A robust quasi-superhydrophobic ceria coating prepared using air-plasma spraying

Hydrophobic coatings that could survive in harsh environment have a wide range of applications from industry to houseware. However, the state-of-the-art polymer-based coatings cannot meet such requirements due to their low melting point and poor wear resistance. In this study, we reported a plasma sprayed ceramic coating made of ceria with exceptional hydrophobicity, high-temperature stability, and good wear resistance. The coating exhibited a water contact angle (WCA) up to 139°, due to the intrinsic hydrophobicity of ceria and unique surface morphology produced by plasma spraying. The WCA only slightly decreased to 131° after annealing at 773 K. In addition, the polished coating (WCA ~ 116°) was still more hydrophobic than the sintered bulk specimen (WCA ~ 95°) with the same composition and roughness, which can be attributed to the surface chemistry change induced by Ar⁺ ion bombing by plasma. It is believed that such robust hydrophobic coating should have great potential in engineering application.