Improvement of corrosion resistance of plasma sprayed and laser treated material for boiling sulfuric acid process by pre-oxidation

Ioka, Ikuo  ; Kuriki, Yoshiro*; Iwatsuki, Jin ; Kubo, Shinji  ; Inagaki, Yoshiyuki; Sakaba, Nariaki 

IS process is one of candidates for the large-scale production of hydrogen. Severe corrosive environment which is thermal decomposition of sulfuric acid exists in the IS process. A hybrid material with the corrosion-resistance and the ductility was made by a plasma spraying and laser treatment. The specimen had excellent corrosion resistance in the condition of 95% boiling sulfuric acid. On the other hand, the corrosion rate of the specimen in 47% boiling sulfuric acid was fifty times higher than that in 95% boiling sulfuric acid. It seems that the cracks of the surface layer weren't sealed up perfectly in the condition of 47% boiling sulfuric acid. To improve the corrosion resistance of the specimen in 47% boiling sulfuric acid, the specimen was treated with a thermal treatment for pre-oxidation. The pre-oxidized specimen got superior corrosion resistance in the condition of 47% boiling sulfuric acid. It was confirmed that the pre-oxidation was effective in improving corrosion resistance of the specimen.