High‑temperature stealth across multi‑infrared and microwave bands with efficient radiative thermal management

As hypersonic vehicles, scramjet nozzles and high-speed drones push beyond Mach 2, their skins glow at 700 °C—shining like a beacon in every thermal and radar band. Now, researchers from Zhejiang University and Westlake University, led by Dr. Qiang Li and Dr. Meng Zhao, have unveiled a single, scalable coating that hides platforms from SWIR, MWIR, LWIR and X-band radar while actively shedding 9.6 kW m^-2 of waste heat. The work delivers a turnkey architecture for survivability in extreme flight regimes.

Why Multispectral Stealth Matters
• Peak-Shift Problem: At 700 °C black-body radiation peaks at 2.8 µm—inside the short-wave IR (SWIR) window—making conventional MWIR/LWIR-only camouflage obsolete.
• Radar-IR Conflict: Low-emissivity metals that suppress IR are perfect microwave reflectors, while radar absorbers glow fiercely at high temperature.
• Heat-Accumulation Trap: Thick thermal insulators cool the inner airframe but cook the outer skin when aerodynamic heating strikes, leading to catastrophic IR signature spikes.

Innovative Design & Features
• IR-Selective Emitter: A laser-etched Mo/Si multilayer (total < 1 µm) delivers ε ≤ 0.38/0.44/0.60 across MWIR/LWIR/SWIR yet jumps to ε = 0.82 in the 5–8 µm “non-atmospheric” window—turning the surface into a high-power radiator exactly where the sky is transparent.
• TiB₂ Metasurface: Embedded square blocks create an impedance-matched Salisbury screen that sucks in 9.6–12 GHz microwaves with < −3 dB reflection while surviving 700 °C in air.
• Monolithic Integration: Both functional layers are deposited by standard e-beam evaporation and picosecond-laser diced on a single Al₂O₃ tile, enabling wafer-scale fabrication and direct bonding to curved aerosurfaces.

Applications & Future Outlook
• 72 °C Cooler: Under 17.3 kW m^-2 aerodynamic heating (Mach 2.2 equivalent) the hybrid surface runs 72.4 °C colder than low-emissivity molybdenum, translating into a 270 °C lower radiative temperature in the LWIR band—an unambiguous “vanishing” act for thermal imagers.
• Five-Band Cloaking: Experimental IR cameras confirm signal suppression of 37–64 % versus black-body references in SWIR, MWIR and LWIR up to 700 °C, while X-band radar cross-section drops by > 90 % across 2.4 GHz of bandwidth.
• Beyond Hypersonics: The same stack doubles as a radiative heat sink for satellite bus panels, turbine shrouds and reusable launch-vehicle leading edges, offering a universal thermal-management skin for any high-flux, high-risk platform.

Challenges & Opportunities: The team highlights next steps—boosting SWIR emissivity below 0.5, pushing operating temperature to 1 000 °C through high-entropy-ceramic spacers, and roll-to-roll transfer of the metasurface onto polymer-matrix composites for flexible hypersonic wings.

This work provides a photonics-first route to simultaneous multispectral stealth and self-cooling, promising a new generation of survivable, energy-efficient platforms for both military and civilian extreme-environment missions.