Gelcasting of alumina

Abstract

Gel casting, a novel method for molding ceramic powders, based on the synthesis concepts of polymer chemistry and traditional slip casting, has been investigated. The process comprises the casting of a stable suspension, prepared with high solid content (ceramic or metallic powder) and an addition of water soluble organic monomers (monofunctional and difunctional-crosslinking). The key role of the process is in situ polymerization of the organic monomers which form a hydrogel that acts as a powder binder. The gelled parts subsequently undergo drying, machining, burning out and sintering to produce a final ceramic body. In this study, the alumna was used as a model ceramic powder.

Ispitan je savremeni postupak oblikovanja keramičkih prahova, "livenje geliranjem", eng. gelcasting, zasnovan na konceptima polimerne hemije i klasičnog postupka livenja. Postupak obuhvata livenje stabilne suspenzije pripremljene sa velikom količinom čvrste faze (keramički ili metalni prah) i rastvorom organskih monomera, monofunkcionalnog i difunkcionalnog-umreživača, u odgovarajuće kalupe željene geometrije. Specifičnost postupka se ogleda u in situ polimerizaciji monomera u hidrogel koji služi kao vezivo praha. Gelirani odlivci se zatim suše, po potrebi mašinski obrađuju, termički tretiraju i sinteruju do finalne keramike. Kao model prah u radu je korišćen aluminijum-oksid.