Fiber-laying-assisted material extrusion additive manufacturing of continuous carbon fiber reinforced SiC ceramic matrix composites

A novel fiber-laying-assisted method for the additive manufacturing of continuous carbon fiber reinforced SiC (C_f/SiC) ceramic matrix composites was proposed. A fiber-laying-assisted material extrusion (ME) additive manufacturing system was developed to enable the introduction of continuous carbon fiber in ceramic components during the part fabrication. In this process, SiC slurry was extruded through a nozzle to build the SiC matrix layer-by-layer. In the case of continuous carbon fiber introduction, the fabrication process was halted after a certain layer was deposited; the continuous carbon fibers were placed in their predetermined locations by the fiber-laying system; and the remaining layers were deposited until the part fabrication was completed. Because the continuous carbon fibers were embedded during the fabrication process, they were fully integrated with the SiC matrix and the problems of traditional continuous fiber introduction could be eliminated. Then, the C_f/SiC green parts were densified by precursor infiltration and pyrolysis (PIP), and the final C_f/SiC composites were obtained. The effects of spacing between neighbor continuous carbon fibers on the microstructure and mechanical properties of C_f/SiC composites were also studied. When the spacing between neighbor continuous fibers was 5.0 mm, the C_f/SiC composite had a maximum bending strength of 217.16 MPa and a maximum fracture toughness of 13.55 MPa m^1/2. The continuous carbon fibers improved the fracture toughness of C_f/SiC composites, which was about 3 times better than that of the SiC ceramics without fibers. This work unravels the potential of additive manufacturing of continuous carbon fibers into ceramics.