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Title: Magnesium Alloy Effects on Plasma Electrolytic Oxidation Electro-Ceramic and Electro-Coat Formation and Corrosion Resistance

Abstract

Plasma electrolytic oxidation (PEO) electro-ceramic (EC) coatings with and without an epoxy-base electro-coat (E-coat) overlayer were studied on four magnesium alloys using the same process deposition parameters: Mg-3Al-1Zn (AZ31B), Mg-9Al-0.5Zn (AZ91D), Mg-1.5Zn-0.3Zr-<0.5Nd (ZE10A, ZEK100 type), and Mg-4Y-(<2.5 Nd)-0.4Zr (WE43). A similar magnesium-fluoride (Mg-F) base EC chemistry formed on all four alloys. However, the morphology of the EC was significantly impacted by the substrate alloys, with higher alloy Al or Zr/rare earth (RE) levels also resulting in thicker coatings. A duplex EC structure formed on AZ31B, AZ91D, and ZE10, with a submicron inner layer and a thicker outer porous layer; whereas a striated multi-layer inner region and thick porous outer region formed on WE43. The EC coated alloys exhibited similar corrosion resistance to the bare alloys due to coating porosity, with the best corrosion resistance exhibited by AZ91D and WE43. After applying the E-coat overlayer, similar, excellent corrosion resistance was exhibited for all four EC + E-coated alloys. Scribing of the EC + E-coat to controllably introduce a coating defect degraded corrosion resistance, particularly for WE43, which suffered from E-coat blistering due to susceptibility of the inner striated EC layer to delamination.

Authors:
ORCiD logo [1]; ORCiD logo [1];  [2]; ORCiD logo [2]; ORCiD logo [1]; ORCiD logo [1];  [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. McMaster Univ., Hamilton, ON (Canada)
  3. Luxfer Graphic Arts, Madison, IL (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1607067
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 166; Journal Issue: 14; Journal ID: ISSN 0013-4651
Publisher:
IOP Publishing - The Electrochemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Brady, Michael P., Leonard, Donovan N., McNally, Elizabeth A., Kish, Joseph R., Meyer, III, Harry M., Cakmak, Ercan, and Davis, Bruce. Magnesium Alloy Effects on Plasma Electrolytic Oxidation Electro-Ceramic and Electro-Coat Formation and Corrosion Resistance. United States: N. p., 2019. Web. doi:10.1149/2.0531914jes.
Brady, Michael P., Leonard, Donovan N., McNally, Elizabeth A., Kish, Joseph R., Meyer, III, Harry M., Cakmak, Ercan, & Davis, Bruce. Magnesium Alloy Effects on Plasma Electrolytic Oxidation Electro-Ceramic and Electro-Coat Formation and Corrosion Resistance. United States. https://doi.org/10.1149/2.0531914jes
Brady, Michael P., Leonard, Donovan N., McNally, Elizabeth A., Kish, Joseph R., Meyer, III, Harry M., Cakmak, Ercan, and Davis, Bruce. Tue . "Magnesium Alloy Effects on Plasma Electrolytic Oxidation Electro-Ceramic and Electro-Coat Formation and Corrosion Resistance". United States. https://doi.org/10.1149/2.0531914jes. https://www.osti.gov/servlets/purl/1607067.
@article{osti_1607067,
title = {Magnesium Alloy Effects on Plasma Electrolytic Oxidation Electro-Ceramic and Electro-Coat Formation and Corrosion Resistance},
author = {Brady, Michael P. and Leonard, Donovan N. and McNally, Elizabeth A. and Kish, Joseph R. and Meyer, III, Harry M. and Cakmak, Ercan and Davis, Bruce},
abstractNote = {Plasma electrolytic oxidation (PEO) electro-ceramic (EC) coatings with and without an epoxy-base electro-coat (E-coat) overlayer were studied on four magnesium alloys using the same process deposition parameters: Mg-3Al-1Zn (AZ31B), Mg-9Al-0.5Zn (AZ91D), Mg-1.5Zn-0.3Zr-<0.5Nd (ZE10A, ZEK100 type), and Mg-4Y-(<2.5 Nd)-0.4Zr (WE43). A similar magnesium-fluoride (Mg-F) base EC chemistry formed on all four alloys. However, the morphology of the EC was significantly impacted by the substrate alloys, with higher alloy Al or Zr/rare earth (RE) levels also resulting in thicker coatings. A duplex EC structure formed on AZ31B, AZ91D, and ZE10, with a submicron inner layer and a thicker outer porous layer; whereas a striated multi-layer inner region and thick porous outer region formed on WE43. The EC coated alloys exhibited similar corrosion resistance to the bare alloys due to coating porosity, with the best corrosion resistance exhibited by AZ91D and WE43. After applying the E-coat overlayer, similar, excellent corrosion resistance was exhibited for all four EC + E-coated alloys. Scribing of the EC + E-coat to controllably introduce a coating defect degraded corrosion resistance, particularly for WE43, which suffered from E-coat blistering due to susceptibility of the inner striated EC layer to delamination.},
doi = {10.1149/2.0531914jes},
journal = {Journal of the Electrochemical Society},
number = 14,
volume = 166,
place = {United States},
year = {Tue Oct 01 00:00:00 EDT 2019},
month = {Tue Oct 01 00:00:00 EDT 2019}
}

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