Large-scale material extrusion-based additive manufacturing of short carbon fibre-reinforced silicon carbide ceramic matrix composite preforms

Large-scale short carbon fibre-reinforced silicon carbide (C_sf/SiC) ceramic matrix composites (CMCs) have important applications in the field of aerospace engineering. This study proposed the use of material extrusion based additive manufacturing to fabricate large-scale C _sf/SiC CMC preforms. In this paper, we determined how the key material extrusion parameters, including solid loading, nozzle diameter and layer height impact the stability of the additively manufactured C _sf/SiC CMCs. The solid loading significantly influenced the stability of the C _sf/SiC CMCs, and the slurry with 50 vol.% solid loading was better for additive manufacturing. The layer height played a significant role in the void formation in CMCs. It was appropriate for structure retention to set the layer height as 60–75% of the nozzle diameter. The effect of angle from vertical on the stability of out-of-plane structure was also investigated. When the angle was over 40^o, the out-of-plane structure additively manufactured without supports tended to collapse. Large-scale C _sf/SiC CMC preforms with out-of-plane structures were finally successfully fabricated. This study is believed to provide some fundamental understanding for the fabrication of large-scale fibre-reinforced ceramic matrix composites.