Here we prepared PEO coatings on Mg alloys in silicate-NaOH-phosphate electrolyte containing different concentrations of NaF addition.The detailed microstructural characterizations combining with potentiodynamic polar...Here we prepared PEO coatings on Mg alloys in silicate-NaOH-phosphate electrolyte containing different concentrations of NaF addition.The detailed microstructural characterizations combining with potentiodynamic polarization and electrochemical impedance spectra(EIS)were employed to investigate the roles of fluoride in the growth and corrosion properties of PEO coating on Mg.The result shows the introduction of NaF led to a fluoride-containing nanolayer(FNL)formed at the Mg/coating interface.The FNL consists of MgO nanoparticles and insoluble MgF_(2)nanoparticles(containing rutile phase and cubic phase).The increase in the NaF concentration of the electrolyte increases the thickness and the MgF_(2)content in the FNL.When anodized in the electrolyte containing 2 g/L NaF,the formed FNL has the highest thickness of 100-200 nm along with the highest value of x of∼0.6 in(MgO)_(1-x)(MgF_(2))x resulted in the highest corrosion performance of PEO coating.In addition,when anodized in the electrolyte containing a low NaF concentration(0.4-0.8 g/L),the formed FNL was thin and discontinuous,which would decrease the pore density and increase the coating's uniformness simultaneously.展开更多
基金Zhu.L.and Li.H.contributed equally to this work.This work is supported by the National Natural Science Foundation of China(Grant No.51901121)the Natural Science Foundation of Shaanxi Province(Grant No.2021JM-203,2019JQ-433,2020zdzx04-03-02)the Fundamental Research Funds for the Central Universities(Grant No.GK202103022).
文摘Here we prepared PEO coatings on Mg alloys in silicate-NaOH-phosphate electrolyte containing different concentrations of NaF addition.The detailed microstructural characterizations combining with potentiodynamic polarization and electrochemical impedance spectra(EIS)were employed to investigate the roles of fluoride in the growth and corrosion properties of PEO coating on Mg.The result shows the introduction of NaF led to a fluoride-containing nanolayer(FNL)formed at the Mg/coating interface.The FNL consists of MgO nanoparticles and insoluble MgF_(2)nanoparticles(containing rutile phase and cubic phase).The increase in the NaF concentration of the electrolyte increases the thickness and the MgF_(2)content in the FNL.When anodized in the electrolyte containing 2 g/L NaF,the formed FNL has the highest thickness of 100-200 nm along with the highest value of x of∼0.6 in(MgO)_(1-x)(MgF_(2))x resulted in the highest corrosion performance of PEO coating.In addition,when anodized in the electrolyte containing a low NaF concentration(0.4-0.8 g/L),the formed FNL was thin and discontinuous,which would decrease the pore density and increase the coating's uniformness simultaneously.
