Atomic modeling for the initial stage of chromium passivation
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The well-known anti-corrosive property of stainless steels is largely attributed to the addition of Cr, which can assist in forming an inert film on the corroding surface. To maximize the corrosion-resistant ability of Cr, a thorough study dealing with the passivation behaviors of this metal, including the structure and composition of the passive film as well as related reaction mechanisms, is required. Here, continuous electrochemical adsorptions of OH-groups of water molecules onto Cr terraces in acid solutions are investigated using DFT methods. Different models with various surface conditions are applied. Passivation is found to begin in the active region, and a fully coated surface mainly with oxide is likely to be the starting point of the passive region. The calculated limiting potentials are in reasonable agreement with passivation potentials observed via experiment.
Keywordschromium acid solutions passive films interfaces modeling studies
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This work was financially supported by the National Key Research and Development Program of China (No. 2017YFB0702100) and the National Natural Science Foundation of China (Nos. 51571028, 51431004, and U1706221). L.N. Zhang gratefully acknowledges financial support from China Scholarship Council.
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