(19)
(11)EP 3 312 309 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
29.04.2020 Bulletin 2020/18

(21)Application number: 16194360.0

(22)Date of filing:  18.10.2016
(51)International Patent Classification (IPC): 
C25D 7/00(2006.01)
C22C 9/00(2006.01)
C25D 5/10(2006.01)
C23C 28/00(2006.01)

(54)

ELECTROPLATED PRODUCT HAVING A PRECIOUS METAL FINISHING LAYER AND IMPROVED CORROSION RESISTANCE, METHOD FOR ITS PRODUCTION AND USES THEREOF

ELEKTROPLATTIERTES PRODUKT MIT EINER EDELMETALLOBERFLÄCHENSCHICHT UND VERBESSERTER KORROSIONSBESTÄNDIGKEIT, VERFAHREN ZU DESSEN HERSTELLUNG UND VERWENDUNGEN DAVON

PRODUIT PLAQUÉ PRÉSENTANT UNE COUCHE DE FINITION DE MÉTAL PRÉCIEUX ET UNE RÉSISTANCE À LA CORROSION AMÉLIORÉE, SON PROCÉDÉ DE PRODUCTION ET LEURS UTILISATIONS


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(43)Date of publication of application:
25.04.2018 Bulletin 2018/17

(73)Proprietor: COVENTYA S.p.A.
22060 Carugo (CO) (IT)

(72)Inventors:
  • Nelias, Coline
    51100 Pistoia (IT)
  • Petracchi, Daniele
    59100 Prato (IT)

(74)Representative: Pfenning, Meinig & Partner mbB 
Patent- und Rechtsanwälte Theresienhöhe 11a
80339 München
80339 München (DE)


(56)References cited: : 
WO-A1-2013/164165
JP-A- 2003 096 592
JP-A- 2002 060 993
US-A1- 2003 059 634
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] This invention provides an electroplated product with a precious metal finishing layer that has an improved corrosion and abrasion resistance. The electroplated product comprises two electroplated copper alloy layers having a different copper concentration (e.g. white bronze and yellow bronze). The electroplated product is especially suitable for use in jewelry, fashion, leather, watch, eyewear, trinkets and/or lock industry. Another advantage of the electroplated product is that the use of allergenic nickel or expensive palladium intermediate layers against copper migration can be dispensed with. This means that the electroplated product can be non-allergenic (nickel-free) and be provided in a more economical and environment-friendly manner. A method for the production of the inventive electroplated product is presented. Furthermore, the use of the inventive electroplated product in the jewelry, fashion, leather, watch, eyewear, trinkets and/or lock industry is suggested.

    [0002] The underlayers presently used in the fashion market to provide a high corrosion and wear resistant support for a top gold finishing layer comprises nickel and/or nickel based alloys. The allergy associated with nickel and the classification of nickel salts as carcinogenic, mutagenic and reprotoxic substances makes the use of nickel and nickel based alloys more and more restricted in this market. Thus, its use has been strongly restricted, especially for fashion and jewelry applications. Several attempts have been made to develop a nickel-free electrolytic deposit for applying metal layers to substrates.

    [0003] The most commonly used alternative to nickel is white bronze which is an alloy of copper, tin and zinc. However, this alloy alone can not meet the corrosion resistance requirements of the fashion industry. As an alternative to said alloy, layers of precious metals like palladium were used between the substrate and the final decorative finishing layer. However, palladium as an intermediate protective layer strongly increases the cost of the final item i.e. its use is uneconomical.

    [0004] As an alternative to palladium, the use of different tin alloys as an intermediate barrier layer has been suggested. However, it was found that a tin content of more than 50 wt.-% in the alloy results in poor resistance to acidity and oxidants leading to corrosion and to a brightness level which are unsatisfactory for the fashion market. As a further alternative to palladium, intermediate layers consisting of chromium have been used. However, said chromium layers resulted in adhesion problems and corrosion resistance problems for the final precious metal layer such as gold. In addition, the use of toxic chromium VI is highly undesirable in the field of jewelry and fashion.

    [0005] Moreover, WO 2013/164165 A1 discloses a multi-layered nickel-free surface coating for sanitary application having a copper layer, a coating of at least one metal layer consisting of an alloy of copper, tin and zinc or copper and tin, a coating of at least one metal layer consisting of chromium, copper, gold, palladium or iron and a final chromium layer. Importantly, the intermediate layer contains a precious metal (palladium or gold) that drastically increases the cost of the electroplated product or a metal such as chromium, copper and iron that drastically reduce adherence of the final decorative layer or lower the corrosion resistance of the electroplated product. Thus, the electroplated product is less suitable for the high requirements in the jewelry and/or fashion industry.

    [0006] WO 2008/003216 A1 discloses an electroplated product including a copper layer on the surface of the base material, characterized in that the electroplated copper metal layer further includes a metal layer as a nickel substitute, and this nickel substitute metal is a Cu-Sn alloy, Ru, Rh, Pd, or an alloy composed of 2, 3, or 4 elements selected from Ru, Rh, Pd, and Co. However, the use of one single layer of Cu-Sn alloy is not sufficient to target the high corrosion resistance requirement for the jewelry or fashion market and the use of precious metal intermediate layers is very expensive.

    [0007] US 2003/0059634 A1 discloses a low-priced personal ornament which has a white-colored inexpensive stainless steel outermost coating layer having long-term corrosion resistance and discloses a process for producing said ornament.

    [0008] JP 2003 096592 A discloses external parts for timepieces which greatly expand color variations by applying a coating thereto.

    [0009] Therefore, the prior art does not fulfill the requirements of the decorative, fashion and jewelry industry of providing in an economic and easy manner an electroplated product which is non-allergenic and has a high level of brightness and improved corrosion and abrasion resistance.

    [0010] Starting therefrom, it was the object of the present invention to provide an electroplated product and method for its production which overcomes said disadvantages.

    [0011] The object is solved by the electroplated product according to claim 1, the method for producing the inventive electroplated product according to claim 16 and the use of the inventive electroplated product according to claim 17. The dependent claims illustrate advantageous embodiments.

    [0012] According to the invention, an electroplated product is provided, comprising
    1. a) a base material;
    2. b) a first layer comprising or consisting of copper, wherein the first layer is disposed on the base material;
    3. c) a second layer comprising or consisting of a first copper alloy, wherein the first copper alloy comprises tin and zinc;
    4. d) a third layer comprising or consisting of a second copper alloy, wherein the second copper alloy comprises tin and zinc; and
    5. e) a fourth layer comprising or consisting of a precious metal, wherein the precious metal is selected from the group consisting of gold, silver, platinum, ruthenium, rhodium, palladium, osmium, iridium and alloys thereof;
    wherein
    1. i) the second layer is disposed on the first layer, the third layer is disposed on the second layer and the fourth layer is disposed on the third layer; or
    2. ii) the third layer is disposed on the first layer, the second layer is disposed on the third layer and the fourth layer is disposed on the second layer, characterized in that the fourth layer is the finishing metal layer of the electroplated product, the copper concentration in the first copper alloy is different from the copper concentration in the second copper alloy, and the first layer has a thickness in the range of >15 to 60 µm.


    [0013] In the electroplated product, diffusion of copper from a copper containing layer into a layer containing less copper and/or a precious metal layer (like e.g. gold layer) is generally thermodynamically favoured. However, the presence of zinc in the copper containing layer was found to strongly decrease copper diffusion. Furthermore, it was discovered that if there is a first intermediate layer in the electroplated product which comprises or consists of a copper-zinc alloy having a lower copper concentration than a second intermediate layer which comprises or consists of a copper-zinc alloy, the first layer acts as a copper sink and prevents copper migration from copper containing layers of the electroplated product into the finishing precious metal layer of the electroplated product.

    [0014] The electroplated product fulfills the main requirements of the fashion industry in terms of corrosion resistance, wear resistance and copper diffusion barrier properties. Compared to known alternatives in the prior art of palladium-less and nickel-less electroplated products, the inventive electroplated product shows a better corrosion performance, a better abrasion performance, an increased shelflife and a decreased production cost.

    [0015] The copper concentration of the first copper alloy (in wt.-%) may differ from the copper concentration of the second copper alloy (in wt.-%) by an absolute value of 1 to 99 wt.-%, preferably 5 to 80 wt.-%, more preferably 10 to 60 wt.-%, even more preferably 15 to 40 wt.-%, most prefer ably 20 to 30 wt.-%,

    [0016] The inventive electroplated product is characterized in that
    1. i) the second layer is disposed on the first layer, the third layer is disposed on the second layer and the fourth layer is disposed on the third layer; or
    2. ii) the third layer is disposed on the first layer, the second layer is disposed on the third layer and the fourth layer is disposed on the second layer.


    [0017] The copper concentration in the second alloy can be higher than the copper concentration in the first alloy. Thus, the second alloy (e.g. yellow bronze) gives better brightness than the first alloy and may be deposited at faster deposition rates (higher productivity). On the other hand, the first alloy having a lower copper concentration (e.g. white bronze) gives a harder layer and better corrosion and abrasion resistance properties compared to the second alloy. Thus, if increased hardness is desired, it is beneficial if the second layer is disposed on the third layer in the electroplated product whereas if increased brightness is desired, it is beneficial if the third layer is deposited on the second layer. In terms of corrosion resistance, it has turned out that the best sequence is if the second layer (e.g. white bronze layer) is deposited on the first layer (e.g. copper layer), the third layer (e.g. yellow bronze layer) is deposited on the second layer (e.g. white bronze layer) and the fourth layer (e.g. gold layer) is deposited on the third layer (e.g. yellow bronze layer).

    [0018] The copper concentration in the
    1. i) first copper alloy may be ≤ 65 wt.-%, preferably 30 to 64 wt.-%, more preferably 40 to 60 wt.-%, most preferably 45 to 55 wt.-%, in relation to the whole weight of the copper alloy; and/or
    2. ii) the second copper alloy may be ≥ 66 wt.-%, preferably 66 to 90 wt.-%, more preferably 70 to 87 wt.-%, most preferably 75 to 85 wt.-%, in relation to the whole weight of the copper alloy.


    [0019] The zinc concentration in the
    1. i) first copper alloy may be ≥ 10 wt.-%, preferably 11 to 35 wt.-%, more preferably 12 to 25 wt.-%, most preferably 15 to 20 wt.-%, in relation to the whole weight of the copper alloy; and/or
    2. ii) the second copper alloy may be ≤ 15 wt.-%, preferably 2 to 10 wt.-%, more preferably 3 to 8 wt.-%, most preferably 4 to 7 wt.-% (optionally 5 to 7 wt.-%), in relation to the whole weight of the copper alloy.


    [0020] The tin concentration in the
    1. i) first copper alloy may be ≥ 26 wt.-%, preferably 26 to 35 wt.-%, in relation to the whole weight of the copper alloy; and/or
    2. ii) the second copper alloy may be ≤ 25 wt.-%, preferably 1 to 25 wt.-%, more preferably 10 to 25 wt.-%, most preferably 15 to 25 wt.-%, in relation to the whole weight of the copper alloy.


    [0021] In a preferred embodiment of the invention, the first copper alloy and/or the second copper alloy comprises Bi, Pb and/or Sb, preferably Bi. Having Bi in the alloy has the advantage that the alloy becomes both brighter and has an improved blocking ability of copper migration. The first copper alloy and/or the second copper alloy may also comprise phosphorus and/or silicon.

    [0022] In a preferred embodiment of the invention, the first copper alloy is white bronze and/or the second copper alloy is yellow bronze.

    [0023] The fourth layer may be disposed on the second or third layer.

    [0024] In a preferred embodiment of the invention, there is no layer comprising or consisting of palladium between the first layer and fourth layer. Preferably, the electroplated product does not comprise palladium.

    [0025] In a further preferred embodiment of the invention, there is no layer comprising or consisting of nickel, cobalt and/or chromium between the first layer and fourth, wherein the electroplated product preferably does not comprise nickel, cobalt and/or chromium, most preferably no nickel.

    [0026] An organic protection layer can be disposed on the fourth layer. The layer may comprise or consist of a hydrophobic substance and is preferably a monolayer of a hydrophobic substance, more preferably a monolayer of a hydrophobic substance being a corrosion inhibitor, most preferably a monolayer of a corrosion inhibitor comprising thiol groups, especially a monolayer of alkanethiol monomers or alkanethiol polymers like e.g. octadecanethiol monomers. This has the advantage that the surface of the finishing precious metal layer is made more hydrophobic and thus less prone to corrosion. Especially acid corrosion and corrosion due to sweat or interaction with leather is decreased. If the layer is only monomolecular in thickness, it is not visible and does not affect the appearance of the electroplated products.

    [0027] The precious metal is selected from the group consisting of gold, silver, platinum, ruthenium, rhodium, palladium, osmium, iridium and alloys thereof, preferably gold, silver, palladium and alloys thereof, more preferably gold, palladium and alloys thereof, most preferably gold.

    [0028] The base material may comprise or consist of bronze, brass, zamak, alpaca, copper alloy, tin alloy and/or steel. It is especially preferred that the base material comprises or consists of zamak. The base material may be an article selected from the group consisting of jewelry, fashion, leather industry, watches, eyewear, trinkets and locks.

    [0029] The thickness of
    1. i) the first layer may be 16 to 60 µm, preferably 20 to 55 µm, more preferably 25 to 50 µm, most preferably 30 to 45 µm;
    2. ii) the second layer may be 1 to 10 µm, preferably 2 to 8 µm;
    3. iii) the third layer may be 1 to 10 µm, preferably 2 to 4 µm; and/or
    4. iv) the fourth layer may be 0.1 to 5 µm, preferably 0.2 to 1 µm.


    [0030] Moreover, a method of producing the inventive electroplated product is presented, the method comprising the steps:
    1. a) electroplating a layer comprising or consisting of the first copper alloy on a copper layer disposed on a substrate;
    2. b) electroplating a layer comprising or consisting of the second copper alloy on the layer of step a);
    3. c) electroplating a layer comprising or consisting of the precious metal on the layer of step b),
      characterized in that the first copper alloy layer is plated with a copper concentration different from that of the second copper alloy layer.


    [0031] Finally, the use of the electroplated product in jewelry industry, fashion industry, leather industry, watch industry, eyewear industry, trinkets industry and/or lock industry, is proposed.

    [0032] With reference to the following figures and examples, the subject-matter according to the invention is intended to be explained in more detail without wishing to restrict said subject-matter to the special embodiments shown here.

    Figure 1 shows the GDOES depth profile of a nickel-less electroplated product according to Example 4 (2 µm white bronze layer (wt.-% of Cu:Sn:Zn = 40:40:20), no palladium intermediate layer) before (A) and after a heat-treatment at 180 °C for 24 hours (B). Extensive mutual diffusion of the metal atoms at the gold-white bronze interface is obvious. Due to the absence of calibration, the thicknesses and metallic concentrations illustrated in the GDOES depth profile do not mirror the true layer thicknesses and metallic concentrations. This applies also to Figg. 2-6.

    Figure 2 shows the GDOES depth profile of a nickel-containing electroplated product according to Example 5 (2 µm white bronze layer, palladium-nickel intermediate layer) before (A) and after a heat-treatment at 180 °C for 24 hours (B). The nickel/palladium layer inhibits any major metal migration at the interfaces.

    Figure 3 shows the GDOES depth profile of a nickel-free electroplated product according to Example 6 (2 µm white bronze layer with wt.-% of Cu:Sn:Zn = 40:40:20, 3 µm yellow bronze layer with wt.-% of Cu:Sn:Zn = 70:20:10, no palladium intermediate layer) before (A) and after a heat-treatment at 180 °C for 24 hours (B). The migration of gold and copper at the interface concerned is strongly reduced. Copper migrates predominantly from yellow to white bronze.

    Figure 4 shows the GDOES depth profile of a nickel-less electroplated product according to Example 7 (2-3 µm yellow bronze layer with wt.-% of Cu:Sn:Zn = 80:15:05 next to bright copper layer, 2-3 µm white bronze layer with wt.-% of Cu:Sn:Zn = 50:35:15 next to gold finishing layer) before (A) and after a heat-treatment at 180 °C for 24 hours (B). The GDOES analysis reveals a higher diffusion of the gold in the white bronze layer compared to the one observed in Figure 3.

    Figure 5 shows the GDOES depth profile of a nickel-less electroplated product according to the first assay of Example 8 (2-3 µm white bronze layer with wt.-% of Cu:Sn:Zn = 50:35:15 next to the gold finishing layer and another, identical 2-3 µm white bronze layer next to the bright copper layer) before (A) and after a heat-treatment at 180 °C for 24 hours (B). The effect of a double layer of white bronze is not very different from that of a single layer (see Fig. 1). The GDOES analysis reveals an alteration of the surface and thickness of the gold finishing layer due to gold diffusion into the white bronze layers.

    Figure 6 shows the GDOES depth profile of a nickel-less electroplated product according to the second assay of Example 8 (2-3 µm yellow bronze layer with wt.-% of Cu:Sn:Zn = 80:15:05 next to the gold finishing layer and another, identical 2-3 µm yellow bronze layer next to the bright copper layer) before (A) and after a heat-treatment at 180 °C for 24 hours (B). A double layer of yellow bronze does not show the reduced diffusion as compared to Figg. 3 for a white bronze-yellow bronze sequence and 4 for a yellow-bronze-white bronze sequence. The GDOES analysis reveals that the gold finishing layer surface is intact, but also reveals an internal alteration of the substrate which is likely responsible for the observed lower corrosion protection.

    Figure 7 shows a model to explain the observed prevention of any major copper migration into the gold finishing layer 4. Migration of copper in the electroplated product is observed owing to the high mobility of copper atoms during the heat treatment of the electroplated product. Since the first copper alloy layer 2 (white bronze) has a reduced copper content compared to the second copper alloy layer 3 (yellow bronze) it acts as a copper sink which draws copper atoms from the second copper alloy layer 3 and also from the first copper layer 1. This creates a strong flow of copper from the second copper alloy layer 3 towards the first copper alloy layer 2. This strong flow of copper appears to prevent copper from migrating from the second copper alloy layer 3 into the gold finishing layer 4 and thus ensures a low copper concentration in the gold finishing layer 4 which leads to an improved corrosion resistance of the electroplated product and preservation of its gold color tone. The thickness of the arrows in the illustrated model are supposed to indicate the intensity of copper migration i.e. the thicker the arrow the stronger the copper migration in the indicated direction. A small gold migration from the gold finishing layer 4 to the second copper alloy layer 3 (not shown) compensates the copper migration from the second copper alloy layer 3 to the gold finishing layer 4 at this interface. Figures 1-3 show that there is also a thermodynamically driven, concomitant migration of tin and zinc.


    Example 1 - Composition and properties of employed white and yellow bronze



    [0033] 
    White bronze
     Examples 4, 5 and 6Examples 7 and 8
    copper: 50-54 wt.-%** 40-54 wt.-%
    tin: 28-32 wt.-% 28-40 wt.-%
    zinc: 15-20 wt.-% 10-20 wt.-%
     Examples 4 to 8 
    layer density: 8.3 g/cm3  
    hardness: 550 HV  
    Colorimetric parameters*: L 87-90; a 0,5-2,5; b 2-4  
    * measured with Minolta CM-503i spectrophotometer. Illuminant used was Daylight D65 (6500K) with reflective component included (sci). Observer was set at standard (10°) and the measurements were done in the Color space CIE L*a*b*.
    Yellow bronze
     Examples 4, 5 and 6Examples 7 and 8
    copper: 72-77 wt.-% 70-80 wt.-%
    tin: 17-23 wt.-% 15-23 wt.-%
    zinc: 3-7 wt.-% 3-10 wt.-%
     Examples 4 to 8 
    layer density: 8.2 g/cm3  
    hardness: 400 HV  
    Colorimetric parameters*: L 87-90; a 4-6; b 18-20  
    * measured with Minolta CM-503i spectrophotometer. Illuminant used was Daylight D65 (6500K) with reflective component included (sci). Observer was set at standard (10°) and the measurements were done in the Color space CIE L*a*b*.
    ** measured by EDS microanalysis BRUCKER SVE 6, microprobe X Flash 610 mini

    Example 2 - GDOES principle and GDOES analysis of the layer structure of inventive electroplated products and electroplated products of the prior art


    Principle of GDOES (glow discharge optical emission spectrometry)



    [0034] The sample forms the cathode and a thin (4 mm diameter) copper tube forms the anode. A small O-ring separates the anode from the cathode. High-purity argon is pumped into the anode chamber. A high voltage (DC or RF) between sample and anode ionizes the argon to produce a glow discharge. The excited argon ions bombard the electroplated product sample and cause uniform sputtering of the sample surface. Atoms ejected are then excited by an Argon plasma, and finally come back to their fundamental energy level, emitting a characteristic X-ray photon.

    [0035] Emitted photons, whose energy is characteristic of the energy level of a chemical element, are then collected by photomultipliers. The intensity of each emission depends on the concentration of the element in the sample. The recorded signals are processed to obtain the distribution of the elements according to the erosion time. GDOES provides depth profiling analysis of solids like metals, powders, polymers, glasses and ceramics (in the present case: depth profiling of electroplated substrates).

    [0036] The advantages of GDOES are its rapid, multi-elemental acquisition, a simple implementation (no ultra-high vacuum) and the high sensitivity of detection for light elements, (like e.g. C, N and 0).

    Present GDOES analysis



    [0037] In the present analysis, the following GDOES parameters were used:

    ▪ GD Profiler, HORIBA, Jobin Yvon

    ▪ detection of elements: Au, Cu, Zn, Sn , Ni

    ▪ diameter of the anode: 4 mm

    ▪ analyses of the samples without and with heat treatment:

    • Sample 1: acidic copper+ gold 0.5 µm
    • Sample 2: acidic copper+ flash bronze (1 µm) + gold 0.5 µm
    • Sample 3: acidic copper+ white bronze (2 µm) + gold 0.5 µm
    • Sample 4: acidic copper+ white bronze (2 µm) +palladium/nickel flash 0,1 µm + gold 0.5 µm
    • Sample 5 : acidic copper + white bronze (2-3 µm) + yellow bronze (2-3 µm) + gold 0.5 µm
    • Sample 6: acidic copper + yellow bronze (2-3 µm) + white bronze (2-3 µm) + gold 0.5 µm;
    • Sample 7: acidic copper + white bronze (2-3 µm) + white bronze (2-3 µm) + gold 0.5 µm;
    • Sample 8: acidic copper + yellow bronze (2-3 µm) + yellow bronze (2-3 µm) + gold 0.5 µm.

    ▪ analyze before and after heat treatment for 24 hours at 180°C

    ▪ power: 25 W

    ▪ pressure: 620 Pa

    ▪ wavelengths of the spectral lines used (in nm): Au 242,8 ; Cu 224, 7; Zn 481; Sn 317,5; Ni 341,5.



    [0038] A low power was retained to decrease the speed of abrasion of the deposits with low thickness and to obtain maximum information at the interface. Quantified compositional results were evaluated automatically utilizing the standard Jobin Yvon quantum Intelligent Quantification software. The instrument was calibrated with standards of known composition. Depths were calculated using relative sputter rates, obtained from the sputter yields of each major element with corrections for composition and discharge conditions.

    [0039] The Figures 1 to 6 give the GDOES depth profile for the different electroplated products of Examples 4 and 8 before and after the heat treatment at 180°C for 24 hours. The concentration of each chemical element Au, Cu, Zn, Sn and eventually Ni (when this element is present to determine the Pd-Ni coating) is shown (y-axis in wt.-%) as a function of the distance from the surface of the finishing layer towards the base material of the electroplated product (x-axis in µm). The thicknesses of the layers given for the process of the argon ablation (abscissa) and the metal concentrations (ordinate) are not normalized, but reflect the progress of the metal migration from the as-plated to the annealed state (annealing at 180 °C for 24 h).

    Example 3 - Performance in corrosion and abrasion tests of a nickel-containing electroplated product of the prior art



    [0040] An electroplated nickel-containing product of the prior art comprises the following layers electrolytically deposited on a brass substrate:
    bright nickel layer: 10 µm
    nickel phosphorus layer: 2 µm
    gold layer as finishing layer: 0.5 µm


    [0041] Said electroplated nickel-containing product has the following properties:
    NFS 80772: 24 HOURS;
    ABRASION WITH TURBULA: 5 MINUTES
    LEATHER INTERACTION UNDER ISO 4611: 96 HOURS;
    ISO 4538: 48 HOURS;
    ISO 4524/2: 8 HOURS;
    ISO 4611: 96 HOURS;
    ABRASION TEST BY TURBULA UNDER ISO 23160: no color change after 30 min.


    [0042] Aim of the Turbula test is to simulate general wear that results from wearing the parts. The test was performed using an industrial rotating machine (Turbula, model T2F, Willy A. Bachofen AG Maschinenfabrik, Switzerland). Abrasive load was composed of abrasion ceramic elements mixed with fresh water containing a surface tension agent. Detailed information on the size of the ceramic elements is described in the ISO 23160 reference (see Table 1 - page 3). Test duration was 30 minutes. Evaluation of wear was done by visual inspection and comparison with reference samples. In particular, a color change after abrasion was used to evaluate wear resistance of the tested parts. The Turbula test is considered positive if no colour change is visible in the tested parts, especially on the edges or regions that are more exposed.

    [0043] The result of this test gave that the nickel sequence gives a very good performance, especially regarding abrasion due to the thick layer of nickel that does not give discoloration.

    Example 4 - Performance in corrosion and abrasion tests of a nickel-less electroplated product of the prior art



    [0044] An electroplated nickel-less product of the prior art comprises the following layers electrolytically deposited on a brass substrate:
    bright copper layer: 10 µm
    white bronze layer: 2 µm
    gold layer as finishing layer: 0.5 µm


    [0045] Said electroplated nickel-free product has the following properties:
    NFS 80772: 12 HOURS;
    ABRASION WITH TURBULA: 5 MINUTES
    LEATHER INTERACTION UNDER ISO 4611: 48-72 HOURS;
    ISO 4538: 48 HOURS;
    ISO 4524/2: 8 HOURS;
    ISO 4611: 96 HOURS;
    ABRASION TEST BY TURBULA UNDER ISO 23160: no color change after 30 min.


    [0046] Thus, the performance in some of the tests is reduced compared to the nickel-containing electroplated product.

    [0047] The reason for which the bronze layer is very thin is related with the level of quality of bronze plating processes known in the prior art that do not allow exceeding 2 µm of the deposit while maintaining the desired bright aspect. In other words, this is the reason why thicker deposits of white bronze are undesirable for the jewelry and/or fashion industry because of a lack of brightness.

    [0048] Due to the fact that the precious metal layers are regularly a very thin deposit (approx. 0.5 µm), it is easy for corrosive media or mechanical action to reach the underlying bronze layer. Said bronze layer is softer than nickel and has a slightly lower thickness. Thus, it is less resistant to mechanical stress and can be damaged easily. Upon damage of the white bronze layer, the underlying copper layer will appear and be exposed to the atmosphere and oxidation. For these reasons, the nickel-free plated parts are more easily damaged by aggressive media, like leather and the acid sweat of human skin.

    Example 5 - Performance in corrosion and abrasion tests of a nickel-containing electroplated product of the prior art having a palladium-nickel intermediate layer



    [0049] An electroplated nickel-containing product of the prior art comprises the following layers electrolytically deposited on a brass substrate:
    bright copper layer: 10 µm
    white bronze layer: 2 µm
    palladium-nickel layer: 0.3 µm
    gold layer as finishing layer: 0.5 µm


    [0050] Said electroplated nickel-free product has the following properties:
    NFS 80772: 24 HOURS;
    ABRASION WITH TURBULA: 5 MINUTES
    LEATHER INTERACTION UNDER ISO 4611: 48-72 HOURS;
    ISO 4538: 48 HOURS;
    ISO 4524/2: 8 HOURS;
    ISO 4611: 96 HOURS;
    ABRASION TEST BY TURBULA UNDER ISO 23160: change of color in article edges more exposed to abrasion (copper color)


    [0051] In fact, even a palladium intermediate layer with only 0.3 µm thickness increases the performance in the NFS 80772 test from 12 hours to almost 24 hours. However, the disadvantage of having said palladium intermediate layer is that the electroplating of the substrates is cost-intensive.

    Example 6 - Performance in corrosion and abrasion tests of a nickel-less electroplated product



    [0052] A first example of an electroplated nickel-less product comprises the following layers electrolytically deposited on a brass substrate:
    bright copper layer: 10 µm
    white bronze layer (Cu:Sn:Zn = 40:40:20): 2-4 µm
    yellow bronze layer (Cu:Sn:Zn = 70:20:10): 3-4 µm
    gold layer as finishing layer: 0.5 µm


    [0053] A second example of an electroplated nickel-less product comprises the following layers electrolytically deposited on a brass substrate:
    bright copper layer: 10 µm
    yellow bronze layer (Cu:Sn:Zn = 70:20:10): 3-4 µm
    white bronze layer (Cu:Sn:Zn = 40:40:20): 2-3 µm
    palladium layer as finishing layer: 0.5 µm


    [0054] The electroplated nickel-free products of the first and second example have the following properties:
    NFS 80772: 24 HOURS;
    ABRASION WITH TURBULA: 5 MINUTES
    LEATHER INTERACTION UNDER ISO 4611: 96 HOURS;
    ISO 4538: 48 HOURS;
    ISO 4524/2: 8 HOURS;
    ISO 4611: 96 HOURS;
    ABRASION TEST BY TURBULA UNDER ISO 23160: no color change after 30 min.


    [0055] Thus, the improvement of performance is essentially related to the protection of the copper underlayer on the one hand and to the conservation of the quality of the top gold layer on the other hand by the presence of both the white and yellow bronze layer.

    Example 7 - Performance in corrosion and abrasion tests of a nickel-less electroplated product - assessing the influence of the sequence of the bronze layers



    [0056] A white bronze layer is deposited next to the gold layer and a yellow bronze layer is deposited next to the bright copper layer i.e. the electroplated nickel-less product comprises the following layers electrolytically deposited on a brass (indicated relations of the elements in the bronze layer are in weight-%):
    bright copper layer: >10 µm
    yellow bronze layer (Cu:Sn:Zn = 80:15:05): 2-3 µm
    white bronze layer (Cu:Sn:Zn = 50:35:15): 2-3 µm
    gold layer as finishing layer: 0.5 µm


    [0057] The electroplated nickel-free product has the following properties:
    NFS 80772: 12 HOURS;
    ABRASION WITH TURBULA: 3 MINUTES
    LEATHER INTERACTION UNDER ISO 4611: 56 HOURS;
    ABRASION TEST BY TURBULA UNDER ISO 23160: no color change after 60 min.


    [0058] The properties of the electroplated nickel-free product obtained for the plating sequence of example 4 are better than the properties obtained for the plating sequence of this example, showing that the sequence bright copper/yellow bronze/white bronze is less adapted as underlayer of gold than the sequence copper/white bronze/yellow bronze. The present sequence is more adapted as an underlayer of Palladium as final finish.

    Example 8 - Performance in corrosion and abrasion tests of two non-inventive nickel-less electroplated product - assessing the significance of the difference in copper concentration of the bronze layers



    [0059] In a first assay, next to the gold layer and next to the bright copper layer a white bronze layer with identical composition is deposited i.e. the electroplated nickel-less product comprises the following layers electrolytically deposited on a brass (indicated relations of the elements in the bronze layer are in weight-%):
    bright copper layer: >10 µm
    white bronze layer (Cu:Sn:Zn = 50:35:15): 2-3 µm
    white bronze layer (Cu:Sn:Zn = 50:35:15): 2-3 µm
    gold layer as finishing layer: 0.5 µm


    [0060] The electroplated nickel-free product has the following properties:
    NFS 80772: 12 HOURS;
    ABRASION WITH TURBULA: 3 MINUTES
    LEATHER INTERACTION UNDER ISO 4611: 48 HOURS;
    ABRASION TEST BY TURBULA UNDER ISO 23160: no color change after 60 min.


    [0061] In a second assay, next to the gold layer and next to the bright copper layer a yellow bronze layer with identical composition is deposited i.e. the electroplated nickel-less product comprises the following layers electrolytically deposited on a brass substrate (indicated relations of the elements in the bronze layer are in weight-%):
    bright copper layer: >10 µm)
    yellow bronze layer (Cu:Sn:Zn = 80:15:05): 2-3 µm
    yellow bronze layer (Cu:Sn:Zn = 80:15:05): 2-3 µm
    gold layer as finishing layer: 0.5 µm


    [0062] The electroplated nickel-free product has the following properties:
    NFS 80772: 6 HOURS;
    ABRASION WITH TURBULA: 3 MINUTES
    LEATHER INTERACTION UNDER ISO 4611: 48 HOURS;
    ABRASION TEST BY TURBULA UNDER ISO 23160: no color change after 120 min.


    [0063] From this experiment, it is evident that if two bronze layers with identical copper concentration (either two white bronze layers or two yellow bronze layers) are deposited, the corrosion resistance of the resulting substrate is worse than if the two bronze layers with different copper concentration are deposited. In addition, it can be observed that plating two white bronze layers provides better corrosion protection than plating two yellow bronze layers. This indicates that the worse corrosion protection observed may be caused by a higher copper content in the gold finishing layer of the final substrate due to copper migration into said layer.

    Example 9 - Corrosion and abrasion resistance of an electroplated article which comprises a palladium alloy as intermediate layer



    [0064] Zamac is massively used in the luxury industry due to its low cost: compared to brass, the proportion between copper and zinc are opposed and the massive object contains mainly zinc. The zinc potential of corrosion is lower than copper and reduces the "nobility" of the final article.

    [0065] On the other hand, the final object to be electroplated is stamped starting from ingots with low compactness. The stamping step will compress the material, but porosity remains and is uncontrollable during the stamping process.

    [0066] The galvanic sequence will have to protect the material either from the attacks coming from outside (such as oxidizing medias), but also from the inside considering holes residues for the original ingot and the stamping process. The stamping process will concentrate the pores in the thickness of the final article but as it happens frequently, the base material external composition presents low porosity density close to the galvanic treatment.

    [0067] The use of a poorly resistant substrate as a base material is then problematic, even more in the case that the substrate has a porous composition like zamak. In fact, cavity corrosion can occur in the pores which alters the visual aspect of the electroplated article.

    [0068] This is a reference example as the electroplated article contains a palladium layer as intermediate layer.

    [0069] The ageing useful to evaluate abrasion and corrosion resistance is in line with the following parameters:
    • TURBULA® set at 62 rounds/min (three-dimensional movement) and a container with a capacity of 2L;
    • Ceramic abrasive: 2.5 kg, supplier* ROSLER RS06/06S (angle cutting)


    [0070] This example describes the known use of a precious metal such as palladium as intermediate layer to save production costs compared to the expensive gold finishing. This example of an electroplated nickel-less product comprises the following layers electrolytically deposited on a zamak substrate:
    copper layer: > 15 µm (30 - 50 µm)
    bronze layer (Cu-Sn-Zn alloy layer): 3 µm
    palladium alloy layer (nickel-free): 0.5 µm
    gold layer: 0.5 microns


    [0071] This use of a palladium alloy layer is expensive in terms of final thickness of precious metal. On the other side, the hydrogen embrittlement that occurs during palladium plating will raise the risk of under-layer cracking during ageing due to the close distance between pores of the substrate and holes left by hydrogen release.

    [0072] The electroplated article was submitted to the synthetic sweat resistance test (performed following NFS 80772 standard with ageing).

    [0073] Globally, it turned out that the gold surface seems to be covered by copper after 24 hours of sweat interaction.

    [0074] After an analysis with an optical microscope, it has turned out that before the synthetic sweat resistance test, there were holes visible on the surface. After said test, the holes were enlarged compared to before the test an oxidation was visible. In addition, copper covers the tested article (red stains are formed on top of gold in contact with the synthetic sweat). Due to the difference of potential of corrosion between the first copper layer and zinc as the main component of the substrate, the "battery effect" occurs and copper is dissolved.

    [0075] Synthetic sweat is a conductive liquid. It will transport copper ions until the precious metal finishing where the opposite phenomenon happens and copper ions are reduced. This phenomenon is enhanced by the difference of corrosion potential between the substrate and the first copper layer and the presence of palladium below the gold layer due to high nobility of the final galvanic treatments. In fact, the presence of a Palladium layer between the copper layer and the gold layer enhances the copper dissolution rate.

    [0076] An electron microscope allows the identification of the chemical composition of the surface of an article.

    [0077] When viewing the electroplated article under an electron microscope before the synthetic sweat resistance test, it was observed that the surface of the article is mechanically altered, some open pores are visible with the mechanical alteration and the gold is the main element detected with mapping analysis.

    [0078] When the same article was viewed after said test, it was observed that gold was missing at a distance of 100 µm around the hole which indicates that the base material is directly exposed to the oxidizing media. It was also observed that the strong synthetic sweat testing conditions create a stressed area between the porous substrate and the hydrogen present in the palladium. Due to the noble finishing and the substrate sensitive to corrosion, the copper is electrochemically dissolved. Through conductive synthetic sweat, dissolved copper ions are reduced on top of gold by potentiometric difference.

    [0079] Table 1 below is a summary of the chemical composition obtained by EDS measurement located at the surface of the electroplated article before synthetic sweat interaction, on copper reduced areas and on oxidized areas.
    Table 1
     before sweat interactionafter sweat interaction
     unaltered areas (copper reduced areas)altered areas (oxidized areas)
    Au 82 wt.% 75 wt.% 0 wt.%
    Pd 10 wt.% 10 wt.% 0 wt.%
    Cu 5 wt.% 5 wt.% 5 wt.%
    Sn - - 2 wt.%
    Zn 3 wt.% 2 wt.% 55 wt.%
    O - 8 wt.% 38 wt.%

    Example 10 - Corrosion and abrasion resistance of an electroplated article having a substrate with high zinc content and low thickness of first copper layer



    [0080] This is a reference example as the thickness of the first copper layer is maximally 15 µm.

    [0081] The ageing useful to evaluate abrasion and corrosion resistance is in line with the following parameters:
    • TURBULA® set at 62 rounds/min (three-dimensional movement) and a container with a capacity of 2L;
    • Ceramic abrasive: 2.5 kg, supplier* ROSLER RS06/06S (angle cutting)


    [0082] This example describes a sequence on zamak with a copper thickness lower than 15 µm. The zamak alloy is mainly composed of zinc (around 70 - 80%). Zinc being soluble in most acids, an interaction with the synthetic sweat would directly destroy the base material. This example of an electroplated nickel-less product comprises the following layers electrolytically deposited on a zinc alloy (zamak) substrate:
    copper layer: ≤ 15 µm (8 - 15 µm)
    white bronze layer (Cu-Sn-Zn alloy layer): 3 µm
    yellow bronze layer (Cu-Sn-Zn alloy layer): 3 µm
    gold layer: 0.5 microns


    [0083] The properties of the deposited white bronze layer and yellow bronze layer are summarized in Table 2.
    Table 2
     white bronze layeryellow bronze layer
    colour of the layerwhiteyellow
    %Cu 46 - 49 wt.% 75 - 85 wt.%
    %Sn 40 - 45 wt.% 15 - 20 wt.%
    %Zn 10 - 15 wt.% 2 - 7 wt.%
    density of the alloy 8.3 g/cm3 8.1 g/cm3


    [0084] Ageing of the electroplated articles was performed applying 3 minutes of TURBULA®. The electroplated article was submitted to the synthetic sweat resistance test (performed following NFS 80772 standard with ageing).

    [0085] An improvement compared to the plating sequence in Example 9 was observed: Compared to example 9, the reduction of copper did not occur on the whole surface but rather only locally.

    [0086] The analysis with the optical microscope showed that copper seems to be locally dissolved and reduced on the gold finishing, but this phenomenon remains localized.

    [0087] An analysis with the electron microscope allows the identification of the chemical composition of the surface before and after synthetic sweat resistance test on article submitted to ageing before the interaction with sweat. This analysis was performed with the electroplated articles. It was observed that the opening of holes in the substrate occurs like observed in Example 9, but a different behavior is observed. In fact, corrosion is only located around the holes and does not spread on the entire gold finishing surface. Moreover, copper dissolution is limited which is most likely due to the substitution of the palladium intermediate layer. As a consequence, the final galvanic treatment is globally less noble. Copper dissolution can happen between substrate and the first copper layer, but copper reduction was observed to slow down on the external surface of the article.

    [0088] Table 3 below is a summary of the chemical composition located at the surface of the electroplated article before synthetic sweat interaction, on copper reduced areas and on oxidized areas.
    Table 3
     before sweat interactionafter sweat interaction
    unaltered areas (copper reduced areas)altered areas (oxidized areas)
    Au 95 wt.% 88 wt.% 0 wt.%
    Cu 3 wt.% 5 wt.% 5 wt.%
    Sn - - 2 wt.%
    Zn 2 wt.% 2 wt.% 55 wt.%
    O - 5 wt.% 38 wt.%

    Example 11 - Corrosion and abrasion resistance of an electroplated article having a substrate with high zinc content and high thickness of first copper layer



    [0089] This is an example according to the invention as the thickness of the first copper layer is more than 15 µm.

    [0090] The ageing useful to evaluate abrasion and corrosion resistance is in line with the following parameters:
    • TURBULA® set at 62 rounds/min (three-dimensional movement) and a container with a capacity of 2L;
    • Ceramic abrasive: 2.5 kg, supplier* ROSLER RS06/06S (angle cutting)


    [0091] This example describes a sequence on zamak with a copper thickness of more than 15 µm. The zamak alloy is mainly composed of zinc (around 70 - 80%). Zinc being soluble in most acids, an interaction with the synthetic sweat would directly destroy the base material. This example of an electroplated nickel-less product comprises the following layers electrolytically deposited on a zinc alloy (zamak) substrate:
    copper layer: > 15 µm (30 - 50 µm)
    white bronze layer (Cu-Sn-Zn alloy layer): 3 µm
    yellow bronze layer (Cu-Sn-Zn alloy layer): 3 µm
    gold layer: 0.5 microns


    [0092] The properties of the deposited white bronze layer and yellow bronze layer are summarized in Table 4.
    Table 4
     white bronze layeryellow bronze layer
    colour of the layerwhiteyellow
    %Cu 46 - 49 wt.% 75 - 85 wt.%
    %Sn 40 - 45 wt.% 15 - 20 wt.%
    %Zn 10 - 15 wt.% 2 - 7 wt.%
    density of the alloy 8.3 g/cm3 8.1 g/cm3


    [0093] The electroplated article was submitted to the synthetic sweat resistance test (performed following NFS 80772 standard with ageing).

    [0094] Indeed, it was discovered that by combining a copper layer thickness of more than 15 µm with the sequence consisting of the double bronze combination followed by the precious metal final layer led to a raise in the resistance performance. Specifically, it was observed that the synthetic sweat test opens the holes created by the TURBULA® treatment, but no detrimental consequences occur. In fact, it turned out that the copper of the copper layer is not dissolved by synthetic sweat and the electroplated article remains unchanged after 24 hours in contact with synthetic sweat. Despite the articles presenting mechanical alteration, no chemical oxidation is visible.

    [0095] Moreover, the chemical analysis of the surface of the electroplated article confirms that there are no sign of corrosion. Firstly, only the metals are detected i.e. no oxygen from corrosion is seen and the composition is unchanged. Secondly, the electron microscope (SEM) pictures before and after the corrosion test are identical and show no sign of corrosion on the surface after the synthetic sweat interaction for 24 hours.

    [0096] Table 5 below is a summary of the chemical composition located at the surface of the electroplated article before synthetic sweat interaction and after the synthetic sweat interaction.
    Table 5 n/o: no altered areas observed
     before sweat interactionafter sweat interaction
    unaltered areas (copper reduced areas)altered areas (oxidized areas)
    Au 96 wt.% 95.6 wt.% n/o
    Cu 2 wt.% 2.6 wt.%
    Sn - -
    Zn 2 wt.% 1.2 wt.%
    O - -


    [0097] In Table 6 below the galvanic sequences applied on the zinc alloy as base material are reported
    Table 6
     Example 9Example 10Example 11
    Substrate zamak zamak zamak
    First Copper layer copper: 30-50 microns copper: 8 - 15 microns copper: 30 - 50 microns
    Second layer white bronze alloy white bronze alloy white bronze alloy
    46 - 49 wt.-% Cu 46 - 49 wt.-% Cu 46 - 49 wt.-% Cu
    40 - 45 wt.-% Sn 40 - 45 wt.-% Sn 40 - 45 wt.-% Sn
    10 - 15 wt.-% Zn 10 - 15 wt.-% Zn 10 - 15 wt.-% Zn
    2.5 microns 2.5 microns 2.5 microns
    Third layer palladium alloy 0.5 micron yellow bronze alloy yellow bronze alloy
    75 - 85 wt.-% Cu 75 - 85 wt.-% Cu
    15 - 20 wt.-% Sn 15 - 20 wt.-% Sn
    2 - 7 wt.-% Zn 2 - 7 wt.-% Zn
    2.5 microns 2.5 microns
    Finishing Gold Gold Gold
    0.5 micron 0.5 micron 0.5 micron


    [0098] Table 7 below summarizes the obtained data regarding the electroplated articles of Examples 9 to 11.
    Table 7
     Example 9Example 10Example 11
    sweat resistance negative negative positive
    global aspect after sweat interaction surface covered by copper reduction from the first layer local opening of holes from the substrate which lead to their oxidation local opening of holes without oxidation
    EDS analysis of the global surface oxygen content is raised oxygen content is raised element concentration does not change
    EDS analysis on localized defect mainly zinc and oxygen mainly zinc and oxygen no defect



    Claims

    1. Electroplated product, comprising

    a) a base material;

    b) a first layer comprising or consisting of copper, wherein the first layer is disposed on the base material;

    c) a second layer comprising or consisting of a first copper alloy, wherein the first copper alloy comprises tin and zinc;

    d) a third layer comprising or consisting of a second copper alloy, wherein the second copper alloy comprises tin and zinc; and

    e) a fourth layer comprising or consisting of a precious metal, wherein the precious metal is selected from the group consisting of gold, silver, platinum, ruthenium, rhodium, palladium, osmium, iridium and alloys thereof;

    wherein

    i) the second layer is disposed on the first layer, the third layer is disposed on the second layer and the fourth layer is disposed on the third layer; or

    ii) the third layer is disposed on the first layer, the second layer is disposed on the third layer and the fourth layer is disposed on the second layer;

    and wherein the copper concentration in the first copper alloy is different from the copper concentration in the second copper alloy,
    characterized in that the fourth layer is the finishing metal layer of the electroplated product, and the first layer has a thickness in the range of >15 to 60 µm.
     
    2. Electroplated product according to claim 1, characterized in that the copper concentration in the second alloy is higher than the copper concentration in the first alloy.
     
    3. Electroplated product according to one of the preceding claims, characterized in that the copper concentration of the first copper alloy differs from the copper concentration of the second copper alloy by an absolute value of 1 to 99 wt.-%, preferably 5 to 80 wt.-%, more preferably 10 to 60 wt.-%, even more preferably 15 to 40 wt.-%, most prefer ably 20 to 30 wt.-%,
     
    4. Electroplated product according to one of the preceding claims, characterized in that the copper concentration in the

    i) first copper alloy is ≤ 65 wt.-%, preferably 30 to 64 wt.-%, more preferably 40 to 60 wt.-%, most preferably 45 to 55 wt.-%, in relation to the whole weight of the copper alloy; and/or

    ii) the second copper alloy is ≥ 66 wt.-%, preferably 66 to 90 wt.-%, more preferably 70 to 87 wt.-%, most preferably 75 to 85 wt.-%, in relation to the whole weight of the copper alloy.


     
    5. Electroplated product according to one of the preceding claims, characterized in that the zinc concentration in the

    i) first copper alloy is ≥ 10 wt.-%, preferably 11 to 35 wt.-%, more preferably 12 to 25 wt,-%, most preferably 15 to 20 wt.-%, in relation to the whole weight of the copper alloy; and/or

    ii) the second copper alloy may be ≤ 15 wt.-%, preferably 2 to 10 wt.-%, more preferably 3 to 8 wt.-%, most preferably 4 to 7 wt.-%, in relation to the whole weight of the copper alloy.


     
    6. Electroplated product according to one of the preceding claims, characterized in that the tin concentration in the

    i) first copper alloy may be ≥ 26 wt.-%, preferably 26 to 35 wt.-%, in relation to the whole weight of the copper alloy; and/or

    ii) the second copper alloy may be ≤ 25 wt.-%, preferably 1 to 25 wt.-%, more preferably 10 to 25 wt.-%, most preferably 15 to 25 wt.-%, in relation to the whole weight of the copper alloy.


     
    7. Electroplated product according to one of the preceding claims, characterized in that the first copper alloy and/or the second copper alloy comprises Bi, Pb and/or Sb, preferably Bi.
     
    8. Electroplated product according to one of the preceding claims, characterized in that the fourth layer is disposed on the second or third layer.
     
    9. Electroplated product according to one of the preceding claims, characterized in that there is no layer comprising or consisting of palladium between the first layer and fourth layer, wherein the electroplated product preferably does not comprise palladium.
     
    10. Electroplated product according to one of the preceding claims, characterized in that there is no layer comprising or consisting of nickel, cobalt and/or chromium between the first layer and fourth, wherein the electroplated product preferably does not comprise nickel, cobalt and/or chromium, most preferably no nickel.
     
    11. Electroplated product according to one of the preceding claims, characterized in that an organic protection layer is disposed on the fourth layer, preferably a layer comprising or consisting of a hydrophobic substance, more preferably a monolayer of a hydrophobic substance, even more preferably a monolayer of a hydrophobic substance being a corrosion inhibitor, most preferably a monolayer of a hydrophobic substance comprising thiol groups, especially a monolayer of alkanethiol monomers or alkanethiol polymers.
     
    12. Electroplated product according to one of the preceding claims, characterized in that the precious metal is selected from the group consisting of gold, silver, palladium and alloys thereof, more preferably gold, palladium and alloys thereof, most preferably gold.
     
    13. Electroplated product according to one of the preceding claims, characterized in that the base material comprises or consists of bronze, brass, zamak, alpaca, copper alloy, tin alloy and/or steel, preferably comprises or consists of zamak.
     
    14. Electroplated product according to one of the preceding claims, characterized in that the thickness of

    i) the first layer is 16 to 60 µm, preferably 20 to 55 µm, more preferably 25 to 50 µm, most preferably 30 to 45 µm;

    ii) the second layer is 1 to 10 µm, preferably 2 to 8 µm ;

    iii) the third layer is 1 to 10 µm, preferably 2 to 4 µm; and/or

    iv) the fourth layer is 0.1 to 5 µm, preferably 0.2 to 1 µm.


     
    15. Method of producing an electroplated product according to one of the preceding claims, comprising the steps:

    a) electroplating a layer comprising or consisting of the first copper alloy on a copper layer disposed on a substrate;

    b) electroplating a layer comprising or consisting of the second copper alloy on the layer of step a);

    c) electroplating a layer comprising or consisting of the precious metal on the layer of step b),

    wherein the first copper alloy layer is plated with a copper concentration different from that of the second copper alloy layer.
     
    16. Use of the electroplated product according to one of claims 1 to 14 in the jewelry industry, fashion industry, leather industry, watch industry, eyewear industry, trinkets industry and/or lock industry.
     


    Ansprüche

    1. Galvanisch beschichtetes Produkt, umfassend

    a) ein Grundmaterial;

    b) eine erste Schicht, enthaltend oder bestehend aus Kupfer, wobei die erste Schicht auf dem Basismaterial angeordnet ist;

    c) eine zweite Schicht, enthaltend oder bestehend aus einer ersten Kupferlegierung, wobei die erste Kupferlegierung Zinn und Zink enthält;

    d) eine dritte Schicht, enthaltend oder bestehend aus einer zweiten Kupferlegierung, wobei die zweite Kupferlegierung Zinn und Zink enthält; und

    e) eine vierte Schicht, enthaltend oder bestehend aus einem Edelmetall, wobei das Edelmetall ausgewählt ist aus der Gruppe bestehend aus Gold, Silber, Platin, Ruthenium, Rhodium, Palladium, Osmium, Iridium und deren Legierungen;

    wobei

    i) die zweite Schicht auf der ersten Schicht angeordnet ist, die dritte Schicht auf der zweiten Schicht angeordnet ist und die vierte Schicht auf der dritten Schicht angeordnet ist; oder

    ii) die dritte Schicht auf der ersten Schicht angeordnet ist, die zweite Schicht auf der dritten Schicht angeordnet ist und die vierte Schicht auf der zweiten Schicht angeordnet ist;

    und wobei sich die Kupferkonzentration in der ersten Kupferlegierung von der Kupferkonzentration in der zweiten Kupferlegierung unterscheidet,
    dadurch gekennzeichnet, dass die vierte Schicht die abschließende Metallschicht des galvanisch beschichteten Produkts ist,
    und die erste Schicht eine Dicke im Bereich von >15 bis 60 µm aufweist.
     
    2. Galvanisch beschichtetes Produkt nach Anspruch 1, dadurch gekennzeichnet, dass die Kupferkonzentration in der zweiten Legierung höher ist als die Kupferkonzentration in der ersten Legierung.
     
    3. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass sich die Kupferkonzentration der ersten Kupferlegierung von der Kupferkonzentration der zweiten Kupferlegierung um einen Absolutwert von 1 bis 99 Gew.-%, vorzugsweise 5 bis 80 Gew.-%, bevorzugter 10 bis 60 Gew.-%, noch bevorzugter 15 bis 40 Gew.-%, besonders bevorzugt 20 bis 30 Gew.-%, unterscheidet.
     
    4. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Kupferkonzentration in der

    i) ersten Kupferlegierung ≤ 65 Gew.-%, vorzugsweise 30 bis 64 Gew.-%, bevorzugter 40 bis 60 Gew.-%, besonders bevorzugt 45 bis 55 Gew.-%, in Bezug auf das Gesamtgewicht der Kupferlegierung beträgt; und/oder

    ii) der zweiten Kupferlegierung ≥ 66 Gew.-%, vorzugsweise 66 bis 90 Gew.-%, bevorzugter 70 bis 87 Gew.-%, besonders bevorzugt 75 bis 85 Gew.-%, in Bezug auf das Gesamtgewicht der Kupferlegierung beträgt.


     
    5. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Zinkkonzentration in der

    i) ersten Kupferlegierung ≥ 10 Gew.-%, vorzugsweise 11 bis 35 Gew.-%, bevorzugter 12 bis 25 Gew.-%, besonders bevorzugt 15 bis 20 Gew.-%, in Bezug auf das Gesamtgewicht der Kupferlegierung beträgt; und/oder

    ii) die zweite Kupferlegierung ≤ 15 Gew.-%, vorzugsweise 2 bis 10 Gew.-%, bevorzugter 3 bis 8 Gew.-%, besonders bevorzugt 4 bis 7 Gew.-%, in Bezug auf das Gesamtgewicht der Kupferlegierung betragen kann.


     
    6. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Zinnkonzentration in der

    i) ersten Kupferlegierung ≥ 26 Gew.-%, vorzugsweise 26 bis 35 Gew.-%, in Bezug auf das Gesamtgewicht der Kupferlegierung betragen kann; und/oder

    ii) die zweite Kupferlegierung ≤ 25 Gew.-%, vorzugsweise 1 bis 25 Gew.-%, bevorzugter 10 bis 25 Gew.-%, besonders bevorzugt 15 bis 25 Gew.- %, in Bezug auf das Gesamtgewicht der Kupferlegierung betragen kann.


     
    7. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die erste Kupferlegierung und/oder die zweite Kupferlegierung Bi, Pb und/oder Sb, vorzugsweise Bi, enthält.
     
    8. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die vierte Schicht auf der zweiten oder dritten Schicht angeordnet ist.
     
    9. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass keine Schicht, enthaltend oder bestehend aus Palladium, zwischen der ersten Schicht und der vierten Schicht vorhanden ist, wobei das galvanisch beschichtete Produkt vorzugsweise kein Palladium enthält.
     
    10. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass keine Schicht, enthaltend oder bestehend aus Nickel, Kobalt und/oder Chrom, zwischen der ersten Schicht und der vierten Schicht vorhanden ist, wobei das galvanisch beschichtete Produkt vorzugsweise kein Nickel, Kobalt und/oder Chrom, besonders bevorzugt kein Nickel, enthält.
     
    11. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass auf der vierten Schicht eine organische Schutzschicht angeordnet ist, vorzugsweise eine Schicht, enthaltend oder bestehend aus einer hydrophoben Substanz, bevorzugter eine Monoschicht aus einer hydrophoben Substanz, noch bevorzugter eine Monoschicht aus einer hydrophoben Substanz, die ein Korrosionsinhibitor ist, besonders bevorzugt eine Monoschicht aus einer hydrophoben Substanz, umfassend Thiolgruppen, insbesondere eine Monoschicht aus Alkanethiol-Monomeren oder Alkanethiol-Polymeren.
     
    12. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Edelmetall ausgewählt ist aus der Gruppe bestehend aus Gold, Silber, Palladium und deren Legierungen, bevorzugter Gold, Palladium und deren Legierungen, besonders bevorzugt Gold.
     
    13. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass das Grundmaterial aus Bronze, Messing, Zamak, Alpaka, Kupferlegierung, Zinnlegierung und/oder Stahl enthält oder daraus besteht, vorzugsweise Zamak enthält oder daraus besteht.
     
    14. Galvanisch beschichtetes Produkt nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, dass die Dicke

    i) der ersten Schicht 16 bis 60 µm, vorzugsweise 20 bis 55 µm, bevorzugter 25 bis 50 µm, besonders bevorzugt 30 bis 45 µm beträgt;

    ii) der zweiten Schicht 1 bis 10 µm, vorzugsweise 2 bis 8 µm, beträgt;

    iii) der dritten Schicht 1 bis 10 µm, vorzugsweise 2 bis 4 µm beträgt; und/oder

    iv) der vierten Schicht 0,1 bis 5 µm, vorzugsweise 0,2 bis 1 µm, beträgt.


     
    15. Verfahren des Herstellens eines galvanisch beschichteten Produkts nach einem der vorangehenden Ansprüche, umfassend die Schritte:

    a) Galvanische Abscheidung einer Schicht, enthaltend oder bestehend aus der ersten Kupferlegierung, auf eine Kupferschicht, die auf einem Substrat angeordnet ist;

    b) Galvanische Abscheidung einer Schicht, enthaltend oder bestehend aus der zweiten Kupferlegierung, auf die Schicht von Schritt a);

    c) Galvanische Abscheidung einer Schicht, enthaltend oder bestehend aus dem Edelmetall, auf die Schicht von Schritt b),
    wobei die erste Kupferlegierungsschicht mit einer Kupferkonzentration plattiert ist, die sich von der der zweiten Kupferlegierungsschicht unterscheidet.


     
    16. Verwendung des galvanisch beschichteten Produkts nach einem der Ansprüche 1 bis 14 in der Schmuckindustrie, Modeindustrie, Lederindustrie, Uhrenindustrie, Brillenindustrie, Modeschmuckindustrie und/oder Türschlossindustrie.
     


    Revendications

    1. Produit plaqué, comprenant

    a) un matériau de base ;

    b) une première couche comprenant du, ou constituée de, cuivre, où la première couche est disposée sur le matériau de base ;

    c) une deuxième couche comprenant un, ou constituée d'un, premier alliage de cuivre, où le premier alliage de cuivre comprend de l'étain et du zinc ;

    d) une troisième couche comprenant un, ou constituée d'un, second alliage de cuivre, où le second alliage de cuivre comprend de l'étain et du zinc ; et

    e) une quatrième couche comprenant un, ou constituée d'un, métal précieux, où le métal précieux est sélectionné dans le groupe constitué par l'or, l'argent, le platine, le ruthénium, le rhodium, le palladium, l'osmium, l'iridium et des alliages de ceux-ci ;

    i) la deuxième couche est disposée sur la première couche, la troisième couche est disposée sur la deuxième couche, et la quatrième couche est disposée sur la troisième couche ; ou

    ii) la troisième couche est disposée sur la première couche, la deuxième couche est disposée sur la troisième couche, et la quatrième couche est disposée sur la deuxième couche ;

    et où la concentration en cuivre dans le premier alliage de cuivre, est différente de la concentration en cuivre dans le second alliage de cuivre,
    caractérisé en ce que
    la quatrième couche est la couche métallique de finition du produit plaqué,
    et la première couche présente une épaisseur comprise entre15 et 60 µm.
     
    2. Produit plaqué selon la revendication 1, caractérisé en ce que la concentration en cuivre dans le second alliage, est supérieure à la concentration en cuivre dans le premier alliage.
     
    3. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce que la concentration en cuivre du premier alliage de cuivre, diffère de la concentration en cuivre du second alliage de cuivre, d'une valeur absolue comprise entre 1 et 99 % en poids, de préférence entre 5 et 80 % en poids, mieux entre 10 et 60 % en poids, mieux encore entre 15 et 40 % en poids, l'idéal étant entre 20 et 30 % en poids.
     
    4. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce que la concentration en cuivre dans

    i) le premier alliage de cuivre, est ≤ 65 % en poids, de préférence compris entre 30 et 64 % en poids, mieux entre 40 et 60 % en poids, mieux encore entre 45 et 55 % en poids, par rapport au poids total de l'alliage de cuivre ; et / ou

    ii) le second alliage de cuivre, est ≥ 66 % en poids, de préférence compris entre 66 et 90 % en poids, mieux entre 70 et 87 % en poids, mieux encore entre 75 et 85 % en poids, par rapport au poids total de l'alliage de cuivre.


     
    5. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce que la concentration en zinc dans

    i) le premier alliage de cuivre, est ≥ 10 % en poids, de préférence compris entre 11 et 35 % en poids, mieux entre 12 et 25 % en poids, mieux encore entre 15 et 20 % en poids, par rapport au poids total de l'alliage de cuivre ; et / ou

    ii) le second alliage de cuivre, peut être ≤ 15 % en poids, de préférence compris entre 2 et 10 % en poids, mieux entre 3 et 8 % en poids, mieux encore entre 4 et 7 % en poids, par rapport au poids total de l'alliage de cuivre.


     
    6. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce que la concentration en étain dans

    i) le premier alliage de cuivre, peut être ≥ 26 % en poids, de préférence compris entre 26 et 35 en % poids, par rapport au poids total de l'alliage de cuivre ; et / ou

    ii) le second alliage de cuivre, peut être ≤ 25 % en poids, de préférence compris entre 1 et 25 % en poids, mieux entre 10 et 25 % en poids, mieux encore entre 15 et 25 % en poids, par rapport au poids total de l'alliage de cuivre.


     
    7. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce que le premier alliage de cuivre et / ou le second alliage de cuivre comprend du Bi, du Pb et / ou du Sb, de préférence du Bi.
     
    8. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce que la quatrième couche est disposée sur la deuxième ou sur la troisième couche.
     
    9. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce qu'aucune couche ne comprend du, ou n'est constituée de, palladium entre la première couche et la quatrième couche, où le produit plaqué ne comprend de préférence pas de palladium.
     
    10. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce qu'aucune couche ne comprend du, ou n'est constituée de, nickel, de cobalt et / ou de chrome, entre la première couche et la quatrième couche, où le produit plaqué ne comprend de préférence ni nickel, ni cobalt et / ou ni chrome, mieux encore pas de nickel.
     
    11. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce qu'une couche de protection organique est disposée sur la quatrième couche, de préférence une couche comprenant une, ou constituée d'une, substance hydrophobe, de préférence une monocouche d'une substance hydrophobe, mieux une monocouche d'une substance hydrophobe d'inhibition de la corrosion, mieux encore une monocouche d'une substance hydrophobe constituée de groupes thiols, en particulier une monocouche de monomères d'alcanethiols ou de polymères d'alcanethiols.
     
    12. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce que le métal précieux est sélectionné dans le groupe constitué par l'or, l'argent, le palladium et des alliages de ceux-ci, mieux constitué par l'or, le palladium et des alliages de ceux-ci, mieux encore constitué par l'or.
     
    13. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce que le matériau de base comprend du, ou est constitué de, bronze, laiton, zamak, alpaga, alliage de cuivre, alliage d'étain et / ou acier, de préférence il comprend du, ou est constitué de, zamak.
     
    14. Produit plaqué selon l'une quelconque des revendications précédentes, caractérisé en ce que l'épaisseur de

    i) la première couche, est comprise entre 16 et 60 µm, de préférence entre 20 et 55 µm, mieux entre 25 et 50 µm, mieux encore entre 30 et 45 µm ;

    ii) la deuxième couche, est comprise entre 1 et 10 µm, de préférence entre 2 et 8 µm ;

    iii) la troisième couche, est comprise entre 1 et 10 µm, de préférence entre 2 et 4 µm ; et / ou

    iv) la quatrième couche, est comprise entre 0,1 et 5 µm, de préférence entre 0,2 et 1 µm.


     
    15. Procédé destiné à produire un produit plaqué selon l'une quelconque des revendications précédentes, comprenant les étapes suivantes :

    a) plaquer une couche comprenant le, ou constituée du, premier alliage de cuivre sur une couche de cuivre disposée sur un substrat ;

    b) plaquer une couche comprenant le, ou constituée du, second alliage de cuivre sur la couche de l'étape a) ;

    c) plaquer une couche comprenant le, ou constituée du, métal précieux sur la couche de l'étape b) ;

    où la première couche d'alliage de cuivre est plaquée avec une concentration en cuivre différente de celle de la deuxième couche d'alliage de cuivre.
     
    16. Utilisation du produit plaqué selon l'une quelconque des revendications 1 à 14 dans l'industrie des bijoux, l'industrie de la mode, l'industrie du cuir, l'industrie de l'horlogerie, l'industrie des lunettes, l'industrie des bibelots et / ou l'industrie de la serrurerie.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



    This list of references cited by the applicant is for the reader's convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

    Patent documents cited in the description