TY - JOUR
T1 - An Optimized Trivalent Chromium Conversion Coating Process for AA2024-T351 Alloy
AU - Qi, Jiantao
AU - Gao, Lei
AU - Li, Y.
AU - Wang, Zhengjian
AU - Thompson, George
AU - Skeldon, Peter
PY - 2017/6/1
Y1 - 2017/6/1
N2 - In this work, a trivalent chromium conversion coating applied on AA2024-T351 alloy has been optimized for corrosion protection in sodium chloride solutions. Scanning electron microscopy, energy dispersive X-ray spectroscopy and electrochemical measurements were employed to characterize the coating. An immersion post-treatment of the coated alloy in 40 ºC deionized water for 120 s considerably enhanced the corrosion protection properties, compared with a post treatment at 20 °C, or the absence of a post-treatment. Electrochemical noise measurements, combined with real time imaging, and potentiodynamic polarization experiments indicated a conversion treatment for 300 or 600 s provides optimal corrosion protection. Relatively long conversion treatments decreased the corrosion protection due to an increase in coating defects and cracks, especially around the second-phase particles.
AB - In this work, a trivalent chromium conversion coating applied on AA2024-T351 alloy has been optimized for corrosion protection in sodium chloride solutions. Scanning electron microscopy, energy dispersive X-ray spectroscopy and electrochemical measurements were employed to characterize the coating. An immersion post-treatment of the coated alloy in 40 ºC deionized water for 120 s considerably enhanced the corrosion protection properties, compared with a post treatment at 20 °C, or the absence of a post-treatment. Electrochemical noise measurements, combined with real time imaging, and potentiodynamic polarization experiments indicated a conversion treatment for 300 or 600 s provides optimal corrosion protection. Relatively long conversion treatments decreased the corrosion protection due to an increase in coating defects and cracks, especially around the second-phase particles.
KW - Coating process
KW - AA2024 alloy
KW - Corrosion protection
KW - Electrochemical Impedance
KW - Electrochemical noise
U2 - 10.1149/2.1371707jes
DO - 10.1149/2.1371707jes
M3 - Article
SN - 0013-4651
JO - Journal of the Electrochemical Society
JF - Journal of the Electrochemical Society
ER -