Stabilized tialite–mullite composites with low thermal expansion and high strength for catalytic converters

Abstract

Aluminium titanate (AT) is a potential candidate material for use in demanding high temperature applications, because it exhibits an excellent thermal shock resistance due to its low thermal expansion coefficient and high refractoriness. However, industrial applications of this material are hindered by two major limitations. Its decomposition to α-Al 2O 3 and TiO 2 between 800 and 1280 °C and its low mechanical strength. The present work aims to stabilize aluminium titanate with the addition of Fe 2O 3. The decomposition of aluminium titanate–iron oxide solid solutions when heated at 1100 °C for up to 1000 h was studied. The effect of iron oxide addition on pure aluminium titanate properties was investigated. Additionally, strengthening of the iron stabilized AT with mullite was considered adding mullite (M), 3Al 2O 3·2SiO 2 to tialite body at various amounts (5–50%, w/w). Properties like four point bending strength, thermal expansion coefficient (TEC), and porosity of the composites, were evaluated. Finally, the effect of mullite on the mechanical properties of AT–mullite composites was investigated. It was found that aluminium titanate (iron oxide stabilized)–mullite composites exhibit very good mechanical strength combined with excellent thermal stability.