A comparison study of tialite ceramics doped with various oxide materials and tialite-mullite composites: microstructural, thermal and mechanical properties

Tialite (Al2TiO5) is a material of very low thermal expansion coefficient, high thermal shock resistance, high refractoriness and good corrosion resistance. However, its applications are very limited due to its low mechanical strength and to its thermal instability in the temperature range 750-1350 °C, which leads to the decomposition of the material to its parent oxides alumina and rutile. To overcome both problems, stabilization of the structure is tried through doping with various oxides; in the present work, a comparison study of the properties that can be achieved and of the decomposition behavior of tialite ceramics stabilized by adding MgO, talc or feldspar and of tialite-mullite composites made by the addition of kaolin is carried out. The processing conditions are also investigated for preparing porous ceramics for applications in the area of soot traps and hot gas clean-up. It was found that talc addition has an excellent stabilizing behavior, whereas tialite-mullite composites exhibit increased strength. Such composites with 10-20 wt.% mullite present the appropriate properties for the applications under consideration. Mullite presence also brings a stabilizing effect, thus in combination with talc additions it could lead to a very stable product.