3D-printed SiC-microfiber-reinforced polymer-derived ceramic with high strength at elevated temperature

In this work, a polymer-derived ceramic composite was formulated using polysilazane resin, silicon carbide microfiber reinforcement, and fumed alumina rheology modifier. Demonstration pieces and flexural test specimens were 3D printed using direct ink writing, a type of material extrusion additive manufacturing technology. Printed specimens were cured and then pyrolyzed at 1200°C in argon, resulting in 3D-printed polymer-derive ceramic composites. Flexural test specimens were tested in 3-pt. flexure at room temperature and at high temperature (1200, 1400, 1500, and 1600°C). Flexural strength increased from 97.8 ± 20.1 MPa at room temperature to 367 ± 88 MPa and 401 ± 54 MPa at 1200 and 1400°C, respectively. Strength decreased to ∼184 MPa at 1500°C and was not measurable at 1600°C. Microscopy of fracture surfaces reveals evidence of degradation of the matrix phase above 1400°C and x-ray diffraction reveals the formation of mullite above 1200°C.