Inhibition effect of inorganic and organic inhibitors on the corrosion of Mg-10Gd-3Y-0.5Zr alloy in an ethylene glycol solution at ambient and elevated temperatures

Highlights: → Sodium phosphate can inhibit the dissolution of GW103 Mg alloy in ethylene glycol. → Sodium dodecylbenzenesulfonate can also inhibit the corrosion of GW103. → These two inhibitors have different inhibition mechanisms on GW103. → The two inhibitors have a synergistic inhibition effect on GW103 if used together. - Abstract: In this study, the corrosion performance of magnesium-based rare-earth containing alloy Mg-10Gd-3Y-0.5Zr (GW103) was evaluated in an ethylene glycol solution with a group of selected aliphatic, aromatic carboxylates and inorganic salts as inhibitors. The dependence of inhibition efficiency on the concentration ratio of sodium phosphate to sodium dodecylbenzenesulfonate (SDBS) and the total inhibitor concentration was measured by means of electrochemical techniques. It was found that the corrosion rate of GW103 decreased by addition of inorganic-organic inhibitors at both ambient and elevated temperatures. The inhibitors were more effective at the ambient temperature than at the elevated temperature. The corrosion of GW103 in the ethylene glycol solution can be effectively inhibited by 1000 ppm of the inorganic-organic inhibitor mixture. It is believed that the added phosphate can interact with SDBS, resulting in a more compact surface film on the GW103 surface. Based on these results, as well as Environmental Scanning Electron Microscope (ESEM) observations, a synergistic mechanism was proposed to explain the inhibition behavior of the sodium phosphate + SDBS combination.