Therefore, in the conducted experimental studies, the elemental composition is not a significant factor affecting the difference in the wetting properties of copper (Table 1) and steel surfaces (Table 2). Based on the analysis of the measured contact angles (Tables 1 and 2), it was found that, when increasing the roughness, the wetting properties of copper surfaces deteriorate and the contact angle increases from 66 \(\pm\) 5\({}^{\circ}\) (Cu\({}_{1.0}\)) to 93 \(\pm\) 4\({}^{\circ}\) (Cu\({}_{46.2}\)) (Table 1). In contrast, the wetting properties of the steel surface are enhanced and the contact angle decreases from 89 \(\pm\) 4\({}^{\circ}\) (St\({}_{1.0}\)) to 71 \(\pm\) 5\({}^{\circ}\) (St\({}_{46.2}\)) (Table 2). The texture (roughness) and wetting properties determine the phase transition characteristics of a droplet located on a heated metal surface in single-phase regime. In the conducted studies, copper and steel surfaces were processed by abrasive materials under identical conditions. However, as noted earlier, when using the same abrasive materials, with other conditions being equal, a different texture was formed on copper and steel surfaces, characterized by different values of the roughness parameters. For example, the maximum height of irregularities for copper is in the range of Sz(Cu\({}_{1.0}\div\) Cu\({}_{46.2}\)) = 1.1 \(\div\) 7.3 \(\upmu\)m and, for steel, it is in the range of Sz(St\({}_{1.0}\div\) St\({}_{46.2}\)) = 0.7 \(\div\) 1.7 \(\upmu\)m. Moreover, these metals demonstrate the opposite change in the wetting properties with an increase in roughness. As the roughness increases, the wetting properties deteriorate (the contact angle increases) on copper surfaces, whereas, on steel surfaces, the wetting properties improve (the contact angle decreases). This is explained by the hypothesis formulated in [26] regarding the effect of the distance between adjacent irregularities that form a texture of metals treated by grinding or polishing on the wetting properties. In [26], there were two typical intervals of change in the contact angle depending on the roughness parameters of copper and steel. In the first interval, the wetting properties improve with an increase in roughness. Among the studied textures in this work, all steel surfaces (St\({}_{1.0}\div\) St\({}_{46.2}\)) belong to this interval. A wetting improvement is associated with a sufficiently high density of peaks on the surface, and, consequently, with a small width of the cavities formed by them. Owing to such capillaries, which have an insignificant width compared to their depth (Sz no less than 1.7 \(\upmu\)m), the liquid wets the surface more effectively due to capillary forces. In the second conventionally selected interval, the angle increases, and wetting worsens with an increase in roughness. Among the studied textures, Cu\({}_{12.6}\div\) Cu\({}_{46.2}\) belongs to this interval. The height of irregularities in the second interval increases, as does the distance between neighboring peaks, and the energy barrier grows, which must be overcome by the droplet contact line during the time from the moment the droplet is placed on the surface until the equilibrium state is reached. Influence of the Metal Surface Texture on the Possibility of Controlling the Phase Transition of water Droplets in the Single-Phase Regime  
Figures 2 and 3 present the experimental dependencies of the contact angle and diameter on the evaporation time obtained for distilled water droplets evaporating in the single-phase regime from copper and steel surfaces heated to 80 \({}^{\circ}\)C.  
Based on the analysis of Figures 2 and 3, it was found that heating the copper and steel surfaces to 80 \({}^{\circ}\)C does not affect the initial geometric parameters (contact angle, contact diameter) of water droplets. The initial values of the contact angle and diameter at 80 \({}^{\circ}\)C are close to the values recorded without heating at a temperature of 22-24 \({}^{\circ}\)C (Tables 1 and 2).