The effects of NaF concentration on electrochemical and corrosion behavior of AZ31B magnesium alloy in a composite electrolyte

Abstract

Electrochemical and corrosion behavior of AZ31B magnesium alloy have been investigated using electrochemical methods in a composite solution of MgSO₄–Mg(NO₃)₂ (0.14 mol L⁻¹ MgSO₄, 1.86 mol L⁻¹ Mg(NO₃)₂) under different sodium fluoride (NaF) concentrations. The surface of the AZ31B magnesium alloy is characterized using scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The experimental results indicate that the magnesium electrode achieves a low corrosion rate and high reactivity in the selected composite solution. Furthermore, the effect of NaF on the AZ31B magnesium alloy in the composite electrolyte is investigated in detail and the results demonstrated that the inhibition efficiency increased up to 80% and the delay time was reduced by four times when the NaF concentration reaches 30 mmol L⁻¹. Thus, NaF could efficiently reduce corrosion rate and improve the discharge activity of the magnesium anode as it changes the composition of the surface film. We believe that the composite electrolyte of MgSO₄–Mg(NO₃)₂ with optimized concentration of NaF is a promising candidate for improving the corrosion resistance and reducing the delayed action of AZ31B alloy in aqueous solution.