High-temperature infrared camouflage with efficient thermal management

Abstract

High-temperature infrared (IR) camouflage is crucial to the effective concealment of high-temperature objects but remains a challenging issue, as the thermal radiation of an object is proportional to the fourth power of temperature (T 4). Here, we experimentally demonstrate high-temperature IR camouflage with efficient thermal management. By combining a silica aerogel for thermal insulation and a Ge/ZnS multilayer wavelength-selective emitter for simultaneous radiative cooling (high emittance in the 5-8 μm non-atmospheric window) and IR camouflage (low emittance in the 8-14 μm atmospheric window), the surface temperature of an object is reduced from 873 to 410 K. The IR camouflage is demonstrated by indoor/outdoor (with/without earthshine) radiation temperatures of 310/248 K for an object at 873/623 K and a 78% reduction in with-earthshine lock-on range. This scheme may introduce opportunities for high-temperature thermal management and infrared signal processing.

Kirchhoff’s Thermal Radiation from Lithography-Free Black Metals

“…The IR emission of hot photo-excited electrons into the IR absorption band of photo-polymerisable resists is shown to contribute to 3D polymerisation when ultra-short laser pulses are used [ 49 ]. Another promising area of application is in camouflage [ 50 , 51 , 52 ], where hiding thermal signatures of objects at the air transparency window while re-radiating heat via black body emission at a different spectral range can benefit from the presented simple multi-layer coatings. In addition, thermo-electrical energy harvesting combined with semiconductor solar cells can benefit from broad band engineering of absorbance and reflectivity [ 53 ].…”

Multispectral camouflage for infrared, visible, lasers and microwave with radiative cooling

“…To satisfy the requirements of multispectral camouflage, the spectral properties of the device should be: (i) low emittance in the MIR atmospheric windows i.e., mid-wavelength infrared (MWIR) 3–5 μm and long-wavelength infrared (LWIR) 8–14 μm against thermal imagers and heat-seeking missiles 19 – 26 ; (ii) characteristic reflection in the visible (380–780 nm) range for background matching 27 , 28 ; (iii) high absorbance in the microwave radar band (X-band, 8–12 GHz) for reducing radar cross-section (RCS) 29 and (iv) high absorbance at the laser wavelengths (1.55 μm and 10.6 μm) 30 , 31 . According to the Stefan-Boltzmann law, the thermal radiation intensity is proportional to the fourth power of the surface temperature; therefore, reduction of the surface temperature is desired for IR camouflage 32 – 35 , especially for the military objectives with high surface temperature (e.g., converging nozzles of aircraft (~950 K) 36 , tailpipe of aircraft (~740 K) 37 , and funnels of naval ships (~680 K) 38 ). However, radiative heat transfer is blocked in traditional MIR camouflage with broadband low emittance, introducing heat instability 39 , 40 .…”

Effect of Unit Cell Shape on Switchable Infrared Metamaterial VO 2 Absorbers/Emitters

“…Emission bands whose radiation is much narrower are suitable for various scenarios [ 6 , 7 ]. For example, Zhu et al designed thermal management devices by combining wavelength-selective emitters and thermal insulators and achieved emittance of ~0.58 and~0.08 within 5-8 and 8-14 μ m, reducing the surface temperature of a high-temperature object (873 K) to 410 K [ 8 ].…”