Voltammetric studies of extruded pure magnesium in different electrolytes and its corrosion morphology

Abstract

This study concerns the voltammetric behavior in different electrolytes of pure Mg processed by direct extrusion. The recrystallized microstructure is fine grained and homogeneously distributed. Mg is known to suffer pitting corrosion when exposed to chloride solutions. To cause a high anodic dissolution, corrosion has been evaluated with potentiodynamic polarization in Ringer, HBSS and DMEM up to 500 mV. The anodic current density within the active corrosion region and the current density and potential for passivation were used to compare the corrosion behavior. Corrosion in DMEM showed a tendency to passivation, Mg in HBSS only pseudo-passivated. Corrosion in Ringer showed the highest current density without passivation up to 500 mV. Corrosion morphology is discussed by using the pitting factor and size of corroded area. These values are correlated to the current density-potential curves. With decreased corroded area due to passivation the pitting factor increases. Corrosion behavior is compared to immersion tests.