Study on the Corrosion Resistance of Superhydrophobic Ni-Co-P-BN(h) Nanocomposite Coatings Prepared by Electrochemical Machining and Fluorosilane Modification

In this work, a superhydrophobic surface was fabricated on 45 steel substrates by using electrochemical machining to improve the corrosion resistance of Ni-Co-P-BN(h) nanocomposite coatings. The surface morphology, chemical composition, crystalline structure, surface roughness and wettability of the samples were investigated with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), laser scanning confocal microscopy (LSCM) and water contact angle measurements, respectively. The corrosion resistance of the samples was investigated in a 3.5 wt% NaCl solution using an electrochemical workstation. The results showed that the current density and processing time in electrochemical machining significantly influenced the wettability. The Ni-Co-PBN(h) nanocomposite coatings exhibited a superhydrophobic surface under suitable process parameters. Evaluation of this superhydrophobic surface revealed an average water contact angle of 153.2 degrees and a sliding angle of 5 degrees in the contact angle test. In addition, the polarization curve in the electrochemical test indicated that the superhydrophobic surface exhibited a lower corrosion current density (I-corr) of 0.14 mu A/cm(2) and a higher polarization resistance (R-p) of 131.40 k Omega. cm(2) when compared with those of the normal samples. The above results showed that Ni-Co-P-BN(h) nanocomposite coatings with superhydrophobic surfaces could provide improved corrosion resistance.