Design of Optimal Organic Materials System for Ceramic Suspension-Based Additive Manufacturing

Ceramic suspension is a basic ingredient for various ceramic processing, and designing a ceramic suspension system is important to secure material processability in various applications. Especially when engineering ceramics, a highly loaded ceramic suspension is essential to fabricate dense ceramic bodies for proper mechanical properties. However, as solid loading increases, the viscosity of ceramic suspension keeps increasing and shows a shear-thickening behavior under a shear condition, which makes suspension formulation a challenging issue of interest. Herein, a strategy to design highly loaded ceramic suspension with optimal organic materials system is given based on the systematic correlation between solubility parameter of organic materials system and rheological processability of highly loaded ceramic suspensions. Especially with silicon nitride suspension that generally suffers from inferior rheological processability, a trend between solubility parameter of organic dispersing media and rheological behavior of suspensions is defined as a material selection guideline. Based on this selection strategy, a photocurable monomer is selected as an optimal dispersing media and directly applied to prepare highly loaded silicon nitride suspension (≈51 vol%) showing low viscosity and a shear-thinning behavior. The designed ceramic suspension is successfully applied to a photocuring-based additive manufacturing process, the digital light processing, for fabrication of various 3D silicon nitride shapes.