Object with an applied 3D decoration

Abstract

Article (1) made of an electrically non-conductive material, comprising at least one relief decoration (2a) which is applied successively towards the outside of the article (1) with at least a first adhesive layer (4a), a second adhesive layer (4b) and a visible layer (5) made of a precious metal or one of its alloys, wherein the first adhesive layer (4a) and the second adhesive layer (4b) each have a thickness between 30 nm and 70 nm and the visible layer (5) has a thickness between 0.02 mm and 0.7 mm, preferably between 0.03 mm and 0.3 mm.

Description

Technical field of the invention

[0001] The invention relates to an article having a 3D decoration applied with a precious metal or a precious metal alloy. Technical background

[0002] Decorations are typically applied to components made of hard, non-conductive materials such as ceramic, e.g., by bonding. Decorations applied in this way adhere poorly to the substrate, increasing the risk of tearing or detaching, especially in highly stressed components such as watch bezels. Summary of the invention

[0003] The present invention aims to remedy the aforementioned deficiencies by proposing an article with a positive relief decoration, also called a 3D decoration, which is integral with the substrate to avoid adhesion problems. A protective layer of gold, silver, or more generally, a precious metal or its alloy is applied to this relief decoration to give it a decorative appearance.

[0004] More specifically, the invention relates to an article made of an electrically non-conductive material such as ceramic, sapphire, YAG (yttrium aluminum garnet) or silicon nitride, the article comprising at least one relief decoration coated with a visible layer of a precious metal or one of its alloys, the article being capable of being manufactured by a process comprising the following steps: - Providing a one-piece blank with a surface formed by a base surface and at least one relief decoration superimposed on the base surface; - applying a first adhesive layer and then a second adhesive layer to the relief decoration and at least partially to the base surface; - Electroplating of the visible layer on the second adhesive layer; - Selective laser ablation of the visible layer and at least partially of the first adhesive layer and the second adhesive layer on the base surface, so that only the visible layer remains on the relief decoration including its flanks.

[0005] Produced by this process, the decoration cannot tear or detach from the substrate as it is part of the substrate.

[0006] In addition, the layer of precious metal or its alloy on the relief decoration is considerably thick, up to several tenths of a millimeter. The precious metal can be gold or a gold alloy. The great thickness of the applied metal or alloy contributes to the "solid" appearance of any decoration applied to it, such as an appliqué.

[0007] Since this invention is specifically aimed at decorating bezels, there is no risk of friction from clothing wearing off the coating, which could expose the substrate.

[0008] Another advantage of electroformed gold is that it is harder than a metallurgical gold alloy that would have been applied to the substrate. This allows for a satin finish that is more durable over time. Short description of the characters Fig. 1 to 5 schematically show the 5 steps of the method for producing an article according to the invention. Fig. 6 shows a watch bezel with indices and numerals forming the 3D decoration according to the invention, applied with precious metal or its alloy. Detailed description of the invention

[0009] The invention relates to an article with a relief decoration coated with a precious metal or a precious metal alloy. The precious metal is in particular gold, silver, platinum, palladium, rhodium or ruthenium. The article can be, for example, a watch component. In particular, it can be a feature selected from a non-exhaustive list comprising a middle part, a case back, a bezel, a crown, a pusher, a bracelet link, a bracelet, a pin buckle, a clasp, a dial and a hand. Typically, the watch component is a dial or bezel with indices and numerals forming the relief decoration and coated with a layer of precious metal or alloy. The article is made of an electrically non-conductive material such as ceramic, silicon nitride, YAG or sapphire.These materials are usually hard with a hardness of 1100 HV (Vickers hardness) or higher.

[0010] In the Fig. 1 to 5, a method for producing an article according to the present invention is shown in 5 steps. In a first step ( Fig. 1) The article is provided with the uncoated decoration 2a, collectively referred to as the ingot 3. The decoration 2a is an integral part of the ingot 3, which is manufactured by a conventional powder sintering process or by additive manufacturing for ceramics, silicon nitride, and YAG, or by the Verneuil process and the EFG (edge-defined film-fed growth) technique for sapphire. EFG stands for "edge-defined film growth" in German. These processes are mentioned as examples, and of course, other processes for manufacturing the ingot can also be considered.

[0011] The blank 3 is defined by its outer side 2, which has a base surface 2b and at least one relief decoration 2a that projects beyond this base surface 2b.

[0012] In a second step ( Fig. 2) At least two adhesion layers 4a, 4b are then applied, preferably by PVD (Physical Vapor Deposition), to the relief decoration 2a and to at least part of the base surface 2b. A first layer 4a is formed from Cr or Ti and a second layer 4b is formed from Au, Ag or Cu. Each layer has a thickness between 30 nm and 70 nm, with one layer typically being on the order of 50 nm. According to the invention, one or both adhesion layers can be selectively applied, e.g., using a mask, only to part of the base surface. The surface of one or both adhesion layers can also be structured, e.g., with a laser, to change their physical properties, such as hydrophobicity.

[0013] In a third step ( Fig. 3) The layer of precious metal or its alloy 5 is deposited by electroforming. This layer 5 has a thickness between 0.02 mm and 0.7 mm, preferably between 0.03 mm and 0.3 mm. For the growth of a gold alloy in a shade between 3N and 5N (according to ISO standard 8654 of February 2018), the parameters are as follows: - the bath contains 1 to 10 g / l of gold metal in the form of alkaline aurocyanide; - the bath contains 30 to 80 g / l of copper metal in the form of alkaline double cyanide; - the bath may contain between 10 mg / l and 5 g / l of indium metal in complex form; - the bath contains 15 to 35 g / l of free cyanide; - the temperature of the bath is kept between 50° and 80°C; - the pH of the bath is maintained between 8 and 12; - the process is carried out at current densities between 0.05 and 1.5 A / dm 2 carried out.

[0014] In an optional fourth step ( Fig. 4) the upper part of the layer of precious metal or its alloy 5 may be subjected to mechanical processing in order to polish, satinise and / or mattify this layer.

[0015] In a fifth step ( Fig. 5) the layer of precious metal or its alloy 5 and at least partially the two adhesion layers 4a, 4b are removed by laser ablation at the level of the base surface 2b, so that the various layers 4a, 4b, 5 remain only on the relief decoration 2a, including its flanks. The laser ablation is preferably carried out using a pulsed laser such as a picosecond, nanosecond, or femtosecond laser. A variety of source and parameter combinations can be used for ablating metal layers. However, a femtosecond laser source with a wavelength between 310 nm and 600 nm is preferably used, the pulses of which are shaped to have a minimum average energy and high peak values per pulse relative to the average energy acting on the metal layer.Typically, repetition frequencies between 400 kHz and 1200 kHz are used, as well as a burst envelope shape consisting of a linearly rising or falling slope with a variable slope and containing 1 to 35 pulses.

[0016] It should be noted that the fourth step can also be carried out after this fifth step and possibly after the sixth and seventh steps described below.

[0017] In an optional sixth step, not shown, the blank material can be textured to give the surface a matte, satin, and / or patterned appearance. Texturing can be done using a laser or a mechanical process.

[0018] In an optional, not shown, seventh step, the bonding layers 4a, 4b can be removed from the base surface 2b of the object if the laser ablation has left residues of these bonding layers. This removal consists of chemically removing the residues from the layers by immersing the workpiece in a bath, e.g., a bath containing chromium etchant No. 1, developed by Technic. Removing these layers has only a minor impact on the precious metal layer or its alloy, since the thicknesses of the bonding layers and the precious metal layer or its alloy are very different. In other words, by removing any remaining few nanometers of bonding layers, relatively little material is removed from the thick layer of precious metal or its alloy. This optional step can also be performed before the sixth step if, as mentioned above, this is optional.

[0019] The object 1 thus obtained, which is in Fig. 6 for a bezel, thus has one or more relief decorations 2a which project beyond the base surface 2b, the layer of precious metal or its alloy 5 being present only on the relief decorations 2a, including its flanks. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited non-patent literature

[0000] ISO standard 8654 of February 2018

[0013]

Claims

[1] Article (1) made of an electrically non-conductive material, comprising at least one relief decoration (2a) which is applied successively towards the outside of the article (1) with at least a first adhesive layer (4a), a second adhesive layer (4b) and a visible layer (5) made of a precious metal or one of its alloys, wherein the first adhesive layer (4a) and the second adhesive layer (4b) each have a thickness between 30 nm and 70 nm and the visible layer (5) has a thickness between 0.02 mm and 0.7 mm, preferably between 0.03 mm and 0.3 mm. [2] Article (1) according to the preceding claim, wherein the article (1) is a watch component. [3] Article (1) according to the preceding claim, wherein the article (1) is a bezel or a dial. [4] Article (1) according to one of claims 1 to 3, wherein the article (1) is made of ceramic, sapphire, YAG or silicon nitride.

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