Sub-micron porous niobium solid electrolytic capacitor prepared by dealloying in a metallic melt

Kim, Joung Wook; Wada, Takeshi; Kim, Sung Gyoo; Kato, Hidemi

doi:10.1016/j.matlet.2013.11.036

Cited by 35 publications

(22 citation statements)

References 17 publications

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“…The SPS processing parameters for the fabrication of the (Ti15Mo) 1–x Cu x master alloys are determined at temperature of 830 °C for holding time of 10 min under pressure of 50 MPa. The SPS temperature for the dense (TiMo)–Cu master is much lower than that of the arc‐melting method (1 700 °C) and normal powder metallurgy methods for fabricating of Ti and Ti alloys, which are always higher than 1 200 °C…”

Section: Resultsmentioning

confidence: 90%

“…The optimal dealloying parameter is at SPS temperature of 600° for holding time of 30 min to obtain pure β phased Ti15Mo foams. The dealloying temperature is much lower than the method of Mg melts (700–900 °C) . There are less than 1.0 at% Cu atoms, left in the foams after the solid state dealloying and acid etching.…”

Section: Resultsmentioning

confidence: 93%

“…The Mg melt dealloying method was accomplished by attractive interactions between Cu and Mg and repulsive interactions between Ti and Mg . They have reported the preparation of NP Nd, Fe, Cr, ferritic stainless‐steel using this Mg melt method …”

Section: Introductionmentioning

confidence: 99%

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Preparation of Nano to Submicro‐Porous TiMo Foams by Spark Plasma Sintering

Zhang

Wang

et al. 2016

Adv Eng Mater

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The nano to submicro-porous b-titanium molybdenum (TiMo) foams are prepared by dealloying of (TiMo) 1-x Cu x master alloys using a solid state dealloying method. The dealloying is performed within Mg powders by a pressureless spark plasma sintering (SPS). Experimental results show that Cu atoms in the master alloy are selectively dissolved into Mg powders during heating, the Ti and Mo atoms are spontaneously organized into homogeneous open-cell b-TiMo foams. The foams from (Ti15Mo) 40 Cu 60 alloy have BET surface area of 28.96 m 2 g -1 and pore sizes mostly in the range of 3.42 to 50 nm. The hardness and elastic modulus of the foams decrease dramatically with nanoporosities from 55.1 to 74.2%. Solid state dealloying by using pressureless SPS is promising for developing functional nanoporous (NP) Ti alloy foams.

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 93%

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Preparation of Nano to Submicro‐Porous TiMo Foams by Spark Plasma Sintering

Zhang

Wang

et al. 2016

Adv Eng Mater

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“…The challenge with electrochemically dealloyed materials is that they tend to be precious metals, whose low melting points make it difficult to make strong materials for structural applications. Kato introduced a possible solution by developing a new dealloying technique, liquid metal dealloying (LMD), which uses a molten metal as a medium to selectively dissolve one of the alloying components . Through this process, he has successfully fabricated porous Ti, Cr, Fe, Si, and Nb; however, he exclusively focused on the properties and applications of nanoporous materials.…”

Section: Methodsmentioning

confidence: 99%

Size Effects in the Mechanical Properties of Bulk Bicontinuous Ta/Cu Nanocomposites Made by Liquid Metal Dealloying

et al. 2015

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Control of microstructural length scales is central to the design and fabrication of strong and tough metals. [1][2][3] Most strengthening strategies in metals, such as precipitation hardening, grain refinement, and work hardening, uniformly control the intrinsic microstructure and generally work to inhibit dislocation motion. These methods increase the stress required to move dislocations but they also tend to lower ductility. As the physical dimensions are reduced below that of a material's internal microstructural obstacles, a number of interesting size effects come into play. For example, the strength of metallic thin films scales with the inverse of the film thickness, [4] dislocation-free whiskers are many times stronger than conventional wires, [5] the hardness of metals increases with decreasing indentation size, [6] and the compressive strength of micropillars is much greater than that measured in the bulk. [7][8][9][10] There is general recognition that dislocation activity is different in reduced volumes where interactions with free surfaces can lead to dislocation starvation, source truncation, or pileup. [11][12][13][14] Although the exact origin of size-dependent strengthening is still debated and may vary from system to system, experimental observations of smaller-is-stronger show promising new metallic materials. It is compelling to consider how to translate these kinds of mechanical responses into bulk materials.One class of bulk-nanostructured materials that exhibit size effects on their mechanical properties are dealloyed metals, for which nanoporous gold (NPG) is a model system due to its ease of fabrication. [15][16][17][18][19] NPG is made via electrochemical dealloying, immersing a Ag-rich Ag-Au parent alloy in acid, selectively dissolving away the silver atoms while leaving the gold atoms behind to diffuse along the metal/electrolyte interface, self-organizing into a porous structure with welldefined length scales (e.g., average ligament or pore diameter). [20][21][22] Dealloyed metals are porous at scales smaller than the parent alloy grain size and the dealloyed phase is a complex, 3D network of interconnected beams without any crystal defects that did not exist prior to dealloying. Indentation and micropillar compression tests show that with smaller feature size, the strength of individual NPG ligaments approach the theoretical strength of gold, but testing of bulk samples generally results in brittle failure, a feature common to most nanoporous metals (NPMs). [23,24] Weissmuller recently showed that if the pores of nanoporous gold are impregnated with a polymer, then the mechanical properties of the composite are greatly improved compared to the porous component alone, having both good strength and high plastic strain in compression. [25] The challenge with electrochemically dealloyed materials is that they tend to be precious metals, whose low melting points make it difficult to make strong materials for structural applications. Kato introduced a possible solution by developing a new ...

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“…To make this alloy more biocompatible, extensive researches for developing two-phase alloy without using V and Al [4] and also the establishing surface improvement technology are ongoing [5]. Unlike these conventional works, our approach is to utilize a dealloying method to dissolve toxic elements from an alloy by immersion into a metallic melt [6][7][8][9][10]. In this study, we apply this dealloying method to remove toxic elements from the surface of biomedical alloys and then investigate the resulting effect on the biocompatibility.…”

Section: Introductionmentioning

confidence: 99%

Surface Improvement for Biocompatibility of Ti-6Al-4V by Dealloying in Metallic Melt

Fukuzumi

Wada

Kato

2015

Interface Oral Health Science 2014

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Dealloying is known to be a powerful method to produce porous materials mainly with noble metals because the mechanism involves the selective dissolution of specific element(s) by corrosion in acid/alkali aqueous solutions. Recently, an alternative dealloying method has been developed by our research group using a metallic melt in place of the corrosive aqueous solution. In this study, using the novel dealloying method using a metallic melt, toxic Al element, was successfully removed from the surface of Ti-6Al-4V, which has been used for biomedical applications, for improving their biocompatibility. The toxic ion release from the overall sample did not effectively decrease because of the substantial surface area that developed using the dealloying method. By optimizing the dealloying conditions to suppress surface area development, drastic improvement in the biocompatibility of this Ti alloy is expected.

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Sub-micron porous niobium solid electrolytic capacitor prepared by dealloying in a metallic melt

Cited by 35 publications

References 17 publications

Preparation of Nano to Submicro‐Porous TiMo Foams by Spark Plasma Sintering

Preparation of Nano to Submicro‐Porous TiMo Foams by Spark Plasma Sintering

Size Effects in the Mechanical Properties of Bulk Bicontinuous Ta/Cu Nanocomposites Made by Liquid Metal Dealloying

Surface Improvement for Biocompatibility of Ti-6Al-4V by Dealloying in Metallic Melt

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