Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

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

03.03.2011
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".

Publication:

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
E-Mail: daria.andreeva@uni-bayreuth.de

Christian Wißler | Universität Bayreuth
Further information:
http://www.uni-bayreuth.de

More articles from Materials Sciences:

nachricht Novel sensors could enable smarter textiles
17.08.2018 | University of Delaware

nachricht Quantum material is promising 'ion conductor' for research, new technologies
17.08.2018 | Purdue University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Color effects from transparent 3D-printed nanostructures

New design tool automatically creates nanostructure 3D-print templates for user-given colors
Scientists present work at prestigious SIGGRAPH conference

Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and...

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

LaserForum 2018 deals with 3D production of components

17.08.2018 | Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

 
Latest News

Smallest transistor worldwide switches current with a single atom in solid electrolyte

17.08.2018 | Physics and Astronomy

Robots as Tools and Partners in Rehabilitation

17.08.2018 | Information Technology

Climate Impact Research in Hannover: Small Plants against Large Waves

17.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>