Preparation and Characterization of Transparent Hydrophobic Al₂O₃ Surface by Vacuum Cold Spray

Transparent hydrophobic materials have broad application prospects in industry and daily life due to its transparent and super-hydrophobic characteristics, while its performance will be significantly influenced by the materials and its surface morphology. Hydrophobicity and transparency are competitive properties from the viewpoint of surface roughness. However, there are still a lot of problems to be solved to satisfy hydrophobicity and transparency simultaneously in the prepared surface. A novel and simple method to fabricate transparent hydrophobic surface is introduced in the present paper. Micron and sub-micron mixed Al₂O₃ powders were deposited on the glass and plastic substrate by vacuum cold spray. The coatings were modified by 1,1,2,2- Tetrahydroperfluorodecyltrimethoxysilane (FAS) to reduce the surface energy. The surface morphology was characterized by scanning electron microscopy (SEM) and 3D laser microscopy (LSM). The transmittance of the coating was also investigated. The results show that the as-sprayed surfaces exhibit submicron structure. After FAS absorbing treatment, the contact angle of water droplets on the coatings ranged from 108° to 136° depending on the local surface morphology, and the transmittance of Al₂O₃ coatings are all above 80% in the range of visible light.