An interdisciplinary team of researchers from Faunhofer WKI, IWU and IFAM have developed a new material by combining wood foam and metal sponge.
The innovative new material mix which was developed under the HoMe (a German acronym for wood-metal) Foam project, boasts of excellent insulating properties and has a low bending strength.
Wood foams are made entirely of wood. The natural adhesive properties of wood make synthetic adhesives superfluous.
From an ecological standpoint, this makes wood foams ideal for a whole range of applications like lightweight construction, packaging and thermal insulation or soundproofing.
In order to extend the application range of wood foam, the WKI researchers led by Dr. Frauke Bunzel have developed a wood-metal foam hybrid that unites the properties of both wood foam and metal sponge.
Manufacturing the composite and determining its initial key properties, helped the researchers to classify the new product in relation to other materials.
“Strengthening the wood foam with a metal skeleton, for example, can substantially enhance its characteristically low bending strength. In the case of HoMe foam, the bending strength of the hybrid is even greater than that of its two components. That makes it an ideal core material for sandwich panels or as a self-supporting lightweight semi-finished material,” explains Dr. Bunzel.
Another advantage is that, unlike wood foam, metal sponge can conduct electricity. The outstanding properties of wood foam are its high levels of sound absorption and low thermal conductivity, making it an excellent insulation material.
Combining metal sponge and wood foam creates a lightweight hybrid material with a higher functionality, one that can be used for components that provide reinforcement and absorb sound.
The material is thus suitable for use in the automotive industry, for example, as reinforcing acoustic mats in engine compartments or as floor plates.
According to the researchers, the hybrid material was manufactured in a casting process. The result is a sponge-like, open-cell metal structure with many tiny cavities.
At present, this metal sponge is manufactured in plates measuring 250 mm x 250 mm x 30 mm. The wood foam, which has a firm consistency similar to that of beaten egg whites, is then inserted into the metal sponge plate.
Image credits and content: Fraunhofer IWU/Fraunhofer WKI