(241a) Plant Protecting Plant: Investigating A Novel Biographene Growth Method On Fe For Corrosion Protection

Corrosion, a natural phenomenon, involving simultaneous oxidation and reduction reactions, leads to enormous economic losses worldwide. Several industrial applications including piping, cooling systems, boilers, heat exchangers, water treatment plants, etc. use metallic materials in the presence of saline media. Aggressive chloride ions in such media destabilize the passivation of even high chromium/nickel stainless steels as well as other normally-corrosion-resistant transition metals and lead to corrosion. Currently, metal surface protection can be achieved through several approaches including coating with other metals, chemical modification, anodizing, use of an oxide layer, and of organic layer/polymer coating. Recently, interest has piqued into using graphene as an ideal candidate for corrosion inhibition due to its unique properties like high electrical conductivity, transparency and chemical impermeability. Since its discovery, graphene has been successfully grown on Cu and Cu/Ni alloys using chemical vapor deposition (CVD). However, iron (Fe) is one of the most widely used metal in industry and chemical plants but to date, uniform graphene layers have not been able to be grown on this metal.

This work has the ambitious goal of making Fe corrosion-proof to increase its service life. The innovation lies in both the feedstock used and the carefully chosen process operating conditions. First, unlike the current state-of-the art method, Chemical Vapor Deposition (CVD), which mainly uses gaseous hydrocarbons, our process uses a solid renewable carbon source (biochar: carbon-rich residue left after hydrothermal carbonization (HTC) of biomass) to grow (bio)graphene on metal sheets like Fe. The mechanism is not deposition-based (CVD: weaker graphene-metal interaction) but rather dissolution-precipitation-based (stronger Fe-C affinity). This makes the adhesion of the graphene coating stronger, providing better corrosion protection when compared to the weaker CVD-grown graphene. Second, CVD is usually performed under high vacuum in the presence of H₂. Our process operates at atmospheric pressure and is H₂-free. Third, the Fe foils are used ‘as is’ without any pretreatment. These process conditions, being less harsh, are safer and more economical. Fourth, multilayer graphene, produced by our proposed process, has been shown to be better for corrosion prevention (CVD tends to produce single layer graphene). Fifth, any size of metal sheet can be “coated” with the graphene as this process is easily scaled up with the size of the furnace only and does not have to factor in the cost of vacuum and hydrogen to be used. Lastly, our process grows graphene on both sides of the foil simultaneously for better corrosion protection not only from the outside aggressive atmosphere but also from the internal corrosive material the pipe or vessel is carrying. We will be sharing some preliminary results obtained along with some analysis done using X-ray Diffraction (XRD), Raman spectroscopy and corrosion testing to explore our newly patented facile method to grow uniform (bio)graphene layers with high coverage on Fe for corrosion prevention.