Binder jetting 3D printing preparation of SiC ceramics with low free silicon content and densification by PIP and LSI process

Silicon carbide ceramic (SiC) composites were prepared using a combination of binder injection (BJ), impregnation pyrolysis (PIP), and liquid silicon infiltration (LSI) processes. The study investigated the effects of various carbon sources and PIP cycles on the properties of green bodies, preforms, and composites. Experiments revealed that the introduction of graphite and carbon black as carbon sources facilitated the subsequent LSI process. However, the addition of graphite and carbon black led to a reduction in the density and strength of the green body. Notably, the carbon black-doped sample (C10) exhibited the highest strength (3 ± 0.13 MPa) and density (53 ± 0.13 g/cm 3 ). The incorporation of SiC through polycarbosilane PIP effectively addressed the issue of insufficient green body density. Following LSI treatment, the C10 sample's strength was significantly higher than that of C0 and C5, due to the influence of the green body. After three PIP cycles, the flexural strength of 3D-printed SiC (3D-SiC) reached its peak value (277 ± 10.2 MPa), primarily because of its lower residual silicon content (10.28 vol%) and residual carbon content (1.36 vol%). This research demonstrates the feasibility of optimizing 3D-SiC ceramics by precisely controlling the number of carbon sources and PIP cycles.Through this process, SiC ceramic matrix composites (CMCs) with complex structures and high strength have been fabricated, which could be applied to lightweight thermal protection structures in the aerospace field, complex chemical ceramic pump blades, and high-precision optical equipment.