Creation of Hydrophobic Functional Surfaces of Structural Materials on the Basis of Laser Ablation (Overview)

Over the past decade, interest has increased in controlling the wettability of metal surfaces with various liquids. In particular, the use of hydrophobic functional surfaces improves the efficiency and reliability of thermal power plants and systems operating in various areas of life. One of the most promising ways to achieve a hydrophobic state of structural materials is surface modification using laser equipment: laser ablation. As a result of exposure to laser radiation, melting, evaporation and recrystallization of the surface layer of the metal occur. By varying the parameters of exposure to laser radiation, it is possible to form a relief with specified geometric characteristics on a metal surface. The creation of hydrophobic metal surfaces using laser equipment includes the following steps: choosing the type of laser source, determining the radiation parameters and the trajectory of the laser beam over the surface, preparing the initial surface, forming the relief, and reducing the surface energy after laser ablation. This paper presents an overview of the results of research on the creation of hydrophobic metal surfaces based on the formation of a structured relief. In most studies, a relief was formed on the surface of metal samples in the form of equidistant lines, a grid, or had no pronounced structure (irregular structure). It has been established that the hydrophobic state of a metal surface with the highest contact angles (more than 150°) is achieved by laser texturing of the relief in the form of equidistant lines or a grid with a step not exceeding 100 μm. The maximum contact angle (approximately 179°) was obtained by forming a relief in the form of a grid with mutually perpendicular lines equidistant at 15 and 20 µm.