One-step gaseous silicon infiltration fabrication of matrix-coating integrated C/C-SiC-Si composites against oxidation at 1300–1700°C

To overcome the limitations of carbon/carbon (C/C) composites in long-term applications across a wide temperature range (1300–1700 °C), an integrated oxidation protection strategy has been developed through a one-step gaseous silicon infiltration (GSI) process, incorporating matrix modification and surface coating. This process leverages the high permeability of gaseous Si to simultaneously densify the porous matrix and in situ grow a SiC-Si protection system. The resulting C/C-SiC-Si composite demonstrates a service life exceeding 502 h at 1300and 1500 °C, and 149 h at 1700 °C. Crucially, after oxidation testing, the material retains a complete load-bearing structure and maintains over 54% of its original flexural strength (196 MPa). The superior performance is attributed to the continuous anti-oxidation network. This creates a mechanically interlocked interface between the coating and substrate, increasing the bonding strength by 31%, and establishes a continuous thermal expansion coefficient gradient that effectively mitigates thermal mismatch.