TW201840964A - Method for determining an amount of sediment in a ceramic dispersion - Google Patents

Abstract

A method determines an amount of sediment in a ceramic dispersion. The ceramic dispersion includes a free-radical curable monomer, silica, and metal particles. The method includes providing a centrifuge to apply a gravitational force to the ceramic dispersion, placing a sample of the ceramic dispersion in a sample container in the centrifuge, and applying a gravitational force of from 25G to 2000G to the ceramic dispersion to precipitate a portion of the silica thereby forming a sediment that includes a topmost layer that includes the metal particles to allow for visualization. The method further includes measuring the amount of the sediment via calculating the height of the sediment as a percentage of the total height of the dispersion, and/or decanting the continuous phase and measuring the mass of the sediment to determine mass percentage of the sediment based on the total mass of the dispersion before application of gravitational force.

Description

Method for determining the content of deposits in ceramic dispersions

The present invention generally relates to a method of determining the amount of deposits in a ceramic dispersion. More specifically, the dispersion includes metal particles to allow visualization.

The additive fabrication process for producing three-dimensional objects is well known. The laminate manufacturing process uses computer-aided design (CAD) data from objects to create three-dimensional parts. These three-dimensional parts can be formed from liquid resins, powders or other materials. In stereo lithography (SL), the CAD data of an object is transformed into a thin cross section of a three-dimensional object. The data is loaded into a computer that controls the laser that passes through the liquid radiation curable resin composition in the cylinder to draw a pattern of cross-sections corresponding to a thin layer of the cross-section cured resin composition. The cured layer is recoated by the resin composition and the laser depicts another cross section to harden another layer of the resin composition on top of the previous layer. This process is repeated layer by layer until the three-dimensional object is completed. When initially formed, the three-dimensional object is generally not fully cured and is referred to as a "green model." This process is also known as three-dimensional (3D) printing. There are several types of lasers for stereo lithography whose wavelengths are traditionally in the range of 193 nm to 355 nm, although other wavelength variations exist. The use of a gas laser-curable liquid radiation curable resin composition is well known. The laser energy transmitted in the stereo lithography system may be a continuous wave (CW) or a Q-switched pulse. CW lasers provide continuous laser energy and can be used in high speed scanning methods. However, its output power is limited, reducing the amount of solidification that occurs during the creation of an object. Other methods of laminate manufacturing utilize lamps or light emitting diodes (LEDs). An LED is a semiconductor device that generates light using an electroluminescence phenomenon. Currently, LED UV sources generally emit light at wavelengths between 300 and 475 nm, with 365 nm, 390 nm, 395 nm, 405 nm, and 415 nm being common peak spectral outputs. Many laminate manufacturing applications require green molds with high mechanical strength (eg, modulus of elasticity, breaking strength, etc.). This property, commonly referred to as "green strength", is typically determined by a liquid radiation curable resin composition. Some compositions include cerium oxide, for example to increase heat distortion temperature and modulus or to make ceramic parts. However, such compositions tend to have (1) high initial viscosity, (2) poor viscosity stability, and (3) a tendency to phase separation, resulting in a phenomenon known as "soft packaging" or "hard packaging", and (4) A high cure shrinkage that causes distortion of the printed portion. As the amount of cerium oxide in such compositions increases, the viscosity of the composition increases, resulting in reduced processability and processing speed. At the same time, the composition must have sufficient viscosity stability over time. Viscosity should not increase significantly over time, otherwise additional processing problems can arise. Moreover, such compositions tend to phase separate over time during storage. For example, cerium oxide can be concentrated at the bottom of the storage vessel to produce a phase separated composition. The top portion of the composition can be a low viscosity, largely unfilled portion, i.e., a portion that does not include sufficient cerium oxide loading. The bottom portion can be super-saturated and highly viscous. The composition in the top portion cannot be used to produce a green mold of sufficient strength and hardness and any resulting part will suffer from high shrinkage and cracking during burnout and sintering of the binder due to the depletion of cerium oxide. The composition in the bottom portion cannot be used because it is too viscous and has a concentration of cerium oxide that renders the final part unusable. Thus, the entire container may become unavailable or, at a minimum, must undergo additional expensive and time consuming processing to enable use. In one scenario, the cerium oxide settles at the bottom of the storage container and forms a flexible package. The precipitated cerium oxide can be surrounded by a partially polymerized resin to produce a waxy consistency. Although it is possible to assimilate into a usable composition, such methods require frequent and often severe recycling. This is a time and energy maintenance process and still does not remove the problematic viscosity of the composition. In another scenario, the cerium oxide settles at the bottom of the storage container and forms a rigid package. In such situations, cerium oxide forms an extremely hard rock-like structure. Such structures must be broken by a drill or similar device and may then be assimilated. Again, this is time consuming and energy intensive. Many compositions must be tested to achieve a stable dispersion and this may take many days or weeks to test each formulation. Metrics for determining stability typically use only subjective observations to define when deposition occurs and then use a further qualitative assessment of the deposit. However, even these methods are inaccurate and time consuming. Therefore, there are still opportunities for improvement.

The present invention provides a method of determining the amount of deposits in a ceramic dispersion for multilayer manufacturing. The ceramic dispersion comprises (a) a radically curable monomer as a continuous phase, (b) as a dispersed phase of cerium oxide, the dispersed phase being dispersed in the continuous phase and being 55 to 70 in terms of the total volume of the ceramic dispersion. The volume percentage is present, and (c) the metal particles. The method includes the steps of providing a centrifuge to apply gravity to the ceramic dispersion and placing the ceramic dispersion sample in a sample container in the centrifuge. The method also includes applying a gravity of 25G to 2000G to the ceramic dispersion in the centrifuge to precipitate a quantity of cerium oxide from the continuous phase, thereby forming a deposit comprising the topmost layer disposed on the deposit, wherein the topmost layer Contains metal particles to allow visualization. The method further includes the step of measuring the amount of deposits in the ceramic dispersion. The measuring step can be carried out by calculating the height of the deposit by a percentage of the total height of the dispersion, and/or decanting the continuous phase and measuring the mass of the deposit to determine the deposit based on the total mass of the dispersion before gravity is applied. Percentage of mass.

The present invention provides a method of determining the amount of deposits in a ceramic dispersion for multilayer manufacturing. The ceramic dispersion is described below as a "dispersion". The term "layered fabrication" describes the established portion of the layer, as is well known in the art and as described above. The term "ceramic" describes the dispersion used to form ceramic articles and is also described in more detail below. The term "dispersion" describes a composition comprising a continuous phase and a dispersed phase dispersed in a continuous phase. The term "sediment" generally describes the amount of dispersed phase precipitated from the continuous phase. The dispersion includes a radically curable monomer as a continuous phase, cerium oxide as a dispersed phase, and metal particles dispersed in the continuous phase and in an amount of 55 to 70 volume percent based on the total volume of the ceramic dispersion. presence. Each is described below. In various embodiments, the dispersion is, consists essentially of, or consists of a radical curable monomer, cerium oxide, and metal particles. For example, in an embodiment "consisting essentially of" the composition of the above components, the dispersion may contain no monomers, other polymers, any type of additives known in the art that are not polymerizable by a free radical mechanism. (including any of the additives described herein), any polymerization initiator that is not a free radical initiator, and/or a filler other than cerium oxide, and the like, and/or combinations thereof. Alternatively, any one or more of these components may be less than 25, 20, 15, 10, 5, 4, 3, 2, 1, 0.1, 0.05, 0.01, etc., based on the total weight of the dispersion, or any The amount of scope exists. In various non-limiting embodiments, all values and ranges of values between the above values are specifically intended to be encompassed. Free radical curable monomer: The dispersion includes a radical curable monomer. This monomer can be polymerized with itself and/or with other acrylate monomers via free radical polymerization, for example by exposure to UV light/energy, peroxides or other free radical initiators known in the art. This monomer acts as a continuous (e.g., liquid) phase of the dispersion. The free radical curable monomer can be an acrylate or methacrylate. The acrylate monomer can be a polyfunctional acrylate. A single type or more than one type of UV curable acrylate monomer can be used. Suitable non-limiting examples include isobornyl (meth)acrylate, decyl (meth)acrylate, tricyclodecyl (meth)acrylate, dicyclopentanyl (meth)acrylate, (meth)acrylic acid Cyclopentenyl ester, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, 4-butylcyclohexyl (meth)acrylate, acryloylmorpholine, (meth)acrylic acid, (A) 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, (methyl) ) propyl acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, amyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, ( Amyl methacrylate, caprolactone acrylate, isoamyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, (methyl) Isooctyl acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, tridecyl (meth) acrylate Ester, undecane (meth) acrylate , lauryl (meth)acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxylate Diethanol (meth) acrylate, benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate , methoxyethylene glycol (meth) acrylate, ethoxyethyl (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, methoxy polypropylene glycol (meth) acrylate Diacetone (meth) acrylamide, β-carboxyethyl (meth) acrylate, (meth) acrylate, dimethylaminoethyl (meth) acrylate, (meth) acrylate Diethylaminoethyl ester, butylamine methyl methacrylate, (meth) acrylamide fluorinated n-isopropyl (meth) acrylate, 7-amino-3 (meth) acrylate , 7-dimethyloctyl ester, trimethylolpropane tri(meth)acrylate, isoamyl (meth)acrylate, ethylene glycol di(meth)acrylate, bisphenol A diglycidyl Ether di(meth)acrylate, two Cyclopentadiene dimethanol di(meth) acrylate, [2-[1,1-dimethyl-2-[(1-sided oxyallyl)oxy]ethyl]-5-ethyl -1,3-dioxan-5-yl]methacrylate; 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxa Spiro[5.5-]undecanedi(meth)acrylate; diisoamyltetraol monohydroxypenta(meth)acrylate, propoxylated trimethylolpropane (meth)acrylate, propoxy Neopentyl glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylic acid Ester, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polybutylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate , tris(meth)acrylate, glycerol mono(meth)acrylate and di(meth)acrylate, C7-C20 alkyl di(meth)acrylate, tris(2-hydroxyethyl)isocyanate Uric acid tris(meth)acrylate, tris(2-hydroxyethyl)isocyanurate di(meth)acrylate, tricyclodecanediyldimethyldi(meth)acrylate and Alkoxylated (eg ethoxylated) And/or propoxylated) forms, and adducts of triethylene glycol divinyl ether, hydroxyethyl acrylate, and combinations thereof. In other embodiments, the acrylate monomer is a polyfunctional (meth) acrylate that can include all of the methacryl fluorenyl groups, all propylene fluorenyl groups, or any combination of methacryl fluorenyl groups and acryl fluorenyl groups. In one embodiment, the acrylate monosystem is selected from the group consisting of propoxylated trimethylolpropane tri(meth)acrylate, and propoxylated neopentyl glycol di(meth)acrylate, and combinations thereof. In other embodiments, the acrylate monomer has greater than 2, greater than 3, or greater than 4 functional groups. Alternatively, the acrylate monomer may have exactly 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 functional groups. In one embodiment, the acrylate monomer consists solely of a single polyfunctional (meth) acrylate component. In other embodiments, the acrylate monoester is selected from the group consisting of dicyclopentadiene dimethanol diacrylate, [2-[1,1-dimethyl-2-[(1-sided oxyallyl)oxy) Ethyl]ethyl]-5-ethyl-1,3-dioxan-5-yl]methacrylate, propoxylated trimethylolpropane triacrylate and propoxylated neopentyl glycol Acrylates, and combinations thereof. In various non-limiting embodiments, all values and ranges of values between the above values are specifically intended to be encompassed. Alternatively, the acrylate monomer may be dicyclopentadiene dimethanol di(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and/or propoxylated neopentyl glycol. Di(meth)acrylate, and more specifically, dicyclopentadiene dimethanol diacrylate, propoxylated trimethylolpropane triacrylate and/or propoxylated neopentyl glycol diacrylate One or more of the esters. The above-mentioned acrylate monomers may be used singly or in combination of two or more. The dispersion may include any suitable amount of acrylate monomer as long as the cerium oxide is present in an amount of 55 to 70 volume percent based on the total volume of the dispersion and the radical initiator and the shear thinning additive is also present in the dispersion. Just fine. In various embodiments, the free radical curable monomer is otherwise defined as a (meth) acrylate monomer, which can be any monomer having at least one acrylate functional group and/or at least one methacrylate functional group. In other words, the term "(meth)" describes "methyl" as it exists and is not required. Therefore, the monomer may be an "acrylate" monomer (no methyl group) or a "methacrylate" monomer including a methyl group. Typically, the (meth) acrylate monomer used herein is a compound selected from the group consisting of aliphatic acrylates, aliphatic methacrylates, cycloaliphatic acrylates, cycloaliphatic methacrylates, and combinations thereof. It should be understood that each of the compound, aliphatic acrylate, aliphatic methacrylate, cycloaliphatic acrylate, and cycloaliphatic methacrylate includes an alkyl group. The alkyl groups in such compounds can include up to 20 carbon atoms. The aliphatic acrylate which may be selected from one of the (meth) acrylate monomers is selected from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, Tert-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, isodecyl acrylate, isoamyl acrylate, tridecyl acrylate, stearyl acrylate, lauryl acrylate, and mixtures thereof. The aliphatic methacrylate which may be selected from one of the (meth) acrylate monomers is selected from the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, methyl group. N-butyl acrylate, isobutyl methacrylate, tert-butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, isooctyl methacrylate, isodecyl methacrylate, Isoamyl methacrylate, tridecyl methacrylate, stearyl methacrylate, lauryl methacrylate, and mixtures thereof. The cycloaliphatic acrylate which is one of the (meth) acrylate monomers may be cyclohexyl acrylate, and may be selected from cycloaliphatic methacrylic acid of one of the (meth) acrylate monomers. The ester is cyclohexyl methacrylate. In various embodiments, the acrylate monomer is present in an amount greater than zero and up to about 40% by volume of the dispersion. In other embodiments, the acrylate monomer is 2 to 40, 5 to 40, 5 to 35, 5 to 30, 10 to 30, 10 to 25, 10 to 20, 15 to 30, based on the total volume by weight of the dispersion. , 15 to 25, 15 to 20 or 1, 2, 3, 4 or 5 volume percent is present. In various non-limiting embodiments, all values and ranges of values between the above values are specifically intended to be encompassed. Free radical curable monomers other than acrylates can also be used. Such monomers may include any monomer known in the art, such as including carbon-carbon double bonds (eg, ethylenically unsaturated compounds), carbon-carbon triple bonds, and/or any other polymerizable via free radical polymerization mechanisms. The compounds are the same. In various alternative embodiments, the dispersion does not contain monomers that are not (meth) acrylates. Cerium Oxide : The dispersion also includes cerium oxide. Cerium oxide is a dispersed phase dispersed in the continuous phase described above. For example, the cerium oxide particles can be dispersed in an acrylate monomer, which is typically a liquid or liquid. The cerium oxide is present in an amount of from 55 to 70 volume percent based on the total volume of the dispersion. In various embodiments, the cerium oxide is in a volume of 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69 or 70, based on the total volume of the dispersion. The percentage exists. In various non-limiting embodiments, all values and ranges of values between the above values are specifically intended to be encompassed. In various embodiments, cerium oxide is additionally defined as cerium oxide particles, such as microparticles and/or nanoparticles. For example, the cerium oxide (particles) may be 90, 95, 99 or approximately 100% by weight of microparticles, nanoparticles or a combination of microparticles and nanoparticles. Nanoparticles can be described as such particles having an average particle size between 1 nanometer (nm) and 999 nm. Microparticles are alternatively described as having particles having an average particle size of from 1 micrometer (μm) to 999 μm. In various embodiments, the cerium oxide has a particle size (distribution) ranging from 0.04 microns to 90 microns. In various embodiments, the cerium oxide has a particle size of from 1 micron to 90 microns and comprises 5, 4, 3, 2, 1, 0.5, 0.1, 0.05 or 0.01 weight or volume percent or less having a particle size of 10 nanometers to 999 nanometer nano particles. In all of the non-limiting embodiments, all values and ranges of values (including endpoints) between all of the above values are specifically intended to be used. In various embodiments, the cerium oxide comprises a combination of microparticles having a particle size of from 1 to 90 micrometers and nanoparticles having a particle size of from 10 to 500 nanometers, and the average particle size ratio of the microparticles: nanoparticles is from 1:2 to 1 :200. In other embodiments, the cerium oxide comprises a combination of microparticles having a particle size of from 1 to 90 micrometers and nanoparticles having a particle size of from 10 to 1000 nanometers. The average particle size ratio of the microparticles: nanoparticles is from 1:2 to 1 :200. In other non-limiting embodiments, such ratios may be reversed. In various non-limiting embodiments, all values and ranges of values (including endpoints) between 1 and 90 microns, between 10 and 500 nanometers, and between 1:2 and 1:200 are specifically contemplated for use. Alternatively, nanoparticles can be described as such particles having an average particle size between 1 nanometer (nm) and 999 nm. Microparticles are alternatively described as having particles having an average particle size of from 1 micrometer (μm) to 999 μm. In various embodiments, the cerium oxide has a particle size (distribution) ranging from 0.04 microns to 90 microns. In all of the non-limiting embodiments, all values and ranges of values (including endpoints) between all of the above values are specifically intended to be used. The particle size can be measured using laser diffraction particle size analysis according to ISO 13320:2009. A suitable apparatus for measuring the average particle size of the nanoparticles is a LB-550 machine from Horiba Instruments, Inc. which measures the particle size by dynamic light scattering. In various non-limiting embodiments, all values and ranges of values between the above values are specifically intended to be encompassed. The cerium oxide may include more than 85% by weight, 90% by weight or 95% by weight of cerium oxide (SiO ₂ ). Some non-limiting examples of commercially available ceria include Crystallite 3K-S, Crystallite NX-7, Crystallite MCC-4, Crystallite CMC-12, Crystallite A-1, Crystallite AA, Crystallite C, Crystallite D, Crystallite CMC- 1. Crystallite C-66, Crystallite 5X, Crystallite 2A-2, Crystallite VX-S2, Crystallite VX-SR, Crystallite VX-X, Crystallite VX-S, Huselex RD-8, Huselex RD-120, Huselex MCF-4, Huselex GP-200T, Huselex ZA-30, Huselex RD-8, Huselex Y-40, Huselex E-2, Huselex Y-60, Huselex E-1, Huselex E-2, Huselex FF, Huselex X, Huselex ZA-20 IMSIL A-25, IMSIL A-15, IMSIL A-10 and IMSIL A-8 (Ryushin Co., Ltd.); ORGANOSILICASOL MEK-EC-2102, Organosilicasol MEK-EC-2104, Organosilicasol MEK-AC-2202, Organosilicasol MEK-AC-4101, Organosilicasol MEK-AC-5101, Organosilicasol MIBK-SD, Organosilicasol MIBK-SD-L, Organosilicasol DMAC-ST, Organosilicasol EG-ST, Organosilicasol IPA-ST, Organosilicasol IPA-ST-L, Organosilicasol IPA -ST-L-UP, Organosilicasol IPA-ST-ZL, Organ Osilicasol MA-ST-M, Organosilicasol MEK-ST, Organosilicasol MEK-ST-L, Organosilicasol MEK-ST-UP, Organosilicasol MIBK-ST, Organosilicasol MT-ST, Organosilicasol NPC-ST-30, Organosilicasol PMA-ST, Sunsphere H -31, Sunsphere H-32, Sunsphere H-51, Sunsphere H-52, Sunsphere H-121, Sunsphere H-122, Sunsphere L-31, Sunsphere L-51, Sunsphere L-121, Sunsphere NP-30, Sunsphere NP -100 and Sunsphere NP-200 (Asahi Glass Co., Ltd.); Silstar MK-08 and MK-15 (Nippon Chemical Industrial Co., Ltd.); FB-48 (Denki Kagaku Kogyo KK); Nipsil SS-10 Nipsi: L SS-15, Nipsil SS-10A, Nipsil SS-20, Nipsil SS-30P, Nipsil SS-30S, Nipsil SS-40, Nipsil SS-50, Nipsil SS-50A, Nipsil SS-70, Nipsil SS -100, Nipsil SS-10F, Nipsil SS-50F, Nipsil SS-50B, Nipsil SS-50C, Nipsil SS-72F, Nipsil SS-170X, Nipsil SS-178B, Nipsil E150K, Nipsil E-150J, Nipsil E-1030 , Nipsil ST-4, Nipsil E-170, Nipsil E-200, Nipsil E-220, Nipsil E-200A, Nipsil E-1009, Nipsil E-220A, Nipsil E-1011, Nipsil EK 300, Nipsil HD, Nipsil HD-2, Nipsil N-300A, Nipsil L-250, Nipsil G-300, Nipsil E-75, Nipsil E-743 and Nipsil E-74P (Nippon Silica Industry, Ltd.). In other embodiments, cerium oxide is as described in U.S. Patent No. 6,013,714, which is hereby incorporated by reference in its entirety in its entirety in its entirety in its entirety in its entirety. The cerium oxide can be surface treated with a decane coupling agent. The decane coupling agents which can be used for this purpose include vinyltrichloromethane, vinyl stilbene (β-methoxyethoxy) decane, vinyl triethoxy decane, vinyl trimethoxy decane, γ-(methyl Propylene methoxypropyl)trimethoxydecane, β-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, γ-glycine methoxypropyltrimethoxydecane, γ-glycin oxime Oxypropylmethyldiethoxydecane, N-β(Amineethyl)Aminopropyltrimethoxydecane, N-β-(Aminoethyl)-γ-Aminopropylmethyldimethoxy Decane, γ-aminopropyltriethoxydecane, N-phenyl-γ-aminopropyltrimethoxydecane, γ-mercaptopropyltrimethoxydecane, and γ-chloropropyltrimethoxydecane. In various embodiments, a typical ceria formulation suitable for printing a 100 μm layer is set forth in the table below. In other embodiments, formulations suitable for printing 50 μ layers are found in the table below. * indicates that Angular-200 as supplied by Remet is screened through a 325 mesh screen. ** Indications such as RP-1 supplied by Imerys were sieved through a 325 mesh screen. Teco-sphere Microdust is commercially available from Imerys Fused Materials Greenville, Inc., 109 Coile Street, Greeville, TN, USA. Angular-200 is commercially available from Remet Corporation, 210 Commons Road, Utica, NY 13502-6395, USA. RP-1 is commercially available from Imerys Fused Materials Greenville, Inc., 109 Coile Street, Greeville, TN, USA. A-10 is commercially available from Almatis Inc., 501 West Park Road, Leetsdale, Pa 15056, USA. Milled Zircon Fine Grind is commercially available from Remet Corporation, 210 Commons Road, Utica, NY 13502-6395, USA. In other embodiments, increasing the ceramic loading increases the probability of viscosity and particle-particle interaction, which reduces the settling rate of the dispersion. Maximizing the ceramic load can also increase the density of the ceramic article, reduce cracking and delamination defects, and increase the mechanical strength of the ceramic article. When the ceramic load reaches 64-66 volume percent of the load, the viscosity can begin to increase exponentially. Thus, in various embodiments, a 64 volume percent ceramic loading is used to maintain a formulation viscosity that is sufficiently low for 3D printing. The metal particle dispersion also includes metal particles. The metal particles are typically steel, but can be any type of metal. Metal particles are typically derived from metal equipment used to form the dispersion and are typically not added to the dispersion independently by the skilled person. In other words, the metal particles are usually generated in situ when the dispersion is formed. However, in various embodiments, the invention is not limited in this manner such that the metal particles themselves and/or additional metal particles can be manually added independently, regardless of whether any metal particles are produced in situ. The metal particles may be present in an amount of less than 0.5, 0.4, 0.3, 0.2, 0.1, 0.05, 0.01, 0.005, 0.001, 0.0005 or 0.0001% by weight, based on the total weight of the dispersion. In all of the non-limiting embodiments, all values and ranges of values (including endpoints) between all of the above values are specifically intended to be used. Dyes and / or pigments: The dispersions may also comprise dyes and/or pigments, for example in an amount of from 0.01 to 0.3% by weight, based on the total weight % of the dispersion. In various embodiments, the dye and/or pigment is present in an amount of from 0.05 to 0.25, from 0.1 to 0.2, or from 0.15 to 0.2% by weight, based on the total weight percent of the dispersion. In various embodiments, the dye is an anthraquinone dye. In other embodiments, the pigment has a density greater than 3, 3.5, 4, 4.5, or 5 g/cm ³ . In all of the non-limiting embodiments, all values and ranges of values (including endpoints) between all of the above values are specifically intended to be used. Free Radical Initiator: In various embodiments, the dispersion comprises a free radical initiator. Typically, the free radical initiator is a UV activated free radical initiator. For example, free radical initiators are typically initiated by exposure to UV light, which causes free radical formation followed by propagation of the free radicals. However, non-UV initiated free radical initiators can be used alone or in combination with UV activated free radical initiators. Free radical initiators can be described as free radical photoinitiators. Free radical photoinitiators are generally classified into those known as "Norrish Type I" by cleavage to form free radicals, and those known as "Norrish Type II" which form free radicals by hydrogen extraction. Norrish Type II photoinitiators typically require a hydrogen donor that acts as a source of free radicals. Since the initiation is based on a bimolecular reaction, Norrish Type II photoinitiators are generally slower than Norrish Type I photoinitiators formed from free radical based single molecules. However, Norrish Type II photoinitiators typically have better light absorption characteristics in the near UV spectral region. Such as benzophenone, 9-oxosulfur Photolysis of an aromatic ketone of diphenylethylenedione and anthracene in the presence of a hydrogen donor such as an alcohol, an amine or a thiol results in the formation of a free radical (carbonyl radical-type free radical) derived from a carbonyl compound and derived therefrom. Another free radical from a hydrogen donor. Photopolymerization of vinyl monomers is typically initiated by free radicals generated from hydrogen donors. Due to steric hindrance and delocalization of unpaired electrons, carbonyl radicals generally do not react with vinyl monomers. In various embodiments, the free radical initiator is selected from the group consisting of benzamidine phosphine oxides, aryl ketones, benzophenones, hydroxylated ketones, 1-hydroxyphenyl ketones, ketals, metallocenes, and combinations thereof. In other embodiments, the free radical initiator is selected from the group consisting of 2,4,6-trimethylbenzimidyldiphenylphosphine oxide and 2,4,6-trimethylbenzomethylphenyl, B. Oxylphosphine oxide, bis(2,4,6-trimethylbenzylidene)-phenylphosphine oxide, 2-methyl-1-[4-(methylthio)phenyl]-2- Morpholinoacetone-1,2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone, 2-dimethylamino- 2-(4-Methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, 4-benzylidene-4'-methyldiphenyl Thioether, 4,4'-bis(diethylamino)benzophenone and 4,4'-bis(N,N'-dimethylamino)benzophenone (Michler's ketone) , benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, dimethoxybenzophenone, 1-hydroxycyclohexyl benzophenone, phenyl (1 -hydroxyisopropyl)one, 2-hydroxy-1-[4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone, 4-isopropylphenyl (1-hydroxyiso) Propyl)ketone, oligo-[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone], camphorquinone, 4,4'-bis(diethylamine) Benzophenone, diphenylethylenedione dimethyl ketal, bis(η 5-2-4-cyclopentadien-1-yl) Bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium and combinations thereof. Typically, when a dispersion is formed, the wavelength sensitivity of the photoinitiator present is assessed to determine if it will be activated by the selected source of radiation. Non-limiting examples of suitable free radical initiators that absorb in these ranges for light sources that illuminate in the 300-475 nm wavelength range, especially at 365 nm, 390 nm, or 395 nm include (but not Limited to benzamidine phosphine oxides such as 2,4,6-trimethylbenzimidyl diphenylphosphine oxide (Lucirin TPO from BASF) and 2,4,6-trimethylbenzamide Phenylphenyl, ethoxyphosphine oxide (Lucirin TPO-L from BASF), bis(2,4,6-trimethylbenzylidene)-phenylphosphine oxide (Irgacure 819 from Ciba) Or BAPO), 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinylacetone-1 (Irgacure 907 from Ciba), 2-benzyl-2-(di) Methylamino)-1-[4-(4-morpholino)phenyl]-1-butanone (Irgacure 369 from Ciba), 2-dimethylamino-2-(4-methyl-benzene Methyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one (Irgacure 379 from Ciba), 4-benzylidene-4'-methyldiphenylsulfide Ether (Chivacure BMS from Chitec), 4,4'-bis(diethylamino)benzophenone (Chivacure EMK from Chitec) and 4,4'-bis(N,N'-dimethylamine) Base) benzophenone (milaxone). Also suitable for their combination. Additionally, photosensitizers can be used, such as when using LED light sources. Non-limiting examples of suitable photosensitizers include: hydrazine, such as 2-methyl hydrazine, 2-ethyl hydrazine, 2-tert-butyl fluorene, 1-chloroindole, and 2-pentyl hydrazine. 9-oxopurine Oxene ketone, such as isopropyl 9-oxopurine 2-chloro 9-oxosulfuron 2,4-Diethyl 9-oxothione And 1-chloro-4-propoxy 9-oxothione , methotrexate (Darocur MBF from Ciba), methyl-2-benzhydryl benzoate (Chivacure OMB from Chitec), 4-benzylidene-4' Methyl diphenyl sulfide (Chivacure BMS from Chitec), 4,4'-bis(diethylamino)benzophenone (Chivacure EMK from Chitec). For light sources that emit light in the wavelength range of 100 to 300 nm, photosensitizers such as benzophenones such as benzophenone, 4-methylbenzophenone, 2,4,6-trimethyl s can be used. Benzophenone, dimethoxybenzophenone, and 1-hydroxyphenyl ketone, such as 1-hydroxycyclohexyl phenyl ketone, phenyl (1-hydroxyisopropyl) ketone, 2-hydroxy-1-[ 4-(2-hydroxyethoxy)phenyl]-2-methyl-1-propanone and 4-isopropylphenyl(1-hydroxyisopropyl)one, diphenylethylenedione dimethyl condensate Ketones and oligo-[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone] (obtained from Lamberti's Esacure KIP 150), and combinations thereof. For light sources that emit light in the wavelength range of 475 to 900 nm, free radical initiators such as camphorquinone, 4,4'-bis(diethylamino)benzophenone (acquired from Chitec's Chivacure EMK), 4,4'-bis(N,N'-dimethylamino)benzophenone (milaxone), bis(2,4,6-trimethylbenzylidene)-phenylphosphine oxide ( "BAPO" or Irgacure 819 from Ciba, and visible light initiators from Spectra Group Limited, Inc., such as H-Nu 470, H-Nu-535, H-Nu-635, H-Nu-Blue -640 and H-Nu-Blue-660, and combinations thereof. Referring back to UV light, the light can be UVA radiation, which is radiation having a wavelength between about 320 and about 400 nm; UVB radiation, which is between about 280 and about 320 nm; and/or UVC radiation, It is radiation having a wavelength between about 100 and about 280 nm. The dispersion can include any amount of free radical initiator as long as other desired components are present. For example, the free radical initiator can be present in an amount greater than zero and up to about 10% by weight of the dispersion, from about 0.1 to about 10% by weight of the dispersion, or from about 1 to about 6% by weight of the dispersion. In various non-limiting embodiments, all values and ranges of values between the above values are specifically intended to be encompassed. Shear thinning additives: In other embodiments, the dispersion also includes a shear-thinning additive to make the dispersion of silicon dioxide to minimize settling. The shear thinning additive may be selected from the group consisting of bentonite, urea-polyol-aliphatic copolymers, acrylic copolymers, and combinations thereof. In one embodiment, the shear thinning additive is bentonite. In another embodiment, the shear thinning additive is a urea-polyol-aliphatic copolymer. In another embodiment, the shear thinning additive is an acrylic polymer. The shear thinning additive that can be used is commercially available as BYK 410, 420 or 430. In various embodiments, the acrylic copolymer has the following structure: Wherein each of R ¹ and R ² is independently a group (C _n H _2n )OH, wherein n is from 15 to 20. For example, n can be 15, 16, 17, 18, 19, or 20. Furthermore, OH groups may be present at any position on the chain of R ¹ and R ² . R ¹ and R ² may have the same or different chain lengths. In one embodiment, the acrylic copolymer is N,N'-ethane-1,2-diylbis(12-hydroxyoctadec-1-amine) and has the structure: N,N'-ethane-1,2-diylbis(12-hydroxyoctadec-1-amine) wherein n of R ¹ and R ² are both 17. In other embodiments, the acrylic copolymer of Attagel 50 is available from BASF. In other embodiments, the shear thinning additive is a urea-polyol-aliphatic copolymer having the following structure: . In other embodiments, the shear thinning additive is a urea-polyol-aliphatic copolymer having the following structure: . In other embodiments, the shear thinning additive is a modified hydrogenated castor oil. The modified hydrogenated castor oil may be EFKA RM1900 from BASF. Additives : The dispersion may also or may not include, or include less than 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.5, 0.1, 0.05, or 0.01% by weight of one or more of the following Additives. The dispersion may alternatively comprise 0.01, 0.05, 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10% by weight of one or more of the additives set forth below. Such additives include, but are not limited to, those described in U.S. Patent No. 5,665,792 and U.S. Patent No. 6,099,787, each of which is incorporated herein in The disclosure is incorporated herein by reference. In various embodiments, the additive is selected from the group consisting of hydrocarbon carboxylic acid salts of Group IA and IIA metals, such as sodium bicarbonate, potassium bicarbonate and cesium carbonate, polyvinylpyrrolidone, polyacrylonitrile, and combinations thereof. Other additives include dyes, pigments, antioxidants, wetting agents, photosensitizers, chain transfer agents, leveling agents, defoamers, surfactants, bubble breakers, antioxidants, acid scavengers, thickeners, flame retardants , decane coupling agent, ultraviolet absorber, resin particles, core-shell particle impact modifier, soluble polymer and block copolymer. In various non-limiting embodiments, the inclusion of the above-described values and all values and ranges of values therebetween are specifically intended to be used herein. Any one or more of the above components may be combined with any one or more of the other components in whole or in various parts. Physical Properties : The dispersion also typically has a settling rate that is at least 75, 80, 85, 90, 95 or 99% less than the same composition without the shear thinning additive. The sedimentation rate is usually determined by the following method. However, any of the methods can be used. Method for determining the amount of deposits in a dispersion : The method of the present invention comprises providing a centrifuge to apply gravity to a ceramic dispersion, placing a sample of the ceramic dispersion in a sample container in a centrifuge, and applying the ceramic dispersion to the centrifuge A gravity of 25G to 2000G precipitates a certain amount of cerium oxide from the continuous phase, thereby forming a deposit comprising a topmost layer (25) disposed on the deposit, wherein the topmost layer (25) contains metal particles to allow visualization, And measuring the sediment content in the ceramic dispersion. The measuring step may additionally be defined as, or include, or (i) calculating the height of the deposit as a percentage of the total height of the dispersion (eg, as shown in FIG. 1A), and/or (ii) decanting the continuous phase and The mass of the deposit is measured to determine the mass percentage of the deposit based on the total mass of the dispersion, followed by gravity (e.g., as shown in Figure IB). Each is described in more detail below. In one embodiment, the method typically uses a centrifuge to apply a centripetal force to the dispersion that is many times the normal force of gravity. This increased G force accelerates particle isolation and precipitation. Any centrifugal device can be used. However, when the centrifuge is oriented such that the centrifuge tube containing the test dispersion is aligned with the direction of the applied centripetal force such that the top surface of the resulting precipitate is parallel to the top and bottom of the centrifuge tube, it tends to be easier to quantitatively evaluate the deposition. Content. In this way, the thickness of the precipitate (20) can be easily measured only by using a prescribed scale, such as a millimeter scale. An oscillating centrifuge that allows the centrifuge tube to swing into the position described can be used. Alternatively, a centrifuge can be used to mount the centrifuge tube to a flat circular plate, such as found in a device manufactured and sold by LUMISizer. In various embodiments, a LUMiSizer 6112-24 dispersion analyzer is used. The analyzer is designed to accelerate and follow the precipitation method by irradiating a beam of light through the centrifuge tube as the tube rotates. When a dispersion comprising large particles and small particles is used, a large amount of large particle precipitate (20) can be observed by the naked eye, while the remaining dispersion is still opaque to the probe of LUMiSizer 6112-24. The first method decanters the dispersion (30) from the precipitate (20) (see FIG. 1A), for example as shown in FIG. 1B, and measures the precipitate as a percentage of the total mass of the dispersion before applying the centrifugal centripetal force (20) ) the quality. The second method aligns the specified scale with the distance between the centrifuge tube and the bottom of the tube, the top of the dispersion, and the top of the precipitate (20) and reports the height of the precipitate (20) as a percentage of the total height of the dispersion. The rate of rotation of the centrifuge can be varied to minimize test time so that a measurable precipitate (20) can be observed while avoiding all or most of the particles being precipitated. The acceleration applied to the dispersion is calculated by the following equation: a _c = v ² / r = ω ² r = (2 π n _s ) ² r = (2 π n _rpm / 60) ² r where a _c = centripetal acceleration ( m / s ² ) v = tangential velocity ( m / s ) r = circular radius from the center of rotation to the point ( m ) in the dispersion column ω = angular velocity ( rad / s ) n _s = number of revolutions per Seconds ( 1 / s ) n _rpm = number of revolutions per minute ( 1 / min ) The sample can be prepared by pipetting the dispersion into a centrifuge tube to a height of 45 mm. Polyamine centrifuge tubes can be used to prevent dissolution of the tube by acrylate monomers. The acceleration of 2000 G usually precipitates all particles, which are not required. 500 G force can achieve the same undesired results. A rotational speed of about 600 RPM corresponding to 46 G reproducibly produces a measurable precipitate (20). The time at which the rotation is applied can then be varied to determine the optimal test time. Two test samples can then be removed from the centrifuge at 10 minute intervals. More specifically, the tube can be rotated at 46 ° C (for example, 600 rpm) for 10 to 60 minutes at 25 °C. Centrifugation can begin with a complete cannula (12 each). Every 10 minutes, the centrifugation can then be paused to remove one tube for sediment measurement while the remaining tubes continue to centrifuge. The height of the deposit and the total height of the dispersion can be measured by a scale having an accuracy of ±0.5 mm. The appropriate acceleration can depend, at least in part, on the characteristics of the particles in the dispersion. In one embodiment, when the particles are ceramic particles (D50 = 9 μm, mainly comprising cerium oxide particles and a small portion of alumina and zircon particles as large as 90 μm), an acceleration of approximately 46 G is sufficient. In various embodiments, the G force is 25 to 100, 30 to 95, 35 to 90, 40 to 85, 45 to 80, 50 to 75, 55 to 70, 60 to 65, 40 to 50, 40 to 45 or 45. Up to 50 G. In other embodiments, the G force is 100 to 2000, 200 to 1900, 300 to 1800, 400 to 1700, 500 to 1600, 600 to 1500, 700 to 1400, 800 to 1300, 900 to 1200, or 1000 to 1100 G. In other embodiments, the visualization of the sediment boundary can be customized by the addition of a small fraction of pigment (0.1 w% Oracet Blue 640). In the absence of pigment, the interface between the deposit and the supernatant can be rarely detected because the dispersion of the present invention typically does not have a clear supernatant. Instead, only the largest particles from the deposit tend to be apparent, while most of the small ceramic particles remain suspended in the supernatant, making them opaque. The dispersion used in ASTM D 2196-99 has a viscosity of typically 500 to 4,000 cps at 25 ° C and 30 RPM. In various embodiments, the viscosity of ASTM D 2196-99 at 25 ° C and 30 RPM is 600 to 3,900, 700 to 3,800, 800 to 3,700, 900 to 3,600, 1,000 to 3,500, 1,100 to 3,400, 1,200 to 3,300, 1,300 to 3,200, 1,400 to 3,100, 1,500 to 3,000, 1,600 to 2,900, 1,700 to 2,800, 1,800 to 2,700, 1,900 to 2,600, 2,000 to 2,500, 2,100 to 2,400 or 2,200 to 2,300 cps. A method of forming a dispersion: The present invention also provides a method of forming the dispersion. The method includes the steps of providing a UV curable acrylate monomer, providing cerium oxide, providing a free radical initiator, and providing a shear thinning additive. The method also includes the steps of combining a UV curable acrylate monomer, ceria, a free radical initiator, and a shear thinning additive to form a dispersion. One or more of these components may be combined with any one or more of the other components, either in whole or in various parts. In various non-limiting embodiments, in order to reduce the viscosity of the dispersion sufficient for 3D printing and to avoid the presence of agglomerated particles greater than one print layer thickness, the cerium oxide particles must undergo high shear during mixing to break large Ceria agglomerates. This requires the slow addition of 86.7% w of cerium oxide powder to a mixture of 1.7% w dispersant Variquat CC 42 NS and 11.6% w of the main acrylic monomer upon mixing, followed by continuous shear mixing of the high viscosity paste for several hours. A cerium oxide syrup concentrate ("cerium oxide concentrate") was prepared. In various embodiments, the cerium oxide concentrate is then mixed with the remaining liquid components (e.g., "photopolymer diluent") to reduce the viscosity of the dispersion suitable for 3D printing. The ceria photopolymer dispersion can be prepared, for example, using high shear mixing, such as by the National Board number/U-1 131 of the anchor-double helix mixer manufactured by Chemineer or by using Amazon.com. KFE5T Flex Edge Beater's 5-quart KitchenAid mixer provides high shear mixing. In some embodiments, it is important to have sufficient shear with a high viscosity ceria concentrate to depolymerize the cerium oxide before reducing the viscosity by adding a photopolymer diluent. For example, 0.10 Kg of dispersant Variquat CC 42 NS and 0.7 Kg of acrylic monomer can be added to a 5 quart KitchenAid mixer equipped with a nylon coated plate stirrer. These liquid components can then be mixed for 1 minute at the slowest speed setting. The cerium oxide powder can then be added in small aliquots such that the consistency does not exceed the syrup stage while allowing sufficient mixing between aliquot additions to reduce the viscosity back to the high viscosity liquid. The addition of cerium oxide usually takes 45-60 minutes. The agitator can then be turned into a curved edge agitator to increase the shear force that breaks the ceria agglomerate by having a small clearance between the agitating blades and the mixing channel walls. Stirring can continue for another two hours in this manner. As the viscosity decreases due to the depolymerization of cerium oxide, the stirring speed can be increased, however, the stirring speed should be slowed to maintain the temperature of the mixture below 50 ° C to avoid polymerization of the dispersion. This cerium oxide concentrate can then be mixed with the remaining liquid components ("photopolymer diluent") to reduce the viscosity of the dispersion suitable for 3D printing. In a mixing vessel equipped with a temperature controller, such as a Chemineer vessel, the temperature of the vessel can be controlled by a cooling jacket in addition to the agitation speed. Usually, but not necessarily, a higher agitation speed is used at the end of the mixing time to ensure that the agglomerates break. Any high shear blade or paddle (such as a double helix) will provide sufficient shear to break the agglomerates. Ceramic articles : Dispersions can be used to form ceramic articles. The ceramic article is not particularly limited and can be any ceramic article known in the art. For example, ceramic articles are typically ceramic cores or ceramic shells that produce molds for investment casting of nickel superalloy portions. In other embodiments, the dispersion can be used to form ceramic articles that are involved in the casting or formation of metal parts and many different types of castings. Method of Forming a Ceramic Article : The present invention also provides a method of forming a ceramic article from a dispersion. The method comprises the steps of: applying a layer of ceramic dispersion to the surface and B. selectively exposing the layer to actinic radiation imagewise to form an imaging cross section. The method also includes the steps of applying a second layer of the ceramic dispersion to the imaging section and D. selectively exposing the second layer to actinic radiation imagewise to form a second imaging section. The method also includes the steps of E. repeating steps (C) and (D) to produce a three-dimensional ceramic green article and F. sintering the three-dimensional ceramic green article in a furnace to form a ceramic article. A. The step of applying a layer of the ceramic dispersion to the surface may be additionally defined as applying a dispersion having a thickness of 50 to 100, 55 to 95, 60 to 90, 65 to 85, 70 to 80 or 75 to 80 μm to the surface. Layer. Further, the surface is not particularly limited and may be any surface known in the art. For example, typically, all layers in a part structure have the same thickness, such as 50 or 100 μm. However, the layer may be 150 or 200 μm thick, but then, the stepping step on the inclined surface may be too large. In various embodiments, a series of layers of vertical walls are formed with a greater layer thickness while establishing a layer that forms a sloped or rounded surface with a smaller layer thickness. Thicker layers tend to build faster. However, the contoured area of the part is required to minimize the step height. The coating step is typically additionally defined as coating using a computer controlled spatula. The doctor blade can have 1-3 baffles wherein the blade can be closed or not closed such that a portion of the vacuum applied pulls the dispersion up into the blade to aid deposition onto the surface of the previous layer portion. B. The step of selectively exposing the layer to actinic radiation imagewise may additionally be defined as a UV laser exposed to the 325-365 nm range, which is directed onto the surface of the dispersion by an XY scanning mirror. The computer control of the mirror can be used to draw a cross section of the part such that only the part section selectively receives UV radiation. Alternatively, a group of LED lamps having wavelengths of 260, 265, 280, 310, 325, and 340 nm, 365, 375, and 385 nm and/or 405 nm, or a combination thereof, can be reflected from a digital micro-mirror array (DLP wafer) to be dispersed The cross-sectional image of the layer is exposed on the surface of the liquid such that only the cross-section of the part selectively receives UV radiation. C. The step of applying the second layer of the ceramic dispersion to the imaging section may be the same as step A or may differ in one or more aspects. For example, the second layer can be the same or different from the first layer in terms of composition, thickness, size, coating method, and the like. D. The step of selectively exposing the second layer to actinic radiation imagewise to form a second imaging cross section may be the same as step B or may differ in one or more aspects. For example, the second layer can be selectively exposed in the same or different manner as the first layer, can be exposed to the same or different actinic radiation, and can be the same, more or less exposed than the second layer In radiation. E. The steps of repeating steps (C) and (D) to produce a three-dimensional ceramic green article can be performed one or more times. For example, steps (C) and (D) may be repeated as many times as selected by those skilled in the art, such as 50 to 5,000. F. The step of sintering a three-dimensional ceramic green article in a furnace to form a ceramic article is typically additionally defined as heating in a furnace at a temperature of 1100-1600 °C. Generally, the time and temperature can be any time and temperature known in the art. In addition, the furnace type can be any furnace type known in the art. Moreover, the method can alternatively be described as three-dimensional printing of the ceramic green article. Thus, the method can include any one or more of the steps associated with three-dimensional printing in the art. In various non-limiting embodiments, one or more of the steps of the method can be as described in: (A) Rapid Prototyping & Manufacturing: Fundamentals of StereoLithography, January 15, 1992, Paul F. Jacobs; (B) Stereolithography & Other RP&M Technologies: From Rapid Prototyping to Rapid Tooling, Paul F Jacobs, 1995; (C) US Patent No. 4,093,017; (D) Integrally Cored Ceramic Investment Casting Mold Fabricated By Ceramic Stereolithography, Chang-Jun Bae; (E) Parametric Study And Optimization Of Ceramic Stereolithography, Kahn Chia Wu; and/or (F) Towards Inert Cores for Investment Casting, Martin Riley, each of which is associated with the method in various non-limiting embodiments The text is fully incorporated herein. The method can also include the step of post-curing the three-dimensional ceramic green article prior to the sintering step. Although most dispersions are typically cured by the radiation provided during the part build process, the parts are typically only partially polymerized. The post-cure step can additionally be described as a condition in which the SL portion is post-cured to substantially complete the polymerization process and to improve the final mechanical strength of the ceramic green article. A 3D Systems Inc. Post-Curing Device (PCA) can be used, which is essentially an "oven" with a UV source that radiates and reflects within the device. The PCA has a turntable that provides a more distributed exposure to actinic UV illumination. The standard post cure time for this device is 60 minutes. In various embodiments, Prodways L5000 machines can be used and specific parameters can be selected by those skilled in the art. In other embodiments, a laser based stereolithography system can be used. Still further, UV 3D printing can be used that exposes the photopolymer layer from the bottom via a glass plate (rather than printing from the top exposed to free air). In all such systems, parameters, cycle times, etc. can be selected by those skilled in the art. Ceramic green product : The present invention also provides the ceramic green product itself. The ceramic green article can be cured, partially cured or uncured, for example by UV radiation. In other words, the ceramic green article can include a cured, partially cured or uncured monomer, as described above. In various embodiments, the ceramic green article is cured using a UV exposure sufficient to cure the layer thickness by 200% (i.e., over 100 μm over 100 μm layer). In such embodiments, the ceramic green article typically has a flexural modulus greater than 10 MPa, greater than 40 MPa, greater than 100 MPa, as measured by ASTM D790. The combination of the ceramic photopolymer formulation and the UV exposure should form a green product having an acceptable green strength as described above and a crimp factor of less than 3, preferably less than 2 and optimally less than 1.5, such as by Rapid Prototyping & Manufacturing: Fundamentals of StereoLithography, January 15, 1992, as determined by the method described in Paul F. Jacobs, the documents relating to various non-limiting examples are expressly incorporated herein by reference in their entirety. . In any of the various non-limiting embodiments, any one or more of the components, compounds, reactants, solvents, or any one of the US Provisional Patent Applications, both of which are incorporated herein by reference. Additives, method steps, equipment components, and the like can be used herein. Each of these applications is hereby expressly incorporated by reference in its entirety in its entirety in its entirety in its entirety. EXAMPLES Samples were prepared by pipetting the dispersion into a centrifuge tube to a height of 45 mm (Fig. 2; 10 x 10 mm square section). Polyamine centrifuge tubes are used to prevent tube disintegration by acrylic acid formulations). The tube was then spun for 10 to 60 minutes at 46 ° C (for this device, 600 rpm) at 25 °C. Centrifugation begins with a complete cannula (12 each). Every 10 minutes, the centrifugation was paused to remove one tube for sediment measurement while the remaining tubes continued to centrifuge. The height of the deposit and the total height of the formulation are measured by a scale having an accuracy of ±0.5 mm. 2A and 2B show the height of the precipitate in the form of a percentage of the total dispersion height as a function of the centrifugation time (46 G) of the above dispersion. It was found that it is difficult to visually distinguish the separator between the white ceramic liquid dispersion and the ceramic precipitate (20). It has also been found that the fine metal particles (25) resulting from the abrasion of the stainless steel propeller blades used to prepare and maintain the ceramic suspension are isolated on top of the precipitate (20), facilitating visual differentiation and measurement using a prescribed scale. The study used various visual auxiliaries, including dyes, pigments, and graphite, to identify the best identifier: 0.1 w% blue dye Oracet Blue 640 from BASF Canada Inc., 100 Milverton Drive, Mississauga, ON L5R 4H1, Canada. A comparison of the test indexes for centrifuge acceleration at 46 G was performed to observe a 150 mm column of the ceramic dispersion under normal 1 G acceleration. Figures 3A and 3B show the sedimentation characteristics of three different materials measured by a centrifugal method at 46 G and normal gravity. This comparison shows the effectiveness of the centrifugal acceleration method. The reproducibility of the method was demonstrated by comparing 6 replicates of the measurements as shown in Figures 4A, 4B and 4C. Compare the method of mass measurement with the method of using sediment height measurement. It is obvious that the method of using the height of the precipitate is more repeatable. All combinations of the foregoing embodiments throughout the disclosure are hereby explicitly covered in one or more non-limiting embodiments, even if such disclosure is not described in a single paragraph or section above. In other words, the embodiments explicitly covered may include any one or more of the elements described above selected and combined from any part of the invention. One or more of the above-described values may vary by ±5%, ±10%, ±15%, ±20%, ±25%, etc., as long as the variation remains within the scope of the present invention. Unexpected results can be obtained from all members of the Markush group independently of all other members. Sufficient support may be provided for individual embodiments and for specific embodiments within the scope of the appended claims. The subject matter of all combinations of independent and dependent request items (single dependencies and multiple dependencies) is explicitly covered herein. The present invention is intended to be illustrative, and not restrictive. Many modifications and variations of the present invention are possible in the light of the teachings herein. It is also to be understood that the scope of the present invention is to be construed as being / or partial values, even if the values are not explicitly written in this article. Those skilled in the art will readily recognize that the scope and sub-ranges are fully described and the various embodiments of the present disclosure can be made, and the scope and sub-range can be further described as a half, one-third, and four One, one fifth, etc. As an example only, the "0.1 to 0.9" range can be further described as the lower third (ie 0.1 to 0.3), the middle third (ie 0.4 to 0.6) and the upper third (ie 0.7 to 0.9), which are individually and collectively within the scope of the appended claims, and which may be individually and/or collectively dependent, and provide sufficient support for specific embodiments within the scope of the appended claims. In addition, as to the language defining or modifying the scope, such as "at least", "greater than", "less than", "not exceeding", and the like, it should be understood that such language includes sub-ranges and/or upper or lower limits. As a further example, the range of "at least 10" essentially includes a sub-range of at least 10 to 35, a sub-range of at least 10 to 25, a sub-range of 25 to 35, etc., and each sub-range may be individually and/or collectively dependent and Particular embodiments within the scope of the appended claims are provided with sufficient support. Finally, the individual numbers within the scope of the disclosure may be relied upon and provide sufficient support for the particular embodiments within the scope of the appended claims. For example, the "1 to 9" range includes various individual integers, such as 3, and individual numbers including decimal points (or fractions), such as 4.1, which may depend on such numbers and are within the scope of the appended claims. Particular embodiments provide sufficient support.

20‧‧ ‧ sediment

25‧‧‧ top layer; metal particles

30‧‧‧Dispersion

Other advantages of the present invention will be readily appreciated, as the advantages will be better understood by reference to the following embodiments in conjunction with the accompanying drawings in which: Figure 1A is a test tube for use in a centrifuge A perspective view showing deposits, metal particles and a certain amount of continuous phase not decanted therefrom. Figure 1B is a perspective view of a test tube for use in a centrifuge showing deposits, metal particles, and a continuous phase decanted therefrom. Figure 2A is a photograph of the measurement of the height of the precipitate as a percentage of the total dispersion height. Figure 2B is a line graph of the height of the sediment string as a function of centrifugation time. Figure 3A is a second line graph of settling height as a function of centrifugation time. Figure 3B is a line graph of the settling height over time as the dispersion settles without centrifugation. Figure 4A is a bar graph showing the settling height as a function of repetition. Fig. 4B is an enlarged view of Fig. 4A. Figure 4C is a bar graph showing the mass of the precipitate as a function of repetition.

Claims (15)

A method for determining a content of a deposit in a ceramic dispersion for additive fabrication, wherein the ceramic dispersion comprises (a) a radically curable monomer as a continuous phase, and (b) a dioxide as a dispersed phase矽, the dispersed phase is dispersed in the continuous phase and is present in an amount of 55 to 70 volume percent based on the total volume of the ceramic dispersion, and (c) metal particles, the method comprising the steps of: A. providing a centrifuge Applying gravity to the ceramic dispersion; B. placing a sample of the ceramic dispersion in a sample container in the centrifuge; C. applying a gravity of 25 G to 2000 G to the ceramic dispersion in the centrifuge from the continuous Precipitating a certain amount of the cerium oxide, thereby forming a deposit comprising a topmost layer disposed on the deposit, wherein the topmost layer comprises the metal particles to permit visualization; and D. measuring the The deposit content in the ceramic dispersion: (i) calculating the height of the deposit as a percentage of the total height of the dispersion; and/or (ii) decanting the continuous phase and measuring the mass of the deposit to Based on application The total mass of the dispersion of the force measured prior to the mass percentage of the deposit. The method of claim 1, wherein the metal particles are present in an amount of less than 0.5% by weight based on the total weight of the dispersion. The method of claim 1 or 2, wherein the metal particles are steel. The method of claim 1 or 2, wherein the metal particles are derived from a metal device for forming the dispersion. The method of claim 1 or 2, further comprising a dye or pigment present in an amount of from 0.01 to 0.3% by weight, based on the total weight% of the dispersion. The method of claim 5, wherein the dye is an anthraquinone dye. The method of claim 5, wherein the pigment has a density greater than 3 g/cm ³ . The method of claim 1 or 2, wherein the applied gravity is 40G to 50G. The method of claim 1 or 2, wherein the ceramic dispersion has a viscosity of 500 to 4,000 cps at 25 ° C and 30 RPM using ASTM D 2196-99. The method of claim 1 or 2, wherein the cerium oxide comprises particles having a particle size of from 0.04 to 90 microns. The method of claim 1 or 2, wherein the cerium oxide comprises a combination of microparticles having a particle size of 1 to 90 micrometers and nanoparticles having a particle size of 10 to 500 nanometers, and an average particle size ratio of the microparticles: nanoparticles is 1:2 to 1:200. The method of claim 1 or 2, wherein the dispersion further comprises a shear thinning additive selected from the group consisting of bentonite, urea-polyol-aliphatic copolymer, acrylic copolymer, and combinations thereof. The method of claim 1 or 2, wherein the radical curable monomer is an acrylate monomer. The method of claim 13, wherein the acrylate monomer is a polyfunctional (meth) acrylate. The method of claim 1 or 2, wherein the dispersion does not contain a monomer other than (meth) acrylate.