METAL ELECTRODEPOSITION METHOD AND ELECTROLYTIC MEDIUM FOR ELECTRODEPOSITION

Abstract

An electrodeposition process for electrodeposition of a metal on a metal part (1), includes the connection of the metal part (1) to be treated to a first electrical pole of a current generator and a second pole opposite the first pole connected to the electrolytic medium through an electrode (3), and includes relative movement of the metal part (1) in relation to a set of free solid particles (4) that retain a conductive solution. The solution includes metal cations of the metal to be deposited charged with a positive electrical charge in a non-conductive environment (5) that causes the reduction of the metal cations of the conductive solution on the surface of the metal part to be treated (1). An electrolytic medium for electrodeposition of a metal on a metal part (1) is also provided.

Claims

1. An electrodeposition process for electrodeposition of a metal on a metal part (1), comprising the connection of the metal part (1) to be treated to a first electrical pole of a current generator and a second pole opposite the first pole connected to the electrolytic medium through an electrode (3), characterised in that it comprises a step: of relative movement of the metal part (1) in relation to a set of free solid particles (4) that retain a conductive solution comprising metal cations of the metal to be deposited charged with a positive electrical charge in a non-conductive environment (5) that causes the reduction of the metal cations of the conductive solution on the surface of the metal part to be treated (1).

2. The electrodeposition process for electrodeposition of a metal on a metal part (1), according to claim 1, characterised in that it comprises a step: of deposition where the metal part (1) to be treated is connected to the negative electrical pole of the current generator and the electrolytic medium is connected to the positive electrical pole of the current generator through an electrode (3), and a step of control where the polarity of the current generator is reversed, that is, the metal part (1) to be treated is connected to the positive electrical pole of the current generator and the electrolytic medium is connected to the negative electrical pole of the current generator through an electrode (3).

3. The electrodeposition process for electrodeposition of a metal on a metal part (1), according to claim 1, characterised in that the electric current applied between the positive pole and the negative pole is a pulsed current.

4. The electrodeposition process for electrodeposition of a metal on a metal part (1), according to claim 1, characterised in that, at the beginning of the electrodeposition process, the metal ions of the metal to be deposited are located within the solid particles (4).

5. The electrodeposition process for electrodeposition of a metal on a metal part (1), according to claim 1, characterised in that, at the beginning of the electrodeposition process, the metal ions of the metal to be deposited are located in the electrode (3) in the form of metal, and during the electrodeposition process, the anode metal oxidises to metal cations in the conductive solution retained within the free solid particles (4) of the electrolytic medium.

6. An electrolytic medium for electrodeposition of a metal on a metal part (1), characterised by comprising: a set of free solid particles (4) that retain a conductive solution comprising metal ions of the metal to be deposited; and an interstitial space between the solid particles (4).

7. The electrolytic medium for electrodeposition according to claim 6, characterised in that the free solid particles (4) comprise ion exchange resin.

8. The electrolytic medium for electrodeposition according to claim 6, characterised in that the free solid particles (4) comprise porous ion exchange resin.

9. The electrolytic medium for electrodeposition according to claim 6, characterised in that the free solid particles (4) comprise gel-type ion exchange resin.

10. The electrolytic medium for electrodeposition according to claim 6, characterised in that the free solid particles (4) are based on strong or weak acid groups.

11. The electrolytic medium for electrodeposition according to claim 6, characterised in that the free solid particles (4) are ion exchange resins based on styrene/divinylbenzene-, acrylate- or methacrylate-based polymers and derivatives.

12. The electrolytic medium for electrodeposition according claim 6, characterised in that the free solid particles (4) are ion exchange resins based on chelating agents.

13. The electrolytic medium for electrodeposition according claim 6, characterised in that the free solid particles (4) are ion exchange resins with amino groups.

14. The electrolytic medium for electrodeposition according to claim 6, characterised in that there is a non-conducting medium (5) in the interstitial space between the solid particles (4).

15. The electrolytic medium for electrodeposition according to claim 10, wherein the strong or weak acid groups are sulfonic acid/sulfonate or carboxylic acid/carboxylate type groups.

Description

DESCRIPTION OF THE DRAWINGS

[0079] To complement the description that is being made and for the purpose of helping to better understand the features of the invention, a sheet of drawings has been attached to the present specification, as an integral part thereof, wherein the following has been depicted in an illustrative and non-limiting manner:

[0080] FIG. 1 shows a schematic depiction of the main elements involved in the electrodeposition process for electrodeposition of metals by ion transport by means of free solid bodies, object of the invention;

[0081] FIG. 2 shows a schematic depiction of a particle forming the solid bodies of the process, according to the invention, where its porous configuration and electrolyte liquid retention capacity that makes it electrically conductive can be seen;

[0082] FIG. 3 shows a schematic depiction of a portion of the surface of the part to be treated and several examples of the possible shapes that the particles used in the process can have; and finally

[0083] FIGS. 4 and 5 show respective diagrams similar to the one depicted in FIG. 1, showing respective moments of the process, where the moment of FIG. 4 is the case where a group of particles forms an electrical bridge of direct contact between the anode and the cathode, and FIG. 5 is another case where the particles rub against the surface of the part in an isolated manner.

EXEMPLARY EMBODIMENTS OF THE INVENTION

[0084] In a preferred embodiment, the electrolytic medium is formed by 0.1 to 1 mm spheres of ion exchange resin that retain a conductive aqueous solution containing cations of the metal to be deposited. Preferably, the ion exchange resin is a cation exchange resin. In a preferred formulation, the concentration of metal in the conductive solution retained in the particles is in a range going from 0.1 g of metal in 1 L of solution to 500 g of metal in 1 L of solution.

[0085] Examples of compositions of the aqueous solution retained by the ion exchange resin particles to deposit different metals are set forth below.

[0086] Dry Nickel Electrodeposition

[0087] For nickel electrodeposition, nickel(II) salts in an acidic medium are used. Preferably, the nickel salts used are nickel(II) sulfate Ni(SO.sub.4), nickel(11) chloride NiCl.sub.2 or nickel(II) sulfamate Ni(SO.sub.3NH.sub.2).sub.2.

[0088] Dry Zinc Electrodeposition

[0089] For zinc electrodeposition, zinc(II) salts in an acidic medium are used. Preferably, the zinc salts used are zinc(II) chloride ZnCl.sub.2.

[0090] Dry Gold Electrodeposition

[0091] For gold electrodeposition, gold(III) salts in a cyanide medium are used. Preferably, the gold salts used are gold(III) chloride AuCl.sub.3 or gold cyanide AuCN.sub.3.

[0092] Dry Silver Electrodeposition

[0093] For gold electrodeposition, silver(I) salts in a cyanide medium are used. Preferably, the gold salts used are silver(I) nitrate AgNO.sub.3 or silver cyanide AgCN.

[0094] Dry Electrodeposition of Copper

[0095] For copper electrodeposition, copper(II) salts in an acid medium are used.

[0096] Preferably, the copper salts used are copper(II) sulfate CuSO.sub.4.

[0097] Chromium Electrodeposition

[0098] One of the most used electrodeposition processes is to form hard chromium coatings. This process in liquid is very inefficient, where more than 80% of the electrical energy is dedicated to producing hydrogen reduction. The use of a solid electrolyte concentrates the electrical density at a few points, which increases efficiency. The use of a solid electrolyte containing chromium to produce a corrosion resistant coating.

[0099] Generally, Cr(VI) salts are used to obtain coatings of this type, the present invention uses Cr(III) salts.