Bio-Inspired, Ultra-hydrophobic Natured Durable Thermal-Sprayed Ytterbium-Oxide Coatings: Review and Perspectives

Ever since the discovery of ultra-hydrophobicity in lotus leaf, rigorous experiments have been carried out to replicate and understand its wetting nature using ceramic oxide based coatings on various substrates. Enormous applications dealing with ultra-hydrophobic nature have been explored which led to the discovery of intrinsic hydrophobic nature in rare-earth oxides. Several studies reported intrinsic hydrophobic behavior exhibited by rare earth oxides. Among all rare earth oxides, ytterbium-oxide (Yb2O3) has numerous applications in different fields because of its ability to phase change with pressure, abrasion resistance, high hardness and melting point. This review gives a basic understanding of wettability studies carried out on Yb2O3 coating via the solution precursor plasma spray (SPPS) technique outlined in the literature and aims to understand the mechanism of post-processing treatments, revealing the conditions affecting the reversible wettability. Additionally, the mechanical durability tests performed on thermal-sprayed Yb2O3 coatings are summarized along with the cost-effective approach of SPPS technique over other plasma spray techniques. The ultra-hydrophobicity in Yb2O3 coatings and its existing applications propels the development of novel device-designing strategies in the field of bio-sensing and oil-water separation.