EPD and spark plasma sintering of bimodal alumina/titania concentrated suspensions

Alumina-aluminium titanate (A-AT) composites and laminates have been recently investigated because they can provide improved flaw tolerance and toughness associated to a microcracking mechanism. A-AT composites have been produced by slip casting and reaction sintering of submicron sized alumina and titania powders. This work deals with the preparation of thick self-sustained A-AT films from mixtures of submicron sized alumina and nanosized titania powders and further sintering by conventional and non-conventional (spark plasma sintering, SPS) methods. Suspensions were prepared in water to high solid loadings, up to 50 vol.%. Self-sustained films were obtained by aqueous electrophoretic deposition (EPD) using graphite substrates under constant current density conditions. The evolution of mass per unit area with current density and deposition time was recorded. The films were characterized in the green state and after sintering at different temperatures (1300-1400) °C. Fully dense A-AT reaction sintered materials were obtained at low temperature by SPS.