日本金属学会誌

J. Japan Inst. Metals, Vol. 52, No. 3 (1988),
pp. 288-294

Mechanism of Hot Corrosion of Iron in Molten Sulfate

Hiroo Numata1, Yasuo Hirano2 and Shiro Haruyama1

1Department of Metallurgical Engineering, Faculty of Engineering, Tokyo Institute of Technology, Tokyo
2Graduate Student, Tokyo Institute of Technology, Tokyo. Present address: Kurami Factory, Nippon Kogyo Ltd., Koza-Gun, Kanagawa

Abstract:

Corrosion of iron in alkali-sulfate melt containing Fe2(SO4)3 has been studied with electrochemical polarization technique. The corrosion rate of iron increased with increasing the concentrations of ferric ion below 10 mol%. The polarization curves of iron consisted of the anodic dissolution of iron and the cathodic reduction of ferric ion in the potential region from 0.3 to -0.5 V. Polarization study showed that the corrosion reaction was controlled by a diffusion-limited cathodic reduction of ferric ion and the rate of corrosion was proportional to the concentration of ferric ion. It was found that the cathodic reaction was also promoted by the corrosion product such as ferrous ion which was chemically oxidized and functioned as an oxidant. Thus, the corrosion of iron in molten sulfate was explained by an auto-catalytic mechanism of the corrosion product.


(Received 1987/8/6)

Keywords:

hot corrosion, iron, electrochemical study, polarization resistance, alkali-sulfate, corrosion product, corrosion mechanism


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