| new method was developed for making macroporous ceramics. Macroporous ceramics were fired from template ceramic-polymer composites produced using polymer phase inversion techniques. Combinations of boehmite, silica, and alumina with cellulose acetate or nylon were examined. With increasing ceramic content in the coating dispersions, the composite microstructures can be shifted from large pores (10's of microns) to a smaller pore network (1-2;Firing of the composites was studied using SEM techniques and mercury porosimetry. Successful firing requires a well dispersed ceramic phase in the template composites and a minimum ceramic loading. For the case of alumina-cellulose acetate, 6.5cm x 6.5cm ceramic films were produced that are completely crystalline and crack free. Using environmental SEM and incremental heating studies, the mechanisms of ceramic consolidation during polymer burnout were deduced. Particle-particle contact is established as polymer is removed form the regions of closest particle approach. Van der Waals forces maintain the ceramic particle structure until the sintering temperature is reached. Despite significant shrinkage during sintering, the pore structures of the alumina-cellulose acetate composites are maintained in the fired ceramics and no reduction in pore size is observed for pores greater than... |
