EP1871554A1 - Dry-spray products for protecting centrifugal casting molds of cast iron pipes in association with a wet-spray product - Google Patents

Dry-spray products for protecting centrifugal casting molds of cast iron pipes in association with a wet-spray product

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Publication number
EP1871554A1
EP1871554A1 EP06778578A EP06778578A EP1871554A1 EP 1871554 A1 EP1871554 A1 EP 1871554A1 EP 06778578 A EP06778578 A EP 06778578A EP 06778578 A EP06778578 A EP 06778578A EP 1871554 A1 EP1871554 A1 EP 1871554A1
Authority
EP
European Patent Office
Prior art keywords
spray
wet
product
cast iron
dry
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Withdrawn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
EP06778578A
Other languages
German (de)
French (fr)
Inventor
Thomas Margaria
Roland Siclari
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.)
Ferropem SAS
Original Assignee
Pechiney Electrometallurgie SAS
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 Pechiney Electrometallurgie SAS filed Critical Pechiney Electrometallurgie SAS
Publication of EP1871554A1 publication Critical patent/EP1871554A1/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Withdrawn legal-status Critical Current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
    • B22D13/00—Centrifugal casting; Casting by using centrifugal force
    • B22D13/10—Accessories for centrifugal casting apparatus, e.g. moulds, linings therefor, means for feeding molten metal, cleansing moulds, removing castings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D13/00—Centrifugal casting; Casting by using centrifugal force
    • B22D13/10—Accessories for centrifugal casting apparatus, e.g. moulds, linings therefor, means for feeding molten metal, cleansing moulds, removing castings
    • B22D13/101—Moulds
    • B22D13/102—Linings for moulds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns

Definitions

  • the invention relates to a product in powder form, of the "dry-spray” type, intended for the protection of molds used for the centrifugal casting of cast iron pipes, in association with a sub-layer product of the "wet-spray” type.
  • the casting molds used are commonly referred to as "shells”.
  • the coatings used for the protection of centrifugal casting shells of cast iron pipes can consist of inoculants and powdered refractory materials, as well as mixtures of silica and bentonite, put in place by projection of an aqueous suspension.
  • Such coatings are described for example in US Pat. No. 4,058,153 to "Pont-A-Monsoon” and are known as "wet-spray".
  • dry-spray powders sprayed on the shell before casting of the cast iron, powders then referred to as the "dry-spray".
  • inoculate more it may be preferable to inoculate more, even if it means slowing the production rate to avoid the final heat treatment, or, on the contrary, to inoculate little, to increase productivity, and to heat-treat the cast iron part downstream.
  • the inoculant capacity of the product can therefore be positioned within fairly wide limits; however, the other effects requested are subject to more constant requirements.
  • the "dry-spray” are therefore generally composed of a mixture of several components, including: An inoculant of greater or lesser effectiveness, which can typically constitute 30 to 100% of the product; may be used for this purpose, for example, ferro-silicon alloys containing 0.1 to 4% aluminum and 0.1 to 4% calcium, and possibly other elements likely to provide the cast an additional or complementary metallurgical effect. Powders of elements or alloys specifically conferring an anti-pitting effect: these may be typically the elements or alloys of the reducing elements of column 2 of the Mendeleev classification, for example silicon-calcium alloys; high calcium content, such as the alloy known as "CaSi" at approximately 30% Ca.
  • An inoculant of greater or lesser effectiveness which can typically constitute 30 to 100% of the product; may be used for this purpose, for example, ferro-silicon alloys containing 0.1 to 4% aluminum and 0.1 to 4% calcium, and possibly other elements likely to provide the cast an additional or complementary metallurgical effect.
  • An inert mineral filler for example silica, which can constitute up to 70% of the product.
  • dry-spray a powder generally consisting of the alloy of the "CaSi" type as mentioned above.
  • the invention relates to a powder product, for the protection of molds, or shells, used for the centrifugal casting of cast iron pipes, according to a process comprising the following steps:
  • first layer of the type known as "wet-spray"
  • first layer of the type known as "wet-spray”
  • dry projection on said first layer of said powder product comprising an alloy or a mixture of inoculating metal alloy (s), optionally powders of reducing elements or alloys with anti-pitting effect, optionally a inert mineral filler,
  • said product being characterized in that it further comprises at least one adjuvant intended to ensure that the "wet-spray" initially deposited on the shell is attached to the cast iron pipe during demolding.
  • the adjuvant is an alkaline carbonate; in another mode, it is an alkali silicate.
  • It can also be a mixture in any proportions of one or more alkali carbonate (s) and / or one or more alkali silicate (s).
  • the alkali silicate is sodium silicate in which the ratio of the mass content of SiO 2 component based on that of the Na 2 O component varies from 1 to 3.
  • the adjuvant is anhydrous sodium meta-silicate.
  • the mass proportion of adjuvant in said product is between 3 and 25%.
  • Powdered products of the prior art used as "dry-spray” for the protection of centrifugal casting molds cast iron pipes and sprayed on a first layer of the type "wet-spray” previously obtained by projection of an aqueous suspension of a mixture of silica and bentonite on the hot shell, have some disadvantages. Indeed, if they consist, as dry-spray dry sprayed directly on the shell, several components including:
  • An inoculant typically constituting 30 to 100% of the product and typically based on ferrosilicon-type alloys containing 0.1 to 4% of aluminum and calcium, optionally combined with other elements likely to contribute to the melts an additional or complementary metallurgical effect,
  • Powders of elements or alloys of reducing elements that specifically confer an anti-puncture effect for example silicon alloys with a high calcium content, such as in particular the "CaSi" type alloy with about 30% Ca,
  • Inert mineral filler for example silica, which can constitute up to 70% of the product, they do not allow the "wet-spray" to remain attached to the pipe during its demolding, thus contributing to increase the risks fouling of shells and formation inclusions in the cast iron, this fouling can also result, in addition to inclusions, by surface defects on the pipes.
  • one or more powder (s) of element (s) or alloys providing reducing elements conferring in particular an anti-puncture effect such as in particular Mg, Zn, Al, Ca ....
  • an inert mineral filler for example silica, but containing no or little alloy of the "CaSi" type,
  • This adjuvant may advantageously be an alkali metal carbonate or an alkali silicate, in particular sodium, in which the ratio of the SiO 2 content by mass ratio to that of component Na 2 O varies from 1 to 3, or a mixture in any proportions of one or more of these adjuvants namely alkaline carbonate (s) and / or alkali silicate (s), or finally anhydrous sodium meta-silicate, in all cases with a particle size of less than 350 ⁇ m.
  • the particle size of the powder product according to the invention is less than 580 ⁇ m and preferably 250 ⁇ m.
  • the effectiveness of the bonding of the "wet-spray” can be characterized by the percentage of the outer surface of the pipe where the "wet-spray” has not remained hooked.
  • the "dry-spray” is then deposited on the “wet-spray” after drying because of the heat of the shell, according to conventional deposition techniques for this type of product.
  • a "dry spray” consisting of 100% "CaSi” alloy containing 61.1% Si, 30.4% Ca and 1.21% Al was used as a reference test. whose granulometry is characterized by a passing at 63 microns of 25% and a passing at 200 microns of 98%.
  • the measurement of the particle size shows that it has a loop at 63 ⁇ m of 28% and a loop at 200 ⁇ m of 97%.
  • a mixture was prepared from the following constituents: 77% of ferro-silicon with 65.5% of Si, 1.3% of Ca and 0.95% of Al, with a particle size of less than 200 ⁇ m,
  • the measurement of the particle size shows that it has a loop at 63 ⁇ m of 24% and a loop at 200 ⁇ m of 95%.
  • Example No. 1 Used under the same conditions as in Example No. 1, this product has given satisfactory results for all the parameters: the pipes are practically free from pitting; the few bites present are shallow and allow to meet the specifications; the carbide content is 10% and there is a ferritic cast iron thickness of 35 ⁇ m on the outer surface of the pipe. The thickness of the border of dross in the interlocking is 7 mm. The percentage of the surface of the pipe without "wet-spray" is only 3%. There is therefore a metallurgical effect similar to that of a conventional "dry-spray" (example No.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Continuous Casting (AREA)
  • Heat Treatment Of Articles (AREA)
  • Coating By Spraying Or Casting (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)

Abstract

The invention relates to a powder product for protecting centrifugal casting molds of cast iron pipes, dry-projected onto a first wet-spray layer, comprising constituents common to dry-spray products with exception of CaSi alloys, as well as a wet-spray additive serving to ensure the adhesion to the pipe, during its removal from the mold, initially applied to the permanent mold. Said additive can be an alkali carbonate or alkali silicate, for example, sodium silicate in which the ratio of the wt. % of SiO2 to that of Na2O varies from 1 to 3, or anhydrous sodium metasilicate as well as a mixture consisting of one or more thereof in any proportions.

Description

Produits du type « dry-spray » pour la protection des moules de coulée centrifugée des tuyaux de fonte, en association avec un produit du type « wet-spray » Products of the "dry-spray" type for the protection of casting molds centrifuged cast iron pipes, in combination with a product type "wet-spray"
Domaine de l'inventionField of the invention
L'invention concerne un produit sous forme de poudre, du type « dry-spray », destiné à la protection des moules utilisés pour la coulée centrifugée des tuyaux de fonte, en association avec un produit de sous-couche du type « wet-spray » ; les moules de coulée utilisés sont communément désignés sous le nom de « coquilles ».The invention relates to a product in powder form, of the "dry-spray" type, intended for the protection of molds used for the centrifugal casting of cast iron pipes, in association with a sub-layer product of the "wet-spray" type. " the casting molds used are commonly referred to as "shells".
Etat de la techniqueState of the art
Sauf mention contraire, toutes les valeurs relatives à des compositions chimiques sont exprimées en pourcentage massique.Unless otherwise stated, all values relating to chemical compositions are expressed as a percentage by mass.
Les revêtements utilisés pour la protection des coquilles de coulée centrifugée des tuyaux de fonte peuvent être constitués d'inoculants et de matériaux réfractaires en poudre, ainsi que de mélanges de silice et de bentonite, mis en place par projection d'une suspension aqueuse. De tels revêtements sont décrits par exemple dans le brevet US 4.058.153 de « Pont- A- Mousson » et sont connus sous le nom de « wet-spray ».The coatings used for the protection of centrifugal casting shells of cast iron pipes can consist of inoculants and powdered refractory materials, as well as mixtures of silica and bentonite, put in place by projection of an aqueous suspension. Such coatings are described for example in US Pat. No. 4,058,153 to "Pont-A-Monsoon" and are known as "wet-spray".
II est également usuel d'utiliser des poudres projetées à sec sur la coquille avant coulée de la fonte, poudres désignées alors par le nom de « dry-spray ».It is also usual to use dry powders sprayed on the shell before casting of the cast iron, powders then referred to as the "dry-spray".
Dans le cas de tuyaux d'un diamètre supérieur typiquement à 400 mm, il est courant d'associer les deux types de produit, c'est à dire : - Une première couche du type « wet-spray », constituée d'un mélange de silice et de bentonite, séchant rapidement après projection sur la coquille chaude, - Une deuxième couche du type « dry-spray » projetée sur la première couche avant coulée de la fonte. Quelle que soit la technique mise en oeuvre pour leur dépôt, ces produits sont utilisés dans plusieurs buts, notamment :In the case of pipes with a diameter typically greater than 400 mm, it is common to combine the two types of product, ie: - A first layer of the "wet-spray" type, consisting of a mixture of silica and bentonite, drying quickly after projection on the hot shell, - A second layer of the "dry-spray" type projected on the first layer before casting of the cast iron. Whatever the technique used for their deposit, these products are used for several purposes, including:
- Obtenir un effet d'agent de démoulage, c'est à dire facilitant l'extraction du tuyau du moule après solidification, - Obtenir un effet de barrière thermique limitant la montée en température de la coquille et contribuant ainsi à augmenter sa durée de vie,- To obtain a release agent effect, ie facilitating the extraction of the pipe from the mold after solidification, - To obtain a thermal barrier effect limiting the rise in temperature of the shell and thus contributing to increasing its lifetime ,
- Obtenir un effet anti -piqûre c'est à dire limitant le risque d'apparition de piqûres à la surface des tuyaux,- Obtain an anti-puncture effect that is to say limiting the risk of occurrence of pitting on the surface of pipes,
- Obtenir un ultime effet inoculant sur la fonte coulée de façon à contrôler la structure métallurgique du tuyau.- Obtain an ultimate inoculating effect on the cast iron so as to control the metallurgical structure of the pipe.
Il est bien connu qu'une inoculation insuffisante entraîne dans la fonte la formation de carbures, un retrait important au refroidissement et un démoulage rapide, gage d'une productivité élevée. Mais les pièces ainsi obtenues nécessitent un traitement thermique ultérieur qui peut s' avérer coûteux.It is well known that insufficient inoculation leads to carbide formation in cast iron, significant cooling shrinkage and rapid demolding, a guarantee of high productivity. But the parts thus obtained require a subsequent heat treatment which can be expensive.
On peut, selon les cas, préférer inoculer davantage, quitte à ralentir la cadence de production pour éviter le traitement thermique final, ou au contraire inoculer peu, pousser la productivité, et traiter thermiquement la pièce en fonte en aval. Le pouvoir inoculant du produit peut donc se positionner dans des limites assez larges ; par contre les autres effets demandés sont l'objet d'exigences plus constantes.Depending on the case, it may be preferable to inoculate more, even if it means slowing the production rate to avoid the final heat treatment, or, on the contrary, to inoculate little, to increase productivity, and to heat-treat the cast iron part downstream. The inoculant capacity of the product can therefore be positioned within fairly wide limits; however, the other effects requested are subject to more constant requirements.
Dans le cas spécifique des « dry-spray » déposés sur une première couche de « wet-spray », ceux ci doivent de plus permettre au « wet-spray » de rester accroché sur le tuyau lors de son démoulage pour éviter son accumulation et la formation de crasses dans la coquille avec le risque de les entraîner dans la fonte lors de la coulée formant ainsi des défauts d'inclusions dans le tuyau, ou de créer des défauts de surface sur ce même tuyau.In the specific case of "dry-spray" deposited on a first layer of "wet-spray", these must also allow the "wet-spray" to remain attached to the pipe during its release to prevent its accumulation and the formation of dirt in the shell with the risk of causing them to melt during casting thus forming inclusions defects in the pipe, or to create surface defects on the same pipe.
Les « dry-spray » sont donc en général constitués d'un mélange de plusieurs composants dont : - Un inoculant d'efficacité plus ou moins forte, qui peut constituer typiquement 30 à 100 % du produit; peuvent être utilisés à cette fin, par exemple, des alliages de type ferro-silicium contenant 0,1 à 4 % d'aluminium ainsi que 0,1 à 4 % de calcium, et éventuellement d'autres éléments susceptibles d'apporter à la fonte un effet métallurgique supplémentaire ou complémentaire. - Des poudres d'éléments ou d'alliages conférant spécifiquement un effet anti-piqûre : il peut s'agir typiquement des éléments ou d'alliages des éléments réducteurs de la colonne 2 de la classification de Mendeleïev, par exemple des alliages silicium-calcium industriels à forte teneur en calcium comme notamment l'alliage connu sous l'appellation « CaSi » à environ 30 % de Ca.The "dry-spray" are therefore generally composed of a mixture of several components, including: An inoculant of greater or lesser effectiveness, which can typically constitute 30 to 100% of the product; may be used for this purpose, for example, ferro-silicon alloys containing 0.1 to 4% aluminum and 0.1 to 4% calcium, and possibly other elements likely to provide the cast an additional or complementary metallurgical effect. Powders of elements or alloys specifically conferring an anti-pitting effect: these may be typically the elements or alloys of the reducing elements of column 2 of the Mendeleev classification, for example silicon-calcium alloys; high calcium content, such as the alloy known as "CaSi" at approximately 30% Ca.
-Une charge minérale inerte, par exemple de la silice, qui peut constituer jusqu'à 70 % du produit.An inert mineral filler, for example silica, which can constitute up to 70% of the product.
Dans le cas spécifique des « dry-spray » déposés sur une première couche de « wet-spray », de tels mélanges ne permettent pas d'atteindre l'un des objectifs recherchés, à savoir cehii de permettre au « wet-spray » de rester accroché sur le tuyau lors de son démoulage.In the specific case of "dry-spray" deposited on a first layer of "wet-spray", such mixtures do not achieve one of the desired objectives, namely cehii to allow the "wet-spray" of stay hooked on the pipe during demolding.
A cette fin on utilise couramment comme « dry-spray » une poudre généralement constituée de l'alliage du type « CaSi » tel que précité.For this purpose, it is commonly used as "dry-spray" a powder generally consisting of the alloy of the "CaSi" type as mentioned above.
Toutefois, si ce type de poudre permet effectivement d'assurer l'accrochage du « wet-spray » sur le tuyau, elle n'est pas réellement satisfaisante pour ce qui est des autres effets précités dont notamment l'effet inoculant et plus généralement les effets relatifs au contrôle de la structure métallographique du tuyau en fonte.However, if this type of powder effectively ensures the attachment of "wet-spray" on the pipe, it is not really satisfactory with respect to the other aforementioned effects including the inoculant effect and more generally the effects relating to the control of the metallographic structure of the cast iron pipe.
Objet de l'invention :Object of the invention
L'invention a pour objet un produit en poudre, pour la protection des moules, ou coquilles, utilisés pour la coulée centrifugée des tuyaux de fonte, selon un procédé comportant les étapes suivantes :The invention relates to a powder product, for the protection of molds, or shells, used for the centrifugal casting of cast iron pipes, according to a process comprising the following steps:
- Création d'une première couche, du type connu sous le nom de « wet-spray », sur la surface interne de la coquille, par projection d'une suspension aqueuse d'un mélange de silice et de bentonite sur ladite surface interne de la coquille chaude, Projection à sec sur ladite première couche dudit produit en poudre comportant un alliage ou un mélange d'alliages métallique(s) inoculant(s), éventuellement des poudres d'éléments ou alliages réducteurs à effet anti -piqûres, éventuellement une charge minérale inerte,- Creation of a first layer, of the type known as "wet-spray", on the inner surface of the shell, by projection of an aqueous suspension of a mixture of silica and bentonite on said inner surface of the hot shell, dry projection on said first layer of said powder product comprising an alloy or a mixture of inoculating metal alloy (s), optionally powders of reducing elements or alloys with anti-pitting effect, optionally a inert mineral filler,
- Coulée centrifugée du tuyau de fonte,- Centrifugal casting of the cast iron pipe,
- Démoulage du tuyau de fonte, ledit produit étant caractérisé en ce qu'il comporte en outre au moins un adjuvant destiné à assurer l'accrochage sur le tuyau de fonte, lors de son démoulage, du « wet-spray » initialement déposé sur la coquille.- Demoulding of the cast iron pipe, said product being characterized in that it further comprises at least one adjuvant intended to ensure that the "wet-spray" initially deposited on the shell is attached to the cast iron pipe during demolding.
Selon un mode de réalisation avantageuse, l'adjuvant est un carbonate alcalin; selon un autre mode, il s'agit d'un silicate alcalin.According to an advantageous embodiment, the adjuvant is an alkaline carbonate; in another mode, it is an alkali silicate.
Il peut également s'agir d'un mélange en proportions quelconques d'un ou plusieurs carbonate(s) alcalin(s) et/ou d'un ou plusieurs silicate(s) alcalin(s).It can also be a mixture in any proportions of one or more alkali carbonate (s) and / or one or more alkali silicate (s).
De préférence, le silicate alcalin est du silicate de sodium dans lequel le ratio de la teneur massique en composant SiO2 rapportée à celle du composant Na2O varie de 1 à 3.Preferably, the alkali silicate is sodium silicate in which the ratio of the mass content of SiO 2 component based on that of the Na 2 O component varies from 1 to 3.
Selon un autre mode de réalisation préférentielle, l'adjuvant est du meta silicate de sodium anhydre.According to another preferred embodiment, the adjuvant is anhydrous sodium meta-silicate.
Enfin, selon un mode de réalisation avantageuse, la proportion massique d'adjuvant dans ledit produit est comprise entre 3 et 25 %.Finally, according to an advantageous embodiment, the mass proportion of adjuvant in said product is between 3 and 25%.
Description de l'invention :Description of the invention
Les produits en poudre de l'art antérieur, utilisés comme « dry-spray » pour la protection des moules de coulée centrifugée des tuyaux de fonte et projetés à sec sur une première couche du type « wet-spray » préalablement obtenue par projection d'une suspension aqueuse d'un mélange de silice et de bentonite sur la coquille chaude, présentent quelques inconvénients. En effet, s'ils sont constitués, comme les « dry-spray » pulvérisés à sec directement sur la coquille, de plusieurs composants dont notamment :Powdered products of the prior art, used as "dry-spray" for the protection of centrifugal casting molds cast iron pipes and sprayed on a first layer of the type "wet-spray" previously obtained by projection of an aqueous suspension of a mixture of silica and bentonite on the hot shell, have some disadvantages. Indeed, if they consist, as dry-spray dry sprayed directly on the shell, several components including:
- Un inoculant constituant typiquement 30 à 100 % du produit et typiquement à base d'alliages de type ferro-silicium contenant 0,1 à 4 % d'aluminium et de calcium, éventuellement associé à d'autres éléments susceptibles d'apporter à la fonte un effet métallurgique supplémentaire ou complémentaire,An inoculant typically constituting 30 to 100% of the product and typically based on ferrosilicon-type alloys containing 0.1 to 4% of aluminum and calcium, optionally combined with other elements likely to contribute to the melts an additional or complementary metallurgical effect,
- Des poudres d'éléments ou d'alliages d'éléments réducteurs conférant spécifiquement un effet anti-piqûre, par exemple des alliages de silicium à forte teneur en calcium comme notamment l'alliage du type « CaSi » à environ 30 % de Ca,Powders of elements or alloys of reducing elements that specifically confer an anti-puncture effect, for example silicon alloys with a high calcium content, such as in particular the "CaSi" type alloy with about 30% Ca,
-Une charge minérale inerte, par exemple de la silice, qui peut constituer jusqu'à 70 % du produit, ils ne permettent pas au « wet-spray » de rester accroché sur le tuyau lors de son démoulage, contribuant ainsi à augmenter les risques d'encrassement des coquilles et de formation d'inclusions dans la fonte, cet encrassement pouvant également se traduire, outre les inclusions, par des défauts de surface sur les tuyaux.Inert mineral filler, for example silica, which can constitute up to 70% of the product, they do not allow the "wet-spray" to remain attached to the pipe during its demolding, thus contributing to increase the risks fouling of shells and formation inclusions in the cast iron, this fouling can also result, in addition to inclusions, by surface defects on the pipes.
La charge minérale inerte en quantité trop importante présente le même risque.Inert mineral filler in too large a quantity presents the same risk.
Une solution consiste à augmenter la teneur en alliage « CaSi » du « dry-spray », généralement même jusqu'à 100 %.One solution is to increase the "CaSi" alloy content of the "dry spray", generally even up to 100%.
Toutefois, si l'effet recherché d'accrochage du « wet-spray » sur le tuyau lors de son démoulage est nettement amélioré, les autres effets recherchés s'en trouvent dégradés. En effet, bien que l'alliage « CaSi » soit en lui-même légèrement inoculant, il ne permet pas seul d'assurer le contrôle de la structure métallographique de la fonte constituant le tuyau de façon aussi efficace que les mélanges décrits auparavant.However, if the desired effect of hooking the "wet-spray" on the pipe during demolding is significantly improved, the other desired effects are degraded. Indeed, although the "CaSi" alloy is in itself slightly inoculant, it does not alone ensure the control of the metallographic structure of the cast iron constituting the pipe as effectively as the mixtures described above.
Accroître sa quantité pour augmenter son effet débouche sur le même inconvénient que cité précédemment, à savoir la formation de crasses dans les coquilles et plus particulièrement dans les zones de son empreinte correspondant aux emboîtements des tuyaux ; ce phénomène se traduit par des défauts d'inclusion ou de surface sur le tuyau, entraînant généralement son rebut.Increasing its quantity to increase its effect leads to the same disadvantage as mentioned above, namely the formation of dirt in the shells and more particularly in the areas of its imprint corresponding to the interlocking of the pipes; this phenomenon results in defects of inclusion or surface on the pipe, generally causing its rejection.
Pour pallier ces inconvénients, la demanderesse a donc cherché à obtenir un produit en poudre du type « dry-spray » à effet composite, c'est à dire conférant à la fois l'effet d'accrochage du « wet-spray » sur le tuyau lors de son démoulage et les autres effets anti-piqûres, d'inoculation et de contrôle de la structure métallographique de la fonte. Ce résultat a pu être obtenu par un « dry-spray » constitué :To overcome these drawbacks, the applicant has therefore sought to obtain a powder product of the "dry-spray" type with a composite effect, that is to say imparting both the hooking effect of the "wet-spray" on the pipe during demolding and other anti-pitting, inoculation and control effects of the metallographic structure of the cast iron. This result could be obtained by a "dry-spray" consisting of:
D'une part, pour 75 à 97 %, d'une poudre du type « dry- spray » habituel contenant un mélange de plusieurs composants dont :On the one hand, for 75 to 97%, a powder of the usual "dry-spray" type containing a mixture of several components including:
- Un ou plusieurs produit(s) inoculant(s) dans les compositions, proportions et granulométries usuelles pour les « dry-spray », tels que pré-cités,One or more product (s) inoculant (s) in the compositions, proportions and granulometries usual for "dry-spray", as mentioned above,
- Eventuellement une ou des ρoudre(s) d'élément(s) ou d'alliages apportant des éléments réducteurs conférant en particulier un effet anti-piqûre, tels que notamment Mg, Zn, Al, Ca ....- Possibly one or more powder (s) of element (s) or alloys providing reducing elements conferring in particular an anti-puncture effect, such as in particular Mg, Zn, Al, Ca ....
- Eventuellement une charge minérale inerte, par exemple de la silice, mais ne contenant pas ou peu d'alliage du type « CaSi »,- Possibly an inert mineral filler, for example silica, but containing no or little alloy of the "CaSi" type,
D'autre part, de 3 à 25 % d'un adjuvant destiné spécifiquement à assurer l'accrochage du « wet-spray » sur le tuyau lors de son démoulage.On the other hand, from 3 to 25% of an adjuvant intended specifically to ensure the attachment of "wet-spray" on the pipe during its demolding.
Cet adjuvant peut être avantageusement un carbonate alcalin ou un silicate alcalin, notamment de sodium dans lequel le ratio de la teneur massique en composant SiO2 rapportée à celle du composant Na2O varie de 1 à 3, ou encore un mélange en proportions quelconques de l'un ou plusieurs de ces adjuvants à savoir carbonate(s) alcalin(s) et/ou silicate(s) alcalin(s), ou enfin du meta silicate de sodium anhydre, dans tous les cas de granulométrie inférieure à 350 μm. La granulométrie du produit en poudre selon l'invention est inférieure à 580 μm et de préférence à 250 μm.This adjuvant may advantageously be an alkali metal carbonate or an alkali silicate, in particular sodium, in which the ratio of the SiO 2 content by mass ratio to that of component Na 2 O varies from 1 to 3, or a mixture in any proportions of one or more of these adjuvants namely alkaline carbonate (s) and / or alkali silicate (s), or finally anhydrous sodium meta-silicate, in all cases with a particle size of less than 350 μm. The particle size of the powder product according to the invention is less than 580 μm and preferably 250 μm.
Exemples :Examples:
L'efficacité du collage du « wet-spray » peut être caractérisée par le pourcentage de la surface extérieure du tuyau où le « wet-spray » n'est pas resté accroché.The effectiveness of the bonding of the "wet-spray" can be characterized by the percentage of the outer surface of the pipe where the "wet-spray" has not remained hooked.
Dans tous les exemples ci-après on dépose d'abord sur la coquille chaude un « wet-spray » contenant, après séchage, 95 % de silice (sous forme de diatomite) et 1 % de CaO ainsi que 3In all the examples below, a "wet spray" containing, after drying, 95% of silica (in the form of diatomite) and 1% of CaO as well as 3
% d'alumine apportés par de la bentonite.% of alumina brought by bentonite.
Le « dry-spray » est ensuite déposé sur le « wet-spray », après son séchage du fait de la seule chaleur de la coquille, selon les techniques classiques de dépôt pour ce type de produit.The "dry-spray" is then deposited on the "wet-spray" after drying because of the heat of the shell, according to conventional deposition techniques for this type of product.
Exemple N° 1 :Example No. 1:
On utilise à titre d'essai de référence un « dry-spray », constitué à 100% d'alliage « CaSi » contenant 61,1 % de Si, 30,4 % de Ca et 1,21 % d'Al, et dont la granulométrie est caractérisée par un passant à 63 μm de 25 % et un passant à 200 μm de 98 %.A "dry spray" consisting of 100% "CaSi" alloy containing 61.1% Si, 30.4% Ca and 1.21% Al was used as a reference test. whose granulometry is characterized by a passing at 63 microns of 25% and a passing at 200 microns of 98%.
Ce produit donne des résultats satisfaisants : les tuyaux sont pratiquement exempts de piqûres ; les quelques piqûres présentes sont peu profondes et permettent de respecter le cahier des charges ; le taux de carbures est de 8 % et on note une épaisseur de fonte ferritique de 35 μm en surface externe du tuyau. Lors du démoulage du tuyau, on constate que sur 2 % de sa surface le « wet-spray » n'est pas resté accroché. Les crasses se concentrent dans l'emboîtement et y forment un liseré d'une épaisseur de 15 mm.This product gives satisfactory results: the pipes are practically free from pitting; the few bites present are shallow and allow to meet the specifications; the carbide content is 8% and there is a thickness of ferritic cast iron of 35 μm in the outer surface of the pipe. When demolding the pipe, it is found that on 2% of its surface the "wet-spray" did not remain hooked. The drosses are concentrated in the interlocking and form a border with a thickness of 15 mm.
Exemple N° 2 :Example N ° 2:
On a préparé un mélange à partir des constituants suivants :A mixture was prepared from the following constituents:
93 % de ferro-silicium à 65,5 % de Si, 1,3 % de Ca et 0,95 % d'Al, de granulométrie inférieure à 200 μm, 3 % de Mg métallique en poudre de granulométrie comprise entre 200 et 400 μm,93% of ferro-silicon with 65.5% Si, 1.3% Ca and 0.95% Al, with a particle size of less than 200 μm, 3% of Mg metal powder with a particle size of between 200 and 400 μm,
4 % de spath fluor de granulométrie inférieure à 150 μm.4% of fluorspar of particle size less than 150 μm.
La mesure de la granulométrie montre qu'il possède un passant à 63 μm de 28 % et un passant à 200 μm de 97 %.The measurement of the particle size shows that it has a loop at 63 μm of 28% and a loop at 200 μm of 97%.
Utilisé dans les mêmes conditions que dans l'exemple n°l, ce produit donne les résultats suivants : les tuyaux sont pratiquement exempts de piqûres ; les quelques piqûres présentes sont peu profondes et permettent de respecter le cahier des charges ; le taux de carbures est deUsed under the same conditions as in Example No. 1, this product gives the following results: the pipes are practically free from pitting; the few bites present are shallow and allow to meet the specifications; the carbide content is
10 % et on note une épaisseur de fonte ferritique de 30 μm en surface externe du tuyau. Ces résultats sont satisfaisants. L'épaisseur du liseré de crasses dans l'emboîtement n'est plus que de 5 mm. Par contre le pourcentage de la surface du tuyau sans « wet-spray » s'élève à 60 %.10% and there is a thickness of ferritic cast iron of 30 μm on the outer surface of the pipe. These results are satisfactory. The thickness of the edge of dross in the interlocking is only 5 mm. By cons the percentage of the surface of the pipe without "wet-spray" is 60%.
11 apparaît clairement que le « dry-spray » de type classique (exemple n° 2) a un effet métallurgique très proche de celui d'un « dry-spray » constitué d'alliage « CaSi » seul ; par contre, il est nettement moins sujet à la formation de crasses, mais aussi nettement moins efficace quant à l'accrochage du « wet-spray » sur le tuyau.It is clear that the "dry-spray" of conventional type (Example No. 2) has a metallurgical effect very close to that of a "dry spray" consisting of alloy "CaSi" alone; on the other hand, it is clearly less subject to the formation of dirt, but also much less effective as to the attachment of the "wet-spray" on the pipe.
Exemple N° 3 :Example No. 3
On a préparé un mélange à partir des constituants suivants : 77 % de ferro-silicium à 65,5 % de Si, 1,3 % de Ca et 0,95 % d'Al, de granulométrie inférieure à 200 μm,A mixture was prepared from the following constituents: 77% of ferro-silicon with 65.5% of Si, 1.3% of Ca and 0.95% of Al, with a particle size of less than 200 μm,
3 % de Mg métallique en poudre de granulométrie comprise entre 200 et 300 μm,3% of Mg metal powder with a particle size of between 200 and 300 μm,
20 % de meta silicate de sodium anhydre de granulométrie inférieure à 350 μm.20% of anhydrous sodium metasilicate of particle size less than 350 microns.
La mesure de la granulométrie montre qu'il possède un passant à 63 μm de 24 % et un passant à 200 μm de 95 %.The measurement of the particle size shows that it has a loop at 63 μm of 24% and a loop at 200 μm of 95%.
Utilisé dans les mêmes conditions que dans l'exemple n°l, ce produit a donné des résultats satisfaisants pour l'ensemble des paramètres : les tuyaux sont pratiquement exempts de piqûres ; les quelques piqûres présentes sont peu profondes et permettent de respecter le cahier des charges ; le taux de carbures est de 10 % et on note une épaisseur de fonte ferritique de 35 μm en surface externe du tuyau. L'épaisseur du liseré de crasses dans l'emboîtement est de 7 mm. Le pourcentage de la surface du tuyau sans « wet-spray » n'est plus que de 3 %. On constate donc un effet métallurgique analogue à celui d'un « dry-spray » classique (exemple n° 2), mais avec une efficacité excellente quant à l'accrochage du « wet-spray » sur le tuyau et une tendance très faible à la formation de crasses (très inférieure à celle d'un « dry- spray » constitué d'alliage « CaSi » seul et analogue à celle d'un « dry-spray » de type classique sur un essai ponctuel mais avec un risque nettement réduit lors d'une utilisation en continue du fait de l'accrochage nettement amélioré du « wet-spray » sur le tuyau). Used under the same conditions as in Example No. 1, this product has given satisfactory results for all the parameters: the pipes are practically free from pitting; the few bites present are shallow and allow to meet the specifications; the carbide content is 10% and there is a ferritic cast iron thickness of 35 μm on the outer surface of the pipe. The thickness of the border of dross in the interlocking is 7 mm. The percentage of the surface of the pipe without "wet-spray" is only 3%. There is therefore a metallurgical effect similar to that of a conventional "dry-spray" (example No. 2), but with excellent efficiency as for the attachment of "wet-spray" on the pipe and a very low tendency to the formation of dirt (much lower than that of a "dry spray" made of alloy "CaSi" alone and similar to that of a "dry-spray" of the conventional type on a one-off test but with a significantly reduced risk when used continuously because of the significantly improved hooking of the "wet-spray" on the pipe).

Claims

Revendications claims
1. Produit en poudre, pour la protection des moules, ou coquilles, utilisés pour la coulée centrifugée des tuyaux de fonte, selon un procédé comportant les étapes suivantes : - Création d'une première couche, du type connu sous le nom de « wet-spray », sur la surface interne de la coquille, par projection d'une suspension aqueuse d'un mélange de silice et de bentonite sur ladite surface interne de la coquille chaude, Projection à sec sur ladite première couche dudit produit en poudre comportant un alliage ou un mélange d'alliages métallique(s) inoculant(s), éventuellement des poudres d'éléments ou alliages réducteurs à effet anti-piqûres, éventuellement une charge minérale inerte,1. Powdered product, for the protection of molds, or shells, used for the centrifugal casting of cast iron pipes, according to a process comprising the following steps: - Creation of a first layer, of the type known under the name of "wet" -spray ", on the inner surface of the shell, by projection of an aqueous suspension of a mixture of silica and bentonite on said inner surface of the hot shell, dry projection on said first layer of said powder product comprising a alloy or a mixture of inoculant metal alloy (s), optionally powders of reducing elements or alloys with an anti-pitting effect, optionally an inert mineral filler,
Coulée centrifugée du tuyau de fonte, - Démoulage du tuyau de fonte, ledit produit étant caractérisé en ce qu'il comporte en outre au moins un adjuvant destiné à assurer l'accrochage sur le tuyau de fonte, lors de son démoulage, du « wet-spray » initialement déposé sur la coquille.Centrifuged casting of the cast iron pipe, - Demoulding of the cast iron pipe, said product being characterized in that it furthermore comprises at least one adjuvant intended to ensure the hooking on the cast pipe, during its demoulding, of the "wet -spray "initially deposited on the shell.
2. Produit selon la revendication 1, caractérisé en ce que l'adjuvant est un carbonate alcalin.2. Product according to claim 1, characterized in that the adjuvant is an alkali carbonate.
3. Produit selon la revendication 1, caractérisé en ce que l'adjuvant est un silicate alcalin.3. Product according to claim 1, characterized in that the adjuvant is an alkali silicate.
4. Produit selon la revendication 1, caractérisé en ce que l'adjuvant est un mélange en proportions quelconques d'un ou plusieurs carbonate(s) alcalin(s) et/ou d'un ou plusieurs silicate(s) alcalin(s).4. Product according to claim 1, characterized in that the adjuvant is a mixture in any proportions of one or more alkali carbonate (s) and / or one or more alkali silicate (s) .
5. Produit selon l'une des revendications 3 ou 4, caractérisé en ce que le silicate alcalin est du silicate de sodium dans lequel le ratio de la teneur massique en composant SiO2 rapportée à celle du composant Na2O varie de 1 à 3.5. Product according to one of claims 3 or 4, characterized in that the alkali silicate is sodium silicate in which the ratio of the mass content of SiO2 component relative to that of the Na2O component varies from 1 to 3.
6. Produit selon l'une des revendications 1 à 5, caractérisé en ce que l'adjuvant est du meta silicate de sodium anhydre. 6. Product according to one of claims 1 to 5, characterized in that the adjuvant is anhydrous sodium meta-silicate.
7. Produit selon Tune des revendications 1 à 6, caractérisé en ce que la proportion massique d'adjuvant dans ledit produit est comprise entre 3 et 25 %. 7. Product according to one of claims 1 to 6, characterized in that the mass proportion of adjuvant in said product is between 3 and 25%.
EP06778578A 2005-04-20 2006-03-29 Dry-spray products for protecting centrifugal casting molds of cast iron pipes in association with a wet-spray product Withdrawn EP1871554A1 (en)

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FR0503949A FR2884739B1 (en) 2005-04-20 2005-04-20 DRY-SPRAY PRODUCTS FOR THE PROTECTION OF CENTRIFUGE CASTING MOLDS OF CAST IRON PIPES IN COMBINATION WITH A WET-SPRAY PRODUCT
PCT/FR2006/000676 WO2006131612A1 (en) 2005-04-20 2006-03-29 Dry-spray products for protecting centrifugal casting molds of cast iron pipes in association with a wet-spray product

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FR3089138B1 (en) * 2018-11-29 2021-10-08 Elkem Materials Mold powder and mold coating
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KR20070122240A (en) 2007-12-28
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FR2884739A1 (en) 2006-10-27
AU2006256658B2 (en) 2011-05-26
FR2884739B1 (en) 2007-06-29
RU2407607C2 (en) 2010-12-27
CN101160186A (en) 2008-04-09
JP2008536688A (en) 2008-09-11
US20080178767A1 (en) 2008-07-31
MY146133A (en) 2012-06-29
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BRPI0609974A2 (en) 2011-10-11
EG24801A (en) 2010-09-15
WO2006131612A1 (en) 2006-12-14

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