Superhydrophobic, self-cleaning carbon nanofiber CVD coating for corrosion protection of AISI 1020 steel and AZ31 magnesium alloys

Abstract Global corrosion damages mandate the synthesis of superhydrophobic, self-cleaning protective surfaces possessing excellent mechanical, chemical, and thermal stability. Thus, a self-cleaning, superhydrophobic carbon nanofiber (CNF) coating on structural alloys AISI 1020 mild steel (MS) and Mg alloy (AZ31) with water contact angle (CA) 145°–150° and sliding angle of 7° ± 2° is fabricated by a novel two-step process of plasma sputter followed by CVD. An extraordinary self-buoyancy of the deposited CNFs coating was observed to be ~378 and ~257 times than that of its own deposited mass on the coated MS and AZ31, respectively. Further, the CNF coated MS, and AZ31 alloys displayed performance of corrosion protection efficiency of about 97% in 3.5 wt NaCl corrosive environment with a lower corrosion current density (Icorr = 0.16 and 14.90 μA/cm2 respectively) than that of uncoated one (Icorr = 5.56 and 691.8 μA/cm2, respectively). The charge transfer resistance (Rct) was obtained to be ~ four and two orders of magnitude greater than the uncoated MS (1.4 kΩ cm2) and AZ31 (2.0 kΩ cm2) alloys, respectively. Thus, this simple and straightforward process of making corrosion resistance superhydrophobic CNF coating can be potentially used for protecting structural alloys in various engineering applications.