Low-cost flexible film achieves infrared stealth
Described in the ACS nano letter under the title “Nanofibrous Kevlar Aerogel Films and Their Phase-Change Composites for Highly Efficient Infrared Stealth”, the KNA/PCM composite film is said to exhibits a high thermal management capability and an infrared emissivity comparable to that of various backgrounds, which could be used to hide hot targets from IR detection e.g. infrared stealth. Because the KNA/PCM composite has an ultra-low IR transmittance, it can cloak a hot target and make it undistinguishable from its surroundings in infrared images.
Without requiring any power supply or any active cooling, the flexible stealth film combines the Kevlar nanofibers aerogel’s good insulating properties with the temperature-damping effect of polyethylene glycol (PEG) coated on the aerogel’s porous structure. PEG stores heat when it melts and releases heat when it solidifies, which damps any temperature variations and averages out the stealth film IR signature within the range of its surroundings.
In simulated sunlight, the composite film covering an object soaked up heat from the sun while only slowly increasing in temperature, just like the surroundings, making a shielded object invisible to a thermal camera. When the light is turned off, the coating gradually surrenders its stored heat energy to match its surroundings. The PEG composite film was demonstrated to effectively hide hot targets from a thermal camera, which could have applications in the military.
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