EIS study of high-temperature oxide films on a stainless steel (253MA)- influence of alloying elements

Alloying elements such as chromium, silicon and cerium in stainless steels are important for the oxidation behavior of the material at high temperatures. In this work, the oxide films formed on a stainless steel (253MA) with a small variation in the content of chromium, silicon and cerium, were characterized by electrochemical impedance spectroscopy (EIS), after exposure up to 100 hours in air at 750 and 1100 C. The EIS spectra suggest a two-layer feature of the oxide films, in agreement with complementary surface analysis. The influence of a small variation in alloying element content on the oxidation behavior was revealed by the difference in the electrical properties of the oxide films. At 750 C, the influence becomes pronounced after 100 hours of oxidation, and the steel with a lower content of chromium, silicon and cerium exhibits a lower film resistance. At 1100 C, the oxide film formed on the steel with a lower content of chromium, silicon and cerium starts to degrade earlier than that on the steel with a higher content of chromium, silicon and cerium. (orig.)