EP4061556A1 - Noyaux pour moulage sous pression - Google Patents

Noyaux pour moulage sous pression

Info

Publication number
EP4061556A1
EP4061556A1 EP20808386.5A EP20808386A EP4061556A1 EP 4061556 A1 EP4061556 A1 EP 4061556A1 EP 20808386 A EP20808386 A EP 20808386A EP 4061556 A1 EP4061556 A1 EP 4061556A1
Authority
EP
European Patent Office
Prior art keywords
group
component
core
refractory materials
particulate
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.)
Pending
Application number
EP20808386.5A
Other languages
German (de)
English (en)
Inventor
Sabrina Maria Sachau
Maria SCHWEINEFUSS
Christian LUSTIG
Klaus Seeger
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.)
Huettenes Albertus Chemische Werke GmbH
Original Assignee
Huettenes Albertus Chemische Werke GmbH
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 Huettenes Albertus Chemische Werke GmbH filed Critical Huettenes Albertus Chemische Werke GmbH
Publication of EP4061556A1 publication Critical patent/EP4061556A1/fr
Pending legal-status Critical Current

Links

Classifications

    • 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
    • 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
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
    • B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
    • B22C1/186—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents contaming ammonium or metal silicates, silica sols
    • B22C1/188—Alkali metal silicates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/10—Cores; Manufacture or installation of cores
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/022—Carbon
    • C04B14/024—Graphite
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/04—Silica-rich materials; Silicates
    • C04B14/046—Zircon
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/04—Silica-rich materials; Silicates
    • C04B14/06—Quartz; Sand
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B14/02—Granular materials, e.g. microballoons
    • C04B14/04—Silica-rich materials; Silicates
    • C04B14/10—Clay
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/24—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/24—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
    • C04B28/26—Silicates of the alkali metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
    • C04B2103/0068—Ingredients with a function or property not provided for elsewhere in C04B2103/00
    • C04B2103/0093—Organic cosolvents
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00482—Coating or impregnation materials
    • C04B2111/00551—Refractory coatings, e.g. for tamping
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/0087—Uses not provided for elsewhere in C04B2111/00 for metallurgical applications

Definitions

  • the present invention relates to the use of a sizing composition for producing cores for die casting, a kit for producing cores for die casting, a method for producing cores for die casting, cores suitable for use in die casting, and the use of such cores Cores in die casting, especially in the die casting of light metals. Further details of the invention emerge from the attached patent claims as well as the following description and the exemplary embodiments.
  • cores are inserted into the casting mold in order to keep the corresponding areas of the mold free from the molten metal.
  • Die-casting or die-casting is to be understood as an industrial casting process in which, for series and mass production of cast parts, a metal melt under high pressure (10 MPa to 200 MPa) and at a high mold filling speed (up to 12 m / s) is converted into a two-part or multi-part Permanent form is introduced where it solidifies.
  • Low-melting metals such as aluminum and magnesium and alloys containing aluminum and / or magnesium are particularly suitable for die casting.
  • WO 2011/151420 A1 discloses cores based on salt (eg sodium chloride), which can be produced by shaping and compacting a core material mixture consisting of at least one salt, at least one binder (eg water glass) and optionally auxiliaries such as additives, wetting agents and catalysts , whereby the salt, the binding agent and the optionally used auxiliaries are inorganic, these core materials are soluble with water as solvent, the parts are shaped and compacted by core shooting or pressing and the compacted cores are stabilized by an infiltrate.
  • the cores can also be given a size.
  • salt cores are relatively complex, however, and their use is associated with some disadvantages, such as high weight, brittleness and poor storage stability due to the hygroscopicity of water-soluble salts.
  • a solution is created which has to be dried in order to recover the salt or which has to be disposed of.
  • US 2018/0318912 A1 discloses a core for use in die casting of aluminum, the core comprising a combination of a synthetic ceramic molding base material, an inorganic binder containing sodium silicate and an additive containing particulate amorphous silicon dioxide.
  • the core can have a coating of size, which is intended to prevent molten aluminum from penetrating through the surface into the core during the die-casting.
  • Zirconium oxide and aluminum oxide, which are to be used in the form of fine powders, are named as suitable refractory materials for the size.
  • WO 2013/044904 A1 discloses containing a size composition
  • (A3) 1 to 20 parts by weight of sodium bentonite, based on the ratio of the components (A1), (A2) and (A3) relative to one another, and
  • the total clay content A1, A2 and A3 of the size together is preferably 0.1% by weight to 4.0% by weight, based on the solids content of the size composition.
  • the refractory materials (C) are preferably quartz, aluminum oxide, zirconium dioxide, aluminum silicates, zircon sands, zirconium silicates, olivine, talc, mica, graphite, coke, feldspar, diatomite, kaolins, calcined kaolins, kaolinite, metakaolinite, iron oxide, bauxite and / or mixtures thereof . If the size composition is used as a concentrate, the proportion of refractory material (C) in the size composition is greater than 70% by weight, preferably greater than 80% by weight, based in each case on the solids content of the size composition.
  • DE 102005041 863 A1 discloses a molding compound for the production of casting molds for the foundry industry, at least comprising a refractory molding material, a binder for curing the molding compound and a portion of a borosilicate glass.
  • DE 10 2014 004 914 A1 discloses a casting mold and a casting mold core made of molding sand for metal casting, a first layer being arranged on the surface of molding sand grains of the molding sand, the first layer being hardened and consisting of water glass and / or phosphate glass.
  • WO 2013/044904 A1 DE 102005041 863 A1 and DE 102014004914 A1 do not relate to the technical field of die casting.
  • a first aspect of the invention relates to a kit for producing cores for use in die casting.
  • the kit according to the invention contains as separate components
  • compositions for making a coating comprising (D1) a carrier liquid selected from the group consisting of water and mixtures of water with one or more alcohols
  • R1 and R2 are each monovalent groups which, independently of one another, each contain 1 to 26 carbon atoms, the group R1 via a carbon atom contained in the group R1 or via an oxygen atom contained in the group R1, and the group R2 via a carbon atom contained in the group R2 is attached, or are linked to one another to form a ring structure that the ring structure comprises a total of 4 to 7 ring atoms and the groups R1 and R2 comprise a total of 2 to 26 carbon atoms, the group R1 having one in the Group R1 is bonded via a carbon atom contained in group R1 or via an oxygen atom contained in group R1, and the group R2 is bonded via a carbon atom contained in group R2;
  • (D4) one or more refractory materials in the form of granular particles, the proportion of refractory materials (D3) being in the range from 15% to 80%, preferably 30% to 60%, based on the total mass of refractory materials (D3) and refractory materials (D4 ) in component (D).
  • the components (A), (B), (C) and (D) are present separately, that is to say spatially separated from one another, for example each of the components (A), (B), (C) and (D) in a separate container.
  • Components (A), (B) and (C) of the kit according to the invention are used to produce a molding material mixture from which a base body for a core is produced by molding and thermal curing.
  • Component (D) of the kit according to the invention is a size composition or a concentrate for producing a size composition.
  • the size composition is a coating composition and is used to produce a coating (size coating) on the base body which extends at least over the entire surface of the core that comes into contact with a molten metal during the casting process.
  • the coating preferably extends over the entire surface of the core.
  • Component (A) of the kit according to the invention represents the basic molding material of the molding material mixture to be produced from components (A), (B) and (C) of the kit.
  • Fine-grained molding materials in particular with an AFS grain size number in the range from 50 to 100, are preferred , particularly preferably with an AFS grain fineness number in the range from 60 to 80.
  • the AFS grain fineness number is determined according to the VDG leaflet (leaflet of the "Association of German Foundry Experts") P 34 of October 1999, point 5.2. There the AFS grit fineness number is given by the formula
  • M3i is the AFS multiplier for the respective grain class (according to table 3 of VDG leaflet P34), and
  • Mold base materials to be used according to the invention are selected from the group consisting of quartz sand, chrome ore sand, olivine sand, aluminum-silicate sands and mixtures thereof.
  • the basic molding material (A) is preferably quartz sand.
  • a particularly preferred basic molding material is quartz sand with an AFS grain fineness number in the range from 50 to 100, particularly preferably with an AFS grain fineness number in the range from 60 to 80.
  • Components (B) and (C) of the kit according to the invention form the binding agent of the molding material mixture to be produced from components (A), (B) and (C) of the kit.
  • the amorphous particulate silicon dioxide in component (B) is preferably selected from the group consisting of particulate synthetic amorphous silicon dioxide, which has at least carbon as a minor component, the proportion of silicon dioxide being 90% or more, based on the total mass of the particulate synthetic amorphous silicon dioxide and the secondary components, preferably producible by reducing quartz in an electric arc furnace; particulate synthetic amorphous silicon dioxide, which has oxides of zirconium as a secondary component, preferably producible by thermal decomposition of ZrSiÜ4; particulate synthetic amorphous silicon dioxide producible by oxidation of metallic silicon by means of an oxygen-containing gas; particulate synthetic amorphous silicon dioxide producible by quenching a silicon dioxide melt; Pyrogenic silica, preferably producible by pyrolysis of silicon tetrachloride; and mixtures thereof.
  • pill refers to a solid powder (including dust) or a granulate that is preferably free-flowing and can therefore also be sieved.
  • the particulate amorphous silicon dioxide is preferably produced synthetically.
  • Synthetically produced particulate amorphous silicon dioxide means in the context of the present text that the amorphous silicon dioxide is the target product of a scheduled chemical reaction process for the technical synthesis of particulate amorphous silicon dioxide or is a by-product of a scheduled chemical reaction process for the technical synthesis of a target product that is not particulate amorphous silicon dioxide.
  • reaction process with the target product particulate amorphous silicon dioxide is the flame hydrolysis of silicon tetrachloride.
  • the particulate amorphous S1O2 (“silicon dioxide”) produced using this process is also referred to as “pyrogenic S1O2” (“pyrogenic silicon dioxide”) or as fumed silica or “fumed silica” (CAS RN 112945-52-5).
  • particulate amorphous silicon dioxide is formed as a by-product is the reduction of quartz with e.g. B. coke in the electric arc furnace for the production of silicon or ferrosilicon as the target product.
  • the particulate amorphous S1O2 (“silicon dioxide”) formed is also referred to as silica dust, silicon dioxide dust or Si0 2 smoke condensate, “silica fume” or microsilica (CAS RN 69012-64-2).
  • Particulate amorphous silicon dioxide can also be obtained by oxidizing metallic silicon by means of an oxygen-containing gas (for details see DE 102012 020 510 A1) and by quenching a silicon dioxide melt.
  • Particulate, amorphous silicon dioxide of the type produced by reducing quartz with carbon (e.g. coke) in an electric arc (in the production of ferrosilicon and silicon) has carbon as a minor constituent due to its production, the proportion being Silica is 90% or more based on the total mass of the particulate synthetic amorphous silica and the minor components.
  • Particulate, amorphous silicon dioxide of the type produced by the thermal decomposition of ZrSiC has oxides of zirconium, in particular zirconium dioxide, as a secondary constituent for production reasons.
  • Particulate synthetic amorphous silicon dioxide which can be produced by oxidation of metallic silicon by means of an oxygen-containing gas
  • particulate synthetic amorphous silicon dioxide which can be produced by quenching a silicon dioxide melt
  • S1O2 is very pure S1O2 with only very few unavoidable (i.e. production-related) impurities.
  • Particulate, amorphous silicon dioxide to be used with particular preference in the context of the present invention comprises those types of particulate, amorphous silicon dioxide which are referred to with the CAS RN 69012-64-2 or with the CAS RN 112945-52-5. These are available as indicated above.
  • the "CAS RN” stands for the CAS registration number and CAS registration number.
  • CAS Registry Number, CAS Chemical Abstracts Service.
  • the S1O2 produced by thermal decomposition of ZrSiÜ 4 to Z1 ⁇ 2 from ZrSiÜ 4 and the S1O2 obtained by flame hydrolysis of silicon tetrachloride.
  • This determination of the particle size distribution by means of laser scattering is based on the relationship between the size of a particle on the one hand and the angle and the intensity of the light scattered by this particle on the other hand. From the measured angles and intensities of the laser radiation that is scattered by the particles contained in the sample, information about the particle sizes can be obtained by means of an algorithm based on the Mie scattering theory.
  • component (B) of the kit according to the invention consists of amorphous particulate silicon dioxide.
  • component (B) is a powdery additive mixture containing particulate amorphous silicon dioxide and other constituents. These further constituents are, for example, particulate inorganic materials (for details see below), alkali metal hydroxides
  • Organosilicon compounds such as silanes, silicones and siloxanes
  • the carbohydrates are preferably selected from
  • particulate inorganic materials are also additives, the addition of which to molding mixtures with waterglass as a binder is known to the person skilled in the art from the prior art.
  • Particulate inorganic materials are preferably selected from the group consisting of
  • Aluminum oxide preferably in the alpha phase; Bauxite; Aluminum / silicon mixed oxides; - Oxides of zirconium, preferably zirconium (IV) oxide;
  • component (B) of the kit according to the invention is a powdery additive mixture containing particulate amorphous silicon dioxide, the total concentration of particulate amorphous silicon dioxide being preferably 25% to 99.5%, particularly preferably 40% to 95%, based on the total mass of the powdery Additive mixture (B) and one or more oxidic boron compounds, preferably selected from the group consisting of borates, boric acids, boric acid anhydrides, borosilicates, borophosphates and borophosphosilicates, the total concentration of oxidic boron compounds preferably 0.5% to 8%, particularly preferably 2 % to 5%, based on the total mass of the powdery additive mixture (B).
  • Oxidic boron compounds in component (B) improve the resistance of the moldings produced from the molding mixture to water and atmospheric moisture.
  • a high resistance to water is important so that the molding is not attacked significantly by the water contained in the carrier liquid (D1) when the coating composition (D) is applied.
  • a high resistance to atmospheric moisture improves the storage stability of the shaped bodies.
  • Component (C) of the kit according to the invention is either a solution or dispersion comprising water glass, or a kit comprising raw materials for producing a solution or dispersion comprising water glass.
  • Water glass is understood to mean alkali metal silicates, which can be obtained, for example, by melting quartz sand with sodium carbonate or potassium carbonate at 1400 ° C to 1500 ° C, or by hydrothermal processes. These alkali metal silicates are typically water soluble.
  • the water glass to be used according to the invention preferably contains cations of one or more alkali metals from the group consisting of lithium, sodium and potassium.
  • the molar modulus S1O2 / M2O of the water glass is preferably in the range from 1.6 to 4.0, where M2O denotes the total amount of oxides of alkali metals M.
  • Component (C) of the kits according to the invention preferably has an alkali metal silicate (ie water glass) content in the range from 20% to 60%, preferably in the range from 25% to 55%, based on the total mass of component (C).
  • component (C) of the kit according to the invention contains one or more oxidic boron compounds, preferably selected from the group consisting of borates, boric acids, and boric anhydrides, particularly preferably sodium tetraborate decahydrate, the total concentration of oxidic boron compounds being calculated as B2O30.4% to 1.0%, particularly preferably 0.5% to 0.8%, based on the total mass of component (C).
  • Oxidic boron compounds in component (C) improve the resistance of the moldings produced from the molding material mixture to water and atmospheric moisture.
  • component (C) of the kit according to the invention is a solution or dispersion comprising lithium-containing waterglass, the total concentration of lithium calculated as LhO preferably 0.4% to 1.0%, particularly preferably 0.4% to 0, 7%, based on the total mass of component (C).
  • Lithium-containing waterglass is understood here to mean alkali metal silicates which contain lithium ions and possibly ions of other alkali metals, typically sodium and / or potassium ions.
  • a solution or dispersion comprising lithium-containing waterglass with a molar module S1O2 / M2O in the range from 1.6 to 3.5, preferably in the range from 1.8 to 3.0, the molar proportion of Lb > 0 of M2O is in the range from 0.05 to 0.60, preferably in the range from 0.1 to 0.4, where M2O denotes the total amount of lithium, sodium and potassium oxide.
  • Lithium-containing waterglass improves the resistance of the moldings produced from the molding material mixture to water and atmospheric moisture.
  • component (C) of the kit according to the invention is a kit containing raw materials for producing a solution or dispersion comprising lithium-containing waterglass.
  • component (C) of the kit according to the invention contains, as separate constituents (C1), an aqueous solution or dispersion comprising water glass, in which constituent
  • component (C1) the S1O2 content is in the range of 20% to 34%, based on the total mass of the solution or dispersion, where component (C1) preferably has a pH value in the range from 10.0 to 13.0, particularly preferably in the range from 11.0 to 12.5,
  • component (C2) a first water glass-free solution or dispersion comprising lithium ions dissolved in water, where in component (C2) - the concentration of the lithium ions is in the range from 0.3 mol / L to 5.3 mol / L and the total concentration of the lithium, sodium and potassium ions is in the range from 0.3 mol / L to 28.0 mol / L, component (C2) preferably having a pH in the range from 8.0 to 14.0, in particular preferably in the range from 11.5 to 12.3, and optionally
  • (C3) a second waterglass-free solution or dispersion comprising alkali metal ions dissolved in water, the concentration of lithium ions in component (C3) being lower than in component (C2) and preferably in the range from 0.1 mol / L to 5 , 0 mol / L, particularly preferably in the range from 0.1 mol / L to 2.0 mol / L; and the total concentration of lithium, sodium and potassium ions is in the range from 0.3 mol / L to 28.0 mol / L and the total concentration of lithium, sodium and potassium ions in component (C3) by no more than 20% from the total concentration of lithium, sodium and potassium ions in component (C2), component (C3) preferably having a pH in the range from 8.0 to 14.0, particularly preferably in the range from 11.5 to 13.5.
  • component (C) of the kit according to the invention the components (C1), (C2) and - if present - (C3) are present separately, i.e. spatially separated from one another, e.g. in separate containers.
  • component (C1) The concentration of lithium ions in the water glass of component (C1) is significantly lower than in the lithium-containing water glass to be produced.
  • Component (C1) preferably does not contain any lithium ions.
  • the production of lithium-containing water glass from the raw materials described above is described in patent application WO 2019/002452 A1.
  • component (D) of the kit according to the invention the constituents (D1), (D2a) or (D2b), (D3) and (D4) are present in the following concentration, based on the total mass of component (D):
  • composition (D) there is an aqueous phase (water-containing liquid phase) for which it applies that the ratio of the mass of the water to the total mass of the aqueous phase is greater than 50%, preferably greater than 70%, particularly preferably greater than 90%.
  • This aqueous phase comprises the carrier liquid (D1) as well as components dissolved therein.
  • Compositions (D) as described above include both ready-to-use sizing compositions and concentrates for forming ready-to-use sizing compositions.
  • Ready-to-use sizing compositions have a sufficiently high content of carrier liquid (D1) so that they can be applied directly to the base body to form a coating.
  • the mass of the carrier liquid (D1) is 40% to 75%, preferably 60% to 75%, based on the total mass of the composition.
  • Concentrates for the production of a ready-to-use sizing composition contain a significantly smaller amount of carrier liquid (D1) compared to the ready-to-use sizing composition.
  • the total mass of the carrier liquid (D1) is 40% or less, based on the total mass of the composition.
  • a ready-to-use sizing composition can be obtained by diluting the concentrate with a carrier liquid (D1).
  • the solids content of component (D) is less than 80%, preferably less than 75%, based on the total mass of component (D).
  • the solids content of component (D) essentially comprises constituents (D3) and (D4). Solids are understood to mean the constituents of component (D) which are present in component (D) in solid form, ie are not dissolved in the carrier liquid (D1), but rather are suspended. In a ready-to-use sizing composition, the proportion of the constituents is (D3) and (D4) 25% to 60%, based on the total mass of the size composition. In a concentrate for producing a ready-to-use size composition, the solids content is greater than 40%, but less than 80%, based on the total mass of component (D).
  • Component (D) of the kit according to the invention contains water or a mixture of water and one or more alcohols, for example ethanol, methanol, isopropanol, as the carrier liquid (constituent (D1)).
  • the carrier liquid (D1) only serves as a vehicle for applying the substances suspended and dissolved in it to the base body of the core to be produced, and is removed when the base body coated with a composition (D) as defined above dries (for details see the disclosure in the context of the method according to the invention described below).
  • the carrier liquid is liquid under normal conditions (20 ° C and 1013.25 hPa) and can be evaporated under normal pressure (1013.25 hPa) at temperatures in the range from 80 ° C to 200 ° C.
  • Component (D) of the kit according to the invention usually contains either as constituent (D2)
  • R1 and R2 are each monovalent groups which, independently of one another, each contain 1 to 26 carbon atoms, the group R1 being attached via a carbon atom contained in the group R1 or via an oxygen atom contained in the group R1, and the group R2 is attached via a carbon atom contained in group R2, or are linked to one another to form a ring structure that the ring structure comprises a total of 4 to 7 ring atoms and the groups R1 and R2 comprise a total of 2 to 26 carbon atoms, the group R1 via a carbon atom contained in the group R1 or via one in the group R1 contained oxygen atom, and the group R2 is bonded via a carbon atom contained in the group R2.
  • R1 and R2 are each monovalent groups which, independently of one another, are straight-chain or branched and contain 1 to 16, preferably 1 to 12, carbon atoms, which carbon atoms are one to four times (that is, once, twice, three times or four times) can be replaced and / or substituted by oxygen and / or hydroxyl, the group R1 being attached via a carbon atom contained in the group R1 or via an oxygen atom contained in the group and R2 via a carbon atom contained in the group R2 is attached, or are linked to one another to form a ring structure that the ring structure comprises a total of 4 to 7, preferably 5 to 7, ring atoms selected from oxygen and carbon, and the groups R1 and R2 together as a whole 2 to 16, preferably 3 to 8, carbon atoms, which are straight-chain or branched and one to fourfold ( i.e.
  • the constituents (D2a) and (D2b) increase the strength of the core provided with the size coating. It is currently assumed that the component (D2a) or by hydrolysis of the component (D2b) of the component (D) of the kit according to the invention provides acid which, via an acid-base reaction, is optionally produced by the aqueous carrier liquid (D1). the alkali silicate structure of the waterglass-bonded base body attacked by the coating composition can cure (heal) again. It is also believed that the Acid-base reaction of the acid from component (D2a) or the acid formed by hydrolysis of component (D2b) with the alkali silicate structure of the base body improves the bonding of the size coating to the base body.
  • component (D) contains the constituent (D2a) defined above, it is preferred that the acids have a pKa ⁇ 5, particularly preferably a pKa ⁇ 4, in each case at 25.degree.
  • the acids are particularly preferably selected from the group consisting of organic acids selected from the group consisting of mono-, di- and tricarboxylic acids, preferably mono-, di- and tricarboxylic acids solid at 25 ° C.
  • component (D) contains the constituent (D2b) defined above, it is preferred that the organic compounds of the formula (I) are selected from the group consisting of esters, lactones and acid anhydrides. Water-soluble esters, lactones and acid anhydrides are preferred. Compounds of the formula (I) from the group consisting of methyl formate, ethyl formate, propylene carbonate, ⁇ -butyrolactone, diacetin, triacetin, dibasic esters, acetic anhydride, methyl carbonate and ⁇ -caprolactone are particularly preferred. Propylene carbonate is particularly preferred.
  • the constituents (D3) and (D4) of component (D) are refractory materials.
  • “refractory” refers to masses, materials and minerals that can withstand the temperature load during casting or solidification of a molten iron, at least for a short time. Masses, materials and minerals that can withstand the casting heat of molten steel for a short time are referred to as “highly refractory”. The temperatures that can occur when casting steel melts are usually higher than the temperatures that can occur when casting iron or cast iron melts.
  • Refractory masses, materials and minerals (refractory materials) and highly refractory masses, materials and minerals are known to the person skilled in the art, for example from DIN 51060: 2000-06.
  • Materials that are particularly suitable as refractory materials are Have melting points which are at least 200 ° C. above the temperature of the metal melt used in each case and / or which do not react with the metal melt.
  • the term “refractory material as used here also includes highly refractory materials.
  • Platelet-shaped particles (D3) in the context of the present invention are particles with three dimensions extending perpendicularly to one another (length, width, thickness), the length being the largest and the thickness being the smallest, with length and width not differing significantly, and the thickness / length ratio is 0.2 or less.
  • the length of the platelet-shaped particles (D3) is preferably in the range from 1 pm to 600 pm, more preferably 5 pm to 500 pm, more preferably 5 pm to 200 pm, particularly preferably 10 pm to 200 pm, in particular 10 pm to 150 pm, 10 pm to 100 pm, or 10 pm to 80 pm.
  • the particle dimensions are determined in accordance with ISO 13322-2. The dimensions of these particles can be determined, for example, in a manner known to the person skilled in the art, using a camsizer. Such particles are also referred to as flakes, flakes, scales or tablets.
  • Platelet-shaped particles (D3) are e.g. obtainable by delamination (e.g. in a grinding process) of sheet silicates or of
  • Suitable sheet silicates are clay minerals belonging to the group of sheet silicates, as well as mica, talc, kaolins, metakaolins, calcined kaolins, pyrophyllites, illites and bentonites.
  • Suitable graphites are macrocrystalline natural graphites and macrocrystalline synthetic graphites. Macrocrystalline natural graphites and macrocrystalline synthetic graphites are in the form of crystal lite (platelets, flakes, flakes or panels) that can be seen with the naked eye, the extent of which in the c-plane is in the range from 100 ⁇ m to a few millimeters.
  • Synthetic graphite can be obtained by the Acheson process or by compression molding and firing (800-1300 ° C) petroleum coke with the addition of a binder (coal tar pitch) and subsequent electrographitization. Synthetic graphite is present in the form of crystals, the extent of which in the c-plane is in the range from a few 100 ⁇ (a few 10 nm) to a few millimeters.
  • macrocrystalline synthetic graphite in the form of crystals can be used with an expansion in the c-plane from 100 ⁇ m to a few millimeters, while microcrystalline synthetic graphite can be used as refractory material (D4) within the meaning of the present invention is (see below).
  • Natural graphite occurs both in macrocrystalline, leafy form and in microcrystalline, earthy form.
  • the macrocrystalline, leafy form of natural graphite can be replaced as refractory material (D3) within the meaning of the present invention, while the microcrystalline, earthy form can be used as refractory material (D4) within the meaning of the present invention (see below).
  • the refractory materials (D3) in the form of platelet-shaped particles are preferably selected from the group consisting of macrocrystalline graphites, ⁇ -boron nitride and sheet silicates.
  • Preferred sheet silicates are clay flours (made from clay minerals belonging to the group of sheet silicates), mica, talc, kaolins, metakaolins, calcined kaolins, pyrophyllites, illites and bentonites. Pyrophyllites and ground clay are particularly preferred.
  • Granular particles (D4) in the context of the present invention are particles with three dimensions extending perpendicularly to one another (length, width, thickness), with thickness and width not differing significantly, and the thickness / length ratio in the range from 0.8 to 1 lies.
  • Granular particles (D4) in the context of the present invention thus also include spherical particles (for details see below).
  • the length of the granular particles (D4) is preferably in the range from 10 nm to 250 pm, preferably 50 nm to 200 pm, particularly preferably 50 nm to 100 pm, in particular 100 nm to 50 pm or 100 nm to 20 pm.
  • the particle dimensions are determined in accordance with ISO 13322-2. The dimensions of these particles can be determined, for example, in a manner known to the person skilled in the art, using a camsizer.
  • Granular particles with sharply defined edges are also referred to in practice as splintery particles; these are among the granular particles in the sine of the present invention.
  • Granular, especially splintery particles (D4) can be obtained, for example, by breaking (e.g. in a grinding process) glass, monocrystalline sands or polycrystalline sands or rocks.
  • the refractory materials (D4) in the form of granular particles are preferably selected from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, silimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxides, bauxite, wollas tonite, titanium dioxides , Olivine, alkaline earth metal phosphates of the composition MsiPO ⁇ OH, where M is an alkaline earth metal, preferably Ca, silicon nitride and rutile. Zirconium silicate and microcrystalline graphite are particularly preferred. Soot is a form of carbon that is formed in the event of incomplete combustion or thermal splitting of vaporous carbon-containing substances.
  • Coke can be obtained by heating hard coal, brown coal or peat in the absence of air to temperatures of approx. 800 ° C.
  • Suitable microcrystalline graphites are microcrystalline natural graphites (earthy natural graphites) and microcrystalline synthetic graphites.
  • Microcrystalline natural graphites as well as microcrystalline synthetic graphites are in the form of crystallites, the extent of which in the c-plane is less than 100 ⁇ m; the individual crystallites can therefore only be seen under the microscope.
  • the proportion of refractory materials (D3) is in the range from 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range from 85% to 20%, preferably in the range from 70% to 40%, each based on the total mass of refractory materials (D3) and refractory materials (D4). This also applies to ready-to-use size compositions produced by diluting component (D) of the kit according to the invention.
  • platelet-shaped particles (D3) on the one hand and granular particles (D4) on the other hand is possible, e.g. using two-dimensional microscopic images of the corresponding particles.
  • Further possibilities for differentiating between platelet-shaped particles (D3) on the one hand and granular particles (D4) are sedimentation methods or granulometry. These methods are known to the person skilled in the art.
  • constituent (D4) of component (D) of the kit according to the invention also comprises
  • component (D4a) amorphous particulate silica.
  • component (D4a) contributes to increasing the strength of the core provided with the size coating and improves the bonding of the size coating to the base body, which also contains amorphous particulate silicon dioxide (from component (B)).
  • the proportion of amorphous particulate silicon dioxide (D4a) is preferably 3% to 30%, based on the total mass of the refractory materials (D4).
  • amorphous particulate silicon dioxide is preferably used in component (B) of the kit according to the invention and in component (D4) of component (D) of the kit according to the invention.
  • the primary particles (“primary particles”) of the amorphous silicon dioxide are often agglomerated after the manufacturing processes mentioned above, ie as agglomerates of primary particles.
  • the particle shape of the primary particles of the particulate, amorphous silicon dioxide (D4a) is preferably approximately spherical, the sphericity being 0.9 or more. In the context of the present invention, sphericity is defined as the circumference of the equivalent projection area of a circle (EQPC for short) of a particle divided by the actual circumference of the particle.
  • the determination of the particle size necessary for the determination of the sphericity is carried out for particles with a particle size of less than 5 pm preferably according to the standard test method according to ISO 13322-1: 2014 and for particles with a particle size of larger than 5 pm preferably according to the standard Test method according to ISO 13322-02: 2006.
  • Modern commercially available electron microscopic or light microscopic systems enable digital image analysis and thus a convenient determination of the particle shape.
  • Digital image analysis is preferred for studies of sphericity.
  • the digital image analysis is preferably carried out using commercial image analysis software, such as the Image-Pro Plus Software from Media Cybernetics. When preparing samples for digital image analysis, make sure that the particles are oriented randomly. If necessary, thin sections are to be made.
  • the refractory materials in the form of platelet-shaped particles selected from the group consisting of macrocrystalline graphites, ⁇ -boron nitride, and layered silicates, the layered silicates preferably being selected from the group consisting of clay flours (of clay minerals belonging to the group of layered silicates), Mica, talc, kaolins, metakaolins, calcined kaolins, pyrophyllites, hats and bentonites, as well
  • the refractory materials in the form of granular or splintery particles selected from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, silimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxide den, bauxite, wollastonite, titanium dioxide, olivine, alkaline earth metal phosphates of the composition M 5 (P0 4 ) 30H, where M is an alkaline earth metal, preferably Ca, silicon nitride and rutile.
  • component (D3) is formed by sheet silicates, for example pyrophyllite and / or powdered clay
  • component (D4) is formed by microcrystalline graphite and zirconium silicate (in a mass ratio of 2: 3 to 3: 2).
  • the proportion of refractory materials (D3) is preferably 40% to 60%, based on the total mass of refractory materials (D3) and refractory materials (D4).
  • Component (D4) preferably additionally contains (D4a) amorphous particulate silicon dioxide.
  • the inventive combination of the particulate constituents (D3) and (D4) in component (D) ensures that the size composition (D) or a size composition produced by diluting component (D) has the effects of a covering size (top size) and united in a penetrating coating.
  • Top coatings usually contain predominantly flake-form refractory materials, penetrating coatings usually predominantly granular refractory materials.
  • top coat when a top coat is applied to a base body formed from a molding material mixture as described above, the particulate refractory materials contained in the top coat form a covering layer on the mold material of the base body, which comes into direct contact with the melt during casting, i.e. becomes the surface of the base body sealed. Finishing layers penetrate less than approx. 2 mm into the molding material. Penetrating coatings, on the other hand, penetrate deeper into the molding material, so that the particulate refractory materials contained in such a coating fill the pores in the molding material.
  • compositions (D3) and (D4) By applying a sizing composition containing the inventive combination of the particulate constituents (D3) and (D4) it is achieved that both pores in the molding material are filled and a covering layer is formed on the molding material that comes into direct contact with the melt (cf. also the statements below in the context of cores according to the invention).
  • Component (D) of the kit according to the invention can comprise further constituents which are usually contained in compositions (D) for the production of size coatings, in particular constituents selected from the group consisting of wetting agents, rheological additives, binders, adjusting agents and biocides. Suitable wetting agents, rheological additives, binders, adjusting agents and biocides and their function and effect are known to the person skilled in the art.
  • a kit according to the invention contains as separate components
  • composition for producing a coating comprising (D1) a carrier liquid selected from the group consisting of water and
  • R1 and R2 are in each case monovalent groups which, independently of one another, each contain 1 to 26 carbon atoms, where the group R1 is attached via a carbon atom contained in the group R1 or via an oxygen atom contained in the group R1, and the group R2 via a carbon atom contained in the group R2 or are linked to one another to form a ring structure that the ring structure comprises a total of 4 to 7 ring atoms and the groups R1 and R2 comprise a total of 2 to 26 carbon atoms, the group R1 via a carbon atom contained in the group R1 or via a the oxygen atom contained in the group R1 is bonded, and the group R2 is bonded via a carbon atom contained in the group R2;
  • (D3) one or more refractory materials from the group consisting of macrocrystalline graphites ⁇ -boron nitride, and sheet silicates;
  • (D4) one or more refractory materials from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, silimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxides, bauxite, wollastonite, titanium dioxides, olivine, alkaline earth metal phosphates of the composition M 5 (Rq 4 ) 3 OH, where M is an alkaline earth metal, preferably Ca, silicon nitride and
  • refractory materials (D3) being in the range from 15% to 80%, preferably 30% to 60%, based on the total mass of refractory materials (D3) and refractory materials (D4) in component (D).
  • the proportion of refractory materials (D3) is in the range from 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range from 85% to 20%, preferably in the range from 70% to 40%, each based on the total mass of refractory materials (D3) and refractory materials (D4).
  • This also applies to ready-to-use sizing compositions produced by diluting component (D) of the kit according to the invention.
  • Suitable sheet silicates are clay minerals belonging to the group of sheet silicates, as well as mica, talc, kaolins, metakaolins, calcined kaolins, pyrophyllites, illites and bentonites.
  • constituent (D3) pyrophyllites and powdered clay (made from clay minerals belonging to the group of sheet silicates) are particularly preferred.
  • Microcrystalline graphite and zirconium silicate are particularly preferred as constituents (D4).
  • constituent (D4) of component (D) of the above-described alternative variant of the kit according to the invention furthermore comprises (D4a) amorphous particulate silicon dioxide.
  • the proportion of amorphous particulate silicon dioxide (D4a) is preferably 3% to 30%, based on the total mass of the refractory materials (D4).
  • component (B) of the kit according to the invention With regard to the characteristics of the amorphous particulate silicon dioxide and the selection of suitable types of amorphous particulate silicon dioxide, the above statements regarding component (B) of the kit according to the invention apply accordingly.
  • the same type of amorphous particulate silicon dioxide is preferably used in component (B) of the alternative variant of the kit according to the invention and in component (D4) of component (D) of the alternative variant of the kit according to the invention.
  • component (D3) is formed by sheet silicates, for example pyrophyllite and / or powdered clay
  • component (D4) is formed by microcrystalline graphite and zirconium silicate (in a mass ratio of 2: 3 to 3: 2).
  • the proportion of refractory materials (D3) is preferably 40% to 60%, based on the total mass of refractory materials (D3) and refractory materials (D4).
  • Component (D4) preferably additionally contains (D4a) amorphous particulate silicon dioxide.
  • Component (D) of the alternative variant of the kit according to the invention can comprise further constituents which are usually contained in compositions for the production of size coatings, in particular constituents selected from the group consisting of wetting agents, rheological additives, binders, adjusting agents and biocides. Suitable wetting agents, rheological additives, binders, adjusting agents and biocides as well as their function and effect are known to the person skilled in the art. If one of these components (e.g. rheological additives) is a refractory material in the form of platelets Particles (D3) as defined above or a refractory material in the form of granular particles (D4) as defined above, it is assigned to component (D3) or (D4) as defined above.
  • a second aspect of the present invention relates to a method for producing cores for use in die casting, comprising the steps
  • step (D) applying a composition (D) or a coating composition formed by diluting a composition (D) with carrier liquid (D1) to the base body and then drying, so that a coating is produced on the base body, a core being formed comprising the base body and a coating which is arranged on the base body and extends at least over the entire surface of the core which comes into contact with a molten metal during the casting process.
  • step (a) of the method according to the invention the spatially separate components (B) and (C) of the kit according to the invention are mixed into the basic molding material (component (A) of the kit according to the invention) simultaneously or one after the other.
  • component (B) of the kit according to the invention is mixed into the basic molding material (component (A) of the kit according to the invention) first, so that a premix comprising components (A) and (B) of the kit according to the invention is mixed is formed, and component (C) of the kit according to the invention is mixed into the premix obtained in this way (ie an aqueous solution or dispersion containing water glass or raw materials for producing a solution or dispersion comprising water glass as described above), so that the molding material mixture is obtained.
  • component (C) of the kit according to the invention is mixed in first (ie an aqueous solution or dispersion containing waterglass or raw materials for the production of a solution or dispersion comprising water glass) is mixed into the basic molding material (component (A) of the kit according to the invention), so that a premix comprising components (A) and (C) of the kit according to the invention is formed, and into the Premix obtained in this way component (B) of the kit according to the invention is mixed in, so that the molding material mixture is obtained.
  • component (A) of the kit according to the invention is mixed in first (ie an aqueous solution or dispersion containing waterglass or raw materials for the production of a solution or dispersion comprising water glass) is mixed into the basic molding material (component (A) of the kit according to the invention), so that a premix comprising components (A) and (C) of the kit according to the invention is formed, and into the Premix obtained in this way component (B) of the kit according to the invention is mixed in
  • the basic molding material (component (A) of the kit according to the invention as defined above) preferably makes up more than 80% by weight, preferably more than 90% by weight, particularly preferably more than 95% by weight, of the total mass of a in step (a ) produced molding material mixture from.
  • the concentration of the particulate, amorphous silicon dioxide from component (B) of the kit according to the invention is preferably 0.05% to 3.0%, more preferably 0.1% to 2.0% , particularly preferably 0.3% to 1.5%, based on the total mass of the basic molding material.
  • component (C) of the kit according to the invention is preferably added in an amount of 0.2% to 3%, particularly preferably 0.3% to 2%, based on the total mass of the basic molding material.
  • a molding material mixture produced in step (a) of the method according to the invention is preferably in a free-flowing form, so that it can easily be poured into a molding tool for molding and compacted there.
  • the compression of the molding material mixture in the mold serves to increase the strength of foundry molds or foundry cores produced from the molding material mixture.
  • the molding of the molding material mixture in step (b) of the method according to the invention is usually carried out in a molding tool.
  • the molding material mixture is preferably introduced into the molding tool by means of compressed air.
  • step (c) of the process according to the invention is preferably carried out at temperatures in the range from 100 ° C to 300 ° C, particularly preferably 100 ° C to 250 ° C.
  • the thermal hardening of the binder system takes place through chemical reaction of components of the binder system with one another, so that a shaped body (base body of the core to be produced) results.
  • the cause of the thermal hardening of the binder system is essentially the condensation of the water glass, ie the linkage of the silicate units of the water glass with one another (the reaction mechanism has been comprehensively described in the specialist literature). For this purpose, water is removed from the binder system by the thermal treatment.
  • the heating of the molded molding material mixture for thermal hardening of the Isyste ms binding agent can take place, for example, in a molding tool which has temperatures of over 100 ° C, preferably temperatures of 100 ° C to 300 ° C, particularly preferably temperatures of 120 ° C to 250 ° C, having.
  • the thermal curing of the binder system in the molded molding material mixture is preferably carried out completely or at least partially in a conventional molding tool for the industrial production of molded articles.
  • the thermal curing of the binder system can take place in the molded molding material mixture, in suitable systems and / or using suitable equipment (such as lines, pumps, etc.), in which the thermal hardening is supported by targeted gassing of the molded molding material mixture with temperature-controlled air.
  • the air is preferably tempered to 100 ° C. to 250 ° C., particularly preferably to 110 ° C. to 180 ° C.
  • air contains carbon dioxide, this does not correspond in the context of the present invention to curing according to the prior art CCW process for curing water glass, which requires the targeted gassing of the formed molding material mixture with a CC> 2-rich gas, in particular in suitable Systems and / or using suitable equipment (such as pipes, pumps, etc.).
  • the formed molding material mixture is gassed with a gas which contains CO2 in a concentration that is higher than its concentration in air, preferably not in the context of the thermal hardening provided according to the invention or in combination therewith.
  • the period of time for thermal curing i.e. also the period of time for heating and targeted gassing of the molded molding material mixture with tempered air
  • the flow rate and / or volume flow of the tempered air during the targeted gassing of the molded molding material mixture are preferably set so that within a period of time that is acceptable for industrial use, preferably a very short period of time, sufficient hardening of the molded molding material is achieved for further processing or use. mixture, is achieved (for details see below).
  • a period of less than 5 minutes is preferred in the context of the present invention, particularly preferably less than 2 minutes. In the case of very large moldings, however, longer periods of time may also be necessary, depending on the requirements of the individual case.
  • the molded molding material mixture can already be largely cured in the molding tool.
  • the process according to the invention does not require that the binder system be completely cured during the thermal treatment.
  • “Thermal hardening” in the sense of the method according to the invention as described above thus also includes the incomplete hardening of the binder.
  • the person skilled in the art knows, for example, the phenomenon of post-curing of the (for example thermally cured) binder system in a molded body, for example a foundry mold or a foundry core.
  • the thermal curing can also be brought about or supported by the action of microwaves or by the action of electromagnetic radiation, in particular infrared radiation, on the molded molding material mixture.
  • the thermal hardening can also be effected or supported by passing electrical current through the molded molding material mixture, preferably uniform and particularly preferably also uniform passing current or by a preferably uniform and particularly preferably uniform application of an electromagnetic field through or to the molded Mixing of the fo rm. Through this the molding material mixture is heated, preferably heated uniformly, and thereby cured particularly uniformly and as a result of high quality. Details are disclosed in DE 102017217098 B3 and the literature cited therein.
  • a composition (D) or a coating composition formed by diluting a composition (D) with carrier liquid (D1) is applied to the surface of the base body.
  • component (D) of the kit according to the invention is not available as a ready-to-use size, but rather as a concentrate (proportion of the carrier liquid (D1) 40% or less, based on the total mass of the composition (D))
  • this concentrate is first diluted with carrier liquid ( D1) a coating composition (ready-to-use size) produced with a proportion of carrier liquid (D1) of 40% to 75% based on the total mass of the coating composition or a coating composition with a proportion of components (D3) and (D4) of 25% to 60% based on the total mass of the coating composition, and the coating composition thus formed is applied to the surface of the base body.
  • a carrier liquid (D1) is usually used which is contained in the carrier liquid (D1) of the concentrate, usually water.
  • the proportion of refractory materials (D3) is in the range from 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range from 85% to 20% , preferably in the range from 70% to 40%, each based on the total mass of refractory materials (D3) and refractory materials (D4).
  • the base body When the composition (D) or the coating composition formed therefrom is applied, the base body preferably has a temperature of less than 80.degree. C., preferably in the range from 15.degree. C. to 35.degree. When the base body has cooled down to a temperature of less than 80 ° C., preferably in the range from 15 ° C. to 35 ° C., after thermal curing (step (c)), the binder in the base body has achieved sufficient strength, see above that the water-glass-bonded base body is sufficiently water-resistant when it comes into contact with the aqueous coating composition.
  • the application of the composition (D) or the coating composition formed therefrom to the surface of the base body can be carried out using any suitable technique respectively.
  • the composition is preferably applied to the surface of the base body in such a way that a core results with a coating formed from the composition (D) or the coating composition produced therefrom, which extends at least over the entire surface of the core, which during the casting process with a molten metal comes into contact.
  • the coating preferably extends over the entire surface of the core.
  • the composition (D) or the coating composition formed therefrom is preferably applied to the surface of the base body by a method selected from the group consisting of spraying, dipping, flooding and brushing, particularly preferably dipping.
  • the composition (D) or the coating composition formed therefrom is preferably applied in such a way that a wet layer thickness in the range from 25 ⁇ m to 600 ⁇ m, preferably 150 ⁇ m to 350 ⁇ m, results.
  • the carrier liquid (D1) is removed by drying and a coating is thus formed on the base body.
  • a core is formed comprising the base body and a coating arranged on the base body which extends at least over the entire surface of the core which comes into contact with a molten metal during the casting process.
  • the coating extends over the entire surface of the core.
  • a third aspect of the present invention relates to a core for use in die casting.
  • a core according to the invention comprises
  • (D4) one or more refractory materials in the form of granular particles, the proportion of refractory materials (D3) being in the range from 15% to 80%, preferably 30% to 60%, based on the total mass of refractory materials (D3) and refractory materials (D4 ).
  • the above statements regarding the corresponding components and constituents of the kit according to the invention apply mutatis mutandis to components (A) and of (B) base body (i) and to constituents (D3) and (D4) of the coating (ii) of the core according to the invention.
  • the proportion of refractory materials (D3) is in the range from 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range from 85% to 20%, preferably in the range from 70% to 40%, each based on the total mass of refractory materials (D3) and refractory materials (D4).
  • the refractory materials (D3) are preferably selected from the group consisting of macrocrystalline graphites (as defined above), ⁇ -boron nitride, and sheet silicates.
  • Suitable sheet silicates (D3) are clay minerals belonging to the group of sheet silicates, as well as mica, talc, kaolins, metakaolins, calcined kaolins, pyrophyllites, illites and bentonites.
  • constituent (D3) pyrophyllites and powdered clay (made from clay minerals belonging to the group of sheet silicates) are particularly preferred.
  • Microcrystalline graphite and zirconium silicate are particularly preferred as constituents (D4).
  • the refractory materials (D4) in the form of granular particles are preferably selected from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, silimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxides, bauxite, wollas tonite, titanium dioxides , Olivine, alkaline earth metal phosphates of the composition Ms (P0 4 ) 30H, where M is an alkaline earth metal, preferably Ca, silicon nitride and rutile. Zirconium silicate and microcrystalline graphite are particularly preferred.
  • constituent (D4) of component (D) of the coating of the above-described core according to the invention also comprises
  • the proportion of amorphous particulate silicon dioxide (D4a) is preferably 3% to 30%, based on the total mass of the refractory materials (D4).
  • component (D3) is formed by sheet silicates, e.g. pyrophyllite and / or powdered clay
  • component (D4) is formed by microcrystalline graphite and zirconium silicate (in a mass ratio of 2: 3 to 3: 2).
  • the proportion of refractory materials (D3) is 40% to 60%, based on the total mass of refractory materials (D3) and refractory materials (D4).
  • Component (D4) preferably additionally contains (D4a) amorphous particulate silicon dioxide.
  • the coating (ii) fills gaps between the particles of the basic mold material on the surface of the base body (i) of the core according to the invention, and a cover layer is formed on the base body (i) which comes into contact with a molten metal during the casting process.
  • the base body in a completely random manner, i.e. without a specific orientation. It is assumed that by aligning the platelet-shaped particles of the component (D3) and the granular particles of the component (D4) parallel to the core surface, it is achieved that the core surface offers very little flow resistance to the molten metal.
  • a core according to the invention on the surface of the base body (i) gaps between the particles of the basic molding material are at least partially filled by granular particles of the component (D4) of the coating (ii), while the platelet-shaped Particles of the component (D3) of the coating (ii) cover and seal the cavities.
  • the coating (ii) of a core according to the invention is therefore almost free of macroscopic pores and cavities. Macroscopic pores are understood to be pores with a size of 0.05 mm or larger that are clearly visible to the naked eye.
  • the interaction of the components (D3) and (D4) ensures that a core according to the invention has a high penetration resistance to the molten metal during die casting.
  • a core according to the invention contains salts that are soluble with water as a solvent (as described in WO 2011/151420 A1) in a concentration of less than 8%, preferably less than 5 %, particularly preferably less than 3%, less than 2%, less than 1%, based on the total mass of the core.
  • the core according to the invention particularly preferably does not contain any salts which are soluble with water as a solvent (as described in WO 2011/151420 A1).
  • a core according to the invention can be produced by the method according to the invention as described above.
  • a core (i) according to the invention comprises a base body
  • (D3) one or more refractory materials from the group consisting of a macrocrystalline graphite, ⁇ -boron nitride, and sheet silicates; (D4) one or more refractory materials from the group consisting of microcrystalline graphites, carbon black, coke, zirconium silicate, andalusite, silimanite, kyanite, quartz, quartz glass, mullite, chamottes, aluminum oxides, bauxite, wollastonite, titanium dioxides, olivine, alkaline earth metal phosphates of the composition M 5 (Rq 4 ) 3 OH, where M is an alkaline earth metal, preferably Ca, silicon nitride and
  • refractory materials (D3) being in the range from 15% to 80%, preferably 30 to 60%, based on the total mass of refractory materials (D3) and refractory materials (D4).
  • the refractory materials (D3) are preferably selected from the group consisting of macrocrystalline graphites (as defined above), ⁇ -boron nitride, and sheet silicates.
  • Suitable sheet silicates (D3) are clay minerals belonging to the group of sheet silicates, mica, talc, kaolins, metakaolins, calcined kaolins, pyrophyllites, illites and bentonites.
  • the proportion of refractory materials (D3) is in the range from 15% to 80%, preferably 30% to 60%, and the proportion of refractory materials (D4) is in the range from 85% to 20%, preferably in the range from 70% to 40% %, each based on the total mass of refractory materials (D3) and refractory materials (D4).
  • constituent (D4) of component (D) of the coating of the alternative variant of the core according to the invention described above also comprises
  • the proportion of amorphous particulate silicon dioxide (D4a) is preferably 3% to 30%, based on the total mass of the refractory materials (D4).
  • component (D3) is formed by sheet silicates, for example pyrophyllite and / or powdered clay
  • component (D4) is formed by microcrystalline graphite and zirconium silicate (in a mass ratio of 2: 3 to 3: 2).
  • the proportion of Refractory materials (D3) preferably 40% to 60%, based on the total mass of refractory materials (D3) and refractory materials (D4).
  • Component (D4) preferably additionally contains (D4a) amorphous particulate silicon dioxide.
  • a core according to the invention can be produced by the method according to the invention as described above.
  • a method for using a core in die casting, in particular in the die casting of light metals comprises the steps
  • Cores according to the invention according to the third aspect of the invention described above or cores produced by a method according to the invention according to the second aspect of the invention described above are particularly suitable for use in the die casting of light metals, in particular from the group consisting of aluminum and aluminum alloys.
  • the core can be removed from the cast part by conventional techniques, e.g. by slowly dissolving the binder in water, or by hydrostatic pressure (e.g. by means of water jets), or by means of vibration, acoustic coring, or current pulse coring.
  • the die casting is preferably carried out with the following machine parameters
  • Piston speed in the range from 1.00 m / s to 10.00 m / s, preferably 1.00 m / s to 5.00 m / s, particularly preferably 2.00 m / s to 2.10 m / s;
  • Cutting speed in the range from 5.0 m / s to 50.0 m / s, preferably 5.0 ms to 40.0 m / s, more preferably 10 m / s to 20 m / s, particularly preferably 13 m / s to 19 m / s;
  • Holding pressure in the range from 15 MPa to 100 MPa, preferably 35 MPa to 80 MPa, particularly preferably 60 MPa to 70 MPa.
  • Another aspect of the invention relates to the use of a composition (D) as described above in the context of the first aspect of the invention for producing a core according to the invention according to the third aspect of the invention described above or in a method according to the invention according to the second aspect of the invention described above .
  • Components (A) - (D) of a kit according to the invention for producing cores for use in die casting were provided.
  • the composition of components (A) - (D) is described below.
  • the same components (A) - (C) were provided as well as a coating composition not according to the invention, the composition of which is given below.
  • a molding material mixture was produced by mixing (A) quartz sand H32 as the molding base material
  • This molding material mixture was used in the usual way
  • a coating composition was applied to the base body, which had been cooled to a temperature of less than 80 ° C., preferably 15 ° C. to 35 ° C.
  • coating compositions size were used which were formed by diluting the concentrates (D) (see Tables 1 and 2 below) with water as the carrier liquid (D1).
  • the coating composition was in each case applied to the surface of the base body by immersing the base body in a bath with the respective coating composition.
  • a coating composition was used which was formed by diluting the concentrate (V) (see Table 1 below) with isopropanol as the carrier liquid.
  • the coating composition not according to the invention corresponds to customary commercially available size compositions.
  • sizes are usually used for waterglass-bonded cores, the carrier liquid of which contains alcohols as the main constituent, and little or no water, since water attacks the alkali silicate framework of waterglass-bonded cores.
  • the viscosities of the coating compositions according to the invention and those not according to the invention are almost identical.
  • “Other constituents” are to be understood in the prior art as conventional constituents from the group consisting of wetting agents, rheological additives, binders, thickening agents and biocides.
  • the cores according to the invention thus obtained were then exposed to a temperature in the range from 80 ° C. to 220 ° C. and the comparison cores to a temperature in the range from 15 ° C. to 30 ° C. so that the carrier liquid evaporates or evaporates and a coating is formed on the base body is formed from the non-volatile constituents of the respective coating composition.
  • Table 1 Composition of the coating compositions
  • Table 2 Composition of further coating compositions for the production of cores according to the invention 2. Light microscopic examination
  • Pieces were sawn out of a core according to the invention (production and composition as described in point 1, coating composition as stated in Table 1 above) and from a core not according to the invention (production and composition as described in point 1, coating composition as stated in Table 1 above) and embedded in a vacuum using a two-component epoxy resin.
  • the preparation then took place using a Tegramin 20 grinding and polishing machine from Struers.
  • the samples are first ground using diamond disks and then polished with diamond suspensions to the final stage, which results in a so-called cut.
  • the polished sections produced were then examined microscopically using a Zeiss Axioscope 5 light microscope with an Axiocam 305 color (D) microscope camera.
  • FIG. 1 shows a micrograph of the core not according to the invention
  • FIG. 2 shows a micrograph of the core according to the invention.
  • the cut extends through an area of the base body close to the surface and the coating arranged on its surface.
  • the relatively large particles of the basic molding material quartz sand H32, see above
  • the coating adjoins the surfaces of the outer particles of the base body.
  • FIG. 1 shows that the granular particles of the coating composition not according to the invention are deposited on the surface of the core in a completely random manner, ie without a specific orientation.
  • the granular particles penetrate into pores between the particles of the basic molding material, but they are not covered and sealed. Therefore the surface formed by the coating is not even and smooth, but at least partially simulates the contours of the surface of the base body, ie the coating has unevenness and depressions which to a certain extent reflect the irregularities of the surface of the base body.
  • Figure 2 shows that the platelet-shaped particles of the coating composition according to the invention align with their longest dimension parallel to the core surface, and thereby bridge and cover the unevenness and depressions on the surface of the base body filled by the granular particles, so that the irregularities of the surface of the Base body hardly affect the surface of the coating.
  • the coating therefore has a relatively flat and smooth surface.
  • Casting tests with aluminum were carried out on a cold chamber die casting machine.
  • cores according to the invention it was possible to successfully produce cast parts with a gate speed of 15 m / s to 20 m / s without penetration errors (penetration of the melt into the core) or core breakage occurring.
  • penetration errors were always found.
  • the cast parts are quenched in a water bath.
  • the core can, for example, be removed from the casting by slowly dissolving the alkali silicate binder in water or removed by means of water jets.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Civil Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Dispersion Chemistry (AREA)
  • Mold Materials And Core Materials (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Moulding By Coating Moulds (AREA)

Abstract

L'invention concerne l'utilisation d'une composition de coulis pour la production de noyaux pour le moulage sous pression, un kit pour la production de noyaux destinés à être utilisés dans le moulage sous pression, un procédé de fabrication de noyaux destinés à être utilisés dans le moulage sous pression, des noyaux destinés à être utilisés dans le moulage sous pression, et l'utilisation de tels noyaux dans le moulage sous pression, en particulier de métaux légers.
EP20808386.5A 2019-11-22 2020-11-18 Noyaux pour moulage sous pression Pending EP4061556A1 (fr)

Applications Claiming Priority (2)

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DE102019131676.6A DE102019131676A1 (de) 2019-11-22 2019-11-22 Kerne für den Druckguss
PCT/EP2020/082498 WO2021099366A1 (fr) 2019-11-22 2020-11-18 Noyaux pour moulage sous pression

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EP4061556A1 true EP4061556A1 (fr) 2022-09-28

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US (1) US20230001470A1 (fr)
EP (1) EP4061556A1 (fr)
JP (1) JP2023503432A (fr)
KR (1) KR20220102137A (fr)
CN (1) CN114728327A (fr)
BR (1) BR112022009901A2 (fr)
DE (1) DE102019131676A1 (fr)
MX (1) MX2022006198A (fr)
TW (1) TW202126402A (fr)
WO (1) WO2021099366A1 (fr)

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JPH0659515B2 (ja) * 1989-08-07 1994-08-10 リョービ株式会社 崩壊性中子の中間層形成用スラリー及びこれを用いた崩壊性中子の製造方法並びにこれにより製造された崩壊性中子
DE102005041863A1 (de) * 2005-09-02 2007-03-29 Ashland-Südchemie-Kernfest GmbH Borsilikatglashaltige Formstoffmischungen
EP2576100A1 (fr) 2010-06-02 2013-04-10 Emil Müller GmbH Noyaux de sel stabilisés par un infiltrat
DE102011114626A1 (de) * 2011-09-30 2013-04-04 Ask Chemicals Gmbh Beschichtungsmassen für anorganische Giessformen und Kerne und deren Verwendung
DE102012020510B4 (de) 2012-10-19 2019-02-14 Ask Chemicals Gmbh Formstoffmischungen auf der Basis anorganischer Bindemittel und Verfahren zur Herstellung von Formen und Kerne für den Metallguss
DE102014004914A1 (de) * 2013-08-26 2015-02-26 Gebrüder Dorfner GmbH & Co. Kaolin- und Kristallquarzsand-Werke KG Gießform oder einen Gießformkern aus beschichtetem Formsand für Metallguss
DE102013111626A1 (de) * 2013-10-22 2015-04-23 Ask Chemicals Gmbh Formstoffmischungen enthaltend eine oxidische Bor-Verbindung und Verfahren zur Herstellung von Formen und Kernen
DE102017217098B3 (de) 2016-12-06 2018-04-05 Wolfram Bach Verfahren und Form- oder Kernwerkzeug zur Herstellung von Formen oder Kernen
DE102017107657A1 (de) * 2017-01-04 2018-07-05 HÜTTENES-ALBERTUS Chemische Werke Gesellschaft mit beschränkter Haftung Schlichtezusammensetzung, umfassend organische Esterverbindungen und partikuläres, amorphes Siliziumdioxid, zur Verwendung in der Gießereiindustrie
DE102017107658A1 (de) * 2017-01-04 2018-07-05 HÜTTENES-ALBERTUS Chemische Werke Gesellschaft mit beschränkter Haftung Schlichtezusammensetzung für die Gießereiindustrie, enthaltend partikuläres, amorphes Siliziumdioxid und Säure
EA201991683A1 (ru) 2017-01-11 2019-12-30 Дуглас М. Триновски Композиции и способы для литейных стержней при литье под высоким давлением
DE102017114628A1 (de) 2017-06-30 2019-01-03 HÜTTENES-ALBERTUS Chemische Werke Gesellschaft mit beschränkter Haftung Verfahren zur Herstellung einer Formstoffmischung und eines Formkörpers daraus in der Gießereiindustrie sowie Kit zur Anwendung in diesem Verfahren

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CN114728327A (zh) 2022-07-08
DE102019131676A1 (de) 2021-05-27
US20230001470A1 (en) 2023-01-05
MX2022006198A (es) 2022-06-16
BR112022009901A2 (pt) 2022-08-09
WO2021099366A1 (fr) 2021-05-27
TW202126402A (zh) 2021-07-16
KR20220102137A (ko) 2022-07-19
JP2023503432A (ja) 2023-01-30

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