Download or read book An Overview on the Characterization and Mechanical Behavior of Nanoporous Gold written by J. R. Hayes and published by . This book was released on 2005 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper we present what we believe are the most pressing issues in understanding the mechanical behavior of nanoporous foams. We have postulated that a gold foam presents the best candidate for a systematic study of nanoporous foams since it can be synthesized with a wide range of ligaments sizes and densities. We have also conducted preliminary tests that demonstrate (a) Au foams have a fracture behavior dictated by the ligament size, and (b) nanoporous Au is a high yield strength material. Thus, we have demonstrated the potential in developing nanoporous foams as a new class of high yield strength/low density materials.
Download or read book Linking the Structure and Mechanical Behavior of Nanoporous Gold written by Ye Sun and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nanoporous Gold written by Arne Wittstock and published by Royal Society of Chemistry. This book was released on 2012 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book provides a broad, multidisciplinary platform to learn more about the properties of nanoporous gold from an interdisciplinary perspective from an overview of state-of-the-art applications and techniques to the latest research progress.
Download or read book Data based Analysis of Nanoporous Metals written by Claudia Richert and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, a comprehensive workflow for an FE beam modeling approach was developed, which allows to predict the macroscopic elastic and plastic mechanical behavior of nanoporous structures. An in-depth characterization of various geometrical and topological descriptors provided detailed insights about the comparability of experimental nanoporoug gold and computer-generated structures. The combination of the macroscopic mechanical predictions by FE simulations and the structural descriptors derived for the over one hundred computer-generated structures enabled to propose an improved scaling law.
Download or read book Micromechanical and Three dimensional Microstructural Characterization of Nanoporous Gold epoxy Composites written by Kaixiong Hu and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoporous gold (npg), a bicontinuous network of nanoscale gold ligaments and pores, displays tunable mechanical behavior through the variation of internal length-scales. However, it is severely limited by its lack of ductility in tension. By infiltrating the porous structure with epoxy, a composite material with enhanced tensile ductility and ow stress is achieved. The present work aims at a three-fold investigation of micromechanical behavior, mechanisms of deformation and failure of the npg-epoxy composite, focusing on 3D microstructural characterization, finite element simulation and micromechanical testing. In order to understand the composite microstructure, high resolution 3D reconstructions of the npg ligament network were achieved with focused ion beam (FIB) based tomography, taking advantage of epoxy infiltration on FIB machining of porous media. It is assumed that the infiltration of epoxy does not significantly alter the geometry of the npg network. Samples of varying structural length-scales were used, with mean ligament diameters in the range of tens to hundreds of nanometers, as achieved through isothermal annealing of npg. Quantitative analyses of the 3D reconstructions were carried out in terms of metric properties (e.g., relative density, ligament diameter distribution and specific surface area), topological properties (e.g., connectivity density), and directional properties (e.g., directional tortuosity). Importantly, representative volumes (RVs) were identified, which reflects the global structural properties of the material. It was found that npg coarsens in a nearly self-similar manner. This allows the identification of structural parameters, which can be used to describe the mechanical behavior of the global npg structure over varying length scales. FEM simulations applied to meshed RVs of the 3D reconstructions strongly suggest that the effective relative density of the load bearing ligament structure is the critical structural parameter in determining the mechanical behavior of npg structural geometry, rather than the solid relative density alone, as is often assumed. After infiltration with epoxy, the densification during deformation of npg-epoxy composites is strongly suppressed. This leads to a strongly enhanced strength compared to pure npg. However, the dependence of the yield strength on the mean ligament size is much weaker in the composite structure as compared to pure npg. The size effects in pure npg have been commonly attributed to dislocation activities within the gold ligaments, whereas in the composite material the influence of the interface on the motion of the dislocations and the epoxy chains must be considered. The interfacial behavior leads to a strengthening effect in the composites but weakens the size effects. The comparisons of the elastic moduli from the analytical models predictions, the experiments and the FEM simulations demonstrated the influences of the connectivity, the effective relative density of the load bearing ligament structure, the directional tortuosity of the ligaments and the interface on the elastic behavior of the npg-epoxy composites. Interfacial failure was experimentally observed under compression and tension. The tension-compression asymmetry investigation revealed that the npg-epoxy composite is stronger in compression than in tension. These various observations point to the important roles that the hard phase, i.e., the interconnected ligament network, the soft phase, i.e., the continuous epoxy, and the interface between them play on the mechanical behavior of npg-epoxy composites.
Download or read book Structure and Property Linkage of Nanoporous Materials written by Haomin Liu and published by . This book was released on 2021 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Nanoporous metals have recently been drawn significant interest in various fields of research. Their open-cell structure and high surface area per unit volume give them unique electrical, mechanical, and catalytic properties as well as high radiation resistance. These properties make nanoporous metals excellent candidates for a variety of high-tech applications including catalysts, biosensors, and actuators. However, the mechanical properties of nanoporous metals have not yet been well determined. Scaling relations linking the mechanical properties of nanoporous materials to their dense counterparts are found not to agree with experimental determinations. This work focuses on integrating computational simulations, continuum modeling, and deep learning techniques to gain data-driven insights about the relationships between the nanostructure and mechanical properties of nanoporous gold. We investigate the effect of structural components; ligaments and nodes on the mechanical properties of the nanoporous materials. In addition, we developed a mathematical model incorporating the bending and stretching deformation modes of ligaments to predict the stiffness of the nanoporous structure based on continuum theory. Moreover, we proposed an interpretable deep learning strategy incorporating the three-dimensional convolutional neural network and interpretation technique. This new relation is found to correctly describe the mechanical properties of nanoporous Copper (Cu)"--Page viii.
Download or read book Electrochemically Tunable Mechanical Behavior of Bulk Nanoporous Gold polypyrrole written by Jie Li and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis explores the viscoelastic modulus and actuation behavior of an electroactuator based on nanoporous gold coated with polypyrrole film (NPG/PPy). The experiments were performed using in situ dynamic mechanical analysis under electrochemical control. Novel mechanical responses of NPG/PPy hybrids have been revealed. First, during the potential sweep, a reversible change in effective elastic modulus of the NPG/PPy hybrid is observed, characterized by alternating stiffening-softening features. This non-monotonous modulus response of NPG/PPy hybrids is different from the linear modulus behavior as a function of electrode potential of non-coated NPG. Moreover, the amplitude of the modulus variations increases with PPy thickness, showing a 7-fold increase for the thickest PPy film (∼ 40 nm) coated NPG as compared to non-coated NPG. It has been suggested that the modulus behavior strongly correlates with the processes in PPy matrix during doping and dedoping of the polymer. The competition between the enhanced intermolecular bonding due to the charged polymer chains-anion interactions and softening of PPy caused by the incorporated solvent has been suggested to lead to the non-monotonous modulus behavior. Second, the actuation strains of NPG/PPy electroactuator under both potential jumps and potential sweeps have been found to be invariant under increasing applied load. The actuation strain of NPG/PPy hybrids comprises of two parts: The free stroke induced by the swelling of PPy which is independent of load and the strain caused by the stiffness variations which is load-dependent. The findings of the modulus behavior mentioned above help to distinguish the strain contributions of these two factors to the total strain. These experiments allow evaluating a contribution of the electrochemically modulated elastic modulus of NPG/PPy to the actuation strain. Depending on the predeformation of the material as well as on the oxidation or reduction state of PPy, this contribution adds an expansion or contraction to the actuation strain. Yet, in the range of the applied loads tested, the actual performance is not affected by the load, demonstrating an enhanced load-bearing efficiency of NPG/PPy electroactuators in contrast to non-coated NPG.
Download or read book Characterization and Evaluation of a Novel Nanoporous Gold Biosensor Substrate written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Dilute but powerful biological markers, such as hormones in blood stream, are potent but difficult to detect quickly and accurately using current biosensor technologies. Nanoporous structures offer greatly increased surface area which can be functionalized for use as a biosensor, amplifying throughput and the enhancing the ability to detect small concentrations. With the option for diverse component materials and conformations, a sensor with prescribed properties could be easily incorporated into devices for clinical diagnosis or research applications. This study evaluates the suitability of a nanoporous gold (NPG) wire for use as a biosensing component as a proof of concept through the detailed characterization of the porosity, structural support, and electrical properties of the wires. The nanoporous gold wires were created using electrochemical etching equipment. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) were used to image and evaluate the pores and effectiveness of the etching procedure. Pores were found to be 9.86 Ã'Â" 4.92 Ã'Âæm in diameter with a density of 880 pores/Ã'Âæm2 and only 5% silver remained following etching procedures. The storage capacity of the nanoporous wire annealed to a gold support structure at 15.6 mF/cm, was found to be higher than that of unsupported wires at 10.6 mF/cm. Structurally supported NPG wires also demonstrated a lower resistance (4.2Ω compared to 13.4Ω) owing to the capacitance of the nonporous gold support structure at high frequencies. Wires annealed to a gold support structure demonstrated greater mechanical stability and generally more consistent electrical properties. Samples were found highly susceptible to fracture and any coatings vulnerable to denaturing with extensive transport, handling, and testing. Some cross-contamination of samples was detected. Most contamination effects were minimal and confined to materials used in the manufacturing process. Future investigation s.
Download or read book Nanoporous Gold Characterization Structural Modification and Use as a Solid Support for Biomolecule Immobilization written by Abeera Sharma and published by . This book was released on 2014 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoporous gold (NPG) has immense technological applications owing to a plethora of properties like large surface area to volume ratio, plasmonic properties, stable gold-thiolate bond formation and a wide range of pore sizes. The surface morphology of nanoporous gold has been altered previously by dealloying and thermal annealing to increase/decrease the pore size and change the surface area. We provide a novel electrochemical annealing technique for post dealloying modification wherein electrochemical sweep cycles in different electrolytes at positive potentials leads to a subsequent increase in pore sizes of nanoporous gold as studied using scanning electron microscopy. Tailoring the surface of nanoporous gold allows us to characterize and study self-assembled monolayers of alkanethiols, including those terminated by carbohydrate moieties. The orientation of these thiols on nanoporous gold is not uniform due to the interconnected framework of pores and ligaments and we try to offer a fair comparison between flat gold and nanoporous gold to determine the surface coverage of these self-assembled monolayers. Carbohydrate-lectin interactions have been studied with the help of dendrimers as linkers. Dendrimers (polyamidoamine generation 4 and 5) have been used as linkers due to their multivalent interactions with carbohydrate moieties and impedance spectroscopy as well as atomic force microscopy techniques have been utilized to study dendrimers attached on nanoporous gold surface using covalent immobilization. This study aims at providing a comprehensive surface property analysis of nanoporous gold.
Download or read book TMS 2012 141st Annual Meeting and Exhibition Materials Properties Characterization and Modeling written by The Minerals, Metals & Materials Society (TMS) and published by John Wiley & Sons. This book was released on 2012-05-15 with total page 909 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains chapters on cutting-edge developments presented at the TMS annual conference of 2012.
Download or read book Handbook of Research on Advancements in the Processing Characterization and Application of Lightweight Materials written by Kumar, Kaushik and published by IGI Global. This book was released on 2021-11-19 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the automotive industry, the need to reduce vehicle weight has given rise to extensive research efforts to develop aluminum and magnesium alloys for structural car body parts. In aerospace, the move toward composite airframe structures urged an increased use of formable titanium alloys. In steel research, there are ongoing efforts to design novel damage-controlled forming processes for a new generation of efficient and reliable lightweight steel components. All these materials, and more, constitute today’s research mission for lightweight structures. They provide a fertile materials science research field aiming to achieve a better understanding of the interplay between industrial processing, microstructure development, and the resulting material properties. The Handbook of Research on Advancements in the Processing, Characterization, and Application of Lightweight Materials provides the recent advancements in the lightweight mat materials processing, manufacturing, and characterization. This book identifies the need for modern tools and techniques for designing lightweight materials and addresses multidisciplinary approaches for applying their use. Covering topics such as numerical optimization, fatigue characterization, and process evaluation, this text is an essential resource for materials engineers, manufacturers, practitioners, engineers, academicians, chief research officers, researchers, students, and vice presidents of research in government, industry, and academia.
Download or read book Microfabrication and Characterization of Nanoporous Gold Structures written by Erkin Şeker and published by . This book was released on 2007 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation reports on the underlying mechanisms of stress and morphology evolution during and after dealloying with respect to annealing temperatures for structures with various geometric constraints. Understanding the fundamental mechanisms that lead to morphology and stress-state evolution via dealloying and thermal treatment will be valuable in developing applications incorporating np-Au in sensors and actuators. In addition, an interesting wetting equilibrium observed during the fabrication experiments will be described. This phenomenon was later utilized for the development of a composite np-Au and silicon elastomer. The synthesis and applications of this material will be outlined. Finally, implications for future studies and applications will be discussed.
Download or read book Microscopic Failure Behavior of Nanoporous Gold written by and published by . This book was released on 2005 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nanoporous metals have recently attracted considerable interest fueled by potential sensor and actuator applications. One of the key issues in this context is the synthesis of high yield strength materials. Nanoporous Au (np-Au) has been suggested as a candidate due to its monolithic character. The material can be synthesized by dealloying Ag-Au alloys, and exhibits an open sponge-like morphology of interconnecting Au ligaments with a typical pore size distribution on the nanometer length scale. Unfortunately, very little is known about the mechanical properties of np-Au besides a length-scale dependent ductile-brittle transition. A key question in this context is: what causes the macroscopic brittleness of np-Au? Is the normal dislocation-mediated plastic deformation suppressed in nanoscale Au ligaments, or is the brittleness a consequence of the macroscopic morphology? Here, we report on the fracture behavior of nanoporous Au studied by scanning electron microscopy. Specifically, we demonstrate the microscopic ductility of nanometer-sized Au ligaments. The observed fracture behavior seems to be general for nanoporous metals, and can be understood in terms of simple fuse networks.
Download or read book Physical Metallurgy written by David E. Laughlin and published by Newnes. This book was released on 2014-07-24 with total page 2963 pages. Available in PDF, EPUB and Kindle. Book excerpt: This fifth edition of the highly regarded family of titles that first published in 1965 is now a three-volume set and over 3,000 pages. All chapters have been revised and expanded, either by the fourth edition authors alone or jointly with new co-authors. Chapters have been added on the physical metallurgy of light alloys, the physical metallurgy of titanium alloys, atom probe field ion microscopy, computational metallurgy, and orientational imaging microscopy. The books incorporate the latest experimental research results and theoretical insights. Several thousand citations to the research and review literature are included. - Exhaustively synthesizes the pertinent, contemporary developments within physical metallurgy so scientists have authoritative information at their fingertips - Replaces existing articles and monographs with a single, complete solution - Enables metallurgists to predict changes and create novel alloys and processes
Download or read book Mineral Surface Reactions at the Nanoscale written by Christine V. Putnis and published by MDPI. This book was released on 2019-05-20 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reactions at mineral surfaces are central to all geochemical processes. As minerals comprise the rocks of the Earth, the processes occurring at the mineral–aqueous fluid interface control the evolution of the rocks and hence the structure of the crust of the Earth during processes such as metamorphism, metasomatism, and weathering. In recent years focus has been concentrated on mineral surface reactions made possible through the development of advanced analytical methods such as atomic force microscopy (AFM), advanced electron microscopies (SEM and TEM), phase shift interferometry, confocal Raman spectroscopy, and advanced synchrotron-based applications, to enable mineral surfaces to be imaged and analyzed at the nanoscale. Experiments are increasingly complemented by molecular simulations to confirm or predict the results of these studies. This has enabled new and exciting possibilities to elucidate the mechanisms that govern mineral–fluid reactions. In this Special Issue, “Mineral Surface Reactions at the Nanoscale”, we present 12 contributions that highlight the role and importance of mineral surfaces in varying fields of research.
Download or read book TMS 2012 141st Annual Meeting and Exhibition Materials Processing and Interfaces written by The Minerals, Metals & Materials Society (TMS) and published by John Wiley & Sons. This book was released on 2012-05-02 with total page 1046 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contains papers relating to materials processing andinterfaces presented at various symposia at the 2012 TMSAnnual Meeting.
Download or read book Nanoporous Metals for Advanced Energy Technologies written by Yi Ding and published by Springer. This book was released on 2016-03-19 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the state-of-the-art research in nanoporous metals for potential applications in advanced energy fields, including proton exchange membrane fuel cells, Li batteries (Li ion, Li-S, and Li-O2), and supercapacitors. The related structural design and performance of nanoporous metals as well as possible mechanisms and challenges are fully addressed. The formation mechanisms of nanoporous metals during dealloying, the microstructures of nanoporous metals and characterization methods, as well as miscrostructural regulation of nanoporous metals through alloy design of precursors and surface diffusion control are also covered in detail. This is an ideal book for researchers, engineers, graduate students, and government/industry officers who are in charge of R&D investments and strategy related to energy technologies.
