Hydrophobic/Hydrophilic Surfaces Constructed Using Laser Spraying: A New Route

Abstract

Hydrophobic/hydrophilic coatings are widely applied in healthcare, construction, and electronic devices. However, low-cost preparation of coatings is a challenge because they are often associated with complex procedures and adverse environmental impacts. Therefore, hydrophobic/hydrophilic Ni coatings were fabricated via a low-cost and environment-friendly laser spraying technology. The hydrophobic or hydrophilic properties of coatings were regulated by laser power and substrate temperature. Microstructure evolution of particles was analyzed by scanning electron microscope (SEM), electron back-scattered diffraction analyzer (EBSD) and transmission electron microscope (TEM). Wettability of coatings was measured using a contact angle meter. The results demonstrate that the particles deposited on substrates at room temperature with spherical morphology and low oxidation rate due to their semi-molten state with the laser power of 3000 W, and the coverage rate of deposited particles was 4%. The water contact angle of the coatings reached up to 143.1°. In contrast, the particles deposited on substrates heated at 700 oC with oblate spherical morphology, high oxidation rate and porous structure as the laser power increased to 5400 W, and the coverage rate of deposited particles was 95%. The water contact angle of the coatings decreased to 8.4°. The results provide a new perspective for fabricating hydrophobic/hydrophilic coatings.

Keywords: Laser spraying, hydrophilic, hydrophobic, microstructure evolution, nickel oxide