Platinum alloy

Abstract

This disclosure relates to a platinum alloy for use in jewelry: - Platinum at 920‰ to 980‰ weight; - Tin in quantities of 5 m / s to 35 m / s; - Ruthenium in 8 wt‰ to 45 wt‰ or copper in 2 wt‰ to 45 wt‰; Regarding platinum alloys.

Description

Technical Field

[0001] Technical Field The present disclosure relates to the field of metallurgy, particularly to the field of platinum alloys. In particular, the present disclosure relates to platinum alloys for jewelry applications.

[0002] The present disclosure also relates to jewelry items obtained using the platinum alloys described herein.

Background Art

[0003] Background Art Platinum alloys are metal alloys that can be used for jewelry applications. In particular, platinum alloys can be advantageously used for obtaining watch mechanisms due to their mechanical and functional properties.

[0004] These mechanisms can be hidden by the back cover or, alternatively, can complete the aesthetics of the item itself by showing it. In this particular case, typically, a transparent part made of, for example, sapphire crystal or plastic material is provided on the back cover, thereby enabling the internal mechanism to be observed when the user is not wearing the watch.

[0005] Platinum alloys can also be used for making jewelry items such as watches or bracelet parts that are intended to come into direct contact with a person's skin.

[0006] In jewelry applications, the brightness or luster of the alloy plays an important role. The higher it is, the higher the aesthetic quality of the item, and as a result, the higher the value of the alloy. In the CIELAB system, this property is defined using the coordinate L*.

[0007] Platinum alloys intended for jewelry applications must possess optimal processing characteristics, and in particular, they must be able to withstand all mechanical operations commonly used in the manufacture of gemstone jewelry or watch components. Specifically, they must not develop defects such as cracks or breakage when subjected to plastic deformation (rolling, drawing, etc.) and / or machining processes involving chip removal.

[0008] In the application areas under consideration, platinum and ruthenium alloys are known for machining; in particular, binary alloys consisting of 950 wt‰ platinum and 50 wt‰ ruthenium are known. Such alloys are characterized by high melting temperatures exceeding 1700°C, and in practice, they have limitations in machinability, especially in the chip removal process. For example, the diamond polishing process is widely used for other precious metal alloy systems, especially gold alloys of different carat weights, but it is hardly applicable to the fabrication of parts made from platinum and ruthenium binary alloys.

[0009] British Patent Application Publication No. 546897A discloses improvements to platinum alloys for use in jewelry and dental applications, in particular an alloy comprising at least 82% platinum and 0.35–5% tin, with the remainder being primarily one or more other metals of the platinum group, each metal present in amounts of 0.5% or more. Similarly, U.S. Patent No. 2273806A discloses a platinum alloy containing a small amount of tin for use in jewelry and dental applications. [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The purpose of this disclosure is to describe a platinum alloy that enables better processability. [Means for solving the problem]

[0011] overview To overcome the aforementioned drawbacks and, in particular, to obtain an alloy with optimal processing characteristics, the applicant has devised platinum alloys according to the embodiments described herein. These embodiments may be combined with each other or with parts of the detailed description or claims.

[0012] According to this disclosure, this disclosure relates to a platinum alloy for use in jewelry: - Platinum at 920‰ to 980‰ weight; - Tin in quantities of 5 m / s to 35 m / s; - Ruthenium in 8 wt‰ to 45 wt‰ or copper in 2 wt‰ to 45 wt‰; Regarding platinum alloys.

[0013] In a further non-limiting embodiment, tin is present in amounts of 10 wt‰ to 30 wt‰, preferably 12 wt‰ to 28 wt‰.

[0014] In a further non-limiting embodiment, copper is present in amounts of 4 wt‰ to 41 wt‰, preferably 8 wt‰ to 39 wt‰, more preferably 8 wt‰ to 34 wt‰.

[0015] In a further non-limiting embodiment, ruthenium is present in amounts of 10 wt‰ to 43 wt‰, preferably 15 wt‰ to 38 wt‰, more preferably 15 wt‰ to 35 wt‰.

[0016] In a further, less restrictive embodiment, the platinum is present in an amount of 930‰ to 970‰, preferably 940‰ to 960‰.

[0017] In a further, less restrictive embodiment, the alloy is: - Tantalum in amounts of 2 wt‰ to 30 wt‰, preferably 4 wt‰ to 25 wt‰, more preferably 8 wt‰ to 20 wt‰ and / or - Niobium in quantities of 2 wt‰ to 20 wt‰, preferably 4 wt‰ to 15 wt‰, more preferably 5 wt‰ to 10 wt‰ include.

[0018] According to a further non-limiting aspect, the sum of the weights of platinum, tin, ruthenium, tantalum and / or niobium, or the sum of the weights of platinum, tin, copper, tantalum and / or niobium, is determined to reach 1000‰ with respect to the weight of the alloy.

[0019] According to a further non-limiting aspect, the sum of the weights of platinum, tin and ruthenium is determined to reach 1000‰ with respect to the weight of the alloy.

[0020] According to a further non-limiting aspect, the sum of the weights of platinum, tin and copper is determined to reach 1000‰ with respect to the weight of the alloy.

[0021] According to a further non-limiting aspect, the alloy is: - chromium at 2 weight‰ to 18 weight‰, preferably 5 weight‰ to 15 weight‰; and / or - molybdenum at 2 weight‰ to 18 weight‰, preferably 5 weight‰ to 15 weight‰; contains.

[0022] According to a further non-limiting aspect, the sum of the weights of platinum, tin, ruthenium, chromium and / or molybdenum, or the sum of the weights of platinum, tin, copper, chromium and / or molybdenum, is determined to reach 1000‰ with respect to the weight of the alloy.

[0023] According to a further non-limiting aspect, the alloy is: - gallium at 5 weight‰ to 23 weight‰, preferably 8 weight‰ to 20 weight‰, more preferably 10 weight‰ to 18 weight‰; or - gold at 2 weight‰ to 14 weight‰, preferably 4 weight‰ to 12 weight‰, more preferably 6 weight‰ to 8 weight‰; or - palladium at 2 weight‰ to 18 weight‰, preferably 4 weight‰ to 16 weight‰, more preferably 6 weight‰ to 14 weight‰; contains.

[0024] In a further, less restrictive embodiment, the sum of the weights of platinum, tin, copper, gallium, gold, or palladium is determined to reach 1000‰ relative to the weight of the alloy.

[0025] In a further non-limiting embodiment, the total weight of platinum, tin, ruthenium, or platinum, tin, and copper reaches 970 wt‰ of the alloy, preferably 975 wt‰ of the alloy, and more preferably 980 wt‰ of the alloy.

[0026] In a further non-limiting embodiment, the platinum alloy contains at least one of iridium, rhenium, vanadium, indium, and hafnium in an amount of 30 wt‰ or less in total, preferably 25 wt‰ or less, and more preferably 20 wt‰ or less.

[0027] In a further non-limiting embodiment, the alloy described herein is characterized by being a ternary or quaternary alloy.

[0028] In a further non-limiting embodiment, the alloy described herein is characterized by exhibiting a color in the CIELAB 1976 color space where the coordinate L*, according to colorimetric conditions in accordance with CIE D65, is at least equal to 85.

[0029] In a further non-limiting embodiment, the alloys described herein are characterized by having a hardness equal to at least 150 on the Vickers scale, and optionally containing copper, the platinum alloy is characterized by having a hardness equal to at least 155 on the Vickers scale, or, if containing ruthenium, the platinum alloy is characterized by having a hardness equal to at least 160 on the Vickers scale, preferably at least 170 on the Vickers scale.

[0030] In a further non-limiting embodiment, the alloy comprises 930 wt‰ to 970 wt‰ of platinum, preferably 940 wt‰ to 960 wt‰, and 18 wt‰ to 35 wt‰ of ruthenium, preferably 22 wt‰ to 34 wt‰.

[0031] In accordance with this disclosure, a platinum alloy comprising the following is also disclosed: - Platinum in a weight of 920‰ to 980‰, preferably 930‰ to 970‰, more preferably 940‰ to 960‰; - Tin in an amount of 5‰ to 35‰, preferably 10‰ to 30‰, more preferably 12‰ to 28‰; - Either way: - Ruthenium in quantities of 8 m‰ to 45 m‰; - Copper in quantities of 2 wt‰ to 45 wt‰; - At least one of the following: - Tantalum in an amount of 2 wt‰ to 30 wt‰, preferably 4 wt‰ to 25 wt‰, more preferably 8 wt‰ to 20 wt‰; and / or - Niobium, 2 wt‰ to 20 wt‰, preferably 4 wt‰ to 15 wt‰, more preferably 5 wt‰ to 10 wt‰; - Alternatively, instead of tantalum and / or niobium, at least one of the following: - Chromium in amounts of 2‰ to 18‰, preferably 5‰ to 15‰; and / or - Molybdenum in amounts of 2 wt‰ to 18 wt‰, preferably 5 wt‰ to 15 wt‰; - Alternatively, instead of tantalum and / or niobium and / or chromium and / or molybdenum, at least one of the following: - Gallium in an amount of 5 wt‰ to 23 wt‰, preferably 8 wt‰ to 20 wt‰, more preferably 10 wt‰ to 18 wt‰; or - Gold in amounts of 2 wt‰ to 14 wt‰, preferably 4 wt‰ to 12 wt‰, more preferably 6 wt‰ to 8 wt‰; or - Palladium in an amount of 2 wt‰ to 18 wt‰, preferably 4 wt‰ to 16 wt‰, more preferably 6 wt‰ to 14 wt‰.

[0032] In accordance with this disclosure, jewelry comprising a platinum alloy according to one or more embodiments thereof is described.

[0033] In a further, less restrictive embodiment, the jewelry body includes jewelry with gemstones, or a watch or watch bracelet or a movement or part of a mechanical watch movement.

[0034] In a further, less limiting embodiment, the watch bracelet is configured to be worn on the wrist, and / or the movement or part of the mechanical watch movement is configured to be attached to the wristwatch.

[0035] drawing Herein, with reference to the attached drawings, several embodiments of the platinum alloy articles of this disclosure are described, and a brief description thereof is given below. [Brief explanation of the drawing]

[0036] [Figure 1] This is a Cartesian coordinate diagram showing data on the quality of platinum alloy crystal grains on the horizontal axis and data on the brightness of the alloy, represented by coordinate L* based on CIELAB 1976, on the vertical axis. [Modes for carrying out the invention]

[0037] Detailed explanation This disclosure describes a platinum alloy for use in jewelry applications that has high machinability, particularly during chip removal and / or diamond polishing.

[0038] The applicant has confirmed that the workability of platinum alloys is related to the characteristics of their microstructure, and has conducted various studies on elements that refine the crystal grains, which play a role in improving the workability of alloys when introduced into the alloy.

[0039] The applicant has generally conducted various studies on specific compositions containing platinum in amounts of 920 wt‰ to 980 wt‰. Given the high amount of platinum and its high price, it is clear that the primary use of the platinum alloys described herein is in the manufacture of high-end jewelry and watches. This does not preclude the possibility that the platinum alloys described herein may be used in other applications. For these reasons, the use in jewelry and watchmaking is not intended to be limiting.

[0040] The platinum alloys subject to this disclosure have been studied in detail by the applicant, and in particular, when subjected to optical microscopy, they exhibit a microstructure characterized by very fine crystal grains and also show particularly high reflectivity.

[0041] The applicant focused particularly on the quality of platinum alloys in terms of average grain size, and then in terms of grain homogeneity. The applicant also noted that known platinum and ruthenium alloys exhibit remarkably high melting temperatures. In fact, the melting temperatures of platinum alloys and ruthenium are such that they can cause cracks in parts of the melting crucible, and the molten alloy may be contaminated with elements other than those of the intended composition.

[0042] For these reasons, the applicant has devised a platinum alloy containing 5 wt‰ to 35 wt‰ of tin. By incorporating tin into the platinum alloy, the melting temperature of the alloy can be lowered, resulting in a reduction in the content of impurities, and consequently, a greater degree of freedom in the selection of the melting crucible. The applicant has confirmed that the inclusion of tin contributes to improving the workability of the alloy. The applicant has also confirmed that the workability of the alloy can be improved by adding niobium in addition to tin, or by replacing part of it.

[0043] To ensure mechanical properties suitable for jewelry processing, the applicant focused primarily on two groups of platinum-tin alloys, which, in addition to the platinum and tin mentioned above, also contain ruthenium or copper.

[0044] The applicant has generally confirmed that copper contributes to a lower melting temperature compared to ruthenium. Therefore, certain formulations characterized by the presence of copper instead of ruthenium also exhibit improved machinability compared to known types of platinum alloys and are less susceptible to contamination from impurities released from the melting crucible.

[0045] The platinum alloys disclosed in this disclosure have been studied not only in terms of their performance under varying chemical compositions, but also in terms of their performance under diverse manufacturing processes.

[0046] The following table shows some specific compositions of platinum alloys studied by the applicant.

[0047] [Table 1]

[0048] The compositions shown in Table 1 are those used by the applicant for jewelry applications: - Platinum at 920‰ to 980‰ weight; - Tin in quantities of 5 m / s to 35 m / s; - Ruthenium in 8 wt‰ to 45 wt‰ or copper in 2 wt‰ to 45 wt‰; This specific composition was obtained starting from research conducted on the general platinum alloy group.

[0049] Platinum-ruthenium alloys have traditionally been used in jewelry applications, while platinum-copper alloys include compositions in which copper is present instead of ruthenium. Since copper is less expensive than ruthenium, this offers a more economical production solution.

[0050] Copper and ruthenium help impart sufficient hardness and workability to platinum alloys for jewelry applications.

[0051] From the aforementioned basic group, the applicant focused their research on the first basic subgroup in which tin is present in amounts of 10 wt‰ to 30 wt‰, preferably 12 wt‰ to 28 wt‰.

[0052] From the basic group, the applicant selected alloys in which copper is present instead of ruthenium, and in particular focused on the second subgroup of alloys in which copper is present in amounts of 4 wt‰ to 41 wt‰, preferably 8 wt‰ to 39 wt‰, and more preferably 8 wt‰ to 34 wt‰.

[0053] Alternatively, by selecting alloys from the basic group in which ruthenium is present instead of copper, the applicant focused on a third subgroup of alloys in which ruthenium is present in amounts of 10 wt‰ to 43 wt‰, preferably 15 wt‰ to 38 wt‰, and more preferably 15 wt‰ to 35 wt‰.

[0054] Further detailed studies were conducted on alloys containing 930 wt‰ to 970 wt‰, preferably 940 wt‰ to 960 wt‰, of platinum. The amount of platinum introduced herein was studied in particular with respect to compositions following the first subgroup and compositions following the second and third subgroups.

[0055] The applicant has devised several embodiments of alloys according to the disclosure in which a non-negligible amount of tantalum is present. Analysis by the applicant has shown that the presence of tantalum, in some cases replacing a portion of ruthenium, further reduces the grain size of the alloy, resulting in alloys that are characterized by higher brightness compared to platinum alloy compositions without tantalum. The applicant has also devised a group of platinum alloys in which niobium and / or chromium are present.

[0056] In particular, the applicant has a platinum alloy: - Tantalum is 2 wt‰ to 30 wt‰, preferably 4 wt‰ to 25 wt‰, more preferably 8 wt‰ to 20 wt‰ and / or - Niobium is 2 wt‰ to 20 wt‰, preferably 4 wt‰ to 15 wt‰, more preferably 5 wt‰ to 10 wt‰ We focused on existing platinum alloys.

[0057] Some of the lower group alloys containing tantalum and / or niobium in the amounts shown in the previous paragraph are quaternary alloys, and the sum of the weights of platinum, tin, ruthenium, tantalum and / or niobium, or, in the case of alloys containing copper instead of ruthenium, the sum of the weights of platinum, tin, copper, tantalum and / or niobium, is determined to reach 1000 wt‰ of the alloy.

[0058] This last group represents the final compositions according to, for example, codes 318, 319, 322, 531, and 561 in Table 1.

[0059] As already stated, the applicant has a platinum alloy which is: - Chromium is 2 wt‰ to 18 wt‰, preferably 5 wt‰ to 15 wt‰; and / or - Molybdenum in amounts of 2 wt‰ to 18 wt‰, preferably 5 wt‰ to 15 wt‰; We studied other groups of existing platinum alloys.

[0060] Some of the lower group alloys containing chromium and / or molybdenum in the amounts indicated in the previous paragraph are quaternary alloys, that is, the sum of the weights of platinum, tin, ruthenium, chromium and / or molybdenum, or, if the alloy contains copper instead of ruthenium, the sum of the weights of platinum, tin, copper, chromium and / or molybdenum, is determined to reach 1000 wt‰ of the alloy.

[0061] This last group represents the final compositions according to, for example, codes 326 and 327 in Table 1.

[0062] Starting from the basic group of compositions described above, and including the limit values ​​of the first, second, and third subgroups, further analysis was conducted on compositions in which platinum is present in amounts of 930 wt‰ to 970 wt‰, preferably 940 wt‰ to 960 wt‰, and the applicant has found that in addition to the above amounts of platinum, copper, or ruthenium: - Gallium in an amount of 5 wt‰ to 23 wt‰, preferably 8 wt‰ to 20 wt‰, more preferably 10 wt‰ to 18 wt‰; or - Gold in amounts of 2 wt‰ to 14 wt‰, preferably 4 wt‰ to 12 wt‰, more preferably 6 wt‰ to 8 wt‰; or - Palladium in amounts of 2 wt‰ to 18 wt‰, preferably 4 wt‰ to 16 wt‰, more preferably 6 wt‰ to 14 wt‰; We have devised several groups of platinum alloys.

[0063] The applicant has focused in particular on quaternary platinum alloys, that is, alloys in which the sum of the weights of platinum, tin, copper, and one of gallium, gold, or palladium reaches 1000 wt‰ of the alloy.

[0064] A further group of platinum alloys studied by the applicant is one in which the sum of the weights of platinum, tin, and ruthenium, or the sum of the weights of platinum, tin, and copper, reaches 970 wt‰ of the alloy, preferably 975 wt‰, and more preferably 980 wt‰; and this group of platinum alloys is characterized in that at least one of iridium, rhenium, vanadium, indium, and hafnium is present in an amount of 30 wt‰ or less in total, preferably 25 wt‰ or less, and more preferably 20 wt‰ or less.

[0065] A particular subgroup of platinum alloys, carefully studied by the applicant, is a group of ternary alloys derived from the basic group, having at least one limit value from the first and third subgroups of platinum alloys, and in particular, a group of ternary alloys having a platinum content of 930 wt‰ to 970 wt‰, preferably 940 wt‰ to 960 wt‰, and containing only 18 wt‰ to 35 wt‰, preferably 22 wt‰ to 34 wt‰.

[0066] Therefore, in light of the above considerations, this disclosure is: - Platinum in a weight of 920‰ to 980‰, preferably 930‰ to 970‰, more preferably 940‰ to 960‰; - Tin in an amount of 5‰ to 35‰, preferably 10‰ to 30‰, more preferably 12‰ to 28‰; - Either way: - Ruthenium in quantities of 8 m‰ to 45 m‰; - Copper in quantities of 2 wt‰ to 45 wt‰; - At least one of the following: - Tantalum in an amount of 2 wt‰ to 30 wt‰, preferably 4 wt‰ to 25 wt‰, more preferably 8 wt‰ to 20 wt‰; and / or - Niobium in a concentration of 2‰ to 20‰, preferably 4‰ to 15‰, more preferably 5‰ to 10‰; - Alternatively, instead of tantalum and / or niobium, at least one of the following: - Chromium in amounts of 2‰ to 18‰, preferably 5‰ to 15‰; and / or - Molybdenum in amounts of 2 wt‰ to 18 wt‰, preferably 5 wt‰ to 15 wt‰; - Alternatively, instead of tantalum and / or niobium and / or chromium and / or molybdenum, at least one of the following: - Gallium in an amount of 5 wt‰ to 23 wt‰, preferably 8 wt‰ to 20 wt‰, more preferably 10 wt‰ to 18 wt‰; or - Gold in amounts of 2 wt‰ to 14 wt‰, preferably 4 wt‰ to 12 wt‰, more preferably 6 wt‰ to 8 wt‰; or - Palladium in amounts of 2 wt‰ to 18 wt‰, preferably 4 wt‰ to 16 wt‰, more preferably 6 wt‰ to 14 wt‰; It is clear that this represents a platinum alloy composed of [the specified material].

[0067] The compositions in Table 1 were obtained as specific embodiments of certain subgroups of platinum alloys based on the above-mentioned research, and were obtained as preferred compositions for the following subgroups.

[0068] Composition 309 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 15 wt‰ to 25 wt‰ of tin, and 23 wt‰ to 33 wt‰ of ruthenium.

[0069] Composition 318 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 15 wt‰ to 25 wt‰ of tin, 13 wt‰ to 23 wt‰ of ruthenium, and 5 wt‰ to 15 wt‰ of niobium.

[0070] Composition 319 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 15 wt‰ to 25 wt‰ of tin, 13 wt‰ to 23 wt‰ of ruthenium, and 5 wt‰ to 15 wt‰ of tantalum.

[0071] The applicant has defined compositions 309, 318 and 319 as follows: - Platinum to 942 wt‰ to 963 wt‰, preferably 947 wt‰ to 957 wt‰, - Tin in an amount of 10‰ to 30‰, preferably 15‰ to 25‰, - Ruthenium in an amount of 18 wt‰ (or 21 wt‰) to 35 wt‰, preferably 23 wt‰ to 33 wt‰, - Optionally, at least one of the following, preferably one: niobium in 2 wt‰ to 17 wt‰, preferably 5 wt‰ to 15 wt‰ and / or tantalum in 2 wt‰ to 17 wt‰, preferably 5 wt‰ to 15 wt‰. Platinum alloy consisting of, In other words, it should be specifically noted that this alloy can be placed in a specific subgroup of platinum alloys where the sum of platinum, tin, and ruthenium, along with optionally niobium and / or tantalum, reaches 1000 wt‰. Thus, this alloy is a ternary, quaternary, or optionally pentary alloy.

[0072] Composition 320 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 10 wt‰ to 20 wt‰ of tin, and 26 wt‰ to 40 wt‰ of ruthenium.

[0073] Composition 322 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 10 wt‰ to 20 wt‰ of tin, 18 wt‰ to 28 wt‰ of ruthenium, and 5 wt‰ to 15 wt‰ of tantalum.

[0074] Composition 325 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 10 wt‰ to 20 wt‰ of tin, 23 wt‰ to 33 wt‰ of ruthenium, and 2 wt‰ to 10 wt‰ of niobium.

[0075] Composition 326 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 10 wt‰ to 20 wt‰ of tin, 18 wt‰ to 28 wt‰ of ruthenium, and 5 wt‰ to 15 wt‰ of chromium.

[0076] Composition 327 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 10 wt‰ to 20 wt‰ of tin, 18 wt‰ to 28 wt‰ of ruthenium, and 5 wt‰ to 15 wt‰ of molybdenum.

[0077] Composition 528 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 9 wt‰ to 19 wt‰ of tin, 15 wt‰ to 25 wt‰ of copper, and 7 wt‰ to 21 wt‰ of gallium.

[0078] Composition 530 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 13 wt‰ to 23 wt‰ of tin, and 25 wt‰ to 35 wt‰ of copper.

[0079] Composition 531 is part of a subgroup of platinum alloys consisting of 947 wt‰ to 957 wt‰ of platinum, 5 wt‰ to 15 wt‰ of tin, 25 wt‰ to 35 wt‰ of copper, and 2 wt‰ to 13 wt‰ of tantalum.

[0080] Composition 561 is part of a subgroup of platinum alloys consisting of 948 wt‰ to 958 wt‰ of platinum, 5 wt‰ to 15 wt‰ of tin, 24 wt‰ to 34 wt‰ of copper, and 2 wt‰ to 13 wt‰ of niobium.

[0081] The applicant has defined compositions 531 and 561 as follows: - Platinum to 942 wt‰ to 963 wt‰, preferably 947 wt‰ to 957 wt‰ or 948 wt‰ to 958 wt‰, - Tin in an amount of 2‰ to 17‰, preferably 5‰ to 15‰, - Copper at a concentration of 21 wt‰ to 39 wt‰, preferably 25 wt‰ to 35 wt‰ or 24 wt‰ to 34 wt‰, - At least one of the following, preferably one: tantalum at 2 wt‰ to 13 wt‰, preferably 3 wt‰ to 12 wt‰ or niobium at 2 wt‰ to 13 wt‰, preferably 3 wt‰ to 12 wt‰ A platinum alloy consisting of, The sum of platinum, tin, copper, and optionally tantalum and / or niobium reaches 1000 wt‰. It should be specifically noted that it can be included in a specific subgroup of platinum alloys.

[0082] Composition 567 is a specific subgroup of platinum alloys consisting of 948 wt‰ to 958 wt‰ of platinum, 20 wt‰ to 30 wt‰ of tin, 7 wt‰ to 17 wt‰ of copper, and 5 wt‰ to 15 wt‰ of palladium.

[0083] Composition 569 is a specific subgroup of platinum alloys consisting of 948 wt‰ to 958 wt‰ of platinum, 20 wt‰ to 30 wt‰ of tin, and 9 wt‰ to 19 wt‰ of copper.

[0084] Table 2 below shows some of the physical properties of the specific platinum alloy compositions listed in Table 1. These two tables have been separated for ease of illustration.

[0085] The following table includes columns showing the qualitative characteristics of the crystal grains, particularly after the annealing process of the alloy. These qualitative characteristics are defined by indices according to UNI EN ISO 643, which specifies the use of standardized grids and optical or electron microscopes to evaluate grain size and / or homogeneity.

[0086] The annealing of platinum alloys described herein is carried out at a temperature below the melting point, followed by a slow cooling and / or controlled cooling process.

[0087] The higher the value shown in the column above, the smaller the average grain size and the higher the quality of the platinum alloy. The other column shows the coordinate L*, which represents the brightness of the alloy on the CIELAB color scale. A higher brightness value corresponds to higher quality of the alloy.

[0088] [Table 2]

[0089] Table 2 shows hardness values ​​according to the Vickers scale. All of the specific compositions listed in Table 2 exhibit higher workability than known alloys, both before and after remelting.

[0090] All of the specific compositions listed in Table 2 have homogeneous crystalline grains.

[0091] Physically, the brightness of an alloy, expressed as reflectance, is related to the grain size to some extent. As the grain size increases, the surface irregularities of objects obtained using that alloy become greater. Therefore, reflectance decreases with increasing grain size, while it increases as grain size decreases. However, a higher coordinate L* does not necessarily correspond to smaller average diameter and more uniform grain size. In fact, the coordinate L* can be influenced by other factors.

[0092] In particular, platinum alloys containing ruthenium (compositions 309, 318, 319, 320, 322, 325, 326, 327) exhibit higher brightness on average compared to platinum alloys containing copper (compositions 528, 530, 531, 561, 567, 569). However, as already shown above, these devised platinum alloys are more expensive than those in which ruthenium is replaced with copper.

[0093] For comparison, the applicant notes that pure platinum exhibits a coordinate L* = 87.5 under the same measurement conditions as the compositions in Table 2. Therefore, the brightness of compositions 309 and 325 surpasses even that of pure platinum.

[0094] From the column related to the grain size index in Table 2, it can be seen that by using ruthenium as a substitute for copper, it is possible to obtain, on average, better, and in particular, more uniform crystal grains. As a result, the surface finish of the amount of platinum-tin-ruthenium composition described herein may, on average, be better than the surface finish of the amount of platinum-tin-copper composition described herein.

[0095] It should also be noted that the presence of tantalum can bring about a considerable improvement in the crystal grain. In fact, comparing composition 320 and composition 322, the latter contains 10‰ less ruthenium, which is replaced by an equal weight of tantalum, and it can be seen that composition 322 has a crystal grain index of 9, while composition 320 has an index of 7 / 8.

[0096] In terms of hardness in an annealed state, platinum-tin alloys containing ruthenium are, on average, harder than platinum-tin alloys containing copper as a substitute for ruthenium. The exception is composition 531, which, due to the presence of tantalum, instead exhibits a hardness comparable to that of platinum-tin-ruthenium alloys.

[0097] The graph in Figure 1 was extracted from Table 2. In this graph, the horizontal axis represents the grain quality (index according to UNI EN ISO 643) for the second to last column in Table 2, and the vertical axis represents the coordinate L* for the last column in Table 2. From the graph in Figure 1, it can be seen that the best compositions overall in terms of grain quality / brightness ratio are, firstly, compositions 325, 322, 309, 318, and 319, and then, in a narrower group, compositions 325 and 322 are considered to be the best.

[0098] The color of platinum alloys is uniquely measured in the CIELAB 1976 color space. This determines the color based on three parameters: L* (first parameter), a* (second parameter), and b* (third parameter). L* defines lightness, taking values ​​between 0 (black) and 100 (white), while a* and b* represent chromaticity parameters. In particular, within the CIELAB 1976 color range, achromatic grayscale is defined by a*=b*=0; when the second parameter a* is positive, it indicates that the value of the second parameter increases as the redness of the color increases; when the second parameter a* is negative, it indicates that the absolute value of the second parameter a* increases as the greenness of the color increases, even if the value is negative; when the third parameter b* is positive, it indicates that the value of the third parameter increases as the yellowness of the color increases; when the third parameter b* is negative, it indicates that the absolute value of the third parameter b* increases as the blueness of the color increases, even if the value is negative. Furthermore, it is also possible to convert the second parameter a* and the third parameter b* into polar coordinate parameters as defined below:

number

[0099] C ab *The parameter is defined as "saturation", C ab *The higher the parameter value, the higher the color saturation;C ab *Lower parameter values ​​tend to result in lower color saturation and a color closer to grayscale.

[0100] From Table 2, and in particular from studies conducted by the applicant on various groups of platinum alloys described herein, it can be seen that certain compositions are of particular interest, as they fall within the elemental range described above and exhibit a color where the coordinate L* measured according to CIE D65 colorimetric conditions in the CIELAB 1976 color space is at least equal to 85. Preferably, alloys where the coordinate L* is at least equal to 85.5 are of particular interest.

[0101] Furthermore, from the compositions in Table 2, alloys characterized by a hardness equal to at least 150 on the Vickers scale are of particular interest.

[0102] In particular, when copper is included, the platinum alloy objects of this disclosure are characterized by having a hardness equal to at least 155 on the Vickers scale.

[0103] Alternatively, if the alloy contains ruthenium, the platinum alloy is characterized by having a hardness equal to at least 160, preferably at least 170, on the Vickers scale.

[0104] In one embodiment, the platinum alloy melting process described herein is a discontinuous melting process. This discontinuous melting process involves melting a mixture and casting it into a graphite mold or into an ingot. In this case, the elements listed above are melted and cast in a controlled atmosphere.

[0105] More specifically, the melting operation is preferably carried out only after at least three cycles of conditioning the atmosphere in the melting chamber. This conditioning first involves reducing the vacuum level to 1 × 10⁻⁶. -2 This involves reducing the pressure to less than mbar, and then partially filling the chamber with argon at 500 mbar. During melting, the argon pressure is maintained between 500 mbar and 800 mbar. Once the pure elements are completely melted, a superheating step is performed, heating the mixture to a temperature of 1600°C to 1850°C to ensure homogeneity in the chemical composition of the molten metal. During the superheating step, the pressure in the melting chamber is again 1 × 10⁻⁶ mbar. -2 Reaching a vacuum level below mbar is useful for removing some of the slag generated by the melting of pure elements.

[0106] At this point, in the casting process, the molten material is either cast into a mold or into an ingot.

[0107] After solidification, the rod-shaped body or casting is removed from the support. Once the alloy has solidified, a rod-shaped body or casting of platinum alloy is obtained from the graphite tube, which is then rapidly cooled by a water immersion process to reduce, and if possible, avoid, phase variation. In other words, the rod-shaped body or casting is subjected to a rapid cooling process to avoid phase changes in the solid state, preferably using water, but not limited to water.

[0108] The platinum alloys according to this disclosure can also be processed in a particularly effective manner to obtain a uniform surface free from visible second phases or carbides. Therefore, the platinum alloys according to this disclosure can be advantageously used in expensive jewelry applications, in particular in the production of expensive jewelry pieces.

[0109] Non-limiting examples of jewelry that can be obtained using at least part of the platinum alloys described herein include: Bracelets, watch bracelets, bezels, watch cases, watch hands, watch mechanisms, bracelet bezels, earrings, ornaments, rings, gemstone settings, ingots, especially collector's ingots, and closures for necklaces, earrings, or bracelets.

[0110] The platinum alloys described herein can be applied to articles that come into direct contact with human skin and are substantially non-allergenic.

[0111] The platinum alloy articles of this disclosure exhibit a specific brightness and optimal machinability, and are therefore particularly useful for use in jewelry applications.

[0112] In conclusion, it is clear that the subject matter of this disclosure can be modified or altered in a manner obvious to those skilled in the art without thereby departing from the scope defined by the appended claims.

Claims

1. A platinum alloy intended for use in jewelry: - Platinum in 920‰ to 980‰ weight; - Tin in quantities of 5 m / s to 35 m / s; - Ruthenium in 8 wt‰ to 45 wt‰ or copper in 2 wt‰ to 45 wt‰; Platinum alloy containing [something].

2. The platinum alloy according to claim 1, wherein tin is present in an amount of 10 wt‰ to 30 wt‰, preferably 12 wt‰ to 28 wt‰.

3. The platinum alloy according to claim 1 or 2, wherein copper is present in an amount of 4 wt‰ to 41 wt‰, preferably 8 wt‰ to 39 wt‰, more preferably 8 wt‰ to 34 wt‰.

4. The platinum alloy according to claim 1 or 2, wherein ruthenium is present in an amount of 10 wt‰ to 43 wt‰, preferably 15 wt‰ to 38 wt‰, more preferably 15 wt‰ to 35 wt‰.

5. The platinum alloy according to any one of claims 1 to 4, wherein platinum is present in an amount of 930 wt‰ to 970 wt‰, preferably 940 wt‰ to 960 wt‰.

6. A platinum alloy according to any one of claims 1 to 5: - Tantalum in an amount of 2 wt‰ to 30 wt‰, preferably 4 wt‰ to 25 wt‰, more preferably 8 wt‰ to 20 wt‰; and / or - Niobium in amounts of 2 wt‰ to 20 wt‰, preferably 4 wt‰ to 15 wt‰, more preferably 5 wt‰ to 10 wt‰; Including, A platinum alloy in which the sum of the weights of platinum, tin, ruthenium, tantalum and / or niobium, or the sum of the weights of platinum, tin, copper, tantalum and / or niobium, is determined to reach 1000 wt‰ relative to the alloy.

7. A platinum alloy according to any one of claims 1 to 6: - Chromium in amounts of 2 wt‰ to 18 wt‰, preferably 5 wt‰ to 15 wt‰; and / or - Molybdenum in amounts of 2 wt‰ to 18 wt‰, preferably 5 wt‰ to 15 wt‰; Including, A platinum alloy in which the sum of the weights of platinum, tin, ruthenium, chromium and / or molybdenum, or the sum of the weights of platinum, tin, copper, chromium and / or molybdenum, is determined to reach 1000 wt‰ relative to the alloy.

8. A platinum alloy according to any one of claims 1 to 7: - Gallium in an amount of 5 wt‰ to 23 wt‰, preferably 8 wt‰ to 20 wt‰, more preferably 10 wt‰ to 18 wt‰; or - Gold in an amount of 2 to 14 weights, preferably 4 to 12 weights, more preferably 6 to 8 weights; or - Palladium in amounts of 2 wt‰ to 18 wt‰, preferably 4 wt‰ to 16 wt‰, more preferably 6 wt‰ to 14 wt‰; Including, A platinum alloy in which the sum of the weights of platinum, tin, copper, gallium, gold, or palladium is determined to reach 1000 wt‰ relative to the alloy.

9. A platinum alloy according to any one of claims 1 to 5, wherein the sum of the weights of platinum, tin, and ruthenium, or the sum of the weights of platinum, tin, and copper, reaches 970 wt‰ relative to the alloy, preferably 975 wt‰ relative to the alloy, and more preferably 980 wt‰ relative to the alloy. The platinum alloy is a platinum alloy containing at least one of iridium, rhenium, vanadium, indium, and hafnium in an amount of 30 wt‰ or less in total, preferably 25 wt‰ or less, and more preferably 20 wt‰ or less.

10. A platinum alloy according to any one of claims 1 to 9, characterized in that it is ternary or quaternary and / or exhibits a color in the CIELAB 1976 color space where the coordinate L* according to the colorimetric conditions in accordance with CIE D65 is at least 85, A platinum alloy characterized by having a hardness equal to at least 150 on a Vickers scale, and optionally containing copper, the platinum alloy is characterized by having a hardness equal to at least 155 on a Vickers scale, or, if containing ruthenium, the platinum alloy is characterized by having a hardness equal to at least 160 on a Vickers scale, preferably at least 170 on a Vickers scale.

11. A platinum alloy according to any one of claims 1 to 10: - Platinum in a weight of 920 wt‰ to 980 wt‰, preferably 930 wt‰ to 970 wt‰, more preferably 940 wt‰ to 960 wt‰; - Tin in an amount of 5 wt‰ to 35 wt‰, preferably 10 wt‰ to 30 wt‰, more preferably 12 wt‰ to 28 wt‰; - Either way: - Ruthenium in quantities of 8 wt‰ to 45 wt‰; - Copper in quantities of 2 wt‰ to 45 wt‰; - At least one of the following: - Tantalum in an amount of 2 wt‰ to 30 wt‰, preferably 4 wt‰ to 25 wt‰, more preferably 8 wt‰ to 20 wt‰; and / or - Niobium in amounts of 2 wt‰ to 20 wt‰, preferably 4 wt‰ to 15 wt‰, more preferably 5 wt‰ to 10 wt‰; - Alternatively, instead of tantalum and / or niobium, at least one of the following: - Chromium in amounts of 2 wt‰ to 18 wt‰, preferably 5 wt‰ to 15 wt‰; and / or - Molybdenum in amounts of 2 wt‰ to 18 wt‰, preferably 5 wt‰ to 15 wt‰; - Alternatively, instead of tantalum and / or niobium and / or chromium and / or molybdenum, at least one of the following: - Gallium in an amount of 5 wt‰ to 23 wt‰, preferably 8 wt‰ to 20 wt‰, more preferably 10 wt‰ to 18 wt‰; or - Gold in an amount of 2 to 14 weights, preferably 4 to 12 weights, more preferably 6 to 8 weights; or - Palladium in amounts of 2 wt‰ to 18 wt‰, preferably 4 wt‰ to 16 wt‰, more preferably 6 wt‰ to 14 wt‰; A platinum alloy consisting of [the following].

12. A jewelry piece comprising the platinum alloy described in any one of claims 1 to 11.

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