High-temperature electromagnetic absorption and multi-physics coupling simulation of ceramizable composites

High-temperature electromagnetic wave absorbing materials are crucial for electromagnetic protection and military stealth. Ceramizable composites are promising candidates for integrating microwave absorption, load-bearing capacity, and thermal protection in multi-field coupling environments; however, their high-temperature electromagnetic response remains poorly understood. This study presents the first systematic investigation of the effects of pretreatment temperature and in situ test temperature on electromagnetic wave absorption of quartz fabric-reinforced phenolic-based ceramizable composites. Experimental results show that increasing pretreatment temperature to 800 °C promotes pore development and heterogeneous interfaces, raising the average X-band reflection loss (RL) from −2 dB to −8 dB. Complete ceramization at 1100 °C forms a stable ZrO₂/Al₂O₃ ceramic skeleton, achieving a minimum RL of −10 dB. For fully ceramized specimens, absorption first improves with test temperature up to 400 °C (RL ≈ −12 dB) due to activated polarization, then declines slightly at 600 °C owing to excessive thermal perturbation. To enable performance prediction, a thermal–chemical–electromagnetic multi-physics coupled simulation framework is established, based on thermogravimetric analysis and reaction kinetics. By mapping reaction progress to complex permittivity, the model successfully predicts RL under various service conditions and reveals parametric sensitivities of thickness, oxygen concentration, and holding time. This work provides a unified experimental and theoretical basis for the design of high-temperature microwave absorption materials.