Effect of halide ions on passivation and pitting Corrosion of copper in alkaline solutions

Abstract

The passivity of copper in NaOH and borate buffer solutions wntainingcbloride, bromide and fluoride ions was studied by using cyclic voltammetry and potentiostatic current transient measurements. At scan rates 3 20 mVs-*, the addition of halide ions does not nearly affect the cyclic voltammograms in the absence of pitting. But they differ considerably in presence of pitting. The pitting potential was found to depend on the solution pH and decreased linearly with increase of logarithm of halide ion concentration.The current transients in the passivity as well as in the pitting potential regions were analyzed. Before the pitting, i-time curves were rather similar to those obtained in the plain solutions. At times >20 seconds, the current varies linearly with the reciprocal of the square root of time indicating diffusional characteristics of the metal corrosion through the passive layer. In presence of pitting, the pitting current versus time relations fit the Engell-Stolica equation.Die Passivitat von Kupfer in Chlorid-, Bromid-und Fluoridionen enthaltender Natronlauge und Boratpufferlosung wurde mit Hilfe der zyklischen Voltammetrie und der Messung der potentiostatischen Stromtransienten untersucht. Bei Vorschubgeschwindigkeit b 20 mVs-' wird durch die Zugabe der Halogenidionen das zyklische Voltammogramm fast nicht beeinfluRt, sofern keine Lochkorrosion auftritt. Liegt jedoch auch Lochkorrosion vor, so ergeben sich betrachtliche Unterschiede. Das Lochkorrosionspotential ist abhangig vom pH der Losung und nimmt mit zunehmendem Wert des Logarithmus der Halogenidkonzentration linear ab. Die Stromtransienten im Passivitatsbereich und im Bereich des Lochkorrosionspotentials wurden analysiert.Vor Beginn der Lochkorrosion sind die i-t-Kurven weitgehend tihnlich den in halogenidfreien Usungen. Nach mehr als 20s andert sich der Strom linear mit dem reziproken Wert der Quadratwunel aus der Zeit, was ein Indiz fiir die Diffusionsabhangigkeit der Metallkorrosion durch die Passivschicht ist. Wenn Lochkorrosion auftritt, so entspricht der Verlauf der Lochkorrosionsstrodzeit-Kurve der Gleichung von Engell-Stolica.

Inhibiting properties of benzimidazole films for Cu(II)/Cu(I) reduction in chloride media studied by RDE and EQCN techniques

“…This promising property is worth further exploration. Among other nitrogen containing inhibitors of copper corrosion, studied so far, are derivatives of pyrazole [44,45], benzo-hydroxamic acid [46], and secondary amines [47]. The inhibition of copper corrosion in sodium chloride solutions with piperidine derivatives was also studied [48,49].…”

Coupled mixed-potential and thermal hydraulics model for long-term uniform corrosion of copper canisters for storing spent nuclear fuel

“…Owing to the residual O2 in the tunnel and upper bentonite blocks, the canister top surface may be more prone to pitting corrosion in Cl − solutions. However, the corrosion potentials is below −0.29 VSCE were considerably lower than the pitting corrosion potentials in the range 0.4-0.9 VSCE (corresponding to pHs in the range 7.26-9.24) for the 0.1 M Cl − solution [40]. Moreover, as can be seen in Figure , between 2 and 10 years, copper is corroded and form Cu2S rather than CuCl2 -.…”

Susceptibility of copper to pitting corrosion in bicarbonate buffer solutions: Part I. Effect of chloride

“…However, localized corrosion processes can occur under aerated conditions in the presence of aggressive anions, or when the pH of the solution is increased. Many studies have been performed to investigate the pitting of Cu in a range of environments, with corrosion parameters considered to be deterministic, not distributed 18,22,26,27,29,31,54,[65][66][67] . However, we showed the stochastic nature of corrosion parameters in our previous papers 73 .…”

“…The Cu2O is commonly porous, allowing Cu 2+ ions to diffuse into solution and precipitate to form an outer layer of CuO or/and Cu(OH)2. The properties of this double-layer film on the Cu surface depend on the pH of the solution 12,17,[30][31][32] .…”