls, and heat transfer in liquid argon obeys the Fourier law. Temperature jump due to the interface thermal resistance (i.e., Kapitza length) is characterized as a function of the wall temperature. MD results enabled development of a phenomenological model for the Kapitza length, which is utilized as the coefficient of a Navier-type temperature jump boundary condition using continuum heat conduction equation. Analytical solution of this model results in successful predictions of temperature distribution in liquid-argon confined in silver and graphite nano-channels as thin as 7 nm and 3.57 nm, respectively.
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Franek, Friedrich, Andreas Pauschitz, Vladislav E. Lazarev, Georg Vorlaufer, Thomas Dick, and Robin Jisa. "Complex Micromodel Analysis of Wearing Contact Interfaces." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63540.
Повний текст джерелаАнотація:
The behavior of tribological systems with hybrid lubrication using solid lubricants on graphite basis and/or liquid lubricant can be optimized. This can be achieved by a detailed knowledge of the transfer mechanisms induced by the tribological stress and consequential material and surface design adaptations. Our first approach is a finite element model containing a representative model of the real asperity geometry and distribution. With this model we can estimate the temperature and pressure distribution in the contact zone. The model is based on an assembly of volumes which limit the surfaces taking part in heat exchange and load transfer. Each surface has a set of equations for heat exchange and mechanical loading in the contact. Similarly, transport mechanisms concerning the liquid lubricant, solid lubricant particles and the dissemination of wear particles are considered.
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Burbelko, Andriy A., Daniel Gurgul, Edward Fras´, and Edward Guzik. "Multiscale Modeling of Ductile Iron Solidification With Continuous Nucleation by a Cellular Automaton." In ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28764.
Повний текст джерелаАнотація:
The solidification of metals and alloys is a typical example of multiphysics and multiscale engineering systems. The phenomenon of different time and spatial scales should be taken into consideration in the modeling of a microstructure formation: heat diffusion, the components diffusion in the liquid and solid phases, the thermodynamics of phase transformation under a condition of inhomogeneous chemical composition of growing and vanishing phases, phase interface kinetics, and grains nucleation. The results of a two-dimensional modeling of the microstructure formation in a ductile cast iron are presented. The cellular automaton model (CA) was used for the simulation. The model takes into account the nucleation of two kinds of grains that appear inside of the liquid during solidification: austenite and graphite. The six states of CA cells correspond to the above-mentioned three phases (liquid, austenite and graphite) and to the three two-phase interfaces. A numerical solution was used for the modeling of concentration and temperature fields. The parabolic nonlinear differential equations with a source function were solved by using the finite element method and explicit scheme. In the mono-phase cells the source function is equal to zero. In the interface cells the value of the source function varies depending on the local undercooling. The undercooling value depends on the front curvature, the local temperature and the local chemical composition of the phases. Overlapping lattices with the same spatial step were used for concentration field modeling and for the CA. The time scale of the temperature field for this lattice is about 104 times shorter. Due to the above reasons, another lattice was used with a multiple spatial step and the same time step. The new grain nucleation of solid phases from a liquid is a phenomenon which must be taken into account for correct simulation of a polycrystalline structure formation. The cumulative distribution curve approach was used to calculate the number of substrates on which nucleation takes place as a function of under-cooling below the equilibrium temperature. An algorithm of continuous nucleation modeling during solidification is presented. The undercooling of solid phase grain nucleation was calculated on the basis of the inverse function of the above-mentioned cumulative distribution curve (fractile) with the argument equal to the random number generated in the interval 0…1 with uniform density. The domain of correct usage of this algorithm was analyzed.