Evaluation of corrosion inhibitor performance under droplet conditions on steel†

Corrosion inhibitors play a crucial role in mitigating metal degradation, yet their performance varies significantly depending on environmental conditions and application methods. This study employs a high-throughput methodology utilising volume loss measurements via optical profilometry to assess corrosion inhibitor efficiency. A comparative analysis between the droplet-on-plate and full-immersion testing methods is conducted to evaluate their impacts on inhibitor performance using optical profilometry. The research delves into the chemistry of corrosion inhibitors specifically designed for droplet corrosion, where benzothiazole derivatives performed well in both environments, whereas thiazole derivatives exhibited weaker performance under droplet conditions, whilst focusing on how pH gradients evolve within a droplet over time and influence corrosion inhibitor effectiveness. Results indicate that localised pH variations significantly alter the adsorption behaviour and stability of corrosion inhibitors, affecting their protective capabilities. Furthermore, the interactions between corrosion inhibitors and oxide layers are explored, revealing that anodic inhibitors tend to accumulate around corrosion pits, suggesting a selective protection mechanism. Those findings provide critical insights into optimising corrosion inhibitor formulations and testing methodologies for sound corrosion assessments.