Science Daily explores the weird, microscopic world of
making ceramics that can bend and twist and smush and reform:
Caltech materials scientist Julia Greer and her colleagues…explain how they used the method to produce a ceramic (e.g., a piece of chalk or a brick) that contains about 99.9 percent air yet is incredibly strong, and that can recover its original shape after being smashed by more than 50 percent.
“Ceramics have always been thought to be heavy and brittle,” says Greer, a professor of materials science and mechanics in the Division of Engineering and Applied Science at Caltech. “We’re showing that in fact, they don’t have to be either. This very clearly demonstrates that if you use the concept of the nanoscale to create structures and then use those nanostructures like LEGO to construct larger materials, you can obtain nearly any set of properties you want. You can create materials by design.”.
They found that the alumina structures with a wall thickness of 50 nanometers and a tube diameter of about 1 micron shattered when compressed. That was not surprising given that ceramics, especially those that are porous, are brittle. However, compressing lattices with a lower ratio of wall thickness to tube diameter — where the wall thickness was only 10 nanometers — produced a very different result.
“You deform it, and all of a sudden, it springs back,” Greer says. “In some cases, we were able to deform these samples by as much as 85 percent, and they could still recover.”