DOI: 10.5006/1.3284829. A Correlation Between Salt Spray and Electrochemical Impedance Spectroscopy Test Results for Conversion-Coated Aluminum Alloys

A Correlation Between Salt Spray and Electrochemical Impedance Spectroscopy Test Results for Conversion-Coated Aluminum Alloys

10.5006/1.3284829

Crossref journal-article

Association for Materials Protection and Performance (AMPP)

Corrosion (2917)

Abstract

The corrosion resistance of 33 inorganic conversion coatings applied to five aluminum alloys was tested by salt spray exposure and electrochemical impedance spectroscopy (EIS). Results were evaluated to determine if a relationship existed. Individual salt spray test panels, with an area of 30 in.2 (194 cm2), were inspected visually at regular intervals up to 168 h of exposure. At each inspection interval, panels were assigned a pass rank if &lt; 5 pits were observed, or a fail rank if &gt; 5 pits were observed. EIS data were analyzed using a simple equivalent circuit which yielded a coating resistance (Rc) which was used as a figure of merit to assess coating performance. Examination of the data showed both tests could be sensitive discriminators of corrosion protection, but that EIS was more discriminating in the extremes of coating performance. Analysis showed the probability of achieving a passing salt spray result increased as Rc increased. In the regimes where both tests were sensitive, regression analysis showed a linear relationship existed for each alloy substrate between the log of Rc and the probability of a coating meeting the pass/fail criterion in salt spray. Based upon these relationships, threshold Rc values were proposed to define the minimum value for which a given coating can be expected to attain a passing result in a 168-h salt spray test. These values were 2 x 106 Ω-cm2 to 5 x 106 Ω-cm2 for Al 356 (UNS A13560), Al 2024-T3 (UNS A92024), and Al 6061-T6 (UNS A96061); 1.5 x 107 Ω-cm2 for Al 7075-T6 (UNS A97075); and 2.3 x 106 Ω-cm2 for Al 3003 (UNS A93003).

Bibliography

Buchheit, R. G., Cunningham, M., Jensen, H., Kendig, M. W., & Martinez, M. A. (1998). A Correlation Between Salt Spray and Electrochemical Impedance Spectroscopy Test Results for Conversion-Coated Aluminum Alloys. Corrosion, 54(1), 61â72.

Authors 5

R.G. Buchheit (first)
M. Cunningham (additional)
H. Jensen (additional)
M.W. Kendig (additional)
M.A. Martinez (additional)

References 18 Referenced 60

{'key': '2025070817052564700_b1-1_3284829', 'first-page': '36', 'volume': '72', 'author': 'Altmayer', 'year': '1985', 'journal-title': 'Plat. Surf. Fin.'} / Plat. Surf. Fin. by Altmayer (1985)
{'key': '2025070817052564700_b2-1_3284829', 'first-page': '57', 'volume': '62', 'author': 'Appleman', 'year': '1990', 'journal-title': 'J. Coat. Technol.'} / J. Coat. Technol. by Appleman (1990)
10.5006/1.3585209 / Corrosion by Mansfeld (1991)
10.5006/1.3585095 / Corrosion by Titz (1990)
10.5006/1.3585282 / Corrosion by Murray (990)
10.1149/1.2086442 / J. Electrochem. Soc. by Mansfeld (1990)
10.1149/1.2095910 / J. Electrochem. Soc. by Mansfeld (1988)
{'article-title': 'Alternatives to Chromium for Metal Finishing', 'volume-title': 'Final Report 0273RE95', 'year': '1995', 'key': '2025070817052564700_b8-1_3284829'} / Final Report 0273RE95 / Alternatives to Chromium for Metal Finishing (1995)
{'volume-title': 'Chemical Conversion Coatings on Aluminum and Aluminum Alloys', 'year': '1990', 'author': 'Military Specification MIL-C-5541E', 'key': '2025070817052564700_b9-1_3284829'} / Chemical Conversion Coatings on Aluminum and Aluminum Alloys by Military Specification MIL-C-5541E (1990)
10.1016/0013-4686(89)87145-2 / Electrochim. Acta by Mansfeld (1989)
{'key': '2025070817052564700_b11-1_3284829', 'first-page': '27', 'volume-title': 'Process Analysis by Statistical Methods', 'author': 'Himmelblau', 'year': '1970'} / Process Analysis by Statistical Methods by Himmelblau (1970)
10.1002/9780470316795 / Accelerated Testing Statistical Models, Test Plans, and Data Analyses by Nelson (1990)
10.5006/0010-9312-33.7.243 / Corrosion by Shibata (1977)
{'key': '2025070817052564700_b14-1_3284829', 'first-page': '390', 'volume-title': 'Metallic Corrosion', 'author': 'Williams', 'year': '1984'} / Metallic Corrosion by Williams (1984)
{'key': '2025070817052564700_b15-1_3284829', 'first-page': '517', 'volume-title': 'Applied Statistics and Probability for Engineers', 'author': 'Montgomery', 'year': '1994'} / Applied Statistics and Probability for Engineers by Montgomery (1994)
{'key': '2025070817052564700_b16-1_3284829', 'first-page': '242', 'volume-title': 'Aluminum: Properties and Physical Metallurgy Metals', 'author': 'Hatch', 'year': '1984'} / Aluminum: Properties and Physical Metallurgy Metals by Hatch (1984)
{'key': '2025070817052564700_b17-1_3284829', 'first-page': '501', 'volume-title': 'Applied Statistics and Probability for Engineers', 'author': 'Montgomery', 'year': '1994'} / Applied Statistics and Probability for Engineers by Montgomery (1994)
{'key': '2025070817052564700_b18-1_3284829', 'article-title': 'Replacement for Chromate Conversion Coating and Anodization', 'author': 'Kendig', 'year': '1993', 'journal-title': 'Final Report to Rockwell International Space Systems Division and the South Coast Air Quality Management District'} / Final Report to Rockwell International Space Systems Division and the South Coast Air Quality Management District / Replacement for Chromate Conversion Coating and Anodization by Kendig (1993)

Dates

Type	When
Created	15 years, 6 months ago (Feb. 22, 2010, 9:49 a.m.)
Deposited	1 month, 1 week ago (July 9, 2025, 3 a.m.)
Indexed	1 month, 1 week ago (July 9, 2025, 3:40 a.m.)
Issued	27 years, 7 months ago (Jan. 1, 1998)
Published	27 years, 7 months ago (Jan. 1, 1998)
Published Print	27 years, 7 months ago (Jan. 1, 1998)

Funders 0

None

BibTeX

@article{Buchheit_1998, title={A Correlation Between Salt Spray and Electrochemical Impedance Spectroscopy Test Results for Conversion-Coated Aluminum Alloys}, volume={54}, ISSN={1938-159X}, url={http://dx.doi.org/10.5006/1.3284829}, DOI={10.5006/1.3284829}, number={1}, journal={Corrosion}, publisher={Association for Materials Protection and Performance (AMPP)}, author={Buchheit, R.G. and Cunningham, M. and Jensen, H. and Kendig, M.W. and Martinez, M.A.}, year={1998}, month=jan, pages={61–72} }

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