Nucleation characteristics of condensation on coarse hydrophobic surface

The hydrophobic glass substrate surfaces with different roughness were prepared by eroding and decorating. The wetting behaviors of these rough surfaces and the condensing nucleation characteristics of water vapor on them were investigated experimentally. The experimental results indicate that the surface micro-morphology has significant influences on the wettability and condensing nucleation properties on these rough surfaces; the apparent wetting angle increases with the increase of surface substrate roughness, while the nucleation density of water droplets on the hydrophobic coarse glass surface decreases. The analysis suggests that the effect of surface microstructure on apparent wetting angle leads to the change of nucleation energy and nucleation density, that is, a larger apparent wetting angle forms on a rougher hydrophobic surface, which leads to the increase of free energy needed for heterogeneous nucleation and the decrease of nucleation density of vapor condensation. The condensation experiments on hydrophobic rough substrates agree with the previous theoretical description for heterogeneous nucleation on rough surfaces.