A study of the behavior of copper electrodes in buffered borax solutions containing BTA‐type inhibitors by photoelectrochemical methods

Abstract

Purpose

The purpose of this paper is to provide useful information pertaining to the corrosion inhibition mechanism of BTA and its derivatives on copper.

Design/methodology/approach

The photoelectrochemical behavior of copper electrodes in buffered borax solutions (pH 9.2) containing BTA and its derivatives was comparatively studied by using a photoelectrochemical technique. It was possible to analyze the inhibition mechanism of the derivatives of BTA for copper corrosion from the photoelectrochemical results. The photoresponse of the Cu electrode in buffered borax solutions containing BTA and its derivatives was measured. Different concentrations and different kinds of inhibitors may result in different photoresponses on the Cu electrode in buffered borax solutions.

Findings

The photoresponse for copper electrodes in solutions containing a certain amount of BTA exhibits an n‐type response during anodic polarization and, the greater the n‐type photoresponse, the better the performance of the inhibitor. The photoresponse for copper electrodes in solutions containing 4CBTA, or 5CBTA, or CBT‐1, always exhibited p‐type behavior during anodic polarization, but the photoresponse changed very evidently during cathodic polarization. The larger the maximum cathodic photocurrent, then the greater was the effectiveness of the corrosion inhibitor. In consequence, it is possible to evaluate inhibitors according to Φ_V and i_ph at more negative potentials. The more negative the Φ_V and i_ph, the better is the inhibition. It was shown that the inhibition mechanism of the derivatives of BTA with a −COOH group was different from that occurring with ester groups. The former could make the Cu₂O film on the Cu electrode thicker. The photocurrent was observed to increase when the potential was scanned to more negative potentials in the presence of certain concentrated inhibitors. It is therefore possible to evaluate the performance of inhibitors according to the value of the cathodic photocurrent. The larger the cathodic photocurrent, the better is the inhibition effect of the compound. The latter could increase the density of the polymer film on the copper electrode and prevent O²⁻ in the solution from entering the copper surface and changing the stoichiometric ratio of Cu₂O. The photocurrent type could transfer from p‐ to n‐type according to the action of certain concentrated inhibitors when the potential was scanned to more positive potentials. The value of the anodic photocurrent can be used to evaluate the effectiveness of inhibition. The larger the anodic photocurrent, the greater is the inhibition effect.

Originality/value

The paper provides useful information pertaining to the corrosion inhibition mechanism of BTA and its derivatives on copper. The photoelectrochemical technique is an effective method with which to evaluate the effectiveness of corrosion inhibitors and to investigate the mechanism of corrosion inhibition on copper.

Citation

Xu, Q. and Zhou, G. (2008), "A study of the behavior of copper electrodes in buffered borax solutions containing BTA‐type inhibitors by photoelectrochemical methods", Anti-Corrosion Methods and Materials, Vol. 55 No. 6, pp. 303-307. https://doi.org/10.1108/00035590810913088