Macroporous ceramics with pore sizes from 400 nm to 4 mm and
porosity within the range 20%–97% have been produced for a
number of well-established and emerging applications, such as
molten metal filtration, catalysis, refractory insulation, and hot
gas filtration. These applications take advantage of the unique
properties achieved through the incorporation of macropores
into solid ceramics. In this article, we review the main processing
routes that can be used for the fabrication of macroporous
ceramics with tailored microstructure and chemical composition.
Emphasis is given to versatile and simple approaches that allow
one to control the microstructural features that ultimately determine
the properties of the macroporous material. Replica,
sacrificial template, and direct foaming techniques are described
and compared in terms of microstructures and mechanical
properties that can be achieved. Finally, directions to future
investigations on the processing of macroporous ceramics are
proposed.