Stealth technologies, used in jets like the F-22, J-20, and Su-57, enhance their ability to avoid detection, making them highly valuable for national defense. Both microwave and infrared imaging are critical in detecting and tracking stealth aircraft, accounting for 90% of the threat posed by such detection systems. Materials that absorb microwaves (MAM) and have low-infrared emissivity are essential in improving these aircraft's stealth capabilities.
Traditionally, microwave-infrared stealth is achieved through two methods. The first involves applying separate layers for microwave absorption and low infrared emissivity, although this approach can compromise the microwave absorption due to reflective interference. The second approach involves fabricating metamaterials on the MAM surface, but this method faces limitations, such as poor oxidation resistance and performance degradation under high temperatures.
A new alternative has emerged from a team led by Peng Wu at Kunming University of Science and Technology, which first reported on the stealth properties of 8YSZ (8 wt% yttria-stabilized zirconia) coatings. This innovative material integrates both microwave absorption and infrared stealth capabilities into a single coating. Through theoretical simulations and practical experiments, the researchers demonstrated that 8YSZ not only absorbs microwaves efficiently but also exhibits low infrared emissivity.
"In this report, we prepared ZrO2 and 8YSZ coatings by atmospheric plasma spraying technology with corresponding feedstock powder. Then, the phase and microstructure of the prepared coatings are characterized," said Peng Wu, a research assistant at Kunming University. The study highlights how 8YSZ, with its unique tetragonal phase, offers high-temperature ionic conductivity, crucial for its stealth performance.
Wu noted that an ideal stealth material should be easy to produce, thermally stable, and balance both microwave and infrared stealth properties. Due to its excellent attributes, 8YSZ is commonly used in various fields like thermal barrier coatings, solid oxide fuel cells, and catalysis. Its potential as a microwave absorbing material lies in its high-temperature ionic conductivity, which enhances the dissipation of microwave energy.
At 900C, 8YSZ demonstrated exceptional microwave absorption, with a minimum reflection loss of -50 dB, a thin layer requirement of 1.5 mm, and an effective absorption bandwidth of 2 GHz. It also maintained low infrared emissivity in the 3-5 um range, making it a promising candidate for future stealth applications.
Despite these promising results, further research is needed to explore the thermal shock properties, stability during plasma deposition, and overall durability of 8YSZ coatings. Wu identified these areas as critical for future developments in the field.
Research Report:Realizing microwave-infrared compatible stealth via single 8YSZ coating
