Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Highly precise nanostructuring using ultrasound: new procedure to produce porous metals

They are corrosion resistant, mechanically strong and withstand exceedingly high temperatures. With such characteristics, porous metals are generating a growing interest in numerous innovative fields of technology.

They are characterised by nanostructured surfaces with pores measuring only a few nanometres in diameter. An international research team including Dr Daria Andreeva of Bayreuth University (department of Physical Chemistry II) has successfully developed a heavy-duty and cost-efficient ultrasound procedure for the design and production of such metallic structures.

In this process, metals are treated in an aqueous solution in such a way that cavities of a few nanometres evolve, in precisely defined gaps. For these tailor-made structures, there is already a broad spectrum of innovative applications, including air cleaning, energy storage or medical technology. Particularly promising is the use of porous metals in nanocomposites. These are a new class of composite materials, in which a very fine matrix structure is filled with particles ranging in size up to 20 nanometres.

The new technique utilises a process of bubble formation, which is termed cavitation in physics (derived from lat. "cavus" = "hollow"). In seafaring, this process is feared due to the great damage it can cause to ship propellers and turbines. For at very high rotation speeds, steam bubbles form under water. After a short period under extremely high pressure the bubbles collapse inwardly, thus deforming the metallic surfaces. The process of cavitation can also be generated using ultrasound. Ultrasound is composed of compressional waves with frequencies above the audible range (20 kHz) and generates vacuum bubbles in water and aqueous solutions. Temperatures of several thousand degrees centigrade and extremely high pressures of up to 1000 bar arise when these bubbles implode.

A precise control of this process may lead to a targeted nanostructuring of metals suspended in an aqueous solution – given certain physical and chemical characteristics of the metals. For metals react very differently when exposed to such sonication, as Dr Daria Andreeva together with her colleagues in Golm, Berlin and Minsk has shown. In metals with high reactivity such as zinc, aluminium and magnesium, a matrix structure is gradually formed, stabilised by an oxide coating. This results in porous metals that can for instance be further processed in composite materials. Noble metals such as gold, platinum, silver and palladium however behave differently. On account of their low oxidation tendency, they resist the ultrasound treatment and retain their initial structures and properties.

The fact that different metals react in dramatically different fashion to sonication can be exploited for innovations in materials science. Alloys can be converted in such a way to nanocomposites in which particles of the more stable material are encased in a porous matrix of the less stable metal. Very large surface areas thus arise in very limited space, which allow these nanocomposites to be used as catalysts. They effect particularly fast and efficient chemical reactions.

Together with Dr Daria Andreeva, the researchers Prof Dr Andreas Fery, Dr Nicolas Pazos-Perez and Jana Schäferhans, also of the department of Physical Chemistry II, contributed to the research results. With their colleagues at the Max Planck Institute of Colloids and Interfaces in Golm, the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH and the Belarusian State University in Minsk, they have published their latest results online in the journal "Nanoscale".


Ekaterina V. Skorb, Dmitri Fix, Dmitry G. Shchukin, Helmuth Möhwald, Dmitry V.
Sviridov, Rami Mousa, Nelia Wanderka, Jana Schäferhans, Nicolas Pazos-Perez,
Andreas Fery, and Daria V. Andreeva,
Sonochemical formation of metal sponges,
in: Nanoscale, Advance first,
DOI-Bookmark: 10.1039/c0nr00635a
Contact for further information:
Dr Daria Andreeva
Department of Physical Chemistry II
University of Bayreuth
95440 Bayreuth
Tel.: +49 (0) 921 / 55-2750

Christian Wißler | Universität Bayreuth
Further information:

More articles from Materials Sciences:

nachricht The search for dark matter widens
21.03.2018 | American Institute of Physics

nachricht Scientists have a new way to gauge the growth of nanowires
19.03.2018 | DOE/Argonne National Laboratory

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

TRAPPIST-1 planets provide clues to the nature of habitable worlds

21.03.2018 | Physics and Astronomy

The search for dark matter widens

21.03.2018 | Materials Sciences

Natural enemies reduce pesticide use

21.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>