CH718555A2 - Process for producing a ceramic part with a pearly effect, in particular for watchmaking. - Google Patents

Abstract

The invention relates to a method for producing a ceramic part (10) with a pearly effect, in particular for watchmaking, the method comprising the following steps: a step for forming a ceramic body (8), a step of depositing a layer of an oxy-nitride component (9) of the OxNy type on at least a part of the ceramic body (8), and a step of oxidizing at least a part of the oxy-nitride layer (9), preferably by heating. A ceramic body (8) is thus obtained, partly covered by a transparent layer (13) producing an iridescent or pearly effect.

Description

Technical field of the invention

The invention relates to a method for producing a ceramic part with a pearly effect, in particular for watchmaking.

Technology background

[0002] The invention will find application in the manufacture of a casing component intended, preferably but not limited to, to the field of watchmaking. Preferably, such a component may for example be a watch bezel intended to be attached to a watch case, a bracelet link, a dial, a watch case, a clasp element.

The invention will also find an application in the manufacture of trim components used in the fields, in a non-exhaustive manner, of mobile and cellular telephony, computer terminals, in particular portable ones, for example to form cell phone shells or tablets, or even in the field of jewelry or tableware.

The invention relates in particular to elements made of hard materials, namely resistant to shocks and scratches. These hard materials may in particular be of technical ceramic types. In addition, each element can be made of zirconium dioxide or "zirconia", aluminum dioxide or "alumina", or even a composite material integrating a ceramic support and a metal matrix or "cermet". Each element of the covering component of the invention can also be made of synthetic sapphire or ruby.

To manufacture these parts, a process is used comprising the following steps: production of a precursor from a mixture of at least one powdered material with a binder, formation of a green body by injection into a mold or by pressing to give the shape of the final part to the green body, sintering said green body in order to harden it and obtain the desired part;

[0006] With conventional methods, the ceramic parts obtained can be colored, for example white. There are processes to obtain a more or less shiny or rather matt ceramic color.

[0007] However, the variation is limited to these shades of color, and it is difficult to obtain other shades, so that interesting color aspects for ceramics are missing.

Summary of the invention

The invention aims to remedy the aforementioned drawbacks, and aims to provide a method for obtaining a ceramic part whose color is pearly, that is to say which has iridescent reflections.

[0009] To this end, the invention relates to a method for producing a ceramic part with a pearly effect, in particular for watchmaking.

The method is remarkable in that it comprises the following steps: a step of forming a ceramic body, a step of depositing a layer of an OxNy type oxy-nitride component on at least a part of the ceramic body, and a step of oxidizing at least part of the oxy-nitride layer, preferably by heating.

[0011] Thus, the method makes it possible to obtain a pearly color on the surface of the ceramic. Indeed, the oxidation of the oxy-nitride layer on the surface of the part of the ceramic part makes this layer partly transparent. The color of the body is visible through this layer, which produces iridescent effects, and therefore a pearlescent finish.

[0012] According to a particular embodiment of the invention, the method the step of forming the ceramic body comprises a sub-step of producing a precursor from a mixture of at least one powder material with a binder.

According to a particular embodiment of the invention, the step of forming the ceramic body comprises a sub-step of forming a green body by injection into a mold or by pressing, the green body having the shape desired for the body.

[0014] According to a particular embodiment of the invention, the step of forming the ceramic body comprises a sub-step of sintering the green body in order to harden it and obtain the desired shape.

[0015] According to a particular embodiment of the invention, the body formed during the step of forming the body is in one piece, and preferably made of white ceramic.

According to a particular embodiment of the invention, the method comprises a step of structuring the layer of the oxy-nitride component before the step of oxidation of the layer.

According to a particular embodiment of the invention, the structuring step is carried out by photolithography, or by direct ablation, for example by laser.

According to a particular embodiment of the invention, the oxy-nitride component is to be chosen from zirconia oxy-nitride of the ZrOxNy type, chromium oxy-nitride of the CrOxN type or oxy -Titanium nitride of the TrOxNy type.

According to a particular embodiment of the invention, the body is heated to at least 500° C., preferably at least 600° C., during the oxidation step

According to a particular embodiment of the invention, the step of depositing the oxy-nitride layer is carried out by physical vapor deposition of the PVD type.

[0021] According to a particular embodiment of the invention, the ceramic body formed during the step of forming the body comprises zirconia, preferably entirely.

According to a particular embodiment of the invention, comprises a step of polishing the body before the step of depositing the oxy-nitride layer.

Brief description of figures

Other features and advantages will emerge clearly from the description given below, by way of indication and in no way limiting, with reference to the appended drawings, in which: FIG. 1 is a block diagram representing the steps of the method according to the invention; Figure 2 is a schematic representation of a sectional view of a body on which a layer of oxy-nitride has been deposited; Figures 3 to 6 are schematic representations of cross-sectional views of the body of Figure 2 during the sub-steps of structuring the oxy-nitride layer; Figure 7 is a schematic representation of a sectional view of the body obtained after the oxidation step; and FIG. 8 is an example of a part obtained using the method according to the invention.

Detailed description of the invention

[0024] As explained above, the invention relates to a method for producing 1 a ceramic part with a pearly effect, in particular for watchmaking, for example for a watch case, bracelet links, a watch bezel, or a dial with ceramic indices. This process 1 can of course be used for any ceramic part, apart from watchmaking.

[0025] Method 1 includes a first step 2 of forming a ceramic body. In general, this step consists of several sub-steps. A first sub-step consists in producing a precursor from a mixture of at least one powdered material with a binder. This material is preferably ceramic. This step 2 is intended to form a precursor from a ceramic-based powder taken in the binder.

[0026] In this context, the ceramic-based powder may comprise at least one metal oxide, a metal nitride or a metal carbide. By way of example, the ceramic-based powder may comprise aluminum oxide or a mixture of aluminum oxide and chromium oxide, or even zirconium oxide. In addition, the binder can be of various natures such as, for example, polymeric types or organic types.

The first step 2 then includes a sub-step of forming the green body, in which the green body is given a shape corresponding to the final part that one wishes to obtain. To this end, a method of injection molding the precursor into a mold is preferably used. Alternatively, it is possible to use a process for pressing the precursor with a pressing device provided with an upper die and a lower die between which the precursor is pressed.

[0028] The first step 2 comprises a third sub-step of sintering the green body in order to form a hard body in the ceramic material. Preferably, the sintering sub-step may include pyrolysis. During the sintering step, the body shrinks by a coefficient depending on the material of which it is made.

[0029] The body obtained in ceramic is preferably in one piece, and comprises for example zirconia, preferably in its entirety.

[0030] In a second step 3, the sintered body is polished to give it a smooth surface facilitating the deposition of the third step, and makes it possible to have an advantageous aesthetic appearance for the parts of the ceramic body which will remain visible for the part. final.

The third step 4 of method 1 consists in depositing a layer of an oxy-nitride compound of the OxNy type on at least part of the ceramic body. The oxy-nitride compound is preferably to be chosen from zirconia oxy-nitride of the ZrOxNy type, chromium oxy-nitride of the CrOxN type or titanium oxy-nitride of the TrOxNy type. The layer preferably has a thickness of between 50 and 1000 nm, or even between 100 and 500 nm.

The deposition of the oxy-nitride layer is preferably carried out by physical vapor deposition of the PVD type. For example, a reactive spray deposition method is used.

[0033] Optionally, method 1 comprises a fourth step 5 of structuring the layer of the oxy-nitride compound. This step is used in the case where one wishes to have a particular pearl pattern. Structuring consists of giving a shape to the oxy-nitride layer by removing certain parts of the layer. One can for example choose a pattern corresponding to a Logo, a brand or time indices drawn on glasses.

This structuring step 5 is preferably carried out by photolithography. Photolithography consists in depositing a layer of photosensitive resin on the parts of the layer to be preserved in order to protect them and in chemically etching the layer of oxy-nitride to remove the parts which are not protected by the resin. Thus, only part of the layer is kept after the protective resin has disappeared.

[0035] As a variant, the structuring can be carried out by means of a laser, which removes parts of the oxy-nitride layer.

In a fifth step 6, oxidation of the oxy-nitride layer is carried out to give it a pearly or iridescent appearance. For this, the part is heated, preferably in an oven. The part is heated to at least 500°C, preferably at least 600°C. The heating oxidizes the layer or parts of the oxy-nitride layer, and makes them at least partly transparent. This partly transparent layer gives the pearly or iridescent effect.

[0037] Figures 2 to 7 show illustrations of the various stages of production of a part according to the method described above, in particular for the stages of structuring the oxy-nitride layer.

In Figure 2, a body 8 formed according to the first and the second step of the process is covered with a layer of oxy-nitride 9, according to the third step of the process by a PVD type process.

To structure the layer 9 and select a part to keep, photolithography is carried out, in which a photosensitive resin 11 is applied over the entire layer 9. A mask is placed on the resin 11 to protect part of the resin 11. The mask has the shape that one wishes to obtain for the layer, either positive or negative, depending on the resin used.

The assembly is subjected to radiation, preferably ultraviolet, to modify the characteristics of the illuminated resin. Two portions of resin 11, 12 are thus obtained, as shown in FIG. 3, one of them having been exposed to radiation, the other portion not having been subjected to radiation.

Alternatively, one can avoid the use of a mask, and directly expose the resin 11 with a selective ultraviolet source, such as an ultraviolet laser.

One of the portions 11 of resin is eliminated, to keep only a portion of resin 12 on part of the oxy-nitride layer, as shown in Figure 4.

In Figure 5, by a chemical etching sub-step, the part of the oxy-nitride layer 14 which is not protected by the remaining resin portion 12 is removed. Thus, the body 8 partially covered by part of the oxy-nitride layer 13 and the remaining resin portion 12.

The resin portion 12, which made it possible to protect the part of the selected layer, is then eliminated to keep only the body and said part.

According to the fifth step of the method, the part of the oxy-nitride layer 13 is oxidized by heating it, according to the fifth step of the method, in order to make it at least partly transparent. Thus, a ceramic body 8 is obtained partly covered by a transparent layer 13 producing an iridescent or pearly effect.

Figure 8 is an example of part 15 in the form of a ceramic ring for a watch bezel. In this case, the ring is almost completely covered with an iridescent layer 16. The process described above was used, the step of structuring the oxy-nitride layer serving for example to inscribe a logo on the ring .

A part can be completely covered with an iridescent layer, the structuring step not being applied in this case.

Of course, the present invention is not limited to the example illustrated but is susceptible to various variants and modifications which will become apparent to those skilled in the art.

Claims (12)

1. Method for producing (1) a ceramic part (10, 15) with a pearly effect, in particular for watchmaking, characterized in that the method (1) comprises the following steps: – a step of forming (2) a ceramic body (8), – a step of depositing (4) a layer (9) of an oxynitride component of the OxNy type on at least a part (13) of the ceramic body (8), and – an oxidation step (6) of at least a part (13) of the oxy-nitride layer (9), preferably by heating. 2. Method according to claim 1, characterized in that the step of forming (2) the ceramic body (8) comprises a sub-step of producing a precursor from a mixture of at least one material powder with a binder. 3. Method according to claim 2, characterized in that the step (2) of forming the ceramic body (8) comprises a sub-step of forming a green body by injection into a mold or by pressing, the body green having the desired shape for the body (8), 4. Method according to claim 3, characterized in that the step of forming (2) the ceramic body (8) comprises a sub-step of sintering the green body in order to harden it and obtain the desired shape, 5. Method according to any one of the preceding claims, characterized in that the body (8) formed during the forming step (2) of the body (8) is in one piece, and preferably in white ceramic; 6. Method according to any one of the preceding claims, characterized in that it comprises a step of structuring (5) the layer of the oxy-nitride component before the step of oxidation of the layer (6 ). 7. Method according to claim 6, characterized in that the structuring step (5) is carried out by photolithography or by direct ablation, for example by laser. 8. Method according to any one of the preceding claims, characterized in that the oxy-nitride component is to be chosen from zirconia oxy-nitride of the ZrOxNy type, chromium oxy-nitride of the CrOxN type or titanium oxy-nitride of the TrOxNy type. 9. Method according to any one of the preceding claims, characterized in that the body (8) is heated to at least 500°C, preferably at least 600°C, during the oxidation stage (6 ). 10. Method according to any one of the preceding claims, characterized in that the step of depositing the oxy-nitride layer (4) is carried out by physical vapor deposition of the PVD type. 11. Method according to any one of the preceding claims, characterized in that the ceramic body (8) formed during the step (2) of forming the body (8) comprises zirconia, preferably entirely . 12. Method according to any one of the preceding claims, characterized in that it comprises a polishing step (3) of the body (8) before the step of depositing the oxy-nitride layer (9) .