Novel Three-Dimensional Extrusion of Multilayered Ceramic/Camphene Mixture for Gradient Porous Ceramics

This study proposes an innovative way of creating porous ceramics with a unique gradient porous structure using three-dimensional extrusion of a multilayered ceramic/camphene feed rod, denoted as “3D-Exm”. This 3D-Exm technique utilizes the wall slip phenomenon during the extrusion process, which can create a gradient core/shell structure with a gradual change in the core/shell thickness ratio. In addition, the microstructure of ceramic filaments can be tuned through the use of the camphene as a pore-forming agent. Porous alumina ceramics produced using a bilayered feed rod comprised of the alumina/camphene mixtures with the relatively high (ϕH = 40 vol%) and low ceramic contents (ϕL = 10 vol%) showed a gradual change in porosity in the intermediate region between the relatively dense (porosity = ~3 vol%) and highly porous regions (porosity = ~85 vol%).