Tailoring the wetting behaviors and surface structures of yttrium oxide coatings deposited via different plasma spray processes

Abstract

Surface structures and microstructures are of vital importance to the wetting behaviors and mechanical robustness of non-wetting surfaces. In this work, yttrium oxide coatings with different surface structures and microstructures were deposited via the solution precursor plasma spray (SPPS) process, powder plasma spray (PPS) process, and a newly-developed mesh shielding PPS process. The SPPS coatings showed porous microstructures and hierarchical surface structures, and thereby presented superhydrophobic behaviors. The PPS coatings showed dense lamellar microstructures and relatively flat surface topographies, resulting in mildly hydrophobic behaviors. The PPS coatings exhibited much higher mechanical robustness and more stable hydrophobicity under physical damage as compared to the SPPS coatings. The coatings deposited via the mesh shielding PPS process showed unique surface structures of conical pillars, endowing the coating with excellent hydrophobicity and high mechanical robustness. The conical-structured coatings showed quasi-superhydrophobic behaviors, and maintained relatively consistent hydrophobicity after abrasion. The effects of the microstructures and surface structures on the wetting behaviors and mechanical robustness of different coatings were comparatively investigated. The effects of the microstructures and surface structures on the wetting behaviors and mechanical robustness of different coatings were comparatively investigated. The change of wetting behaviors of coatings after different treatments was elaborated by correlating with the surface compositions. The work showed the wetting behaviors and mechanical robustness can be manipulated by tailoring the microstructures and surface structures in plasma spray processes.

Keywords

• Plasma-sprayed coatings
• Surface structures
• Wetting behaviors
• Mechanical robustness