Abstract
Gelcasting is a near-net-shape forming technique that is applicable to various types of powders. It is accomplished by casting a concentrated suspension of a commercial ceramic powder in a solution of a polymerizable monomer and then polymerizing. A filled gel is formed, which is dried and processed further. Alumina, sialon, and silicon nitride parts of various geometries have been made and are described. Emphasis is placed on the Unitoperations of the process. Because a requirement of the process is a castable suspension of more than 50 vol % solids loading, good dispersion is crucial. Drying, another key process, has been studied extensively, Shrinkage from the cast size occurs during drying and further shrinkage occurs during sintering. Data on the relationship of physical properties of products to some of the more significant processing variables is discussed. Emphasis is also placed on the machinability of the dried gelled body. Because the body at this stage is quite durable, green part machining is feasible. The monomer used in the process is acrylamide, which undergoes a vinyl polymerization. Environmental, safety and hygiene issues are summarized. Accoedingly, the U.S,
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