Electrochemical fabrication of superhydrophobic 304 stainless steel by neutral electrolyte

Even though 304 stainless steel (SS) has high corrosion resistance, galvanic cells formed from rainwater and impurities can accelerate corrosion and cause SS products to be destroyed. Endowing the SS with superhydrophobicity which has non-wetting, self-cleaning, and anti-icing properties is hopefully to prolong the SS's service life. However, most of the existing fabrication methods of superhydrophobic SS involve strong oxidants which are harmful to humans and the environment. If the superhydrophobic SS surface can be created by electrochemical etching with a neutral electrolyte, it does little harm to the environment and humans. Sodium chloride (NaCl) and sodium nitrate (NaNO3) are common neutral electrolytes to obtain superhydrophobic surfaces, but there are few studies on their etching effects of the wettability on 304 SS. In this paper, the effects of NaCl and NaNO3 on the surface morphology and wettability of SS were investigated in detail using various electrolyte concentrations, current densities, and etching time. The desired wettability with a contact angle of 162° and a sliding angle of 10° was obtained in NaNO3. The as-prepared 304 SS exhibited excellent superhydrophobicity, self-cleaning, anti-icing, and deicing properties, which is expected to further enlarge the application range and improve the service life of 304 SS.