title: Porous ceramics mimicking nature-preparation and properties of microstructures with unidirectionally oriented pores.
abstract: Porous ceramics with unidirectionally oriented pores have been prepared by various methods such as anodic oxidation, templating using wood, unidirectional solidification, extrusion, etc. The templating method directly replicates the porous microstructure of wood to prepare porous ceramics, whereas the extrusion method mimics the microstructures of tracheids and xylems in trees. These two methods are therefore the main focus of this review as they provide good examples of the preparation of functional porous ceramics with properties replicating nature. The well-oriented cylindrical through-hole pores prepared by the extrusion method using fibers as the pore formers provide excellent permeability together with high mechanical strength. Examples of applications of these porous ceramics are given, including their excellent capillary lift of over 1 m height which could be used to counteract urban heat island phenomena, and other interesting properties arising from anisotropic unidirectional porous structures.
authors.affiliation: Materials and Structures Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori, Yokohama, 226-8503, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Okada
authors.affiliation: Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro, Tokyo, 152-8552, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Isobe
authors.affiliation: Materials and Structures Laboratory, Tokyo Institute of Technology, 4259, Nagatsuta, Midori, Yokohama, 226-8503, Japan.
authors.forename: Ken-Ichi
authors.initials: KI
authors.lastname: Katsumata
authors.affiliation: Graduate School of Environmental Science, Okayama University, 1-1-1 Tsushimanaka, Okayama, 700-8530, Japan.
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kameshima
authors.affiliation: Department of Metallurgy and Ceramics Science, Tokyo Institute of Technology, 2-12-1, O-okayama, Meguro, Tokyo, 152-8552, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Nakajima
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington, New Zealand.
authors.forename: Kenneth J D
authors.initials: KJ
authors.lastname: MacKenzie
keywords: anodic oxidation; extrusion process; porous ceramics; templating; unidirectional porous microstructure; unidirectional solidification