Investigation on corrosion of yttrium-doped magnesium-based sacrificial anode in ground grid protection

In the simulated DC and AC discharge circuit in ground grid protection of substation, corrosion and potential of magnesium anode with yttrium addition were studied by potential measurement and scanning electron microscopy. The results showed that potential of anode increased with increasing current density in DC simulation, potential increase of anode with 0.1% yttrium addition was the smallest, and the affordable current density of the anode reached 1.85 A/cm2, which was two times that of the anode without yttrium addition. In AC simulation, addition of yttrium had less effect on its potential. Grains of magnesium alloy sacrificial anode without yttrium addition were the equiaxed grains of magnesium grains coated with β-Mg17Al12, while the anode with yttrium was α-Mg phase with dispersed β phase. The corroded magnesium anode with 0.1% yttrium addition showed the most uniform and the smallest pit on its surface.