Cover Picture: Materials and Corrosion. 8/2014



The cover shows the corrosion layer and the deposits on 9Cr-1Mo P91 steel that was exposed under industrial conditions to a syngas environment containing multiple oxidants, such as water vapour, vanadium compounds and hydrogen sulfide at about 450 °C.

The image was taken by the metallography group of DECHEMA-Forschungsinstitut, Frankfurt am Main. The “differential interference contrast” (DIC) imaging mode was used to evaluate the occurrence of different layers within the deposits. A thick chromium sulfide layer had formed in contact with the underlying metal. Above the chromium sulfide layer different layers of deposits are visible that contain elements such as chlorine, sodium, vanadium, calcium and phosphorus. At high temperatures these deposits may transfer into the molten state, penetrating the chromium sulfide layer and rapidly dissolving the underlying metallic material. For more detailed information please contact