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Novel Mg 2 Zr 5 O 12 /Mg 2 Zr 5 O 12 –ZrO 2 –MgF 2 Gradient Layer Coating on Magnesium Formed by Microarc Oxidation
Author(s) -
Han Yong,
Song Jingfeng
Publication year - 2009
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2009.03105.x
Subject(s) - materials science , corrosion , coating , magnesium , nanocrystalline material , scanning electron microscope , transmission electron microscopy , metallurgy , analytical chemistry (journal) , electrolyte , layer (electronics) , composite material , chemistry , nanotechnology , chromatography , electrode
A novel Mg 2 Zr 5 O 12 ‐based coating on magnesium was formed by microarc oxidation (MAO) in a K 2 ZrF 6 ‐containing electrolyte. The structure of the coating was examined by X‐ray diffraction using the grazing angle method, scanning electron microscopy, and transmission electron microscopy. The friction and wear properties of the MAO‐coated and ‐uncoated Mg samples were evaluated in a ball‐on‐disk testing system. The corrosion resistance of the coating in a 3.5% NaCl solution was investigated by the potentiodynamic polarization test. The coating is relatively dense and composed of a Mg 2 Zr 5 O 12 –ZrO 2 –MgF 2 inner layer and a nanocrystalline Mg 2 Zr 5 O 12 outer layer with a maximum hardness of 1240 Hv. The friction coefficient of the coating against Si 3 N 4 is 0.35 under a dry‐sliding condition. The corrosion resistance of the magnesium substrate is improved considerably by MAO treatment. The corrosion potential of the Mg 2 Zr 5 O 12 ‐coated sample is −1.43 V with a current density as low as 7.06 × 10 −8 A/cm 2 . It is expected that the coating can considerably protect magnesium from wear and corrosion.