Biomimetic Preparation of Alumina Hierarchical Papillary Microrough Structure for Hydrophobic Improvement and Its Abrasion Resistance Finite Element Analysis

The surface of lotus leaves has a hierarchical micro–nano-rough structure. We determined that the papillary structure also possesses hierarchical features on the microscale. We used alumina particles as rough structure building units to construct a Hierarchical Papillary microrough Structure (HPS) on a ceramic surface. The effects of the spatial distribution of HPS on the abrasion resistance and mechanical stability of hydrophobic coatings were investigated. Furthermore, for each HPS, the falling sand abrasion process was analyzed using finite element fluid mechanics analysis. A denser or more two-dimensional HPS implied that more area was impacted by the falling sand and that the abrasion amount and rate were higher. This is contrary to the common belief that when there are more wear-resistant substances on the surface, the abrasion resistance is better; thus, abrasion resistance does not necessarily depend entirely on the concentration of wear-resistant substances on the surface, but it is also influenced by the abrasion mode and the spatial distribution structure of the wear-resistant substances. The 3D stacked HPS (3D-HPS) with excellent abrasion resistance and rich pore structure considerably enhanced the mechanical stability of the hydrophobic coatings. These findings provide novel insights and a theoretical basis for designing spatial structures on high abrasion-resistant superhydrophobic ceramic surfaces.