ES2286938B1 - ELECTROLYTIC SOLUTION FOR ELECTROCHEMICAL POLISHING OF METAL ITEMS. - Google Patents

Abstract

Electrolytic solution for electrochemical polishing of metal articles that constitute the anode in a polishing process by application of electric current. The solution comprises at least one compound of the alkylbenzenesulfonic family of formula I, ** FIGURE ** its salts or derivatives, where R {sub, 1} corresponds to an alkyl radical of 10 to 14 carbons; and R {sub, 2} is selected from a hydrogen atom and an alkyl radical of 10 to 14 carbons.

Description

Electrolytic solution for polishing electrochemical metal items.

Technical sector of the invention

The present invention relates to a solution electrolytic for electrochemical polishing of metal articles which constitute the anode in a polishing procedure by electric current application. Also refers to a new electrochemical polishing procedure and a device for carry out said procedure.

Background of the invention

The electropolishing processes of metals are based on the extraction of ions from the surface of said Geometrically selective metals. In fact, this geometric selectivity, or shape, depends on what the ionic transport restrictions determined by the layer of electrolyte that remains in immediate contact with the surface of the metal part to be polished, that is, the known electrolyte layer as an anodic layer.

The ionic transport restrictions to which referenced are due to polarization.

In conventional electropolishing processes, polarization produces electrical conductivity gradients in the anodic layer, basically due to differences in concentration of ions of the metal to be polished and the increase in viscosity caused by the increase in ionic concentration.

Thus, in the protuberant areas of the piece minimum polishing takes place minimum passivity because it hinder the aforementioned differences in concentration of ions, while the viscosity is lower than in the cavities of the relief where there are usually maximum passivity.

As a result the metal is extracted in greater proportion of protuberant areas with respect to concavities of the relief getting the polishing of the surface of the piece metallic

However, the field of application of these conventional electropolishing processes is strongly conditioned because only the thicknesses of the film or anodic layer of a few microns can be achieved, so that only reliefs of a few microns can be smoothed. This fact causes that for the polishing of the metallic pieces it is necessary to first perform a polishing of the relief by strictly mechanical methods and then profiling or polishing by application of conventional electropolishing, which makes the process complex and
lengthens

In addition, it should be noted that to get properly respect the large-scale geometry of the pieces to polishing, in a mechanical polishing process it is necessary to use, necessarily useful with a certain stiffness (bands, rotary discs, rotary cylinders ...), which confine the action erosive to predetermined areas.

This greatly hinders the automation of processes, especially when trying to polish geometry pieces complex and different from each other.

For all this, the inventors have developed a new electrolytic solution that allows the polishing of parts or metal articles without the use of strictly procedures mechanical and that, being used in devices also developed by the inventors, they allow the polishing of metal parts of Any geometric shape and completely automatically.

Explanation of the invention.

In essence, the electrolyte solution object of the invention is characterized in that it comprises at least one compound of the alkylbenzenesulfonic family of formula I,

       \ vskip1.000000 \ baselineskip
    

2

       \ vskip1.000000 \ baselineskip
    

its salts or derivatives, where R1 corresponds to an alkyl radical of 10 to 14 carbons; Y R2 is selected from a hydrogen atom and a radical rent from 10 to 14 carbons

The electrolytic solution according to the invention is also characterized in that it comprises an alkylbenzenesulfonic compound of formula I wherein R 1 is an alkyl radical of 10 to 14 carbon atoms and R 2 is hydrogen; and an alkylbenzenesulfonic compound of formula I wherein R1 and R2 correspond to alkyl radicals of 10 to 14 atoms of
carbon.

Preferably, the weight percentage of alkylbenzenesulfonic compound of formula I wherein R 1 is a radical alkyl of 10 to 14 carbon atoms and R2 is hydrogen, it is between 2.0% and 4.0%. Similarly, the percentage by weight of alkylbenzenesulfonic compound of formula I wherein R1 and R2 correspond to alkyl radicals of 10 to 14 carbon atoms, it is between 10.0% and 17.0%.

According to another feature of the invention, the electrolyte solution comprises a hydrocarbon in a proportion by weight with respect to the alkylbenzenesulfonic compound or compounds between 15% and 75%.

In addition, the electrolytic solution according to the invention is characterized in that it comprises particles Chemically inert.

Another object of the present invention is the use in a metal polishing process by application of electric current of an electrolyte solution comprising the minus a compound of the alkylbenzenesulfonic family of formula I, its salts or derivatives, where R_ {1} corresponds to a alkyl radical of 10 to 14 carbons; and R2 is selected from a hydrogen atom and an alkyl radical of 10 to 14 carbons.

Preferably, for the polishing process of metals by application of electric current are used electrolytic solutions according to the invention comprising a alkylbenzenesulfonic compound of formula I wherein R 1 is a radical alkyl of 10 to 14 carbon atoms and R2 is hydrogen; and a alkylbenzenesulfonic compound of formula I wherein R1 and R2 correspond to alkyl radicals of 10 to 14 carbon atoms. Plus preferably, the electrolytic solution used comprises chemically inert particles in suspension and between 15% and 75% by weight of a hydrocarbon with respect to the percentage by weight of the alkylbenzenesulfonic compound or compounds of formula I.

An object of the present invention is also a procedure of polishing metal articles by application of electric current between an anode and a cathode, the anode being the metal article to be polished, comprising at least one stage of interaction of said anode with dielectric inert particles of size greater than 100 microns.

The process according to the invention is also characterized because it includes cycles in which they happen a semi-period in which the anode is in contact with the solution electrolytic free of chemically inert particles and a semi-period in which the anode is in contact with a solution electrolytic that contains chemically inert particles in suspension.

According to another feature of the procedure object of the invention, the semi-period in which the anode is in contact with an electrolytic solution containing particles chemically inert in suspension comprises, in turn, a stage of fluidization of said particles and a stage of compaction of said particles.

Another object of the present invention is a device for polishing metal articles by application of electric current between an anode and a cathode, the anode being the metal article to be polished, adapted to carry out the procedure as described in the previous paragraphs.

The device according to the invention is characterized because it comprises at least one container divided by a wall vertical separation that defines two vessels intercommunicated by their bottom, the first one adapted to contain the anode of the electrochemical reaction and provided with means of separation permeable to liquid solutions located in its part lower; and the second vessel provided with oscillation means of the liquid contained inside.

According to another feature of the device of the invention, the solution permeable separation means liquids consist of a plate provided with multiple holes

According to another feature of the device of the invention, the solution permeable separation means Liquids consist of a mesh.

Brief description of the drawings

The attached drawings illustrate, by way of non-limiting example, an embodiment of a device according to the invention, where the steps of the procedure used by it. Schemes are also presented that aim to clarify the behavior of the solution electrolytic around the metal part to be polished along polishing procedure In these drawings:

Fig. 1 corresponds to an elevation view and schematic of the device object of the invention, where they visualize two glasses intercommunicated by means of separation permeable;

Fig. 2 corresponds to the same view as the Fig. 1 but at a stage of the most advanced polishing procedure, specifically when the metal part to be polished comes into contact with chemically inert particles;

Fig. 3 shows the same device of the Figs. 1 and 2 but at another stage of the semi-period in which the piece metallic is in contact with chemically inert particles, specifically when they are compacted;

Fig. 4 is a rough surface scheme of metal to be polished, where a particle can be visualized chemically inert located in contact with said piece; Y

Fig. 5 corresponds to another scheme that illustrates the behavior of the electrolytic solution according to the invention in the final stages of the electrolytic polishing process.

Detailed description of the drawings

Then, as an example, no limiting, components and percentages by weight are detailed of an electrolytic solution 1 according to the invention, useful for electrochemical polishing of metal articles 2 where mentioned Article 2 constitutes the anode in the polishing procedure.

       \ vskip1.000000 \ baselineskip
    

Example 1 Electrolytic solution for electropolishing articles of copper and its alloys

3

The final solution must have a pH included between 7.5 and 9, preferably 8.

The working conditions in this case and for This solution is from:

Voltage = 14V Ta = 20 ° C - 30ºC t_ {cycle} = 1.2 s. t_ {TOTAL} = 70 min

The t_ {TOTAL} refers to the time spent to smooth roughness 11 maximum of the order of tenths of microns

As chemically inert particles 3 is They use 2 mm diameter glass spheres.

The presence of particles is also expected. chemically inert 3 of other materials, such as particles of different types of polyolefins or wood, provided they have a size greater than 100 microns.

In this solution 1 described in Example 1, as compounds of the alkylbenzenesulfonic family of formula I the sodium salt of decylbenzenesulfonic acid is used, which corresponds to the case of R1 equal to an alkyl radical of 10 carbon atoms and an R2 equivalent to an atom of hydrogen. The sodium salt of an acid is also used any dialkylbenzenesulfonic acid with alkyl radicals from 10 to 14 carbon atoms

In a preferred solution formulation electrochemistry 1 according to the invention, are included compounds that act as adjuvants, that is, that optimize the rheology of the anodic layer, such as fatty acid molecules.

In order to detail the procedure of electrochemical polishing of metallic articles 2 object of invention, reference is made to the attached Figs. 1 to 3. Based on these figures also illustrates an embodiment of the device 4 for polishing metal articles 2 according to the invention.

Thus, in Fig. 1 a container can be seen 5 comprising the electrolytic solution 1 according to the invention, the which container 5 is divided into two vats or vessels 7 and 8 intercommunicated by its lower part and that are defined by a vertical separation wall 6. The first vessel 7 is adapted to contain the anode of the electrochemical reaction, how about and As already stated above consists of the metal part 2 to polish. Said piece or metallic article 2 is fixed by fastening means or metal racks (such as hooks) that ensure electrical contact with them as well as their positioning in the first vessel 7 and which, in turn, are in contact (although not shown) with the anodic terminal (positive pole) of an electric current source.

In addition, in its lower part the first glass 7 of the container 5 comprises separation means permeable to liquid solutions 9, being defined in this way and in collaboration with the vertical separation wall 6, the second vessel 8 with solution electrolytic 1 that is communicated with the first 7 through said permeable separation means 9. These means of separation 9 consist of a plate provided with multiple holes Preferably the separation means consist of a mesh or net.

The permeable separation means 9 act at the support of chemically inert particles 3 acting eroding the existing anodic layer 12 on the surface 12 of the pieces to be polished 2.

The second glass or bowl 8 of container 5 comprises oscillation means 10 of the liquid or solution electrolytic 1. In the case represented in Figs. 1 to 3, said oscillation means 10 are constituted by a piston that is slide vertically inside this second glass 8, causing electrolyte solution 1 of container 5 to increase level in the first vessel 7 when said solution 1 passes through permeable separation means 9.

With the passage of electrolyte solution 1 of a glass to another, the formation of a fluidized bed 14 is possible of chemically inert particles 3 in the first vessel 7, the which are suspended as can be seen in the Figs. 2 and 3

In Fig. 2 it is represented with arrows vertical the direction of advance of the piston 10 and the part metallic to polish 2, while with a horizontal arrow it intends to detail the meaning of the electrolytic solution 1 when the plunger 10 descends through the second vessel 8.

The same arrow scheme is used in Fig. 3, where the direction of advance of the piston 10 has been reversed, which now it is recoil, and the anode or metal part to be polished 2 that It is also ascending. With this change of direction of movement from the plunger 10 a fraction of the solution is achieved electrolyte 1 return to the second vessel 8. This causes the compaction of chemically inert particles 3. Of this form maximum particle density 3 is reached around the metal parts 2 and with it, maximum friction of these with respect to the metal surface 13 to be polished.

With a device 4 for polishing items Metal 2 as described, which supports multiple variations without hence leaving the object of the invention, a polishing procedure by application of electric current between a cathode and an anode, the anode being the metal article 2 to polishing, which comprises at least one stage of interaction of said anode with chemically inert particles 3 larger than 100 microns

The procedure that is also removable from the Figs. 1 to 3 includes cycles in which a semi-period is followed interaction or immersion of the anode with electrolyte solution 1 free of inert particles 3 (See Fig. 1); and a half-period in the that the metallic article 2 to be polished or anode is in contact with a electrolytic solution 1 containing said suspension inert particles 3 (See Figs. 2 and 3).

Within the semi-period in which the anode is in contact with electrolyte solution 1 with particles Chemically inert 3 in suspension, two can be distinguished stages or phases: a first stage where the particles are fluidized and the anode is immersed in this fluidized bed 14; and a second stage where chemically inert particles 3 are compacted around the metallic article to be polished entering in contact with it in a more intimate way as detached from Fig. 3.

Finally, although it is not represented, after the stage of compacting the particles chemically inert 3 around the piece or metallic article 2 to be polished, it a semi-period occurs in which said article 2 is in contact with chemically free particle electrolyte solution 1 inert 3, situation analogous to that of Fig. 1.

The conjunction of an electrolyte solution 1 as described and the application of this polishing procedure it allows the polishing of articles 2 whose relief or geometry is relatively complex and present problems when treated by mechanical polishing methods or procedures, highlighting these problems excessive rounding of protruding corners, smoothing deficient in concavities 15, excessive treatment time or polishing, deformations, pitting, etc.

However, with electrolyte solution 1 and the process according to the invention, perfect polishing is achieved of roughness or roughness 11 of the order of up to tenths of micrometer, because the presence of at least one compound of the alkylbenzenesulfonic family of formula I, and more preferably the presence of at least one compound dialkylbenzenesulfonic with alkyl radicals of 10 to 14 atoms of carbon and at least one alkylbenzenesulfonic compound with a alkyl radical of 10 to 14 carbon atoms, enables formation of an anodic layer 12 around the metal article 2 to be polished which presents a supramolecular structuring.

A scheme where you can appreciate a detail of a metal article 2 with protuberances or roughness 11 that configures the anode of the reaction electrochemistry, surrounded by an anodic film or layer 12, represented by dashed lines that follow the profile of the metal 2 and representing the above supramolecular ordination of the electrolytic solution 1. Particles have also been represented Chemically inert 3 interacting with metal 2.

This anodic layer 12 with structuring supramolecular may have a stationary thickness of Order of tenths of a millimeter. In addition, it develops a resistivity electric greater than the rest of electrolyte 1 and a large mechanical susceptibility, so that in the semi-period in which article 2 to be polished is in contact with electrolyte solution 1 with chemically inert particles 3 in suspension, the latter tend to eliminate the anodic layer 12 by mechanical erosion and preferably, of the protuberant parts 11 of the relief to be polished, easily producing an effective displacement of the layer anodic 12 existing on said protuberances or roughnesses 11 towards adjacent spaces or concavities 15 below the same.

The formulation of the electrolytic solution 1 according to the invention facilitates the formation of anodic layers 12 which develop gradients, perpendicular to their thickness, of properties physical-electrical without continuity limit. To the occur this type of anodic layers 12, of thicknesses thereof order that the roughness 11 to level, you get a high roughness or roughness leveling efficiency 11 of very different order of magnitude.

Thus, as can be seen in Fig. 4 indicated with the arrows, when a chemically inert particle 3 interacts with the anodic structuring layer 12 supramolecular, the material or solution 1 near the tips protrusions 11 of the metal article 2 is displaced towards the adjacent sunken or concave areas 15. As the polishing procedure advances, more and more phenomena predominate which prevent direct contact of inert particles 3 with the metal surface 13. This is because the layers more viscous and close to the anode behave statistically as a boundary layer without turbulence, and therefore has a low renewal.

In this way, as it appears in Fig. 5, the final smoothing of the metal surface 13 is intermediate by said boundary layer, thereby smoothing the order of tenths of micrometer.

With the electrolytic solution 1 object of the invention are surprisingly fine polishing pieces Copper metal or its alloys.

This new electrolytic solution 1 allows the polishing metal parts 2 without the use of procedures strictly mechanical, and can also be smoothed in a single stage, reliefs of the order of tenths of millimeters thick, reaching roughness 11 end of the order of only tenths micrometer

Although in Figures 1 to 3 it is represented a device 4 for polishing metal articles comprising a container 5 in which at least two vessels 7 and 8 are distinguished, are equally applicable for polishing metal parts 2 4 devices that have more than two interconnected 7 and 8 vessels where at least one of them contains the particles chemically inert 3 and in such a way that they can be fluidized.

4 devices for polishing are also provided of metal articles 2 with electrolyte solution 1 of the invention where the oscillation means 1 are constituted by other alternative devices such as paddle stirrers or gas insufflation systems.

Obviously, it is also applicable to carry carry out the polishing process according to the invention, any device 4 in which it is an internal 7 or 8 cuvette or vessel with permeable bottom containing chemically inert particles 3, which is subject to relative movement with respect to the walls of the external container 5 in order to fluidize the bed of particles 3 during the half-period of the interaction stage of the anode with the latter.

Claims (14)

1. Electrolytic solution (1) for electrochemical polishing of metal articles (2) that constitute the anode in a polishing process by application of electric current, characterized in that it comprises at least one compound of the alkylbenzenesulfonic family of formula I,

         \ vskip1.000000 \ baselineskip
      

4

         \ vskip1.000000 \ baselineskip
      

its salts or derivatives, where R1 corresponds to an alkyl radical of 10 to 14 carbons; Y R2 is selected from a hydrogen atom and a radical rent from 10 to 14 carbons 2. Electrolytic solution (1) according to claim 1, characterized in that it comprises an alkylbenzenesulfonic compound of formula I wherein R1 is an alkyl radical of 10 to 14 carbon atoms and R2 is hydrogen; and an alkylbenzenesulfonic compound of formula I wherein R1 and R2 correspond to alkyl radicals of 10 to 14 carbon atoms. 3. Electrolytic solution (1) according to any one of claims 1 or 2, characterized in that the weight percentage of alkylbenzenesulfonic compound of formula I wherein R1 is an alkyl radical of 10 to 14 carbon atoms and R2 is hydrogen, is comprised between 2.0% and 4.0%. 4. Electrolytic solution (1) according to any one of claims 1 or 2, characterized in that the weight percentage of alkylbenzenesulfonic compound of formula I wherein R1 and R2 correspond to alkyl radicals of 10 to 14 carbon atoms, is between 10 , 0% and 17.0%. 5. Electrolytic solution (1) according to any one of the preceding claims, characterized in that it further comprises a hydrocarbon in a weight ratio with respect to the alkylbenzenesulfonic compound or compounds of formula I comprised between 15% and 75%. 6. Electrolytic solution (1) according to any one of the preceding claims, characterized in that it further comprises chemically inert particles (3). 7. Use of electrolyte solution (1) according to any one of claims 1 to 6 above in a metal polishing process by current application electric 8. Method of polishing metal articles (2) by applying electric current between an anode and a cathode, the anode being the metal article to be polished, characterized in that it comprises at least one interaction stage of said anode with chemically inert particles ( 3) larger than 100 microns. Method according to claim 8, characterized in that it comprises cycles in which a semi-period occurs in which the anode is in contact with the electrolytic solution (1) free of chemically inert particles (3) and a semi-period in which the anode It is in contact with an electrolytic solution that contains chemically inert particles in suspension. Method according to claim 9, characterized in that the semi-period in which the anode is in contact with an electrolytic solution (1) containing chemically inert particles (3) in suspension comprises, in turn, a fluidization stage of said ones. particles and a compaction stage of said particles
the. 11. Device (4) for polishing items of metal (2) by application of electric current between an anode and a cathode, the anode being the metal article to be polished, adapted to carry out the procedure according to any one of the claims 8 to 10 above. 12. Device (4) according to claim 11, characterized in that it comprises at least one container (5) divided by a vertical separation wall (6) defining two vessels (7,8) interconnected by its lower part, the first of them adapted to contain the anode of the electrochemical reaction and provided in its lower part with permeable separation means (9) to liquid solutions; and the second vessel provided with oscillation means (10) of the liquid contained therein. 13. Device (4) according to claim 12, characterized in that the separation means permeable (9) to liquid solutions consist of a plate provided with multiple holes. 14. Device according to claim 12, characterized in that the separation means permeable (9) to liquid solutions consist of a mesh.