## 4 Conclusions  
1. The surfaces of Cu-SiC composite materials containing up to 20 wt.% of SiC and mechanically processed were found to have a significantly heterogeneous elemental composition. This causes the variability of the surface properties and a significant contact angle hysteresis (more than 10\({}^{\circ}\)). The use of such materials in practice as a structural material in the production of microfluidic devices, systems for separating and mixing micro- and nanoliter liquids is associated with a significant disadvantage. It is extremely difficult, and sometimes impossible, to control the dynamic characteristics of the nano- and micro-liter liquid spreading over such surfaces.  
2. It was shown that laser modification of Cu-SiC composite materials makes it possible to form a developed, multilevel roughness on the surface, as well as to form a near-surface layer with a uniform elemental composition.  
3. It was proven that the recorded deterioration of the wettability properties of Cu-SiC surfaces after abrasive processing with an increase in their sintering temperature, as well as the inversion mechanism and the reason for the spontaneous hydrophobization of the Cu-SiC composite materials modified by nanosecond laser radiation, are due to the adsorption of airborne hydrocarbon contaminants, similar to the known wetting inversion of metal surfaces.  
4. It was established that the wetting properties of materials prior to modification by laser radiation do not affect the intensity, duration of stages, and steady-state values of contact angles upon wetting inversion of Cu-SiC composite materials.  
Figure 12: The values of quasi-static advancing and receding contact angles, contact angle hysteresis and static contact angles obtained on laser-modified Cu-SiC materials. Wetting properties inversion stage: (**a**,**b**)—achieving hydrophobic properties; (**c**,**d**)—stabilization of surface properties. DCA and CAH were obtained at the following liquid flow rates: (**a**,**c**)—5 \(\mu\)L/min; (**b**,**d**)—100 \(\mu\)L/min.  
5. The processing of Cu-SiC surfaces by laser radiation makes it possible, at a given flow rate of 5 \(\upmu\)L/min, to change the dynamic characteristics of the micro-droplet spreading: the liquid front speed of more than three times, advancing dynamic contact angles in the range of 30\({}^{\circ}\). These advantages and the small contact angle hysteresis (less than 10\({}^{\circ}\) under the wetting stabilization conditions) make Cu-SiC suitable for use as a structural material for microfluidic devices, systems for separating and mixing micro- and nanoliter liquids.  
Conceptualization, D.F.; methodology, E.O.; validation A.D.; investigation, G.K.; data curation, D.F.; writing--original draft preparation, E.O.; writing--review and editing, D.F.; visualization, G.K.; supervision, D.F.; funding acquisition, E.O. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the Russian Science Foundation [grant number 21-73-10245, [[https://rscf.ru/project/21-73-10245/](https://rscf.ru/project/21-73-10245/)]([https://rscf.ru/project/21-73-10245/](https://rscf.ru/project/21-73-10245/))].  
The authors declare no conflict of interest.