The F-22’s iron-based radar-absorbing coating fears airflow erosion and peeling, so it must live in temperature- and humidity-controlled hangars. After an F-35C spent a few months on a carrier, photos of coating corrosion spread online in 2025 — iron-based fillers oxidising in a high-salt, high-humidity environment, with salt fog creeping in through the damaged spots. These stealth aircraft have impeccable airframe design; what holds them back is the surface coating.
This article looks at stealth coatings: how the absorption budget is calculated, where new materials got to in 2025, and why the centre of gravity of this race is shifting from “absorbing it” to “surviving it.”
Key Takeaways
- Radar stealth coatings work in two steps: let the wave in (impedance matching) and keep it from leaving (dissipate it as heat).
- Thin, light, broadband and strong are mutually constraining; magnetic-loss materials are heavy, carbon-based ones are light but hard to impedance-match.
- In 2025 the most informative progress was in service environment and spectral breadth, not just lower decibel figures.
- Real-world bottlenecks are temperature, airflow, salt fog and service life — a coating is the only part of a stealth system that needs continuous maintenance.
- The next number worth remembering may not be dB but lifetime.
1. The Absorption Budget: It Comes In but Cannot Leave
A radar stealth coating works in two steps: let the incident electromagnetic wave come in (impedance matching, so it is not bounced straight back at the surface), then keep it from getting out (dissipating the electromagnetic energy as heat internally through magnetic loss, dielectric loss and interfacial polarisation).
The hard part is the constraints — thin, light, broadband and strong pull against one another. Magnetic-loss materials such as ferrites and carbonyl iron powder absorb strongly but are heavy, and their Curie temperature limits high-temperature performance; carbon-based materials are light but hard to impedance-match and narrowband. A 2025 review surveys the traditional systems [9].
Among 2025’s representative results: a team from Beijing Jiaotong University and Beihang University, inspired by the porous structure of coral reefs, grew flower-like ZnNiCo-LDH vertically on MXene surfaces into a three-dimensional network. At 1.35 mm thickness the reflection loss reached −49.6 dB — 99.998% of the electromagnetic energy absorbed — with an effective bandwidth of 3.4 GHz covering the Ku band; interfacial Mott–Schottky structures formed a built-in electric-field network, abandoning the old single-loss-mechanism path [1].
2. After Absorption, the Race Moves to Environment and Spectrum
Once absorption figures reached the −50 dB level, the more informative changes in 2025 appeared in two places: the service environment, and spectral width.
On the environment front, a work published in Advanced Materials in October by teams from Peking University, Beijing University of Technology and Harbin Engineering University is a landmark: chemical vapour deposition grows graphene on silica fabric, and laser patterning builds a metasurface with tunable surface impedance. The coating is about 0.1 mm thick and as soft as cloth; its performance is unchanged after 5 minutes at 600 °C in air and long-term heating at 1000 °C in vacuum; a 200 m/s high-speed airflow produces less than 1% loss; and integrated into a thermal-insulation layer it brings radar reflection down to −42 dB [2]. Thickness, temperature resistance and erosion resistance holding at the same time matters far more than shaving off a few more decibels.
Multispectral capability is another front. Radar stealth needs “absorption” while infrared stealth needs “low emissivity” — 3–5 μm is the main distribution region of thermal radiation for 300–1000 °C targets — and the two demands often fight on the same coating layer: a strongly absorbing conductive network is often exactly the high-emissivity infrared bright spot. Several solutions appeared in 2025:
A team at Shandong University of Technology used 3D-printed polysilazane precursors to prepare TPMS-SiCN ceramic, composited with porous SiOC and a paraffin phase-change material: the ceramic walls absorb (reflection loss −31.29 dB), while the phase-change material buffers heat and suppresses surface temperature, compressing the infrared signature — after 42 minutes of heating it still maintained a 36.6 °C temperature difference from the thermal load, integrating radar, thermal insulation and infrared in one [3].
Closer to surface-technology peers is the laser-cladding route: a 2025 work in the Journal of Alloys and Compounds prepared a pomegranate-bionic FeCoNiCrAl high-entropy alloy / AlN ceramic composite coating, in which Marangoni convection in the melt pool drives in-situ TiN-coated AlN to self-assemble into a core–shell structure; at an 8:2 mass ratio a 2 mm coating reached −15.1 dB reflection loss at 14.75 GHz and 0.28 infrared emissivity at 3–5 μm, stable at 500 °C and 700 °C [4]. Layered spraying routes are also advancing: one work sequentially sprayed a bonding layer, thermal-barrier ceramic layer, matching layer and loss layer — six layers in total — on a GH3128 superalloy surface, achieving about 250 °C overall insulation under 1050 °C conditions and 0.446 emissivity at 3–5 μm at 900 °C [7].
A more radical approach is simply to make it a film. A team at Sun Yat-sen University used continuous centrifugal spray coating to prepare a highly dense MXene film with ordered nanosheets: 2.25 μm thick, 45 dB electromagnetic shielding in the GHz band (8.2–40 GHz) and 59 dB in the THz band, while infrared emissivity at 2.5–16 μm is as low as 0.1 — close to aluminium — making day-and-night outdoor infrared stealth viable [5]. A team at the Institute of Metal Research went further and made a transparent version: a MXene/PET film covering GHz-to-THz shielding and infrared stealth at 82% transmittance, aimed at aircraft windows [6]. Flexible heterostructure films are following: a PEF-MXene/liquid-metal composite film reaches 23104 dB·cm²/g specific shielding effectiveness in the X band and 90% infrared radiation suppression [8].
3. The Real Hurdle: Not dB, but Lifetime
Line up the 2025 results and the common thread is that, beyond performance, every paper is filling in service data — temperature, airflow, duration, emissivity stability. Behind this is the real accounting of stealth coatings: the airframe is formed once and never goes offline, but the coating is consumed by airflow, rain erosion, salt fog and thermal cycling on every flight, and is the only part of a stealth system that needs continuous maintenance.
The new generation of materials targets exactly this premise: graphene grown on high-temperature-resistant silica fabric [2], high-entropy alloys resisting oxidation [4], ceramic precursors withstanding thermal shock [3]. The spectral boundary is expanding too — beyond radar and infrared, structured cases of multifunctional protection in the laser band appeared this year [10].
In closing: for the last decade the stealth-coating race was about a lower trough on the reflection-loss curve; now it is about how many fewer days the coating spends in the hangar. The next number worth remembering may not be dB, but lifetime.
References
[1] Meng Y, Wang J, et al. Biomimetic coral reef-structured ZnNiCo-LDH/MXene composite for electromagnetic wave absorption. Nano Research, 2025 (Beijing Jiaotong University, Beihang University, et al.)
[2] Cui G, Wang H, Li M, Liu Z, et al. Graphene@silica fibre membrane metasurface for high-temperature radar absorption. Advanced Materials, 2025 (Peking University, Beijing University of Technology, Harbin Engineering University)
[3] Liu C, Mao K, Feng Y, Guo X, et al. TPMS-SiCN ceramic composite integrating microwave absorption, thermal insulation and infrared stealth. Journal of Advanced Ceramics, 2025 (Shandong University of Technology)
[4] FeCoNiCrAl high-entropy alloy / AlN ceramic pomegranate-bionic radar-infrared compatible stealth coating by laser cladding. Journal of Alloys and Compounds, 2025
[5] Huang W, Liu X, Wang Y, et al. Ultra-Broadband and Ultra-High Electromagnetic Interference Shielding Performance of Aligned and Compact MXene Films. Nano-Micro Letters, 2025, 17: 234. DOI: 10.1007/s40820-025-01750-z (Sun Yat-sen University)
[6] Zhang T Y, Zhao Q Q, et al. All-In-One Flexible MXene/PET Films via Scalable Scanning Centrifugal Casting for High Transparency and Ultra-Wide Multispectral Electromagnetic Responses. Advanced Science, 2025. DOI: 10.1002/advs.202501540 (Institute of Metal Research, CAS)
[7] Zhao J C, Yang L X, Gao W, Gao Y. Study on the performance of composite coatings sprayed on GH3128 surface. Hot Working Technology, 2023. DOI: 10.14158/j.cnki.1001-3814.20230772
[8] Li Y, Chen X, Liu J, et al. PEF-MXene/LM heterostructure films with enhanced EMI shielding, gas barrier efficiency and thermal camouflage properties. Chemical Engineering Journal, 2025
[9] Bera P, Lakshmi R, Barshilia H C. An Overview of Radar-Absorbing Materials and Coatings for Stealth Application. Science and Culture, 2025
[10] Ma J, Xiong S, Wang Y, et al. Bioinspired Directionally Porous Alumina Ceramics With High Reflectivity and Strength for Extreme Laser Protection. Advanced Functional Materials, 2026, 36: e75124. DOI: 10.1002/adfm.75124
(The F-22/F-35 coating maintenance and cost information in this article is cited from media reports — South China Morning Post and The Star, October 2025 — and the specific data should defer to the original literature.)
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FAQ
Q: Why are stealth coatings so hard to maintain?
Because the coating is the only part of a stealth system consumed by every flight — airflow, rain erosion, salt fog and thermal cycling degrade it continuously, unlike the airframe itself.
Q: Why can’t you simply chase ever-lower reflection loss?
Because thin, light, broadband and strong constrain one another, and in real service the limiting factors are temperature, airflow and lifetime. A coating that survives the environment is worth more than a few extra decibels.
Q: Can radar and infrared stealth coexist on one coating?
They often conflict, because a strongly absorbing conductive network tends to be a high-emissivity infrared bright spot. 2025 work addressed this with phase-change materials, high-entropy alloy/ceramic composites and low-emissivity MXene films.
Q: What changed most in 2025?
The centre of gravity shifted from raw absorption performance toward service environment and spectral breadth: high-temperature resistance, erosion resistance and multispectral (radar/infrared/laser) protection.
Q: What is Aomway’s interest in this area?
Aomway supplies FPV and UAV hardware and follows advances in materials and coatings relevant to UAV survivability and sensor performance. If you have questions about materials for your platform, contact Aomway at [email protected].
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