UV-assisted direct ink writing of Si3N4/SiC preceramic polymer suspensions

Direct ink writing (DIW) offers a flexible and readily available processing route for achieving ceramic components with complex shapes and geometries. The successful printing of ceramic green bodies using DIW typically requires the formulation of particle-loaded inks having a narrow window of rheological properties that enable both flow through the nozzle and support the weight of additional layers. Herein, we present a method for DIW that employs UV-curing to enable printing of otherwise unprintable inks. The inks used in this study are suspensions consisting of a commercially available polycarbosilane precursor and silicon nitride, Si3N4, powders. A diacrylate cross-linker and photointiator were employed to enable UV-curing. The effect of cross-linker content on UV-rheology and cure depth as they pertain to printing, and slump in self-supported lattice structures, are discussed. UV-assisted DIW produced components of a high degree of complexity, capable of supporting over-hanging structures, low shrinkage, and relatively high degree of ceramic conversion