Multi-scale bionic design and laser cladding manufacturing of stealth coating

Electromagnetic wave-absorbing coatings (EWACs) play a pivotal role in diverse advanced technologies, including radar stealth, precision detection instruments, 6G communications, and radio astronomy. However, a critical bottleneck persists: the inadequate high-temperature stability and poor corrosion resistance of conventional EWACs when deployed in harsh marine atmospheric environments. To address this challenge, this study innovatively designs and fabricates two high-performance FeCoNiCrAl-based coatings via laser additive manufacturing: a pomegranate-like bionic intrinsic wave-absorbing coating and a butterfly-wing-like periodic porous structural coating. For the intrinsic coating, in-situ synthesis of TiN particles within the FeCoNiCrAl/AlN molten pool is induced by laser cladding. Driven by Marangoni convection, the TiN particles tightly agglomerate around AlN nuclei, spontaneously forming a core-shell AlN-TiN heterostructure. The multi-heterogeneous interfaces inherent to this garnet-type high-entropy alloy-TiN-AlN structure significantly enhance dielectric loss properties, thereby endowing the coating with superior intrinsic wave-absorbing performance. Furthermore, leveraging the mechanisms of multiple reflections and interference cancellation of electromagnetic waves, a periodically ordered bionic porous coating is engineered. The effects of key structural parameters, including coating thickness, pore size, and periodicity, on electromagnetic wave absorption are systematically investigated. Consequently, a bionic ordered porous coating with exceptional wave-absorbing performance is achieved. Both coatings exhibit remarkable high-temperature stability; notably, the structural coating maintains nearly negligible performance degradation after exposure to 500 °C and 700 °C. Even after salt spray corrosion testing, its minimum reflection loss (RLmin) remains below -10dB. This work achieves the integration of tunable structural design and controllable laser cladding-based additive manufacturing, thereby providing a novel and effective strategy for resolving the bottleneck scientific problems associated with EWACs operating in high-temperature and complex corrosive environments.