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A Zr‐ and Cr(III)‐containing conversion coating on Al alloy 2024‐T3 and its self‐repairing behavior
Author(s) -
Cai C.,
Liu X.Q.,
Tan X.,
Li G.D.,
Wang H.,
Li J.M.,
Li J.F.
Publication year - 2017
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.201609067
Subject(s) - x ray photoelectron spectroscopy , materials science , conversion coating , corrosion , dielectric spectroscopy , coating , alloy , zirconium , polarization (electrochemistry) , metallurgy , scratch , chemical engineering , electrochemistry , nuclear chemistry , composite material , chemistry , electrode , engineering
A zirconium‐ and Cr(III)‐containing conversion coating on Al alloy 2024‐T3 was prepared in solution containing Cr 2 (SO 4 ) 3 and K 2 ZrF 6 . Its composition was analyzed by energy dispersive X‐ray spectrometry (EDS), and its corrosion resistance was investigated using polarization curve, electrochemical impedance spectroscopy (EIS), and salt spray exposure. An artificial scratch cell was used to investigate its “self‐repairing” effect by EIS and X‐ray photoelectron spectroscopy (XPS). In addition to Al, the conversion coating contained Zr, Cr, O, and F. The conversion coating provided obvious corrosion protection for the Al alloy 2024‐T3. The EIS measurement and corrosion morphology observation of bare samples (i.e., uncoated samples) in the artificial scratch cell confirmed that the conversion coating possessed “self‐repairing” effect. XPS analysis showed that Cr(III) species, but not Zr species were transported from the conversion coating to the nearby bare area as in a scratch.