An investigation of build orientation on shrinkage in sintered bioceramic parts fabricated by VAT photopolymerization

In this work, a vat photopolymerization (VP) additive manufacturing process fabricated bioceramic cuboids at different build orientations to investigate their effects on post-sintering shrinkage and associated physical properties. A suspension of β-tricalcium phosphate (TCP) in Autodesk PR 57 commercial photopolymer resin and dimethyl sulfoxide (DMSO) solvent was used to shape green parts. Thermal treatment removed polymer from the green shape before sintering TCP at 1300 ^◦C at 5 ^◦C/min. Part morphology, dimensional shrinkage, and mass loss after sintering were evaluated. Part dimensions parallel to the build direction exhibited greater shrinkage compared to the other two dimensions. Mass loss was independent of build orientation. This paper is the first to investigate the relationship between build orientation and post-sintering shrinkage of bioceramic structures shaped by VP. In this work, an understanding of printing ceramic suspensions, and accounting for dimensional ceramic part shrinkage with respect to build orientation is gained to help guide print parameter selection to improve part fidelity and performance.