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This study examined the influence of laboratory corrosion testing methods, specifically salt spray, and immersion tests, on the long-term performance assessment of wire-arc-sprayed Zn-Al coatings. Two Zn-Al alloyed systems, Zn-15Al and Zn-Al pseudo-alloy, were selected for investigation, subjecting them to 1000 h of immersion and salt spray conditions. Electrochemical impedance spectroscopy was used to monitor corrosion progression in both coating systems at 200-h intervals. Post-exposure, the coatings underwent microstructural and chemical characterization, along with potentiodynamic polarization tests. Furthermore, some specimens in both coating systems were intentionally damaged and exposed to 1000 h of salt spray and immersion testing and analyzed with scanning electron microscopy. Immersion testing yielded similar results for both coatings, while salt spray testing unveiled significant differences and highlighted the susceptibility of the Zn-15Al to salt spray in both undamaged and damaged states. The continuously refreshed salt spray electrolyte hindered stable corrosion product formation, allowing chloride penetration and increased corrosion in Zn-15Al. Conversely, the Zn-Al pseudo-alloy coating formed Al (OH)3, acting as a barrier against chloride penetration during salt spray and offering superior protection. In summary, salt spray testing proved more aggressive than immersion when evaluating Zn-Al coatings with high zinc content primarily relying on active dissolution for corrosion protection.
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Post-Fire Analysis of Thermally Sprayed Coatings: Evaluating Microstructure, Mechanical Integrity, and Corrosion Behavior
This paper examines the impact of fire on the microstructural, mechanical, and corrosion behavior of wire-arc-sprayed zinc, aluminum, and Zn-Al pseudo-alloy coatings. Steel plates coated with these materials were subjected to temperatures in increments of 100 °C, starting from 300 °C and progressing until failure. Microstructural characterization, microhardness, abrasion resistance, and electrochemical impedance studies were performed on the post-fire coatings. The findings from this study show that heat had a positive impact on the performance of zinc and Zn-Al pseudo-alloy coatings when they were exposed to temperatures of up to 400 °C, while aluminum coatings maintain their performance up to 600 °C. However, above these temperatures, the effectiveness of coatings was observed to decline, due to increased high-temperature oxidation, and porosity, in addition to decreased microhardness, abrasion resistance, and corrosion protection performance. Based on the findings from this study, appropriately sealed thermal-spray-coated steel components can be reused after exposure to fire up to a specific temperature depending on the coating material.
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- PAR ID:
- 10422257
- Date Published:
- Journal Name:
- Processes
- Volume:
- 11
- Issue:
- 5
- ISSN:
- 2227-9717
- Page Range / eLocation ID:
- 1490
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/pr11051490
