Porous ceramics offer a wealth of uses from water treatment to catalysis to sensors. Processing of porous materials historically has focused on foaming methods in the liquid state. Two examples of alternative processing methods for porous ceramics are presented here, one from natural materials, the second synthetic, with an eye toward optimal design and properties. The first illustration is of silicon carbide (SiC) produced from a naturally derived scaffold - wood. This so-called “biomorphic” SiC is made by pyrolyzing wood to create the carbon scaffold. The scaffold or template is then used for silicon infiltration and reaction to create versatile SiC-based cellular materials having porosities of more than 50%.

Thermoreversible gelcasting has emerged as another feasible processing method for porous, complex-shaped ceramics. Thermoreversible gelcasting is a direct casting method in which a triblock copolymer in solution is used to disperse ceramic particles. Fugitive phases are included to produce the requisite porosity. Gelation is controlled solely by temperature, as the process uses a physical rather than a chemical gelation and can be reversed multiple times. This method has recently been applied to the processing of porous/dense aluminum oxide laminates.