Premium
Designing for the cerium‐based conversion coating with excellent corrosion resistance on Mg–4Y–2Al magnesium alloy
Author(s) -
Wu Xinchen,
Liu Zili,
Liu Xiqin,
Xie Huanjian,
Liu Fang,
Lu Cheng,
Li Jian
Publication year - 2021
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.202012166
Subject(s) - microstructure , coating , materials science , cerium , corrosion , conversion coating , alloy , scanning electron microscope , x ray photoelectron spectroscopy , magnesium alloy , chemical engineering , magnesium , metallurgy , composite material , engineering
The cerium salt chemical conversion baths containing KMnO 4 are applied to prepare protective coatings on the WA42 alloy surface, and the effect of the concentration of KMnO 4 on the microstructure and corrosion properties of the coatings is investigated by scanning electron microscopy, X‐ray photoelectron spectroscopy, and electrochemical tests. The results indicate that with the addition of KMnO 4 to the conversion bath, the microstructure of the coating is more uniform and denser, and the coating with the KMnO 4 concentration of 4 g/L (4M coating) has the most uniform microstructure with the least microcracks. The 4M coating exhibits a two‐layered structure, and it is mainly composed of MgO, Mg(OH) 2 , CeO 2 , Ce 2 O 3 , Ce(OH) 3 , MnO, and MnO 2 . In addition, as the KMnO 4 concentration increases from 0 to 6 g/L, the I corr of the coatings in 3.5% NaCl solution decreases first and then increases, and the 4M coating shows the best corrosion resistance, which should attribute to the uniform and dense microstructure.