Rheology and printability of the ZrO2@C microsphere paste for the fabrication of ZrC ceramics by direct ink writing

ZrO 2 @C spherical powder was synthesized via a solvothermal method and utilized in the fabrication of ZrC ceramics through direct ink writing (DIW) to enhance rheological properties and reduce sintering temperature. The effects of solid content on the rheological behavior and printability of the ZrO 2 @C paste were systematically investigated. The ZrO 2 @C paste exhibited typical pseudoplastic fluid characteristics and viscoelastic properties, demonstrating excellent shape retention and shear-thinning behavior. Optimal solid content and printing speed were determined to be 54 wt% and 100 mm/s, respectively, leading to superior printability. Using these optimized parameters, green bodies with planar and lattice structures were rapidly and precisely fabricated. After reactive sintering at 1600 °C, the resulting ZrC ceramic achieved a promising bending strength of 30.9 MPa. This study provides a robust strategy for the rapid fabrication of ultrahigh-temperature ceramics with complex geometries.