Preparation and Characterization of High-Performance Composite Coatings Compatible with Near-Infrared Low Reflectivity and Low Infrared Emissivity

Polyurethane (PU)/Al-graphene composite coating with low infrared emissivity, a low near-infrared reflectivity of 1.06 mu m, and satisfactory mechanical properties was prepared by using Al powder and graphene as composite pigments and PU as a binder, respectively. The study investigated the impact of the mass ratio of graphene to Al powder, as well as the total addition of functional fillers (Al powder and graphene), on infrared emissivity and near-infrared reflectivity, and the mechanical properties of the coating were studied. The results show that a large number of conjugated systems in the molecular structure of graphene can produce strong absorption of near-infrared radiation, allowing for the coating to exhibit low reflectivity at 1.06 mu m in near-infrared radiation. The flake Al powder, with good electrical conductivity, can create a strong reflection in the 8-14 mu m far-infrared radiation range, resulting in low emissivity and providing the coating with good infrared and laser-compatible stealth performance. By adjusting the mass ratio of graphene to Al powder, the infrared emissivity at 8-14 mu m can be tuned from 0.371 to 0.644, and the reflectivity at 1.06 mu m can be adjusted from 22.9% to 61.6%. Additionally, the coatings demonstrate satisfactory mechanical properties, with adhesion strength, flexibility, and impact strength reaching grade 1, 2 mm, and 50 kg center dot cm, respectively, for coatings with different mass ratios of graphene to Al powder. The PU/Al-graphene composite coating can be regarded as a new type of infrared and laser compatible stealth coating with good functional and mechanical properties.