EP3067444A2 - Separation of decorative palladium iron alloy coatings on metallic substances - Google Patents

Abstract

The invention relates to an electrolytic bath for the cathodic deposition of binary alloys and / or layer sequences with the formation of white, corrosion-resistant, crack-free and (high) glossy coatings on at least metallic or electrically conductive or conductively coated objects on their surface, which bath is composed of alloying metals at least one palladium compound, in particular a palladium salt, as a primary metal and at least one iron compound, in particular an iron salt as a secondary metal. The invention is characterized in that it is - for the deposition of a Pd / Fe alloy containing 5-15% by weight of Fe - as an aqueous, alkaline solution, in particular having a pH of 7.5 to 9, is present and in addition to the metal compounds, as an essential further component at least one wetting agent, in particular from the group of amphoteric surfactants, and additionally at least one of the additives contained in galvanic palladium in the usual way brightener and conductive salts, in particular pH stabilizers and in particular stress reducer contains, wherein the Electrolyte bath is free of ammonia and ammonium compounds.

Description

The present invention is directed to an electrolytic bath composition for depositing white, high-gloss, crack-free, abrasion and corrosion-resistant palladium-iron alloys from alkaline aqueous baths, objects and articles coated with these alloys, and a process for producing the coated objects Items.

Methods for the deposition of palladium-iron alloys from aqueous alkaline electrolytes are known from the AiF research project No. 10302 N of the Research Institute for Precious Metals and Metal Chemistry Schwäbisch Gmünd, "Galvanic deposition of palladium-iron alloy coatings for functional applications and their characterization". However, with the electrolyte described there, no high-gloss alloys could be deposited under the conditions described there. In addition, the electrolyte described is based on ammonium salts, the pH is adjusted with ammonia. At electrolyte temperatures of 55 ° C, therefore, ammonia must be constantly replenished in order to keep the pH constant, and in addition there are enormous odor and health nuisances for the operators of such baths.

The electrolytes are out JP, 2001-192885 A, are also based on ammonium salts and contain additional brighteners and possibly different alloying metals such as iron or tellurium.

JP, 2001-181887 A describes palladium-iron alloy baths which are also based on ammonium salts and additionally contain EDTA. However, strong chelating agents are generally undesirable in electrolytes since they introduce difficulties in wastewater treatment.

JP, 10-046384 A describes palladium alloy baths for the electronics industry. Iron as alloying metal is mentioned, the electrolytes are based on ammonium salts. The examples, however, relate only to palladium-cobalt alloys. Alloys of palladium-iron, palladium-nickel, palladium-rhodium and palladium-ruthenium should be produced in the same way.

DE2657925 describes ammonia-free, semi-glossy to bright palladium and palladium alloy baths for electrical engineering, but iron is not mentioned as alloying metal.

It is the object of the present invention to develop baths from which high gloss, binary palladium-iron alloys can be deposited without any addition of other metals and. In particular, the alloy baths during operation should not present an odor nuisance or health hazard through the release of irritating gases or vapors, and moreover contain no strong complexing agents such as EDTA or NTA, which would cause problems in wastewater treatment.
In addition, the production is to be cheapened by the use of such alloy baths, and resources of the expensive palladium are spared.
A cost saving of about 15% when using such alloy baths in comparison to pure palladium baths results on the one hand from the lower density of the deposited palladium-iron alloy, on the other hand from lower Ausleppungsverlusten of precious metal, since pure palladium baths usually about with a palladium concentration of 10 g / l Palladium work, but the palladium-iron alloy bath of the present invention can get by with about half the concentration.

Such alloys are therefore particularly well suited for any metallic white decorative coating, e.g. of costume jewelery, but also for industrial applications, especially in the electronics industry.

In the present invention, the baths contain 0.5-15 g / l of palladium, 0.2-2 g / l of iron, conductive salts, brighteners and wetting agents. It is possible to deposit layer thicknesses> 5 μ high-gloss, crack-free. The corrosion resistance is comparable to pure palladium, the abrasion resistance is better than pure palladium.

The invention relates to a novel electrolyte bath for the cathodic deposition of binary alloys and / or layer sequences to form white, corrosion-resistant, crack-free and high-gloss coatings on at least on their surface metallic or electrically conductive or conductive coated objects, which bath as electrolyte at least one complex Palladium compound and at least one iron salt, and characterized in that it - for the deposition of a PdFe alloy containing 5-15 wt .-% Fe - as aqueous, alkaline solution is present and in addition to containing as metal compounds, as a further essential component at least one wetting agent from the group of amphoteric surfactants and additionally at least one of the additives contained in galvanic palladium in the usual manner brightener and conductive salts, pH stabilizers and stress reducer.

The pH of the new alloy bath should be maintained in the range of 7.5 - 9, since at lower pH values (approximately between 7 and 7.5) the incorporation rates of iron decrease. At higher pH values (approximately between 9 and 10), burns occur in the high current density range. The pH is advantageously adjusted by means of sodium or potassium hydroxide.

According to the present invention, the iron content of the deposited alloy at 5-15 wt .-% Fe, since at incorporation rates> 15 wt .- Fe Fe the layers are cracked, and at incorporation rates <5% by weight, the deposition receives a milky appearance.

For the purposes of the present invention, it has proven advantageous to use palladium in divalent form, e.g. as palladium chloride, sulfate, nitrate, and iron as the ferric salt, e.g. be present as sulfate, chloride, nitrate or citrate in the electrolyte bath.

Accordingly, an electrolyte bath is advantageously provided for the deposition of a coating, which is characterized in that it has a content of palladium of 0.5 to 15 g / l, preferably from 2 to 8 g / l, and particularly preferably from 4 to 6 g / l, and iron of 0.2 to 2 g / l, preferably from 0.5 to 1.5 g / l.

The wetting agents essential to the extraordinary properties of the novel alloy coatings, in particular from the group of amphoteric surfactants, e.g. Betaine and sulfobetaines are advantageously added to the electrolyte in amounts of 0.5-2 g / l.

As for other components of the new electrolyte bath than the essential metal compounds and wetting agents, it has proven to be advantageous if it contains brighteners. Such brighteners for palladium baths are known and come for example from the group of substituted aromatic N-heterocycles. It has also proved to be advantageous if the electrolyte contains stress reducers such as saccharin or organic sulfonates.

Also included are conductive salts and pH stabilizers such as sodium or potassium sulfate, nitrate, chloride, citrate, tartrate or malonate, and possibly further surface-active or wetting agents, for example alkyl ether sulfonates, alkyl ether phosphates or fatty alcohol alkoxylates.

All conductive salts or pH stabilizers used in the invention are sodium or potassium salts. When using ammonia or ammonium salts at elevated temperatures of about 50 ° C, ammonia is constantly expelled. As a result, the pH of the bath constantly adjusted and continuous work is much more difficult. In addition, there is a constant odor nuisance and health hazard for the operator of the electrolyte.

Furthermore, in the electrolyte of the present invention, no organic acids or salts are used which, when the bath is heated at elevated temperature, release vapors which can lead to an odor nuisance and / or health hazard to the operators of the electrolyte, e.g. Propionic acid / propionates, acetic acid / acetates.

The various advantageous electrolyte baths according to the invention or used according to the invention are described in detail in claims 2 to 5.

Another very important object of the invention are objects or articles, in particular jewelery or decorative articles, and further electro-technical or electronic components and components of a preferably physiologically acceptable metal, in particular brass, zinc, tin, iron or steel, or from alloys thereof or else from a conductive plastic with a coating of a binary alloy of palladium and iron deposited from an abovementioned electrolyte bath, in which the iron content is from 5 to 12% by weight, to which in particular reference is made to claim 7 becomes.

As far as the total thickness of the binary palladium-iron coating to be achieved in the context of the invention is concerned, it is 0.1 to 5 μm, in particular about 0.5 to 3 μm, depending on the field of use.

It can - see in particular claims 6 to 14 - further be provided that on the outside of the palladium-iron coating on the same adherent another, electrodeposited final layer of gold and / or other precious metal, such as in particular rhodium, platinum, ruthenium or of an alloy from the same, is arranged, by which the already high usability and gloss of the coating is still increased.

For further improvements of the new coatings of the new objects or articles may further be provided that on the palladium-iron coating on the same adherent, electrodeposited intermediate layer of adhesive gold is disposed, and on this an electrodeposited, adherent final layer of gold and / or of another noble metal, in particular rhodium, platinum, ruthenium or an alloy of the same.

Usually it is ensured that the intermediate layer of adhesive gold has a thickness of 0.05 to 0.3 microns.

Finally, the ultimate possibility is that the new objects or articles will have a final layer of one with rhodium and ruthenium, preferably in the weight% ratio of (70 to 90) to (30 to 10), especially about 80 to 20 , formed alloy.

It is the object of the present invention to adjust the concentration of the metal salts, wetting agents, brighteners and the additional ingredients in the mold and to vary within the weight ratios according to the invention so that the electrolyte solution is clear and remains, so that no metal salts precipitate, and that just according to the invention desired, shiny, adherent, crack-free, abrasion and corrosion resistant layers or coatings are deposited.

In the course of the process for electrolytic application of the new binary palladium-iron alloys to the respective base materials to be coated objects, objects or articles are immersed in the respective inventive electrolyte bath and switched there as a cathode.

The working temperature of the electrolyte baths according to the invention is between 35 and 75 ° C. The current density can be set to between 0.01 and 10 amps / dm ² , depending on the type of coating system.

Thus, in drum coating processes, current densities between 0.05 and 0.50 A / dm ^{2 are} particularly preferred. In rack coating processes, preference is given to choosing current densities between 0.2 and 10 A / dm ² , particularly preferably 0.2 to 5 A / dm ² .

When using the electrolyte baths according to the invention, various insoluble anodes can be used.

As such insoluble anodes, those made of a material selected from the group consisting of platinized titanium and iridium-transition metal mixed oxide or combinations of these materials are preferably used. Particular preference is given to using platinized titanium anodes.

• Auf einem jeweiligen Grundmaterial, beispielsweise bestehend aus Messing, Zink, Eisen, Stahl bzw. deren Legierungen oder auch anderen zumindest auf ihrer Oberfläche leitfähig gemachten Materialien wird entweder direkt oder auf eine dort vorher aufgebrachte Kupfer- Unterschicht, abgeschieden aus cyanidischen oder nicht cyanidischen alkalischen und/oder aus sauren Kupferbädern, wird entweder direkt oder auf dort aufgebrachte Cu/Sn/Zn-Legierung aus cyanidischen Brozebädern die neue binäre Palladium-Eisen-Legierung abgeschieden.

The production of the objects or articles coated according to the invention is usually carried out as follows:

• On a respective base material, for example made of brass, zinc, iron, steel or their alloys or other materials made conductive at least on its surface is either directly or on a previously applied there copper undercoat, deposited from cyanide or non-cyanide alkaline and or from acidic copper baths, the new binary palladium-iron alloy is deposited either directly or on Cu / Sn / Zn alloy of cyanidic broze baths applied there.

This palladium-iron alloy can be either final or final layer, or further coated by methods known per se. Further z. B. intermediate or final coatings may, as mentioned above, gold-containing or other noble metal-containing layers, such as those of rhodium, platinum, ruthenium or their alloys.

From the prior art is - in addition to the documents already mentioned - known per se that palladium is used as a nickel substitute, as a diffusion barrier and as corrosion protection. In these products, the base material is first copper-plated, then coated with palladium and finally receives the desired finish by coating with gold, rhodium or other precious metals or their alloys.
In order to provide sufficient corrosion protection, a thickness of the palladium layer of about 0.5-5 microns is recommended. Usually a layer thickness of about 1 μm is considered sufficient.

According to the present invention, it has been found that the application of an equally thick palladium alloy layer leads to equally good corrosion results as are achieved in pure palladium-coated base materials, but the abrasion resistance is better. The cost savings alone is about 15% due to the lower density.

If one wants to produce the products particularly efficiently, one can deposit a rhodium-ruthenium alloy instead of a rhodium final layer. If, for example, an alloy in the ratio by weight of rhodium to ruthenium of 80:20 is deposited as the final layer, in addition to the savings in the intermediate layers mentioned above, 20% of the very expensive rhodium would be saved.

In detail, reference is made in particular to claims 6 to 14.

The invention further relates to a per se conventional method for cathodic deposition of the binary alloys according to the invention with an Fe content of 5-15% by weight on at least on their surface metallic or electrically conductive or conductive coated objects or articles using the electrolyte according to the invention according to claim 15.

The invention further relates to the use of the electrolyte bath according to the invention for the cathodic deposition of binary alloys on at least on their surface metallic or electrically conductive or conductive coated objects or articles according to claim 16.

Reference to the following, non-limiting examples, the invention is explained in more detail:

Example 1:

• 4 g/l Pd aus Pd-II-chlorid
• 0,6 g/l Fe aus Fe-III-sulfat
• 80 g/l Kaliumsulfat
• 40 g/l Zitronensäure
• 1 g/l Netzmittel PF (Betain, Produkt der Fa. Ing. W. Garhöfer GesmbH) 0,1 g/l Fettalkoholethoxylat
• 2 g/l Saccharin
• 2 ml/l Glanzmittel: "Brightener PF" (Gemisch substituierter aromatischer N-Heterocyclen, ,
• Produkt der Fa. Ing. W. Garhöfer GesmbH)
• pH-Wert: 8,0 eingestellt mittels KOH

electrolyte:

• 4 g / l Pd of Pd-II chloride
• 0.6 g / l Fe of Fe-III sulfate
• 80 g / l potassium sulfate
• 40 g / l citric acid
• 1 g / l wetting agent PF (betaine, product of the company Ing. W. Garhöfer GesmbH) 0.1 g / l fatty alcohol ethoxylate
• 2 g / l saccharin
• 2 ml / l brightener: Brightener PF (mixture of substituted aromatic N-heterocycles,
• Product of the company Ing. W. Garhöfer GesmbH)
• pH value: 8.0 adjusted by means of KOH

• Ein Schmuckrohling aus Messing wird in einem schwach alkalischen cyanidfreien Reiniger, "Entfettung 1018", Produkt der Fa. Ing. W. Garhöfer GesmbH) bei 25 °C 30 s lang bei 10 A/dm² elektrolytisch entfettet.

Layer sequence and its production:

• A brass jewelry blank is electrolytically degreased in a weakly alkaline cyanide-free cleaner, "degreasing 1018", product of the company Ing. W. Garhöfer GesmbH) at 25 ° C. for 30 seconds at 10 A / dm ² .

Subsequently, the jewelry blank is rinsed in deionized water, dekapiert in 5% sulfuric acid solution for 30 s and in an acidic copper bath with 50 g / l Cu and 60 g / l sulfuric acid ("IWG Cu 550", product of the company. Ing. Garhöfer GesmbH), 20 μm copper are deposited in a shiny, shiny finish at 4 A / dm ² and 25 ° C. The blank is rinsed again.

Then from a palladium-iron-Elektroytbad according to the present invention 2μm palladium-iron of the composition palladium: 90.3%, iron: 9.7%, at 50 ° C, and 1 A / dm ² within 10 minutes from the electrolyte bath deposited.

Finally, the galvanized jewelry was rinsed in deionized water and dried.

• Der auf diese Weise erhaltene, galvanisierte Schmuckteil bzw. dessen Oberfläche war weiß und hochglänzend.
• Die Weissheit gemessen nach CIELAB betrug L* = 85. (Reinpalladiumschichten haben eine Weissheit von L* = 87)

Optical assessment:

• The obtained in this way, galvanized jewelry part or its surface was white and high gloss.
• The whiteness measured according to CIELAB was L * = 85 (pure palladium layers have a whiteness of L * = 87)

• Die Korrosionsbeständigkeit des galvanisierten Schmuckteiles wurde nach DIN 50018, Prüfung im Kondenswasser-Wechselklima mit schwefeldioxidhaltiger Atmosphäre, Juni 1997, geprüft.

Corrosion resistance according to DIN 50018:

• The corrosion resistance of the galvanized decorative part was tested in accordance with DIN 50018, Testing in a condensed water climate with sulfur dioxide-containing atmosphere, June 1997.

The corrosion resistance of the palladium-iron alloy in comparison with a coating of a pure palladium electrolyte (Gapal TS, product of Garhöfer GesmbH), produced on the same base material in the SO ₂ test is equally good.

Abrasion resistance with Taser Abraser

In each case, a brass disc in the palladium-iron electrolyte of example 1 and a brass disc in a pure palladium electrolyte (Gapal TS, product of Garhöfer GesmbH) were coated with 2 .mu.m. Anschießend both discs were abraded. The pure palladium was rubbed much earlier than the palladium-iron alloy.

Examples 2:

• 4 g/l Pd aus Pd-II-chlorid
• 0,6 g/l Fe aus Fe-III-sulfat
• 80 g/l Kaliumsulfat
• 40 g/l Zitronensäure
• 1 g/l Netzmittel PF (Betain, Produkt der Fa. Ing. W. Garhöfer GesmbH)
• 0,1 g/l Fettalkoholethoxylat
• 2 g/l Saccharin
• 2 ml/l Glanzmittel: "Brightener PF" (Gemisch substituierter aromatischer N-Heterocyclen, ,
• Produkt der Fa. Ing. W. Garhöfer GesmbH)
• pH-Wert: 8,0 eingestellt mittels KOH

Electrolyte:

• 4 g / l Pd of Pd-II chloride
• 0.6 g / l Fe of Fe-III sulfate
• 80 g / l potassium sulfate
• 40 g / l citric acid
• 1 g / l wetting agent PF (betaine, product of the company Ing. W. Garhöfer GesmbH)
• 0.1 g / l fatty alcohol ethoxylate
• 2 g / l saccharin
• 2 ml / l brightener: Brightener PF (mixture of substituted aromatic N-heterocycles,
• Product of the company Ing. W. Garhöfer GesmbH)
• pH value: 8.0 adjusted by means of KOH

A jewelery blank made of die-cast zinc is electrolytically degreased in a weakly alkaline cyanide-free cleaner (degreasing 1018, product of the company Ing. W. Garhöfer GesmbH) at 25 ° C. for 30 seconds at 10 A / dm ² .

Subsequently, the jewelry blank is rinsed in deionized water and in an alkaline cyanide Vorkupferbad with 22 g / l Cu and 34 g / l KCN ("Cuproga", product of the company Ing. W. Garhöfer GesmbH) were 5 microns of copper at 1 A / dm ² and 50 ° C deposited.

The pre-coppered jewelry blank is then dekapiert in 5% sulfuric acid solution for 30 s and in an acidic copper bath with 50 g / l Cu and 60 g / l sulfuric acid ("IWG Cu 550", product of the company Ing. W. Garhöfer GesmbH) 15μm copper leveling and high gloss deposited at 4 A / dm ² and 25 ° C. The thus coppered part is rinsed and pre-immersed in a 10% KCN solution.

² μm of bronze alloy are then removed from the electrolyte within a period of 10 minutes from a bronze electrolytic bath (Weissbronze CT 15 LF, product of the company Ing. W. Garhöfer GesmbH) and then rinsed in deionized water and decanted in 5% sulfuric acid solution.

Then from a palladium-iron-Elektroytbad according to the present invention 2μm palladium-iron of the composition palladium: 90.3%, iron: 9.7%, at 50 ° C, and 1 A / dm ² within 10 minutes from the electrolyte bath deposited.

After renewed rinsing and acid immersion with 0.1 μm adhesive gold from a weakly acidic electrolyte with 2.5 g / l Au ("MC 218", product of the company Ing. W. Garhöfer GesmbH), the jewelery thus obtained is 1.5 A / dm ² and 35 ° C provided. Then rinsed thoroughly in demineralized water, dekapiert in 5% sulfuric acid solution and 0.2 .mu.m rhodium from an electrolyte with 2 g / l Rh and 50 g / l sulfuric acid ("rhodium C2", product of the company Ing. W. Garhöfer GesmbH) rhodinated at 3V and 35 ° C.

Finally, the galvanized part was rinsed in deionized water and dried.

• Der auf diese Weise erhaltene, galvanisierte Schmuckteil bzw. dessen Oberfläche war rein weiß und hochglänzend.

Optical assessment:

• The obtained in this way, galvanized jewelry or its surface was pure white and high gloss.

• Der galvanisierte Schmuckteil schnitt in den Korrosionstests gleich gut ab wie ein nach dem gleichen Verfahren, aber mit Reinpalladium beschichteter Schmuckteil.

Corrosion resistance according to DIN 50018:

• The galvanized part of the jewelry performed just as well in the corrosion tests as a jewelery part coated with pure palladium using the same process.

Claims (16)

Electrolytic bath for the cathodic deposition of binary alloys and / or layer sequences to form white, corrosion-resistant, crack-free and (high) glossy coatings on at least metallic or electrically conductive or conductive coated objects on their surface, which bath as alloying metals of at least one palladium compound, in particular a palladium salt, as a primary metal and at least one iron compound, in particular an iron salt as a secondary metal, and characterized in that it - for the deposition of a Pd / Fe alloy containing 5-15% by weight of Fe - as aqueous, alkaline Reactive solution, in particular having a pH of 7.5 to 9, and in addition to the metal compounds, as a further essential component at least one wetting agent, in particular from the group of amphoteric surfactants, and additionally at least one of the usual in galvanic palladium baths Way contained Eq and addition of conductive salts, in particular pH stabilizers and in particular voltage reducer, wherein the electrolyte bath is free of ammonia and ammonium compounds. Electrolyte bath according to claim 1, characterized in that it has a content of palladium of 0.5 to 15 g / l, preferably from 2 to 8 g / l, and particularly preferably from 4 to 6 g / l, and to iron of 0, 2 to 2 g / l, preferably from 0.5 to 1.5 g / l. Electrolyte bath according to one of claims 1 to 2, characterized in that the alloying metals contained therein palladium in divalent form, for example as palladium chloride, sulfate or nitrate, and iron as iron-III salt, for example as sulfate, chloride, nitrate or Citrate available. Electrolyte bath according to one of claims 1 to 3, characterized in that it contains as wetting agents from the group of amphoteric surfactants in particular betaines and sulfobetaines in amounts of 0.5-2 g / l. Electrolyte bath according to one of claims 1 to 4, characterized in that it contains brighteners from the group of substituted aromatic N-heterocycles, and / or stress reducers such as saccharin or organic sulfonates, and / or further conductive salts and / or pH stabilizers such as sodium or potassium sulfate, chloride, nitrate, citrate, tartrate, or malonate, and / or possibly others surfactants or wetting agents, for example alkyl ether sulfonates, alkyl ether phosphates or fatty alcohol alkoxylates. Objects or articles, in particular jewelery or decorative articles, as well as further electrotechnical or electronic components and components of a, preferably physiologically acceptable, metal, in particular of brass, zinc, tin, iron or steel, or of alloys thereof or of one conductive plastic, comprising a palladium and iron-based white coating deposited from an electrolyte bath according to any one of claims 1 to 6, characterized in that it is coated with a binary alloy of palladium and iron containing 5-15 wt .-% Fe, in particular 7-12 wt .-%, are provided. Objects or articles according to claim 6, characterized in that they are provided with a deposited from the electrolyte bath according to one of claims 1 to 5 white coating or with such a corrosion-resistant, crack-free, highly abrasion and adherent, shiny coating, wherein, preferably an alloy comprising 85 to 95% by weight of palladium and 5 to 15% by weight of iron is arranged on a metallic background layer located directly on the surface of the object or article and deposited there, preferably of copper. Objects or articles according to any one of claims 6 to 7, characterized in that they are provided with a deposited from the electrolyte bath according to any one of claims 1 to 5 white coating or with such a corrosion-resistant, crack-free, highly abrasion and adherent, shiny coating , wherein, preferably, an alloy with 88 to 93 wt .-% palladium and 7 to 12 wt .-% iron is arranged, preferably on a directly on the surface of the object or article metallic base layer, preferably made of copper. Objects or articles according to any one of claims 6 to 7, characterized in that they are provided with a deposited from the electrolyte bath according to any one of claims 1 to 5 white coating or with such a corrosion-resistant, crack-free, highly abrasion and adherent, shiny coating , wherein, preferably on a directly on the surface of the object or article metal substrate layer, preferably made of a Cu / Sn / Zn alloy, an alloy with 88 to 93 wt .-% palladium and 7 to 12 wt .-% iron is arranged. Objects or articles according to one of claims 6 to 9, characterized in that the total thickness of the binary palladium-iron coating - depending on the field of application - 0.1 to 5 .mu.m, in particular about 0.5 to 3 microns, is. Objects or articles according to any one of claims 6 to 10, characterized in that on their white palladium-iron coating on the same adherent another, electrolytically deposited final layer of gold and / or other precious metal, in particular of rhodium, platinum, Ruthenium or an alloy of these precious metals, is arranged. Objects or articles according to any one of claims 6 to 11, characterized in that on the white palladium-iron coating on the same adherent, electrodeposited thin intermediate layer adhesive gold and on this an electrodeposited, adherent final layer of gold and / or from a other noble metal, in particular rhodium, platinum, ruthenium or an alloy of these precious metals, is arranged. Objects or articles according to one of claims 6 to 12, characterized in that the intermediate layer of adhesive gold has a thickness of 0.05 to 0.3 microns. Objects or articles according to any one of claims 6 to 13, characterized in that they - instead of a 100% rhodium final layer - a final layer of one with rhodium and ruthenium, preferably in the weight ratio of (70 to 90 ) :( 30 to 10), in particular of about 80:20, have formed alloy. A process for the production of a white coating or with such a corrosion-resistant, crack-free, highly abrasion-resistant and adherent, glossy coating are provided, wherein, preferably on a on the surface of the object or article metallic substrate layer, in particular of copper, alloys, Objects or articles, in particular jewelery or decorative articles, as well as further electrotechnical or electronic components and components of a physiologically acceptable metal, in particular of brass, zinc, tin, iron or steel, or of alloys thereof or of a conductive equipped Plastic, characterized in that the objects or articles to be coated, optionally after a base coat with copper, by means of electrolysis in an electrolyte bath according to one of claims 1 to 5 at temperatures of 35 to 75 ° C and current densities of 0.1 to 10 A. / dm ² , in the case of a drum coating process at current densities of 0.2 to 10 A / dm ² , in particular from 0.2 to 5 A / dm ² , are subjected to electrolysis using at least one insoluble cathode. Use of an electrolytic bath according to any one of claims 1 to 5 for obtaining an object or article coated with a palladium-iron white alloy having an iron content of 5-15% by weight according to any one of claims 6 to 14.