Inhibition mechanism of NaF on WE43 Mg alloy in NaCl solution
(1. State Key Laboratory of Digital Steel, Northeastern University, Shenyang 110819, China;
2. Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou 510632, China
3. Shaoguan Research Institute of Jinan University, Shaoguan 512027, China)
2. Institute of Advanced Wear & Corrosion Resistant and Functional Materials, Jinan University, Guangzhou 510632, China
3. Shaoguan Research Institute of Jinan University, Shaoguan 512027, China)
Abstract: The influence of NaF on the microstructure, composition and corrosion performance of WE43 Mg alloy in 3.5 wt.% NaCl solution was systematically investigated by means of SEM, TEM, EPMA, XRD, XPS and electrochemical measurements. It was proved that NaF is an effective inhibitor for WE43 Mg alloy and the highest inhibition efficiency is 92.6% at its concentration of 40 mmol/L in neutral NaCl solution. The dissolution of WE43 alloy is inhibited by formation and deposition of a dense and protective double-layered corrosion film by chemical reaction between corrosion inhibitor and dissolved Mg2+. The microstructure and composition of this double-layered corrosion film were investigated by FIB and TEM. The outer layer of the corrosion film is found to be composed of NaMgF3, MgF2 and MgO, while the inner layer mainly consists of MgO and MgF2.
Key words: Mg alloy; corrosion; corrosion film; inhibitor; inhibition mechanism