METHOD FOR PRODUCTION OF SUBSTRATE WITH CHROMIUM VI FREE AND COBALT-FREE PASSIVATION Russian patent published in 2018 - IPC C23C22/06 C23C22/34 C23C22/44 C23C22/46 C23C22/60 

FIELD: metallurgy.

SUBSTANCE: invention relates to the passivation of a metal surface. Method includes first acid passivation and second alkaline passivation of the metal substrate. In the first acid passivation, an aqueous acidic composition containing a chromium (III) compound is applied to said substrate, wherein said compound is selected from the group consisting of chromium (III) sulphate, chromium (III) hydroxide, chromium (III) dihydrogen phosphate, chromium (III) chloride, chromium (III) nitrate, chromium (III)-sodium sulphate, chromium (III) -potassium sulphate and chromium (III) salts with organic acids, as well as phosphonic acid and / or its derivatives in amounts of 0.5 to 3% by weight, based on the weight of the aqueous acidic composition, and for the second alkaline passivation, an aqueous alkaline composition is used, which contains silicates modified with silane and/or siloxane.

EFFECT: invention enables, without the use of additional metal compounds in the first acid passivation, to obtain a passivated metal surface without chromium VI and cobalt having good corrosion protection.

18 cl, 5 tbl