The Effect of Oxygen on the Inhibition of Copper Corrosion with Benzotriazole

Abstract

The inhibition of copper corrosion by benzotriazole ͑BTAH͒ has been studied by scanning electrochemical microscopy as a function of time and oxygen content. Under normal atmospheric conditions the inhibiting ͓Cu͑I͒-BTA͔ film was formed in approximately 1 h. When the oxygen content was lowered below 15 ppm, an insulating film could not be obtained in 4 h, clearly showing that the formation of the inhibiting ͓Cu͑I͒-BTA͔ requires oxygen.

Application of AC‐SECM in Corrosion Science: Local Visualisation of Inhibitor Films on Active Metals for Corrosion Protection

“…All aqueous solutions were prepared with ultrapure water purified with a Milli-Q system from Millipore. Inhibitor films were produced on the copper electrode ex situ by dipping the metal samples in the inhibitorcontaining solution for six different immersion times (5,10,15,30,45 and 60 min).…”

“…The protective effect is considered to arise from the inhibitor-containing film on the metal and not from the copper oxide layer, since the reported effect was also found with conventional SECM on polarised copper samples for varying oxygen concentrations in the electrolyte. [30] Note that a perfectly insulating barrier film is not produced with the dipping procedure employed in this work, even for the longest pre-treatment employed. A perfect insulating barrier would have resulted only in the measurement of negative feedback AC approach curves even at the highest frequencies.…”

“…These layers introduce a physical barrier between the underlying metal and the electrolytic environment, and greatly hinder the investigation of such highly resistive systems. This is reflected in the scarcity of publications concerning the characterization of intact polymer coatings on metals [26][27][28] or for corrosion protection with inhibitors, [29][30][31][32] though both are topics of major interest in the corrosion sciences. Moreover, the possible transport of the added redox mediator through the surface layers into the polymer matrix and towards the metal/organic film interface cannot be neglected, at least for sufficiently long exposure times.…”

“…[46][47][48] The only antecedents for such studies employing microelectrochemical scanning techniques are the SECM-based investigations of benzotriazole films using zapproach curves on polarised copper by Mansikkamäki et al, [29][30][31] and on non-polarised copper samples using both z-approach curves and 3D topographic maps of the surface by Izquierdo et al [32] In those studies, however, ferrocene/ methanol had to be added to the test electrolyte to serve as freely diffusing redox mediator, though it might influence the corrosion process on the metal surface.…”

Effect of hydrodynamic conditions on copper pitting corrosion inhibition in hydrocarbonate–chloride solutions by benzotriazole

“…The difference between the BTAH concentrations required for full PC suppression on a copper SDE and RDE was probably due to the fact that a protective polymeric layer [Cu(I)-BTA] n was formed more readily on an RDE because of a significantly higher O 2 concentration [10,11] in the reaction zone compared to SDE.…”