Volumetric tomographic 3D printing of silicon oxycarbide ceramics

Ceramic materials have numerous industrial applications thanks to their high chemical, mechanical, and thermal resistances. Precisely because of these reasons, producing parts with these materials is technically challenging with conventional subtractive manufacturing methods. Additive manufacturing is a promising alternative to fabricate ceramic parts with complex geometries. Recent works have demonstrated the fabrication of micrometric tools layer-by-layer, by two-photon polymerization of preceramic materials, with subsequent polymer-to-ceramic conversion through the pyrolysis step. Two-photon polymerization exhibits very high printing resolutions, typically at the cost of print speed and size. On the other hand, tomographic volumetric 3D printing has been used to rapidly produce larger objects in the cm-scale with different materials, such as acrylates, cell-compatible hydrogels and thiol-ene photoresins. Tomographic volumetric 3D printing uses one-photon polymerization; which reduces the achievable resolution but strongly increases the printing speed and achievable size. Additionally, tomographic volumetric 3D printing has the advantage of printing hollow structures without the need of support structures. Here we show that tomographic volumetric additive manufacturing can be applied to the fabrication of ceramic parts from liquid SiOC-based precursors. We use a reverse tomographic technique that consists of collimating light from a 405 nm laser, which is modulated into dynamic patterns by means of a digital micromirror device, to polymerize a viscous liquid ceramic precursor within a rotating vial. After printing, the unpolymerized monomer is washed away with organic solvents, leaving the green body that is pyrolyzed into the final ceramic part. We show the fabrication of smooth parts with high ceramic conversion.