The effect of graphene orientation on permeability and corrosion initiation under composite coatings

TL;DR

This study models how the orientation of graphene sheets in composite coatings affects corrosion protection, showing that smaller angles between graphene and the substrate significantly delay corrosion initiation.

Contribution

Introduces a novel trigonometric model linking graphene orientation to corrosion delay, validated by experimental data, advancing understanding of anisotropic graphene effects in coatings.

Findings

A 10-degree mismatch angle can delay corrosion initiation by 65 times.

The model accurately predicts corrosion parameters aligning with experimental results.

Smaller angles between graphene sheets and substrate improve corrosion resistance.

Abstract

The unique anisotropic properties of graphene, particularly impermeability, have made it a promising candidate for further advances in corrosion prevention applications. Despite the large number of experimental works divulging the use of graphene in anticorrosion coatings, there is no report on the numerical modelling and simulation of the relationships between the orientation of graphene sheets in composite coatings and the introduced corrosion protection efficiency, to our knowledge. Herein, it is tried to model the influence of the orientation of graphene sheets dispersed in organic coatings on the diffusivity and flux of corrosive substances besides the corrosion initiation time of the protected substrates. To discover the relationship between the graphene orientation and corrosion-related phenomena, this study introduces a novel model consisting of a trigonometric factor named unprotected projected surface area proportion, which calculates corrosion-related parameters based on the principal Fick's laws. The model reveals that the decrease in the angle between graphene sheets and the substrate is highly beneficial for postponing the corrosion onset. It is accordingly estimated that a mismatch angle of 10 degree can slow down the diffusion process significantly and delay the corrosion initiation by around 65 times in a 100 micron thick epoxy/graphene composite coating in comparison to the counterpart with the perpendicular alignment. The predicted corrosion parameters were in a good agreement with the experimental data, indicating the merit of the proposed model. Thus, this model can be further employed as the fundamental of future research on the optimum graphene orientation in anticorrosion composite coatings.