Manufacture of titania foams by replica method and infiltration with anatase nanoparticles

Abstract

Ceramic foams present special features that do not have the corresponding dense materials and hence they are widely used in a broad variety of applications. Titania has exceptional photoinduced properties with applications in membranes, bioceramics and photocatalysis and photovoltaics. However, in the photoinduced applications, the anatase phase is more active, but the sintering at high temperature leads to the transformation to rutile. The maintenance of anatase would require low sintering temperatures leading to a lack of consistency and very weak struts. To avoid this problem a possible alternative is to produce sintered rutile foams and to coat the strut walls with nanoparticles of anatase. This is a very simple and inexpensive method. In this work rutile foams are obtained by the replica method after a full optimization of the rheological behaviour of titania suspensions that are subsequently infiltrated with a colloidal titania suspension either in vacuum or using microwaves. The infiltrated foam can be sintered at 650 °C while maintaining the anatase phase.