Additive manufacturing of complex-shaped SiC/Al composites via digital light processing with controlled interfacial oxide and enhanced mechanical properties

High-volume fraction SiC/Al (HVF-SiC/Al) composites offer exceptional specific strength, stiffness, and thermal conductivity, making them highly desirable for advanced structural applications. Nevertheless, their extreme hardness and poor machinability have persistently hindered the fabrication of components with complex geometries. In this work, a novel manufacturing strategy that integrates digital light processing (DLP) of SiC preforms with vacuum pressure infiltration (VPI) of aluminum alloy is presented to overcome this challenge. A carefully designed one-step debinding and sintering process in the air was developed to maintain the structural integrity of the complex-shaped SiC green bodies. An optimal porous SiC preform was obtained using a debinding heating rate of 0.3 °C/min followed by sintering at 1350 °C for 1 h. Critically, the sintering step engineered a uniform, in-situ SiO₂ layer on the SiC surfaces. During molten Al infiltration, this layer acted as a diffusion barrier, effectively suppressing the formation of brittle Al₄C₃ and facilitating the formation of a continuous ~600 nm Al₂O₃ interface. The resultant controlled interfacial structure achieved outstanding mechanical properties, with an average flexural strength of 417.52 MPa and an elastic modulus of 176.93 GPa, which surpass those of most HVF-SiC/Al composites. The effectiveness of this approach is further demonstrated by the successful fabrication of a complex-shaped SiC/Al component. This work provides an effective pathway for fabricating complex-shaped, high-performance metal-ceramic composites.