Overcoming resolution vs. throughput trade-offs in ceramic material extrusion additive manufacturing via viscoelastic filament stretching

Fabricating large, monolithic ceramic parts using material-extrusion additive manufacturing remains challenging due to difficulty maintaining uniform moisture content during printing, which can lead to drying-induced defects such as warping and cracking, especially as part size and print time increase. Fabricated parts have trade-offs among print resolution, high throughput, and structural fidelity. Our study has shown that increasing the ratio of nozzle traverse speed vs. material extrusion speed increases filament stretching in viscoelastic ceramic paste, helping to overcome the trade-offs between resolution and throughput. Using aqueous ZrB2–SiC (70/30 vol.%) as a representative ultra-high temperature ceramic paste, rheological characterisation revealed viscoelastic yield-stress behaviour with strong shear-thinning properties. Filament behaviour was examined for different nozzle sizes, printing speeds, and layer heights. A critical balance was identified between the speed ratio and layer height to avoid filament instability such as necking and Rayleigh–Plateau instability while maintaining deposition continuity. Three different print approaches were evaluated to produce a representative compact heat exchanger as a large ceramic part with fine features, while addressing the part drying issue during the fabrication.