DE3726037A1 - Process for producing shaped articles from brittle materials - Google Patents

Abstract

Published without abstract.

Description

The method described below is preferably aimed at the technical production of wire and ribbon-shaped bodies from brittle Fabrics for use in electrical engineering and for manufacturing composite materials.

Brittle substances (SPS) include chemical metal compounds such as borides, carbides, nitrides, oxides and sulfides and their complex compounds such as oxycarbides and mixed compounds such as Nb, Ti (C, O) or La _{2 x} Ba _x Cu _{3 x} and others

The use in electrical engineering is aimed at Hot Electric, i. H. for use up to approx. 500 ° C and for the production of warm Supra conductors.

The use in the composite materials is primarily on the composite of Metal matrix aligned with wires / strips from PLC.

The process is based on the following process stages:

• 1. Alloying the metals contained in the PLC.
• 2. Forming the alloys into wires, strips, tubes or the like Bodies.
• 3. Chemical shaping of the bodies produced according to 2. to SPS.
• 4. Enveloping the body produced according to 3.

The individual process steps are described in more detail below.

The metals are alloyed by melting, sintering or hot pressing the metal powder or the powder from master alloys and metal powders. Corresponding granules can also be used instead of the metal powder. Master alloys are alloys that do not have the full composition of the required alloy. In the case of the warm superconductor La _{2 x} Ba _x Cu _{3 x} , a pre-alloy of lanthanum and barium with a small amount of copper is used. A fine granulate is produced from the master alloy in a known manner by spraying.

The granules are finally added with the remaining and necessary amount Copper powder to rod-shaped green compacts with a diameter of 50 mm pressed. The green compacts are then slowly turned on in the protective gas increasing temperature up to approx. 850 ° C sintered into bars.

The melted alloys also become rod-shaped Ingot reshaped, advantageously by casting and solidification in molds.

Reshaped or cast ingots to wires, strips or pipes is done in a known manner by deep pull at normal temperature or, depending on the alloy, at elevated temperatures temperature in protective gas, such as argon or hydrogen.

In order to produce strips, the bars are rolled and the sheets are closed Cut strips. Since many PLCs after chemical forming un are usually brittle, the rolled sheets are advantageously with other, chemically resistant auxiliary sheets or auxiliary foils plated one or more times and then to the final one Starch rolled.

It is essential that the chemically resistant auxiliary sheet with the Non-metal practically does not react during chemical forming and for the non-metal, e.g. B. is permeable to oxygen.

Is z. B. used as auxiliary sheet silver, the oxygen can of chemical transformation pass through the silver and the sheet oxidize for the PLC and thus a band-shaped, metal-reinforced body generate from PLC.

The silver layer can also be applied by the following known method are brought:

• - Deposition via electrochemical processes from electroplating baths and / or de-energized;  
• - Evaporation or through
• - sputtering in vacuum or plasma.

The auxiliary layer made of silver u. a. Metals is not limited to Sheets, including wires from both of the above. Types of ingots can be wrapped this way are used to mechanically protect the PLC alloy, carbide or nitride.

Gold can also be used in the same way.

The chemical transformation the body made according to 2nd to SPS takes place at elevated temperature below the melting range of the bodies used as below described.

For oxides, the reaction takes place in oxygen and / or a mixture Hydrogen and water vapor at temperatures up to approx. 1000 ° C. Here the bodies produced according to 2. are slowly passed through a tunnel oven pulled through, through which the above. Mixture flows through.

The way of working in the tunnel furnace is i. w. also in the following ge called PLC used.

For carbides, the chemical transformation takes place in a mixture of water gases and carbon-containing gases such as methane, gasoline or chlorinated coal hydrogen.

For nitrides, nitrogen and / or dilute ammonia (NH ₃ ) is used.

Gases such as hydrogen sulfide are used for sulfides in sulfur-donating gases or a mixture of hydrogen and sulfur vapor.

For borides, hydrogen or / and nitrogen are used in gaseous hydrogens alone or in a batch. In the latter case, mixtures of borides and nitrides or complex compounds with boron and nitrogen, e.g. B. (Co, La, Ti) (B, N) ₃ .

A similar procedure can also be used for complex carbonitrides will. For this purpose, gaseous and / or vaporized substances are used that give off carbon and nitrogen.  

Two variants are technically special in chemical forming advantageous. Once all the alloyed material used be chemically formed and the second variant is that only part is reshaped; the remaining metal core then serves as a mechanical one Amplification or to power line.

The following procedure is also used for the production of oxidic PLCs advantageous.

On a metal support, e.g. B. copper wire, the oxides through Oxidation and / or pyrolysis of vaporized organic metal ver ties down. The organic part of the verb dung burned to gaseous substances and the oxides grow adherent on the wire and react with each other to form complex oxide compounds. This should be explained using an example.

Chemical vapor deposition turns oxides from strontium, Lanthanum and cerium by oxidation of the corresponding alkoxy compounds deposited in a mixture of oxygen and water vapor.

Instead of the alkoxy compounds there are also the corresponding acetyl acetonates and organic complexes with one or more Metals can be used in the complex.

Crown ethers can also be used.

The organic part of the molecules is only used for transport and to volatilize the metals that are to be oxidized to SPS. The following example explains this:

A mixture of the acetylacetonates of cobalt, copper and cerium are in dissolved in a mixture of alcohol, ether and acetone and fed to a burner operated with oxygen / propane. With such a flame, SPS can be applied to metals and ceramics be burned, e.g. B. in the form of conductor tracks or homogeneous in Layers up to a thickness of approx. 0.1 mm. Through targeted oxidation Depending on the flame, the oxides can be oxidized in different ways separate stage.  

Working with organic compounds as vehicles for The PLC also allows metals to be screen-printed on metals and / or Apply ceramics.

To do this, the organic metal compounds are thickened medium dissolved and / or dispersed, optionally with the addition of Metal and / or master alloy powders.

The mass is screen printed on metals or ceramics as conductor tracks or switching elements applied. Then the printed ones Parts in a reactive, e.g. B. oxidizing atmosphere or Oxygen plasma converted to PLC.

Furthermore, working with organic metal compounds allows Manufacture of varnishes similar to ver be working. For this purpose, the paints, the organic metal ver Minority bonds included on the metal or ceramic or semiconductor carrier applied in a layer of 0.1 to 10 microns and then using an electron beam in an oxygen atmosphere lithographed sphere.

In this way, conductor structures can be made from warm superconductors aims to apply. The rest of the paint layer is covered with a suitable one Solvent removed.

Before removing the paint layer with metals or another Material such as oxides, sulfides coated, so finally remains a system of superconductors with a Cover layer made of oxides, sulfides or metals.

Wrapping the body produced according to 3. is for mechanical reinforcement, Insulation and / or power line.

The coating with metals, alloys can be electrochemical, electroless done chemically or by vapor deposition.  

The coating with plastics takes place by spraying on paints or Wrapping polyethylene, PVC and. a. Polymers.

The procedure outlined thus allows wires and strips to make from brittle materials, without breaking and without losing their magnetic or electrical properties, too Coils can be wound. Are particularly easy to process Wires and bands that still have a metal core in their axis and are covered on the outside with a metal jacket and a plastic layer.

Wires with a metal core can also be made from a dough-like mass of produce the necessary oxides, borides, carbides, nitrides or sulfides is pressed through nozzles and at the same time a metal wire in the longitudinal axis is carried along. In this way, wires can be made from PLC, which have a diameter of 0.1 mm and one in the soul Have copper wire, the z. B. has a thickness of 25 microns.

The extruded, "green" wires must ver at elevated temperature be consolidated. The remaining porosity is then passed through electrochemical deposition of metal eliminated.

Tubular bodies can be produced in the same way. Instead of of the central wire, several wires are carried in the tube module.

Such wires and tubes are extremely suitable for production of superconducting magnets and for hot electric. For wrapping and filling the pores are particularly suitable for gold, silver, lead, tin, copper, nickel, Cobalt, iron, aluminum, tungsten, molybdenum and the like. a. Transition elements.

In this way, warm and hot superconductors can be made from triploxides manufacture that contain several fine copper wires as a soul and whose pores are filled with copper and / or silver.

The wire from the PLC can then, as described above, again with a dough-like oxide mass are encased, a wire mesh for reinforcement kung is incorporated. The green layer in turn increases Solidified temperature and finally with one of the above. Metals encased.  

In the same way, tapes can be produced that are self-supporting or firmly on a carrier material made of non-superconducting material lie.

This can also be used to reinforce the green wires made of PLC be that the mixture of SPS additional metal oxides and / or metal sulfides are added, which are reduced to metal in hydrogen to let. The reduction can coincide with the solidification of the green success.

An example should make this clear.

A dough-like mixture of barium oxide, cerium oxide and titanium oxide contains too one tenth of copper oxide (CuO). Such a mixture can be with a Extrude core from nickel or copper and at 800 ° C in pure water material for extremely strong and largely unbreakable oxide wires to process. As solidifying oxides, sulfides are those that are Hydrogen can be reduced up to approx. 1000 ° C. These are largely the Oxides and sulfides of transition metals. In the same way with a Mixture of barium oxide, lanthanum oxide and copper oxide worked.

Reduction with hydrogen has another advantage. With her can the sulfides, oxides and nitrides that carry superconductivity, in lower oxidation levels are transferred; in this way the Jump temperature can be set.

Claims (12)

1. Process for the production of wire, tape or tubular bodies from brittle substances such as borides, carbides, oxides or sulfides of the A and B metals, characterized in that the elemental metals and / or their master alloys are alloyed, then to wire - Shaped, band-shaped or tubular, metallic bodies and then the bodies thus obtained are completely or partially borated, carbidized, oxidized and / or sulfided by means of a reactive gas phase and finally completely covered with a metal jacket or the brittle materials, in particular oxides, are considered to be dough-like Mass extruded into wire, ribbon or tubular bodies, one or more fine wires being carried in the core of the extrudate at the same time and the green wires then being solidified at elevated temperature and finally being coated with a metal sheath. 2. The method according to claim 1, characterized in that the A and B-metals by melting the metals alone or their master alloys be alloyed and the melt is formed into bars. 3. The method according to claim 1, characterized in that the A and B metals alloyed by sintering and / or hot pressing the metal powder and formed into bars. 4. The method according to claim 1 to 3, characterized in that the metallic bars into wire, ribbon or tubular bodies processed according to known forming processes. 5. The method according to claim 4, characterized in that the shaped, metallic bodies in a reactive gas phase, the boron, carbon, Releases oxygen and / or sulfur to brittle substances such as borides, Carbides, oxides and / or sulfides and their complex compounds be chemically formed.   6. The method according to claim 5, characterized in that the brittle Body covered with metals and possibly soaked with metals will. 7. The method according to claim 1, characterized in that the chemical Forming into brittle substances, especially oxides through oxidation of organometallic compounds in an oxygen-containing atmosphere he follows. 8. The method according to claim 1, characterized in that the production of shaped, brittle bodies by simultaneously extruding one dough-like mass and metal wires, the metal wires have a much smaller diameter than the whole Extrudate. 9. The method according to claim 1, characterized in that as an output product organic metal compounds, organic metal complex compounds used in a boriding, carbide ionizing, nitriding, oxidizing or sulfidizing Atmosphere to be brittle. 10. The method according to claim 9, characterized in that the forming with the help of chemical vapor deposition, pyrolysis. 11. The method according to claim 9, characterized in that the organic Metal compounds are processed in screen printing and then be formed according to claim 9 and / or 10. 12. The method according to claim 9, characterized in that the organic Metal compounds in the form of paints processed and attached closing by means of electron beams or laser beams and reactive gases such as oxygen, nitrogen and. a. to brittle fabrics, in particular to be formed into conductor tracks.