Phase-inversion tape casting and synchrotron-radiation computed tomography analysis of porous alumina

A variant of tape casting based on the phase inversion phenomenon was adopted for fabrication of porous ceramic wafer. A slurry was prepared by dispersing alumina powder in an N-methyl-2-pyrrolidone (NMP) solution of the polymers polyethersulfone (PES) and polyvinylpyrrolidone (PVP). The slurry was cast using a doctor blade, and immersed in water to solidify the polymer solution via phase inversion. The green tape was dried and sintered at 1500 °C. The as-prepared ceramic wafer was characterized using synchrotron-radiation computed tomography (SR-CT). It was revealed that the ceramic wafer contained typical finger-like macrovoids, and the porosity resulting from these macrovoids was ~30%. The overall porosity of the wafer was 59%, as derived from the density data measured by Archimedes method in mercury. It is concluded that the phase inversion tape casting is a simple and effective method for preparation of porous ceramics.