Fabrication and Properties of Superhydrophobic Colored Stainless Steel Surface for Decoration and Anti-Corrosion

A colored superhydrophobic surface on a stainless steel substrate was achieved by means of high temperature oxidation combined with subsequent spraying modification by superhydrophobic nano-silica film. Comprehensive characterizations of the surface were performed in terms of color, morphology, composition, wettability, and corrosion resistance by optical microscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), contact angle, potentiodynamic polarization, and electrochemical impedance spectroscopy measurement. At 400 degrees C, the surface was pale yellow, gradually turning yellow and then red as the temperature increased. At 700 degrees C and 800 degrees C, the surface colors were blue and dark brown, respectively. The samples with oxide films demonstrated lower contact angles, specifically 80.5 degrees +/- 2.5 at 400 degrees C, 79.1 degrees +/- 2.8 at 500 degrees C, and 75.6 degrees +/- 3.4 at 600 degrees C. The polarization resistance measured on the oxidized film formed at 600 degrees C exceeded 7.93 x 104 Omega<middle dot>cm2. After spraying the treatment, these colorful surfaces exhibited superhydrophobicity, they were self-cleaning, and they satisfied anti-corrosion properties. The treatment performs as an excellent barrier and exhibits a high corrosion resistance of 4.68 x 106 Omega<middle dot>cm2. The successful preparation of superhydrophobic colored surfaces offers the possibility of providing stainless steel with both decoration value and self-cleaning function simultaneously by our proposed chromium-free fabrication process.