Template-engineered 3D porous C/TiC(ZrC) ceramics with decoupled impedance matching and dissipation for thickness-adaptive microwave absorption

Practical microwave absorbers for stealth applications require strong absorption, broad bandwidth, and high performance across a wide thickness range. Herein, two types of 3D porous C/TiC(ZrC) ceramics were fabricated using different porous carbon skeletons derived from melamine foam and cellulose nanofiber aerogel templates, followed by SiOC coating to further tailor the electromagnetic parameters. By tuning the carbon network continuity and carbide phase (TiC, ZrC), extended matching thickness ranges for effective absorption (RL < −10 dB) across the X-band were achieved. Results indicate that the cellulose-derived C-C/ZrC ceramic demonstrates an exceptionally wide matching thickness range of 3.96–5.20 mm with a minimum RL of −18.6 dB. This exceptional thickness-adaptive absorption originates from the low and frequency-stable permittivity of the C-C/ZrC composite, which enables continuous quarter-wavelength impedance matching across a broad thickness range. This behavior is underpinned by a multi-scale synergistic effect involving moderate conductive loss, strong interfacial and dipolar polarization at multiple heterointerfaces, and enhanced multiple scattering within the hierarchical porous architecture. This work establishes a template-driven strategy for decoupling impedance matching from dissipation, offering a new paradigm for designing thickness-adaptive microwave absorbers.