Controlled fabrication of porous metals from the nanometer to the macroscopic scale

Kränzlin, Niklaus; Niederberger, Markus

doi:10.1039/c4mh00244j

Cited by 75 publications

(50 citation statements)

References 111 publications

(177 reference statements)

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“…[15b,93] It includes the sequential deposition of oppositely charged building blocks. [100] In contrast to the ceramic foams discussed above, where sintering leads to coalescence of the particles, nanoparticlebased aerogels are macroscopic bodies, in which the properties of the initial building blocks are still preserved. Kotov and co-workers reported the synthesis of self-standing films of gold nanoparticles in polyurethane.…”

Section: From Nano To Macro: Assembly and Colloidal Processing Over Smentioning

confidence: 99%

“…However, there are many other ways to fabricate porous metal pieces of macroscopic sizes. [100] In contrast to the ceramic foams discussed above, where sintering leads to coalescence of the particles, nanoparticlebased aerogels are macroscopic bodies, in which the properties of the initial building blocks are still preserved. But similar to foaming, during gelation the surface chemistry of the nanoparticles plays a decisive role.…”

Section: From Nano To Macro: Assembly and Colloidal Processing Over Smentioning

confidence: 99%

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Multiscale Nanoparticle Assembly: From Particulate Precise Manufacturing to Colloidal Processing

Niederberger

2017

Adv Funct Materials

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Nanoparticle assembly and colloidal processing are two techniques with the goal to fabricate materials and devices from preformed particles. While colloidal processing has become an integral part of ceramic processing, nanoparticle assembly is still mainly limited to academic interests. It typically starts with the precise synthesis of building blocks, which are generally not only considerably smaller than those used for colloidal processing, but also better defined in terms of size, shape, and size distribution. Their arrangement into 1D, 2D, and 3D architectures is performed with great accuracy well beyond what is achieved by colloidal processing. At the same time, the final assembly is not sintered such that the intrinsic, nanospecific properties of the initial building blocks are preserved or even lead to collective behavior. However, in contrast to colloidal processing the structures accessible by nanoparticle assembly are often limited to a small length scale. The review presents selected examples of nanoparticle assembly and colloidal processing with the goal to reveal the capabilities of these two techniques to fabricate novel materials from preformed building blocks, and also to demonstrate the immense opportunities that would arise if the two methods could be combined with each other.

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Section: From Nano To Macro: Assembly and Colloidal Processing Over Smentioning

confidence: 99%

Section: From Nano To Macro: Assembly and Colloidal Processing Over Smentioning

confidence: 99%

Multiscale Nanoparticle Assembly: From Particulate Precise Manufacturing to Colloidal Processing

Niederberger

2017

Adv Funct Materials

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“…The variety of available core designs and numerous material options allows for the optimization of these metal cellular structures for applications in the aerospace and automotive industry. [14,21] When evaluating the mechanical properties of stochastic and periodic structures, one finds that for a given relative density, ordered porous structures have superior load-bearing properties when compared to their stochastic counterparts. [14,15,20] Each category is associated with distinct mechanical properties as well as differences in relative density and production effort or cost.…”

Section: Materials With Multiple Length Scales Stochastic Versus Permentioning

confidence: 99%

“…For instance, the latter implies permeability to fluids, typically along with a lower density. [14,21] When evaluating the mechanical properties of stochastic and periodic structures, one finds that for a given relative density, ordered porous structures have superior load-bearing properties when compared to their stochastic counterparts. [22] Figure 1.…”

Section: Materials With Multiple Length Scales Stochastic Versus Permentioning

confidence: 99%

Nanoporous Metals with Structural Hierarchy: A Review

et al. 2017

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Nanoporous (np) metals have generated much interest since they combine several desirable material characteristics, such as high surface area, mechanical size effects, and high conductivity. Most of the research has been focused on np Au due to its relatively straightforward synthesis, chemical stability, and many promising applications in the fields of catalysis and actuation. Other materials, such as np-Cu, Ag, and Pd have also been studied. This review discusses recent advances in the field of np metals, focusing on new research areas that implement and leverage structural hierarchy while using np metals as their base structural constituents. First, we focus on single-element porous metals that are made of np metals at the fundamental level, but synthesized with additional levels of porosity. Second, we discuss the fabrication of composite structures, which use auxiliary materials to enhance the properties of np metals. Important applications of these hierarchical materials, especially in the fields of catalysis and electrochemistry, are also reviewed. Finally, we conclude with a discussion about future opportunities for the advancement and application of np metals.

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“…Uno de los métodos más usados para preparar esponjas metálicas por pulvimetalurgia emplea forma-dores de poros [4,5]. Se eligen partículas de algún material y se recubren con el metal en polvo.…”

Section: Introductionunclassified

Fabricación de espumas de cobre por pulvimetalurgia

et al. 2018

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RESUMENSe presenta un método de fabricación de esponjas de cobre por pulvimetalurgia, empleando perlas de urea como formadores de poros que son removidas por disolución en agua antes de sinterizar el compacto. Este método permite un control preciso de las características de las celdas (tamaño, forma y distribución), obteniéndose una porosidad de celdas interconectadas. El empleo de metales en polvo lleva a tener una porosidad asociada a las paredes de las mismas que afecta a las propiedades mecánicas, provocando la falla a tensiones menores de lo esperable. Se optimizó el método de fabricación seleccionando los parámetros de sinterizado (presión de compactado, temperatura y atmósfera). Para caracterizar la meso y microestructura de las muestras se emplearon técnicas de microscopía tradicionales (microscopio electrónico de barrido SEM) y tomografía de rayos x. Esta última técnica permite visualizar en 3D la distribución de las celdas, realizar una caracterización completa de la mesoestructura, evaluar la porosidad de las muestras y seguir la evolución de la deformación de las celdas en ensayos de compresión.Palabras clave: esponjas metálicas, pulvimetalurgia, cobre. ABSTRACTA method for the fabrication of copper foams by powder metallurgy, employing carbamide beads as space holders, is presented. These are removed by water dissolution before sintering the compact. The method allows for a precise control of the cell characteristics (size, shape and distribution) within an interconnected porosity. The use of metal powder promotes the formation of an inherent porosity in the cell walls that affects their mechanical properties, producing failure at a lower than expected tension. Optimization of the method was achieved by selecting the sintering parameters (compaction pressure, temperature and atmosphere). The mesostructure and microstructure of the samples were characterized by traditional microscopy (scanning electron microscope SEM) and x-ray tomography. The latter technique allows a 3D visualization of the cell distribution, a complete characterization of the mesostructure, the evaluation of the porosity and to follow the cell evolution during compression tests.

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Controlled fabrication of porous metals from the nanometer to the macroscopic scale

Abstract: We discuss fabrication techniques for porous metals with the focus on how to control the architecture over several length scales.

Cited by 75 publications

References 111 publications

Multiscale Nanoparticle Assembly: From Particulate Precise Manufacturing to Colloidal Processing

Multiscale Nanoparticle Assembly: From Particulate Precise Manufacturing to Colloidal Processing

Nanoporous Metals with Structural Hierarchy: A Review

Fabricación de espumas de cobre por pulvimetalurgia

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