EP2057107B1 - Size for production of a bn-containing coating, method for production thereof coated body production and use thereof - Google Patents

Size for production of a bn-containing coating, method for production thereof coated body production and use thereof Download PDF

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Publication number
EP2057107B1
EP2057107B1 EP20070801637 EP07801637A EP2057107B1 EP 2057107 B1 EP2057107 B1 EP 2057107B1 EP 20070801637 EP20070801637 EP 20070801637 EP 07801637 A EP07801637 A EP 07801637A EP 2057107 B1 EP2057107 B1 EP 2057107B1
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EP
European Patent Office
Prior art keywords
weight
slip
coating
coated body
substrate
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Not-in-force
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EP20070801637
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German (de)
French (fr)
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EP2057107A1 (en
Inventor
Martin Engler
Krishna Uibel
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ESK Ceramics GmbH and Co KG
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ESK Ceramics GmbH and Co KG
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
    • Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/29—Coated or structually defined flake, particle, cell, strand, strand portion, rod, filament, macroscopic fiber or mass thereof
    • Y10T428/2913—Rod, strand, filament or fiber
    • Y10T428/2916—Rod, strand, filament or fiber including boron or compound thereof [not as steel]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/31504—Composite [nonstructural laminate]
    • Y10T428/31678—Of metal
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T442/00—Fabric [woven, knitted, or nonwoven textile or cloth, etc.]
    • Y10T442/20—Coated or impregnated woven, knit, or nonwoven fabric which is not [a] associated with another preformed layer or fiber layer or, [b] with respect to woven and knit, characterized, respectively, by a particular or differential weave or knit, wherein the coating or impregnation is neither a foamed material nor a free metal or alloy layer

Definitions

  • the present invention relates to a hydrous sizing agent for producing a BN-containing coating on a substrate, a process for producing such a sizing, a coated body of a substrate and a coating applied thereon, which has been prepared from the sizing, and the use of the coated body, for example in the form of casting tables, runners and holding containers, in the field of foundry applications, in particular light metal casting applications.
  • the work equipment and apparatus used in foundries are typically provided with a coating to keep these equipment and devices resistant to highly corrosive metal melts, such as aluminum melts, at temperatures in the range of 600 to 950 ° C to protect.
  • a coating for the preparation of such coatings usually based on BN slurries in water, optionally with inorganic or organic binders are used.
  • binders for example, alumina, bentonite. Phosphates and silicates used.
  • these sizes have the disadvantage that only powdery layers or layers of low layer thickness can be applied without cracking and that the layers tend to flake off and therefore have only a limited life.
  • a further disadvantage is that coatings produced from these sizes are not or only limitedly resistant to abrasion in the cold state, so that it is easy to damage the coatings, for example when cleaning with metallic objects such as pliers and iron bars. If the coating is not abrasion-resistant and scratch-resistant, it is easily destroyed.
  • BN-containing hard coatings and release coatings are also known in the art. That's how it describes DE 101 27 494 B4 a high temperature stable inorganic layer made of a ceramic boron nitride offset, at least one of ceramic Nanoparticles, inorganic binder system and at least one solvent, such as water.
  • the EP 1 386 983 B1 describes a ceramic coating prepared from a mixture of boron nitride, at least one inorganic binder of average particle size in the nanometer range and at least one solvent and / or water by applying the mixture to a metallic or ceramic surface and baking the mixture.
  • the DE 103 26 769 B3 describes durable BN-form release layers for the die casting of non-ferrous metals as well as their sizing, whereby refractory nanoscale binders are used as binding phase for boron nitride.
  • suspensions of SiO 2 -based sol-gel binder and BN powder are applied to metal or inorganic non-metal surfaces, and the coatings thus obtained are dried and thermally densified.
  • the binder system transforms into a glassy matrix, which gives the resulting ceramic layer mechanical stability.
  • BN hardcoats and release coatings are not applicable to metal foundry applications because these layers require careful surface preparation and high film layup uniformity, which is not feasible under foundry conditions. Ebeso also uneven substrates must be coated in foundries, which is also not possible with the known from the aforementioned patents sizing. With the sizes according to these patents, just as with the foundry coatings usually used in foundry molding, only layers of limited layer thickness can be applied, dried and baked without defects. These layers continue to have only a limited life and are only limited abrasion and scratch resistance in the cold state.
  • the invention is therefore based on the object to provide a BN-containing size available, can be made free of cracks with the thick coatings long life, the coatings do not chipping and their susceptibility to cracking, especially when used in G confuseeretanassemble, lower and their abrasion resistance in the cold state is higher than in the known from the prior art coatings for foundry applications.
  • a size for producing a BN-containing coating on a substrate according to claim 1 a method for producing such a size according to claim 11, a coated body comprising a substrate with a coating applied thereto according to claim 12 , a method for producing such a coated body according to claim 15 and the use of a coated body according to claim 19.
  • Advantageous or particularly expedient embodiments of the subject of the application are specified in the subclaims.
  • the coatings prepared from the sizes according to the invention are flexible for a long time at the usual application temperatures, which property is referred to herein as "hot flexibility".
  • hot flexibility can not be observed in the coatings known from the prior art.
  • the formation of cracks in the coatings due to different expansion coefficients between substrate and coating material can be prevented or any cracks that have occurred can be healed again, so that the coatings according to the invention have a self-healing property.
  • the coatings produced according to the invention also have a significantly lower tendency to chip off in use, so that coatings with a significantly longer service life can be achieved.
  • the coatings can also be heated quickly from room temperature to the usual application temperatures of 600 to 950 ° C.
  • the coatings produced according to the invention are also abrasion-resistant in the cold state, which is the case with layers made from conventional foundry coatings are not the case. This reduces the risk of damage to the coatings when cleaning with tools, and the equipment and devices provided with such a coating are reusable without repair for a long time.
  • thick layers can be produced free of cracks with the sizes according to the invention, the possible layer thickness being significantly higher than in the case of the coatings known in the prior art.
  • the production of thick layers also makes it possible to fill and close any cracks and asperities in the substrate.
  • defects in the equipment and tools can be filled without causing cracks during subsequent drying.
  • cracks which have formed can be sealed with the sizes according to the invention.
  • Another advantage of such thick layers is their longer lifetime, since their wear, even with abrasive wear, a higher layer thickness is available.
  • the sizes according to the invention can also be applied to unclean substrates without expensive surface pretreatment, which is not possible with sizes according to the patent specifications mentioned above.
  • non-oxidation-resistant substrates such as, for example, metal or graphite
  • decomposition of the water-insoluble boron compound contained therein at temperatures from 600 ° C.
  • Such a decomposition of the water-insoluble boron compound obviously proceeds via the consumption of oxygen, so that oxygen can not reach the surface of the substrate during the decomposition of the boron-containing compound in the coating.
  • the illustration 1 is a graph of an abrasion test in which the abrasion resistance of a coating of a size according to the invention according to Example 3 was compared with commercial coatings.
  • Water or alcohols such as ethanol, or water / alcohol mixtures can be used as the solvent or dispersion medium for the water-containing sizes according to the invention.
  • ethanol e.g., ethanol
  • water / alcohol mixtures e.g., water / alcohol mixtures
  • the solids content of the size is preferably 20-40% by weight, more preferably 25-35% by weight.
  • the BN content is preferably 45-85 wt.%, More preferably 45-75 wt.%
  • the content of boehmite nanoparticles is preferably 5-20 wt.%, More preferably 10-18 Wt .-%, the content of borate preferably 1-4 wt .-%, more preferably 1-3 wt .-%, the content of the water-insoluble boron compound preferably 5-25 wt .-%, more preferably 5-20 wt. % and the content of an organic compound is preferably 3-20% by weight, more preferably 3-15% by weight.
  • the BN of component a) is preferably used as BN powder having an average particle size of 1-30 microns, more preferably 2-15 microns. It is also possible to use BN agglomerates having a mean agglomerate size of 20-100 ⁇ m, preferably 20-50 ⁇ m. Likewise, mixtures of both forms are possible.
  • the BN used may further contain up to 10% by weight of various impurities and additives. In particular, mention may be made of boric acid, boron trioxide, carbon, alkali or alkaline earth borates. However, it is preferred that as pure, washed out BN with a purity of at least 98%, preferably 99%, is used.
  • the boehmite nanoparticles used in the size according to the invention preferably have an average particle size of 1-100 nm, more preferably 1-40 nm and particularly preferably 2-20 nm.
  • Commercially available boehmite powder can be used, for example as described by Sasol in US Pat Qualities Disperal or Dispal sold, preferably one with the product name Disperal P2 is used.
  • the borate c) is preferably selected from the group consisting of lithium borate, potassium borate, sodium borate, calcium borate and borax, borax in particular being preferred.
  • the borate may also be present as a production-related impurity in the BN powder.
  • the water-insoluble boron compound d) is preferably selected from the group consisting of boron carbide (B 4 C), metal borides and elemental boron. These boron compounds are oxidized during normal use of the sizings with atmospheric oxygen to boron oxide, in particular boron carbide is preferred. Examples of suitable metal borides are TiB 2 . ZrB 2 and CaB 6 .
  • Suitable organic compounds e) are compounds which form a liquid or viscous phase when the sizings are used as intended and burn out at relatively high temperatures, leaving behind pores.
  • Such organic compounds are preferably selected from synthetic polymers, such as thermoplastics, natural polymers, such as celluloses and cellulose derivatives, waxes, oils and polyphosphate esters group are selected. It is likewise possible to use water-based paints in the form of a suspension or emulsion having a fine dispersion distribution, preferably having a particle size or drop size of ⁇ 50 ⁇ m. Preference is given to low-melting compounds and non-water-soluble compounds. Water-soluble compounds should not crystallize out. Particularly preferred as the organic compound, a polyvinyl butyral (PVB) is used.
  • PVB polyvinyl butyral
  • the optional hard materials g) are preferably selected from the group comprising Al 2 O 3 , ZrO 2, TiO 2 and SiC. These additional hard materials increase the abrasion resistance in the cold state of the coatings produced from the sizes. Although TiO 2 has the lowest hardness among the latter substances, it is particularly suitable when using the size under oxidizing conditions.
  • the optionally contained metal powder h) is preferably added when the sizes according to the invention are provided for coating metallic substrates.
  • the metal powders are selected from the group of metals Al, Mg, Si, Zr, Sn, Zn, mixtures or alloys thereof, which are capable of dissolving iron from metallic substrates.
  • mixed crystals or intermetallic phases are formed at the interface between substrate and coating.
  • the oxidation products of these phases form a protective film, thereby improving the oxidation resistance of the substrate.
  • Particular preference is given to selecting the metal powder h) from the group of light metals having a melting point below 800 ° C., particularly preferably from Al, Mg, their mixtures and alloys.
  • boehmite powder grades with particle sizes in the nanometer range can be used to produce the boehmite sol, for example the above-mentioned, commercially available boehmite powder from Sasol.
  • the boehmite powders are stirred into an aqueous medium, preferably water, which is more preferably preheated, preferably to temperatures above 80 ° C.
  • the preparation of a boehmite sol can be via alkoxide routes according to the Yoldas process or via the use of aluminum salts and addition of a base. After homogenization, the dispersion is usually peptized by acid addition and converted into a sol.
  • solids concentrations in the sol of up to 20% by weight of boehmite, preferably 5-12% by weight can be adjusted.
  • the boehmite sol prepared as above serves as a dispersing medium into which the remaining constituents of the size are introduced by portioned addition of the powder components with simultaneous homogenization.
  • the homogenization can be carried out by means of conventional stirring devices, such as a blade stirrer.
  • the remaining components are added in the order of 1) water-soluble ingredients, 2) fine powders, and 3) coarse powders.
  • the homogenization can be carried out in a ball mill, in an attritor, with an Ultraturrax or by means of other dispersing or milling units.
  • the invention furthermore relates to a coated body comprising a substrate with a coating applied thereto, wherein the coating has been produced from a size according to the invention.
  • the substrate may be a metallic, ceramic or other inorganic (e.g., graphite) substrate.
  • the substrate can be in the form of any shaped article or shaped article, a film, a fabric or a fiber.
  • the application of the size can be carried out at room temperature or at substrate temperatures up to 300 ° C.
  • the substrate can be pretreated with a primer.
  • the drying of the still moist coating can be carried out at room temperature, but preferably at temperatures of 80-100 ° C.
  • the firing according to step 3) can be carried out in situ when using the coated body in a foundry application, the heat being supplied either by contact with molten metals or hot moldings or by radiation and / or convection.
  • baking can also be carried out beforehand in a separate process step at temperatures of 180 to 800 ° C., preferably at temperatures of 470 ° C. or above, in particular 500 ° C. or above.
  • the function and mode of action of the individual components of the size according to the invention in the formation of coatings can be explained as follows.
  • the coatings obtainable according to the invention are hot-flexible and self-healing. This can be explained by the fact that when passing through the entire temperature range from room temperature to the use temperature of about 750 ° C in the sizing or the coating always a liquid or viscous phase is available, which ensures that no cracks or if necessary, cracks are closed again.
  • the various components of the size result in overlapping areas of liquid or viscous phases: water up to 100 ° C., then liquefaction of the organic compound, for example liquid PVB at about 70-200 ° C., boric acid, if present, from 170 ° C. and boron oxide from 450 ° C., and above 600 ° C., finally, the water-insoluble boron compound, as B 4 C, oxidized to B 2 O 3 .
  • Dissolved borax Na2B 4 O 7 x 10 H 2 O
  • a body coated according to the invention is particularly suitable in the field of foundry applications, in particular light-metal foundry applications.
  • the coated body is a casting table, a runner or a container for holding or transporting molten metal.
  • the sizes according to the invention can furthermore be used in an inverse coating process.
  • a coating is applied to a sand mold using a sizing invention.
  • a metal casting preferably a metal having a melting point> 1200 ° C, the sand mold is then removed.
  • a metallic object for example a ladle, can be obtained, which is already provided with a coating baked in situ according to the invention.
  • Example 1 or Example 2 having a solids content of boehmite of 7.1% by weight (corresponding to a content of 8.8 g of hydrated boehmite powder Disperal P2 or corresponding to 6 g of resulting Al 2 O 3 content) is initially charged as dispersing medium.
  • the powdery components of the suspension are homogenized in the sol using an Ultraturrax.
  • the coated panels were cooled to room temperature and tested in a Taber Abraser Test, 3N, Friction Rolls AT20D1-CS110F.
  • Table 1 Cross hatch test results for different BN coatings Inventive coating (Example 3) Al 2 O 3 binder (type 1) Al 2 O 3 binder (Type 2) Magnesium silicate binder GT value 0 1 5 5
  • a GT value of 0 corresponds to the best detectable adhesive strength.
  • the coating according to the invention according to Example 3 has reached the best value.
  • Table 2 summarizes the GT values that can be determined. Table 2: Assignment of GT values GT values Description (short version) 0 no flaking 1 about 5% flaking 2 about 15% flaking 3 about 35% flaking 4 about 65% flaking 5 > 65% flaking

Abstract

The invention relates to a water-containing slip for producing a BN-containing coating on a substrate, which comprises, based on the solids content of the slip, a) 45-90% by weight of BN, b) 3-25% by weight of boehmite nanoparticles, c) 0.5-5% by weight of at least one borate, d) 2-30% by weight of at least one water-insoluble boron compound which is different from the components a) and c), e) 2-30% by weight of an organic compound, where the solids content of the slip is 15-60% by weight.

Description

Gebiet der ErfindungField of the invention

Die vorliegende Erfindung betrifft eine wasserhaltige Schlichte zur Herstellung einer BN-haltigen Beschichtung auf einem Substrat, ein Verfahren zur Herstellung einer solchen Schlichte, einen beschichteten Körper aus einem Substrat und einer darauf aufgebrachten Beschichtung, die aus der Schlichte hergestellt worden ist, sowie die Verwendung des beschichteten Körpers, beispielsweise in Gestalt von Gießtischen, Gießrinnen und Warmhaltebehältern, auf dem Gebiet der Gießereianwendungen, insbesondere Leichtmetallgießereianwendungen.The present invention relates to a hydrous sizing agent for producing a BN-containing coating on a substrate, a process for producing such a sizing, a coated body of a substrate and a coating applied thereon, which has been prepared from the sizing, and the use of the coated body, for example in the form of casting tables, runners and holding containers, in the field of foundry applications, in particular light metal casting applications.

Stand der TechnikState of the art

Die in Gießereien verwendeten Arbeitsgerätschaften und Vorrichtungen, wie Gießtische, Gießrinnen und Behälter zum Warmhalten und Transportieren von Metallschmelzen, sind in der Regel mit einer Beschichtung versehen, um diese Gerätschaften und Vorrichtungen gegenüber den stark korrosiv wirkenden Metallschmelzen, wie Aluminiumschmelzen, bei Temperaturen im Bereich von 600 bis 950°C zu schützen. Zur Herstellung solcher Beschichtungen werden üblicherweise Schlichten auf Basis von BN-Aufschlämmungen in Wasser, gegebenenfalls mit anorganischen oder organischen Bindern eingesetzt. Als Binder werden beispielsweise Aluminiumoxid, Bentonit. Phosphate und Silicate verwendet. Diese Schlichten haben jedoch den Nachteil, dass mit ihnen nur pulvrige Schichten bzw. Schichten von geringer Schichtdicke rissfrei aufgebracht werden können und dass die Schichten zum Abplatzen neigen und daher nur eine begrenzte Lebensdauer haben. Ein weiterer Nachteil besteht darin, dass aus diesen Schlichten hergestellte Beschichtungen im kalten Zustand nicht oder nur beschränkt abriebfest sind, so dass es leicht zu Beschädigungen der Beschichtungen kommen kann, beispielsweise beim Reinigen mittels metallischer Gegenstände wie Zangen und Eisenstangen. Ist die Beschichtung nicht abrieb- und kratzfest, wird sie hierbei leicht zerstört.The work equipment and apparatus used in foundries, such as casting tables, runners, and containers for holding and transporting molten metals, are typically provided with a coating to keep these equipment and devices resistant to highly corrosive metal melts, such as aluminum melts, at temperatures in the range of 600 to 950 ° C to protect. For the preparation of such coatings usually based on BN slurries in water, optionally with inorganic or organic binders are used. As binders, for example, alumina, bentonite. Phosphates and silicates used. However, these sizes have the disadvantage that only powdery layers or layers of low layer thickness can be applied without cracking and that the layers tend to flake off and therefore have only a limited life. A further disadvantage is that coatings produced from these sizes are not or only limitedly resistant to abrasion in the cold state, so that it is easy to damage the coatings, for example when cleaning with metallic objects such as pliers and iron bars. If the coating is not abrasion-resistant and scratch-resistant, it is easily destroyed.

Andererseits sind BN-haltige Hartbeschichtungen und Trennmittelschichten ebenfalls aus dem Stand der Technik bekannt. So beschreibt die DE 101 27 494 B4 eine hochtemperaturstabile anorganische Schicht, hergestellt aus einem keramischen Versatz von Bornitrid, mindestens einem aus keramischen Nanoteilchen bestehenden, anorganischen Bindersystem und mindestens einem Lösungsmittel, beispielsweise Wasser.On the other hand, BN-containing hard coatings and release coatings are also known in the art. That's how it describes DE 101 27 494 B4 a high temperature stable inorganic layer made of a ceramic boron nitride offset, at least one of ceramic Nanoparticles, inorganic binder system and at least one solvent, such as water.

Die EP 1 386 983 B1 beschreibt eine keramische Beschichtung, hergestellt aus einer Mischung aus Bornitrid, mindestens einem anorganischen Bindemittel einer mittleren Teilchengröße im Nanometerbereich und mindestens einem Lösungsmittel und/oder Wasser durch Auftragen der Mischung auf eine metallische oder keramische Oberfläche und Einbrennen der Mischung.The EP 1 386 983 B1 describes a ceramic coating prepared from a mixture of boron nitride, at least one inorganic binder of average particle size in the nanometer range and at least one solvent and / or water by applying the mixture to a metallic or ceramic surface and baking the mixture.

Die DE 103 26 769 B3 beschreibt dauerhafte BN-Formtrennschichten für das Druckgießen von Nichteisenmetallen sowie Schlichten zu deren Herstellung, wobei refraktäre nanoskalige Bindemittel als Bindephase für Bornitrid eingesetzt werden. Insbesondere werden Suspensionen aus SiO2-basiertem Sol-Gel-Binder und BN-Pulver auf Metall- oder anorganische Nichtmetalloberflächen aufgebracht und die so erhaltenen Beschichtungen getrocknet und thermisch verdichtet. Bei Temperaturen über 500°C wandelt sich das Bindersystem in eine glasartige Matrix um, die der dabei entstehenden keramischen Schicht mechanische Stabilität verleiht.The DE 103 26 769 B3 describes durable BN-form release layers for the die casting of non-ferrous metals as well as their sizing, whereby refractory nanoscale binders are used as binding phase for boron nitride. In particular, suspensions of SiO 2 -based sol-gel binder and BN powder are applied to metal or inorganic non-metal surfaces, and the coatings thus obtained are dried and thermally densified. At temperatures above 500 ° C, the binder system transforms into a glassy matrix, which gives the resulting ceramic layer mechanical stability.

Die vorgenannten BN-Hartbeschichtungen und Trennmittelschichten sind jedoch für Metallgießereianwendungen nicht einsetzbar, da diese Schichten eine sorgfältige Oberflächenvorbehandlung und eine hohe Gleichmäßigkeit bei der Schichtaufbringung erfordern, was unter den Bedingungen in Gießereien nicht umsetzbar ist. Ebeso müssen in Gießereien auch unebene Untergründe beschichtet werden, was mit den aus den vorgenannten Patentschriften bekannten Schlichten ebenfalls nicht möglich ist. Mit den Schlichten gemäß diesen Patentschriften können ebenso wie bereits mit den üblicherweise in Gießereiten eingesetzten Gießereischlichten nur Schichten von begrenzter Schichtdicke defektfrei aufgebracht, getrocknet und eingebrannt werden. Diese Schichten weisen weiterhin nur eine begrenzte Lebensdauer auf und sind auch im kalten Zustand nur beschränkt abrieb- und kratzfest.The aforementioned BN hardcoats and release coatings, however, are not applicable to metal foundry applications because these layers require careful surface preparation and high film layup uniformity, which is not feasible under foundry conditions. Ebeso also uneven substrates must be coated in foundries, which is also not possible with the known from the aforementioned patents sizing. With the sizes according to these patents, just as with the foundry coatings usually used in foundry molding, only layers of limited layer thickness can be applied, dried and baked without defects. These layers continue to have only a limited life and are only limited abrasion and scratch resistance in the cold state.

Aufgabe der ErfindungObject of the invention

Der Erfindung liegt daher die Aufgabe zugrunde, eine BN-haltige Schlichte zur Verfügung zu stellen, mit der dicke Beschichtungen hoher Lebensdauer rissfrei hergestellt werden können, wobei die Beschichtungen nicht zum Abplatzen neigen und deren Rissanfälligkeit, insbesondere im Einsatz bei Gießeretanwendungen, geringer und deren Abrasionsbeständigkeit im kalten Zustand höher ist als bei den aus dem Stand der Technik bekannten Beschichtungen für Gießereianwendungen.The invention is therefore based on the object to provide a BN-containing size available, can be made free of cracks with the thick coatings long life, the coatings do not chipping and their susceptibility to cracking, especially when used in Gießeretanwendungen, lower and their abrasion resistance in the cold state is higher than in the known from the prior art coatings for foundry applications.

Zusammenfassung der ErfindungSummary of the invention

Die oben genannte Aufgabe wird erfindungsgemäß gelöst durch eine Schlichte zur Herstellung einer BN-haltigen Beschichtung auf einem Substrat gemäß Anspruch 1, ein Verfahren zur Herstellung einer solchen Schlichte gemäß Anspruch 11, einen beschichteten Körper, umfassend ein Substrat mit einer darauf aufgebrachten Beschichtung gemäß Anspruch 12, ein Verfahren zur Herstellung eines solchen beschichteten Körpers gemäß Anspruch 15 sowie die Verwendung eines beschichteten Körpers gemäß Anspruch 19. Vorteilhafte bzw. besonders zweckmäßige Ausgestaltungen des Anmeldungsgegenstandes sind in den Unteransprüchen angegeben.The above object is achieved according to the invention by a size for producing a BN-containing coating on a substrate according to claim 1, a method for producing such a size according to claim 11, a coated body comprising a substrate with a coating applied thereto according to claim 12 , a method for producing such a coated body according to claim 15 and the use of a coated body according to claim 19. Advantageous or particularly expedient embodiments of the subject of the application are specified in the subclaims.

Gemäß der Erfindung hat sich in überraschender Weise gezeigt, dass die aus den erfindungsgemäßen Schlichten hergestellten Beschichtungen bei den üblichen Anwendungstemperaturen über längere Zeit flexibel sind, welche Eigenschaft hierin als "Heißflexibilität" bezeichnet wird. Eine solche Heißflexibilität kann bei den aus dem Stand der Technik bekannten Beschichtungen nicht beobachtet werden. Dadurch kann die Entstehung von Rissen in den Beschichtungen aufgrund von unterschiedlichen Ausdehnungskoeffizienten zwischen Substrat- und Beschichtungsmaterial verhindert werden oder eventuell aufgetretene Risse werden wieder geheilt, so dass den erfindungsgemäßen Beschichtungen eine Selbstheilungseigenschaft zukommt. Dadurch haben die erfingdungsgemäß hergestellten Beschichtungen im Einsatz auch eine deutlich geringere Neigung zum Abplatzen, so dass Beschichtungen mit einer deutlich längeren Lebensdauer erzielt werden.According to the invention, it has surprisingly been found that the coatings prepared from the sizes according to the invention are flexible for a long time at the usual application temperatures, which property is referred to herein as "hot flexibility". Such a hot flexibility can not be observed in the coatings known from the prior art. As a result, the formation of cracks in the coatings due to different expansion coefficients between substrate and coating material can be prevented or any cracks that have occurred can be healed again, so that the coatings according to the invention have a self-healing property. As a result, the coatings produced according to the invention also have a significantly lower tendency to chip off in use, so that coatings with a significantly longer service life can be achieved.

Durch diese Flexibilität über die gesamte Anwendungstemperatur können die Beschichtungen auch schnell von Raumtemperatur bis auf die üblichen Anwendungstemperaturen von 600 bis 950°C aufgeheizt werden.This flexibility over the entire application temperature, the coatings can also be heated quickly from room temperature to the usual application temperatures of 600 to 950 ° C.

Ferner sind die erfindungsgemäß hergestellten Beschichtungen auch im kalten Zustand abriebfest, was bei Schichten, die aus herkömmlichen Gießeretschlichten hergestellt werden, nicht der Fall ist. Dies reduziert die Gefahr der Beschädigung der Beschichtungen beim Reinigen mit Werkzeugen, und die mit einer solchen Beschichtung versehenen Gerätschaften und Vorrichtungen sind ohne Reparatur über längere Zeit wiederverwendbar.Furthermore, the coatings produced according to the invention are also abrasion-resistant in the cold state, which is the case with layers made from conventional foundry coatings are not the case. This reduces the risk of damage to the coatings when cleaning with tools, and the equipment and devices provided with such a coating are reusable without repair for a long time.

Weiterhin können mit den erfindungsgemäßen Schlichten dicke Schichten rissfrei hergestellt werden, wobei die mögliche Schichtdicke deutlich höher ist als bei den im Stand der Technik bekannten Beschichtungen. Die Herstellung dicker Schichten ermöglicht es auch, im Susbtrat eventuell vorhandene Risse und Oberflächenunebenheiten zu füllen und zu schließen. Ferner können durch die hohen erzielbaren Schichtdicken Defekte in den Gerätschaften und Werkzeugen gefüllt werden, ohne dass bei der anschließenden Trocknung Risse entstehen. Zudem können gegebenenfalls entstandene Risse mit den erfindungsgemäßen Schlichten versiegelt werden. Ein weiterer Vorteil solcher dicken Schichten ist deren längere Lebenszeit, da für deren Abnutzung, auch bei abrasivem Verschleiß, eine höhere Schichtdicke zur Verfügung steht.Furthermore, thick layers can be produced free of cracks with the sizes according to the invention, the possible layer thickness being significantly higher than in the case of the coatings known in the prior art. The production of thick layers also makes it possible to fill and close any cracks and asperities in the substrate. Furthermore, due to the high layer thicknesses that can be achieved, defects in the equipment and tools can be filled without causing cracks during subsequent drying. In addition, if necessary, cracks which have formed can be sealed with the sizes according to the invention. Another advantage of such thick layers is their longer lifetime, since their wear, even with abrasive wear, a higher layer thickness is available.

Zudem können die erfindungsgemäßen Schlichten auch auf unsaubere Untergründe ohne aufwendige Oberflächenvorbehandlung appliziert werden, was mit Schlichten gemäß den eingangs genannten Patentschriften nicht möglich ist.In addition, the sizes according to the invention can also be applied to unclean substrates without expensive surface pretreatment, which is not possible with sizes according to the patent specifications mentioned above.

Ein zusätzlicher überraschender Vorteil der erfindungsgemäß herstellbaren Beschichtungen besteht darin, dass durch eine Zersetzung der darin enthaltenen, wasserunlöslichen Borverbindung bei Temperaturen ab 600°C nichtoxidationsbeständige Substrate, wie beispielsweise Metall oder Graphit, effektiv vor Korrosion geschützt werden. Eine solche Zersetzung der wasserunlöslichen Borverbindung verläuft offensichtlich über den Verbrauch von Sauerstoff, so dass Sauerstoff während der Zersetzung der borhaltigen Verbindung in der Beschichtung nicht an die Susbtratoberfläche gelangen kann.An additional surprising advantage of the coatings that can be prepared according to the invention is that non-oxidation-resistant substrates, such as, for example, metal or graphite, are effectively protected from corrosion by decomposition of the water-insoluble boron compound contained therein at temperatures from 600 ° C. Such a decomposition of the water-insoluble boron compound obviously proceeds via the consumption of oxygen, so that oxygen can not reach the surface of the substrate during the decomposition of the boron-containing compound in the coating.

Kurze Beschreibung der beigefügten ZeichnungBrief description of the attached drawing

Die Abbildung 1 ist ein Diagramm aus einem Abrasionstest, bei dem die Abrasionsbeständigkeit einer Beschichtung aus einer erfindungsgemäßen Schlichte gemäß Beispiel 3 mit handelsüblichen Beschichtungen verglichen wurde.The illustration 1 is a graph of an abrasion test in which the abrasion resistance of a coating of a size according to the invention according to Example 3 was compared with commercial coatings.

Detaillierte Beschreibung der ErfindungDetailed description of the invention

Gegenstand der Erfindung ist somit eine wasserhaltige Schlichte zur Herstellung einer BN-haltigen Beschichtung auf einem Substrat, umfassend, bezogen auf den Feststoffgehalt der Schlichte,

  1. a) 45-90 Gew.-% BN,
  2. b) 3-25 Gew.-% Böhmit-Nanoteilchen,
  3. c) 0.5-5 Gew.-% mindestens eines Borats,
  4. d) 2-30 Gew.-% mindestens einer wasserunlöslichen, von den Komponenten a) und c) verschiedenen Borverbindung,
  5. e) 2-30 Gew.-% einer organischen Verbindung,
wobei der Feststoffgehalt der Schlichte 15-60 Gew.-% beträgt.The invention thus relates to a water-containing size for producing a BN-containing coating on a substrate, comprising, based on the solids content of the size,
  1. a) 45-90% by weight BN,
  2. b) 3-25 wt.% boehmite nanoparticles,
  3. c) 0.5-5% by weight of at least one borate,
  4. d) 2-30% by weight of at least one water-insoluble boron compound other than components a) and c),
  5. e) 2-30% by weight of an organic compound,
wherein the solids content of the size is 15-60 wt .-%.

Als Lösemittel bzw. Dispergiermedium für die erfindungsgemäßen wasserhaltigen Schlichten können Wasser, Alkohole, wie Ethanol, oder Wasser/Alkohol-Mischungen eingesetzt werden. Für die Anwendung als Gießereischlichte wird vorzugsweise nur Wasser eingesetzt, da für solche Anwendungen brennbare Lösungsmittel unerwünscht sind.Water or alcohols, such as ethanol, or water / alcohol mixtures can be used as the solvent or dispersion medium for the water-containing sizes according to the invention. For use as foundry glazings preferably only water is used, since for such applications combustible solvents are undesirable.

Der Feststoffgehalt der Schlichte beträgt vorzugsweise 20-40 Gew.-%, weiter vorzugsweise 25-35 Gew.-%.The solids content of the size is preferably 20-40% by weight, more preferably 25-35% by weight.

Bezogen auf den Feststoffgehalt der Schlichte betragen der BN-Gehalt vorzugsweise 45-85 Gew.-%, weiter vorzugsweise 45-75 Gew.-%, der Gehalt an Böhmit-Nanoteilchen vorzugsweise 5-20 Gew.-%, weiter vorzugsweise 10-18 Gew.-%, der Gehalt an Borat vorzugsweise 1-4 Gew.-%, weiter vorzugsweise 1-3 Gew.-%, der Gehalt der wasserunlöslichen Borverbindung vorzugsweise 5-25 Gew.-%, weiter vorzugsweise 5-20 Gew.-% und der Gehalt an einer organischen Verbindung vorzugsweise 3-20 Gew.-%, weiter vorzugsweise 3-15 Gew.-%.Based on the solids content of the size, the BN content is preferably 45-85 wt.%, More preferably 45-75 wt.%, And the content of boehmite nanoparticles is preferably 5-20 wt.%, More preferably 10-18 Wt .-%, the content of borate preferably 1-4 wt .-%, more preferably 1-3 wt .-%, the content of the water-insoluble boron compound preferably 5-25 wt .-%, more preferably 5-20 wt. % and the content of an organic compound is preferably 3-20% by weight, more preferably 3-15% by weight.

Weiterhin ist es bevorzugt, dass die erfindungsgemäße Schlichte, bezogen auf die Gesamtzusammensetzung der Schlichte, mindestens eine der folgenden Komponenten umfasst

  • f) bis zu 2 Gew.-%, vorzugsweise bis zu 1 Gew.-%, weiter vorzugsweise bis zu 0,5 Gew.-% Borsäure.
  • g) bis zu 15 Gew.-%, vorzugsweise 0,5-10 Gew.-%, insbesondere bevorzugt 1-8 Gew.-% mindestens eines aus Oxiden, Carbiden und Nitriden gewählten Hartstoffes.
  • h) bis zu 15 Gew.-%, vorzugsweise 0,5-10 Gew.-%, weiter vorzugsweise 1-8 Gew.-% mindestens eines Metallpulvers.
Furthermore, it is preferred that the size according to the invention, based on the total composition of the size, comprises at least one of the following components
  • f) up to 2 wt .-%, preferably up to 1 wt .-%, more preferably up to 0.5 wt .-% boric acid.
  • g) up to 15 wt .-%, preferably 0.5-10 wt .-%, particularly preferably 1-8% by weight of at least one hard material selected from oxides, carbides and nitrides.
  • h) up to 15% by weight, preferably 0.5-10% by weight, more preferably 1-8% by weight of at least one metal powder.

Das BN der Komponente a) wird vorzugsweise als BN-Pulver mit einer mittleren Teilchengröße von 1-30 µm, weiter vorzugsweise 2-15 µm eingesetzt. Es können auch BN-Agglomerate mit einer mittleren Agglomeratgröße von 20-100 µm, bevorzugt 20-50 µm, verwendet werden. Ebenso sind Mischungen aus beiden Formen möglich. Das eingesetzte BN kann weiterhin bis zu 10 Gew.-% verschiedener Verunreinigungen und Zusätze enthalten. Insbesondere sind zu erwähnen Borsäure, Bortrioxid, Kohlenstoff, Alkali- oder Erdalkaliborate. Es wird jedoch bevorzugt, dass möglichst reines, ausgewaschenes BN mit einer Reinheit von mindestens 98%, bevorzugt 99%, eingesetzt wird.The BN of component a) is preferably used as BN powder having an average particle size of 1-30 microns, more preferably 2-15 microns. It is also possible to use BN agglomerates having a mean agglomerate size of 20-100 μm, preferably 20-50 μm. Likewise, mixtures of both forms are possible. The BN used may further contain up to 10% by weight of various impurities and additives. In particular, mention may be made of boric acid, boron trioxide, carbon, alkali or alkaline earth borates. However, it is preferred that as pure, washed out BN with a purity of at least 98%, preferably 99%, is used.

Die in der erfindungsgemäßen Schlichte eingesetzten Böhmit-Nanoteilchen besitzen vorzugsweise eine mittlere Teilchengröße von 1-100 nm, weiter vorzugsweise 1-40 nm und insbesondere bevorzugt 2-20 nm. Es kann kommerziell erhältliches Böhmitpulver verwendet werden, beispielsweise wie von der Firma Sasol in den Qualitäten Disperal oder Dispal vertrieben, wobei vorzugsweise ein solches mit der Produktbezeichnung Disperal P2 eingesetzt wird.The boehmite nanoparticles used in the size according to the invention preferably have an average particle size of 1-100 nm, more preferably 1-40 nm and particularly preferably 2-20 nm. Commercially available boehmite powder can be used, for example as described by Sasol in US Pat Qualities Disperal or Dispal sold, preferably one with the product name Disperal P2 is used.

Das Borat c) wird vorzugsweise aus der Lithiumborat, Kaliumborat, Natriumborat, Calciumborat und Borax umfassenden Gruppe gewählt, wobei insbesondere Borax bevorzugt ist. Das Borat kann auch als herstellungsbedingte Verunreinigung im BN-Pulver enthalten sein.The borate c) is preferably selected from the group consisting of lithium borate, potassium borate, sodium borate, calcium borate and borax, borax in particular being preferred. The borate may also be present as a production-related impurity in the BN powder.

Die wasserunlösliche Borverbindung d) wird vorzugsweise aus der Borcarbid (B4C), Metallboride und elementares Bor umfassenden Gruppe gewählt. Diese Borverbindungen werden beim bestimmungsgemäßen Einsatz der Schlichten mit Luftsauerstoff zu Boroxid oxidiert, wobei insbesondere Borcarbid bevorzugt ist. Beispiele geeigneter Metallboride sind TiB2. ZrB2 und CaB6.The water-insoluble boron compound d) is preferably selected from the group consisting of boron carbide (B 4 C), metal borides and elemental boron. These boron compounds are oxidized during normal use of the sizings with atmospheric oxygen to boron oxide, in particular boron carbide is preferred. Examples of suitable metal borides are TiB 2 . ZrB 2 and CaB 6 .

Als organische Verbindung e) sind Verbindungen geeignet, welche beim bestimmungsgemäßen Einsatz der Schlichten eine flüssige bzw. viskose Phase ausbilden und bei höheren Temperaturen ausbrennen und dabei Poren zurücklassen. Solche organischen Verbindungen werden vorzugsweise aus der synthetische Polymere, wie Thermoplaste, natürliche Polymere, wie Cellulosen und Cellulose-Derivate, Wachse, Öle und Polyphosphatester umfassenden Gruppe gewählt. Ebenfalls können Wasserlacke in Form einer Suspension oder Emulsion mit feiner Dispersionsverteilung, vorzugsweise mit einer Partikel- bzw. Tropfengröße < 50 µm, eingesetzt werden. Bevorzugt sind niedrigschmelzende Verbindungen und nichtwasserlösliche Verbindungen. Wasserlösliche Verbindungen sollten nicht auskristallisieren. Insbesondere bevorzugt wird als organische Verbindung ein Polyvinylbutyral (PVB) eingesetzt.Suitable organic compounds e) are compounds which form a liquid or viscous phase when the sizings are used as intended and burn out at relatively high temperatures, leaving behind pores. Such organic compounds are preferably selected from synthetic polymers, such as thermoplastics, natural polymers, such as celluloses and cellulose derivatives, waxes, oils and polyphosphate esters group are selected. It is likewise possible to use water-based paints in the form of a suspension or emulsion having a fine dispersion distribution, preferably having a particle size or drop size of <50 μm. Preference is given to low-melting compounds and non-water-soluble compounds. Water-soluble compounds should not crystallize out. Particularly preferred as the organic compound, a polyvinyl butyral (PVB) is used.

Die wahlweise enthaltenen Hartstoffe g) werden vorzugsweise aus der Al2O3, ZrO2, TiO2 und SiC umfassenden Gruppe gewählt. Diese zusätzlichen Hartstoffe erhöhen die Abriebfestigkeit im kalten Zustand der aus den Schlichten hergestellten Beschichtungen. Obwohl unter den zuletzt genannten Stoffen TiO2 die geringste Härte aufweist, eignet es sich insbesondere beim Einsatz der Schlichte unter oxidierenden Bedingungen.The optional hard materials g) are preferably selected from the group comprising Al 2 O 3 , ZrO 2, TiO 2 and SiC. These additional hard materials increase the abrasion resistance in the cold state of the coatings produced from the sizes. Although TiO 2 has the lowest hardness among the latter substances, it is particularly suitable when using the size under oxidizing conditions.

Das wahlweise enthaltene Metallpulver h) wird vorzugsweise dann zugesetzt, wenn die erfindungsgemäßen Schlichten zur Beschichtung metallischer Substrate vorgesehen sind. Vorzugsweise werden die Metallpulver aus der Gruppe der Metalle Al, Mg, Si, Zr, Sn, Zn, Mischungen oder Legierungen daraus ausgewählt, welche in der Lage sind, Eisen aus metallischen Substraten zu lösen. Dadurch werden an der Grenzfläche zwischen Substrat und Beschichtung Mischkristalle oder intermetallische Phasen gebildet. Die Oxidationsprodukte dieser Phasen bilden einen Schutzfilm aus, so dass die Oxidationsbeständigkeit des Substrats dadurch verbessert wird. Insbesondere bevorzugt wird das Metallpulver h) aus der Gruppe der Leichtmetalle mit einem Schmelzpunkt unterhalb 800°C, besonders bevorzugt aus Al, Mg, deren Mischungen und Legierungen, ausgewählt.The optionally contained metal powder h) is preferably added when the sizes according to the invention are provided for coating metallic substrates. Preferably, the metal powders are selected from the group of metals Al, Mg, Si, Zr, Sn, Zn, mixtures or alloys thereof, which are capable of dissolving iron from metallic substrates. As a result, mixed crystals or intermetallic phases are formed at the interface between substrate and coating. The oxidation products of these phases form a protective film, thereby improving the oxidation resistance of the substrate. Particular preference is given to selecting the metal powder h) from the group of light metals having a melting point below 800 ° C., particularly preferably from Al, Mg, their mixtures and alloys.

Gegenstand der Erfindung ist ebenso ein Verfahren zur Herstellung einer erfindungsgemäßen wasserhaltigen Schlichte, umfassend die Schritte

  • i) Herstellen eines Böhmitsols in einem wässrigen Medium,
  • ii) Zugeben der restlichen Bestandteile unter gleichzeitiger Homogenisierung zur Erzielung der Schlichte.
The invention likewise provides a process for preparing a water-containing size according to the invention, comprising the steps
  • i) preparing a boehmite sol in an aqueous medium,
  • ii) adding the remaining ingredients while homogenizing to obtain the size.

Zur Herstellung des Böhmitsols können kommerziell erhältliche Böhmit-Pulverqualitäten mit Partikelgrößen im Nanometerbereich eingesetzt werden, beispielsweise die oben erwähnten, kommerziell erhältlichen Böhmitpulver der Firma Sasol. Die Böhmitpulver werden in ein wässriges Medium, vorzugsweise Wasser, eingerührt, das weiter vorzugsweise vorerwärmt wurde, vorzugsweise auf Temperaturen über 80°C. Alternativ kann die Herstellung eines Böhmitsols über Alkoxidrouten gemäß dem Yoldas-Prozess oder über die Verwendung von Aluminiumsalzen und Zugabe einer Base erfolgen. Nach der Homogenisierung wird die Dispersion üblicherweise durch Säurezugabe peptisiert und in ein Sol überführt. Geeigneterweise können Feststoffkonzentrationen im Sol von bis zu 20 Gew.-% Böhmit, vorzugsweise 5-12 Gew.-%, eingestellt werden.Commercially available boehmite powder grades with particle sizes in the nanometer range can be used to produce the boehmite sol, for example the above-mentioned, commercially available boehmite powder from Sasol. The boehmite powders are stirred into an aqueous medium, preferably water, which is more preferably preheated, preferably to temperatures above 80 ° C. Alternatively, the preparation of a boehmite sol can be via alkoxide routes according to the Yoldas process or via the use of aluminum salts and addition of a base. After homogenization, the dispersion is usually peptized by acid addition and converted into a sol. Suitably, solids concentrations in the sol of up to 20% by weight of boehmite, preferably 5-12% by weight, can be adjusted.

Das wie oben hergestellte Böhmitsol dient als Dispergiermedium, in das die restlichen Bestandteile der Schlichte durch portionierte Zugabe der Pulverkomponenten bei gleichzeitiger Homogenisierung eingebracht werden. Die Homogenisierung kann mittels üblichen Rührvorrichtungen, wie einem Blattrührer erfolgen. Vorzugsweise werden die restlichen Komponenten in der Reihenfolge 1) wasserlösliche Bestandteile, 2) feine Pulver und 3) grobe Pulver zugegeben. Für hohe Dispergierungsgrade kann die Homogenisierung in einer Kugelmühle, in einem Attritor, mit einem Ultraturrax oder mit Hilfe anderer Dispergier- oder Mahlaggregate erfolgen.The boehmite sol prepared as above serves as a dispersing medium into which the remaining constituents of the size are introduced by portioned addition of the powder components with simultaneous homogenization. The homogenization can be carried out by means of conventional stirring devices, such as a blade stirrer. Preferably, the remaining components are added in the order of 1) water-soluble ingredients, 2) fine powders, and 3) coarse powders. For high degrees of dispersion, the homogenization can be carried out in a ball mill, in an attritor, with an Ultraturrax or by means of other dispersing or milling units.

Gegenstand der Erfindung ist weiterhin ein beschichteter Körper, umfassend ein Substrat mit einer darauf aufgebrachten Beschichtung, wobei die Beschichtung aus einer erfindungsgemäßen Schlichte hergestellt worden ist.The invention furthermore relates to a coated body comprising a substrate with a coating applied thereto, wherein the coating has been produced from a size according to the invention.

Bei dem Substrat kann es sich um ein metallisches, keramisches oder anderes anorganisches (z.B. Graphit) Substrat handeln. Das Substrat kann in Form eines beliebigen Formteils oder Formkörpers, einer Folie, eines Gewebes oder einer Faser vorliegen.The substrate may be a metallic, ceramic or other inorganic (e.g., graphite) substrate. The substrate can be in the form of any shaped article or shaped article, a film, a fabric or a fiber.

Die erfindungsgemäß vorgesehene Beschichtung weist vorzugsweise eine Dicke von 5-2.000 µm, weiter vorzugsweise 15-1.000 µm, insbesondere bevorzugt 30-500 µm auf, wobei diese Schichtdicken jeweils als mittlere Schichtdicken zu verstehen sind. Die Erzielung defektfreier Beschichtungen dieser Dicke war bisher im Stand der Technik nicht möglich, insbesondere auf metallischen oder dichten Substraten. Vielmehr liegen die gemäß dem Stand der Technik defektfrei applizierten Schichtdicken üblicherweise bei 20-150 µm. Gegenstand der Erfindung ist ebenso ein Verfahren zur Herstellung eines wie oben beschriebenen beschichteten Körpers, umfassend die Schritte

  • 1) Auftragen der oben beschriebenen, erfindungsgemäßen Schlichte auf das Substrat durch ein- oder mehrmaliges Rakeln, Tauchen, Fluten, Schleudern, Sprühen, Bürsten oder Streichen,
  • 2) Trocknen der so erhaltenen Beschichtung,
  • 3) Einbrennen der Beschichtung.
The coating provided according to the invention preferably has a thickness of 5-2,000 μm, more preferably 15-1,000 μm, particularly preferably 30-500 μm, these layer thicknesses in each case being to be understood as average layer thicknesses. The achievement of defect-free coatings of this thickness has hitherto not been possible in the prior art, in particular on metallic or dense substrates. Rather, the defect-free applied according to the prior art layer thicknesses are usually 20-150 microns. The invention also provides a process for producing a coated body as described above comprising the steps
  • 1) application of the above-described inventive size to the substrate by single or multiple doctoring, dipping, flooding, spinning, spraying, brushing or brushing,
  • 2) drying the coating thus obtained,
  • 3) baking the coating.

Im obigen Schritt 1) kann die Auftragung der Schlichte bei Raumtemperatur oder bei Substrattemperaturen bis zu 300°C erfolgen. Gegebenenfalls kann das Substrat mit einem Primer vorbehandelt werden.In the above step 1), the application of the size can be carried out at room temperature or at substrate temperatures up to 300 ° C. Optionally, the substrate can be pretreated with a primer.

Die Trocknung der noch feuchten Beschichtung kann bei Raumtemperatur, vorzugsweise jedoch bei Temperaturen von 80-100°C erfolgen.The drying of the still moist coating can be carried out at room temperature, but preferably at temperatures of 80-100 ° C.

Das Einbrennen gemäß Schritt 3) kann in situ beim Einsatz des beschichteten Körpers in einer Gießereianwendung erfolgen, wobei die Wärmezufuhr entweder durch den Kontakt mit Metallschmelzen oder heißen Formteilen oder über Strahlung und/oder Konvektion erfolgt. Alternativ kann das Einbrennen aber auch vorher in einem separaten Verfahrensschritt bei Temperaturen von 180 bis 800°C erfolgen, vorzugsweise bei Temperaturen von 470°C oder darüber, insbesondere 500°C oder darüber.The firing according to step 3) can be carried out in situ when using the coated body in a foundry application, the heat being supplied either by contact with molten metals or hot moldings or by radiation and / or convection. Alternatively, however, baking can also be carried out beforehand in a separate process step at temperatures of 180 to 800 ° C., preferably at temperatures of 470 ° C. or above, in particular 500 ° C. or above.

Ohne an eine bestimmte Theorie gebunden zu sein, kann die Funktion und Wirkungsweise der einzelnen Komponenten der erfindungsgemäßen Schlichte bei Ausbildung von Beschichtungen wie folgt erklärt werden. Wie oben bereits erwähnt, sind die erfindungsgemäß erzielbaren Beschichtungen heißflexibel und selbstheilend. Dies kann dadurch erklärt werden, dass beim Durchlaufen des gesamten Temperaturbereichs von Raumtemperatur bis zur Einsatztemperatur von etwa 750°C in der Schlichte bzw. der Beschichtung immer eine flüssige oder viskose Phase zur Verfügung steht, welche dafür sorgt, dass keine Risse entstehen bzw. dass gegebenenfalls entstehende Risse wieder geschlossen werden. Durch die verschiedenen Komponenten der Schlichte ergeben sich überlappende Bereich an flüssigen bzw. viskosen Phasen: Wasser bis 100°C, dann Verflüssigung der organischen Verbindung, beispielsweise flüssiges PVB bei ca. 70-200°C, Borsäure, falls vorhanden, ab 170°C und Boroxid ab 450°C, und oberhalb 600°C wird schließlich die wasserunlösliche Borverbindung, wie B4C, zu B2O3 oxidiert. Gelöstes Borax (Na2B4O7 x 10 H2O) schmilzt bei ca. 75°C und zersetzt sich bei weiterer Temperaturerhöhung zu wasserfreiem Borax, das wiederum bei ca. 742°C schmilzt.Without being bound by any particular theory, the function and mode of action of the individual components of the size according to the invention in the formation of coatings can be explained as follows. As already mentioned above, the coatings obtainable according to the invention are hot-flexible and self-healing. This can be explained by the fact that when passing through the entire temperature range from room temperature to the use temperature of about 750 ° C in the sizing or the coating always a liquid or viscous phase is available, which ensures that no cracks or if necessary, cracks are closed again. The various components of the size result in overlapping areas of liquid or viscous phases: water up to 100 ° C., then liquefaction of the organic compound, for example liquid PVB at about 70-200 ° C., boric acid, if present, from 170 ° C. and boron oxide from 450 ° C., and above 600 ° C., finally, the water-insoluble boron compound, as B 4 C, oxidized to B 2 O 3 . Dissolved borax (Na2B 4 O 7 x 10 H 2 O) melts at about 75 ° C and decomposes on further increase in temperature to anhydrous borax, which in turn melts at about 742 ° C.

Gemäß der Erfindung hat sich ebenfalls gezeigt, dass beim Austausch der oben erwähnten wasserunlöslichen Borverbindung d), insbesondere B4C, durch einen entsprechenden Anteil an B2O3 oder auch an Borsäure, das B2O3 in der Beschichtung auskristallisiert und es zu einem Abplatzen der Beschichtung kommt. Wird jedoch erfindungsgemäß die wasserunlösliche Borverbindung, insbesondere B4C, zugesetzt, entsteht zwar offensichtlich ebenfalls B2O3 als Oxidationsprodukt, aber es kommt überraschenderweise nicht zum unerwünschten Effekt des Auskristallisterens und des Abplatzens der Schicht. Dies war für einen Fachmann nicht vorhersehbar.According to the invention, it has also been found that when replacing the above-mentioned water-insoluble boron compound d), in particular B 4 C, by a corresponding amount of B 2 O 3 or boric acid, the B 2 O 3 crystallized in the coating and it a spalling of the coating comes. However, if according to the invention the water-insoluble boron compound, in particular B 4 C, is added, it is obvious that B 2 O 3 also forms as the oxidation product, but surprisingly there is no undesired effect of the crystallizing agent and the spalling of the layer. This was unpredictable for a person skilled in the art.

Aufgrund der oben beschriebenen Vorteile und Eigenschaften eignet sich ein erfindungsgemäß beschichteter Körper insbesondere auf dem Gebiet der Gießereianwendungen, insbesondere Leichmetallgießereianwendungen. Beispielsweise handelt es sich hierbei bei dem beschichteten Körper um einen Gießtisch, eine Gießrinne oder einen Behälter zum Warmhalten oder Transportieren von Metallschmelzen.Due to the advantages and properties described above, a body coated according to the invention is particularly suitable in the field of foundry applications, in particular light-metal foundry applications. By way of example, the coated body is a casting table, a runner or a container for holding or transporting molten metal.

Die erfindungsgemäßen Schlichten können weiterhin bei einem inversen Beschichtungsverfahren eingesetzt werden. Hierbei wird unter Verwendung einer erfindungsgemäßen Schlichte eine Beschichtung auf eine Sandform aufgebracht. In der so beschichteten Form erfolgt dann ein Metallabguss, vorzugsweise eines Metalls mit einem Schmelzpunkt > 1200°C, wobei die Sandform anschließend entfernt wird. Durch ein solches Verfahren kann ein metallischer Gegenstand, beispielsweise ein Gießlöffel, erhalten werden, der bereits mit einer in situ eingebrannten erfindungsgemäßen Beschichtung versehen ist.The sizes according to the invention can furthermore be used in an inverse coating process. Here, a coating is applied to a sand mold using a sizing invention. In the thus coated form is then a metal casting, preferably a metal having a melting point> 1200 ° C, the sand mold is then removed. By such a method, a metallic object, for example a ladle, can be obtained, which is already provided with a coating baked in situ according to the invention.

Die nachfolgenden Beispiele erläutern die Erfindung.The following examples illustrate the invention.

Beispiel 1:Example 1: Böhmitsolherstellung über die Pulverroute:Boehmitsol production via the powder route:

400 ml Wasser werden auf 85-95°C aufgeheizt. Es folgt unter starkem Rühren die Zugabe von 34g nanoskaligem Böhmitpulver. Die Homogenisierung wird unter starkem Rühren innerhalb von 10 Minuten durchgeführt. Die Suspension wird bei Prozesstemperatur mit 6ml konzentrierter Salpetersäure peptisiert. Ein Alterungsschritt wird nicht durchgeführt. Während der Synthese konzentriert sich das Sol auf. Das Sol wird durch Zugabe von Wasser auf einen Böhmitfeststoffgehalt von 7.1 Gew.-% verdünnt.400 ml of water are heated to 85-95 ° C. This is followed by the addition of 34 g of nanoscale boehmite powder with vigorous stirring. The homogenization is carried out with vigorous stirring within 10 minutes. The suspension is peptized at process temperature with 6 ml of concentrated nitric acid. An aging step is not performed. During synthesis, the sol concentrates. The sol is diluted by addition of water to a boehmite solids content of 7.1% by weight.

Beispiel 2:Example 2: Böhmitsolherstellung über die Precursorroute (Alkoxide):Boehmitsol production via the precursor route (alkoxides):

500 ml Wasser mit einer Temperatur von 85-100°C werden vorgelegt. Der pH-Wert im Wasser wird mit Salpetersäure bereits vor der Synthese auf einen Wert von unter 1 eingestellt. Anschließend erfolgt die Zugabe von 98g Aluminiumisopropoxid. Auf Siedetemperatur des Sols wird das Volumen des Sols rasch auf 3/5 reduziert. Bei der zweiten Säurezugabe wird das Sol mit 10ml konzentrierter Salpetersäure peptisiert, gefolgt von einer raschen Abkühlung des Sols. Das Sol wird durch Zugabe von Wasser auf einen Böhmitfeststoffgehalt von 7.1 Gew.-% verdünnt. Ein Alterungsschritt wird nicht durchgeführt.500 ml of water at a temperature of 85-100 ° C are presented. The pH in the water is adjusted to a value of less than 1 with nitric acid even before the synthesis. This is followed by the addition of 98 g of aluminum isopropoxide. At the boiling temperature of the sol, the volume of the sol is rapidly reduced to 3/5. The second addition of acid solutes the sol with 10 ml of concentrated nitric acid, followed by rapid cooling of the sol. The sol is diluted by addition of water to a boehmite solids content of 7.1% by weight. An aging step is not performed.

Beispiel 3:Example 3: Herstellung einer Schlichte:Preparation of a size:

108.3g Sol aus Beispiel 1 oder Beispiel 2 mit einem Feststoffgehalt an Böhmit von 7,1 Gew.% (entsprechend einem Gehalt von 8,3 g hydratisiertem Böhmitpulver Disperal P2 oder entsprechend 6 g resultierendem Al2O3-Gehalt) wird als Dispergiermedium vorgelegt. Die pulvrigen Komponenten der Suspension werden unter Verwendung eines Ultraturrax im Sol homogenisiert. Es werden separat voneinander 1g Borsäure, 1g Borax, 4g Borcarbid mit einer mittleren Partikelgröße von 1 µm, 30g Bornitrid mit einer mittleren Partikelgröße von 4 µm und 3,3g Polyvinylbutyral bei laufendem Dispergieraggregat portionsweise zudosiert.108.3 g of the sol of Example 1 or Example 2 having a solids content of boehmite of 7.1% by weight (corresponding to a content of 8.8 g of hydrated boehmite powder Disperal P2 or corresponding to 6 g of resulting Al 2 O 3 content) is initially charged as dispersing medium , The powdery components of the suspension are homogenized in the sol using an Ultraturrax. 1g boric acid, 1g borax, 4g boron carbide with an average particle size of 1 μm, 30g boron nitride with an average particle size of 4 μm and 3.3 g of polyvinyl butyral are added in portions while the dispersing unit is running.

Beispiel 4:Example 4: Herstellung einer Schlichte:Preparation of a size:

108,3g Sol aus Beispiel 1 oder Beispiel 2 mit einem Feststoffgehalt an Böhmit von 7.1 Gew.% (entsprechend einem Gehalt von 8,3 g hydratisiertem Böhmitpulver Disperal P2 oder entsprechend 6 g resultierendem Al2O3-Gehalt) wird als Dispergiermedium vorgelegt. Die pulvrigen Komponenten der Suspension werden unter Verwendung eines Ultraturrax im Sol homogenisiert. Es werden separat voneinander 1g Borax, 2g Borcarbid mit einer mittleren Partikelgröße von 1 µm, 2g Titandiborid mit einer mittleren Partikelgröße von 4,5 µm, 30g Bornitrid mit einer mittleren Partikelgröße von 4 µm, 1g Aluminiumoxid und 2g Polyvinylbutyral bei laufendem Dispergieraggregat portionsweise zudosiert.108.3 g of the sol from Example 1 or Example 2 having a solids content of boehmite of 7.1% by weight (corresponding to a content of 8.8 g of hydrated boehmite powder Disperal P2 or corresponding to 6 g of resulting Al 2 O 3 content) is initially charged as dispersing medium. The powdery components of the suspension are homogenized in the sol using an Ultraturrax. Separately, 1 g of borax, 2 g of boron carbide having an average particle size of 1 μm, 2 g of titanium diboride having an average particle size of 4.5 μm, 30 g of boron nitride having an average particle size of 4 μm, 1 g of aluminum oxide and 2 g of polyvinyl butyral are added in portions while the dispersing unit is running.

Beispiel 5:Example 5: Herstellung einer Schlichte:Preparation of a size:

108,3g Sol aus Beispiel 1 oder Beispiel 2 mit einem Feststoffgehalt an Böhmit von 7.1 Gew.% (entsprechend einem Gehalt von 8,3 g hydratisiertem Böhmitpulver Disperal P2 oder entsprechend 6 g resultierendem Al2O3-Gehalt) wird als Dispergiermedium vorgelegt. Die pulvrigen Komponenten der Suspension werden unter Verwendung eines Ultraturrax im Sol homogenisiert. Es werden separat voneinander 0,5g Borax, 1g Borcarbid mit einer mittleren Partikelgröße von 1 µm, 30g Bornitrid mit einer mittleren Partikelgröße von 4 µm und 1g Polyvinylbutyral bei laufendem Dispergieraggregat portionsweise zudosiert. 2g Aluminiumpulver (Standard-Al-Pulver PCS, Eckert-Werke) werden anschließend mit einem Blattrührer eingerührt.108.3 g of the sol from Example 1 or Example 2 having a solids content of boehmite of 7.1% by weight (corresponding to a content of 8.8 g of hydrated boehmite powder Disperal P2 or corresponding to 6 g of resulting Al 2 O 3 content) is initially charged as dispersing medium. The powdery components of the suspension are homogenized in the sol using an Ultraturrax. Separately, 0.5 g of borax, 1 g of boron carbide having an average particle size of 1 μm, 30 g of boron nitride having an average particle size of 4 μm and 1 g of polyvinyl butyral are added in portions while the dispersing unit is running. 2 g of aluminum powder (standard Al powder PCS, Eckert-Werke) are then stirred in with a paddle stirrer.

VergleichsbeispieleComparative Examples 1. Abrasionstest (Taber Abraser-Untersuchungen) an erfindungsgemäßer Beschichtung und Vergleichsbeschichtungen1. Abrasion test (Taber abraser investigations) on inventive coating and comparative coatings

Für vergleichende Untersuchungen der Abrasionsbeständigkeit der Beschichtungen wurden als Substrat plangeschliffene Scheiben aus Warmarbeitsstahl 1.2343 (X38CrMoV5-1) verwendet. Die BN-Suspensionen (erfindungsgemäße Schlichte nach Beispiel 3, handelsübliche Schlichten mit Aluminiumoxid-Binder, Typ1 und Typ2, sowie mit Magnestumsilikat-Binder) wurden per Sprühen appliziert, bei 90°C eine halbe Stunde getrocknet und bei 750°C eine halbe Stunde eingebrannt.For comparative investigations of the abrasion resistance of the coatings, flat-ground disks of hot-work steel 1.2343 (X38CrMoV5-1) were used as the substrate. The BN suspensions (inventive size according to Example 3, commercial sizes with alumina binder, Type 1 and Type 2, and with Magnestumsilikat binder) were applied by spraying, dried at 90 ° C for half an hour and baked at 750 ° C for half an hour ,

Nach dem Einbrennen wurden die beschichteten Platten auf Raumtemperatur abgekühlt und in einem Taber Abraser-Test, 3N, Reibrollen AT20D1-CS110F, untersucht.After baking, the coated panels were cooled to room temperature and tested in a Taber Abraser Test, 3N, Friction Rolls AT20D1-CS110F.

Für die Untersuchungen wurde ein Gerät der Fa.

  • TABER® INDUSTRIES
  • 455 Bryant Street
  • North Tonawanda, New York 14120
  • USA
verwendet. Die Reibrollen AT20D1 - CS-110F wurden vor jedem Test gereinigt. Das Ergebnis der Untersuchungen ist in Abb. 1 dargestellt. Die BN-Schlichte mit den geringsten Abtragsraten im Test ist die erfindungsgemäße Schlichte aus Beispiel 3. Nach 100 Umdrehungen ist bei den Vergleichsschlichten bereits fast die komplette ursprünglich 50 bis 90 µm dicke Beschichtung abgetragen, während bei der erfindungsgemäßen Schlichte aus Beispiel 3 die Beschichtung nur sehr langsam abgetragen wird und auch nach 500 Umdrehungen noch eine über 40 µm dicke Beschichtung erhalten ist.For the investigations, a device of Fa.
  • TABER® INDUSTRIES
  • 455 Bryant Street
  • North Tonawanda, New York 14120
  • USA
used. The friction rollers AT20D1 - CS-110F were cleaned before each test. The result of the investigations is in Fig. 1 shown. The BN size with the lowest removal rates in the test is the size of Example 3 according to the invention. After 100 revolutions, almost the complete originally 50 to 90 .mu.m thick coating has already been removed from the comparative sizes, whereas in the case of the size of Example 3 according to the invention the coating is only very high is slowly removed and even after 500 revolutions still more than 40 microns thick coating is obtained.

2. Gitterschnitttest an erfindungsggemäßer Beschichtung und Vergleichsbeschichtungen2. Cross-hatch test on erfindungsggemäßer coating and comparative coatings

Für vergleichende Untersuchungen der Haftfestigkeit der Beschichtungen wurden Gitterschnitttests nach DIN EN ISO 2409 auf plangeschliffenen beschichteten Scheiben aus Warmarbeitsstahl (1.2343 X38CrMoV5-1) durchgeführt. Die Applikation sowie Trocknung und Einbrennen der Beschichtungen erfolgte wie unter 1. beschrieben.For comparative investigations of the adhesion of the coatings, cross-cut tests according to DIN EN ISO 2409 were carried out on flat-ground coated disks of hot-work steel (1.2343 X38CrMoV5-1). The application and drying and baking of the coatings took place as described under 1. above.

Das Ergebnis der Untersuchungen ist in Tabelle 1 dargestellt. Tabelle 1: Ergebnisse des Gitterschnitttests für unterschiedliche BN-Beschichtungen Erfindungsgemäße Beschichtung (Beispiel 3) Al2O3-Binder (Typ 1) Al2O3-Binder (Typ 2) Magnesium-silikat-Binder GT-Wert 0 1 5 5 The result of the investigations is shown in Table 1. Table 1: Cross hatch test results for different BN coatings Inventive coating (Example 3) Al 2 O 3 binder (type 1) Al 2 O 3 binder (Type 2) Magnesium silicate binder GT value 0 1 5 5

Nach DIN EN ISO 2409 entspricht ein GT-Wert von 0 der besten ermittelbaren Haftfestigkeit. Die erfindungsgemäße Beschichtung nach Beispiel 3 hat den besten Wert erreicht. In Tabelle 2 sind die ermittelbaren GT-Werte zusammengefasst. Tabelle 2: Zuordnung von GT-Werte GT-Werte Beschreibung (Kurzfassung) 0 keine Abplatzungen 1 ca. 5% Abplatzungen 2 ca. 15% Abplatzungen 3 ca. 35% Abplatzungen 4 ca. 65% Abplatzungen 5 > 65% Abplatzungen According to DIN EN ISO 2409, a GT value of 0 corresponds to the best detectable adhesive strength. The coating according to the invention according to Example 3 has reached the best value. Table 2 summarizes the GT values that can be determined. Table 2: Assignment of GT values GT values Description (short version) 0 no flaking 1 about 5% flaking 2 about 15% flaking 3 about 35% flaking 4 about 65% flaking 5 > 65% flaking

Claims (19)

  1. A water-containing slip for producing a BN-containing coating on a substrate, which comprises, based on the solids content of the slip,
    a) 45-90% by weight, preferably 45-85% by weight, more preferably 45-75% by weight of BN,
    b) 3-25% by weight, preferably 5-20% by weight, more preferably 10-18% by weight of boehmite nanoparticles,
    c) 0.5-5% by weight, preferably 1-4% by weight, more preferably 1-3% by weight of at least one borate,
    d) 2-30% by weight, preferably 5-25% by weight, more preferably 5-20% by weight of at least one water-insoluble boron compound which is different from the components a) and c),
    e) 2-30% by weight, preferably 3-20% by weight, more preferably 3-15% by weight of an organic compound,
    where the solids content of the slip is 15-60% by weight, preferably 20-40% by weight, more preferably 25-35% by weight.
  2. The slip as claimed in claim 1, which further comprises, based on the total composition of the slip, at least one of the following components
    f) up to 2% by weight, preferably up to 1% by weight, more preferably up to 0.5% by weight of boric acid,
    g) up to 15% by weight, preferably 0.5-10% by weight, more preferably 1-8% by weight of at least one hard material selected from among oxides, carbides and nitrides,
    h) up to 15% by weight, preferably 0.5-10% by weight, more preferably 1-8% by weight of at least one metal powder.
  3. The slip as claimed in at least one of the preceding claims, wherein the borate c) is selected from the group consisting of lithium borate, potassium borate, sodium borate, calcium borate and borax.
  4. The slip as claimed in at least one of the preceding claims, wherein the water-insoluble boron compound d) is selected from the group consisting of boron carbide, metal borides and elemental boron.
  5. The slip as claimed in at least one of the preceding claims, wherein the organic compound e) is selected from the group consisting of synthetic polymers, natural polymers, waxes, oils and phosphate esters.
  6. The slip as claimed in at least one of the preceding claims, wherein the organic compound e) is a polyvinyl butyral.
  7. The slip as claimed in at least one of the preceding claims, wherein the BN of component a) is a BN powder having an average particle size of 1-30 µm, preferably 2-15 µm.
  8. The slip as claimed in at least one of the preceding claims, wherein the boehmite nanoparticles b) have an average particle size of 1-100 nm, preferably 1-40 nm, particularly preferably 2-20 nm.
  9. The slip as claimed in at least one of claims 2-8, wherein the hard materials g) are selected from the group consisting of Al2O3, ZrO2, TiO2 and SiC.
  10. The slip as claimed in at least one of claims 2-9, wherein the metal powder h) is selected from the group of the metals Al, Mg, Si, Zr, Sn, Zn, their mixtures and their alloys, preferably from the group of light metals having a melting point below 800°C, particularly preferably Al, Mg, their mixtures and alloys.
  11. A process for producing a water-containing slip as claimed in at least one of claims 1-10, which comprises the steps
    i) production of a boehmite sol in an aqueous medium,
    ii) addition of the remaining constituents with simultaneous homogenization to produce the slip.
  12. A coated body comprising a substrate, wherein the substrate is preferably selected from among metallic, ceramic or other inorganic substrates, having a coating applied thereto, wherein the coating has been produced from a slip as claimed in at least one of claims 1-10.
  13. The coated body as claimed in claim 12, wherein the substrate is present in the form of a shaped part, a film, a woven fabric or a fiber.
  14. The coated body as claimed in at least one of claims 12-13, wherein the coating has a thickness of 5-2000 µm, preferably 15-1000 µm, more preferably 30-500 µm.
  15. A process for producing a coated body as claimed in at least one of claims 12-14, which comprises the steps
    1) application of the slip as claimed in at least one of claims 1-10 to the substrate by one or more doctor blade coating, dipping, flooding, spin coating, spraying, brushing or painting steps,
    2) drying of the coating obtained in this way,
    3) baking of the coating.
  16. The process as claimed in claim 15, wherein the baking in step 3) is effected in situ during use of the coated body in a foundry application.
  17. The process as claimed in claim 15, wherein the baking in step 3) is carried out at elevated temperatures before use of the coated body.
  18. The process as claimed in claim 15 and/or 17, wherein the baking in step 3) is carried out at temperatures of from 180 to 800°C.
  19. The use of a coated body as claimed in at least one of claims 12-14 in the field of foundry applications, in particular light metal foundry applications, wherein the coated body is preferably a mold frame, a pouring spout or a container for keeping metal melts hot.
EP20070801637 2006-09-01 2007-08-13 Size for production of a bn-containing coating, method for production thereof coated body production and use thereof Not-in-force EP2057107B1 (en)

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DE200610041047 DE102006041047A1 (en) 2006-09-01 2006-09-01 Sizing for the preparation of a BN-containing coating, process for its preparation, coated body, its preparation and its use
PCT/EP2007/007153 WO2008025448A1 (en) 2006-09-01 2007-08-13 Size for production of a bn-containing coating, method for production thereof coated body production and use thereof

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DE102005050593A1 (en) 2005-10-21 2007-04-26 Esk Ceramics Gmbh & Co. Kg Skim coat for making a durable hard coating on substrates, e.g. crucibles for melt-processing silicon, comprises silicon nitride particles and a binder consisting of solid nano-particles made by a sol-gel process
DE102007053284A1 (en) * 2007-11-08 2009-05-20 Esk Ceramics Gmbh & Co. Kg Firmly adhering silicon nitride-containing separating layer
DE102011078066A1 (en) * 2011-06-24 2012-12-27 Oskar Frech Gmbh + Co. Kg Casting component and method for applying a corrosion protection layer
KR20140050740A (en) * 2011-09-28 2014-04-29 도요타 지도샤（주） Member for casting, casting method, and method for producing lubricant used therefor
CN105567075B (en) * 2016-02-04 2018-07-24 宁波格莱美厨具有限公司 A kind of non-stick pan antibacterial hybrid coating and preparation method thereof
CN110177652A (en) * 2016-12-23 2019-08-27 圣戈班磨料磨具股份有限公司 Coated abrasives with performance enhancement package
CN113178545A (en) * 2021-04-23 2021-07-27 中南大学 Structure of lithium metal/nano h-BN powder film layer and preparation method and application thereof

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ATE515487T1 (en) 2011-07-15

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