Ultraviolet Curable Ceramic Suspensions for Stereolithography of Ceramics

Abstract Ceramic green bodies can be created using stereolithography methods where a ceramic slip consisting of 45-55 v/o ceramic powder is dispersed within a curable ultraviolet solution. In this study, two ultraviolet solutions were examined, an aqueous-acrylamide solution and a low viscosity diacrylate. Of the ceramic materials possible, two were investigated: silica, SiO2, for investment casting purposes, and silicon nitride, Si3N4, for structural parts. After mixing the powders in the curable solution, the ceramic slip is tape cast onto a substrate for cure under a high intensity ultraviolet lamp (220-450 nm) at different exposure times. The materials systems were evaluated at different solids loadings (5-50 v/o) for cure thickness and viscosity control. Silica had a cure depth of 330 μm at a solids loading of 55 v/o, where silicon nitride had a depth of cure of 60 μm at 30 v/o. Preliminary work utilizing scattering theory revealed the cure depth is controlled by the particle size and the refractive index difference between the ceramic and ultraviolet solution. The silicon nitride powder had a smaller particle size and the slip had a larger refractive index term, and this resulted in a lower depth of cure.