Black-colored decorative thin tialc coating

Abstract

The invention relates to a watch component (1) at least partially covered with a decorative coating (20) comprising at least one layer (20A) based on titanium and aluminum carbide stacked with at least one layer (20B) based on oxide allowing to obtain a decorative coating (20) with a black appearance with a reflectance of less than 5% on the human visible spectrum.

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a thin decorative coating offering a deep black colour appearance. TECHNICAL BACKGROUND OF THE INVENTION

[0002] Historically, black has been a highly sought-after color in watchmaking. However, achieving such a color in a thin layer (to be suitable for watchmaking applications) is difficult without iridescence (localized color variations that change depending on the viewing angle). Furthermore, these coatings are generally poorly adherent (weak adhesion prevents contact applications) and may require specialized machinery.

[0003] Coatings used in watchmaking include black electroplating, black DLC coatings, and carbon nanotubes (CNTs). Carbon nanotubes are particularly attractive because they allow for a very deep black color. For example, the Vantablack coating (carbon nanotubes) is currently renowned for producing the deepest black (see, in particular, patent documents CH 711 141 and EP 3 327 517).

[0004] Carbon nanotubes, however, remain very problematic to implement. The coating application process is complex, requiring highly specialized machinery, which makes it difficult and expensive. Furthermore, adhesion is poor on virtually any material, making it impossible to guarantee the coating's durability over time, even if it is not intended as a contact coating like a watch dial. Finally, carbon nanotube dust particles are very small and classified as carcinogenic. They can pose a risk to operators (during manufacturing or maintenance), negatively impact the long-term aesthetics (when deposited on visible parts), and disrupt the proper functioning of the watch movement (when deposited on moving parts). SUMMARY OF THE INVENTION

[0005] The invention aims to provide a decorative coating for a watch component that provides a decorative coating with good adhesion, high aesthetic durability, low thickness, a black appearance, and low reflectance.

[0006] To this end, according to a first embodiment of the invention, the invention relates to a watch component formed of a body based on a material to be decorated which is at least partially covered with a decorative coating, characterized in that the decorative coating comprises at least one layer based on titanium and aluminum carbide having a thickness of at least 200 nm stacked with at least one layer based on oxide having a thickness of at least 30 nm allowing to obtain a decorative coating adhering to the black appearance with a reflectance of less than 5% on the human visible spectrum.

[0007] Advantageously, according to the first embodiment of the invention, the material already present on the watch component is of little importance. Typically, from 230 nm of total thickness of decorative coating (an individual or cumulative thickness of at least 200 nm added to an individual or cumulative thickness of at least 30 nm), i.e. including the stacking of titanium carbide and aluminum-based and oxide-based layers, it becomes possible to obtain a very deep black tint with good adhesion, high aesthetic durability, low reflectance and low luminance.

[0008] Finally, an atomic layer deposition (ALD) or physical vapor deposition (PVD) machine is sufficient to form the deposit; that is, no specific machine is required. Consequently, the watch component is simpler to manufacture, without excessive thickness, and thus benefits from a durable and advantageous aesthetic effect.

[0009] According to a second alternative embodiment of the invention, the invention relates to a watch component formed of at least one body based on a decoration material based on nickel or zinc, and which is at least partially covered with a decorative coating, characterized in that the decorative coating comprises at least one titanium and aluminum carbide-based layer of at least 40 nm stacked with at least one oxide-based layer of at least 40 nm allowing to obtain a decorative coating with a black appearance with a reflectance of less than 5% on the human visible spectrum.

[0010] Advantageously, according to the second embodiment of the invention, a nickel- or zinc-based material already present on the watch component allows for limiting the thickness of the decorative coating layers. This material can be, for example, based on a Ni-Au, Ni-Zn, or Zn-Ni alloy. Typically, with a total decorative coating thickness of 80 nm, including the stacked layers of titanium carbide and aluminum and oxide-based materials, it becomes possible to obtain a very deep black shade with good adhesion, high aesthetic durability, low reflectance, and low luminance. The watch component is therefore simple to manufacture, without significant added thickness, and thus benefits from a durable and advantageous aesthetic effect.The nickel-based decoration material may comprise pure nickel (Ni), 50 to 70% nickel by total weight of the alloy and the remaining 30 to 50% gold (Ni-Au), or 50 to 97% nickel by total weight of the alloy and the remaining 3 to 50% zinc (Ni-Zn). The zinc-based decoration material may comprise pure zinc (Zn) or 60 to 80% zinc by total weight of the alloy and the remaining 20 to 40% nickel.

[0011] Regardless of the embodiment, the invention may also include one or more of the following optional features, taken alone or in combination.

[0012] The decorative coating may comprise several layers based on titanium and aluminum carbide and several layers based on oxide. The decorative coating according to the invention may thus comprise a stack of at least two layers based on titanium and aluminum carbide and one layer based on oxide, a stack of one layer based on titanium and aluminum carbide and at least two layers based on oxide, or a stack of at least two layers based on titanium and aluminum carbide and at least two layers based on oxide, without departing from the scope of the invention.

[0013] The coating thickness is preferably no more than 1000 nm, which ensures compatibility with watchmaking applications, meaning it does not excessively increase the thickness (vertical axis) of the watch component with the decorative coating. Advantageously, the decorative coating according to the invention does not require a thickness of 1000 nm or more to achieve the desired black appearance, regardless of the material of the watch component's body.

[0014] Said at least one oxide layer may be formed from aluminum oxide, zinc oxide, titanium oxide, silicon oxide, zirconium oxide, tantalum oxide, and / or hafnium oxide. Advantageously, such at least one oxide layer has a different refractive index than said at least one layer based on titanium and aluminum carbide in order to achieve the interference effect capable of preventing the reflection of all or most of the wavelengths of the human-visible spectrum from an incident light flux. Typically, a difference in refractive index of at least 0.2 and preferably at least 0.6, i.e. for example equal to 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0015] Furthermore, the invention also relates to a timepiece comprising a watch movement, characterized in that it includes a watch component as described above. The watch component according to the invention may thus form all or part of a component of the case or the watch movement of the timepiece.

[0016] Finally, the invention also relates to a method for manufacturing a watch component as described above, characterized in that the method comprises the following steps: a - to form a body; b - to deposit, on at least part of the body, a decorative coating; characterized in that step b of the decorative coating application comprises the following phases: b1 - deposit at least one layer based on titanium and aluminum carbide; b2 - deposit at least one layer based on oxide.

[0017] Due to the nature of the deposited materials, the advantageous process according to the invention can be implemented by atomic layer deposition (ALD) or physical vapor deposition (PVD), which are machines commonly found in watchmaking companies; that is, no specific machine is required. Consequently, the process is simpler to implement, does not encounter any particular adhesion difficulties for the decorative coating, and allows for a decorative coating with a long-lasting, aesthetically pleasing, deep black finish.

[0018] The invention may also include one or more of the following optional features, taken alone or in combination.

[0019] At least one of the phases b1 and b2 of step b is preferably carried out by an ALD method in order to obtain deposition thickness accuracies on the order of nanometers. Of course, other vacuum deposition methods are possible to obtain step b, such as, for example, physical vapor deposition or chemical vapor deposition, without departing from the scope of the invention.

[0020] When step b is obtained from an ALD method, step b is preferably carried out at least 150 °C. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other features and advantages of the invention will become clear from the description given below, which is by way of example and in no way limiting, with reference to the attached drawings, in which: there figure 1 is a schematic view of an example of a timepiece comprising a timepiece component according to the invention; the figure 2is a cross-sectional view of an example of a first embodiment of a watch component according to the invention; the figure 3 is a cross-sectional view of an example of a second embodiment of a watch component according to the invention; the figure 4 is a cross-sectional view of an example of a variant of the first embodiment of a watch component according to the invention; the figure 5 is a perspective view of an example of a watch component according to the invention. DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT OF THE INVENTION

[0022] In the various figures, identical or similar elements bear the same references, possibly with an additional subscript. Therefore, a description of their structure and function is not systematically repeated.

[0023] In all that follows, orientation terms are understood with respect to the orthogonal coordinate system taken with reference to the normal direction of travel of the motor vehicle 10, represented on the figure 1and in which we can distinguish: a longitudinal axis X, horizontal extending from left to right; a transverse axis Y, horizontal extending from front to back; and a vertical axis Z, extending from bottom to top.

[0024] The term "horizontal" is defined in relation to the XY plane (parallel to the two main faces of the watch movement plate), the terms "vertical plane" are defined in relation to a horizontal component projected along the vertical Z axis.

[0025] The term "based on" means a material or alloy constituting at least 50% by total mass or weight of a given element, such as, in particular, 51%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 100% by total mass. In what follows, unless otherwise stated, all percentages (%) are expressed as percentages by total mass or weight.

[0026] By "human visible spectrum" we mean the range of wavelengths between 380 and 780 nm as defined by the ISO / CIE 11664-3:2019 standard of the International Commission on Illumination "CIE".

[0027] By "low reflectance coating" we mean a thin coating deposited on a surface where the proportion of light reflected by the surface of the coating is low, that is to say less than 5% and preferably 1% on the human visible spectrum measured by colorimetry.

[0028] A "low luminance coating" is defined as a thin coating applied to a surface whose lightness L* in the CIE 1976 L*a*b* color space is less than 6 in the human visible spectrum as measured by spectrophotometry. In the tests performed, parameters a* and b* with absolute values ​​of less than 4 were also observed.

[0029] By "good adhesion coating," we mean a coating that withstands the NIHS adhesion tests ("tape test") using a tape previously applied to the coating (such as, for example, with 3M 600 or 3M 845 products from 3M®). In effect, the adhesion is either good because the coating remains intact during the adhesion test, or poor because the coating is partially or completely delaminated (at least part of the coating remains on the tape) during the adhesion test.

[0030] By "thin deposit" is meant a thin layer of solid material deposited (on a surface) whose thickness is substantially between 1 nm and 1000 nm such as a layer 20, 20A, 20B, 20C, 20D implemented by step b of the process according to the invention or an intermediate layer 15 forming part of the body. The thin-layer deposition can thus include a thickness of deposited material equal to 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm or 1000 nm.

[0031] The purpose of the thin decorative coating 20 according to the invention is to obtain an optical configuration capable of absorbing all or most of an incident light flux in order to give the decorative coating 20 a very deep black tint, that is to say, in particular, with low reflectance and low luminance. Furthermore, the purpose of stacking at least one thin titanium-aluminum carbide-based layer 20A, 20C and at least one thin oxide-based layer 20B, 20D is to obtain an interference phenomenon capable of preventing the reflection of all or most of the wavelengths of the human visible spectrum from an incident light flux in order to obtain a very deep black tint for the decorative coating 20.

[0032] By "pure metal," we mean a material theoretically composed of 100% by total mass or weight of a given metal, that is, without any other alloying metal. In practice, depending on the manufacturing process, the resulting material may contain so-called contaminants whose proportion by weight does not exceed 0.2% of the total mass of the alloy. This generally prevents obtaining 100% metal by total mass, resulting in a proportion between 97% and 100%.

[0033] By "oxide" we mean all materials in crystalline and / or amorphous form based on a molecule (M x O y) comprising the element oxygen (O), such as in particular a metallic oxide (M being a metal), such as aluminium oxide (alumina, Al 2 O 3 ), zinc oxide (ZnO), titanium oxide (TiOz), silicon oxide (SiO 2 ), zirconium oxide (zirconia, ZrO 2 ), tantalum oxide (TazOs) and hafnium oxide (HfO 2 ).

[0034] By "horological component 2", we mean all types of timekeeping or measuring instruments such as clocks, small clocks, watches, etc...

[0035] By "watch movement 3", we mean all types of mechanisms capable of counting time whether they are powered by mechanical energy (e.g. a barrel) or electrical energy (e.g. a battery).

[0036] By "housing 4", we mean all types of devices capable of containing, displaying, decorating and / or controlling a watch movement such as, for example, all or part of a case, a bracelet or a display.

[0037] Component 1 was developed for use in the watchmaking industry. Therefore, the component can form all or part of a watch case, such as all or part of a dial 1A ( figure 1) or a flange, a display 4 such as a hand or a disc, a case, a bracelet, a crystal or a control element such as a crown or a push-button. Component 1 may also form all or part of a part of a watch movement 3 such as all or part of an escapement device such as a Swiss lever mechanism, a resonator such as a balance-spring mechanism, a power source such as a barrel, a self-winding system or a battery, a gear train such as a moving part or a toothed wheel 1B ( figure 5 ), of a spring, a screw, a bridge or a plate.

[0038] The invention provides two embodiments depending on whether the material of the watch component 1 is less suitable for obtaining the black appearance with low reflectance, such as, for example, silver, copper, brass, or gold. It is understood that, depending on the type of material of the watch component 1, a thin intermediate layer 15 based on nickel or zinc (or even if the watch component 1 is nickel- or zinc-based) could be deposited before the decorative coating 20 according to the second embodiment of the invention explained below.

[0039] The invention relates to a watch component 1 formed of a body 10 made of a material to be decorated, which is at least partially covered with a decorative coating 20 as illustrated in the figure 2Advantageously, according to the invention, the decorative coating 20 comprises at least one layer 20A, 20C based on titanium aluminum carbide (TiAIC) stacked with at least one layer 20B, 20D based on an oxide. This stacking provides an optical configuration capable of absorbing all or most of the incident light flux, thus giving the decorative coating 20 a very deep black tint, i.e., in particular, with low reflectance and low luminance. Furthermore, this coating 20 according to the invention, due to the materials used, inherently possesses good adhesion to all common watchmaking materials tested; that is, the coating 20 according to the invention consistently withstood the adhesion tests ("tape test") on all common watchmaking materials tested. It is therefore understood that the invention makes it possible to obtain a coating 20 with high aesthetic durability.

[0040] According to a first embodiment of the invention, regardless of the nature of the material of the watch component 1, in order to obtain a decorative coating 20 adhering to the black appearance with a reflectance of less than 5% on the human visible spectrum, said at least one layer 20A, 20C based on titanium and aluminum carbide has, individually or cumulatively, a thickness (vertical axis Z) of at least 200 nm, i.e. the thickness of a single layer 20A or 20C or the cumulative thickness of several layers 20A, 20C, while said at least one layer 20B, 20D based on oxide has, individually or cumulatively, a thickness (vertical axis Z) of at least 30 nm, i.e. the thickness of a single layer 20B or 20D or the cumulative thickness of several layers 20B, 20D.

[0041] Advantageously, according to the first embodiment of the invention, the material already present on the watch component 1 is of little importance. Typically, with a total thickness (vertical axis Z) of 230 nm of decorative coating 20 (an individual or cumulative thickness of at least 200 nm plus an individual or cumulative thickness of at least 30 nm), i.e., comprising the stacking of titanium and aluminum carbide-based and oxide-based layers 20A, 20B, 20C, and 20D, it becomes possible to obtain a very deep black shade with good adhesion, high aesthetic durability, low reflectance, and low luminance. The watch component 1 is therefore simple to manufacture, without excessive thickness, and thus benefits from a durable and advantageous aesthetic effect.

[0042] According to a second alternative embodiment of the invention visible at the figure 3insofar as the body 10 is at least based on a nickel- or zinc-based material (intermediate layer 15) to be decorated, in order to obtain a decorative coating 20 adhering to a black appearance with a reflectance of less than 5% on the human visible spectrum, said at least one titanium-aluminum carbide-based layer 20A, 20C has, individually or cumulatively, a thickness (vertical axis Z) of at least 40 nm, i.e., the thickness of a single layer 20A or 20C or the cumulative thickness of several layers 20A, 20C, while said at least one oxide-based layer 20B, 20D has, individually or cumulatively, a thickness (vertical axis Z) of at least 40 nm, i.e., the thickness of a single layer 20B or 20C or the cumulative thickness of several layers 20B, 20D.

[0043] Advantageously, according to the second embodiment of the invention, a material (intermediate layer 15) already present on the watch component 1 makes it possible to limit the thickness (vertical axis Z) to be deposited for layers 20A, 20B, 20C, 20D of the decorative coating 20. This material of the intermediate layer 15 can, for example, be nickel-based or zinc-based.

[0044] Thus, with a total thickness (vertical axis Z) of 80 nm for the decorative coating 20, i.e., comprising the stack of titanium and aluminum carbide-based and oxide-based layers 20A, 20B, 20C, and 20D, it becomes possible to obtain a very deep black shade with good adhesion, high aesthetic durability, low reflectance, and low luminance. The watch component 1 is therefore simple to manufacture, without significant added thickness, and thus benefits from a highly advantageous aesthetic effect.

[0045] The material of the intermediate layer 15 to be decorated can, for example, be based on an alloy of the Ni-Au, Ni-Zn or Zn-Ni type. The intermediate layer 15 can be a thin deposit, i.e. approximately between 1 nm and 1000 nm, or form all or part of the watch component 1, 1A, 1B.

[0046] The nickel-based decoration material may comprise pure nickel (Ni), 50 to 70% nickel by total weight of the alloy and the remaining 30 to 50% gold (Ni-Au), or 50 to 97% nickel by total weight of the alloy and the remaining 3 to 50% zinc (Ni-Zn). The zinc-based decoration material may comprise pure zinc (Zn) or 60 to 80% zinc by total weight of the alloy and the remaining 20 to 40% nickel.

[0047] Nickel (Ni), in its pure form (containing at least 95% nickel), has a silvery-white color that is color-neutral. Similarly, zinc (Zn), in its pure form (containing at least 95% zinc), has a light gray color that is also color-neutral.

[0048] For a binary Ni-Au alloy, the intermediate layer 15 can be deposited by electroplating using an electrolyte bath composed of 10-25% ammonium nickel sulfate and an electrometric pH (at 20 °C) of 5.7 to 5.9. The deposition temperature can be in the range of 65-75 °C. Preferably, it is regulated at 65 °C and the current density of 0.5 to 1.0 A.dm-2.

[0049] The resulting binary alloy comprises, for example, 50 to 70% nickel by total weight and the remaining 30 to 50% gold. Preferably, the alloy comprises 60 to 65% nickel and 35 to 40% gold. In one specific example, the alloy comprises approximately 62.5% nickel and 37.5% gold, and has a dark gray color.

[0050] According to a second example, the intermediate layer 15 may comprise from 50 to 97% nickel by total weight of the alloy and the remaining 3 to 50% zinc. Preferably, the intermediate layer 15 comprises between 80% and 90% nickel by total weight of the alloy and the remaining 10% to 20% zinc. Alloys of this type and methods for depositing them by electroplating are described, for example, in US patent 4,416,737.

[0051] As an example, the binary Zn-Ni alloy can be deposited by electroplating using an electrolyte bath whose base consists mainly of nickel sulfate hexahydrate 10-25%, nickel chloride hexahydrate 2.5-10%, zinc sulfate (mono-, hexa- and heptahydrate) 2.5-10%, sodium thiocyanate ≤ 2.5% and an electrometric pH (at 20 °C) of 5.8 to 6. The deposition temperature can be set within a window between 22 °C and 17 °C. Preferably, it is regulated along the deposition process at 18 °C and the current density from 0.12 to 0.15 A.dm⁻².

[0052] The resulting binary alloy comprises, for example, 60 to 80% zinc by total weight and the remaining 20 to 40% nickel. In one specific example, the alloy comprises approximately 80% zinc and 20% nickel and has a dark gray color.

[0053] Regardless of the embodiment, the decorative coating 20 may comprise several layers 20A, 20C based on titanium and aluminum carbide and / or several layers 20B, 20D based on oxide. The decorative coating 20 according to the invention may thus comprise a stack of at least two layers 20A, 20C based on titanium and aluminum carbide and one layer 20B, 20D based on oxide, a stack of one layer 20A, 20C based on titanium and aluminum carbide and at least two layers 20B, 20D based on oxide, or a stack of at least two layers 20A, 20C based on titanium and aluminum carbide and at least two layers 20B, 20D based on oxide (as seen in the first embodiment of the figure 4 ) without going outside the scope of the invention.

[0054] According to a second embodiment of the invention, a first layer 20A based on titanium and aluminum carbide is deposited on the body 10 with a thickness of 20 nm, a second layer 20B based on an oxide is deposited with a thickness of 15 nm on layer 20A, a third layer 20C based on titanium and aluminum carbide is deposited with a thickness of 20 nm on layer 20BA, and a second layer 20D based on an oxide is deposited with a thickness of 35 nm on layer 20C. Preferably, the uppermost layer of the decorative coating 20, that is, the layer 20B, 20D furthest from the body 10 of the decorative coating 20, is oxide-based. However, the order of the layers could be reversed without departing from the scope of the invention.

[0055] The total thickness (vertical axis Z) of the decorative coating 20 is preferably no more than 1000 nm, which ensures compatibility with watchmaking applications. This means that the decorative coating 20 does not excessively increase the thickness (vertical axis Z) of the watch component 1. Advantageously, the decorative coating 20 according to the invention does not require a thickness of 1000 nm or more to achieve the desired black appearance, regardless of the material of the body 10 of the watch component 1. This is true even in the second embodiment, where a greater thickness of at least one titanium and aluminum carbide-based layer 20A, 20C is necessary. During the development of the invention, total thicknesses (vertical axis Z) of the decorative coating 20 between 200 nm and 400 nm were also found to be satisfactory.

[0056] Said at least one 20B, 20D oxide-based layer may be formed from aluminum oxide, zinc oxide, titanium oxide, silicon oxide, zirconium oxide, tantalum oxide, and / or hafnium oxide. Such at least one 20B, 20D oxide-based layer advantageously has a different refractive index from said at least one 20A, 20C titanium-aluminum carbide-based layer in order to achieve the interference phenomenon capable of preventing the reflection of all or most of the wavelengths of the human-visible spectrum from an incident light flux. Typically, the difference in refractive index is at least equal to 0.2 and preferably at least equal to 0.6, i.e. for example equal to 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0057] The invention also relates to a method for manufacturing a watch component 1 as described above. The method comprises the following steps: a - form a body 10 (with or without the intermediate layer 15); b - deposit, on at least a part of the body 10, a decorative coating 20.

[0058] According to the invention, step b of the deposition of the decorative coating 20 comprises the following phases: b1 - deposit at least one layer 20A, 20C based on titanium and aluminum carbide; b2 - deposit at least one layer 20B, 20D based on oxide.

[0059] Due to the nature of the deposited materials, the advantageous process according to the invention can be implemented by atomic layer deposition, generally abbreviated as "ALD" (Atomic Layer Deposition), or by physical vapor deposition (PVD), which uses machines commonly found in watchmaking companies; that is, no specific machine is required. Consequently, the process is simpler to implement, does not encounter any particular adhesion difficulties with the decorative coating, and allows for a decorative coating with a long-lasting, deep black aesthetic effect.

[0060] Each layer 20A, 20B, 20C, 20D can preferably be deposited with a thickness between 1 nm and 200 nm. At least one of the phases b1 and b2 of step b is preferably carried out by an ALD method. Preferably, phases b1 and b2 of step b are carried out by an ALD method. Of course, other vacuum deposition methods are possible for obtaining step b, such as, for example, physical vapor deposition or chemical vapor deposition, without departing from the scope of the invention.

[0061] Indeed, the ALD method is an atomic layer deposition process that allows for very thin and uniform layer deposition, typically at ±1 nm. The ALD method involves successively exposing a surface to different chemical precursors to deposit thin layers of metallic compounds, oxides, or other materials. It is based on self-saturated surface reactions that occur sequentially, allowing for controlled growth. Generally, an ALD cycle includes at least two precursor injections, separated by a purging step to remove the precursor and excess reaction products before the introduction of the next precursor. Advantageously, ALD technology allows for the deposition of layers on surfaces with a very high aspect ratio, as the reaction takes place on a monolayer of precursor gases adsorbed directly onto the surface.The ALD method being very well known, it will not be explained further below. When step b is obtained from an ALD method, step b is preferably carried out at least 150 °C and even more preferably between 300 °C and 500 °C.

[0062] An example of ALD method parameters is explained below to better understand the process according to the invention. Material Pulse 1 name / pulse time / purge time Pulse 2 name / pulse time / purge time TiAlC TiCL / 0.1 to 1 s / 5 s to 2 min TMA / 0.1 to 1 s / 5 s to 2 min Al 2 O 3 TMA / 0.1 to 1 s / 5 s to 2 min H2O / 0.1 to 1 s / 5 s to 2 min

[0063] Other parameters may include: Temperature: 200 - 400°C Nitrogen flow rate: 100 - 500 sccm in the reactor; TiCl4 and TMA pulse flow rate: 50 - 300 sccm in the lines; H2O pulse flow rate: 100 - 500 sccm in the lines.

[0064] Growth rates of approximately 0.065 nm per cycle for TiAIC and 0.08 nm per cycle for Al₂O₃ were observed. These growth rates are used to calculate the number of cycles required to achieve the target thicknesses. Naturally, these growth rates can be adjusted, i.e., increased or decreased, particularly by modifying the pulse and / or purge times and / or temperature variations. Finally, the order of precursors for depositing a material can be reversed, or other known precursors of the materials can be used without any impact on the process.In addition, at the interface between the substrate 10 (i.e. possibly the intermediate layer 15 made of nickel- or zinc-based material) and said at least one layer 20A, 20C made of titanium- and aluminum-based carbide, there may be at least one layer of said at least one layer 20B, 20D made of oxide to improve adhesion with the substrate 10 (i.e. possibly the intermediate layer 15 made of nickel- or zinc-based material).

[0065] The invention is not limited to the embodiments and variations shown, and other embodiments and variations will be obvious to those skilled in the art. Thus, the above embodiments are examples. Although the description refers to one or more embodiments, this does not necessarily mean that each reference relates to the same embodiment, or that the features apply only to a single embodiment. Simple features of different embodiments can also be combined and / or interchanged to provide other embodiments.

[0066] Furthermore, the invention cannot be limited to a timepiece 2. Thus, the invention could also be applied in other fields such as, for example, jewelry, fine jewelry, leather goods, tableware, optical instruments, firearms or writing instruments. LIST OF REFERENCES

[0067] 1 - Watch component 1A - Dial 1B - Gear wheel 2 - Watch part 3 - Watch movement 4 - Casing 10 - Case 15 - Intermediate layer 20 - Decorative coating 20A - Titanium and aluminum carbide-based layer 20B - Oxide-based layer 20C - Titanium and aluminum carbide-based layer 20D - Oxide-based layer

Claims

1. Watch component (1, 1A, 1B) formed of a body (10) made of a material to be decorated which is at least partially covered with a decorative coating (20), characterized in that the decorative coating (20) comprises at least one layer (20A, 20C) based on titanium and aluminum carbide having a thickness of at least 200 nm stacked with at least one layer (20B, 20D) based on oxide having a thickness of at least 30 nm allowing to obtain a decorative coating (20) adhering to the black appearance with a reflectance of less than 5% on the human visible spectrum.

2. Watch component (1, 1A, 1B) consisting of at least one body (10) made of a material (15) to be decorated, based on nickel or zinc, and which is at least partially covered with a decorative coating (20), characterized in thatthe decorative coating (20) comprises at least one layer (20A, 20C) based on titanium and aluminum carbide having a thickness of at least 40 nm stacked with at least one layer (20B, 20D) based on oxide having a thickness of at least 40 nm allowing to obtain a decorative coating (20) with a black appearance with a reflectance of less than 5% on the human visible spectrum.

3. Watch component (1, 1A, 1B) according to the preceding claim, wherein the nickel-based material (15) to be decorated comprises 50 to 70% nickel by total weight of the alloy and the remaining 30 to 50% gold.

4. Watch component (1, 1A, 1B) according to claim 2, wherein the nickel-based material (15) to be decorated comprises from 50 to 97% nickel by total weight of the alloy and from 3 to 50% remaining zinc.

5. Watch component (1, 1A, 1B) according to claim 2, wherein the zinc-based decoration material comprises 60 to 80% zinc by total weight of the alloy and the remaining 20 to 40% nickel.

6. Watch component (1, 1A, 1B) according to any one of the preceding claims, wherein the decorative coating (20) comprises several layers (20A, 20C) based on titanium and aluminum carbide and several layers (20B, 20D) based on oxide.

7. Watch component (1, 1A, 1B) according to any one of the preceding claims, wherein the thickness of the decorative coating (20) is at most equal to 1000 nm.

8. Watch component (1, 1A, 1B) according to any one of the preceding claims, wherein said at least one layer (20A, 20C) of oxide is formed based on aluminium oxide, zinc oxide, titanium oxide, silicon oxide, zirconium oxide, tantalum oxide and / or hafnium oxide.

9. Timepiece (2) comprising a timepiece movement (3), characterized in that it includes a watch component (1, 1A, 1B) according to one of the preceding claims.

10. Timepiece (2) according to the preceding claim, wherein the timepiece component (1, 1A, 1B) forms all or part of a part of the casing (4) of the timepiece.

11. Timepiece (2) according to claim 7, wherein the timepiece component (1, 1A, 1B) forms all or part of a part of the timepiece movement (3) of the timepiece (2).

12. Method for manufacturing a watch component (1, 1A, 1B) according to any one of claims 1 to 6, characterized in that the process comprises the following steps: a - forming a body (10); b - depositing, on at least a part of the body, a decorative coating (20); characterized in thatThe coating (20) deposition step for decoration comprises the following phases: b1 - deposit at least one layer (20A, 20C) based on titanium and aluminum carbide; b2 - deposit at least one layer (20B, 20D) based on oxide.

13. A method according to the preceding claim, wherein step b is carried out by an ALD method.

14. A method according to the preceding claim, wherein step b is carried out at least 150 °C.

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