Preparation and characterization of porous fibrous mullite bodies doped with TiO2

The preparation and characterization of porous mullite ceramic bodies doped with TiO2 are described. The bodies were prepared from sol–gel by the replication process with cellulosic nonwoven fabric as the template. The microstructure and the dependence of the porosity and the mechanical properties on the TiO2 content are discussed. Clear differences were found in the microstructure of doped and undoped samples. Rodlike anisotropic mullite grains were grown in titania-doped mullite bodies fired at 1650 °C, while fine almost homogeneously distributed mullite grains were formed in the latter. Strength measurements showed that increasing TiO2 content increased the bending strength of the bodies.

Research Highlights
► TiO2 addition increases the bulk density and decreases the apparent porosity.
► The results confirm a typical strength – porosity exponential dependency.
► TiO2 addition increases the samples grain size.
► The grain size increase leads to the formation of necks between grains.
► Large mullite crystals are distinguished in TiO2 – doped samples.