High Potential Magnesium Anode Preparation And Performance

The high-potential magnesium sacrificial anode has a larger driving voltage differential potential to the steel structure, which are widely used in high-resistivity soils or the freshwater environments. It has a bigger share than the low-potential magnesium anode in the market and it has becomes the main product of the magnesium anodes. Commercially pure magnesium was the fist used high-potential magnesium anode with the current efficiency of about 30%, while the currently used Mg-Mn sacrificial anode is the only kind of the high-potential magnesium sacrificial anode with a higher current efficiency of about 50%. The low efficiency of the Mg-Mn sacrificial anode shorten the working time, increasing operating costs, which largely limits its use in the cathodic protection project.In this dissertation, the rules how the pure magnesium anode and the Mg-Mn anode were studied and the two main reasons that effected the efficiency of the anode were found out: self-corrosion and mechanical loss. And the work was done on the two aspects as follows: 1) the melt of Mg-Mn anode was refined by the fluxes mixed with TiO₂ powder to reduce the Fe content and the Si content, which decreases the self-corrosion. 2) To add some content of Sr into the Mg-Mn anode and the pure magnesium anode respectively blocking the intergranular corrosion which decrease the particles spalling. Their electrochemical performances are tested with constant current method and microstructures are also observed and analyzed by metallography microscope, scanning electron microscope and energy spectrum analysis.The results of purified process on the melt of Mg-Mn anode by using TiO₂ powder were showed as follows: TiO₂ powder can reduce the Fe content and Si content, when the melt of Mg-Mn anode was refined by the fluxes with 25%(Wt%), the Fe content and Si content can decreased from 0.015% and 0.026% to 0.004% and 0.004% respectively of the melt. After purified process, the efficiency and the open potential of the anode reached 51.2% and -1.71V_SCE respectively. Using more TiO₂ powder cannot continue to decrease the Fe content and Si content, while the Fe...