Ceramic binder jetting additive manufacturing: Effects of granulation on properties of feedstock powder and printed and sintered parts

Because of its high sinterability, nanopowder could be beneficial for ceramic binder jetting additive manufacturing to achieve a high density on printed and sintered parts. However, the flowability of nanopowder is poor because of the large interparticle cohesion. This poor flowability prohibits the usage of nanopowder in ceramic binder jetting. In this study, to improve the flowability of nanopowder, alumina nanoparticles were granulated into micron-sized granules through spray freeze drying. The raw nanopowder and granulated powder were compared by characterizing their flowability and printability. Results showed that the granulated powder had a much better flowability than the raw nanopowder. Because of the superior flowability, the granulated powder formed a denser and smoother powder bed than the raw nanopowder and resulted in denser and smoother printed and sintered samples. These improvements indicated that the printability of nanopowder was improved by granulation.