Multilevel structure carbon aerogels with 99.999 % electromagnetic wave absorptivity at 1.8 mm and efficient thermal stealth

Abstract

Given the complex practical environment and application fields, it is urgent to integrate various functions into one material. Based on the introduction of nano-sites, the creation of multilevel structures synergy, a light weight electromagnetic wave-infrared stealth compatible composite was prepared for the first time. In which the multi-contact sites and interfaces greatly limited the thermal conduction and enhanced the synergistic polarization. Moreover, the gold nanoparticles with low emissivity not only reduced the external thermal radiation, but also promoted the conduction loss. Optimized composites showed excellent thermal stealth and ultra-high electromagnetic wave absorption (EMA) performance. The difference between the surface and the ambient background temperature was less than 5 °C when the target temperature was 120 °C, thus the detection distance of the infrared system to the target would be effectively reduced. The products provided a minimum reflection loss of −55.9 dB with a thickness of only 1.8 mm, and an ultra-wide effective absorption bandwidth of 16 GHz within 1–5 mm. Surprisingly, in the far-field condition, the minimum radar cross section value can achieve −49 dB m2. This work provides valuable insights for synthesizing functional materials with excellent EMA and thermal stealth properties.