Improving the Corrosion Resistance of Steel Alloys Using Polyaniline/Graphene Nanocomposite Coatings.

In this work, a polyaniline (PANI)/graphene nanocomposite coating was applied to steel (St 37-2) alloy to enhance its physicochemical properties. The nanocomposite coating consisted of polyaniline and graphene with different weight percentages (1, 5, and 8 wt %). An electrophoretic deposition technique was utilized to apply the nanocomposite coating to the steel alloy, followed by characterization with X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). XRD patterns indicated the crystal structures for uncoated and coated samples. XRD patterns indicate the crystallinity of the nanocomposite coating due to the appearance of phases related to PANI and graphene. AFM images of the prepared graphene indicate a wrinkled structure, with a graphene sheet thickness of 46.9 nm. SEM images show a uniform and homogeneous nanocomposite coating of PANI/graphene on the steel alloy. FTIR spectra for PANI and graphene indicated the characteristic functional groups. On the other side, the FTIR spectra for the coated samples showed the same spectrum for different weight % of graphene. Corrosion behavior of the steel alloy and coated samples was studied via potentiodynamic polarization at different temperatures. Nanocomposite coating of PANI/graphene enhanced the corrosion resistance of the steel alloy by reducing the corrosion current density for the coated samples because of the uniform and dense coating layer. Also, the protection efficiency improved for the coated samples (80%-90%), which indicates the effectiveness of the nanocomposite coating in decreasing the corrosion of the coated samples.