Kevlar airgel film prepared with fellow team Zhang, can realize the infrared stealth

According to Stefan-Boltzmann\’s law, and the emission of radiant energy per unit area is proportional to the fourth ratio and the thermodynamic temperature. Thus, infrared camouflage can be achieved by adjusting the temperature-controlled or infrared emissivity. For example, manufacturing a microstructure having a special surface can be changed infrared emissivity of the target, but does not impart a microstructure infrared emissivity of the target adjustable. Quantum wells, electrochromic dye, phase change material or the like can dynamic control of infrared radiation, however, usually require continuous power during the tuning process, and a slow response speed, a narrow tuning range, poor flexibility. Further, by regulating the temperature infrared camouflage can be achieved, however, thermal blankets and other materials are generally relatively heavy, easily lead to heat build-up. Visible, effectively hiding the target, it is not visible to the thermal infrared detectors still faces enormous challenges. Suzhou Institute of Nanotechnology and Nano-bionics, CAS Zhang airgel team led by the same researcher prepared having a high porosity (98%) and high specific surface area (365.99 m2 / g) is a flexible airgel film, by dissolving DuPont Kevlar (TM) nano-fiber obtained sol, then knife coating, by sol – gel process and the subsequent freeze-drying to obtain airgel film Kevlar. The airgel has excellent heat insulating properties, at room temperature, a thermal conductivity of about 0.036 W / m · K, 200μm thick airgel film over the heat source to 300 ° C, the surface temperature of only airgel 220 ° C, the temperature difference reached 80 ° C. And polyethylene glycol complex phase change material and the hydrophobic treatment, was prepared airgel / phase change composite film, composite film of the phase change: (1) a phase change enthalpy of up to 179.1 J / g; (2) with infrared emissivity most environmental context matching; (3) with ultra-low infrared transmittance in the infrared band 3μm-15μm. In outdoor environments (e.g., light), covering an object with a non-heat the composite film, can realize the infrared stealth. Continued heating the object (such as engine), airgel insulation layer is proposed in combination with the structural phase transition superposed composite film: Kevlar airgel film having excellent heat insulating properties, depending on the temperature difference between the target and the environment, select suitable airgel layer thickness or number of layers, the temperature can be lowered to match the ambient temperature; phase-change composite film having a low infrared transmittance, the infrared light emitted can not be the target temperature transmission. Thus covering the objectives of this high-temperature composite structure in the infrared photographs can also be achieved Infrared Stealth.The airgel usage scenario, a matched / phase change composite film or a composite structure, to achieve infrared stealth , as shown in FIG. Relevant research results to \”Nanofibrous Kevlar Aerogel Films and Their Phase Change Composites for Highly Efficient Infrared Stealth\” in the title, has been published online in the international journal \”ACS Nano\” (ACS Nano 2019,13,2236? 2245), and was named ACS Editors\’ Choice Article. American ACS News Service Weekly PressPac to \”Now you see heat, now you do not\”, carried a report for the title. https://www.acs.org/content/acs/en/pressroom/presspacs/2019/acs-presspac-february-27-2019/now-you-see-heat-now-you-dont.html American Chemical & Engineering News , C & EN referred to \”Packable Kevlar cloak provides infrared stealth across changing temperatures\” in the title were reported. https://cen.acs.org/materials/coatings/Packable-Kevlar-cloak-provides-infrared/97/web/2019/02 US Optics & Photonics News to \”A flexible way to hide the heat\” were reported in the title. https://www.osaopn.org/home/newsroom/2019/march/a_flexible_way_to_hide_the_heat /? tdsourcetag = s_pcqq_aiomsg