EP2776597B1 - Gold timepiece or jewellery part - Google Patents

Description

Field of the invention

The invention relates to a timepiece or jewelery made of a gold alloy.

The invention also relates to a gold-based alloy, called 18-carat red gold, and more particularly to such an alloy having improved discoloration characteristics.

The invention relates to the field of metallurgy of gold alloys for watchmaking, jewelery and jewelery.

Background of the invention

The standard 5N red gold according to the ISO 8654 standard (of composition Au750Cu205Ag45) is currently the most used alloy on the watch market, particularly for the production of watch-making parts, typically watch cases, bracelets etc. Unfortunately , this interesting red gold alloy looks faded over time and slowly changes from its initial red color to the yellow color. This phenomenon frequently leads to complaints from customers dissatisfied with this transformation. The origin of this discoloration is the selective dissolution of the Cu close to the surface, generating an increase in the concentration of Au on the yellowing surface of the alloy. We already know EP Patent 1,512,766 A1 a red gold alloy with platinum addition, which increases the fade resistance vis-à-vis the previous red gold alloys. However this gold alloy still has, although slower, a color change that can be improved under certain conditions to wear such as when subjected to sweat to acid rain. In addition, we know that platinum is an element with a very high melting point (1768 ° C) requiring mixtures of preparations with other specific elements (Au and / or Cu) in order to lower its melting temperature which makes the implementation of the more complicated and more expensive alloy. Indeed, without the addition of these alloying elements, the platinum does not dissolve homogeneously in gold and makes it mechanically more difficult to deform for some horological applications.

The document JP 10 245646 discloses an 18-carat gold alloy comprising between 15.0 and 23.0% copper and between 0.3 and 5.0% palladium.

Also, platinum remains a very expensive metal that increases the alloy.

Summary of the invention

The present invention therefore aims to overcome the drawbacks of the aforementioned prior art by providing a timepiece, jewelery or jewelery made in a red gold alloy, 18 carats with improved fade resistance compared to to red gold alloys, typically 5N gold of the prior art.

The invention also aims to provide a timepiece, jewelery or jewelery made in a red gold alloy, 18 carats alloy preparations with lower melting points to facilitate its implementation implemented.

The invention also aims to provide a timepiece, jewelery or jewelery made in a red gold alloy, 18 carats with lower alloy costs.

For this purpose, the invention relates to a timepiece, jewelery or jewelry according to claim 1 of the patent.

The invention also relates to a gold-based alloy, called 18-carat red gold, according to claim 9 of the patent.

Advantageously, the gold-based alloy (including that of the timepiece of the invention) comprises 1.4% by weight of palladium.

Preferably, the gold-based alloy (including that of the piece of the invention) further comprises between 0.45 and 2.0% by weight of a member selected from the group consisting of iron, zinc, silver and indium or a combination of these latter.

According to a preferred embodiment, the gold-based alloy (including that of the timepiece of the invention) comprises 0.48% by weight of platinum.

According to another preferred embodiment, the gold-based alloy (including that of the timepiece of the invention) further comprises 1.81% by weight of silver.

Advantageously, the gold-based alloy (including that of the timepiece of the invention) further comprises by weight at most 1.0% of any one or a combination of the elements chosen from the set comprising gallium, magnesium, calcium, lithium, aluminum, sodium, titanium, molybdenum, tin, silicon, rhodium, zirconium, potassium, and chromium.

Preferably, the gold-based alloy (including that of the timepiece of the invention) comprises, by weight, at most 0.05% of iridium, rhenium, or ruthenium and, advantageously, The alloy comprises by weight 0.01% iridium.

It has been found that timepieces or jewelery as defined by the appended claims are very interesting from the point of view of their color, their brightness and their price.

Brief description of the drawings

• la figure 1 représente, le changement de couleur ΔE pour les alliages No126, No128, No129 et No139 et deux ors rouges 18 carats de l'art antérieur à savoir les alliages No 113 et No 103 en fonction du temps dans un test NaCl saturé à 70°C.
• la figure 2 représente, le changement de couleur ΔE pour les alliages No126, No 128, No 129 et No 139 et deux ors rouges 18 carats de l'art antérieur à savoir les alliages No113 et No103 en fonction du temps dans un test de sueur synthétique à 40°C
• la figure 3 représente, le changement de couleur ΔE pour les alliages N°126, N°128, N°129 et N°139 et deux ors rouges 18 carats de l'art antérieur à savoir les alliages No113 et No103 en fonction du temps dans un test de pluie acide à 70°C.

Other features and advantages of the invention will appear on reading the detailed description which follows, with reference to the appended drawings, in which:

• the figure 1 represents the color change ΔE for the alloys No126, No128, No129 and No139 and two 18-carat red golds of the prior art, namely the alloys Nos. 113 and 103 as a function of time in a NaCl test saturated at 70 ° C. .
• the figure 2 represents the ΔE color change for alloys No126, No.128, No.129 and No.139 and two 18-carat red golds of the prior art ie alloys No113 and No103 as a function of time in a synthetic sweat test at 40 ° C
• the figure 3 represents the color change ΔE for the alloys No. 126, No. 128, No. 129 and No. 139 and two 18-carat red golds of the prior art, namely the alloys No113 and No103 as a function of time in a test acid rain at 70 ° C.

Table 1 shows examples of alloy compositions in weight according to the invention with the exception of alloys No. 103 and No. 113 which respectively represent 18-carat red gold alloy compositions of the prior art. <u> Table 1 </ u> No. At. Pd. Cu. Pt. Ag . Ir. 126 773.9 14.0 212.0 0.1 128 769.1 14.0 212.0 4.8 0.1 129 751.0 14.0 212.0 4.8 18.1 0.1 139 751.0 14.0 216.8 18.1 0.1 103 750.7 204.3 45 113 765 210 25

Each of these gold alloys was subjected to three bleaching tests respectively in a solution of saturated sodium chloride, in a solution of synthetic sweat and in an acid rain solution and the discoloration of each alloy was measured. Table 2 gives the compositions of the test solutions and the thermal conditions in which they were used. The compositions of the tests "synthetic sweat" and "acid rain" represent conditions that a timepiece can suffer to wear especially in Asian climatic regions. <u> Table 2 </ u> Test T (° C) Formula 70 Saturated NaCl - DI water - NaCl until saturation (at 70 ° C) 40 Synthetic sweat Acid sweat "Citizen type" - DI water - Sodium chloride: 9.9 g / l - Sodium sulphide: 0.8 g / l - Urea: 1.7 g / l - Lactic acid: 1.4 ml / l - Sucrose: 0.2 g / l Ammonia NH ₃ · H ₂ O: 0.22 ml / l - Hydrochloric acid: quantity necessary for bring the pH to 3.6 (at 25 ° C) 70 Acid rain Composition "Hangzhou" (pH = 4.5): - DI water - NaF: 5.8 μmol / l MgCl ₂ : 7.1 μmol / l - CaSO ₄ : 52 μmol / l KNO ₃ : 5 μmol / l HNO ₃ : 31.4 μmol / l - (NH ₄ ) SO ₄ : 40 μmol / l Na ₂ SO ₄ : 18 μmol / l The three discoloration tests were carried out on gold alloy rings having a diameter of 20 mm and a thickness of 2.5 mm. The washers were polished successively with grain abrasive papers 320, 600, 1200, 2400 to the felt containing diamond particles of 3 to 1 μm in average diameter.

Each pellet was immersed in 200 ml of a solution corresponding to the tests shown in Table 2 for 42 days. Each washer was placed at the bottom of a closed bottle (∅ 65 mm, made of polypropylene). For statistical reasons, 3 slices of each alloy of Table 1 were tested for each of the three tests.

The washers were removed and rinsed to measure the discoloration at different times during the test period and to see the evolution. The curves of Figures 1 to 3 have been traced.

où L*, a*, b* sont les valeurs colorimétriques des échantillons mesurés avec un colorimètre « Varian Cary 1 E» doté d'une sphère d'intégration de 70mm.The color change or discoloration ΔEi after i days has been calculated according to the following formula: $$\mathrm{\Delta }{E}_i=\sqrt{{\left({\mathrm{The}}_i^{*}-{\mathrm{The}}_0^{*}\right)}^2+{\left({\mathrm{at}}_i^{*}-{\mathrm{at}}_0^{*}\right)}^2+{\left(b_i^{*}-{\mathrm{<figure-callout\; id="0"\; label="b"\; filenames="imgf0001.png,imgf0002.png"\; state="\{\{state\}\}">b</figure-callout>}}_0^{*}\right)}^2}\mathrm{.}$$

where L *, a *, b * are the colorimetric values of the samples measured with a "Varian Cary 1 E" colorimeter with a 70mm integrating sphere.

The results of the discoloration test in the saturated NaCl solution at 70 ° C show that the red gold alloys according to the invention, alloys No. 126, No. 128, No. 129 and No. 139 discolour significantly less rapidly than the 18-carat red gold alloy of the prior art No. 103 in this saline atmosphere. These results are illustrated in figure 1 where it can be seen that the variation of ΔE between alloy No. 103 of the prior art and alloy No. 129 according to the invention changes from 1.5 after 2 days to practically 3 after a period of 42 days.

The results of the discoloration test in the synthetic sweat solution at 40 ° C. show that the red gold alloys according to the invention, alloys No. 126, No. 128, No. 129 and No. 139 discolour distinctly. slower than the 18-carat red gold alloy of the prior art No. 103 in this atmosphere of sweat. These results are illustrated in figure 2 where it can be seen that the variation of ΔE between alloy No. 103 of the prior art and alloy No. 129 according to the invention changes from 0.4 after 2 days to practically 0.8 after a period of 42 days.

The results of the discoloration test in the acid rain solution at 70 ° C show that the red gold alloys according to the invention alloys: No. 126, No. 128, No. 129 and No. 139, discolor significantly less rapidly that the 18-carat red gold of the prior art No. 113 in this acidic atmosphere. These results are illustrated in figure 3 where it can be seen that the variation of ΔE between alloy No. 113 of the prior art and alloy No. 129 according to the invention changes from 0.5 after 5 days to practically 2 after a period of 40 days.

These tests clearly show that the fade resistance of the alloys according to the invention is clearly better compared to the 18-karat gold alloys of the prior art in saline and acidic atmospheres and slightly better in the case of the test to the synthetic sweat.

Claims (16)

1. Timepiece, or piece of jewellery fabricated in an 18 carat red gold, nickel-free and cobalt-free alloy whose composition comprises, by weight, between 75% and 77.5% of gold, between 1.35 and 1.45% of palladium, between 20.1 and 23.8% of copper, said alloy being silver-free and when said alloy includes silver, said alloy includes 1.81% by weight of silver, said alloy further includes, by weight, possibly between 0.45 and 2.0% of one element selected from among iron, zinc, silver and indium or a combination thereof, possibly 0.48% of platinum, possibly at most 1.0% of any one element or a combination of elements selected from among gallium, magnesium, calcium, lithium, aluminium, sodium, titanium, molybdenum, tin, silicon, rhodium-zirconium, potassium and chromium, and possibly at most 0.05% by weight of one element selected from among iridium, rhenium and ruthenium.
2. Timepiece or piece of jewellery according to claim 1, characterized in that the alloy comprises 1.4% by weight of palladium.
3. Timepiece or piece of jewellery according to claim 1, characterized in that the alloy further comprises between 0.45 and 2,0% by weight of an element selected from among iron, zinc, silver and indium or a combination thereof.
4. Timepiece or piece of jewellery according to claim 3, characterized in that the alloy comprises 0.48% by weight of platinum.
5. Timepiece or piece of jewellery according to claim 4, characterized in that the alloy comprises 1.81% by weight of silver.
6. Timepiece or piece of jewellery according to any of claims 1 to 5, characterized in that the alloy comprises at most 1.0% by weight of any one element or of a combination of elements chosen from among gallium, magnesium, calcium, lithium, aluminium, sodium, titanium, molybdenum, tin, silicon, rhodium-zirconium, potassium and chromium.
7. Timepiece or piece of jewellery according to any of claims 1 to 5, characterized in that the alloy includes a maximum of 0.05% by weight of an element chosen from among iridium, rhenium, ruthenium.
8. Timepiece or piece of jewellery according to claim 7, characterized in that the alloy comprises 0.1 % by weight of iridium.
9. 18 carat red gold, nickel-free and cobalt-free alloy characterized in that the alloy comprises, by weight:

   - between 75% and 77.5% of gold,

   - from 1.35% to 1.45% of palladium,

   - from 20.1 to 23.8% of copper, said alloy being silver-free and when said alloy includes silver, said alloy includes 1.81% by weight of silver, said alloy further includes, by weight, possibly between 0.45 and 2.0% of one element selected from among iron, zinc, silver and indium or a combination thereof, possibly 0.48% of platinum, possibly at most 1.0% of any one element or a combination of elements selected from among gallium, magnesium, calcium, lithium, aluminium, sodium, titanium, molybdenum, tin, silicon, rhodium-zirconium, potassium and chromium, and possibly at most 0.05% by weight of one element selected from among iridium, rhenium and ruthenium.
10. Gold-based alloy according to claim 9, characterized in that the palladium content by weight is 1.4%.
11. Gold-based alloy according to any of claims 9 or 10, characterized in that the alloy comprises between 0.45% and 2.0% by weight of an element selected from among the group including iron, zinc, silver and indium or a combination thereof.
12. Gold-based alloy according to claim 11, characterized in that the alloy includes 0.48% by weight of platinum.
13. Gold-based alloy according to claim 12, characterized in that the alloy includes 1.81% by weight of silver.
14. Gold-based alloy according to any of claims 9 to 13, characterized in that the alloy includes a maximum of 1.0% by weight of any one element or a combination of elements selected from the group including gallium, magnesium, calcium, lithium, aluminium, sodium, titanium, molybdenum, tin, silicon, rhodium, zirconium, potassium and chromium.
15. Gold-based alloy according to any of claims 9 to 13, characterized in that the alloy comprises a maximum of 0.05% by weight of any one element or a combination of elements selected from the group including iridium, rhenium and ruthenium.
16. Gold-based alloy according to claim 15, characterized in that the alloy includes 0.01% by weight of iridium.

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