KR20230113355A - Ruthenium alloy layers and layer combinations thereof - Google Patents

Abstract

Aqueous electrolyte for depositing ruthenium alloy layers on metal surfaces, in particular on non-metal surfaces, its use and corresponding electrolytic processes, and correspondingly produced layer sequences.

Description

Ruthenium alloy layers and layer combinations thereof

The present invention relates to an aqueous electrolyte for depositing ruthenium alloy layers on metal surfaces, particularly base metal surfaces. The invention also relates to the use of the electrolyte according to the invention for producing a ruthenium alloy layer on a corresponding surface by means of an electrolysis process, which is also the subject of the invention. Finally, the present invention also includes a layer sequence having a ruthenium alloy layer deposited in this way.

Consumer and professional items, jewelry and ornaments are finished with thin layers of oxidation-stable metals to protect them from corrosion or to enhance their appearance. These coatings must be mechanically stable and show no signs of discoloration or wear even after prolonged use. Proven means for producing such layers include galvanic processes that can be used to obtain layers of various metals and alloys in high quality form. Well-known examples from everyday life are layers of galvanic bronze and brass on doorknobs or handles, chrome coating on automobile parts, and gold coating on galvanized tools or watch straps.

In this regard, galvanic palladium deposits and palladium alloy deposits have been known for a long time. Because of its bright color, excellent electrical properties, hardness, contact resistance, corrosion resistance and stability, palladium is often used as a coating for, for example, electrical plug-in connections, printed circuit boards, decorative applications and many other industrial and commercial applications. As a substitute for gold and platinum, palladium has provided an economical and cost-effective alternative because of its wide range of applications. Alloys of palladium with base metals such as nickel or cobalt are more cost-effective than pure precious metals, so these alloys have been and continue to be used for a long time. Coatings of these palladium alloys are often produced by galvanic deposition from a palladium alloy electrolyte.

Today, due to the rapid rise in the price of palladium, there is a search for cheaper alternatives that do not use palladium and retain the same properties. In this regard, the interest of the person skilled in the art is directed, among other things, to the use of substantially cheaper ruthenium.

The ruthenium baths and processes described in the prior art often refer to the deposition of black ruthenium and ruthenium alloy layers and may contain compounds of toxicological concern such as thio compounds as blackening additives (eg DE 102011105207 B4 and publications cited therein). Often, due to their acidic nature, these baths allow deposition only on metals with relatively noble metal properties (eg DE 1959907 A1).

According to US 4082625, bright ruthenium deposits in the basic range are also obtainable. A process for the deposition of ruthenium operating in the pH range of 9 to 10 is disclosed. Ruthenium is maintained in solution in this pH range by complexing anions (EDTA, NTA, CDTA). A stable and bright ruthenium precipitate is obtained.

Nitridochloro complexes of ruthenium can be used in aqueous non-acidic baths for the electrodeposition of ruthenium. This method is disclosed in US 4297178. It also contains oxalic acid or oxalate anions. According to the method, only pure ruthenium deposits are produced, but these deposits cannot replace palladium and palladium alloy deposits of this type without causing disadvantages.

Ruthenium deposits are mentioned, for example, in US 3692641 or GB 2101633. In the former, deposits of ruthenium, especially with other noble metals, are promoted. In the latter, ruthenium alloy deposits in acidic environments are referred to.

WO 18142430 A1 discloses the production of ruthenium or ruthenium alloy deposits of various colors, in particular using metals such as Ni, Co, Cu, Sn and the like. It is stated that deposition on non-metallic subsurfaces is possible. However, only strong acid electrolytes are presented here, which is why successful direct deposition on such subsurfaces is certainly not possible.

Means to successfully prevent palladium-containing layers in electrolytic deposition are still being sought. To this end, the replacement layer should have properties as similar as possible to the palladium-containing layer. This should apply in particular with respect to appearance, corrosion resistance, wear resistance and crack formation properties. It should additionally be possible to deposit suitable layers on non-metallic surfaces to replace the Pd-strike deposits often used for this purpose. Also, replacing palladium should of course result in cost savings.

These and further objects, obvious to a person skilled in the art, are achieved by the disclosure of an electrolyte according to claim 1 herein. Claims 2 to 7 relate to preferred configurations of the electrolyte according to the present invention. Claims 8, 12 and 15, together with corresponding dependent claims, respectively relate to the use of electrolytes, methods for electrolytic deposition from electrolytes and layer sequences obtainable therefrom.

As an aqueous electrolyte for depositing ruthenium alloys on metal surfaces, in particular non-metal surfaces,

a) Formula [Ru ₂ N(H ₂ O) ₂ X ₈ ] ^3- , at a concentration of 0.5 to 20 g/L, based on ruthenium as metal, where X is one or more single or multiple negatively charged counterions, e.g. , ruthenium as a bicyclic anionic ruthenium nitrido complex compound of a halide ion, hydroxide ion or other anionic ligand (eg sulfate, phosphate, oxalate, citrate);

b) at least one alloy selected from the group consisting of Cu, W, Fe, Co, Ni, In, Zn, Sn, Pd, Pt, dissolved in ionic form, each having a concentration of 0.5 to 10 g/L, based on said metal; metal;

c) at least one anion of a di-, tri-, or tetracarboxylic acid at a concentration of 0.05 to 2 mol/L;

d) at least one anionic surfactant, at a concentration of 0.1 to 500 mg/L

By using an aqueous electrolyte comprising <RTI ID=0.0>a pH</RTI> The electrolytes presented herein can be used to deposit layers of ruthenium alloys that are similar in color to palladium deposits, have high corrosion resistance, low cracking propensity, and high hardness and high wear resistance.

Ruthenium is preferably a water-soluble, known to those skilled in the art as bicyclic anionic nitridohalogeno complex compounds of the formula [Ru ₂ N(H ₂ O) ₂ X ₈ ] ^3- , where X is a halide ion. used in compound form. In this connection, the chlorocomplex [Ru ₂ N(H ₂ O) ₂ Cl ₈ ] ^3- is particularly preferred. The amount of the complex compound in the electrolyte according to the present invention may preferably be selected such that the ruthenium concentration calculated as ruthenium metal after the compound is completely dissolved is 1 to 20 g per liter of electrolyte. The finished electrolyte particularly preferably contains from 1 to 10 g of ruthenium per liter of electrolyte, very particularly preferably from 3 to 7 g of ruthenium per liter of electrolyte.

Electrolytes contain certain organic compounds with one or more carboxylic acid groups. In particular it is a di-, tri- or tetracarboxylic acid. This is well known to the person skilled in the art and can be found, for example, in Beyer-Walter, Lehrbuch der Organischen Chemie, 22nd Edition, S. Hirzel-Verlag, pp. 324 et seqq. In this regard, acids selected from the group consisting of oxalic acid, citric acid, tartaric acid, succinic acid, maleic acid, glutaric acid, adipic acid, malonic acid and malic acid are particularly preferred. In this regard, oxalic acid is particularly preferred. Acids naturally exist in anionic form in the electrolyte at a set pH value. The carboxylic acids mentioned herein are added to the electrolyte in concentrations between 0.05 and 2 mol/L, preferably between 0.1 and 1 mol/L, and very particularly preferably between 0.2 mol/L and 0.5 mol/L. This applies in particular to the use of oxalic acid, which is presumed to also act as a conductive salt in the electrolyte.

In the electrolyte according to the present invention, anionic surfactants are used as wetting agents. These are, for example, selected from the group consisting of fatty alcohol sulfates, alkyl sulfates, alkyl sulfonates, aryl sulfonates, alkylaryl sulfonates, heteroaryl sulfates and salts thereof, especially alkoxylated derivatives thereof (Kanani, N: Galvanotechnik; Hanser Verlag, Munich Vienna, 2000; pp. 84 et seqq.). Ethoxylated sodium fatty alcohol (C12-C14) ether sulfate or sodium fatty alcohol sulfate (C12-C14) is particularly preferred.

The pH value of the electrolyte is preferably in the slightly acidic to slightly alkaline range. According to the present invention, the pH value is set in the range between 5 and 10. More preferably, the pH value of the electrolyte when used is between 6 and 9, particularly preferably between 7 and 8. Most preferably, a pH value of about 7.5 is set. By adding a buffer substance, the pH value is kept constant during electrolysis. This is well known to those skilled in the art (Handbook of Chemistry and Physics, CRC Press, 66th Edition, D-144 et seqq.). Preferred buffer systems are borate, phosphate and carbonate buffers. The compound for preparation of the buffer system may be selected from the group consisting of boric acid, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, potassium hydrogen carbonate or dipotassium carbonate. The buffer system is used at a concentration of 0.08 to 1.15 mol/L, preferably 0.15 to 0.65 mol/L and very particularly preferably 0.2 to 0.4 mol/L (anion basis).

Of course, additional materials advantageous to deposition may be added to the electrolytes discussed herein. This is well known to those skilled in the art. It is preferably selected from the group consisting of conductive salts and brighteners (Praktische Galvanotechnik, 5th Edition, Eugen G. Leuze Verlag, Bad Saulgau, Germany, pp. 39 et seqq.). A conductive salt selected from the group consisting of alkali sulfate, ammonium sulfate, ammonium chloride and ammonium oxalate is preferred.

Besides ruthenium, other dissolved metals are also present in the electrolyte. It is electrolytically deposited with ruthenium as a ruthenium alloy layer. It is suitably selected from the group consisting of Cu, W, Fe, Co, Ni, In, Zn, Sn, Pd and Pt. It is usually dissolved in the electrolyte as a salt, especially as a sulfate. In this regard, it is particularly preferred that the alloying metal is selected from the group of Ni, Sn, Zn, Co, Pd. Ni is most preferably used. The alloying metal is present in the electrolyte in concentrations of 0.1 to 10 g/L in each case. The concentration of the alloying metal is preferably 1 to 6 g/L, very particularly preferably 2 to 5 g/L. In particular, it has been found to help improve the corrosion resistance and cracking tendency of the ruthenium layer. In particular, Ni showed good results in this regard.

The electrolyte of the present invention may contain sulfur-containing compounds, such as wetting agents or surfactants specified above. However, it is advantageous if the electrolyte does not contain sulfur-containing compounds in which sulfur exists in an oxidation state of +4 or greater. In particular, blackening additives based on sulfur compounds are not present in the electrolyte according to the invention.

The electrolytes of the present invention do not produce black or dark anthracite deposits and produce grayish metallic deposits. It is therefore similar in appearance to Pd and Pd alloy deposits that must be replaced. The deposited alloy metal layer advantageously has an L* value of 65 or greater. According to the Cielab color system (EN ISO 11664-4 - the latest version as of the filing date), the a* value is preferably -3 to +3 and the b* value is -7 to +7.

In addition, the present invention includes at least one of ruthenium metal and an alloy metal selected from the group consisting of Cu, W, Fe, Co, Ni, In, Zn, Sn, Pd, and Pt dissolved in ionic form, and an alloy The metal layer relates to the use of the aforementioned electrolyte having corrosion resistance similar to that of the corresponding palladium-containing layer, for producing articles having an alloy metal layer electrolytically deposited on a metal surface, in particular a non-metal surface. The addition of the listed metals significantly reduces the cracking tendency during electrolytic deposition compared to pure ruthenium deposits. Cracking tendency is preferably determined by visual inspection under an optical microscope at 20× magnification. Precious metal sublayers onto which a ruthenium alloy layer can be deposited are known to those skilled in the art. According to the present invention, non-metallic surfaces are unstable and tend to dissolve in acidic or more basic environments. Preferred non-metallic layers for the ruthenium alloy layer are those selected from the group of copper, copper alloys, nickel, or nickel alloys.

The ruthenium alloy layer obtainable using the electrolyte according to the present invention may have a thickness specified by a person skilled in the art. The thickness of the alloy metal layer is preferably 0.05 to 5 μm, more preferably 0.05 to 2 μm and very preferably 0.05 to 1 μm. With further preference, the alloy metal layer is used as a sublayer for a further metal layer to be electrolytically deposited, as is the case for example with a Pd layer or a Pd-Ni layer. The metal layer deposited on the ruthenium alloy layer may consist of a noble metal, for example Ag, Au, Pt, Rh or an alloy thereof, generally 0.03 to 10 μm, preferably 0.05 to 3 μm, very preferred. It has a thickness of 0.1 to 1 μm.

The metal deposits discussed herein (both for the ruthenium alloy layers themselves and for the layer sequences) have very high wear resistance, which has been found to be particularly advantageous (eg as a contact material) in the jewelry and professional applications. In the so-called Bosch-Weinmann test (Bosch-Weinmann, A. M. Erichsen GmbH, Publication 317/D-V/63, or Weinmann K., Farbe und Lack 65 (1959), pp. 647-651), the present invention Metallic deposits of ruthenium alloys with electrolytes according to achieve values of less than 0.25 μm per 1000 strokes. Further advantageously, even less than 0.1 μm per 1000 strokes and very advantageously less than 0.08 μm per 1000 strokes are within the feasible range. For such wear-resistant metal deposits, the composition of the ruthenium alloy layer is very preferably from 95:5 to 80:20, most preferably from 90:10 to 80:20, based on the weight ratio of ruthenium to other metal(s). .

The present invention also provides a method for depositing an alloy metal layer on a metal surface, in particular a non-metal surface, comprising:

a) contacting the metal surface cathodically with the aqueous electrolyte described above;

b) contacting the anode with an electrolyte; and

c) establishing sufficient current flow between the cathode and anode;

Including, it relates to a method.

It should be noted that the embodiments described as preferred for the electrolyte and its use also apply mutatis mutandis to the processes mentioned herein. The current density formed in the electrolyte between the cathode and anode during the deposition process can be selected by one skilled in the art depending on the efficiency and quality of the deposition. Depending on the use and type of coating system, the current density in the electrolyte is advantageously set between 0.1 and 50 A/dm 2 . If necessary, the current density can be increased or decreased by adjusting system parameters such as design of the coating cell, flow rate, anode or cathode relationship, etc. A current density of 0.2 to 25 A/dm 2 is usually advantageous, 0.25 to 15 A/dm 2 is preferred, and 0.25 to 10 A/dm 2 is very particularly preferred. Most preferably, the current density is 0.25 to 5 A/dm 2 . The selected current density value is determined by the type of coating process. In a drum coating process, the preferred current density herein is between 0.25 A/dm 2 and 5 A/dm 2 . In a rack coating process, a current density of 0.5 to 10 A/dm 2 gives better results.

Typically, thin layer thicknesses in the range of 0.1 to 0.3 μm are produced in rack operation. Low current densities in the range of 0.25 to 5 A/dm 2 are advantageously used herein. A further application of low current densities is for example drum or vibratory technology in the coating of contact pins. Here, a layer of approximately 0.25 to 0.5 μm thickness is applied in the current density range of 0.25 to 0.75 A/dm 2 . Layer thicknesses in the range of 0.1 to 1.0 μm are usually deposited in rack operations, mainly for decorative applications with current densities in the range of 0.25 to 5 A/dm 2 .

Instead of direct current, pulsed direct current may be applied. Thus, current flow is stopped for a period of time (pulse plating). In reverse pulse plating, the polarity of the electrode is reversed so that the coating is partially separated into the anode. By continuously alternating the anode separation with the cathode pulses, layer build-up is controlled. For example, applying simple pulse conditions such as 1 s current flow (t _on ) and 0.5 s pulse pause (t _off ) at moderate current densities produces more uniform coatings (Pulse-Plating, J.-C. Puippe , F. Leaman, Eugen G. Leuzeverlag, Bad Saulgau, 1990).

With the electrolyte according to the present invention, an insoluble anode can preferably be used. Preferred insoluble anodes are anodes made of a material selected from the group consisting of titanium platinide, graphite, mixed metal oxides, glassy carbon anodes, and special carbon materials ("diamond-like carbon," DLC), or combinations of these anodes. there is An insoluble anode of platinum coated titanium or titanium coated with a mixed metal oxide is advantageous, the mixed metal oxide being preferably selected from iridium oxide, ruthenium oxide, tantalum oxide and mixtures thereof. Iridium-transition metal mixed oxide anodes composed of iridium-ruthenium mixed oxide, iridium-ruthenium-titanium mixed oxide, or iridium-tantalum mixed oxide are also advantageously used in the practice of the present invention. More information can be found in Cobley, A.J et al., The use of insoluble anodes in acid sulphate copper electrodeposition solutions, Trans IMF, 2001,79(3), pp. 113 and 114.

The deposition of a ruthenium alloy layer on a metallic object, in particular a non-metallic object, according to the present invention can be carried out taking into account the above, for example as follows:

For galvanic application, the jewellery, ornament, consumer product or specialty item to be coated (collectively referred to as the substrate) is immersed in the electrolyte according to the present invention. This forms the cathode. For example, an anode made of platinum platinide (product information - PLATINODE ^® from Umicore Galvanotechnik GmbH) is also immersed in the electrolyte. Proper current flow is then ensured between the anode and cathode. A maximum current density of 10 amperes per square decimeter [A/dm 2 ] has proven advantageous for obtaining a highly adhesive and uniform layer.

The temperature of the electrolyte during deposition can be appropriately set by a person skilled in the art. Advantageously, the temperature range to be set is between 20 and 80°C. It is preferably set to a temperature of 50 to 75°C, particularly preferably 60 to 70°C. It may be advantageous if the electrolyte under consideration is agitated during deposition.

Suitable substrate materials advantageously used herein include copper base materials such as pure copper, brass or bronze; ferrous materials such as, for example, iron or stainless steel; nickel, gold and silver. The substrate material may be a multilayer system that is galvanically coated or coated using other coating techniques. For example, it applies to printed circuit board base materials or ferrous materials that have been nickel-plated or copper-plated and then optionally gold-plated or pre-silver coated. A further substrate material is, for example, a wax core previously coated with a silver conductive lacquer (so-called electroforming).

A further subject of the invention is an alloy metal layer electrolytically deposited on a metal surface, in particular a non-metallic surface, produced by the method according to the invention and having the thickness described above, and an electrolytically deposited layer on said layer, for example Ag, A metal layer sequence comprising a substrate provided with a metal layer formed of noble metals such as Au, Pt or Rh and their alloys and having the thickness described above. The thickness of the layer can vary within the preferred ranges specified above. The preferred embodiments described for the electrolyte, its use and method according to the present invention also apply to the layer sequences described herein with minor modifications only where necessary.

The ruthenium alloy layers described herein are suitable to replace expensive Pd layers or Pd alloy layers, particularly Pd-Ni layers. As the latter is advantageously used, the ruthenium alloy layers described herein may be a more cost effective alternative. In particular for jewelry products, a precious metal layer may be applied as a finish to the ruthenium alloy layer according to the present invention. In particular, rhodium, platinum, gold and silver are suitable as noble metals. A person skilled in the art knows how to carry out such finishing.

However, ruthenium alloy layers can also be established as replacements for Pd or Pd-Ni in electronically used products. Here, rhodium, rhodium alloys (eg RhRu), platinum, platinum alloys (PtRh, PtRu) or gold form the preferred top layer. A thin layer of palladium or palladium-nickel may also be applied as the top layer. The top layer to be applied and its thickness depend on the intended use and are known to those skilled in the art.

The present invention can preferably be used in drum and rack coating processes. Using the electrolytes described herein, it is possible to achieve crack-free, corrosion-resistant and wear-resistant deposits of ruthenium alloys on suitable substrates, which deposits are similar to Pd deposits. It is also possible to work with electrolytes in the neutral range, which for the first time allows ruthenium alloy coatings to be deposited on base metals without the need to first provide a noble metal intermediate layer on base metals. Considering the known prior art, this was by no means obvious.

Example:

One liter of the electrolyte specified in each exemplary embodiment is heated with a magnetic stirrer to the temperature specified in the exemplary embodiment while stirring with a 60 mm long cylindrical magnetic stir bar at at least 200 rpm. This agitation and temperature are maintained during coating.

After reaching the desired temperature, the pH value of the electrolyte is set to the value specified in the exemplary embodiment using KOH solution (c = 0.5 g/ml) and sulfuric acid (c = 25%).

An expanded metal section made of titanium platinide serves as the anode.

A mechanically polished brass plate with a surface area of at least 0.2 dm2 serves as the cathode. It may be pre-coated with at least 5 μm of nickel from the electrolyte to create a high gloss layer. A gold layer approximately 0.1 μm thick may also be deposited on the nickel layer.

Before introduction into the electrolyte, these cathodes are cleaned with the aid of electrolytic degreasing (5-7 V) and with the aid of an acid dip containing sulfuric acid (c = 5% sulfuric acid). Between each cleaning step and before introduction into the electrolyte, the cathode is cleaned. Rinse with deionized water.

The cathode is located in the electrolyte between the anodes and moves in parallel at more than 5 cm/sec. The distance between the anode and cathode should not change.

In the electrolyte, the cathode is coated by applying a direct current between the anode and cathode. The current strength is chosen such that at least 0.5 A/dm 2 is achieved over the surface area. Higher current densities can be selected if the electrolyte specified in the application examples is intended to produce a layer that can be used for technical and decorative purposes.

The duration of the current flow is selected such that a layer thickness of at least 0.5 to 1 μm is achieved on average over the surface area. If the electrolytes specified in the application examples are intended to create layers that can be used for technical and decorative purposes, higher layer thicknesses can be produced.

After coating, the cathode is removed from the electrolyte and rinsed with deionized water.

Drying of the cathode may occur via compressed air, hot air, or centrifugation.

The surface area of the cathode, the level and duration of the applied current, and the weight of the cathode before and after coating are recorded and used to determine the average layer thickness and deposition efficiency.

Claims (15)

As an aqueous electrolyte for depositing ruthenium alloys on metal surfaces, in particular base metal surfaces,
a) Bi of the formula [Ru ₂ N(H ₂ O) ₂ X ₈ ] ^3- , where X is one or more single or multiple negatively charged counterions, at a concentration of 0.5 to 20 g/L, based on ruthenium as metal; ruthenium as a cyclic anionic ruthenium nitrido complex compound;
b) one or more dissolved in ionic form selected from the group consisting of Cu, W, Fe, Co, Ni, In, Zn, Sn, Pd, Pt, each having a concentration of 0.1 to 10 g/L based on the metal; alloy metal;
c) at least one anion of a di-, tri-, or tetracarboxylic acid at a concentration of 0.05 to 2 mol/L;
d) at least one anionic surfactant, at a concentration of 0.1 to 500 mg/L
and having a pH of 5.0 to 10.0. The electrolyte according to claim 1, wherein the carboxylic acid is selected from the group consisting of oxalic acid, citric acid, tartaric acid, succinic acid, maleic acid, glutaric acid, adipic acid, malonic acid, and malic acid. 3. The method of claim 1 or 2, wherein the surfactant is selected from the group consisting of fatty alcohol sulfates, alkyl sulfates, alkyl sulfonates, aryl sulfonates, alkylaryl sulfonates, heteroaryl sulfate salts thereof and alkoxylated derivatives thereof. characterized by electrolytes. 4. Electrolyte according to any one of claims 1 to 3, characterized in that the pH value of the electrolyte ranges from 7 to 8. 5. Electrolyte according to any one of claims 1 to 4, characterized in that the electrolyte has a buffer system selected from the group consisting of borate, phosphate and carbonate buffers. 6. The electrolyte according to any one of claims 1 to 5, characterized in that the alloying metal is selected from the group consisting of Ni, Pd, Pt, Sn, Zn and Co. 7. Electrolyte according to any one of claims 1 to 6, characterized in that it does not contain sulfur-containing compounds in which sulfur is present in an oxidation state of +4 or higher. Claims 1 to 7 comprising at least one of ruthenium metal and an alloy metal selected from the group consisting of Cu, W, Fe, Co, Ni, In, Zn, Sn, Pd, Pt dissolved in ionic form. Use of an aqueous electrolyte according to any one of the preceding claims for the manufacture of articles having an alloy metal layer electrolytically deposited on a metal surface, in particular a non-metal surface. The use according to claim 7, wherein the thickness of the alloy metal layer is 0.05 to 5 μm. 10. Use according to claim 8 or 9, characterized in that the alloy metal layer is for a further electrolytically deposited metal layer of noble metal or its alloy and serves as a sublayer with a thickness of 0.05 to 5 μm. 11. Use according to any one of claims 8 to 10, characterized in that the metal layer(s) produced has a wear resistance of less than 0.25 μm per 1000 strokes (in the Bosch-Weinman test). A method for the electrolytic deposition of an alloy metal layer on a metal surface, in particular a non-metal surface, comprising:
a) contacting the metal surface cathodically with an aqueous electrolyte according to any one of claims 1 to 7;
b) contacting an anode with the electrolyte; and
c) establishing sufficient current flow between the cathode and the anode;
Including, method. 13. The method according to claim 12, characterized in that the current density in the electrolyte is from 0.1 to 50.0 A/dm2. 14. Method according to claim 12 or 13, characterized in that the temperature during the electrolysis is between 20 °C and 80 °C. A metal layer sequence comprising a substrate provided with a metal surface, in particular a non-metal surface, an alloy metal layer electrolytically deposited and produced by the method according to claims 12 to 14.