Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion Exposure

Anticorrosive organic coatings are usually tested with accelerated weathering methods to assess their anticorrosive performance. The results of lab testing often do not correlate well with results from field testing, which resembles the conditions of actual use more closely. We tested the correlatio...

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Main Author: Matthias J. Schmid
Format: Article
Language:English
Published: MDPI AG 2024-10-01
Series:Corrosion and Materials Degradation
Subjects:
Online Access:https://www.mdpi.com/2624-5558/5/4/23
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author Matthias J. Schmid
author_facet Matthias J. Schmid
author_sort Matthias J. Schmid
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description Anticorrosive organic coatings are usually tested with accelerated weathering methods to assess their anticorrosive performance. The results of lab testing often do not correlate well with results from field testing, which resembles the conditions of actual use more closely. We tested the correlation of the neutral salt spray test (NSS, ISO 9227) and tests for mechanical properties and a 5-year field exposure in four different locations in the atmospheric zone, splash zone and immersion zone using 19 organic coatings for hydraulic steelwork. No correlation was found between the anticorrosive performance under outdoor exposure and the mechanical properties of a coating. The NSS test showed a positive correlation with the results in the field in 6 of 12 cases. For the fresh water testing location in Trier, the correlation proved to be very good. The biggest difference between lab and field testing was observed for zinc-primer-free coatings, which passed in the lab testing and failed in the outdoor testing. This study shows that the NSS test correlates with outdoor exposure only in some cases on a statistically significant level, but the results of NSS testing can be useful in approval testing for protective coating systems using predefined pass/fail criteria.
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spelling doaj-art-b7f170ad9b094cc7aa0c8f875e66b57d2025-08-20T02:00:37ZengMDPI AGCorrosion and Materials Degradation2624-55582024-10-015449051210.3390/cmd5040023Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion ExposureMatthias J. Schmid0Federal Waterways Engineering and Research Institute, Kußmaulstr. 17, 76187 Karlsruhe, GermanyAnticorrosive organic coatings are usually tested with accelerated weathering methods to assess their anticorrosive performance. The results of lab testing often do not correlate well with results from field testing, which resembles the conditions of actual use more closely. We tested the correlation of the neutral salt spray test (NSS, ISO 9227) and tests for mechanical properties and a 5-year field exposure in four different locations in the atmospheric zone, splash zone and immersion zone using 19 organic coatings for hydraulic steelwork. No correlation was found between the anticorrosive performance under outdoor exposure and the mechanical properties of a coating. The NSS test showed a positive correlation with the results in the field in 6 of 12 cases. For the fresh water testing location in Trier, the correlation proved to be very good. The biggest difference between lab and field testing was observed for zinc-primer-free coatings, which passed in the lab testing and failed in the outdoor testing. This study shows that the NSS test correlates with outdoor exposure only in some cases on a statistically significant level, but the results of NSS testing can be useful in approval testing for protective coating systems using predefined pass/fail criteria.https://www.mdpi.com/2624-5558/5/4/23organic coatingfield testingneutral salt spray testISO 9227hydraulic steelworksNSS
spellingShingle Matthias J. Schmid
Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion Exposure
Corrosion and Materials Degradation
organic coating
field testing
neutral salt spray test
ISO 9227
hydraulic steelworks
NSS
title Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion Exposure
title_full Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion Exposure
title_fullStr Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion Exposure
title_full_unstemmed Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion Exposure
title_short Correlation Between the Anticorrosive Performance of Protective Coatings Under Neutral Salt Spray Testing and Outdoor Atmospheric and Immersion Exposure
title_sort correlation between the anticorrosive performance of protective coatings under neutral salt spray testing and outdoor atmospheric and immersion exposure
topic organic coating
field testing
neutral salt spray test
ISO 9227
hydraulic steelworks
NSS
url https://www.mdpi.com/2624-5558/5/4/23
work_keys_str_mv AT matthiasjschmid correlationbetweentheanticorrosiveperformanceofprotectivecoatingsunderneutralsaltspraytestingandoutdooratmosphericandimmersionexposure