Silver-modified chromium(III) oxide as multi-band compatible stealth materials for visual/ infrared stealth and radar wave transmission

Here we proposed a strategy of modifying colored pigments with low emissivity materials to develop multi-band compatible stealth materials. The silver-modified Cr₂O₃ particles were first prepared for achieving visual/infrared stealth and radar wave transmission simultaneously. The electrical conductivity increased significantly and the emissivity reduced effectively of Cr₂O₃@Ag hybrid powders with the increase of Ag content. By employing silicone resin as the binder, and Cr₂O₃@Ag (X mol·L⁻¹) as the filler, coatings were prepared to investigate the stealth performance. The coating with 65 wt% Cr₂O₃@Ag (0.2 mol⋅L⁻¹) content achieved the lowest emissivity of 0.760. Particularly, the complex permittivity increased slowly and the transmittance was over 90% at the coating thickness within 0.3 mm. The high transmittance of radar waves is attributed to the good impedance matching between Cr₂O₃ and free space, along with the space between the Ag particles. Additionally, the brownish-green Cr₂O₃@Ag pigment showed a lower visible-near infrared reflectance than pure Cr₂O₃. The proposed method provides an idea for the design of colored coating with low emissivity and high radar wave transmission for application in stealth technology.