Ceramic component having a color gradient and method for manufacturing the same

Abstract

To provide a production method capable of mass production of a ceramic part with a color gradient, in particular a bezel of a timepiece, and to provide such a ceramic part.SOLUTION: The present invention produces a ceramic part using uniaxial pressing by a method involving the injection of at least two differently-colored ceramic materials, the ceramic materials being mixed in different weight ratios to create a plurality of mixed materials forming a color gradient.SELECTED DRAWING: Figure 3a

Description

Technical Field

[0001] The present invention relates to ceramic parts. More specifically, the present invention relates to timepiece parts such as bezels made by uniaxially pressing a plurality of ceramic materials of different colors that form a continuous change in color for decorating timepiece parts.

Background Art

[0002] Timepiece parts made of ceramic or cermet are generally obtained by a method including injection of materials, or a method including uniaxially pressing or hydrostatic pressing of materials and subsequent sintering. These parts often feature decorations such as indices and numbers on bezels of a color different from the rest of the part, or simply a two-tone (combining two colors) decoration throughout. The decorative elements are generally brazed or adhered to the sintered blank parts. This mechanical assembly between the blank parts and the decorative elements can be costly and complex to implement.

[0003] An alternative to this mechanical assembly is to manufacture blank parts by injecting a plurality of materials of different colors having colors intended to form decorations after machining. However, manufacturing parts made of different colors of ceramic or cermet is a complex process. In fact, significant shrinkage of up to 30% is observed during sintering. The shrinkage rate depends on several factors such as the choice of material and the amount of material injected. In the bi-injection method or the more general multi-injection method, a shrinkage difference occurs during sintering, and separation may occur at the joints of various materials.

[0004] To improve this drawback, Patent Document 1 proposes forming a green body and impregnating a part of this green body with a solution containing a metal that functions as a pigment before sintering. However, a drawback of this method is that it is difficult to obtain a uniform color throughout the colored part. Furthermore, Patent Document 2 describes a method for obtaining a ceramic material having a continuous color change and forming a dental prosthesis. However, such a method generally uses hydrostatic press molding, which is time-consuming and demanding. Moreover, such a method cannot be industrially applied for mass production. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] European Patent Application Publication No. 2746243 [Patent Document 2] European Patent Application Publication No. 2965713 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention aims to improve upon the above-mentioned drawbacks by providing a novel uniaxial compression molding method for obtaining ceramic parts having a color gradient. [Means for solving the problem]

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

[0008] More specifically, the method for manufacturing a component according to the present invention is: The steps include: preparing at least a first ceramic material and a second ceramic material, wherein the first ceramic material has a different color from the second ceramic material; • The step of preparing a filling shoe with compartments attached, The process involves preparing multiple mixed materials, each containing a first ceramic material and a second ceramic material in different weight ratios, while varying the weight ratios to form a desired color gradient. The steps include: • Stacking the materials in ascending or descending order according to their weight ratio within the compartments of the filling shoe; • Steps to prepare the impression on the filling shoe, The steps include: filling the impression with a mixed material deposited inside the shoe, • The step of removing the filling shoe and uniaxially press-molding the mixed material in order to form the green body, • The step of degreasing the green body in order to obtain the brown body, • The step of sintering a brown body to form a blank part, The steps include: • Machining the obtained blank part to obtain a ceramic part having a color gradient. Includes.

[0009] The present invention also relates to ceramic components obtained by this manufacturing method.

[0010] According to other advantageous modifications of the present invention, The first ceramic material and the second ceramic material include any of the following: 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. The first ceramic material and the second ceramic material each contain different pigments that give the first ceramic material and the second ceramic material different colors. The pigment is a metal oxide 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 thereof. The pigment is cobalt / iron / chromium spinel or cobalt / aluminum spinel. The first ceramic powder and the second ceramic powder each contain a binder. The degreasing step consists of thermal degreasing. The sintering step is carried out at a temperature between 1,200°C and 1,800°C for 30 minutes to 20 hours. ·The sintering step is carried out in an oxidizing or reducing environment.

[0011] The present invention also relates to a ceramic component having a color gradation.

[0012] The component according to the present invention includes several different ceramic materials with different colors and more generally different aesthetic appearances. According to the present invention, the decorated component is an integral body, and there is no discontinuity between the ceramic materials of the component to obtain a color gradation. Other features and advantages of the present invention will become apparent in the following description of preferred embodiments presented as non-limiting examples with reference to the accompanying drawings.

Brief Description of the Drawings

[0013] [Figure 1] A perspective view of the filling shoe used in the manufacturing method according to the present invention is shown. [Figure 2a-2b] Perspective views and top views of the impressions used in the manufacturing method according to the present invention are shown respectively. [Figure 3a] An exemplary embodiment of a ceramic component having a continuous change in color obtained using the manufacturing method according to the present invention is shown. [Figure 3b] An exemplary embodiment of a ceramic component having a continuous change in color obtained using the manufacturing method according to the present invention is shown. [Figures 4a-4d] Various steps in the manufacturing method according to the present invention are shown.

Modes for Carrying Out the Invention

[0014] The present invention relates to a ceramic component such as an exterior component or a watch component used in watches or jewelry, which has a color gradation over its entire mass. "Color gradation" refers to a continuous change in color, and at least two colors are used as a basis for creating a continuous change. Of course, the continuous change in color can have three or more base colors.

[0015] The components according to the present invention are made of ceramic. For example, they may be made of zirconium oxide, aluminum oxide, titanium nitride, silicon nitride, or carbides such as titanium carbide, chromium carbide, tungsten carbide, or mixtures thereof of these ceramics.

[0016] At least one of the ceramic materials contains a pigment for coloring the material. The pigment is a metal oxide or spinel selected according to the desired color. 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 (e.g., iron oxide / chromium oxide). For example, in the case of blue, the pigment may be cobalt oxide; in the case of green, the pigment may be chromium oxide; and in the case of brown, the pigment may be iron oxide.

[0017] The component according to the present invention may also be a decorative component such as a component of a watch, jewelry, or wristlet. In the field of watchmaking technology, this component may be an exterior component such as a middle, case back, bezel, bezel insert, button, crown, wristlet link, clasp, buckle, dial, hands, or dial indices. This component may also be a movement component such as a oscillating weight or platinum. As an example, the component is a bezel 1 made of multiple ceramics of different colors, for example, having a gradient from black to turquoise blue. As a further example, the component may be the acronym on the crown of a watch or an index on the bezel.

[0018] The parts are made by injecting various materials to form a green body and by sintering the green body. The manufacturing method for a part containing seven consecutive materials of different colors is shown below, but the part may also consist of two, three, four, or more materials, each having a different color and / or composition for each of the consecutive materials injected.

[0019] The manufacturing method by uniaxial compression molding includes the following steps, as shown in the diagram. Prepare at least a first ceramic material 2 and a second ceramic material 3. The first material differs from the second material by its color and therefore by its chemical composition. Multiple mixed materials 20, 21, 22, 23, and 24, in which the first ceramic material 2 and the second ceramic material 3 are mixed in different weight ratios, are prepared by varying the weight ratios to form a continuous change of the desired color. Thus, when using two types of ceramic materials, the mixed materials can have weight ratios such as 100 / 0, 90 / 10, 80 / 20, 70 / 30, 60 / 40, 50 / 50, 40 / 60, 30 / 70, 20 / 80, 10 / 90, and 0 / 100. For those skilled in the art, it would not be difficult to use three or more types of ceramic materials, for example, three, four, or five types of ceramic materials, to obtain the desired color and the desired color gradient. Prepare a filling shoe 5 containing compartments arranged to receive mixtures of ceramic materials 20, 21, 22, 23, and 24. The number of compartments in the filling shoe 5 is determined by the desired final gradation. Place the impression 6 on the filling shoe 5. - The mixed material deposited in the compartment of the filling shoe is filled into the impression 6 in ascending or descending order according to the desired weight ratio or gradation. The height of the mixed material deposited in the compartment is at least 0.5 mm and does not exceed the height of the filling shoe. • To form the green body 7, the filling shoe 5 is removed and the mixed material is uniaxially compressed. • Degrease the green body 7 in order to form the brown body. • Brownian bodies are sintered to form blank parts. • A finishing step is performed on the blank part to form part 1.

[0020] By stacking several layers of mixed ceramic material, a specific color pattern can be formed that is visible from the side of the part.

[0021] The compartments of the filling shoe may be linear or non-linear, depending on the needs and desired patterns of those skilled in the art.

[0022] Ceramic materials can be raw materials that are mainly ceramic powder, or mixtures of ceramic powder and organic binders.

[0023] When using raw materials to form a mixed material, a degreasing step is required before sintering the green body 8. Degreasing (debinder removal) can be carried out in a solvent to remove materials such as wax and paraffin. Subsequently, thermal degreasing can be performed in a temperature range of 100°C to 800°C.

[0024] The brown body is sintered for 30 minutes to 20 hours at a temperature range of 1,200°C to 1,800°C, preferably 1,350°C to 1,450°C. Those skilled in the art know that each color has an optimal temperature and time during sintering so that the color appears immediately after sintering. Therefore, when creating a continuous change, it is particularly useful to select multiple colors having similar sintering temperatures and times, and to sinter at the average temperature of the ideal sintering temperatures of the selected multiple colors.

[0025] Preferably, the temperature is raised at a rate of 100°C to 200°C per hour until the desired sintering temperature is reached. Once sintering is complete, the temperature is gradually lowered at a rate of 100°C to 200°C per hour.

[0026] The sintering step is carried out in an oxidizing or reducing environment. For example, sintering can be carried out in an oxygenated atmosphere, which may be ordinary air or an atmosphere artificially created by combining oxygen with other gases. The oxygenated atmosphere may be static, or there may be a constant or intermittent flow of gas.

[0027] Depending on the needs of those skilled in the art, several sintering steps can be performed to obtain the desired result.

[0028] To form the bezel, the blank part is machined to the desired dimensions.

[0029] The method may include laser ablation to form decorations on the parts. The decorations may consist of, for example, indices, markings, or logos.

[0030] Following laser ablation, the manufacturing process includes finishing steps such as polishing, satin finish, and matte finish. Furthermore, post-sintering machining can help to more clearly accentuate continuous color variations or specific patterns, depending on the cross-section of the part.

[0031] Typically, the bezel 1 shown in Figures 3a and 3b is obtained using the method according to the present invention, and the bezel has a color gradient from black to turquoise blue. Naturally, other gradients based on other colors can be obtained using this method.

Claims

1. A method for manufacturing ceramic parts having a color gradient by uniaxial compression molding, - A step of preparing at least a first ceramic material (2) and a second ceramic material (3), wherein the first ceramic material (2) is of a different color from the second ceramic material (3), - A step of preparing a filling shoe (5) which includes multiple compartments (4) arranged in a horizontal line, - A step of preparing a plurality of mixed materials (20, 21, 22, 23, 24) in which the first ceramic material (2) and the second ceramic material (3) are mixed in different weight ratios, while changing the weight ratio, - A step of depositing the mixed material in ascending or descending order according to the weight ratio within the compartment of the filling shoe so as to form a desired color gradient in the horizontal direction, - A step of preparing the impression (6) on the filling shoe (5), - A step of filling the impression (6) with the mixed material deposited inside the filling shoe (5), - A step of removing the filling shoe and uniaxially press-molding the mixed material in the vertical direction in order to form the green body (7), - A step of degreasing the green body (7) in order to obtain the brown body, - A step of sintering the brown body to form a blank part, - A step of machining the blank part (8) obtained in order to obtain a ceramic part (1) having a color gradient. Includes, A method wherein the first ceramic material (2) and the second ceramic material (3) contain the same ceramic powder as a main raw material.

2. The method according to claim 1, characterized in that the same ceramic powder is any one of 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.

3. The method according to claim 1, characterized in that the first ceramic material (2) and the second ceramic material (3) each contain different pigments that give the first ceramic material (2) and the second ceramic material (3) different colors.

4. The method according to claim 3, characterized in that the pigment is a metal oxide or spinel.

5. 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.

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

7. The method according to claim 1, characterized in that the first ceramic material (2) and the second ceramic material (3) each include a binder.

8. The method according to claim 7, characterized in that the degreasing step comprises thermal degreasing.

9. The method according to claim 1, characterized in that the sintering step is carried out at a temperature between 1,200°C and 1,800°C for 30 minutes to 20 hours.

10. The method according to claim 1, characterized in that the sintering step is carried out in an oxidizing or reducing environment.

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