DE102019213587A1 - Platinum jewelry alloy - Google Patents

Abstract

The invention relates to a platinum jewelry alloy comprising - 74.0% by weight to 84.0% by weight of platinum, - 9.0% by weight to 23.0% by weight of copper and - 0.5% by weight. -% to 6.0% by weight iron, with no other element from the group of noble metals being included in addition to platinum. The platinum jewelry alloy preferably also contains 0.1% to 4.0% by weight at least one Elements selected from the group consisting of tungsten, rhenium, niobium and tantalum. Furthermore, the invention relates to a semi-finished product for jewelry production, which is made from the alloy according to the invention.

Description

The invention relates to a new platinum jewelry alloy and to a semi-finished product manufactured with the aid of this alloy.

Because of its characteristic gray-white color, platinum has long since found its way into jewelry production and thus also into the jewelry industry. However, in its elemental state, platinum is comparatively soft, so that although it can be easily formed, it does not have the necessary strength and durability for everyday use. For this reason, platinum is usually alloyed with other metals for the jewelry industry in order to increase its strength and thereby significantly improve the processing properties.

The metals that have so far been added to platinum for the production of jewelry alloys are often high-priced precious metals. This means that the production of platinum alloys is comparatively expensive.

Known, commercially used platinum alloys therefore have, for example, significant additions of palladium, iridium, rhodium, ruthenium or gold.

The WO 2005/075690 A1 discloses platinum alloys which, in addition to platinum, copper and cobalt, can contain the noble metals palladium, iridium and ruthenium. While palladium is added to the platinum alloy to change the color, iridium and ruthenium are used to improve the hardness and structure of the alloy.

From the WO 2010/115839 A1 platinum alloys comprising platinum, copper and the noble metal silver are known. Ruthenium, rhodium and iridium can be added to the alloy as additional noble metals.

The WO 2009/059736 A1 describes platinum alloys that use the noble metals ruthenium, rhodium and iridium. Furthermore, copper and tungsten are essential components of the alloys.

Another disadvantage of the known platinum alloys relates to the recycling of these alloys. Recycling in the form of the recovery of raw materials, especially precious metals, from alloys is of great economic interest due to the comparatively high prices of the individual raw materials, especially precious metals. With the use of an increasing number of different precious metals in an alloy, however, the recovery of each individual precious metal also turns out to be increasingly difficult and particularly time-consuming.

TASK AND SOLUTION

The object of the present invention is to provide a new platinum jewelry alloy which circumvents the inadequacies known from the prior art. It should be possible to produce this alloy with materials which reduce the costs of production by dispensing with high-priced precious metals except for platinum. At the same time, however, the new alloy should retain or even improve the properties required for processing in the jewelry industry, for example with regard to its weight and hardness on the one hand and its machinability on the other. In addition, this alloy should in particular be able to be recycled through a simplified process.

This object is achieved by a platinum jewelry alloy having the features of claim 1. Preferred embodiments of this alloy are described in the dependent claims 2 to 12. The invention further comprises a semi-finished product according to claims 13 and 14. The wording of all claims is hereby made part of the content of the present description by express reference.

• - 74,0 Gew.-% bis 84,0 Gew.-% Platin (Pt),
• - 9,0 Gew.-% bis 23,0 Gew.-% Kupfer (Cu) und
• - 0,5 Gew.-% bis 6,0 Gew.-% Eisen (Fe),

wobei neben Platin kein weiteres Element aus der Gruppe der Edelmetalle enthalten ist.According to a first aspect, the invention relates to a platinum jewelry alloy comprising

• - 74.0% by weight to 84.0% by weight platinum (Pt),
• - 9.0 wt .-% to 23.0 wt .-% copper (Cu) and
• - 0.5% by weight to 6.0% by weight iron (Fe),

no other element from the group of precious metals is included besides platinum.

In the context of the present invention, the expression “precious metals” is to be understood as meaning an element from the group consisting of the platinum metals platinum, palladium, iridium, rhodium, ruthenium and osmium as well as gold and silver.

In addition to the alloy elements mentioned, which give the alloy according to the invention its special properties in combination, the alloy according to the invention can also contain impurities in amounts of up to 0.03% by weight, in particular up to 0.02% by weight, based on the total weight of the alloy.

In the context of the present invention, the expression “impurities” should be understood to mean all metallic or non-metallic elements and substances that are not in the alloy added on purpose. As a rule, these are components that are already contained in the starting materials for the production of the alloy according to the invention.

In an embodiment of the invention, the alloy according to the invention preferably additionally contains 0.1% by weight to 4.0% by weight of at least one element selected from the group consisting of tungsten, rhenium, niobium and tantalum.

Tungsten, rhenium, niobium and tantalum are known as grain refiners.

The addition of grain refiners to the alloys according to the invention proves to be particularly advantageous, since grain refiners ensure that the alloy obtained has a smaller mean grain size compared to alloys which do not contain these elements. A smaller mean grain size increases the fine grain size of the alloy according to the invention, which advantageously increases the strength. An increased strength in turn has an advantageous influence on the deformation properties of the alloy according to the invention.

It is preferred in this context if at least tungsten is included as a component of the alloy according to the invention from the group consisting of the elements tungsten, rhenium, niobium and tantalum, preferably only tungsten is provided as such an additive in the alloy according to the invention.

In a further embodiment of the invention, the alloy according to the invention preferably additionally contains 0.1% by weight to 4.0% by weight of at least one element selected from the group of indium, gallium, tin and germanium.

The elements indium, gallium, tin and germanium serve as melting point lowerers in the alloy according to the invention, i.e. by adding such elements to an alloy, the melting point can be lowered compared to alloys that do not contain these elements. In addition, these elements increase the hardness of the alloy according to the invention.

In the present case, it is preferred in this context for the alloy according to the invention if at least indium from the group mentioned indium, gallium, tin and germanium is contained, preferably only indium is provided as such an additive.

The platinum content of the alloy according to the invention is preferably between 75.0% by weight and 80.0% by weight. Within this range, platinum contents between 76.0% by weight and 79.0% by weight are again more preferred.

The copper content of the alloy according to the invention is preferably between 14.0% by weight and 21.0% by weight. Within this range, copper contents between 16.0% by weight and 19.0% by weight are again more preferred.

The iron content of the alloy according to the invention is preferably between 1.0% by weight and 5.0% by weight. Iron contents between 2.0% by weight and 4.0% by weight are again more preferred within this range.

In further preferred embodiments of the invention, the content of the at least one element selected from the group consisting of tungsten, rhenium, niobium and tantalum in the alloy according to the invention is between 0.2% by weight and 2.0% by weight. Within this range, contents of the at least one element selected from the group consisting of tungsten, rhenium, niobium and tantalum between 0.2% by weight and 1.0% by weight are further preferred.

In other preferred embodiments of the invention, the content of the at least one element selected from the group of indium, gallium, tin and germanium in the alloy according to the invention is preferably between 0.2% by weight and 2.0% by weight. Within this range, contents of the at least one element selected from the group indium, gallium, tin and germanium between 0.2% by weight and 1.0% by weight are further preferred.

In the alloy according to the invention, the iron content, the content of the at least one element selected from the group tungsten, rhenium, niobium and tantalum and the content of the at least one element selected from the group indium, gallium, tin and germanium are preferably not more than 5 % By weight, preferably not more than 4% by weight, in particular not more than 3% by weight, based on the total weight of the alloy according to the invention.

In a further embodiment of the invention, the alloy according to the invention is preferably nickel-free.

In a further embodiment of the invention, the alloy according to the invention is preferably cobalt-free.

In a further embodiment of the invention, the alloy according to the invention is preferably cadmium-free.

• - Platin (Pt),
• - Kupfer (Cu),
• - Eisen (Fe) und
• - Wolfram (W) aufweisen, oder die Bestandteile
• - Platin (Pt)
• - Kupfer (Cu)
• - Eisen (Fe) und
• - Rhenium (Re).

According to the invention, in accordance with the previous statements, those platinum jewelry alloys are preferred that contain the constituents

• - platinum (Pt),
• - copper (Cu),
• - Iron (Fe) and
• - contain tungsten (W), or the components
• - platinum (Pt)
• - copper (Cu)
• - Iron (Fe) and
• - Rhenium (Re).

• - 76,0 Gew.-% bis 79,0 Gew.-%, vorzugsweise 77,0 Gew.-% bis 78,0 Gew.-%, insbesondere 77,7 Gew.-% Platin,
• - 16,0 Gew.-% bis 19,0 Gew.-%, vorzugsweise 18 Gew.-% bis 19 Gew.-%, insbesondere 18,8 Gew.-% Kupfer,
• - 2,0 Gew.-% bis 4,0 Gew.-%, vorzugsweise 2,5 Gew.-% bis 3,5 Gew.-%, insbesondere 3,0 Gew.-% Eisen und
• - 0,2 Gew.-% bis 1,0 Gew.-%, vorzugsweise 0,3 Gew.% bis 0,7 Gew.%, insbesondere 0,5 Gew.-% mindestens eines Elements ausgewählt aus der Gruppe Wolfram, Rhenium, Niob und Tantal, insbesondere Wolfram oder Rhenium,

wobei neben Platin kein weiteres Element aus der Gruppe der Edelmetalle in der erfindungsgemäßen Legierung enthalten ist.In this context also particularly preferred are platinum jewelry alloys according to the invention consisting of

• - 76.0% by weight to 79.0% by weight, preferably 77.0% by weight to 78.0% by weight, in particular 77.7% by weight of platinum,
• - 16.0 wt .-% to 19.0 wt .-%, preferably 18 wt .-% to 19 wt .-%, in particular 18.8 wt .-% copper,
• - 2.0 wt .-% to 4.0 wt .-%, preferably 2.5 wt .-% to 3.5 wt .-%, in particular 3.0 wt .-% iron and
• 0.2% by weight to 1.0% by weight, preferably 0.3% by weight to 0.7% by weight, in particular 0.5% by weight, of at least one element selected from the group consisting of tungsten and rhenium , Niobium and tantalum, especially tungsten or rhenium,

In addition to platinum, no further element from the group of noble metals is contained in the alloy according to the invention.

With such a platinum jewelry alloy, the advantages according to the invention can be realized in a special way.

The alloy according to the invention is associated with clear advantages.

Apart from platinum, it is free of elements from the group of precious metals. This is advantageous, inter alia, because noble metals are high-priced metals and their production costs can be markedly reduced by reducing the use of expensive noble metals in the alloy according to the invention.

Such an alloy can also, from a particularly economic point of view, substitute very high-quality 18-carat multi-material white gold alloys with a very high palladium content (> 12% Pd) for reasons of white coloring, and with a significantly lower precious metal content and only one precious metal (e.g. B. Pt 752/1000), also convince in terms of color and technical properties.

A 752 Pd white gold alloy (18 kt gold with 13.5% Pd content), which is roughly comparable in color, shows e.g. B. cumulative precious metal content of 887/1000 shares of high-priced precious metals in the alloy.

Furthermore, the alloy according to the invention is distinguished by a simplified recycling process.

In the context of the present invention, the expression “recycling” should be understood to mean the recovery of raw materials, in particular precious metals, from an alloy.

The recycling process of the alloy according to the invention is therefore particularly advantageous because fewer recycling steps are required to separate platinum as the only noble metal from the remaining components of the alloy according to the invention, compared to alloys that contain more than one noble metal and thus multistage, time-consuming and have to go through costly recycling processes.

Accordingly, the alloy according to the invention is of great commercial importance because it can be produced inexpensively using a single noble metal and is also characterized by a simplified, efficient and more cost-effective recycling process.

The alloy according to the invention preferably has a minimum hardness in the soft state of 190 HV5 and a so-called delivery hardness of 225 HV5. Deformation hardness at 40% cold deformation is 305 HV5 to 375 HV10.

The person skilled in the art understands the unit “HV” to be the hardness of an alloy, which was determined using the Vickers hardness test. HV5 corresponds to the test force of 50 N (Newton) and HV10 to the test force of 100 N. This specification is a common specification for the hardness of such materials for metal alloys.

In addition, the alloy according to the invention preferably has a density of less than 20 g / cm ³ , in particular of less than 18 g / cm ³ .

Finally, it should be emphasized that, despite the new composition, the alloy according to the invention can provide the properties that are required of such jewelry alloys. On the one hand, this is the stated hardness of the alloy according to the invention. Furthermore, the alloy according to the invention is sufficiently fine-grained with a homogeneous, very uniform microstructure to ensure its good machinability by machining techniques, be it manually by the jewelry designer or by machines, for example CNC machines in the jewelry industry. The alloy according to the invention can also be diamond-coated (mechanically machinable with the aid of natural diamonds) and can be polished very well. The mentioned properties of the alloy according to the invention are particularly advantageous for the design of wedding rings.

Finally, according to a second aspect, the invention relates to a semifinished product for the manufacture of jewelry which is at least partially, preferably completely, made from the inventive alloy described.

In the context of the present invention, the term “semi-finished product” should be understood to mean a prefabricated geometric shape made from the corresponding alloy material. The semi-finished product is then further processed manually or industrially into the respective end jewelry products. In the jewelry sector, such semi-finished products are usually pipes, rods, rings, sheets, strips, wires and the like. They are first produced as a cast semi-finished product and then, as a rule, further processed into the final semi-finished product with the desired dimensions, preferably reshaped.

According to the invention, it is preferred if the semifinished products according to the invention are tubular or ring-like semifinished products. Such semi-finished products are particularly suitable for the production of jewelry rings, including wedding rings.

With regard to further features and advantages of the semifinished product for the manufacture of jewelry according to the second aspect of the invention, reference is made in full to the statements made in the context of the first aspect of the invention. The features and advantages described there also apply mutatis mutandis to the semifinished product according to the second aspect of the invention.

The described and further features of the invention emerge from the following description of exemplary embodiments in conjunction with the subclaims. The individual features can be implemented individually or in combination with one another. The exemplary embodiments merely serve to explain the invention further, without restricting it thereto.

EXAMPLES

example 1

6 kg of alloy mixture are melted in a vacuum induction melting plant and then poured into a cooled copper casting mold.

A round bar with a diameter of 42 mm obtained in this way is formed in three steps with a rotary hammering machine (technical term: rotary kneading machine) onto a round bar with a diameter of 34 mm.

A pipe blank with an outside diameter of 34 mm and an inside diameter of 26 mm is then produced by turning and drilling.

The pipe blank is then annealed for one hour at 900 ° C., after which it is cooled to room temperature by water quenching.

The tube is now reshaped and processed in the conventional way.

The following alloys are produced in accordance with the procedure described above.

• - 777 Platin (Pt)
• - 188 Kupfer (Cu)
• - 30 Eisen (Fe)
• - 5 Wolfram (W)

To produce a first platinum jewelry alloy according to the invention, the following metals are provided in the form of their pure fine metals as an alloy mixture _{based on the total weight 1,000 (% 0; English: ppt = parts per thousand):}

• - 777 platinum (Pt)
• - 188 copper (Cu)
• - 30 iron (Fe)
• - 5 tungsten (W)

• - 77,7 Gew.-% Platin (Pt)
• - 18,8 Gew.-% Kupfer (Cu)
• - 3,0 Gew.-% Eisen (Fe)
• - 0,5 Gew.-% Wolfram (W)

Converted to% by weight, this alloy according to the invention thus has the composition:

• - 77.7% by weight platinum (Pt)
• - 18.8% by weight copper (Cu)
• - 3.0% by weight iron (Fe)
• - 0.5 wt .-% tungsten (W)

• - 800 Platin (Pt)
• - 175 Kupfer (Cu)
• - 25 Eisen (Fe)

For the production of a second platinum jewelry alloy according to the invention are obtained on the total weight of 1,000 (% ₀ ; English: ppt = parts per thousand) the following metals are provided in the form of their pure fine metals as an alloy mixture:

• - 800 platinum (Pt)
• - 175 copper (Cu)
• - 25 iron (Fe)

• - 80,0 Gew.-% Platin (Pt)
• - 17,5 Gew.-% Kupfer (Cu)
• - 2,5 Gew.-% Eisen (Fe)

Converted to% by weight, this alloy according to the invention thus has the composition:

• - 80.0% by weight of platinum (Pt)
• - 17.5% by weight copper (Cu)
• - 2.5% by weight iron (Fe)

Example 2

3 kg alloy mixture is melted in a vacuum induction melting plant and then poured into a cooled copper casting mold.

The sprue cavity is cut off on a round rod with a diameter of 35 mm obtained in this way and the casting skin is turned down to a diameter of 30 mm to form a round rod / rod. The round material is then formed with conventional hexagonal or octagonal wire rollers in several production steps up to a 4 mm rolled profile.

After at least one of the work steps, this alloy is annealed for one hour at 900 ° C., the alloy then being cooled to room temperature by water quenching.

This raw material is then processed further in wire drawing up to the desired wire diameter and reshaped.

The following alloy is produced and processed in accordance with the procedure described above.

• - 750 Platin (Pt)
• - 205 Kupfer (Cu)
• - 25 Eisen (Fe)
• - 10 Wolfram (W)
• - 10 Indium (In)

To produce a platinum jewelry alloy according to the invention, the following metals are provided in the form of their pure fine metals as an alloy mixture _{based on the total weight 1,000 (% 0; English: ppt = parts per thousand):}

• - 750 platinum (Pt)
• - 205 copper (Cu)
• - 25 iron (Fe)
• - 10 tungsten (W)
• - 10 indium (In)

• - 75,0 Gew.-% Platin (Pt)
• - 20,5 Gew.-% Kupfer (Cu)
• - 2,5 Gew.-% Eisen (Fe)
• - 1,0 Gew.-% Wolfram (W)
• - 1,0 Gew.-% Indium (In)

Converted to% by weight, this alloy according to the invention thus has the composition:

• - 75.0% by weight platinum (Pt)
• - 20.5% by weight copper (Cu)
• - 2.5% by weight iron (Fe)
• - 1.0 wt .-% tungsten (W)
• - 1.0 wt .-% indium (In)

Example 3

In a vacuum induction melting plant, 5 kg of alloy mixture are melted and then poured into a cooled copper casting mold.

A plate obtained in this way with dimensions of 100 mm × 24 mm is planed to remove the casting skin to a thickness of 20 mm and the pouring cavities are cut off.

The plate is now formed by a plate rolling mill to a thickness of up to 7 mm, with intermediate anneals of one hour each at 900 ° C. with subsequent water quenching being carried out.

The thus formed plate is processed into a blank for a watch case by means of wire erosion.

The following alloy is produced and further processed according to the procedure described above.

• - 800 Platin (Pt)
• - 175 Kupfer (Cu)
• - 20 Eisen (Fe)
• - 5 Rhenium (Re)

To produce a platinum jewelry alloy according to the invention, the following metals are provided in the form of their pure fine metals as an alloy mixture _{based on the total weight 1,000 (% 0; English: ppt = parts per thousand):}

• - 800 platinum (Pt)
• - 175 copper (Cu)
• - 20 iron (Fe)
• - 5 rhenium (Re)

• - 80,0 Gew.-% Platin (Pt)
• - 17,5 Gew.-% Kupfer (Cu)
• - 2,0 Gew.-% Eisen (Fe)
• - 0,5 Gew.-% Rhenium (Re)

Converted to% by weight, this alloy according to the invention thus has the composition:

• - 80.0% by weight of platinum (Pt)
• - 17.5% by weight copper (Cu)
• - 2.0 wt .-% iron (Fe)
• - 0.5% by weight rhenium (Re)

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2005/075690 A1 [0005]
• WO 2010/115839 A1 [0006]
• WO 2009/059736 A1 [0007]

Claims (14)

Comprising platinum jewelry alloy - 74.0% by weight to 84.0% by weight platinum, - 9.0 wt .-% to 23.0 wt .-% copper and - 0.5% by weight to 6.0% by weight iron, with no other element from the group of noble metals being included besides platinum. Platinum jewelry alloy according to Claim 1 , characterized in that the alloy contains 0.1% by weight to 4.0% by weight of at least one element selected from the group consisting of tungsten, rhenium, niobium and tantalum, preferably tungsten. Platinum jewelry alloy according to Claim 1 or Claim 2 , characterized in that the alloy contains 0.1% by weight to 4.0% by weight of at least one element selected from the group consisting of indium, gallium, tin and germanium. Platinum jewelry alloy according to one of the preceding claims, characterized in that the platinum content is between 75.0% by weight and 80.0% by weight, preferably between 76.0% by weight and 79.0% by weight, amounts to. Platinum jewelry alloy according to one of the preceding claims, characterized in that the copper content is between 14.0% by weight and 21.0% by weight, preferably between 16.0% by weight and 19.0% by weight, amounts to. Platinum jewelry alloy according to one of the preceding claims, characterized in that the iron content is between 1.0% by weight and 5.0% by weight, preferably between 2.0% by weight and 4.0% by weight, amounts to. Platinum jewelry alloy according to one of the Claims 2 to 6th , characterized in that the content of the at least one element selected from the group consisting of tungsten, rhenium, niobium and tantalum is between 0.2% by weight and 2.0% by weight, preferably between 0.2% by weight and 1 , 0% by weight. Platinum jewelry alloy according to one of the Claims 3 to 7th , characterized in that the content of the at least one element selected from the group indium, gallium, tin and germanium, between 0.2 wt .-% and 2.0 wt .-%, preferably between 0.2 wt .-% and 1.0 wt%. Platinum jewelry alloy according to one of the preceding claims, characterized in that the alloy is nickel-free. Platinum jewelry alloy according to one of the preceding claims, characterized in that the alloy is cobalt-free. Platinum jewelry alloy according to one of the preceding claims, characterized in that the alloy is cadmium-free. Platinum jewelry alloy according to one of the preceding claims consisting of - 76.0% by weight to 79.0% by weight, preferably 77.0% by weight to 78.0% by weight, in particular 77.7% by weight of platinum, - 16.0 wt .-% to 19.0 wt .-%, preferably 18 wt .-% to 19 wt .-%, in particular 18.8 wt .-% copper, 2.0% by weight to 4.0% by weight iron, preferably 2.5% by weight to 3.5% by weight, in particular 3.0% by weight iron and 0.2% by weight to 1.0% by weight, preferably 0.3% by weight to 0.7% by weight, in particular 0.5% by weight, of at least one element selected from the group consisting of tungsten and rhenium , Niobium and tantalum, in particular tungsten or rhenium, with no other element from the group of noble metals being included besides platinum. Semi-finished product for jewelry production, characterized in that it is at least partially, preferably completely made of an alloy according to one of the preceding claims. Semi-finished product after Claim 13 , characterized in that it is a tubular or ring-like semi-finished product.