EP0314981B1 - Process for production of smelting material containing copper, chromium and at least one volatile component and consumable electrode for use in such a process - Google Patents

Description

The invention relates to a method for producing melting materials made of copper (Cu), chromium (Cr) and at least one highly volatile component, an arc melting method being used in which the electrode material melting from a melting electrode is melted in a water-cooled mold for the purpose of cooling without Macroscopic segregation of copper and chrome is caught. In addition, the invention also relates to a consumable electrode for use in this method, which consists of copper (Cu) and chromium (Cr) as well as tellurium (Te) and / or selenium (Se) and / or antimony (Sb) as an easily evaporable component predetermined total composition of all components.

A method of the type mentioned at the outset is known from EP-B-0115292. Materials produced by such a method were initially intended for use as contact materials for vacuum medium-voltage circuit breakers with breaking currents above 10 kA. From EP-A-0172411 it is also known to provide such a material also as a contact material for vacuum contactors, the material for reducing the welding force adding at least one of the metals tellurium (Te), antimony (Sb), bismuth (Bi) and / or tin (Sn) and their alloys. The additives are introduced by subsequent alloying or diffusing into the contact pieces produced by the known method, which is comparatively lengthy and complex.

Tellurium and / or selenium and / or antimony or bismuth in particular have proven to be suitable as additional components for copper-chromium contact materials for reducing the welding force. However, the elements mentioned are characterized by a high vapor pressure, so that additives of these elements evaporate easily when the arc is melted. Accordingly, it has been shown that the direct alloying of these additives is not possible when arc-melting copper-chromium, since the additives - especially if they are mixed in as a fine powder of the electrode - evaporate due to their high vapor pressure under the influence of the arc and lead to pore formation in the melting block . Tellurium or selenium or antimony form intermetallic compounds with copper, the vapor pressure and thus evaporation tendency - as measurements have shown - are reduced compared to the pure components tellurium and selenium or antimony. However, pore formation also occurs when the additives are not mixed as elemental tellurium or selenium or antimony, but as intermetallic compounds Cu₂Te or Cu₂Se or Cu₃Sb in powder form. This is due to the gas loading of the finely divided Cu₂Te or Cu₂Se or Cu₃Sb powder. A fine-particle powder has so far been considered essential for homogeneous distribution.

Since the direct alloying of tellurium or selenium or antimony or their intermetallic Cu compounds in the melting process is not possible in the manner described, according to EP-A-0172411, tellurium has been specifically used after the arc melting and, if appropriate, after a corresponding shaping of the CuCr blanks, for example, by extrusion in a separate manufacturing step. This involves an additional process step that makes the manufacturing process more expensive.

In contrast, the object of the invention is to improve the method of the type mentioned at the outset in such a way that an easily evaporable Component can be introduced directly into the material during the melting process. For this purpose, suitable consumable electrodes should be specified that can be used in the context of an arc melting process.

The object is achieved in that such a melting electrode is used to melt the material with the easily evaporable component, which partially consists of a solid alloy of copper with the easily evaporable component, the concentration of the easily evaporable component in the alloy being higher than in Sum composition of the melting material, and that the easily evaporable component remains bound in the melting material during melting. In the case of a melting electrode for use in this method, which consists of copper and chromium and tellurium and / or selenium and / or antimony, the easily evaporable component is at least partially alloyed as an intermetallic compound in the copper, the copper-tellurium or copper Selenium or copper-antimony alloy is present as a solid part in the electrode structure.

The invention enables the introduction of easily evaporable additives in arc-melted copper-chromium alloys directly during the melting process and thus the production of pore-free CuCrTe or CuCrSe or CuCrSb melting blocks, provided the correspondingly constructed melting electrodes are used. For the introduction of tellurium in particular in the melting process, all effects leading to pore formation are now avoided. For example, massive rods of a CuTe alloy, such as CuTe0.6, can be introduced into a tube electrode, which are then coated with CuCr powder.

It was found that the vapor pressure of, for example, massive CuTe0.6 is significantly lower than that of pure tellurium or copper telluride. This takes place when remelting no evaporation of the Te component takes place, as a result of which the tellurium remains bound in the melting material. The gas loading of tellurium-containing powder is also eliminated in the manufacturing process according to the invention. It is thus achieved that pore-free arc-melted CuCrTe or CuCrSe or CuCrSb as well as CuCrTeSe or CuCrTeSb materials can be produced for the first time without additional manufacturing steps.

• Es zeigen Fig. 1 und 2 zwei Beispiele für eine Abschmelzelektrode erster Art im Querschnitt,
• Fig. 3 eine andere Abschmelzelektrode im Längsschnitt und
• Fig. 4 eine weitere Abschmelzelektrode im Querschnitt.

Further details and advantages of the invention emerge from the following description of the figures of exemplary embodiments with reference to the drawing in conjunction with the patent claims.

• 1 and 2 show two examples of a melting electrode of the first type in cross section,
• Fig. 3 shows another melting electrode in longitudinal section and
• Fig. 4 shows a further consumable electrode in cross section.

The figures are drawn approximately on a scale of 1: 2, so that the respective proportions are comparable. Identical parts have the same reference numerals, the figures being partially described together.

1 to 3, 1 denotes a copper tube with the cross-sectional dimensions of, for example, 70 × 2 mm. For the copper pipe 1 may, for example OFHC (o Xigen f ree h igh c onductive) - or SF (s auerstof f rei) material may be used. Reference numeral 2 denotes a CuCr powder mixture in low-gas quality with a predetermined particle size distribution.

In Fig. 1, three solid rods 3 to 5 with a diameter of 10 mm made of an alloy of, for example, CuTe0.6 are embedded in the powder mixture 2 made of CuCr. This material is known according to DIN 17666 under the material number 2.1546 with a tellurium content of 0.4 to 0.7 m%. Are in accordance with Fig. 2 nine rods 3 to 11 with a diameter of 10 mm made of an alloy of, for example, CuTe0.6 embedded in the CuCr powder mixture 2.

It has been shown that with the geometry of the copper pipe given in FIG. 1 or FIG. 2, the number of rods can expediently be varied between one and ten, their number and the diameter and the tellurium or selenium or antimony content of the individual rod as a result determine the concentration of the finished material. The profile of the individual bar is irrelevant; the rods can, for example, as round or. Square part or be designed as a tube.

Furthermore, the concentration in the CuCr powder mixture can be varied. Powder from 25 m% Cr up to pure Cr powder are possible.

In FIG. 3, a plurality of individual sections 13 of rods or profiles with a predetermined cross section made of CuTe0.6 material are approximately uniformly embedded in the copper tube 1 with CuCr powder mixture 2. If a melting electrode constructed in this way is used, the highly evaporable component in the melting material is also largely bonded.

In Fig. 4 there is an outer tube 41 with the cross-sectional dimensions 70 × 2 mm made of CuTe material. A CuCr powder mixture 42 is introduced into the tube 41. Even with a melting electrode constructed in this way, the tellurium remains bound during the melting process and alloys into the melting material.

Especially in the case of the consumable electrodes according to FIG. 1 or 2, the composition of the CuCrTe or CuCrSe or CuCrSb melt material to be produced for a given rod diameter should in particular be determined by the number of rods on the one hand and by the tellurium or selenium or antimony content in the rods on the other hand: From a manufacturing point of view it is theoretically possible that rods made of copper-tellurium alloys as solid parts can have a tellurium content of up to 8.2% by mass. With a maximum number of ten rods of CuTe8.2 with ⌀ 10 mm in a copper tube ⌀ 70 × 2 mm, this would lead to a CuCr50Te4.1 material, provided that the tube also consists of the CuTe pre-alloy. The production of solid alloys with a higher tellurium content is prevented by the segregation in the CuTe two-component system in the liquid state. The same applies to copper-selenium alloys, since even in the CuSe system there is a separation in the liquid state above 2.2 m%. This means that a CuCr50Se1.1 material can be produced with a maximum number of rods of ten. With regard to a melting electrode with an antimony content, reference is made to claim 13.

The table below shows a number of examples specifically for the production of CuCrTe melting materials using a melting electrode according to FIG. 1 or 2, such as the number of rods, their tellurium content and the composition of the copper-chromium powder mixture the concentration of the finished melting material can be influenced. A tube electrode with ∅ 70 × 2 mm is assumed. To produce other dimensions, the use of tubular electrodes of larger or smaller diameter, for example between 50 and 100 mm, is also possible. The tellurium content of the melting material is also determined by the number and diameter of the CuTe rods or the diameter and thickness of the CuTe tube. For copper pipes ∅ 52 × 2 mm, two rods of CuTe0.6 with a diameter of 10 mm already have a tellurium content in the melting material of 0.1 m%.

Corresponding calculations for the dimensioning of the tube electrode and the number of rods can be made for CuCrSe or CuCrSb and also for CuCrTeSe and CuCrTeSb melting materials carry out.

The arc melting with the above-described melting electrodes takes place in the manner described in EP-B-0115292 under a protective gas atmosphere; for example, 100 mb helium or argon have proven to be suitable.

Claims (14)

1. A method for manufacturing melting materials of copper (Cu), chromium (Cr) and at least one easily evaporable component, wherein an electric arc melting method is used, in which the electrode material melting off from a fusible electrode of a predetermined total composition, is collected in a water-cooled permanent mould for the purpose of cooling without macroscopic separation of copper and chromium, characterised in that for melting the material with the easily evaporable component such a fusible electrode is used, which consists partially of a solid alloy of copper with the easily evaporable component, wherein the concentration of the easily evaporable component in the alloy is higher than in the total composition of the melting material and that when melting the easily evaporable component remains bonded in the melting material.

2. A fusible electrode for using with a method for manufacturing melting materials according to claim 1, which consists of copper (Cu) and chromium (Cr) as well as tellurium (Te) and/or selenium (Se) and/or antimony (Sb) as easily evaporable component with a predetermined total composition of all components, characterised in that the easily evaporable component is alloyed at least partially as an intermetallic compound in the copper, wherein the copper-tellurium or copper-selenium or copper-antimony alloy is present in the electrode structure as a solid part.

3. A fusible electrode according to claim 2, characterised in that the solid parts can have any profile, for example round or square or tubular.

4. A fusible electrode according to claim 2, characterised in that the electrode structure consists of a pipe (1) of copper, in which, embedded in a copper chromium powder mixture (2) the solid parts (3-5; 5-11;13) of the copper-tellurium, copper-selenium or copper-antimony alloy are arranged (Figures 1-3).

5. A fusible electrode according to claim 4, characterised in that the copper pipe (1) consists of copper, which is low in oxygen, for example OFHC or SF copper.

6. A fusible electrode according to claim 4, characterised in that the solid parts are continuous rods (3-5; 3-11), which are embedded in parallel and at a distance relative to each other in the CuCr powder mixture (2), (Figure 1, 2).

7. A fusible electrode according to claim 6, characterised in that the electrode structure consists of a pipe (1) with the cross-section dimensions 70  ×  2 mm, in which one to ten rods (3-5; 3-11) of a copper-tellurium or a copper-selenium or a copper-antimony alloy with 10 mm diameter are distributed over the cross-section.

8. A fusible electrode according to claim 7, characterised in that the rods (3-5; 3-11) are distributed symmetrically.

9. A fusible electrode according to claim 3, characterised in that the solid parts are distributed as sections (13) evenly in the CuCr powder mixture (2)(Figure 3).

10. A fusible electrode according to claim 3, characterised in that the electrode structure consists of a pipe (41) of copper-tellurium or copper-selenium or copper-antimony alloys as outer shell, in which a copper-chromium powder mixture (42) is arranged (Figure 4).

11. A fusible electrode according to claim 2, wherein the easily evaporable component is tellurium, characterised in that the tellurium content in the solid part is  ≦ 8.2 m-% and a copper-chromium or pure chromium power is used, whereby a CuCrTe material is able to be produced with a tellurium content of up to 4.1 m-%.

12. A fusible electrode according to claim 2, wherein the easily evaporable component is selenium, characterised in that the selenium content in the solid part is  ≦  2.2 m-%; and a copper-chromium or pure chromium powder is used, whereby a CuCrSe material is able to be produced with a selenium component of up to 1.1 m-%.

13. A fusible electrode according to claim 2, wherein the easily evaporable component is antimony, characterised in that the antimony content in the solid part is  ≦ 11 m-% and a copper-chromium or pure chromium powder is used, whereby a CuCrSe material is able to be produced with an antimony content of up to 5.5 m-%.

14. A fusible electrode according to claim 7 and claim 11, characterised in that the rods consist of a CuTe alloy with 0.4 to 0.7 m-% tellurium.

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