Build platforms for use with additive manufacturing devices

Abstract

The present disclosure provides a build platform for use in an additive manufacturing device that builds an object with layers of photocurable resin, the build platform comprising a build surface for building an object thereon, the build surface comprising a ceramic material. The present disclosure also provides a method for manufacturing a build surface comprising a ceramic surface. Further, the present disclosure provides an additive manufacturing device including a build platform comprising a ceramic material. The present disclosure also describes articles made using the described methods and devices.

Description

[Technical Field]

[0001] This disclosure relates, in general terms, to a build platform having a ceramic surface for use in additive manufacturing devices. The invention also relates to a method of using such a device. The invention also relates to articles prepared by using such an additive manufacturing device, including a build platform having a ceramic surface. [Background technology]

[0002] The additive manufacturing process typically allows for the construction of an object into its desired individual shape by continuously adding material, for example, in continuous layers. In contrast, subtractive manufacturing processes include cases where an object is machined from a large blank by removing material. In some technical fields, physical objects or mechanical workpieces are increasingly being manufactured by additive manufacturing processes as technology advances.

[0003] Several additive manufacturing processes are based on stereolithography. Stereolithography generally uses light to cure photocurable or photopolymerizable resins. Data based on computer-aided design and / or computer-aided manufacturing (CAD / CAM) is used to project a light pattern onto a layer of photocurable resin. The photosensitive resin typically solidifies upon exposure to light, forming a layer of cured resin according to the desired pattern. For example, selectively applying energy to a photopolymerizable (photocurable) composition in a container (tank) may include applying chemical beams such as ultraviolet light, visible radiation, electron beam radiation, or any combination thereof, that have sufficient energy to cure the photopolymerizable composition. Those skilled in the art can select a suitable radiation source and wavelength range for a particular application without excessive experimentation.

[0004] By continuously adding layers, the desired three-dimensional object is created. Therefore, the pattern is controlled according to the desired shape of the three-dimensional object.

[0005] While additive manufacturing processes are widely used in the industry for rapid prototyping, the production of finished products remains challenging in many areas. Some materials used in rapid prototyping are not intended for contact with the human body. However, when manufacturing dental articles using additive manufacturing processes, it is necessary to ensure that the materials used do not contain any substances that could be harmful to the patient. In addition, the environment in which dental articles are manufactured must meet certain hygiene requirements to prevent the dental articles from being contaminated with unwanted substances.

[0006] While methods exist for fabricating dental articles using additive manufacturing, there is still a need for devices that help minimize cross-contamination with unwanted materials during the additive manufacturing process of dental articles. [Overview of the Initiative]

[0007] This disclosure relates to an additive manufacturing device, a build platform, and a method of using the same for constructing an object with layers of photocurable resin. In one embodiment, this disclosure relates to a build platform for use in an additive manufacturing device for constructing an object with layers of photocurable resin. The build platform comprises a build surface on which an object is constructed, the build surface comprising a ceramic material. In another embodiment, this disclosure relates to an additive manufacturing device for constructing an object with layers of photocurable resin. The additive manufacturing device comprises a build carrier, a light source for emitting light toward a modeling plate, the build carrier and the light source being movable toward each other, and a build platform comprising a build surface on which an object is constructed, the build surface being formed of a plurality of blocks including a ceramic build surface, each block having a flat surface portion extending in a common plane, and a plurality of spaced flat surface portions forming the build surface. This disclosure relates to a method for manufacturing a build platform for use in an additive manufacturing device for constructing an object with layers of photocurable resin on a build surface formed by the build platform. The method comprises providing a plurality of ceramic surface-finished block precursors and sandblasting the surface of each block precursor so that the sandblasted surface forms a surface portion of the build surface. The disclosure relates to constructing an object with a layer of photocurable resin. In some embodiments, the object may be a dental article. Examples of dental articles include crowns (including monolithic crowns), bridges, inlays, onlays, veneers, veneeres, copings, crown and bridge frameworks, implants, piercing teeth, orthodontic appliances (e.g., brackets, buccal tubes, cleats, attachments and buttons) and parts thereof. The surface of a tooth is not considered a dental article. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view of an additive manufacturing device according to one embodiment of the present invention. [Figure 2] This is a perspective view of a build platform according to one embodiment of the present invention, mounted on the build carrier of an additive manufacturing device. [Figure 3] This is a perspective view of a ceramic block according to one embodiment of the present invention. [Figure 4] Figure 3 is a perspective view of a slot nut for use with a ceramic block. [Figure 5] This is a perspective view of the ceramic block in Figure 3, combined with the slot nut in Figure 4. [Figure 6] Figure 3 is a perspective view of the ceramic block combined with the slot nut shown in Figure 4 in a different way. [Figure 7] This is a perspective view of a build platform according to one embodiment of the present invention, without a ceramic block. [Modes for carrying out the invention]

[0009] The present invention relates to a build platform for use in additive manufacturing devices. In some embodiments, the build platform for use in additive manufacturing devices may be particularly useful for the manufacture of dental articles. Examples of dental articles include crowns (including monolithic crowns), bridges, inlays, onlays, veneers, veneeres, copings, crown and bridge frameworks, implants, piercing teeth, orthodontic appliances (e.g., brackets, buccal tubes, cleats, attachments and buttons) and parts thereof. The surface of a tooth is not considered a dental article. Such additive manufacturing devices are based on constructing objects in layers with layers made of photocurable resin. Furthermore, the present invention relates to an additive manufacturing device comprising a build platform. The build platform comprises a build surface on which articles are constructed. In one embodiment, the build surface is preferably formed of a ceramic material. In one embodiment, the build surface comprises zirconia (ZrO2).

[0010] The present invention has certain advantages in that it provides an additive manufacturing device and method that can remove residual photocurable resin or cured resin from the build surface with minimal effort. This minimizes the amount of residual photocurable resin or cured resin present on the used build surface used to construct any further objects. Therefore, cross-contamination between residual photocurable resin or cured resin and new photocurable resin can be minimized. The present invention is even more advantageous in that it provides a build surface that is more durable than a build surface made of metal.

[0011] Glossary: As used herein, “ceramics” or “ceramic articles” refers to nonmetallic materials produced by the application of heat, including amorphous materials, glass, crystalline ceramics, glass ceramics, and combinations thereof. Ceramics are generally classified as inorganic materials. The term “amorphous material” refers to a material that lacks a long-period crystalline structure determined by X-ray diffraction and / or has an exothermic peak corresponding to the crystallization of amorphous materials, determined by DTA (differential thermal analysis). The term “glass” refers to an amorphous material that exhibits a glass transition temperature. The term “glass ceramic” refers to a ceramic that contains crystals formed by heat treatment of an amorphous material. The term “crystalline ceramic” refers to a ceramic material that exhibits an identifiable X-ray powder diffraction pattern. “Crystalline” means a solid composed of atoms arranged in a three-dimensional periodic pattern (i.e., having a long-period crystalline structure that can be determined by techniques such as X-ray diffraction). “Microcrystalline” means a crystalline domain of a solid having a defined crystalline structure. Microcrystalline can have only one crystalline phase.

[0012] As used herein, "ceramic particles" refers to non-metal materials including particles of amorphous materials, glass, crystalline ceramics, glass ceramics, and combinations thereof, which are produced by the application of heat or by a chemical synthesis process. Ceramic particles are typically classified as inorganic materials. The term "amorphous material" with respect to ceramic particles refers to materials derived from a molten phase and / or a gaseous phase, as well as materials made from chemical synthesis, which have no long-period crystal structure determined by X-ray diffraction and / or have an exothermic peak corresponding to the crystallization of the amorphous material determined by DTA (differential thermal analysis). For example, amorphous silica nanoparticles can be produced by condensing silanes to form nanoparticles.

[0013] As used herein, "additive manufacturing" means a process used to manufacture three-dimensional articles. An example of an additive manufacturing technique is stereolithography (SLA), in which successive layers of material are placed under computer control. The article can be of almost any shape or form and is made from a three-dimensional model or other electronic data source.

[0014] As used herein, "sol" refers to a continuous liquid phase containing discrete particles having a size in the range of 1 nanometer (nm) to 100 nm.

[0015] As used herein, "slurry" refers to a continuous liquid phase containing discrete particles having a size in the range of greater than 100 nm to 50 micrometers, or greater than 100 nm to 10 micrometers. The slurry may optionally further contain discrete particles having a size in the range of 1 nanometer (nm) to 100 nm.

[0016] As used herein, "powder" refers to a dry bulk material composed of a large number of fine particles that can flow freely when shaken or poured.

[0017] As used herein, "particle" refers to a substance that is a solid having a geometrically definable shape. The shape may be regular or irregular. Particles can typically be analyzed, for example, with respect to particle size and particle size distribution. A particle can comprise one or more microcrystals. Thus, a particle can comprise one or more crystal phases.

[0018] As used herein, "associated" refers to a group of two or more primary particles that are aggregated and / or agglomerated. Similarly, the term "non-associated" refers to two or more primary particles that are not aggregated and / or agglomerated or are substantially not aggregated and / or agglomerated.

[0019] As used herein, "aggregation" refers to a strong association of two or more primary particles. For example, the primary particles can be chemically bonded to each other. Generally, it is difficult to divide an aggregate into smaller particles (e.g., primary particles).

[0020] As used herein, "agglomeration" refers to a weak association of two or more primary particles. For example, the particles can be held together by charge or polarity. Dividing an agglomerate into smaller particles (e.g., primary particles) is not as difficult as dividing an aggregate into smaller particles.

[0021] As used herein, "primary particle size" refers to the size of a non-associated single crystalline ceramic particle or a single amorphous ceramic particle, and this particle is regarded as a primary particle. To measure the primary particle size, typically X-ray diffraction (XRD) is used for crystalline particles and transmission electron microscopy (TEM) is used for amorphous particles.

[0022] As used herein, "substantially spherical" means that the shape of the particle is close to a sphere. This particle does not include sharp edges resulting from milling processes.

[0023] As used herein, "soluble" means that the component (e.g., a solid) can be completely dissolved in a solvent. That is, when dispersed in water at 23°C, the substance can form individual molecules (such as glucose) or individual ions (such as sodium chloride). However, the solubilization process may take some time, for example, requiring the component to be stirred for several hours (e.g., 10-20 hours).

[0024] As used herein, "density" means the ratio of the mass of an object to its volume. The unit of density is typically grams per cubic centimeter (g / cm³). 3 The density of an object can be calculated, for example, by determining the volume of the object (for example, by calculation or by applying Archimedes' principle or method) and measuring the mass of the object. The volume of a sample can be determined based on the overall external dimensions of the sample. The density of a sample can be calculated from the measured sample volume and sample mass. The total volume of a material sample can be calculated from the sample mass and the density of the material used. The total volume of bubbles in a sample is assumed to be the remainder of the sample volume (100% minus the total volume of the material).

[0025] As used herein, "theoretical density" refers to the maximum possible density obtainable in a sintered article if all pores were removed. The percentage of the theoretical density of a sintered article can be determined, for example, from an electron microscope image of a cross-section of the sintered article. From the electron microscope image, the percentage of the area that can be attributed to pores in the sintered article can be calculated. In other words, the percentage of the theoretical density can be calculated by subtracting the percentage of voids from 100%. That is, if 1 percent of the area of ​​the electron microscope image of the sintered article can be attributed to pores, the sintered article is considered to have a density equal to 99 percent of the theoretical density. Density can also be determined by the Archimedes method.

[0026] As used herein, “porous material” in the art of ceramics refers to a material that contains partial volumes formed by voids, pores, or bubbles. Therefore, the “open-celled” structure of a material may be called an “open-porous” structure, and the structure of a “closed-celled” material may be called a “closed-porous” or “non-porous” structure. It may also be found that in this art, the term “pore” may be used instead of “bubble.” The material structural classifications of “open-celled” and “closed-celled,” or “porous” and “non-porous,” can be determined according to DIN 66133 for various porosities measured for various material samples (e.g., using the mercury “Poremaster 60-GT” from Quantachrome Inc., USA). Materials having an open-celled or open-porous structure can, for example, allow gas to pass through.

[0027] As used herein, “heat treatment,” “calcination,” “binder burnout,” or “debindering” refers to a process of heating a solid material to remove at least 90 percent by weight of volatile chemically bound components (e.g., organic components), in contrast to drying, which removes physically bound water by heating. The heat treatment is carried out at a temperature lower than the temperature required to carry out the sintering process.

[0028] As used herein, “sintering” and “firing” are used interchangeably. Porous (e.g., pre-sintered) ceramic articles shrink during the sintering process, i.e., when an appropriate temperature is applied. The applied sintering temperature varies depending on the selected ceramic material. Sintering typically involves densifying a porous material into a less porous material (a material with fewer bubbles), or essentially into a “non-porous” material with high density. In some cases, sintering may also involve a change in the material phase composition (e.g., a partial conversion from an amorphous phase to a crystalline phase).

[0029] As used herein, “gel,” “gelled article,” and “gelled body” are used interchangeably and refer to a three-dimensional gel resulting from the curing reaction of polymerizable components contained in a slurry or sol containing an organic binder and a solvent.

[0030] As used herein, “raw material / green material” means an unsintered ceramic product, typically a ceramic product containing an organic binder.

[0031] As used herein, “pre-sintered” ceramic articles are those from which the solvent and binder have been removed and which exhibit a density of less than 93% of their theoretical density.

[0032] As used herein, “geometrically defined article” means an article whose shape can be described using geometric terms, such as two-dimensional terms like circle, square, and rectangle, and three-dimensional terms like layer, cube, cube-like, and sphere.

[0033] As used herein, “dental articles” means articles that can or will be used in the field of dentistry or orthodontics, in particular, for the manufacture of dental restorations, dental models, and parts thereof, or as such. Examples of dental articles include crowns (including monolithic crowns), bridges, inlays, onlays, veneers, veneeres, copings, crown and bridge frameworks, implants, piercing teeth, orthodontic appliances (e.g., brackets, buccal tubes, cleats, and buttons) and parts thereof. The surface of a tooth is not considered a dental article.

[0034] In the context of this invention, a material or composition is considered "essentially free" or "substantially free" of a particular component if it does not contain that component as an essential characteristic. Therefore, the component is not intentionally added to the composition or material, either by itself or in combination with other components or raw materials of other components. A composition or material that is essentially free of a particular component typically contains that component in amounts of less than about 1% by weight, less than about 0.1% by weight, or less than about 0.01% by weight (or less than about 0.05 moles per liter of solvent, or less than about 0.005 moles per liter of solvent, or less than about 0.0005 moles per liter of solvent) relative to the entire composition or material. Ideally, the composition or material would contain no of the component at all. However, it may be unavoidable that small amounts of the component are present, for example, due to impurities.

[0035] As used herein, "hardenable" refers to a material or composition that can be hardened or solidified by, for example, heating to remove a solvent, heating to induce polymerization, chemical crosslinking, radiation-induced polymerization, or crosslinking.

[0036] As used herein, “hardening” means hardening or partial hardening of a composition by any mechanism, such as heat, light, radiation, electron beam, microwave, chemical reaction, or a combination thereof.

[0037] As used herein, “cured” refers to a material or composition that has been hardened or partially hardened by curing (e.g., polymerized or crosslinked).

[0038] As used herein, “integral” means that they are manufactured simultaneously, or that it is impossible to separate one or more of the (integral) parts, e.g., “unitary,” without damaging them.

[0039] As used herein, "(meth)acrylate" is an abbreviation for acrylate, methacrylate, or a combination thereof; "(meth)acrylic" is an abbreviation for acrylic, methacrylic, or a combination thereof; and "(meth)acrylic" is an abbreviation for acrylic and methacrylic groups. "Acrylic" refers to derivatives of acrylic acid, such as acrylate, methacrylate, acrylamide, and methacrylamide. "(meth)acrylic" means a monomer or oligomer having at least one acrylic or methacrylic group, which, if it contains two or more groups, is linked by an aliphatic segment. As used herein, "(meth)acrylate-functional compound" is, in particular, a compound containing a (meth)acrylate moiety.

[0040] As used herein, "non-crosslinkable" refers to a polymer that does not crosslink when exposed to chemical radiation or high heat. Typically, a non-crosslinkable polymer is an unfunctionalized polymer that lacks functional groups that are involved in crosslinking.

[0041] As used herein, the terms “polymerizable slurry or sol,” “polymerizable composition,” and “photocurable resin” are used interchangeably and mean a curable composition that can be polymerized at initiation (e.g., at the initiation of free radical polymerization). Typically, prior to polymerization (e.g., hardening), the polymerizable slurry / sol or polymerizable composition has a viscosity profile that matches the requirements and parameters of one or more additive manufacturing (e.g., 3D printing) systems. In some embodiments, hardening, for example, involves irradiating the “photopolymerizable slurry or sol” with a chemical beam having sufficient energy to initiate a polymerization or crosslinking reaction. For example, in some embodiments, ultraviolet (UV) radiation, visible radiation, electron beam radiation, or a combination thereof can be used.

[0042] As used herein, “resin” includes all polymerizable components (monomers, oligomers, and / or polymers) present in a curable slurry / sol or curable composition. A resin may contain only one polymerizable component compound or a mixture of different polymerizable compounds.

[0043] As used herein, “sintered article” refers to a gelled article that has been dried, heated to remove the organic matrix, and then further heated to reduce porosity and increase density. The density after sintering is at least 40 percent of the theoretical density. Articles with densities in the range of 40 to 93 percent of the theoretical density are typically open-porous (pores open to the surface, “porous”). Above 93 percent or 95 percent of the theoretical density, typically closed-pore, “non-porous” (no pores open to the surface) are present.

[0044] As used herein, "thermoplastic" refers to a polymer that flows when heated well above its glass transition temperature and becomes solid when cooled.

[0045] As used herein, "heat-set" refers to a polymer that is permanently set upon curing and does not flow upon subsequent heating. Heat-set polymers are typically crosslinked polymers.

[0046] The terms “preferred” and “preferably” refer to embodiments of the disclosure that can provide a particular benefit under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unhelpful, nor is it intended to exclude other embodiments from the scope of the disclosure.

[0047] In this application, terms such as “a,” “an,” and “the” are not intended to refer only to singular entities, but include general classifications, and specific examples thereof may be used for illustrative purposes. The terms “a,” “an,” and “the” are used interchangeably with the term “at least one.” The phrases “at least one of” and “including at least one of” following an enumeration refer to any one item in the enumeration, or any combination of two or more items in the enumeration.

[0048] As used herein, the term "or" is used in its ordinary sense, generally including "and / or," unless otherwise specified. The term "and / or" means one or all of the enumerated elements, or any combination of two or more of the enumerated elements.

[0049] Furthermore, in this specification, all numbers are assumed to be modified with the term “approximately,” and preferably with the term “exactly.” When used herein, in relation to a measured quantity, the term “approximately” refers to the variation in the measured quantity that can be predicted by a person skilled in the art who performs the measurement and exercises a level of care commensurate with the purpose of the measurement and the precision of the measuring instrument used. Moreover, in this specification, the description of a numerical range by endpoints includes all numbers and their endpoints that are contained within that range (for example, 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, 5, etc.).

[0050] When used herein as a modifier for a characteristic or attribute, the term “generally” means, unless otherwise specified, that the characteristic or attribute is readily recognizable to a person skilled in the art, but does not require absolute precision or perfect agreement (e.g., within ±20% for quantifiable characteristics). The term “substantially” means, unless otherwise specified, a high degree of approximation (e.g., within ±10% for quantifiable characteristics), but again, does not require absolute precision or perfect agreement. Terms such as identical, equal, uniform, constant, and strictly are understood to mean that they do not require absolute precision or perfect agreement, but are within the normal tolerance or measurement error applicable to the particular situation.

[0051] In one embodiment, the build surface containing the ceramic material has a non-porous material structure. This preferably means that the build surface contains a sintered ceramic obtained or obtainable from sintering a ceramic green body to its full density. In some embodiments, the sintered ceramic material contains sintered zirconia (ZrO2).

[0052] In another embodiment, the build surface is provided by a plurality of spaced-apart flat surface portions. Thus, the build platform may comprise a plurality of spaced-apart flat surface portions that combine to form a build surface. The plurality of surface portions, and therefore the build surface, preferably extend within a common plane.

[0053] In yet another embodiment, a gap is formed between adjacent surface portions. The gap preferably has a width in the dimensions of a common plane and a depth in the dimensions perpendicular to the common plane. For example, the width may be defined by the shortest distance between two adjacent surface portions.

[0054] In another embodiment, the surface portions are rectangular or square in shape. In this embodiment, the surface portions may be spaced at uniform distances from each other. Thus, one or more gaps of uniform width are formed. Each surface portion may generally be polygonal, for example, square or rectangle. However, each surface portion may be hexagonal, triangular, or any other suitable shape, with gaps of uniform width placed between them.

[0055] In yet another embodiment, the depth of the gap between adjacent surface portions exceeds 1 mm. Furthermore, the width of the gap may exceed 8 mm. Furthermore, the width of the gap may be 20 mm. The amount of photocurable resin that can be accepted in the gap can be determined by determining the depth and width of the gap.

[0056] In other embodiments, each surface portion has a surface roughness Ra of 0.5–1.25 μm or a surface roughness Rz of 10–20 μm. Such surface roughness has been found to provide sufficient retention between the constructed article and the build surface, and furthermore, to allow for maximum cleaning of the build surface.

[0057] In one embodiment, the surface portion is provided by a plurality of ceramic blocks. Specifically, each of the plurality of ceramic blocks may have a surface corresponding to one of the surface portions. The ceramic blocks are preferably made of ceramic only. In some embodiments, the ceramic blocks include zirconia (ZrO2).

[0058] In yet another embodiment, each ceramic block has one or more recesses extending into the ceramic block from the opposite side of the surface portion. At least one or more of the recesses may be V-shaped or T-shaped. Thus, the ceramic block can be fixed to the additive manufacturing device by using threaded slot nuts that engage with the recesses. One or more of the recesses may be cylindrical to receive threaded inserts. This makes it possible to fix the ceramic block to the additive manufacturing device by using screws.

[0059] In another embodiment, the ceramic blocks are spaced apart from each other to provide a desired gap between them. The ceramic blocks are preferably individually removable from the additive manufacturing device. This allows the ceramic blocks to be cleaned individually. For example, the ceramic blocks may be cleaned by heating or burning at a specific temperature. The temperature selected depends on the ceramic block composition and the resin composition. For example, the temperature may exceed 1000°C. The temperature should be selected so that the residual photocurable resin or cured resin burns typically without residue or essentially without residue.

[0060] In one embodiment, the present invention also relates to an additive manufacturing device for constructing articles in layers of a photocurable resin. The additive manufacturing device comprises a build carrier, a tank or container, and a light source for emitting light toward the build carrier, wherein the tank container is of appropriate size and consists of one or more materials selected to contain a liquid photocurable resin. The build carrier and the light source are movable relative to each other. Furthermore, the additive manufacturing device comprises a build platform. This build platform corresponds to the build platform of the present invention, although the additive manufacturing device may be configured to operate on a different build platform. The build platform comprises a build surface for constructing an article thereon. The build surface is formed of or contains a ceramic material. Furthermore, the build surface may be provided by a plurality of spaced flat surface portions extending in a common plane. The surface portions may be provided by a plurality of ceramic blocks. The ceramic preferably has a non-porous material structure. For example, the ceramic may be sintered to full density. Gaps may be formed between adjacent surface portions. The gap may have a width in the dimensions of the common plane and a depth in the dimensions perpendicular to the common plane. As defined above, each surface portion may be polygonal, specifically square or rectangular. In some embodiments, the depth of the gap is greater than 1 mm. In other embodiments, the depth of the gap may be greater than 8 mm, for example, 20 mm. As defined above, each surface portion may have a surface roughness Ra of 0.5 to 1.25 μm or a surface roughness Rz of 10 to 20 μm.

[0061] The ceramic material of the build surface preferably has a non-porous material structure, typically produced by sintering the ceramic to full density. For example, a sintering process is carried out to obtain a ceramic build surface or ceramic block article having a “full” density of 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, 99.5% or more, or 99.9% or more of the theoretical density of the selected ceramic material. Heating and pre-sintering processes may be performed as necessary, depending on the ceramic material used. Following any necessary pre-sintering or heating steps, the sintering of porous ceramic articles is typically carried out under the following conditions: temperature: 900°C to 2300°C, 100°C to 2000°C, 2050°C to 2300°C, or 1800°C to 2100°C; or above 900°C, above 1200°C, above 1400°C, above 1600°C, or above 1900°C; and below 2300°C, below 2250°C, below 2200°C, below 2150°C, below 2100°C, below 2050°C, or below 2000°C; atmospheric / environmental conditions: air or inert gas (e.g., nitrogen, argon); pressure: atmospheric pressure (e.g., 10¹³ mbar); and duration: until the material reaches a density of 94% to 100% of its final density. Instead of atmospheric pressure, sintering may be carried out under high or low pressure.

[0062] Each ceramic block may have one or more recesses extending into the ceramic block from the opposite side of the surface portion. The ceramic blocks are preferably spaced apart from one another to provide gaps between them. The ceramic blocks are preferably removablely attached to the build carrier of the additive manufacturing device.

[0063] In a further embodiment, the present invention relates to a method for manufacturing a build platform for use in an additive manufacturing device to construct layers of articles made of photocurable resin on a build surface formed by the build platform. The method includes the steps of providing at least one ceramic block precursor made of ceramic (hereinafter referred to as "ceramic block precursor"), or a plurality of ceramic block precursors made of ceramic (hereinafter referred to as "ceramic block precursor"). Furthermore, the method may include the step of sandblasting the surface of each ceramic block precursor. The sandblasted surface preferably forms the surface portion of the build surface. The sandblasting step may include the use of sand made of Al2O3, which is commercially available from BEGO Bremer, Goldschlagerei Wilh.Herbst GmbH&Co.KG in Bremen, Germany.

[0064] The method may further include the steps of providing one or more green bodies made of pressurized ceramic powder, and sintering the one or more green bodies to or toward full density, thereby providing a ceramic block precursor. The method may further include the steps of milling one or more recesses into the one or more green bodies.

[0065] Figure 1 shows an additive manufacturing device 1 that can be used with the present invention. The additive manufacturing device 1 is configured to construct a physical object with a photocurable resin. In this embodiment, the object is formed of a plurality of dental articles 100 constructed of a photocurable resin 11. In this embodiment, a plurality of dental crowns are shown, but the dental articles may further include, for example, a dental bridge, a dental inlay, or one or more replacement teeth. In addition, the articles 100 may be any three-dimensional object made by continuously adding layers, and are not necessarily or exclusively dental articles. For example, the articles 100 may hereafter be referred to as dental articles.

[0066] As shown in the figure, the additive manufacturing device 1 includes a tank 3 into which a photocurable resin 11 can be supplied. To supply the photocurable resin, the additive manufacturing device 1 may have one or more tanks (not shown) for storing the photocurable resin and means for dispensing the amount of photocurable resin into the tank 3. The photocurable resin may be supplied selectively in various colors as desired. The photocurable resin is also commonly called a photopolymerizable resin in the field of dental materials. The photocurable resin has a liquid or paste-like (and therefore fluid) viscosity. The tank 3 has a light-transmitting base 2. In this example, the entire tank 3 is made of a transparent material. Suitable materials for the tank 3 include, for example, silica glass or polycarbonate. Other materials are also possible, as is known to those skilled in the art.

[0067] The tank 3 is generally cup-shaped. In particular, the tank 3 has a bottom wall 3a and side walls 3b, with an opening formed on the opposite side of the bottom wall 3a. In this embodiment, the tank 3 is generally rectangular (having rectangular side walls), but it may have other shapes.

[0068] The additive manufacturing device 1 is generally configured to construct one or more objects by stereolithography. Stereolithography provides a method for constructing a physical object (or a number of articles 100) by sequentially curing portions, specifically layers, made of a photocurable resin. Thus, each constructed layer consists of cured resin. The cured resin is solid and does not have fluidity. The dimension in which the layers are “laminated” or provided on top of each other is referred to herein as the “build dimension” and is shown as “B” in the figure. The shape in the remaining two dimensions is controlled by the shape of each layer made of cured resin.

[0069] The shape of individual layers made of cured resin is determined by exposure of selected portions of the layers made of photocurable resin. This is performed by a light source 5, which is an image projector in the illustrated example. The image projector is controlled by a computer based on a three-dimensional virtual object virtually sliced ​​into layers of desired thickness (provided with an image). The image projector may also be based on Digital Light Processing (DLP). Digital Light Processing (DLP) uses micromirrors arranged in a matrix on a semiconductor chip. Such semiconductor chips are known as Digital Micromirror Devices (DMDs). The mirrors of a typical DMD have a size of about 5 μm or less. Each mirror is movable between two positions by semiconductor control. In one position, the mirror is positioned to reflect light directed onto the mirror through the light output, and in the other position, the mirror is positioned so that light directed onto the mirror does not leave the projector. Each mirror typically represents one pixel in the projected image, and therefore the number of mirrors usually corresponds to the resolution of the projected image. Those skilled in the art will recognize that other projector technologies or laser beams can be similarly used in the additive manufacturing device of the present invention.

[0070] The light source 5 is positioned below the light-transmitting region 7 of the additive manufacturing device 1. The light-transmitting region 7 is positioned roughly horizontally (perpendicular to the direction of gravity), and the light source 5 is positioned toward the center of gravity of the light-transmitting region 7. In this embodiment, the light-transmitting region 7 is provided within the housing 6 of the additive manufacturing device 1. The tank 3 is detachably positioned such that its light-transmitting base 2 is on the light-transmitting region 7. Thus, the light emitted by the light source 5 and transmitted through the light-transmitting region 7 of the housing 6 also transmits through the light-transmitting base 2 of the tank 3. Furthermore, because the tank 3 is detachably positioned within the additive manufacturing device 1, the tank 3 can be replaced with another tank, for example, a tank for use with a different color of photocurable resin.

[0071] The light-transmitting region 7 and the light-transmitting base 2 are preferably transparent and free from clouding. Therefore, the image sharpness of the image projected onto the light-transmitting base can be maximized. This also forms the basis for constructing the object with the highest precision. Note that in another example, the light-transmitting region and the light-transmitting base may be combined as a single unit.

[0072] The additive manufacturing device 1 includes a build carrier 4. The build carrier 4 is located on the side of the light-transmitting region 7 opposite to the light source 5. In one embodiment, the build carrier 4 is configured to build objects directly on it. In another embodiment, the build carrier 4 is provided with a plurality of ceramic blocks 13 on which dental articles 100 are built, as described in more detail below.

[0073] The build carrier 4, along with the multiple ceramic blocks 13, can be positioned relative to the light-transmitting base 2 (and light-transmitting region 7) by computer control. The build carrier 4 having the multiple ceramic blocks 13 is movable to at least the build dimension B. In another embodiment, the build carrier may be movable to one or two dimensions perpendicular to the build dimension B.

[0074] Article 100 is constructed within the additive manufacturing device 1 to build dimension B. Specifically, the construction process is performed downward (in the direction of Earth's gravity) relative to the initially fabricated part or layer of the object. This is achieved because, as the dental article 100 is constructed, the additive manufacturing device 1 continuously pulls the dental article 100 upward (away from the Earth's center of gravity and away from the light-transmitting region 7).

[0075] The build carrier 4 is connected to a linear drive 9 via a support 8. In this embodiment, the linear drive 9 has a spindle (not shown) mechanically coupled to the support 8, and the support 8 is movable between two dimensions within the build dimension B. The linear drive 9 further includes a motor 10 and a position measuring device. Thus, the support 8 and the attached build carrier 4 can be precisely positioned by control of the additive manufacturing device 1 via computer numerical control (CNC). Those skilled in the art will recognize that in another embodiment, the support 8 itself can be configured as the build carrier. Furthermore, those skilled in the art will recognize that the build carrier 4 can be connected to the linear drive by other means. Furthermore, drives other than spindle drives are also possible. In addition, those skilled in the art will recognize that the support 8, carrier 4, build platform, and build surface may be integral, i.e., formed or manufactured simultaneously or from the same material, or it may be impossible to separate one or more integral parts without damaging them. For example, in some embodiments, one or more of the support 8, carrier 4, build platform, or build surface include the ceramic material according to the present disclosure.

[0076] As shown in Figure 1, the dental article 100 is constructed within the additive manufacturing device 1. Generally, the dental article 100 is constructed in the region between the build carrier 4, specifically the ceramic block 13, and the light-transmitting base 2. The dental article 100 is supported by the ceramic block 13 via a support structure 103, with the ceramic block 13 attached to the build carrier 4.

[0077] A photocurable resin 11 is supplied into the tank 3. The amount of photocurable resin 11 is selected so that a bath is formed with a predetermined filling height of photocurable resin. A build carrier 4 containing the ceramic block 13 is positioned (not shown) such that the ceramic block 13 is immersed in the bath of photocurable resin but is still spaced apart from the light-transmitting base 2. At this stage, an image projector 5 can be used to radiate light through the light-transmitting base 2 onto the photocurable resin 11 present in the space between the light-transmitting base 2 and the ceramic block 13. The light is preferably radiated in the form of a two-dimensional pattern in a plane parallel to the light-transmitting base 2. Thus, the photocurable resin 11 is irradiated locally according to the shape of the light pattern. Specifically, any light pixel in the pattern cures the portion of the photocurable resin 11 exposed to the light of that light pixel. Since the photocurable resin 11 is typically somewhat light-transmitting, the light completely penetrates the layer formed by the photocurable resin 11. Therefore, the curing of the photocurable resin creates portions (specifically layers) made of the cured resin. These portions of cured resin are built up continuously on top of each other, becoming part of an increasingly complementary object. From this stage, the complementary object can be set back from the light-transmitting base 2, thereby creating new spaces filled with uncured photocurable resin. The uncured photocurable resin can then be exposed to further light patterns to further complement the object, and this continues until the object is fully constructed layer by layer.

[0078] The ceramic block 13 is provided with a retaining surface facing the light-transmitting region 7. The retaining surface provides a force to hold the hardened resin, and therefore adheres the dental article 100 to the ceramic block 13. The force holding the hardened resin is greater than the force holding the hardened resin on the light-transmitting base 2. Therefore, when the object is pulled away from the light-transmitting base, the object is separated from the light-transmitting base but remains held in place by the ceramic block 13.

[0079] The light-transmitting base 2 is optionally coated with a non-stick coating, such as polytetrafluoroethylene. Thus, the cured resin easily separates from the light-transmitting base 2, while the cured portions adhere to each other. Therefore, the decomposition of the constructed object during retraction can be prevented.

[0080] As the object retracts, the photocurable resin in the tank flows into the newly exposed space left behind by the object. To prevent the filling height from falling below the thickness of the space between the light-transmitting base 2 and the ceramic block 13 (which could create voids in the object), additional photocurable resin is supplied to the tank before and / or simultaneously with the retraction of the object.

[0081] After constructing the dental article 100, any excess (liquid or paste-like) photocurable resin adhering to the article is preferably removed. The excess photocurable resin may be removed, for example, by spin washing, which involves a method step of spinning the dental article 100 at a rate that separates the excess photocurable resin from the dental article 100 by centrifugal force. Since the photocurable resin typically does not flow completely off the article, excess photocurable resin may adhere to the article. Such adhered excess photocurable resin may be cured (post-cured) to omit the washing step, but it has been found that the adhered photocurable resin may not form a uniform layer. Therefore, the adhered excess photocurable resin may adversely affect the accuracy of the article's shape.

[0082] Figure 2 shows a build carrier 4 including a ceramic block 13 in more detail. In this embodiment, the build carrier 4 is shown mounted on a support 8 of the additive manufacturing device. The support 8 is preferably part of the additive manufacturing device, and the build carrier 4 including the ceramic block 13 is preferably detachably mounted on the support 8. Thus, the build carrier 4 including the ceramic block 13 can be replaced with another build carrier. For example, in the case of dental articles, after a dental article has been built on the ceramic block of the build carrier 4, the build carrier may be replaced with a new (empty) build carrier to build further dental articles on the new build carrier. Thus, idle time of the additive manufacturing device can be minimized.

[0083] The ceramic blocks 13 are arranged with space between them such that gaps 14 are formed between adjacent ceramic blocks 13. Each gap has a width equal to the shortest distance between two adjacent ceramic blocks 13. In the illustrated example, the gaps have a uniform width. Furthermore, preferably, the holding surface 15 of each ceramic block 13 is flat. In this embodiment, the holding surfaces 15 of all ceramic blocks 13 are located in a single plane. However, the plurality of ceramic blocks 13 may include a first subset of ceramic blocks 13 having holding surfaces 15 in a first plane, and a second subset of ceramic blocks 13 having holding surfaces 15 in a different second plane. Therefore, for example, an object may be constructed on the first subset of ceramic blocks 13 in a timely manner before further objects can be constructed on the second subset of ceramic blocks 13.

[0084] Each gap 14 further has a length in dimensions spanning several ceramic blocks 13 and a depth in dimensions perpendicular to one or more planes formed by the retaining surface 15. The width, length, and depth of the gaps 14 are dimensioned so that they can receive the photocurable resin into their interior. For example, if the ceramic blocks 13 are placed in a bath of photocurable resin and the retaining surface 15 protrudes into the bath, the photocurable resin moves toward the gaps 14. It has been found that the air that eventually exists between the retaining surface 15 (or the layer of cured resin) and the photocurable resin tends to move toward the gaps 14. Therefore, the gaps 14 help construct an object in which the void content caused by trapped air is minimized.

[0085] Figure 3 shows the ceramic block 13 in more detail. The ceramic block 13 is shown from the back, which is opposite the retaining surface 15 formed by the front side of the ceramic block 13. The ceramic block 13 has a plurality of recesses 16. The recesses 16 can be used to secure the ceramic block 13 on a build carrier. In this embodiment, the ceramic block 13 is provided with one or more threaded inserts 17. The threaded inserts 17 can be securely fixed into the ceramic block 13, for example, by adhesive. Thus, the ceramic block 13 can be fixed using screws that are screwed into the threaded inserts 17.

[0086] Furthermore, the ceramic block 13 may be provided with one or more threaded slot nuts 18. The slot nuts 18 may be used in addition to, or as a substitute for, the threaded insert 17.

[0087] Figure 4 shows the threaded slot nut 18 in more detail. The slot nut 18 in this embodiment is V-shaped to cooperate with the V-shaped recess in the ceramic block. The recess 16 in the ceramic block (see Figures 5 and 6) is wider in the direction that it penetrates further into the ceramic block 13 from the back side. The slot nut 18 has a plate dimension formed by two plate portions 19. The plate dimension is less than or equal to the minimum width of the recess (see "W" in Figures 5 and 6). Thus, the slot nut 18 can be inserted into the recess of the ceramic block, as shown in Figure 5. After being inserted into the recess 16, the slot nut 18 is rotated so that the V-shape of the slot nut 18 engages with the V-shape of the recess. To enable rotation, the slot nut 18 has a rounded structure 20.

[0088] Figure 7 shows the build carrier 4 without the ceramic block (for example, before the ceramic block is mounted on the build carrier, or after the ceramic block has been removed from the build carrier 4). The build carrier 4 is provided with a number of positioning pins 21 for engaging with recesses in the ceramic block. Thus, the positioning pins 21 have a diameter corresponding to the width of the recess. In this embodiment, four positioning pins 21 are provided for each ceramic block. However, more or fewer positioning pins 21 may be used in the same manner. In this embodiment, the positioning pins 21 have a cylindrical shape. In this case, at least two positioning pins 21 are used to provide a predetermined position for the ceramic block on the build carrier 4. In some embodiments, the ceramic block includes zirconia (ZrO2).

[0089] Ceramic materials A build surface comprising the ceramic material of this disclosure comprises particles made of at least one ceramic material. In many embodiments, the ceramic particles include metal oxide ceramic particles, non-oxide ceramic particles, or any combination thereof.

[0090] In some embodiments, the ceramic particles are zirconia (ZrO2), silica (SiO2), alumina (Al2O3), yttria (Y2O3), ceria (CeO2), magnesium aluminate magnesia (MMA), magnesium oxide (MgO), hydroxyapatite (Ca5(PO4)3OH), fluoroapatite (Ca5(PO4)3F), chlorapatite (Ca5(PO4)3Cl), calcite (CaCO3), cordierite (Mg2Al4Si5O 18 ), silicon carbide (SiC), silicon nitride (Si3N4), boron carbide (B4C), titanium diboride (TiB2), zirconium diboride (ZrB2), boron nitride (BN), titanium carbide (TiC), zirconium carbide (ZrC), aluminum nitride (AlN), calcium hexaboride (CaB6), MAX phase (M n+1 AX n The particles are selected from the group consisting of ), and combinations thereof. In the selected embodiment, high-purity particles are used in which the total content of metal impurities is preferably less than 100 ppm, and particularly preferably less than 50 ppm. In the alternative embodiment, particles are used in which the total content of metal impurities is about 2,000 ppm.

[0091] In certain embodiments, the ceramic particles may include nanofillers. Optionally, the nanofillers include nanoclusters. One or more different types of nanoclusters may be present. It has been found that the use of nanoclusters can be beneficial because it allows for the formulation of compositions with higher filler content compared to other fillers, resulting in superior mechanical properties, such as abrasion resistance or wear resistance, and higher aesthetics. If present, nanoclusters can typically be characterized by at least one or all of the following features: specific surface area: 30-400, or 60-300, or 80-250 m². 2 / g; Contains particles of SiO2, ZrO2, Al2O3, and mixtures thereof.

[0092] If desired, the specific surface area of ​​the nanoclusters can be determined according to the Brunauer-Emmett-Teller (BET) method using a measuring device (e.g., MONOSORB, available from Quantachrome Instruments (Boynton Beach, FL)).

[0093] Suitable zirconia particles include, but are not limited to, nano-sized zirconia particles having at least one and up to all of the following parameters or characteristics: primary particle size XRD (diameter): 2–100 nm, 2–50 nm, 2–20 nm, 2–15 nm, or 4–15 nm; essentially spherical, cubic, or a mixture of spherical and cubic; non-associative; crystalline; and not coated with inorganic colorants.

[0094] Suitable nano-sized zirconia particles may have at least one and up to all of the following characteristics: ZrO2 content: 70-100 mol% or 80-97 mol%; HfO2 content: 0-4.5 mol%, 0-3 mol%, or 0.1-2.8 mol%; stabilizer selected from Y2O3, CeO2, MgO, CaO, La2O3, or combinations thereof in amounts of 0-30 mol%, 1.5-16 mol%, 2-10 mol%, or 2-5 mol%; Al2O3 content: 0-1 mol%, or 0.005-0.5 mol%, or 0.01-0.2 mol%. According to one embodiment, nano-sized zirconia particles are characterized as follows: ZrO2 content: 70-98.4 mol%; HfO2 content: 0.1-2.8 mol%; Y2O3 content: 1.5-28 mol%. Nano-sized zirconia particles can be obtained, or are possible to obtain, by a process that includes a step of hydrothermal treatment of an aqueous solution or suspension of a metal salt (e.g., zirconium salt, yttrium salt). Such a process is described in International Publication No. 2013 / 055432 (Kolb et al.).

[0095] Suitable silica particles include, but are not limited to, spherical and non-spherical silica particles. Spherical silica particles (sols) in aqueous media are well known and commercially available in the art, for example, from WRGrace & Co. (Columbia, MD) under the trade name LUDOX, from Nyacol Nanotechnologies Inc. (Ashland, MA) under the trade name NYACOL, or from Nalco Company (Naperville, IL) under the trade name NALCO, as silica sols in water or aqueous alcohol solutions. One useful silica sol with an average volume particle size of 5 nm, a pH of 10.5, and a nominal solids content of 15 wt percent is available from Nalco Company as NALCO 2326. Other useful commercially available silica sols include NALCO 1115 and NALCO 1130 from Nalco Company, REMASOL SP30 from Remet Corp. (Utica, NY), and LUDOX SM from WRGrace & Co. Other suitable silica particles include fumed silica. Granulated silica particles are commercially available, for example, from Degussa, Cabot Corp., or Wacker under trade names AEROSIL, CAB-O-SIL, and HDK. The specific surface area of ​​hydrophobic fumed silica is typically 100–300 m². 2 / g, or 150-250m 2 The value is / g. If desired, mixtures of different fumed silicas can be used. For example, a mixture of fumed silica whose surface is treated with a hydrophobic surface treatment agent and fumed silica whose surface is treated with a hydrophilic surface treatment agent can be used. Suitable nanosilica containing aggregated nano-sized particles can be produced, for example, according to the process described in U.S. Patent No. 6,730,156 (Zhang et al.; Preparation Example A).

[0096] Suitable alumina particles include, but are not limited to, aqueous alumina dispersions (e.g., alumina particles with an average particle size of 500 nm available from Sumitomo Chemicals (New York, NY)) and alumina particles available from Saint-Gobain Surface Conditioning Group (Anaheim, CA).

[0097] Suitable yttrium particles include, but are not limited to, yttrium oxide available from Treibacher Industrie AG (Althofen, Austria).

[0098] Suitable ceria particles include, but are not limited to, colloidal cerium oxide in the form of colloidal sols and nanostructured powders available from NYACOL Nano Technologies, Inc. (Ashland, MA). NYACOL CDP is a dispersible ceria powder with a particle size of, for example, 25-30 nm, while NYACOL Ce120 / 10 is a colloidal ceria with a particle size of 100-140 nm and water as a support.

[0099] Suitable magnesium aluminate particles include, but are not limited to, magnesium spinel aluminate in the form of nanostructured powder, available from American Elements (Los Angeles, CA). For example, 99.9% Magnesium Aluminate, Spinel Nanopowder has a nominal particle size of less than 50 nm. Larger particle powders are available from Reade International, Corp (Riverside, RI) as Spinel Powder (MgAl2O4) with particle sizes of 1 to 5 micrometers.

[0100] Suitable magnesium oxide particles include, but are not limited to, particles in the form of an aqueous dispersion. However, it should be understood that a certain amount of magnesium oxide is converted to magnesium hydroxide in the presence of water. Preferred magnesium oxide dispersions are prepared from commercially available magnesium oxide such as ELASTOMAG 170 from Martin Marietta Magnesia Specialties, LLC (Baltimore, MD) and MAGLITE A from Hallstar (Chicago, IL). Magnesium oxide may be dispersed by those skilled in the art or obtained from suppliers such as Tiarco Chemical and HMRoyal.

[0101] Suitable apatite particles include, but are not limited to, hydroxyapatite, fluoroapatite, and chlorapatite, which have high concentrations of OH, F, and Cl ions in their crystal structure, respectively. For example, suitable hydroxyapatite particles include, but are not limited to, hydroxyapatite manufactured by CAM Bioceramics (Leiden, The Netherlands). Since natural bone is approximately 70% hydroxyapatite by weight and 50% by volume, hydroxyapatite has been used as a bone substitute. Hydroxyapatite has also been widely used in various implant applications, such as a scaffold for tissue growth and as a coating for implants to promote tissue bonding. The synthesis of chlorapatite and fluoroapatite has been reported in publications such as Sanjeevi et al., "Journal of the European Ceramic Society", 2007, 27, 2287-2294; Montazeri et al., "International Journal of Nanomedicine", 2011, 6, 197-201; and Ghomi et al., "Materials Research Innovations", 2013, 17:4, 257-262.

[0102] Suitable calcite particles include, for example, calcite nanoparticles commercially available under the trade names "MULTIFEX MM" and "ALBAFIL" from Cary Company (Addison, IL), the trade name "SOCAL 31" from Solvay Specialty Chemicals, LTD (Houston, TX), and the trade names "NPCC-111" and "NPCC-113" from NanoMaterials Technology Ltd (Singapore), but are not limited thereto.

[0103] Suitable cordierite particles include, for example, cordierite particles commercially available as Cordierite Powder with an average particle size of 6 - 7 micrometers from Reade International, Corp (Riverside, RI), and cordierite particles commercially available as Cordierite or Magnesium Aluminum Silicate from American Elements (Los Angeles, CA), but are not limited thereto.

[0104] Suitable silicon nitride particles include, for example, powders having an intermediate (mean) particle size or agglomerate size (D 50 ) of 0.5 - 20 micrometers, for example 1 - 10 micrometers, but are not limited thereto. The oxygen content of the silicon nitride powder is preferably less than 2% by weight, and the total carbon content is preferably less than 0.35% by weight. Commercially available silicon nitride powder can be obtained from AlzChem Group AG (Trastber, Germany) under the trade name SILZOT.

[0105] Suitable boron carbide particles include, for example, B4C powders having a purity of 97% by weight or more and an intermediate particle size (D 50 ) of 0.1 - 8 micrometers, but are not limited thereto. An example of a suitable boron carbide powder is 3M Boron Carbide Powder commercially available from 3M Company (St. Paul, MN).

[0106] Suitable titanium diboride particles include, for example, intermediate particle size (D 50 Examples of suitable titanium diboride powders include, but are not limited to, TiB2 powders with a diameter of approximately 2 to 20 micrometers. A suitable example of titanium diboride powder is 3M Titanium Diboride Powder, which is commercially available from 3M Company, based in St. Paul, Minnesota.

[0107] Suitable zirconium diboride particles include, but are not limited to, high-purity or ultra-high-purity ZrB2 powder available from American Elements (Los Angeles, CA).

[0108] Suitable boron nitride particles include, but are not limited to, granular aggregates of plate-shaped hexagonal boron nitride primary particles. Here, the hexagonal boron nitride primary particles are connected to each other by an inorganic bonding phase. The inorganic bonding phase comprises at least one nitride and / or oxynitride. The nitride or oxynitride is preferably a compound of the elements aluminum, silicon, titanium, and boron. An example of a suitable boron nitride powder is the 3M Boron Nitride Cooling Fillers Platelets, commercially available from 3M Company.

[0109] Suitable titanium carbide particles include, for example, intermediate particle size (D 50 Examples of suitable titanium carbide powders include, but are not limited to, TiC powders with a diameter of 1 to 3 micrometers. A suitable example of a suitable titanium carbide powder is TiC Grade High Vacuum 120, which is commercially available from HC-Starck (Munich, Germany).

[0110] Suitable zirconium carbide particles include, for example, intermediate particle size (D 50 Examples of suitable zirconium carbide powders include, but are not limited to, ZrC powders with a diameter of 3 to 5 micrometers. A suitable example of a suitable zirconium carbide powder is ZrC Grade B, which is commercially available from HC-Starck.

[0111] Suitable aluminum nitride particles include, for example, intermediate particle size (D 50 Examples of suitable aluminum nitride powders include, but are not limited to, AlN powders with a diameter of 0.8 to 2 micrometers. A suitable example of aluminum nitride powder is AlN Grade C, which is commercially available from HC-Starck.

[0112] Suitable calcium hexaboride particles include, but are not limited to, CaB6 powder, which is commercially available from 3M Company as 3M Calcium Hexaboride.

[0113] MAX phase particles are given by the general formula M n+1 AX n The MAX phase is a layered hexagonal carbide and nitride having (wherein n=1 to 3, M is a pre-periodic transition metal, A is a group A element, and X is independently selected from carbon and nitrogen). The group A element is preferably a group 13 to 16 element. An example of a suitable MAX phase powder is MAXTHAL 312 powder, which is commercially available from Kanthal (Hallstahammar, Sweden).

[0114] photocurable resin A photocurable resin (photopolymerizable slurry or sol) typically comprises at least one radiation-curable monomer, a solvent, a photoinitiator, optionally an inhibitor, and optionally ceramic particles. For example, preferred components of the radiation-curable monomer, ceramic particles, solvent, photoinitiator, and inhibitor of this disclosure can be found, for example, in U.S. Provisional Patent Application No. 62 / 883,239 to Shah et al., filed on August 6, 2019, assigned to the assignee of the present invention, and incorporated herein by reference in its entirety.

[0115] In some embodiments, the photocurable resin (photopolymerizable slurry or sol) may contain one or more radiation-curable monomers that are part of or form an organic matrix. If two or more radiation-curable monomers are present in the photopolymerizable slurry or sol, they may be described as first, second, third, etc. The properties and structure of the radiation-curable monomers are not particularly limited, as long as the desired results are not unattainable. In some embodiments, at least one radiation-curable monomer is an acrylate. Preferably, at least one radiation-curable monomer is a (meth)acrylate, epoxy, silane, or a combination thereof. In some embodiments, the radiation-curable monomers form a network with (preferably) homogeneously dispersed ceramic particles during polymerization.

[0116] The photocurable resin may or may not contain ceramic particles such as the ceramic material mentioned above. The photocurable resin may also be called a photopolymerizable resin, or a photopolymerizable slurry or sol. In some embodiments, the photocurable resin itself may contain ceramic particles. In embodiments containing ceramic particles, the photopolymerizable slurry or sol may contain 20% or more by weight, 21% or more by weight, 22% or more by weight, 23% or more by weight, 24% or more by weight, 25% or more by weight, 26% or more by weight, 27% or less by weight, 28% or less by weight, 29% or less by weight, 30% or less by weight, or 24.5% or less by weight of ceramic particles, based on the total weight of the photopolymerizable slurry or sol. In other words, the photopolymerizable slurry or sol may contain 20% to 60% by weight of ceramic particles, based on the total weight of the photopolymerizable slurry or sol.

[0117] In some embodiments, the photopolymerizable slurry or sol contains 3 volume percent (vol%) or more of ceramic particles based on the total volume of the photopolymerizable slurry or sol, or 4 volume%, 5 volume%, 10 volume%, 15 volume%, 20 volume%, 25 volume%, 30 volume%, 35 volume%, 40 volume%, 45 volume%, 50 volume%, 55 volume%, 60 volume%, 65 volume%, or 70 volume% or more based on the total volume of the photopolymerizable slurry or sol; and 70 volume% or less, 65 volume%, 60 volume%, 55 volume%, 50 volume%, 45 volume%, 40 volume%, 35 volume%, 30 volume%, 25 volume%, or 20 volume% or less of ceramic particles. In other words, the photopolymerizable slurry or sol may contain, for example, 3 to 70 volume percent of ceramic particles, 10 to 60 volume percent, or 20 to 50 volume percent of ceramic particles, based on the total volume of the photopolymerizable slurry or sol.

[0118] Ceramic particles typically have an average (intermediate) particle size diameter (i.e., D 50 ) is 1 nanometer (nm) or larger, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 12 nm, 15 nm, 17 nm, 20 nm, 25 nm, 30 nm, 40 nm, 50 nm, 60 nm, 75 nm, 90 nm, 100 nm, 125 nm, 150 nm, 175 nm, 200 nm, 225 nm, 250 nm, 350 nm, 500 nm, 750 nm, 1 micrometer, 1.25 micrometers, 1.5 micrometers, 1.75 micrometers, 2 micrometers, 2.5 micrometers, 3.0 micrometers, 3.5 micrometers, 4.0 micrometers, or 4.5 micrometers or larger; and D 50However, the particle sizes are 10 micrometers or less, 9.5 micrometers, 9 micrometers, 8.5 micrometers, 8 micrometers, 7.5 micrometers, 7 micrometers, 6.5 micrometers, 6 micrometers, 5.5 micrometers, 5 micrometers, 4.5 micrometers, 3 micrometers, 2 micrometers, 1.5 micrometers, 1 micrometer, 900 nm, 800 nm, 700 nm, 600 nm, 500 nm, 400 nm, 300 nm, or 250 nm or less. In other words, ceramic particles have an average particle size diameter (D 50 The particle size can be 1 nm to 900 nm, 1 nm to 500 nm, 1 nm to 250 nm, 250 nm to 10 micrometers, 1 micrometer to 10 micrometers, 500 nanometers to 1.5 micrometers, or 250 nm to 1 micrometer. Average (intermediate) particle size (D 50 ) refers to the particle diameter at or below which 50 volume percent of the particles in the particle distribution have a diameter equal to or smaller than that, as measured by laser diffraction. Preferably, the average particle diameter is that of the primary particles.

[0119] All of the above-mentioned patents and patent applications are expressly incorporated herein by reference. The embodiments described above are illustrative of the present invention, and other structures are also possible. Accordingly, the present invention should not be considered limited to the embodiments described in detail above and shown in the accompanying drawings, but rather limited only to the reasonable scope of the following claims, including their equivalents.

Claims

1. 1. A build platform for use in an additive manufacturing device, the build platform comprising: a build surface for building an object thereon; a surface portion of the build surface comprising a ceramic material having a non-porous material structure; the build surface comprising a plurality of spaced apart flat surface portions extending in a common plane, with gaps formed between adjacent flat surface portions, the gaps having a width in a dimension of the common plane and a depth in a dimension perpendicular to the common plane, the gap width exceeding 8 mm and the gap depth exceeding 8 mm.

2. The build platform of claim 1 , wherein the ceramic material comprises zirconia.

3. A tank having a size and material for containing a liquid photocurable resin; a build carrier comprising a build platform having a build surface for building an object thereon, a surface portion of the build surface comprising a ceramic material having a non-porous material structure, the build surface comprising a plurality of spaced apart flat surface portions extending in a common plane, gaps formed between adjacent flat surface portions, the gaps having a width in a dimension of the common plane and a depth in a dimension perpendicular to the common plane, the gap width exceeding 8 mm and the gap depth exceeding 8 mm; a light source for emitting light towards the build surface, the build carrier and the light source being movable relative to each other; the build carrier is movable within the vat in a direction in which layers of the cured liquid photocurable resin are deposited to build the object; Additive manufacturing devices.

4. 1. A method for manufacturing an article, comprising: Providing the additive manufacturing device of claim 3; providing a liquid photocurable resin; curing the liquid photocurable resin by applying actinic radiation selected from ultraviolet light, visible light, electron beam radiation, and any combination thereof using a light source having sufficient energy to cure the liquid photocurable resin composition; A method comprising:

Images