SCIENTISTS in Germany have developed a method of producing metal foams for use as translucent room dividers and suspended ceilings.
Closed-pore metallic foams are normally produced by combining metal powders with blowing agents and heating the mixture. As it approaches melting point the blowing agents release gases that form a mass of bubbles within the mixture.
Although metal foams produced using the closed cell technique have seen some success in the automotive sector, thanks to their light weight and rigidity, the research team at Dresdenbased producer m-pore wanted to find a method of producing foams that would be permeable to light.
It has developed a method of casting an open-pored structure that allows light to pass through the interconnected pores, which can also be filled with translucent plastic.
A mould cut in polyurethane foam is coated in wax and the cavity filled with heat-resistant ceramic paste.
When liquid metal is poured into the mould the plastic foam burns away leaving behind a metal sponge filled with pores 1 to 5 mm in diameter. The final step is to blast off the ceramic mould with a water jet.
According to Thomas Hipke, head of production systems department at the Fraunhofer Institute in Chemnitz, Germany, which helped set up an alliance of foam manufacturers, the finished material is expensive at the moment because most of the manufacturing process has to be carried out by hand.