Abstract: Reaction-bonded silicon carbide (RB-SiC) ceramics typically exhibit limited thermal conductivity due to excessive residual silicon (Si) content and coarse Si pockets. To address this challenge, a homogeneous mesoporous carbon network was constructed in SiC/C preform as an alternative to conventional carbon black. Utilizing resorcinol-formaldehyde polycondensation and pyrolysis, a 3D mesoporous carbon architecture with a small pore size and high specific surface area of 116 m2/g was engineered. RB-SiC ceramics were subsequently fabricated via vacuum melt infiltration at 1650 °C. The mesoporous carbon network optimizes reaction melt infiltration kinetics, yielding three critical microstructural improvements: (1) Residual Si content decreased from 22.8 to 16.8 vol.%, with Si refined to submicron particles; (2) Heterophase boundary density and lattice misorientation at Si/SiC interfaces were reduced, alleviating thermal stress; (3) Oxygen-containing SiOxCy impurities were minimized (oxygen content reduced from 0.11 to 0.05 wt.%) due to enhanced reducibility of native SiO2 impurities in SiC raw material. Consequently, these microstructural refinements effectively suppressed phonon scattering, resulting in a significant 53 % increase in thermal conductivity from 99 to 151 W/(m K). This work demonstrates the feasibility of tailored mesoporous carbon architectures for advancing high-thermal-conductivity RB-SiC ceramics.

Key words: Reaction-bonded silicon carbide, Mesoporous carbon, Residual silicon, Microstructure, Thermal conductivity