Not so heavy metal

Scientists at the Fraunhofer Institute have developed a material which appears and behaves like metal but is made ultra light through the addition of tiny glass bubbles.



The material is made by introducing hollow glass balls measuring a maximum of 60 micrometres 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,” said Dr. Jörg Weise from the Shaping and Functional Materials branch at Fraunhofer.



Although the material is extremely porous, it looks as smooth as metal and weighs only a fraction of the amount. Using this technique, the density of aluminium is reduced from 2.7 grams per cubic centimetre to only 1.2 grams per cubic centimetre, and that of zinc from seven grams per cubic centimetre to 3.1 grams per cubic centimetre.



The aluminium composite material has a density similar to that of a polymer, but has the same surface feel as metal and has a high temperature resistance. Despite being so light, it can withstand pressures up to 1,000 bar, equivalent to the pressure at a depth of 1,000 metres under water. Its structure also enables the light metal to absorb energy in the event of a crash.



Weise said he believes it could be used in the lightweight construction industry and that there are other potential benefits.



“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 on the possibility of chrome-plating zinc containing hollow glass balls,” Weise said.