A process for producing a rigid reticulated article involves coating a reticulated
substrate which has open, interconnected porosity with a first dispersion comprising
a ceramic or metal powder to form a first coating thereon; drying the coated reticulated
substrate; contacting the coated reticulated substrate with one or more additional
dispersions in succession to form one or more additional coatings thereon; drying
the additional coatings between the steps of contacting; heating the coated reticulated
substrate to pyrolyze organic components; and sintering the coated reticulated
substrate to form a reticulated article, wherein each dispersion has a viscosity
less than that of all preceding dispersions. A rigid reticulated article includes
inner, intermediate and outer sintered layers of material in which the inner and
outer layers are of different composition and the intermediate layer is a composite
of the inner and outer layers.