Direct ink writing (DIW) of single-phase and composite ceramics: Linking paste rheology, printing parameters, and final material properties

Direct ink writing (DIW) enables shaping complex ceramic geometries. This study developed aqueous ZrO 2 , Al 2 O 3 , and ZTA pastes, emphasizing the correlation between rheology, printing parameters, and sintered properties. Optimization involved adjusting solid loading and organic content. Beyond shear-thinning, "printability" was defined by viscosity at 30 s⁻¹ and the viscoelastic network stability. The yield point (LVER limit) and flow point (G'=G'') were identified as critical parameters governing shape fidelity and self-supporting capability after deposition. Using a 0.84 mm nozzle (1 bar, 4 mm·s⁻¹), stable extrusion and high dimensional precision were achieved. After sintering at 1500 °C, components reached ∼96 % relative density. Microstructural analysis confirmed homogeneous grain structures and strong interlayer bonding. The results demonstrate that precise rheological tuning, standardizing yield and flow points combined with optimized DIW parameters, enables the fabrication of ceramic components with properties competitive with recent literature reports.