Electrophoretically deposited graphene oxide–polymer bilayer coating on Cu-Ni alloy with enhanced corrosion resistance
For an actual study an environmentally benign and facile bilayer coating comprised of graphene oxide (GO) and acrylic polymer has been fabricated over a cupronickel sample.
This was done by using electrophoretic deposition followed by dip coating. The infrared, Raman, and field emission scanning electron microscopy (FESEM) studies of the bilayer coating confirm the noncovalent functionalisation of GO through H-bonding with acrylic polymer, reduction in local defects in GO structure, and distorted spherical void peripheries of polymer coating, respectively.
The FESEM cross-sectional analysis showed that the coating thickness is 5–6 µm.
Increase in the corrosion resistance
The bilayer-coated sample showed a three- to fourfold increase in the corrosion resistance, as compared to GO-alone-coated sample in 3.5% (w/v) NaCl electrolyte, which is attributed to the reduction in the local defects in GO coating and the galvanic coupling between the GO and sample surface.
The GO sheets make the diffusion pathway of corrosive media more tortuous for corrosive ions to reach the metal surface. The lower anodic current density observed with the new bilayer coating after 30 days of exposure confirms the active corrosion protection. The coating was intact and stable after 30 days of exposure in chloride medium with a water uptake of about 32.7%.
The study has been published in Journal of Coatings Technology and Research, Volume 16, pages1317–1335.
Image source: Pixabay.
