Structured Polymer-Derived Ceramic Composites via Near-Infrared Thermal Stereolithography

We have developed near-infrared (NIR) thermal stereolithography (SLA) to print 2.5D-structured polymer-derived ceramic (PDC) composites with high SiC particle loadings in a PDC matrix. When combined with polymer infiltration and pyrolysis (PIP), this approach overcomes the challenges associated with traditional ultraviolet-based printing techniques when printing composite resins, namely, low light penetration, limited particle loadings, high shrinkage, and weak mechanical properties. Using an NIR laser to deliver spatially controlled thermal energy to the surface of a reactive resin pool induces localized thermally initiated free-radical polymerization in a top-down SLA configuration. After printing the green body, postprocessing methods, including debinding and PIP, are employed to densify and strengthen the printed samples. A Si-O-C _<i>x</i> support network was formed in the debinded samples using a small amount of preceramic polymer in the printing resin to maintain the structural integrity of this porous preform. After 5 cycles of PIP, the PDC composites demonstrated a flexural strength of 74.3 ± 13.7 MPa with a density of 2.31 g/cm³. Different 2.5D lattice designs were fabricated by using this printing and materials processing method, and a compressive strength of 32.8 ± 11.2 MPa was obtained for lightweight honeycomb structures with an effective density of 1.07 g/cm³.