Influence of slurry and injection methods on the fabrication of C_f/ZrB₂-SiC composite via slurry injection and RMI

To address the issues of long preparation cycle and high cost in fiber-reinforced ultra-high temperature ceramic matrix composites, C_f/ZrB₂-SiC composite was prepared by slurry injection combined with reactive melt infiltration (RMI). The dispersion and rheological behavior of slurries with different compositions were investigated, as well as the impact of various slurries and injection methods on the three-dimensional filling of porous C_f/ZrB₂-C composite. The porosity of porous C_f/ZrB₂-C composite was 24.4–37.2% and the bulk density was 1.70–2.36 g/cm³ after injection and infiltration. The porous C_f/ZrB₂-C composite obtained by double-sided injection has uniform distribution of ceramic phase, and the bulk density and open porosity are 2.36 g/cm³ and 24.4% when the ceramic content is 70 wt.% in slurry. Additionally, the volume filling rate has increased by 32% compared to single-injection. After 1 h of silicon infiltration at 1450°C, the flexural strength and fracture toughness of the C_f/ZrB₂-SiC composite were 188.8 MPa and 5.51 MPa·m^1/2. Compared with other RMI processes, this study showed no significant damage to carbon fibers after low-temperature silicon infiltration, and has certain advantages in mechanical properties. It achieved uniform high solid-content ZrB₂ incorporation and rapid densification, enabling cost-effective short-cycle fabrication of C_f/ZrB₂-SiC composite.