Percolation Threshold-Driven Dual Dissipation Channels in SiO–Graphitic Carbon–Paraffin Composites: Synchronous Optimization of Interfacial Polarization and Conductive Networks for Tailorable Microwave Absorption

Herein, a percolation threshold-driven dual dissipation mechanism is revealed in SiO–graphitic carbon–paraffin composites, where the percolation threshold acts as a “polarization efficiency peak” to synergistically optimize microwave absorption. By tuning filler loadings (40–70 wt %), the correlation between structural evolution (isolated → quasi-connected → agglomerated networks) and absorption performance is systematically investigated. Structural characterizations confirm a core–shell SiO–graphitic carbon architecture with Si–O/Si–C interfacial bonds, which enhance interfacial polarization. Electromagnetic analysis shows that the percolation threshold at 60 wt % balances interfacial polarization and conductive loss: this quasi-connected conductive network achieves an optimal reflection loss of −25.63 dB at 8.32 GHz and an effective absorption bandwidth of 5.45 GHz at a thickness of 1.9 mm. Below 60 wt %, isolated particles limit conductive loss despite dominant polarization; above 60 wt %, agglomeration reduces interfacial area, diminishing polarization efficiency even with enhanced conductance. Radar cross-section simulations verify 98.3% radar scattering reduction compared to a perfect electric conductor, confirming the stealth potential. This study establishes a “structural regulation–relaxation–absorption” relationship based on the percolation threshold, providing a theoretical basis for the design of broadband, low-carbon-content microwave absorbers.