Corrosion inhibition of magnesium alloy AZ31 in chloride-containing solutions by aqueous permanganate

Abstract

In this work, corrosion of the AZ31 magnesium alloy was examined in 0.05 M NaCl solutions containing 0.01–0.150 mol/dm3 of potassium permanganate as a corrosion inhibitor. A set of electrochemical impedance spectroscopy, linear sweep voltammetry, and hydrogen evolution measurements revealed high inhibitor effectiveness at relatively high (0.150 mol/dm3) KMnO4 concentrations. Based on data of energy-dispersive X-ray analysis, scanning electron microscopy, and Raman spectroscopy, a mechanism of the corrosion inhibition of AZ31 alloy by potassium permanganate in chloride-containing media was proposed.

Corrosion Inhibition of AZ31-xLi (x = 4, 8, 12) Magnesium Alloys in Sodium Chloride Solutions by Aqueous Molybdate

“…This results in an increased current density over unprotected areas and, consequently, an increased corrosion rate. The same behavior was previously observed for the WE43 and AZ31 alloys in the case of the molybdate and permanganate inhibitors [31,38,39]. At higher added concentrations, Na2MoO4 caused a pronounced decrease in icorr.…”

“…The latter usually act as precipitation-type inhibitors and their effectiveness is strongly related to the microstructure of a Mg alloy, since the inhibition is usually based on retarding the cathodic activity of IMPs. In our previous works [31,38,39], we have shown that inorganic oxidizing anions, such as permanganates and molybdates, are effective inhibitors for the corrosion protection of AZ31 and WE43 alloys. In the case of the AZ31 alloy, the inhibition mechanism is based on the formation of a surface oxide layer suppressing the cathodic activity of IMPs and the anodic activity of the Mg matrix.…”

“…As a reference corrosion medium, 0.05 M NaCl solution was selected. This concentration of salt prevents rapid degradation of Mg alloys and was previously used in our studies of inorganic corrosion inhibitors of Mg and Al alloys [31,38,39,49]. The effectiveness of the molybdate inhibitor was examined in 0.05 M NaCl with the concentration of the inhibitor varying in the range of 10-150 mM.…”

“…( 2)) were similar to those of the potentiodynamic measurements. The EIS data were analyzed and fitted following the approach proposed in [43] and used in our previous publications [31,38,39]. To minimize the possible overestimation of the corrosion resistance and fitting error, the fitting was performed by the equivalent circuit shown in Fig.…”

Effect of Graphene Oxide as an Anodizing Additive for the ZK60A Magnesium Alloy: Correlating Corrosion Resistance, Surface Chemistry and Film Morphology

“…Nyquist plots of the uncoated and anodized ZK60A alloy obtained in 3.5 wt.% NaCl solution at room temperature are shown in Figure 10a. The diameter of the semicircle is associated with the charge transfer resistance of the electrode surface [55,56]. The plot of the uncoated ZK60A alloy can be barely seen in Figure 10a, as it exhibits a capacitive loop whose diameter is much smaller than those of the anodized samples, thus indicating that the anodizing treatment greatly enhanced the corrosion resistance of the alloy.…”