Reaction sintered Al2O3/Al2TiO5 microcrack-free composites obtained by colloidal filtration

Dense and microcrack-free Al2O3/Al2TiO5 composites (10, 30 and 40 vol.% of Al2TiO5) have been obtained by colloidal filtration and reaction sintering, using alumina and titania as starting powders. The processing of the composites has been studied focusing on the rheological behaviour of aqueous suspensions of each powder and of mixtures. Colloidal filtration of optimised suspensions, with a solid loading as high as 50 vol.%, and a thermal treatment at 1450 °C, lead to completely reacted and uncracked sintered materials with homogeneously distributed aluminium titanate contents up to 40 vol.% and high density. Thermal diffusivity values from 25 to 800 °C are coincident on heating and cooling for the three studied composites, and decrease with temperature and with aluminium titanate content.