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WO2024208450A1 - Support structure for material jetting - Google Patents

Support structure for material jetting Download PDF

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Publication number
WO2024208450A1
WO2024208450A1 PCT/EP2024/025098 EP2024025098W WO2024208450A1 WO 2024208450 A1 WO2024208450 A1 WO 2024208450A1 EP 2024025098 W EP2024025098 W EP 2024025098W WO 2024208450 A1 WO2024208450 A1 WO 2024208450A1
Authority
WO
WIPO (PCT)
Prior art keywords
particles
support structure
suspension
separating layer
green body
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
PCT/EP2024/025098
Other languages
German (de)
French (fr)
Inventor
Wolfgang Kollenberg
Dieter Nikolay
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.)
Durst Group AG
Original Assignee
Durst Group AG
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 Durst Group AG filed Critical Durst Group AG
Publication of WO2024208450A1 publication Critical patent/WO2024208450A1/en
Anticipated expiration legal-status Critical
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/10—Formation of a green body
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B22F1/107—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material containing organic material comprising solvents, e.g. for slip casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/14—Treatment of metallic powder
    • B22F1/145—Chemical treatment, e.g. passivation or decarburisation
    • B22F1/147—Making a dispersion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/10—Formation of a green body
    • B22F10/12—Formation of a green body by photopolymerisation, e.g. stereolithography [SLA] or digital light processing [DLP]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/40—Structures for supporting workpieces or articles during manufacture and removed afterwards
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/40—Structures for supporting workpieces or articles during manufacture and removed afterwards
    • B22F10/43—Structures for supporting workpieces or articles during manufacture and removed afterwards characterised by material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/40—Structures for supporting workpieces or articles during manufacture and removed afterwards
    • B22F10/47—Structures for supporting workpieces or articles during manufacture and removed afterwards characterised by structural features
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/10—Processes of additive manufacturing
    • B29C64/165—Processes of additive manufacturing using a combination of solid and fluid materials, e.g. a powder selectively bound by a liquid binder, catalyst, inhibitor or energy absorber
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
    • B29C64/40—Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y10/00—Processes of additive manufacturing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y70/00—Materials specially adapted for additive manufacturing
    • B33Y70/10—Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y80/00—Products made by additive manufacturing
    • 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
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/30—Inkjet printing inks
    • C09D11/32—Inkjet printing inks characterised by colouring agents
    • C09D11/322—Pigment inks
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D11/00—Inks
    • C09D11/30—Inkjet printing inks
    • C09D11/38—Inkjet printing inks characterised by non-macromolecular additives other than solvents, pigments or dyes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B1/00—Producing shaped prefabricated articles from the material
    • B28B1/001—Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
    • C04B2235/5436—Particle size related information expressed by the size of the particles or aggregates thereof micrometer sized, i.e. from 1 to 100 micron
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
    • C04B2235/5445—Particle size related information expressed by the size of the particles or aggregates thereof submicron sized, i.e. from 0,1 to 1 micron
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
    • C04B2235/5454—Particle size related information expressed by the size of the particles or aggregates thereof nanometer sized, i.e. below 100 nm
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/54—Particle size related information
    • C04B2235/5463—Particle size distributions
    • C04B2235/5472—Bimodal, multi-modal or multi-fraction
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
    • C04B2235/602—Making the green bodies or pre-forms by moulding
    • C04B2235/6026—Computer aided shaping, e.g. rapid prototyping
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
    • C04B2235/608—Green bodies or pre-forms with well-defined density
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/77—Density
    • 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
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/96—Properties of ceramic products, e.g. mechanical properties such as strength, toughness, wear resistance
    • C04B2235/9607—Thermal properties, e.g. thermal expansion coefficient

Definitions

  • the invention relates to a green body which was produced in layers using the 3D printing process material jetting and which is connected to a support structure via a separating layer, as well as a method for its production, a sintered part and a method for its production, as well as the use of a composition containing particles for producing a separating layer between a green body and a support structure.
  • the building material is applied using an inkjet print head. This can move across the construction platform in strips and prints the component layer by layer according to the sliced CAD data.
  • the printed material is dried using IR radiation, for example, or photosensitive components in the ink are cured using a light source.
  • a support structure In order to be able to create overhangs in components, a support structure must be built underneath.
  • Commercially available 3D printers that work according to the material jetting principle already use such support structures. However, since these printers have so far been used to produce plastic parts, water-soluble resins (or low-melting waxes), for example, are used for the support structures. Support structures are also used in binder jetting.
  • the disadvantage of the binder jetting process is that it can only be used to print relatively thick layers of usually more than 100 ⁇ m and that only green bodies with high porosities of usually more than 40% are obtained, which can then shrink considerably during sintering or become brittle after sintering.
  • WO2014152798A1 describes a ceramic support structure.
  • W02018102731A1 describes additively manufactured components with an acceleration of debinding.
  • US10800108B2 describes a sinterable release material.
  • US2017297100A1 describes the production of a release layer in a binder jetting process.
  • US2017297097A1 also describes the production of a release layer in a binder jetting process.
  • EP3612330A2 describes a method for producing printed articles.
  • W02010061394A1 describes a method for applying material to a substrate.
  • WO2018193306A2 describes a method for producing printed articles.
  • W02017180314A1 describes additive manufacturing with support structures in a binder jetting process.
  • the object of the present invention is therefore to overcome the disadvantages of the prior art and to provide a technology with which components with overhangs and undercuts can be produced by means of material jetting and support structures can be used during construction and simultaneously also during sintering.
  • the object underlying the invention is achieved by a green body which was produced in layers using the 3D printing process material jetting and which is connected to a support structure via a separating layer, wherein the green body, separating layer and support structure contain particles, wherein the median particle size of the particles in the separating layer is in a range from 200% to 10,000% of the median particle size of the material particles in the support structure, and/or the median particle size of the particles in the separating layer is in a range from 200% to 10,000% of the median particle size of the material particles in the green body, wherein the thermal expansion coefficient of the material of the particles in the separating layer deviates from the thermal expansion coefficient of the material of the particles in the support structure and/or from the thermal expansion coefficient of the material of the particles in the green
  • the green body behaves in such a way that the risk of defects and cracks forming during the drying and/or sintering process is reduced. Ceramic components typically become smaller during the thermal processes, which is referred to as shrinkage. The extent of the shrinkage depends to a first approximation on the type of ceramic, the particle size of the raw material and the sintering temperature. To prevent the support material (support structure) from sintering with the building material (green body), a separating layer is applied between the support and the component.
  • the basis of the patent is the idea of producing a support structure from the same material or at least a very similar material as the component (such as Al2O3 with a grain size in the median of 1000 lb/ft). This would allow it to sinter and shrink.
  • a support structure that supports the green body during 3D printing can also be used as a sintering base during sintering.
  • the linear sintering shrinkage of the support structure preferably differs from the linear sintering shrinkage of the green body by less than 20%, particularly preferably less than 10%. Sintering shrinkage can be determined, for example, using a caliper.
  • a layer of coarse-grained material (for example with a grain size of 40pm) is preferably applied between the component and the support structure as a separating layer.
  • This separating layer material would therefore not sinter into a solid structure at the sintering temperature, which means that the component can be removed from the support structure after sintering.
  • layer thickness refers to the thickness of the layers that are applied to one another using the material jetting process to obtain the green body.
  • the layer thickness of the individual printed layers of the support structure is preferably in a range from 1 to 50 pm, particularly preferably in a range from 2 to 30 pm, very particularly preferably in a range from 5 to 20 pm.
  • the layer thickness can also be in a range from 2 to 300 pm, particularly preferably in a range from 100 to 250 pm, very particularly preferably 150 to 200 pm.
  • the layer thickness can be measured, for example, using an optical microscope. For example, 10 measuring points can be measured along a specific layer and the average value calculated.
  • the porosity represents the ratio between the void volume and the total volume.
  • the porosity can be determined according to DIN EN 993-1.
  • Support structure measured after sintering is preferably in a range of 0 to 15 Vol.%, particularly preferably in a range of 0 to 5 vol.%.
  • the porosity of the support structure measured after sintering or before sintering preferably deviates by less than 5% from the porosity of the green body.
  • the volume taken up by air, water and organic substances (such as solvents or binders) in the green body and/or the support structure is preferably in a range of 7 to 20 vol.%, particularly preferably in a range of 10 to 15 vol.%.
  • Water and also the organic substances are largely removed by sintering.
  • a certain amount of shrinkage occurs during sintering.
  • the resulting porosity of the sintered object is preferably in the aforementioned preferred range.
  • the separating layer preferably has a thickness in a range of 10 to 1000 pm, most preferably in a range of 20 to 200 pm.
  • the material of the particles in the support structure is preferably metallic or ceramic.
  • the ceramic material can be selected from metal oxides, metal nitrides, metal carbides and/or mixtures thereof.
  • the material of the particles in the green body is preferably metallic or ceramic.
  • the ceramic material can be selected from metal oxides, metal nitrides, metal carbides, carbon and/or mixtures thereof.
  • carbon is described as a ceramic material (carbon ceramic).
  • the material of the particles in the separating layer is preferably metallic or ceramic.
  • the ceramic material can be selected from metal oxides, metal nitrides, metal carbides and/or mixtures thereof.
  • the material of the particles of the separating layer is particularly preferably not a carbonate, in particular not iron carbonate, since this can lead to contamination and/or discoloration of the ceramic or the metal.
  • the material of the particles in the support structure and in the green body is substantially identical in its chemical composition, in particular the material has the same sintering temperature.
  • the material of the particles in the support structure, in the green body and in the separating layer is identical. This results in fewer defects such as cracks or distortion due to different thermal expansion of the materials.
  • the easiest way is to use the same material for the support structure as for the sintered part.
  • the material of the particles in the support structure and in the green body is therefore preferably identical.
  • the median particle size of the particles in the green body is preferably in a range from 0.01 to 15 pm, particularly preferably in a range from 0.05 to 6 pm, very particularly preferably in a range from 0.1 to 3 pm.
  • the median particle size of the particles in the support structure is preferably in a range from 0.01 to 15 pm, particularly preferably in a range from 0.05 to 6 pm, very particularly preferably in a range from 0.1 to 3 pm.
  • the deviation of the median particle size of the particles in the green body from the median particle size of the particles in the support structure is preferably in a range from 0 to 5%.
  • the median particle size of the particles in the separating layer is preferably in a range from 2 to 100 pm, very particularly preferably in a range from 6 to 50 pm.
  • the content of particles with a diameter of less than 6 pm in the separating layer is in a range from 0 to 5% relative to all particles in the separating layer.
  • the particles in the separating layer preferably have a higher sphericity than the particles in the support structure. This has the advantage that the particles in the separating layer do not sinter as easily later during sintering.
  • the sphericity of the particles in the separating layer is The median sphericity of the particles in the support structure is preferably in a range from 0 to 0.5.
  • Sphericity can be determined, for example, using dynamic image analysis according to ISO 13322, whereby the values obtained represent the volume-weighted average over the respective sample of the corresponding particle mixture.
  • the sphericity of a particle describes the relationship between the surface area of a particle image and the circumference. Accordingly, a spherical particle would have a sphericity close to 1, while a jagged, irregular particle image would have a roundness close to zero.
  • the object on which the invention is based is achieved by a method for producing the green body according to the invention, characterized in that the following steps are carried out: a. producing at least one main suspension, a support structure suspension and a separating layer suspension of particles in solvent, wherein the median particle size of the particles in the separating layer suspension is in a range from 200% to 10,000% of the median particle size of the material particles in the support structure suspension and/or the median particle size of the particles in the separating layer suspension is in a range from 200% to 10,000% of the median particle size of the material particles in the main suspension, b. printing at least the main suspension and the support structure suspension with at least one print head onto a substrate to form a first layer of the green body and the support structure, c.
  • step b repeating step b. until the support structure and the green body are fully printed, whereby wherever the green body and the support structure meet, one or more layers of the separating layer suspension are printed so that a separating layer is created, wherein the thermal expansion coefficient of the material of the particles in the separating layer suspension deviates from the thermal expansion coefficient of the material of the particles in the support structure suspension and/or from the thermal expansion coefficient of the material of the particles in the main suspension by less than 5%.
  • the support structure can be printed from a support structure suspension that is different from the main suspension.
  • an additional print head is preferably used.
  • the support structure suspension can also be identical to the main suspension.
  • the main suspension is then used as the support structure suspension.
  • the main suspension is preferably printed with only one print head.
  • the main suspension and/or support structure suspension can also contain other components such as binders, wetting additives or defoamers.
  • the separating layer suspension can also contain other components such as binders, wetting additives or defoamers.
  • the median particle size of the particles in the main suspension and/or support structure suspension is preferably in a range from 0.01 to 6 pm, most preferably in a range from 0.1 to 3 pm.
  • the median particle size of the particles in the separating layer suspension is preferably in a range from 2 to 100 pm, most preferably in a range from 6 to 50 pm.
  • the content of particles having a diameter of less than 6 pm in the separating layer suspension is in a range of 0 to 5% relative to all particles in the separating layer suspension.
  • the particles in the separating layer suspension preferably have a higher sphericity than the particles in the main suspension and/or support structure suspension. This has the advantage that the particles in the separating layer do not sinter as easily later during sintering.
  • the median sphericity of the particles in the separating layer suspension is preferably in a range from 0.6 to 1.
  • the median sphericity of the particles in the main suspension and/or support structure suspension is preferably in a range from 0 to 0.5.
  • the binder content in the main suspension and/or support structure suspension is preferably in a range from 0.1 to 5 wt.%.
  • the binder content in the separating layer suspension is preferably in a range from 0.4 to 5 wt.%.
  • the binder content in the separating layer suspension is preferably at least 10%, most preferably at least 50%, above the binder content in the main suspension and/or support structure suspension. This has the advantage that the particles cannot sinter together as easily due to the high binder content.
  • the binder content in the separating layer suspension can be at least 10%, most preferably at least 50%, below the binder content in the main suspension and/or support structure suspension. This has the advantage that a solid structure cannot form in the separating layer in the first place.
  • a print head is used for printing the separating layer with the separating layer suspension which differs from the print head for printing the main suspension and/or support structure suspension.
  • the print head for printing the separating layer suspension in contrast to the print head for printing the main suspension and/or support structure suspension, is suitable for printing suspensions with particles with a particle size of more than 5 pm.
  • the same print head can be used for printing the main suspension and/or support structure suspension and the separating layer suspension. This is then preferably able to print suspensions with particles with a particle size of more than 5 pm.
  • step c 1 to 50 layers, preferably 1 to 10 layers or 5 to 50 layers, are printed with the separating layer suspension in order to obtain the separating layer.
  • the layer thickness of the individual printed layers in the separating layer is preferably in a range from 2 to 200 pm, very particularly preferably in a range from 5 to 20 pm or in a range from 50 to 180 pm.
  • the solvent is preferably water.
  • the water content in the main suspension and/or support structure suspension is preferably in a range from 10 to 40 wt.%.
  • the water content in the separating layer suspension is preferably in a range from 10 to 40 wt.%.
  • the content of particles in the main suspension and/or support structure suspension is preferably in a range from 60 to 90 wt.%.
  • the content of particles in the separating layer suspension is preferably in a range from 60 to 90 wt.%.
  • the content of wetting additive in the main suspension and/or support structure suspension is preferably in a range from 0.1 to 2% by weight, in particular 0.1 to 1.
  • the content of wetting additive in the separating layer suspension is preferably in a range from 0.05 to 0.5% by weight (up to 1%).
  • the content of wetting additive in the main suspension and/or support structure suspension is preferably at least 50%, very particularly preferably at least 100%, above the content of wetting additive in the separating layer suspension.
  • the content of defoamer in the main suspension and/or support structure suspension is preferably in a range from 0.01 to 0.2 wt.%.
  • the content of defoamer in the separating layer suspension is preferably in a range from 0.01 to 0.2 wt.%.
  • the object underlying the invention is achieved by a sintered part which is produced by sintering the green body according to the invention, characterized in that the porosity is in a range from 0 to 15 vol.%.
  • the sintered part can be easily lifted off the support structure through the separating layer.
  • the support structure is sintered together with the green body, for example. Sintering can preferably result in the material of the separating layer being sintered in such a way that the green body and support structure can be easily separated from one another.
  • the porosity of the sintered support structure deviates by less than 5% from the porosity of the sintered part.
  • the sintered part can have all the properties of the green body mentioned above, as long as the expert would not consider them to be explicitly. In contrast to the green body, it will no longer be possible to detect any defoamers in the sintered part. On the other hand, the materials of the particles and the particle sizes may still be the same, for example.
  • the object underlying the invention is achieved by a method for producing the sintered part according to the invention, characterized in that a green body according to the invention is sintered.
  • the object underlying the invention is achieved by using a liquid composition containing ceramic or metallic particles for producing a separating layer between a green body and a support structure.
  • the composition can, for example, be the separating layer suspension described above, including its preferred embodiments.
  • a main suspension which, in addition to AI2O3 with a median grain size of 0.7pm (CT3000 SG from Almatis), contains a wetting additive (Dolapix CE 64 from Zschimmer&Schwarz), a temporary binder (Optapix AC95 from Zschimmer&Schwarz) and a defoamer (Contraspum KWE from Zschimmer&Schwarz). Water was used as a dispersing medium.
  • the composition of such a main suspension is listed in the following table.
  • This main suspension was used to produce a green body and a support structure of a component using material jetting.
  • a special print head from Durst Phototechnik AG was used as the print head, which is described in detail in WO2013013983A1.
  • This print head is very robust against abrasive suspensions such as ceramic glazes and slips.
  • This print head can also be used to print suspensions with particles with a diameter of more than 45 pm. Water-based suspensions with a very low proportion of organic solvents can also be printed.
  • the support structure was made with the same main suspension and the same print head was used.
  • a separating layer suspension was produced with the same chemical material of the particles, but with a significantly coarser grain size (“separating layer”).
  • a fused corundum of size F600 with an average grain size of about 9 pm was suitable for this.
  • a separating layer suspension was therefore produced from this material, the composition of which is listed in the following table:
  • This release layer suspension was printed with a second print head connected to a second ink supply system. After sintering at 1600°C and a holding time of 2 hours, the green body was sintered into a ceramic part, as was the support structure. The significantly coarser material between the now sintered part and the support structure was not sintered but formed a separating layer, which allowed the sintered part to be lifted off the support structure.
  • the generation of the support structure and the green body as well as the separating layer was supported by suitable software.
  • the printing of the separating layer between the green body and the support structure was controlled by the 3D printer software.

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Abstract

The invention relates to a green body that has been produced in layers by the 3D method of material jetting and which is bonded to a support structure via a separation layer, and to a process for production thereof, to a sintered part and to a method of production thereof, and to the use of a composition containing particles for production of a separation layer between a green body and a support structure.

Description

Stützstruktur für Material Jetting support structure for material jetting

Die Erfindung betrifft einen Grünkörper, der mit dem 3D-Druckverfahren Material-Jetting in Schichten hergestellt wurde und der mit einer Stützstruktur über eine Trennschicht verbunden ist, sowie ein Verfahren zu dessen Herstellung, ein gesintertes Teil und ein Verfahren zu dessen Herstellung, sowie die Verwendung einer Zusammensetzung enthaltend Partikel zur Herstellung einer Trennschicht zwischen einem Grünkörper und einer Stützstruktur. The invention relates to a green body which was produced in layers using the 3D printing process material jetting and which is connected to a support structure via a separating layer, as well as a method for its production, a sintered part and a method for its production, as well as the use of a composition containing particles for producing a separating layer between a green body and a support structure.

Um Keramikbauteile mittels Material Jetting herstellen zu können, ist es notwendig, ein Stützmaterial zu nutzen. Nur dadurch ist es möglich, filigrane Bauteile mit Überhängen und Hinterschneidungen herzustellen. Wenn ein solches Stützmaterial das Bauteil im Bauprozess und gleichermaßen im Sinterprozess stützen könnte, könnte der Aufwand zur defektfreien Herstellung von Keramikbauteilen deutlich reduziert werden. In order to be able to manufacture ceramic components using material jetting, it is necessary to use a support material. This is the only way to manufacture delicate components with overhangs and undercuts. If such a support material could support the component during the construction process and equally during the sintering process, the effort required to produce defect-free ceramic components could be significantly reduced.

Die Nomenklatur richtet sich in dieser Anmeldung nach der DIN EN ISO/ASTM 52900:2022-03. The nomenclature in this application is based on DIN EN ISO/ASTM 52900:2022-03.

Im Material Jetting wird das Baumaterial über einen Tintenstrahl-Druckkopf aufgebracht. Dieser kann bahnenweise die Bauplattform überfahren und druckt gemäß der geslicten CAD- Daten Lage für Lage das Bauteil. Um eine Verfestigung der Tropfen zu erreichen, wird das verdruckte Material beispielsweise mittels IR-Strahlung getrocknet oder photosensitive Bestandteile in der Tinte mittels einer Lichtquelle ausgehärtet. Um Überhänge in Bauteilen herstellen zu können, muss darunter eine Stützstruktur aufgebaut werden. In kommerziell verfügbaren 3D-Druckern, die nach dem Prinzip des Material Jettings arbeiten, werden bereits solche Stützstrukturen genutzt. Da mit diesen Druckern jedoch bisher Kunststoff-Teile hergestellt werden, werden für die Stützstrukturen beispielsweise wasserlösliche Harze (oder niedrig schmelzende Wachse) eingesetzt. Im Binder Jetting ebenfalls werden bereits Stützstrukturen eingesetzt. Der Nachteil des Binder Jetting Verfahrens ist, dass damit nur relativ hohe Schichtdicken von üblicherweise mehr als 100 p in gedruckt werden können und nur Grünkörper mit hohen Porositäten von üblicherweise mehr als 40% erhalten werden, die dann beim Sintern sehr stark schrumpfen können oder nach dem Sintern brüchig sind. In material jetting, the building material is applied using an inkjet print head. This can move across the construction platform in strips and prints the component layer by layer according to the sliced CAD data. In order to solidify the droplets, the printed material is dried using IR radiation, for example, or photosensitive components in the ink are cured using a light source. In order to be able to create overhangs in components, a support structure must be built underneath. Commercially available 3D printers that work according to the material jetting principle already use such support structures. However, since these printers have so far been used to produce plastic parts, water-soluble resins (or low-melting waxes), for example, are used for the support structures. Support structures are also used in binder jetting. The disadvantage of the binder jetting process is that it can only be used to print relatively thick layers of usually more than 100 μm and that only green bodies with high porosities of usually more than 40% are obtained, which can then shrink considerably during sintering or become brittle after sintering.

WO2014152798A1 beschreibt eine keramische Stützstruktur. WO2014152798A1 describes a ceramic support structure.

W02018102731A1 beschreibt additiv gefertigte Bauteile mit einer Beschleuningung der Entbinderung. W02018102731A1 describes additively manufactured components with an acceleration of debinding.

US10800108B2 beschreibt ein sinterfähiges Trennmaterial. US10800108B2 describes a sinterable release material.

US2017297100A1 beschreibt die Herstellung einer Trennschicht in einem Binder Jetting Verfahren. US2017297100A1 describes the production of a release layer in a binder jetting process.

US2017297097A1 beschreibt ebenfalls die Herstellung einer Trennschicht in einem Binder Jetting Verfahren. US2017297097A1 also describes the production of a release layer in a binder jetting process.

US2016229128A1 beschreibt eine Tinte für den 3D-Druck. US2016229128A1 describes an ink for 3D printing.

EP3612330A2 beschreibt ein Verfahren zur Herstellung von Druckartikeln. EP3612330A2 describes a method for producing printed articles.

W02010061394A1 beschreibt ein Verfahren zum Aufträgen von Material auf ein Substrat. W02010061394A1 describes a method for applying material to a substrate.

WO2018193306A2 beschreibt ein Verfahren zum Herstellen von gedruckten Artikeln. WO2018193306A2 describes a method for producing printed articles.

W02017180314A1 beschreibt additive Fertigung mit Stützstrukturen in einem Binder Jetting Verfahren. W02017180314A1 describes additive manufacturing with support structures in a binder jetting process.

Die Aufgabe der vorliegenden Erfindung ist es daher, die Nachteile des Standes der Technik zu überwinden und eine Technologie bereitzustellen, mit der Bauteile mit Überhängen und Hinterschneidungen mittels Material Jetting hergestellt und Stützstrukturen beim Aufbau und gleichzeitig auch beim Sintern verwendet werden können. In einer ersten Ausführungsform wird die der Erfindung zu Grunde liegende Aufgabe durch einen Grünkörper gelöst, der mit dem 3D-Druckverfahren Material-Jetting in Schichten hergestellt wurde und der mit einer Stützstruktur über eine Trennschicht verbunden ist, wobei Grünkörper, Trennschicht und Stützstruktur Partikel enthalten, wobei die Partikelgröße der Partikel in der Trennschicht im Median in einem Bereich von 200% bis 10.000% der Partikelgröße der Materialpartikel im Median in der Stützstruktur liegt, und/oder die Partikelgröße der Partikel in der Trennschicht im Median in einem Bereich von 200% bis 10.000% der Partikelgröße der Materialpartikel im Median im Grünkörper liegt, wobei der Wärmeausdehnungskoeffizient des Materials der Partikel in der Trennschicht von dem Wärmeausdehnungskoeffizient des Materials der Partikel in der Stützstruktur und/oder von dem Wärmeausdehnungskoeffizient des Materials der Partikel im Grünkörper jeweils weniger als 5% abweicht, wobei das Volumen, das im Grünkörper durch Luft, Wasser und organische Substanzen eingenommen wird, in einem Bereich 5 bis 25 Vol.% liegt. The object of the present invention is therefore to overcome the disadvantages of the prior art and to provide a technology with which components with overhangs and undercuts can be produced by means of material jetting and support structures can be used during construction and simultaneously also during sintering. In a first embodiment, the object underlying the invention is achieved by a green body which was produced in layers using the 3D printing process material jetting and which is connected to a support structure via a separating layer, wherein the green body, separating layer and support structure contain particles, wherein the median particle size of the particles in the separating layer is in a range from 200% to 10,000% of the median particle size of the material particles in the support structure, and/or the median particle size of the particles in the separating layer is in a range from 200% to 10,000% of the median particle size of the material particles in the green body, wherein the thermal expansion coefficient of the material of the particles in the separating layer deviates from the thermal expansion coefficient of the material of the particles in the support structure and/or from the thermal expansion coefficient of the material of the particles in the green body by less than 5%, wherein the volume taken up in the green body by air, water and organic substances is in a range from 5 to 25 vol.%.

Der Grünkörper verhält sich dadurch so, dass die Gefahr der Defekt- und Rissbildung während der Trocknung und/oder Sintervorgang verringert wird. Keramische Bauteile werden während der thermischen Prozesse typischerweise kleiner, was als Schwindung bezeichnet wird. Die Größe der Schwindung ist in erster Näherung abhängig von der Art der Keramik, der Partikelgröße des Rohstoffes und der Sintertemperatur. Um zu vermeiden, dass das Stützmaterial (Stützstruktur) mit dem Baumaterial (Grünkörper) versintert, wird zwischen Stütze und Bauteil eine Trennschicht aufgebracht. The green body behaves in such a way that the risk of defects and cracks forming during the drying and/or sintering process is reduced. Ceramic components typically become smaller during the thermal processes, which is referred to as shrinkage. The extent of the shrinkage depends to a first approximation on the type of ceramic, the particle size of the raw material and the sintering temperature. To prevent the support material (support structure) from sintering with the building material (green body), a separating layer is applied between the support and the component.

Basis des Patentes ist die Idee, eine Stützstruktur beispielsweise aus dem gleichen Material oder zumindest sehr ähnlichem Material wie das Bauteil (wie beispielsweise AI2O3 mit einer Korngröße im Median von Ipm) herzustellen. Hierdurch würde es gleichermaßen sintern und schwinden. So kann man eine Stützstruktur, die den Grünkörper während des 3D-Drucks stützt, auch als Sinterunterlage während des Sinterns verwenden. The basis of the patent is the idea of producing a support structure from the same material or at least a very similar material as the component (such as Al2O3 with a grain size in the median of 1000 lb/ft). This would allow it to sinter and shrink. For example, a support structure that supports the green body during 3D printing can also be used as a sintering base during sintering.

Die lineare Sinter Schwindung der Stützstruktur unterscheidet sich vorzugsweise von der linearen Sinterschwindung des Grünkörpers um weniger als 20%, besonders bevorzugt weniger als 10%. Sinterschwindung kann beispielsweise durch eine Schieblehre bestimmt werden. The linear sintering shrinkage of the support structure preferably differs from the linear sintering shrinkage of the green body by less than 20%, particularly preferably less than 10%. Sintering shrinkage can be determined, for example, using a caliper.

Um ein Versintem (beispielsweise bei 1600°C) des Grünkörpers mit der Stützstruktur zu vermeiden, wird vorzugsweise eine Lage grobkörniges Material (beispielsweise mit einer Korngröße von 40pm) zwischen Bauteil und Stützstruktur als Trennschicht aufgebracht. Dieses Material der Trennschicht würde daher bei der Sintertemperatur nicht zu einer festen Struktur versintern, wodurch das Bauteil nach dem Sintern von der Stützstruktur abgenommen werden kann. In order to avoid sintering (for example at 1600°C) of the green body with the support structure, a layer of coarse-grained material (for example with a grain size of 40pm) is preferably applied between the component and the support structure as a separating layer. This separating layer material would therefore not sinter into a solid structure at the sintering temperature, which means that the component can be removed from the support structure after sintering.

Mit dem Begriff Schichtdicke ist bei der vorliegenden Erfindung die Dicke der Schichten gemeint, die mit dem Material Jetting Verfahren aufeinander aufgetragen werden, um den Grünkörper zu erhalten. In the present invention, the term layer thickness refers to the thickness of the layers that are applied to one another using the material jetting process to obtain the green body.

Vorzugsweise liegt die Schichtdicke der einzelnen gedruckten Schichten der Stützstruktur in einem Bereich von 1 bis 50 pm, besonders bevorzugt in einem Bereich von 2 bis 30 pm, ganz besonders bevorzugt in einem Bereich von 5 bis 20 pm. Alternativ bevorzugt kann die Schichtdicke auch in einem Bereich von 2 bis 300 pm, besonders bevorzugt in einem Bereich von 100 bis 250 pm, ganz besonders bevorzugt 150 bis 200 pm, liegen. Die Schichtdicke kann beispielsweise mit einem optischen Mikroskop gemessen werden. Dabei können beispielsweise 10 Messpunkte entlang einer bestimmten Schicht gemessen werden und der Mittelwert gebildet werden. The layer thickness of the individual printed layers of the support structure is preferably in a range from 1 to 50 pm, particularly preferably in a range from 2 to 30 pm, very particularly preferably in a range from 5 to 20 pm. Alternatively, the layer thickness can also be in a range from 2 to 300 pm, particularly preferably in a range from 100 to 250 pm, very particularly preferably 150 to 200 pm. The layer thickness can be measured, for example, using an optical microscope. For example, 10 measuring points can be measured along a specific layer and the average value calculated.

Die Porosität stellt das Verhältnis zwischen dem Hohlraumvolumen und dem Gesamtvolumen dar. Die Porosität kann gemäß DIN EN 993-1 bestimmt werden. Die Porosität derThe porosity represents the ratio between the void volume and the total volume. The porosity can be determined according to DIN EN 993-1. The porosity of the

Stützstruktur gemessen nach dem Sintern liegt vorzugsweise in einem Bereich von 0 bis 15 Vol.%, besonders bevorzugt in einem Bereich von 0 bis 5 Vol.%. Die Porosität der Stützstruktur gemessen nach dem Sintern oder auch vor dem Sintern weicht vorzugsweise weniger als 5% von der Porosität des Grünkörpers ab. Support structure measured after sintering is preferably in a range of 0 to 15 Vol.%, particularly preferably in a range of 0 to 5 vol.%. The porosity of the support structure measured after sintering or before sintering preferably deviates by less than 5% from the porosity of the green body.

Das Volumen, das im Grünkörper und/oder der Stützstruktur durch Luft, Wasser und organische Substanzen (wie beispielsweise Lösungsmittel oder Bindemittel) eingenommen wird, liegt vorzugsweise in einem Bereich 7 bis 20 Vol.%, besonders bevorzugt in einem Bereich von 10 bis 15 Vol.%. Durch das Sintern wird Wasser und auch die organischen Substanzen weitgehend entfernt. Zudem kommt es beim Sintern zu einer gewissen Schrumpfung. Dadurch liegt dann die entstehende Porosität des gesinterten Gegenstandes vorzugsweise in dem vorgenannten bevorzugten Bereich. The volume taken up by air, water and organic substances (such as solvents or binders) in the green body and/or the support structure is preferably in a range of 7 to 20 vol.%, particularly preferably in a range of 10 to 15 vol.%. Water and also the organic substances are largely removed by sintering. In addition, a certain amount of shrinkage occurs during sintering. As a result, the resulting porosity of the sintered object is preferably in the aforementioned preferred range.

Die Trennschicht weist vorzugsweise eine Dicke in einem Bereich von 10 bis 1000 pm, ganz besonders bevorzugt in einem Bereich von 20 bis 200 pm. The separating layer preferably has a thickness in a range of 10 to 1000 pm, most preferably in a range of 20 to 200 pm.

Das Material der Partikel in der Stützstruktur ist vorzugsweise metallisch oder keramisch. Das keramische Material kann ausgewählt sein aus Metalloxiden, Metallntriden, Metallcarbiden und/oder Mischungen derselben. The material of the particles in the support structure is preferably metallic or ceramic. The ceramic material can be selected from metal oxides, metal nitrides, metal carbides and/or mixtures thereof.

Das Material der Partikel in dem Grünkörper ist vorzugsweise metallisch oder keramisch. Das keramische Material kann ausgewählt sein aus Metalloxiden, Metallntriden, Metallcarbiden, Kohlenstoff und/oder Mischungen derselben. Beispielsweise im Fachbuch „Technische keramische Werkstoffe“ (Herausgeber: J. Kriegesmann, Kapitel 4.3.6.0) wird Kohlenstoff als keramisches Material (Kohlenstoffkeramik) beschrieben. The material of the particles in the green body is preferably metallic or ceramic. The ceramic material can be selected from metal oxides, metal nitrides, metal carbides, carbon and/or mixtures thereof. For example, in the textbook “Technical Ceramic Materials” (editor: J. Kriegesmann, chapter 4.3.6.0), carbon is described as a ceramic material (carbon ceramic).

Das Material der Partikel in der Trennschicht ist vorzugsweise metallisch oder keramisch. Das keramische Material kann ausgewählt sein aus Metalloxiden, Metallntriden, Metallcarbiden und/oder Mischungen derselben. Besonders bevorzugt ist das Material der Partikel der Trennschicht kein Carbonat, insbesondere kein Eisencarbonat, da dies zu Kontaminationen und/oderVerfärbungen der Keramik oder des Metalls führen kann. Vorzugsweise ist das Material der Partikel in der Stützstruktur und in dem Grünkörper in ihrer chemischem Zusammensetzung im Wesentlichen identisch, insbesondere weist das Material dieselbe Sintertemperatur auf. The material of the particles in the separating layer is preferably metallic or ceramic. The ceramic material can be selected from metal oxides, metal nitrides, metal carbides and/or mixtures thereof. The material of the particles of the separating layer is particularly preferably not a carbonate, in particular not iron carbonate, since this can lead to contamination and/or discoloration of the ceramic or the metal. Preferably, the material of the particles in the support structure and in the green body is substantially identical in its chemical composition, in particular the material has the same sintering temperature.

Vorzugsweise ist das Material der Partikel in der Stützstruktur, in dem Grünkörper und in der Trennschicht identisch. Dadurch entstehen weniger Defekte wie Risse oder Verzug durch unterschiedliche thermische Ausdehnung der Materialien. Preferably, the material of the particles in the support structure, in the green body and in the separating layer is identical. This results in fewer defects such as cracks or distortion due to different thermal expansion of the materials.

Möchte man nun eine Stützstruktur herstellen, die in den thermischen Prozessen um das gleiche Maß schwindet wie die eigentliche Keramik, so ist der einfachste Weg, das identische Material für die Stutzstruktur zu nutzen, wie für das gesinterte Teil. Vorzugsweise ist daher das Material der Partikel in der Stützstruktur und in dem Grünkörper identisch. If you want to produce a support structure that shrinks in the thermal processes to the same extent as the actual ceramic, the easiest way is to use the same material for the support structure as for the sintered part. The material of the particles in the support structure and in the green body is therefore preferably identical.

Der Median der Partikelgröße der Partikel im Grünkörper liegt vorzugsweise in einem Bereich von 0,01 bis 15 pm, besonders bevorzugt in einem Bereich von 0,05 bis 6 pm, ganz besonders bevorzugt in einem Bereich von 0,1 bis 3 pm. Der Median der Partikelgröße der Partikel in der Stützstruktur liegt vorzugsweise in einem Bereich von 0,01 bis 15 pm, besonders bevorzugt in einem Bereich von 0,05 bis 6 pm, ganz besonders bevorzugt in einem Bereich von 0,1 bis 3 pm. Vorzugsweise liegt die Abweichung des Medians der Partikelgröße der Partikel im Grünkörper von dem Median der Partikelgröße der Partikel in der Stützstruktur in einem Bereich von 0 bis 5%. The median particle size of the particles in the green body is preferably in a range from 0.01 to 15 pm, particularly preferably in a range from 0.05 to 6 pm, very particularly preferably in a range from 0.1 to 3 pm. The median particle size of the particles in the support structure is preferably in a range from 0.01 to 15 pm, particularly preferably in a range from 0.05 to 6 pm, very particularly preferably in a range from 0.1 to 3 pm. The deviation of the median particle size of the particles in the green body from the median particle size of the particles in the support structure is preferably in a range from 0 to 5%.

Der Median der Partikelgröße der Partikel in der Trennschicht liegt vorzugsweise in einem Bereich von 2 bis 100 pm, ganz besonders bevorzugt in einem Bereich von 6 bis 50 pm. Vorzugsweise liegt der Gehalt an Partikeln mit einem Durchmesser von weniger als 6 pm in der Trennschicht in einem Bereich von 0 bis 5% relativ zu allen Partikeln in der Trennschicht. The median particle size of the particles in the separating layer is preferably in a range from 2 to 100 pm, very particularly preferably in a range from 6 to 50 pm. Preferably, the content of particles with a diameter of less than 6 pm in the separating layer is in a range from 0 to 5% relative to all particles in the separating layer.

Die Partikel in der Trennschicht weisen vorzugsweise eine höhere Sphärizität als die Partikel in der Stützstruktur auf. Dies hat den Vorteil, dass die Partikel in der Trennschicht später beim Sintern nicht so leicht versintem. Die Sphärizität der Partikel in der Trennschicht liegt im Median vorzugsweise in einem Bereich von 0,6 bis 1. Die Sphärizität der Partikel in der Stützstruktur liegt im Median vorzugsweise in einem Bereich von 0 bis 0,5. The particles in the separating layer preferably have a higher sphericity than the particles in the support structure. This has the advantage that the particles in the separating layer do not sinter as easily later during sintering. The sphericity of the particles in the separating layer is The median sphericity of the particles in the support structure is preferably in a range from 0 to 0.5.

Sphärizität kann beispielsweise mittels dynamischer Bildanalyse gemäß ISO 13322 ermittelt werden, wobei die erhaltenen Werte das Volumen-gewichtete Mittel über die jeweilige Probe der entsprechenden Partikelmischung darstellen. Die Sphärizität eines Partikels beschreibt das Verhältnis zwischen dem Flächeninhalt eines Partikelbildes und dem Umfang. Demnach hätte ein kugelförmiges Partikel eine Sphärizität nahe 1 während ein gezacktes, unregelmäßiges Partikelbild eine Rundheit nahe Null hätte. Sphericity can be determined, for example, using dynamic image analysis according to ISO 13322, whereby the values obtained represent the volume-weighted average over the respective sample of the corresponding particle mixture. The sphericity of a particle describes the relationship between the surface area of a particle image and the circumference. Accordingly, a spherical particle would have a sphericity close to 1, while a jagged, irregular particle image would have a roundness close to zero.

In einer weiteren Ausführungsform wird die der Erfindung zu Grunde liegende Aufgabe durch ein Verfahren zur Herstellung des erfindungsgemäßen Grünkörpers, dadurch gekennzeichnet, dass man folgende Schritte durchführt: a. Herstellung von wenigstens einer Hauptsuspension, einer Stützstruktursuspension und einer Trennschichtsuspension von Partikeln in Lösungsmittel, wobei die Partikelgröße der Partikel in der Trennschichtsuspension im Median in einem Bereich von 200% bis 10.000% der Partikelgröße der Materialpartikel im Median in der Stützstruktursuspension liegt und/oder die Partikelgröße der Partikel in der Trennschichtsuspension im Median in einem Bereich von 200% bis 10.000% der Partikelgröße der Materialpartikel im Median in der Hauptsuspension liegt, , b. Verdrucken von wenigstens der Hauptsuspension und der Stützstruktursuspension mit wenigstens einem Druckkopf auf ein Substrat zu einer ersten Schicht des Grünkörpers und der Stützstruktur, c. Wiederholung des Schrittes b. solange, bis die Stützstruktur und der Grünkörper fertig gedruckt sind, wobei überall dort, wo Grünkörper und Stützstruktur aufeinandertreffen, ein oder mehrere Schichten der Trennschichtsuspension gedruckt werden, so dass eine Trennschicht entsteht, wobei der Wärmeausdehnungskoeffizient des Materials der Partikel in der Trennschichtsuspension von dem Wärmeausdehnungskoeffizient des Materials der Partikel in der Stützstruktursuspension und/oder von dem Wärmeausdehnungskoeffizient des Materials der Partikel in der Hauptsuspension jeweils weniger als 5% abweicht. In a further embodiment, the object on which the invention is based is achieved by a method for producing the green body according to the invention, characterized in that the following steps are carried out: a. producing at least one main suspension, a support structure suspension and a separating layer suspension of particles in solvent, wherein the median particle size of the particles in the separating layer suspension is in a range from 200% to 10,000% of the median particle size of the material particles in the support structure suspension and/or the median particle size of the particles in the separating layer suspension is in a range from 200% to 10,000% of the median particle size of the material particles in the main suspension, b. printing at least the main suspension and the support structure suspension with at least one print head onto a substrate to form a first layer of the green body and the support structure, c. repeating step b. until the support structure and the green body are fully printed, whereby wherever the green body and the support structure meet, one or more layers of the separating layer suspension are printed so that a separating layer is created, wherein the thermal expansion coefficient of the material of the particles in the separating layer suspension deviates from the thermal expansion coefficient of the material of the particles in the support structure suspension and/or from the thermal expansion coefficient of the material of the particles in the main suspension by less than 5%.

Die Stützstruktur kann aus einer Stützstruktursuspension gedruckt werden, die sich von der Hauptsuspension unterscheidet. Hierzu wird vorzugsweise ein weiterer Druckkopf eingesetzt. Die Stützstruktursuspension kann auch identisch zur Hauptsuspension sein. Als Stützstruktursuspension wird dann die Hauptsuspension eingesetzt. In diesem Fall wird vorzugsweise die Hauptsuspension nur mit einem Druckkopf gedruckt. The support structure can be printed from a support structure suspension that is different from the main suspension. For this purpose, an additional print head is preferably used. The support structure suspension can also be identical to the main suspension. The main suspension is then used as the support structure suspension. In this case, the main suspension is preferably printed with only one print head.

Die Hauptsuspension und/oder Stützstruktursuspension kann auch weitere Bestandteile wie beispielsweise Binder, Benetzungs additiv oder auch Entschäumer enthalten. Die Trennschichtsuspension kann auch weitere Bestandteile wie beispielsweise Binder, Benetzungs additiv oder auch Entschäumer enthalten. The main suspension and/or support structure suspension can also contain other components such as binders, wetting additives or defoamers. The separating layer suspension can also contain other components such as binders, wetting additives or defoamers.

Der Median der Partikelgröße der Partikel in der Hauptsuspension und/oder Stützstruktursuspension liegt vorzugsweise in einem Bereich von 0,01 bis 6 pm, ganz besonders bevorzugt in einem Bereich von 0,1 bis 3 pm. The median particle size of the particles in the main suspension and/or support structure suspension is preferably in a range from 0.01 to 6 pm, most preferably in a range from 0.1 to 3 pm.

Der Median der Partikelgröße der Partikel in der Trennschichtsuspension liegt vorzugsweise in einem Bereich von 2 bis 100 pm, ganz besonders bevorzugt in einem Bereich von 6 bis 50 pm. The median particle size of the particles in the separating layer suspension is preferably in a range from 2 to 100 pm, most preferably in a range from 6 to 50 pm.

Vorzugsweise liegt der Gehalt an Partikeln mit einem Durchmesser von weniger als 6 pm in der Trennschichtsuspension in einem Bereich von 0 bis 5% relativ zu allen Partikeln in der Trennschichtsuspension. Die Partikel in der Trennschichtsuspension weisen vorzugsweise eine höhere Sphärizität als die Partikel in der Hauptsuspension und/oder Stützstruktursuspension auf. Dies hat den Vorteil, dass die Partikel in der Trennschicht später beim Sintern nicht so leicht versintern. Die Sphärizität der Partikel in der Trennschichtsuspension liegt im Median vorzugsweise in einem Bereich von 0,6 bis 1. Die Sphärizität der Partikel in der Hauptsuspension und/oder Stützstruktursuspension liegt im Median vorzugsweise in einem Bereich von 0 bis 0,5. Preferably, the content of particles having a diameter of less than 6 pm in the separating layer suspension is in a range of 0 to 5% relative to all particles in the separating layer suspension. The particles in the separating layer suspension preferably have a higher sphericity than the particles in the main suspension and/or support structure suspension. This has the advantage that the particles in the separating layer do not sinter as easily later during sintering. The median sphericity of the particles in the separating layer suspension is preferably in a range from 0.6 to 1. The median sphericity of the particles in the main suspension and/or support structure suspension is preferably in a range from 0 to 0.5.

Der Gehalt an Binder in der Hauptsuspension und/oder Stützstruktursuspension liegt vorzugsweise in einem Bereich von 0,1 bis 5 Gew.%. Der Gehalt an Binder in der Trennschichtsuspension liegt vorzugsweise in einem Bereich von 0,4 bis 5 Gew.%. Vorzugsweise liegt der Gehalt an Binder in der Trennschichtsuspension wenigstens 10%, ganz besonders bevorzugt wenigstens 50%, oberhalb des Gehaltes an Binder in der Hauptsuspension und/oder Stützstruktursuspension. Dies hat den Vorteil, dass die Partikel durch den hohen Bindergehalt nicht so leicht miteinander versintern können. Alternativ bevorzugt kann der Gehalt an Binder in der Trennschichtsuspension wenigstens 10%, ganz besonders bevorzugt wenigstens 50%, unterhalb des Gehaltes an Binder in der Hauptsuspension und/oder Stützstruktursuspension liegen. Dies hat den Vorteil, dass sich gar nicht erst eine feste Struktur in der Trennschicht bilden könnte. The binder content in the main suspension and/or support structure suspension is preferably in a range from 0.1 to 5 wt.%. The binder content in the separating layer suspension is preferably in a range from 0.4 to 5 wt.%. The binder content in the separating layer suspension is preferably at least 10%, most preferably at least 50%, above the binder content in the main suspension and/or support structure suspension. This has the advantage that the particles cannot sinter together as easily due to the high binder content. Alternatively, the binder content in the separating layer suspension can be at least 10%, most preferably at least 50%, below the binder content in the main suspension and/or support structure suspension. This has the advantage that a solid structure cannot form in the separating layer in the first place.

Vorzugsweise wird bei dem erfindungsgemäßen Verfahren für den Druck der Trennschicht mit der Trennschichtsuspension ein Druckkopf verwendet, der sich von dem Druckkopf zum Verdrucken der Hauptsuspension und/oder Stützstruktursuspension unterscheidet. Insbesondere ist der Druckkopf zum Verdrucken der Trennschichtsuspension im Unterschied zum Druckkopf zum Verdrucken der Hauptsuspension und/oder Stützstruktursuspension dazu geeignet, Suspensionen mit Partikeln mit einer Partikelgröße von mehr als 5 pm zu verdrucken. Alternativ kann aber zum Verdrucken der Hauptsuspension und/oder Stützstruktursuspension und der Trennschichtsuspension derselbe Druckkopf verwendet werden. Dieser ist dann vorzugsweise in der Lage, Suspensionen mit Partikeln mit einer Partikelgröße von mehr als 5 pm zu verdrucken. Vorzugsweise werden in Schritt c 1 bis 50 Schichten, vorzugsweise 1 bis 10 Schichten oder 5 bis 50 Schichten, mit der Trennschichtsuspension gedruckt, um die Trennschicht zu erhalten. Die Schichtdicke der einzelnen gedruckten Schichten in der Trennschicht liegt vorzugsweise in einem Bereich von 2 bis 200 pm, ganz besonders bevorzugt in einem Bereich von 5 bis 20 pm oder in einem Bereich von 50 bis 180 pm. Preferably, in the method according to the invention, a print head is used for printing the separating layer with the separating layer suspension which differs from the print head for printing the main suspension and/or support structure suspension. In particular, the print head for printing the separating layer suspension, in contrast to the print head for printing the main suspension and/or support structure suspension, is suitable for printing suspensions with particles with a particle size of more than 5 pm. Alternatively, however, the same print head can be used for printing the main suspension and/or support structure suspension and the separating layer suspension. This is then preferably able to print suspensions with particles with a particle size of more than 5 pm. Preferably, in step c, 1 to 50 layers, preferably 1 to 10 layers or 5 to 50 layers, are printed with the separating layer suspension in order to obtain the separating layer. The layer thickness of the individual printed layers in the separating layer is preferably in a range from 2 to 200 pm, very particularly preferably in a range from 5 to 20 pm or in a range from 50 to 180 pm.

Das Lösungsmittel ist vorzugsweise Wasser. The solvent is preferably water.

Der Gehalt an Wasser in der Hauptsuspension und/oder Stützstruktursuspension liegt vorzugsweise in einem Bereich von 10 bis 40 Gew.%. Der Gehalt an Wasser in der Trennschichtsuspension liegt vorzugsweise in einem Bereich von 10 bis 40 Gew.%. The water content in the main suspension and/or support structure suspension is preferably in a range from 10 to 40 wt.%. The water content in the separating layer suspension is preferably in a range from 10 to 40 wt.%.

Der Gehalt an Partikeln in der Hauptsuspension und/oder Stützstruktursuspension liegt vorzugsweise in einem Bereich von 60 bis 90 Gew.%. Der Gehalt an Partikeln in der Trennschichtsuspension liegt vorzugsweise in einem Bereich von 60 bis 90 Gew.%. The content of particles in the main suspension and/or support structure suspension is preferably in a range from 60 to 90 wt.%. The content of particles in the separating layer suspension is preferably in a range from 60 to 90 wt.%.

Der Gehalt an Benetzungs additiv in der Hauptsuspension und/oder Stützstruktursuspension liegt vorzugsweise in einem Bereich von 0,1 bis 2 Gew.%, insb 0,1 bis 1. Der Gehalt an Benetzungs additiv in der Trennschichtsuspension liegt vorzugsweise in einem Bereich von 0,05 bis 0,5 Gew.% (bis 1%). Vorzugsweise liegt der Gehalt an Benetzungsadditiv in der Hauptsuspension und/oder Stützstruktursuspension wenigstens 50%, ganz besonders bevorzugt wenigstens 100%, über dem Gehalt an Benetzungsadditiv in der Trennschichtsuspension. The content of wetting additive in the main suspension and/or support structure suspension is preferably in a range from 0.1 to 2% by weight, in particular 0.1 to 1. The content of wetting additive in the separating layer suspension is preferably in a range from 0.05 to 0.5% by weight (up to 1%). The content of wetting additive in the main suspension and/or support structure suspension is preferably at least 50%, very particularly preferably at least 100%, above the content of wetting additive in the separating layer suspension.

Der Gehalt an Entschäumer in der Hauptsuspension und/oder Stützstruktursuspension liegt vorzugsweise in einem Bereich von 0.01 bis 0,2 Gew.%. Der Gehalt an Entschäumer in der Trennschichtsuspension liegt vorzugsweise in einem Bereich von 0.01 bis 0,2 Gew.%. The content of defoamer in the main suspension and/or support structure suspension is preferably in a range from 0.01 to 0.2 wt.%. The content of defoamer in the separating layer suspension is preferably in a range from 0.01 to 0.2 wt.%.

In einer weiteren Ausführungsform wird die der Erfindung zu Grunde liegende Aufgabe durch ein gesintertes Teil gelöst, das durch Versinterung des erfindungsgemäßen Grünkörpers hergestellt wird, dadurch gekennzeichnet, dass die Porosität in einem Bereich von 0 bis 15 Vol.% liegt. Das gesinterte Teil kann durch die Trennschicht von der Stützstruktur leicht abgehoben werden. Die Stützstruktur wird beispielsweise mit dem Grünkörper gemeinsam gesintert. Durch das Sintern kann es bevorzugt dazu kommen, dass das Material der Trennschicht so gesintert wird, dass Grünkörper und Stützstruktur leicht voneinander getrennt werden können. In a further embodiment, the object underlying the invention is achieved by a sintered part which is produced by sintering the green body according to the invention, characterized in that the porosity is in a range from 0 to 15 vol.%. The sintered part can be easily lifted off the support structure through the separating layer. The support structure is sintered together with the green body, for example. Sintering can preferably result in the material of the separating layer being sintered in such a way that the green body and support structure can be easily separated from one another.

Vorzugsweise weicht die Porosität der gesinterten Stützstruktur weniger als 5% von der Porosität des gesinterten Teils ab. Preferably, the porosity of the sintered support structure deviates by less than 5% from the porosity of the sintered part.

Das gesinterte Teil kann alle Eigenschaften des vorgenannten Grünkörpers aufweisen, solange der Fachmann diese nicht als abwegig erachten würde. So wird man im gesinterten Teil im Unterschied zum Grünkörper keine Entschäumer mehr nachweisen können. Andererseits werden beispielsweise die Materialien der Partikel und die Partikelgrößen noch möglicherweise übereinstimmen. The sintered part can have all the properties of the green body mentioned above, as long as the expert would not consider them to be absurd. In contrast to the green body, it will no longer be possible to detect any defoamers in the sintered part. On the other hand, the materials of the particles and the particle sizes may still be the same, for example.

In einer weiteren Ausführungsform wird die der Erfindung zu Grunde liegende Aufgabe durch ein Verfahren zur Herstellung des erfindungsgemäßen gesinterten Teils gelöst, dadurch gekennzeichnet, dass man einen erfindungsgemäßen Grünkörper versintert. In a further embodiment, the object underlying the invention is achieved by a method for producing the sintered part according to the invention, characterized in that a green body according to the invention is sintered.

In einer weiteren Ausführungsform wird die der Erfindung zu Grunde liegende Aufgabe durch die Verwendung einer flüssigen Zusammensetzung enthaltend keramische oder metallische Partikel zur Herstellung einer Trennschicht zwischen einem Grünkörper und einer Stützstruktur gelöst. Die Zusammensetzung kann beispielsweise die oben beschriebene Trennschichtsuspension auch mit ihren bevorzugten Ausführungsformen sein.

Figure imgf000012_0001
In a further embodiment, the object underlying the invention is achieved by using a liquid composition containing ceramic or metallic particles for producing a separating layer between a green body and a support structure. The composition can, for example, be the separating layer suspension described above, including its preferred embodiments.
Figure imgf000012_0001

Konkret wurde eine Hauptsuspension hergestellt, die neben AI2O3 einer Korngröße im Median von 0,7pm (CT3000 SG von Almatis) ein Benetzungs-Additiv (Dolapix CE 64 von Zschimmer&Schwarz), einen temporären Binder (Optapix AC95 von Zschimmer&Schwarz) und einem Entschäumer (Contraspum KWE von Zschimmer&Schwarz) enthält. Als Dispergiermedium wurde Wasser verwendet. Die Zusammensetzung einer solchen Hauptsuspension ist in der folgenden Tabelle aufgelistet.

Figure imgf000013_0001
Specifically, a main suspension was prepared which, in addition to AI2O3 with a median grain size of 0.7pm (CT3000 SG from Almatis), contains a wetting additive (Dolapix CE 64 from Zschimmer&Schwarz), a temporary binder (Optapix AC95 from Zschimmer&Schwarz) and a defoamer (Contraspum KWE from Zschimmer&Schwarz). Water was used as a dispersing medium. The composition of such a main suspension is listed in the following table.
Figure imgf000013_0001

Diese Hauptsuspension wurde genutzt, um mittels Material Jetting ein den Grünkörper und eine Stützstruktur eines Bauteils herzustellen. Als Druckkopf wurde ein spezieller Druckkopf der Firma Durst Phototechnik AG verwendet, der in WO2013013983A1 ausführlich beschrieben ist. Dieser Druckkopf ist sehr robust gegenüber abrasiven Suspensionen wie beispielsweise keramischen Glasuren und Schlicker. Mit diesem Druckkopf lassen sich auch Suspensionen mit Partikeln mit einem Durchmesser von mehr als 45 pm verdrucken. Es können auch wasserbasierte Suspensionen mit sehr geringem Anteil an organischen Lösungsmitteln verdruckt werden. Die Stützstruktur wurde mit der gleichen Hauptsuspension hergestellt und es wurde der gleiche Druckkopf genutzt. This main suspension was used to produce a green body and a support structure of a component using material jetting. A special print head from Durst Phototechnik AG was used as the print head, which is described in detail in WO2013013983A1. This print head is very robust against abrasive suspensions such as ceramic glazes and slips. This print head can also be used to print suspensions with particles with a diameter of more than 45 pm. Water-based suspensions with a very low proportion of organic solvents can also be printed. The support structure was made with the same main suspension and the same print head was used.

Um ein Versintem des Bauteils mit der Stützstruktur zu vermeiden, wurde eine Trennschichtsuspension mit chemisch gleichem Material der Partikel, jedoch mit deutlich gröberer Korngröße hergestellt („Trennschicht“). Hierzu eignete sich ein Schmelzkorund der Größe F600 mit einer mittleren Korngröße von etwa 9 pm. Aus diesem Material wurde also eine Trennschichtsuspension hergestellt, deren Zusammensetzung in der folgenden Tabelle aufgelistet ist:

Figure imgf000014_0001
Diese Trennschichtsuspension wurde mit einem zweiten Druckkopf aufgedruckt, der mit einem zweiten Tintenversorgungssystem verbunden war. Nach dem Sintern bei 1600°C und einer Haltezeit von 2 Stunden war der Grünkörper zu einem keramischen Teil versintert, ebenso wie die Stützstruktur. Das deutlich gröbere Material zwischen dem nun versinterten Teil und Stützstruktur war nicht versintert sondern hat eine Trennschicht ausgebildet, wodurch das versinterten Teil von der Stützstruktur abgehoben werden konnte. In order to avoid sintering of the component with the support structure, a separating layer suspension was produced with the same chemical material of the particles, but with a significantly coarser grain size (“separating layer”). A fused corundum of size F600 with an average grain size of about 9 pm was suitable for this. A separating layer suspension was therefore produced from this material, the composition of which is listed in the following table:
Figure imgf000014_0001
This release layer suspension was printed with a second print head connected to a second ink supply system. After sintering at 1600°C and a holding time of 2 hours, the green body was sintered into a ceramic part, as was the support structure. The significantly coarser material between the now sintered part and the support structure was not sintered but formed a separating layer, which allowed the sintered part to be lifted off the support structure.

Das Generieren der Stützstruktur und des Grünkörpers sowie der Trennschicht wurde durch eine geeignete Software unterstützt. Insbesondere das Aufdrucken der Trennschicht zwischen Grünkörper und Stützstruktur wurde durch die Software des 3D-Druckers gesteuert. The generation of the support structure and the green body as well as the separating layer was supported by suitable software. In particular, the printing of the separating layer between the green body and the support structure was controlled by the 3D printer software.

Claims

P a t e n t a n s p r ü c h e patent claims 1. Grünkörper, der mit dem 3D-Druckv erfahren Material-Jetting in Schichten hergestellt wurde und der mit einer Stützstruktur über eine Trennschicht verbunden ist, wobei Grünkörper, Trennschicht und Stützstruktur Partikel enthalten, wobei die Partikelgröße der Partikel in der Trennschicht im Median in einem Bereich von 200% bis 10.000% der Partikelgröße der Materialpartikel im Median in der Stützstruktur liegt, und/oder die Partikelgröße der Partikel in der Trennschicht im Median in einem Bereich von 200% bis 10.000% der Partikelgröße der Materialpartikel im Median im Grünkörper liegt, wobei der Wärmeausdehnungskoeffizient des Materials der Partikel in der Trennschicht von dem Wärmeausdehnungskoeffizient des Materials der Partikel in der Stützstruktur und/oder von dem Wärmeausdehnungskoeffizient des Materials der Partikel im Grünkörper jeweils weniger als 5% abweicht, wobei das Volumen, das im Grünkörper durch Luft, Wasser und organische Substanzen eingenommen wird, in einem Bereich 5 bis 25 Vol.% liegt. 1. Green body that was produced in layers using the 3D printing process material jetting and that is connected to a support structure via a separating layer, wherein the green body, separating layer and support structure contain particles, wherein the median particle size of the particles in the separating layer is in a range from 200% to 10,000% of the median particle size of the material particles in the support structure, and/or the median particle size of the particles in the separating layer is in a range from 200% to 10,000% of the median particle size of the material particles in the green body, wherein the thermal expansion coefficient of the material of the particles in the separating layer deviates from the thermal expansion coefficient of the material of the particles in the support structure and/or from the thermal expansion coefficient of the material of the particles in the green body by less than 5%, wherein the volume taken up in the green body by air, water and organic substances is in a range from 5 to 25 vol.%. 2. Grünkörper gemäß Anspruch 1, dadurch gekennzeichnet, dass der Median der Partikelgröße der Partikel in der Trennschicht in einem Bereich von 2 bis 100 pm liegt. 2. Green body according to claim 1, characterized in that the median particle size of the particles in the separating layer is in a range from 2 to 100 pm. 3. Grünkörper gemäß Anspruch 1 oder 2, dadurch gekennzeichnet, dass die lineare Sinterschwindung der Stützstruktur sich von der linearen Sinterschwindung des Grünkörpers um weniger als 20% unterscheidet. 3. Green body according to claim 1 or 2, characterized in that the linear sintering shrinkage of the support structure differs from the linear sintering shrinkage of the green body by less than 20%. 4. Grünkörper gemäß einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die Trennschicht eine Dicke in einem Bereich von 10 bis 1000 pm aufweist. 4. Green body according to one of the preceding claims, characterized in that the separating layer has a thickness in a range of 10 to 1000 pm. 5. Verfahren zur Herstellung des Grünkörpers gemäß einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass man folgende Schritte durchführt: a. Herstellung von wenigstens einer Hauptsuspension, einer Stützstruktursuspension und einer Trennschichtsuspension von Partikeln in Lösungsmittel, wobei die Partikelgröße der Partikel in der Trennschichtsuspension im Median in einem Bereich von 200% bis 10.000% der Partikelgröße der Materialpartikel im Median in der Stützstruktursuspension liegt und/oder die Partikelgröße der Partikel in der Trennschichtsuspension im Median in einem Bereich von 200% bis 10.000% der Partikelgröße der Materialpartikel im Median in der Hauptsuspension liegt, b. Verdrucken wenigstens der Hauptsuspension und der Stützstruktursuspension mit wenigstens einem Druckkopf auf ein Substrat zu einer ersten Schicht des Grünkörpers und der Stützstruktur, c. Wiederholung des Schrittes b. solange, bis die Stützstruktur und der Grünkörper fertig gedruckt sind, wobei überall dort, wo Grünkörper und Stützstruktur aufeinandertreffen, ein oder mehrere Schichten der Trennschichtsuspension gedruckt werden, so dass eine Trennschicht entsteht, wobei der Wärmeausdehnungskoeffizient des Materials der Partikel in der Trennschichtsuspension von dem Wärmeausdehnungskoeffizient des Materials der Partikel in der Stützstruktursuspension und/oder von dem Wärmeausdehnungskoeffizient des Materials der Partikel in der Hauptsuspension jeweils weniger als 5% abweicht. 5. Process for producing the green body according to one of claims 1 to 4, characterized in that the following steps are carried out: a. Production of at least one main suspension, a support structure suspension and a separating layer suspension of particles in solvent, wherein the median particle size of the particles in the separating layer suspension is in a range from 200% to 10,000% of the median particle size of the material particles in the support structure suspension and/or the median particle size of the particles in the separating layer suspension is in a range from 200% to 10,000% of the median particle size of the material particles in the main suspension, b. Printing at least the main suspension and the support structure suspension with at least one print head onto a substrate to form a first layer of the green body and the support structure, c. Repeating step b. until the support structure and the green body are completely printed, whereby wherever the green body and the support structure meet, one or more layers of the separating layer suspension are printed so that a separating layer is formed, whereby the thermal expansion coefficient of the material of the particles in the separating layer suspension deviates from the thermal expansion coefficient of the material of the particles in the support structure suspension and/or from the thermal expansion coefficient of the material of the particles in the main suspension by less than 5%. 6. Verfahren gemäß Anspruch 5, dadurch gekennzeichnet, dass Hauptsuspension und Trennschichtsuspension ein Benetzungsadditiv enthalten und der Gehalt an Benetzungs additiv in der Hauptsuspension wenigstens 50% über dem Gehalt an Benetzungs additiv in der Trennschichtsuspension liegt. 6. Process according to claim 5, characterized in that the main suspension and the separating layer suspension contain a wetting additive and the content of wetting additive in the main suspension is at least 50% above the content of wetting additive in the separating layer suspension. 7. Verfahren gemäß Anspruch 5 oder 6, dadurch gekennzeichnet, dass in Schritt c 1 bis 50 Schichten, vorzugsweise 1 bis 10 Schichten oder 5 bis 50 Schichten, mit der Trennschichtsuspension gedruckt werden, um die Trennschicht zu erhalten. 7. The method according to claim 5 or 6, characterized in that in step c 1 to 50 layers, preferably 1 to 10 layers or 5 to 50 layers, are printed with the release layer suspension in order to obtain the release layer. 8. Gesintertes Teil, hergestellt durch Versinterung des Grünkörpers gemäß einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass die Porosität in einem Bereich von 0 bis 15 Vol.% liegt. 8. Sintered part produced by sintering the green body according to one of claims 1 to 4, characterized in that the porosity is in a range of 0 to 15 vol.%. 9. Verfahren zur Herstellung des gesinterten Teils gemäß Anspruch 8, dadurch gekennzeichnet, dass man einen Grünkörper gemäß einem der Ansprüche 1 bis 4 versintert. 9. A process for producing the sintered part according to claim 8, characterized in that a green body according to one of claims 1 to 4 is sintered. 10. Verwendung einer flüssigen Zusammensetzung enthaltend keramische oder metallische Partikel zur Herstellung einer Trennschicht zwischen einem10. Use of a liquid composition containing ceramic or metallic particles for producing a separating layer between a Grünkörper und einer Stützstruktur. green body and a support structure.
PCT/EP2024/025098 2023-04-07 2024-02-29 Support structure for material jetting Pending WO2024208450A1 (en)

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