Method For Processing A Dispersion-hardened Platinum Composition

Abstract

A method for processing a dispersion-hardened platinum composition is provided. A three-dimensional body of a dispersion-hardened platinum composition containing at least 70% by weight platinum and maximally 29.95% by weight other precious metals, as well as 0.05% by weight to 0.5% by weight of at least one partially-oxidized non-precious metal selected from zirconium, cerium, scandium, and yttrium is provided and cold formed, whereby the cross-sectional area of the three-dimensional body is reduced by maximally 20% during the cold forming, Subsequently a temperature treatment is performed on the cold-formed three-dimensional body, in which the cold-formed product is tempered at at least 1,100.degree. C. for at least one hour. A method for producing a product made of a dispersion-hardened platinum composition, a dispersion-hardened platinum material obtained according to the processing method, and the use of a dispersion-hardened platinum material are also described.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Section 371 of International Application No. PCT/EP2014/076600, filed Dec. 4, 2014, which was published in the German language on Jun. 11, 2015 under International Publication No. WO 2015/082630 A1 and the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] Form bodies made of platinum are commonly used in high-temperature processes, in which the material must possess high corrosion resistance. For example, components made of platinum exposed to mechanical loads, such as, for example, stirrers or glass fiber jet troughs, are used in the glass industry. However, its low mechanical strength at high temperatures is a disadvantage of platinum when used as a material. For this reason, dispersion-hardened platinum compositions are generally used in the high-temperature processes referred to above.

[0003] The production and processing of these materials are known, for example, from printed specifications GB 1 340 076 A, GB 2 082 205 A, EP 0 683 240 A2, EP 1 188 844 A1, and EP 1 964 938 A1.

[0004] The production of components from dispersion-hardened platinum compositions generally starts with generating an ingot that is being hot rolled. The semi-finished product thus obtained can then be cold-formed.

[0005] Forming at low temperatures enables inexpensive adaptation to individual requirements. However, it has been evident that the mechanical properties of dispersion-hardened materials are not yet sufficiently good or, at least, could be better in these forming techniques. The components have too-short service lives for some applications or need to be replaced more frequently than desired. This replacement is associated with high costs. However, forming at high temperatures (so-called hot forming) is very expensive and difficult since the machinery used for this purpose is very elaborate.

BRIEF SUMMARY OF THE INVENTION

[0006] Accordingly, it is the object of the invention to overcome the disadvantages of the prior art. In particular, the method is to enable inexpensive adaptation of components made of platinum compositions to individual requirements while improving the mechanical properties. Concurrently, the components thus obtained are to have a long service life and show as little wear and tear as possible. Moreover, the method should be easy and inexpensive to implement. In addition, the formed components should show good processing properties, in particular, welding properties.

[0007] The invention thus relates to a method for processing a dispersion-hardened platinum composition. Moreover, the present invention describes a method for producing a product from a dispersion-hardened platinum composition. Moreover, the present invention relates to a product obtained from this method and the use of these platinum compositions.

[0008] The objects of the invention are solved by a method for processing of a dispersion-hardened platinum composition characterized by the steps of:

Providing a three-dimensional body of a dispersion-hardened platinum composition comprising at least 70% by weight platinum and maximally 29.95% by weight other precious metals, as well as 0.05% by weight to 0.5% by weight of at least one partially-oxidized non-precious metal selected from zirconium, cerium, scandium, and yttrium; cold forming the dispersion-hardened platinum composition, whereby the cross-sectional area of the three-dimensional body made of the dispersion-hardened platinum composition is reduced by maximally 20% during the cold forming; and subsequently performing a temperature treatment on the cold-formed three-dimensional body, in which the cold-formed product is tempered at a temperature of at least 1,100.degree. C. for at least one hour.

DETAILED DESCRIPTION OF THE INVENTION

[0009] In the scope of the invention, cross-sectional area shall be understood to be the surface area of the surface formed by an (imaginary) section through the three-dimensional body. The plane defined by the cross-sectional area does not necessarily have to be situated perpendicular or essentially perpendicular to the longest extension of the three-dimensional body.

[0010] The percent by weight specifications given above add up to 100%, whereby the weight of the non-precious metals relates to the weight of metal.

[0011] Preferably, the non-precious metal or non-precious metals are oxidized with oxygen at a level of at least 70%, preferably at least 90%. In this context, all oxidation stages of the non-precious metals are taken into consideration, such that, preferably, at most 30 atom-%, particularly preferably at most 10 atom-%, of the non-precious metal are present as metal, i.e., in the formal oxidation stage of 0.

[0012] Preferably, the dispersion-hardened platinum composition contains 0.05% by weight to 0.5% by weight, particularly preferably 0.1% by weight to 0.4% by weight, and specifically preferably 0.15% by weight to 0.3% by weight of the at least partially-oxidized non-precious metal.

[0013] High fractions of non-precious metal oxides lead to longer service lives of the three-dimensional bodies when exposed to mechanical strain. Three-dimensional bodies having low fractions of non-precious metal oxides show advantages with regard to the processing properties, for example welding properties, of the three-dimensional bodies.

[0014] A three-dimensional body is provided in the method according to the present invention. The term three-dimensional body shall be understood comprehensively in this context. Preferably, a three-dimensional body can take the shape of a sheet metal, a tube or a wire.

[0015] In this context, the extension of the three-dimensional body in the three directions of space is not subject to any particular limitations, but can be selected according to the requirements.

[0016] Accordingly, the sheet metals, tubes or wires provided can have a thickness in the range of 0.1 mm to 10 mm, preferably 0.3 mm to 5 mm. In this context, thickness refers to the minimal extension of a three-dimensional body. In the case of a wire, this is the diameter, and in the case of a tube, this is the difference between outer and inner radius, which is also called wall thickness of the tube.

[0017] The platinum composition that can be used according to the invention comprises at least 70% by weight platinum and maximally 29.95% by weight of other precious metals. Accordingly, the composition can essentially consist of platinum and the at least partially-oxidized non-precious metals specified above. Accordingly, the platinum material can be pure platinum other than common impurities with the at least partially-oxidized non-precious metals admixed to it. Moreover, the platinum composition can further comprise other precious metals, in which case the platinum composition is a platinum alloy.

[0018] The invention can provide other precious metals to be selected from ruthenium, rhodium, gold, palladium, and iridium.

[0019] The three-dimensional body provided is cold-formed according to the method according to the invention. The term "cold forming" is known in professional circles, whereby this forming takes place at relatively low temperatures below the recrystallization temperature of the platinum composition and comprises, in particular, drawing, pressing, deep drawing, cold rolling, cold hammering, and pushing. Forming comprises an extensive deformation of the three-dimensional body. Preferably, the invention can provide at least 50%, particularly preferably at least 75%, and specifically preferably at least 95% of the volume of the three-dimensional body to be subjected to a deformation. Accordingly, if the three-dimensional body is, for example, a sheet metal, preferably at least 50%, particularly preferably at least 75%, and specifically preferably at least 95% of the surface of the sheet metal are exposed to a force and/or a pressure, for example by rolling. In the case of a sheet metal, the surface can be simplified to be the surfaces that are perpendicular to the minimal extension of the three-dimensional body (thickness). If the three-dimensional body is, for example, a wire or a tube, preferably at least 50%, particularly preferably at least 75%, and specifically preferably at least 95% of the length of the wire or tube are exposed to a force, for example by drawing.

[0020] It is essential to the invention that only a relatively low forming takes place during cold forming. The cross-sectional area of the three-dimensional body made of the dispersion-hardened platinum composition is reduced by maximally 20%, particularly preferably by maximally 18%, and specifically preferably by maximally 15%. These values are related to the cross-sectional area of the three-dimensional body, which is reduced maximally. In the case of a sheet metal, which is being rolled in one direction only, the reduced cross-sectional area results, for example, from the thickness and the non-extended extension of the three-dimensional body. In the case of a wire or a tube, the reduction of the cross-sectional area results from the change of the diameter and/or wall thickness. Since the volume of the body does not change due to the forming, at least one cross-sectional area must be enlarged during a forming process. For example, the length of a sheet metal, tube or wire will increase during a forming process such that the surface area in the direction in which the length increases will increase as well. The directions in which the forming forces act, engage, in particular, parallel or perpendicular to the plane defined by the cross-sectional area.

[0021] A preferred embodiment provides the cross-sectional area of the three-dimensional body made of the dispersion-hardened platinum composition to be reduced by at least 5%, preferably by at least 8%, and particularly preferably by at least 10% during cold forming.

[0022] It has been found that the internal damage to the dispersion-hardened three-dimensional body upon forming which is associated with a reduction of the cross-sectional area of less than 5% and subsequent annealing does not contribute significantly to an improvement of the creep strength. The lower the change of the cross-sectional area per forming step in the specified range, the lesser is the impact on the improvement of the creep strength as compared to forming processes associated with a reduction of the cross-sectional area of 5% to 20%, preferably of 8% to 18%, and specifically preferably of 10% to 15%.

[0023] Moreover, the invention can provide a wire to be drawn or pressed during cold forming, whereby the cross-sectional area of the wire made of the dispersion-hardened platinum composition is reduced by maximally 20%, particularly preferably by maximally 18%, and specifically preferably by maximally 15% during the cold forming, or a sheet metal to be rolled, drawn, pressed or pushed during cold forming, whereby the cross-sectional area of the sheet metal or the thickness of the sheet metal is reduced by maximally 20%, particularly preferably by maximally 18%, and specifically preferably by maximally 15% during cold forming, or a tube to be rolled, drawn or pressed during cold forming, whereby the cross-sectional area of the tube made of the dispersion-hardened platinum composition is reduced by maximally 20%, particularly preferably by maximally 18%, and specifically preferably by maximally 15% during cold forming.

[0024] The invention can provide no micro-fissures or pores to arise or less than 100 micro-features and/or less than 1,000 pores per cubic millimeter to arise on the inside of the dispersion-hardened platinum composition during the cold forming.

[0025] After the cold forming of the three-dimensional body, a temperature treatment of the cold-formed three-dimensional body follows, in which the cold-formed product is tempered at a temperature of at least 1,100.degree. C. for at least one hour. The tempering can preferably take place over a period of time of at least 90 minutes, more preferably at least 120 minutes, particularly preferably at least 150 minutes, and specifically preferably at least 180 minutes. The temperature at which the tempering is performed can preferably be at least 1,200.degree. C., particularly preferably at least 1,250.degree. C., more particularly preferably at least 1,300.degree. C., and specifically preferably at least 1,400.degree. C.

[0026] Moreover, the invention can provide the cold-formed three-dimensional body to be tempered at a temperature of at least 1,250.degree. C. for at least one hour, preferably at a temperature of 1,400.degree. C. for one to three hours during the temperature treatment.

[0027] The longer the tempering process and the higher the temperature at which the temperature treatment is performed, the better are the mechanical properties of the cold-formed form body. However, the improvement of the mechanical properties reaches saturation at some point and there is a risk of strong grain growth, which deteriorates the mechanical properties again. Moreover, the costs of the method increase with the duration and the tempering temperature. The minimal temperature of the tempering process is 1,100.degree. C. The highest temperature of the tempering process is 20.degree. C. below the melting temperature of the respective dispersion-hardened platinum composition.

[0028] Preferably, the invention can provide the temperature treatment or temperature treatments on the cold-formed three-dimensional body to be used in order to heal defects of the three-dimensional body.

[0029] Methods according to the invention can just as well provide multiple consecutive cold forming processes to be performed and the cross-sectional area of the three-dimensional body to be reduced by more than 20% by the cold forming processes, whereby each individual cold forming process reduces the cross-sectional area of the three-dimensional body made of the dispersion-hardened platinum composition by maximally 20%, particularly preferably by maximally 18%, and specifically preferably by maximally 15%, and a temperature treatment to be performed on the cold-formed three-dimensional body between each cold forming process, in the course of which the cold-formed product is tempered at a temperature of at least 1,100.degree. C. for at least one hour.

[0030] In this context, "between each cold forming process" shall be understood to mean that a temperature treatment is preferably performed at a temperature of at least 1,100.degree. C. for at least one hour after each cold forming process, such that the number of cold forming steps and the number of tempering steps are equal.

[0031] Performing multiple cold forming processes and temperature treatments is advantageous in that the cold forming processes and temperature treatments, which are relatively easy and simple to perform, allow even major forming processes to be implemented without weakening the dispersion-hardened platinum composition, i.e., without reducing, e.g., the creep strength of the alloy. It has even been evident, surprisingly, that the creep strength steadily improves with an increasing number of forming and annealing steps.

[0032] A preferred embodiment of the invention provides for the case of multiple consecutive cold forming processes. Each individual cold forming process reduces the cross-sectional area of the three-dimensional body made of the dispersion-hardened platinum composition by at least 5%, preferably by at least 8%, and particularly preferably by at least 10%.

[0033] Forming steps that comprise only minor reduction of the cross-sectional area of the dispersion-hardened three-dimensional body of less than 5% per forming step and subsequent annealing do not contribute significantly to an improvement of the creep strength. The lower the change of the cross-sectional area per forming step in the specified range, the lesser is the impact on the improvement of the creep strength as compared to forming processes associated with a reduction of the cross-sectional area of 5% to 20%. Moreover, having multiple consecutive forming and annealing steps renders the method elaborate and therefore uneconomical. This is even more pronounced with a larger number of requisite forming steps in order to attain the desired final dimension of the dispersion-hardened three-dimensional body. It is preferred to reach the final dimension in a total of eight forming steps. This number of forming steps is a good compromise of economic efficiency and improvement of the mechanical properties.

[0034] Preferably, the invention can provide the cold-formed product to be tempered at a temperature of at least 1,550.degree. C. for at least 24 h, at a temperature of at least 1,600.degree. C. for at least 12 hours, at a temperature of at least 1,650.degree. C. for at least one hour or to be tempered at a temperature of 1,690.degree. C. to 1,740.degree. C. for at least 30 minutes during the last temperature treatment after the last cold forming of the three-dimensional body.

[0035] This last step largely removes the minor defects to-be-healed of the dispersion-hardened platinum composition in their final form, and the thus generated product therefore exhibits a very high creep strength.

[0036] Any dispersion-hardened platinum composition is suitable as a starting product for the present processing method. However, surprising advantages result from the use of semi-finished products that have generally been subjected to a hot forming process. Before the cold forming, the dispersion-hardened platinum composition can be formed by a hot forming process at a temperature of at least 800.degree. C., preferably at a temperature of at least 1,000.degree. C., particularly preferably at a temperature of at least 1,250.degree. C.

[0037] A further subject matter of the present invention is a method for producing a product from a dispersion-hardened platinum composition, which is characterized in that, before providing the dispersion-hardened platinum composition, it is produced from a composition of at least 70% by weight platinum and maximally 29.95% by weight other precious metals, as well as 0.05% by weight to 0.5% by weight of at least one non-precious metal selected from ruthenium, zirconium, cerium, scandium, and yttrium by at least partial oxidation of the non-precious metal or non-precious metals.

[0038] Preferably, the non-precious metal or non-precious metals are converted to metal oxides at a level of at least 70%, preferably at least 90%.

[0039] The treatment of the non-precious metal or non-precious metals can preferably take place at a temperature between 600.degree. C. and 1,600.degree. C. in an oxidizing atmosphere, preferably between 800.degree. C. and 1,000.degree. C. in an oxidizing atmosphere.

[0040] The method for producing a product made of a dispersion-hardened platinum composition can preferably be combined with the previously described method for processing and the embodiments thereof that are described herein as being preferred.

[0041] Another subject matter of the present invention is a dispersion-hardened platinum material that can be obtained through a method for processing and/or through a method for producing a product from a dispersion-hardened platinum composition. This subject matter provides excellent mechanical properties in combination with excellent processing properties and/or an inexpensive and simple production.

[0042] Preferably, the invention can provide a cylindrical three-dimensional body made of the dispersion-hardened platinum material to withstand a tensile strain of 9 MPa in the direction of the length of the three-dimensional body at a temperature of 1,600.degree. C. for at least 40 hours without tearing, preferably to withstand at least 50 hours without tearing, particularly preferably to withstand at least 100 hours without tearing and/or a sheet metal made of the dispersion-hardened platinum material, which has a rectangular cross-section of 0.85 mm.times.3.9 mm and a length of 140 mm and is placed in an oven chamber at 1,650.degree. C. on two parallel-arranged cylindrical rods with a circular cross-section and a diameter of 2 mm at a distance of 100 mm, whereby the middle of the sheet metal is exposed to a load of 30 g, to sag by less than 40 mm, preferably to sag by less than 30 mm, particularly preferably to sag by less than 20 mm, more particularly preferably to sag by less than 14 mm after 40 hours.

[0043] According to the present invention, a cylindrical three-dimensional body shall be understood to be a straight cylinder-like body, in particular a cylinder, or a cylinder-like body with a non-circular or round footprint. In particular, the cylindrical three-dimensional body is a cuboid (i.e., a cylinder-like body with a rectangular footprint) with edge lengths in the range of 0.5 mm to 5 mm.

[0044] The length of the cylindrical three-dimensional body shall be understood to be the longest extension. In the case of a wire or a tube, the direction of the length is the axis of the cylindrical three-dimensional body, whereas, in the case of a sheet metal, it is one extension in the plane of the sheet metal.

[0045] Moreover, a dispersion-hardened platinum material having the mechanical properties described above of a cylindrical three-dimensional body is a subject matter of the present invention.

[0046] Preferably, the invention can provide the dispersion-hardened platinum material to comprise 0.05% by weight to 0.4% by weight, specifically preferably 0.05% by weight to 0.3% by weight of at least one at least partially oxidized non-precious metal selected from zirconium, cerium, scandium, and yttrium. This embodiment allows, in particular, a material with excellent mechanical properties and very good processing properties to be provided.

[0047] In a special embodiment, the dispersion-hardened platinum material can be a sheet metal, a tube or a wire or a product formed from a wire, tube and/or sheet metal.

[0048] Another subject matter of the present invention is a use of a dispersion-hardened platinum material or of a formed three-dimensional body made of a platinum composition that can be obtained or is obtained through a method according to the invention for processing and/or through a method according to the invention for producing a product made of a dispersion-hardened platinum composition, for devices for use in the glass industry or in a laboratory.

[0049] The invention is based on finding, surprisingly, that keeping the degree of cold forming low (at most 20% change of the cross-sectional area) also keeps low the structural damage, such as, e.g., crystal lattice displacements, which are introduced into the dispersion-hardened platinum composition such that the subsequent temperature treatment successfully heals the damage to the extent that the stability of the formed platinum composition is significantly higher than in known methods for cold forming of dispersion-hardened platinum compositions. If more extensive forming is desired, this can be attained either with an upstream hot forming process or multiple consecutive low-level cold forming processes, whereby the structural damage is healed through a temperature treatment between each cold forming process. According to an insight obtained in the scope of the present invention, the mechanical weakening of cold-formed dispersion-hardened platinum compositions arises from an excessive number of major defects, such as micro-fissures, delamination of the particle/matrix boundaries, and pores on grain boundaries, and these are caused by an excessively high degree of forming and/or excessive reduction of the cross-sectional area.

[0050] In particular, the gentle, low level cold forming prevents internal damage, such as micro-fissures, delamination of the particle/matrix boundaries, and pores on grain boundaries, that cannot be healed at all or only with great effort. Micro-fissures and pores arising on the grain boundaries due to the forming are particularly damaging since they impair the mechanical stability of the dispersion-hardened platinum composition to a particularly strong extent. Using the method according to the invention, this damage can be prevented. Accordingly, this is the first successful attempt to generate a dispersion-hardened platinum composition with very high mechanical stability and excellent processing properties, in particular welding properties, which is also being claimed.

[0051] Further exemplary embodiments of the invention shall be illustrated in the following on the basis of some examples, though without limiting the scope of the invention.

Semi-Finished Precursor 1: Production of a Semi-Finished Precursor With a sheet Thickness of 2 mm Through Internal Oxidation by Zr and Y

[0052] Following the method specified in Example 1 of EP 1 964 938 A1, an ingot containing PtRh10 (alloy made of 90% by weight Pt and 10% by weight Rh) and 2200 ppm non-precious metals (1800 ppm Zr and 400 ppm Y) was cast. The ingot was then subjected to mechanical and thermal treatment. Accordingly, it was rolled to a sheet thickness of 2.2 mm, then recrystallization-annealed, and subsequently rolled to a sheet thickness of 2 mm. The sheet-metal was then oxidized at 900.degree. C. for 18 days and subsequently ductility-annealed at 1400.degree. C. for 6 h.

Semi-Finished Precursor 2: Production of a Semi-Finished Precursor With a Sheet Thickness of 3 mm Through Internal Oxidation by Zr and Y

[0053] Following the method specified in Example 1 of EP 1 964 938 A1, an ingot containing PtRh10 (alloy made of 90% by weight Pt and 10% by weight Rh) and 2200 ppm non-precious metals (1800 ppm Zr and 400 ppm Y) was cast. The ingot was then subjected to mechanical and thermal treatment. Accordingly, it was rolled to a sheet thickness of 3.3 mm, then recrystallisation-annealed, and subsequently rolled to a sheet thickness of 3 mm. The sheet-metal was then oxidized at 900.degree. C. for 27 days and subsequently ductility-annealed at 1400.degree. C. for 6 h.

Semi-Finished Precursor 3: Production of a Semi-Finished Precursor With a Sheet Thickness of 3 mm Through Internal Oxidation by Zr, Y, and Sc

[0054] Following the method specified in Example 1 of EP 1 964 938 A1, an ingot containing PtRh10 (alloy made of 90% by weight Pt and 10% by weight Rh) and 2120 ppm non-precious metals (1800 ppm Zr, 270 mm Y, and 50 ppm Sc) was cast. The ingot was then subjected to mechanical and thermal treatment. Accordingly, it was rolled to a sheet thickness of 3.3 mm, then recrystallization-annealed, and subsequently rolled to a sheet thickness of 3 mm. The sheet-metal was then oxidized at 900.degree. C. for 24 days and subsequently ductility-annealed at 1400.degree. C. for 6 h.

EXAMPLE 1

[0055] The semi-finished precursor 1 with a thickness of approx. 2 mm obtained according to the procedure described above was then processed further, according to the invention, according to the following rolling and annealing steps.

[0056] The sheet metal was rolled to 1.7 mm and subsequently annealed at 1,400.degree. C. for 4 h. Then, the sheet metal was rolled to 1.4 mm and annealed at 1,400.degree. C. for 2 h. Then, the sheet metal was rolled further to 1.2 mm and annealed again at 1,400.degree. C. for 2 h. Then, the sheet metal was rolled to 1 mm and annealed again at 1,400.degree. C. Subsequently, the sheet metal was rolled to its final thickness of 0.85 mm and a final annealing at 1,100.degree. C. for 4 h was performed. The reduction of the cross-sectional area per rolling step was 20%.

EXAMPLE 2

[0057] Example 1 was essentially repeated, except that a final annealing was performed at 1,700.degree. C. for 1 h after rolling to a final thickness of 0.85 mm.

EXAMPLE 3

[0058] The semi-finished precursor 2 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further, according to the invention, according to the following rolling and annealing steps.

[0059] The sheet metal was rolled to 2.4 mm and subsequently annealed at 1,150.degree. C. for 4 h. Then, the sheet metal was rolled to 1.92 mm and annealed at 1,150.degree. C. for 4 h. Then, the sheet metal was rolled to 1.53 mm and annealed again at 1,150.degree. C. for 4 h. The rolling and annealing steps were repeated thrice, whereby the sheet metal was rolled first to 1.22 mm, then to 0.99 mm, and subsequently to 0.8 mm and annealed at 1,150.degree. C. for 4 h after each rolling step. The reduction of the cross-sectional area per rolling step was 20%.

EXAMPLE 4

[0060] The semi-finished precursor 2 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further, according to the invention, according to the following rolling and annealing steps.

[0061] The sheet metal was rolled to 2.4 mm and subsequently annealed at 1300.degree. C. for 4 h.

[0062] Then, the sheet metal was rolled to 1.92 mm and annealed at 1,300.degree. C. for 4 h. Then, the sheet metal was rolled to 1.53 mm and annealed again at 1300.degree. C. for 4 h. The rolling and annealing steps were repeated thrice, whereby the sheet metal was rolled first to 1.22 mm, then to 0.99 mm, and subsequently to 0.8 mm and annealed at 1300.degree. C. for 4 h after each rolling step. The reduction of the cross-sectional area per rolling step was 20%.

EXAMPLE 5

[0063] The semi-finished precursor 2 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further, according to the invention, according to the following rolling and annealing steps.

[0064] The sheet metal was rolled to 2.4 mm and subsequently annealed at 1400.degree. C. for 4 h. Then, the sheet metal was rolled to 1.92 mm and annealed at 1,400.degree. C. for 4 h. Then, the sheet metal was rolled to 1.53 mm and annealed again at 1400.degree. C. for 4 h. The rolling and annealing steps were repeated thrice, whereby the sheet metal was rolled first to 1.22 mm, then to 0.99 mm, and subsequently to 0.8 mm and annealed at 1400.degree. C. for 4 h after each rolling step. The reduction of the cross-sectional area per rolling step was 20%.

EXAMPLE 6

[0065] The semi-finished precursor 2 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further, according to the invention, according to the following rolling and annealing steps.

[0066] The sheet metal was rolled to 2.55 mm and subsequently annealed at 1400.degree. C. for 4 h. Then, the sheet metal was rolled to 2.16 mm and annealed at 1,400.degree. C. for 4 h. Then, the sheet metal was rolled to 1.84 mm and annealed again at 1400.degree. C. for 4 h. The rolling and annealing steps were repeated 5 times, whereby the sheet metal was rolled first to 1.56 mm, then to 1.33 mm, then to 1.13 mm, then to 0.96 mm, and subsequently to 0.8 mm and annealed at 1,400.degree. C. for 4 h after each rolling step. The reduction of the cross-sectional area per rolling step was 15%.

EXAMPLE 7

[0067] The semi-finished precursor 3 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further, according to the invention, according to the following rolling and annealing steps.

[0068] The sheet metal was rolled to 2.4 mm and subsequently annealed at 1150.degree. C. for 4 h.

[0069] Then, the sheet metal was rolled to 1.92 mm and annealed at 1,150.degree. C. for 4 h. Then, the sheet metal was rolled to 1.53 mm and annealed again at 1150.degree. C. for 4 h. The rolling and annealing steps were repeated thrice, whereby the sheet metal was rolled first to 1.22 mm, then to 0.99 mm, and subsequently to 0.8 mm and annealed at 1150.degree. C. for 4 h after each rolling step. The reduction of the cross-sectional area per rolling step was 20%.

EXAMPLE 8

[0070] The semi-finished precursor 3 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further, according to the invention, according to the following rolling and annealing steps.

[0071] The sheet metal was rolled to 2.55 mm and subsequently annealed at 1400.degree. C. for 4 h. Then, the sheet metal was rolled to 2.16 mm and annealed at 1,400.degree. C. for 4 h. Then, the sheet metal was rolled to 1.84 mm and annealed again at 1400.degree. C. for 4 h. The rolling and annealing steps were repeated 5 times, whereby the sheet metal was rolled first to 1.56 mm, then to 1.33 mm, then to 1.13 mm, then to 0.96 mm, and subsequently to 0.8 mm and annealed at 1,400.degree. C. for 4 h after each rolling step. The reduction of the cross-sectional area per rolling step was 15%.

EXAMPLE 9

[0072] The semi-finished precursor 3 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further, according to the invention, according to the following rolling and annealing steps.

[0073] The sheet metal was rolled to 2.7 mm and subsequently annealed at 1400.degree. C. for 4 h. Then, the sheet metal was rolled to 2.43 mm and annealed at 1,400.degree. C. for 4 h. Then, the sheet metal was rolled to 2.19 mm and annealed again at 1400.degree. C. for 4 h. The rolling and annealing steps were repeated 9 times, whereby the sheet metal was rolled first to 1.97 mm, then to 1.77 mm, then to 1.44 mm, then to 1.29 mm, then to 1.16 mm, then to 1.05 mm, then to 0.94 mm, and subsequently to 0.85 mm and annealed at 1,400.degree. C. for 4 h after each rolling step. The reduction of the cross-sectional area per rolling step was 10%.

EXAMPLE 10

[0074] Example 9 was essentially repeated, except that a final annealing was performed at 1,700.degree. C. for 1 h after rolling to a final thickness of 0.85 mm.

EXAMPLE 11

[0075] The semi-finished precursor 3 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further, according to the invention, according to the following rolling and annealing steps.

[0076] The sheet metal was rolled at 1,100.degree. C. (hot forming) to 1.5 mm and subsequently annealed at 1,400.degree. C. for 4 h. Then, the sheet metal was rolled to 1.2 mm (1st cold forming) and subsequently annealed at 1,250.degree. C. for 4 h. Then, the sheet metal was rolled to 1.02 mm (2nd cold forming) and subsequently annealed again at 1,250.degree. C. for 4 h. The rolling and annealing steps were repeated thrice, whereby the sheet-metal was rolled first to 0.94 mm (3rd cold forming), then to 0.86 mm (4th cold forming), and subsequently to 0.8 mm (5th cold forming) and the sheet-metal was annealed at 1,250.degree. C. for 4 h after each rolling step. The reduction of the cross-sectional area was 50% during the hot forming step and 20% initially, then 15%, and then 8% each during the cold forming steps.

Reference Example 1

[0077] The semi-finished precursor 1 with a thickness of approx. 2 mm obtained according to the procedure described above was then processed further according to a conventional method. For this purpose, the sheet metal was rolled directly to 1 mm and annealed at 1,000.degree. C. Subsequently, the sheet metal was rolled to 0.85 mm and a final annealing at 1,000.degree. C. for 1 h was performed.

Reference Example 2

[0078] The semi-finished precursor 2 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further according to a conventional method. For this purpose, the sheet metal was rolled to 1.5 mm and annealed at 1,400.degree. C. for 4 h. Then, the sheet metal was rolled to 0.8 mm. The reduction of the cross-sectional area per rolling step was 50%.

Reference Example 3

[0079] The semi-finished precursor 3 with a thickness of approx. 3 mm obtained according to the procedure described above was then processed further according to a conventional method. For this purpose, the sheet metal was rolled to 1.5 mm and annealed at 1,400.degree. C. for 4 h. Then, the sheet metal was rolled to 0.8 mm. The reduction of the cross-sectional area per rolling step was 50%.

Mechanical Properties of the Platinum Materials Thus Obtained

Creep Strength According to Rupture Test:

[0080] To measure the creep strength, a weight corresponding to the desired load in MPa for the specified cross-section was appended to a sheet-metal sample with a cross-section of 0.85 mm.times.3.9 mm and a length of 120 mm (Examples 1, 2, 9, 10 and Reference Example 1) or 0.08 mm.times.3.9 mm and a length of 120 mm (Examples 3, 4, 5, 6, 7, 8, 11 and Reference Examples 2 and 3). The sample was heated by means of electrical current and controlled to constantly be at the desired temperature by means of a pyrometer measurement. The time until rupture of the probe was determined and corresponds to the creep strength.

TABLE-US-00001 TABLE 1 Creep Strength until Rupture at 1,600.degree. C. and 9 MPa Load Reference example 1 20 h Reference example 2 35 h Reference example 3 30 h Example 1 50 h Example 2 >120 h Example 3 >100 h Example 4 >100 h Example 5 >100 h Example 6 >100 h Example 7 >100 h Example 8 >100 h Example 9 >100 h Example 10 >120 h Example 11 >100 h

Creep Strength Values According to the Sagging Test

[0081] The sagging test is another method for estimation of the creep strength. For this purpose, pieces of sheet metal with a cross-section of 0.85 mm.times.10 mm and a length of 140 mm (Examples 1, 2, 9, 10 and Reference Example 1) or with a cross-section of 0.8 mm.times.10 mm and a length of 140 mm (Examples 3, 4, 5, 6, 7, 8, 11 and Reference Examples 2 and 3) were placed on two parallel ceramic rods separated by a distance of 100 mm and the middle of the sheet was exposed to a load of 30 g. The sample arrangement was then heated to 1,650.degree. C. in a chamber oven and the sagging of the samples was measured after 40 h.

TABLE-US-00002 TABLE 2 Creep Strength According to the Sagging Test Reference example 1 Sagging >40 mm Reference example 2 Sagging 35 mm Reference example 3 Sagging 37 mm Example 1 Sagging 18 mm Example 2 Sagging <12 mm Example 3 Sagging 18 mm Example 4 Sagging 17 mm Example 5 Sagging 18 mm Example 6 Sagging 16 mm Example 7 Sagging 17 mm Example 8 Sagging 17 mm Example 9 Sagging 16 mm Example 10 Sagging 10 mm Example 11 Sagging 16 mm

[0082] The Examples illustrated above demonstrate that a surprising improvement in the mechanical properties can be attained through the measures according to the invention, whereby this improvement can be increased even more by a tempering step at a temperature above 1,100.degree. C., in particular above 1,500.degree. C.

[0083] The features of the invention disclosed in the preceding description, claims, and exemplary embodiments, can be essential for the implementation of the various embodiments of the invention both alone and in any combination.

[0084] It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

1.-15. (canceled)

16. A method for processing a dispersion-hardened platinum composition, comprising: providing a three-dimensional body of a dispersion-hardened platinum composition comprising at least 70% by weight platinum, maximally 29.95% by weight other precious metals, and 0.05% by weight to 0.5% by weight of at least one partially-oxidized non-precious metal selected from zirconium, cerium, scandium, and yttrium; cold forming the dispersion-hardened platinum composition to form a cold-pressed three-dimensional body, wherein a cross-sectional area of the three-dimensional body is reduced by maximally 20% during the cold forming; and subsequently performing a temperature treatment on the cold-formed three-dimensional body by tempering at a temperature of at least 1,100.degree. C. for at least one hour.

17. The method according to claim 16, further comprising before the cold forming step, forming the dispersion-hardened platinum composition by a hot forming process at a temperature of at least 800.degree. C.

18. The method according to claim 16, wherein multiple consecutive cold forming steps are performed and the cross-sectional area of the three-dimensional body is reduced by more than 20% by the cold forming steps, wherein each individual cold forming step reduces a cross-sectional area of the three-dimensional body by maximally 20%, and wherein a temperature treatment is performed on the cold-formed three-dimensional body between each cold forming step by tempering at a temperature of at least 1,100.degree. C. for at least one hour.

19. The method according to claim 18, wherein the tempering comprises tempering at a temperature of at least 1,550.degree. C. for at least 24 hours, at a temperature of at least 1,600.degree. C. for at least 12 hours, at a temperature of at least 1,650.degree. C. for at least one hour, or at a temperature of 1,690.degree. C. to 1,740.degree. C. for at least 30 minutes during the last temperature treatment after the last cold forming step.

20. The method according to claim 16, wherein the cold forming comprises drawing, pushing, pressing, or rolling a wire, sheet or tube of the dispersion-hardened platinum composition, wherein a cross-sectional area of the wire, the sheet, or the tube, or a thickness of the sheet is reduced by maximally 20% during the cold forming step.

21. The method according to claim 16, wherein the cold forming is performed at a temperature of 500.degree. C. or less.

22. The method according to claim 16, wherein the temperature treatment heals defects of the three-dimensional body.

23. The method according to claim 16, wherein the tempering is performed at a temperature of at least 1,250.degree. C. for at least one hour.

24. The method according to claim 16, wherein the dispersion-hardened platinum composition is produced from a composition comprising at least 70% by weight platinum, maximally 29.95% by weight other precious metals, and 0.05% by weight to 0.5% by weight of at least one non-precious metal selected from ruthenium, zirconium, cerium, scandium, and yttrium by at least partial oxidation of the at least one non-precious metal.

25. The method according to claim 24, wherein the oxidation of the at least one non-precious metal is performed at a temperature between 600.degree. C. and 1,600.degree. C. in an oxidizing atmosphere.

26. A dispersion-hardened platinum material produced by the method according to claim 16.

27. A cylindrical three-dimensional body made of the dispersion-hardened platinum material according to claim 26, wherein the body withstands a tensile strain of 9 MPa in a direction of the length of the three-dimensional body at a temperature of 1,600.degree. C. for at least 40 hours without tearing.

28. A sheet metal made of the dispersion-hardened platinum material according to claim 26, wherein the sheet has a rectangular cross-section of 0.85 mm.times.3.9 mm and a length of 140 mm, and wherein the sheet sags by less than 40 mm after 40 hours in a oven chamber at 1,650.degree. C. on two parallel-arranged cylindrical rods with a circular cross-section and a diameter of 2 mm at a distance of 100 mm when the middle of the sheet metal is exposed to a load of 30 g.

29. A sheet metal, a tube, a wire, or a product formed from a wire, tube, and/or sheet metal comprising the dispersion-hardened platinum material according to claim 26.

30. The dispersion-hardened platinum material according to claim 26, wherein the dispersion-hardened platinum material comprises 0.05% by weight to 0.3% by weight of at least one at least partially-oxidized non-precious metal selected from zirconium, cerium, scandium, and yttrium.

31. A device comprising a dispersion-hardened platinum material produced according to the method of claim 16.