skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Tracer Film Growth Study of the Corrosion of Magnesium Alloys AZ31B and ZE10A in 0.01% NaCl Solution

Abstract

We conducted a sequential isotopic tracer study of corrosion film growth for Mg-3Al-1Zn-0.25Mn (AZ31B) and Mg-1.2Zn-0.25Zr-<0.5Nd (ZE10A) by 4 h immersion in H 2 18O or D 2 16O, followed by a 20 h immersion in a 0.01 wt% NaCl H 2 18O or D 2 16O solution. Sputter depth profiles were obtained for 16O, 18O, H, and D using secondary ion mass spectrometry (SIMS). When compared to the previous tracer study for these alloys in salt-free water, the addition of 0.01 wt% NaCl resulted in a transition from oxygen inward-dominated film growth to a component of mixed inward/outward film growth for both alloys. The hydrogen tracer behavior remained inward growing for AZ31B, and short-circuit, inward growing for ZE10A, in both pure water and in 0.01 wt% NaCl solution, with extensive penetration of D beyond the film and into the underlying alloy also observed for ZE10A. Our analysis of the films by X-ray photoelectron spectroscopy (XPS) and cross-section scanning transmission electron microscopy (STEM) indicated intermixed Mg(OH) 2 and MgO, with the relative fraction of Mg(OH) 2 peaking near the center of the film. These findings suggest a decoupled film growth mechanism, with initial formation of oxide followed by NaCl-accelerated conversionmore » to hydroxide, likely by both solid-state and dissolution-precipitation processes.« less

Authors:
 [1];  [2];  [1];  [1];  [1];  [1];  [1]; ORCiD logo [1];  [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of Manitoba, Winnipeg, MB (Canada)
  3. Magnesium Elektron North America, Madison, IL (United States)
Publication Date:
Research Org.:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1360066
Grant/Contract Number:
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the Electrochemical Society
Additional Journal Information:
Journal Volume: 164; Journal Issue: 7; Journal ID: ISSN 0013-4651
Publisher:
The Electrochemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Brady, M. P., Fayek, M., Leonard, D. N., Meyer, H. M., Thomson, J. K., Anovitz, L. M., Rother, G., Song, G. -L., and Davis, B. Tracer Film Growth Study of the Corrosion of Magnesium Alloys AZ31B and ZE10A in 0.01% NaCl Solution. United States: N. p., 2017. Web. doi:10.1149/2.1211707jes.
Brady, M. P., Fayek, M., Leonard, D. N., Meyer, H. M., Thomson, J. K., Anovitz, L. M., Rother, G., Song, G. -L., & Davis, B. Tracer Film Growth Study of the Corrosion of Magnesium Alloys AZ31B and ZE10A in 0.01% NaCl Solution. United States. doi:10.1149/2.1211707jes.
Brady, M. P., Fayek, M., Leonard, D. N., Meyer, H. M., Thomson, J. K., Anovitz, L. M., Rother, G., Song, G. -L., and Davis, B. Thu . "Tracer Film Growth Study of the Corrosion of Magnesium Alloys AZ31B and ZE10A in 0.01% NaCl Solution". United States. doi:10.1149/2.1211707jes. https://www.osti.gov/servlets/purl/1360066.
@article{osti_1360066,
title = {Tracer Film Growth Study of the Corrosion of Magnesium Alloys AZ31B and ZE10A in 0.01% NaCl Solution},
author = {Brady, M. P. and Fayek, M. and Leonard, D. N. and Meyer, H. M. and Thomson, J. K. and Anovitz, L. M. and Rother, G. and Song, G. -L. and Davis, B.},
abstractNote = {We conducted a sequential isotopic tracer study of corrosion film growth for Mg-3Al-1Zn-0.25Mn (AZ31B) and Mg-1.2Zn-0.25Zr-<0.5Nd (ZE10A) by 4 h immersion in H218O or D216O, followed by a 20 h immersion in a 0.01 wt% NaCl H218O or D216O solution. Sputter depth profiles were obtained for 16O, 18O, H, and D using secondary ion mass spectrometry (SIMS). When compared to the previous tracer study for these alloys in salt-free water, the addition of 0.01 wt% NaCl resulted in a transition from oxygen inward-dominated film growth to a component of mixed inward/outward film growth for both alloys. The hydrogen tracer behavior remained inward growing for AZ31B, and short-circuit, inward growing for ZE10A, in both pure water and in 0.01 wt% NaCl solution, with extensive penetration of D beyond the film and into the underlying alloy also observed for ZE10A. Our analysis of the films by X-ray photoelectron spectroscopy (XPS) and cross-section scanning transmission electron microscopy (STEM) indicated intermixed Mg(OH)2 and MgO, with the relative fraction of Mg(OH)2 peaking near the center of the film. These findings suggest a decoupled film growth mechanism, with initial formation of oxide followed by NaCl-accelerated conversion to hydroxide, likely by both solid-state and dissolution-precipitation processes.},
doi = {10.1149/2.1211707jes},
journal = {Journal of the Electrochemical Society},
number = 7,
volume = 164,
place = {United States},
year = {Thu May 25 00:00:00 EDT 2017},
month = {Thu May 25 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Save / Share:
  • The local metal-coating interface microstructure and chemistry formed on commercial magnesium alloys Mg–3Al–1Zn (AZ31B) and Mg–1Zn–0.25Zr–<0.5Nd (ZE10A, ZEK100 type) were analyzed as-chemical conversion coated with a commercial hexafluoro-titanate/zirconate type + organic polymer based treatment (Bonderite® 5200) and a commercial hexafluoro-zirconate type + trivalent chromium Cr3 + type treatment (Surtec® 650), and after the same conversion coatings followed by electrocoating with an epoxy based coating, Cathoguard® 525. Characterization techniques included scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and cross-section scanning transmission electron microscopy (STEM). Corrosion behavior was assessed in room temperature saturated aqueous Mg(OH)2 solution with 1 wt.% NaCl. Themore » goal of the effort was to assess the degree to which substrate alloy additions become enriched in the conversion coating, and how the conversion coating was impacted by subsequent electrocoating. Key findings included the enrichment of Al from AZ31B and Zr from ZE10A, respectively, into the conversion coating, with moderate corrosion resistance benefits for AZ31B when Al was incorporated. Varying degrees of increased porosity and modification of the initial conversion coating chemistry at the metal-coating interface were observed after electrocoating. These changes were postulated to result in degraded electrocoating protectiveness. As a result, these observations highlight the challenges of coating Mg, and the need to tailor electrocoating in light of potential degradation of the initial as-conversion coated Mg alloy surface.« less
  • The microstructure and corrosion behavior of high pressure die-cast (HPDC) and super vacuum die-cast (SVDC) AM60B magnesium alloys were investigated in a complex salt solution using slow positron beam technique and potentiodynamic polarization tests. The experiments revealed that a CaCO 3 film was formed on the surface of the alloys and that the rate of CaCO 3 formation for the SVDC alloy with immersion time was slower than that of the HPDC alloy. The larger volume fraction of b-phase in the skin layer of the SVDC alloy than that of the HPDC alloy was responsible for the better corrosion resistance.
  • In this study, Ti-Al-N/Ti-Al duplex coating was deposited on AZ31 magnesium alloy by magnetron sputtering with a Ti/Al composite target. Scanning electron microscopy and Auger electron spectroscopy were applied to investigate the morphology and elemental concentration of the obtained coating, respectively. The top layer was Ti-Al-N film with a Ti:Al:O:N ratio of 0.32:0.84:0.08:1, and the bottom layer was Ti-Al film with a Ti:O:Al ratio of 1.94:0.12:1. Each layer of this coating presented a developed columnar structure. The polarization test and immersion test were used to investigate corrosion behavior of the coated sample in 3.5 wt.% NaCl aqueous solution. The resultsmore » showed that this duplex coating could protect the substrate effectively in NaCl aqueous solution. Nevertheless, several through-thickness micropores in the coating finally induced the failure of the coated AZ31 in the immersion test.« less