From Rapid Prototyping to Rapid Firing: On the Feasibility of High‐Speed Production for Complex BaTiO3 Components

Direct ink writing (DIW) is an attractive additive manufacturing (AM) technology because of its simplicity, production speed, and feedstock flexibility; in addition, the use of a limited amount of binder makes the subsequent thermal debinding process easy. Nevertheless, the conventional approach to debind and sinter AMed components remains extremely slow, representing a bottleneck in the manufacturing process. In order to address such limitation, we explored different rapid sintering strategies: ultrafast high-temperature sintering (UHS), pressureless spark plasma sintering (P-SPS), and fast firing (FF), for the densification of BaTiO3 components fabricated by DIW, one of the widely used lead-free piezoceramics. All sintering technologies allow debinding and sintering of crackfree components in a few minutes instead of several hours. The final density and microstructure are strongly dependent on the sintering atmosphere (inert for UHS and P-SPS, air for FF) and a maximum relative density of only ≈72% was obtained when firing occurred in an inert environment, irrespective of the sintering technique (UHS and P-SPS). An undesired phase transition from tetragonal to hexagonal BaTiO3 was also observed upon UHS and -PSPS. On the contrary, FF in air yielded a density of about 95% in a few minutes while maintaining the desired tetragonal polymorph. The results provide proof of feasibility for rapid processing of BaTiO3 components obtained by DIW.