Production of highly aligned porous alumina ceramics by extruding frozen alumina/camphene body

We herein propose a new technique for producing highly aligned porous ceramics by extruding a frozen ceramic/camphene body. To accomplish this, an alumina/camphene slurry with an initial alumina content of 10 vol% was first frozen unidirectionally in a 20 mm × 20 mm mold and extruded through a reduction die with a cross-section of 5 mm × 5 mm at room-temperature. This simple process enabled the formation of porous alumina ceramics with highly aligned pores as a replica of the camphene dendrites with a preferential orientation parallel to the extrusion direction. The sample showed much higher compressive strength of 280 ± 80 kPa with a porosity of 83 vol% when tested parallel to the direction of pore alignment. In addition, these materials could be used as a valuable framework for the production of ceramic/epoxy composites, particularly with a lamellar structure, which would result in a remarkable increase in mechanical properties.