Hydrolysis assisted solidification process and its use in ceramic wet forming

A novel ceramic near-net shaping method is presented which enables the prod uction of complex-shaped green bodies directly from aqueous suspensions The hydrolysis assisted solidification (HAS) process relies on the time-delaye d in situ hydrolysis of AIN powder added to concentrated aqueous slurries o f the host powder(s), as a reactant. The incubation period before the hydro lysis starts can be controlled by the addition of anions, which adsorb onto the AlN powder's surface, as well as by temperature. During the hydrolysis reactions part of the water is internally consumed, the aluminum-hydroxide reaction product gels to form a stiff network, whereas the formation of am monia can be exploited for flocculation. As a result, the viscosity of the host ceramic slurry dramatically increases until its fluid character is los t and a saturated body is formed. Examples of using the HAS process in slur ry forming alumina and zirconia bodies are given and the process potential and limitations are discussed.