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.
Johannes Ehrlenspiel | alfa
New design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University
Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
26.06.2017 | Life Sciences
26.06.2017 | Physics and Astronomy
26.06.2017 | Information Technology