Coagulation Method of Aqueous Concentrated Alumina Suspensions by Thermal Decomposition of Hydroxyaluminum Diacetate

Consolidation of aqueous concentrated suspensions was used to shape alumina green bodies because it enabled us to obtain complex-shape components with accurate sizes. A high state of alumina particle dispersion was achieved by using (HO)₂C₆H₂(SO₃Na)₂ (Tiron), which allowed us to obtain stable alumina suspensions at pH 9 with a powder concentration higher than 60 vol%. The addition to the suspension of hydroxyaluminum diacetate, (CH₃CO₂)₂AlOH, which decomposed as the temperature increased, permitted us to coagulate an alumina suspension dispersed with Tiron efficiently. Adsorption measurements, electrokinetic mobility, and the rheological behavior of the suspensions provided useful methods to characterize each processing stage. Dense green bodies with sufficient cohesion could be demolded and dried, demonstrating that the dispersant and the flocculant agent chosen permit one to optimize the direct coagulation casting processing of alumina components.