Additive manufacturing of continuous carbon fiber-reinforced silicon carbide composite by fused filament fabrication and precursor infiltration pyrolysis

Continuous fiber reinforced silicon carbide composites (Cf/SiC) are known for their advantages such as high strength, high modulus, high thermal conductivity, and low density. In this paper, we propose an integrated Cf/SiC preparation and processing process. The continuous carbon fiber-reinforced resin matrix composite green parts were processed by fused filament fabrication, and then ceramicized by precursor infiltration pyrolysis process. The processing parameters of the green parts, the performance of the green-part specimens, the phase evolution in the post treatment, and the performance of Cf/SiC samples were investigated. The infill line distance (ILD) had a huge influence on the mechanical properties of green parts and Cf/SiC. The bending strength of the green parts and the Cf/SiC specimens increased with the decrease in ILD. The maximum bending strength of 169.48 MPa and 155.83 MPa was achieved for the carbon fiber/polyethylene terephthalate glycol (Cf/PETG) and polylactic acid (Cf/PLA) green parts, respectively. The highest bending strength of 47.73 MPa of the Cf/SiC material was obtained with the Cf/PLA green parts, while the bending strength of 93.79 MPa was obtained for the Cf/SiC with Cf/PETG green parts. The increase in mechanical properties was believed to result from the pyrolyzed carbon brought by PETG and the increase of the equivalent fiber density within the single layer after a larger nozzle size was used.