Exterior part made of ceramic material including a protective layer and method for manufacturing such an exterior part - Patent Application 20070122997

Abstract

To provide an exterior component formed of a ceramic material including a protective coating.SOLUTION: An exterior component 10 includes a substrate 11 formed of a ceramic material, wherein a transparent inorganic protective coating 12 spreads over a surface of the substrate. The protective coating is constituted to have a refractive index substantially equal to that of the substrate in a visible range of an optical spectrum so that the exterior component 10 has a color substantially equal to an intrinsic color of the substrate, wherein the protective coating extends over a thickness selected between 300 nm and 5 μm.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to ornamentation in the fields of watchmaking, jewellery or clothing, and more particularly to an exterior part made of ceramic material comprising a protective coating and to a method for manufacturing such an exterior part.

[0002] In this specification, the term "exterior part" is commonly used in the above-mentioned fields to refer to parts that are visible to the user, especially parts that have a decorative function.

[0003] Apparel accessories also include articles or accessories for clothing such as belts, shoes, clothing, and further include writing instruments, eyeglasses, leather goods, telephones or any decorative item. [Background technology]

[0004] In the field of watchmaking, many solutions have been developed to protect ceramic exterior parts such as dials, flanges, bezels, middles, crowns, push-pieces, links, etc. from chemical and / or mechanical attack that could alter their appearance or color.

[0005] By way of example, the exterior component may include a thin protective layer deposited by a vacuum deposition method such as PVD (physical vapor deposition), CVD (chemical vapor deposition) or ALD (atomic layer deposition) deposition.

[0006] However, the prior art solutions are not entirely satisfactory: in fact, prior art protective layers are not completely transparent and have a small thickness, for example less than 5 μm, i.e. they do not absorb part of the incident light radiation in the visible region of the light spectrum, do not produce interference colors, and do not have adequate resistance to chemical and mechanical attack.

[0007] It should be noted that thin layers deposited by ALD deposition have advantages over thin layers deposited by PVD and CVD deposition: in fact, these ALD thin layers are very effective in protecting the substrate from chemical attack and, due to their small thickness, are invisible to the naked eye and do not affect the appearance of the substrate they cover.

[0008] However, these layers are so thin that they are highly sensitive to mechanical stresses such as friction and shocks, and therefore cannot be used to cover exterior parts that may come into contact with external elements, such as the bezel or watch band.

[0009] Layers with thicknesses greater than those of ALD thin layers, typically in the micron range, offer greater resistance to mechanical stress. However, these layers are visible on the substrate and therefore do not meet the requirements, especially when the appearance of the substrate needs to be maintained for decorative reasons. Summary of the Invention [Problem to be solved by the invention]

[0010] There is therefore a need for a protective solution that is effective against chemical and mechanical attack and is suitable for maintaining the appearance of the substrate thus protected. [Means for solving the problem]

[0011] The present invention overcomes the above-mentioned drawbacks and to this end relates to an exterior part, preferably for a watch, comprising a substrate made of a ceramic material, on the surface of which a transparent inorganic protective coating extends, the coating being configured so that, at least at its interface with the substrate, it has a refractive index substantially equal to that of the substrate for wavelengths in the visible region of the light spectrum, so that interference phenomena do not occur or are very little, i.e. are substantially invisible to the naked eye, and the exterior part has a color substantially identical to the intrinsic color of the substrate.

[0012] The coating also has a relatively small thickness, which saves deposition time and manufacturing costs for exterior components, while being thick enough to provide excellent mechanical resistance to abrasion and excellent protection against chemical attack. Specifically, the coating has a thickness of 300 nm to 5 μm. The coating can advantageously have a high hardness, typically a Vickers hardness of the order of 25 GPa.

[0013] Thus, the present invention allows for the protection of exterior components while allowing the inherent color of the substrate to be preserved.

[0014] In particular embodiments, the invention may further include one or more of the following features, taken alone or in any technically possible combination:

[0015] In certain embodiments, the protective coating is configured such that the protective coating imparts a color to the exterior component that is characterized by a difference from the native color of the substrate of Delta E≦10 in L*a*b* color space.

[0016] In certain embodiments, the protective coating is configured such that the protective coating imparts a color to the exterior component that is characterized by a difference from the native color of the substrate of Delta E≦5 in L*a*b* color space.

[0017] In certain embodiments, the protective coating has a thickness of from 300 nm to 1 μm.

[0018] In certain embodiments, the protective coating is formed from at least two compounds having refractive indices greater than and less than that of the substrate for wavelengths in the visible region of the light spectrum. By controlling the proportion of each compound in the protective coating's composition, the refractive index of the protective coating can be precisely controlled to be substantially equal to that of the substrate, thereby eliminating interference phenomena.

[0019] In certain embodiments, the protective coating comprises Tix Al y O z The laminated structure includes at least one layer made of

[0020] In certain embodiments, the protective coating is Si x O y N z The laminated structure includes at least one layer made of

[0021] In particular embodiments, the substrate may be made of an oxide, nitride, carbide, carbonitride or boride, in particular alumina Al2O3, zirconia ZrO2 or an alumina-zirconia composite.

[0022] According to another aspect, the present invention also relates to a method for manufacturing an exterior component, such as those described above, comprising the steps of preparing a surface of a substrate and depositing a transparent inorganic protective coating on said surface by vacuum deposition in a reactive or non-reactive atmosphere.

[0023] The depositing step is performed from at least one source of at least one material selected so that the protective coating has a refractive index substantially equal to the refractive index of the substrate in the visible region of the light spectrum, said step also being performed so that the protective coating has a thickness of 300 nm to 5 μm so that the protective coating is resistant to mechanical and chemical attack.

[0024] In a particular implementation, the step of depositing the protective coating is performed by cathodic sputtering.

[0025] In a specific implementation, the protective coating is deposited from at least two sources of different materials selected such that during the deposition step, each of the materials forms a compound having a refractive index greater than and less than that of the substrate in the visible region of the light spectrum, respectively, and the sputtering power of each source is controlled such that the proportion of each compound in the protective coating is such that the coating has substantially the same refractive index as that of the substrate.

[0026] In a particular implementation, the protective coating is deposited from at least one source of a mixture of at least two materials, the materials being selected such that during the deposition step, the materials each form a compound having a refractive index greater than and less than that of the substrate in the visible region of the light spectrum, respectively, and the source is prepared to contain predetermined proportions of the materials such that the protective coating has a refractive index substantially the same as that of the substrate at the end of the deposition step.

[0027] In a particular implementation, the materials selected are Al and Ti, and the deposition step is carried out such that at the end of the deposition step, a protective coating is applied to the Ti x Al y O z This is done using O2 as the reactive gas to form compounds of the type containing a mixture of TiO2 and Al2O3.

[0028] In certain implementations, the protective coating is applied during the deposition step. , Existence A single material is formed by reacting with some reactive gases present. but The protective coating is deposited from at least one source of a selected single material to form several compounds, each having a refractive index greater than and less than that of the substrate in the visible region of the light spectrum, and the reactive gases are present in a predetermined ratio such that at the end of the deposition step, the protective coating has a refractive index substantially the same as that of the substrate.

[0029] In a particular implementation, the deposition step may be performed such that at the end of the deposition step, a protective coating is formed on the surface of the silicon dioxide film. x O y N z This is done using O2 and N2 as reactive gases from a source made of Si, containing a mixture of SiO2 and Si3N4 to form compounds of the type. [Brief explanation of the drawings]

[0030] Other characteristics and advantages of the invention will become apparent from the following detailed description, given by way of non-limiting example with reference to FIG. [Figure 1] 1 shows a schematic cross-sectional view of an exterior part according to a preferred embodiment of the present invention;

[0031] Please note that the figures are not necessarily drawn to scale for clarity. DETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention relates to an external part 10, as shown diagrammatically in Figure 1. The external part 10 according to the invention is suitable for the fields of watchmaking, jewellery, clothing, etc. Preferably, the external part 10 is intended to form the dial, middle, bezel, bracelet or any other watch part visible to the user.

[0033] The exterior component 10 comprises a dielectric substrate 11 made of a ceramic material, such as alumina Al2O3, zirconia ZrO2, or an alumina-zirconia composite, with or without a pigment to color said substrate. The exterior component 10 further comprises a transparent inorganic protective coating 12 extending over the surface of the substrate 11 that is intended to be visible to the user.

[0034] It should be noted that the term "transparent" in this specification refers to the ability of a material not to absorb light in a manner visible to the human eye.

[0035] The protective coating 12 may be formed of a single thin layer or multiple thin layers.

[0036] Advantageously, the protective coating 12 can protect the substrate 11 from chemical attack caused by, among other things, humidity, sulfur gases, oxygen, and acidic environments. Furthermore, the protective coating 12 is dimensioned to withstand mechanical stresses caused, among other things, by friction or impact.

[0037] For this purpose, the protective coating 12 extends over a thickness chosen for example between 300 nm and 5 μm, more particularly between 300 nm and 1 μm. Preferably, the thickness of the protective coating 12 is equal to 1 μm.

[0038] Protective coating 12 is configured to have a refractive index, at least at its interface with substrate 11, substantially equal to the refractive index of substrate 11 in the visible region of the light spectrum. As used herein, the refractive index of protective coating 12 is substantially equal to the refractive index of substrate 11 within plus or minus 5 percent of the value of substrate 11.

[0039] Advantageously, these characteristics allow protective coating 12 to produce little or no optical interference, thus allowing exterior component 10 protected by layer 12 to have the native color of substrate 11. It should be noted that any interference that occurs is so slight as to be imperceptible to the user and therefore negligible.

[0040] The concept of "intrinsic color" as used herein refers to the color of uncoated substrate 11, as perceived by a user when illuminated with white light, due to the materials that make up substrate 11. Protective coating 12 is therefore invisible to the naked eye in the sense that exterior component 10 has substantially the same color with or without protective coating 12 deposited on substrate 11.

[0041] More specifically, protective coating 12 is configured such that protective coating 12 imparts a color to exterior component 10 that is characterized by a difference from the native color of substrate 11 in L*a*b* color space of Delta E≦10, and more particularly Delta E≦5.

[0042] In summary, thanks to the features of the present invention, exterior component 10 includes chemical protection for substrate 11 while maintaining the aesthetic appearance and mechanical strength of the substrate.

[0043] Preferably, the protective coating is formed from at least two compounds having a higher and lower refractive index than substrate 11, respectively, for wavelengths in the visible region of the light spectrum.

[0044] For example, protective coating 12 can include a mixture of TiO2, which has a high refractive index, and Al2O3, which has a low refractive index. It should be noted that this example of protective coating 12 is not compatible with substrate 11 made of a material whose refractive index is lower than that of a coating of Al2O3 alone or higher than that of a coating of TiO2 alone.

[0045] Alternatively, the protective coating 12 may comprise a mixture of Si3Ni4, which has a high refractive index, and SiO2, which has a low refractive index.

[0046] More generally, in summary, the protective coating 12 is a Ti x Al y O z or Si x O y N z The substrate may include at least one thin layer made of

[0047] The present invention also relates to a method for manufacturing an exterior part 10, such as the aforementioned exterior part 10. The method comprises the steps of preparing a surface of a substrate 11 intended to be visible to a user, and depositing a protective coating 12 on said surface by a vacuum deposition method.

[0048] The preparation step may include polishing, sandblasting, brushing, satin finishing, or performing any other surface treatment operation on the substrate 11 .

[0049] The deposition step is carried out using one or more sources of material, the composition of which is selected to form a protective coating 12 having a refractive index substantially equal to that of the substrate 11 in the visible region of the light spectrum.

[0050] This deposition step is also carried out so as to deposit the protective coating 12 with a thickness such that it is resistant to mechanical attack, in particular abrasion, and chemical attack, as described above.

[0051] Furthermore, the method can include a preliminary step of preparing at least one material source to be used during the deposition step. The step of preparing the source makes it possible, for example, to adapt the appropriate type of source depending on the vacuum deposition method to be used during the deposition step, and to adapt the proportions of materials in the source if the source contains multiple materials, in order to obtain the desired protective coating 12. The type of material source differs depending on the vacuum deposition method used, in that the source is a target in solid form when the deposition method used is physical vapor deposition (PVD), and the source is a gas-phase precursor when the deposition method used is chemical vapor deposition (CVD) or atomic layer deposition (ALD).

[0052] In one variant of the method, protective coating 12 is deposited from at least two sources of different materials, e.g., different metallic materials. The materials are selected so that, during the deposition step, each of the materials forms a compound, e.g., an oxide, nitride, or carbide, having a refractive index greater than or less than that of substrate 11, respectively, in the visible region of the light spectrum. During the deposition step, by controlling the sputtering power of each source, the proportion of each compound deposited to form protective coating 12 is controlled so that protective coating 12 has a desired refractive index, which, as described above, is substantially the same as that of substrate 11.

[0053] For example, one of the materials can be Al and the other can be Ti. A preliminary preparation step is performed to obtain two sources, one made of Ti and the other made of Al, and the deposition step is performed using O2 as the reactive gas. In this example, at the end of the deposition step, the protective coating 12 is formed from a mixture of TiO2 and Al2O3. These two metal oxides have refractive indices higher and lower than that of the substrate 11, respectively, so that the refractive index of the coating 12 can be controlled by controlling their proportions in the protective coating 12.

[0054] In another variant implementation of the method, the protective coating 12 is deposited from at least one source of a mixture of at least two materials, the materials also being selected so that during the deposition step, each of the materials forms a compound, such as an oxide, nitride, boride or carbide, with a refractive index in the visible region of the light spectrum that is greater than or less than that of the substrate 11. During a preliminary step, the sources are prepared containing predetermined proportions of the materials in order to control the composition of the deposited protective coating 12 so that the protective coating 12 has the desired refractive index at the end of the deposition step.

[0055] For example, a preparatory step can be performed to obtain a source of a mixture of Ti and Al, and the deposition step can be performed using O as the reactive gas. In this example, at the end of the deposition step, the protective coating 12 consists of a mixture of TiO and AlO. As in the previous variant, these two metal oxides have refractive indices higher and lower than those of the substrate 11, respectively, so by controlling their proportions in the protective coating 12, the refractive index of the coating 12 can be controlled to be substantially equal to that of the substrate 11. Because the sources are prepared upstream with predetermined proportions of each material, this variant is more suitable for industrial implementation in a simple, fast, and stable manner.

[0056] In yet another variation of the method, protective coating 12 can be deposited from at least one source of a single material selected such that the single material forms various compounds during the deposition step, depending on the reactive gases used, such as O or N. In the visible region of the light spectrum, the compounds have refractive indices lower and higher than those of substrate 11, respectively. Thus, by controlling the amount of each gas present during the deposition step, the stoichiometric composition of the compounds comprising protective coating 12 can be controlled to obtain the desired refractive index of protective coating 12.

[0057] For example, a preparatory step can be performed to obtain a Si source, and the deposition step can be performed using N2 and O2 as reactive gases. In this example, at the end of the deposition step, the protective coating 12 consists of a mixture of SiO2 and Si3N4. Thus, by mixing metal oxides with nitrides of the same metals in controlled proportions, the refractive index of the coating 12 can be controlled to be substantially the same as the refractive index of the substrate 11.

[0058] These different variants advantageously allow, by adjusting the proportions between the different compounds that make up the protective coating 12, to obtain, with high flexibility and in a relatively simple manner, a protective coating 12 having an effective refractive index that corresponds as accurately as possible to the refractive index of the substrate 11.

[0059] The step of depositing the protective coating 12 is preferably carried out in a reactive or non-reactive atmosphere by a physical vapor deposition (PVD) method, for example by arc evaporation, laser ablation, ion beam sputtering or electron beam or Joule effect evaporation, preferably by cathodic sputtering. Alternatively, the deposition step can be carried out by any chemical vapor deposition (CVD) or atomic layer deposition (ALD) method.

[0060] More generally, it should be noted that the implementations and embodiments described above are described as non-limiting examples, and therefore other variations are possible.

[0061] In particular, materials other than those described in the variant implementations of the above-described method can be used, and in particular, although the use of metallic material sources is described, non-metallic material sources can also be used.

Claims

1. An exterior part (10), The exterior part (10) comprises a substrate (11) made of a ceramic material, a transparent inorganic protective coating (12) extending over the surface of said substrate (11); the substrate (11) has a refractive index greater than or equal to that of Al 2 O 3 and less than or equal to that of TiO 2 for all wavelengths in the visible region of the light spectrum; said protective coating (12) being at least one layer made of a compound of the Ti x Al y O z type, having a refractive index within plus or minus 5 percent of the value of the refractive index of said substrate (11) for all wavelengths in the visible region of the light spectrum; An exterior part (10), characterized in that the protective coating (12) extends over a thickness selected between 300 nm and 5 μm.

2. An exterior part (10), The exterior part (10) comprises a substrate (11) made of a ceramic material, a transparent inorganic protective coating (12) extending over the surface of said substrate (11); the substrate (11) has a refractive index greater than or equal to that of SiO 2 and less than or equal to that of Si 3 N 4 for all wavelengths in the visible region of the optical spectrum; said protective coating (12) being at least one layer made of a compound of the Si x O y N z type, having a refractive index within plus or minus 5 percent of the value of the refractive index of said substrate (11) for all wavelengths in the visible region of the light spectrum; An exterior part (10), characterized in that the protective coating (12) extends over a thickness selected between 300 nm and 5 μm.

3. 3. The exterior part (10) of claim 1 or 2, wherein the protective coating (12) is configured to impart to the exterior part (10) a color that differs from the intrinsic color of the substrate (11) by a delta E≦10 in the L*a*b* color space.

4. 4. The exterior component (10) of claim 3, wherein the protective coating (12) is configured to impart to the exterior component (10) a color that differs from the intrinsic color of the substrate (11) in L*a*b* color space by a delta E≦5.

5. 3. The exterior part (10) according to claim 1 or 2, wherein the thickness of the protective coating (12) is between 300 nm and 1 μm.

6. The substrate (11) is made of alumina Al 2 O 3 , zirconia ZrO 2 An exterior part (10) according to claim 1 or 2, made of an alumina-zirconia composite.

7. A manufacturing method for manufacturing an exterior part (10), comprising: - preparing the surface of the substrate (11); depositing a transparent inorganic protective coating (12) on said surface by vacuum deposition; Including, the substrate (11) has a refractive index greater than or equal to that of Al 2 O 3 and less than or equal to that of TiO 2 for all wavelengths in the visible region of the light spectrum; The depositing step is carried out from at least one source of Ti and Al so that the protective coating (12) is at least one layer made of a compound of the Ti x Al y O z type, which has a refractive index within plus or minus 5 percent of the value of the refractive index of the substrate (11) for all wavelengths in the visible region of the light spectrum; The method is also characterized in that the depositing step is performed so that the protective coating (12) has a thickness of 300 nm to 5 μm.

8. The method of claim 7 , wherein the depositing step is performed by cathodic sputtering.

9. The protective coating (12) is deposited from a source of Ti and a source of Al; During the depositing step, Ti and Al form TiO 2 and Al 2 O 3 , respectively; 8. The method of claim 7, wherein the sputtering power of each source is controlled so that TiO2 and Al2O3 in the protective coating (12) are present in a predetermined ratio to form the TixAlyOz type compound.

10. the protective coating (12) is deposited from at least one source of a mixture of Ti and Al; During the depositing step, Ti and Al form TiO 2 and Al 2 O 3 , respectively; 8. The method of claim 7, wherein said source is prepared to contain Ti and Al in predetermined proportions to form said TixAlyOz type compound at the end of said depositing step.

11. The depositing step is carried out such that at the end of the depositing step, the protective coating (12) is x Al y O z to form compounds of the type TiO 2 and Al 2 O 3 The reactive gas is O, so as to contain a mixture of 2 The method according to claim 7, wherein the method is carried out using

12. A manufacturing method for manufacturing an exterior part (10), comprising: - preparing the surface of the substrate (11); depositing a transparent inorganic protective coating (12) on said surface by vacuum deposition; Including, the substrate (11) has a refractive index greater than or equal to that of SiO 2 and less than or equal to that of Si 3 N 4 for all wavelengths in the visible region of the optical spectrum; The depositing step is carried out from at least one source of Si so that the protective coating (12) is at least one layer made of a compound of the Si x O y N z type having a refractive index within plus or minus 5 percent of the value of the refractive index of the substrate (11) for all wavelengths in the visible region of the light spectrum; 3. A method of manufacturing a semiconductor device comprising: depositing a protective coating having a thickness of from 300 nm to 5 μm; 13. The method of claim 12, wherein O 2 and N 2 as reactive gases are present in a predetermined ratio to form the Si x O y N z type compound at the end of the depositing step.

14. The depositing step is carried out such that at the end of the depositing step, the protective coating (12) is formed on the Si x O y N z to form compounds of the type SiO 2 and Si 3 N 4 The reactive gas is O, so as to contain a mixture of 2 and N 2 The method according to claim 12, wherein the method is carried out using

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