K, S.Babu, N.Cadambi, S.Arya, S.B.2026-02-042024Ceramics International, 2024, 50, 2, pp. 2808-28182728842https://doi.org/10.1016/j.ceramint.2023.11.001https://idr.nitk.ac.in/handle/123456789/21332Mullite's inherent qualities have made it a potential material for the application of thermal barrier coatings (TBCs) for diesel engine components. Hot corrosion at 600–800 °C can cause TBC degradation, thus significantly affecting the performance of engine components and reducing their service life. This work examines the hot corrosion behaviour of atmospheric plasma-sprayed (APS) mullite coating over NiCrAlY bond coat on mild steel substrates. The coated specimen surface was covered with a mixture of Na<inf>2</inf>SO<inf>4</inf> (sodium sulphate) and V<inf>2</inf>O<inf>5</inf> (vanadium pentoxide) in the form of paste and heated in a muffle furnace at 700 °C for up to 300 h. SEM, EDS, and XRD characterisations were used to investigate the mechanism of hot corrosion. Coatings remained intact after corrosion tests; however, it had reacted with corrosive salts, particularly sodium sulphate. This was evidenced by the removal of amorphous silica, followed by the formation of nosean as a major phase. During the reaction between sodium sulphate and mullite coating, vanadium pentoxide was found to be acting as a flux and mineraliser. © 2023 Elsevier Ltd and Techna Group S.r.l.Atmospheric corrosionCorrosion resistant coatingsCorrosive effectsDiesel enginesHigh temperature corrosionMullitePlasma jetsPlasma sprayingSilicaSprayed coatingsSteel corrosionSulfur compoundsThermal barrier coatingsVanadium pentoxideCorrosion behaviourHot corrosionHot corrosion (C)Marine Diesel EnginesMullite (D)Mullite coatingsNosean (D)Plasma spray (A)Potential materialsSodium sulfate