EP0700058A1 - Process for protection of porous components submitted to high potential differences and components manufactured by this process - Google Patents

Process for protection of porous components submitted to high potential differences and components manufactured by this process Download PDF

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Publication number
EP0700058A1
EP0700058A1 EP95401954A EP95401954A EP0700058A1 EP 0700058 A1 EP0700058 A1 EP 0700058A1 EP 95401954 A EP95401954 A EP 95401954A EP 95401954 A EP95401954 A EP 95401954A EP 0700058 A1 EP0700058 A1 EP 0700058A1
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Prior art keywords
components
resin
porous
bath
potential differences
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EP95401954A
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German (de)
French (fr)
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EP0700058B1 (en
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Jean-Pierre Delvinquier
Christian Girardet
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C1/00—Details
    • H01C1/02—Housing; Enclosing; Embedding; Filling the housing or enclosure
    • H01C1/028—Housing; Enclosing; Embedding; Filling the housing or enclosure the resistive element being embedded in insulation with outer enclosing sheath

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  • the present invention relates to a method for protecting porous components subjected to high potential differences and to the components thus produced.
  • the overall electrical insulation of the electronic device is conventionally provided by a dielectric fluid, for example a mineral oil; this fluid is likely to penetrate into the porosities of the material. If the component is subjected to a high potential difference applied in a very short time, the dielectric fluid present in the cavities of the porous material can be partially destroyed and release conductive carbonaceous particles. Local degradation can then extend and lead to the short-circuiting of the component, which immediately leads to its total destruction. Another possibility of degradation exists if the dielectric fluid is capable of releasing gas bubbles under the effect of the electric field (phenomenon known as "degazing"). In this case, the gas bubble which is created in a microcavity is capable of generating a significant stress on the walls of the cavity and of cracking the material, which also leads to the destruction of the component.
  • a dielectric fluid for example a mineral oil
  • the subject of the present invention is a process for durable protection against electrical breakdowns with the minimum Joule loss, of porous components immersed in an insulating fluid, the protection products having to be compatible with the insulating fluid at temperatures up to about 150 ° C, which allows, when these components are subjected to high potential differences, and / or repeated electrical discharges at high voltage, to prevent their destruction, a process which is easy to implement and provides protection long term.
  • the present invention also relates to components comprising a porous part, which are protected against destruction when they are subject to high potential differences, and the cost price of which is not excessively increased by such protection.
  • the method according to the invention consists in carrying out a total impregnation of the porous components to be protected in a hot bath of polymerizable fluid resin which is polymerized after penetration into the porosities of these components.
  • porous components protected in accordance with the invention have their porosities filled with polymerized resin.
  • FIG. 1 shows the simplified diagram of an example of a high voltage circuit comprising a porous component.
  • the circuit of FIG. 1 comprises: a generator 1 comprising a high voltage output 2 producing, with respect to the ground, a high voltage HT, of 40 KV for example.
  • the generator 1 also has two outputs 3, 4 (the output 4 being connected to ground) between which a low voltage LV appears, supplying the filament of an electronic tube 5 (for example an output amplifier tube of a radio transmitter) whose cathode is connected to ground and the anode to the outlet 2 through a resistor 6 immersed in organic or mineral oil.
  • This resistance 6 is of low value (for example a few tens of ohms) and not inductive.
  • the material commonly used to make resistance 6 is a weakly conductive ceramic made from finely ground mineral elements, mixed and fired at high temperature to forming a slightly porous solid with excellent resistance to electrical and thermal stresses.
  • the protection conventionally employed against the penetration of dielectric fluids into porous components consists of a protective coating deposited on the surface.
  • This coating can be a paint, a varnish or a coating resin.
  • the coating material must constitute a waterproof film without any discontinuity and be able to tolerate without degradation the prolonged stay in the dielectric fluid under the conditions of operation of the material (pressure, temperature, vibrations, etc.;) and of possible mechanical attacks (scratches ).
  • This coating must adhere perfectly to the various supports: porous material constituting the body of the component, electrical connections, fixings, etc.).
  • the coating must have a high surface resistivity so as not to be the seat of significant leakage currents.
  • a resistor 7 thus treated.
  • This resistor 7 comprises a body 8 made of porous ceramic and two connection electrodes 9, 10 with their connection wires 11, 12.
  • the aforementioned treatment results in the formation of an outer protective layer 13 on the resistor 7, to the exclusion, of course, of the sons 11, 12 who are spared. If, for example at a point 14 of the layer 13 occurs a crack, a scratch or a puncture of this layer, the insulating oil in which this resistance is immersed ends up passing through this layer and penetrates into the porosities of the resistance, which can result in destruction as described above.
  • Another solution consists in using a very efficient dielectric fluid which has greater dielectric rigidity and does not release gas under the effect of electric discharges.
  • This solution excludes many common fluids, therefore inexpensive, and requires the use of synthetic compounds (silicone oil, perfluorinated fluids ”) much more expensive, and generally denser than mineral oils. traditional, which precludes their use in airborne equipment.
  • the proposed method consists of a total impregnation of the porous material using a very fluid resin which is subsequently polymerized to obtain a solid dielectric.
  • This solid dielectric therefore occupies all the cavities and porosities of the material and penetration of the dielectric fluid is made impossible.
  • the component mentioned above is a resistor, but it is obviously possible to treat other components comprising a substrate or a porous part, such as for example capacitors, coils.
  • the support can be ceramic or ferrite for example.
  • the method of the invention makes it possible, compared to known methods, at equal voltage, to significantly increase their service life, or else, for the same duration life, increase the voltage applied to these components, and / or use an ordinary oil bath instead of a high quality, very expensive oil.

Abstract

The protection method of porous components which are to be subject to large potential differences involves soaking the whole component in a hot bath of polymerisable fluid resin. The resin is polymerised after penetration into all the porous holes formed in the material. Before the soaking process, the fluid is heated under vacuum at a temperature at which it attains the required viscosity to penetrate in the pores of the material. The viscosity of the resin under these conditions is less than or equal to 0.5 Pa.s. The soaking process may be improved by subjecting the heated bath to pressure during the immersion.

Description

La présente invention se rapporte à un procédé de protection de composants poreux soumis à des différences de potentiel élevées et aux composants ainsi réalisés.The present invention relates to a method for protecting porous components subjected to high potential differences and to the components thus produced.

De nombreux dispositifs électroniques mettant en jeu des tensions élevées utilisent des composants élaborés à partir de matériaux poreux, par exemple des céramiques. Ces matériaux peuvent donc absorber par capillarité des fluides de faible viscosité.Many electronic devices involving high voltages use components made from porous materials, for example ceramics. These materials can therefore absorb low viscosity fluids by capillary action.

L'isolation électrique globale du dispositif électronique est classiquement assurée par un fluide diélectrique, par exemple une huile minérale ; ce fluide est susceptible de pénétrer dans les porosités du matériau. Si le composant est soumis à une différence de potentiel élevée appliquée en temps très court, le fluide diélectrique présent dans les cavités du matériau poreux peut être partiellement détruit et libérer des particules carbonées conductrices. La dégradation locale peut alors s'étendre et déboucher sur la mise en court-circuit du composant, ce qui entraîne immédiatement sa destruction totale. Une autre possibilité de dégradation existe si le fluide diélectrique est susceptible de libérer des bulles de gaz sous l'effet du champ électrique (phénomène dit de "degazing"). Dans ce cas, la bulle de gaz qui se crée dans une microcavité est capable de générer une contrainte importante sur les parois de la cavité et de fissurer le matériau, ce qui entraîne également la destruction du composant.The overall electrical insulation of the electronic device is conventionally provided by a dielectric fluid, for example a mineral oil; this fluid is likely to penetrate into the porosities of the material. If the component is subjected to a high potential difference applied in a very short time, the dielectric fluid present in the cavities of the porous material can be partially destroyed and release conductive carbonaceous particles. Local degradation can then extend and lead to the short-circuiting of the component, which immediately leads to its total destruction. Another possibility of degradation exists if the dielectric fluid is capable of releasing gas bubbles under the effect of the electric field (phenomenon known as "degazing"). In this case, the gas bubble which is created in a microcavity is capable of generating a significant stress on the walls of the cavity and of cracking the material, which also leads to the destruction of the component.

La présente invention a pour objet un procédé de protection durable contre les claquages électriques avec le minimum de pertes Joule, de composants poreux baignant dans un fluide isolant, les produits de protection devant être compatibles avec le fluide isolant à des températures pouvant aller jusqu'à environ 150°C, qui permette, lorsque ces composants sont soumis à des différences de potentiel élevées, et/ou à des décharges électriques répétées à tension élevée, d'éviter leur destruction, procédé qui soit facile à mettre en oeuvre et assure une protection de longue durée.The subject of the present invention is a process for durable protection against electrical breakdowns with the minimum Joule loss, of porous components immersed in an insulating fluid, the protection products having to be compatible with the insulating fluid at temperatures up to about 150 ° C, which allows, when these components are subjected to high potential differences, and / or repeated electrical discharges at high voltage, to prevent their destruction, a process which is easy to implement and provides protection long term.

La présente invention a également pour objet des composants comportant une partie poreuse, qui soient protégés contre la destruction lorsqu'ils sont soumis à des différences de potentiel élevées, et dont le prix de revient ne soit pas exagérément augmenté par une telle protection.The present invention also relates to components comprising a porous part, which are protected against destruction when they are subject to high potential differences, and the cost price of which is not excessively increased by such protection.

Le procédé conforme à l'invention consiste à réaliser une imprégnation totale des composants poreux à protéger dans un bain chaud de résine fluide polymérisable qui est polymérisée après pénétration dans les porosités de ces composants.The method according to the invention consists in carrying out a total impregnation of the porous components to be protected in a hot bath of polymerizable fluid resin which is polymerized after penetration into the porosities of these components.

Les composants poreux protégés conformément à l'invention ont leurs porosités remplies de résine polymérisée.The porous components protected in accordance with the invention have their porosities filled with polymerized resin.

La présente invention sera mieux comprise à la lecture de la description détaillée d'un mode de réalisation, pris à titre d'exemple non limitatif et illustré par le dessin annexé, sur lequel :

  • la figure 1 est le bloc-diagramme simplifié d'un appareil haute tension comportant une résistance à substrat poreux, qui doit être protégée contre les claquages, et
  • la figure 2 est une vue en coupe simplifiée d'un composant à substrat poreux protégé selon un procédé de l'art antérieur.
The present invention will be better understood on reading the detailed description of an embodiment, taken by way of nonlimiting example and illustrated by the appended drawing, in which:
  • FIG. 1 is the simplified block diagram of a high voltage device comprising a resistance on a porous substrate, which must be protected against breakdowns, and
  • FIG. 2 is a simplified sectional view of a component with a porous substrate protected according to a method of the prior art.

On a représenté en figure 1, le schéma simplifié d'un exemple de circuit haute tension comportant un composant poreux. Le circuit de la figure 1 comporte : un générateur 1 comportant une sortie haute tension 2 produisant, par rapport à la masse, une haute tension HT, de 40 KV par exemple. Le générateur 1 comporte également deux sorties 3, 4 (la sortie 4 étant reliée à la masse) entre lesquelles apparaît une basse tension BT alimentant le filament d'un tube électronique 5 (par exemple un tube amplificateur de sortie d'un émetteur radio) dont la cathode est reliée à la masse et l'anode à la sortie 2 à travers une résistance 6 baignant dans de l'huile organique ou minérale. Cette résistance 6 est de faible valeur (par exemple quelques dizaines d'ohms) et non inductive. Elle doit être capable d'absorber l'énergie de décharge des éléments capacitifs du générateur 1 (énergie pouvant être de 50 à 100 joules). S'il se produit des arcs électriques dans le tube 5, la haute tension se trouve reportée aux bornes de la résistance 6, et le courant instantané la traversant peut alors atteindre 1000 A.FIG. 1 shows the simplified diagram of an example of a high voltage circuit comprising a porous component. The circuit of FIG. 1 comprises: a generator 1 comprising a high voltage output 2 producing, with respect to the ground, a high voltage HT, of 40 KV for example. The generator 1 also has two outputs 3, 4 (the output 4 being connected to ground) between which a low voltage LV appears, supplying the filament of an electronic tube 5 (for example an output amplifier tube of a radio transmitter) whose cathode is connected to ground and the anode to the outlet 2 through a resistor 6 immersed in organic or mineral oil. This resistance 6 is of low value (for example a few tens of ohms) and not inductive. It must be able to absorb the discharge energy from the capacitive elements of generator 1 (energy which can be from 50 to 100 joules). If electric arcs occur in the tube 5, the high voltage is transferred to the terminals of the resistor 6, and the instantaneous current passing through it can then reach 1000 A.

Le matériau communément employé pour réaliser la résistance 6 est une céramique faiblement conductrice fabriquée à partir d'éléments minéraux finement broyés, mélangés et cuits à haute température pour former un solide légèrement poreux présentant une excellente résistance aux contraintes électriques et thermiques.The material commonly used to make resistance 6 is a weakly conductive ceramic made from finely ground mineral elements, mixed and fired at high temperature to forming a slightly porous solid with excellent resistance to electrical and thermal stresses.

Selon les procédés connus, la protection classiquement employée contre la pénétration des fluides diélectriques dans les composants poreux consiste en un revêtement protecteur déposé en surface.According to known methods, the protection conventionally employed against the penetration of dielectric fluids into porous components consists of a protective coating deposited on the surface.

Ce revêtement peut être une peinture, un vernis ou une résine d'enrobage. Le matériau de revêtement doit constituer un film étanche sans aucune discontinuité et pouvoir tolérer sans dégradation le séjour prolongé dans le fluide diélectrique dans les conditions d'exploitation du matériel (pression, température, vibrations, ..;) et des agressions mécaniques éventuelles (rayures). Ce revêtement doit adhérer parfaitement sur les différents supports : matériau poreux constituant le corps du composant, connexions électriques, fixations...).This coating can be a paint, a varnish or a coating resin. The coating material must constitute a waterproof film without any discontinuity and be able to tolerate without degradation the prolonged stay in the dielectric fluid under the conditions of operation of the material (pressure, temperature, vibrations, etc.;) and of possible mechanical attacks (scratches ). This coating must adhere perfectly to the various supports: porous material constituting the body of the component, electrical connections, fixings, etc.).

De plus, le revêtement doit présenter une forte résistivité de surface pour ne pas être le siège de courants de fuite notables.In addition, the coating must have a high surface resistivity so as not to be the seat of significant leakage currents.

Cet ensemble d'exigences fait que le matériau idéal est difficile à trouver, l'expérience montre que ce revêtement est un point critique qui limite les performances de tenue en tension du composant.This set of requirements makes the ideal material difficult to find, experience shows that this coating is a critical point which limits the performance of the component withstand tension.

On a schématiquement représenté en coupe, sur la figure 2, une résistance 7 ainsi traitée. Cette résistance 7 comporte un corps 8 en céramique poreuse et deux électrodes de connexion 9, 10 avec leurs fils de connexion 11, 12. Le traitement précité a pour résultat la formation d'une couche 13 de protection extérieure sur la résistance 7, à l'exclusion, bien entendu, des fils 11, 12 qui sont épargnés. Si, par exemple en un point 14 de la couche 13 se produit une fissure, une rayure ou une piqûre de cette couche, l'huile isolante dans laquelle est plongée cette résistance finit par traverser cette couche et pénètre dans les porosités de la résistance, ce qui peut en entraîner la destruction de la façon décrite ci-dessus.There is schematically shown in section, in Figure 2, a resistor 7 thus treated. This resistor 7 comprises a body 8 made of porous ceramic and two connection electrodes 9, 10 with their connection wires 11, 12. The aforementioned treatment results in the formation of an outer protective layer 13 on the resistor 7, to the exclusion, of course, of the sons 11, 12 who are spared. If, for example at a point 14 of the layer 13 occurs a crack, a scratch or a puncture of this layer, the insulating oil in which this resistance is immersed ends up passing through this layer and penetrates into the porosities of the resistance, which can result in destruction as described above.

Une autre solution consiste en l'utilisation d'un fluide diélectrique très performant qui présente une plus grande rigidité diélectrique et ne libère pas de gaz sous l'effet des décharges électriques. Cette solution exclut beaucoup de fluides courants, donc peu chers, et oblige à utiliser des composés synthétiques (huile de silicone, fluides perfluorés...) beaucoup plus chers, et généralement plus denses que les huiles minérales traditionnelles, ce qui écarte leur utilisation dans les équipements aéroportés.Another solution consists in using a very efficient dielectric fluid which has greater dielectric rigidity and does not release gas under the effect of electric discharges. This solution excludes many common fluids, therefore inexpensive, and requires the use of synthetic compounds (silicone oil, perfluorinated fluids ...) much more expensive, and generally denser than mineral oils. traditional, which precludes their use in airborne equipment.

Selon l'invention, pour interdire définitivement toute possibilité de pénétration du fluide diélectrique, la méthode proposée consiste en une imprégnation totale du matériau poreux à l'aide d'une résine très fluide qui est polymérisée dans un second temps pour obtenir un diélectrique solide. Ce diélectrique solide occupe donc toutes les cavités et porosités du matériau et la pénétration du fluide diélectrique est rendue impossible.According to the invention, to definitively prohibit any possibility of penetration of the dielectric fluid, the proposed method consists of a total impregnation of the porous material using a very fluid resin which is subsequently polymerized to obtain a solid dielectric. This solid dielectric therefore occupies all the cavities and porosities of the material and penetration of the dielectric fluid is made impossible.

Pour garantir la pénétration parfaite de la résine d'imprégnation, il est nécessaire de respecter les règles de l'art habituelles pour ce type d'opération, et, de préférence, on procède de la façon suivante :

  • on choisit une résine très fluide et de faible tension superficielle, par exemple un système époxydique d'imprégnation, mais d'autres types de résines sont applicables. La résine doit être très performante sur le plan diélectrique et compatible avec le fluide diélectrique utilisé (pas de dissolution, pas de dégradation de la résine ou du fluide).
  • on dégraisse soigneusement le composant à imprégner par trempé dans un bain de solvant du type trichloroéthane ou équivalent, de préférence sous ultrasons.
  • on étuve le composant pour en éliminer le solvant et l'humidité, sous vide d'air (10 mbar environ ou mieux, par exemple). Cet étuvage se fait à une température comprise entre 90°C et 120° C environ, pendant 8 h à 4 jours environ.
  • on protège les parties du composant à épargner (par exemple, pour une résistance, les fils de connexion, tels que les fils 11 et 12 précités), à l'aide d'un vernis pelable.
  • on préchauffe la résine d'imprégnation jusqu'à la température à laquelle elle acquiert la viscosité désirée (pour pouvoir pénétrer dans les pores du composant). Cette température est par exemple d'environ 60°C. Ce préchauffage se fait sous vide (10 mbar environ ou mieux) et permet d'éliminer l'air inclus dans la résine. La résine a, de préférence, à chaud, une viscosité inférieure ou égale à 0,5 Pa.s et une rigidité diélectrique à froid d'au moins 5 kV/mm.
  • On plonge le composant à imprégner dans le bain de résine ainsi préchauffée : en en maintenant la température à la valeur atteinte à la fin du préchauffage (60°C pour l'exemple précité), et on dégaze l'ensemble sous vide (10 mbar environ ou mieux) jusqu'à élimination complète de l'air inclus dans les porosités du composant. Cette étape peut par exemple durer 10 à 30 mn environ. En général, elle dure tant que l'on voit des bulles d'air monter à la surface du bain de résine.
  • On complète l'imprégnation par mise sous pression élevée du bain de résine (par exemple à 20 bars environ) dans lequel est plongé le composant. La température du bain peut alors être portée à une température légèrement supérieure à celle qu'il avait pendant le dégazage du composant, par exemple 80 à 90°C pour une température de dégazage d'environ 60°C. Cette étape peut durer par exemple 2 à 4 heures environ. Elle est nécessaire en particulier pour traiter des composants à faible porosité (par exemple porosités de diamètre inférieur à 50 µm).
  • Enfin, on sort le composant du bain, on l'égoutte, on essuie les coulures et on fait polymériser la résine à chaud selon les spécifications du fournisseur (par exemple à 90°C environ pendant 4 heures).
To guarantee perfect penetration of the impregnation resin, it is necessary to comply with the usual rules of the art for this type of operation, and, preferably, the procedure is as follows:
  • a very fluid resin with a low surface tension is chosen, for example an epoxy impregnation system, but other types of resins are applicable. The resin must be very efficient on the dielectric level and compatible with the dielectric fluid used (no dissolution, no degradation of the resin or of the fluid).
  • the component to be impregnated is carefully degreased by soaking in a solvent bath of the trichloroethane or equivalent type, preferably under ultrasound.
  • the component is steamed to remove the solvent and the humidity, under an air vacuum (approximately 10 mbar or better, for example). This steaming takes place at a temperature of between 90 ° C and 120 ° C approximately, for 8 h to 4 days approximately.
  • the parts of the component to be saved are protected (for example, for resistance, the connection wires, such as the above-mentioned wires 11 and 12), using a peelable varnish.
  • the impregnating resin is preheated to the temperature at which it acquires the desired viscosity (in order to be able to penetrate into the pores of the component). This temperature is for example around 60 ° C. This preheating takes place under vacuum (approximately 10 mbar or better) and makes it possible to eliminate the air included in the resin. The resin preferably has a viscosity of 0.5 Pa.s or less when hot and a cold dielectric strength of at least 5 kV / mm.
  • The component to be impregnated is immersed in the resin bath thus preheated: maintaining the temperature at the value reached at end of preheating (60 ° C for the above example), and the assembly is degassed under vacuum (approximately 10 mbar or better) until complete elimination of the air included in the porosities of the component. This step can, for example, last approximately 10 to 30 minutes. In general, it lasts as long as we see air bubbles rising to the surface of the resin bath.
  • The impregnation is completed by placing the resin bath under high pressure (for example at about 20 bars) in which the component is immersed. The temperature of the bath can then be brought to a temperature slightly higher than that which it had during the degassing of the component, for example 80 to 90 ° C. for a degassing temperature of approximately 60 ° C. This stage can last for example 2 to 4 hours approximately. It is necessary in particular for treating components with low porosity (for example porosities with a diameter of less than 50 μm).
  • Finally, the component is removed from the bath, it is drained, the drips are wiped and the resin is polymerized hot according to the supplier's specifications (for example at approximately 90 ° C. for 4 hours).

Bien entendu, on peut imprégner simultanément plusieurs composants dans le même bain, si on peut les y loger. Le composant mentionné ci-dessus est une résistance, mais on peut évidemment traiter d'autres composants comportant un substrat ou une partie poreuse, comme par exemple des condensateurs, des bobinages. Le support peut être en céramique ou en ferrite par exemple.Of course, several components can be simultaneously impregnated in the same bath, if they can be housed there. The component mentioned above is a resistor, but it is obviously possible to treat other components comprising a substrate or a porous part, such as for example capacitors, coils. The support can be ceramic or ferrite for example.

Le procédé décrit ci-dessus a été testé avec une résine époxydique "Scotchcast 280" de la Société 3M sur des résistances en céramique chargée en carbone. Bien entendu, de nombreuses autres résines peuvent convenir. Les conditions qu'elles doivent remplir est d'être non attaquables par les solvants classiques et par l'huile du bain dans lequel sont plongés les composants en utilisation normale, d'avoir une viscosité, à chaud, inférieure ou égale à 0,5 Pa.s et une rigidité diélectrique, à la température d'utilisation, d'au moins 5 kV/mm.The process described above was tested with an epoxy resin "Scotchcast 280" from the company 3M on ceramic resistors loaded with carbon. Of course, many other resins may be suitable. The conditions which they must fulfill is to be non-attackable by conventional solvents and by the oil of the bath in which the components are immersed in normal use, to have a viscosity, hot, less than or equal to 0.5 Pa.s and a dielectric strength, at operating temperature, of at least 5 kV / mm.

La tenue en tension de ces résistances, plongées dans un bain d'huile minérale ou organique est excellente et se maintient après un nombre d'utilisation (décharges capacitives) supérieur à 1000, à la tension maximale applicable, alors que ces mêmes résistances non imprégnées et utilisées dans les mêmes conditions sont détruites très rapidement (environ 10 décharges).The resistance in tension of these resistors, immersed in a bath of mineral or organic oil is excellent and is maintained after a number of uses (capacitive discharges) greater than 1000, at the maximum applicable voltage, while these same resistances not impregnated and used under the same conditions are destroyed very quickly (around 10 landfills).

Par conséquent, pour des composants tels que des résistances à substrat poreux, le procédé de l'invention permet, par rapport aux procédés connus, à tension égale, d'augmenter de façon importante leur durée de vie, ou bien, pour une même durée de vie, d'augmenter la tension appliquée à ces composants, et/ou d'utiliser un bain d'huile ordinaire au lieu d'une huile de haute qualité, très onéreuse.Consequently, for components such as resistors with a porous substrate, the method of the invention makes it possible, compared to known methods, at equal voltage, to significantly increase their service life, or else, for the same duration life, increase the voltage applied to these components, and / or use an ordinary oil bath instead of a high quality, very expensive oil.

Claims (6)

1 - Procédé de protection de composants poreux soumis à des différences de potentiel élevées, caractérisé en ce qu'il consiste à réaliser une imprégnation totale de ces composants dans un bain chaud de résine fluide polymérisable, qui est polymérisée après pénétration dans les porosités de ces composants. 1 - Method for protecting porous components subjected to high potential differences, characterized in that it consists in carrying out a total impregnation of these components in a hot bath of polymerizable fluid resin, which is polymerized after penetration into the porosities of these components. 2 - Procédé selon la revendication 1, caractérisé en ce que, avant de réaliser l'imprégnation, on préchauffe sous vide la résine jusqu'à une température à laquelle elle atteint la viscosité nécessaire pour pénétrer dans les porosités du composant. 2 - Process according to claim 1, characterized in that, before carrying out the impregnation, the resin is preheated under vacuum to a temperature at which it reaches the viscosity necessary to penetrate into the porosities of the component. 3 - Procédé selon la revendication 2, caractérisé en ce que la viscosité à chaud de la résine est inférieure ou égale à environ 0,5 Pa.s. 3 - Process according to claim 2, characterized in that the hot viscosity of the resin is less than or equal to about 0.5 Pa.s. 4 - Procédé selon l'une des revendications précédentes, caractérisé en ce que les composants plongés dans le bain chaud de résine y sont maintenus sous vide tant qu'ils ne sont pas entièrement dégazés. 4 - Method according to one of the preceding claims, characterized in that the components immersed in the hot resin bath are kept there under vacuum as long as they are not fully degassed. 5 - Procédé selon la revendication 4, caractérisé en ce qu'après imprégnation dans le bain chaud de résine, on met ce bain sous pression pour compléter l'imprégnation. 5 - Process according to claim 4, characterized in that after impregnation in the hot resin bath, this bath is pressurized to complete the impregnation. 6 - Composants comportant une partie poreuse et destinés à être soumis à des différences de potentiel élevées, caractérisé en ce que leurs porosités sont remplies de résine polymérisée. 6 - Components comprising a porous part and intended to be subjected to high potential differences, characterized in that their porosities are filled with polymerized resin.
EP19950401954 1994-08-30 1995-08-25 Process for protection of porous components submitted to high potential differences and components manufactured by this process Expired - Lifetime EP0700058B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9410410 1994-08-30
FR9410410A FR2724044B1 (en) 1994-08-30 1994-08-30 PROCESS FOR THE PROTECTION OF POROUS COMPONENTS SUBJECT TO HIGH POTENTIAL DIFFERENCES AND COMPONENTS THUS PRODUCED

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EP0700058A1 true EP0700058A1 (en) 1996-03-06
EP0700058B1 EP0700058B1 (en) 2000-02-09

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DE (1) DE69514969T2 (en)
FR (1) FR2724044B1 (en)
WO (1) WO2004075215A1 (en)

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FR2767675B1 (en) 1997-08-26 1999-12-03 Materiel Orthopedique En Abreg INTERSOMATIC IMPLANT AND ANCILLARY OF PREPARATION SUITABLE FOR ALLOWING ITS POSITION

Citations (5)

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JPS5663888A (en) * 1979-10-26 1981-05-30 Hokkaido Nozai Kogyo Co Manufacture of polymerrimpregnated burnt body
JPS60120780A (en) * 1983-12-02 1985-06-28 Mitsubishi Rayon Co Ltd Method for impregnating porous article and sealing pore
JPS61188481A (en) * 1985-02-14 1986-08-22 Dia Furotsuku Kk Resin impregnating agent composition having excellent heat resistance
JPS63182391A (en) * 1987-01-23 1988-07-27 Daiichi Kasei Kogyo Kk Impregnating agent for porous rigid material
JPS63252981A (en) * 1987-04-08 1988-10-20 住友ベークライト株式会社 Ceramic-macromolecule composite formed article and manufacture

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5663888A (en) * 1979-10-26 1981-05-30 Hokkaido Nozai Kogyo Co Manufacture of polymerrimpregnated burnt body
JPS60120780A (en) * 1983-12-02 1985-06-28 Mitsubishi Rayon Co Ltd Method for impregnating porous article and sealing pore
JPS61188481A (en) * 1985-02-14 1986-08-22 Dia Furotsuku Kk Resin impregnating agent composition having excellent heat resistance
JPS63182391A (en) * 1987-01-23 1988-07-27 Daiichi Kasei Kogyo Kk Impregnating agent for porous rigid material
JPS63252981A (en) * 1987-04-08 1988-10-20 住友ベークライト株式会社 Ceramic-macromolecule composite formed article and manufacture

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Title
DATABASE WPI Section Ch Week 2981, Derwent World Patents Index; Class A82, AN 81-52469 *
DATABASE WPI Section Ch Week 4888, Derwent World Patents Index; Class A81, AN 88-341462 *
PATENT ABSTRACTS OF JAPAN vol. 009, no. 271 (C - 311) 29 October 1985 (1985-10-29) *
PATENT ABSTRACTS OF JAPAN vol. 011, no. 013 (C - 397) 14 January 1987 (1987-01-14) *
PATENT ABSTRACTS OF JAPAN vol. 012, no. 462 (C - 549) 5 December 1988 (1988-12-05) *

Also Published As

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WO2004075215A1 (en) 2004-09-02
EP0700058B1 (en) 2000-02-09
DE69514969D1 (en) 2000-03-16
FR2724044A1 (en) 1996-03-01
DE69514969T2 (en) 2000-08-17
FR2724044B1 (en) 1997-01-03

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