Effect of coating composition on the corrosion resistance of 316L steel

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F26722445%3A_____%2F24%3AN0000119" target="_blank" >RIV/26722445:_____/24:N0000119 - isvavai.cz</a>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Effect of coating composition on the corrosion resistance of 316L steel

Original language description

The aim of the work was to verify the behaviour of materials under the working conditions of the pump impeller of a small lead-cooled modular reactor. Specimens of 316L stainless steel in as-received state and coated were exposed to liquid lead with 10-8 wt.% oxygen at 520 °C for 3500 h. Three various coatings based on Al, Ti, and W were applied by PVD. The post-test microscopic analyses revealed different mechanisms of degradation of the coatings and confirmed the improved corrosion resistance of the coated steel compared to the uncoated steel. For 316L steel, the corrosion attack occurred on 92 % of the surface, with an average depth of the damage of 8.5 µm. Considering the fact, that this was a low oxygen environment, mainly solution-based attack (SBA) and Pb penetration into the material structure was found. The outer oxidation was negligible as small nodules of the oxide were visible only on 4 % of the surface. The evaluation of the cross-section of the coated specimens showed that SBA and Pb penetration were minimal, and the main damage mechanism was internal oxidation. Minimal corrosion damage occurred on the AlTiN coated specimen. In this case, AlTiN formed a protective barrier against the Pb penetration and there was also minimal oxygen penetration through the coating and negligible oxidation of the base material. Only 6 % of the 316L surface was attacked by internal oxidation with average depth of 0.1 µm. AlTi protective layer was more permeable to oxygen and internal oxidation of the base material occurred on 30 % of the surface with an average depth of 1 µm. The coating structure proved to be less dense and Pb penetration through the coating also occurred. The worst results were achieved with the metallic coating containing W. In this case, even the low oxygen concentration in the corrosive environment was sufficient to oxidize the coating and forming a mixed oxide with Pb. Similarly, to AlTi oxygen penetrated to the coating and the internal oxidation was found on 36 % of the base material surface with an average depth of 1.5 µm. SBA was found on 13 % of the base material surface. Presented at EUROCORR conference 2024, 1. 9. 2024 – 5. 9. 2024, Paris, France.

Czech name

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Czech description

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Type

O - Miscellaneous

CEP classification

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OECD FORD branch

20501 - Materials engineering

Project

<a href="/en/project/TK04030082" target="_blank" >TK04030082: Pretty Fast Flow</a><br>

Continuities

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Publication year

2024

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů