The r-GO/oil coating is scratch-tolerant and protects metal wires from localized corrosion. (a) Schematic illustration of the experimental procedure testing the effects of localized corrosion on the mechanical properties of brass wires. A wire is first coated with a barrier film and then scratched to expose a small area before being immersed in etching solution (5.5 M or 17% HCl). After etching, tensile tests are performed to directly evaluate corrosion-induced damage. (b) Representative stress-strain curves of an unetched wire, etched wire, etched wire with an unhealable coating, and etched wire with the r-GO/oil coating. (c) A bar graph summarizing changes in tensile strength and the mass of the wires tested in (b). The unprotected wire loses nearly 40% of mass and over 90% of strength after 1 week. The polymer-coated wire has negligible mass loss, even after 2 weeks, but its strength is decreased by about half, due to localized corrosion at the scratch. The wire coated with the self-healing r-GO/oil film retains its original mechanical properties and is not affected by the scratch.