Wire electrochemical etching of superhydrophobic 304 stainless steel surfaces based on high local current density with neutral electrolyte

Abstract

Possessing special wetting properties, superhydrophobic surfaces on 304 SS substrates have great application prospects in various fields. However, due to the excellent corrosion resistance of 304 SS, currently, only strong oxidants can directly process stainless steel to obtain desired structures, which poses great threats to human health and the environment. In addition, other methods, such as electrical discharge machining and coating, are relatively expensive, and the prepared surfaces tend to be fragile. Therefore, it is of great significance to find an environmentally friendly and highly efficient method to fabricate superhydrophobic surfaces on 304 SS substrates. Electrochemical etching can generate microstructures on metals with neutral electrolytes; nevertheless, there has been no report on fabricating superhydrophobic 304 SS surfaces by electrochemical etching with neutral electrolytes owing to the excellent corrosion resistance of 304 SS. In this paper, wire electrochemical etching with neutral sodium nitrate is adopted for the first time to fabricate superhydrophobic surfaces on 304 SS substrates. Based on theoretical analysis, superhydrophobic 304 SS surfaces with contact angles of ∼ 166° and roll-off angles of ∼ 10° are successfully fabricated. The prepared superhydrophobic 304 SS surfaces show excellent anti-icing performance and self-cleaning properties, which may greatly facilitate the application of 304 SS in extreme conditions.