Hydrophobic/hydrophilic surfaces constructed using laser spraying: A new route

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, an innovative low-cost and environmentally friendly laser spraying technology was employed to fabricate hydrophobic and hydrophilic Ni coatings. The wettability of the coatings was regulated by systematically varying laser power and substrate temperature. The Ni particles presented spherical morphology, low oxidation rate and low coverage rate (4 %) with a laser power of 3000 W and room temperature substrate, yielding a hydrophobic coating with a water contact angle of 125.9 ± 17.2° Conversely, Ni particles exhibited oblate spherical morphology, higher oxidation rate, higher coverage rate (95 %) and a porous structure with a laser power of 5400 W and a substrate temperature of 700 °C, resulting in a hydrophilic coating with a water contact angle of 8.4 ± 1.2° These findings demonstrate a novel approach for tailoring the wettability of the Ni coatings, offering new insights into the fabrication of functional coatings for various applications.