Abstract
The pitting corrosion of copper in alkaline solutions in the presence of benzotriazole (BTA) was investigated. The presence of BTA shifts the breakdown (E b) and the repassivating (E p) potentials positively with respect to the blanks. However, the shift ofE p becomes smaller than that ofE b, particularly at pH9 and 11. Pitting corrosion involves the formation of crystallographic pits. The kinetics of the process fits a nucleation and growth mechanism involving instantaneous nucleation and 3D growth under charge transfer control. The spatial distribution of pits indicates that there is no marked influence of a pit on the nucleation and growth of other pits.
Highlights
Protection characteristics of anodic layers in relation to the corrosion and passivation of copper in aqueous solutions of different electrolyte composition were extensively investigated over a wide range ofpH [1, 2]
The structure of the passivating layers formed on copper in alkaline solutions in the absence of inhibitors was related to a composite duplex layer consisting of an inner Cu(I) oxide layer and an outer Cu(II) oxide layer [3,4,5,6,7], their stability and protective characteristics depending considerably on the applied potential range and the composition of the solution
At the three pH values the voltammograms recorded at 0.01Vs -~ in 1M NaCIO4 (Fig. 1, dotted traces) and in I mM BTA + 1M NaC104 (Fig. 1, full traces) exhibit two well defined potential ranges related to the passivity and to the corrosion of copper
Summary
Protection characteristics of anodic layers in relation to the corrosion and passivation of copper in aqueous solutions of different electrolyte composition were extensively investigated over a wide range ofpH [1, 2]. The structure of the passivating layers formed on copper in alkaline solutions in the absence of inhibitors was related to a composite duplex layer consisting of an inner Cu(I) oxide layer and an outer Cu(II) oxide layer [3,4,5,6,7], their stability and protective characteristics depending considerably on the applied potential range and the composition of the solution. A kinetic model based upon the nucleation and growth mechanism is presented for describing the breakdown of the protective layer formed on copper in the presence of BTA
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