Additive manufacturing of oriented chopped carbon fiber reinforced mullite refractory via extrusion-based technique- Effects of slurry rheological behavior and 3D printing parameters

This study investigated the fabrication of oriented chopped carbon fiber-reinforced mullite-based refractory using extrusion-based 3D printing technology. Dispersants were incorporated into the printing paste to optimize its rheological properties. The effects of carbon fiber content on paste rheology and castable flowability were also evaluated. At dispersant and carbon fiber contents of 0.2 wt% and 0.3 wt%, respectively, the paste exhibited pronounced shear thinning behavior and notable structural recovery, significantly enhancing its printability. Furthermore, precise adjustments in air pressure and layer height, along with an analysis of shear rate distribution during printing, contributed to improved structural accuracy of the printed bodies. Post-printing, the chopped carbon fibers were oriented in the mullite matrix. Following sintering, the flexural strength of the 3Dprinted specimens increased from 6.1 MPa to 6.7 MPa, with concurrent improvements in fracture toughness compared to carbon fiber-reinforced mullite refractory specimens produced by casting.