Ceramic article and method of making the same

Abstract

The invention relates to a multicolour cermet and / or ceramic article and to a method for manufacturing the same. The invention relates to a multicolour cermet and / or ceramic article, and in particular to a watch bezel (1), made by a method for injecting at least two materials (2, 3) of different colours, said article comprising a raised decoration (11) of a colour different from the rest of the article, said decoration (11) being made by laser ablation after injection of the two materials.

Description

Technical Field

[0001] This invention relates to articles obtained by multiple injection molding of ceramic and / or cermet materials. More specifically, this invention relates to a watch component (e.g., a bezel) made by injection molding of ceramic and / or cermet materials of different colors, wherein one color forms an ornamentation on the watch component. Background Technology

[0002] Ceramic or cermet watch components are typically obtained by injecting material and then sintering it. These components often feature decorative elements, such as bezel markings and numerals, which are distinguished by their color from the rest of the component. The individual elements of these decorative elements are usually attached directly to the sintered semi-finished product (ébauche) by brazing or gluing. This mechanical assembly between the semi-finished product and the decorative elements can be expensive and complex to implement.

[0003] An alternative to this mechanical assembly method is to manufacture semi-finished products by injecting materials of different colors, one of which is used to form decorative elements after processing. However, manufacturing ceramic or cermet parts with different colors is complex. In fact, significant shrinkage, which can amount to 30%, is observed during sintering. The shrinkage rate will depend on several factors, including the choice of materials and the volume of materials injected. In double-injection or more generally multi-injection methods, this can lead to differential shrinkage during sintering, which can cause separation at the joints between the different materials.

[0004] To overcome this drawback, a method of injecting a single material and impregnating the green body (corps vert) with a solution containing metal (as pigment) before sintering has been proposed in document EP 2 746 243. However, a disadvantage of this method is that it is difficult to obtain a uniform color across the entire colored portion. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned disadvantages by proposing a new multi-material injection method that limits the shrinkage differences between the different colored injection materials and has subsequent steps for processing decorations with one of the colors.

[0006] Therefore, the present invention relates to a manufacturing method using an insert with a raised or recessed structure during an injection step, the insert being used to imprint a hook surface for a second injection material onto a first injection material. This hook surface allows the second injection material to be retained, thereby reducing shrinkage during the sintering step.

[0007] More specifically, the method for manufacturing an article according to the present invention includes the following steps:

[0008] - Provides at least one first material and one second material, wherein the first material is distinguished from the second material by its chemical composition and more specifically by its color, and wherein the first material and the second material are ceramic or cermet.

[0009] - A mold with an empreinte is provided, the empreinte comprising a portion having a raised or recessed structure for forming a hook-and-loop surface on a first material.

[0010] - The first material is injected into the mold cavity containing the portion so that the structure is printed on the portion of the first material, thereby forming a hook-on surface on the portion.

[0011] - The second material is injected onto the first material at least at the hook-up surface to form a green body.

[0012] - Sintering green bodies to form semi-finished products,

[0013] - To create a decorative element in the second material on a base of the first material by laser ablation of at least a second material.

[0014] - Refining the semi-finished product to obtain the finished product.

[0015] Advantageously, the method also includes another processing step before and / or after the sintering step to adjust the dimensions of the green body and / or semi-finished product, respectively.

[0016] The present invention also relates to a ceramic and / or cermet article obtained by the manufacturing method. Articles according to the invention comprise at least two distinct materials, which are distinguished by their colors, and more generally by their aesthetic appearance. According to the invention, unlike articles decorated by directly attaching the elements of an ornament to the article by brazing or gluing, this decorative article is integrally formed, with no gap between the ornament and the remainder of the article. According to the invention, the ornament and the remainder of the article are generally colored with a uniform color for each color.

[0017] Other features and advantages of the invention will appear in the following description of preferred embodiments, which are presented by way of non-limiting examples with reference to the accompanying drawings. Attached Figure Description

[0018] Figure 1 A three-dimensional view showing the fixed portion of the mold with two cavities, one of which includes an insert having a raised structure according to the invention.

[0019] Figure 2 A three-dimensional view showing an insert with a raised structure.

[0020] Figure 3 This is a cross-sectional view of the mold during the injection of the first material on the right and the injection of the second material on the left.

[0021] Figure 4 This represents a three-dimensional view of the green body produced by double injection of material.

[0022] Figure 5 express Figure 4 A partial view of the green blank.

[0023] Figure 6 A three-dimensional view showing the decorative bezel produced by the manufacturing method according to the present invention.

[0024] Figure 7 A plan view showing the decorative bezel produced by the manufacturing method according to the present invention. Detailed Implementation

[0025] This invention relates to a method for manufacturing an article by injection molding, the article being made of at least two distinct materials, said materials being cermet or ceramic. The term "distinct materials" refers to materials distinguished by their aesthetic appearance, and especially their color. This results in differences in chemical composition. It can be the same substrate with different pigments used to change its color, or it can be different substrates. As an example, it can be the same zirconia substrate, where a black pigment is used on one side to obtain a black material, and an alumina pigment is used on the other side to obtain a white material. More generally, ceramics can be nitrides, carbides, and / or oxides. Similarly, cermets can include a ceramic phase and a metal binder phase, wherein the ceramic phase comprises carbides, nitrides, and / or oxides, and the metal binder is selected from, for example, noble metals such as ruthenium, rhodium, palladium, osmium, iridium, platinum, gold, and silver.

[0026] The article according to the invention can be a decorative article, such as a component of a watch, jewelry, bracelet, etc. In the field of watchmaking, the article can be an external component, such as a middle component, case back, bezel, bezel insert, pushers, crown, strap links, latches, dial, hands, dial markers, etc. It can also be a movement component, such as a balance wheel, bridges, etc. As an illustration, the article is a bezel 1 made of two ceramics of different colors, such as black and white, one color forming the base and the other color forming the decorative element 11, such as... Figure 6 and 7 As shown. Still as an example, it could be an acronym on the table's crown.

[0027] This article is made by injecting different materials to form a green body and then sintering the green body. The manufacturing method is described below for an article comprising two different materials, but the article can also comprise three, four, or other different materials, with hook surfaces created for each continuously injected material. Similarly, the description is for an article with decorations of the same color; however, decorations of different colors may exist.

[0028] refer to Figures 1 to 7 The manufacturing method includes the following steps:

[0029] - Provides at least one first material 2 and one second material 3, wherein the first material is distinguished from the second material by its color and therefore by its chemical composition, and wherein the first material and the second material are ceramic or cermet. Therefore, the first material and the second material can both be ceramic or both be cermet, or one material can be ceramic and the other cermet.

[0030] - A mold 5 is provided having a cavity 6, the cavity 6 including a portion 7, also referred to as an insert, which contains a raised or recessed structure for forming a hook surface on the first injection material. Figure 1 Preferably, the structure is convex. This structure is preferably discontinuous. Therefore, it can consist of multiple pillars 7a ( Figure 2 The recess or protrusion is formed. For better material retention, this discontinuous structure is preferred over a continuous structure (e.g., a groove or tab). Preferably, the recess or protrusion has a depth or height of at least 0.2 mm. Preferably, the number of protrusions or recesses is [number] per 10 mm. 2 The surface has 1 to 10, more preferably 1 to 3.

[0031] - The first material 2 is injected into the mold cavity 6 provided with the insert 7 so that the structure is printed on a portion of the first material 2, thereby forming a hook structure for the second material 3.

[0032] - The second material 3 is injected onto the first material 2 at least at the hook-and-joint surfaces to form a green compact 8. Figure 3 and Figure 4 ),

[0033] - Sintering green blanks 8 to form semi-finished products,

[0034] - At least a second material 3 of the green blank 8 or semi-finished product is processed by laser ablation to create a decoration 11 located on the first material 2 of the semi-finished product. The second material 3 is hollowed out into the first material 2 to expose the first material 2, and only the decoration 11 remains in the second material 3.

[0035] - Refining the semi-finished product to obtain the finished product.

[0036] During the processing steps, the first material can also be slightly hollowed out to remove material from the hook area, which will remain visible near the decoration. In other words, it involves removing the structure printed on a portion of the first material that will be visible near the decoration. When two or more different colors of material are present, different materials can be hollowed out to create decorations of different colors. Therefore, in the case of a third material injected onto the second material, the third material can be hollowed out into the second material or even into the first material to form a decoration located on the second material, or on the first material, or partially on both the second and first materials.

[0037] Laser ablation can be performed before sintering, i.e. on the green blank, or after sintering, i.e. on the semi-finished product.

[0038] Laser ablation is preferably performed using a pulsed laser, such as a picosecond, nanosecond, or femtosecond laser.

[0039] The method may also include another processing step, also known as a second processing step, for adjusting the dimensions of the green and / or semi-finished product. Preferably, the green is processed prior to sintering to prevent the material from becoming too hard. The invention does not preclude this processing step from being performed partly before sintering and partly after sintering.

[0040] If the material has been injected with an organic binder system (paraffin, polyethylene, etc.), the method may optionally include a debinding step prior to the sintering step.

[0041] After processing via laser ablation, the manufacturing method includes finishing steps such as polishing, satin finishing, and matte finishing.

[0042] In the illustrated example, the injection device includes a mold 5 having a fixed portion 5a formed by two mold cavities 6, wherein the first mold cavity 6a is used for injection of the first material 2, and the second mold cavity 6b is used for injection of the second material 3. Figure 1 The first mold cavity 6a includes an insert 7 with a raised structure. In this example, the insert is directly mounted to the mold cavity, but it can also be integral with the rest of the mold cavity. During injection, the first material 2 is injected into the mold 5 formed by the fixed portion 5a and the movable portion 5b, as shown. Figure 3 As shown on the right. Then, the movable portion 5a with the first injection material 2 is moved above the fixed portion 5b of another mold cavity 6b to allow for the injection of the second material 3. Figure 3(On the left). An insert 7 with a raised structure is used to print a recess 2a in the first material 2, which will serve as a hook during the injection of the second material 3. Figure 4 This refers to a green body 8 produced by double injection, wherein the second material 3 is superimposed on the first material 2. The green body and the semi-finished product at the end of sintering include a portion 4 in which the two materials 2 and 3 overlap, and more specifically, the two materials 2 and 3 interlock (…). Figure 5 The term "interlocking" refers to a structure in which one of two materials has a surface filled with another material. Figure 5 The image shows two materials 2 and 3, which are superimposed, with one material interlocked in a recess 2a formed on the surface of the other material.

[0043] To form the bezel, during the second processing step, the injection port 10 is cut and the inner diameter of the bezel is hollowed out. Before or after this, the second material is hollowed out to at least the first material by laser ablation to form an ornament 11, the color of which differs from the base formed by the bezel.

[0044] Typically, by injecting white and black zirconium oxide and sintering at 1400°C for 48 hours in an oxidizing atmosphere, the desired product is obtained. Figure 6 and Figure 7 bezel 1.

[0045] legend

[0046] (1) Products, watch parts or bezels

[0047] (2) The first material, also known as ceramics

[0048] a. concave part

[0049] (3) Second material, also known as ceramics

[0050] (4) Part of the product

[0051] (5) Mold

[0052] a. Fixed part

[0053] b. Movable parts

[0054] (6) Mold cavity

[0055] a. First mold cavity

[0056] b. Second mold cavity

[0057] (7) Insert, also known as part of the mold cavity

[0058] a. Column

[0059] (8) Green blank

[0060] (9) Inlet of green body

[0061] (10) Decorations.

Claims

1. A manufacturing method for producing ceramic articles having raised decorations (11) by injection molding, the method comprising the following steps: - Provide at least one first material (2) and one second material (3), wherein the first material (2) is distinguished from the second material (3) by its color, and the first material (2) and the second material (3) are ceramics. - A mold (5) is provided having a cavity (6), the cavity including a portion (7) having a protruding or recessed structure for forming a hook surface on the first material (2) after injection. - The first material (2) is injected into the mold cavity (6) having the portion (7) so that the structure is printed on the portion of the first material (2) and thereby forming a hook surface on the portion of the first material (2). - The second material (3) is injected onto the first material (2) at least at the hook surface to form a green body (8). - Sinter the green body (8) to form a semi-finished product. - A second material (3) is processed on the green blank (8) or the semi-finished product by laser ablation to make the raised decoration (11), wherein the second material (3) is at least hollowed out to the first material (2) by laser ablation to expose the first material (2) and the raised decoration (11) is obtained in the second material (3) located on the first material (2). - The semi-finished product is finished to obtain the finished product.

2. The manufacturing method according to claim 1, characterized in that, The structure of the portion (7) of the mold cavity (6) is discontinuous.

3. The manufacturing method according to claim 1 or 2, characterized in that, The structure of the portion (7) of the mold cavity (6) is convex.

4. The manufacturing method according to claim 3, characterized in that, The structure of the portion (7) of the mold cavity (6) is formed by a plurality of pillars (7a).

5. The manufacturing method according to claim 1 or 2, characterized in that, The structure of the portion (7) of the mold cavity (6) is recessed and formed by a plurality of recesses.

6. The manufacturing method according to claim 1 or 2, characterized in that, The second material (3) is injected onto the first material (2) to form the green body (8) comprising two superimposed layers having a layer of the first material (2) and a layer of the second material (3), the layers interlocking with each other at the hook surface.

7. The manufacturing method according to claim 1 or 2, characterized in that, The first material (2) is partially hollowed out to remove the hook surface.

8. The manufacturing method according to claim 1 or 2, characterized in that, The ceramic product is a multi-colored metal ceramic product.

9. The manufacturing method according to claim 1 or 2, characterized in that, The first material (2) and the second material (3) are metal ceramics.

10. A ceramic article having a raised decoration (11) having a color distinct from the rest of the article, the article being obtained by the manufacturing method according to any one of claims 1 to 9, characterized in that, The raised decoration (11) is integrally formed with the rest of the article, and the raised decoration (11) and the rest of the article are colored with a uniform color for each color in general.

11. The article of claim 10, characterized in that, The product in question is an external component or movement component of a watch.

12. The article of claim 11, characterized in that, The watch's external components or movement components are selected from a list that includes the following: center component, case back, bezel, bezel insert, pushers, crown, strap links, latches, dial, hands, dial markers, balance wheel, and bridges.

13. The article of claim 12, characterized in that, The article is a bezel (1) having the raised decoration (11) which is formed by at least indexes and numbers.

14. The article of claim 12, characterized in that, The article is a crown, the crown having the raised decoration (11), the raised decoration (11) being formed from an acronym.

15. The article of manufacture according to any one of claims 10 to 14, characterized in that, The raised ornament (11) is made of white zirconium oxide, and the rest of the article is made of black zirconium oxide.

16. The article of claim 10, characterized in that, The ceramic product in question is a multi-colored ceramic product.

17. The article of claim 10, characterized in that, The ceramic product in question is a metal-ceramic product.

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