EP3733930A1 - Coating system for deposition by means of electrodeposition on a blank - Google Patents

Abstract

The invention relates to a coating system for application by galvanic deposition to a blank, in particular a blank for a jewelry element, comprising a palladium-free, in particular noble-metal-free, rosebronze layer (1) facing the blank, the rosebronze layer (1) containing tin and copper, one on top of the A diffusion barrier layer (2) arranged on a rose bronze layer (1) and an outer rose gold layer (3) arranged on the diffusion barrier layer (2).

Description

The invention relates to a coating system for application to blanks, in particular blanks for decorative elements, the decorative elements having a rose gold-colored appearance. The present invention is further directed to a production method for producing this coating system, as well as to decorative or decorative elements coated with the coating system.

In recent years, rose gold has increasingly become a fashionable color for jewelry and costume jewelery. In the manufacture of costume jewelery, base raw parts made of brass, cast pewter, zinc, iron or steel are often coated with different layers until they have a noble appearance. It is important that the rose gold does not tarnish, i.e. that it is tarnish-resistant. Jewelry parts, especially rings, are exposed to relatively high mechanical stress, as we constantly attack and pick up something with our fingers. The jewelry parts are therefore scratched and rubbed off relatively quickly. It is therefore important for the quality of fashion jewelry to have a high level of abrasion resistance. Furthermore, the coating should not lead to undesirable reactions even with prolonged contact with the skin, such as occurs when wearing jewelry.

Various coating systems are known from the prior art.

For example, in the WO 2018/146623 Bronze alloys are provided that have a yellow to pink hue. These alloys contain palladium (Pd), whereby the palladium content of the alloy for stainless steel tints varies from 25 - 45%. The layer thickness is specified as 0.35 - 1.5 µm. The ones in the WO 2018/146623 disclosed alloys with a pink hue have colorimetric coordinates of L * = 78 - 82 in the CIELAB color space; a = 3-5; b = 8 - 12, where L * represents the brightness, a the red / green part and b the yellow / blue part. The corresponding alloy compositions contain approx. 36% Pd. In order to achieve a shade that is comparable to rose gold, these pink shades can be used.
Example 11 describes a pink bronze with L * = 80; a = 4; b = 14.5, which has a gray-pink hue, with an alloy composition with Cu 45%, Sn 21%, Pd 34%. The outer layer is pink gold with L * = 87; a = 8.0; b = 16.5.
Example 12 describes a pink bronze with L * = 80; a = 3; b = 11.5, which also has a gray-pink hue, with an alloy composition with Cu 39%, Sn 20%, Pd 38%. The outer layer is yellow gold with L * = 87; a = 4.5; b = 25.5.
Example 14 describes three current density ranges with different hues.
At low current density, a pink bronze with L * = 80; a = 3.1; b = 10.9, i.e. a gray to gray-pink color, provided with an alloy composition with Cu 46.9%, Sn 17.1%, Pd 30.9%, Zn 5.1%. The outer layer is yellow gold with L * = 87; a = 2.1; b = 13.7.
At medium current density, a pink bronze with L * = 80; a = 3.2; b = 11.1, also a gray to gray-pink color, and an alloy composition with Cu 40.6%, Sn 20.3%, Pd 35.8%, Zn 3.3%. The outer layer is yellow gold with L * = 87; a = 2.1; b = 13.7.
With a high current density, a pink bronze with L * = 80; a = 3.3; b = 11.6, with a gray to gray-pink hue, and an alloy composition with Cu 39.2%, Sn 20.5%, Pd 37.6%, Zn 2.7%. The outer layer is yellow gold with L * = 87; a = 1.85; b = 13.1.
The ones in the WO 2018/146623 The colors designated as pink are therefore either inox or bronze medal colors or gray-pink. There is therefore a clearly visible color difference between the outer layer and the bronze layer below.

18 carat rose gold has CIELAB values of L * = 86; a = 9; b = 15, a soft yellow-pink shade, so the underlying layer should also be as identical as possible in color. In particular, the layer underneath should not be darker, otherwise any imperfections will be more noticeable. Another disadvantage is that the price of palladium is currently higher than the price of gold, which makes the price of a product with a palladium-alloyed lower layer significantly more expensive, although drag-out losses occurring during manufacture in baths with 5 or up to 8 g / l palladium have not yet been taken into account .

The object is therefore to provide a coating system that is inexpensive and yet has a noble appearance and high abrasion resistance.

The object is achieved by a coating system with the features of claim 1.
According to the invention, a coating system for application to a blank, in particular a blank for a jewelry element, comprising a palladium-free, in particular noble metal-free, rosebronze layer facing the blank, the rosebronze layer containing tin and copper, one arranged on the rosebronze layer Diffusion barrier layer and an outer rose gold layer disposed on the diffusion barrier layer.

The coating system has improved abrasion resistance and good corrosion resistance and is inexpensive to manufacture. The rose gold layer is underlaid with an essentially same-colored rose bronze layer so that imperfections are barely visible. The rose bronze can be deposited from baths of different types such as alkaline cyanide baths, alkaline cyanide-free baths, strongly acidic baths, or other baths and is therefore easy and inexpensive to apply, so that the coating system can be produced inexpensively. To ensure that the rose gold layer remains tarnish-resistant, a diffusion barrier is applied to the rose bronze layer. A diffusion barrier is an intermediate layer that prevents copper from migrating into the gold layer and causing tarnishing there. Since there is no precious metal in the rose bronze alloy, the coating system is also inexpensive. Precious metals are metals that are corrosion-resistant, which means that they are permanently chemically stable in a natural environment under the influence of air and water. The precious metals include gold, silver and the platinum metals ruthenium, rhodium, palladium, osmium, iridium and platinum.

Advantageous configurations result from the following features:
It can be provided that the rose gold layer, in particular 70% -80%, preferably 75% or 18 carat gold and, in particular 20% -30%, preferably 25%, copper. The soft yellow-pink shade of such an alloy is perceived as particularly noble. The manufacturing costs are mainly based on the amount of gold used. A deposition can take place from acidic, neutral, alkaline as well as from alkaline cyanide baths. In addition, small amounts of other metals can also be included, for example.

It is advantageous if the rose bronze layer and the rose gold layer have the same color. This means that imperfections in the coating system are hardly noticeable. An object coated with the coating system therefore remains attractive for longer. In particular, the shade of the rose bronze layer cannot be distinguished from 18 carat rose gold. As a result, a particularly elegant appearance can be achieved at low manufacturing costs.

In order to achieve that the rose bronze layer and the rose gold layer have a particularly similar appearance, it can be provided that the rose gold layer CIELAB values of L * = 85-87; a = 8-9.5; b = 14-16. In addition, it can be provided that the rose bronze layer has CIELAB values of L * = 84 - 87; a = 8-10; b = 13-17, especially L * = 86-87; a = 8-9; b = 15 -17. As a result, particularly inexpensive production and noble-looking objects or decorative elements can be achieved.

In order to achieve a color tone that is particularly similar to the rose gold layer, it can be provided that the rose bronze layer contains 5% -15%, in particular 7% -12%, tin. It can be provided that the rose bronze layer contains 85% -95%, in particular 88% -93%, copper. It can also be provided that the rose gold layer, in particular, comprises up to 5% zinc. For example, either a copper-tin alloy or a copper-tin-zinc alloy is used as rose bronze, which may contain small amounts of other alloy components, apart from precious metals.

It is advantageous if the rose bronze layer consists of tin and copper, in particular of 5% -15%, preferably 7% -12%, tin and 85% -95%, preferably 88% -93%, copper. The fact that it only contains two alloy metals makes it much easier to manage the bath. The manufacturing costs can thereby be reduced without any loss of quality.

In order to make the coating system particularly resistant, it can be provided that an adhesive layer, in particular comprising or containing gold and / or copper, is arranged under the rosebronze layer. This improves the adhesion of the coating system to the blank.

The diffusion barrier layer can consist of palladium or a palladium alloy. In particular, it can be provided that the diffusion barrier layer is free of copper. The diffusion barrier layer can prevent tarnishing of the rose gold layer particularly effectively. In addition, the diffusion barrier layer has a light shade of at least L * = 84, which reduces the visibility of imperfections. If a pure diffusion barrier layer made of palladium is used, the bath management is particularly simple and a clear cost calculation is possible, since the costs only depend on the layer thickness.

The abrasion resistance of the coating system is an important variable for many applications. Good abrasion resistance at low manufacturing costs can be achieved if the rose bronze layer has a layer thickness of 0.5 µm - 4 µm, in particular 0.8 µm - 3 µm. Since the abrasion resistance increases with increasing layer thickness and the rosebronze layer is inexpensive, the layer thickness can be selected depending on the desired abrasion resistance.

In addition or instead, provision can be made for the diffusion barrier layer to have a layer thickness of 0.1 μm-1.2 μm, in particular 0.2 μm-0.3 μm. This effectively prevents tarnishing of the rose gold layer, while at the same time keeping costs low. The abrasion resistance is also positively influenced.

Alternatively or additionally, it can also be provided that the rose gold layer has a layer thickness of 0.3 µm - 1 µm, in particular 0.4 µm - 0.7 µm. As a result, high abrasion resistance is achieved at low manufacturing costs. The coating system also has a particularly elegant appearance.

It is advantageous if the rose bronze layer, the diffusion barrier layer and the rose gold layer are arranged in a direct layer sequence on top of one another or if the layers are arranged directly adjacent to one another without intermediate layers. In particular, it can be provided that the rose gold layer forms the outermost layer of the coating system. Both the color and the durability are positively influenced by this.

For use on objects that come into contact with the skin for a long time, as is often the case with jewelry elements, it can be provided that the coating system is free from toxic alloy metals. This particularly includes metals that are labeled with the GHS symbols GHS06 "Acute Toxicity" or GHS08 "Harmful". A substance is acutely toxic if it can lead to death or acute or chronic damage to health in small quantities when inhaled, swallowed or absorbed through the skin. Substances are considered to be harmful if they are inhaled, swallowed or absorbed through the skin and can cause acute or chronic damage to health. Nickel, cobalt and lead are particularly to be avoided. Otherwise, these metals could lead to undesirable reactions on contact with the skin.

According to the invention is also a method for coating objects, in particular with a coating system described above, wherein a rose bronze layer containing copper and tin is applied, wherein on the Rose bronze layer, a diffusion barrier layer is applied, and an outer rose gold layer is applied over the diffusion barrier layer.

In order to increase the adhesion, it can be provided that an object to be coated, in particular a decorative element to be coated, is coated with an adhesion layer, in particular comprising gold and / or copper, before the rosebronze layer is applied.

The coating can be done by electrodeposition. This enables a particularly targeted process management and the coating of objects with finely divided surface structures is also made possible. The composition of the coating system enables simple bath management, so that galvanic deposition is particularly suitable for producing the coating system.

According to the invention, a coating system is also obtained by a method described above. Such a coating system has high abrasion resistance, and a noble appearance can be achieved with inexpensive production.

According to the invention, a decorative or decorative element is also coated with a coating system described above or obtained according to a method described above. Such a decorative or decorative element has a high level of abrasion and corrosion resistance and a long service life. At the same time, a noble appearance is achieved, although production is inexpensive.

• Fig. 1 zeigt ein beispielhaftes erfindungsgemäßes Beschichtungssystem.
• Fig. 2 zeigt die Abriebbeständigkeit getesteter Beschichtungssysteme im Vergleich.
• Fig. 3 zeigt einen Kostenvergleich verschiedener Beschichtungssysteme.

Exemplary embodiments of the invention are shown on the basis of the figures and examples without restricting the general inventive concept.

• Fig. 1 shows an exemplary coating system according to the invention.
• Fig. 2 shows the abrasion resistance of tested coating systems in comparison.
• Fig. 3 shows a cost comparison of different coating systems.

Fig. 1 shows an exemplary coating system for application to a blank for a jewelry element, the coating system being damaged by a scratch 4. The coating system has a rose bronze layer 1 which faces the blank. A diffusion barrier layer 2 is located above the rose bronze layer 1 arranged. A rose gold layer 3 is also arranged on the diffusion barrier layer 2. In the embodiment shown, the rose bronze layer 1 has a layer thickness of 3 μm, the diffusion barrier layer 2 has a layer thickness of 0.2 μm and the rose gold layer 3 has a layer thickness of 0.5 μm. The scratch 4 extends through the superficially arranged rose gold layer 3 and the diffusion barrier layer 2 into the rose bronze layer 1. Since the diffusion barrier layer 2 has a light shade and the rose bronze layer 1 has a shade comparable to the rose gold layer 3, the scratch 4 is hardly visible.

To produce an exemplary decorative article, the following procedure can be used:
A blank made of tin, zinc or iron, for example, can first be coated with an adhesive layer of 3 - 10 µm copper, which is deposited from a cyanide copper bath, in order to ensure that it adheres to the blank. If the blank is made of brass, this step can be omitted. Furthermore, 5 - 25 µm copper can be deposited from a strongly leveling acidic copper bath, depending on the surface properties or the desired degree of gloss. Leveling means that the copper bath is able to level out indentations and unevenness and to make the surface shiny.

A rose bronze layer 1 is then deposited, which has the same hue as the rose gold layer 3. In the embodiment shown, the rose gold has a composition of 75% Au and 25% Cu, as well as colorimetric coordinates in the CIELAB color space of approximately L * = 86; a = 9; b = 15. The rose bronze is composed of 93% Cu and 7% Sn and the colorimetric coordinates of the rose bronze are L * = 84 - 87; a = 8-10; b = 13-16.
Palladium, or in an alternative embodiment a palladium alloy, with a layer thickness of 0.1-1 μm as a diffusion barrier layer 2 is applied over the rosebronze layer 1. This prevents the copper from migrating into the rose gold layer 3 and thus prevents tarnishing. The colorimetric coordinates in CIELAB space of a deposit of Gapal FS, a neutral strike palladium electrolyte, gives L * = 84.0; a = 1; b = 6.6, or provides a deposit of Gapal HT, an alkaline pure palladium electrolyte, L * = 86.9; a = 0.77; b = 5.43.
The rose gold layer 3 is then deposited on this diffusion barrier layer 2.

Durchmesser: 10,2 cm Prüfplättchen für Farbmessung Material: Messing

Länge: 3 cm Breite: 3 cm Ringe Material: Messing

Durchmesser: 2 cm Höhe: 4 mm Modeschmuckteil Material: Zinkdruckguss Kettenanhänger Breite: ca. 5 cm Länge: ca. 3 cm

In order to be able to carry out comparative tests, test objects were produced. Table 1 shows the test objects used, Table 2 shows the electrolytes used: Tab. 1 test objects used Test discs for abrasion test Material: iron

Diameter: 10.2 cm Test plate for color measurement Material: brass

Length: 3 cm Width: 3 cm Rings Material: brass

Diameter: 2 cm Height: 4mm Costume jewelry Material: die-cast zinc Chain pendant Width: approx. 5 cm Length: approx. 3 cm

The disks were first coated with an adhesive layer of 0.05 µm adhesive gold deposited from MC 210 H.
The platelets and rings were coated with 15 μm copper which was deposited from IWG Cu 550.
The costume jewelery item was coated with an adhesive layer of 5 µm Cu from Cuproga and then with 15 µm Cu from IWG Cu 550.

The layer sequences summarized in Table 3 were then applied, the layer sequences 1 to 3 being used as a comparison and the layer sequences 4 to 7 leading to exemplary coating systems. Tab. 3 Layer sequences of the tested coating systems Shift sequence Layer thickness (µm) rose bronze layer Layer thickness (µm) Diffusion barrier layer (Pd) Layer thickness (µm) rose gold 1 0.25 1 2 0.25 2 3 0.25 3 4th 0.8 0.30 0.5 5 1.6 0.12 0.5 6th 2 0.20 0.5 7th 3 0.25 0.5

Example: Production of an exemplary costume jewelery item

In the following example, the production of a costume jewelery item with the layer sequence 7 is described in detail to illustrate the coating system according to the invention:
A jewelery blank made of die-cast zinc is electrolytically degreased in a weakly alkaline, cyanide-free cleaner (Degreasing 1018, product of Ing. W. Garhöfer GesmbH) at 25 ° C. for 30 s at 10 A / dm ² .
The jewelery blank is then rinsed in deionized water and 5 µm of copper are added at 1 A / l in an alkaline cyanide pre-copper bath with 22 g / l Cu and 34 g / l KCN ("Cuproga", product of Ing. W. Garhöfer GesmbH) dm ² and 50 ° C deposited.
The pre-copper-plated jewelry blank is then pickled in 5% sulfuric acid solution for 30 s and placed in an acidic copper bath with 50 g / l Cu and 60 g / l sulfuric acid ("IWG Cu 550 ", product from Ing. W. Garhöfer GesmbH), 15 μm copper is deposited in a leveling and high-gloss finish at 4 A / dm ² and 25 ° C.
The copper-plated part is rinsed and pre-immersed in a 10% KCN solution. Then, from the rose bronze bath Pink Bronze CT 18 LF, 3 μm rose bronze with the composition 93% Cu, 7% Sn, at 50 ° C. and 1 A / dm ^{2 is} deposited from the electrolyte within 15 minutes.
It is then rinsed in deionized water, pickled in 5% sulfuric acid solution and added to a neutral, ammonia-containing pure palladium electrolyte with 2 g / l Pd ("Gapal FS", product from Ing. W. Garhöfer GesmbH) with 0.25 μm Pd 1A / dm ² and 25 ° C coated.
The jewelry part obtained in this way is rinsed again with 0.5 μm rose gold with a composition of 75% or 18 carat Au and 25% Cu from a neutral electrolyte with 3 g / l Au ("MC 630", product from Ing. W Garhöfer GesmbH) at 0.5 A / dm ² and 55 ° C.

The layer sequences 1 to 6 were applied analogously to this procedure.

Finally, the galvanized part is rinsed in deionized water and dried. The galvanized jewelry part obtained in this way or its surface is rose-colored and high-gloss with CIELAB values of L * = 86.30; a = 8.76; b = 15.61.

The other test objects were also coated according to this procedure.

Exams: 1. Test for abrasion resistance

The test was performed with a Taber Industries Rotary Platform Abrasion Tester Model 5135 with 250 g weight per wheel and P1000 sandpaper strip. For this purpose, as shown in Table 1, the test disks that exactly fit this device were used. These were first coated with the various layer sequences in a manner analogous to the production of the costume jewelery item described by way of example.

The coated disks were clamped in the testing device and rubbed off.
After every 25 revolutions, the sheaths were removed from the device and it was determined by means of X-ray fluorescence analysis whether a layer had already been completely rubbed off. The number of revolutions before a layer was worn was recorded. The sum of the individual layer abrasions resulted in the total abrasion.

The results are summarized in Table 4 and in Fig. 2 shown as a bar chart. Tab. 4 Comparison of the abrasion resistance Shift sequence Abrasion [U to layer abraded] Abrasion [U to total abrasion] 0.25µ Pd 25th 150 1µ rose gold 125 0.25µ Pd 25th 275 2µ rose gold 250 0.25µ Pd 25th 400 3µ rose gold 375 0.8µ rose bronze 100 200 0.3µ Pd 25th 0.5µ rose gold 75 1.6µ rose bronze 200 275 0.12µ Pd 25th 0.5µ rose gold 50 2µ rose bronze 225 300 0.2µ Pd 25th 0.5µ rose gold 50 3µ rose bronze 325 400 0.25µ Pd 25th 0.5µ rose gold 50

It has been shown that despite the low layer thickness of the rose gold layer and the diffusion barrier layer, a high level of abrasion resistance could be achieved.

2. Test of corrosion resistance according to DIN 50018

The rings were used as test objects for the corrosion resistance test. The galvanized rings were subjected to the corrosion test together. The results were all comparable and showed no tarnishing regardless of the shift sequence.

3. Color measurement

As can be seen from Table 1, small test objects were used for the color measurement. The platelets were coated analogously to the production of the costume jewelery item described by way of example. The platelets were coated with the base copper another layer or further layer sequences are applied. The numbering corresponds to the layer sequences listed in Table 3. The colors were measured using a Ci6X color measuring device from X-rite. The use of plates is necessary for this device, as the device should lie flat on the surface to be measured, as this is the only way to correctly determine the L * value.

On the one hand, the CIELAB value of the coating system was measured. In addition, the CIELAB values of the individual layers were measured, which become visible when the layer above is damaged.

It has been shown that the CIELAB values of the rose bronze layer are comparable to the CIELAB values of the rose gold layer. Damage, for example a scratch that extends into the rose bronze layer, is therefore hardly visible. Damage that extends into the diffusion barrier layer made of palladium is also barely visible due to the lighter color.

The measured values are summarized in Table 5. Tab. 5 Comparison of the CIELAB values Shift or shift sequence L * a b 0.25 µm Pd 84.32 +1.02 +6.55 1 85.95 +9.15 +14.37 2 86.65 +9.22 +15.72 3 86.01 +8.96 +15.54 0.8 µm rose bronze 86.78 +8.72 +16.61 0.8 µm rose bronze / 0.3 µm Pd 84.07 +0.99 +6.63 4th 86.60 +9.18 +14.75 1.6 µm rose bronze 86.23 +8.94 +16.86 1.6 µm rose bronze / 0.12 µm Pd 84.18 +1.13 +6.49 5 86.55 +9.37 +15.67 2 µm rose bronze 86.89 +8.86 +16.73 2 µm rose bronze / 0.2 µm Pd 84.09 +0.78 +6.71 6th 86.46 +8.99 +14.59 3 µm rose bronze 86.19 +8.44 +16.98 3 µm rose bronze / 0.25 µm Pd 84.20 +0.83 +6.61 7th 86.04 +9.04 +15.42

4. Optical assessment

The fashion jewelry items were used as test objects. The fashion jewelery items provided with the different layer sequences 1 to 7 were placed next to one another and examined for comparison. They were comparable in both gloss and color.

Cost comparison

The cost of the individual coatings was calculated. The metal rates and the metal or alloy densities were taken into account. The costs for the individual shift sequences are shown in Table 6 and Fig. 3 shown. The exemplary coating systems have a clear cost advantage in comparison with known coating systems. Tab. 6: Cost comparison for different coating systems Shift sequence Costs (EUR / dm ² ) 0.25 µm Pd / 1 µm rose gold 6.29 0.25 µm Pd / 2 µm rose gold 11.45 0.25 µm Pd / 3 µm rose gold 16.61 0.8µm rose bronze / 0.3µm Pd / 0.5µm rose gold 3.94 1.6 µm rose bronze / 0.12 µm Pd / 0.5 µm rose gold 3.12 2µm rose bronze / 0.2µm Pd / 0.5µm rose gold 3.48 3µm rose bronze / 0.25µm Pd / 0.5µm rose gold 3.71

It was thus possible to show that objects and articles which are produced with the layer sequences according to the invention have comparable corrosion resistance with the same optical appearance, and despite lower production costs have improved abrasion resistance.

Compared to WO 2018/146623 .
The ones in the WO 2018/146623 The specified formulations from Example 1 and Example 2 were prepared in the laboratory and alloys were deposited therefrom.

An alloy composition of approx. 29% Pd, 48% Cu, 18% Sn and 5% Zn was deposited from the electrolyte according to Example 1 at 60 ° C., 1.5 A / dm ² in 7 minutes. The deposit was gray and without gloss.

An alloy composition of approx. 0.8% Pd, 98.4% Cu, 0.8% Sn at 50 ° C., 1 A / dm ^{2 was} deposited in 15 minutes from the electrolyte according to Example 2. It showed a copper-colored deposit without gloss.
The ones in the WO 2018/146623 The bronze alloys described are gray to steel-colored and have only slight yellow and pink tints, although their color is more similar to pure palladium deposits than 18-carat rose gold.

The four alloy components make bath management much more difficult.

WO 2018/146623 Example 14 specifies a coating with 0.9-1.2 µm pink bronze with a palladium content between 31% - 38%, which corresponds to a pure palladium layer of about 0.28-0.46 µm. The amount of deposited palladium is therefore somewhat larger and the costs are therefore also somewhat higher, with 4 alloy components making the bath more difficult and the diffusion of copper into the outer layer of gold is not excluded, as there is no diffusion barrier and the alloy is copper below the gold layer contains.

In contrast, the invention provides a coating system which can also meet high optical requirements and has high durability, in particular high corrosion resistance and high abrasion resistance, at low production costs.

Claims (15)

Coating system for application by galvanic deposition on a blank, in particular a blank for a jewelry element, comprising a palladium-free, in particular precious metal-free, rosebronze layer facing the blank, the rosebronze layer containing tin and copper, a diffusion barrier layer arranged on the rosebronze layer and an outer layer arranged on the diffusion barrier layer Rose gold layer. Coating system according to claim 1, characterized in that the rose gold layer contains gold and copper, it being provided in particular that 70% -80%, preferably 75% or 18 carat gold and 20% -30%, preferably 25%, contain copper is. Coating system according to one of Claims 1 or 2, characterized in that the rose bronze layer and the rose gold layer have the same color tone. Coating system according to one of Claims 1 to 3, characterized in that the rose gold layer has CIELAB values of L * = 85 - 87; a = 8-9.5; b = 14-16 and / or that the rose bronze layer has CIELAB values of L * = 84-87; a = 8-10; b = 13-17. Coating system according to one of Claims 1 to 4, characterized in that the rose bronze layer contains 5% - 15%, in particular 7% - 12%, tin, and / or that the rose bronze layer contains 85% - 95%, in particular 88% - 93%, Contains copper, and / or that the rose bronze layer, in particular up to 5%, contains zinc. Coating system according to one of claims 1 to 5, characterized in that the rose bronze layer consists of tin and copper, in particular of 5% - 15%, preferably 7% - 12%, tin and 85% - 95%, preferably 88% - 93% , Copper. Coating system according to one of Claims 1 to 6, characterized in that an adhesive layer, in particular comprising gold and / or copper, is arranged under the rose bronze layer. Coating system according to one of Claims 1 to 7, characterized in that the diffusion barrier layer consists of palladium or a palladium alloy, it being provided in particular that the diffusion barrier layer is free of copper. Coating system according to one of Claims 1 to 8, characterized in that the rose bronze layer has a layer thickness of 0.5 µm - 4 µm, in particular 0.8 µm - 3 µm,
and / or that the diffusion barrier layer has a layer thickness of 0.1 µm - 1.2 µm, in particular 0.2 µm - 0.3 µm,
and / or that the rose gold layer has a layer thickness of 0.3 µm - 1 µm, in particular 0.4 µm - 0.7 µm. Coating system according to one of claims 1 to 10, characterized in that the rose bronze layer, the diffusion barrier layer and the rose gold layer are arranged in a direct layer sequence on top of one another or are arranged directly adjacent to one another without intermediate layers, it being provided in particular that the rose gold layer is the outermost layer of the coating system forms. Coating system according to one of Claims 1 to 10, characterized in that the coating system is free from lead and / or nickel and / or cobalt, and / or that the coating system is free from toxic alloy metals. A method for coating objects, in particular with a coating system according to one of claims 1 to 11, wherein a rose bronze layer containing copper and tin is applied to the object, a diffusion barrier layer being applied to the rose bronze layer, and an outer rose gold layer being applied over the diffusion barrier layer . Method according to Claim 11 or 12, characterized in that the coating is carried out by electroplating. Coating system obtained by a method according to one of Claims 12 or 13. Ornamental or decorative element coated with a coating system according to one of claims 1 to 11 or 14 and / or obtained by a method according to one of claims 12 or 13.

Images