Impact of pre-oxidation on the reactivity and conductivity in H2–H2O atmosphere of a ferritic stainless steel for high temperature water vapour electrolysis
Résumé
The as-rolled K41X (AISI 441) ferritic stainless steel presents unusual behaviour when exposed in H2-H2O atmosphere at 800°C, with growth of non-protective iron oxides at its surface. The impact of pre-oxidation in air is investigated in this paper. The pre-oxidation induces the formation of a thin chromia layer at the steel surface. The results obtained after subsequent oxidation for 100 hours in H2-H2O atmosphere evidence a change in the surface reactivity behaviour of the as-rolled alloy: iron oxides formation is avoided and high temperature behaviour (reactivity and conductivity) is improved. Air pre-oxidation seems a promising solution for large scale use of K41X as-rolled steel in H2-H2O atmosphere at high temperature.