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Showing 1 to 20 of 21 for “"dealloying"”.
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In situ investigation of the dealloying process using environmental transmission electron microscopy
Dealloying is a corrosion process where a constituent of a metal alloy selectively dissolves out of the host metal, leaving behind a porous network. The process is thought to proceed by either surface diffusion or bulk diffusion. While the process has been studied extensively in the past, it was …
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The Effect of Lead on Dealloying and Stress Corrosion Cracking (SCC) of Ni-Cr-Fe Alloys in Boiling Caustic Environments
… (135-140 °C) in reducing conditions to study dealloying. Flat samples were used for electrochemical measurements, and SS 316L was used in some tests to evaluate the effect of Mo addition and subtle changes in Ni content. Twisted and U-bend samples of SS 304L were used to evaluate the effect of …
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Nanoporosity Formation in Ag-Au Alloys
Selective dissolution also known as dealloying is a corrosion process in which one component of a binary alloy system is selectively removed through an electrochemically controlled process which leads to the formation of a porous metal "sponge" with a porosity that is completely interconnected and …
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EFFECTS OF SIZE AND COMPOSITION ON THE PERFORMANCE OF DEALLOYED NANOPOROUS METAL CATALYSTS FOR CO2 REDUCTION, O2 EVOLUTION, AND H2 GENERATION
… problem (1) by introducing several alternative dealloying routes, namely synthesis of noble nanoporous metals such as nanoporous gold under mild conditions by engineering the reaction pathway, and synthesis of more chemically reactive nanoporous metals including nanoporous zinc and nanoporous …
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Nanoporous Gold: Mechanics of Fabrication and Actuation
… and complex surface reconstruction during dealloying potentially leads to a high overall stress in the newly forming NPG. Hence, constrained NPG thin films or suspended NPG structures often develop cracks in fabrication. Similarly, nanovoids in thin film precursor alloys or low Au content …
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An investigation of corrosion mechanisms of constructional alloys in supercritical water oxidation (SCWO) systems
… with a constant pressure of 24.1MPa. Dealloying of Ni and Fe, and oxidation of Cr and Mo are observed at subcritical temperatures at a pH value of 2. At a pH value of 1, even chromium is selectively dissolved and only molybdenum forms a stable oxide at the subcritical temperature. At …
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Experimental and ab initio investigations into the fundamentals of corrosion, in the context of supercritical water oxidation systems
… analysis and controlled exposure experiments. Dealloying and intergranular corrosion were observed. Dealloying rate was found to be strongly correlated with temperature and dielectric constant. Intergranular corrosion behavior was found to be affected by the alloy hardness. In order to …
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Degradation Mechanisms of Copper and Copper Alloys
… typical journal article format. A mechanism for dealloying and intergranular attack of Monel 400, a Ni-Cu alloy used as a steam generator tubing material, is proposed. Dealloying of Monel is contingent on the accumulation of Cu2+, which stabilizes metallic copper. This is achieved in the nuclear …
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Bimetallic Nanoporous Sponges
… of np-S thin films and bulk structures using the dealloying method. Ag-Al alloy precursors with varying aluminium content (24.6–72.6 at.%) were sputter-deposited as thin films and dealloyed in NaOH, resulting in a ligament-pore structure. Smaller ligament sizes (13 nm) increased electron …
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Nanoporous Platinum
Dealloying is a corrosion process in which one or more elements are selectively removed from an alloy leading to a 3-dimensional porous structure of the more noble element(s). These porous structures have been known to cause stress corrosion cracking in noble metal alloy systems but more recent …
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Materials with engineered mesoporosity for programmed mass transport
… using a colloidal crystal template and the dealloying of silver from gold and possed porosity on length scales range from 10s of nanometers (due to the colloidal crystal template) down to ca. 10 nm (due to dealloying). The transport properties of the material were studied using cyclic …
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A comparative study of PtCo/C Alloys and Pt/C as cathode catalysts for fuel cell applications
… before and after activation by electrochemical dealloying. Structural changes occurring during these processes have been characterised using cyclic voltammetry, Transmission Electron Microscopy (TEM) and X-ray absorption spectroscopy (XAS).<br/><br/>XAS has also been used to explore the …
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Investigating the origin of localized plastic deformation in nanoporous gold by in situ electron microscopy and automatic structure quantification
… varying numerous processing factors such as dealloying time, annealing time, and mechanical agitation. Through the expanded scope of synthesis experiments and detailed analysis, it was discovered that the curvature of the ligaments and the distribution width of ligament diameters could be …
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Surface Oxidation and Dissolution of Metal Nanocatalysts in Acid Medium
… code is developed to study the degradation and dealloying in nanocatalysts. The results on the degradation of Pt nanoparticles under different potential regimes demonstrate that the dissolution depends on the potential path to which the nanocatalyst is exposed. Metal atoms detach from the …
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Electrochemical Synthesis and Characterisation of Multimetallic Nanostructured Electrocatalysts
… overpotentially-deposited copper, potentiostatic dealloying, direct spontaneous deposition of noble metals (without intermediary steps involving redox-replacement templating reactions) as well as sequential codeposition of noble metals (with or without SLRR templating reactions). Fundamental …
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Mechanisms of Liquid-Metal-Activated Aluminum-Water Reactions and Their Application
… (i.e. deionized water, 1 bar, 100 degC) due to dealloying of the gallium and indium at the microscale. It was then discovered that in ionic aqueous solutions, liquid-phase eGaIn emerges from solution under specific ambient conditions. From this discovery, a method for recovering and recycling …
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Ultrasound-driven formation of porous metals for catalysis
… Gegensatz zum konventionellen, durch chemisches Dealloying, hergestelltes „Raney®-Nickel“, ist dieses Material nicht pyrophor. Aufbauend auf den positiven Erfahrungen mit der Al/Ni-Legierung wurde eine Aluminum/Kupfer-Legierung im eigenen Labor hergestellt. Diese wurde durch Ultraschallbehandlung …
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Design and Mechanism Study of Electrocatalysts for Alkaline Hydrogen Evolution
… the unusual performance of these samples is that dealloying can selectively optimize the H and OH binding energy on Pt sites, promoting the overall activity. Secondly, well-defined RuPt alloy and core-shell (Ru@Pt) nanoparticles were studied to demonstrate the contribution of the electronic and …
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Stability of Nanoporous Metals
A study of the stability of bicontinuous nanoporous metals is presented. Atomic scale simulations are used to probe the dominant mechanisms of geometric relaxation in these materials. A method is presented for generating model bicontinuous metal / void structures for use in atomistic simulations of …
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