Multi-interface synergistic regulation of strength and toughness in additive manufacturing C_f/SiC

This work combines selective laser sintering (SLS) and reactive melt infiltration (RMI) to fabricate short carbon fiber reinforced ceramic matrix composites (C_f/SiC). Pyrolytic carbon and ceramic coating layers are prepared on the exposed fiber surface via a gas/liquid phase method, effectively shieling the fibers from molten silicon erosion. The study examines the process and mechanism of densification, regulation of toughness and strength and multi-interface synergistic mechanism. The results show that SiC coatings promote high-density composites due to their good wettability with molten silicon. CVI-SiC provided the best encapsulation, preventing silicon infiltration and only slightly increasing fiber elastic modulus and nano-hardness. The PyC layer thickness of approximately 200 nm allowed the fibers to effectively enhance and toughen the material. The composite exhibited optimal bending strength (279.1 MPa), density (2.70 g/cm³), and fracture toughness (3.30 MPa·m^1/2). This approach offers a promising strategy for additive manufacturing of high-strength, high-toughness and complex-structured C_f/SiC composites.