Characterization and Corrosion Behavior of Nano-ceramic Coatings Produced by MAO Method: The Role of Process Time.

Autor: Shahri, Z., Allahkaram, S. R., Soltani, R., Jafari, H.
Předmět:
Zdroj: JOM: The Journal of The Minerals, Metals & Materials Society (TMS); Jan2024, Vol. 76 Issue 1, p222-231, 10p
Abstrakt: The aim of this study is to investigate the surface properties of protective coatings applied for various periods on Mg-5Zn-0.4C (ZX504) magnesium alloy using the micro-arc oxidation (MAO) method and to study their corrosion behavior in a phosphate-buffered-saline solution. The coatings were prepared under a unipolar constant-current regime in a phosphate- containing electrolyte. The effect of coating time on surface characteristics was assessed using a scanning electron microscope, image analyzer, energy-dispersive spectroscope, X-ray diffractometer, and stylus profilometer. Corrosion behavior was also evaluated by electrochemical impedance spectroscopy. The results confirmed that the MAO process time has a great effect on the surface characteristics, and nano-crystalline magnesium oxide (MgO) coatings are obtained. It was also shown that the MgO coating obtained at the higher process time is less protective because of having a higher number of large pores and cracks, causing enhanced diffusion of corrosive ions. Moreover, the increased MAO process time resulted in formation of an intermediate layer in the coating. The results also revealed that the corrosion resistance of the coated sample produced at the low process time of 2 min is > 1000 times better than that of the uncoated alloy. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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