EP3177747B1 - Amorphously solidifying noble metal-based noble metal alloy - Google Patents

Description

The invention relates to an amorphous precious metal alloy containing platinum and / or palladium, a process for their preparation and an article produced on the basis of this noble metal alloy, in particular jewelry such as a piece of jewelry, a clock, a watch case, or a writing instrument.

Noble metal amorphous precious metal alloys are increasingly being used, especially in the jewelery or watch industry, as they provide an exceptional combination of mechanical properties, particularly in terms of their strength and elasticity, which is not achieved by any other currently known material so. Often, amorphous metallic precious metal alloys are also characterized by a significantly higher hardness compared to conventional crystalline noble metal alloys of comparable composition.

Another advantage of amorphous metals is the combination of mechanical properties with the possibility of near-net-shape processing by casting or thermoplastic molding: The processing of such amorphous metals goes hand in hand with no solidification shrinkage and leads to workpieces with high mechanical loads. When casting such amorphous metals, the maximum achievable thickness of fully amorphous solidified workpieces is limited by the critical cooling rate of the respective noble metal alloy. In thermoplastic molding, amorphous workpieces may be deformed or bonded at temperatures above the glass transition temperature T _g , thereby producing thin-walled, hollow, large area and / or surface structured workpieces having dimensions beyond the critical thickness.

The first amorphous noble metal alloy based on precious metals was a binary precious metal alloy in the Au-Si system. Starting from this system, the hitherto most known amorphous noble metal alloy having the composition Au ₄₉ Ag _5.5 Pd _2.3 Cu _26.9 Si _16.3 from Liquidmetal Technologies Inc. was developed, the abovementioned proportions being expressed in atomic percentages , In mass percent this corresponds to Au _76.3 Ag _4.7 Pd _1.9 Cu _13.5 Si _3.6 . This precious metal alloy with an 18-karat gold content has a hardness of 360 HV and thus exceeds the hardness value of a color-comparable crystalline precious metal alloy by more than 50%. A disadvantage of this noble metal alloy was a lack of corrosion behavior, which is why this precious metal alloy was not widely used.

Furthermore, platinum-based noble metal alloys are known, for example Pt _42.5 Cu ₂₇ Ni _9.5 P ₂₁ and Pt ₈₀ Cu ₁₆ Co ₂ P ₂₂ , the abovementioned proportions being again expressed in atomic percent. In terms of mass percentage this corresponds to Pt _73.9 Cu _15.3 Nis P _5.8 or Pt _88.8 Cu _4.5 Co _0.9 P ₅ . These exclusively high grade precious metal alloys also have unusually high hardnesses above 400 HV and are more corrosion resistant than the aforementioned amorphous gold alloys because of generally slower kinetics. The main drawback of these known platinum-based amorphous noble metal alloys is their large admixtures of nickel-phosphorus and phosphorus, which make processing and recycling more difficult. In the aforementioned platinum alloys z. As nickel-phosphorus content or phosphorus content of 21 or 22 atomic percent required to achieve a sufficient glass forming ability or lowest liquidus temperatures in the system Pt-P.

Furthermore, palladium-based amorphous precious metal alloys are known, e.g. B. Pd ₄₀ Co ₃₀ Ni ₁₀ P ₂₀ , wherein the proportions of the aforementioned alloy components are again indicated in atomic percent. In terms of mass percentage, the abovementioned noble metal alloy has the following composition: Pd ₅₈ Co ₂₆ Ni ₈ P ₈ . Again, the large proportion of nickel-phosphorus of about 16 percent by mass is disadvantageous again.

The US 4,746,584 A1 describes metal electrodes formed from an amorphous metal according to the formula Pt _p A _a D _d , where A is iridium, palladium, rhodium, ruthenium or a mixture thereof and D is boron, aluminum, arsenic, phosphorus, antimony, germanium, silicon or Sicillium or a mixture thereof. The mass fraction p is in the range of 40-82%, that of a in the range of 1-40% and that of d in the range between 8-40%, wherein the mass fractions p, a and d to 100 wt .-% complementary , This amorphous precious metal alloy is characterized by being always contains two elements from the platinum group, namely always platinum and another element of the platinum group.

From the EP 0 267 318 A2 For example, a jewelery crystalline precious metal alloy is known which consists of 75% to 99.5% by weight of palladium as the base metal with additions of metals of the 3rd to 6th periods of the Periodic Table of the Elements.

The DE 20 2009 013 202 U1 describes a crystalline platinum-jewelery alloy comprising 50% to 70% by weight of platinum, 2% to 15% by weight of at least one element selected from indium, gallium, germanium, tin and zinc and 0.5% to 40% by weight of silver or copper.

The DE 10 2007 006 623 A1 describes a crystalline platinum alloy for the manufacture of jewelery having the following composition, the percentages being given by weight: 39-66% platinum, 5-30% palladium and 10-32% copper. Preferred embodiments of the alloys provide a composition of 44-46% platinum, 9-30% palladium and 24-27% copper and 39-41% platinum, 9-30% palladium and 29-52 copper, respectively.

It is an object of the present invention to provide an amorphous precious metal alloy, which - apart from unavoidable admixtures and impurities - is free of nickel and / or phosphorus. In addition, a method for producing a semifinished product of the noble metal alloy according to the invention is to be created. Further objects of the invention are the provision of a semifinished product, in particular for the production of jewelry, as well as in the use of the precious metal alloy according to the invention for the production of a jewelry article as well as in the creation of a jewelry article.

The noble metal alloy according to the invention has a composition according to A _a B _b C _c , wherein A is at least one element selected from the group consisting of Pt and Pd, B is at least one element selected from the group consisting of Al, Au, Ag, Cu and C represents at least one element selected from the group consisting of Ga and Ge, the mass fraction a being in the range of 45-60% by mass, preferably in the range of 45-59% by mass, more preferably in the range of 48-54% by mass, the mass fraction b in the range of 39-55 % By mass preferably in the range of 39-49 mass%, more preferably in the range of 40-47 mass%, and the mass fraction c in the range of 0-13 mass%, preferably in the range of 1-13% by mass, more preferably in the range of 2 to 10% by mass and more preferably in the range of 2 to 5 mass%, preferably wherein, in the coexistence of platinum and palladium, the noble metal alloy does not have aluminum as the sole alloying component of group B, and wherein the aforesaid mass fractions a, b and c are common Apart from admixtures and impurities, supplement to 100 percent by mass.

The inventive measures a platinum alloy is created, which is nickel and / or phosphorus-free, and yet has a good glass forming ability. The precious metal alloy according to the invention is characterized by a high resistance to corrosion and tarnishing and is therefore particularly suitable for the production of high-quality workpieces such. B. pieces of jewelry suitable.

Surprisingly, it has been found that these advantageous properties are achieved not only in the case of platinum as starting material but also in the case of palladium or a combination of platinum and palladium, the proportion of palladium or platinum and palladium being between 45 and 60 percent by mass.

The noble metal alloys according to the invention have the advantage that they contain no nickel and / or phosphorus. This significantly simplifies their production and material recycling. The precious metal alloys are also harmless in terms of any allergies, which is particularly advantageous for use in the jewelry and watch industry, where the corresponding piece of jewelry often directly and for a long time in direct contact with the skin, is beneficial.

The inventive method for producing a semifinished product of an amorphous solidifying noble metal alloy suggests that a masses of at least one element of the aforementioned group A, b mass fractions of at least one element of the aforementioned group B and c mass fractions of at least one element of the aforementioned group C alloyed and to the Semi-finished products are poured.

The semifinished product according to the invention provides that it is produced from the above-described noble metal alloy according to the invention.

According to the invention, an amorphous solidifying noble metal alloy is used for producing a jewelry article, in particular a piece of jewelry, a clock of a watch case, a watch band, a writing instrument or a part of such an article, which is characterized by the composition A _a B _b C _c A at least one noble metal from a group consisting of platinum and palladium, B at least one element from a group consisting of Al, Au, Ag and Cu, C at least one element from a group consisting of Ga and Ge, wherein the mass fraction a is in the range of 45-60% by mass, preferably in the range of 45-59% by mass, more preferably in the range of 48-54% by mass, the mass fraction b in the range of 39-49 55% by mass, preferably in the range of 39 -55% by mass, more preferably in the range of 39 to 49% by mass, more preferably in the range of 40 to 47% by mass, and the mass c is in the range of 0-13% by mass, preferably in the range of 1-13% by mass, more preferably in the range of 1 to 12% by mass, more preferably in the range of 2 to 10% by mass and in particular in the range of 2 to 5% by mass, and wherein the aforementioned mass fractions a, b and c, apart from customary admixtures and impurities, supplement to 100 percent by mass.

An article of jewelery according to the invention, in particular jewelery such as a piece of jewelery, a watch, a watch case, a watch strap, a writing instrument or a part of the aforementioned article provides that this article is wholly or partly made of the amorphous precious metal alloy according to the invention.

Advantageous developments of the invention are the subject of the dependent claims.

Further details and advantages of the invention can be taken from the exemplary embodiments which are described below; the following quantities are in each case percent by mass

1. Platinum alloys 1.1 System Pt-Ag-Cu

The first three embodiments of a platinum-based noble metal alloy belong to the Pt-Ag-Cu system.

A first embodiment of a platinum-based noble metal alloy is given by Pt _53.2 Ag _31.4 Cu _12.2 Ga _3.2 . This precious metal alloy is characterized by a favorable glass forming ability.

A second embodiment provides that the noble metal alloy Pt ₅₀ AG is _33.8 Cu _13.2 Ga ₃ .

A third embodiment of a noble metal alloy is given by Pt ₅₀ Ag _30.6 Cu _11.9 Ge _7.5 .

1.2 System Pt-Al-Cu

The next three embodiments relate to an amorphous solidified noble metal alloy whose main components are Pt-Al-Cu.

The fourth embodiment consists of the noble metal alloy Pt _53.1 Al _35.8 Cu _7.9 Ga _3.2 . The fifth embodiment consists of the noble metal alloy Pt ₅₀ Al _{38.5 Cu 8.5} Ga ₃ .

The sixth embodiment provides a noble metal alloy Pt ₅₀ Al _34.9 Cu _7.7 Ge _7.4 .

1.3 System Pt-Au-Ag-Cu

The seventh and eighth embodiments each describe a noble metal alloy of Pt-Au-Ag-Cu system. The corresponding precious metal alloys are exemplified by Pt ₅₀ Au _23.5 Ag ₁₇ Cu _6.5 Ga ₃ and Pt ₅₀ Au _21.2 Ag _15.3 Cu ₆ Ge _7.5 .

The abovementioned eight embodiments thus describe amorphously solidifying platinum-based noble metal alloys which are characterized by the following composition: Pt _a B _b C _c , where Pt is platinum, B is at least one element from a group consisting of Al, Au, Ag and Cu is defined, and C is at least one element of the group consisting of Ga and Ge defined. The parameter a stands for the platinum content of the described noble metal alloys with 45-60 mass percent, the parameter b for 39 to 55 mass percent, preferably 39-49 mass percent and the parameter c for 0-13 mass percent.

It is preferred that platinum is present in an amount of 45-60 mass%, more preferably 45-59 mass%, more preferably 48-54 mass%, especially in a proportion of 49-51 mass% or 50-54 mass% and for the latter range further especially a proportion of 50-52 mass percent is present in the described precious metal alloys. The latter areas are characterized by a particularly favorable glass-forming ability.

The proportion b of one or more metals from group B is 39 to 55 mass%, preferably 39-49 mass%, preferably 40-47 mass% and especially 42-47 mass%.

It is preferred that gallium and / or germanium in a proportion c between 0-13 mass percent, preferably in a proportion of 1-13 mass%, preferably in an amount of 1-12 mass% and in particular in an amount of 2-10 mass% and in particular 2 to 5 percent by mass is present in the described noble metal alloys. It is also possible that, although this is not preferred, gallium and / or germanium are present in a proportion c of 0-1 mass percent, that is, in the extreme case (c = 0) gallium and / or germanium in the above-described noble metal Alloys is not included.

2. Palladium alloys

As already mentioned, it has surprisingly been found that not only amorphous solidifying noble metal alloys based on platinum with the composition described above have the described advantageous properties, but that platinum can be wholly or partly substituted by palladium.

2.1 System Pd-Ag-Cu

The ninth embodiment is a noble metal alloy associated with the Pd-Ag-Cu system and consists of Pd ₅₀ Ag ₃₄ Cu ₁₃ Ga ₃ . Again, a favorable glass forming ability is given.

2.2 System Pd-Au-Ag-Cu

An exemplary embodiment of such a noble metal alloy pertaining to this system is Pd ₅₀ Au _20.2 Ag _14.6 Cu _5.7 Ge _9.5 .

2.3

The noble metal alloys described above can thus be characterized by Pd _a B _b C _c , where Pd for palladium and B and C in turn for at least one element from the above-described groups Al, Au, Ag, Cu or Ga, Ge.

The proportion a of palladium in this case is again 45-60% by mass, preferably 45-59% by mass, more preferably 48-54% by mass, more preferably 49-51% by mass or 50-54 and in this case preferably 50-52% by mass, in particular in the latter Concentration areas a particularly favorable glass forming ability is given.

In this case, the proportion b of the group B element (s) is 39 to 55% by mass, preferably 39-49% by mass, more preferably 40-47% by mass, and still more preferably 42-47% by mass.

Again, the proportion of gallium and / or germanium is 0-13 mass%, with the preferred ranges given for the platinum-based amorphous precious metal alloys described in paragraph 1 above correspondingly for palladium.

It is preferred here that the ratio of the atomic proportions of palladium and aluminum is greater than or equal to 4. This atomic ratio of palladium to aluminum corresponds to a mass ratio of palladium to aluminum of greater than or equal to 94/6; It is thus preferred that the ratio of the proportions of palladium and aluminum - expressed in mass ratios - is greater than or equal to 15.67. An example of such an alloy is an alloy containing 45 to 60 mass percent palladium, 39 to 55 mass percent of at least two group B and gallium and / or germanium elements of 0 to 13 mass percent, but with the proviso that: the first of at least two metals from group B are aluminum, with aluminum being equivalent the proportion of palladium in the range of 45 to 60% by mass and the aforementioned ratio between palladium and aluminum - in a proportion of at most 45 / 15.67 to 60 / 15.67, that is in a proportion from 2.87 to 3.83 mass percent is; the remainder of the fraction b of the at least two elements from the group B is provided by at least one further element from the aforementioned group B. As in the case described above, the abovementioned preferred ranges apply to the parts a. b and c again accordingly.

3. Platinum-palladium alloy

It has also been shown that a precious metal alloy containing not only platinum or palladium in isolation, but a combination of platinum and palladium - (Pta ₁ Pda ₂ ) _a in a proportion a = a ₁ + a ₂ of 45-60 Percent by mass and otherwise has the abovementioned constituents, in which therefore here platinum is substituted by up to 100 wt .-% of palladium, the aforementioned advantageous properties, in particular with regard to the glass-forming ability having. As an example of such a noble metal alloy is here Pd ₅₀ Pd _3.2 Ag _31.4 Cu _12.2 Ga _{3.2 be} mentioned.

The platinum-palladium alloys are thus characterized by (Pt _a1 Pd _a2 ) _a B _b C _c , wherein for the mass fractions a, b and c again preferably the values given in Sections 1.3 and 2.3 apply correspondingly.

Again, it is also preferred that the ratio of the atomic proportions of palladium and aluminum is greater than or equal to 4. The explanations given at the end of section 2.3 also apply to a combination of platinum and palladium. As an exemplary example, the following alloy is to be given: This alloy has platinum and palladium in a total proportion of 55 percent by mass, assuming 50 percent by weight of platinum and 5 percent by weight of palladium. The proportion of elements from group B, here exemplarily aluminum and copper, is between 40 and 45 mass percent, optionally containing a corresponding proportion c of elements of group C. The proportion of aluminum is then less than 0.32 mass percent and the proportion of copper is in the range of 39.7 to 24.7 mass percent.

It is preferred that in the simultaneous presence of platinum and palladium, one of the two elements, so either platinum or palladium, each in a proportion of more than 50 mass percent is present to the Punzierfähigkeit such a noble metal alloy with at least 50 mass percent of Platinum or palladium, or in a proportion of only slightly less than 50 mass percent is present. For example, for a total platinum and palladium content of 51-60 mass%, the proportion of platinum may be 50-59 mass%, i. h., That palladium is then present only in a proportion of 1 percent by mass. The same applies vice versa, namely that - again only for example - palladium in a proportion of 50-59 percent by mass is present and consequently the proportion of platinum is then only 1 percent by mass. Of course, all combinations are possible, for. B. that the proportion of platinum or palladium 50-54 percent by mass, preferably 50-52 mass percent, with a total content of platinum and palladium of z. B. 59 percent by mass, is, and the proportion of each other metal then has the missing 59 percent by mass residue.

In the above description of the exemplary embodiments of the amorphous platinum-palladium alloys, it has been assumed that plural elements of the group B, that is, the group consisting of Al, Au, Ag, Cu, are present. But it is also possible that only one of these elements, as the only alloying element, from this group B is present in the described precious metal alloys. But it is preferred that aluminum is not present as the only element of group B. A combination of elements of the group B, which includes Al, is also quite similar amorphous platinum-palladium alloys - as well as in the described amorphous platinum alloys and the amorphous palladium alloys - also possible. This in particular when the proportion a of platinum and palladium is between 45 and 59 percent by mass, in particular in the abovementioned subregions of the fraction a.

4. Production and further processing

The preparation of the abovementioned noble metal alloys is described by way of example with reference to the first embodiment. The production of the other noble metal alloys comprising the abovementioned compositions A _a B _b C _c is carried out accordingly: 53.2 parts by mass of platinum, 31.4 parts by mass of silver, 12.2 parts by mass of copper and 3 by 2 mass fractions of gallium alloyed and poured as a solid semi-finished product. The semi-finished product is melted in the next step and processed in a rapid solidification process. Preference is given here an atomization of the melt in an inert gas stream, by means of a device and a method which z. In the German patent DE 103 40 606 B4 are described.

In an atomization of the melt with a starting temperature of 1250 ° C in a nitrogen stream with an outlet pressure of 10 bar, the material solidifies in fractions of a second in the form of amorphous powders, which typically have a mean particle diameter of 25 microns. The amorphous powder has a glass transition temperature T _g of about 290 ° C and a crystallization temperature T _x of about 450 ° C.

Other applicable rapid solidification processes include die casting and surface coating processes such as thermal spraying or cold gas spraying.

The further processing of plasticized amorphous semifinished materials at temperatures above the glass transition temperature by means of so-called thermoplastic molding under pressure (TPF process), such as the injection molding of plasticized amorphous semifinished materials at temperatures above the glass transition temperature is possible.

From the above description, it is clear to the person skilled in the art that the range limits specified in each case apply within the scope of customary alloy tolerances. In addition, it can be seen that by specifying the respective range limits, all mass fractions falling within the respective range are also included.

To summarize, it should be noted that the precious metal alloys described are particularly suitable for the production of jewelry such as jewelry, watches, watch cases, writing instruments and components of the aforementioned goods.

Claims (14)

1. Amorphous precious metal alloy, characterized by the following composition: A_aB_bC_c, whereby

   - A designates at least one precious metal of a group consisting of platinum and palladium,

   - B designates at least one element of a group consisting of Al, Au, Ag and Cu,

   - C designates at least one element of a group consisting of Ga and Ge,

   whereby the mass amount a is in the range of 45-60 mass percent, preferably in the range of 45-59 mass percent, further preferably in the range of 48 to 54 mass percent, the mass amount b is in the range between 39-55 mass percent, preferably in the range of 39-49 mass percent, further preferably in the range of 40 to 47 mass percent, and the mass amount c is in the range of 0-13 mass percent, preferably in the range of 1-13 mass percent, further preferably in the range of 2 to 10 mass percent, and in particular preferably in the range of 2 to 5 mass percent, whereby preferably, when platinum and palladium are simultaneously present, the amorphous precious metal alloy does not contain aluminum as a single alloy component of the group B, and wherein the afore-mentioned mass amounts a, b and c, apart from usual admixtures, impurities and alloy tolerances, supplement to 100 mass percent.
2. Precious metal alloy according to claim 1, characterized in that the precious metal alloy consists of Pt_a B_b and C_c, whereby Pt designate the precious metal platinum.
3. Precious metal alloy according to claim 1, characterized in that the precious metal alloy consists of Pd_a B_b and C_c, whereby Pd designate the precious metal palladium.
4. Precious metal alloy according to one of the previous claims, characterized in that the precious metal alloy consists of (Pta₁ Pda₂)_a B_b C_c, wherein the sum of the mass portions a₁ of platinum and a₂ of palladium, is - apart from usual admixtures and impurities - equal to the mass portion a.
5. Amorphous precious metal alloy according to one of the previous claims, characterized in that the mass portion a is in the range of 49-51 mass percent or in the range of 50-54 mass percent, preferably in the range of 50-52 mass percent, and/or that the mass portion b is in the range of 42-47 mass percent.
6. Precious metal alloy according to one of the previous claims, characterized in that the amount of platinum or the amount of palladium is equal or greater than 50 mass percent, and/or that in the simultaneous presence of platinum and palladium the mass portion of one of these two elements is preferably greater than 50 mass percent.
7. Precious metal alloy according to one of the previous claims, characterized in that the precious metal is Pt_53,2Ag_31,4Cu_12,2Ga_3,2 or Pt₅₀Ag_33,8Cu_13,2Ga₃.
8. Method for the manufacturing of a semi-finished product from an amorphous solidifying precious metal alloy according to one of the previous claims, characterized in that

   - a mass portions of at least one element of the group A,

   - b mass portions of at least one element of the group B, and

   - c mass portions of at least one element of the group C are alloyed and cast to a semi-finished product.
9. Method according to claim 8, characterized in that the semi-finished product is melted and is further processed in a rapid solidification process.
10. Method according to claim 9, characterized in that an atomization of the molten material in an inert gas is used as a rapid solidification process, or that as rapid solidification process a die-casting or a surface coating like thermic spraying or cold gas spraying is used.
11. Method according to claim 8, characterized in that the amorphous semi-finished product is further processed by means of a thermoplastic forming under pressure (TPF-method).
12. Semi-finished product, in particular for manufacturing of ornamental items, characterized in that the semi-finished product is made of an amorphous solidifying precious metal alloy according to one of the claims 1 to 7.
13. Use of an amorphous solidifying precious metal alloy for manufacturing an ornamental article, in particular a piece of jewellery, a watch, a watch case, a watch band, a writing instrument or a part of such an article, characterized in that an amorphous precious metal alloy according to one of the claims 1 to 7 is used.
14. Ornamental article, in particular jewellery like a piece of jewellery, a watch, a watch case, a watch band, a writing instrument or a part of said articles, characterized in that the article is completely or partially made of an amorphous precious metal alloy according to one of the claims 1 to 7.