Q. Explain Sulphidation process?
The presence of sulphur converts the surface of the metal to a sulphide scale which is generally more destructive than an oxide scale. Sulphidation is highly dependent on the form in which the sulphur exists, and corrosivity generally increases as temperature increases. Resistance to attack is improved by the addition of Cr and Si, as well as Al to a lesser extent. The addition of nickel may contribute to sulphide scaling.