The corrosion of Ni in O 2+SO 2 atmospheres in the temperature range 500–750 °C

Abstract

The corrosion of pure Ni sheet by controlled mixtures of SO 2 + oxygen has been studied in the temperature range 500–750 °C. At a given temperature the rate of attack passed through a maximum value for SO 2-rich gas mixtures. The mechanism was usually of the parabolic diffusion-controlled type, but at the highest rates of attack the process had linear kinetics. The corrosion products were a mixture of nickel oxide and sulphide, and from the results of X-ray diffraction, microprobe analysis and marker studies it was concluded that this type of corrosion only occurs when the metal sulphate can be formed. The sulphate is subsequently reduced to a sulphide-oxide mixture.