Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Metal Fibers Baked To Make Filters

09.07.2004


In automotive catalytic converters and industrial exhaust gas filters, porous materials play a crucial role: they filter and break down hot waste gases. It is now possible to process virtually all metal alloys into fibers which can be used to make open-pored sintered materials.

The requirements to be met by a coffee filter are simple: it must retain the powder and not be decomposed by the hot water. The conditions for dealing with exhaust gases in industrial processes are much tougher: temperatures of several hundred degrees and aggressive media are no rarity. In such conditions, manufacturers need different filter materials than cellulose or textiles in order to remove particles and pollutants. A solution is provided by filters made of metal, as produced by researchers at the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research IFAM. The filters are made of small metallic fibers - a few millimeters long and just a tenth of a millimeter thick. Depending on the application, they can be baked to make semis such as rings, tubes or disks.

In conventional fiber manufacture, however, the metal must be formable. “High-temperature alloys containing lots of aluminum are too brittle for this purpose,” explains Olaf Andersen from the institute’s Powder Metallurgy and Composite Materials unit in Dresden. “We can make fibers from virtually any metal or alloy. This allows us to produce particularly heat-resistant or catalytically active filters tailor-made for specific applications.” The extremely wide range of materials is made possible by a new process applied by Andersen and his colleagues. Formability is not a requirement because the fibers are drawn directly from molten metal. A cooled roll with a fine profile rotates over the melt. The raised areas of the roll’s profile determine the length and width of the resulting fibers. Where they touch the liquid metal’s surface, it cools down, solidifies, contracts and finally disengages from the roll as a thin fiber. In a second step the scientists pack the finished fibers in a mold, cover it with a plate and heat the fibers until they are close to melting point. During sintering the cover plate drops down gradually until it reaches a spacer. The remaining volume and the fiber length determine the size of the cavities in the finished filter.



The porous metal filters are used, for example, to protect electric motors. If the motor catches fire or explodes, the hot gases are expelled through the filter. They cool down rapidly on the large inner metal surface, which reduces risks and further damages. In an EU project, the IFAM researchers are developing a melting furnace filter in cooperation with the French company LECES based near Metz. As the exhaust gases from the furnaces contain dioxins, the filters need to be catalytically active in order to effectively destroy these toxic substances.

Johannes Ehrlenspiel | alfa
Further information:
http://www.fraunhofer.de

More articles from Materials Sciences:

nachricht Atomic structure of ultrasound material not what anyone expected
21.02.2018 | North Carolina State University

nachricht Hidden talents: Converting heat into electricity with pencil and paper
20.02.2018 | Helmholtz-Zentrum Berlin für Materialien und Energie

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Developing reliable quantum computers

International research team makes important step on the path to solving certification problems

Quantum computers may one day solve algorithmic problems which even the biggest supercomputers today can’t manage. But how do you test a quantum computer to...

Im Focus: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Stiffness matters

22.02.2018 | Life Sciences

Magnetic field traces gas and dust swirling around supermassive black hole

22.02.2018 | Physics and Astronomy

First evidence of surprising ocean warming around Galápagos corals

22.02.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>