Passivation of stainless steels in organosulphonic acid medium
AssigneeElf Atochem S.A.
InventorsJean Goudiakas, Guy Rousseau
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Abstract
To avoid the corrosion of stainless steels in organosulphonic acid medium, at least one oxidizing agent selected from cerium(IV), iron(III), molybdenum(VI) or vanadium(V) oxides or salts, nitrites and persulphates, is added to the medium in an amount which is sufficient to place the spontaneous potential between the passivation and transpassivation potentials.
Claims23
Process for protecting against corrosion of stainless steel in contact with an organosulphonic acid, comprising adding an amount of at least one oxidizing agent selected from cerium(IV), iron(III), molybdenum(VI) or vanadium(V) oxides or salts, nitrites and persulphates to an aqueous solution of said organosulphonic acid, said amount being sufficient for the spontaneous potential of said aqueous organosulphonic acid solution, measured using a stainless steel electrode, to be within the passivation zone determined under the same conditions in the absence of said oxidizing agent.
Aqueous alkanesulphonic acid solution containing at least one oxidizing agent selected from cerium(IV), molybdenum(VI) or vanadium(V) oxides or salts, nitrites and persulphates, in an amount which is sufficient for its spontaneous potential, measured using a stainless steel electrode, to be within the passivation zone determined under the same conditions in the absence of said oxidizing agent.
Aqueous alkanesulphonic acid solution containing at least one oxidizing agent selected from cerium (IV), molybdenum (VI) or vanadium (V) oxides or salts, and persulphates, in an amount which is sufficient for its spontaneous potential, measured using a stainless steel electrode, to be within the passivation zone determined under the same conditions in the absence of said oxidizing agent.
Dependencies are inferred from the claim text.