Method for depositing a decorative and/or functional metal layer on a surface of an article made of an electrically non-conductive ceramic material

Patent metadata

Field	Value
Publication number	US-11952667-B2
Application number	US-202117476909-A
Country	US
Kind code	B2
Filing date	Sep 16, 2021
Priority date	Nov 19, 2020
Publication date	Apr 9, 2024
Grant date	Apr 9, 2024

Abstract

A method for depositing a decorative and/or functional layer on at least a portion of a surface of a finished or semi-finished article made of a non-conductive ceramic material, this deposition method includes the following operations: subjecting the at least a portion of the surface of the article to a carburising or nitriding treatment during which carbon, respectively nitrogen atoms, diffuse in the at least a portion of the surface of the article, then depositing, by galvanic growth of a metallic material, the decorative and/or functional layer on at least a portion of the surface of the article which has undergone the carburising or nitriding treatment.

First claim

The invention claimed is:

1. A method for depositing a decorative and/or functional layer on at least a portion of a surface of a finished or semi-finished article made of a ceramic material initially non-conductive of electricity, the method comprising:
subjecting the at least a portion of the surface of the article to a plasma carburizing or plasma nitriding during which, respectively, carbon or nitrogen atoms diffuse in the at least a portion of the surface of the article, then
depositing, by galvanic growth of a metallic material, the decorative and/or functional layer on the at least a portion of the surface of the article which has undergone the carburizing or nitriding,
wherein the plasma carburizing or plasma nitriding is carried out in a plasma reactor or in a hot filament reactor which allows to create a reactive atmosphere,
wherein the plasma carburizing or plasma nitriding comprises introducing the article into a reactor wherein an at least partial vacuum is created before creating a plasma obtained from ionizing a mixture of hydrogen, neutral gas, and traces of carbon, and
wherein the article is made of ZrO 2 , Al 2 O 3 , or SiO 2 .

2. The method of claim 1 , wherein, prior to the plasma carburizing plasma nitriding, the at least a portion of the surface of the finished or semi-finished article is subjected to a reduction, comprising depleting oxygen from the surface to the center of the finished or semi-finished article.

3. The method of claim 1 , wherein the article is subjected to the plasma carburizing, and
wherein the traces of carbon used to form the plasma are obtained from a hydrocarbon or a mixture of hydrocarbons.

4. The method of claim 3 , wherein the hydrocarbon(s) are ethane, methane, and/or acetylene.

5. The method of claim 1 , wherein the article is subjected to the plasma carburizing, and
wherein the neutral gas is argon.

6. The method of claim 1 , wherein the article is subjected to the plasma carburizing, and
wherein the article is maintained in the reactive atmosphere created by the plasma for a duration in a range of from 15 to 240 minutes.

7. The method of claim 1 , wherein the average temperature of the article during the plasma carburizing varies in a range of from 600 to 1300° C.

8. The method of claim 1 , wherein the article is subjected to the plasma nitriding, and
wherein the neutral gas is argon or neon.

9. The method of claim 1 , wherein the article is subjected to the plasma nitriding, and
wherein the article is maintained in the reactive atmosphere created by the plasma for a duration in a range of from 15 to 240 minutes.

10. The method of claim 1 , wherein the average temperature of the article during the plasma nitriding is established in a range of from 500 to 900° C.

11. The method of claim 1 , wherein the plasma is generated using a direct current discharge, by radiofrequency (RF) waves, or by microwave.

12. The method of claim 1 , wherein the plasma carburizing or plasma nitriding is carried out in a hot filament reactor, comprising creating an at least partial vacuum in the hot filament reactor before creating a reactive atmosphere of atomic carbon or atomic nitrogen which is optionally supplemented by atomic hydrogen.

13. The method of claim 2 , wherein the plasma carburizing or plasma nitriding is carried out in a hot filament reactor, comprising creating an at least partial vacuum in the hot filament reactor before creating a reactive atmosphere of atomic carbon or atomic nitrogen whichis optionally supplemented by atomic hydrogen.

14. The method of claim 12 , wherein the hot filament reactor comprises a filament, and
wherein a temperature of the filament reaches at least 1500° C.

15. The method for of claim 14 , wherein the at least one filament is made of a refractory metallic material.

16. The method of claim 1 , wherein the ceramic article is transformed over a thickness in a range of from 10 to 1000 nm,
wherein an outermost layer of the ceramic article comprises zirconium carbide or nitride over a thickness of in a range of from 20 to 200 nm.

17. The method for of claim 1 , wherein the article is made of the Zr 2 .

18. The method of claim 14 , wherein the zirconia is in tetragonal phase.

19. The method of claim 18 , wherein the tetragonal phase is stabilized at room temperature by adding 3 mol % of yttrium oxide Y 2 O 3 .

20. The method of claim 1 , wherein the metallic material for the galvanic growth comprises gold, silver, copper, platinum, indium, palladium, rhodium, white bronze, yellow bronze, and/or nickel or alloys of these metals.

21. The method of claim 20 , wherein the galvanic growth is carried out in a bath having temperature in a range of from 60 to 70° C., and
wherein the bath circulates a current with a current density in a range of from 0.1 to 1.0 A/dm 2 .

22. The method of claim 21 , wherein the galvanic growth is of a gold-copper alloy on carburized parts, and uses potassium cyanide is used as a catalyst.

23. The method of claim 22 , wherein the galvanic growth is of 18 carat gold, using a current density in a range of from 0.4 to 0.5 A/dm 2 .

24. The method of claim 1 , wherein the article after carburizing or nitriding treatment has a surface electrical resistance less than 10 Ω/□.

25. The method of claim 6 , wherein the article is maintained in the reactive atmosphere created by the plasma for a duration of 150 minutes.

26. The method of claim 9 , wherein the article is maintained in the reactive atmosphere created by the plasma for a duration of 150 minutes.

27. The method of claim 1 , wherein the article is made of the Al 2 O 3 .

28. The method of claim 1 , wherein the article is made of the SiO 2 .

29. The method of claim 1 , wherein diffusion of carbon or nitrogen atoms into the article creates crystallites of zirconium carbide or zirconium nitride, to a depth of 1 μm from the surface of the article.

30. The method of claim 1 , wherein the plasma carburizing or plasma nitriding is applied at the same rate to an entire surface of the article exposed to an atmosphere of the reactor.

Assignees

• Swatch Group Res & Dev Ltd

Inventors

• Curchod Loïc
• Vuille Pierry

Classifications

• C23C8/02 Primary

  Pretreatment of the material to be coated (C23C8/04 takes precedence) · CPC title

• A44C27/006

  Metallic coatings · CPC title

• C04B41/0054

  Plasma-treatment, e.g. with gas-discharge plasma · CPC title

• C04B41/009

  characterised by the material treated · CPC title

• C04B41/5001

  with carbon or carbonisable materials · CPC title