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EP1348505A1 - Thermal shock resistant moulded pouring part and process for its manufacture - Google Patents

Thermal shock resistant moulded pouring part and process for its manufacture Download PDF

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Publication number
EP1348505A1
EP1348505A1 EP02447051A EP02447051A EP1348505A1 EP 1348505 A1 EP1348505 A1 EP 1348505A1 EP 02447051 A EP02447051 A EP 02447051A EP 02447051 A EP02447051 A EP 02447051A EP 1348505 A1 EP1348505 A1 EP 1348505A1
Authority
EP
European Patent Office
Prior art keywords
casting
coating
piece according
casting piece
liquid metal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP02447051A
Other languages
German (de)
French (fr)
Inventor
Eric Hanse
Fran-Ois Delvoye
Philippe Laval
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vesuvius Crucible Co
Original Assignee
Vesuvius Crucible Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vesuvius Crucible Co filed Critical Vesuvius Crucible Co
Priority to EP02447051A priority Critical patent/EP1348505A1/en
Priority to TW092106494A priority patent/TWI271239B/en
Priority to SI200330052T priority patent/SI1492639T1/en
Priority to ES03711721T priority patent/ES2242160T3/en
Priority to DK03711721T priority patent/DK1492639T3/en
Priority to AT03711721T priority patent/ATE298643T1/en
Priority to PT03711721T priority patent/PT1492639E/en
Priority to EP03711721A priority patent/EP1492639B1/en
Priority to DE60300946T priority patent/DE60300946T2/en
Priority to AU2003218536A priority patent/AU2003218536A1/en
Priority to US10/509,501 priority patent/US7237596B2/en
Priority to PCT/BE2003/000056 priority patent/WO2003082500A1/en
Priority to BR0308821-9A priority patent/BR0308821A/en
Publication of EP1348505A1 publication Critical patent/EP1348505A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/50—Pouring-nozzles
    • B22D41/52—Manufacturing or repairing thereof
    • B22D41/54—Manufacturing or repairing thereof characterised by the materials used therefor

Definitions

  • the present invention relates to a refractory piece used for the transfer of a molten metal.
  • a special case in which the invention turns out to be very advantageous is a refractory tube for the transfer of steel from a pocket towards a distributor and especially such a tube which is used without preheating.
  • the refractory parts used during the casting of a molten metal are sensitive by their nature to thermal shock.
  • the parts undergo during their use, in contact with metal, of significant thermal shocks which generate formation of cracks, especially since their temperature is low before use. Consequently, the service life of the parts is reduced.
  • the cracks can allow air to enter, resulting in deterioration of the quality of the cast metal.
  • the document DE 38 05 334 A1 describes another method allowing to improve the resistance to thermal shocks of such parts.
  • This method consists of insert a sleeve of ceramic material into the casting opening of the part fibrous or foamy.
  • This method has several drawbacks.
  • foaming agents or surfactants which are generally not compatible with refractory parts, in particular if they consist of a carbon-bound material.
  • foaming agents or surfactants which are generally not compatible with refractory parts, in particular if they consist of a carbon-bound material.
  • the manufacture and positioning of the sleeve is particularly difficult; in particular, to ensure continuous contact between the sleeve and part.
  • the sleeve is not an integral part of the part, it can move or even come off when handling the part or putting it in place service in contact with metal.
  • Sleeve pieces can block the part, form a plug or at least make it difficult for the molten metal to pass, the metal not being able to flow normally in the lower metallurgical container, it can then exit through the joints connecting the refractory pieces together.
  • refractory jet protection tubes intended for transfer of molten metal from a ladle to a distributor
  • the most used method is certainly that of pre-oxidizing the inner surface of the tube to form a layer without or low carbon percentage.
  • This oxidized layer with a low content of carbon is a layer with a low coefficient of thermal conductivity relative to the body of the tube. It serves as a barrier when starting the casting of metal and allows the refractory tube to withstand the thermal shock of the first contact with molten metal.
  • This method although generally satisfactory, presents however, some drawbacks.
  • the oxidized layer is obtained during cooking in oxidizing atmosphere of the refractory tube. It is therefore quite difficult to obtain a homogeneous layer of uniform thickness over the entire length of the part.
  • the oxidized layer thicknesses can therefore vary significantly (2 to 10 mm) from one tube to another or from one zone to another of the same tube. This does not allow to have homogeneous insulating properties.
  • this layer which has lost its binder carbon is washed in a few minutes on contact with molten metal. The thickness of the tube is therefore quickly reduced by the thickness of the layer, this decreases appreciably the mechanical resistance and its lifespan.
  • the subject of the present invention is a casting, the resistance of which to thermal shock is increased and does not have the disadvantages of the techniques reported above.
  • the casting according to the invention comprises a base body of material refractory.
  • This basic body itself comprises an external surface and a surface internal defining a channel through which a liquid metal can flow.
  • the present invention is based on the observation that the properties of resistance to thermal shock are especially useful at the start of using the room not preheated. It is indeed necessary that such a part can be shocked considerable thermal (change from room temperature to room temperature molten metal) in an extremely short period (a few seconds). Afterwards, the part being used at its operating temperature, it is no longer exposed to as large temperature variations and its resistance to thermal shock becomes less crucial. It will be noted that a temporary stopping of the casting (for example during the ladle change operation) leaving no time for the part to cooling above a critical threshold will no longer give rise to major shocks thermal. On the other hand, once the temperature regime is reached, it would be desirable to take into account other quality factors of the casting such as non-permeability to gas. In particular, it would be highly desirable to ensure good resistance to thermal shock of the part at the start of its cold use and good gas impermeability for further use.
  • the casting according to the invention is characterized in that at least one part of its internal surface is coated with an insulating coating forming, in contact with the liquid metal, a gas-impermeable layer.
  • the insulating coating covering the part cold allows the part to overcome thermal shock at the start of its use, that is to say when the liquid metal comes into contact with the internal part of the part.
  • the impermeable layer formed in contact with liquid metal gives the part gas impermeability properties, air intakes will be reduced see eliminated and the quality of the cast metal improved. In general such a layer waterproof is formed after a few seconds to a few minutes.
  • the coating comprises components which give it its insulating properties as well only components that will promote the formation of a layer impermeable to contact with liquid metal. Note that the same component can play these two roles.
  • the components of the coating giving it its insulating properties are by example of insulating microspheres.
  • the coating components likely to forming a layer impermeable to casting temperatures are for example silica and alumina.
  • the coating comprises 20 to 80% in weight of a ceramic matrix, 5 to 40% by weight of insulating microspheres, from 0.5 to 15% by weight of one or more binders, and up to 5% water.
  • the coating can also comprise 5 to 20% by weight of a metal or a metal alloy in order to improve the continuity of the coating of the part and therefore the texture of the coating.
  • the ceramic matrix comprises silica or alumina, in particular vitreous grains such as atomized silica.
  • the atomized silica being very fine, it has the advantage of easily penetrating into the porosity of the body of the part and thus secure the coating and the material of the body.
  • Microspheres insulators also include, for example, silica and / or alumina.
  • Components of the coating forming a gas-impermeable layer can react with certain elements contained in the liquid metal as well as with certain elements contained in the material of the body of the casting.
  • the result of these reactions are low melting, melted or glassy phases to operating temperatures, which cover and waterproof the surface of the part. It has been noted that advantageously these phases have a relatively viscosity high allowing good attachment to the internal workpiece surface. In particular, these phases are not damaged when cleaning the room, for example oxygen. We have noticed that these reactions take place even when these elements are present in very small proportions.
  • the elements of the metal that can participate in these reactions are for example calcium, magnesium or manganese.
  • the elements of the material of the body of the part are for example magnesia and mulite.
  • the casting is a jet protection tube by example in refractory material bonded carbon not preheated before use.
  • the thickness of the coating can vary from 1 to 10 mm, good results have been obtained with a thickness of 3 to 5 mm.
  • the insulating coating is applied to part of the internal surface of the workpiece. casting.
  • the coating has a structure and a particle size such as the coating and the material constituting the body of the part casting bond together, the plaster penetrating the porosity of the body material for example by wetting or capillarity. There is therefore interpenetration of the material of the body and coating which join together.
  • the coating of the part will transform during use into a layer waterproof which will remain attached to the material of the body of the casting.
  • a layer of insulating plaster similar or different from that described in the The present invention can also be applied to part of the external surface of the casting part, in particular in a part of the part capable of being submerged in liquid metal.
  • This part indeed must overcome the internal thermal shock during the first passage of the liquid metal as well as the thermal shock during its quenching in liquid metal.
  • the present invention also relates to a method of coating a casting part characterized in that it is applied to at least part of the surface internal part of the part an insulating coating forming, in contact with the liquid metal, a layer impermeable to gases, said casting comprising a base body of material refractory, this basic body itself comprising an external surface and a surface internal defining a channel.
  • the coating can be applied to the surface of the tube by spraying, using with a brush or by soaking in an aqueous solution or in a slip. It is also possible to simply pour an aqueous solution or a slip through the channel defined by the internal surface of the part.
  • slip means an aqueous suspension or in another fine particle liquid (with a dimension less than 50 ⁇ m) or again such a suspension in which we would also have more particles coarse (with grains up to about 2 mm in size).
  • a coating that has given good results is a coating comprising silica atomized in proportions from 20 to 80% by weight relative to the total weight of the coating. Atomized silica is actually easily put in the form of a slip and easily penetrates into the porosity of the body of the casting.
  • a coating comprising 20 to 80% by weight of a ceramic matrix, 5 to 40% by weight of insulating microspheres, from 0.5 15% by weight of one or more binders, and up to 5% water is prepared under the shaped like a slip, said slip is brought into contact with the surface of the part to be coated and is then dried for at least two hours.
  • the coating can also comprise 5 to 20% by weight of a metal or an alloy metallic to improve the coating process of the part and reduce the formation cracks during drying.
  • the coating of the present invention is capable of withstanding this preheating.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Glass Compositions (AREA)
  • Cylinder Crankcases Of Internal Combustion Engines (AREA)
  • Ceramic Products (AREA)
  • Insulating Bodies (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)

Abstract

A component for the casting of liquid metal comprises a base body of refractory material including external and internal surfaces defining a channel for casting the liquid metal. At least part of the internal surface of the component is coated with an insulating coating forming a layer impermeable to gas, on contact with the liquid metal An Independent claim is also included for a method for the coating of such a casting component.

Description

La présente invention se rapporte à une pièce réfractaire utilisée pour le transfert d'un métal en fusion. Un cas particulier dans lequel l'invention se révèle très avantageuse est un tube réfractaire pour le transfert de l'acier au départ d'une poche vers un répartiteur et spécialement un tel tube qui est utilisé sans préchauffage.The present invention relates to a refractory piece used for the transfer of a molten metal. A special case in which the invention turns out to be very advantageous is a refractory tube for the transfer of steel from a pocket towards a distributor and especially such a tube which is used without preheating.

Les pièces réfractaires utilisées lors de la coulée d'un métal en fusion sont sensibles, de par leur nature, aux chocs thermiques. Les pièces subissent lors de leur utilisation, au contact du métal, des chocs thermiques importants qui engendrent la formation de fissures et ce d'autant plus que leur température est basse avant utilisation. Par conséquent, la durée de vie des pièces est réduite. De plus, les fissures peuvent permettre les entrées d'air, ce qui entraíne une détérioration de la qualité du métal coulé.The refractory parts used during the casting of a molten metal are sensitive by their nature to thermal shock. The parts undergo during their use, in contact with metal, of significant thermal shocks which generate formation of cracks, especially since their temperature is low before use. Consequently, the service life of the parts is reduced. Moreover, the cracks can allow air to enter, resulting in deterioration of the quality of the cast metal.

Afin d'améliorer la tenue aux chocs thermiques des pièces, une technique largement répandue consiste à préchauffer les pièces à des températures avoisinant le plus possible la température d'utilisation. Cependant, cette technique nécessite de disposer d'une zone de préchauffage à proximité de la zone d'utilisation des pièces, et consomme de l'énergie, elle est par conséquent coûteuse. De plus, il existe un temps minimum de préchauffage avant lequel la pièce n'est pas suffisamment préchauffée pour surmonter le choc thermique et un temps de préchauffage maximum après lequel la pièce commence à se détériorer. Cette méthode manque également de flexibilité puisqu'elle ne permet pas de faire face aux imprévus ni aux écarts trop important par rapport aux prévisions de fabrication.In order to improve the resistance to thermal shocks of parts, a technique widespread is to preheat the parts to temperatures around the operating temperature as much as possible. However, this technique requires have a preheating zone near the parts use zone, and consumes energy and is therefore expensive. In addition, there is a time minimum preheating before which the room is not sufficiently preheated to overcome thermal shock and a maximum warm-up time after which the part begins to deteriorate. This method also lacks flexibility since it does not make it possible to cope with unforeseen events or excessively large differences by compared to manufacturing forecasts.

Une autre technique bien connue de l'homme du métier et combinée avec celle décrite ci-dessus est l'utilisation de fibres isolantes qui sont soit collées soit cimentées sur l'extérieur de la pièce réfractaire. Dans ce cas, le revêtement extérieur permet de garder plus longtemps la chaleur acquise lors du préchauffage et d'augmenter son efficacité. Cependant, les fibres qui supportent les températures élevées (> 1000°C) nécessaires dans ces applications sont toxiques et leur utilisation est de moins en moins permise.Another technique well known to those skilled in the art and combined with that described above is the use of insulating fibers which are either glued or cemented on the outside of the refractory piece. In this case, the outer coating allows keep the heat acquired during preheating longer and increase its efficiency. However, fibers that withstand high temperatures (> 1000 ° C) necessary in these applications are toxic and their use is less and less less allowed.

Le document DE 38 05 334 A1 décrit une autre méthode permettant d'améliorer la tenue aux chocs thermiques de telles pièces. Cette méthode consiste à introduire dans l'orifice de coulée de la pièce un manchon en matériau céramique fibreux ou mousseux. Cette méthode présente plusieurs inconvénients. Dans le cas de l'utilisation de matériau céramique mousseux, il est nécessaire pour les former d'employer des agents moussants ou tensioactifs qui ne sont généralement pas compatibles avec les pièces réfractaires en particulier si elles sont constituées d'un matériau lié au carbone. Il est aussi difficile de contrôler la mousse afin de former une couche d'épaisseur plus ou moins constante et présentant des propriétés isolantes reproductibles. L'isolation obtenue n'est donc pas homogène et peut créer des gradients de température néfastes au sein de la pièce. Lorsque les pièces présentent des géométries complexes, ce qui est de plus en plus courrant en vue de l'amélioration de la qualité du métal coulé, la fabrication et le positionnement du manchon est particulièrement difficile; en particulier, pour assurer un contact continu entre le manchon et la pièce. Le manchon ne faisant pas partie intégrante de la pièce, il peut se déplacer voire se détacher lors de la manipulation de la pièce ou de sa mise en service au contact du métal. Des morceaux de manchon peuvent obstruer la pièce, former un bouchon ou du moins rendre difficile le passage du métal en fusion, le métal ne pouvant s'écouler normalement dans le récipient métallurgique inférieur, il peut alors sortir par les joints reliant les pièces réfractaires entre elles.The document DE 38 05 334 A1 describes another method allowing to improve the resistance to thermal shocks of such parts. This method consists of insert a sleeve of ceramic material into the casting opening of the part fibrous or foamy. This method has several drawbacks. In the case of the use of sparkling ceramic material, it is necessary to form them to use foaming agents or surfactants which are generally not compatible with refractory parts, in particular if they consist of a carbon-bound material. It is also difficult to control the foam in order to form a layer of more or less constant thickness and having insulating properties reproducible. The insulation obtained is therefore not homogeneous and can create Harmful temperature gradients within the room. When the pieces show complex geometries, which is more and more common for improvement of the quality of the cast metal, the manufacture and positioning of the sleeve is particularly difficult; in particular, to ensure continuous contact between the sleeve and part. As the sleeve is not an integral part of the part, it can move or even come off when handling the part or putting it in place service in contact with metal. Sleeve pieces can block the part, form a plug or at least make it difficult for the molten metal to pass, the metal not being able to flow normally in the lower metallurgical container, it can then exit through the joints connecting the refractory pieces together.

Dans le cas particulier des tubes réfractaires de protection de jet, destinés au transfert d'un métal en fusion depuis une poche de coulée vers un répartiteur, ceux-ci étant en général des tubes en matériau à base de graphite et liés carbone (alumine/graphite, magnésie/graphite, ...), la méthode la plus utilisée est certainement celle consistant à pré-oxyder la surface intérieure du tube afin de former une couche sans ou à faible pourcentage en carbone. Cette couche oxydée à faible teneur en carbone, est une couche qui présente un faible coefficient de conductivité thermique par rapport au corps du tube. Elle sert de barrière lors du démarrage de la coulée du métal et permet au tube réfractaire de supporter le choc thermique du premier contact avec le métal fondu. Cette méthode, bien que généralement satisfaisante, présente toutefois quelques inconvénients. La couche oxydée est obtenue lors de la cuisson en atmosphère oxydante du tube réfractaire. Il est donc assez difficile d'obtenir une couche homogène d'épaisseur uniforme sur toute la longueur de la pièce. Les épaisseurs de couche oxydée peuvent donc varier de façon significative (2 à 10 mm) d'un tube à l'autre ou d'une zone à l'autre d'un même tube. Ceci ne permet pas d'avoir des propriétés isolantes homogènes. De plus, cette couche qui a perdu son liant carbone, est lavée en quelques minutes au contact du métal fondu. L'épaisseur du tube est donc rapidement réduite de l'épaisseur de la couche, ceci diminue sensiblement la résistance mécanique et sa durée de vie.In the specific case of refractory jet protection tubes, intended for transfer of molten metal from a ladle to a distributor, these generally being tubes of graphite-based material and carbon bonded (alumina / graphite, magnesia / graphite, ...), the most used method is certainly that of pre-oxidizing the inner surface of the tube to form a layer without or low carbon percentage. This oxidized layer with a low content of carbon, is a layer with a low coefficient of thermal conductivity relative to the body of the tube. It serves as a barrier when starting the casting of metal and allows the refractory tube to withstand the thermal shock of the first contact with molten metal. This method, although generally satisfactory, presents however, some drawbacks. The oxidized layer is obtained during cooking in oxidizing atmosphere of the refractory tube. It is therefore quite difficult to obtain a homogeneous layer of uniform thickness over the entire length of the part. The oxidized layer thicknesses can therefore vary significantly (2 to 10 mm) from one tube to another or from one zone to another of the same tube. This does not allow to have homogeneous insulating properties. In addition, this layer which has lost its binder carbon, is washed in a few minutes on contact with molten metal. The thickness of the tube is therefore quickly reduced by the thickness of the layer, this decreases appreciably the mechanical resistance and its lifespan.

La présente invention a pour objet une pièce de coulée dont la résistance au choc thermique est accrue et ne présentant pas les inconvénients des techniques relatées ci-dessus. En outre, il serait souhaitable de proposer une pièce réfractaire possédant des propriétés améliorées, en particulier une perméabilité au gaz sensiblement réduite par rapport aux pièces de l'état de la technique.The subject of the present invention is a casting, the resistance of which to thermal shock is increased and does not have the disadvantages of the techniques reported above. In addition, it would be desirable to propose a refractory piece having improved properties, in particular gas permeability significantly reduced compared to parts of the state of the art.

La pièce de coulée selon l'invention comprend un corps de base en matériau réfractaire. Ce corps de base comprend lui-même une surface externe et une surface interne définissant un chenal au travers duquel un métal liquide peut s'écouler. The casting according to the invention comprises a base body of material refractory. This basic body itself comprises an external surface and a surface internal defining a channel through which a liquid metal can flow.

La présente invention est basée sur l'observation que les propriétés de résistance au choc thermique sont surtout très utiles au début de l'utilisation de la pièce non préchauffée. Il est en effet nécessaire qu'une telle pièce puisse subir un choc thermique considérable (passage de la température ambiante à la température du métal fondu) en une période extrêmement courte (quelques secondes). Par après, la pièce étant utilisée à sa température de régime, elle n'est plus exposée à d'aussi importantes variations de température et sa résistance au choc thermique devient moins cruciale. On notera qu'un arrêt temporaire de la coulée (par exemple lors de l'opération de changement de poche de coulée) ne laissant pas le temps à la pièce de se refroidir au delà d'un seuil critique ne donnera plus lieu à d'importants chocs thermiques. D'autre part, une fois le régime de température atteint, il serait souhaitable de tenir compte d'autres facteurs de qualité de la pièce de coulée tels que la non perméabilité au gaz. En particulier, il serait hautement souhaitable d'assurer une bonne résistance au choc thermique de la pièce au début de son utilisation à froid et une bonne imperméabilité aux gaz pour la suite de son utilisation.The present invention is based on the observation that the properties of resistance to thermal shock are especially useful at the start of using the room not preheated. It is indeed necessary that such a part can be shocked considerable thermal (change from room temperature to room temperature molten metal) in an extremely short period (a few seconds). Afterwards, the part being used at its operating temperature, it is no longer exposed to as large temperature variations and its resistance to thermal shock becomes less crucial. It will be noted that a temporary stopping of the casting (for example during the ladle change operation) leaving no time for the part to cooling above a critical threshold will no longer give rise to major shocks thermal. On the other hand, once the temperature regime is reached, it would be desirable to take into account other quality factors of the casting such as non-permeability to gas. In particular, it would be highly desirable to ensure good resistance to thermal shock of the part at the start of its cold use and good gas impermeability for further use.

La pièce de coulée selon l'invention est caractérisée en ce que au moins une partie de sa surface interne est revêtue d'un enduit isolant formant, au contact du métal liquide, une couche imperméable aux gaz. L'enduit isolant recouvrant la pièce froide permet à la pièce de surmonter le choc thermique au début de son utilisation, c'est à dire lorsque le métal liquide vient au contact de la partie interne de la pièce. La couche imperméable formée au contact du métal liquide confère à la pièce des propriétés d'imperméabilité aux gaz, les entrées d'air seront donc réduites voir éliminées et la qualité du métal coulé améliorée. En général une telle couche imperméable est formée après de quelques secondes à quelques minutes.The casting according to the invention is characterized in that at least one part of its internal surface is coated with an insulating coating forming, in contact with the liquid metal, a gas-impermeable layer. The insulating coating covering the part cold allows the part to overcome thermal shock at the start of its use, that is to say when the liquid metal comes into contact with the internal part of the part. The impermeable layer formed in contact with liquid metal gives the part gas impermeability properties, air intakes will be reduced see eliminated and the quality of the cast metal improved. In general such a layer waterproof is formed after a few seconds to a few minutes.

L'enduit comprend des composants lui conférant ses propriétés isolantes ainsi que des composants qui vont promouvoir la formation d'une couche imperméable au contact avec le métal liquide. Il faut noter qu'un même composant peut jouer ces deux rôles. Les composants de l'enduits lui conférant ses propriétés isolantes sont par exemple des microsphères isolantes. Les composants de l'enduit susceptibles de former une couche imperméable aux températures de coulée sont par exemple la silice et l'alumine.The coating comprises components which give it its insulating properties as well only components that will promote the formation of a layer impermeable to contact with liquid metal. Note that the same component can play these two roles. The components of the coating giving it its insulating properties are by example of insulating microspheres. The coating components likely to forming a layer impermeable to casting temperatures are for example silica and alumina.

Selon un mode de réalisation de l'invention, l'enduit comprend 20 à 80 % en poids d'une matrice céramique, 5 à 40 % en poids de microsphères isolantes, de 0,5 à 15 % en poids d'un ou plusieurs liants, etjusqu' à 5 % d'eau. L'enduit peut aussi comprendre 5 à 20 % en poids d'un métal ou d'un alliage métallique afin d'améliorer la continuité du revêtement de la pièce et par conséquent la texture de l'enduit. Dans un cas particulier la matrice céramique comprend de la silice ou de l'alumine, notamment des grains vitreux tels que de la silice atomisée. La silice atomisée étant très fine, elle présente l'avantage de pénétrer facilement dans la porosité du corps de la pièce et de solidariser ainsi l'enduit et le matériau du corps. Les microsphères isolantes comprennent également par exemple de la silice et/ou de l'alumine.According to one embodiment of the invention, the coating comprises 20 to 80% in weight of a ceramic matrix, 5 to 40% by weight of insulating microspheres, from 0.5 to 15% by weight of one or more binders, and up to 5% water. The coating can also comprise 5 to 20% by weight of a metal or a metal alloy in order to improve the continuity of the coating of the part and therefore the texture of the coating. In a particular case, the ceramic matrix comprises silica or alumina, in particular vitreous grains such as atomized silica. The atomized silica being very fine, it has the advantage of easily penetrating into the porosity of the body of the part and thus secure the coating and the material of the body. Microspheres insulators also include, for example, silica and / or alumina.

Des composants de l'enduit formant une couche imperméable aux gaz peuvent réagir avec certains éléments contenus dans le métal liquide ainsi qu'avec certains éléments contenus dans le matériau du corps de la pièce de coulée. Le résultat de ces réactions sont des phases à bas point de fusion, fondues ou vitreuses aux températures d'utilisations, qui recouvrent et imperméabilisent la surface de la pièce. On a remarqué qu'avantageusement ces phases présentent une viscosité relativement élevée permettant un bon accrochage à la surface interne de pièce. En particulier, ces phases ne sont pas endommagées lors d'un nettoyage de la pièce, par exemple à l'oxygène. On a remarqué que ces réactions ont lieu même lorsque ces éléments sont présents en très faibles proportions. Les éléments du métal pouvant participer à ces réactions sont par exemple le calcium, le magnésium ou le manganèse. Les éléments du matériau du corps de la pièce sont par exemple la magnésie et la mulite.Components of the coating forming a gas-impermeable layer can react with certain elements contained in the liquid metal as well as with certain elements contained in the material of the body of the casting. The result of these reactions are low melting, melted or glassy phases to operating temperatures, which cover and waterproof the surface of the part. It has been noted that advantageously these phases have a relatively viscosity high allowing good attachment to the internal workpiece surface. In particular, these phases are not damaged when cleaning the room, for example oxygen. We have noticed that these reactions take place even when these elements are present in very small proportions. The elements of the metal that can participate in these reactions are for example calcium, magnesium or manganese. The elements of the material of the body of the part are for example magnesia and mulite.

Dans un cas particulier, la pièce de coulée est un tube de protection de jet par exemple en matériau réfractaire lié carbone non préchauffé avant utilisation.In a particular case, the casting is a jet protection tube by example in refractory material bonded carbon not preheated before use.

L'épaisseur de l'enduit peut varier de 1 à 10 mm, de bons résultats ont été obtenus avec une épaisseur de 3 à 5 mm.The thickness of the coating can vary from 1 to 10 mm, good results have been obtained with a thickness of 3 to 5 mm.

L'enduit isolant est appliqué sur une partie de la surface interne de la pièce de coulée. Selon un mode de réalisation de l'invention, l'enduit présente une structure et une granulométrie telles que l'enduit et le matériau constituant le corps de la pièce de coulée se lient l'un à l'autre, l'enduit pénétrant dans la porosité du matériau du corps par exemple par mouillage ou capillarité. Il y a donc interpénétration du matériau du corps et de l'enduit qui se solidarisent.The insulating coating is applied to part of the internal surface of the workpiece. casting. According to one embodiment of the invention, the coating has a structure and a particle size such as the coating and the material constituting the body of the part casting bond together, the plaster penetrating the porosity of the body material for example by wetting or capillarity. There is therefore interpenetration of the material of the body and coating which join together.

L'enduit de la pièce se transformera pendant son utilisation en une couche imperméable qui restera solidaire au matériau du corps de la pièce de coulée.The coating of the part will transform during use into a layer waterproof which will remain attached to the material of the body of the casting.

Plusieurs couches successives d'enduit en vue d'améliorer la résistance au choc thermique peuvent s'avérer nécessaires, par exemple dans le cas d'applications difficiles.Several successive layers of plaster to improve impact resistance may be necessary, for example in the case of applications difficult.

Une couche d'enduit isolant similaire ou différent de celui décrit dans la présente invention peut également être appliqué sur une partie de la surface externe de la pièce de coulée, notamment dans une partie de la pièce susceptible d'être immergée dans le métal liquide. Cette partie en effet doit surmonter le choc thermique interne lors du premier passage du métal liquide ainsi que le choc thermique lors de sa trempe dans le métal liquide.A layer of insulating plaster similar or different from that described in the The present invention can also be applied to part of the external surface of the casting part, in particular in a part of the part capable of being submerged in liquid metal. This part indeed must overcome the internal thermal shock during the first passage of the liquid metal as well as the thermal shock during its quenching in liquid metal.

La présente invention concerne également un procédé de revêtement d'une pièce de coulée caractérisé en ce qu'on applique sur au moins une partie de la surface interne de la pièce un enduit isolant formant, au contact du métal liquide, une couche imperméable aux gaz, ladite pièce de coulée comprenant un corps de base en matériau réfractaire, ce corps de base comprenant lui-même une surface externe et une surface interne définissant un chenal.The present invention also relates to a method of coating a casting part characterized in that it is applied to at least part of the surface internal part of the part an insulating coating forming, in contact with the liquid metal, a layer impermeable to gases, said casting comprising a base body of material refractory, this basic body itself comprising an external surface and a surface internal defining a channel.

L'enduit peut être appliqué sur la surface du tube par pulvérisation, à l'aide d'un pinceau ou encore par trempage dans une solution aqueuse ou dans une barbotine. Il est également possible de simplement verser une solution aqueuse ou une barbotine à travers le chenal défini par la surface interne de la pièce. Dans le cadre de la présente divulgation, on entend par barbotine une suspension aqueuse ou dans un autre liquide de particules fines (avec une dimension inférieure à 50 µm) ou encore une telle suspension dans laquelle on aurait également des particules plus grossières (avec des grains d'une dimension jusqu'à environ 2 mm).The coating can be applied to the surface of the tube by spraying, using with a brush or by soaking in an aqueous solution or in a slip. It is also possible to simply pour an aqueous solution or a slip through the channel defined by the internal surface of the part. In the For the purposes of this disclosure, slip means an aqueous suspension or in another fine particle liquid (with a dimension less than 50 µm) or again such a suspension in which we would also have more particles coarse (with grains up to about 2 mm in size).

L'interpénétration de l'enduit et du matériau du corps de la pièce est facilitée lorsque l'enduit est préparé sous la forme d'une solution aqueuse ou d'une barbotine, appliqué à la pièce et séché ensuite par exemple à l'air libre. Un enduit ayant donné de bons résultats est une enduit comprenant de la silice atomisée dans des proportions de 20 à 80 % en poids par rapport au poids total de l'enduit. La silice atomisée est effectivement aisément mise sous la forme d'une barbotine et pénètre facilement dans la porosité du corps de la pièce de coulée.The interpenetration of the plaster and the material of the body of the part is facilitated when the coating is prepared in the form of an aqueous solution or a slip, applied to the part and then dried, for example in the open air. A coating that has given good results is a coating comprising silica atomized in proportions from 20 to 80% by weight relative to the total weight of the coating. Atomized silica is actually easily put in the form of a slip and easily penetrates into the porosity of the body of the casting.

Dans un mode de réalisation de l'invention, un enduit comprenant 20 à 80 % en poids d'une matrice céramique, 5 à 40 % en poids de microsphères isolantes, de 0,5 à 15 % en poids d'un ou plusieurs liants, et jusqu' à 5 % d'eau est préparé sous la forme d'une barbotine, ladite barbotine est mise en contact avec la surface de la pièce à revêtir et est ensuite séchée pendant au moins deux heures.In one embodiment of the invention, a coating comprising 20 to 80% by weight of a ceramic matrix, 5 to 40% by weight of insulating microspheres, from 0.5 15% by weight of one or more binders, and up to 5% water is prepared under the shaped like a slip, said slip is brought into contact with the surface of the part to be coated and is then dried for at least two hours.

L'enduit peut aussi comprendre 5 à 20 % en poids d'un métal ou d'un alliage métallique afin d'améliorer le procédé d'enduction de la pièce et de réduire la formation de fissures lors du séchage.The coating can also comprise 5 to 20% by weight of a metal or an alloy metallic to improve the coating process of the part and reduce the formation cracks during drying.

ExempleExample

On prend un tube de protection de jet constitué d'alumine graphite et liée carbone dont la surface interne du tube n'a pas été oxydée. Un enduit comprenant en poids:

  • 12,1 % d'eau
  • 2,9 % de dextrine
  • 7,8 % de silice colloïdale
  • 1,7 % de dolapix CE 64 (dolapix CE 64 est un défloculant vendu par la firme allemande ZCHIMMER & SCHWARZ AG.)
  • 8,6 % de fillite
  • 4,1 % d'argile
  • 42,9 % de silice atomisée
  • 10,7 % d'alumine
  • 9,1 % d'aluminium (métal)
  • 0,1 % de tripolyphosphate de sodium
    • est préparé sous la forme d'une barbotine. L'extrémité du tube est bouchée à l'aide d'un bouchon en caoutchouc. On rempli l'intérieur du tube avec la barbotine. Après 20 à 30 secondes, on ouvre l'extrémité du tube et on laisse l'excédant de barbotine s'éliminer. La surface interne du tube est ainsi recouverte d'une couche d'enduit d'une épaisseur sensiblement constante. L'enduit et le matériau du tube étant interconnecté l'un à l'autre. La pièce est ensuite séchée à l'air libre pendant environ deux heures. Une pièce fabriquée selon l'exemple a été comparée à une pièce connue comprenant une couche oxydée sur sa surface interne de 5 mm. Après utilisation, la pièce selon l'invention ne présentait aucune fissure et sa durée de vie était de très loin supérieure à celle de la pièce de l'état de la technique.
    La surface interne de la pièce selon l'invention était recouverte d'une couche d'aspect vitreux, imperméable aux gaz. Cette couche fondue comprenait notamment des aluminates de chaux, des silico-aluminates de chaux et du silicate de manganèse.Take a jet protection tube made of graphite alumina and carbon bonded, the internal surface of the tube has not been oxidized. A coating comprising by weight:
  • 12.1% water
  • 2.9% dextrin
  • 7.8% colloidal silica
  • 1.7% of dolapix CE 64 (dolapix CE 64 is a deflocculant sold by the German company ZCHIMMER & SCHWARZ AG.)
  • 8.6% of fillite
  • 4.1% clay
  • 42.9% atomized silica
  • 10.7% alumina
  • 9.1% aluminum (metal)
  • 0.1% sodium tripolyphosphate
    • is prepared in the form of a slip. The end of the tube is plugged with a rubber stopper. The inside of the tube is filled with the slip. After 20 to 30 seconds, the end of the tube is opened and the excess slip is allowed to eliminate. The internal surface of the tube is thus covered with a coating layer of substantially constant thickness. The coating and the tube material being interconnected to each other. The part is then dried in the open air for approximately two hours. A part produced according to the example was compared with a known part comprising an oxidized layer on its internal surface of 5 mm. After use, the part according to the invention had no cracks and its lifetime was far greater than that of the part of the prior art.
    The internal surface of the part according to the invention was covered with a layer of vitreous appearance, impermeable to gases. This molten layer notably comprised lime aluminates, lime silico-aluminates and manganese silicate.

    Dans certaines applications critiques où un préchauffage s'avérerait encore nécessaire, l'enduit de la présente invention est capable de résister à ce préchauffage.In certain critical applications where preheating would still prove to be necessary, the coating of the present invention is capable of withstanding this preheating.

    Claims (11)

    Pièce pour la coulée d'un métal liquide, comprenant un corps de base en matériau réfractaire, ledit corps comprenant une surface externe et une surface interne définissant un chenal pour la coulée du métal liquide, caractérisée en ce qu'au moins une partie de la surface interne de la pièce est revêtue d'un enduit isolant formant, au contact du métal liquide, une couche imperméable aux gaz.Piece for casting a molten metal, comprising a base body of refractory material, said body comprising an outer surface and an inner surface defining a channel for pouring molten metal, characterized in that at least part of the internal surface of the part is coated with an insulating coating forming, in contact with the liquid metal, a gas-impermeable layer. Pièce de coulée selon la revendication 1, caractérisée en ce que l'enduit comprend 20 à 80 % en poids d'une matrice céramique, de préférence comprenant de la silice ou de l'alumine.Casting piece according to claim 1, characterized in that the coating comprises 20 to 80% by weight of a ceramic matrix, preferably comprising silica or alumina. Pièce de coulée selon la revendication 2, caractérisée en ce que la matrice céramique comprend des grains vitreux, notamment de la silice atomisée.Casting piece according to claim 2, characterized in that the ceramic matrix comprises vitreous grains, in particular atomized silica. Pièce de coulée selon l'une quelconque des revendications 1 à 3, caractérisé en ce que l'enduit comprend des microsphères isolantes, de préférence en une quantité comprise entre 5 et 40 % en poids.Casting piece according to any one of claims 1 to 3, characterized in that the coating comprises insulating microspheres, preferably in an amount between 5 and 40% by weight. Pièce de coulée selon l'une quelconque des revendications 1 à 4, caractérisée en ce que l'épaisseur de l'enduit est comprise entre 1 et 10 mm.Casting piece according to any one of claims 1 to 4, characterized in that the thickness of the coating is between 1 and 10 mm. Pièce de coulée selon l'une quelconque des revendications 1 à 5, caractérisée en ce que la couche imperméable et le matériau réfractaire s'interpénètrent.Casting piece according to any one of claims 1 to 5, characterized in that the impermeable layer and the refractory material interpenetrate. Pièce de coulée selon l'une quelconque des revendications 1 à 6, caractérisée en ce que le corps de base est constitué d'un matériau lié au carbone.Casting piece according to any one of claims 1 to 6, characterized in that the base body is made of a material bonded to carbon. Pièce de coulée selon l'une quelconque des revendications 1 à 7, caractérisée en ce que la pièce de coulée est un tube de protection de jet.Casting piece according to any one of Claims 1 to 7, characterized in that the casting piece is a jet protection tube. Pièce de coulée selon l'une quelconque des revendications 1 à 8, caractérisée en ce que au moins une partie de la surface externe est revêtue d'un enduit isolant.Casting piece according to any one of Claims 1 to 8, characterized in that at least part of the external surface is coated with an insulating coating. Procédé de revêtement d'une pièce de coulée comprenant un corps de base en matériau réfractaire, ledit corps comprenant une surface externe et une surface interne définissant un chenal pour la coulée du métal liquide caractérisé en ce qu' on applique sur au moins une partie de la surface interne de la pièce un enduit isolant formant, au contact du métal liquide, une couche imperméable aux gaz.Method for coating a casting comprising a base body of refractory material, said body comprising an external surface and an internal surface defining a channel for the casting of liquid metal characterized in that one applies to at least a part of the internal surface of the part an insulating coating forming, in contact with the liquid metal, a gas-impermeable layer. Procédé selon la revendication 10, caractérisé en ce qu'on prépare l'enduit sous la forme d'une barbotine, on met la pièce en contact avec ladite barbotine et on le laisse sécher au moins deux heures.Method according to claim 10, characterized in that the coating is prepared in the form of a slip, the part is brought into contact with said slip and it is left to dry for at least two hours.
    EP02447051A 2002-03-29 2002-03-29 Thermal shock resistant moulded pouring part and process for its manufacture Withdrawn EP1348505A1 (en)

    Priority Applications (13)

    Application Number Priority Date Filing Date Title
    EP02447051A EP1348505A1 (en) 2002-03-29 2002-03-29 Thermal shock resistant moulded pouring part and process for its manufacture
    TW092106494A TWI271239B (en) 2002-03-29 2003-03-24 Thermal shock resistant casting element and manufacturing process thereof
    SI200330052T SI1492639T1 (en) 2002-03-29 2003-03-28 Thermal shock resistant casting element and manufacturing process thereof
    ES03711721T ES2242160T3 (en) 2002-03-29 2003-03-28 COLADA ELEMENT RESISTANT TO THERMAL SHOCK AND MANUFACTURING PROCEDURE OF THE SAME.
    DK03711721T DK1492639T3 (en) 2002-03-29 2003-03-28 Temperature shock-resistant molding member and method of making them
    AT03711721T ATE298643T1 (en) 2002-03-29 2003-03-28 TEMPERATURE SHOCK RESISTANT CASTING ELEMENT AND ITS PRODUCTION PROCESS
    PT03711721T PT1492639E (en) 2002-03-29 2003-03-28 THERMAL SHOCK RESISTANT ELEMENT AND PROCESS FOR ITS PRODUCTION
    EP03711721A EP1492639B1 (en) 2002-03-29 2003-03-28 Thermal shock resistant casting element and manufacturing process thereof
    DE60300946T DE60300946T2 (en) 2002-03-29 2003-03-28 TEMPERATURE SHOCK-RESISTANT CASTING ELEMENT AND ITS MANUFACTURING METHOD
    AU2003218536A AU2003218536A1 (en) 2002-03-29 2003-03-28 Thermal shock resistant casting element and manufacturing process thereof
    US10/509,501 US7237596B2 (en) 2002-03-29 2003-03-28 Thermal shock resistant casting element and manufacturing process thereof
    PCT/BE2003/000056 WO2003082500A1 (en) 2002-03-29 2003-03-28 Thermal shock resistant casting element and manufacturing process thereof
    BR0308821-9A BR0308821A (en) 2002-03-29 2003-03-28 Casting element of a liquid metal and process for coating a casting element

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    EP02447051A EP1348505A1 (en) 2002-03-29 2002-03-29 Thermal shock resistant moulded pouring part and process for its manufacture

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    ES2595214T3 (en) * 2013-04-26 2016-12-28 Refractory Intellectual Property Gmbh & Co. Kg Wash spoon and bottom of it
    KR102649884B1 (en) 2018-02-09 2024-03-21 베수비우스 유에스에이 코포레이션 Fire resistant composition and in situ antioxidant barrier layer

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    PT1492639E (en) 2005-10-31
    US20050156365A1 (en) 2005-07-21
    DK1492639T3 (en) 2005-10-31
    ES2242160T3 (en) 2005-11-01
    WO2003082500A1 (en) 2003-10-09
    TWI271239B (en) 2007-01-21
    TW200304856A (en) 2003-10-16
    BR0308821A (en) 2005-01-04
    DE60300946T2 (en) 2006-05-11
    ATE298643T1 (en) 2005-07-15
    DE60300946D1 (en) 2005-08-04
    EP1492639A1 (en) 2005-01-05
    EP1492639B1 (en) 2005-06-29
    AU2003218536A1 (en) 2003-10-13

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