Self-Similar Superhydrophobic Whisker-Based Coatings with High Impact and Abrasion Resistance.

Abstract

Spray-on fabrication of superhydrophobic (SH) coatings using nanoparticles (NPs) has broad applications, but their mechanical durability often falls short of practical requirements. In this work, we demonstrate that mixing NPs with well-dispersed SiC whiskers (SiCw) can significantly improve the SH stability and mechanical durability of sprayed coatings, even under complex and harsh impact/abrasion conditions (such as sandblasting), which is attributed to the formation of a fully connected, avian nest-like, self-similar SiCw framework via the random packing of whiskers during coating drying. The resulting coating exhibits exceptional abrasion resistance, enduring 1,000 dry and 900 wet cycles in Taber abrasion tests (CS-17 wheels), and shows negligible degradation after impact testing at 3.12 × 106 J·m-2. It is further shown that achieving high dispersity of the whiskers is critical to the coating's preservation of microstructural roughness against various environmental impacts. The whisker-based coatings demonstrate excellent contact time reduction, icing delay, and self-cleaning capabilities on a variety of substrates, including textiles and power line strands. At -15 °C and 67% RH, the well-dispersed coating delays icing by 1,442 s─over 300 s longer than its poorly dispersed counterpart. This work presents a green spray-on strategy to produce durable SH coatings without complicating the fabrication process, offering persistent superhydrophobicity for real-world applications.