Fiber-orientation controlled C f /SiC composites with anisotropic thermal conductivity via additive manufacturing and reactive melt infiltration

Manipulation of fiber alignment provides an effective means of tailoring the directional thermal transport properties of Cf/SiC composites. However, maintaining the designed fiber orientation during subsequent high-temperature densification remains challenging, particularly during silicon infiltration, where molten Si can strongly react with Cf. Here, fiber-orientation-controlled Cf/SiC composites were fabricated by combining selective laser printing, polymer infiltration and pyrolysis processing, and reactive melt infiltration. During laser printing, roller-induced shear forces promoted the in-plane alignment of high aspect ratio Cf, establishing a preferential fiber orientation within the printed body. Subsequent infiltration and pyrolysis of polycarbosilane and phenolic resin formed a protective layer around the fibers, mitigating their reaction with molten Si. The resulting composites exhibited a fiber orientation factor of 0.7789 and a bulk density of 2.87 ± 0.04 g·cm−3, with a flexural strength of 268.1 ± 15.3 MPa along the preferred direction. The preserved fiber orientation led to direction-dependent thermal transport, with a thermal conductivity of 130.1 W·m−1·K−1 along the preferred direction and a thermal anisotropy ratio of 1.5. These results demonstrate that combining additive manufacturing with interfacial protection and RMI provides an effective strategy for preserving designed fiber alignments while achieving highly densified Cf/SiC composites with anisotropic thermal transport.