Al2TiO5–mullite porous ceramics from particle stabilized wet foam

Aluminium titanate (Al2TiO5)–mullite porous ceramics were synthesized by a direct foaming method, using αα-Al2O3, TiO2, and SiO2 as starting materials. The initial suspension for Al2TiO5 was prepared by adding TiO2 suspension to an equimolar amount of partially hydrophobized colloidal Al2O3 suspension. A secondary suspension was prepared using molar composition 3:2 Al2O3/SiO2, and blended to the initial suspension in (0, 10, 20, 30 and 50) vol%, to obtain the mullite phase in the sintered sample. The wet foam exhibits an air content of 80–92% and Laplace pressure from 1.30 to 2.23 mPa, which results in 68–83% foam stability. It also exhibits a much higher adsorption free energy of about 2.2×10−13 J to 2.7×10−13 J at the interface, which results in irreversible adsorption of particles at the air–water interface, leading to outstanding foam stability. The final suspension was foamed, and the wet foam was sintered at 1500 °C for 1 h. Phase identification was accomplished using X-ray diffraction, and microstructural analysis was performed by field emission scanning electron microscopy.