Corrosion Inhibition Study of Mg-Nd-Y High Strength Magnesium Alloy Using Organic Inhibitor
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A study on corrosion inhibition mechanism has been performed on rare earth containing WE43 magnesium alloy in 3.5 wt.% NaCl containing 8-hydroxyquinoline (HQ). After an initial increase in corrosion rate due to the formation of sparingly soluble MgQ2 complex, it was found to decrease owing to inhibition effect of the complex. Scanning electrochemical microscopic analysis showed a decrease in corrosion currents and enhanced resistance to pitting corrosion was observed for WE43 samples in the presence of HQ after an exposure of 48 h. With time, the MgQ2 thus generated formed a protective layer on the Mg alloy surface to prevent further corrosion. The corrosion rate of WE43 samples decreased by ~ 50% in HQ containing medium after a constant exposure of 28 days (from ~ 0.22 mg/cm2 day in no HQ to ~ 0.11 mg/cm2 day in HQ). For the WE43 samples in the presence of HQ, formation of MgO and MgQ2 was detected by x-ray photoelectron spectroscopy and x-ray diffraction. Shallower and smaller pits appeared on the magnesium alloy with HQ in the solution as compared to deeper and larger pits on the samples with no HQ in the solution. The significance of metal-complexing organic agent, hydroxyquinoline, in initial acceleration and subsequent prevention of Mg corrosion via protective MgQ2 complex layer formation is demonstrated.
Keywordscorrosion inhibitor magnesium alloy scanning electrochemical microscopy scanning electron microscopy x-ray photoelectron spectroscopy
The authors thank the Materials Research Facility (MRF) for providing access to the microscopy, XRD, and XPS facilities. The authors thank Advanced Materials and Manufacturing Processes Institute (AMMPI) for the access to scanning electrochemical microscopic analysis.
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