Rheology, Stability, and Photosensitivity of SiC Slurry by Triblock Copolymer Dispersant and Particle Size Grading

Abstract

The formulation of photosensitive SiC slurry with high solid loading, low viscosity, and long‐term stability remains a critical challenge. Herein, a triblock copolymer of poly(ethylene glycol)–block–poly(propylene glycol)–block–poly(ethylene glycol) (PEG–PPG–PEG) was employed as a kind of dispersant to modulate the wettability of SiC particle surfaces through hydrogen‐bonding anchoring interactions. The results demonstrate that with the addition of 6 wt % PEG–PPG–PEG, the slurry viscosity reaches a minimum, and the retained sedimentation height after 96 h is as high as 86%, indicating pronounced shear‐thinning behavior and excellent long‐term stability. Furthermore, fine SiC particles were incorporated to construct a particle size grading system, and the effects of particle size grading on slurry stability, rheological properties, and photosensitive properties were systematically investigated. Through the optimized debinding and liquid silicon infiltration (LSI) processes, the fabricated SiC ceramic achieves a density of 2.76 ± 0.01 g/cm3, a flexural strength of 198.21 ± 5.04 MPa, and a Vickers hardness of 27.95 ± 1.66 GPa. A honeycomb‐structured space mirror, printed using the bimodal slurry, exhibits superior surface quality after polishing and delivers clear, undistorted imaging. This work provides a novel strategy and theoretical foundation for enhancing the printability of high‐solid‐loading SiC slurry.