Rheological Behavior of Alumina Suspensions for Additive Manufacturing Using Digital Light Processing

Additive manufacturing using vat photopolymerization has gained attention for creating intricate ceramic parts. Digital light processing (DLP) is known for its high resolution and speed, but achieving stable ceramic suspensions with high solids concentration and low viscosity is challenging. This study investigated the impact of different dispersants on the rheology and stability of photopolymerizable suspensions. A commercially available water-washable resin, along with three dispersants (Castament FS 10, Triton-X, and DISPERBYK-111), and reactive alumina powder were used to formulate various ceramic suspensions. Viscosity and stability measurements determined the most efficient dispersant and concentration for DLP ceramic part production. Results showed that suspensions with DISPERBYK-111 had optimal viscosity and stability. However, the commercial resin presented higher viscosity, limiting solid loading to 40 vol.% alumina. Successful printing trials were conducted using a commercial printer. The alumina parts were thermally treated at 1550oC, resulting in ceramics with a good surface finish, well-defined and adhered printed layers, 53.3% relative density, 19.65% XY shrinkage, and 13.69% Z-axis shrinkage.