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Abstract
Incipient Flocculation Molding (IFM) is a new and low-cost net-shape forming technique for ceramic components. Unlike other ceramic forming processes, the slurry has a very low viscosity, which facilitates molding very intricate features. IFM utilizes a concentrated, non-aqueous, sterically stabilized ceramic colloidal suspension that is injected into a nonporous mold at a very low pressure. As the temperature of the suspension is lowered below the theta-point of the stabilizer-solvent system, it is destabilized, resulting in flocculation of the slurry to a solid mass. The flocculation process is both rapid and reversible. IFM operates essentially as a temperature-dependent deflocculant. IFM is ideal for molding ferroelectric ceramics, particularly PZT powders, for manufacturing actuators having complex and intricate features. This is accomplished by dispersing the powders in a solvent, stabilized by grafted polyethylene glycol (PEG), and injecting into a mold. The solvent is removed by vacuum evaporation and the dried green body is finally sintered at an elevated temperature.