Superhydrophobic anticorrosion coating with active protection effect: Graphene oxide-loaded inorganic/organic corrosion inhibitor for magnesium alloys

In this study, we developed a superhydrophobic coating that provides active protection against corrosion on magnesium alloys. Graphene oxide (GO) served as a nanocontainer, loaded with molybdate (an inorganic corrosion inhibitor) and dopamine (an organic corrosion inhibitor). The hydrophobic effect was amplified by the addition of octadecylamine. By uniformly dispersing this intelligent nanocontainer in an organic coating, the coating is endowed with the ability to actively protect against corrosion spread. The resulting superhydrophobic coating exhibits an outstanding hydrophobic effect, with a water contact angle (WCA) of 161.35 ± 2°. In addition, the coating showed exceptional stability in each of the four extreme test conditions, as well displayed excellent electrochemical properties. The corrosion rate of the superhydrophobic coating was determined statistically and computationally to be 9.12 × 10 −6  mm/year. At a frequency of 0.01 Hz, the impedance modulus (|Z|) and polarization resistance (R p ) were measured to be 2.24 × 10 8  Ω cm 2 and 6.07 × 10 8  Ω cm 2 , respectively. Following a 28-day immersion in a 3.5 wt% NaCl solution, |Z| f=0.01 Hz and R p both remained at 1.25 × 10 8  Ω cm 2 and 1.69 × 10 8  Ω cm 2 , respectively. The coating demonstrated robust, active protection capabilities. After a 12-h immersion in water, the wounded portion of the coating significantly lightened, and the electrochemical properties substantially recovered. This study offers novel insights and methodologies for addressing the corrosion issues of magnesium and its alloys. It emphasizes how the superhydrophobic coatings can in improve the durability and longevity of these materials.