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

Abstract

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.