Facile processing of oriented macro-porous ceramics with high strength and low thermal conductivity

Unidirectionally oriented architectures demonstrate a notable efficiency in enhancing the properties of macro-porous materials, yet are difficult to construct in a time- and cost-effective fashion. Here a facile approach was exploited for fabricating oriented macro-porous ceramic materials by employing natural graphite flakes as a fugitive material and preferentially aligning the flakes within ceramic matrices using accumulative rolling technique. Flaky to near-ellipsoid shaped pores with a homogeneous distribution were created in macro-porous zirconia ceramics with their porosity and microstructural characteristics adjustable by controlling the additive amounts of graphite flakes. The resulting materials exhibited a good combination of properties with high compressive strength up to over 1.5 GPa, which exceeds those of most other porous zirconia ceramics with similar porosities, along with low thermal conductivity of 0.92–1.85 Wm−1·K−1. This study offers a simple means for developing new oriented macro-porous materials with enhanced properties, and may promote their application by allowing for easy mass production.