Anti-icing fluids interaction with surfaces: Ice protection and wettability change

Abstract

Some aircraft anti-icing fluids can dangerously weaken on hydrophobic surfaces. However, information about such fluids and surfaces was not full. Therefore, we considered the interaction of commercially available Newtonian and pseudo-plastic anti-icing fluids with super-hydrophilic and hydrophobic aluminum surfaces. In freezing rain simulations, no noticeable surface effect was observed on fluid endurance times at 10% ice coverage of the surfaces. The difference with previous works can be caused by fluid surface tensions, the contact angle hysteresis of test plates, and fluid viscosity (the last is irrelevant for Newtonian fluids). In further comparative studies, the roughness must also be considered because on rough hydrophobic surfaces the Newtonian fluid took longer to freeze once ice coverage surpassed 20% compared to smooth super-hydrophilic surfaces. Furthermore, the fluid physical adsorption in the surface texture leads to the drifting of receding contact angles of water on hydrophobic surfaces, thereby worsening their water-repelling. Thus, smooth hydrophobic surfaces are probably the preferred solution for ice mitigation systems contacting aircraft anti-icing fluids.