Coated metallic article of daily use or coated metallic component of a daily use article

Abstract

A consumer article comprising at least one metallic component (1a) or formed by a metallic component having a multi-layer coating and a relief surface formed at least partially profiled by mechanical processing of the coated component, wherein the multi-layer coating comprises layers in the combination and layer sequence specified below: a - with at least one underlayer (3, 3', 3'') deposited galvanically on a base material of the metallic component, which underlayer contains at least nickel, b - with at least one intermediate layer (4a) made of titanium (Ti) applied thereto by a vacuum coating process and c - with a cover layer (4c) of niobium (Nb) or tantalum (Ta) applied thereto by a vacuum coating process, wherein the cover layer (4c) has a color-oxidized layer region (5) by a preferably anodic oxidation process.

Description

[0001] The invention relates to a utility article, in particular for decorative or representative purposes, which has at least one metallic component or is formed by a metallic component which has an at least partially profiled surface and a coating.

[0002] Metallic articles of daily use, in particular for decorative or representative purposes, are, within the meaning of the invention, in particular valuable, decorative articles of daily use, such as coins, medals, seals, tokens, decorative elements, parts of jewelry, or trophies, which can preferably consist of non-ferrous metals and which have a visible profiled surface (relief surface) for decoration, representation or marking.

[0003] It is known to coat the relief surface of these metallic articles of daily use in order to achieve, for example, corrosion protection and / or decorative coloring of the metallic articles of daily use.

[0004] The known coatings of metallic everyday objects are limited to the application of a lacquer surface by means of pad printing, screen printing or spray painting or to a foil coating following their finished relief surface.

[0005] These coatings have the disadvantage that the applied surface coating diminishes the metallic luster and feel, especially of the coin or medal. This is due, among other things, to the fact that fine details of a high-quality relief or image embossed on the surface of the coin or medal are undesirably covered or leveled by the lacquer layer, which is significantly thicker than the relief thickness.

[0006] A similar multi-layer coating that smooths and levels the surface of a metallic object is known from the document DE 602 20 754 T2, whereby the coating is not subjected to any subsequent mechanical processing.

[0007] From the document DE 38 09 139 A1, a multi-layer coating of a metallic base material is known, which serves to improve the corrosion resistance and the mechanical adhesion of the top layer, whereby here too the coating is not subjected to any subsequent mechanical processing.

[0008] From the document EP 3 017 095 B1, a multi-layer coating of an already minted coin or medal with a colored niobium layer is known to improve the durability and aesthetic properties.

[0009] However, all such coatings are less suitable for application before a final mechanical processing of the metallic everyday objects to produce the relief surface, such as is done by a joining or embossing process to complete the coins or medals, since this is likely to result in inhomogeneous layer defects and layer detachments of the lacquer or foil layers or the multi-layer coatings, which would significantly impair the quality of the decorative everyday objects in terms of durability, appearance and feel.

[0010] However, due to certain technological and legal requirements for particularly valuable consumer goods such as coins, it must be taken into account that all manufacturing processes, including finishing by coating, must take place before the individual coin components are joined and the coins are minted.

[0011] In addition, the wear resistance of the lacquer or foil surfaces, particularly on coins or tokens, is unsatisfactory due to their continuous stress caused by frequent use.

[0012] For particularly valuable, decorative everyday objects, such as coins, where a permanently brilliant relief surface is desired, such coatings are rarely used to achieve coloration.

[0013] To produce coins / medals with a brilliant, metallically shiny and colorful surface, it is known to use a refractory metal, such as niobium or titanium, as the base material for the solid blank, which receives a colored oxidized layer area in an anodic oxidation process and is then finished into coins / medals in a subsequent joining or minting process.

[0014] However, the base materials niobium or titanium are very expensive compared to the usual base materials for coins / medals. Furthermore, the material properties of niobium and titanium do not allow for economically viable production of these coins / medals. Therefore, the use of these base materials for the production of coins / medals is not cost-effective for large-scale production.

[0015] The invention is based on the object of providing a metallic article of daily use or a metallic component of the article of daily use according to the aforementioned type with a colored coating which ensures an improved quality of the relief surface with regard to durability, appearance and / or haptics.

[0016] In particular, the colored coating of the metallic article of daily use or the metallic component of the article of daily use should have a brilliant, metallic shine, have a metallic feel and be so wear-resistant that the coating can withstand both continuous stress caused by frequent handling and mechanical processing, such as joining coated components to one another and to other components or embossing reliefs on the coated surface, without damage.

[0017] The object is achieved according to the invention by a coating of a metallic article of daily use or a metallic component of the article of daily use having the features of claim 1.

[0018] According to the invention, the metallic article of daily use or its metallic component has a multi-layer coating with the following layer sequence, wherein the article of daily use coated in this way or its coated component has an at least partially profiled relief surface by subsequent mechanical processing: - with at least one underlayer deposited galvanically on a base material of the metallic component, which underlayer contains at least nickel, - with at least one intermediate layer of titanium (Ti) applied thereto by a vacuum coating process and - with a cover layer of niobium (Nb) or tantalum (Ta) applied thereon by a vacuum coating process, wherein the cover layer has a color-oxidized layer region as a result of a preferably anodic oxidation process.

[0019] The underlayer deposited on the metallic component serves to protect the metallic base material of the metallic component from corrosion and oxidation.

[0020] This protection is particularly useful for the base materials of the metallic components commonly used for the manufacture of decorative or representational objects, which may consist of or contain non-ferrous metal or its alloy, gold or its alloy, or silver and its alloy, and are therefore not themselves corrosion-resistant and may tarnish upon contact with the ambient air.

[0021] The base materials commonly used for metallic components of coins or medals consist of one of the following metals or metal alloys: CuNi 25, CuNi 19, CuZn20Ni5, Cu89Al5Zn5Sn1, silver (Ag) and its various alloys, gold (Au) and its various alloys or consist of combinations of the aforementioned metals or metal alloys or at least contain these metals or metal alloys.

[0022] The closed galvanic underlayer made of corrosion-resistant material prevents oxidizing gases, such as atmospheric oxygen, or corrosive fluids, such as skin perspiration, from reaching the surface of the base material through micropores (pinholes) or microcracks in the layers above and causing local corrosion, which can lead to the coating lifting off or flaking off.

[0023] Furthermore, it was surprisingly found that the full-surface galvanic underlayer makes a significant contribution to the favorable ductility of the multi-layer coating system.

[0024] According to an advantageous embodiment, two galvanic sublayers are provided.

[0025] According to a further advantageous embodiment, the electrodeposited underlayer(s) has(have) a total layer thickness of up to 2.5 µm. In this layer thickness range, the electroplated underlayer(s)—and consequently the multilayer coating system as a whole—has(have) such ductile properties that the layers can deform largely damage-free when subjected to mechanical deformation stress.

[0026] The advantageous embodiments of the galvanic underlayer(s) claimed below can be adapted to the mentioned, commonly used base materials of the metallic components of coins / medals for a respective optimal protection.

[0027] Furthermore, two different galvanic undercoats offer improved corrosion and oxidation protection, particularly for metallic components with non-ferrous metal or non-ferrous metal alloys as base materials.

[0028] An intermediate layer of titanium (Ti) applied to these sublayers by a vacuum coating process serves to promote adhesion for the top layer of niobium (Nb) or tantalum (Ta), which can thereby advantageously develop its special properties.

[0029] Both the intermediate layer and the cover layer are applied by a vacuum coating process, preferably by sputter deposition in a PVD (Physical Vapour Deposition) system using a target, whereby the target for producing the intermediate layer is made of titanium and the target for producing the cover layer is made of niobium or tantalum.

[0030] In sputter deposition, the ion source is preferably a direct current gas discharge (DC sputtering) using a non-reactive gas, such as argon. Preferably, the target material is atomized using a magnetized target (DC magnetron sputtering).

[0031] Other vacuum-based coating processes can also be used to apply the intermediate layer and the top layer.

[0032] The top layer of niobium or tantalum is then oxidized, preferably anodically in an aqueous, alkaline bath. Depending on the oxidation conditions, such as the applied voltage and the duration of oxidation, a variety of different colors of the oxidized niobium or tantalum layer can be produced, which are caused by light interference.

[0033] The full-surface intermediate layer made of titanium, in particular pure titanium, provides a particularly good base for the niobium or tantalum layer on top and also creates a uniform and color-homogeneous top layer.

[0034] The combination of the galvanic underlayer, the intermediate layer of titanium and the top layer of niobium or tantalum creates a surface with high corrosion resistance, hardness and ductility.

[0035] The applied top layer of niobium or tantalum is characterized by a brilliant, homogeneous and durable color after oxidation.

[0036] In the case of a consumer article whose metallic component has this coating according to the invention, it can be seen that even if the metallic component is subsequently mechanically processed, e.g. by embossing or joining, the coated surface does not reveal any layer defects or layer detachments that are visually perceptible to the human eye.

[0037] This means that the layer structure and the properties of the coating according to the invention have remained essentially undamaged even after mechanical processing.

[0038] The positive adhesion and strength properties of the layer structure of the coating are further improved if a transition layer is provided between the intermediate layer and the cover layer, in which a portion of the material of the intermediate layer (e.g. titanium) and a portion of the material of the cover layer, i.e. niobium or tantalum, is contained.

[0039] In a further advantageous embodiment, it is provided that the proportion of the material of the intermediate layer in the transition layer is designed to decrease with increasing layer thickness of the transition layer from 100% to 0%, preferably continuously, and the proportion of the material of the cover layer in the transition layer is designed to increase with increasing layer thickness of the transition layer from 0% to 100%, preferably continuously.

[0040] By gradually, preferably continuously changing the mixing ratios of the material of the intermediate layer and the top layer in the transition layer, even better adhesion and strength properties of the layer structure of the coating are achieved.

[0041] In addition, particularly homogeneous and even more brilliant color results are achieved on the surface of the coated metallic component.

[0042] Further advantageous embodiments and developments of the invention emerge from the dependent claims 2 to 17, the following description and the associated drawings.

[0043] The product according to the invention is explained in more detail below using an exemplary embodiment. The accompanying drawings show a schematic representation in Fig. 1a Top view of a ring-shaped, metallic component of a coin with the coating according to the invention, Fig. 1b Top view of a circular disc-shaped metallic component of the coin, Fig. 2 enlarged, half-sectional view of the coated, ring-shaped component, Fig. 3a enlarged sectional view of the joining process of the ring-shaped component with the circular disc-shaped component of the coin, Fig. 3b enlarged sectional view of the joined coin blank, Fig. 3c Top view of the joined coin blank, Fig. 4a, b enlarged sectional views of the minting process of the coin blank, Fig. 4c enlarged sectional view of the minted coin, Fig. 5 Sectional view of the enlarged detail X of the minted coin after Fig. 4c.

[0044] The Fig. 1a and Fig. 1b each show a metallic component of a coin. The metallic, ring-shaped component (ring component) 1a according to Fig. 1a comprises a base body 2a, consisting of the base material CuNi25, and the colored coating according to the invention. The metallic, circular disc-shaped component (platelet component) 1b according to the Fig. 1b has a base body 2b, which also consists of the base material CuNi25, but is untreated, i.e. is not provided with a coating.

[0045] The colour-coated ring 1a is intended to create a clear decorative, coloured contrast to the plate 1b when the coin is finished.

[0046] Fig. 2 shows the annular component (ring component) 1a coated according to the invention in a sectional view.

[0047] A two-layer galvanic coating system 3 consisting of a first and a second galvanic sub-layer is deposited on the cleaned base body 2a of the ring component 1a made of CuNi25.

[0048] The first galvanic sublayer 3' consists of nickel (Ni) with a layer thickness of 2 µm. The second galvanic sublayer 3'' consists of palladium nickel (PdNi) with an average layer thickness of 0.5 µm, this alloy preferably being composed of 80% palladium and 20% nickel.

[0049] For the sake of clarity, the two sublayers 3', 3'' of the galvanic layer system 3 are not shown separately.

[0050] Based on this, a PVD coating system applied using the PVD vacuum process is provided. The PVD coating system 4 comprises an intermediate layer 4a, a transition layer 4b, and a cover layer 4c with varying proportions of titanium and niobium. These layers 4a, 4b, and 4c can be applied sequentially using the DC magnetron sputtering process within a vacuum chamber with argon as the ion source by magnetron sputtering the respective magnetron target material (titanium, niobium).

[0051] The intermediate layer 4a, made of pure titanium with a thickness of 0.3 µm, is deposited onto the electroplated layer system using a target made of high-purity titanium with a purity of more than 99.9%. The intermediate layer 4a forms the homogeneous adhesion base for the transition layer 4b located above it.

[0052] The transition layer 4b with an average layer thickness of 150 nm has a proportion of titanium that decreases with increasing layer thickness of the transition layer 4b and a proportion of niobium that increases with increasing layer thickness of the transition layer 4b, wherein to produce the transition layer 4b the sputtering rate of the titanium target is continuously reduced from 100% to 0% and the sputtering rate of the niobium target is continuously increased from 0% to 100% to the same extent.

[0053] The cover layer 4c made of high-purity niobium formed on the transition layer 4b has a layer thickness of 1 µm.

[0054] The portion of niobium in the transition layer 4b and the top layer 4c of high-purity niobium is deposited using a target of high-purity niobium with a purity of more than 99.9%.

[0055] This layer thickness of the cover layer 4c is just sufficient to trigger an oxidation process of the niobium material.

[0056] The ring component 1a coated with the PVD layer system 4 is anodically oxidized in an aqueous, alkaline solution, whereby an oxidized layer region 5 is formed within the cover layer 4c made of niobium, which has a very small layer thickness of only about 30 nm and which is perceived as colored by interference of the light.

[0057] Depending on the selected oxidation conditions (such as the nature of the solution, the level of the voltage, the duration of the oxidation), different interference colors of the niobium oxidation layer 5 can be achieved.

[0058] The Fig. For better understanding, the layers of the ring component 1a shown in Figure 2 are shown only schematically and much larger than in reality.

[0059] The cover layer 4c with the colored oxidation layer 5 gives the ring component 1a a brilliant, metallic shine and a metallic feel.

[0060] In Fig. 3a shows the joining process of the ring component 1a coated according to the invention with the platelet component 1b of the coin, the result of which is a coin blank 6 joined from two components according to the Fig. 3b, Fig. 3c is created.

[0061] It is made clear that the layers of the galvanic layer system 3 and the PVD layer system 4 - including the oxidation area 5 of the cover layer 4c - of the ring component 1a of the coin blank 6 are tapered / pressed in their layer thicknesses compared to the initial coating due to the mechanical pressure of the joining, but the individual layers are damage-free, firmly adhering and continuously closed.

[0062] There are no visually apparent layer defects or local layer detachments.

[0063] The Fig. 4a, Fig. 4b schematically show the minting process on the joined coin blank 6 by means of a minting die 7, with which the surface of the coin blank 6 is deformed under high pressure according to the pattern of the minting die 7 and receives an embossing (relief surface).

[0064] The result is a minted coin with a colour-coated ring component 1a and an uncoated platelet component 1b (see Fig. 4c).

[0065] In the enlarged detail X of the minted coin after Fig. 4c shows that the individual layers of the galvanic layer system 3 and the PVD layer system 4 - including the oxidation area 5 of the cover layer 4c - of the ring component 1a of the coin are tapered / compressed in their layer thicknesses compared to the initial coating, even due to the mechanical deformation pressure acting on the surface, but are damage-free, firmly adhering and completely closed.

[0066] There are also no visually apparent layer defects or layer detachments in the relief surface of the minted coin.

[0067] The brilliant, metallic luster and the metallic feel of the top layer 4c with the colored oxidation area 5 have been retained throughout.

[0068] Any microcracks that may occur in the layers and are not visible to the naked eye do not affect the adhesion of the layers and are insignificant for the advantageous optical and haptic properties achieved.

Claims

[1] A consumer article comprising at least one metallic component (1a) or formed by a metallic component having a multi-layer coating and a relief surface formed at least partially profiled by mechanical processing of the coated component, wherein the multi-layer coating comprises layers in the combination and layer sequence specified below: a - with at least one underlayer (3, 3', 3'') deposited galvanically on a base material of the metallic component, which underlayer contains at least nickel, b - with at least one intermediate layer (4a) made of titanium (Ti) applied thereto by a vacuum coating process and c - with a cover layer (4c) of niobium (Nb) or tantalum (Ta) applied thereto by a vacuum coating process, wherein the cover layer (4c) has a color-oxidized layer region (5) by a preferably anodic oxidation process. [2] Article according to claim 1, characterized by that the metallic component (1a) has a base material made of a non-ferrous metal or its alloy, of gold or its alloy or of silver and its alloy or consists of this base material. [3] Article according to claim 1 or 2, characterized by that the commodity is a coin, a medal, a token, a seal, a decorative element or part or a trophy. [4] Article according to one of claims 1 to 3, characterized by that the electroplated underlayer (3, 3', 3'') has a layer thickness of up to 2.5 µm. [5] Article according to one of claims 1 to 4, characterized by that the electrodeposited underlayer (3) is formed from a first underlayer (3') and a second underlayer (3''). [6] Article according to claim 5, characterized by that the first electroplated underlayer (3') is formed from nickel (Ni). [7] Article according to claim 5 or 6, characterized by that the first electroplated underlayer (3') has a layer thickness of 2 µm. [8] Article according to one of claims 5 to 7, characterized by that the second galvanically deposited underlayer (3'') is formed from palladium nickel alloy (PdNi). [9] Article according to claim 8, characterized by that the palladium-nickel alloy (PdNi) contains 80% palladium and 20% nickel. [10] Article according to claim 8 or 9, characterized bythat the second electroplated underlayer (3'') has a layer thickness of 0.5 µm. [11] Article according to one of claims 1 to 10, characterized by that the intermediate layer (4a) made of, in particular, high-purity titanium, is an intermediate layer (4a) applied by the PVD process, in particular by the DC magnetron sputtering process. [12] Article according to one of claims 1 to 11, characterized by that the intermediate layer (4a) has a layer thickness of 0.3 to 0.5 µm. [13] Article according to one of claims 1 to 12, characterized by that the cover layer (4c) made of in particular high-purity niobium or tantalum is a cover layer (4c) applied by the PVD process, in particular by the DC magnetron sputtering process. [14] Article according to one of claims 1 to 13, characterized by that the cover layer (4c) has a layer thickness of 1 µm. [15] Article according to one of claims 1 to 14, characterized by that the oxidized layer region (5) of the cover layer (4c) has a layer thickness of approximately 30 nm. [16] Article according to one of claims 1 to 15, characterized by that a transition layer (4b) is formed between the intermediate layer (4a) and the cover layer (4c), in which a portion of the material of the intermediate layer (4a) and a portion of the material of the cover layer (4c) are contained. [17] Article according to claim 16, characterized by that the proportion of the material of the intermediate layer (4a) is designed to decrease with increasing layer thickness of the transition layer (4b) from 100% to 0%, and the proportion of the material of the cover layer (4c) is designed to increase with increasing layer thickness of the transition layer (4b) from 0% to 100%. [18] Article according to claim 17, characterized bythat the proportion of the material of the intermediate layer (4a) is continuously decreasing and the proportion of the material of the cover layer (4c) is continuously increasing.

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