Process for manufacturing a gold alloy timepiece component, and resulting timepiece

Abstract

The present invention relates to a process for manufacturing a timepiece component in which gold alloys are assembled to make mixed powders for producing alloys having specified colors. The powders are combined and arranged to create visual effects on the timepiece component. The invention further relates to a timepiece component and to a timepiece comprising at least one of said timepiece components.

Description

Process for manufacturing a watch component based on gold alloy and resulting part Technical field

[0001] The present invention relates to a method for manufacturing a watch component based on several precious or noble metals or alloys of such metals. In particular, at least one of these precious metals or alloy of precious metals designates gold or one of its alloys. Preferably, the method of the present description applies to the manufacture of a watch component based on several different golds. The different precious metals, golds, or their alloys are individually atomized into separate powders and then mixed in predetermined proportions to produce homogeneous mixed powders. The proportions of corresponding metals, golds or alloys constituting a mixed powder are determined according to the color to be obtained on the finished component.The mixed powders are arranged relative to each other so as to form a colored pattern such as a gradient, and are jointly involved in a sintering operation, in particular SPS sintering (spark plasma sintering) also known as flash sintering. The composites resulting from the different mixed powders can be distinguished from each other in the watch component thus obtained, in particular by their color. The present description further covers a watch component consisting of several distinct gold alloys assembled into composites, as well as a timepiece comprising such a component. State of the art

[0002] The principle of sintering powders of metallic materials is known and often used to manufacture metal alloys. Document EP3766997, for example, describes the formation of precious metal alloys using such a process. However, such alloys require that all the powders be mixed to form a single, preferably homogenized, mixture. Such processes do not allow to produce components with different local compositions.

[0003] Document EP3822712 gives an example of a process based on metal powders for the design of a component for a timepiece comprising a surface melting step to eliminate defects.

[0004] Document W02015061817 describes a multi-phase structure made by the intercalation or interpenetration of different materials, in a random, unique and individual arrangement, serving as an authentication element for a piece of jewelry or a luxury product. The resulting multi-colored macrostructure, being difficult to reproduce, has an anti-copy function.

[0005] Document CN110328371A describes a multi-step process where different materials are successively placed in a mold and compressed with a characteristic shaped element to produce the desired pattern.

[0006] Document CN111992731A describes a process for including particles in gold to increase its hardness.

[0007] The sintering technique is an alternative to brazing or welding which has the advantage of limiting or avoiding the addition of material at the interfaces, as well as the mixing of the materials present. There is therefore scope for developing a process specifically adapted to precious materials, in particular gold alloys, allowing a greater variety of their use and assembly.

[0008] Furthermore, in the field of watchmaking, the aesthetic properties of the alloys used sometimes take on crucial importance, as they determine the appearance of the final piece. The available alloys in commerce can present aesthetic variations between them but their shade is not adjustable, which limits the diversity of colors and appearances that can be obtained. The control of colored nuances remains a challenge today. It is therefore necessary to develop processes that allow the production on demand of materials according to their aesthetic properties, and in particular their colors. Brief summary of the invention

[0009] An aim of the present invention is to propose a method of manufacturing a watch element and / or a watch part allowing greater aesthetic diversity, in particular in terms of shades, colors, tints and their combinations.

[0010] Another aim of the present invention is to propose a method for manufacturing a watch element and / or a watch part making it possible to determine its composition according to the colors, shades, nuances expected in the final part.

[0011] Another aim of the present invention is to propose a method for manufacturing a watch element and / or a timepiece whose decorative patterns, obtained by means of the constituents of the watch element and / or the timepiece, are reproducible.

[0012] Another aim of the present invention is to propose a method for manufacturing a watch element and / or a timepiece whose decorative patterns are obtained in the mass, the structure of the watch element and / or the timepiece remaining homogeneous.

[0013] Another aim of the invention is to provide a timepiece and / or a timepiece of greater quality and / or aesthetic diversity, particularly in terms of shades, colors, tints and their combinations.

[0014] Another aim of the present invention is to propose a watch element and / or a timepiece comprising decorative patterns obtained in the mass and the shapes and colors of which are reproducible from one piece to another, and forming a homogeneous structure.

[0015] According to the invention, these aims, or at least some of these aims, are achieved, in particular by means of the method, the timepiece element and the timepiece which are the subject of the independent claims and detailed in the claims which depend thereon.

[0016] This solution has the particular advantage over the prior art of being able to predetermine the compositions of the elements and timepieces according to the final colors and / or shades to be obtained, in a greater diversity than that currently available. The present solution also allows for high reproducibility of the shapes and shades of the decorative motifs, while preserving a homogeneous structure of such timepieces. Brief description of the figures

[0017] Examples of implementation of the invention are indicated in the description illustrated by the following figures: • Figure 1: example of a colorimetric curve for some gold alloys according to the present invention • Figure 2: example of colorimetric curve as a function of the mass percentage of 5N gold Figure 3: example of distribution of different gold alloys in a watch element blank, according to the present description Figure 4: Example of colorimetric analysis model used in this method Example(s) of embodiment of the invention

[0018] The method according to the present description makes it possible to obtain a watch component, as well as a timepiece comprising such a component, in which several colored shades are juxtaposed, thus making it possible to produce a wide variety of patterns. The colors or shades are directly linked to the material constituting the watch element and are not limited to a surface coloring. The method according to the present invention makes it possible to have various precious materials, in particular several gold alloys, without mixing them. The method according to the present description also makes it possible to obtain a greater diversity of combinations, compared to the predetermined alloys already available on the market. The composites produced according to the method described here may have mechanical characteristics that differ from one another, in particular in terms of hardness.The composites produced according to the present process also have specific aesthetic characteristics, which are exploited as a priority within the framework of the present invention.

[0019] For the purposes of this description, the term "composite" designates a material resulting from the sintering of the mixed powders described herein under the conditions of the present process. Since the process does not involve the melting of these powders, the resulting composites are not considered to be alloys. Preferably, the different powders are each produced based on a precious metal, in particular gold, or their alloys. The powders may be described as "mixed". Preferably, the mixed powders comprise at least one gold.

[0020] According to one embodiment, the watch elements considered here are produced on the basis of at least one composite, which can be combined with at least one other material such as a composite, pure gold and / or an alloy, for example a gold alloy. Such another material is designated in this description as a separate material. In such an arrangement, the composite remains separate from the separate materials in the final product. The method of the present invention makes it possible to produce the composite, preferably an assortment of several composites, and to assemble them. It notably comprises a first step S1 of selecting a first gold 01 in the form of a first powder P1 and a second material in the form of a second powder P2. According to a preferred aspect, the second material designates a second gold 02.

[0021] For the purposes of this description, a "gold", such as a first gold and a second gold, may refer to pure gold or any gold-based alloy already commercially available. A gold may therefore refer to an alloy of white gold, or pink gold, or gray gold, or green gold, or red gold. Preferably, a gold according to the present description refers to a material comprising at least 37.5% (9ct), or even at least 75% (18ct) or more, 92% (22ct) or even 100% (24ct)%. Preferably, a gold according to the present description refers to an alloy containing 18 carats or more, such as 18 or 24 carats. A gold according to the present description may comprise other elements than gold, such as precious or noble metals, among silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), scandium (Sc), ruthenium (Ru) osmium (Os) and iridium (Ir), non-precious metals among copper (Cu), titanium (Ti), tin (Sn), nickel (Ni), aluminum (Al) or their combination.Precious or non-precious metals can independently be used in different capacities, such as 9 and, 12 and, 18 and or 24 and or in other capacities. The golds mentioned herein designate all golds from 1N to 5N. Non-limiting examples of golds and their composition are defined below:. White gold: 75% gold, 19% copper, 6% silver, White gold: 75% gold, 25% palladium or 25% nickel, Red gold: 75% gold, 25% copper, Rose gold: 75% gold, 20% copper, 5% silver, Green gold: 75% gold, 25% silver.

[0022] One or more additional materials Mi, different from the first gold 01 and the second material, can be selected in this selection step 51. The additional materials can be independently selected from the precious or noble materials and / or non-precious materials mentioned above. The additional material(s) Mi are in the form of as many corresponding additional powders Pi.

[0023] The method comprises a first step S2 of mixing the first P1 and second P2 powders, and where appropriate the additional powder(s) Pi so as to produce a first homogeneous mixed powder PM1.

[0024] The first gold 01, the second material, as well as any additional materials are selected according to their nature, i.e. their composition, and are mixed in predetermined proportions, as explained in more detail below. In this case, the compositions and proportions of the different golds, determined by their mass percentage, are predetermined according to the expected final color of the timepiece.

[0025] A watch component may consist of only one composite. Such a watch component will, under these conditions, have a uniform color representative of the composite, which may be different from the usual colors representative of commercial alloys.

[0026] According to a more advantageous embodiment, a timepiece element comprises a composite combined with another material. The method allows for this purpose to combine the first mixed powder PM1 with other powders already commercially available. For example, a separate material Md in the form of Pd powder can be arranged together with the first mixed powder PM1 so that the color Cd of the separate material Md differs from the color C1 of the resulting composite A1. of the first mixed powder PM1. In this case, the color Cd will correspond to an already existing color and the color C1 will be characteristic of the composition of the mixed powder PM1.

[0027] According to another embodiment, a timepiece element comprises two or more combined composites. The method comprises for this purpose at least one other selection step and one other mixing step as described above, and possibly the addition of additional materials, capable of producing at least one composite of a color different from that of the composite resulting from the first selection step S1 and the first mixing step S2. The resulting mixed powder(s) are not limited in number or in shades. For example, all the shades between white gold and pink gold can be obtained by as many mixed powders.

[0028] Thus, the method according to the present description could comprise at least a second selection step S1' of a second first gold 01' and at least a second second material in the form of a second first PV and at least a second second P2' powders respectively, and one or more possible second additional materials Mi' in the form of as many second additional powders Pi'. According to an advantageous arrangement, the second second material designates a second second gold 02'. The method further comprises at least a second mixing step S2' of said second first PV and second P2' powders and where appropriate one or more additional second powders Pi', so as to produce at least one second mixed powder PM2.

[0029] It is understood that more than two different golds may be selected and mixed as required, particularly to achieve very specific shades. For example, white, pink and red golds may be mixed, or pink, green and grey golds, etc. Furthermore, mixing two or more golds does not preclude mixing them with one or more other golds. several second materials, nor with one or more additional materials Mi.

[0030] Further steps of selecting and mixing different golds can be carried out so as to produce as many different PMi mixed powders as are then used in the manufacture of the timepiece. The number of mixed powders is not limited. A timepiece can be manufactured from two, or three, or four, or five or more different mixed powders. In addition, separate materials in powder form can be used in combination with the mixed powders, as indicated above, which may not contain gold.

[0031] In the context of the present description, a mixed powder means a homogeneous powder comprising at least two materials. Preferably, a mixed powder means a homogeneous powder comprising at least one gold, combined with at least one other material such as a precious metal or an alloy. Preferably, a mixed powder according to the present description means a homogeneous powder comprising at least two different golds. A homogeneous powder means that the different constituents are distributed therein uniformly, that is to say without a concentration gradient. In this way, the color of the mixed powder is uniform. In addition, a homogeneous powder is defined by a predetermined and constant particle size where, for example, more than 80% or more than 90% or more than 95% of the particles have a size corresponding to a reference size. The particles are for example of micrometric size, i.e. with an average diameter of the order of 1 μm to 500 μm, or preferably 10 to 100 μm.The particles can alternatively be sub-micrometric, i.e. with an average diameter of less than one micrometer. The average particle size of mixed powders can be adapted according to the material considered and / or the result to be obtained.

[0032] The term "homogeneous" excludes multiphase or polyphase structures including, for example, inclusions within a matrix, which results in heterogeneous mixtures. The term "homogeneous" here is synonymous with single-phase or monophasic. The term "homogeneous" applies to all mixed powders, composites and additional materials, as well as their combination.

[0033] For the purposes of this description, a "homogeneous structure" means the material resulting from the process described herein, based on one or more powders according to the present invention, whether juxtaposed or mixed. Although they may have different optical or physical properties, the juxtaposed powders result in a structurally homogeneous material, in particular with regard to its particle size. In particular, a homogeneous structure excludes any inclusion of a particle size greater than 5% or 10% or 20% of the average particle size of the powders used in its composition. A homogeneous structure is here synonymous with a single-phase or monophasic structure.

[0034] The method comprises a step S3 of arranging in a mold the powders obtained separately, regardless of their number, including at least one mixed powder PMi. The method thus comprises a step S3 of arranging the first mixed powder PM1 and at least one second powder. The at least one second powder may be a Pd powder of a distinct material Md. The distinct material Md may be chosen from pure metals, in particular pure gold or a precious metal, or gold alloys, or precious metal alloys not comprising gold. Alternatively or in addition, the at least one second powder may be a second mixed powder PM2. The second mixed powder comprises at least one gold. In this way, an assembly of at least two powders may be formed in which at least one of the powders consists of a mixed powder as described above.It is understood that the mixed powders and powders of distinct material all remain distinct from each other and are not mixed during the process. The different powders are in other words juxtaposed or contiguous or superimposed, so as to preserve their properties, and in particular the color which characterizes them. Preferably, the different powders are brought into contact with each other, this makes it possible to produce colored patterns such as gradients or designs or visual effects. such as camouflage patterns or the like. This does not exclude that the different powders can be separated from each other by a partition, such as a metal partition producing a pattern in itself. The powders are preferably arranged sequentially so as not to mix. They can each be arranged so as to form a powder bed, or a powder cluster or in different arrangements such as in the form of lines, or geometric or seemingly random, although reproducible, figures. Depending on the needs, one or more of the mixed powders can be used several times, for example to form several clusters, or several lines or on several layers alternating with other powders.

[0035] It is understood that two juxtaposed powders are selected so that their expected colors at the end of the process differ from each other.

[0036] The mold used is suitable for sintering the powders placed inside it. In particular, the mold is suitable for flash sintering or SPS sintering (spark plasma sintering). The use of electrodes to heat the assembly of unmixed powders allows for very short heating times and preserves the fineness of the grains.

[0037] According to one embodiment, the powders may be subjected to vibrations or any other operation to densify them or distribute them better if necessary. It is then appropriate to ensure that the mixed powders do not mix during these operations, if they take place.

[0038] The mixed powders are arranged relative to each other according to the color patterns to be obtained. In other words, a mixed powder positioning plan can be developed, which allows the powders, identified by their colorimetric characteristics, to be arranged at predetermined locations and in predetermined spaces in the mold. The resulting patterns are thus reproducible.

[0039] The method comprises a step S4 of carrying out solid-phase sintering under conditions making it possible to produce a solid part from the assembly of powders arranged in the mold. The sintering is preferably flash or SPS sintering carried out at a sintering temperature Tfri and a sintering pressure Pfri determined so that none of the powders, and in particular none of the mixed powders, melts. For example, the melting temperature of gold at atmospheric pressure is approximately 1064°C. The melting temperatures of gold alloys are generally higher than this value. The sintering pressure Pfri may in this case be a mechanical pressure. Preferably, the sintering temperature Tfri is determined so as to remain lower than the lowest of the melting temperatures of the mixed powders PMi under the sintering conditions.The appropriate sintering temperature Tfri can be assessed based on the sintering pressure Pfri, so as not to reach or exceed, or to remain below the melting temperatures of the mixed powders at the sintering pressure Pfri. The temperatures are also adapted so as not to degrade any structural elements incorporated into the powders, such as separating elements.

[0040] According to one embodiment, the sintering temperature Tfri is less than 2000°C, or even less than 1500°C, or even less than 1000°C. The sintering temperature is for example between 600°C and 1600°C.

[0041] The sintering pressure Pfri can be between 20 and 180 N / mm 2 or between 50 and 100 N / mm 2 . Other pressure values ​​may be preferred depending on the components selected and / or the required quality of the final mechanical part.

[0042] After sintering, the PMi mixed powders lead to as many Ai gold composites. For example, the first PM1 mixed powder leads to a first A1 gold composite, the second PM2 mixed powder leads to a second A2 gold composite, etc.

[0043] The part resulting from sintering is a single part comprising several distinct materials agglomerated together. The materials can be independently selected from gold alloys, pure gold and mixed powders such as those described above. The part therefore locally comprises different compositions. According to one embodiment, the part comprises at least one composite derived from a mixed powder such as described above. Being produced for their different colors, the mixed powders give the resulting part as many different colors as those which characterize the composites used.

[0044] The method comprises a step S5 of demolding the solid part to obtain a demolded part, typically a pellet, a preform or a blank. The demolded solid part may correspond to the final component. However, the demolded part may require one or more subsequent interventions to improve its quality or aesthetic appearance or to modify its shape to obtain the final component 1. A grinding step S6 may, for example, allow the demolded solid part to be resized. A machining step S7 may be carried out conventionally to modify the solid part by any suitable technique, whether mechanical, laser, water jet or any equivalent. One or more finishing steps S8 may also be envisaged. Other post-sintering transformations may be provided depending on the needs.

[0045] Alternatively or in addition, the demoulded solid part can be finished by one or more decorative operations such as satin finishing, beading, mirror polishing or micro-blasting, locally or over its entire surface.

[0046] The nature of the first gold 01, of the second material, in particular of the second gold 02 and of any additional materials Mi, as well as their proportions in the corresponding mixtures are determined so that the resulting mixed powder PM1 produces a first composite A1 of color C1 under the process conditions. The first color C1 is not however not necessarily identical to that of the corresponding mixed powder PM1 before the sintering operation. It may also be difficult to precisely characterize the color of the mixed powder before sintering. It should therefore be ensured that during the process, the mixed powders produced upstream lead to the corresponding composites Ai having the appropriate color. The nature of the at least one second first 01' and second 02' ors and any second additional materials Mi', as well as their proportions in the mixture are also determined so that the resulting mixed powder(s) PM2 produce a second composite A2 - or several other composites Ai, of color C2 and Ci respectively, under the process conditions. The second color C2 is different from the first color C1. The other colors Ci are also different.

[0047] The various composites Ai are each developed and produced so as to have a color Ci corresponding to a predetermined color. The various composites Ai represent gold composites combining at least one gold and one other material. The gold may be selected, for example, from pure gold, white gold alloys, pink gold alloys, gray gold alloys, green gold alloys, yellow gold alloys, blue gold alloys, violet gold alloys, and red gold alloys. Typically, the other material refers to a precious metal or an alloy of precious metals. It may also refer to non-precious metals and their alloys. Preferably, the various composites Ai represent gold composites combining at least two golds. The two golds may be independently selected from those mentioned above or others.The present description covers in this context a means of determining the composition of these composites Ai as a function of the colors to be obtained on the finished part. The method described here may comprise one or more calibration steps Se consisting of selecting and mixing at least one gold and a second material as described in steps S1 and S2 above, for example, so as to constitute a mixed powder, and of determining the visual characteristics thereof. The visual characteristics are in particular determined after a sintering operation representative of the conditions applied to the manufacture of the part. The visual characteristics of a. mixed powder can be determined by any means in force such as colorimetric tests.

[0048] According to one embodiment, a colorimetric test may be based on a color space of type L* a* b*, where L* denotes lightness and can take values ​​from 0 to 100, where a* denotes the axis going from green to red and where b* denotes the axis going from blue to yellow. Figure 4 represents an example of such a color space used to characterize the colors of the parts obtained. Other characterization systems may nevertheless be used.

[0049] A calibration step Se1 according to the present description may consist of producing several mixed powders comprising a gold and a second determined material, or two determined golds, in variable proportions, of involving them in a sintering operation such as that described above, so that the mixed powders produce the corresponding composites, and after demolding of characterizing the colors thereof. Figure 1 gives an example of such a calibration curve of the a* and b* values ​​of the following composites: 75% Pd150 / 25% 5N18 50% Pd150 / 50% 5N18 25% Pd150 / 75% 5N18 100% 5N18 where the term 5N refers to a 5N red gold alloy and Pd150 refers to a nickel-free 18ct white gold alloy, both alloys being marketed by the PX Group company. A composite material used for the manufacture of a watch element or a timepiece may correspond to one of these compositions or to an intermediate composition depending on the targeted color.

[0050] Several similar curves can be constructed based on several other golds. In addition, other parameters than a* and b* can be determined. In particular, the parameters L*, a* and b* can be determined either individually, or in binary combination in two-dimensional space, or all together in three-dimensional space.

[0051] According to one embodiment, a calibration step Se2 may consist of producing several mixed powders each comprising a mass percentage of a variable element, involving them in a sintering operation such as that described above, and after demolding, characterizing one or more of the parameters L*, a* or b*. In this way, the influence of one of the golds on one or other of the parameters L*, a* and b* can be precisely determined. Figure 2 gives an example of such a calibration curve, making it possible to determine the influence of 5N gold on the parameter a*.

[0052] The nature and proportions of the golds mixed in each of the mixed powders can thus be determined on the basis of one or more calibration curves such as those developed during one or other of the calibration steps Se1 and Se2 described above. According to one embodiment, an extrapolation or interpolation of the calibration points makes it possible to determine the nature and / or proportions of the golds to be mixed to obtain an alloy of a predetermined color. According to another embodiment, a computer-implemented predictive model can be used. In this case, the final colors of a part to be produced can be selected on an appropriate graphical interface. The model then makes it possible to determine the compositions of the corresponding mixed powders. According to one embodiment, other parameters can also be proposed by the program, such as the temperature and pressure conditions of the sintering operation.In other variants, other input values ​​than colors can be implemented in the program. For example, hardness or density properties can be subject to secondary selection and allow the colors to be adapted to other physical constraints such as resistance to rubbing and scratching.

[0053] The calibration steps Se1 and Se2 described above can be based on materials other than gold, in particular additional materials Mi possibly used in the design of mixed powders PMi.

[0054] The calibration step(s) are preferably carried out prior to the powder selection steps S1 and / or mixing S2, on calibration parts produced according to the process described here. In this way, the composition of the powders can be determined according to the colors to be obtained at the end of the process, which makes it possible to avoid multiple trial and error attempts to obtain a part of the required color.

[0055] Additives may also be included in the composition of mixed powders. Such additives may include metal oxides or pigments, which may also be the subject of calibration curves.

[0056] According to a preferred embodiment, the mixed powders prepared according to the method described herein do not comprise any pigment. Preferably, the mixed powders consist exclusively of a mixture of two or more golds. Alternatively, the mixed powders according to the present method consist exclusively of a mixture composed of at least two golds, a precious or noble metal and / or a non-precious metal such as those mentioned above or their alloys. Alternatively, the mixed powders according to the present method consist, or consist exclusively, of two or more golds and a precious or noble metal. Alternatively or in addition, the mixed powders according to the present method do not comprise more than one pure gold.

[0057] The golds involved in the present method may be acquired in the form of powders. Alternatively, the method according to the present description comprises one or more steps of atomizing the golds. For example, the method may comprise a step 51a of atomizing the first gold 01 so as to produce said first powder P1. It may further comprise a step S1b of atomizing said second material, for example a second gold 02 independently of the first gold, so as to produce said second powder P2. It may alternatively or additionally comprise a step Sli of atomizing the additional materials where appropriate, so as to produce the corresponding powder(s) Pi. The same atomizing steps may be reproduced for one or more of the other powders. In particular, the method may comprise a step S1a' of atomizing the second first gold 01' so as to produce the second first powder P1', a step S1b' of atomizing the second second material, for example a second second gold 02' so as to produce the second second powder P2' and / or a step S1i' of atomizing any additional second materials Mi' so as to produce the corresponding powder(s) Pi'.Preferably, the atomization steps S1a, S1a' etc. make it possible to control the properties of the powders obtained, in particular their particle size, the distribution of particle sizes, etc. The atomization conditions can be identical for all the powders or vary depending on the materials used or the results to be obtained.

[0058] The method according to the present description may further comprise one or more subsequent steps of transformation of the demolded solid part. It may for example comprise a step S6 of grinding the demolded solid part to the desired thicknesses, a machining step S7, and / or a step S8 of finishing the demolded solid part. Alternatively or in addition, the method described here may comprise one or more steps among operations such as satin finishing, circular graining, mirror polishing or micro-blasting, depending on the properties of the timepiece element to be obtained.

[0059] The present description further covers a timepiece component resulting from the method described herein. In particular, the present description covers a timepiece component comprising at least one gold-based composite A1, composed of a first gold 01, and at least one other material, such as a second gold 02, and one or more optional additional materials Mi, Mi', forming an inseparable assembly. Typically, the present description covers a timepiece component comprising at least two gold-based composites A1, A2, each composed of a first gold 01, 01' and at least one other material, such as a second gold O2, O2', and one or more possible additional materials Mi, Mi', forming an inseparable whole. The watch component is characterized by the fact that the gold-based composites remain distinct from each other and that they have colors C1, C2 distinct from each other. In particular, the colors of the composites A1, A2 or at least of some of the composites used, are different from the usual colors obtained by standard alloys. Preferably, a timepiece element according to the present description comprises three, four or more different composites A1, A2, specifically designed for their color. The watch component is further characterized by the fact that the composite(s) remain distinct from any distinct materials that they contain.

[0060] A watch component, or watch component, can refer to any element used in the composition of a timepiece. A watch component can, for example, refer to a case middle, a bezel, a back, a crown, a winding mass or bracelet elements such as studs, links, pins or a clasp. Other watch components, including components that are part of the movement, can be produced according to the terms set out here.

[0061] Figure 3 illustrates an example of a watch component blank comprising several composites A1, A2. In this case, the blank shown in Figure 3 comprises a first central alloy flanked symmetrically by a succession of several different composites, thus producing a gradient of colors or shades from the center to the periphery of the component. Two golds are shown here whose mass proportions vary from 100% of one of the golds to 100% of the other of the golds. Other arrangements can nevertheless be provided. According to another embodiment, the different composites can be arranged in the form of concentric circles rather than bands. They can alternatively be arranged in a manner that could appear random, although reproducible, so as to create a specific visual effect.In this case, a central alloy is shown, but it can be replaced by pure gold, or another pure metal, precious or non-precious.

[0062] The composites A1, A2 obtained according to the process described herein can be combined with standard alloys. In other words, the watch element can comprise one or more composites resulting from the mixed powders described herein, assembled or associated with one or more standard alloys, available on the market.

[0063] The present description further covers a timepiece, such as a wristwatch, comprising at least one watch component as described herein. Preferably, the timepiece is designed so that the watch component is visible to the user. The visual effects may appear on a casing element, such as the case middle or a portion thereof, as well as on other elements constituting or integrating the timepiece such as elements of the movement. Furthermore, the visual effects may be reproduced on several components of the same timepiece, thus producing an enhanced aesthetic effect. For example, the links or a portion of the links of the bracelet may reproduce the visual effects of the case middle or another component.Alternatively or in addition, different components of the timepiece may have a solid color resulting from one of the mixed powders produced according to the method described herein, so that the different components have a color distinct from each other. It is understood that the variety of different arrangements is not limited and that the present invention offers numerous possibilities. Examples 1 Different alloys of white (B) and pink (R) gold are produced and characterized by colorimetry according to the parameters L*, a* and b*: Atomization of a white gold alloy (B) of composition: Au750 PdCu150 Atomization of a rose gold alloy (R) of composition: Au750 Ag45 Cu205 The white (B) and pink (R) gold alloys in powder form are weighed and mixed in the turbula. The different compositions obtained are referenced from A1 to A5: Pellets are formed by sintering compositions A1, A2, A3, A4 and A5. The sintering is SPS (Spark Plasma Sintering) with the following characteristics: - pressure force between 5 MPa and 200 MPa - Sintering temperature between 300°C and 1200°C - Sintering time between 10 min and 2 h. The pellets obtained are then demolded and the colorimetric parameters L*, a* and b* are determined (table 1). Table 1 Figure 1 shows that the evolution of the colors is proportional to the concentrations of two alloys A and R. Figure 2 shows the evolution of the a* coordinate as a function of the mass percentage of 5N gold. The piece obtained has a 18-carat gold content. Example 2 Atomization of a white gold alloy (C) titrating 22 carats of composition: Au925 Pd75 Atomization of a rose gold alloy (D) titrating 22 carat with composition: Au917 Cu83 The white (C) and pink (D) gold alloys in powder form are weighed and mixed in the turbula. The composition obtained is referenced A6 (table 2): Table 2 A pellet is formed by sintering the A6 composition. The sintering is SPS (Spark Plasma Sintering) with the following characteristics: pressure force between 5 MPa and 200 MPa - Sintering temperature between 250°C and 1300°C - Sintering time between 10 min and 2 hours The resulting pellet is removed from the mold. The resulting piece has a 22-carat content. Example 3 Atomization of a white gold alloy (A) titrating 18 carats of composition: Au750 PdCu150 Atomization of a rose gold alloy (D) titrating 22 carats of composition: Au917 Cu83 Atomization of a non-precious titanium alloy grade 5 (E) of composition: TI6AI4V. The alloys of white gold (A) and pink gold (D) and titanium (E) in powder form are weighed and mixed in the turbula. The composition obtained is referenced A7 (table 3): Table 3 The quantities of alloys (A), (D) and (E) must comply with the following equation (E1): (E 1 ): VmA x %A + VmD x %D + VmE x %E> 75% where VmA, VmD and VmE denote respectively the mass percentages of precious materials in alloys A, D and E, and where %A, %D and %E denote respectively the mass percentages of alloys A, D and E in the part. In this way, the final piece is 18 carat. A pellet is formed by sintering the A6 composition. The sintering is SPS (Spark Plasma Sintering) with the following characteristics: - pressure force between 5 MPa and 200 MPa - Sintering temperature between 350°C and 1400°C - Sintering time between 10 min and 2 hours The resulting pellet is removed from the mold. The resulting piece is a gold / titanium composite weighing 18 carats. In each of the above examples, the demolded pellet can be machined by any conventional means such as milling on a 5-axis machine. A timepiece such as a winding mass, a case middle, a bezel, a back, a crown, or bracelet elements such as studs, links, pins or a clasp can be obtained. The resulting part can be decorated by one or more satin-finishing, circular-graining, mirror-polishing or micro-blasting operations.

[0064] The method for manufacturing a watch component (1) based on at least one composite comprising a composite of 18 carats and more according to the present description may be characterized by one or more of the following elements:

[0065] It comprises a first selection step S1 of at least a first gold (01) in the form of a first powder (P1), a second material in the form of a second powder (P2) and optionally one or more additional materials (Mi) different from the first gold (01) and the second material, in the form of as many corresponding additional powders (Pi),

[0066] a first step S2 of mixing said first (P1), second (P2) powders and where appropriate the additional powder(s) (Pi) in predetermined proportions so as to produce a first homogeneous mixed powder (PM1),

[0067] at least one step of selecting a distinct material (Md) in the form of one or more powders (Pd), intended to be combined with said first mixed powder (PM1) without mixing with it.

[0068] a step S3 of placing in a mold (2) said first mixed powder (PM1) and said one or more powders (Pd) of distinct materials (Md), so as to form an assembly of at least two powders, in which said powders are not mixed with each other,

[0069] a step S4 of carrying out sintering, the sintering being flash or SPS type sintering carried out at a sintering temperature (Tfri) and a sintering pressure (Pf) determined so that none of the powders (PM1, Pd) melts,

[0070] a step S5 of demolding the part resulting from the sintering step S4 to obtain a demolded part,

[0071] The nature of the first gold (01) and the second material and of the possible one or more additional materials (Mi) and / or the proportions of their mixture can be determined so that said first mixed powder (PM1) is suitable for producing a first composite (A1) of color (C1) under the conditions of the process, and in that the distinct material (Ad) results in a color (Cd) under the conditions of the process, such that the color (C1) of the first composite differs from the color (Cd) of the distinct material (Ad).

[0072] The second material may denote a second gold (02), a precious metal other than gold or an alloy of precious metals not containing gold.

[0073] The distinct material (Md) designating a precious metal, an alloy of precious metals or a mixed powder suitable for producing a composite under the conditions of said process.

[0074] The distinct material (Md) may be a second mixed powder (PM2) comprising at least one gold. The selection of one or more distinct materials (Md) comprises a second selection step 51' of a second first gold (01') and at least one second second material in the form of a second first (PV) and at least one second second (P2') powder respectively and one or more possible additional second materials (Mi') in the form of as many additional second powders (Pi') and at least one second mixing step 52' of the second first (PV) and at least one second (P2') powders and where appropriate one or more additional second powders (Pi'), so as to produce at least one second mixed powder (PM2),where the nature of the second first gold (01 ') and second second materials and of the possible second additional materials (Mi') and / or the proportions of their mixture are determined so that said at least second mixed powder (PM2) is suitable for producing a second composite (A2) of color (C2), different from (C1) under the conditions of the process.,

[0075] The second second material designating a second second gold (02'), a precious metal other than gold or an alloy of precious metals not containing gold.

[0076] Gold refers to pure gold or an alloy of gold.

[0077] Additional materials (Mi, Mi') can be selected from silver (Ag), platinum (Pt), palladium (Pd), osmium (Os), titanium (Ti), nickel (Ni), copper (Cu), aluminum (Al) and their alloys.

[0078] The first (P1), second (P2), second first (PV) second second (P2') powders are 18 carats or 22 carats.

[0079] The first mixed powder (PM1) and the one or more powders of distinct materials (Md) are arranged during step S3 so as to independently form one or more clusters, one or more lines, or several alternating layers.

[0080] The sintering temperature (Tf) is between 600°C and 1600°C.

[0081] Sintering pressure (Pfri) is a mechanical pressure between 20 and 180 N / mm 2 .

[0082] The method may further comprise one or more steps from a step S1a of atomizing said first gold (01) so as to produce said first powder (P1), a step S1b of atomizing said second material so as to produce said second powder (P2) and a step S1i of atomizing said additional materials so as to produce the corresponding powder(s) (Pi), a step S1a' of atomizing said second first gold (01') so as to produce the second first powder (P1'), a step S1b' of atomizing said second second material so as to produce the second second powder (P2') and a step S1i' of atomizing any additional second materials (Mi') so as to produce the powder (Pi').

[0083] The method may further comprise one or more of the steps S6 of grinding the demolded solid part to the desired thicknesses, S7 of machining the demolded solid part, S8 of finishing the demolded solid part, S9 of decoration comprising one or more satin finishing, perlage, mirror polishing or microblasting operations, so as to obtain said watch component.

[0084] The first color (C1) can be determined on the basis of at least one calibration curve developed during at least one prior calibration step Se.

[0085] A calibration curve according to the present method makes it possible to determine the proportions of gold, second material and any additional materials and / or their mass percentage in the mixed powders, depending on the color (C1) to be obtained, via an extrapolation or an interpolation of the parameters measured on said at least one calibration curve and / or via a predictive program implemented by computer.

[0086] The watch component according to the present description may be characterized by one or more of the following elements. It may comprise at least one composite, comprising a first gold (01, 01') and at least one second material as well as one or more possible additional materials (Mi, Mi'), forming an inseparable whole, and one or more distinct materials (Md) in which said at least one composite and the one or more distinct materials (Md) remain distinct from each other, said at least one composite having a color (C1) distinct from said one or more distinct materials (Md), so that their juxtaposition produces a visual effect, such as a gradient of colors or shades.

[0087] The at least one second material may designate a second gold (02, 02'), a precious metal or an alloy of precious metals not comprising gold.

[0088] The one or more distinct materials (Md) may refer to a precious metal, a precious metal alloy, or a composite. The watch component can be selected from a case middle, a bezel, a back, a crown, a winding mass or bracelet elements such as studs, links, pins or a clasp.

Claims

Claims 1. Method for manufacturing a watch component (1) based on at least one first homogeneous composite (A1) of predetermined color (C1), containing 18 carats or more, the method comprising: - a first selection step S1 of at least a first gold (01) in the form of a first powder (P1), a second material in the form of a second powder (P2) and optionally one or more additional materials (Mi) different from the first gold (01) and the second material, in the form of as many corresponding additional powders (Pi), - a first step S2 of mixing said first (P1), second (P2) powders and where appropriate the additional powder(s) (Pi) in predetermined proportions so as to produce a first homogeneous mixed powder (PM1), - a step S4 of carrying out sintering, the sintering being flash or SPS type sintering carried out at a sintering temperature (Tfri) and a sintering pressure (Pf) determined so that said first mixed powder (PM1) does not melt, at the end of which said first mixed powder (PM1) results in said at least one first composite (A1) of color (C1), - a step S5 of demolding the part resulting from the sintering step S4 to obtain a demolded part, characterized in that the nature of the first gold (01) and of the second material and of the possible one or more additional materials (Mi) and / or the proportions of their mixture are determined so that said first mixed powder (PM1) is suitable for producing a first composite (A1) of color (C1) under the conditions of the process.

2. Method according to claim 1, further comprising one or more calibration steps Se, making it possible to determine the visual characteristics of said at least one first composite (A1) as a function of its composition, so as to define the nature of the first gold (01) and of the second material and of the possible one or more additional materials (Mi) and said predetermined proportions to obtain said predetermined color (C 1 ) on the basis of said one or more calibration steps Se.

3. Method according to claim 2, said one or more calibration steps being carried out before the selection steps S1 and mixing steps S2.

4. Method according to one of claims 1 to 3, further comprising at least one step of selecting a distinct material (Md) in the form of one or more powders (Pd), intended to be combined with said first mixed powder (PM1) without mixing therewith and a step S3 of arranging in the mold (2) said one or more powders (Pd) of distinct materials (Md), so as to form an assembly of at least two powders with said first mixed powder (PM1) and in which said one or more powders (Pd) and said first powder (PMi) are not mixed with each other, where said distinct material (Md) results in a color (Cd) after the sintering step S4, distinct from the color (C1) of said first composite (A1).

5. Method according to one of claims 1 to 4, said one or more calibration steps comprising the mixing of at least one gold and a second material so as to produce a mixed powder, the mixed powder being involved in a sintering step to produce a composite, the visual characteristics of said composite then being determined.

6. Method according to one of claims 1 to 5, said visual characteristics being determined by colorimetric tests based on a chromatic space of type L*, a*, b*.

7. Method according to one of claims 1 to 6, said second material designating a second gold (02), a precious metal other than gold or an alloy of precious metals not comprising gold.

8. Method according to one of claims 1 to 7, said distinct material (Md) designating a precious metal, an alloy of precious metals or a mixed powder suitable for producing a composite under the conditions of said method.

9. Method according to one of claims 1 to 8, wherein said distinct material (Md) is a second mixed powder (PM2) comprising at least one gold, said selection of one or more distinct materials (Md) comprises a second selection step 51' of a second first gold (01') and at least one second second material in the form of second first (P1') and at least one second second (P2') powders respectively and one or more possible additional second materials (Mi') in the form of as many additional second powders (Pi') and at least one second mixing step 52' of said second first (PV) and at least one second (P2') powders and where appropriate one or more additional second powders (Pi'), so as to produce at least one second mixed powder (PM2), resulting in a second composite (A2) of color (C2), different from the color (C1) of the first composite (A1) under the conditions of process.

10. Method according to claim 9, the color of said second composite (A2) being predetermined and the nature of the second first gold (01') and second second materials and of the possible second additional materials (Mi') and / or the proportions of their mixture being determined on the basis of the one or more calibration steps Se so as to produce said color (C2) of the second composite under the conditions of the method.

11. Method according to one of claims 9 and 10, said second second material designating a second second gold (02'), a precious metal other than gold or an alloy of precious metals not comprising gold.

12. Method according to one of claims 1 to 11, in which gold denotes pure gold or a gold alloy.

13. Method according to one of claims 1 to 12, wherein said additional materials (Mi, Mi') are selected from silver (Ag), platinum (Pt), palladium (Pd), osmium (Os), titanium (Ti), nickel (Ni), copper (Cu), aluminum (Al) and their alloys.

14. Method according to one of claims 1 to 13, in which said first (P1), second (P2), second first (PV) second second (P2') powders have a titration of 18 carats or 22 carats.

15. Method according to one of claims 1 to 14, in which the first mixed powder (PM1) and the one or more powders of distinct materials (Md) are arranged during step S3 according to a predetermined positioning plan.

16. Method according to one of claims 1 to 15, in which the sintering temperature (Tf) is between 600°C and 1600°C.

17. Method according to one of claims 1 to 16, in which the sintering pressure (Pfri) is a mechanical pressure of between 20 and 180 N / mm 2 .

18. Method according to one of claims 1 to 17, further comprising one or more steps from a step S1a of atomizing said first gold (01) so as to produce said first powder (P 1 ), a step S1b of atomizing said second material so as to produce said second powder (P2) and a step S1i of atomizing said additional materials so as to produce the corresponding powder(s) (Pi), a step S1a' of atomizing said second first gold (01') so as to produce the second first powder (PV), a step S1b' of atomizing said second second material so as to produce the second second powder (P2') and a step S1i' of atomizing possible second additional materials (Mi') so as to produce the powder (Pi').

19. Method according to one of claims 1 to 18, further comprising one or more of the steps: 56 of rectification of the demolded solid part to the desired thicknesses, 57 machining of the demolded solid part, 58 to finish the demolded solid part, 59 decoration comprising one or more satin finishing, pearling, mirror polishing or micro-blasting operations, so as to obtain said watch component.

20. Method according to one of claims 1 to 19, in which said at least one preliminary calibration step allows at least one calibration curve to be established suitable for determining the proportions of gold, second material and any additional materials and / or their mass percentage in the mixed powders, as a function of the color (C1, C2) to be obtained, via an extrapolation or an interpolation of the parameters measured on said at least one calibration curve and / or via a predictive program implemented by computer.

21. Watch component comprising at least one first homogeneous composite (A1), of color (C1) comprising a first gold (01, 01') and at least one second material as well as one or more possible additional materials (Mi, Mi'), forming an inseparable and homogeneous whole, the nature of the first gold (01) and of the second material and of the possible one or more additional materials (Mi, Mi') and their proportions being defined so that the color (C1) corresponds to a predetermined color on at least one of the first gold (01, 01') and at least one second material as well as one or more possible ... at least one calibration curve, said at least one first composite (A1) forming a predetermined pattern.

22. A watch component according to claim 21, further comprising one or more distinct materials (Md) of color (Cd), wherein said at least one first composite (A1) and the one or more distinct materials (Md) remain distinct from each other, said at least one first composite (A1) having a color (C1) distinct from the color (Cd) of said one or more distinct materials (Md), such that their juxtaposition produces a predetermined visual effect.

23. Watch component according to one of claims 21 and 22, said at least one second material designating a second gold (02, 02'), a precious metal or an alloy of precious metals not comprising gold.

24. Watch component according to one of claims 21 to 23, said one or more distinct materials (Md) designating a precious metal, an alloy of precious metals or a composite.

25. Watch component according to one of claims 21 to 24, said at least one composite (A1) having one of the following compositions: 75% Pd150 / 25% 5N18 50% Pd150 / 50% 5N18 25% Pd150 / 75% 5N18 100% 5N18 where 5N denotes a 5N red gold alloy and Pd150 denotes a nickel-free 18ct white gold alloy.

26. Watch component according to one of claims 21 to 25, comprising a white gold alloy (B) of composition Au750 PdCu150, a pink gold alloy (R) of composition Au750 Ag45 Cu205 in the following proportions: or comprising a white gold alloy grading 22 carats of composition Au925 Pd75 and a pink gold alloy grading 22 carats of composition Au917 Cu83 in a mass proportion of 67 / 33, or comprising a white gold alloy (A) grading 18 carats of composition Au750 PdCu150, a pink gold alloy (D) grading 22 carats of composition Au917 Cu83 and a non-precious alloy (E) of grade 5 titanium in which the mass proportion of the alloys is determined by the following equation: VmA x %A + VmD x %D + VmE x %E> 75% where VmA, VmD and VmE denote the mass percentages of precious materials in alloys A, D and E respectively, and where %A, %D and %E denote the mass percentages of alloys A, D and E in the part respectively.

27. Watch component according to one of claims 21 to 26, said watch component being selected from a case middle, a bezel, a caseback, a crown, a winding mass or bracelet elements such as studs, links, pins or a clasp.

28. Timepiece comprising a timepiece component according to one of claims 21 to 27.

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