# From Complex Shaping to Mirror Finish: Additive Manufacturing of Aerospace‐grade Cf/SiC Space Optics

## TL;DR

A new additive manufacturing method creates lightweight, strong, and smooth ceramic composites for space mirrors, combining 3D printing with advanced surface treatments.

## Contribution

A hybrid additive manufacturing route for aerospace-grade Cf/SiC composites with engineered interphases and thin-film finishing.

## Key findings

- The method achieves benchmark mechanical robustness for Cf/SiC composites.
- Ultrasmooth surfaces with high visible-band reflectivity are produced via physical vapor deposition.
- The approach enables systematic optimization of geometric formability and optical performance.

## Abstract

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 (Cf/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 Cf/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 Cf/SiC substrate. It establishes a scalable paradigm for Cf/SiC space mirrors while positioning interface‐engineered fabrication as a pathway for next‐generation multifunctional ceramic composites in aerospace environments.

An integrated additive manufacturing route combines selective laser sintering, engineered interphases, and optimized silicon infiltration to fabricate complex Cf/SiC composites. The approach enables precise shaping, high mechanical performance, and excellent optical reflectivity, offering a scalable solution for advanced aerospace optics with both structural robustness and surface smoothness.