Copper Corrosion Behavior in Simulated Concrete-Pore Solutions

Abstract

The copper corrosion was studied for 30 days in two alkaline electrolytes: saturated Ca(OH)2 and cement extract, employed to simulate concrete-pore environments. Electrochemical Impedance Spectroscopy (EIS) and Cyclic Voltammetry were carried out at the open circuit potential (OCP), and potentiodynamic polarization (PDP) curves were performed for comparative purposes. Electrochemical current fluctuations, considered as electrochemical noise (EN), were employed as non-destructive methods. The tests revealed that sat. Ca(OH)2 is the less aggressive to the Cu surface, mainly because of the lower in one order pH. In consequence, the OCP values of Cu were more positive, the polarization resistance values were higher by one order of magnitude, and the anodic currents of Cu were lower than those in the cement extract. The analyzed EN indicated that the initial corrosion attacks on the Cu surface are quasi-uniform, resulting from the stationary persistent corrosion process occurring in both model solutions. XPS analysis and X-ray diffraction (XRD) patterns revealed that in sat. Ca(OH)2, a Cu2O/CuO corrosion layer was formed, which effectively protects the metallic Cu-surface. We present evidence for the sequential oxidation of Cu to the (+1) and (+2) species, its impact on the corrosion layer, and also its protective properties.

Corrosion Activity of Carbon Steel B450C and Low Chromium Ferritic Stainless Steel 430 in Cement Extract Solution

“…Furthermore, a major concern is the composition of alkaline solutions, which may influence the corrosion resistance of steels, as well as the composition of the corrosion products formed [26][27][28][29][30][31][32]. Few works have proposed the use of cement extract solution, which may provide variety with regards to the ions found in the concrete pores in real conditions [33][34][35][36][37]. There is still considerable controversy about the effect of the composition of the model solution on the electrochemical behavior of steels [38].…”

Corrosion Effects on Durability of RC Structures

“…Five research papers have been published in Special Issue of Metals titled Corrosion Effects on the Durability of RC Structures. The collected articles deal with several aspects of the corrosion phenomenon in reinforced concrete, including the copper corrosion behavior in simulated concrete-pore solutions [1], the influence of microstructure on the corrosion resistance of steel bars and their fatigue behavior [2], the degradation of bond mechanism between steel and concrete [3,4], and the flexural capacity of corroded Prestressed Reinforced Concrete (PRC) beams [5].…”

Corrosion inhibition of copper in ferric chloride solutions with organic inhibitors

“…Figure 5b includes a constant phase element (CPE), which represents a non-ideal capacitance and replaces the double-layer capacitance (C dl ) with the aim of better matching the measurement results and the equivalent circuits. The use of CPE takes into consideration surface characteristics such as surface roughness, discontinuity of the inhibitor layer adsorbed on the metal surface, and inhomogeneity in the conductance or dielectric constant, which cause a non-uniform distribution in C dl 32,46,48 . Poor surface uniformity may be related, for example, to a pore structure through which electrolyte, ions and neutral molecules could permeate 48 .…”

“…where Y 0 is the magnitude of the CPE, ω is the angular frequency, and α the exponential term of the CPE 32,46 . The α values range from 0 to 1, the former representing an ideal resistor whereas the latter representing an ideal capacitor 48 . The inhibition efficiency was calculated using Eq.…”