Enhanced corrosion protection for MAO coating on magnesium alloy by the synergism of LDH doping with deposition of 8HQ inhibitor film

The inherent micropores of micro-arc oxidation (MAO) coatings on magnesium alloy often cause poor long-term corrosion resistance. Herein, a low-porosity and high corrosion-resistant 8HQ/LDH/MAO composite coating, comprising a layered double hydroxide (LDH)-doped MAO primer and a top layer of 8-hydro...

Full description

Saved in:
Bibliographic Details
Published inCeramics international Vol. 49; no. 18; pp. 30039 - 30048
Main Authors Liu, Runjia, Xu, Dan, Liu, Yan, Wu, Liang, Yong, Qiwen, Xie, Zhi-Hui
Format Journal Article
LanguageEnglish
Published Elsevier Ltd 15.09.2023
Subjects
Corrosion protection
Layered double hydroxide
Magnesium alloy
Micro-arc oxidation
Corrosion protection
Layered double hydroxide
Micro-arc oxidation
Magnesium alloy
Online AccessGet full text

Cover

More Information
Summary:The inherent micropores of micro-arc oxidation (MAO) coatings on magnesium alloy often cause poor long-term corrosion resistance. Herein, a low-porosity and high corrosion-resistant 8HQ/LDH/MAO composite coating, comprising a layered double hydroxide (LDH)-doped MAO primer and a top layer of 8-hydroxyquinoline (8HQ) inhibitor film, was deposited onto the magnesium alloy surface. Characterizations such as high-resolution field-emission transmission electron microscopy were performed to observe the synthesized nanoparticles’ morphology, size, composition, and structure. Results confirmed the successful synthesis of nitrate ion intercalated MgAl-LDH nanosheets and demonstrated the increase in thickness and denseness of the MAO coating after LDH doping. Based on electrochemical impedance spectroscopy and Tafel curves, the corrosion current density (jcorr) of the newly fabricated 8HQ/LDH/MAO composite coating was reduced by about three orders of magnitude. The low-frequency impedance modulus (|Z|ƒ=0.1 Hz) increased by nearly four orders of magnitude compared with that of bare Mg alloy. After 14 days of exposure to the corrosive electrolyte, the composite coating maintained a low jcorr, showing significantly enhanced corrosion resistance compared with single MAO coating. These findings demonstrated the synergism of LDH doping with 8HQ sealing to enhance the corrosion protection of MAO coating on magnesium alloy.
ISSN:0272-8842
1873-3956
DOI:10.1016/j.ceramint.2023.06.261