Uniform filling process of ultra-lightweight RGO-based aerogel for achieving broadband microwave absorption in aramid honeycomb

The use of microwave absorption (MA) materials in practical aerospace applications would be challenging without a dependable mechanical support structure. However, achieving a wide effective absorption bandwidth (EAB) in aramid honeycomb structures at low weight gain is crucial for the practical aerospace applications of MA materials. To address this challenge, this study proposes a combination of porous carbon foam and high structural strength honeycomb to achieve broadband microwave absorption in structural devices through the synergistic effect of carbon foam absorption and honeycomb structure. The uniform filling process of ultra-lightweight reduced GO aerogel is achieved through freeze-drying, solving the issues of uneven dispersion and incomplete filling of traditional absorbers in honeycombs. Further optimization and comprehensive evaluation of filling concentration and reduction process were carried out. The freeze-drying process combined with chemically reduced honeycomb samples filled with different concentrations of GO all exhibit broadband absorption performance. At a specific standard honeycomb thickness of 15 mm, uniformly filled honeycomb samples with 0.1 to 0.3% GO exhibit triple resonance peaks near 2-3 GHz, 8-9 GHz, and 15 GHz, with effective absorption peaks all below - 10 dB. Moreover, the incorporation of transparent wave honeycomb walls in conjunction with honeycomb materials enhances the overall impedance matching, leading to a further improvement in the EAB to 10.53 GHz for the honeycomb sample filled with 0.2% freeze-dried and reduced GO. CST simulation data confirms that the loss in the honeycomb samples originates from uniform conduction loss, and the electric field stably enters the interior of the honeycomb. This approach, based on the rapid and efficient filling of uniform RGO by freeze-drying, provides a new way to achieve broadband microwave absorption in aramid honeycombs and has significant potential for development in the field of aerospace stealth.