TOUGH CERAMIC EMERGES FROM ICE

Abstract

MATERIALS SCIENTISTS HAVE drawn inspiration from nature to enhance the properties of ceramics. Antoni P. Tomsia, Sylvain Deville, and colleagues at Lawrence Berkeley National Laboratory have used nacre, or mother-of-pearl, as a model for the production of improved ceramic materials. Ceramics tend to be strong but brittle. On the other hand, nacre, a natural ceramic composite, is both strong and tough enough to reinforce mollusk shells. Nacre is constructed of layers of calcium carbonate platelets held together with a small amount of protein mortar. Tomsia's team created a synthetic mimic of this structure, using freezing water as a template ( Science 2006 , 377 , 515). The researchers knew that when seawater freezes, it can form tiny plates of ice. Impurities in the water are squeezed out as the plates form and become trapped in the spaces between them. Tomsia's group exploits this behavior using concentrated suspensions of ceramic particles in water. As the water freezes, ...