Synthesis and properties of in situ Al 2TiO 5/Al 2O 3 composite

Abstract

A novel route to simple processing of an in situ aluminum titanate–alumina composite is described. This process offers a simple means of tailoring the composition and microstructure of ceramic material. The process involves and equimolar mixture of Al 2O 3–TiO 2 mixed with a varying equal proportion of FeTiO 3+Fe 2O 3 (1–10 wt.%, 50/50 mixture). It is known that the kinetic transformation of the aluminum titanate is slow, leaving unreacted Al 2O 3 and TiO 2 after the Al 2TiO 5 transformation, besides the iron pseudobrookite: Fe 2TiO 5 grows at the expense of hematite–ilmenite solid solution at 1100 °C which is isostructural with Al 2TiO 5 and forms a complete solid solution, the obtained structure over 5% addition was Al 2TiO 5 with dispersed unreacted Al 2O 3. The XRD patterns did not show the presence of FeTiO 3, TiO 2 or Fe 2O 3 signals that makes to believe that they enter completely in solid solution with the aluminum titanate. The variation in composition allows an increase in the aluminum titanate Vickers hardness: 10 GPa partly due to the additive strengthening and to the alumina reinforcement.