Water condensation on superhydrophobic aluminum surfaces with different low-surface-energy coatings

In this work, we have fabricated superhydrophobic aluminum surfaces by a facile chemical etching method. Surface morphology and composition were studied by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). To comparatively investigate the effect of environmental factors on superhydrophobic behaviors of surfaces with different low-surface-energy coatings under controllable condensation conditions, contact and sliding angles were measured from −10 °C to 30 °C under relative humidity (RH) of 30, 60 and 90%, respectively. The calculation of the solid–liquid contact area fraction quantitatively explained the increased wettability characterized by descending contact angle and ascending sliding angle under low temperature and high humidity, and indicated a transition of the equilibrium state from Cassie–Baxter to Wenzel on rough surfaces. The wettability restoration test showed that the loss of superhydrophobicity during condensation could be recovered completely after a drying process at room temperature.