Particle size-dependent anti-corrosion and mechanical behavior of green-graphene composite

Abstract

In this study, Green graphene (GG) was synthesized from residual agricultural biomass through pyrolysis and prepared various sizes (2D, 37 μm, 45 μm, 53 μm, and 100 μm) via mechanical and liquid phase exfoliation. These GG samples were incorporated into an EP matrix, forming GG/EP composite coatings for carbon steel. Corrosion resistance was assessed via PDP and EIS techniques. The 37 μm-GG/EP composite coating also showed uniform distribution and compact surfaces. The 37 μm-GG/EP composite coating displayed higher corrosion inhibition (99 %) owing to the even distribution of GG within the EP matrix than the uncoated, along with enhanced hydrophobicity, tensile strength (61.3 %), fracture strain (77.2 %), and toughness (90.5 %) than pure EP coating. Improved corrosion resistance, which was found related to three main factors: first, GGs enhance the coating integrity by obstructing pores and flaws, to stop corrosive media from penetrating. Second, the well-dispersed GG sheet lengthens the diffusion pathways for corrosive agents to the carbon steel substrate, consequently lenghtening the corrosion process. Third, at 37 μm size the resititve forcefields of the GG/EP structure become the most effecitve agaisnt the corrosive media. The study also establishes GG as an eco-friendly sustainable alternative of non-renewable resource based mined compounds of Zn, etc. that are universally and traditionally used, for protective coatings.