Combining powder bed compaction and nanopowders to improve density in ceramic binder jetting additive manufacturing

This paper reports a new approach to density improvement in ceramic binder jetting additive manufacturing: combining powder bed compaction and nanopowders. Samples were printed on a commercially available binder jetting 3D printer using an alumina nanopowder. Compaction thickness was varied across 0, 5, 10, 15, 20, and 60 μm at a layer thickness of 5 μm, and across 0, 100, and 200 μm at a layer thickness of 30 μm. Sintered density, as well as powder bed density, was measured. Furthermore, microstructure of sintered samples, with a focus on number and size of pores, was investigated to substantiate the density results. It was shown that at the same layer thickness, higher compaction thickness resulted in higher powder bed density, higher sintered density, and smaller number and size of pores in sintered samples. The highest sintered density (72.0%) achieved in this study was on par with the highest density reported in the literature on binder jetting of alumina without involving unusual liquid feedstocks or special post-processing techniques, demonstrating the effectiveness of this new approach to density improvement.