Enhancement of low carbon steel corrosion resistance in acidic and saline media using superhydrophobic nanocomposite

Superhydrophobic anticorrosion layers of various thicknesses were deposited onto low carbon steel. The layer is comprised of MnO2/Polystyrene nanocomposite with a hierarchical structure. AFM imaging of the nanocomposite illustrated a very rough surface with rms roughness of 109 nm. A polarization method was applied to measure the corrosion potential and corrosion current by using a potentiostat device. Two corrosive solutions were utilized in this study (NaCl & HCl). Strong concentrations of 1M HCl and 5000ppm NaCl were used in this work. The results revealed that the nanocomposite exhibits better corrosion inhibition after 24h immersion time in NaCl compared to HCl, where the corrosion current density is 0.56 μA/cm2 in NaCl against 24.3 μA/cm2 in HCl. The uncoated sample presented a higher corrosion current density after 24h immersion time with values of 14.4 μA/cm2 and 83.6 μA/cm2 in NaCl and HCl, respectively. Moreover, the ultrathin layers of the nanocomposite demonstrated better corrosion inhibition than the relatively thicker layers. This result was elucidated by the peeling effect of the thick samples. Immersion time was also considered in this study by leaving the samples over a course of 30 days in the solution and performing the measurements for every 10 days’ span. The activation energy of the surface was determined using Arrhenius method by varying the solution temperature during measurements. Corrosion protection efficiency showed excellent results with up to 96.1% in NaCl solution. Pitting potential was also determined in this work.