Roller-compaction-assisted binder jetting with different granulated zirconia powders

Abstract

Three zirconia powders were printed on a commercially available binder jetting printer with forward-rotating roller compaction. The three powders include a commercially available granulated powder prepared by spray drying (SD), a lab-prepared granulated powder by slow freezing and freeze drying (SF-FD), and a lab-prepared granulated powder by fast freezing and freeze drying (FF-FD). Effects of compaction thickness on the densities of the printed samples were studied. Defects (including distortion, cracking, and delamination) were observed in the printed samples as a result of excessive compaction. The results show that different powders behaved differently under powder bed compaction. The SD powder could not be compacted with a forward-rotating roller, while the SF-FD and FF-FD powders could be compacted to achieve higher powder bed density. Under excessive compaction, printed samples from SF-FD and FF-FD powders showed different defects (i.e., distortion, delamination, or cracking). After sintering, the printed samples from all three powders could achieve a similar density of about 50%, but showed different fracture surfaces: those from the SD powder had intergranular fracture, while those from SF-FD powder had transgranular fracture. This study indicates that different granulated powders could be used to tune the compaction behaviour in roller-compaction-assisted binder jetting and further fracture behaviour of the sintered samples.