From Complex Shaping to Mirror Finish: Additive Manufacturing of Aerospace-grade C_f/SiC Space Optics

Among additive manufacturing strategies, selective laser sintering (SLS) enables complex, resource-efficient architectures, yet its application to aerospace-grade ceramic composites is hindered by high sintering activation energies and fragile interfacial bonding. Herein, a hybrid route is established that couples SLS preform fabrication with interface-engineered densification and thin-film finishing, using carbon-fiber reinforced silicon carbide (C_f/SiC) as a model for lightweight space mirrors. To overcome the inherent limitations of conventional liquid silicon infiltration (LSI), a deliberately engineered pyrolytic carbon (PyC) interphase is introduced ex situ through phenolic-resin infiltration and controlled pyrolysis, establishing an interface-design strategy that stabilizes fiber-matrix interactions while enabling efficient load transfer and thermal transport. The resulting C_f/SiC exhibits benchmark mechanical robustness for this materials class. Physical vapor deposition (PVD) of dense Si and Ag films yields an ultrasmooth surface (0.031 λ in roughness) with high visible-band reflectivity. By integrating additive shaping with interphase-assisted densification and thin-film finishing, this route enables systematic optimization of geometric formability and optical performance, with roughness and visible-band reflectance set by the optical film stack and structural support from the C_f/SiC substrate. It establishes a scalable paradigm for C_f/SiC space mirrors while positioning interface-engineered fabrication as a pathway for next-generation multifunctional ceramic composites in aerospace environments.