Zhaozhou Bridge inspired embedded material extrusion 3D printing of C_sf/SiC ceramic matrix composites

Material extrusion (MEX) 3D printing, while effective for many applications, faces challenges in fabricating arch shapes and suspended structures. This study advances MEX technology by drawing inspiration from ancient bridge construction techniques like the Zhaozhou Bridge, using an innovative embedded material extrusion (EMEX) method that eliminates the need for additional support structures in fabricating complex short carbon fiber reinforced SiC ceramic matrix composites (C_sf/SiC CMCs). Utilizing solid powders as a supporting medium, EMEX enables the creation of intricate arch shapes and suspension structures, overcoming limitations associated with conventional MEX. The impact of supporting media (SiC powders and sugar) on the microstructure and mechanical properties of the composites was demonstrated. Residual SiC powders caused uneven material distribution, while residual sugar led to cracking. The presence of residual powders also influenced the shrinkage behavior and bending strength of the C_sf/SiC CMCs, with a notable decrease observed when transitioning from air to SiC powders and then to sugar as the printing environment. The successful fabrication of C_sf/SiC CMCs with complex geometries using EMEX indicates its potential as a promising supportless strategy for producing sophisticated CMC structures.