One-step sintering of co-extruded, crack-free continuous carbon fiber-reinforced SiOC mini-composites

Although ceramics exhibit excellent thermal, chemical, and mechanical stability, their brittleness limits their use in high end applications; therefore, Ceramic Matrix Composites have been developed to provide higher toughness. Among the various reinforcements, short fibers represent an optimal compromise between toughening and the potential for exploiting Additive Manufacturing to further enhance their application in harsh environments. On the other hand, continuous fibers allow for better reinforcement, but their integration into Additive Manufacturing processes is challenging. This study reports crack-free Continuous Carbon Fiber-reinforced Silicon Oxycarbide components produced by Direct Ink Writing of a preceramic polymer with embedded short fibers, followed by single-step sintering. This method removes the need for post-sintering densification, lowering processing complexity and cost while enabling continuous fiber reinforcement in advanced ceramic composites. We demonstrate CCF-reinforced SiOC mini-composites with a density of 1.83 g/cm³ and maximum bending and tensile strengths of 74 MPa and 26 MPa, respectively.