抄録
In order to assess the protectiveness of preformed Al2O3 scale in an H2-10%H2S atmosphere and the influence of Hf addition on it, Fe-10 mass%Al alloys with or without Hf were oxidized in pure O2 at 1300 K for specified periods up to 400 ks and subsequently sulfidized at 1200 K without an intermittent cooling. The addition of 0.088 mass%Hf suppresses the formation of wavy scales which are often associated with mechanical defects and improves the mechanical soundness of the scale. As a result of this the protection time also increases. These benefits were considered to be due to the modification of the mode of diffusion through the scale. The complete prevention of sulfidation by the scale was found to be impossible, since sulfides were formed on scales which looked very sound.
