N, M.Santhy, K.Rajasekaran, R.2026-02-042023International Journal of Hydrogen Energy, 2023, 48, 81, pp. 31767-317783603199https://doi.org/10.1016/j.ijhydene.2023.04.322https://idr.nitk.ac.in/handle/123456789/21720A new and novel approach has been adopted in this study to evaluate thermal mismatch induced by thermal expansion in substrate-coating contact pairs using in-situ high-temperature X-ray diffraction (HT-XRD). Atmospheric plasma sprayed (APS) Mn<inf>1.0</inf>Co<inf>1.9</inf>Fe<inf>0.1</inf>O<inf>4</inf> (MCF) coating on Crofer 22 APU steel interconnect was investigated. In-situ HT-XRD was performed individually for substrate and coating from 25 °C to 900 °C. Diffraction data were recorded for different temperatures to obtain lattice parameters and strain as a function of temperature. The coefficient of thermal expansion (CTE) of MCF coating was slightly higher than steel substrate and showed no significant thermal expansion mismatch till 700 °C. The increasing lattice strain measured by Scherrer and Williamson-Hall methods indicates strain-induced phase transformation of MCF coating with temperature, supporting the phase transformation-induced self-healing phenomenon of MCF coating. The merit of in-situ HT-XRD as a tool for optimizing operating temperature and measuring thermal mismatch of solid oxide fuel cell (SOFC) stacks has been discussed. © 2023 Hydrogen Energy Publications LLCAtmospheric temperatureCoatingsManganese alloysManganese compoundsPhase transitionsPlasma jetsPlasma sprayingSolid oxide fuel cells (SOFC)X ray diffractionEffects of strainsHigh-temperature X-ray diffractionIn-situ XRDMetallic interconnectsPlasma-sprayedSolid-oxide fuel cellSpinel coatingStrain-induced phase transformationThermal mismatchThermal mismatch stressThermal expansion