Biomimetic Processing of Ceramics and Ceramic-Metal Composites

Abstract

ABSTRACTBiomimetic design and processing of laminated B4C-Al cermets, based on knowledge gained from the microstructure-property characterization of abalone shells, is described. In the nacre section of the shell, the microstructure is highly organized as CaCO3(aragonite) crystals, with a thickness of 0.25 μm, separated by a layer of organic matter 300–500 Å thick. This organization forms a miniature “brick and mortar” microstructure. The resultant strength and fracture toughness of the nacre, i.e., 180 MPa and 7 MPa-m1/2, are many orders of magnitude higher than those of monolithic CaCO3. The processing of laminated B4C-Al cermets, based on the microstructure of the nacre, was performed by a combination of tape casting of the ceramic and infiltration of the metal. The resultant cermets displayed a 40% increase in both fracture toughness and strength over monolithic B4C-Al cermets.