EP0221492B1 - Article coated with a wear-resistant film of a precious metal - Google Patents

Article coated with a wear-resistant film of a precious metal Download PDF

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Publication number
EP0221492B1
EP0221492B1 EP86114909A EP86114909A EP0221492B1 EP 0221492 B1 EP0221492 B1 EP 0221492B1 EP 86114909 A EP86114909 A EP 86114909A EP 86114909 A EP86114909 A EP 86114909A EP 0221492 B1 EP0221492 B1 EP 0221492B1
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EP
European Patent Office
Prior art keywords
layer
precious metal
inclusions
gold
alloy
Prior art date
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EP86114909A
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German (de)
French (fr)
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EP0221492A3 (en
EP0221492A2 (en
Inventor
Eric Saurer
Yves Ruedin
Jean-Paul Randin
Michel Sallin
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Asulab AG
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Asulab AG
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
    • C23C28/023—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only
    • A—HUMAN NECESSITIES
    • A44—HABERDASHERY; JEWELLERY
    • A44C—PERSONAL ADORNMENTS, e.g. JEWELLERY; COINS
    • A44C27/00—Making jewellery or other personal adornments
    • A44C27/001—Materials for manufacturing jewellery
    • A44C27/005—Coating layers for jewellery
    • A44C27/006—Metallic coatings
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
    • C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
    • C23C28/021—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material including at least one metal alloy layer
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B37/00—Cases
    • G04B37/22—Materials or processes of manufacturing pocket watch or wrist watch cases
    • G04B37/223—Materials or processes of manufacturing pocket watch or wrist watch cases metallic cases coated with a nonmetallic layer
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/922—Static electricity metal bleed-off metallic stock
    • Y10S428/9335—Product by special process
    • Y10S428/934—Electrical process
    • Y10S428/935—Electroplating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S428/00—Stock material or miscellaneous articles
    • Y10S428/922—Static electricity metal bleed-off metallic stock
    • Y10S428/9335—Product by special process
    • Y10S428/938—Vapor deposition or gas diffusion
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12486—Laterally noncoextensive components [e.g., embedded, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12868—Group IB metal-base component alternative to platinum group metal-base component [e.g., precious metal, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12875—Platinum group metal-base component
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12889—Au-base component
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12896—Ag-base component

Definitions

  • the invention relates to an object, in particular a watch case, surmounted by a wear-resistant coating and consisting mainly of a precious metal from the group of gold, silver, rhodium, palladium, platinum, iridium, osmium and ruthenium or an alloy of said precious metal, said coating consisting of a first layer of said precious metal or its alloy, said first layer comprising discrete inclusions of a compound metallic consisting of an oxide, a nitride, a carbide, a boride, a phosphide, a silicide or a fluoride, said inclusions being distributed in a substantially homogeneous manner throughout the thickness of the first layer, said first layer being applied by deposition in vapor phase (CVD or PVD), its thickness being equal to or greater than 0.4 ⁇ m.
  • a wear-resistant coating consisting mainly of a precious metal from the group of gold, silver, rhodium, palladium, platinum, iridium, osm
  • the surface gold layer must be thin (equal to or less than 1 ⁇ m) for the coating to produce the expected effect, namely to make scratches caused by foreign bodies not very visible.
  • the coating described does not allow to reach a real plating containing enough precious metal so that said object can carry the maker's mark.
  • a source for example TiN
  • Another embodiment of the cited invention starts from two separate sources constituted respectively by the noble metal and the metallic compound, these sources being subjected to an evaporation process at increasing, respectively decreasing, speeds.
  • the coatings which are the subject of the two documents cited above, although being different in their composition, have a common characteristic: they both have a layer of precious metal, for example gold, deposited on underlying layers much harder than that of precious metal, for example titanium nitride. If the surface layer is scratched, it will be only slightly deep and the scratch will be only slightly visible, and this all the more if the underlying layer is of a color close to that of the precious metal deposited on the surface.
  • precious metal for example gold
  • Document JP-A-59 185774 describes a plating of a gold alloy deposited in the vapor phase and further comprising hardening agents in the form of nitrides. Thanks to this contribution, the hardness and the corrosion resistance of the plating are improved.
  • Document JP-A-60 114567 proposes the use of a precious metal codeposited with a transparent oxide to form the coating of an object which then has better resistance to wear and scratches.
  • the use of gold is proposed in conjunction with SiO2 deposited by methods such as vacuum deposition. The method can be applied to watch cases and makes it possible to reduce the gold content to one fifth of a conventional coating while increasing the abrasion resistance.
  • the document JP-A-6O 67 654 describes a coating of an object formed of gold or of a gold alloy and titanium nitride by evaporation under vacuum, for example. This improves the abrasion and scratch resistance of objects such as watches or spectacle frames.
  • Figure 1 is a partial sectional view of the object according to the prior art.
  • Object 1 can be a watch case, a link making up a bracelet or any other item of jewelry.
  • he comprises a box body or substrate 2 which can be made of noble metal, common metal (stainless steel, brass) or plastic.
  • the substrate 2 is surmounted by a coating 3 called the first layer.
  • This first layer consists mainly of a precious metal from the group of gold, silver, rhodium, palladium, platinum, iridium, osmium and ruthenium or an alloy of said precious metal, represented by an oblique hatching 4.
  • This layer 3 also comprises discrete inclusions of a metallic compound constituted by an oxide, a nitride, a carbide, a boride, a phosphide, a silicide or a fluoride, represented by points 5.
  • discrete means that these are inclusions, that is to say aggregates composed of a large number of molecules without chemical bonds with the precious metal. These inclusions are distributed in a substantially homogeneous manner throughout the thickness of the layer considered.
  • This layer is obtained by vapor deposition, for example by CVD or PVD methods well known in the state of the art. These techniques are described in detail in the documents cited above and there is therefore no need to return to them here.
  • the deposit is applied in a single operation, either from a composite source, or from two sources, one containing the metal, the other the metallic compound.
  • the fine inclusions of metallic compound (of the order of 100 A) are distributed very evenly in the layer. This would not be the case if this layer was deposited galvanically from a bath containing metallic compounds in the form of powders whose dimensions would necessarily be much larger (of the order of 1 ⁇ m). In the latter case the distribution of inclusions in the layer would be less homogeneous because the dimension of these inclusions is of the same order than the thickness of the layer. This would result in a decrease in wear resistance.
  • the coating comprises only a single first layer of precious metal and inclusions of metallic compound. If it is desired to produce an imitation of plating only, this layer will remain thin and its thickness will be between 0.5 and 1.5 ⁇ m for example. In addition to the metallic compound, this layer will include precious metal in the pure state or in the alloy state.
  • a precious metal alloy instead of pure precious metal, an alloy with a title equal to or greater than that required by legislation.
  • a second layer 6 consisting of a precious metal or an alloy of said precious metal, for example galvanically deposited.
  • a first layer 3 composed of a precious metal or a precious metal alloy 4 and inclusions of metallic compound 5 defined during the description of FIG. 1.
  • the second layer 6 can be pure precious metal if you want a high-grade coating or an alloy at 9, 14, 18 C depending on the title you want to reach.
  • This second embodiment has the advantage of being the cheapest since most of the coating is galvanically deposited, a very common process well known to specialists.
  • FIG. 3 reports spectral reflectivity measurements carried out on several samples using a spectrophotometer.
  • Curve A is that of fine gold (or pure gold)
  • curves B and C are those of standard colors defined respectively by symbols 1N14 and 2H18 of the standards of the Swiss watch industry (NIHS)
  • curve M is that of gold with inclusions according to the invention.
  • Curve M is obtained with inclusions of titanium nitride (TiN) in fine gold, these inclusions representing by volume 5 to 7% of the total volume occupied by the first layer.
  • This curve shows that the reflectivity of the first layer is close to that of the standard colors of layers commonly used in the watch industry (curves B and C) and which are generally obtained by galvanic means.
  • the layer studied here is naturally only an example and it is clear that by varying the percentage of inclusions and / or by replacing TiN with another metallic compound, it will be possible to obtain very different reflectivities and hence the colors related to other standards than those considered above.
  • FIG. 4 is a diagram reporting measurements on the wear resistance of the coated articles according to the invention compared to the wear resistance of a galvanically coated object.
  • it is a gold coating with inclusions at 6% by volume of TiN.
  • the time in hours during which the samples are subjected to the wear test was plotted on the abscissa and the mass of material removed in milligrams (mg) on the ordinate.
  • the samples to be tested are put in a smoothing machine by sliding with ceramic sticks, water and a wetting agent.
  • the abrasive mass and the samples oscillate in several directions and undergo a smoothing pressure which is pulsed.
  • the mass loss of the samples is determined as a function of the treatment time.
  • Such a smoothing machine was described in communication no. 18 entitled: "The wear of watch cases in galvanic gold plated" from the 57th congress of the Swiss Chronometry Society, Montreux 22 and 23 October 1982.
  • the method which has just been described operates by smoothing or rubbing the surface to be examined. It differs in this from a simple hardness measurement with a microdurometer, because we realized that it is not always correct to correlate a hardness measurement and a determination of the resistance to wear.
  • the coating does not have a much higher hardness in the sense that it is usually understood, but rather an excellent resistance to wear if this is measured by simulating the phenomenon of wear. as it occurs naturally.
  • curve A ′ represents the mass loss of a sample covered with galvanic fine gold
  • curve M ′ represents the mass loss of a sample covered with the coating according to the invention, the mass losses being measured according to the method indicated above under identical conditions.
  • the loss of mass therefore the wear is about twice as low for the sample covered according to the invention this characteristic remaining substantially constant throughout the time that the test lasted (240 hours).
  • the reduction in thickness of a layer of galvanic gold alloy titrating 18 carats is around 2 ⁇ m per year for a watch case to wear. This reduction will only be 1 ⁇ m for the same period if the watch case is coated with the layer defined by the invention, which represents a remarkable improvement.
  • Decorative coatings generally include a so-called color finishing phase.
  • This important operation generally consists in depositing a layer of gold with a thickness of between 0.5 and 1.5 ⁇ m for 23.5 C. It aims mainly at two goals: that of checking the final color first ( aspect) of the plating, because the underlying plating composed of gold, silver, copper, cadmium can have very variable colors depending on the deposition conditions (different deposition rate of the metals constituting the alloy); that of preventing the color changes in the underlying plating (tarnishing) that would occur over time, changes that are all the more important the lower the titer.
  • the galvanic coloring phase is replaced by a phase pursuing the same goals but deposited in the vapor phase.
  • the wear resistance will be at least doubled, which will lead to a plating of higher quality and better reliability, thanks to the inclusions of metallic compound deposited at the same time as the precious metal.
  • the coating deposited according to the invention must have a total thickness of at least 8 ⁇ m and titrate at least 9 carats.
  • This coating could comprise a second layer of gold alloy with a thickness equal to or greater than 7 ⁇ m, second layer on which is deposited a first layer of thickness reaching at least 1 ⁇ m obtained in the vapor phase and containing gold and nitride inclusions of titanium occupying a volume of between 5% and 7% of the total volume occupied by said first layer.
  • the coating according to the invention also has a corrosion resistance which is comparable to that of precious metal without inclusions.
  • tests have been carried out according to conventional methods such as, for example, exposure to salt spray and periodic soaking in artificial sea water or artificial sweat.

Description

L'invention est relative à un objet, notamment une boîte de montre, surmonté d'un revêtement résistant à l'usure et constitué principalement d'un métal précieux du groupe de l'or, l'argent, le rhodium, le palladium, le platine, l'iridium, l'osmium et le ruthénium ou d'un alliage dudit métal précieux, ledit revêtement étant constitué d'une première couche dudit métal précieux ou de son alliage, ladite première couche comprenant des inclusions discrètes d'un composé métallique constitué par un oxyde, un nitrure, un carbure, un borure, un phosphure, un siliciure ou un fluorure, lesdites inclusions étant réparties de manière sensiblement homogène dans toute l'épaisseur de la première couche, ladite première couche étant appliquée par déposition en phase vapeur (CVD ou PVD), son épaisseur étant égale ou supérieure à 0,4 µm.The invention relates to an object, in particular a watch case, surmounted by a wear-resistant coating and consisting mainly of a precious metal from the group of gold, silver, rhodium, palladium, platinum, iridium, osmium and ruthenium or an alloy of said precious metal, said coating consisting of a first layer of said precious metal or its alloy, said first layer comprising discrete inclusions of a compound metallic consisting of an oxide, a nitride, a carbide, a boride, a phosphide, a silicide or a fluoride, said inclusions being distributed in a substantially homogeneous manner throughout the thickness of the first layer, said first layer being applied by deposition in vapor phase (CVD or PVD), its thickness being equal to or greater than 0.4 µm.

Des revêtements résistant à l'usure et à la corrosion contenant un métal précieux, notamment de l'or, ont déjà été décrits maintes fois. Le but recherché consiste à obtenir un produit ayant une bonne résistance au rayage tout en présentant l'aspect et l'éclat de l'or.Wear-resistant and corrosion-resistant coatings containing a precious metal, in particular gold, have already been described many times. The aim is to obtain a product with good scratch resistance while having the appearance and luster of gold.

C'est le cas par exemple de l'objet défini dans la demande GB-A-2.000.812 où l'on dépose sur une première couche de TiN, TaN, TaC, ZrN ou VN une couche de métal noble ou d'alliage soit par évaporation et placage ionique (exemples 1 et 2), soit par un placage électrochimique suivi d'un traitement thermique de diffusion (exemples 3 et 5). Il est également envisagé de réaliser successivement des couches de Ti, de TiN, d'un mélange de TiN et de métal noble, et d'or ou d'un alliage d'or. Les revêtements obtenus dans tous ces modes de réalisation sont constitués de couches superposées de compositions très différentes, déposées l'une après l'autre. Ils risquent par conséquent de présenter des défauts d'homogénéité ou de résistance au rayage ou aux chocs thermiques aux interfaces entre les différentes couches.This is the case for example of the object defined in application GB-A-2,000,812 where a layer of noble metal or alloy is deposited on a first layer of TiN, TaN, TaC, ZrN or VN either by evaporation and ion plating (examples 1 and 2), or by electrochemical plating followed by a diffusion heat treatment (examples 3 and 5). It is also envisaged to successively produce layers of Ti, of TiN, of a mixture of TiN and of noble metal, and of gold or of a gold alloy. The coatings obtained in all these embodiments consist of superimposed layers of very different compositions, deposited one after the other. They are therefore likely to present defects in uniformity or resistance to scratching or thermal shock at the interfaces between the different layers.

Il est également prévu dans la même demande de brevet britannique (exemple 4) de former, après le dépôt par évaporation et placage ionique d'une couche de TiN, une deuxième couche obtenue par l'évaporation simultanée de deux sources distinctes formées respectivement de Ti et de Cu. Les remarques précédentes s'appliquent encore, mais, en outre, on notera que ce dernier procédé ne permet pas d'obtenir une couche de métal noble à la surface externe du revêtement.It is also provided in the same British patent application (Example 4) to form, after the deposition by evaporation and ion plating of a layer of TiN, a second layer obtained by the simultaneous evaporation of two distinct sources formed respectively of Ti and Cu. The above remarks still apply, but, moreover, it will be noted that this latter method does not make it possible to obtain a layer of noble metal on the external surface of the coating.

Dans l'objet décrit dans le document précité la couche d'or superficielle doit être mince (égale ou inférieure à 1 µm) pour que le revêtement produise l'effet attendu, à savoir rendre peu apparentes des rayures provoquées par des corps étrangers. En cela le revêtement décrit ne permet pas d'atteindre un vrai placage contenant assez de métal précieux pour que ledit objet puisse porter le poinçon de maître.In the object described in the aforementioned document, the surface gold layer must be thin (equal to or less than 1 μm) for the coating to produce the expected effect, namely to make scratches caused by foreign bodies not very visible. In this the coating described does not allow to reach a real plating containing enough precious metal so that said object can carry the maker's mark.

Pour pallier les inconvénients cités dans le document ci-dessus, le brevet EP-B-0038294 (=US 4.403.014) propose un procédé simple, permettant d'effectuer des dépôts de revêtements durs, métalliques dont la composition varie de façon progressive de la surface de l'objet vers la surface extérieure, et cela au moyen d'une source soumise à un seul processus d'évaporation ou de pulvérisation. Ainsi, au cours du dépôt, fait-on simultanément croître la concentration en volume de métal précieux et décroitre celle d'un composé métallique (par exemple du TiN) déposés selon des gradients opposés au moyen d'une source comportant des gradients de concentration en volume de métal précieux et de composé métallique opposés. Un autre mode d'exécution de l'invention citée part de deux sources séparées constituées respectivement par le métal noble et le composé métallique, ces sources étant soumises à un procédé d'évaporation selon des vitesses croissantes, respectivement décroissantes.To overcome the drawbacks mentioned in the document above, patent EP-B-0038294 (= US 4,403,014) proposes a simple process, making it possible to deposit hard, metallic coatings whose composition varies gradually from the surface of the object towards the external surface, and this by means of a source subjected to a single process of evaporation or spraying. Thus, during deposition, we simultaneously increase the volume concentration of precious metal and decrease that of a metal compound (for example TiN) deposited in opposite gradients by means of a source comprising gradients of concentration in volume of opposing precious metal and metal compound. Another embodiment of the cited invention starts from two separate sources constituted respectively by the noble metal and the metallic compound, these sources being subjected to an evaporation process at increasing, respectively decreasing, speeds.

Le procédé qui vient d'être décrit a l'inconvénient de devoir mettre en oeuvre soit une source composite dont l'épaisseur doit être en rapport avec l'épaisseur du dépôt à effectuer, soit un réglage délicat de l'appareil de dépôt qui doit être en mesure de contrôler avec précision la variation de vitesse de pulvérisation en cours de processus. D'autre part ce procédé conduit par définition à des dépôts dont le pourcentage volumique d'or et de composé métallique est identique ce qui ne permet pas d'atteindre un dépôt d'or à très haut titre. Enfin on notera que le procédé est mal adapté au dépôt de placage en couches épaisses car il est lent et onéreux.The process which has just been described has the drawback of having to use either a composite source whose thickness must be in relation to the thickness of the deposit to be made, or a delicate adjustment of the depositing apparatus which must be able to precisely control the variation in spray speed during the process. On the other hand this process leads by definition to deposits of which the volume percentage of gold and of compound metallic is identical which does not allow to reach a gold deposit with very high title. Finally, it will be noted that the process is ill-suited to depositing plating in thick layers because it is slow and expensive.

Les revêtements qui font l'objet des deux documents cités plus haut, bien qu'étant différents dans leur composition, présentent une caractéristique commune: ils possèdent les deux une couche de métal précieux, par exemple de l'or, déposée sur des couches sousjacentes beaucoup plus dures que celle du métal précieux, par exemple du nitrure de titane. Si la couche superficielle est rayée, elle ne le sera que peu profondément et la rayure ne sera que peu apparente et cela d'autant plus si la couche sousjacente est d'une couleur proche de celle du métal précieux déposé en surface.The coatings which are the subject of the two documents cited above, although being different in their composition, have a common characteristic: they both have a layer of precious metal, for example gold, deposited on underlying layers much harder than that of precious metal, for example titanium nitride. If the surface layer is scratched, it will be only slightly deep and the scratch will be only slightly visible, and this all the more if the underlying layer is of a color close to that of the precious metal deposited on the surface.

Les propriétés optiques, électriques, mécaniques et de résistance à la corrosion d'un film d'or comprenant des particules de silice (SiO₂) et déposé par un procédé en phase vapeur ont été discutées dans la revue "Thin Solid Films" vol. 39(1976) p. 165 à 174, Elsevier Sequoia, Lausanne, Taylor et al: "Properties of metal - dielectric codeposited films". L'article en question analyse avant tout les propriétés optiques d'une telle couche. En particulier la réflectivité spectrale de l'or pur est comparée à celle d'un film composite d'or et de SiO₂. Très succinctement l'article mentionne que la résistance à la rayure du composé Au-SiO₂ est très bonne dans tout le domaine de composition examiné, ladite résistance étant bien meilleure que celle d'un film d'or pur. Cette remarque, purement qualitative, n'est complétée par aucune donnée quantitative. L'article en question ne donne aucun enseignement sur les modifications des propriétés optiques et mécaniques dues à une structure non homogène (croissance colonnaire à faible densité, par exemple) qui pourraient apparaître pour des épaisseurs de films de l'ordre 0,4 µm ou davantage.The optical, electrical, mechanical and corrosion resistance properties of a gold film comprising silica particles (SiO₂) and deposited by a vapor phase process were discussed in the review "Thin Solid Films" vol. 39 (1976) p. 165 to 174, Elsevier Sequoia, Lausanne, Taylor et al: "Properties of metal - dielectric codeposited films". The article in question first analyzes the optical properties of such a layer. In particular, the spectral reflectivity of pure gold is compared to that of a composite film of gold and SiO₂. Very briefly the article mentions that the scratch resistance of the Au-SiO₂ compound is very good in the whole range of composition examined, said resistance being much better than that of a film of pure gold. This remark, purely qualitative, is not supplemented by any quantitative data. The article in question gives no teaching on the modifications of the optical and mechanical properties due to an inhomogeneous structure (columnar growth at low density, for example) which could appear for thicknesses of films of the order 0.4 µm or more.

Le document JP-A-59 185774 décrit un placage d'alliage d'or déposé en phase vapeur et comportant en outre des agents durcisseurs se présentant sous la forme de nitrures. Grâce à cet apport, la dureté et la résistance à la corrosion du placage sont améliorées.Document JP-A-59 185774 describes a plating of a gold alloy deposited in the vapor phase and further comprising hardening agents in the form of nitrides. Thanks to this contribution, the hardness and the corrosion resistance of the plating are improved.

Le document JP-A-60 114567 propose l'utilisation d'un métal précieux codéposé avec un oxyde transparent pour former le revêtement d'un objet qui présente alors une meilleure résistance à l'usure et aux rayures. On propose l'utilisation d'or conjointement avec du SiO₂ déposés par des méthodes telles que le dépôt sous vide. La méthode peut être appliquée à des boîtes de montre et permet de réduire le contenu d'or au cinquième d'un revêtement conventionnel tout en augmentant la résistance à l'abrasion.Document JP-A-60 114567 proposes the use of a precious metal codeposited with a transparent oxide to form the coating of an object which then has better resistance to wear and scratches. The use of gold is proposed in conjunction with SiO₂ deposited by methods such as vacuum deposition. The method can be applied to watch cases and makes it possible to reduce the gold content to one fifth of a conventional coating while increasing the abrasion resistance.

Enfin le document JP-A-6O 67654 décrit un revêtement d'objet formé d'or ou d'alliage d'or et de nitrure de titane par évaporation sous vide par exemple. On améliore ainsi la résistance à l'abrasion et aux rayures d'objets comme des montres ou des montures de lunettes.Finally, the document JP-A-6O 67 654 describes a coating of an object formed of gold or of a gold alloy and titanium nitride by evaporation under vacuum, for example. This improves the abrasion and scratch resistance of objects such as watches or spectacle frames.

Dans les quatre derniers documents cités ci-dessus on porte l'accent sur la minceur de la couche déposée, d'où économie de matière précieuse, le souci étant de proposer une couche avant tout résistante à l'usure. Il n'est nullement fait mention de couches épaisses de métal précieux destinées à porter le poinçon d'orfèvre ou également de couches épaisses devant être mises en couleur tout en étant résistantes à l'usure.In the last four documents cited above, the emphasis is on the thinness of the deposited layer, hence saving precious material, the concern being to provide a layer which is above all resistant to wear. There is no mention of thick layers of precious metal intended to carry the goldsmith's punch or also of thick layers to be colored while being resistant to wear.

C'est l'objet principal de la présente invention de proposer un revêtement comportant une seconde couche d'un métal précieux ou d'un alliage dudit métal précieux, seconde couche disposée entre l'objet et la première couche, l'épaisseur totale dudit revêtement étant égale ou supérieure à 8 µm.It is the main object of the present invention to provide a coating comprising a second layer of a precious metal or of an alloy of said precious metal, second layer disposed between the object and the first layer, the total thickness of said coating being equal to or greater than 8 µm.

L'invention sera mieux comprise maintenant à l'aide de la description qui suit et des dessins qui l'illustrent à titre d'exemple et dans lesquels

  • la figure 1 est une coupe dans l'objet selon l'art antérieur,
  • la figure 2 est une coupe dans l'objet de l'invention,
  • la figure 3 est un diagramme présentant des mesures de réflectivité exécutées sur les objets obtenus par l'invention, et
  • la figure 4 est un diagramme rendant compte de mesures de résistance à l'usure des objets en question.
The invention will be better understood now with the aid of the description which follows and of the drawings which illustrate it by way of example and in which
  • FIG. 1 is a section through the object according to the prior art,
  • FIG. 2 is a section through the subject of the invention,
  • FIG. 3 is a diagram showing reflectivity measurements carried out on the objects obtained by the invention, and
  • Figure 4 is a diagram showing measures of resistance to wear of the objects in question.

La figure 1 est une vue partielle en coupe de l'objet selon l'art antérieur. L'objet 1 peut être une boîte de montre, un maillon composant un bracelet ou tout autre article de joaillerie. Il comprend un corps de boîte ou substrat 2 qui peut être fait en métal noble, en métal commun (acier inoxydable, laiton) ou en matière plastique. Le substrat 2 est surmonté d'un revêtement 3 dit première couche. Cette première couche est constituée principalement d'un métal précieux du groupe de l'or, l'argent, le rhodium, le palladium, le platine, l'iridium, l'osmium et le ruthénium ou d'un alliage dudit métal précieux, figurés par une hachure oblique 4. Cette couche 3 comporte en outre des inclusions discrètes d'un composé métallique constitué par un oxyde, un nitrure, un carbure, un borure, un phosphure, un siliciure ou un fluorure, figurées par des points 5.Figure 1 is a partial sectional view of the object according to the prior art. Object 1 can be a watch case, a link making up a bracelet or any other item of jewelry. he comprises a box body or substrate 2 which can be made of noble metal, common metal (stainless steel, brass) or plastic. The substrate 2 is surmounted by a coating 3 called the first layer. This first layer consists mainly of a precious metal from the group of gold, silver, rhodium, palladium, platinum, iridium, osmium and ruthenium or an alloy of said precious metal, represented by an oblique hatching 4. This layer 3 also comprises discrete inclusions of a metallic compound constituted by an oxide, a nitride, a carbide, a boride, a phosphide, a silicide or a fluoride, represented by points 5.

Le terme "discret" signifie qu'il s'agit ici d'inclusions, c'est-à-dire d'agrégats composés d'un grand nombre de molécules sans liaisons chimiques avec le métal précieux. Ces inclusions sont réparties de manière sensiblement homogène dans toute l'épaisseur de la couche considérée. Cette couche est obtenue par déposition en phase vapeur, par exemple par des procédés CVD ou PVD bien connus de l'état de la technique. Ces techniques sont décrites en détail dans les documents cités plus haut et il n'est donc pas nécessaire d'y revenir ici.The term "discrete" means that these are inclusions, that is to say aggregates composed of a large number of molecules without chemical bonds with the precious metal. These inclusions are distributed in a substantially homogeneous manner throughout the thickness of the layer considered. This layer is obtained by vapor deposition, for example by CVD or PVD methods well known in the state of the art. These techniques are described in detail in the documents cited above and there is therefore no need to return to them here.

Des précautions particulières devront toutefois être prises si l'on veut obtenir un dépôt dont l'aspect soit celui du métal précieux ou d'un de ses alliages. Comme la couche à déposer est relativement épaisse, on veillera tout spécialement à refroidir l'objet à recouvrir tout au long du processus. On évitera ainsi les croissances colonnaires à faible densité qui ont été évoquées ci-dessus. Le dépôt est appliqué en une seule opération, soit à partir d'une source composite, soit à partir de deux sources l'une contenant le métal, l'autre le composé métallique.However, special precautions must be taken if one wishes to obtain a deposit whose appearance is that of the precious metal or one of its alloys. As the layer to be deposited is relatively thick, special care will be taken to cool the object to be covered throughout the process. This will avoid the low density columnar growths which have been mentioned above. The deposit is applied in a single operation, either from a composite source, or from two sources, one containing the metal, the other the metallic compound.

Grâce à la déposition en phase vapeur, les fines inclusions de composé métallique (de l'ordre de 100 A) sont réparties de façon très homogène dans la couche. Ce ne serait pas le cas si cette couche était déposée galvaniquement à partir d'un bain contenant des composés métalliques sous forme de poudres dont les dimensions seraient nécessairement bien plus grandes (de l'ordre de 1 µm). Dans ce dernier cas la distribution des inclusions dans la couche serait moins homogène car la dimension de ces inclusions est du même ordre de grandeur que l'épaisseur de la couche. Il en résulterait une diminution de la résistance à l'usure.Thanks to the vapor deposition, the fine inclusions of metallic compound (of the order of 100 A) are distributed very evenly in the layer. This would not be the case if this layer was deposited galvanically from a bath containing metallic compounds in the form of powders whose dimensions would necessarily be much larger (of the order of 1 μm). In the latter case the distribution of inclusions in the layer would be less homogeneous because the dimension of these inclusions is of the same order than the thickness of the layer. This would result in a decrease in wear resistance.

Si l'on se reporte à nouveau à la coupe présentée en figure 1 qui présente l'art antérieur, le revêtement ne comporte qu' une seule première couche de métal précieux et d'inclusions de composé métallique. Si l'on désire produire une imitation de placage seulement, cette couche restera mince et son épaisseur sera comprise entre 0,5 et 1, 5 µm par exemple. En plus du composé métallique, cette couche comprendra du métal précieux à l'état pur ou à l'état d'alliage.If we refer again to the section presented in FIG. 1 which presents the prior art, the coating comprises only a single first layer of precious metal and inclusions of metallic compound. If it is desired to produce an imitation of plating only, this layer will remain thin and its thickness will be between 0.5 and 1.5 μm for example. In addition to the metallic compound, this layer will include precious metal in the pure state or in the alloy state.

Dans le cas cependant où l'on désire mettre sur le marché un objet plaqué autorisé à porter le poinçon de maître, cette couche devra être beaucoup plus épaisse pour obéir aux diverses législations nationales. Pour prendre l'exemple de la législation actuellement en vigueur en Suisse, le placage doit au moins avoir une épaisseur de 8 µm et titrer au moins 9 carats (C) pour être autorisé à porter le poinçon du maître. En utilisant une seule première couche d'épaisseur 8 µm contenant du métal précieux pur et déposée comme indiqué on sera conduit à un titre très élevé si l'on utilise le revêtement discuté plus haut contenant 6 % en volume de TiN (plus de 23 C). Pour abaisser le titre et partant le prix de l'objet, on pourrait naturellement augmenter la proportion de composé métallique, mais on risquerait alors d'obtenir une réflectivité ne correspondant plus à l'étalon de couleur que l'on désire obtenir, comme cela sera discuté ci-après à propos de la figure 3.However, in the case where one wishes to put on the market a plated object authorized to carry the maker's mark, this layer will have to be much thicker to obey the various national legislations. To take the example of the legislation currently in force in Switzerland, the veneer must at least have a thickness of 8 µm and titrate at least 9 carats (C) to be authorized to carry the maker's mark. By using a single first layer 8 μm thick containing pure precious metal and deposited as indicated, the titer will be very high if the coating discussed above containing 6% by volume of TiN (more than 23 C) is used. ). To lower the title and therefore the price of the object, one could naturally increase the proportion of metallic compound, but one would then risk obtaining a reflectivity no longer corresponding to the color standard that one wishes to obtain, like this will be discussed below in connection with Figure 3.

Pour remédier à cet inconvénient, on peut utiliser un alliage de métal précieux au lieu du métal précieux pur, alliage au titre égal ou supérieur à celui exigé par la législation. On pourrait par exemple choisir un alliage d'or à 14 C contenant notamment 14 parties d'or, 8 1/4 parties d'argent et 1 3/4 partie de cuivre et lui inclure du TiN ou du SiO₂, alliage et composés métalliques étant codéposés en phase vapeur.To remedy this drawback, it is possible to use a precious metal alloy instead of pure precious metal, an alloy with a title equal to or greater than that required by legislation. One could for example choose a 14 C gold alloy containing in particular 14 parts of gold, 8 1/4 parts of silver and 1 3/4 part of copper and include TiN or SiO₂, alloy and metallic compounds therein. being co-deposited in the vapor phase.

Il n'en reste pas moins qu'une seule couche déposée selon l'art antérieur est très onéreuse si l'on désire obtenir des couches épaisses car le dépôt en phase vapeur est très lent et donc dispendieux en temps. On en arrive donc à décrire maintenant l'objet de l'invention et on se reportera pour cela à la figure 2.The fact remains that a single layer deposited according to the prior art is very expensive if it is desired to obtain thick layers because the vapor deposition is very slow and therefore expensive in time. We therefore come now to describe the object of the invention and we will therefore refer to FIG. 2.

Directement appliquée sur le substrat 2 on trouve une seconde couche 6 constituée d'un métal précieux ou d'un alliage dudit métal précieux déposé par exemple galvaniquement. Par dessus cette seconde couche 6 se trouve une première couche 3 composée d'un métal précieux ou d'un alliage de métal précieux 4 et des inclusions de composé métallique 5 définis lors de la description de la figure 1. La seconde couche 6 peut être du métal précieux pur si l'on désire un revêtement à haut titre ou un alliage à 9, 14, 18 C selon le titre que l'on désire atteindre.Directly applied to the substrate 2 there is a second layer 6 consisting of a precious metal or an alloy of said precious metal, for example galvanically deposited. Above this second layer 6 is a first layer 3 composed of a precious metal or a precious metal alloy 4 and inclusions of metallic compound 5 defined during the description of FIG. 1. The second layer 6 can be pure precious metal if you want a high-grade coating or an alloy at 9, 14, 18 C depending on the title you want to reach.

Ce second mode d'exécution a l'avantage d'être le meilleur marché puisque la plus grande partie du revêtement est déposé galvaniquement, procédé très courant et bien connu des spécialistes.This second embodiment has the advantage of being the cheapest since most of the coating is galvanically deposited, a very common process well known to specialists.

Des mesures de réflectivité spectrale et de résistance à l'usure ont été conduites sur des plaquettes recouvertes du revêtement selon l'invention dont l'épaisseur de la première couche 3 était au moins égale à 4000 A (= 0,4 µm).Spectral reflectivity and wear resistance measurements were carried out on wafers covered with the coating according to the invention, the thickness of the first layer 3 was at least equal to 4000 A (= 0.4 μm).

La figure 3 rend compte de mesures de réflectivité spectrale opérées sur plusieurs échantillons au moyen d'un spectrophotomètre. On trouve en abcisse la longueur d'onde de la lumière en nm (nanomètre) et en ordonnée le rapport de l'énergie réfléchie à l'énergie incidente totale en pourcent. La courbe A est celle de l'or fin (ou or pur), les courbes B et C sont celles de couleurs étalons définies respectivement par les symboles 1N14 et 2H18 des normes de l'industrie horlogère suisse (NIHS) et la courbe M est celle de l'or avec inclusions selon l'invention. La courbe M est obtenue avec des inclusions de nitrure de titane (TiN) dans de l'or fin, ces inclusions représentant en volume le 5 à 7 % du volume total occupé par la première couche. Cette courbe montre que la réflectivité de la première couche est proche de celles des couleurs étalons de couches utilisées couramment dans l'industrie horlogère (courbes B et C) et qui sont généralement obtenues par voie galvanique. La couche étudiée ici n'est naturellement qu'un exemple et il est clair qu'en variant le pourcentage d'inclusions et/ou en remplaçant le TiN par un autre composé métallique on pourra obtenir des réflectivités très différentes et partant des teintes s'apparentant à d'autres étalons que ceux considérés plus haut.FIG. 3 reports spectral reflectivity measurements carried out on several samples using a spectrophotometer. We find the wavelength of light in nm (nanometer) on the abscissa and the ratio of the energy reflected to the total incident energy in percent on the ordinate. Curve A is that of fine gold (or pure gold), curves B and C are those of standard colors defined respectively by symbols 1N14 and 2H18 of the standards of the Swiss watch industry (NIHS) and curve M is that of gold with inclusions according to the invention. Curve M is obtained with inclusions of titanium nitride (TiN) in fine gold, these inclusions representing by volume 5 to 7% of the total volume occupied by the first layer. This curve shows that the reflectivity of the first layer is close to that of the standard colors of layers commonly used in the watch industry (curves B and C) and which are generally obtained by galvanic means. The layer studied here is naturally only an example and it is clear that by varying the percentage of inclusions and / or by replacing TiN with another metallic compound, it will be possible to obtain very different reflectivities and hence the colors related to other standards than those considered above.

Un cas particulier intéressant est celui pour lequel la quantité d'inclusions est telle que la réflectivité de la première couche est sensiblement la même que la réflectivité du métal à l'état pur. On a constaté par exemple que des inclusions de silice (SiO₂) à moins de 10% en volume dans de l'or fin amènent à une courbe de réflectivité qui est presque identique à celle de l'or fin.An interesting particular case is that for which the amount of inclusions is such that the reflectivity of the first layer is substantially the same as the reflectivity of the metal in the pure state. It has been found, for example, that inclusions of silica (SiO₂) at less than 10% by volume in fine gold lead to a reflectivity curve which is almost identical to that of fine gold.

La figure 4 est un diagramme rendant compte de mesures sur la résistance à l'usure des objets revêtus selon l'invention par rapport à la résistance à l'usure d'un objet revêtu galvaniquement. Il s'agit dans cet exemple de revêtement d'or avec des inclusions à 6% en volume de TiN. On a porté en abcisse le temps en heures pendant lequel les échantillons sont soumis au test d'usure et en ordonnée la masse de matière enlevée en milligramme (mg). Les échantillons à tester sont mis dans une machine à lisser par glissement avec des bâtonnets en céramique, de l'eau et un mouillant. La masse abrasive et les échantillons oscillent dans plusieurs directions et subissent une pression de lissage qui est pulsé. On détermine la perte de masse des échantillons en fonction du temps de traitement. Une telle machine à lisser a été décrite dans la communication no 18 intitulée: "L'usure des boîtiers de montre en plaqué or galvanique" du 57ème congrès de la Société Suisse de Chronométrie, Montreux 22 et 23 octobre 1982.FIG. 4 is a diagram reporting measurements on the wear resistance of the coated articles according to the invention compared to the wear resistance of a galvanically coated object. In this example, it is a gold coating with inclusions at 6% by volume of TiN. The time in hours during which the samples are subjected to the wear test was plotted on the abscissa and the mass of material removed in milligrams (mg) on the ordinate. The samples to be tested are put in a smoothing machine by sliding with ceramic sticks, water and a wetting agent. The abrasive mass and the samples oscillate in several directions and undergo a smoothing pressure which is pulsed. The mass loss of the samples is determined as a function of the treatment time. Such a smoothing machine was described in communication no. 18 entitled: "The wear of watch cases in galvanic gold plated" from the 57th congress of the Swiss Chronometry Society, Montreux 22 and 23 October 1982.

La méthode qui vient d'être décrite opère par lissage ou frottement de la surface à examiner. Elle se distingue en cela d'une simple mesure de dureté au microduromètre, car on s'est aperçu qu'il n'est pas toujours correct de mettre en corrélation une mesure de dureté et une détermination de la résistance à l'usure. Dans le cas de la présente invention le revêtement ne présente pas une dureté beaucoup plus élevée au sens où on l'entend d'habitude, mais bien une résistance à l'usure excellente si celle-ci est mesurée en simulant le phénomène d'usure tel qu'il se produit naturellement.The method which has just been described operates by smoothing or rubbing the surface to be examined. It differs in this from a simple hardness measurement with a microdurometer, because we realized that it is not always correct to correlate a hardness measurement and a determination of the resistance to wear. In the case of the present invention, the coating does not have a much higher hardness in the sense that it is usually understood, but rather an excellent resistance to wear if this is measured by simulating the phenomenon of wear. as it occurs naturally.

Sur la figure 4 la courbe A' représente la perte de masse d'un échantillon recouvert d'or fin galvanique et la courbe M' la perte de masse d'un échantillon recouvert du revêtement selon l'invention, les pertes de masse étant mesurées selon la méthode indiquée ci-dessus dans des conditions identiques. On s'aperçoit que la perte de masse donc l'usure est envion deux fois plus faible pour l'échantillon recouvert selon l'invention cette caractéristique restant sensiblement constante pendant tout le temps qu'a duré l'essai (240 heures). Dans l'ouvrage intitulé "L'habillement de la montre" par J.P. Renaud, LSRH, Neuchâtel 3 et 17 juin 1975, on a montré que la diminution d'épaisseur d'une couche d'alliage d'or galvanique titrant 18 carats est de l'ordre de 2 µm par année pour une boîte de montre au porter. Cette diminution ne sera plus que de 1 µm pour la même période si la boîte de montre est revêtue de la couche définie par l'invention, ce qui représente une amélioration remarquable.In FIG. 4, curve A ′ represents the mass loss of a sample covered with galvanic fine gold and curve M ′ represents the mass loss of a sample covered with the coating according to the invention, the mass losses being measured according to the method indicated above under identical conditions. We notice that the loss of mass therefore the wear is about twice as low for the sample covered according to the invention this characteristic remaining substantially constant throughout the time that the test lasted (240 hours). In the work entitled "The clothing of the watch" by JP Renaud, LSRH, Neuchâtel June 3 and 17, 1975, it has been shown that the reduction in thickness of a layer of galvanic gold alloy titrating 18 carats is around 2 µm per year for a watch case to wear. This reduction will only be 1 µm for the same period if the watch case is coated with the layer defined by the invention, which represents a remarkable improvement.

Les revêtements décoratifs comportent généralement une phase de finition dite de mise en couleur. Cette opération importante consiste généralement à déposer une couche d'or d'épaisseur comprise entre 0,5 et 1,5 µm au titre de 23,5 C. Elle vise principalement deux buts: celui d'abord du contrôle de la couleur finale (aspect) du placage, car le placage sousjacent composé d'or, d'argent, de cuivre, de cadmium peut présenter des couleurs très variables selon les conditions de déposition (vitesse de dépôt différente des métaux constituant l'alliage); celui ensuite d'empêcher les changements de couleur du placage sousjacent (ternissement) qui se produiraient avec le temps, changements d'autant plus importants que le titre est faible.Decorative coatings generally include a so-called color finishing phase. This important operation generally consists in depositing a layer of gold with a thickness of between 0.5 and 1.5 μm for 23.5 C. It aims mainly at two goals: that of checking the final color first ( aspect) of the plating, because the underlying plating composed of gold, silver, copper, cadmium can have very variable colors depending on the deposition conditions (different deposition rate of the metals constituting the alloy); that of preventing the color changes in the underlying plating (tarnishing) that would occur over time, changes that are all the more important the lower the titer.

Dans le revêtement selon l'invention on remplace la phase de mise en couleur galvanique par une phase poursuivant les mêmes buts mais déposée en phase vapeur. Dans ce cas cependant, comme on l'a montré plus haut, la résistance à l'usure sera au moins doublée ce qui conduira à un placage de qualité supérieure et de meilleure fiabilité et ceci grâce aux inclusions de composé métallique déposées en même temps que le métal précieux.In the coating according to the invention, the galvanic coloring phase is replaced by a phase pursuing the same goals but deposited in the vapor phase. In this case, however, as shown above, the wear resistance will be at least doubled, which will lead to a plating of higher quality and better reliability, thanks to the inclusions of metallic compound deposited at the same time as the precious metal.

Pour reprendre ce qui a été dit à propos de la législation suisse sur le contrôle du commerce des métaux précieux, le revêtement déposé selon l'invention devra avoir une épaisseur totale d'au moins 8 µm et titrer au moins 9 carats. Ce revêtement pourrait comprendre une seconde couche d'alliage d'or d'une épaisseur égale ou supérieure à 7 µm, seconde couche sur laquelle est déposée une première couche d'épaisseur atteignant au moins 1 µm obtenue en phase vapeur et contenant de l'or et des inclusions de nitrure de titane occupant un volume compris entre 5 % et 7 % du volume total occupé par ladite première couche.To repeat what has been said about the Swiss legislation on the control of trade in precious metals, the coating deposited according to the invention must have a total thickness of at least 8 µm and titrate at least 9 carats. This coating could comprise a second layer of gold alloy with a thickness equal to or greater than 7 μm, second layer on which is deposited a first layer of thickness reaching at least 1 μm obtained in the vapor phase and containing gold and nitride inclusions of titanium occupying a volume of between 5% and 7% of the total volume occupied by said first layer.

Il est clair que d'autre épaisseurs et/ou d'autres proportions pourraient être choisies sans sortir du domaine d'application de la présente invention. On pourrait par exemple adopter les critères découlant des recommandations de l'Organisation Internationale de Normalisation (ISO).It is clear that other thicknesses and / or other proportions could be chosen without departing from the scope of the present invention. One could for example adopt the criteria resulting from the recommendations of the International Organization for Standardization (ISO).

Le revêtement selon l'invention présente aussi une résistance à la corrosion qui est comparable à celle du métal précieux sans inclusions. Pour cela des essais ont été conduits selon des méthodes classiques comme par exemple l'exposition au brouillard salin et le trempage périodique dans l'eau de mer artificielle ou de la sueur artificielle.The coating according to the invention also has a corrosion resistance which is comparable to that of precious metal without inclusions. For this, tests have been carried out according to conventional methods such as, for example, exposure to salt spray and periodic soaking in artificial sea water or artificial sweat.

Claims (5)

  1. Article such as a watch case topped by a wear resistant coating formed for the most part of a precious metal from the group including gold, silver, rhodium, palladium, platinum, iridium, osmium and ruthenium or an alloy of the foregoing, said coating being made up of a first layer (3) of said precious metal or alloy thereof (4), said first layer comprising discrete inclusions of a metallic compound (5) formed by an oxide, a nitride, a carbide, a boride, a phosphide, a silicide or a fluoride, said inclusions being distributed in a substantially homogeneous manner through the entire thickness of the first layer, said first layer being applied by vapour deposition (CVD or PVD), its thickness being equal to or greater than 0.4 µm, characterized by the fact that said coating including a second layer (6) formed by a precious metal or alloy thereof and located between the article and said first layer (3), the total thickness of said coating being equal or greater than 0.8 µm.
  2. Article according to claim 1, characterized by the fact that said second layer is an electrodeposited layer.
  3. Article according to claim 1, characterized by the fact that the quantity of the inclusions in the first layer is such that its spectral reflectivity is substantially the same as the spectral reflectivity of the precious metal or one of its alloys.
  4. Article according to claim 1, characterized by the fact that the second layer (6) is a gold alloy of at least 9 carats fineness and that the first layer (3) comprises gold and titanium nitride inclusions.
  5. Article according to claim 4, characterized by the fact that the thickness of the second layer (6) is equal to or greater than 7 µm, that the thickness of the first layer (3) is equal to or greater than 1 µm and that the titanium nitride inclusions occupy a volume between 5 and 7 % of the total volume of said first layer.
EP86114909A 1985-11-04 1986-10-27 Article coated with a wear-resistant film of a precious metal Expired - Lifetime EP0221492B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8516425 1985-11-04
FR8516425A FR2589484A1 (en) 1985-11-04 1985-11-04 OBJECT WITH PRECIOUS METAL COATING RESISTANT TO WEAR

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EP0221492A2 EP0221492A2 (en) 1987-05-13
EP0221492A3 EP0221492A3 (en) 1988-04-13
EP0221492B1 true EP0221492B1 (en) 1991-05-15

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US (1) US4745035A (en)
EP (1) EP0221492B1 (en)
JP (1) JPS62112783A (en)
DE (1) DE3679280D1 (en)
ES (1) ES2022801B3 (en)
FR (1) FR2589484A1 (en)

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Also Published As

Publication number Publication date
EP0221492A3 (en) 1988-04-13
EP0221492A2 (en) 1987-05-13
DE3679280D1 (en) 1991-06-20
FR2589484A1 (en) 1987-05-07
JPS62112783A (en) 1987-05-23
ES2022801B3 (en) 1991-12-16
US4745035A (en) 1988-05-17

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