Shaping of complex ceramic parts using stereolithography and gel casting
Résumé
The “gel casting” is a process used for producing parts with complex geometries. It was initially developed to overcome the limitations of other shaping processes such as injection moulding or machining. Designed by Janney & Omatete [1] in 1991, this process is very versatile, both in terms of its compatibility with different classes of materials (ceramics and metals) and its compatibility with different mould manufacturing techniques. In practice, gel casting is based on the production of a slurry in an aqueous medium in the presence of a dispersant and a gelling agent. The suspension is pouring into a mould where the gelling can occur and form a three-dimensional network which ensures the conservation of the different parameters of the slurry. The desired part is obtained after drying and then demolding while a debinding/sintering heat treatment ensures its densification. Although the approach is productive and efficient for high quality complexes object, but is it still limited by the need for a manufacturing technic for the mould. Its use is also limited by the toxicity of polymers gelling systems based on acrylamide.
The idea for this project is therefore to work on an indirect additive manufacturing process combining stereolithography (SLA) polymer and gel casting. Additive manufacturing allows the manufacture of casting moulds while gel casting allows the shaping of ceramic parts. The coupling of these two techniques theoretically allows the manufacture of parts with very complex shape where only the ability to unmould and dry the sample is a hurdle.
[1] Omatete, Ogbemi O., Mark A. Janney, et Stephen D. Nunn. « Gelcasting: From Laboratory Development toward Industrial Production ». Journal of the European Ceramic Society 17, no 2‑3 (january 1997): 407‑13.