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US-12619198-B2 - Multicolour cermet and/or ceramic article and manufacturing method thereof

US12619198B2US 12619198 B2US12619198 B2US 12619198B2US-12619198-B2

Abstract

A multicolour cermet and/or ceramic article, and in particular a bezel of a timepiece, made by a method for injecting at least two materials of distinct colours, said article comprising a relief decoration of a colour different from the rest of the article, said decoration being made by laser ablation after injection of the two materials.

Inventors

  • Thierry Cordier
  • Alexandre LE COLLETER
  • JULIEN MOREAU
  • Pascal Chopard-Lallier

Assignees

  • COMADUR SA

Dates

Publication Date
20260505
Application Date
20240813
Priority Date
20210719

Claims (8)

  1. 1 . A multicolour ceramic and/or cermet article with a relief decoration ( 11 ) of a colour distinct from the rest of the article, said article being obtained with a manufacturing method comprising: providing a first material ( 2 ) and a second material ( 3 ), said first material ( 2 ) being distinguished from the second material ( 3 ) by its colour, said first ( 2 ) and second ( 3 ) materials being either a ceramic or a cermet; providing a mould ( 5 ) with a pattern cavity ( 6 ) comprising a portion ( 7 ) including a relief or hollow structure configured to form a hooking surface on the first material ( 2 ) after injection; injecting said first material ( 2 ) into the pattern cavity ( 6 ) provided with the portion ( 7 ) so as to print the structure on a portion of the first material ( 2 ) and thus form the hooking surface on said portion; injecting the second material ( 3 ) onto the first material ( 2 ) at least at the hooking surface to form a green body ( 8 ); sintering the green body ( 8 ) to form a movement-blank; machining, by laser ablation, the second material ( 3 ) on the green body ( 8 ) or on the movement-blank to make the relief decoration ( 11 ), said second material ( 3 ) being hollowed out by laser ablation at least to the first material ( 2 ) to reveal said first material ( 2 ) and obtain the relief decoration ( 11 ) in said second material ( 3 ) standing on the first material ( 2 ); finishing the movement-blank to obtain the article, wherein the relief decoration ( 11 ) is formed in one piece with the rest of the article, said decoration ( 11 ) as well as the rest of the article being tinted in the mass with a uniform colour for each colour, and wherein the structure of the portion is discontinuous and the structure of the portion is formed of a multitude of structures provided in a quantity of 1 to 10 per 10 mm 2 of surface.
  2. 2 . The article according to claim 1 , wherein the article is a horological external or movement component.
  3. 3 . The article according to claim 1 , wherein the horological external or movement component is selected from the list comprising a middle, a bottom, a bezel, a bezel insert, a push-piece, a crown, a bracelet link, a buckle, a dial, a hand, a dial index, an oscillating weight and a plate.
  4. 4 . The article according to claim 1 , wherein the article is the bezel ( 1 ) with the relief decoration ( 11 ), and the relief decoration ( 11 ) indicates indexes and numerals.
  5. 5 . The article according to claim 1 , wherein the article is a crown with the relief decoration ( 11 ), and the relief decoration ( 11 ) indicates an acronym.
  6. 6 . The article according to claim 1 , wherein the decoration ( 11 ) is made of a white zirconia and the rest of the article of a black zirconia.
  7. 7 . The article according to claim 1 , wherein the multitude of structures are a multitude of studs.
  8. 8 . The article according to claim 1 , wherein the multitude of structures are a multitude of recesses.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a divisional of U.S. application Ser. No. 17/727,947, filed Apr. 25, 2022, which claims priority to European Patent Application No. 21186465.7 filed on Jul. 19, 2021, the disclosure of which is incorporated herein in its entirely by reference. TECHNICAL FIELD The present invention relates to an article obtained by multi-injection of ceramics and/or cermets. It relates more particularly to a horological component such as a bezel, made by injection of ceramic and/or cermet materials of different colours with one colour forming a decoration of the horological component. PRIOR ART The ceramic or cermet horological components are generally obtained by a method for injecting a material followed by sintering. These components often have a decoration, such as indexes and numerals for a bezel, which is of a colour distinct from the rest of the component. The elements of the decoration are generally directly mounted by brazing or gluing on the movement-blank resulting from the sintering. This mechanical assembly between the movement-blank and the elements of the decoration can be expensive and complicated to implement. An alternative to this mechanical assembly consists in making a movement-blank by injection of materials of different colours with a colour intended to form the decoration after machining. However, manufacturing ceramic or cermet components with different colours is complex. Indeed, a significant shrinkage, which can amount to 30%, is observed during sintering. The shrinkage rate will be dependent on several factors which are among others the choice of the material and the volume of injected material. This can result in the bi-injection or more generally multi-injection methods, differences in shrinkage during sintering which will lead to a disengagement at the junction between the different materials. In order to overcome this drawback, it has been proposed in the document EP 2 746 243 to inject a single material and to impregnate a portion of the green body before sintering with a solution comprising a metal acting as a pigment. However, this method has the drawback that it is difficult to obtain a uniform colour in the mass of the coloured portion. SUMMARY OF THE INVENTION The object of the present invention is to overcome the aforementioned drawbacks by proposing a new multi-material injection method limiting the differences in shrinkage between the injected materials of distinct colours, with a subsequent step of machining the decoration in one of the colours. To this end, the present invention relates to a manufacturing method using, during the injection step, an insert having a relief or hollow structure intended to imprint, on the first injected material, a hooking surface for the second injected material. This hooking surface allows holding the second injected material and thus reducing the shrinkage during the sintering step. More specifically, the method of manufacturing the article according to the invention includes the following steps: Providing at least one first material and one second material, said first material being distinguished from the second material by its chemical composition and more particularly by its colour, said first and second materials being either a ceramic or a cermet,Providing a mould with a pattern cavity comprising a portion provided with a relief or hollow structure intended to form the hooking surface on the first material,Injecting said first material into the pattern cavity provided with the portion so as to print the structure on a portion of the first material and thus form the hooking surface on said portion,Injecting the second material onto the first material at least at the hooking surface to form a green body,Sintering the green body to form a movement-blank,Machining, by laser ablation, at least the second material to make the decoration in said second material on the bottom of said first material,Finishing the movement-blank to obtain the article. Advantageously, the method further comprises another machining step before and/or after the sintering step to size respectively the green body and/or the movement-blank. The present invention also relates to the ceramic and/or cermet article resulting from the manufacturing method. The article according to the invention includes at least two distinct materials being differentiated by their colour, more generally by their aesthetic appearance. According to the invention, the decorated article is formed in one piece without discontinuity between the decoration and the rest of the article, unlike an article decorated by directly mounting, by brazing or gluing, the elements of the decoration on the article. According to the invention, the decoration as well as the rest of the article are tinted in the mass with a uniform colour for each colour. Other features and advantages of the present invention will appear in the following description of a preferre