Compositions and methods of making a ceramic ribbon

Abstract

A green tape composition for forming a green tape, the composition including a ceramic powder and a radiation-curable binder composition comprising a photoinitiator, a monomer, and a dispersant. The ceramic powder is present at a concentration of greater than 40 vol. %. The porosity of the green tape is less than 10%. The green tape is sintered at a temperature range from 950°C to 1500°C to form a continuous ribbon ceramic.

Description

Attorney Docket No. SP24- 274COMPOSITIONS AND METHODS OF MAKING A CERAMIC RIBBONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 63 / 717,393 filed November 7, 2024, the content of which is incorporated herein by reference in its entirety.FIELD

[0002] The present disclosure relates generally to compositions and methods of making a ceramic ribbon and, more particularly, to compositions and methods of making a ceramic ribbon using radiation-curable green body.BACKGROUND

[0003] Ceramics ribbons have traditionally been manufactured using a tape casting process to create thin green tapes. This process involves the use of a variety of ceramic powders, which must be properly dispersed in a slurry with appropriate binders and solvents. The slurry is then pumped into a reservoir and spread out in a thin layer on a carrier film. As the solvent evaporates, the binder and ceramic particles are left behind, forming the green tape. This green tape can subsequently be cut to the desired size and processed through lamination, hot pressing, or sintering in a kiln.

[0004] A common issue encountered with tape-cast green tapes is porosity, which arises from the settling of ceramic powder within the binder. This settling prevents the green tape from achieving full density, leading to additional shrinkage during the sintering process. The shrinkage can result in deformation or cracking of the ribbon. Furthermore, pores that do not fully close during sintering can prevent the final product from reaching a fully dense state. Additionally, the use of organic solvents, such as ketones, toluene, and xylene, in the formulation requires special precautions due to their flammability, toxicity, and environmental impact. The excess solvent must be thoroughly dried before sintering, adding to the complexity and cost of the manufacturing process.

[0005] Consequently, there is a need to develop a tape casting process that minimizes shrinkage by achieving a high initial green body density, approaching the theoretical densityAttorney Docket No. SP24- 274 of the green tape. Additionally, there is a need for more environmentally friendly processes that reduce the use of hazardous solvents.SUMMARY

[0006] Certain embodiments commensurate in scope with the originally claimed subject matter are summarized below. These embodiments are not intended to limit the scope of the claimed invention, but rather these embodiments are intended only to provide a brief summary of possible forms of the invention. Indeed, the present disclosure may encompass a variety of forms that may be similar to or different from the embodiments set forth below.

[0007] In some embodiments, a green tape composition to form a green tape comprises a ceramic powder and a radiation-curable binder composition which comprises a photoinitiator, a monomer, and a dispersant. The ceramic powder may be present in an amount greater than 40 vol. %. The porosity of the green tape is less than 10%. The green tape may be sintered at a temperature range from 950°C to 1500°C to form a continuous ceramic ribbon.

[0008] In some embodiments, the ceramic powder in the green tape composition comprises at least one of zirconia, yttria-stabilized tetragonal zirconia polycrystals, alumina, or lithium- garnet.

[0009] In some embodiments, the monomers in the green tape composition may comprise at least one of a monofunctional acrylate, a difunctional acrylate, and a trifunctional acrylate, methacrylate monomers, or epoxide monomers.

[0010] In some embodiments, the monomer in the green tape composition may comprise at least one of 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, tripropylene glycol diacrylate, trifunctional or ethoxylated acrylate.

[0011] In some embodiments, the ceramic powder in the green tape composition may be present in an amount greater than about 45 vol. %, more preferably in an amount greater than 50 vol. %.

[0012] In some embodiments, the ceramic powder in the green tape composition may comprise doped lULasZ O variants.

[0013] In some embodiments, the dispersant in the green tape composition may comprise at least one of a fatty acid, a fish oil, a poly (ethylene imine), or a phosphate ester.

[0014] In some embodiments, the dispersant in the green tape composition may be present in the radiation-curable binder composition in an amount in a range of 0 wt. % to about 2.0 wt. %.Attorney Docket No. SP24- 274

[0015] In some embodiments, the photoinitiator in the green tape composition is present in the radiation-curable binder composition in an amount in a range from about 0.1 wt. % to about 1.0 wt. %.

[0016] In some embodiments, the photoinitiator in the green tape composition comprises ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate.

[0017] In some embodiments, the green tape composition may further comprise at least one of an epoxy acrylates, a urethane acrylate, a polyester acrylate, or a polyether acrylate.

[0018] In some embodiments, the green tape composition may further comprise a plasticizer, an antioxidant, UV stabilizers, or a toughening agent.

[0019] In some embodiments, the green tape composition may be solvent-free.

[0020] In some embodiments, the ceramic powder in the green tape composition may comprise lithium garnet and the dispersant may be oleic acid.

[0021] In some embodiments, a shear viscosity of the green tape composition before cured by radiation may be less than about 10000 poise, preferably less than about 5000 poise, more preferably less than about 3000 poise at a shear rate of 100 / s as measured by a parallel plate rheometer at room temperature.

[0022] In some embodiments, a method of making a sintered ceramic ribbon comprises forming a green tape by continuously depositing a green tape composition onto a carrier, wherein the green tape composition comprises a ceramic powder and a radiation-curable binder composition; wherein the radiation-curable binder comprises a photoinitiator, a monomer, and a dispersant; curing the green tape under ultraviolet (UV) radiation to cause the radiation-curable binder composition to polymerize and bond together with the ceramic powder; an heating cured green tape to remove the radiation-curable binder composition and form a sintered ribbon ceramic.

[0023] In some embodiments, the cured green body may be heated at a temperature in a range from about 900°C to about 1500°C for a time in a range of about 10 seconds to about 10 minutes.

[0024] In some embodiments, the green tape has a thickness of less than about 200 pm, preferably less than about 100 pm, more preferably less than about 50 pm.

[0025] In some embodiments, a thickness of the sintered ceramic ribbon may be less than about 100 pm, for example less than about 50 pm, such as less than about 30 pm.

[0026] In some embodiments, the green tape further may further comprise multiple layers of the green tape composition.Attorney Docket No. SP24- 274

[0027] In some embodiments, at least one layer of the multiple layers of the green tape composition may comprises a pore former. The pore former may comprise at least one of graphite, carbon black, or PMMA beads.

[0028] In some embodiments, the sintered ceramic ribbon may comprise a fully dense structure.

[0029] In some embodiments, the sintered ribbon ceramic may further comprise a multilayer structure, with at least one layer comprising a fully dense structure and at least one layer comprising a porous structure.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and other features and advantages of embodiments of the present disclosure are better understood when the following detailed description is read with reference to the accompanying drawings, in which:

[0031] FIG. 1 is a flow chart illustrating example methods of the embodiments of the disclosure;

[0032] FIG. 2A is a graph showing viscosity as a function of shear rate for an 80 wt. % solids loading of formulation 1C of embodiments of the disclosure;

[0033] FIG. 2B is a graph showing viscosity as a function of shear rate for an 87 wt. % solids loading of formulation 1C of embodiments of the disclosure;

[0034] FIG. 3A is an SEM image of a sintered sample made with UV-cured material and zirconia.

[0035] FIG. 3B is an SEM image of a sintered sample produced via the traditional tape casting method;

[0036] FIG. 4 is a TGA (Thermogravimetric Analysis) data plot of three types of zirconia tapes of the embodiments of the disclosure; and

[0037] FIG. 5 is an SEM (Scanning Electron Microscopy) image of a UV-curable green tape after firing of the embodiments of the disclosure.DETAILED DESCRIPTION

[0038] When introducing elements of various embodiments of the present disclosure, the articles “a”, “an”, and “the” are intended to mean that there are one or more of the elements. The terms “comprising,” including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Additionally, it should be understood that references to “one embodiment” or “an embodiment” of the presentAttorney Docket No. SP24- 274 disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

[0039] Present embodiments are directed toward radiation-curable green tape composition that include a ceramic powder and a radiation-curable binder composition. The volume percentage of ceramic powder within the total composition is at a concentration greater than 45% by volume, preferably at a concentration of greater than 50 vol. %, and more preferably at a concentration of greater than 55 vol. %. In some embodiments, the ceramic powder includes or doped lULasZ^On variants. The particles may be used as received or prepared by attrition milling, ball milling, or jet milling. The particles may contain a monomodal or multimodal particle size distribution (PSD).

[0040] The radiation-curable binder composition can polymerize and bond together with a ceramic powder when exposed to activation light from a suitable activation light source (e.g., ultraviolet (UV) radiation). In some embodiments, the radiation-curable binder composition may include a photoinitiator, a monomer, and a dispersant. The monomers serve as building blocks for the polymer network that forms upon exposure to the activation light. Specifically, the monomers undergo polymerization, cross-linking, and copolymerization reactions, facilitated by the photoinitiator. This process results in the formation of a robust, three- dimensional network that binds the ceramic particles together, providing structural integrity and mechanical strength to the green tape. The choice of monomers, whether monofunctional, difunctional, or trifunctional, influences the properties of the final polymer network, such as its flexibility, hardness, and adhesion of the ceramic particles. The monomers may comprise a monofunctional acrylate, a difunctional acrylate, a trifunctional acrylate, a methacrylate monomers, or epoxide monomers. In some embodiments, the monomer may comprise at least one of 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, tripropylene glycol diacrylate, or trifunctional ethoxylated acrylate. The photoinitiator may include any suitable structure capable of absorbing light (e.g., UV, visible light) emitted by the activation light source and, in response, promote copolymerization of the green tape composition. In some embodiments, the photoinitiator may be present in the radiation-curable binder composition in an amount in a range of 0.1 wt. % to 1.0 wt. %. In some embodiments, the photoinitiator may comprise ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate (Omnirad TPO-L from IGM Resins). In some embodiments, the dispersant may comprise at least one of a fatty acid, a fish oil, poly (ethylene imine), or phosphate esters. As used herein, a dispersant is one or more compounds designed to increase the wetting and / or stability of the ceramicAttorney Docket No. SP24- 274 particles. In some embodiments, the dispersant may be present in the radiation-curable binder composition in an amount in a range of 0 wt. % to 2.0 wt. %, such as in the range of about 0.01 wt. % to about 1.9 wt., about 0.05 wt. % to about 1.8 wt. %, or about 0.1 wt. % to about 1.8 wt. Providing a dispersant can increase the wetting of the ceramic particles, which can facilitate higher loading of particles (e.g., about 80 wt.% or more). Providing a dispersant may also increase stability of the composition (e.g., decrease settling) and / or improve flow properties of the composition (e.g., decrease shear-thickening). The dispersant can be incorporated into the green tape composition in several ways. It may be mixed with the ceramic powder prior to its dispersion in the radiation-curable binder composition, added after the ceramic powder has been dispersed in the radiation-curable binder composition, or directly added to the radiation-curable binder composition before mixing with the ceramic powder. In some embodiments, the dispersant may be oleic acid. When LiyLasZrjOtz (LLZO, lithium garnet) is used as the ceramic particles, the oleic acid may passivate the surface of the LLZO, making the cast tape stable in ambient air. This passivation process converts the LLZO into H-LLZO (protonated LLZO). Additionally, the acid treatment can remove CO? volatiles from Lij-CO?, whether pre-existing or added. As a result, the degassing temperature of LLZO can be reduced from approximately about 730°C to below about 500°C. The lower degassing temperature offers several advantages, including the ability to maintain a clean atmosphere (free of H?O and CO2) in the sintering temperature zone, which is beneficial for both fast firing and batch firing processes.

[0041] In some embodiments, the green tape composition may further include an acrylate oligomer. The acrylate oligomer may comprise epoxy acrylates, urethane acrylates, polyester acrylates, or polyether acrylates. Preferred radiation-curable oligomers may include urethane acrylates. Suitable urethane acrylates may include Miramer PU2100 and / or Miramer PS2500. Acrylate oligomers can contribute to the overall properties of the final polymer network and provide additional cross-linking sites. Additionally, the presence of oligomers improves the flow and wetting characteristics of the coating, facilitating the uniform distribution of ceramic particles and enhancing the overall quality of the green tape. Urethane acrylates, in particular, are preferred for applications requiring high flexibility and good adhesion, as they provide excellent elasticity and impact resistance in the cured state.

[0042] In some embodiments, the composition may further include a plasticizers, antioxidants, UV stabilizers, or toughening agents. Plasticizers may improve the flexibility and workability of the green tape and reduce the glass transition temperature (Tg) of theAttorney Docket No. SP24- 274 polymer, making it more pliable and easier to handle. This is particularly important during the processing and handling stages, where increased flexibility can prevent cracking and brittleness. Common plasticizers used in these compositions may include phthalates, adipates, and other low-molecular-weight compounds. Plasticizer selection depends on the specific requirements of the application, such as the desired level of flexibility and the compatibility with other components in the composition. Antioxidants may help prevent degradation of the polymer by scavenging free radicals that can cause oxidative damage, thus extending the shelf life and stability of the green tape. In some embodiments, the antioxidants may include butylated hydroxy toluene (BHT) or / and Omnistab IN 516 (IGM Resins). UV stabilizers may include any suitable molecule capable of reacting with a reactive species in the green tape composition to block undesirable side reactions, such as premature polymerization of the binder before exposure to the activation source. Preferred toughening agents may include fluorinated compounds or silicone-based compounds. Toughening agents enhance the impact resistance and toughness of the green tape, making it more durable and resistant to mechanical stress. In some embodiments, the toughening agent is Xiameter OFX-0190 (Dow).

[0043] In some embodiments, the green tape composition is solvent-free. Compared to the traditional tape casting method, this approach eliminates the need for solvent drying and evaporation, thereby avoiding issues such as high shrinkage and cracking. In conventional processes, organic solvents such as methyl ethyl ketone (MEK), toluene, and xylene are often used to dissolve the polymer binder and stabilize the ceramic particles. However, the drying of these organic solvents can pose significant chemical safety risks during large-scale manufacturing and can also have adverse environmental impacts. By eliminating solvents, the solvent-free green tape composition not only enhances the mechanical integrity of the final product but also improves the safety and environmental sustainability of the manufacturing process.

[0044] Green tape compositions exhibit shear-thinning rheological properties, which can be important for the formation of green tapes, especially at high loading levels. Viscosity is a key factor influencing the processability of the formulation during coating. The temporary reduction in viscosity under high shear conditions during the coating process facilitates tape formation. The preferred shear-thinning behavior of the green tape composition is characterized by a shear viscosity less than about 10,000 poise at a shear rate of 100 / s, asAttorney Docket No. SP24- 274 measured by a parallel plate rheometer at room temperature, for example less than 5,000 poise, or less than 3,000 poise.

[0045] With the foregoing in mind, embodiments of methods 100 of making a sintered ceramic ribbon in accordance with the embodiments of the disclosure will be discussed with reference to the flow chart in FIG. 1. In a first step 110, a green tape is formed by continuously depositing a green tape composition onto a carrier. The green tape composition comprises a ceramic powder and a radiation-curable binder composition. The radiation- curable binder may include a photoinitiator, a monomer, and a dispersant. It should be noted that the ingredients may be mixed in different orders. For example, in some embodiments, the components of the monomer may be added first, followed by the dispersant and the photoinitiator to form the radiation-curable binder composition, and then ceramic particles may be added to form the radiation-curable slurry. In some embodiments, the porosity of the green tape may be less than about 10%. In some embodiments, the porosity of the green tape may be in a range from about 1% to about 3%, about 3% to about 5%, about 5% to about 7%, about 7% to about 9%, or about 9% to about 10%.

[0046] Methods of forming a continuous green tape from UV-curable compositions on carrier or liner films are numerous and include roll coating (forward, reverse, squeeze, wipe, gravure, tensioned, kiss, etc.), knife coating, air knife, extrusion, slot die coating, rod coating, curtain coating, rotary screen printing, jetting, and spray, among others. However, the material may be highly filled with inorganic particles, which can have abrasive effects on various coating implements, leading to shorter tool life and possible contamination of the composition. To avoid these issues and simplify clean-up and change-over times, methods for coating between liners (films), also known as wet lamination, may be employed. The two most common candidates are bar coating between liners and fluid-fed nip rollers. In the case of the nip roller approach, metal rollers may provide easier gap setting, and calendaring roll stacks or lamination roller systems are often used, which can also enable temperature control. In high-speed production, these roll systems and round bar techniques may produce ribbing instabilities depending on the material rheology, and so notch bar coating might be preferred as it eliminates the negative pressure condition that can arise at the exit of other systems. Some examples of relevant laboratory equipment can be purchased from Chemlnstruments Inc., which provides products such as laminators, universal coaters, hotmelt coaters, and mini-coaters, each of which could be used to produce samples if UV curing capability and appropriate fluid delivery are added. In some embodiments, the green tape may have aAttorney Docket No. SP24- 274 thickness less than about 200 micrometers ( m), for example less than 100 pm, such as less than 50 pm. In some embodiments, a thickness of the green tape may be in a range from about 10 pm to about 20 pm, about 20 pm to about 50 pm, about 50 pm to about 100 pm, about 100 pm to about 150 pm, or about 150 pm to about 200 pm.

[0047] In some embodiments, the green tape can comprise multiple layers of the green tape composition. This multilayer approach allows for the incorporation of different properties and functionalities within a single green tape. The formation of multilayer green tapes can be achieved using various coating techniques, such as those mentioned above, by sequentially depositing each layer onto the carrier or liner film. The use of wet lamination methods, such as bar coating between liners or fluid-fed nip rollers, may be particularly advantageous for creating well-defined, uniform multilayer structures. Note that sequential layer deposition does not need to be done with the same technique, and various combinations of techniques can be employed sequentially. However, some embodiments allow for the simultaneous formation of multiple layers via processes such as multilayer slot die coating, multilayer slide coating, multilayer extrusion, and any combination of these with the other mentioned coating methods.

[0048] In certain embodiments, at least one layer of the multilayer green tape composition may further include a pore former. Suitable pore formers may comprise graphite, carbon black, PMMA beads, or combinations thereof. These pore formers may be added to create controlled porosity (i.e. percentage of void space or gaps) in the final sintered ceramic. During the sintering process, the pore formers burn out, leaving behind a porous structure. The choice of pore former and its concentration can be tailored to achieve the desired level of porosity and pore size distribution, thereby enhancing the functional properties of the sintered ribbon ceramic.

[0049] The illustrated process 100 continues with the curing process 120. Once the green tape is formed, it is cured under UV radiation. This curing process causes the radiation- curable binder composition to polymerize and bond together with the ceramic powder, forming a stable green body. UV sources such as halogen lamps, fluorescent lamps, LEDs, and other suitable light sources can be used for this step. In some embodiments, the light source can be configured to emit a light beam comprising an UV wavelength or a visible wavelength. In some embodiments, the wavelength of the light beam can be in a range from about 10 nanometers (nm) to about 400 nm, from about 100 nm to about 400 nm, from about 200 nm to about 400 nm, from about 10 nm to about 300 nm, from about 100 nm to aboutAttorney Docket No. SP24- 274300 nm, from about 200 nm to about 300 nm, from about 10 nm to about 200 nm, from about 100 nm to about 200 nm, or any range or subrange therebetween. In some embodiments, the operating wavelength range may be over a range of optical wavelengths from about 315 nm to about 400 nm, from about 280 nm to about 315 nm, from about 100 nm to about 280 nm, or from about 122 nm to about 200 nm. In some embodiments, the wavelength of the light beam can be in a range from about 300 nm to about 1,000 nm, from about 350 nm to about 900 nm, from about 400 nm to about 800 nm, from about 500 nm to about 700 nm, or any range or subrange therebetween. In some embodiments, the wavelength of the light beam can be about 365 nm, about 415 nm, or about 590 nm. In some embodiments, the wavelength of the light beam can correspond to a wavelength that the photoinitiator is sensitive to. In some embodiments, 365 nm LED lamps from Phoseon Technology were utilized for the curing process.

[0050] After step 120, the method can proceed to step 130. The cured green tape undergoes heating and sintering. This step removes the radiation-curable binder and consolidates the ceramic powder, resulting in a dense and uniform sintered ribbon ceramic. The cured green body may be sintered at a temperature in a range from about 950°C to about 1500°C for a time in a range from about 10 seconds to about 10 minutes. In some embodiments, the temperature for sintering may be in a range from about 900°C to about 1000°C, about 1000°C to about 1100°C, about 1100°C to about 1200°C, about 1200°C to about 1300°C, about 1300°C to about 1400°C, or about 1400°C to about 1500°C. In some embodiments, the temperature for sintering is set to a range from about 900°C to about 1500°C, about 1100°C to about 1400°C, about 1100°C to about 1300°C, or about 1200°C to about 1300°C. In an aspect, the cured green body may be sintered at a temperature in a range from about 900°C to about 1500°C for a time in a range from about 10 seconds to about 10 minutes. In an aspect, when held at a temperature in a range from about 950°C to about 1500°C, such as for about 10 seconds to about 10 minutes or other times as described herein, the green tape sinters to form a continuous ceramic ribbon. In some embodiments, the time for sintering may range from about 10 seconds to about 30 seconds, about 30 seconds to about 1 minute, about 1 minute to about 3 minutes, about 3 minutes to about 5 minutes, about 5 minutes to about 7 minutes, or about 7 minutes to about 10 minutes. In some embodiments, the time for sintering may range from about 10 seconds to about 10 minutes, such as about 30 seconds to about 7 minutes, or about 1 minute to about 5 minutes. For sintering, the as-received green tapes may be separated from the carrier film on a flat surface and placed on a leader tape. The leaderAttorney Docket No. SP24- 274 tape, typically made of a high-temperature resistant material such as alumina, guides and supports the green tape through the furnace. It can help ensure the green tape moves smoothly and maintains consistent tension, which may provide for uniform thickness and preventing deformation. In some embodiments, the leader tape may then be pulled at approximately 4 inches per minute through a five-zone binder burnout system and a three-zone furnace. In some embodiments, the sintered ceramic ribbon has a thickness less than about 100 pm, for example less than 50 pm, such as less than about 30 pm. In some embodiments, the thickness of the ceramic ribbon may be in a range from about 5 pm to about 10 pm, from about 10 pm to about 20 pm, from about 20 pm to about 30 pm, from about 30 pm to about 40 pm, from about 40 pm to about 50 pm, from about 50 pm to about 60 pm, from about 60 pm to about 70 pm, from about 70 pm to about 80 pm, from about 80 pm to about 90 pm, from about 90 pm to about 100 pm. In some embodiments, the sintered ceramic ribbon may have a thickness in a range from about 5 pm to about 100 pm, from about 10 pm to about 90 pm, from about 20 pm to about 80 pm.

[0051] In some embodiments, the sintered ceramic ribbon resulting from the firing and sintering process has a fully dense structure. A fully dense structure is characterized by very low or negligible porosity, typically with a porosity of less than 1% or a density that is close to the theoretical density of the material. This is achieved through the complete removal of the radiation-curable binder and the consolidation of the ceramic powder, resulting in a material with minimal or no porosity. In other embodiments, the sintered ceramic ribbon can have a multilayer structure, where at least one layer is fully dense, and at least one layer has a porous structure. A porous structure, on the other hand, contains a network of interconnected or isolated pores or voids. These pores can be created by incorporating pore formers, such as graphite, carbon black, PMMA beads, or combinations thereof, into the green tape composition. During the sintering process, these pore formers are burned out, leaving behind a controlled porous structure. The presence of pores in the material can provide specific functionalities, such as gas permeability, reduced density, or improved thermal insulation. This combination of layers allows for the creation of a material with tailored properties. The ability to create such a multilayer structure with varying densities provides flexibility in designing materials for a wide range of applications, including but not limited to fuel cells, sensors, and electronic components.EXAMPLESAttorney Docket No. SP24- 274

[0052] Examples of UV-curable compositions are provided in Tables 1A and IB. The powder used was a zirconia powder, TZ-3Y-E, supplied by Tosoh Corporation (Japan). This powder is stabilized with 3 mol% yttria and has a reported average particle size of approximately 40 nm. The powder was processed by coating with 1 wt.% oleic acid (a dispersant) in a solution comprising 60 wt.% methyl ethyl ketone and 40 wt.% ethanol. The mixture was then sonicated for 30 minutes to ensure uniform dispersion, followed by drying in a weighing dish in an oven set to 55°C for 48 hours. The oleic acid served as a dispersant to ensure homogeneity of the UV-curable mixture. An alternative method involves dry mixing the powder with a surfactant in a high-shear mixer, thereby eliminating the need for solvents. After the surfactant is mixed with the particles, the resulting mixture was combined with the UV vehicle using a 3 -roll mill. The final mixture was then ready for casting.

[0053] FIG. 2 illustrates viscosity as a function of shear rate for two different solid loadings of formulation 1C: 80 wt.% and 87 wt.%. For the 1C 80 wt.% sample (FIG. 2A), the viscosity can be seen to decrease gradually with increasing shear rate, exhibiting a shearthinning behavior. As the shear rate increases from 101to 103s ', the viscosity drops significantly, indicating the material becomes less viscous under higher shear conditions. The 1C 87 wt.% sample (FIG. 2B), shows a similar shear thinning behavior. It is believed the sudden increase of viscosity was caused by resin overflow between the testing plates. Viscosity influences the processability of the formulation during coating, and a temporary reduction in viscosity under high shear conditions during the coating process facilitates the tape formation.

[0054] In Table IB, solids loading includes the weight percentage of the ceramic powder and dispersant. The dispersant was mixed with the ceramic powder prior to its dispersion in the radiation-curable binder composition. The 2-Ethylhexyl acrylate (2 -EHA) was obtained from BASF, while the other monomers, including M3130, M220, and PPG-lk Oligomer, were obtained from Miwon Specialty Chem. Co. Oleic acid, which acts as a dispersant, can be obtained from Sigma-Aldrich. The photoinitiator TPO-L (2,4,6-Trimethylbenzoyl- diphenyl-phosphine oxide) mya be obtained from IGM Resins.

[0055] Viscosity was measured at room temperature (RT) with a shear rate of 10 s'1using a rotational viscometer. Tensile strength was determined according to ASTM D638. Young's modulus was determined according to ASTM D638. Elongation at break was determined according to ASTM D638.Attorney Docket No. SP24- 274

[0056] Table 1A: Compositions for Various Formulations of Radiation-Curable Binder Systems

[0057] Table IB: Compositions and Properties of Various Formulations of UV Curable green tape composition

[0058] Once the tape is cast using one of the aforementioned coating processes, it was subjected to a belt-fed UV curing system. The UV curing was performed using 365 nm LED lamps from Phoseon Technology.

[0059] For firing and sintering, the as-received green tapes were carefully separated from the carrier film on a flat surface and placed on an alumina leader tape. For example, in the case of the 1C formulation, when continuous firing was employed, the leader tape was pulled at a rate of approximately 4 inches per minute through a five-zone binder burnout system andAttorney Docket No. SP24- 274 a three-zone furnace. The binder burnout temperature settings for the five zones were 300°C, 350°C, 400°C, 450°C, and 500°C, with each section being 30 cm long. The subsequent three- zone furnace was set to 1550°C for all three zones. Typically, the final zone of the furnace is 20-25°C cooler (1525-1530°C) than the set point due to the short thermal gradient at the end of the furnace. The hot zone, which was 40-50 cm long, varied in length depending on the temperature, as higher firing temperatures result in a sharper drop-off. The primary benefits of the UV-curable process are derived from the high green density of the material and the lower volumetric shrinkage observed after firing. In the case of the 1C formulation, the theoretical green density of the UV-curable green tape was calculated to be around 3.82 g / cm3, while the experimental density was measured to be 3.73 g / cm3. This resulted in an estimated porosity of 2.43% for the green tape. This porosity is significantly lower compared to the same TZ-3Y-E green tape prepared by traditional tape casting methods, which typically exhibit porosities of 20% or higher.

[0060] In another set of examples, when lithium lanthanum zirconate (LLZO) was used as the ceramic particles and traditional tape casting methods were employed, the resultant LLZO tapes exhibited variations in their theoretical and experimental green densities. Table 2 compares the solids loading and porosity found in the green tapes for different binder systems and ceramic powder types. Compared to the traditional tape casting method, which typically produced higher green tape porosity, the UV-curable binder-based tape generated a green tape porosity of 2.36%. This shows that the UV binder approach resulted in lower green tape porosity.

[0061] Table 2: Comparison of Green Tape Properties for Different Binder Systems and Ceramic TypesAttorney Docket No. SP24- 274

[0062] A high green density can reduce the amount of shrinkage experienced during firing. Excessive shrinkage increases the risk of the ceramic tape breaking or warping, especially during continuous firing. This is particularly important during the binder burnout phase. A high number of pores will also increase the risk of breakage, as the ceramic microstructure will be too thin to maintain the integrity of the sample.

[0063] Table 3 shows the calculated differences in post-sintered properties for the various tapes. The UV-curable tape exhibited lower volumetric and isometric shrinkage, which helps to minimize the risk of breakage during the binder burnout stage, making it more suitable for continuous "roll-to-roll" firing processes, especially when long tapes are involved.

[0064] Table 3: Calculated Volumetric and Isometric Shrinkage During Sintering for Different Binder Systems and Zirconia.

[0065] FIG. 5 shows the cross-sectional view of a ceramic tape, produced from a UV- curable green tape, after the firing process, as observed under scanning electron microscopy (SEM). The SEM image reveals the ceramic tape maintained its flatness even after firing, indicating excellent dimensional stability throughout the sintering process. Furthermore, the microstructure shown in the SEM image demonstrates a highly densified ceramic tape, with minimal visible porosity. The uniformity and compact nature of the microstructure suggest the UV-cured tape has undergone complete consolidation during sintering, resulting in a dense and homogeneous ceramic component.

[0066] As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. Ranges can be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, embodiments include from the one particular value and / or to the other particular value. Similarly, when values are expressed asAttorney Docket No. SP24- 274 approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. Whether or not a numerical value or endpoint of a range in the specification recites “about,” the numerical value or endpoint of a range is intended to include two embodiments: one modified by “about,” and one not modified by “about.” It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint and independently of the other endpoint.

[0067] The terms “substantial,” substantially,” and variations thereof as used herein, unless otherwise noted, are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, as defined above, “substantially similar” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially similar” may denote values within about 5% of each other, for example, within about 2% of each other, or within about 1% of each other.

[0068] It will be appreciated that the various disclosed embodiments may involve features, elements, or steps that are described in connection with that embodiment. It will also be appreciated that a feature, element, or step, although described in relation to one embodiment, may be interchanged or combined with alternate embodiments in various non-illustrated combinations or permutations.

[0069] It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the spirit and scope of the disclosure. Thus, it is intended that the present disclosure cover the modifications and variations of the embodiments herein provided they come within the scope of the appended claims and their equivalents.

Claims

Attorney Docket No. SP24- 274What is claimed is:

1. A green tape composition for forming a green tape, comprising: a ceramic powder in an amount greater than about 40 vol. %; a radiation-curable binder composition comprising a photoinitiator, a monomer, and a dispersant.

2. The green tape composition of claim 1, wherein the ceramic powder comprises at least one of zirconia, yttria-stabilized tetragonal zirconia polycrystals, alumina, or lithium-garnet.

3. The green tape composition of claim 1, wherein the monomer comprises at least one of a monofunctional acrylate, a difunctional acrylate, a trifunctional acrylate, methacrylate monomers, or epoxide monomers.

4. The green tape composition of claim 3, wherein the monomer comprises at least one of 2- ethylhexyl acrylate, 2-hydroxyethyl acrylate, tripropylene glycol diacrylate, or trifunctional ethoxylated acrylate.

5. The green tape composition of claim 1, wherein the amount of ceramic powder is greater than about 45 vol. %,6. The green tape composition of claim 1, wherein the amount of ceramic powder is greater than about 50 vol. %.

7. The green tape composition of claim 1, wherein the ceramic powder comprises doped LiyLasZnOn variants.

8. The green tape composition of claim 1, wherein the dispersant comprises at least one of fatty acids, fish oils, poly (ethylene imine), or phosphate esters.

9. The green tape composition of claim 1, wherein the dispersant is present in the radiation- curable binder composition in an amount from 0 wt. % to about 2.0 wt. %.Attorney Docket No. SP24- 27410. The green tape composition of claim 1, wherein the photoinitiator is present in the radiation-curable binder composition in an amount from about 0.1 wt. % to about 1.0 wt. %.

11. The green tape composition of claim 1, wherein the photoinitiator comprises ethyl (2,4,6- trimethylbenzoyl) phenylphosphinate.

12. The green tape composition of claim 1, wherein the green tape composition further comprises an acrylate oligomer comprising at least one of epoxy acrylates, urethane acrylates, polyester acrylates, or polyether acrylates.

13. The green tape composition of claim 1, wherein the green tape composition further comprises an additive comprising a plasticizer, an antioxidants, a UV stabilizer, or a toughening agent.

14. The green tape composition of claim 1, wherein the green tape composition is solvent- free.

15. The green tape composition of claim 1, wherein the ceramic powder comprises lithium garnet and the dispersant is an oleic acid.

16. The green tape composition of claim 1, wherein a shear viscosity of the green tape composition is less than about 10000 poise at a shear rate of about 100 / s when measured by a parallel plate rheometer at room temperature.

17. The green tape composition of claim 1, wherein a shear viscosity of the green tape composition is less than about 5000 poise at a shear rate of about 100 / s when measured by a parallel plate rheometer at room temperature.

18. The green tape composition of claim 1, wherein a shear viscosity of the green tape composition is less than about 3000 poise at a shear rate of about 100 / s when measured by a parallel plate rheometer at room temperature.

19. A method of making a ceramic ribbon, comprising:Attorney Docket No. SP24- 274 forming a green tape by continuously depositing a green tape composition onto a carrier, the green tape composition comprising a ceramic powder and a radiation-curable binder composition comprising a photoinitiator, a monomer, and a dispersant; curing the green tape with UV radiation to cause the radiation-curable binder composition to polymerize and bond together with the ceramic powder and form a cured green tape; and heating the cured green tape to remove the radiation-curable binder composition and form the ceramic ribbon.

20. The method of making a ceramic ribbon of claim 19, wherein the heating the cured green tape comprises a temperature in a range from about 900°C to about 1500°C for a time in a range from about 10 seconds to about 10 minutes.

21. The method of making a ceramic ribbon of claim 19, wherein a thickness of the green tape is less than about 200 pm,22. The method of making a ceramic ribbon of claim 19, wherein a thickness of the green tape is less than about 100 pm,23. The method of making a ceramic ribbon of claim 19, wherein a thickness of the green tape is less than about 50 pm.

24. The method of making a ceramic ribbon of claim 19, wherein a thickness of the ceramic ribbon less than about 100 pm,25. The method of making a ceramic ribbon of claim 19, wherein a thickness of the ceramic ribbon less is less than about 50 pm,26. The method of making a ceramic ribbon of claim 19, wherein a thickness of the ceramic ribbon less is less than about 30 pm.

27. The method of making a ceramic ribbon of claim 19, wherein a porosity of the ceramic ribbon is less than about 1%.Attorney Docket No. SP24- 27428. The method of making a ceramic ribbon of claim 19, wherein the green tape further comprises multiple layers of the green tape composition.

29. The method of making a ceramic ribbon of claim 27, wherein at least one layer of the multiple layers comprises a pore former comprising graphite, carbon black, or PMMA beads.

30. The method of making a ceramic ribbon of claim 19, wherein the ceramic ribbon further comprises a multilayer structure, and a porosity of at least one layer of the multilayer structure is equal to or less than about 1% and at least one layer of the multilayer structure comprises a porosity greater than 1%.

Images