Laser etching ultra-black coating with novel anti-icing performance

Ultra-black coating has more than 99 % absorbance and is widely applied in aerospace, optical instruments, and solar industries. However, preparing the presently available ultra-black coatings requires high temperatures, significantly limiting their application. Based on a resin-matrix composite coating filled with carbon nanotubes (CNTs), this study provides a new method for preparing resin-matrix ultra-black coatings using laser etching technology at room temperature. The obtained results indicated that the laser etching process could effectively remove the pure resin film coated on the coating surface and change the light contact interface from air/resin to air/CNTs. The highest average absorption achieved by the coating was 99.49 %. The morphological characteristics prove that the laser etching changed the coating surface from a smooth resin to a porous microstructure. The porous microstructure played a significant role in light absorption and remarkably improved surface roughness and hydrophobicity. In addition, the excellent light absorption performance significantly improved the photothermal conversion, which translated to enhanced anti-icing and anti-frosting performance over an aluminum substrate. Under 1 sun illumination at −10 °C, the frozen time of water drop on the coating surface was 692 s, 11.2 times longer than that on an aluminum substrate surface. No frosting was observed on the coating surface after 600 s of testing. Furthermore, the coating also showed remarkable anti-icing and anti-frosting performance at −20 °C. Hence, the reported ultra-black layer demonstrated room-temperature synthesis and extremely high light absorbance, making it a promising candidate for various cold-weather applications.