Electrochemical corrosion behavior and surface passivation of bulk nanocrystalline copper in alkaline solution

Abstract

Purpose This paper aims to focus on an assessment of the electrochemical corrosion performance of bulk NC copper in a variety of corrosion environments. Design/methodology/approach The electrochemical corrosion behavior of bulk nanocrystalline (NC) copper prepared by inert gas condensation and in situ warm compress technique was studied by using potentiodynamic polarization and electrochemical impedance spectroscopy tests in de-aerated 0.1 M NaOH solution. Findings NC copper exhibited a typical active-passive-transpassive behavior with the formation of duplex passive films, which was qualitatively similar to coarse-grain (CG) copper. Although a compact passive film formed on NC copper surface, the corrosion resistance of NC copper was lower in comparison with CG copper. The increase in corrosion rate for NC copper was mainly attributed to the high activity of surface atoms and intergranular atoms. These atoms led to an enhancement of passive ability and an increase of dissolution rate of passive film in oxygen-deficiency solution. For NC copper, the corrosion resistance decreased as grain size increased in NC range. Originality/value The difference in corrosion resistance between bulk NC copper and its CG counterpart is dependent upon the corrosion solution. In a previous work, the potentiodynamic polarization tests revealed that NC copper bulks (grain size 48, 68, 92 nm) had identical corrosion resistance to CG copper bulk in naturally aerated 0.1 M NaOH solution. The results might be related to the dissolved oxygen in the medium.

Morphological Stability of Copper Surfaces under Reducing Conditions

“…Our findings are in contradiction with current literature, wherein it is often proposed that the catalyst deactivation observed for Cu surfaces is possibly due to changes in the surface morphology resulting in facet redistribution, ,,− , as induced in some manner by the reaction environment (e.g., due to the applied potential, ,, or due to (CO2RR intermediate-related) adsorbates, or due to the local pH, , or other factors). However, a comparatively much simpler explanation underlying reported changes in surface morphology exists: accidental surface oxidation and subsequent anisotropic (Figures and ) reduction of the surface (likely in concert with dissolution and redeposition), as also proposed by Popovic et al, where the rate of reduction of these oxides is likely to influence the final morphology.…”

Analysis on corrosion of aluminum-based micro-arc oxidation coating

“…Based on the PDP curves, two important parameters can be determined: the corrosion potential ( E corr ) and corrosion current density ( I corr ). Here, the E corr is associated with the stability of the samples and the I corr is important to evaluate the kinetic of corrosion reactions (Wei et al , 2016; Sun et al , 2017; Luo and Hu, 2020). The E corr and I corr have been calculated based on the Tafel extrapolation (Lu et al , 2015), as listed in Table 1.…”

Effect of strain energy on corrosion behavior of ultrafine grained copper prepared by severe plastic deformation

“…SSE processed sample at eight passes represented a non-equilibrium grain boundary state, having higher dislocation density than coarse grain material. It may promote the activation energy associated with the dissolution process [21][22][23][24][25]. After twelve passes, the non-equilibrium grain boundaries transformed into equilibrium grain boundaries due to large deformation.…”