Colloid Casting Processes: Slip Casting, Centrifugal Casting, and Gel Casting

Abstract

The reliability of ceramic materials can be improved by using colloidal processing techniques. In this work, colloid-casting processes such as slip casting, pressure casting, vacuum casting, centrifugal casting, and gel casting for production of complex shaped parts with microstructural homogeneity are reviewed in detail. These routes enable production of green bodies directly from suspension. One crucial step of such processes is to obtain well-dispersed, uniform, and concentrated slip with related sintering additives to obtain stable slips and homogenous ceramic shapes. Furthermore, casting-forming kinetics is a key factor to produce complex ceramic shapes in an economically viable manner. Slip casting is one of the most widely used industrial technique for manufacturing of ceramic parts based on removal of the water in the slurry by capillary action until a thick layer (desired shape) is formed along the porous mold. Pressure, vacuum, and centrifugal casting are more recently used to shorten the casting time and drying time of the molds, while providing more opportunities for automation. Finally, in gel casting green bodies are produced through in situ polymerization of a slurry compromised of ceramic powders and organic monomers to create a macromolecular network for holding the ceramic particles together in the desired shape.