USE OF SULFONIC ACIDS IN DRY ELECTROLYTES TO REMOVE VAPOR DEPOSITED AND/OR THERMALLY SPRAYED COATINGS ON METAL SURFACES

Abstract

The use of dry electrolytes to strip vapor or thermal spray deposition coated metal surfaces through ion transport, wherein the conductive liquid of the dry electrolyte comprises at least a sulfonic acid.

Claims

1.-12. (canceled)

13. A method of stripping a vapor or thermal spray deposition coated metal surface through ion transport, the method comprising contacting the metal surface with a conductive liquid of a dry electrolyte, wherein the conductive liquid comprises at least a sulfonic acid

14. The method of claim 13, wherein the dry electrolyte comprises porous particles.

15. The method of claim 14, wherein the porous particles comprise a sulfonate polymer.

16. The method of claim 14, wherein the porous particles comprise an ion exchange resins of polystyrene-divinylbenzene.

17. The method of claim 13, wherein the sulfonic acid comprises methane-sulfonic acid.

18. The method of claim 13, wherein the concentration of sulfonic acid in relation to a solvent is from 1% to 70%.

19. The method of claim 13, wherein the conductive liquid further comprises a complexing agent.

20. The method of claim 19, wherein the wherein the complexing agent comprises a polyether.

21. The method of claim 20, wherein the wherein the polyether is linear alkyl.

22. The method of claim 21, wherein the wherein the polyether is polyethyleneglycol.

23. The method according to claim 22, wherein the polyethyleneglycol has a molecular weight ranging from 200 to 500 Da.

24. The method of claim 21, wherein the wherein the polyether is polypropyleneglycol.

25. The method of claim 13, wherein the conductive liquid further comprises a chelating agent.

Description

EXEMPLARY EMBODIMENTS AS DESCRIBED IN EP3795722

Example 1 in EP3795722

[0033] A dry electrolyte was prepared mixing and homogenizing 1.5 kg of ion exchange resin AMBERLITE 252RFH with 550 ml of a solution of methanesulfonic acid to 4% of water. This dry electrolyte is used to polish a part of iron alloy with the following composition expressed in % C (0.17-0.23) Si (0.40) Mn (0.65-0.95) V (0.025) S (0.050) Cr (0.35-0.70) Ni (0.40-0.70) Mo (0.15-0.55) Cu (0.35) Al (0.050) with a surface area of 5 cm2. The counter-electrode was a network of iridium on titanium. The current used was a positive wave of an electric current of 50 Hz at 20 V, that provided an intensity of 0.1 A. The part had a downwards/upwards movement at around 4 Hz and the dry electrolyte container was submitted to a vibration. After 5 minutes of this proceeding, the metal surface had acquired spectacular properties.

Example 2 in EP3795722

[0034] A dry electrolyte was prepared mixing and homogenizing 5.3 kg of ion exchange resin AMBERLITE 252RFH with 1950 ml of a methanesulfonic acid solution at 32% in water. This dry electrolyte is used to polish a part of iron alloy having the same composition as before with a surface area of 36 cm2. The counter-electrode was a network of iridium on titanium. The current used was a positive wave of an electric current of 50 Hz at 30 V. The part had an upwards/downwards movement at around 4 Hz and the dry electrolyte container was submitted to a vibration. After 10 minutes of this process, the metal surface had acquired spectacular properties.

Example 3 in EP3795722

[0035] A solution was prepared with 550 mL of methane sulfonic acid 70%, 160 mL PEG and 3000 mL of de-ionized water. This solution is mixed and homogenized with 6.7 kg of ion exchange resin AMBERLITE 252RFH to produce a dry electrolyte. This dry electrolyte was used to polish a part of carbon steel of 36 cm2. The counter-electrode used was a network of iridium on titanium. The current used was a positive wave of an electric current of 50 Hz at 30 V. The part had a downwards/upwards movement ca. 4 Hz and the dry electrolyte container was submitted to vibration. After 5 minutes of this process the metal surface had acquired spectacular properties.

SUMMERY OF THE INVENTION

[0036] Turning back to the present invention the inventors surprisingly realized that the polishing process as described in EP3795722 can as well efficiently be used to perform a stripping process.

[0037] The object of this invention refers to the method to strip vapor deposited coatings fand/or thermally sprayed coatings from a metallic surface of a substrate. The core of the invention is the use of ion transport that uses free solid bodies that contain sulfonic acids as electrolytes. All the aspects as described above related to EP3795722 can be applied to the stripping process according to the present invention.

[0038] Therefore according to the present invention sulfonic acids in free solid bodies or particles as described above are used to remove vapor deposited and/or thermally sprayed coatings from metal surfaces through ions transport. This can be used in the same way as described above for polishing. The vapor deposited coatings could be for example physical vapor deposited (PVD) coatings and/or chemical vapor deposited (CVD) coatings.

[0039] The invention will now be described in detail on the basis of examples.

[0040] As a first example a CrAlN-based coating (brand name FORMERA) which had been cathodic arc deposited onto an iron alloy. The thickness of the coating was about Sum. A dry electrolyte was prepared mixing and homogenizing 1.5 kg of ion exchange resin AMBERLITE 252RFH with 550 ml of a solution of methanesulfonic acid to 4% of water. This dry electrolyte is used to strip the iron alloy substrate. The counter-electrode was a network of iridium on titanium. The current used was a positive wave of an electric current of 50 Hz at 20 V, that provided an intensity of 0.1 A. The part had a downwards/upwards movement at around 4 Hz and the dry electrolyte container was submitted to a vibration. After 30 minutes of this proceeding, the coating was completely removed as can be seen in FIG. 1. FIG. 1 shows in addition that the surface of the substrate is slightly roughened, which proposes that this process is different to a polishing process.

[0041] As a second example an AlCrN-based coating (brand name ALNOVA) which had been cathodic arc deposited onto an carbon steel. The thickness of the coating was again about 5 m.

[0042] A solution was prepared with 550 mL of methane sulfonic acid 70%, 160 mL PEG and 3000 mL of de-ionized water. This solution is mixed and homogenized with 6.7 kg of ion exchange resin AMBERLITE 252RFH to produce a dry electrolyte. This dry electrolyte was used to strip the carbon steel substrate. The counter-electrode used was a network of iridium on titanium. The current used was a positive wave of an electric current of 50 Hz at 30 V. The part had a downwards/upwards movement ca. 4 Hz and the dry electrolyte container was submitted to vibration. After 30 minutes of this process the coating was completely removed as can be seen in FIG. 2.

[0043] The present invention relates to the use of dry electrolytes to strip vapor or thermal spray deposition coated metal surfaces through ion transport, characterized in that the conductive liquid of the dry electrolyte comprises at least a sulfonic acid.

[0044] The porous particles of the dry electrolyte can comprise sulfonate polymer.

[0045] The porous particles of the dry electrolyte can comprise ions exchange resins of polystyrene-divinylbenzene.

[0046] The conductive liquid of the dry electrolyte can comprise methane-sulfonic acid.

[0047] The concentration of sulfonic acid in relation to the solvent can ranging from 1 to 70%.

[0048] The conductive liquid of the dry electrolyte can comprises a complexing agent. The complexing agent can comprise a polyether. The polyether can be a linear alkyl.

[0049] The polyether can comprise or be polyethyleneglycol. The polyethyleneglycol can have a molecular weight ranging from 200 to 500 Da.

[0050] The polyether can be polypropyleneglycol.

[0051] The conductive liquid of the dry electrolyte can be a chelating agent.