Classifications

• • 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
  • G04B15/00—Escapements
  • G04B15/14—Component parts or constructional details, e.g. construction of the lever or the escape wheel
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2030/00—Specified physical or chemical properties which is improved by the additive characterising the lubricating composition, e.g. multifunctional additives
  • C10N2030/06—Oiliness; Film-strength; Anti-wear; Resistance to extreme pressure
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
  • C10N2040/00—Specified use or application for which the lubricating composition is intended
  • C10N2040/06—Instruments or other precision apparatus, e.g. damping fluids

Definitions

• the present invention relates to the field of watchmaking. More particularly, it concerns a watch component intended to undergo dynamic friction and having improved tribological properties, as well as a method for optimizing the tribological properties of such a watch component.
• This material also has the advantage of interesting tribological properties, which have suggested that it would be possible to rub one on the other two silicon parts, without having to resort to lubrication. Indeed, the interaction between moving parts, which is necessary for the operation of a clock mechanism, induces friction that is harmful to the performance of the mechanism and wear parts. It is therefore necessary to lubricate the parts of the components that undergo this friction. However, the oils traditionally used age and degrade, posing problems of maintenance of the movement, in particular.
• improved tribological properties is meant a reduction in the coefficient of friction, a reduction in wear with respect to a given stress or given conditions (surface condition, hygrometry, temperature, topology, etc.).
• the present invention aims to provide an alternative to the methods proposed above, to obtain a watch component intended to undergo dynamic friction, which has improved tribological properties, including the implementation of ion implantation certain elements under special conditions.
• CH709628 did not favor, and in some cases pejorate, the tribological properties of the spiral spring. As part of a spiral spring, such adverse effects on the tribological properties are of no importance, since such components do not undergo any dynamic friction during their operation, and therefore do not suggest a solution to the aforementioned problem.
• the invention relates to a watch component intended to undergo dynamic friction during its normal operation, made based on a substrate comprising a silicon layer whose crystallographic structure comprises at least one of monocrystalline, polycrystalline or amorphous forms, said substrate being reinforced by a protective layer formed on its surface during a protective operation of the substrate, said component having at least one ionically implanted zone, this zone lying in the protective layer , in the substrate or distributed between the protective layer and the substrate.
• Distributed includes a single zone disposed astride between the protective layer and the silicon layer, that is to say shared between these two layers, or several implanted zones arranged in one and the other of the different layers respectively.
• the ionically implanted zone is shared between the substrate and the protective layer, the substrate having an implantation in ion number greater than the protective layer.
• Another independent claim relates to a watch movement comprising at least one such watch component.
• the invention finally relates to a method for optimizing the tribological properties of a watch component intended to undergo dynamic friction during its normal operation, made based on a substrate comprising a silicon layer whose crystallographic structure comprises at least one of the monocrystalline, polycrystalline or amorphous forms, said substrate being reinforced by a protective layer formed on its surface during a protective operation of the substrate, said method comprising a step of ion implantation of at least one ion, by ion bombardment on the surface of said component.
• FIG. 1 illustrates the friction measured with a watch component implanted ionically at different doses, in FIG. function of the distance (in m) traveled in contact with the component by a ruby sphere,
• FIG. 2 illustrates the evolution of the average coefficient of friction measured under the conditions of FIG. 1 for a watch component according to the invention, as a function of the implantation dose
• FIGS. 3, 4, 5 and 6 represent different possibilities. implantation in a substrate, and
• FIGS 7, 8 and 9 propose different substrate configurations that may be suitable for the implementation of the invention.
• a toothed wheel meshing with another undergoes a dynamic friction at the surfaces of contact of its teeth, which is also the case between the certain components of the exhaust, including an anchor, an anchor wheel or the part of a resonator undergoing friction, such as a plateau pin, which undergo dynamic friction where they interact with neighboring components.
• a spiral spring being integral on the one hand with its peg and on the other hand with the balance shaft, it undergoes no dynamic friction in the sense of the invention and is therefore excluded from its scope since no Relative displacement is present at the points of contact between the spring and the components with which it interacts.
• silicon layer includes substrates for which, within the layer, the silicon does not form an atomic bond with other atoms.
• the different crystallographic natures of silicon are included in the scope of the invention and dopings or possible impurities present in the substrate are also possible and encompassed within the scope of the claims.
• a single layer of silicon, forming a silicon core, is also included in the scope of protection.
• this protective layer is obtained by an effective protective operation and a natural oxidation layer is not not a protective layer within the meaning of the present application, because it does not result from a protective operation as such, performed effectively and positively.
• a protective layer made of S1O2 obtained by an oxidation step measured at least 50 nm thick, which can not be obtained with natural oxidation.
• FIG. 7 the substrate takes the form of a single layer of silicon 10, covered with a protective layer 12.
• FIG. 8 the substrate takes the form of two layers of silicon 10, separated and covered with a protective layer 12.
• the substrate comprises a core 14 covered with a silicon layer 10 whose thickness is such that its tribological properties are equivalent to those of a silicon substrate.
• the protective layer 12 covers the silicon layer.
• the thickness of the silicon layer is greater than the ion implantation depth, so that the ions do not penetrate the core.
• the invention relates to a watch component made from a substrate comprising a silicon layer whose crystallographic structure comprises at least one of polycrystalline or amorphous monocrystalline, said substrate being reinforced by a layer of protection performed on its surface during a substrate protection operation, said component having at least one implanted zone ionically, this area being in the protective layer, in the substrate or distributed between the protective layer and the substrate.
• the ionically implanted zone 16 is shared between the substrate, illustrated here in the form of a single silicon layer 10, and the protective layer 12, the substrate having an implantation (in number of ions ) greater than the protective layer.
• Figure 4 shows such a configuration. It is found, more specifically, that the ions present in the protective layer are few or very few and that they are essentially concentrated in a specific area of the substrate.
• ion bombardment for example, ion beam, MEWA - Metal Vapor Vacuum Arc
• the ion density curve as a function of the depth of the component forms a narrow Gaussian showing this concentration in a region. precise.
• the implanted area is located at least in the substrate.
• the implanted zone 16 is located only in the protective layer 12 ( Figure 5). This is particularly the case with a protective layer having a thickness greater than the implantation depth obtained with a given energy. More commonly, the implanted area is located at least in the protective layer.
• the ionically implanted zone may be located either in the protective layer only, or in the substrate only or shared between the protective layer and the substrate, that is to say in the region of the interface between the protective layer and the substrate.
• Figure 1 shows the coefficient of friction of a substrate on a ruby sphere, rolling on the substrate over a distance of 100m (abscissa). The first few centimeters of the curve correspond to a break-in and the establishment of regular conditions, and are not significant.
• Curve A is the reference curve, obtained for a substrate without ion implantation.
• Curve B is obtained for an identical substrate, implanted ionically with a dose of C ions of 2.10 17 ions / cm 2 , with an energy of 600keV.
• Curve C is obtained for an identical substrate, implanted ionically with a dose of C ions of 1.10 18 ions / cm 2 , with an energy of 600keV.
• Figure 2 shows the average coefficients of friction measured under conditions similar to those of Figure 1, except the energy which is in this case 35keV, depending on the implantation dose, and on different substrates. with a layer of S1O2 of different thickness, which explains the results not comparable directly.
• the effects obtained with a dose of 5.10 17 ions / cm 2 are already interesting.
• the values of the curve in are treated as extrapolations.
• nitrogen ions can be implanted in the protective layer, in the substrate, or in the region of the interface between the substrate and the protective layer, predominantly in the substrate, or only in the substrate if the energy is sufficient.
• ionically implanted components as proposed above, to produce components subject to repeated or significant shocks or friction, in particular the components of the escapement, in particular an anchor, an anchor wheel or part of a resonator undergoing friction, such as a plateau pin.
• ions could be implanted in order to achieve the desired effect, including ions included in the list comprising boron, argon, oxygen, carbon dioxide, fluorine, phosphorus, sulfur, neon or metal ions such as aluminum and some noble metals such as palladium, silver, gold, etc.
• the invention also relates to a watch movement comprising one or more of these components.
• the performance of a watch movement thus equipped will be improved and its power reserve, for a given barrel, increased.
• the invention also relates to the method for implanting the components described above, also defining a method for optimizing the tribological properties of a watch component as mentioned above, made based on a substrate comprising a silicon layer 10 whose crystallographic structure comprises at least one of the monocrystalline, polycrystalline or amorphous forms, said substrate being reinforced by a protective layer 12 formed on its surface during a protective operation of the substrate.
• the method comprises a step of ion implantation of at least one ion, by ion bombardment on the surface of said component.
• the implantation step may be performed with C ions at a dose greater than 5.10 17 ions / cm 2 , preferably greater than 1.10 18 ions / cm 2 and with an energy greater than 600keV, or with N ions, at a dose greater than 1.10 16 ions / cm 2 and with an energy higher than 600keV.
• Implantation is performed on the components when, after etching, they have been detached from the base wafer in which they are etched.
• the areas of the components that are relevant to treat the tribological level are the side faces that, in general in the watch industry, are those that are exposed to friction.
• the side faces are not yet defined and therefore not accessible either to perform the protection operation, fundamental in the present application.
• the components it is nevertheless possible for the components to remain integral with the wafer or part of the wafer, at least at one point, to allow batch manipulation of the components, the components being easily separable from the support. formed by the wafer, for example by breaking the junction between the wafer and the component, after the latter has undergone the protection and ion implantation operations.
• the side flanks of the components can pass anywhere in the crystallographic mesh.
• the ion implantation is directional and the ion bombardment may have a variable angle of incidence on the lateral faces of the component, a tribological improvement is obtained which is averaged over the entire lateral surface. of the component and that is significant. Therefore, the method proposed in this application is applicable with substrates of any crystallographic orientation, since at the side surfaces the part can take any crystallographic orientation.

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• 2017
  • 2017-12-04 WO PCT/EP2017/081407 patent/WO2018104247A1/fr active Application Filing
  • 2017-12-04 EP EP17808909.0A patent/EP3548972B1/de active Active

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