Inhibition mechanism and warning performance of corrosion inhibitor and fluorescent indicator combinations on AA2024-T3

Abstract

To elucidate the inhibition mechanisms and determine the interaction concentration thresholds while ensuring effective corrosion warning, a systematic combination of corrosion inhibitors (BTA, 2-MBT, Ce(NO₃)₃, Na₃VO₄) and fluorescent agents (8-HQ, SA) was conducted at various concentrations. Based on the high-throughput microdroplet array test, contour plots illustrating the corrosion rates for various combinations of inhibitors and indicators were generated. The extensive region in the contour plots depicting a corrosion rates below 2 for BTA and 8-HQ combination highlights a pronounced synergistic corrosion inhibition effect, consistent with the Langmuir isotherm adsorption model and indicative of mixed adsorption behavior. In contrast, the SA and 8-HQ mixture demonstrates a significant antagonistic effect in certain ratios, aligning more closely with the Frumkin adsorption model due to the strong intermolecular interactions facilitated by hydrogen bonding. Across the whole range of concentrations, the combination of 0.8 mM BTA and 2 mM 8-HQ achieves a synergism factor that significantly exceeding 1, along with the exceptional corrosion inhibition efficiency of up to 99.37 %. This remarkable performance is associated with a maximum binding energy of 157.17 kcal/mol, primarily attributed to the enhanced adsorption of 8-HQ facilitated by BTA. Moreover, this combination exhibited a strong fluorescence response and high sensitivity for dipping corrosion monitoring, making it an ideal choice for both corrosion protection and warning in 2024-T3 aluminum alloy.