PREPARATION AND THERMAL-MECHANICAL PROPERTIES OF ALUMINUM TITANATE BASED CERAMICS

Aluminium titanate (Al 2 TiO 5 ) based ceramic materials were successfully processed through the addition of porcelain clay and different amounts of CaO to the stoichiometric alumina -titania mixtures that contained commonly used MgO and Fe 2 O 3 additives at 1350 -1400 C for 1 h. The effect of the addition of CaO and sintering temperatures on the formation of the Al 2 TiO 5 ceramics and thermal-mechanical performances were investigated. The results revealed that CaO promoted the formation of a long columnar Al 2 TiO 5 solid solution and anorthite as well as gahnite phases. Due to the mismatch of the thermal expansion coefficient between the Al 2 TiO 5 solid solution crystals and the anorthite and gahnite phases, a compressive residual stress developed on the surface of the Al 2 TiO 5 solid solution particulates, effectively improving the mechanical properties and inhibiting the thermal decomposition of the Al 2 TiO 5 solid solution and the microcrack propagation. The average thermal expansion coefficient (20 -800 ) of the sample with 3 wt. % CaO sintered at 1400 for 60 min was 0.80 10 -6 -1 , and the flexural strength of the sample with 5 wt. % CaO sintered at 1380 was as high as 58.59 MPa, with a 12.43 % increase in the strength after the thermal shock test.