Modification of Al pigment with graphene for infrared/visual stealth compatible fabric coating

Al pigment was modified with graphene to reduce the lightness and visible reflectance via a three-step preparation method, including pretreatment of Al pigment with silane coupling agent, absorption of graphene oxide(GO), and reduction of GO. Al pigment was pretreated with silane coupling agent to introduce –NH2 groups so that it will be able to combine with GO by ionic bands, which were confirmed by Zeta potential tests and FTIR spectra. The SEM images of Al pigment modified with reduced graphene oxide (Al-RGO) showed that RGO was absorbed onto the surface of Al pigment, which resulted in the reduce of lightness and visual reflection. Raman spectra conformed the multi-layer structure of RGO and indicated that a great number of defects remained in RGO sheets. After modification, the metallic lightness of Al pigment was significantly suppressed, and the color hue of Al pigment changed to dimgray from silver white. Al-RGO was used in low emissivity fabric coating with optimized visual property. In comparison with blank Al pigment fabric coating, the lightness L* of Al-RGO coating was decreased by 49%, the visual light reflectivity was reduced by 23%, and the gloss was suppressed upto 58%, while the infrared emissivity in the range of 8–14 μm waveband only exhibited a slight increase of 0.12. Al-RGO works as a novel low infrared emissivity pigment with improved visual spectral stealthy compatible property.