Fabrication and mechanical properties of diamond/SiC composites via gel-casting and Si infiltration

The fabrication of complex-shaped diamond/SiC composites with high solid loadings remains a formidable challenge. This study introduces a gel-casting combined with silicon infiltration strategy that overcomes this hurdle through precise colloidal design and rheological control of aqueous diamond/SiC suspensions. The synergistic electrostatic stabilization yielded a zeta potential of −75 mV, enabling high-solid-loading (65 vol%) slurries with optimal casting behavior. The resulting composites exhibited excellent mechanical properties, with flexural strength and elastic modulus reaching 420.2 MPa and 578.6 GPa, respectively. These values corresponded to 84.5% and 34.0% enhancements over a reference reaction-bonded silicon carbide (RB-SiC) composite at identical overall solid loading. This leap is underpinned by a significant fracture mechanism transition to transgranular diamond cleavage, consistent with strong interfacial bonding. This work establishes a practical route for manufacturing high-performance diamond/SiC composites.