Agent for the production of anti-corrosion layers on metal surfaces
View Patent ↗An agent for the production of anti-corrosion layers on metal surfaces is produced by producing an aqueous solution, which contains at least oxo-cations and halogen complex anions, and forming nanoparticles in the solution in situ by physical and/or chemical treatment of the solution. The oxo-cations are selected from MnO 3 + , VO 3+ , VO 2+ , WO 2 2+ , MoO 2 2+ , TiO 2+ , ZrO 2+ and mixtures thereof, and the halogen complex anions have the structure MX a b− , wherein M is selected from B, Ti, Zr, Si, Al, X is selected from F, Cl, Br, I, a is an integer of between 3 and 6 and b is an integer of between 1 and 4. The nanoparticles have a mean particle diameter of <500 nm.
1. An agent for the production of anti-corrosion layers on metal surfaces, produced by the following steps:
A) producing an aqueous solution which contains at least the following:
a) oxo-cations selected from MnO 3 + , VO 3+ , VO 2+ , WO 2 2+ , MoO 2 2+ , TiO 2+ , ZrO 2+ and mixtures thereof, in a concentration of between 0.1 and 0.5% by weight, and
b) halogen complex anions of the structure MX a b− , wherein M is selected from B, Ti, Zr, Si, Al, X is selected from F, Cl, Br, I, a is an integer of between 3 and 6 and b is an integer of between 1 and 4, in a concentration of between 0.1 and 3.0% by weight, and
B) forming nanoparticles the formation of which results in a positive Tyndall effect and having a mean particle diameter of <500 nm in the solution in situ by physical and/or chemical treatment of the solution, wherein the physical and/or chemical treatment is selected from the group consisting of supersaturation of the solution with halogen complex anions, agitation of the solution, and a combination thereof.
2. An agent as set forth in claim 1 characterised by the further step C) in which there is added to the solution produced in accordance with step B) an oxidative substance selected from hydrogen peroxide, organic peroxides, alkali metal peroxides, persulfates, perborates, nitrates and mixtures thereof.
3. An agent as set forth in claim 2 characterised by the further step D) in which the pH-value of the solution produced in accordance with step C) is adjusted by means of an acid or base to a value in the range of between 0.5 and 5.0.
4. An agent as set forth in claim 2 characterised in that the solution obtained in step B) is diluted with water in a ratio of between 1:3 and 1:5 prior to the addition of an oxidative substance in step C).
5. An agent as set forth in claim 2 characterised by the further step D) in which the pH-value of the solution produced in accordance with step C) is adjusted by means of an acid or base to a value in the range of between 1.0 to 3.0.
6. An agent as set forth in claim 2 characterised by the further step D) in which the pH-value of the solution produced in accordance with step C) is adjusted by means of an acid or base to a value in the range of between 1.3 and 2.0.
7. An agent as set forth in claim 1 characterised in that the formation of nanoparticles in accordance with step B) is effected at a temperature in the range of between ambient temperature and 100° C.
8. An agent as set forth in claim 1 characterised in that the halogen complex anions b) of the aqueous solution in step A) are added in the form of their metal salts.
9. An agent as set forth in claim 1 characterised in that there are added to the aqueous solution in step A) further metal salts.
10. An agent as set forth in claim 1 characterised in that the halogen complex anions b) are selected from BF 4 1− , TiF 6 2− , ZrF 6 2− , SiF 6 2− , AlF 6 3− and mixtures thereof.
11. An agent as set forth in claim 1 characterised in that the nanoparticles formed in step B) are of a mean particle diameter of <250 nm.
12. An agent as set forth in claim 1 characterised in that the formation of nanoparticles in accordance with step B) is effected at a temperature in the range of between 30° C. and 80° C.
13. An agent as set forth in claim 1 characterised in that the formation of nanoparticles in accordance with step B) is effected at a temperature in the range of between 35° C. and 50° C.
14. An agent as set forth in claim 1 characterised in that the halogen complex anions b) of the aqueous solution in step A) are added in the form of their alkali metal salts.
15. An agent as set forth in claim 1 characterised in that the halogen complex anions b) of the aqueous solution in step A) are added in the form of their sodium and potassium salts.
16. An agent as set forth in claim 1 characterised in that there are added to the aqueous solution in step A) further salts of the metals B, Ti, Zr, Si and/or Al.
17. An agent as set forth in claim 16 , wherein said further salts of the metals B, Ti, Zr, Si and/or Al are in the form of the metal halides, metal nitrates and/or metal sulfates.
18. An agent as set forth in claim 1 characterised in that the aqueous solution produced in step A) contains the oxo-cations in a concentration of between 0.1 and 0.3% by weight.
19. An agent as set forth in claim 1 characterised in that the aqueous solution produced in step A) contains the halogen complex anions in a concentration of between 0.5 and 2.0% by weight.
20. An agent as set forth in claim 1 characterised in that the nanoparticles formed in step B) are of a mean particle diameter of <200 nm.
21. An agent as set forth in claim 1 characterised in that the nanoparticles formed in step B) are of a mean particle diameter of <150 nm.