Method for manufacturing a ceramic component

Abstract

The present invention relates to a method for producing a technical ceramic component (10), which method in particular comprises the steps of: i) placing in a mold at least one composition (p1; p1, p2; p1, p2, p3) of ceramic powder containing at least one metal oxide; ii) carrying out an SPS sintering cycle to obtain a blank (12) of a ceramic component (12) having at least one gray shade (n1; n1, n2; n1, n2, n3) on the surface of the component; and iii) machining the blank (12) to obtain a blank (14) of predetermined shape. Step iii) is followed by an additional step iv) of carrying out an oxidation operation on the blank (14) of predetermined shape, so that at least on the surface of a first portion of the ceramic component (10) there appears at least one color (c1; c1, c2; c1, c2, c3) resulting from the oxidation of the at least one metal oxide, and the surface of a second portion of the ceramic component (10) exhibits the at least one gray shade.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing technical ceramic components, in particular decorative components in the field of horology or jewellery, which method comprises, among other steps, an oxidation operation that makes it possible to manufacture ceramic components with a greater variety of aesthetic effects, without compromising their mechanical properties. [Background technology]

[0002] In the field of horology, the mechanical performance of watch components, especially the watch middle case, is important to withstand unexpected shocks. However, ceramic materials have the disadvantage of being fragile due to their structure. There are various methods for producing ceramic-based components with improved mechanical performance.

[0003] Patent document CH718069 (Patent Document 1) discloses a method for producing ceramic decorative components that retains their original appearance while providing decorative components that are substantially homogeneous in terms of their structure and mechanical properties. The method includes the following steps: i) preparing a first base composition containing powders intended for a sintering operation to form a ceramic; ii) preparing a second base composition containing powders intended for a sintering operation to form a ceramic; iii) treating at least one of the first and second base compositions to incorporate at least one pigment and define respective first and second reactants prior to the sintering operation; iv) arranging the first and second reactants in a mold in the form of at least two at least partially adjacent layers to define an interface of a predetermined shape between them; and v) carrying out a sintering operation on the mold containing the first and second reactants.

[0004] The method further comprises at least one machining step of the ceramic product obtained after the sintering operation, which step comprises at least one material removal operation along a path that intersects said interface, so that at least a portion of the interface is visible on the surface of the decorative element, said element exhibiting a change in tone and / or color on its surface.

[0005] This method has the drawback of being complicated to implement, since it involves several steps, including the preparation of a powder containing a binder and a stabilizer, and a debinding step, which consequently significantly impacts the cost of the component being manufactured. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] CH718069 Summary of the Invention [Problem to be solved by the invention]

[0007] It is therefore an object of the present invention to provide a method for producing technical ceramic components, the implementation of which is simplified compared to the above-mentioned prior art.

[0008] Another object of the present invention is to provide a method for producing technical ceramic components with improved mechanical performance.

[0009] Another object of the invention is to provide a method for producing technical ceramic components, in particular watch case middles, which makes it possible to produce components with a wider range of aesthetic effects without compromising their mechanical properties.

[0010] A further object of the invention is to provide a method for manufacturing technical ceramic components, in particular watch middle cases, which includes a decoration step that does not involve the addition of new materials. [Means for solving the problem]

[0011] These objects are achieved, in particular, at least in part, by a method for producing an industrial ceramic component comprising the following steps: i) placing at least one ceramic powder composition containing at least one metal oxide into a mold; ii) carrying out an SPS sintering cycle to obtain a blank of a ceramic component in a reduced state having at least one shade of grey on the surface of said component; and iii) machining said blank to obtain a blank of predetermined shape, Step iii) is followed by a further step iv) of subjecting said blank of predetermined shape to an oxidation operation so as to reveal, at least on the surface of a first portion of said ceramic component, at least one color resulting from oxidation of said at least one metal oxide, and wherein the surface of a second portion of said ceramic component exhibits said at least one shade of gray.

[0012] According to one embodiment, step i) comprises placing in a mold first and second compositions each comprising a ceramic powder and a different metal oxide to obtain after step ii) first and second grey shades.

[0013] According to one embodiment, step i) comprises filling the mold with at least three compositions, each comprising a ceramic powder and a different metal oxide, in order to obtain three grey shades after step ii).

[0014] According to one embodiment, the oxidation operation in step iv) is carried out by means of a laser beam or a plasma jet, supplied with a flow of oxygen.

[0015] According to one embodiment, at least one of a laser beam and a plasma jet is used to create a pattern with a level of detail where the resolution depends on the effective diameter of the beam or plasma jet, respectively.

[0016] According to one embodiment, the oxidation operation includes performing oxidation on at least the surface of one or more selected discrete regions of the ceramic component.

[0017] According to one embodiment, oxidation of the selected one or more discrete regions of the ceramic component results in the formation of one or more predetermined shaped patterns that exhibit at least one color depending on the metal oxide contained in the oxidized region of the ceramic component.

[0018] According to one embodiment, the method further comprises, between steps iii) and iv), a surface treatment operation of at least one area of ​​the blank of predetermined shape to obtain at least one treated surface, the oxidation operation being carried out on one or more areas whose surface has been previously treated.

[0019] According to one embodiment, relative motion is effected between the plasma jet or the laser beam and the blank of predetermined shape while varying the distance between the plasma jet and the blank of predetermined shape or the power of the laser beam in order to vary the degree of oxidation in the first portion of the ceramic component so that this portion exhibits a color gradient.

[0020] According to one embodiment, the oxidation operation in step iv) is carried out by placing the blank of a predetermined shape in an oxygen or air furnace for a predetermined duration and temperature cycle, which are set so that oxidation occurs on at least a portion of the surface of the blank, obtaining a color according to the metal oxides present on the surface of the blank, and on the other hand oxidation occurs to a predetermined depth within the bulk of the blank. The oxidation operation is followed by an operation of selectively removing the oxide layer, so as to reveal at least one gray shade and / or color gradient.

[0021] According to one embodiment, the predetermined temperature cycle comprises a temperature increase cycle from about 20°C to a temperature between 800°C and 1200°C within a time period ranging from 3 to 5 hours. The temperature increase cycle is followed by a temperature decrease cycle to about 20°C for a time period ranging from 2h30 to 3h30, which makes it possible, on the one hand, to oxidize said at least part of the surface of the blank, obtaining a color according to the metal oxides present on the surface, and, on the other hand, to oxidize the material below the surface to a depth ranging from 50 to 300 micrometers.

[0022] According to one embodiment, the material is removed according to a predetermined pattern to a depth that exceeds the depth of the oxidized body of the blank, so as to reveal one or more grey shades.

[0023] According to one embodiment, the material is removed according to a predetermined pattern and variable depth along tracks within the oxidized body so as to reveal a color gradient.

[0024] According to one embodiment, the SPS sintering cycle is carried out at a temperature between 1100° C. and 1300° C. for a time ranging from 10 to 45 minutes.

[0025] Another aspect of the invention relates to a component for a watch or a piece of jewellery, in particular a watch middle case or a watch bezel, obtainable by the method described above. [Brief explanation of the drawings]

[0026] Examples of embodiments of the invention are set forth in the description illustrated by the accompanying drawings, in which: 1a to 1e show schematic views of a watch middle case during various stages of its manufacture according to one embodiment; 2a to 2e show schematic views of a watch middle case during various stages of its manufacture according to another embodiment. - Figures 3a to 3d show schematic views of a watch middle case during various stages of its manufacture according to another embodiment, and Figures 4a and 4b show two exemplary final decoration steps according to another embodiment. 5a to 5d show schematic views of a watch middle case during various stages of its manufacture according to another embodiment. 6a to 6e show schematic views of a watch middle case during various stages of its manufacture according to another embodiment. - Figure 7 is a schematic top view of the watch case middle from Figure 6e during the oxidation process, which produces a color gradient through the injection of oxygen plasma by a plasma jet using a nozzle. FIG. 8 is a graph showing the degree of oxidation of the watch middle case as a function of the distance between the nozzle and the watch middle case. FIG. 9 shows the middle case of the watch from FIG. 7, showing the color gradient in its central part as a function of the degree of oxidation and the distance between the nozzle and the central part of the middle case.

[0027] Examples of embodiments of the present invention The following description focuses on describing a method for manufacturing a technical ceramic component in the field of horology or jewelry, according to various embodiments selected as non-limiting examples. More specifically, the ceramic component manufactured by carrying out said method according to any of the embodiments described below is a watch middle case. Of course, those skilled in the art can apply the same method to manufacture other ceramic components without departing from the scope of the invention.

[0028] In the context of the present invention, the term "color" refers to a color other than a palette of gray shades. Color or color palette in the context of the present invention relates to the visual appearance imparted to the surface or visible portion of a ceramic component revealed by an oxidation operation. The palette of colors that can be obtained depends on the metal oxides present in the ceramic powder. Furthermore, the term "at least one shade of gray" refers to the visual appearance imparted to the surface of the ceramic component when the ceramic powder is subjected to an SPS sintering cycle to obtain a ceramic component blank in a reduced state without being subjected to an oxidation operation. A gray shade is one of the tones that appears to the human eye to be between white and black.

[0029] Generally, the manufacturing method for a watch middle case involves two steps common to the embodiments described below. The first step involves placing at least one composition of ceramic powder containing at least one metal oxide into a mold. This step is followed by a second step involving a flash sintering operation, or "electric field-assisted sintering / spark plasma sintering (FAST / SPS)." This operation, more commonly known as SPS sintering, is similar to hot isostatic pressing, but uses the Joule effect to heat a pre-compacted powder in a mold placed between two graphite electrodes in an inert atmosphere or under vacuum, and the mold containing the pre-compacted powder is subjected to a pressure of several megapascals under the action of a hydraulic press. A continuous or alternating current of several kiloamperes, pulsed or non-pulsed, is passed between the electrodes at a voltage of several volts.

[0030] The plasma during sintering ionizes the residual gases between the powder particles, producing negative ions that consume all of the oxygen from the metal oxides contained in the ceramic powder. Although the sintering operation is typically carried out under vacuum or in an inert atmosphere, this ionization of the residual gases thus creates a so-called reducing atmosphere within the plasma. This reducing atmosphere inevitably results in the resulting component being in a reduced state once the flash sintering operation is completed.

[0031] SPS sintering is carried out at a predetermined sintering temperature and pressure so as not to melt any of the powders. The sintering pressure can be a mechanical pressure in this case. Preferably, the sintering temperature is determined so as to remain below the lowest melting temperature of the powder under the sintering conditions. The appropriate sintering temperature can be evaluated based on the sintering pressure so as to avoid reaching or exceeding the melting temperature of the powder at the sintering pressure, or to remain below it.

[0032] According to one embodiment, the SPS sintering temperature is less than 2000° C., or less than 1500° C. For example, the SPS sintering temperature is between 1000° C. and 1300° C. for a time period of 10 to 45 minutes.

[0033] SPS sintering pressure is 20~180N / mm 2 or 50 to 100N / mm 2 Other pressure values ​​may be preferred depending on the components selected and / or the required quality of the final mechanical component.

[0034] The SPS sintering operation results in a sintered component that retains the fine grain size of the ceramic, which has the advantage over conventional sintering cycles of optimizing mechanical properties, particularly hardness and toughness. Because sintering is carried out in an inert atmosphere or under vacuum, the resulting sintered component is in a reduced state, and its shape is determined by the final shape of the component.

[0035] Taking the example of a watch middle case, the shape of the sintered blank is substantially cylindrical, has a diameter that can be in the range between 40 mm and 60 mm, for example a diameter of about 50 mm, and a thickness that is in the range between 15 mm and 20 mm, for example a thickness of 18 mm.

[0036] In a first embodiment, and with reference to Figures 1a to 1e, a method for producing a ceramic watch middle case 10 comprises a first step S1 which comprises placing in a mold (not shown) first and second compositions p1, p2, each comprising a ceramic powder, preferably zirconia, in particular yttrium-stabilized zirconia, and at least one different metal oxide (preferably selected from iron oxide, aluminum oxide, bismuth oxide and chromium oxide).

[0037] As shown in Figure 1a, the first and second compositions p1 and p2 are distributed in a mold without being mixed together. More specifically, the first and second compositions p1 and p2 are arranged adjacent to each other to form an interface therebetween and extend in a direction that may be substantially perpendicular to the bottom of the mold.

[0038] As shown in Figure lb, in a second step S2, an SPS sintering operation is performed to obtain a watch middle case blank 12 having on its surface two grey shades n1, n2 that meet at an interface that may be substantially perpendicular to the general central plane of the watch middle case 10. In a variant not shown, three, four or five or more different compositions are arranged side by side to obtain, after the SPS sintering operation, a watch middle case blank having a corresponding number or plurality of grey shades on its surface, so that their respective interface surfaces preferably extend substantially perpendicular to the general central plane of the watch middle case.

[0039] In another variant not shown, at least two different compositions, for example three, four, five or more compositions, are distributed in the mold to form a corresponding number or number of separate superimposed layers. A watch middle case blank is thus obtained after the SPS sintering operation, having two, three, four, five or more gray shades that meet at their respective interfaces, which may be substantially parallel. These interfaces may be essentially parallel or inclined relative to the general plane of the watch middle case.

[0040] Each composition p1, p2 may contain one or more different metal oxides (including, for example, iron oxide, aluminum oxide, cerium oxide, bismuth oxide, and chromium oxide). The two compositions p1, p2 may each occupy substantially equal volumes. Compositions p1, p2 are positioned relative to each other in the mold based on the desired locations of the different gray shades n1, n2 on the finished component. Compositions p1, p2 may also differ in their ceramic powders; for example, composition p1 may be based on zirconia and composition p2 may be based on alumina or another material.

[0041] Once the SPS sintering operation is complete, the method includes a third step S3, as shown in Figure 1c, which involves machining the blank 12 to obtain a blank 14 of predetermined shape, which generally corresponds to the final dimensions of the ceramic component, i.e., in this case, the shape of the watch middle case. Machining is carried out using conventional means, in particular milling and / or grinding.

[0042] The method may include a surface treatment step S4, as shown in FIG. 1d. This optional step involves decorating one or more areas of the surface of the component, in particular the side of the watch caseband, by mechanical and / or chemical operations. Mechanical operations may include polishing, sandblasting, linear, circular, or spiral satin finishing, microbeading, guilloche, circular graining, Côtes de Genève, or hand engraving. In this example, a machined blank 14 has been subjected to a surface treatment to provide one or more surfaces 16 with a decoration obtained by one of the aforementioned mechanical operations.

[0043] For components that include several regions separated from one another and that have undergone a surface treatment, the same type of treatment, for example sandblasting, may be applied to all regions, or in one variant the treatment may differ from one region to another, for example sandblasting for a first region, satin finishing for a second region, and polishing for a third region. According to another variant, these different regions may be adjacent.

[0044] The method includes a final step S5, which involves decorating the blank, as shown, for example, in FIG. 1e. This decoration step S5 involves performing an oxidation operation on at least a portion of the watch case middle, particularly on its side, so that the color of the metal oxide appears on the surface of the component. According to FIG. 1e, the oxidation operation involves selectively oxidizing the surface of the watch case middle 10, for example, to a depth of 50 micrometers, so that the shape of the oxidized surface matches the desired pattern. This operation triggers a chemical reaction initiated by oxygen coming into contact with the metal oxide(s) present on the surface of the component. This reaction allows the different oxides to reveal their vibrant colors. This final operation is therefore a chemical transformation of the material, unlike the method described in CH718069, in which the final step involves removing material using a CNC machine or laser.

[0045] The patterns 18a, 18b, 18c, represented in this example by three stars, exhibit different colors: the first star 18a exhibits a color specific to the metal oxide(s) present in the first composition p1, the second star 18b exhibits two distinct colors corresponding to the metal oxide(s) present in the first composition p1 and the second composition p2, respectively, while the third star 18c exhibits another color specific to the metal oxide(s) in the second composition p2.

[0046] As an example, compositions p1 and p2 can contain bismuth oxide and aluminum oxide, respectively, to obtain the blank shown in Figure 1b, where compositions p1 and p2 in their reduced state have dark and light gray shades, respectively. The dark and light gray shades can vary depending on the concentration of oxides in the two compositions. After the oxidation step shown in Figure 1e, the first pattern 18a has a homogeneous color c1 that tends toward blue with varying intensity depending on the concentration of bismuth oxide. The third pattern 18c has a color c3 that tends toward white with varying intensity depending on the concentration of aluminum oxide, while the second bicolor pattern has a combination of the two aforementioned colors.

[0047] The watch middle case 10 obtained according to this first embodiment therefore has two grey shades n1, n2 on its surface, together with different decorations 18a, 18b, 18c (represented in this example as stars, with vibrant colours depending on the oxide(s) present on the surface at the position of these stars). The stars 18 are preferably produced on the area 16 of the watch middle case that has been subjected to the surface treatment described above, in order to provide additional contrast to the decorations 18a, 18b, 18c. According to a variant not shown, the decoration can also be applied to an area of ​​the watch middle case that has not previously been subjected to the surface treatment.

[0048] The oxidation operation can be carried out, for example, using a laser source, in which localized heat allows the localized generation of an oxide layer. The laser source can be controlled so that the laser follows a predetermined path on the surface of the watch middle case 10, reproducing a pattern, for example a repeating pattern or even text.

[0049] According to a second embodiment and with reference to Figures 2a to 2e, the method for producing a ceramic component comprises a first step S1, which involves filling a mold (not shown) with a single composition p1 comprising one or more metal oxides, followed during a second step S2 by carrying out an SPS sintering operation, as described with reference to the first embodiment, to obtain a watch middle case blank 12 in the form of a disk in a reduced state. The visual appearance of the ceramic at this point exhibits only a single homogeneous grey shade n1, as shown in Figure 2b.

[0050] As in the first embodiment, the method includes a third step S3 which, once the sintering operation is complete, involves machining the watch middle case blank 12 to its final dimensions, as shown in FIG. 2c.

[0051] The operation of decorating the machined blank 14 consists in this embodiment of two steps: A preliminary step S4 involves carrying out an oxidation operation on at least a part of the surface of the blank, preferably the entire surface of the blank being oxidized.

[0052] To achieve this, the machined blank 14 is placed in a furnace under oxygen or air for a predetermined duration and temperature cycle, so that oxidation occurs on the surface of the component blank to obtain a color related to the type of metal oxide(s) present on the component surface, and also within the bulk of the component, i.e., at least to a certain depth where oxidation can no longer be considered part of the component's surface. Step S4 is a chemical transformation of the material, particularly at the surface of the blank. This step is distinct from the previous step S3, which involves machining the watch case middle blank 12 to its final dimensions. This contrasts with the method described in CH718069, where the final step involves removing material using a CNC machine or laser. The process involves a temperature increase cycle from approximately 20°C to a temperature between 800°C and 1200°C within a time period ranging from 3 to 5 hours, followed by a temperature decrease cycle to approximately 20°C within a time period ranging from 2.5 to 3.5 hours.

[0053] The predetermined temperature cycle typically comprises a temperature ramp-up cycle from about 20°C to a temperature between 800°C and 1200°C, preferably to about 1000°C, within a time period of 3 to 5 hours, preferably about 4 hours. The temperature ramp-up cycle is followed by a temperature ramp-down cycle to about 20°C, within a time period of 2.5 to 3.5 hours, preferably about 3 hours. This temperature cycle makes it possible, on the one hand, to oxidize the surface of the blank to obtain a single homogeneous color c1 related to the type of metal oxide(s) present on the surface of the blank, and, on the other hand, to oxidize the material below the surface, preferably to a depth of between 50 and 300 micrometers.

[0054] The oxidation operation is followed by step S5, the purpose of which is to selectively remove the entire thickness of the oxide layer on and near the surface of the component, according to one or more arbitrary decorative shapes (in this example, stars 18a, 18b, 18c), so as to reveal the ceramic in a reduced state beneath the oxide layer, corresponding to the grey shade n1.

[0055] Selective removal of the oxide layer can be accomplished, for example, by conventional machining or, for highly detailed patterns, by using a laser source as the machining tool.

[0056] The watch middle case 10 obtained by the method according to this embodiment therefore has an overall visual appearance including a substantially homogeneous surface that is brightly colored according to the metal oxide(s) on the surface of the component, as well as one or more decorations 18a, 18b, 18c in which a gray shade n1 appears (which correspond to the reduced ceramic below the surface).

[0057] According to a variant not shown, the depth of material removal varies along the trajectory through the thickness of the oxide layer so as to produce a color gradient corresponding to different degrees of oxidation of the oxide(s) present in composition p1.

[0058] According to a third embodiment, and with reference to Figures 3a to 3d, a method for producing a ceramic component comprises a first step S1, which comprises filling a mold (not shown) with three compositions p1, p2, p3, each comprising a ceramic powder, preferably zirconia, in particular yttrium-stabilized zirconia, and at least one different metal oxide. The three compositions p1, p2, p3 are distributed in the mold without being mixed. Each composition p1, p2, p3 may contain one or more different metal oxides.

[0059] According to the method described with reference to the first embodiment, an SPS sintering operation S2 is carried out to obtain a watch middle case blank 12 in a reduced state, as shown in Figure 3b. The SPS sintering operation results in three homogeneous grey shades n1, n2, n3 coming together at the two interfaces. As shown in Figure 3c, a machining operation S3 is carried out on the sintered component to obtain the final dimensions of a watch middle case blank 14 of predetermined shape.

[0060] Next, as shown in FIG. 3d, the entire surface of the blank 14 is subjected to an oxidation operation S4. The oxidation of the three gray-shade areas results in the appearance of three distinct vibrant colors c1, c2, and c3. As with the first two embodiments, step S4 is a chemical transformation of the material on the surface of the blank. This step is distinct from the previous step S3, which involves machining the watch case middle blank 12 to its final dimensions.

[0061] The oxidation operation is followed by operation S5, which involves selectively removing the oxide layer to form a decoration including one or more patterns. Figures 4a and 4b show a watch case middle 10 obtained by the method according to this embodiment, whose schematic surface has three distinct vibrant colors and two decorative examples. The case middle 10 shown in Figure 4a includes a decoration in the form of a groove 18 on its side, along which three shades of gray n1, n2, and n3 appear successively. The case middle 10 in Figure 4b has a decoration in the form of three distinct patterns on its side, for example, three stars 18a, 18b, and 18c, each appearing in three shades of gray n1, n2, and n3.

[0062] Figures 5a-5d show a fourth embodiment, in which the first three steps S1, S2, and S3 are identical to the first three steps of the previous embodiment. The surface of the blank 14 of predetermined shape, shown in Figure 5c, is subsequently selectively oxidized in step S4 according to one or more arbitrary patterns 18 to produce decoration within the region including three gray shades n1, n2, and n3. The oxidation allows the development of three vibrant colors c1, c2, and c3 specific to the type of metal oxide(s) present in the different compositions p1, p2, and p3. This chemical transformation of the material on the surface of the blank 14 also distinguishes it from the previous step S3, which involves machining the watch middle blank to its final dimensions.

[0063] The watch middle case 10 obtained by the method according to this embodiment has a general visual appearance including a surface bearing one or more decorations appearing in three shades of grey n1, n2, n3, as well as three vibrant colours c1, c2, c3.

[0064] According to another embodiment shown in Figures 6a-6e, the first three steps S1, S2, and S3 are identical to the first three steps of the method according to the second embodiment. The machining step S3 can be followed by an optional step S4, which involves performing a surface treatment, as described above, to obtain one or more surfaces with a specific finish on the side of the watch case middle. The machining step S3 or the surface treatment step S4 is followed by an oxidation step S5 on the central portion 20 of the watch case middle by injecting a stream of oxygen plasma. The resulting watch case middle 10 has an overall surface of bright color c1 and a gray shade n1 on the portion 22 containing the horn.

[0065] 7-9, the injection of the oxygen plasma stream is performed using a nozzle that generates the plasma jet 30. The watch middle case 10 or the plasma jet 30, particularly the nozzle from which the jet is emitted, can be moved to induce a relative movement of the plasma stream injection over the central portion 20 of the watch middle case. In an advantageous embodiment, the nozzle or middle case 10 can be moved to vary the distance between the plasma jet 30 and the watch middle case, more specifically the distance between the effective diameter of the essentially conical plasma jet and the watch middle case, and indeed the distance d between the nozzle and the middle case. This variation in distance allows for a variation in the degree of oxidation in the central portion 20, which in turn characterizes the color gradient, and, on the other hand, the gray shades in the horn 22.

[0066] Regardless of the intended embodiment, it should be noted that the use of a laser beam and / or plasma jet 30 to perform the oxidation operation can be used to obtain both selected or random patterns, as well as flat areas on the surface of the blank 14 of a predetermined shape. Such flat areas may consist of surfaces or zones that are either uniform, gradient, or mixed. The same applies to the aforementioned patterns, which can also be generated in whole or in part outside or inside these areas.

[0067] Although the method is primarily described with respect to the production of technical ceramic watch case middles, it can be applied to other ceramic components without departing from the invention as defined by the claims. The method can, for example, be applied to any type of horological component, in particular to components of a watch movement intended to be visible through a sapphire crystal from the back of the watch case, or to decorative components in both the horological and jewelry fields.

Claims

1. A method for manufacturing an industrial ceramic component (10) comprising the following steps: i) placing in a mold at least one composition of ceramic powder (p1; p1, p2; p1, p2, p3) comprising at least one metal oxide; ii) carrying out an SPS sintering cycle to obtain a ceramic component blank (12) having at least one grey shade (n1; n1, n2; n1, n2, n3) on the surface of the component; iii) machining said blank (12) to obtain a blank (14) of predetermined shape; In a method comprising: the method, characterized in that step iii) is followed by an additional step iv) of subjecting the blank (14) of predetermined shape to an oxidation operation so as to reveal, at least on the surface of a first portion of the ceramic component (10), at least one color (c1; c1, c2; c1, c2, c3) resulting from the oxidation of said at least one metal oxide, and the surface of a second portion of the ceramic component (10) exhibits said at least one grey shade.

2. 2. The method of claim 1, wherein step i) comprises placing in a mold first and second compositions (p1, p2), each comprising a ceramic powder and a different metal oxide, to obtain after step ii) first and second grey shades (n1, n2).

3. 2. The method of claim 1, wherein step i) comprises filling the mold with at least three compositions (p1, p2, p3), each comprising a ceramic powder and a different metal oxide, to obtain three grey shades (n1, n2, n3) after step ii).

4. The method according to any one of claims 1 to 3, wherein the oxidation operation in step iv) is carried out by means of a laser beam or a plasma jet (30) supplied with a flow of oxygen.

5. 5. The method of claim 4, wherein at least one of the laser beam and the plasma jet (30) is used to generate a pattern having a level of detail whose resolution depends on the beam diameter or the effective diameter of the plasma jet (30), respectively.

6. 6. The method of claim 4 or 5, wherein the oxidation operation comprises performing oxidation on the surface of at least one selected discrete area or areas of the ceramic component.

7. 7. The method of claim 6, wherein the oxidation of the selected one or more discrete regions of the ceramic component results in the formation of one or more predetermined shaped patterns (18) that exhibit at least one color (c1, c2, c3) depending on the metal oxide contained in the oxidized region of the ceramic component.

8. 8. The method according to claim 5, further comprising, between steps iii) and iv), a surface treatment operation on at least one region of said blank of predetermined shape (14) to obtain at least one treated surface (16), said oxidation operation being carried out on one or more regions (16) whose surface has been previously treated.

9. 5. The method of claim 4, further comprising varying the distance between the plasma jet (30) and the blank (14) of predetermined shape or varying the power of the laser beam while causing relative motion between the plasma jet (30) or the laser beam and the blank (14) of predetermined shape to vary the degree of oxidation in the first portion of the ceramic component so that the portion exhibits a color gradient.

10. 4. The method according to claim 1, wherein the oxidation operation in step iv) is carried out by placing the blank (14) of predetermined shape in an oxygen or air oven for a predetermined duration and temperature cycle, so that on the one hand oxidation occurs on at least a part of the surface of the blank (14) in order to obtain a color according to the metal oxides present on the surface of the blank (14), and on the other hand oxidation occurs to a predetermined depth within the body of the blank, the oxidation operation being followed by an operation of selectively removing oxide layers so as to reveal a gradient of at least one gray shade (n1, n2, n3) and / or color (c1, c2, c3).

11. 11. The method of claim 10, wherein the predetermined temperature cycle comprises a temperature increase cycle from about 20° C. to a temperature between 800° C. and 1200° C. within a time ranging from 3 to 5 hours, followed by a temperature decrease cycle to about 20° C. for a time ranging from 2 hours 30 minutes to 3 hours 30 minutes, in order, on the one hand, to oxidize said at least part of the surface of the blank (14) to obtain a color according to the metal oxides present on said surface, and, on the other hand, to oxidize the material below said surface to a depth ranging from 50 to 300 micrometers.

12. 12. A method according to claim 10 or 11, wherein the material is removed to a depth exceeding that of the oxidized body of the blank (14) according to a predetermined pattern so as to reveal one or more grey shades (n1, n2, n3).

13. 12. A method according to claim 10 or 11, wherein the material is removed according to a predetermined pattern and variable depth along a track within the oxidized body so as to reveal a color gradient (c1, c2, c3).

14. The method according to any one of claims 1 to 13, wherein the SPS sintering cycle is carried out at a temperature between 1100°C and 1300°C and for a time period ranging from 10 to 45 minutes.

15. A component for a watch or a piece of jewellery obtainable by the method according to any one of claims 1 to 14.

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