WO2006032559A1 - Method for producing a ceramic precursor - Google Patents

Method for producing a ceramic precursor Download PDF

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Publication number
WO2006032559A1
WO2006032559A1 PCT/EP2005/053570 EP2005053570W WO2006032559A1 WO 2006032559 A1 WO2006032559 A1 WO 2006032559A1 EP 2005053570 W EP2005053570 W EP 2005053570W WO 2006032559 A1 WO2006032559 A1 WO 2006032559A1
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Prior art keywords
precursor
pyrolysis
contact wires
ceramic
liquid
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PCT/EP2005/053570
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German (de)
French (fr)
Inventor
Gert Lindemann
Alexander Klonczynski
Martin KÖHNE
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Robert Bosch Gmbh
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    • C04B35/515—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics
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    • C04B35/565—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on non-oxide ceramics based on carbides or oxycarbides based on silicon carbide
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    • C04B35/62605—Treating the starting powders individually or as mixtures
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    • H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
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    • C04B2235/48—Organic compounds becoming part of a ceramic after heat treatment, e.g. carbonising phenol resins
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Definitions

  • the invention generally relates to a method for producing a precursor ceramic according to the preamble of the independent claim. Specifically, the invention relates to the preparation of such precursor ceramics having contact wires. The invention also relates to a precursor ceramic produced by means of the method.
  • amorphous SiOC ceramics are obtained by pyrolysis of elemental organic precursors.
  • Advantages of the precursor thermolysis process compared to the conventional production methods for ceramics (sintering) are the significantly lower process temperatures and the simple processability and moldability of polysiloxane resins.
  • the development of the ceramic glow plug aims at a further reduction of the diameter of the ceramic glow plug and the integration of other functions (eg pressure measurement in the combustion chamber).
  • the electrical contact on the surface of the ceramic glow plug is considerably more complex.
  • An inexpensive variant of the contacting is to contact wires in the plastic molding of the glow plug precursor so that it sits part of the contact wire in the glow plug and the other part protrudes as a free end.
  • the integration of a pressure sensor in the ceramic glow plug requires two contact wires, through which the measurement signal can be tapped from the pressure sensor.
  • a serious disadvantage of direct contacting with encapsulation of the contact wires in the shaping is that due to the pyrolysis necessary for the production of the ceramic glow pencil in a reducing atmosphere and the subsequent heat treatment in an oxidizing atmosphere (both processes take place at temperatures above 1200 ° C.) the demands on the chemical resistance of the contact wires are extremely high. Suitable wires are therefore disproportionately expensive.
  • the aim of the present invention is therefore to avoid the disadvantages of the prior art and to protect the contact wires in a simple manner against oxidation. It should be noted that the present invention is not only applicable to ceramic glow plugs, but can be made using the inventive method any heater.
  • the inventive method for the production of precursor ceramics by pyrolysis of oxygen-containing organoelement precursor polymer moldings has the advantage over the prior art that in a simple manner protect the contact wires on a molded part of precursor ceramic from oxidation during the heat treatment to let.
  • the core of the invention is the use of preparations of precursors, such as e.g. organosilicon precursors such as polysilsesquioxanes, polysiloxanes, polycarbosilanes and polysilanes or the use of organoaluminum precursors such as aluminoxanes as dip coating for the coating of the free ends of contact wires.
  • precursors such as e.g. organosilicon precursors such as polysilsesquioxanes, polysiloxanes, polycarbosilanes and polysilanes or the use of organoaluminum precursors such as aluminoxanes as dip coating for the coating of the free ends of contact wires.
  • organosilicon precursors such as polysilsesquioxanes, polysiloxanes, polycarbosilanes and polysilanes
  • organoaluminum precursors such as aluminoxanes
  • the preparation may further contain, in particular for the organosilicon precursors, additives, e.g. Boron, cerium, bismuth, sodium, etc., for the adjustment of certain properties, e.g. Viscosity, layer thickness, coefficient of thermal expansion, wetting of the contact wire by the oxidation protection layer, the ceramic resulting from the precursor.
  • additives e.g. Boron, cerium, bismuth, sodium, etc.
  • certain properties e.g. Viscosity, layer thickness, coefficient of thermal expansion, wetting of the contact wire by the oxidation protection layer, the ceramic resulting from the precursor.
  • the adjustment of the rheological properties e.g., thixotropy
  • fumed silica and / or organosilicon precursors in combination with organoaluminum precursors (aluminoxanes) a film can be produced which contains mullite after the heat treatment.
  • the free ends of the contact wires are dipped before the pyrolysis of the molding in a bath of a preparation of a precursor.
  • the adhering film of the preparation transforms into a ceramic during pyrolysis.
  • This ceramic film is oxidized on its surface during the subsequent heat treatment in an oxygen-containing atmosphere, in the case of the organosilicon precursors to SiO 2 , in the case of the organoaluminum precursors to Al 2 O 3 .
  • SiO 2 and Al 2 O 3 are strong diffusion barriers for oxygen, so that this SiO 2 or Al 2 O 3 layer on the free end of the Contact wire protects this during the heat treatment from oxidation by oxygen. By grinding only one contact point, the wire continues to be protected against corrosion.
  • Suitable precursors are the following polymers: polysiloxanes, polysilsesquioxanes, polycarbosilanes, polysilanes and aluminoxanes.
  • additives for adjusting the melt viscosity of the film in the case of organosilicon precursors u.a. the following elements and their organic and inorganic compounds are used: boron, bismuth, barium, sodium.
  • additives are preferably added to the preparation as nanopowder of the element or of the oxide or in liquid organic element form (also in dissolved elemental organic form).
  • liquid organoelemental forms are:
  • Polymethylsilsesquioxane 30.0% by mass of xylene or acetone as solvent
  • the free ends of the contact wires that is, the part of the contact wires, which protrudes from the molded part, which was prepared from the precursor of the ceramic glow pencil by plastic molding, immersed in the liquid.
  • the subsequent pyrolysis is carried out under the following conditions: heating at 200 K / min until 1300 ° C are reached; 2h hold at 1300 ° C; Cool at 300 K / min until room temperature is reached.
  • the electrically insulating oxidation protection layer must be removed from the contact wire end. This can be done with two different methods:
  • the wire ends are pressed flat by means of a roller or press. Due to the deformation of the contact wire, the oxidation protection layer bursts in the deformed region of the wire.
  • the oxidation protection layer is mechanically removed by scraping or grinding.
  • the thickness of the SiOC-SiO 2 -FiImS is depending on the order quantity of the precursor between 1 and 10 microns.
  • An unprotected molybdenum wire is completely oxidized to volatile oxides after heat treatment at 1300 0 C in air.
  • a molybdenum wire treated with the method according to the invention is still intact after the same heat treatment.

Abstract

The invention relates to a method for producing a ceramic precursor by the pyrolysis of elemental organic polymer precursor moulded parts that contain oxygen. According to the invention, the polymer precursor moulded parts comprise contact wires, one end of which protrudes freely from the moulded part. Prior to pyrolysis, said end of the contact wires is coated with a liquid, which contains a precursor that is converted into a ceramic during the pyrolytic process.

Description

Verfahren zur Herstellung einer PrecursorkeramikProcess for the preparation of a precursor ceramic
Die Erfindung betrifft allgemein ein Verfahren zur Herstellung einer Precursor-Keramik nach dem Oberbegriff des unabhängigen Anspruchs. Speziell betrifft die Erfindung die Herstellung solcher Precursor-Keramiken, die Kontaktdrähte aufweisen. Die Erfindung betrifft außerdem eine mit Hilfe des Verfahrens hergestellte Precursor-Keramik.The invention generally relates to a method for producing a precursor ceramic according to the preamble of the independent claim. Specifically, the invention relates to the preparation of such precursor ceramics having contact wires. The invention also relates to a precursor ceramic produced by means of the method.
Stand der TechnikState of the art
Bei der Herstellung von keramischen Glühstiftkerzen aus Keramik- Verbundwerkstoffen werden durch die Pyrolyse von elementorganischen Precursoren amorphe SiOC - Keramiken gewonnen. Vorteile des Precursor-Thermolyse- Verfahrens gegenüber den konventionellen Herstellungsverfahren für Keramiken (Sintern) sind die wesentlich niedrigeren Prozesstemperaturen und die einfache Verarbeitbarkeit und Formbarkeit von Polysiloxanharzen.In the production of ceramic glow plugs from ceramic composite materials, amorphous SiOC ceramics are obtained by pyrolysis of elemental organic precursors. Advantages of the precursor thermolysis process compared to the conventional production methods for ceramics (sintering) are the significantly lower process temperatures and the simple processability and moldability of polysiloxane resins.
Die Herstellung von Formkörpern ist aber nur bei Einsatz von zusätzlichen Füllstoffen möglich, da sonst Schwindungsrisse und Poren während der Pyrolyse auftreten. Mittels geeigneter Füllstoffe lassen sich auf diese Weise die Eigenschaften (Wärmeausdehnungs¬ koeffizient, Wärmeleitfähigkeit, spezifischer elektrischer Widerstand) des Komposits genau einstellen. Hierbei ist es möglich, wie in der EP-B-O 412 428 offenbart, reaktive Füller einzusetzen, um eine bessere Anbindung der Füllstoffe an die Matrix zu erreichen oder auch inerte Füllstoffe zu verwenden.However, the production of moldings is only possible with the use of additional fillers, as otherwise shrinkage cracks and pores occur during pyrolysis. By means of suitable fillers, the properties (coefficient of thermal expansion, thermal conductivity, specific electrical resistance) of the composite can be precisely adjusted in this way. In this case, it is possible, as disclosed in EP-B-0 412 428, to use reactive fillers in order to achieve better bonding of the fillers to the matrix or to use inert fillers.
Die Entwicklung der keramischen Glühstiftkerze zielt auf eine weitere Reduktion des Durchmessers der keramischen Glühstiftkerze sowie der Integration weiterer Funktionen (z.B. Druckmessung im Brennraum). Durch die Reduktion des Durchmessers der Glühstiftkerze wird die elektrische Kontaktierung auf der Oberfläche des keramischen Glühstifts erheblich aufwändiger. Eine kostengünstige Variante der Kontaktierung ist es, Kontaktdrähte bei der kunststofftechnischen Formgebung des Glühstift-Precursors zu umspritzen, so dass es ein Teil des Kontaktdrahtes im Glühstift sitzt und der andere Teil als freies Ende herausragt. Auch die Integration eines Drucksensors in den keramischen Glühstift erfordert zwei Kontaktdrähte, durch die das Messsignal vom Drucksensor abgegriffen werden kann.The development of the ceramic glow plug aims at a further reduction of the diameter of the ceramic glow plug and the integration of other functions (eg pressure measurement in the combustion chamber). By reducing the diameter of the glow plug, the electrical contact on the surface of the ceramic glow plug is considerably more complex. An inexpensive variant of the contacting is to contact wires in the plastic molding of the glow plug precursor so that it sits part of the contact wire in the glow plug and the other part protrudes as a free end. Also, the integration of a pressure sensor in the ceramic glow plug requires two contact wires, through which the measurement signal can be tapped from the pressure sensor.
Ein schwerwiegender Nachteil der direkten Kontaktierung mit Umspritzen der Kontaktdrähte bei der Formgebung ist, dass auf Grund der für die Herstellung des keramischen Glühstifts notwendigen Pyrolyse in reduzierender Atmosphäre und der anschließenden Wärmebehandlung in oxidierender Atmosphäre (beide Prozesse laufen bei Temperaturen oberhalb von 1200°C ab) die Anforderung an die chemische Beständigkeit der Kontaktdrähte extrem hoch sind. Geeignete Drähte sind daher unverhältnismäßig teuer.A serious disadvantage of direct contacting with encapsulation of the contact wires in the shaping is that due to the pyrolysis necessary for the production of the ceramic glow pencil in a reducing atmosphere and the subsequent heat treatment in an oxidizing atmosphere (both processes take place at temperatures above 1200 ° C.) the demands on the chemical resistance of the contact wires are extremely high. Suitable wires are therefore disproportionately expensive.
Ziel der vorliegenden Erfindung ist es daher, die Nachteile des Standes der Technik zu vermeiden und die Kontaktdrähte auf einfache Weise gegen Oxidation zu schützen. Dabei ist anzumerken, dass die vorliegende Erfindung nicht nur auf keramische Glühstiftkerzen anwendbar ist, vielmehr können mit Hilfe des erfindungsgemäßen Verfahrens beliebige Heizer hergestellt werden.The aim of the present invention is therefore to avoid the disadvantages of the prior art and to protect the contact wires in a simple manner against oxidation. It should be noted that the present invention is not only applicable to ceramic glow plugs, but can be made using the inventive method any heater.
Vorteile der ErfindungAdvantages of the invention
Das erfindungsgemäße Verfahren zur Herstellung von Precursor-Keramiken durch Pyrolyse von sauerstoffhaltigen elementorganischen Precursor-Polymer-Formteilen hat gegenüber dem Stand der Technik den Vorteil, dass sich damit auf einfache Art und Weise die Kontaktdrähte an einem Formteil aus Precursorkeramik vor einer Oxidation während der Wärmebehandlung schützen lassen.The inventive method for the production of precursor ceramics by pyrolysis of oxygen-containing organoelement precursor polymer moldings has the advantage over the prior art that in a simple manner protect the contact wires on a molded part of precursor ceramic from oxidation during the heat treatment to let.
Weiterhin ist vorteilhaft, dass das Verfahren relativ kostengünstig ist.Furthermore, it is advantageous that the method is relatively inexpensive.
Ein weiterer Vorteil liegt darin, dass preisgünstige, nicht oxidationsstabile metallische Drähte verwendet werden können. Vorteilhafte Weiterbildungen der Erfindung ergeben sich aus den in den Unteransprüchen genannten Maßnahmen.Another advantage is that inexpensive, non-oxidation-stable metallic wires can be used. Advantageous developments of the invention will become apparent from the measures mentioned in the dependent claims.
AusiührungsbeispieleAusiührungsbeispiele
Kern der Erfindung ist die Verwendung von Zubereitungen aus Precursoren, wie z.B. siliziumorganischen Precursoren wie Polysilsesquioxanen, Polysiloxanen, Polycarbosilanen und Polysilanen oder die Verwendung von aluminiumorganischen Precursoren wie Aluminoxanen als Tauchlack für die Beschichtung der freien Enden von Kontaktdrähten. Die Zubereitungen können die Precursoren in flüssiger, gelöster oder geschmolzener Form enthalten.The core of the invention is the use of preparations of precursors, such as e.g. organosilicon precursors such as polysilsesquioxanes, polysiloxanes, polycarbosilanes and polysilanes or the use of organoaluminum precursors such as aluminoxanes as dip coating for the coating of the free ends of contact wires. The preparations may contain the precursors in liquid, dissolved or molten form.
Die Zubereitung kann insbesondere für die siliziumorganischen Precursoren weiterhin Additive enthalten, wie z.B. Bor, Cer, Wismut, Natrium, etc., für die Einstellung bestimmter Eigenschaften wie z.B. Viskosität, Schichtdicke, Wärmeausdehnungskoeffizient, Benetzung des Kontaktdrahtes durch die Oxidationsschutzschicht, der aus dem Precursor entstehenden Keramik. So lässt sich bspw. durch Zugabe von pyrogener Kieselsäure die Einstellung der Theologischen Eigenschaften (z.B. Thixotropierung) der Zubereitung variieren. Durch Verwendung von pyrogener Kieselsäure und/oder siliziumorganischer Precursoren in Kombination mit aluminiumorganischen Precursoren (Aluminoxane) kann ein Film erzeugt werden, der nach der Wärmebehandlung Mullit enthält.The preparation may further contain, in particular for the organosilicon precursors, additives, e.g. Boron, cerium, bismuth, sodium, etc., for the adjustment of certain properties, e.g. Viscosity, layer thickness, coefficient of thermal expansion, wetting of the contact wire by the oxidation protection layer, the ceramic resulting from the precursor. For example, by adding fumed silica, the adjustment of the rheological properties (e.g., thixotropy) of the formulation can be varied. By using fumed silica and / or organosilicon precursors in combination with organoaluminum precursors (aluminoxanes), a film can be produced which contains mullite after the heat treatment.
Mit Hilfe der vorliegenden Erfindung lassen sich auf einfache Art und Weise freie Enden von Kontaktdrähten, die aus einem Formteil aus Precursorkeramik hervorstehen, vor der Oxidation während der Wärmebehandlung in sauerstoffhaltiger Atmosphäre schützen. Dazu werden die freien Enden der Kontaktdrähte vor der Pyrolyse des Formteils in ein Bad aus einer Zubereitung eines Precursors getaucht. Der anhaftende Film der Zubereitung wandelt sich während der Pyrolyse in eine Keramik um. Dieser keramische Film wird während der nachfolgenden Wärmebehandlung in sauerstoffhaltiger Atmosphäre an seiner Oberfläche oxidiert, im Falle der siliziumorganischen Precursoren zu SiO2, im Falle der aluminiumorganischen Precursoren zu Al2O3. SiO2 und Al2O3 sind starke Diffusionsbarrieren für Sauerstoff, so dass diese SiO2- bzw. Al2O3 -Schicht auf dem freien Ende des Kontaktdrahtes diesen während der Wärmebehandlung vor der Oxidation durch Sauerstoff schützt. Durch Anschleifen nur einer Kontaktstelle bleibt der Draht auch weiterhin vor Korrosion geschützt.With the aid of the present invention, it is possible in a simple manner to protect free ends of contact wires, which protrude from a precursor ceramic molding, from oxidation during the heat treatment in an oxygen-containing atmosphere. For this purpose, the free ends of the contact wires are dipped before the pyrolysis of the molding in a bath of a preparation of a precursor. The adhering film of the preparation transforms into a ceramic during pyrolysis. This ceramic film is oxidized on its surface during the subsequent heat treatment in an oxygen-containing atmosphere, in the case of the organosilicon precursors to SiO 2 , in the case of the organoaluminum precursors to Al 2 O 3 . SiO 2 and Al 2 O 3 are strong diffusion barriers for oxygen, so that this SiO 2 or Al 2 O 3 layer on the free end of the Contact wire protects this during the heat treatment from oxidation by oxygen. By grinding only one contact point, the wire continues to be protected against corrosion.
Als Precursoren kommen folgende Polymere in Frage: Polysiloxane, Polysilsesquioxane, Polycarbosilane, Polysilane und Aluminoxane.Suitable precursors are the following polymers: polysiloxanes, polysilsesquioxanes, polycarbosilanes, polysilanes and aluminoxanes.
Als Zusatzstoffe zur Einstellung der Schmelzviskosität des Films bei siliziumorganischen Precursoren (nach der Keramisierung durch die Wärmebehandlung) können u.a. folgende Elemente sowie deren organische und anorganische Verbindungen verwendet werden: Bor, Wismut, Barium, Natrium.As additives for adjusting the melt viscosity of the film in the case of organosilicon precursors (after the ceramization by the heat treatment) u.a. the following elements and their organic and inorganic compounds are used: boron, bismuth, barium, sodium.
Figure imgf000005_0001
Figure imgf000005_0001
Wirkung: + erniedrigend o neutral - erhöhendEffect: + degrading o neutral - increasing
Diese Zusatzstoffe werden bevorzugt als Nanopulver des Elements oder des Oxids oder in flüssiger elementorganischer Form (auch in gelöster elementorganischer Form) der Zubereitung zugegeben. Beispiele für flüssige elementorganische Formen sind:These additives are preferably added to the preparation as nanopowder of the element or of the oxide or in liquid organic element form (also in dissolved elemental organic form). Examples of liquid organoelemental forms are:
Bor- Verbindungen Wismut- Verbindungen Barium- VerbindungenBoron compounds Bismuth compounds Barium compounds
Triethylborat Wismut-2-ethylhexaonat Barium-2-ethylhexaonat Tri-i-propylborat Wismut-neodecanoat Barium-i-propoxidTriethyl borate bismuth 2-ethylhexaonate barium 2-ethylhexaonate tri-i-propylborate bismuth neodecanoate barium i-propoxide
Natrium- VerbindungenSodium compounds
Natriumacetat (Smp.: ca. 580C) Natriumisopropoxid (Smp.: 70-750C)Sodium acetate (mp .: about 58 0 C) sodium isopropoxide (mp .: 70-75 0 C)
Smp. = SchmelzpunktM.p. = melting point
Beispielexample
Einwiegen von:Weighing of:
68,7 Masse-% GR 650 F (Hersteller: Techneglas) (Zusammensetzung:68.7 mass% GR 650 F (manufacturer: Techneglas) (composition:
Polymethylsilsesquioxan) 30,0 Masse-% Xylol oder Aceton als LösungsmittelPolymethylsilsesquioxane) 30.0% by mass of xylene or acetone as solvent
1,0 Masse-% Bor (Hersteller: HC-Starck) elementar oder bspw. 2 Massen-% Barium- i- propoxid1.0% by mass boron (manufacturer: HC-Starck) elemental or, for example, 2% by mass barium i-propoxide
0,3 Mase-% AEROSIL© R 812 S (Hersteller: Degussa; Zusammensetzung: pyrogene Kieselsäure) zur Einstellung eines thixotropen Theologischen Verhaltens für eine bessere Verabeitung0.3% by mass AEROSIL © R 812 S (manufacturer: Degussa; composition: fumed silica) for the adjustment of a thixotropic theological behavior for a better handling
100g dieser Mischung wird in einem Mischgefäß eingewogen und 10 min lang mit einem Rührer (z.B., Ultraturax (Hersteller: IKA- Werke)) gerührt.100 g of this mixture is weighed into a mixing vessel and stirred for 10 minutes with a stirrer (e.g., Ultraturax (manufacturer: IKA-Werke)).
Anschließend werden die freien Enden der Kontaktdrähte, d.h., der Teil der Kontaktdrähte, der aus dem Formteil herausragt, das aus dem Precursor des keramischen Glühstifts durch kunststofftechnische Formgebung hergestellt wurde, in die Flüssigkeit eingetaucht. Die anschließende Pyrolyse wird unter folgenden Bedingungen durchgeführt: Aufheizen mit 200 K/min, bis 1300°C erreicht sind; 2h Halten bei 1300°C; Abkühlen mit 300 K/min, bis Raumtemperatur erreicht ist.Subsequently, the free ends of the contact wires, that is, the part of the contact wires, which protrudes from the molded part, which was prepared from the precursor of the ceramic glow pencil by plastic molding, immersed in the liquid. The subsequent pyrolysis is carried out under the following conditions: heating at 200 K / min until 1300 ° C are reached; 2h hold at 1300 ° C; Cool at 300 K / min until room temperature is reached.
Die anschließende Wärmebehandlung in Luft findet unter folgenden Bedingungen statt:The subsequent heat treatment in air takes place under the following conditions:
Aufheizen mit 200 K/min, bis 13000C erreicht sind; 2 h Halten bei 13000C;Heating at 200 K / min until 1300 0 C are reached; 2 h hold at 1300 0 C;
Abkühlen mit 300 K/min, bis Raumtemperatur erreicht ist.Cool at 300 K / min until room temperature is reached.
An Stelle von Bor können Wismut und/oder Barium und/oder Natrium bzw. deren Verbindungen in ähnlichen Mengen zugegeben werden.In place of boron bismuth and / or barium and / or sodium or their compounds may be added in similar amounts.
Bevor die elektrische Kontaktierung durchgeführt wird, muss die elektrisch isolierende Oxidationsschutzschicht vom Kontaktdrahtende entfernt werden. Dies kann mit zwei verschiedenen Verfahren durchgeführt werden:Before the electrical contacting is carried out, the electrically insulating oxidation protection layer must be removed from the contact wire end. This can be done with two different methods:
Die Drahtenden werden mittels einer Walze oder Presse flachgepresst. Durch die Deformation des Kontaktdrahtes platzt die Oxidationsschutzschicht im deformierten Bereich von dem Draht ab.The wire ends are pressed flat by means of a roller or press. Due to the deformation of the contact wire, the oxidation protection layer bursts in the deformed region of the wire.
Die Oxidationsschutzschicht wird mechanisch durch Schaben oder Schleifen entfernt.The oxidation protection layer is mechanically removed by scraping or grinding.
Die Dicke des SiOC-SiO2-FiImS liegt je nach Auftragsmenge des Precursors zwischen 1 und 10 μm. Ein ungeschützter Molybdändraht ist nach der Wärmebehandlung bei 13000C in Luft vollständig zu flüchtigen Oxiden oxidiert. Ein mit dem erfindungsgemäßen Verfahren behandelter Molybdändraht ist nach der gleichen Wärmebehandlung noch intakt. The thickness of the SiOC-SiO 2 -FiImS is depending on the order quantity of the precursor between 1 and 10 microns. An unprotected molybdenum wire is completely oxidized to volatile oxides after heat treatment at 1300 0 C in air. A molybdenum wire treated with the method according to the invention is still intact after the same heat treatment.

Claims

Ansprüche claims
1. Verfahren zur Herstellung einer Precursor-Keramik durch Pyrolyse von sauerstoffhaltigen elementorganischen Precursor-Polymer-Formteilen, wobei die Precursor- Polymer-Formteile Kontaktdrähte aufweisen, bei denen ein Ende frei aus dem Formteil herausragt, dadurch gekennzeichnet, dass das frei aus dem Formteil herausragende Ende der Kontaktdrähte vor der Pyrolyse mit einer Flüssigkeit beschichtet wird, die einen Precursor enthält, der sich während der Pyrolyse in eine Keramik umwandelt.1. A method for producing a precursor ceramic by pyrolysis of oxygen-containing element organic precursor polymer moldings, wherein the precursor polymer molded parts comprise contact wires, wherein one end protrudes freely from the molded part, characterized in that the free protruding from the molded part The end of the contact wires is coated prior to pyrolysis with a liquid containing a precursor, which is converted into a ceramic during pyrolysis.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass die Flüssigkeit den Precursor in flüssiger, gelöster oder geschmolzener Form enthält.2. The method according to claim 1, characterized in that the liquid contains the precursor in liquid, dissolved or molten form.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass der Precursor ein Polymer ist, ausgewählt aus der Gruppe bestehend aus Polysiloxane, Polysilsesquioxane, Polycarbosilane, Polysilane und Aluminoxane.3. The method according to claim 1 or 2, characterized in that the precursor is a polymer selected from the group consisting of polysiloxanes, polysilsesquioxanes, polycarbosilanes, polysilanes and aluminoxanes.
4. Verfahren nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, dass die Flüssigkeit zusätzlich Additive enthält.4. The method according to any one of the preceding claims, characterized in that the liquid additionally contains additives.
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass die Additive ausgewählt sind aus der Gruppe bestehend aus Bor, Wismut, Barium und Natrium sowie deren organischen und anorganischen Verbindungen.5. The method according to claim 4, characterized in that the additives are selected from the group consisting of boron, bismuth, barium and sodium and their organic and inorganic compounds.
6. Verfahren nach Anspruch 4, dadurch gekennzeichnet, dass das Additiv pyrogene Kieselsäure ist. 6. The method according to claim 4, characterized in that the additive is fumed silica.
7. Precursor-Keramik, hergestellt durch Pyrolyse von sauerstoffhaltigen elementorganischen Precursor-Polymer-Formteilen, wobei die Precursor-Polymer-Formteile Kontaktdrähte aufweisen, bei denen ein Ende frei aus dem Formteil herausragt, dadurch gekennzeichnet, dass das frei aus dem Formteil herausragende Ende der Kontaktdrähte nach der Pyrolyse eine SiO2-, Al2O3- oder Alumosilikatschicht aufweist.7. precursor ceramic, produced by pyrolysis of oxygen-containing element organic precursor polymer moldings, wherein the precursor polymer molded parts comprise contact wires, wherein one end protrudes freely from the molded part, characterized in that the freely protruding from the molding end of the Contact wires after pyrolysis, a SiO 2 -, Al 2 O 3 - or aluminosilicate layer has.
8. Oxidationsschutzschicht für freie Enden von in Precursor-Polymer-Formteilen enthaltenen Kontaktdrähten, dadurch gekennzeichnet, dass die Schutzschicht aus einer Flüssigkeit besteht, die einen Precursor enthält, der während der Pyrolyse in eine Keramik umwandelbar ist. 8. oxidation protection layer for free ends of contact wires contained in precursor polymer moldings, characterized in that the protective layer consists of a liquid containing a precursor which is convertible into a ceramic during pyrolysis.
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EP0848209A2 (en) * 1996-12-11 1998-06-17 Isuzu Ceramics Research Institute Co., Ltd. Ceramic heater and process for producing the same
US20030085214A1 (en) * 2001-11-07 2003-05-08 University Of Colorado At Boulder Micro-glow plug and method of making same field of the invention
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Publication number Priority date Publication date Assignee Title
EP2058823A1 (en) * 2007-11-06 2009-05-13 Honeywell International Inc. Flexible insulated wires for use in high temperatures and methods of manufacturing
US7795538B2 (en) 2007-11-06 2010-09-14 Honeywell International Inc. Flexible insulated wires for use in high temperatures and methods of manufacturing

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