Corrosion Inhibition of Disodium Hydrogen Phosphate for AZ91 Mg Alloy

Electrochemical impedance spectroscopy, potentiodynamic polarization curves, weight loss and scanning electron microscopy were used to study the inhibition behavior of disodium hydrogen phosphate for AZ91 Mg alloy in 0.05% NaCl solution. The results indicated that the mono-hydrogen phosphate can inhibit the corrosion of AZ91 Mg alloy effectively, because the deposits of magnesium salt protect the alloy surface from corrosion. When organic sulfonate or carboxylate was used alone, their anions adsorbed on the surface of Mg alloy, and thus protected Mg alloy to a certain extent. When they compounded with mono-hydrogen phosphate, they can improve the inhibition efficiency of mono-hydrogen phosphate, and the maximum inhibition rate can be reached by sulfonate compounded with mono-hydrogen phosphate.