Effect of black silicon structure on capillary spreading of liquid

The paper presents the experimental results on capillary liquid spreading over superhydrophilic black silicon surfaces of various morphologies created by cryogenic plasma-chemical etching. Five samples of capillary surfaces with different microstructure characteristics were made, including two hybrid surfaces combining microstructuring of different heights. The morphology of surfaces and characteristics of their wetting with water were studied, including the Wi number, which characterizes the capillary absorption of liquid. It was found that a greater height of microstructures ensures better liquid spreading. The maximum values of the Wi number are achieved on hybrid surfaces with a greater density of “high” microstructures. The prospects of using hybrid capillary surfaces to increase the critical heat flux during water boiling are shown.