3D printing of polymer-derived SiOC with hierarchical and tunable porosity

A facile and controllable method for the fabrication of SiOC ceramic components with hierarchical porosity is reported in this work, using additive manufacturing, sacrificial polymeric microbeads and a silicone resin. Particles-containing inks with suitable rheology enabled the fabrication by Direct Ink Writing of scaffolds with mm-scale macropores between filaments, and um-scale and/or nm pores within the filaments. Isotropic shrinkage and an appropriate pyrolysis program enabled to obtain scaffolds without defects and shape distortions. Total porosity and compression strength depended on the content and size of the PMMA particles in the inks, enabling the fabrication of SiOC ceramic with components possessing a remarkable strength up to 2.92 MPa for a total porosity of 86.5 vol% by the addition of 5 mu m PMMA particles.