Improved mechanical quality of ceramic vat photopolymerization prints by supercritical carbon dioxide extraction

Vat photopolymerization (VPP) enables 3D printing of dense ceramics with complex structures, however the mandatory thermal pre-conditioning and debinding steps to remove the organic substances, can last 7 days. Supercritical carbon dioxide (scCO2) extraction was used as a pre-conditioning method to investigate if dense and sufficiently strong alumina parts can be obtained using a shorter thermal debinding cycle, due to the creation of nanosized porosity during the scCO2 extraction. The mechanical properties and microstructure of the sintered alumina parts with 15 h scCO2 extraction + 18 h thermal debinding were comparable to the reference with 101 h debinding, which marks a significant 67 % reduction in time. Furthermore, scCO2 extraction improved the flexural strength and density, and resulted in less deviation. Thus, scCO2 extraction can shorten post-processing of ceramic VPP prints and facilitate more predictable properties, which have been the two bottlenecks related to the VPP process.