PREPARATION AND THERMAL-MECHANICAL PROPERTIES OF ALUMINUM TITANATE BASED CERAMICS

Abstract

Aluminium titanate (Al₂TiO₅) based ceramic materials were successfully processed through the addition of porcelain clay and different amounts of CaO to the stoichiometric alumina - titania mixtures that contain commonly used MgO and Fe₂O₃ additives at 1350-1400 ̊C for 1 h. The effect of the addition of CaO and sintering temperatures on the formation of the Al₂TiO₅ ceramics and thermal-mechanical performances were investigated. The results revealed that CaO promoted the formation of a long columnar Al₂TiO₅ solid solution and anorthite as well as gahnite phases. Due to the mismatch of the thermal expansion coefficient between the Al₂TiO₅ solid solution crystals and the anorthite and gahnite phases, a compressive residual stress developed on the surface of the Al₂TiO₅ solid solution particulates, effectively improving the mechanical properties and inhibiting the thermal decomposition of the Al₂TiO₅ solid solution and the microcrack propagation. The average thermal expansion coefficient (20-800 ̊C) of the sample with 3 wt% CaO sintered at 1400 ̊C for 60 min was 0.80×10-6 ̊C-1, and the flexural strength of the sample with 5 wt% CaO sintered at 1380 ̊C was as high as 58.59 MPa, with a 12.43 % increase in the strength after the thermal shock test.

Keywords

• al₂tio₅ solid solution
• low thermal expansion
• thermal shock resistance
• cao additive