Overview
Graphene and related 2D materials such as graphene oxide (GO) are atom-thin platelets that block the passage of gases and liquids. Added to coatings, they promise a longer, more tortuous path for water, oxygen and ions. Their electrical conductivity, however, can interact with the metal underneath in ways that matter for corrosion.
Key findings
- A continuous film of CVD-grown graphene protected copper and copper/nickel alloy from oxidation in hot air for several hours and also resisted hydrogen peroxide, demonstrating its potential as an ultrathin barrier.[1]
- Polyaniline/graphene composite coatings were developed and studied as anticorrosion coatings for steel, with graphene platelets intended to improve barrier performance.[2]
- The caveat: graphene protected copper in the short term but, over longer exposure, promoted wet corrosion more extensive than on bare metal, attributed to galvanic coupling at defects in the conductive graphene layer.[3]
- As a filler in polymer coatings, graphene can also accelerate corrosion. Insulating the platelets, for example by wrapping reduced graphene oxide with a silane, improved barrier performance and suppressed the corrosion-promotion effect in scratch tests.[4]
- Reviews of graphene-based anticorrosive coatings identify dispersion in the resin and control of defects as recurring practical challenges.[5]
What it means in the field
For specifiersWell-dispersed, functionalized or electrically insulated graphene and GO fillers can improve the barrier performance of epoxy and polyurethane primers. Poorly dispersed or conductive graphene can worsen corrosion at scratches and holidays. Ask suppliers for long-term scribed salt-spray or electrochemical data, not just short-term results or marketing claims.
References
- Chen S, Brown L, Levendorf M, et al. (2011). Oxidation resistance of graphene-coated Cu and Cu/Ni alloy. ACS Nano, 5(2), 1321–1327. doi:10.1021/nn103028d
- Chang CH, Huang TC, Peng CW, et al. (2012). Novel anticorrosion coatings prepared from polyaniline/graphene composites. Carbon, 50(14), 5044–5051. doi:10.1016/j.carbon.2012.06.043
- Schriver M, Regan W, Gannett WJ, et al. (2013). Graphene as a long-term metal oxidation barrier: worse than nothing. ACS Nano, 7(7), 5763–5768. doi:10.1021/nn4014356
- Sun W, Wang L, Wu T, et al. (2015). Inhibiting the corrosion-promotion activity of graphene. Chemistry of Materials, 27(7), 2367–2373. doi:10.1021/cm5043099
- Cui G, Bi Z, Zhang R, et al. (2019). A comprehensive review on graphene-based anti-corrosive coatings. Chemical Engineering Journal, 373, 104–121. doi:10.1016/j.cej.2019.05.034
Citations were checked against publisher, DOI or agency records. Summaries are paraphrased; read the original papers for full methods and data.