Ceramic timepiece or jewellery component

Abstract

To provide a component of a timepiece or a piece of jewelry made of a material having a hardness greater than or equal to that of 3000HV in order to increase its resistance to wear, scratching and, more generally, to degradation.SOLUTION: The invention concerns a timepiece or jewellery component including, in the range from 99% to 100% by volume, silicon nitride in the gamma phase.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to timepiece or jewelry components made from a hard, optically transparent ceramic material. [Background technology]

[0002] Currently, various timepiece components are made from the following materials. Bezels for portable timepieces (e.g., wristwatches and pocket watches) are generally made from ceramic materials such as zirconium oxide, aluminum alloys, or steel. Crystals are usually made from sapphire, and timepiece stones are generally ruby. Case middles, pushers, and crowns are usually made from metal alloys such as stainless steel, titanium, or ceramics. One such ceramic is silicon nitride. Silicon nitride used in timepiece components exists in the trigonal α phase or the hexagonal β phase, both of which have hardnesses in the range of 1500HV to 1600HV.

[0003] Typically, the hardness of these materials ranges from 1600 HV for ceramics to 2000 HV for ruby. It is difficult to achieve hardness values ​​higher than these, which limits their ability to reduce the vulnerability of the external components of the timepiece, such as the buttons and bezel.

[0004] Nowadays, there is an increasing demand for materials with higher hardness values ​​than those mentioned above, as the higher the hardness, the less susceptible they are to scratches and the less wear and deterioration they undergo. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide a timepiece or jewelry component made from a material having a hardness of 3000 HV or more in order to increase its resistance to wear, scratches and, more generally, deterioration. [Means for solving the problem]

[0006] To this end, we propose creating timepiece or jewelry components from silicon nitride containing the cubic gamma phase, rather than the alpha or beta phases currently used in timepiece components. In the gamma phase, silicon nitride possesses exceptional hardness, reaching up to 3500 HV. Therefore, the hardness of components is 2.3 times that of traditional ceramics. For exterior applications, case middles, bezels, crowns, and buttons made from this material offer unique scratch resistance. This material is also optically transparent. This optical transparency makes it particularly attractive for creating crystals with exceptional scratch resistance. For interior applications, for example, timepiece stones made from this material are 1.75 times harder than rubies, which are commonly used for this purpose. Furthermore, initial research suggests that silicon derived from silicon nitride could enable lubricant-free movements. This material is likely to have favorable tribological properties, which could lead to the development of maintenance-free movements. Improved tribological properties contribute to lowering the coefficient of friction between components in dry or lubricated contact, thereby reducing wear of the internal components.

[0007] In particular, the present invention relates to a timepiece or jewelry component comprising silicon nitride in the gamma phase in the range of 99% to 100% by volume.

[0008] In particular, the present invention relates to a timepiece or jewelry component comprising in the range of 99% to 100% by volume of gamma-phase silicon nitride, optionally containing up to 1% by volume of alpha and / or beta-phase silicon nitride and / or impurities. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention relates to timepiece or jewelry components made of gamma-phase silicon nitride (Si3N4). In the field of timepieces, these can be external parts such as case middles, case backs, bezels, pushers, crowns, valves, wrist links, dials, hands, and dial indexes, but also movement components such as timepiece stones.

[0010] Components made from this gamma silicon nitride have a hardness of over 3000 HV and can reach up to 3500 HV.

[0011] Components are made from powders or powder blends, such as the SN-E10 powder sold by Ube Industries, Ltd. (Ube City, Yamaguchi Prefecture, Japan). The powder blend can consist of 20% α-Si3N4 and 80% β-Si3N4 or 100% β-Si3N4. Sintering is performed in a MAP (Multi-Anvil Press) apparatus. The press can be of the KAWAI type. This press allows for extreme pressures of up to 45 GPa using an anvil assembly that applies force to the encapsulated powder. The capsules can be made of platinum. Sintering is performed at temperatures ranging from 1600°C to 1900°C, preferably 1650°C to 1850°C, for dwell times ranging from 20 to 60 minutes, under pressures of 10 GPa or higher, preferably 15 GPa or higher. The achievable pressures are higher for smaller components, making it particularly suitable for the production of buttons, crowns, and timepiece stones.

[0012] Preferably, the resulting component is composed of 100% by volume of gamma-phase Si3N4, but the presence of alpha and / or beta-phase Si3N4 in proportions of less than 1% by volume cannot be excluded, the presence of different phases being quantified by X-ray diffraction according to standard NF EN 13925. This proportion of less than 1% may also contain impurities such as Na, Ca, P, Fe, Ni, Cl.

[0013] The hardness of this component is in the range of 3000HV to 3500HV as measured according to ISO 14705:2016. Another feature is that it is optically transparent.

Claims

1. Contains 99% to 100% by volume of gamma-phase silicon nitride 1. A component of a timepiece or piece of jewelry, characterized in that:

2. HV hardness is in the range of 3000 to 3500 2. A timepiece or jewelry component according to claim 1.

3. External parts or components of the movement 2. A timepiece or jewelry component according to claim 1.

4. Buttons, crowns, or timekeeping stones 4. A timepiece or jewelry component according to claim 3.

5. It is a windshield 4. A timepiece or jewelry component according to claim 3.