VIBRAFORMING AND IN-SITU FLOCCULATION OF CONSOLIDATED, COAGULATED, ALUMINA SLURRIES

Aqueous, alumina slurries dispersed at low pH form weakly attractive n etworks when excess counterions are added, These slurries can be conso lidated to a high relative packing density via either pressure filtrat ion or centrifugation without mass segregation or density gradients, T hese saturated, consolidated bodies can be reshaped by vibrating them into a complex-shaped die cavity, a process termed VibraForming, The y ield stress of these bodies can be increased by adding urea to the slu rry before consolidation and then heating the VibraFormed body to chan ge the pH of the water within the body to the isoelectric point for th e alumina powder, The increased yield stress, characterized by stress relaxation experiments, allows the body to be removed from the die cav ity without shape distortion.