Mechanical and thermal properties of highly porous Al2TiO5–Mullite ceramics

Al2TiO5–mullite porous ceramics were synthesized by direct foaming method using αα-Al2O3, TiO2 and SiO2 as starting materials. The initial suspension for Al2TiO5 was prepared by adding TiO2 suspension to the equimolar amount of partially hydrophobized colloidal Al2O3 suspension. A secondary suspension was prepared using following molar composition 3:2 Al2O3/SiO2 and it was blended to the initial suspension in (0, 10, 20, 30 and 50) vol% to obtain the mullite phase in the sintered sample. Thermal expansion coefficient and thermal hysteresis curves of the porous ceramic samples with pure Al2TiO5 and of the Al2TiO5 ceramic with mullite addition were measured. Hertzian indentations are used to evaluate the damage behavior under constrained loading conditions. Mechanical behavior from indentation load–displacement curves is investigated.