COMPONENT FOR TIMEPIECE OR PIECE OF JEWELLERY MADE OF CERMET

Abstract

A component suitable for a timepiece or a jewellery item may be made of a cermet material including a carbide phase and a metal binder phase selected from among gold, platinum, palladium rhodium, osmium, ruthenium, and one of the alloys thereof. The metal binder phase may be present in a range of from 3 and 25 wt. % and the carbide phase may be present in a range of from 75 and 97 wt. %.

Claims

1. A non-ferromagnetic component, which is suitable for a timepiece or jewelry, wherein the non-ferromagnetic component comprises: a cermet material comprising a carbide phase and a metallic binder phase of a binder, wherein the binder comprises platinum, wherein the metallic binder phase is present in a range of from 3 to 25 wt. %, wherein the carbide phase is present in a range of from 75 to 97 wt. %, and wherein the non-ferromagnetic component is free from nickel and cobalt.

2. The non-ferromagnetic component of claim 1, wherein the metallic binder phase is present in a range of from 3 to 22 wt %, and wherein the carbide phase is present in a range of from 78 to 97%.

3. The non-ferromagnetic component of claim 1, characterised in that the metallic binder phase is present in a weight percentage between 6 and 22% and in that the carbide phase is present in a weight percentage between 78 and 94%.

4. The non-ferromagnetic component of claim 1, wherein the carbide phase comprises titanium carbide, molybdenum carbide, silicon carbide, tungsten carbide, and/or niobium carbide.

5. The non-ferromagnetic component of claim 1, wherein the carbide phase comprises predominantly titanium carbide or molybdenum carbide or tungsten carbide.

6. The non-ferromagnetic component of claim 4, wherein the carbide phase comprises predominantly titanium carbide and a minority of molybdenum carbide.

7. The non-ferromagnetic component of claim 4, wherein the carbide phase comprises predominantly titanium carbide and a minority of silicon carbide.

8. The non-ferromagnetic component of claim 4, wherein the carbide phase comprises predominantly molybdenum carbide.

9. The non-ferromagnetic component of claim 1, having a hardness HV30 in a range of from 700 to 1900.

10. The non-ferromagnetic component of claim 5, having a hardness HV30 in a range of from 700 to 1300, and wherein the carbide phase comprises predominantly molybdenum carbide.

11. The non-ferromagnetic component of claim 5, having a hardness HV30 in a range of from 1000 to 1900, and wherein the carbide phase comprises predominantly titanium carbide and a minority of silicon carbide.

12. The non-ferromagnetic component of claim 5, having a hardness HV30 in a range of from 900 to 1600, and wherein the carbide phase comprises predominantly tungsten carbide.

13. The non-ferromagnetic component of claim 1, having a tenacity K.sub.iC greater than or equal to 4 MPa.Math.m.sup.1/2, wherein the carbide phase comprises predominantly molybdenum carbide, and wherein the metallic binder phase comprises gold and copper.

14. The non-ferromagnetic component of claim 1, having a tenacity KiC greater than or equal to 8 MPa.Math.m.sup.1/2, wherein the carbide phase comprises predominantly molybdenum carbide, and wherein the metallic binder phase comprises palladium.

15. The non-ferromagnetic component of claim 1, having, in a CIELAB color space, a component L* in a range of from 60 to 90.

16. The non-ferromagnetic component of claim 1, having, in a CIELAB color space, a component L* in a range of from 77 to 85, and wherein the carbide phase comprises predominantly molybdenum carbide.

17. The non-ferromagnetic component of claim 1, which is an external part component or movement in watchmaking.

18. A non-ferromagnetic component suitable for a timepiece or piece of jewellery, the non-ferromagnetic component comprising: a cermet material comprising a carbide phase and a metallic binder phase of a metallic binder, wherein the metallic binder comprises silver, gold, platinum, palladium, rhodium, osmium, ruthenium, or an alloy thereof, wherein the metallic binder phase is present in a range of from 6 to 25 wt. %, wherein the carbide phase is molybdenum carbide is present in a range of from 75 to 94 wt. %, and wherein the non-ferromagnetic component is free from nickel and cobalt.

19. The component of claim 18, wherein the metallic binder phase is present in a range of from 6 to 22 wt. %, and wherein the carbide phase is present in a range of from 78 to 94 wt. %.

20. The component of claim 18, having a hardness HV30 in a range of from 700 to 1900.

21. The component of claim 18, having a tenacity K.sub.iC greater than or equal to 2 MPa.Math.m.sup.1/2.

22. The component of claim 18, having, in a CIELAB color space, a component L* in a range of from 60 to 90.

23. The component of claim 18, which is an external part component or movement in watchmaking.

Description

BRIEF DESCRIPTION OF THE FIGURE

[0018] FIG. 1 represents a timepiece comprising a middle made with the cermet type material according to the invention.

[0019] FIG. 2 represents an electron microscopy image of the cermet type material for a composition according to the invention (80% Mo.sub.2C—15% Au and 5% Cu).

[0020] FIG. 3 represents an electron microscopy image of the cermet type material for a further composition according to the invention (80% TiC—2% SiC—18% Pt).

DETAILED DESCRIPTION

[0021] The present invention relates to a component particularly for a timepiece or piece of jewellery made of a cermet type material comprising a majority carbide phase and a minority phase of a metallic binder including a precious element such as silver, gold, platinum, palladium, ruthenium, osmium, rhodium or an alloy of one of these precious elements. Preferably, the metallic binder is chosen from silver, gold, platinum, palladium or an alloy of one of these precious elements. The component according to the invention can form a decorative article such as a constituent element of watches, pieces of jewellery, bracelets, etc. In the watchmaking field, this component can be an external part such as a middle, a back, a bezel, a push-piece, a bracelet link, a dial, a hand, a dial index, etc. It can also consist of a component of the movement such as an oscillating mass, a plate, etc. By way of illustration, a middle 1 made with the cermet type material according to the invention is represented in FIG. 1.

[0022] The cermet component is produced by sintering from a mixture of the carbide and metallic powders. The manufacturing process includes steps of: [0023] a) Producing a mixture with the different powders, optionally in a wet environment. The powders of the mixture preferably have a d50 less than 20 μm, more preferably less than 10 μm and even more preferably less than 5 μm. The mixture can optionally be produced in a mill to obtain the sought d50. The particle size distribution is measured by laser diffraction in accordance with the standard ISO 13320: 2020.

[0024] This mixture contains by weight between 75 and 97%, advantageously between 78 and 97%, and more advantageously between 78 and 94%, of the carbide powder and between 3 and 25%, advantageously between 3 and 22%, and more advantageously between 6 and 22% of the metallic powder. The mixture can optionally contain one or more additives in a weight percentage for all of the additives less than or equal to 4%. In the presence of one or more additives, the latter are preferably present in a percentage for all of the additives between 1 and 3% by weight. More specifically, in the presence of one or more additives, the mixture includes the carbide powder in a weight percentage between 75 and 96%, the metallic binder powder in a weight percentage between 3 and 24% and the additive(s) in a weight percentage for all of the additives between 1 and 3%. These additives are aimed at improving densification during sintering. For example, they may consist of metallic di-silicide such as Si.sub.2Ti or Si.sub.2Zr.

[0025] Preferably, the carbide powder includes one or more carbides chosen from TiC, SiC, Mo.sub.2C, WC and NbC. More specifically, the carbide powder contains predominantly titanium carbide (TiC), tungsten carbide (WC) or molybdenum carbide (Mo.sub.2C). Predominantly means that, when there are several types of carbides in the powder, titanium carbide (TiC), tungsten carbide (WC) or molybdenum carbide (Mo.sub.2C) are present in a greater percentage than the other carbides. It can thus contain Mo.sub.2C and TiC with Mo.sub.2C predominantly present. It can also contain Mo.sub.2C and TiC with TiC predominantly present. It can also contain TiC and SiC with TiC predominantly present. Alternatively, it can, apart from impurities, consist entirely of TiC, WC or Mo.sub.2C. The metallic powder contains predominantly palladium, platinum, silver, gold, ruthenium, osmium, rhodium or an alloy of one of these elements. It can, apart from impurities, consist entirely of platinum, palladium, ruthenium, osmium, rhodium or silver. Gold is preferably present in alloyed form with at least one element chosen from Cu, Ag, Pd, In. More specifically, the gold alloy contains gold alloyed with silver and copper (3N yellow gold, 5N red gold) or palladium (white gold). The metallic powder can also contain carbon in a weight percentage between 0.1 and 5% with respect to the total weight of the powder mixture. Indeed, during sintering, some of the Mo.sub.2C can be converted to Mo resulting in a decrease in hardness. Adding carbon makes it possible to limit Mo formation and therefore maintain the hardness level. Alternatively, carbon can be added in the carbide powder. The carbide powder thus contains carbon in a weight percentage between 0.1 and 5% with respect to the total weight of the powder mixture.

[0026] By way of example, the powder mixture can contain one of the following distributions by weight: [0027] between 80 and 95% of TiC and between 5 and 20% of Pd or Pt, [0028] between 75 and 95% of TiC and between 5 and 25% of an Au alloy, [0029] between 50 and 70% of TiC, between 5 and 30% of Mo.sub.2C, and between 5 and 30% of an Au alloy, preferably between 55 and 65% of TiC, between 10 and 25% of Mo.sub.2C, and between 5 and 25% of an Au alloy, [0030] between 70 and 85% of TiC, between 5 and 10% of Mo.sub.2C, and between 5 and 20% of Pd or Pt, [0031] between 75 and 85% of TiC, between 2 and 10% of SiC, and between 5 and 23% of Pd or Pt, [0032] between 80 and 97% of Mo.sub.2C and between 3 and 20% of Pd, Pt, Ag or an Au alloy, [0033] between 75 and 95% of Mo.sub.2C and between 5 and 25% of an Au alloy, [0034] between 75 and 95% of WC and between 5 and 25% of Pd or Pt, [0035] between 80 and 95% of WC and between 5 and 20% of an Au alloy.
Optionally, a second mixture comprising the mixture cited above and an organic binder system (paraffin, polyethylene, etc.) can be made. [0036] b) Form a blank by giving the mixture the shape of the desired component, for example, by injection or by pressing in a mould. [0037] c) Sinter the blank in an inert atmosphere or in a vacuum at a temperature between 1000 and 1900° C. for a period between 30 minutes and 10 hours, preferably between 30 minutes and 5 hours. This step can be preceded by one or more debinding steps in a temperature range between 60 and 800° C. if the mixture contains an organic binder system.

[0038] The blank thus obtained is cooled and polished. It can also be machined before polishing to obtain the desired component.

[0039] The component, which can also be referred to as article, from the manufacturing process contains the carbide phase and the metallic phase in weight percentages close to those of the initial powders. However, it is not possible to rule out slight variations of compositions and percentages between the base powders and the material from the sintering following, for example, contaminations or transformations, for example, Mo.sub.2C to Mo. As such, in the final product from the process, the mass percentages for the different phases must be understood as follows. The carbide phase is distinguished from the metallic phase, also referred to as metallic binder. The carbide phase contains carbides as well as any elements derived from basic carbide powder derivatives such as Mo for the example above. Similarly, for the metallic phase, it contains the compounds of the initial metallic powder as well as an optional compound from a decomposition or reaction of the metallic base powder. In the presence of additives in the powder mixture, the latter can be detected in the carbide phase and/or in the metallic phase.

[0040] The component has a CIELAB colour space (according to the CIE No. 15, ISO 7724/1, DIN 5033 Teil 7, ASTM E-1164 standard) with a brightness component L*, representative of how the material reflects light, between 60 and 90, preferably between 65 and 85 and, more preferably between 70 and 85.

[0041] The ceramic material has a hardness HV30 between 700 and 1900 according to the types and percentages of the constituents. More specifically, it has a hardness HV30 between 700 and 1300 when the carbide phase contains predominantly molybdenum carbide. A hardness HV30 between 900 and 1600 when the carbide phase contains predominantly tungsten carbide and a hardness HV30 between 700 and 1900 when the carbide phase contains predominantly titanium carbide.

[0042] The ceramic material has a tenacity Kc of at least 2 MPa.Math.m.sup.1/2 with values potentially exceeding 20 MPa.Math.m.sup.1/2. The tenacity is determined on the basis of the crack length measurements at the four ends of the diagonals of the Vickers hardness imprint according to the formula:

[00001]$K\text{?}=0.0319\frac{P}{{\mathrm{al}}^{1/2}}\text{?}\text{indicates text missing or illegible when filed}$

where P is the load applied (N), a is the half-diagonal (m) and l is the measured crack length (m).

[0043] Tables 1 to 3 hereinafter contain various examples of cermets according to the invention.

[0044] 27 powder mixtures were prepared in a mill in the presence of a solvent. The mixtures were produced without binder. They were compacted in chip form by uniaxial pressure and sintered in a vacuum or under a partial argon pressure between 5 and 100 mbar at a temperature which is dependent on the powder composition. After sintering, the samples were polished plane mechanically.

[0045] Table 1 contains tests No. 1 to 9 with a carbide phase comprising TiC, Mo.sub.2C or TiC and Mo.sub.2C and with a binder phase comprising Pd, Au or an Au alloy. For test 7, 0.5% of C is added to limit Mo formation.

[0046] Table 2 contains tests No. 11 to 18 with a carbide phase comprising TiC, TiC and Sic or Ti and Mo.sub.2C and with a binder phase comprising Pt or

[0047] Pd. In test 16, the powder mixture contains an additive to improve densification. This additive is Si.sub.2Ti present in a weight percentage of 2%.

[0048] Table 3 contains tests No. 19 to 27 with a carbide phase comprising Mo.sub.2C or WC and with a binder phase comprising Pd, Pt, Ag, an Ag alloy or an Au alloy.

[0049] HV30 hardness measurements were made on the surface of the samples and the tenacity was determined based on the hardness measurements as described above.

[0050] The Lab colorimetric values were measured on the polished samples with a KONICA MINOLTA CM-5 spectrophotometer under the following conditions: SCI (specular component included) and SCE (specular component excluded) measurements, inclination of 8°, 8 mm diameter MAV measurement zone.

[0051] It is apparent from these tests that the cermets with a carbide phase containing predominantly TiC have as a whole a greater hardness than that of the cermets with a carbide phase containing predominantly Mo.sub.2C. The hardnesses are thus between 750 and 1800 HV30 for the cermets comprising TiC compared to values within the 750-1200 HV30 range for cermets comprising predominantly Mo.sub.2C. Sample 4 containing TiC and an Au alloy has a lower hardness (761 HV30) attributed to a lower sintering time compared to sample 3 containing TiC and an Au alloy (1209 HV30). Sample 4 moreover has a lower tenacity compared to sample 3.

[0052] The cermets comprising Mo.sub.2C and Pd have extremely high tenacity values which are greater than 10 MPa.Math.m.sup.1/2 for Pd contents greater than or equal to 8% (tests 6, 20, 21). For certain compositions, there are no crack propagations during the HV30 hardness measurements, hence a tenacity value could not be measured.

[0053] The cermets comprising predominantly Mo.sub.2C have high brightness indexes L* regardless of the type of precious binder used (Pt, Pd, Ag, Au—Cu) with values of the order of 80 as opposed to values within the 70-75 range for cermets comprising predominantly TiC.

[0054] A cermet composed solely of tungsten carbides, at a rate of 80% by mass, and of 20% palladium as precious metal binder, has a high hardness (1472 HV30) and a good tenacity (6.3 MPa.Math.m.sup.1/2) which makes it a good candidate for producing functional parts such as an oscillating mass, also given the high density thereof.

[0055] In terms of microstructures, FIG. 2 represents an electron microscopy image of a sintered sample from the powder mixture comprising 80% Mo.sub.2C, 15% Au and 5% Cu by weight. The carbide phase is formed from the dark grey zone composed of Mo.sub.2C and the Mo-rich medium grey zone. Some of the Mo.sub.2C converted to Mo during sintering resulting in a decrease in hardness. The metallic phase AuCu is the white phase.

[0056] FIG. 3 represents an electron microscopy image of a sintered sample from the powder mixture comprising 80% TiC, 2% SiC and 18% Pt by weight. There is the carbide phase formed from the black and grey zones with the TiC-rich black zone and the grey zone comprising TiC and Pt. The metallic phase is in white.

[0057] As explained above, the invention relates to the component made of a cermet material. This component was devised for applications particularly in the field of watchmaking and jewellery such as for example elements of external parts or the movement of a timepiece. Obviously, the component according to the invention would not be restricted to watchmaking. Thus, by way of non-limiting example, it is also conceivable that this component can be applied in the field of tableware, cutlery, leatherware, or jewellery.

TABLE-US-00001 TABLE 1 Size Sintering Properties Composition (wt) d50 T time KiC No. Carbides Binder (μm) (° C.) (min) HV30 (MPa .Math. m½) L* a* b* (1) 84% TiC 16% Pd 0.68 1500 90 1583 6.1 70.39 0.69 4.29 84% TiC 16% Pd 0.68 1700 90 1655 4.9 / / / (2) 80% TiC 15% Au—5% Cu 0.72 1400 180 1256 6 73.02 0.85 1.15 (3) 80% TiC 20% Au3N* 0.50 1400 180 1209 7.5 73.10 0.75 1.37 (4) 79% TiC 21% Au5N* 0.76 1400 90 761 6.0 71.16 1.33 1.79 (5) 80% Mo2C 15% Au—5% Cu 0.89 1200 180 756 12.5 81.33 1.13 3.19 80% Mo2C 15% Au—5% Cu 0.89 1250 180 766 12.6 81.17 1.15 3.34 (6) 86% Mo2C 14% Pd 0.69 1250 90 757 >20 81.06 0.22 2.19 86% Mo2C 14% Pd 1.69 1500 90 839 >20 80.89 0.31 2.15 (7) 79.2% Mo2C 15.2% Au—5.1% Cu—0.5% C 0.90 1150 90 922 8.8 80.61 1.08 3.56 79.2% Mo2C 15.2% Au—5.1% Cu—0.5% C 0.90 1450 90 984 4.9 80.79 0.74 3.13 (8) 84% Mo2C 12% Au—4% Cu 0.78 1150 90 874 11.4 80.88 0.92 3.16 (9) 20% Mo2C—60% TiC 15.2% Au—4.8% Cu 0.60 1300 90 1224 5.6 73.64 1.12 2.03 20% Mo2C—60% TiC 15.2% Au—4.8% Cu 0.60 1450 90 1188 6.5 74.03 1.05 1.91 / = not measured *20% Au3N = 15%Au—3.2%Ag—1.8%Cu; 21% Au5N = 15.75%Au—4.2%Cu—1.05%Ag

TABLE-US-00002 TABLE 2 Size Sintering Properties Composition (wt) d50 T time KiC No. Carbides Binder (μm) (° C.) (min) HV30 (MPa .Math. m½) L* a* b* (11) 85% TiC 15% Pt 0.95 1400 60 1555 3.3 71.79 −0.34 −0.47 85% TiC 15% Pt 0.95 1500 90 1720 3.1 71.95 −0.32 −0.57 (12) 90% TiC 10% Pt / 1500 90 1746 2.1 72.87 −0.07 0.15 (13) 80%TiC—2%SiC 18% Pt 0.32 1500 60 1561 3.0 73.14 0.08 0.24 80%TiC—2%SiC 18% Pt 0.32 1650 60 1486 3.3 72.10 −0.20 −0.06 (14) 80%TiC—5%SiC 15% Pt 0.59 1400 60 1313 3.1 71.82 0.56 0.42 80%TiC—5%SiC 15% Pt 0.59 1500 60 1498 2.7 72.49 0.52 0.35 (15) 80%TiC—10%SiC 10% Pt 0.73 1400 60 1528 2.7 70.96 0.37 0.25 80%TiC—10%SiC 10% Pt 0.73 1500 60 1585 3.0 71.35 0.37 0.25 (16) 80%TiC—2%Si2Ti 18% Pt 1.43 1500 60 1605 3.2 72.82 −0.11 0.12 80%TiC—2%Si2Ti 18% Pt 1.43 1650 60 1497 3.4 71.59 −0.35 −0.41 (17) 77.5%TiC—7.5%Mo2C 15.5% Pt 1.10 1450 90 1755 3.4 72.21 0.19 −0.17 77.5%TiC—7.5%Mo2C 15.5% Pt 1.10 1650 60 1583 4.1 70.52 0.94 0.19 (18) 77.5%TiC—7.5%Mo2C 15.5% Pd 0.89 1450 60 1570 3.2 73.40 0.44 0.18 77.5%TiC—7.5%Mo2C 15.5% Pd 0.89 1500 60 1561 3.1 72.94 0.40 0.10

TABLE-US-00003 TABLE 3 Size Sintering Properties Composition (wt) d50 T time K1C No. Carbide Binder (μm) (° C.) (min) HV30 (MPa .Math. m½) L* a* b* (19) 93% Mo2C 7% Pt 0.91 1650 30 1125 3.8 80.33 0.22 2.06 (20) 90% Mo2C 10% Pd 0.67 1350 90 710 12.0 80.78 0.17 1.83 (21) 92% Mo2C 8% Pd 0.86 1350 90 743 11.8 81.00 0.15 1.82 (22) 94% Mo2C 6% Pd 0.75 1350 90 893 3.6 81.21 0.11 1.94 (23) 78% Mo2C 15% Au—5%Cu—2%C 1.05 1400 60 1183 3.5 80.72 0.33 2.66 (24) 90% Mo2C 10% Ag 0.75 1400 60 962 4.6 81.02 0.34 1.95 (25) 92% Mo2C 8% Sterling 925 Ag 0.73 1300 90 887 4.6 81.12 0.49 2.50 92% Mo2C 8% Sterling 925 Ag 0.73 1400 90 946 3.9 81.80 0.38 2.35 (26) 80% WC 20% Pd 2.85 1400 60 1472 6.3 75.81 0.13 0.38 (27) 90% WC 7.5% Au—2.5% Cu 0.58 1450 90 972 5.7 72.49 0.14 1.20 90% WC 7.5% Au—2.5% Cu 0.58 1550 90 1486 4.3 73.82 −0.01 0.67