Award-winning material

This is how it works: The Bremen-based scientists insert hollow glass balls measuring a maximum of 60 micrometers into the metal during casting. “If the glass balls are evenly distributed, we get a smooth surface that feels absolutely smooth – like metal. If the glass content is unevenly distributed, the material gets a distinctive new appearance, full of streaks,” says Dr. Jörg Weise of the foundry technology working group in the Shaping and Functional Materials branch of the institute. Although the material is extremely porous, it looks as smooth as metal and weighs only a fraction of the amount: As an example, the density of aluminum is reduced from 2.7 grams per cubic centimeter to only 1.2 grams per cubic centimeter, and that of zinc from seven grams per cubic centimeter to less than half, or only 3.1 grams per cubic centimeter.

“Our material can’t quite float on water yet, but we’re working on it,” Weise predicts with a wink. The aluminum composite material has a density similar to that of a polymer, but feels as high-grade as metal and has a high temperature resistance as well. Despite being so light, it can withstand pressures up to 1 000 bar – equivalent to the pressure at a depth of a thousand meters under water. Its special structure enables the light metal to absorb energy in the event of a crash. There are further benefits, too: “Because its pores are so microscopically small, the material can be plated in a similar way to a compact non-porous metal. We are currently carrying out investigations jointly with an industrial partner, HDO Druckguss- and Oberflächentechnik GmbH of Paderborn, on the possibility of chrome-plating zinc containing hollow glass balls,” Weise reports. He believes there are potential applications not only in design elements, but also in the lightweight construction industry.