Superhydrophobicity as a key factor in improving slurry erosion resistance of antifouling coatings

Abstract

Superhydrophobic surfaces are renowned for their non-wettability; however, their behavior and effectiveness in slurry water flows have received limited exploration. Furthermore, the enduring resistance of their wettability characteristics following erosion tests remains a topic insufficiently examined in scientific investigations. In this work, multifunctional coatings were obtained by combining functionalized halloysite nanotubes (HNT) with an epoxy primer. Fluorine-free coating (EsH) was prepared using a silanized HNT and fluorine-containing coatings (FPH) were obtained by a sol-gel co-condensation of a fluorinated silane and polyhedral oligomeric silsesquioxane (POSS) over activated HNT, thus producing FPOSS@HNT. The coatings were applied over epoxy primer holding different curing conditions. Both, EsH and FPH samples showed superhydrophobicity. The micromechanical properties of the coatings showed viscoelastic-plastic behavior which was sensitive to the curing state of the primer and fluorine presence. The materials were subjected to a slurry erosion test under high speed flow conditions and wettability was used to characterize the surface integrity over erosion-cumulative time periods. FPH coatings showed an outstanding resistance to the high speed slurry erosion. The hydrophobicity correlation with erosion resistance was properly described in terms of the hydrodynamic flow affecting the materials structure.