Facile fabrication and repair of superhydrophobic metal surfaces via electric spark deposition with oil

Recent research has focused on the durability of superhydrophobic surfaces, and some methods have reported improvements in the resistance of surfaces to abrasion from several sandpaper treatment cycles with the goal of maintaining a contact angle (CA) > 150 degrees. However, the surface water repellency is lost because of the numerous abrasive cycles causing significant mechanical damage. Repairing the superhydrophobicity of the material is necessary when the surface is damaged. Current repair methods have different limitations, such as special abrasion conditions or limits on the substrate size and working conditions. Here, we demonstrate that using electric spark deposition with oil can create a superhydrophobic surface in a single step. This represents a facile method that can be carried out by hand with fewer limitations on its working conditions and the substrate location and shape. The morphology and chemical composition of the coating was investigated. The addition of octadecanoic acid to the oil provided a stable CA > 150 degrees for the coated surface. The coated surface lost superhydrobhobicity after being subject to three different damaging processes, and the superhydrophobicity could be recovered after recoating.