Low emissivity at 8 to 14 μm and low near-infrared reflective properties of Al Sm₂O₃/polyurethane composite coatings

Al-Sm₂O₃/polyurethane (PU) composite coatings were prepared through a simple and convenient process by using Al-Sm₂O₃ as the pigments and PU as the adhesives. The microstructure, infrared emissivity, near-infrared reflective properties and mechanical properties of as-prepared coatings were systematically investigated. The results indicate that the existence of Sm₂O₃ in the coatings can obviously decrease the near-infrared light reflectivity at 1.06 μm, the existence of Al powders in the coatings can effectively reduce the infrared emissivity at the wavelength of 8 μm to 14 μm. By adjusting the mass ratio of Al-Sm₂O₃, the infrared emissivity at the wavelength of 8 μm to 14 μm can be tuned from 0.556 to 0.834, and the reflectivity at 1.06 μm can be tuned from 35.1% to 57.7%. The coatings can present good mechanical properties, the adhesion strength and impact strength of the coatings with different mass ratios of Al-Sm₂O₃can reach 1 grade and 50 kg·cm, respectively. Al-Sm₂O₃/PU composite coatings seem to be a novel low infrared emissivity material with low near-infrared light reflectivity and good mechanical properties.