Effect of the Sodium Silicate Inhibitor on the Corrosion Protection of AZ31 Magnesium Alloy

The effect of the sodium silicate inhibitor on the corrosion protection of the AZ31 magnesium alloy at room temperature was investigated. The results of electrochemical measurement and weight loss experiments showed that incorporating the sodium silicate significantly enhanced the anti-corrosion property of the AZ31 alloy. When the alloy was immersed in the corrosive solution with the 0.1 M sodium silicate, the corrosion rate of the AZ31 alloy declined to 0.014 mm·y^-1, and the inhibition efficiency reached 99.1%. The observation of the corrosion morphology indicated that the magnesium silicate precipitated to cover the corroded area with a thickness of 105 μm, while the silicate ion adsorbed on the uncorroded area. The calculation results of the adsorption energy based on the molecular dynamics indicated that the physical adsorption occurred when the samples were immersed in a sodium silicate solution. Combined with the schematic diagram, the protective mechanism of the adsorption and precipitation after the addition of the sodium silicate inhibitor was investigated.