## 2 Experimental Procedure
### Wetting and Spreading Experiments  
Figure 2 presents a model of an experimental setup for determining wetting properties and studying the liquid movement over the surfaces of composite materials. The light beam from the source MI-150 (Edmund Optics, Barrington, IL, USA) 1 passes through the fiber optic cable glass fiber cable BX4 (Dolan-Jenner, Boxborough, USA) 2, entering the telecentric tube 52 mm telecentric background illuminator 62-760 (Edmund Optics, Barrington, IL, USA) 3, where it is converted to plane-parallel light. Then it illuminates a droplet 4 sitting on the surface of a sample 5. The shadow image of the droplet was obtained by a high-speed camera Fast Video 500 M (Fast Video, Moscow, Russia) 6. The geometrical dimensions of the droplet were determined from shadow images using the LB-ADSA [45] and tangential 1 [46] goniometry methods. When determining wetting properties (static contact angles), a 5-mL droplet of distilled water was dosed onto the surface with a Lepipet Stepper single-channel electronic dispenser (ThermoScientific, Russia) 7. In order to evaluate the wetting inversion (spontaneous hydrophobization), static contact angles were measured on laser-modified Cu-SiC surfaces at least once every 13 days until the wetting properties stabilized. Static contact angles were determined as the arithmetic mean of the values obtained from five measurements in randomly selected areas. The error in determining the contact angles did not exceed 5%. Liquid spreading with a volume not exceeding 10 mL over the Cu-SiC surfaces consisted in determining the dynamic contact angles (DCA), the speed of the liquid front, and the contact angle hysteresis (CAH). In the experiments, a liquid supply system was used, consisting of a [PERSON] 8 high-precision syringe pump ([PERSON], Vernon Hills, IL, USA), a tube 9, and a hollow tip 10. The pump operated in sequentially changing modes of supplying and pumping out liquid. When distilled water was added to a droplet formed on the surface under study, an advancing contact line was formed; when the liquid was pumped out, a receding line was formed. During the measurement of dynamic contact angles, the volume of liquid delivered by the pump (10 mL) remained constant. Two flow rates have been selected. The flow rate of 5 mL/min was chosen based on recommendations [47]: quasi-static advancing and receding angles should be measured at very low fluid flow rates/contact line speeds to avoid dynamic effects. The value of 100 mL/min was chosen to compare the obtained values of CAH and DCA. Figure 2: Experimental setup determining wetting properties and studying the liquid movement: 1—light source; 2—fiber optic cable; 3—telecentric tube; 4—droplet; 5—Cu-SiC sample; 6—high-speed video camera; 7—single-channel electronic dispenser; 8—syringe pump; 9—tube; 10—steel hollow tip. Spreading, from the moment the liquid was formed on the surface to the complete pumping out of the liquid, was recorded by a high-speed video camera. After the experiments, the video files were storyboard into separate photographic images using Fast Video Lab software (Fast Video, Russia). The moment of the droplet formation was taken as the beginning of the experiment. The resulting shadow images were processed by the LB-ADSA [45] and tangential 1 [46] goniometry methods. Liquid spreading over laser-modified Cu-SiC surfaces was studied during the period of wetting inversion from hydrophobic to wetting stabilization. For 19 days after laser processing, an unstable formation of a droplet in the form of a spherical segment was recorded on hydrophilic modified Cu-SiC surfaces, which did not allow one to determine the spreading characteristics with sufficient accuracy. The stabilization of wetting properties was detected according to the recommendations [37], which show that the contact angle hysteresis should be constant over time when the wetting properties are stabilized. Each experiment was repeated 3-5 times according to a well-tested procedure [20] under identical conditions.