Wood-metal material blend

Wood foam with metal muscle

Print edition :

Metal sponge manufactured in a casting process. Photo: Fraunhofer IWU

In a project titled “HoMe Foam”—HoMe being a German acronym for wood-metal—the Fraunhofer Institute for Wood Research (FIWR), Wilhelm-Klauditz-Institut WKI, together with scientists from the Fraunhofer Institute for Machine Tools and Forming Technology IWU and the Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, has developed a technique to blend these two contrasting materials in perfect harmony. The innovative new material mix has excellent insulating properties as well as a low bending strength.

Keeping in view sustainability as a key aspect when developing new materials, where the main focus is on ensuring that the input materials come from renewable sources and that the product is recyclable at the end of its service life, researchers at the FIWR have been developing wood foams 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, such as usage as core material in lightweight construction and sandwich panels, as packaging material and in thermal insulation and soundproofing.

In order to extend the application range of wood foam, a group led by Frauke Bunzel from Fraunhofer WKI developed a wood-metal foam hybrid that unites the properties of both wood foam and metal sponge.

In the course of the project, they elaborated on the principles for manufacturing the composite and determined its initial key properties.

“Strengthening the wood foam with a metal skeleton, for example, can substantially enhance its characteristically low bending strength,” Bunzel said. In the case of HoMe foam, the bending strength of the hybrid is greater than that of its two components.

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.

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