Biomimetic Processing of Ceramics and Ceramic-Metal Composites

Abstract

Biomimetic 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.

Biological materials: Structure and mechanical properties

“…However, severe problems occurred because of the reaction of Al with B 4 C forming Al 4 C 3 , a very brittle material. Although improvements were achieved in the mechanical properties of synthetic laminated composites [164,166,349] based on biological architecture, these have not been as extraordinary as the one nacre provides in comparison with monolithic CaCO 3 . This may be due to limited laminate thickness in synthetic composites and the still not yet clearly identified composition and structure, especially of the complex nanolaminated structure in the organic layer.…”

An introduction to biomimetics: A structural viewpoint

“…The nacre structure, mother-of-pearl, is found in many families of mollusks, such as red abalone (Haliotis rufescens; Currey, 1987;Jackson et al, 1988;Sarikaya et al, 1990;Sarikaya and Aksay, 1992;Yasrebi et al, 1990), the gastropod family, cephalopods, such as nautilus (Nautilus pompilius; Gregoire, 1972) and bivalves, such as black-lipped pearl oysters (Pinctada margaritifera; Currey, 1987). A transverse cross-section of the red abalone shell displays two types of microstructures: an outer prismatic layer (calcite) and inner nacreous layer (aragonite).…”

“…A transverse cross-section of the red abalone shell displays two types of microstructures: an outer prismatic layer (calcite) and inner nacreous layer (aragonite). The structure and properties of the nacreous layer are described here as this is the part of the shell that displays an excellent combination of mechanical properties as a result of its highly ordered hierarchical structure (Currey, 1987;Jackson et al, 1988;Sarikaya et al, 1990;Sarikaya and Aksay, 1992;Yasrebi et al, 1990). As shown in Figure 5, nacre is composed of stacked platelets (0.2-0.5 pm thick) that are arranged in brick and mortar microarchitecture with an organic matrix (20-400 nm in thickness) forming a "glue" between the platelets (Jackson et al, 1988;Sarikaya et al, 1990;Yasrebi et al, 1990).…”

Processing of Ceramics by Biopolymers. Ultrastructure-Property Relationships in Biocrystals

“…Vesicle-Mediated Multicomponent Processing: Intravesicular precipitation of inorganic, crystalline particles is a very common method of producing nanosized particles in biological systems [24,25]. For example, nanometer-sized magnetite particles are fabricated in intracellular vesicles by certain types of bacteria with precise control over particle morphology and orientation (Fig.…”

“…For example, nanometer-sized magnetite particles are fabricated in intracellular vesicles by certain types of bacteria with precise control over particle morphology and orientation (Fig. 5) [24,25]. Various investigators have already demonstrated that single component particles can be precipitated within synthetic vesicles as a model system for the study of biomineralization [26].…”