Key Takeaways & Executive Findings
- •• Simultaneous stealth across multiple infrared bands (SWIR, MWIR, LWIR) and microwaves at high temperatures (700 °C) is achieved. • At 700 °C, the device features low emissivity of 0.38/0.44/0.60 in MWIR/LWIR/SWIR bands, reflection loss below −3 dB in the X-band (9.6–12 GHz), and high emissivity of 0.82 in the 5–8 μm range. • Under an input power equivalent to Mach 2.2 aerodynamic heating, effective thermal management achieves a 72.4 °C temperature reduction compared to conventional low-emissivity molybdenum. • The proposed strategy integrates an IR-selective emitter and a microwave metasurface, providing comprehensive guidance for high-temperature stealth design.
Abstract
High-temperature stealth is vital for enhancing the concealment, survivability, and longevity of critical assets. However, achieving stealth across multiple infrared bands—particularly in the short-wave infrared (SWIR) band—along with microwave stealth and efficient thermal management at high temperatures, remains a significant challenge. Here, we propose a strategy that integrates an IR-selective emitter (Mo/Si multilayer films) and a microwave metasurface (TiB2–Al2O3–TiB2) to enable multi-infrared band stealth, encompassing mid-wave infrared (MWIR), long-wave infrared (LWIR), and SWIR bands, and microwave (X-band) stealth at 700 °C, with simultaneous radiative cooling in non-atmospheric window (5–8 μm). At 700 °C, the device exhibits low emissivity of 0.38/0.44/0.60 in the MWIR/LWIR/SWIR bands, reflection loss below −3 dB in the X-band (9.6–12 GHz), and high emissivity of 0.82 in 5–8 μm range—corresponding to a cooling power of 9.57 kW m−2. Moreover, under an input power of 17.3 kW m−2—equivalent to the aerodynamic heating at Mach 2.2—the device demonstrates a temperature reduction of 72.4 °C compared to a conventional low-emissivity molybdenum surface at high temperatures. This work provides comprehensive guidance on high-temperature stealth design, with far-reaching implications for multispectral information processing and thermal management in extreme high-temperature environments.
1. Introduction
Stealth technology aims to conceal the characteristics of critical assets and render them invisible to various types of detectors, thereby enhancing survivability and longevity. On the modern battlefield, target detection primarily relies on the infrared (IR) and microwave bands. In the IR band, thermal cameras detect objects by capturing their emitted thermal radiation, with the radiation intensity proportional to the fourth power of the object’s temperature. In the microwave band, radar systems detect objects by emitting microwaves and receiving the reflected waves from the objects. With advancements in multispectral detection technology, multispectral stealth materials spanning visible to microwave spectra have flourished. Among these, IR-microwave compatible stealth materials are of critical importance.
Furthermore, as high-speed targets evolve, numerous critical assets (e.g., aircraft skin, converging nozzles) are affected by internal or external heat sources, resulting in high operating temperatures and intense thermal radiation. The existing multispectral stealth materials often fail at high temperatures, and their infrared stealth bands are typically limited to the conventional mid-wave infrared (MWIR, 3–5 μm) and long-wave infrared (LWIR, 8–14 μm) bands. However, at high temperatures, significant thermal radiation also occurs in the short-wave infrared (SWIR, 1.4–2.5 μm) band. As the peak wavelength of thermal radiation blueshifts at elevated temperatures, objects become highly susceptible to detection. Therefore, simultaneous high-temperature IR and microwave stealth has become an imminent requirement.
Considerable efforts have been made toward achieving high-temperature stealth. High-temperature IR stealth can be achieved by reducing surface temperature through thermal insulators. This approach is effective against internal heat sources, but is accompanied by a heat accumulation issue. When exposed to external heat sources, it loses efficacy as the outer surface of thermal insulators can be directly heated to high temperatures. Another method for high-temperature IR stealth is emissivity modulation through single-layer low-emissivity films (e.g., MXene, Au) and Fabry–Pérot cavities. However, these structures are incompatible with microwave stealth due to their high reflectivity to microwaves. High-temperature microwave stealth can be achieved through absorption induced by electric or magnetic losses, or scattering from destructive interference.
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Meng Zhao, Huanzheng Zhu, Bing Qin, Rongxuan Zhu, Jihao Zhang, Pintu Ghosh, Zuojia Wang, Min Qiu, Qiang Li (2025). High-Temperature Stealth Across Multi-Infrared and Microwave Bands with Efficient Radiative Thermal Management. Nano-Micro Letters. https://doi.org/10.1007/s40820-025-01712-5
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Frequently Asked Questions
What is the significance of achieving stealth across multiple infrared bands?
At high temperatures, thermal radiation shifts to shorter wavelengths, including the short-wave infrared (SWIR) band. Traditional stealth materials often only cover MWIR and LWIR, leaving SWIR as a detection vulnerability. This work achieves simultaneous stealth in SWIR, MWIR, and LWIR, enhancing concealment against multispectral detectors.
How does the device achieve both infrared and microwave stealth?
The device integrates an IR-selective emitter (Mo/Si multilayer films) for infrared stealth and a microwave metasurface (TiB2–Al2O3–TiB2) for microwave absorption. This combination allows low emissivity in the infrared bands and reflection loss below −3 dB in the X-band, enabling compatible stealth.
What is the role of radiative cooling in the 5–8 μm range?
The device exhibits high emissivity (0.82) in the 5–8 μm range, which is a non-atmospheric window. This allows efficient radiative heat dissipation, reducing the surface temperature and enhancing thermal management, especially under aerodynamic heating conditions.
How does the device perform under high-temperature conditions?
At 700 °C, the device maintains low emissivity in MWIR/LWIR/SWIR bands and microwave absorption in the X-band. Under an input power equivalent to Mach 2.2 aerodynamic heating, it achieves a temperature reduction of 72.4 °C compared to conventional low-emissivity molybdenum, demonstrating effective thermal management.
What are the potential applications of this technology?
This technology is crucial for enhancing the survivability and longevity of high-speed aerospace vehicles and other critical assets operating in extreme high-temperature environments, by providing multispectral stealth and efficient thermal management.
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