Binder Jetting (BJ) is an additive manufacturing technique of great potential for the production of ceramic materials of complex shape, however the number of feasibility studies on BJ of piezoceramics is still quite  limited. Its application still faces a number of issues, the attaining fully dense materials being the more challenging one.  In this work, as-synthesized as well as commercial  powders are employed in the BJ 3D printing process. The aim is to  apply BJ to the preparation of porous materials while controlling the total porosity and tailoring the pore morphology. Critical parameters  are the starting powder morphology, and its flowability,  the binder saturation and the layer thickness.  PZT complex shapes were produced starting from  conventional solid state synthesized powder, while   KNN lead-free  samples were prepared starting from in house synthesized powder and  a commercial one. Microstructural properties, such as porosity, grain size distributions, and phase composition were studied by SEM, XRD and MIP (Mercury Intrusion Porosimetry) and compared to die-pressed pellets. Considerable residual porosity (~40%) is present in sintered samples, regardless of the printing parameters, with a weak preferential orientation parallel to the printing plane. The piezoelectric characterization demonstrates outstanding d33 values. Finally, the results are discussed in the light of  the employment as porous structures.

References
M. Mariani, R. Beltrami, E. Migliori, L. Cangini, E. Mercadelli, C. Baldisserri, C. Galassi, N. Lecis, Additive manufacturing of lead-free KNN by binder jetting, J. Eur. Ceram Soc. 42 (2022) 5598–5605
M. Mariani, E. Mercadelli, L. Cangini, C. Baldisserri, C. Galassi, N. Lecis Additive manufacturing of niobium-doped lead zirconate titanate (PZT-N) by binder jetting (submitted).