Mechanical Properties of Al 2 TiO 5 Ceramics for High Temperature Application

The present work investigated the effects of MgO as a thermodynamic stabilizer and ZrO2 and mullite (3Al(2)O(3)center dot SiO2) as kinetic stabilizers on the mechanical properties of Al2TiO5 at high temperatures. Al2TiO5 was synthesized using reaction sintering at 1500, 1550, and 1600 degrees C for 2 h. The mix-stabilized Al2TiO5 sintered at 1500 degrees C showed the highest mechanical strength (138 MPa) at 1100 degrees C, while the mullite-only Al2TiO5 sintered at 1550 degrees C showed a mechanical strength of only 67 MPa at 1200 degrees C. The strength improvement achieved at high temperatures was affected by not only secondary phase mullite to inhibit grain growth of Al2TiO5 and to improve strength but thermodynamic stabilizer to promote synthesis Al2TiO5. The coefficient of thermal expansion of mix-stabilized Al2TiO5 decreased with increase of sintering temperature due to its microcrack, however, that of the mullite-only Al2TiO5 was not changed because of large number of pores.