Chloride-Assisted Corrosion of Copper and Protection by Benzotriazole

Corrosion inhibitor distribution on abrasive-blasted steels

HYPOTHESIS

Abrasive-blasted steel surfaces exhibit a complex, multi-substrate environment. Adsorption to contaminant substrates can reduce the amount of available corrosion inhibitor and decrease its efficiency. Knowledge of where inhibitors preferentially adsorb is required.

EXPERIMENTS

The quantitative extent and strength of adsorption of the representative corrosion inhibitor benzotriazole (BTAH) from toluene to particular substrates is given, including corrections for solution self-association, and complemented by X-ray photoelectron spectroscopy (XPS), sum-frequency generation spectroscopy (SFG), and quartz crystal microbalance (QCM) measurements.

FINDINGS

All substrates show adsorbed BTAH layers. Based on the adsorption strength, preferential adsorption is found to be in the order steel > iron oxide > calcium carbonate and garnet > silica - this is relevant when there is limited BTAH. However, with ample BTAH, the amounts adsorbed in the plateau regions of the isotherm are more relevant and the order is calcium carbonate and silica > iron oxide > garnet > steel. Although the contaminant substrates deplete the BTAH concentration, the steel should still have a complete monolayer of BTAH inhibitor. This work is part of a larger initiative developing novel methods of corrosion inhibitor delivery via the blasting process, to prevent corrosion between blasting and repainting.

Feasibility of Carbon Nanoparticle Coatings as Protective Barriers for Copper─Wetting Assessment

Copper is extensively used in a wide range of industrial and daily-life applications, varying from heat exchangers to electrical wiring. Although it is protected from oxidation by its native oxide layer, when subjected to harsh environmental conditions─such as in coastal regions─this metal can rapidly degrade. Therefore, in this study, we analyze the potential use of carbon nanoparticle coatings as protective barriers due to their intrinsic hydrophobic wetting behavior. The nanocarbon coatings were produced via electrophoretic deposition on Cu platelets and characterized via scanning electron microscopy, confocal laser scanning microscopy, and sessile drop test; the latter being the primary focus since it provides insights into the wetting behavior of the produced coatings. Among the measured coatings, graphite flakes, graphene oxide, and carbon nanotube (CNT) coatings showed superhydrophobic behavior. Based on their wetting behavior, and specifically for electrical applications, CNT coatings showed the most promising results since these coatings do not significantly impact the substrate's electrical conductivity. Although CNT agglomerates do not affect the wetting behavior of the attained coatings, the coating's thickness plays an important role. Therefore, to completely coat the substrate, the CNT coating should be sufficiently thick─above approximately 1 μm.