Design and fabrication of laser cladding pomegranate bionic structure FeCoNiCrAl high entropy alloy / AlN ceramic high temperature radar-infrared compatible hidden composite coating

Abstract

With the advancement of multi-target detection technology, radar-wave-infrared-compatible stealth coatings have emerged as crucial materials. To overcome the challenges associated with poor radar-wave-infrared stealth performance in harsh high-temperature environments, FeCoNiCrAl/AlN composite coatings with pomegranate bionic structures were designed and fabricated by laser cladding. Laser-induced FeCoNiCrAl / AlN generates TiN phase in situ in the molten pool and drives TiN to tightly stack around AlN through Marangoni convection, thereby self-assembling to form an AlN-TiN core-shell structure. Modifying the FeCoNiCrAl/AlN mass ratio substantially influences the heterogeneous interfacial polarization between metal and ceramic phases, thereby effectively regulating the coating's electromagnetic (EM) wave response. When the FeCoNiCrAl/AlN mass ratio is optimized to 8:2, the coating demonstrates excellent high-temperature radar wave and infrared (IR) stealth compatibility. With a coating thickness of 2 mm, it achieves a reflection loss (RL) of -15.1 dB at 14.75 GHz and a IR emissivity of 0.28 in the 3-5μm range. The material maintains stable performance at elevated temperatures of 500°C and 700°C, with RL values of -11 dB and -10 dB, and IR emissivity of 0.33 and 0.328, respectively. The laser-induced melt convection-driven bionic structure FeCoNiCrAl / AlN coating has high radar wave absorption and low infrared emission, which can achieve tunable design integration and efficient preparation of high-temperature compatible stealth coatings.