Multicolor ceramic parts and their manufacturing method

Abstract

This invention provides a novel manufacturing method that enables the production of multi-colored ceramic components. [Solution] A method for manufacturing a multi-colored, one-piece ceramic part is provided. The method comprises the steps of: preparing a plurality of ceramic powders or cermet powders having different compositions and / or colors from each other, wherein the ceramic powders or cermet powders consist only of ceramic elements, carbides, nitrides, oxides, or mixtures thereof; depositing the powders in a mold; and sintering at a temperature between 600°C and 1800°C and 5N / mm². 2 From 250 N / mm 2 The manufacturing method includes the steps of: performing flash sintering or discharge plasma sintering at a sintering pressure between 10 minutes and 180 minutes over a total cycle time between 10 minutes and 180 minutes to form a multi-color ceramic component; and demolding the obtained multi-color ceramic component and finishing the multi-color ceramic component. Preferably, the ceramic component is a watch component used as an exterior component or in a movement.

Description

Technical Field

[0001] The present invention relates to ceramic components. Specifically, the present invention relates to a watch component manufactured by spark plasma sintering (SPS) of a colored ceramic material to form a multi-colored integrated watch component.

Background Art

[0002] Watch components made of ceramic or cermet are generally manufactured using injection molding methods, or methods involving uniaxial or isostatic pressing of the material followed by sintering. These components often feature decorations such as indices and numbers on the dial or bezel, decorations of a different color from the rest of the component, or simply a two-color decoration throughout. The decorative elements on the bezel are generally added by inlaying or filling a sintered eboch (rough form). This mechanical assembly of the eboch and the decorative elements can be costly and complex to implement.

[0003] One alternative to this mechanical assembly is to manufacture the eboch by injecting materials of different colors, with the colors used to form the decoration being revealed after machining. However, manufacturing ceramic or cermet components of different colors is a complex process. For example, Patent Document 1 describes an injection molding process using ceramic powder combined with an organic binder. Such a method has the drawback of being complex to implement because it involves many steps, including the preparation of the powder containing the binder, which requires a debinding step, and one or more additional steps to obtain the desired final color.

[0004] Patent Document 2 also describes a method for obtaining a ceramic material with a color gradation and forming a dental prosthesis. However, such a method generally uses isostatic pressing, which is time-consuming and restrictive.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Patent No. 5991050 [Patent Document 2] European Patent Application Publication No. 2965713 [Overview of the project]

[0006] The present invention aims to overcome the aforementioned drawbacks by proposing a novel manufacturing method that makes it possible to obtain multi-color ceramic components.

[0007] For this purpose, the present invention relates to a method for manufacturing multicolor ceramic components.

[0008] Specifically, the method for manufacturing multi-colored components according to the present invention is: A step of preparing multiple ceramic powders or cermet powders, wherein the ceramic powders differ in composition and / or color from one another, and the powders consist only of ceramic elements, carbides, nitrides, oxides, or mixtures thereof. • The process of setting up a mold, • A process of depositing powder into a mold, The process involves performing flash sintering or discharge plasma sintering (SPS) cycles for a total cycle time of 10 to 180 minutes at a sintering temperature between 600°C and 1800°C and a sintering pressure between 5 N / mm² and 250 N / mm² to form multi-color ceramic components. • A process of demolding the obtained multi-colored parts, • The process of finishing multi-colored ceramic parts Includes.

[0009] The present invention also relates to multicolor ceramic components manufactured by the said manufacturing method.

[0010] According to other advantageous modifications of the present invention, Following the demolding process, a heat treatment such as stepwise annealing in air or a reactive gas is performed at a temperature between 550 and 1100°C for 30 minutes to 8 hours. The ceramic powder or cermet powder is selected from zirconium oxide powder, aluminum oxide powder, titanium nitride powder, silicon nitride powder, titanium carbide powder, tungsten carbide powder, or a mixture of at least two of these powders. One or more ceramic powders contain one or more distinct pigments that give the ceramics different colors. The pigment is cerium sulfide. The pigments are metal oxides, perovskites, or spinel. The pigments are selected from chromium oxide, cobalt oxide, iron oxide, titanium oxide, manganese oxide, molybdenum oxide, cerium oxide, vanadium oxide, zinc oxide, aluminum oxide, or mixtures of these oxides. • Cobalt / iron / chromium spinel or cobalt / aluminum spinel, The method includes a powder preparation step in which the powder is mixed, homogenized, or ground in an aqueous or alcoholic solution. The ceramic powder is atomized (spray-dried) after the powder preparation process. The powder is deposited in a mold by a selective powder deposition system to form multiple layers, and each deposited layer contains multiple powders. Before the mold filling process, a grid is placed inside the mold. The sintering process is carried out under vacuum, or in an inert or reactive atmosphere.

[0011] The present invention also relates to a one-piece ceramic component having a multi-colored appearance.

[0012] The component according to the present invention comprises several distinct ceramic materials that differ in composition and / or color, and more generally, in their aesthetic appearance. According to the present invention, the decorated component is multicolored and integral. [Brief explanation of the drawing]

[0013] Other features and advantages of the present invention will become apparent from reading the following detailed description, which is shown as a non-limiting example with reference to the accompanying drawings.

[0014] [Figure 1] It is a schematic diagram of the manufacturing method according to the present invention. [Figure 2a] It is a diagram showing an example of a multicolor ceramic part obtained by using the manufacturing method according to the present invention. [Figure 2b] It is a diagram showing an example of a multicolor ceramic part obtained by using the manufacturing method according to the present invention. [Figure 2c] It is a diagram showing an example of a multicolor ceramic part obtained by using the manufacturing method according to the present invention.

Mode for Carrying Out the Invention

[0015] The present invention relates to ceramic parts such as exterior parts in watches or jewelry, or watch parts having a large number of colors as a whole.

[0016] The method according to the present invention is schematically shown in FIG. 1. This method features an aggregate of various "raw" powders, such as juxtaposition and / or lamination, followed by a step in which all the powders are sintered.

[0017] In this specification, "raw" powder means a powder that does not contain a polymer binder.

[0018] The parts according to the present invention are made of ceramic. For example, it can be a ceramic made from zirconium oxide, aluminum oxide, titanium nitride, silicon nitride, or carbides such as titanium carbide or tungsten carbide, or a mixture of these ceramics.

[0019] Generally, "ceramic" refers to a ceramic base containing a stabilizer, an additive or a sintering aid, and optionally a pigment. For example, in the case of an oxide base such as ZrO2, Y2O3 can be added as a stabilizer, Al2O3 as an additive, and Fe2O3 as a pigment.

[0020] At least one of the ceramic powders contains at least one pigment for coloring the material. The pigment is a metal oxide, spinel, perovskite, or cerium sulfide, and the pigment is selected according to the desired color. Non-limiting examples include chromium oxide, cobalt oxide, iron oxide, titanium oxide, manganese oxide, zinc oxide, molybdenum oxide, cerium oxide, vanadium oxide, aluminum oxide, or mixtures of these oxides, such as iron oxide / chromium. For example, the pigment could be cobalt oxide for blue, chromium oxide for green, or iron oxide for brown.

[0021] The component according to the present invention may be a decorative component such as a component of a watch, jewelry, or bracelet. In the field of watches, this component may be an exterior component such as a middle case, case back, medallion (locket), bezel, bezel insert, push button, crown, bracelet links, clasp, buckle, dial, hands, dial indices, main plate, or bar. Furthermore, it may be an internal component of the movement, such as a rotor or main plate. Further examples include an emblem on the crown of a watch or an indice on the bezel.

[0022] The parts are manufactured by placing various powders into a mold and then performing flash sintering or SPS (discharge plasma sintering) to form ceramic parts with a multi-colored appearance.

[0023] The manufacturing method includes the following steps, as shown in Figure 1. A process for preparing multiple ceramic powders or cermet powders, wherein the ceramic powders or cermet powders differ from each other in composition and / or color, and the powders consist only of carbides, nitrides, oxides, or mixtures thereof. • A step of providing a mold designed to hold ceramic powder, A process of filling a mold with ceramic powder according to a desired pattern and color, wherein the height of the deposited mixed material does not exceed the height of the mold. • A process of performing flash sintering or SPS, • A process to release the obtained ceramic parts from the mold. This is the process of finishing the multi-colored ceramic component 1.

[0024] Optionally, after the demolding process, a stepwise annealing in air can be performed at a temperature between 550 and 1100°C for 30 minutes to 8 hours to remove the graphite covering the ébauche.

[0025] Multiple layers of mixed ceramic materials can be stacked or juxtaposed to form a specific color pattern visible from the side of the component.

[0026] According to one embodiment of the present invention, a grid or shablon (template) is placed inside the mold before the mold filling process. The grid or shablon is used to partition the mold and create a pattern during filling, which persists after sintering. The grid or shablon is removed before the sintering process.

[0027] According to another embodiment, powder is deposited in a mold by a selective powder deposition system to form multiple layers, each deposited layer containing multiple powders.

[0028] The ceramic powder consists solely of carbides, nitrides, oxides, or mixtures of these elements, and does not contain polymer binders.

[0029] In the powder preparation process, the powder is mixed, homogenized, or pulverized in an aqueous or alcoholic solution. Homogenization (or pulverization) is generally performed using an attritor or ball mill. Preferably, an aqueous solution is used if the ceramic powder contains a metal oxide pigment, and an alcoholic solution is used if it is a cermet.

[0030] After homogenization, the powder is atomized or dried. Atomization forms particle spheres containing various components of the ceramic powder, making it possible to obtain a highly homogeneous powder.

[0031] This method includes step d) in which the powder assembly undergoes flash sintering (or SPS) to produce a multicolor ceramic component corresponding to the final part. Temperature and pressure conditions can be adapted according to the type of powder and / or the final characteristics expected of part 1.

[0032] According to one embodiment, the sintering process is carried out at a temperature between 600°C and 1800°C in a vacuum.

[0033] The sintering process also involves a mechanical pressure between 5 N / mm² and 250 N / mm². The mechanical pressure may be constant, or it may have controlled variations such as various thresholds or ramps (gradients) where the value increases or decreases.

[0034] The entire sintering cycle is carried out within a time range of 10 to 180 minutes. The sintering cycle is defined as heating, holding, and cooling.

[0035] The temperature typically reaches the sintering temperature at a rate of 50°C to 500°C per minute.

[0036] Once sintering is complete, step e) consists of demolding the resulting multi-colored parts, as the colors appear immediately after sintering.

[0037] Optionally, after the demolding process, a heat treatment such as stepwise annealing in air or a reactive gas at a temperature between 550 and 1100°C for 30 minutes to 8 hours may be performed.

[0038] If necessary for those skilled in the art, the parts can be machined after sintering to correct their dimensions.

[0039] After any dimensional adjustments, the manufacturing method includes step f) finishing the part. The finishing step may involve one or more methods such as satin finish, polishing, guilloché (engine turning), Côtes de Genève, perlage (circular graining), hammering, mattifying, or other methods known to those skilled in the art.

[0040] Typically, the dial 1 shown in Figures 2a to 2c is manufactured using the method according to the present invention, and the dial has a multicolor appearance. Of course, other multicolor watch components, such as exterior components or movement components used in watches, can also be obtained using the method according to the present invention. Thus, middle cases, case backs, medallions, bezels, bezel inserts, push buttons, crowns, bracelet links, buckles, dials, hands, dial indices, rotors, bridges, or mainplates can be manufactured using the method according to the present invention.

Claims

1. A method for manufacturing a multi-colored, integrated ceramic component, - A step of preparing multiple ceramic powders or cermet powders, wherein the ceramic powders or cermet powders differ from each other in composition and / or color, and the powders consist only of ceramic elements, carbides, nitrides, oxides, or mixtures thereof. - The process of setting up the mold, - A process of depositing powder into the mold, - A process of forming multi-color ceramic parts by performing flash sintering or discharge plasma sintering over a total cycle time of 10 minutes to 180 minutes at a sintering temperature between 600°C and 1800°C and a sintering pressure between 5 N / mm² and 250 N / mm², - A process to release the obtained multi-colored parts, - A process of finishing the multi-color ceramic part (1) A manufacturing method that includes this.

2. The manufacturing method according to claim 1, characterized in that, after the demolding step, a heat treatment such as stepwise annealing in air or a reactive gas is carried out at a temperature between 550 and 1100°C for 30 minutes to 8 hours.

3. The manufacturing method according to claim 1, characterized in that the ceramic powder or cermet powder is selected from zirconium oxide powder, aluminum oxide powder, titanium nitride powder, silicon nitride powder, titanium carbide powder, chromium carbide powder, tungsten carbide powder, or a mixture of at least two of these powders.

4. The manufacturing method according to claim 1, characterized in that at least one ceramic powder contains one or more distinct pigments that give the ceramic different colors.

5. The method according to claim 1, characterized in that the pigment is a metal oxide, a perovskite, or spinel.

6. The method according to claim 4, characterized in that the pigment is selected from chromium oxide, cobalt oxide, iron oxide, titanium oxide, manganese oxide, molybdenum oxide, cerium oxide, vanadium oxide, zinc oxide, aluminum oxide, or a mixture thereof.

7. The method according to claim 4, characterized in that the pigment is cobalt / iron / chromium spinel or cobalt / aluminum spinel.

8. The method according to claim 4, characterized in that the pigment is cerium sulfide.

9. The method according to claim 1, characterized in that it includes a powder preparation step in which the powder is homogenized or pulverized in an aqueous or alcoholic solution.

10. The method according to claim 1, characterized in that the ceramic powder is atomized after the powder preparation step.

11. The method according to claim 1, characterized in that the powder is deposited in a mold by a selective powder deposition system to form a plurality of layers, and each deposited layer contains a plurality of powders.

12. The method according to claim 1, characterized in that a grid is placed inside the mold before the mold filling step.

13. The method according to claim 1, characterized in that the sintering step is carried out under vacuum or in a reactive gas.

14. A ceramic component characterized by having a multi-colored appearance.

15. The part according to claim 13, characterized in that the part is a watch part used as an exterior part or in a movement.

16. The watch component according to claim 13, characterized in that the watch component used as an exterior component or in a movement is selected from a list including a middle case, case back, bezel, bezel insert, push button, crown, bracelet link, buckle, dial, hands, dial indices, rotor, and base plate.

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