Novel Preparation of Porous Alumina using Ice Particles as Pore-Forming Agents

Porous ceramics have successfully been used in a wide variety of highly advanced applications. Current routes to porous ceramics are limited in the types of porosity they can create and no one process is flexible enough to create any desired structure. This study introduces the use of ice particles as pore forming agents to fabricate porous materials. This novel method possesses several advantages over current industrial techniques including environmental friendliness, low cost, and flexibility in size and shape of resulting pores. Porous ceramic structures were created by adding preformed ice particles to an alumina slurry which was quickly frozen, air dried, and then sintered. Porosity was characterized using Scanning Electron Microscopy (SEM), Archimedes measurements, and gas sorption techniques. Small spherical pores were successfully created in the 20-200μm range and larger spherical pores were also created in the 2-3 mm range. Amount of porosity was controlled through specifying the amount of ice added to the ceramic slurry. Samples were prepared with porosity levels ranging from 30-75%. As a completely new process, these initial results are quite promising and further development will allow for even greater morphology control.