Electrochemical behaviour of titanium in H2SO4-MnSO4 electrolytes |
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Authors: | WB Utomo |
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Affiliation: | Discipline of Chemistry, University of Newcastle, Callaghan, NSW 2308, Australia |
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Abstract: | The corrosion of titanium in H2SO4 electrolytes (0.001-1.0 M) at temperatures from ambient to 98 °C has been investigated using steady-state polarization measurements. Four distinct regions of behaviour were identified, namely active corrosion, the active-passive transition, passive region and the dielectric breakdown region. The active corrosion and active-passive transition were characterized by anodic peak current (im) and voltage (Em), which in turn were found to vary with the experimental conditions, i.e., d(log?(im))/dpH=−0.8±0.1 and dEm/dpH which was −71 mV at 98 °C, −58 mV at 80 °C and −28 mV at 60 °C. The activation energy for titanium corrosion, determined from temperature studies, was found to be 67.7 kJ mol−1 in 0.1 M H2SO4 and 56.7 kJ mol−1 in 1.0 M H2SO4. The dielectric breakdown voltage (Ed) of the passive TiO2 film was found to vary depending on how much TiO2 was present. The inclusion of Mn2+ into the H2SO4 electrolyte, as is done during the commercial electrodeposition of manganese dioxide, resulted in a decrease in titanium corrosion current, possibly due to Mn2+ adsorption limiting electrolyte access to the substrate. |
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Keywords: | Titanium Active corrosion Passivation Electrolytic manganese dioxide |
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