Corrosion of lanthanum magnesium hexaaluminate as plasma-sprayed coating and as bulk material when exposed to molten V2O5-containing salt

•Corrosion behavior of LaMgAl11O19 bulk and plasma sprayed coating has been compared.•Degradation mechanism is investigated based on LaMgAl11O19’s crystal chemistry.•LaMgAl11O19 coating displays inferior corrosion resistance to well crystallized bulk.

Corrosion of LaMgAl11O19 (LaMA) bulk and plasma sprayed coating was studied in molten V2O5-containing salt at 710–1050 °C in air. Results indicate that the well crystallized LaMA bulk exhibited prior corrosion resistance to the plasma sprayed LaMA coating with amorphous phase and reduced chemical bond strength in its crystal structure. La–O chemical bonds with the lowest bond energies were the easiest bonds in the LaMA crystal to be broken by molten V2O5-containing salt attack to form LaVO4 at each temperature level for both LaMA bulk and coating. Corrosion products of the LaMA coating were much different at temperature below 900 °C.