Low-Emitting Property of Lanthanum Aluminate and Its Application in Infrared Stealth

A Multilayer Film Based Selective Thermal Emitter for Infrared Stealth Technology

“…The thermal radiation energy, defined as the radiance exitance P , radiated from an object can be suppressed by both reduction of the emissivity and the real temperature, according to the Steven–Boltzmann Law, P = εσT 4 , where σ is the Steven–Boltzmann constant and ε and T are the emissivity and absolute temperature of the object, respectively. Reducing the emissivity ε is a typical solution for infrared stealth . Unfortunately, the poor efficiency in thermal radiation, caused by the low emissivity, leads to a sharp rise in the real temperature T , thus enhancing the radiative energy and weakening the stealth performance.…”

Lightweight, Flexible, and Covalent-Bonding Phenolic Fabric Reinforced Phenolic Ablator for Thermal Insulation and Conformal Infrared Stealth

“…The object with a higher temperature than that of the background can be easily detected by a thermal infrared camera, according to the Stefan–Boltzmann law W = εσ T , wherein W is the emission energy, ε is the infrared emissivity, σ is the constant of Stefan–Boltzmann, and T is the absolute temperature. , Therefore, metal materials with low infrared emissivity and high infrared reflectance like Al and Ag and thermal insulative materials able to decrease the absolute temperature are often employed for infrared stealth or infrared camouflage. Unfortunately, the high density and the melting behavior at high temperatures of metals restrict their independent applications, thereby metal foils or plates are always combined with porous thermal insulative materials for the purpose of both lightweight and temperature reduction. − Distinctive from the current strategies with rigid materials, our flexible and thermal insulative PRF/SPRA was combined with an Al panel with a thickness of 0.2 mm for both complanate and conformable infrared camouflage.…”

Preparation of Flexible Wavelength-Selective Metasurface for Infrared Radiation Regulation

“…Conventional infrared camouflage techniques are based on low-emissivity coating materials, which obtain low detectability via their low emittance in the whole band (3–14 μm). − Such materials hold a series of advantages, such as low consumption, straightforward manufacturability, and prominent fitness, making them particularly promising in conventional camouflage techniques. − However, radiative heat transfer will be blocked in traditional infrared camouflage with broad-band low emittance, introducing heat instability. , To mitigate the severe heat instability and reduce surface temperature, high emissivity is required in the nonatmospheric window 5–8 μm for radiative cooling, , and many wavelength-selective metasurfaces that could achieve thermal regulation by transferring the radiation in the atmospheric windows to 5–8 μm band have been proposed. − For instance, Liu et al designed and fabricated a broadband absorber by employing an Fabry–Perot resonator on top of a narrowband metal-disk-array absorber. The metasurface could realize high emissivity in the 5–8 μm range as well as low emissivity in the 3–5 and 8–14 μm ranges, which satisfied both infrared suppression and radiative cooling.…”

“…10−15 However, radiative heat transfer will be blocked in traditional infrared camouflage with broad-band low emittance, introducing heat instability. 8,9 To mitigate the severe heat instability and reduce surface temperature, high emissivity is required in the nonatmospheric window 5−8 μm for radiative cooling, 10,11 and many wavelength-selective metasurfaces that could achieve thermal regulation by transferring the radiation in the atmospheric windows to 5− 8 μm band have been proposed. 16−20 For instance, Liu et al 21 designed and fabricated a broadband absorber by employing an Fabry−Perot resonator on top of a narrowband metal-diskarray absorber.…”