3D-printed polymer-derived ceramics with tunable cellular architectures

Abstract

Ceramic materials possess high mechanical strength and environmental stability, but their brittleness limits their suitability for structural applications. A solution lies in using polymer-derived ceramics (PDCs), which offer enhanced toughness and versatility in shaping unlike traditional ceramic processing methods. This study explores tunable ceramic cellular architectures based on triply periodic minimal surface (TPMS) designs, fabricated via stereolithography (SLA) using a silicon oxycarbide precursor formulated for vat photopolymerization. By combining the preceramic polymer with a photoinitiator, crosslinkers, and other additives, intricate shapes are 3D-printed and then pyrolyzed under nitrogen, resulting in PDCs with complex TPMS geometries. The toughness, strength, and stiffness of the 3D-printed structures are evaluated through quasi-static compression experiments. Comprehensive material and microstructural characterizations of the PDCs are performed pre- and post-pyrolysis, employing visual inspection, X-ray micro-tomography, thermogravimetric analysis, energy dispersive X-ray spectroscopy, density, and rheological measurements. Optimization of 3D printing and pyrolysis parameters yields ceramic structures with 2.2 MPa compressive strength and 330 MPa stiffness with a lattice density of 0.5 g cm-3. The ceramic material, including porosity, had a maximum density of 1.63 ± 0.01 g cm-3. This low-cost SLA 3D printing technique is ideal for creating thin features and customized structures of bio-inspired, architectured ceramics. Furthermore, the process exhibits excellent printability, being compatible with common and cost-effective SLA, DLP, and LCD 3D printers.