, Volume 42, Issue 20, pp 8760-8764
Date: 15 Jul 2007

Porous alumina ceramics produced with lycopodium spores as pore-forming agents

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Many applications of porous ceramics require a precise control of porosity, as well as pore size, pore shape and pore space topology. Among the various pore-forming agents (PFA) used in ceramic technology, those of biological origin are especially popular for fabricating porous ceramics, due to the fact that their burnout is usually harmless from the ecological and hygiene point of view, while their content of ash-producing inorganic salts is mostly low enough to be neglected with respect to the ceramic composition. Examples are wood flour (saw dust), crushed nut shells [13] and poppy seed [4] for pore sizes of several hundreds of micrometers and, on the other hand, starch for pore sizes below 100 μm [525]. Commercially available starch types cover the size range from approx. 5 μm for rice starch to approx. 50 μm for potato starch (median diameter) [525]. Unfortunately, closer inspection reveals that between corn and tapioca starch, which both have a median size of approx. 12–15 μm,