Passivity of stainless steel in sulphuric acid under chemical oxidation |
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| Authors: | Yingying Yue Peiyang Shi Maofa Jiang |
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| Affiliation: | Key Laboratory for Ecological Metallurgy of Multimetallic Ores (Ministry of Education), School of Metallurgy, Northeastern University, Shenyang, Liaoning, People’s Republic of China |
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| Abstract: | The main purpose of the present work was to study the passivity of stainless steel in sulphuric acid under chemical oxidation with H2O2 solution. Potentiodynamic polarisation and open circuit potential (OCP) measurements indicated that H2O2 facilitates the increase of OCP of stainless steel which shifts from active region into passive region. The X-ray photoelectron spectroscopy results suggested that a passive film, composed of oxyhydroxides, Cr2O3, Cr(VI) species, NiO, and sulphate (FeSO4, Cr2(SO4)3·xH2O), is achieved after H2SO4–H2O2 passivation. The passive mechanism under H2O2 oxidation was discussed and the corrosion resistance of passive film was compared with that of the passive films produced by HNO3 passivity and H2SO4 potentiostatic passivity. The results of electrochemical impedance spectroscopy, cyclic voltammetry, and anodic polarisation experiments confirmed that the chemical oxidation with H2O2 solution is capable of improving the corrosion resistance of stainless steel significantly and the passive film is more stable than those produced by other passivating methods. |
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| Keywords: | Passive film sulphuric acid oxidant open circuit potential stainless steel |
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