Corrosion of NiCoCrAIY Coatings and TBC Systems Subjected to Water Vapor and Sodium Sulfate
2015 (English)In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 24, no 6, 953-964 p.Article in journal (Refereed) Published
Thermal barrier coating (TBC) systems are commonly used in gas turbines for protection against high-temperature degradation. Penetration of the ceramic top coat by corrosive species may cause corrosion damage on the underlying NiCoCrAlY bond coat and cause failure of the TBC system. In the current study, four oxidation/corrosion conditions were tried: (i) lab air, (ii) water vapor, (iii) sodium sulfate deposited on the specimens, and (iv) water vapor + sodium sulfate. The test was done at 750 °C in a cyclic test rig with 48 h cycles. The corrosion damage was studied on NiCoCrAlY-coated specimens, thin APS TBC specimens, and thick APS TBC specimens. Water vapor was found to have very minor influence on the oxidation, while sodium sulfate increased the TGO thickness both for NiCoCrAlY specimens and TBC-coated specimens; the influence of the TBC thickness was found to be very small. Sodium sulfate promoted thicker TGO; more Cr-rich TGO; the formation of Y oxides, and internally, Y sulfides; pore formation in the coating as well as in the substrate; and the formation of a Cr-depleted zone in the substrate.
Place, publisher, year, edition, pages
Springer, 2015. Vol. 24, no 6, 953-964 p.
corrosion, cyclic furnace, sodium sulfate, thermal barrier coating, water vapor
IdentifiersURN: urn:nbn:se:liu:diva-119690DOI: 10.1007/s11666-015-0253-zISI: 000358965400007OAI: oai:DiVA.org:liu-119690DiVA: diva2:825917