Item with a marking and method for producing the marking

Abstract

A substrate with a marking consisting of microscopic metallurgical structures (3) randomly arranged on the substrate's surface, each exhibiting at least one physical and / or chemical property that differs from the rest of the substrate. At least one structure comprises an element where exposure to radiation, an external electric or magnetic field, chemical attack, or mechanical, thermal, or electrical stress causes a temporary or permanent change in at least one physical or chemical property of the structure. The structures may consist of a first alloy (31) and a second alloy (32) that differ from each other. Alloy 31 permanently and stably changes color upon exposure to laser radiation, while alloy 32 exhibits high reflectivity and is therefore stable against laser exposure.

Description

[0001] The present invention relates to an object comprising a metal substrate and at least one marking on the metal substrate, the marking consisting of randomly arranged microscopic metallurgical structures. The present invention also relates to a method for producing such a marking on the substrate of an object.

[0002] Numerous industries use markings on their products to ensure authenticity and traceability. Thanks to modern micro-machining techniques, it is possible to mark a product without altering it. Traceability is particularly important in the medical field or for spare parts, while in luxury industries such as watchmaking or jewelry, authenticity must be guaranteed. The marking must therefore be robust, difficult to reproduce, discreet or even aesthetically pleasing, but also easily legible.

[0003] Most known micromachining marking techniques allow the creation of markings whose properties (pattern, color, etc.) are fixed once the marking is produced. In the field of securities (banknotes), it is common to use optical devices to create markings whose properties (pattern, color, etc.) change depending on the viewing angle. It would be interesting to use micromachining techniques to create markings on metal substrates whose properties continue to change even after processing.

[0004] The present invention therefore aims to offer an alternative to existing markings by providing a marking that can be applied to a metal substrate for aesthetic reasons or for the identification of an object, which is robust and allows for a wide variety of patterns and functional or physical properties that are not fully determined after processing the marking.

[0005] The present invention relates to an object according to claim 1, a method for marking an object according to claim 7 or a method for identifying an object according to claim 8.

[0006] The accompanying figures illustrate an object according to the invention. Fig. Figure 1a shows a cross-section of the substrate of an object before the application of a marking according to the invention. Fig. 1b shows the substrate made of Fig. 1a after applying a marking according to the invention. Fig. 1c shows the substrate made of Fig. 1b, which was exposed to radiation, in particular laser radiation. Fig. 1d shows the object and the marking from Fig. 1b after irradiation. Fig. Figure 2 shows an example of a random pattern that appears in part of the marking. Fig. 1b was created.

[0007] In the following, the term "microscopic" describes anything smaller than 0.1 millimeters, and thus also includes anything in the micrometer or nanometer range or smaller. The term "structure" is used to emphasize that the type of marking considered in the present invention requires a specific chemical and / or physical transformation at the marked site of the metal substrate and the creation of a new element or structure that differs from the metal substrate.

[0008] The present invention relates in particular to an object comprising a metal substrate 1 on which a marking 2 is applied, consisting of microscopic metallurgical structures 3 which are randomly arranged on the surface of the metal substrate 1. Fig. Figure 2 illustrates the random distribution of microscopic metallurgical structures on a portion of the marking 2. The object can be of any type: a finished product onto which the marking is applied directly, or a carrier that carries the marking and is subsequently attached to a product. The present invention is particularly suitable for objects such as watches, watch parts, jewelry, medical or dental devices or instruments, especially prostheses or implants, tools, automotive or aerospace spare parts, etc.

[0009] The marking and, in particular, its metallurgical structures 3 exhibit physical (optical, magnetic, etc.) and / or chemical properties that differ from those of the metal substrate 1.

[0010] Preferably, the marking 2 is produced by a surface treatment process as described in publication WO2008 / 010044. Electrical discharges are applied between a metal tip, serving as the anode, and the surface of the metal substrate 1, serving as the cathode (or vice versa). A gap of a few micrometers separates the tip from the substrate and is completely filled with a composite dielectric. The microdischarge occurring in the dielectric forms a conductive channel of ionized plasma between the tip and the substrate. An electric current, originating from the discharge of a power source, can flow through the ionized plasma. The energy supplied in this way contributes to the formation of a confined microplasma with very high temperatures and pressures. The mass of the plasma, which is surrounded by a gas sheath or gas bubble, increases during the discharge.The radial expansion of the plasma is severely restricted by the presence of the dielectric, and the discharge energy is concentrated in a very small volume. The ultra-hot plasma radiates energy to the electrode surface, melting the substrate metal. The plasma mass consists of molecules of the composite dielectric, which have been atomized and dissociated by the discharge energy. The high temperature of the plasma melts a disc-shaped surface of the substrate. However, the high plasma pressure limits the vaporization of the molten material from the electrodes. This mechanism leads to the formation of nearly circular imprints of molten metal at the roots of the arc. The size of the molten metal disc is a direct function of the discharge duration.These quasi-circular imprints form microscopic metallurgical structures, alloys of the metal substrate and the components of the composite dielectric, which were sputtered by the discharge. These microscopic metallurgical structures are distributed completely randomly on the surface of the metal substrate, as shown in [reference]. Fig. Figure 2 illustrates this. Once the arc is established, the tip can be moved in the plane to create elongated markings, lines, or other more complex paths without interrupting the current, similar to a micro-welding torch. By controlling the discharge energy, duration, breakdown distance and / or gap, and, most importantly, the chemical composition of the dielectric and its additives, the discharge plasma is used as a microreactor to generate markings consisting of microscopic structures of molten metal with a different chemical composition than the underlying metal substrate.

[0011] Alternatively, any suitable method could be used to create a mark 2 on a portion of the surface of the metal substrate of an object, consisting of microscopic metallurgical structures 3 randomly distributed across the surface of the metal substrate 1. For example, the mark on a metal substrate could be created by heating the substrate to a temperature just below its melting point and then bombarding it with a high-velocity gas stream containing solid particles, which are then implanted into the quasi-molten surface of the substrate to form microscopic metallurgical structures randomly distributed across the surface of the metal substrate. Furthermore, other methods such as plasma beaming, plasma coating, or additive manufacturing are also conceivable.

[0012] With both of the methods mentioned above, regardless of whether particles A, B, C... are introduced into the dielectric or the gas stream, it is not possible to predict which microscopic metallurgical structures will form, where they will be located, and in what proportions. In particular, it is not possible to determine in advance that at a specific location within the marking, the microscopic metallurgical structure will contain element A, B, or C... . The distribution of the types of microscopic metallurgical structures and their dispersion are therefore entirely random.

[0013] The marking 2 thus generated already constitutes a very robust identification device in view of the random nature of the scattering of the microscopic metallurgical structures 3 of which it consists: It is possible to identify a specific part of the marking 2, such as the one in Fig. 2. The square shown is to be examined and the unique pattern of microscopic metallurgical structures observed in this part is to be assigned to the object in order to enable future comparison and reliable identification.

[0014] Furthermore, due to its shape and direction, but also due to its composition, which can give it interesting properties, especially with regard to color, the marking 2 can have an aesthetic character depending on the elements added to the metal substrate during the creation of the marking 2.

[0015] The present invention goes further in that the marking 2 formed on the metal substrate 1 contains at least one alloy that differs from that of the metal substrate 1 and that has at least one physical or chemical property that can be temporarily or permanently altered by exposure to radiation, by applying an external field, by chemical attack, or by electrical or mechanical stress. Irradiation is understood to mean laser, UV, or infrared radiation. An external field is understood to mean either a magnetic field or an electric field. Electrical stress is understood to mean the direct application of an electric current to the metal substrate 1. Mechanical stress is understood to mean any mechanical stress applied to the substrate, such as tension, torsion, pressure, or temperature.

[0016] In the example of the Fig. 1a to 1d, a marking 2 is therefore produced on the metal substrate 1 by a suitable method. Preferably, the method described in publication WO2008 / 010044 is used: For this purpose, at least two different elements are selected and added to the dielectric material applied to the metal substrate 1. A micro-discharge is generated in the dielectric between the tip and the substrate, forming a channel of ionized, conductive plasma. An electric current originating from the discharge of a power source can flow through the ionized plasma. Quasi-circular imprints of molten metal are formed at the roots of the arc. In this way, a marking 2 is produced, consisting of microscopic metallurgical structures 3, which are alloys formed from the metal substrate 1 and a mixture of the different elements added to the dielectric material.A wide variety of alloys can be produced depending on the ratios between the individual components (substrate and dielectric elements). For simplification, it is assumed that at least one first alloy 31 and a second alloy 32 with different physical properties are produced under the microscopic metallurgical structures 3, in particular with different behaviors when exposed to laser radiation (thermal reactivity, reflectivity, optical absorption capacity, etc.). In this example, alloy 31 changes its color permanently and stably after exposure to laser radiation, while alloy 32 has a high reflectivity and is therefore stable against laser radiation. Thus, if the marker 2 is exposed to laser radiation 4, as in . Fig. As shown in 1c, the microscopic metallurgical structures containing alloy 31 change their color (as in Fig.1d shown). This creates a new, completely random color pattern, since the microscopic metallurgical structures consisting of alloy 31 are randomly distributed during the production of marking 2.

[0017] In this application using laser radiation, the marking method employed can be designed to produce a mark 2 whose components are highly reflective compounds such as aluminum, copper, silver, or ZrN compounds: These compounds therefore do not change color after exposure to laser radiation. They are combined with non-stoichiometric and heat-sensitive compounds (TiNx) that do change color after exposure to laser radiation. By combining these two types of components to form the mark 2 (e.g., by incorporating them into a dielectric before carrying out the method according to WO2008 / 010044), it is possible to generate a random color pattern after laser irradiation through selective absorption of the laser energy.

[0018] In an application for object identification, for example, a mark 2 is first applied to the object's metal substrate. This mark consists of randomly arranged microscopic metallurgical structures, each containing at least one laser-sensitive element. Subsequently, the metal substrate 1 is laser-engraved at the location of the mark 2 to create a final QR code with completely random coloring, providing a higher level of security and traceability.

[0019] In another example, the marking 2 could be a decorative pattern consisting of numerous microscopic metallurgical structures randomly arranged within the pattern. At least one of these structures would contain a laser-sensitive compound that changes color upon laser irradiation. The decorative pattern would then become unique after laser exposure due to its completely random color distribution. Depending on the method used, alloys with varying laser sensitivities could be incorporated into the marking 2 according to a specific pattern and / or in different proportions to create truly unique decorative designs. This aspect is particularly interesting in the fields of jewelry and watchmaking.It is particularly possible to create complex and unique decorative patterns that can also serve to identify the object. These patterns are produced through micro-machining processes that do not alter the object beyond the marking and, in particular, do not change its mechanical properties. Thus, it is possible to decorate or mark all types of watch or jewelry components, even the most delicate and precise.

[0020] In the example above, the components of the microscopic metallurgical structures 3 of the label 2 are selected based on their reaction to laser radiation and, in particular, on their color, which changes or does not change after exposure to laser radiation.

[0021] In another example, the mark 2 comprises microscopic metallurgical structures 3, the components of which were selected based on their reactivity to an external electric or magnetic field. By exposing the mark 2 to such an external magnetic field, for example, it is possible to induce selective magnetization of certain microscopic metallurgical structures 3 to create a random mosaic of magnetized regions within the mark 2. This mosaic mark can then be read with suitable equipment to identify, track, or authenticate the mark and the object bearing it.

[0022] In another case, the application of an external electric field can induce electrical polarization in specific grains or regions. This makes it possible to develop surfaces with special functional properties (photosensitive, piezoelectric, or magnetoactive surfaces that can be used in actuator-type devices).

[0023] In the examples above, the changes in the mark 2 caused by irradiation or an external field are permanent, and a new mosaic mark is obtained after irradiation. In other variations, the changes could be temporary, particularly for the duration of reading or viewing the mark 2. For example, the mark could consist of microscopic metallurgical structures whose components are metals or alloys with highly diverse optical properties (reflectivity, absorbance, etc.). In this case, it is possible to temporarily generate a new random mosaic by irradiating the mark 2 and its randomly arranged microscopic metallurgical structures with UV or infrared radiation, thus enabling the identification or authentication of the marked object.An object with such a marking can then be identified using a UV lamp by examining the mosaic made visible by the UV radiation.

[0024] In yet another example, a new mosaic is created after the chemical attack of the first marker. For instance, a marker made of tungsten and aluminum is formed. By chemically attacking this marker with hydrochloric acid, a new porous, tungsten-based mosaic is created on the metal surface of the substrate.

[0025] Finally, in further examples, either an electric current is passed through the substrate or a mechanical or thermal stress is applied to induce a temporary or permanent physical and / or chemical change in the microscopic metallurgical structures of the first mark 2, thus creating a new mark. For example, if microscopic metallurgical structures are formed during the formation of the first mark 2, which are shape memory alloys (Ni-Ti, Cu-Zn-Al alloys, etc.), the roughness of the surface of the first mark changes when a mechanical stress is applied that leads to a temperature change. Thus, by heating the surface of the first mark 2, which exhibits microscopic metallurgical structures made of a shape memory alloy, an imprint could become visible.In this way, it is possible to control the properties of the surface of the first marking, such as its wettability, in real time. More generally, this enables the construction of a surface with a controllable and reversible morphology.

[0026] It should be noted that during reactive post-treatment (such as acid attack), one or more of the microscopic metallurgical structures may become non-metallic. Selective CVD treatment of a particular material can lead to this result. This would also be the case with a mosaic of structures made of gold or platinum and another metal subjected to a strong oxidizing treatment.

[0027] As shown above, the initial marking on the metal substrate consists of randomly arranged microscopic metallurgical structures. This random arrangement also makes the final marking, after treatment by irradiation, chemical attack, or magnetic or electric field, random. However, it is possible to control and modulate the structure of the marking at the macroscopic level. This modulation results from the controlled dosage of the ratios between the component(s) introduced into the metal substrate to form microscopic metallurgical structures whose physical (optical, magnetic, etc.) and / or chemical properties differ from those of the substrate. Specifically, it is possible to control the proportions of the elements introduced into the substrate during the preparation of the marking (preparation of the composite dielectric or gas flow).

[0028] For example, the macroscopic reflectivity of the marking after laser irradiation can be modulated by adjusting the ratio between reflective particles A and less reflective particles B. The same applies to the magnetic or piezoelectric response of the marking: this response can be attenuated / modulated by combining magnetic or piezoelectric elements with neutral elements during marking formation. It is also possible to adjust the thermal expansion (similar to borosilicate glass).

[0029] It is also possible to combine several components to form microscopic metallurgical structures with different reactions to radiation or electric / magnetic fields: This allows the production of hybrid mosaics with different magnetic / piezoelectric, superconducting / metallic properties, etc.

[0030] Regarding color, certain color adjustments are possible by varying the proportion of specific components during the marking process: For example, if the 100% TiN alloy produces an intense blue color after laser processing, adding a neutral reagent such as tungsten carbide WC (which tends towards a silvery-gray hue after laser processing) can create a color palette ranging from intense blue to sky blue. Macroscopically, this results in the impression of pointillism.

[0031] Furthermore, it should be noted that the initial marking on the metal substrate can be so small that it can be hidden in a secret location on the substrate or object, or discreetly applied to small objects. Due to the small size of the microscopic metallurgical structures, it is therefore possible to conceal the initial marking within another, highly visible (macroscopic) identification element to provide additional protection.

[0032] The applications of the present invention are diverse. The marking according to the invention can serve aesthetic, technical, and functional purposes, and can be used as decoration or as an identification and security device.

[0033] In the medical field, for example, it is possible to apply a marking to an instrument or device by combining copper- or silver-based alloys with high reflectivity to laser radiation and other alloys with higher sensitivity to laser radiation. Copper and silver also possess strong antibacterial, antimicrobial, and antiviral properties. Therefore, a marking containing a copper compound is a particularly suitable location for laser-engraving instrument identification information. This is because dirt often accumulates in areas where laser engraving is performed.By creating a copper-containing mark that is subsequently engraved, two antibacterial mechanisms are combined, potentially multiplying the antibacterial effect: firstly, the ionic effect, in which OH ions are generated through contact between the copper surface and water, and secondly, a purely mechanical effect, since the spikes created after engraving the mark surface cause the cell wall of the bacteria to rupture. Finally, particularly using the method according to WO2008 / 010044, a mark 2 can be formed on the metal substrate of a medical instrument whose microscopic metallurgical structures include as components an antibacterial element such as copper and another element more attractive to bacteria, such as titanium.Since the “attractive” or “antibacterial” microscopic metallurgical structures are infinitely close together, a “trap” for bacteria is formed at the point of label 2.

[0034] The invention thus makes it possible to create a marking for a medical instrument or medical device that is both robust, since the distribution of the microscopic metallurgical structures and their change after the passage of the laser are completely random and non-reproducible, and is realized on an antibacterial and biocompatible surface.

[0035] In general, the present invention relates to an object comprising a metal substrate and, on this metal substrate, a marking consisting of microscopic metallurgical structures randomly arranged on the surface of the metal substrate. The microscopic metallurgical structures exhibit different physical and / or chemical properties than the rest of the metal substrate. According to the invention, at least one microscopic metallurgical structure comprises a component that is distinct from the metal substrate and such that the action of radiation or an external electric or magnetic field or a mechanical, thermal, or electrical stress on the marking causes at least a temporary or permanent change in at least one physical or chemical property of the at least one microscopic structure.

[0036] Change is understood to mean a change in a physical or chemical property of a microscopic metallurgical structure without destruction of the structure or the substrate, such as a change in color, polarization, roughness, wettability, etc.

[0037] Preferably, the radiation is laser, UV, or infrared radiation. Preferably, the action of the radiation or the external field causes a temporary or permanent change in the color, electrical polarization, or magnetization of the at least one metallurgical microscopic structure.

[0038] Preferably, the marking forms part or all of a decorative pattern or a device for identifying the object.

[0039] The present invention also relates to a method for marking an object for decorative purposes or for identifying the object, comprising the following steps: • Providing an item that includes a metal substrate; • Selecting at least one reactive element that differs from those of which the metal substrate is composed, wherein the reactive element is selected due to its particular reactivity to at least one first treatment, such as exposure to radiation or an external electric or magnetic field, or chemical attack, or mechanical, thermal or electrical stress; • Generating a first mark on the metal substrate consisting of microscopic metallurgical structures randomly arranged on the surface of the metal substrate and exhibiting at least one physical and / or chemical property that differs from that of the metal substrate, wherein at least one of the microscopic metallurgical structures includes the at least one reactive element as a component; • Applying the first treatment to the first label to cause a permanent or temporary change in at least one physical or chemical property of the at least one microscopic structure, in order to produce a second label that differs from the first.

[0040] This method can be used to create random mosaics of colors, magnetization, and electrical polarization, as in the examples above.

[0041] The present invention also relates to a method for identifying an object, comprising the following steps: • Providing an item that includes a metal substrate; • Selecting at least one reactive element that differs from those of which the metal substrate is composed, wherein the reactive element is selected due to its particular reactivity to at least one first treatment, such as exposure to radiation or an external electric or magnetic field, or chemical attack, or mechanical, thermal or electrical stress; • Generating a first mark on the metal substrate consisting of microscopic metallurgical structures randomly arranged on the surface of the metal substrate and exhibiting at least one physical and / or chemical property that differs from that of the metal substrate, wherein at least one of the microscopic metallurgical structures includes the at least one reactive element as a component; • Applying the first treatment to the first label to cause a permanent or temporary change in at least one physical or chemical property of the at least one microscopic structure, in order to produce a second label that differs from the first; • Reading / observing / recognizing the second marking and assigning it to the object for its identification.

[0042] Thus, the present invention enables the marking of an object for aesthetic or identification purposes and offers a wide variety of results regarding the properties of the final mark (color, functional properties, magnetization, polarization, etc.). This variety and the random nature of the generated result are advantages in the field of object identification, authentication, and traceability: In fact, the marks according to the invention are robust and non-reproducible. Moreover, in certain embodiments, particularly when using UV radiation, the mark is very easily legible by simple means, so that the object can be clearly and easily identified (identification of a luxury item directly by a reseller without the need for special tools or costly procedures).

[0043] As stated above, the invention relates to any object comprising a metal substrate onto which a marking can be applied, the marking consisting of microscopic metallurgical structures randomly arranged on the surface of the metal substrate and exhibiting at least one physical and / or chemical property that differs from that of the substrate. In particular, the object may be a watch component, a piece of jewelry, a medical or dental device, a spare part, or a component for the automotive or aerospace industries. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] WO 2008 / 010044 [0010, 0016, 0017, 0033]

Claims

[1] An object comprising a metal substrate and on that metal substrate a marking consisting of microscopic metallurgical structures randomly arranged on the surface of the metal substrate, wherein the structures comprise at least one component different from those of which the metal substrate is composed, and wherein the structures have at least one physical and / or chemical property different from the rest of the metal substrate, characterized by, that at least one of the microscopic metallurgical structures comprises a reactive component such that the action of radiation or an external electric or magnetic field or chemical attack or mechanical, thermal or electrical stress on the first marking causes at least a temporary or permanent change in at least one physical or chemical property of the at least one microscopic metallurgical structure. [2] Subject matter according to claim 1, characterized by that the radiation is laser, UV or infrared radiation. [3] Subject matter according to claim 2, characterized by , that the temporary or permanent change of at least one physical or chemical property of the at least one microscopic metallurgical structure is a color change of the at least one microscopic metallurgical structure. [4] Subject matter according to claim 1, characterized by , that at least one of the microscopic metallurgical structures comprises a reactive component such that the action of an external electric or magnetic field on the marking causes a change in the electric polarization or a magnetization of the at least one microscopic metallurgical structure. [5] Subject matter according to claim 1, characterized by , that at least one of the microscopic metallurgical structures comprises a reactive component, such that the microscopic metallurgical structure is a shape memory alloy, such that the application of a mechanical, thermal or electrical stress to the marking causes a change in the roughness or wettability of the at least one microscopic metallurgical structure. [6] Subject matter according to any of the foregoing claims, characterized bythat the marking forms part or all of a decorative pattern or a device for identifying the object. [7] Method for producing a permanent or temporary mark on an object for decorative purposes or for identifying the object, comprising the following steps: ◯ Providing an item that includes a metal substrate; ◯ Selecting at least one reactive element that differs from those of which the metal substrate is composed, wherein the reactive element is selected due to its particular reactivity to at least one first treatment, such as exposure to radiation or an external electric or magnetic field, or chemical attack, or mechanical, thermal or electrical stress; ◯ Applying a first mark to the metal substrate, wherein the first mark consists of microscopic metallurgical structures randomly arranged on the surface of the metal substrate and exhibiting at least one physical and / or chemical property that differs from that of the substrate, wherein at least one of these structures contains the at least one reactive element as a component; ◯ Action of the first treatment on the first marking to cause a temporary or permanent change in the at least one microscopic metallurgical structure comprising the reactive element to produce a second temporary or permanent marking that differs from the first. [8] A method for identifying an object comprising the following steps: ◯ Providing an item that includes a metal substrate; ◯ Selecting at least one reactive element that differs from those of which the metal substrate is composed, wherein the reactive element is selected due to its particular reactivity to at least one first treatment, such as exposure to radiation or an external electric or magnetic field, or chemical attack, or mechanical, thermal or electrical stress; ◯ Applying a first mark to the metal substrate, such that the first mark consists of microscopic metallurgical structures randomly arranged on the surface of the metal substrate and exhibiting at least one physical and / or chemical property that differs from that of the substrate, wherein at least one of the structures includes the at least one reactive element as a component; ◯ Action of the first treatment on the first marking to cause a temporary or permanent change in the at least one microscopic metallurgical structure comprising the reactive element in order to produce a second temporary or permanent marking that differs from the first; ◯ Reading / observing / recognizing the second marking and assigning it to the object to identify the object.

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