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Jean-françois Silvain - One of the best experts on this subject based on the ideXlab platform.
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Solid-liquid co-existent phase process: towards fully dense and thermally efficient Cu/C composite materials
Journal of Alloys and Compounds, 2018Co-Authors: Clio Azina, Jerome Roger, Anne Joulain, Vincent Mauchamp, Bruno Mortaigne, Yongfeng Lu, Jean-françois SilvainAbstract:Metal matrix composites are currently being investigated for thermal management applications. In the case of a copper/carbon (Cu/C) composite system, a particular issue is the lack of affinity between the Cu matrix and the C reinforcements. Titanium-alloyed Cu (Cu-Ti) powders were introduced in a Cu/C powder mixture and sintered under load at a temperature at which the Cu-Ti powders became liquid, while the rest of the Cu and C remained solid. Fully dense materials were obtained (porosity of less than 5%). The creation of regular and homogeneous Interphases was confirmed. All Ti reacted with the carbon, hence purifying the Cu matrix. Thermal conductivities were enhanced as compared with the Cu/C composites without Interphase. The chemical analyses are in agreement with thermodynamic simulations carried out to predict the phase transformation during the sintering process.
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Relationship between Interphase chemistry and mechanical properties at the scale of micron in Cu–Cr/CF composite
Acta Materialia, 2011Co-Authors: Amélie Veillere, Aravind Sundaramurthy, Jean-marc Heintz, Michel Lahaye, Joël Douin, Namas Chandra, Susan Enders, Jean-françois SilvainAbstract:The properties of a composite material are determined not only by the constitutive properties of the matrix and the reinforcement, but also by the type and nature of interfacial bonding between them. For thermo-mechanical applications, the influence of interfaces and Interphases is fundamental. In this work, we comprehensively study the copper alloy/carbon fiber composite material interfaces, with and without Interphases, in terms of microstructural and chemical properties at the micro- and nanometric scales. These properties are then correlated with the local mechanical properties as determined by nanoindentation, enabling us to establish a direct relationship between the chemistry and mechanical properties at the microscale. In addition to experimental measurements, three-dimensional finite element simulations are performed on the matrix/Interphase/reinforcement system, and the results between experiments and simulations show very good agreement, validating our basic hypothesis that the local mechanical properties are determined by the material chemistry.
Gregory N. Morscher - One of the best experts on this subject based on the ideXlab platform.
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Effect of a BN Interphase that Debonds Between the Interphase and the Matrix In SiC/SiC Composites
2013Co-Authors: Linus Thomas-ogbuji, Gregory N. Morscher, James A. Dicarlo, Hee Mann YunAbstract:Typically, the debonding and sliding interface enabling fiber pullout for silicon-carbide fiber-reinforced silicon-carbide matrix composites with BN-based Interphases occurs between the fiber and the Interphase. Recently, composites have been fabricated where interface debonding and sliding occurs between the BN Interphase and the matrix. This results in two major improvements in mechanical properties. First, significantly higher failure strains were attained due to the lower interfacial shear strength with no real loss in ultimate strength properties of the composites. Second, significantly longer stress-rupture times at higher stresses were observed in air at 815 C. In addition, no real loss in mechanical properties was observed for composites that did not possess a thin carbon layer between the fiber and the Interphase when subjected to burner-rig exposure. Outside debonding is hypothesized to be due to two primary factors: a weaker interface at the BN/matrix interface than the fiber BN interface and a residual tensile/shear stress-state at the interface of melt-infiltrated composites. Also, the occurrence of outside debonding was believed to occur during composite fabrication, i.e., on cool down after molten silicon infiltration.
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Effect of a Boron Nitride Interphase That Debonds between the Interphase and the Matrix in SiC/SiC Composites
Journal of the American Ceramic Society, 2008Co-Authors: Gregory N. Morscher, Hee Mann Yun, James A. Dicarlo, Linus Thomas-ogbujiAbstract:Typically, the debonding and sliding interface enabling fiber pullout for SiC-fiber-reinforced SiC-matrix composites with BN-based Interphases occurs between the fiber and the Interphase. Recently, composites have been fabricated where interface debonding and sliding occur between the BN Interphase and the matrix. This results in two major improvements in mechanical properties. First, significantly higher failure strains were attained due to the lower interfacial shear strength with no loss in ultimate strength properties of the composites. Second, significantly longer stress-rupture times at higher stresses were observed in air at 815°3C. In addition, no loss in mechanical properties was observed for composites that did not possess a thin carbon layer between the fiber and the Interphase when subjected to burner-rig exposure. Two primary factors were hypothesized for the occurrence of debonding and sliding between the BN Interphase and the SiC matrix: a weaker interface at the BN/matrix interface than the fiber/BN interface and a residual tensile/shear stress-state at the BN/matrix interface of melt-infiltrated composites. Also, the occurrence of outside debonding was believed to occur during composite fabrication, i.e., on cooldown after molten silicon infiltration.
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tensile stress rupture of sicf sicmminicomposites with carbon and boron nitride Interphases at elevated temperatures in air
Journal of the American Ceramic Society, 2005Co-Authors: Gregory N. MorscherAbstract:The stress-rupture properties of precracked minicomposites were determined in air at temperatures in the range of 700--1,200 C. The minicomposite systems consisted of a single tow of Nicalon or Hi-Nicalon fibers with carbon or boron nitride (BN) Interphases and a chemical-vapor-infiltrated silicon carbide (CVI-SiC) matrix. The stress-rupture results were compared to single-fiber stress-rupture data and composite data in the literature. Severe embrittlement occurred for carbon Interphase minicomposites. However, BN Interphase minicomposites showed only mild degradation in the rupture properties. This was true even though the BN Interphase reacted and vaporized because of water vapor in the atmosphere at intermediate temperatures (700--950 C) and glass formation occurred at higher temperatures (950--1,200 C). The severe degradation in rupture properties that occurred for carbon Interphase composites at intermediate temperatures was due to degradation of the Nicalon-fiber properties from the environment. The rupture properties of the BN-Interphase minicomposites were controlled by the fiber rupture properties at temperatures of less than {approximately}900 C and greater than {approximately}1,100 C. In the range of {approximately}900--1,100 C, most fibers fused to the matrix because of a glass layer that formed between the fiber and matrix, resulting in fiber stress concentrations that led to the mild embrittlement of themore » BN-Interphase minicomposites.« less
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Intermediate Temperature Strength Degradation in SiC/SiC Composites
Journal of The European Ceramic Society, 2002Co-Authors: Gregory N. Morscher, James D. CawleyAbstract:Abstract Woven silicon carbide fiber-reinforced, silicon carbide matrix composites are leading candidate materials for an advanced jet engine combustor liner application. Although the use temperature in the hot region for this application is expected to exceed 1200 °C, a potential life-limiting concern for this composite system exists at intermediate temperatures (800±200 °C), where significant time-dependent strength degradation has been observed under stress-rupture loading. A number of factors control the degree of stress-rupture strength degradation, the major factor being the nature of the Interphase separating the fiber and the matrix. BN Interphases are superior to carbon Interphases due to the slower oxidation kinetics of BN. A model for the intermediate temperature stress-rupture of SiC/BN/SiC composites is presented based on the observed mechanistic process that leads to strength degradation for the simple case of through-thickness matrix cracks. The approach taken has much in common with that used by Curtin and coworkers, for two different composite systems. The predictions of the model are in good agreement with the rupture data for stress-rupture of both precracked and as-produced composites. Also, three approaches that dramatically improve the intermediate temperature stress-rupture properties are described: Si-doped BN, fiber spreading, and “outside debonding”.
Mb Rubin - One of the best experts on this subject based on the ideXlab platform.
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A nonlinear Cosserat Interphase model for residual stresses in an inclusion and the Interphase that bonds it to an infinite matrix
International Journal of Solids and Structures, 2015Co-Authors: Hai Dong, J Wang, Mb RubinAbstract:Abstract Residual stresses in inclusions and Interphases that are bonded to a matrix can significantly influence the response of composite materials to additional mechanical loads. These residual stresses are modeled by considering the nonlinear 2-phase problem of an inclusion that is bonded to a hollow spherical Interphase with an internal unstressed radius that is different from the outer unstressed radius of the inclusion and with a traction-free outer deformed surface. The resulting macro-inclusion (i.e. the prestressed inclusion and Interphase) is then embedded into a stress-free matrix. The linear equations for small deformations superimposed on this large deformation problem are developed and solved to study the influence of the residual stresses on the response of the 3-phase system of inclusion–Interphase–matrix to external mechanical loads. The results of this solution indicate that this residual stress problem is essentially nonlinear and must be modeled directly by including the influence of coupled terms associated with products of the residual stresses and displacements.
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Reciprocal theorem for a linear elastic Cosserat Interphase with general geometry
Mathematics and Mechanics of Solids, 2014Co-Authors: Mb RubinAbstract:Interphases in heterogeneous media are typically thin regions, such as coatings on inclusions bonded to matrixes. These Interphases are modeled with approximate equations that connect fields on both surfaces of the Interphase. The theory of a Cosserat surface is a special continuum theory that models the response of thin structures. Cosserat Interphase models based on this theory provide unified equations that are valid for the entire range of material parameters of the inclusion, Interphase and matrix. Since the balance laws for these Cosserat Interphases are global integral equations, the theory inherits many of the fundamental properties of the exact three-dimensional theory. Here, it is shown that the Cosserat Interphase model for linear elasticity also satisfies a global form of the reciprocal theorem.
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cosserat Interphase models for elasticity with application to the Interphase bonding a spherical inclusion to an infinite matrix
International Journal of Solids and Structures, 2014Co-Authors: Hai Dong, J Wang, Mb RubinAbstract:Abstract Interphases are often modeled as interfaces with zero thickness using jump conditions that can be developed based on approximate shell or membrane models which are valid for specific limited ranges of the elastic material parameters. For a two-dimensional problem it has been shown (Rubin and Benveniste, 2004) that the Cosserat model of a finite thickness Interphase is a unified model that is accurate over the full range of elastic parameters. In contrast, many other Interphase models are valid for only limited ranges of the elastic parameters. In this paper, the accuracy of different Cosserat models of a finite thickness Interphase that connects a spherical inclusion to an infinite matrix is examined. Specifically, four Cosserat Interphase models are considered: a general shell ( GS ) , a membrane-like shell ( MS ) , a simple shell ( SS ) and a generalized membrane ( GM ) . The models ( GS ) and ( MS ) both satisfy restrictions on the strain energy function of the Interphase that ensure exact solutions for all homogeneous three-dimensional deformations, while the other models ( SS ) and ( GM ) do not satisfy these restrictions. The importance of these restrictions is examined for the three-dimensional inhomogeneous inclusion problem being considered. This is the first test of the accuracy of an elastic Interphase model for a spherical Interphase.
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A Cosserat shell model for Interphases in elastic media
Journal of The Mechanics and Physics of Solids, 2004Co-Authors: Mb Rubin, Y. BenvenisteAbstract:Abstract This study is concerned with the modeling of Interphases in elastic media in general, and in composite materials in particular. The aim is to replace a boundary value problem consisting of a three-phase configuration, say that of fiber–Interphase–matrix, by a simpler problem which involves the fiber and matrix only, plus certain matching conditions which simulate the Interphase. The simplest of such known representations replaces a thin Interphase by a “perfect contact interface” (a single surface) across which the displacements and tractions are assumed to be continuous. Another classical model replaces a thin and soft Interphase by a “spring-type interface”, across which the tractions are continuous, but the displacement field undergoes a discontinuity. In the present paper, a Cosserat shell model of the Interphase is derived which successfully models the original Interphase in a unified manner, for the full range of its material parameters relative to those of the neighboring media. The model is derived in the setting of three-dimensional linear elasticity with small deformations and displacements. Comparisons with an existing exact solution of a coated fiber in an infinite matrix show that it performs extremely well even for moderately thick Interphases.
Jean-françois Gérard - One of the best experts on this subject based on the ideXlab platform.
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Self-Healable Interfaces Based on thermo-reversible Diels-Alder Reactions in Carbon Fiber Reinforced Composites
Journal of Colloid and Interface Science, 2014Co-Authors: W Zhang, Jannick Duchet-rumeau, Jean-françois GérardAbstract:Thermo-reversible Diels-Alder (DA) bonds formed between maleimide and furan groups have been used to generate an Interphase between carbon fiber surface and an epoxy matrix leading to the ability of interfacial self-healing in carbon:epoxy composite materials. The maleimide groups were grafted on an untreated T700 carbon fiber from a three step surface treatment: (i) nitric acid oxidization, (ii) tetraethylenepentamine amination, and (iii) bismaleimide grafting. The furan groups were introduced in the reactive epoxy system from furfuryl glycidyl ether. The interface between untreated carbon fiber and epoxy matrix was considered as a reference. The interfacial shear strength (IFSS) was evaluated by single fiber micro-debonding test. The debonding force was shown to have a linear dependence with embedded length. The highest healing efficiency calculated from the debonding force was found to be about 82% more compared to the value for the reference interface. All the Interphases designed with reversible DA bonds have a repeatable self-healing ability. As after the fourth healing, they can recover a relatively high healing efficiency (58% for the Interphase formed by T700-BMI which is oxidized for 60 min during the first treatment step).
Kang Xu - One of the best experts on this subject based on the ideXlab platform.
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An artificial Interphase enables reversible magnesium chemistry in carbonate electrolytes
Nature Chemistry, 2018Co-Authors: Steve P. Harvey, Chunsheng Wang, Arthu V Cresce, K. Xerxes Steirer, Adam Stokes, Andrew Norman, Kang XuAbstract:Mg-based batteries possess potential advantages over their lithium counterparts; however, the use of reversible oxidation-resistant, carbonate-based electrolytes has been hindered because of their undesirable electrochemical reduction reactions. Now, by engineering a Mg^2+-conductive artificial Interphase on a Mg electrode surface, which prevents such reactivity, highly reversible Mg deposition/stripping in carbonate-based electrolytes has been demonstrated. Magnesium-based batteries possess potential advantages over their lithium counterparts. However, reversible Mg chemistry requires a thermodynamically stable electrolyte at low potential, which is usually achieved with corrosive components and at the expense of stability against oxidation. In lithium-ion batteries the conflict between the cathodic and anodic stabilities of the electrolytes is resolved by forming an anode Interphase that shields the electrolyte from being reduced. This strategy cannot be applied to Mg batteries because divalent Mg^2+ cannot penetrate such Interphases. Here, we engineer an artificial Mg^2+-conductive Interphase on the Mg anode surface, which successfully decouples the anodic and cathodic requirements for electrolytes and demonstrate highly reversible Mg chemistry in oxidation-resistant electrolytes. The artificial Interphase enables the reversible cycling of a Mg/V_2O_5 full-cell in the water-containing, carbonate-based electrolyte. This approach provides a new avenue not only for Mg but also for other multivalent-cation batteries facing the same problems, taking a step towards their use in energy-storage applications.
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Interphases in Sodium‐Ion Batteries
Advanced Energy Materials, 2018Co-Authors: Junhua Song, Kang Xu, Biwei Xiao, Yuehe Lin, Xiaolin LiAbstract:Sodium-ion batteries (SIBs) as economical, high energy alternatives to lithium-ion batteries (LIBs) have received significant attention for large-scale energy storage in the last few years. While the efforts of developing SIBs have benefited from the knowledge learned in LIBs, thanks to the apparent proximity between Na-ions and Li-ions, the unique physical and chemical properties of Na-ions also distinctly differ themselves from Li-ions. It is expected that SIBs have drastically different electrode material structure, solvation–desolvation behavior, electrode–electrolyte Interphase stabilities, ion transfer properties, and hence electrochemical performance of batteries. In this review, the authors comprehensively summarize the current understanding of the anode solid electrolyte Interphase and cathode electrolyte Interphase in SIBs, with an emphasis on how the tuning of the stability and ion transfer properties of Interphases fundamentally determines the reversibility and efficiency of electrochemical reactions. Through these carefully screened references, the authors intend to reveal the intrinsic correlation between the properties/functionalities of the Interphases and the electrochemical performance of batteries.
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Lithium-Ion Batteries and Materials
Springer Handbook of Electrochemical Energy, 2017Co-Authors: Cynthia A. Lundgren, Jan L. Allen, Kang Xu, Sheng S ZhangAbstract:Lithium-ion (Li-ion) batteries are now widely implemented as the power or energy source for everything from portable electronics to electric vehicles. The electrochemical charge storage in the batteries is intimately related to their material properties. This chapter gives an overview of the methods for characterizing battery materials, both ex situ and in situ in practical cells. An important consideration is the Interphase between the active charge storage materials and the electrolyte, often called the secondary electrolyte Interphase (SEI ) layer. Different methodologies unlock different aspects of the battery materials and Interphases. Standard test methods are summarized as well as emerging methodologies. Next generation Li-ion batteries, such as Li-sulfur and Li-air are also described.
