Direct ink writing of chopped carbon fibers reinforced polymer-derived SiC composites with low shrinkage and high strength

The chopped carbon fiber reinforced SiC (Cf/SiC) composite has been regarded as one of the excellent high-temperature structural materials for applications in aerospace and military fields. This paper presented a novel printing strategy using direct ink writing (DIW) of chopped fibers reinforced polymer-derived ceramics (PDCs) with polymer infiltration and pyrolysis (PIP) process for the fabrication of Cf/SiC composites with high strength and low shrinkage. Five types of PDCs printing inks with different Cf contents were prepared, their rheological properties and alignment of carbon fiber in the printing filament were studied. The 3D scaffold structures and bending test samples of Cf/SiC composites were fabricated with different Cf contents. The results found that the Cf/SiC composite with 30 wt% Cf content has high bending strength (∼ 7.09 MPa) and negligible linear shrinkage (∼ 0.48%). After the PIP process, the defects on the Cf/SiC composite structures were sufficiently filled, and the bending strength of Cf/SiC composite can reach up to about 100 MPa, which was about 30 times greater than that of the pure SiC matrix without Cf. This work demonstrated that the printed Cf/SiC composites by using this method is beneficial to the development of the precision and complex high-temperature structural members.