Sintering assisted additive manufacturing

Abstract

The present disclosure provides a device manufacturing process comprising designing a mold for stereolithography resin printing, wherein the mold is configured to minimize distortion from pyrolysis and sintering, printing the mold from resin using stereolithography, pyrolyzing the mold to convert resin into carbon structure, filling the carbon structure with ceramic slurry, drying the ceramic slurry within the carbon structure, and thermally processing the carbon structure and ceramic slurry to decompose the carbon structure and sinter the ceramic slurry into consolidated ceramic part. The ceramic slurry may comprise hydroxyapatite or yttria-stabilized zirconia particles. The mold design may limit beam thickness and wall thickness to 0.6mm and account for isotropic shrinkage of approximately 50% during pyrolysis. Thermal processing may involve sintering at 1200°C for hydroxyapatite or 1450°C for yttria-stabilized zirconia to produce ceramic scaffolds with sub-millimetric channels and intricate lattice structures for biomedical applications.

Description

SINTERING ASSISTED ADDITIVE MANUFACTURINGCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Application No. 63 / 713,517, titled "Sintering Assisted Additive Manufacturing", filed October 29, 2024, which is hereby incorporated by reference in its entirety.STATEMENT OF FEDERAL SUPPORT

[0002] This invention was made with government support under the Designing Materials to Revolutionize and Engineer our Future Grant 2138421 awarded by the National Science Foundation. The government has certain rights in the invention.FIELD OF INVENTION

[0003] The present disclosure relates to additive manufacturing processes for producing ceramic parts, and more particularly to sintering assisted additive manufacturing methods that combine stereolithography printing, pyrolysis, and ceramic sintering to create parts with intricate shapes and internal lattice structures.BACKGROUND

[0004] Bone defects resulting from traumatic injuries, congenital anomalies, or surgical resection during cancer treatment can profoundly impact an individual's quality of life, leading to pain, impaired mobility, and difficulties in performing everyday activities. Hydroxyapatite composites have emerged as effective scaffolding materials in tissue-engineered bone applications due to their biocompatibility and ability to promote bone regeneration by supporting the attachment and growth of osteoblasts. Recent advancements in manufacturing techniques and material sciences have enabled the creation of scaffolds that more closely imitatethe composition and mechanical properties of natural bone, incorporating features such as controlled porosity for better nutrient and oxygen flow and tailored surface textures that promote cell adhesion.

[0005] Traditional manufacturing methods for creating ceramic scaffolds with intricate internal structures face limitations in achieving the precise geometries and fine features desired for biomedical applications. The production of parts with complex internal lattice structures and sub-millimetric channels presents challenges in terms of manufacturing precision, structural integrity, and the ability to control porosity and surface characteristics. Additionally, conventional approaches may struggle to produce scaffolds that can effectively balance mechanical strength with the biological requirements for tissue integration and regeneration.SUMMARY

[0006] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0007] The presently disclosed subject matter is directed to a device manufacturing process. Particularly, the process comprises designing a mold for stereolithography resin printing. The process includes printing the mold from a resin. The process includes pyrolyzing the mold into a carbon structure. The process includes fil ling the mold with a ceramic slurry. The process includes drying the mold. The process includes thermal processing the mold.

[0008] In some embodiments, the ceramic slurry is hydroxyapatite.

[0009] In some embodiments, the ceramic slurry is yttria-stabilized zirconia.

[0010] In some embodiments, thermal processing the mold further comprises decomposing the mold in a set environment at a set temperature profile.

[0011] In some embodiments, the set environment is an air-exposed environment.

[0012] In some embodiments, the set temperature profile is configured for a set density.

[0013] The presently disclosed subject matter is directed to a mold production process. Particularly, the process comprises designing a mold configured to reduce distortion during pyrolysis and sintering. The process includes producing the mold wherein the mold is produced by stereolithography of a resin. The process includes pyrolyzing the mold wherein the resin undergoes pyrolysis, converting the mold into a carbon structure.

[0014] The presently disclosed subject matter is directed to a device. Particularly, the device comprises an intricate scaffold structure wherein the scaffold structure is comprised of a ceramic material, and wherein the ceramic material is shaped into the scaffold structure by filling a mold with a ceramic slurry and heating the mold and slurry which a set temperature profile configured to set the ceramic slurry, remove the mold and sinter the ceramic slurry.

[0015] In some embodiments, the mold is 3d printed.

[0016] In some embodiments, the mold comprises a resin material.

[0017] In some embodiments, the mold comprises a material that was pyrolyzed.

[0018] Additional embodiments and features are set forth in part in the description that follows, and in part will become apparent to those skilled in the art upon examination of the specification or may be learned by the practice of the disclosure. A further understanding of the nature and advantages of the present disclosure may be realized by reference to the remaining portions of the specification and the drawings, which forms a part of this disclosure.BRIEF DESCRIPTION OF FIGURES

[0019] The description will be more fully understood with reference to the following figures, which are presented as embodiments of the invention and should not be construed as a complete recitation of the scope of the invention wherein:

[0020] Figure 1A illustrates a flowchart depicting the device manufacturing process steps, according to aspects of the present disclosure.

[0021] Figure IB shows a sequence of scaffold production stages from resin to sintered ceramic structure, according to an embodiment.

[0022] Figure 2 depicts a graphite die assembly for sintering assisted additive manufacturing, according to aspects of the present disclosure.

[0023] Figure 3 illustrates an exemplary CAD scaffold with cubic lattice structure, according to an embodiment.

[0024] Figure 4A shows an exemplary resin scaffold in a processing tray, according to aspects of the present disclosure.

[0025] Figure 4B depicts exemplary ceramic scaffolds after thermal processing, according to an embodiment.

[0026] Figure 5 illustrates a schematic representation of the thermal treatment process for part densification, according to aspects of the present disclosure.DETAILED DESCRIPTION

[0027] The following description sets forth exemplary aspects of the present disclosure. It should be recognized, however, that such description is not intended as a limitation on the scope of the present disclosure. Rather, the description also encompasses combinations and modifications to those exemplary aspects described herein.

[0028] It will be understood that the components of the embodiments, as generally described herein and illustrated in the appended figures, may be arranged and designed in a variety of different configurations. Thus, the following more detailed description of various embodiments, as represented in the figures, is not intended to limit the scope of the present disclosure but is merely representative of various embodiments. While various aspects of theembodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0029] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive.

[0030] Reference throughout this specification to features, advantages, or similar language does not imply that all of the features and advantages that may be realized with the present invention should be or are in any single embodiment of the invention. Rather, language referring to the features and advantages is understood to mean that a specific feature, advantage, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, discussions of the features and advantages and similar language throughout this specification may, but do not necessarily, refer to the same embodiment.

[0031] Furthermore, the described features, advantages, and characteristics of the invention may be combined in any suitable manner in one or more embodiments. One skilled in the relevant art will recognize, in light of the description herein, that the invention can be practiced without one or more of the specific features or advantages of a particular embodiment. In other instances, additional features and advantages may be recognized in certain embodiments that may not be present in all embodiments of the invention.

[0032] Reference throughout this specification to "one embodiment," "an embodiment," or similar language means that a particular feature, structure, or characteristic described in connection with the indicated embodiment is included in at least one embodiment. Thus, the phrases "in one embodiment," "in an embodiment," and similar language throughout this specification may but do not necessarily, all refer to the same embodiment.

[0033] Systems and methods described herein relate to the production of parts with intricate shapes and internal lattice structures via sintering assisted additive manufacturing. Thedisclosed approach may integrate multiple manufacturing techniques to create ceramic devices that exhibit enhanced properties for various applications, including biomedical uses.

[0034] The manufacturing process may combine pyrolysis, three-dimensional printing technology, and sintering to produce ceramic components with complex geometries. Pyrolysis may involve the thermochemical decomposition of organic materials in an oxygen-limited environment, typically at temperatures ranging from 400°C to 800°C. During pyrolysis, organic material such as polymerized resin parts may break down into smaller molecules, resulting in the formation of a solid carbonaceous structure while releasing liquid and gaseous compounds.

[0035] Sintering may be employed as a manufacturing process for densifying materials, including metals, ceramics, or plastics, through thermal treatment, pressure treatment, or both. The sintering process may transform initially porous materials into denser structures with improved mechanical properties. The combination of pyrolysis and sintering with three- dimensional printing technology may enable the creation of parts with ultra-fine internal lattice structures and intricate external geometries.

[0036] The integration of these manufacturing techniques may produce ceramic devices with enhanced biocompatibility, mechanical strength, and structural integrity. Such devices may closely mimic natural properties of materials like bone, making them suitable for tissue engineering applications. The process may allow for the creation of scaffolds with controlled porosity, tailored surface textures, and specific degradation rates that align with biological requirements.

[0037] The disclosed manufacturing approach may address limitations associated with conventional manufacturing methods for producing complex ceramic structures. Traditional methods may face challenges in creating parts with fine internal features, controlled porosity, and precise geometric specifications. The sintering assisted additive manufacturing process may overcome these limitations by providing greater design flexibility and manufacturing precision for ceramic components with intricate architectures.

[0038] Referring to Figure 1A, the manufacturing process may follow a systematic approach for producing ceramic parts with complex internal structures. The process may begin at step 110, where a mold may be designed for stereolithography resin printing. The mold design at step 110 may be configured to minimize distortion that can occur during subsequent pyrolysis and sintering operations. The design parameters at step 110 may account for predictable dimensional changes that occur during thermal processing stages.

[0039] At step 120, the mold may be printed from a resin using stereolithography techniques. The printing process at step 120 may utilize photopolymerization to create the three- dimensional mold structure with the designed geometric features. The resin material selected for step 120 may be chosen based on the material's ability to undergo controlled pyrolysis in subsequent processing stages.

[0040] The process may continue to step 130, where the printed mold may undergo pyrolysis to convert the resin structure into a carbon structure. During step 130, the mold may be subjected to elevated temperatures in an oxygen-limited environment, causing the organic resin material to decompose and form a carbonaceous framework. The pyrolysis process at step 130 may result in predictable shrinkage of the mold structure, which may be accounted for in the initial design parameters established at step 110.

[0041] Following pyrolysis, the process may proceed to step 140, where the carbon mold structure may be filled with a ceramic slurry. The ceramic slurry introduced at step 140 may contain ceramic particles suspended in a liquid medium, allowing the slurry to flow into and fill the internal cavities and channels of the pyrolyzed mold. The composition and viscosity of the ceramic slurry at step 140 may be selected to achieve optimal filling of the mold structure without damaging the carbon framework.

[0042] The process may then advance to step 150, where the filled mold may be dried to remove the liquid medium from the ceramic slurry. The drying process at step 150 may be controlled to prevent crack formation that could result from rapid solvent evaporation. Thedrying conditions at step 150 may include controlled temperature and humidity parameters to ensure uniform moisture removal from the ceramic material.

[0043] The manufacturing process may conclude with step 160, where the mold and ceramic material may undergo thermal processing. The thermal processing at step 160 may involve heating the assembly to decompose the carbon mold structure and simultaneously sinter the ceramic particles. A temperature profile may be selected for step 160 that may be configured to achieve a desired final density in the ceramic part. The temperature profile at step 160 may include controlled heating rates and hold times that promote proper sintering while allowing for the complete removal of the carbon mold material through oxidation.

[0044] The design of the mold structure may incorporate specific criteria to address challenges associated with thermal processing stages. Thick geometries, such as rods and walls, may result in bloating of the specimen during pyrolysis, leading to distortions and non-usable pyrolyzed geometries. To mitigate shape distortions, strict design criteria may be employed in the mold design process.

[0045] The beam thickness and wall thickness of the designed part may be limited to 0.6mm. This thickness limitation may prevent excessive bloating and dimensional instability during the pyrolysis process. The 0.6mm thickness constraint may apply to all structural elements of the mold, including support beams, walls, and connecting features. The thickness limitation may ensure that the mold structure maintains dimensional stability throughout the thermal decomposition process.

[0046] The design may be configured for isotropic shrinkage during pyrolysis. The mold design may account for predictable dimensional changes that occur uniformly in all directions during the thermal processing. The design may be configured for approximately 50% shrinkage during the pyrolysis process. This 50% shrinkage may occur uniformly across all dimensions of the mold structure, allowing for predictable scaling of the final part dimensions.

[0047] Referring to Figure 3, an exemplary CAD scaffold design may demonstrate the application of these design principles. The exemplary scaffold may comprise a 30x30x30 cube structure with an internal lattice framework. The scaffold design may feature a 0.6 diameter beam lattice structure with individual beams spaced from each other by 5mm intervals. The lattice structure may form a regular geometric pattern throughout the cubic volume, creating a three-dimensional network of interconnected beams.

[0048] The mold shape for the exemplary design may comprise a 30mm diameter cylinder with 0.6mm wall thickness. The cylindrical mold structure may provide the external boundary for the ceramic slurry filling process. The bottom of the cylindrical mold may be closed with a 0.2mm wall thickness, creating a contained volume for the ceramic material. The thin bottom wall may allow for controlled thermal processing while maintaining structural integrity during the filling and drying stages.

[0049] The exemplary design shown in Figure 3 may demonstrate the capability to create precise, repeating geometric patterns with controlled internal architectures. The uniform spacing and consistent beam dimensions may enable predictable flow characteristics for the ceramic slurry during the filling process. The lattice structure may provide a framework for creating controlled porosity and interconnected channels in the final ceramic part.

[0050] Referring to Figure IB, a resin scaffold 1 may be produced through stereolithography printing techniques. The resin scaffold 1 may serve as the initial structure in the manufacturing process, providing the geometric foundation for subsequent processing stages. The resin scaffold 1 may be composed of a high-temperature resin formulation that may be specifically selected for thermal processing applications.

[0051] The high-temperature resin composition for the resin scaffold 1 may contain 15 to 25% of 2,4,6-trioxo-l,3,5-triazine-l,3,5(2H,4H,6H)-triyl)tri-2,l-ethanediyl triacrylate). This triazine-based component may provide thermal stability and structural integrity to the resin scaffold 1 during elevated temperature processing. The resin composition may further include40 to 60% of acrylate monomer, which may contribute to the photopolymerization characteristics and mechanical properties of the resin scaffold 1. The formulation may also contain 25 to 45% urethane dimethacrylate, which may enhance the crosslinking density and thermal resistance of the polymerized structure.

[0052] The resin scaffold 1 may be printed using a commercial stereolithography printer operating with a wavelength of 405 nm. The 405 nm wavelength may provide optimal photopolymerization of the high-temperature resin composition, enabling precise layer-by-layer construction of the scaffold structure. The stereolithography printing process may utilize controlled light exposure to selectively cure the resin material according to the designed geometric specifications.

[0053] As shown in Figure IB, the resin scaffold 1 may exhibit the designed lattice structure with interconnected beams and controlled internal architecture. The printed structure may maintain dimensional accuracy and surface quality suitable for subsequent pyrolysis processing. The resin scaffold 1 may demonstrate the capability of stereolithography printing to produce complex three-dimensional geometries with fine feature resolution.

[0054] Referring to Figure 4, exemplary printed scaffolds may illustrate the application of the stereolithography printing process. Figure 4A may show the resin scaffold 1 after printing, displaying the lattice structure with interconnected elements arranged in a regular pattern. The printed structure may exhibit uniform beam dimensions and consistent spacing throughout the scaffold architecture. The resin scaffold 1 shown in Figure 4A may demonstrate the precision achievable through 405 nm stereolithography printing of the high-temperature resin composition.

[0055] The stereolithography printing process may enable the production of scaffolds with controlled porosity and interconnected channel networks. The 405 nm wavelength printing may provide sufficient resolution to create fine structural features while maintaining the structural integrity of thin-walled elements. The printed resin scaffold 1 may serve as a template for thesubsequent pyrolysis and ceramic filling processes, with the resin composition selected to undergo controlled thermal decomposition during later processing stages.

[0056] With continued reference to Figure IB, the resin scaffold 1 may undergo pyrolysis to form a pyrolyzed structure 2. The pyrolysis process may convert the resin scaffold 1 into a carbonaceous framework through controlled thermal decomposition. The transformation from the resin scaffold 1 to the pyrolyzed structure 2 may occur through a systematic heating process that decomposes the organic polymer chains while preserving the overall geometric structure.

[0057] The pyrolysis process may involve placing the resin polymeric part in a furnace for a slow decomposition cycle. The furnace may be operated at temperatures ranging from 400°C to 800°Cto achieve controlled thermal decomposition of the resin material. The temperature range may be selected to promote complete pyrolysis of the organic components while maintaining structural integrity of the resulting carbon framework. The slow decomposition cycle may prevent rapid thermal expansion or contraction that could lead to structural distortion or cracking of the pyrolyzed structure 2.

[0058] During the pyrolysis process, the organic resin material may break down into smaller molecular components, with volatile compounds being released as gases and liquids. The remaining solid material may form the pyrolyzed structure 2, which may comprise a carbonaceous framework that retains the geometric features of the original resin scaffold 1. The pyrolysis process may occur in an oxygen-limited environment to prevent complete combustion of the organic material and to promote the formation of the stable carbon structure.

[0059] The pyrolyzed structure 2 may undergo isotropic shrinkage of approximately 50% during the pyrolysis process. This shrinkage may occur uniformly in all three dimensions, maintaining the proportional relationships between structural features while reducing the overall size of the structure. The 50% isotropic shrinkage may be predictable and consistent, allowing for accurate scaling of the initial design dimensions to account for the dimensional changes that occur during thermal processing.

[0060] As shown in Figure IB, the transformation from the resin scaffold 1 to the pyrolyzed structure 2 may demonstrate the controlled nature of the pyrolysis process. The pyrolyzed structure 2 may maintain the lattice architecture and interconnected beam network of the original resin scaffold 1, but with reduced dimensions corresponding to the 50% shrinkage factor. The carbonaceous material of the pyrolyzed structure 2 may provide a stable framework for subsequent ceramic filling operations.

[0061] An exemplary demonstration of the shrinkage characteristics may involve a 30x30x30 cube structure that shrinks to a 15mm edge cube during pyrolysis. This example may illustrate the 50% linear shrinkage that occurs uniformly across all dimensions of the structure. The beams that constitute the internal channels of the scaffold may correspondingly shrink from their original 0.6mm diameter to 0.3mm diameter in the pyrolyzed structure 2. This dimensional scaling may maintain the structural proportions while creating a smaller framework suitable for ceramic infiltration.

[0062] Referring to Figure 4, the progression from the initial printed structure to the pyrolyzed structure 2 may be observed through the transformation of the scaffold geometry. Figure 4B may show the results after the printed scaffolding shape has been subjected to the pyrolysis cycle, producing the carbonaceous final structure. The pyrolyzed structure 2 shown in Figure 4B may exhibit the characteristic dimensional reduction while maintaining the interconnected lattice architecture of the original design.

[0063] The pyrolyzed structure 2 may serve as a template for the subsequent ceramic filling process, with the carbon framework providing structural support during slurry infiltration and drying operations. The carbonaceous material may be compatible with ceramic slurries and may not interfere with the sintering process of the ceramic particles. The pyrolyzed structure 2 may ultimately be removed during the final thermal processing stage through oxidation, leaving behind the sintered ceramic part with the desired internal architecture.

[0064] With continued reference to Figure IB, a ceramic slurry 3 may be prepared for filling the pyrolyzed structure 2. The ceramic slurry 3 may comprise ceramic particles suspended in a liquid medium, allowing the slurry to flow into and infiltrate the internal cavities and channels of the pyrolyzed structure 2. The ceramic slurry 3 may be formulated to achieve optimal filling characteristics while maintaining compatibility with the carbonaceous framework of the pyrolyzed structure 2.

[0065] The ceramic slurry 3 may comprise nanometric hydroxyapatite particles with a theoretical density of 3.1 g / cm3. Nanometric hydroxyapatite may provide biocompatibility characteristics suitable for biomedical applications, particularly in bone tissue engineering. The nanometric particle size of the hydroxyapatite may enable enhanced packing density within the ceramic slurry 3 and may facilitate infiltration into fine features of the pyrolyzed structure 2. The 3.1 g / cm3theoretical density of the hydroxyapatite may contribute to the overall density characteristics of the final sintered ceramic part.

[0066] Alternatively, the ceramic slurry 3 may comprise nanometric yttria-stabilized zirconia particles with a density of 6.05 g / cm3. Nanometric yttria-stabilized zirconia may provide enhanced mechanical properties and structural integrity for applications requiring higher strength characteristics. The 6.05 g / cm3density of the yttria-stabilized zirconia may be higher than that of hydroxyapatite, potentially resulting in denser final ceramic parts. The nanometric particle size of the yttria-stabilized zirconia may enable effective infiltration into the fine channels and pores of the pyrolyzed structure 2.

[0067] The ceramic slurry 3 may be configured for the highest compaction density possible without damaging the pyrolyzed structure 2. The slurry formulation may balance particle loading, viscosity, and flow characteristics to maximize the ceramic content while preventing structural damage to the carbonaceous framework. The compaction density optimization may involve adjusting the solid-to-liquid ratio in the ceramic slurry 3 to achieve maximum particle packing without generating excessive pressure that could deform or fracture the pyrolyzed structure 2.

[0068] The ceramic powder may be incorporated into the pyrolyzed structure 2 through controlled infiltration of the ceramic slurry 3. The infiltration process may involve introducing the ceramic slurry 3 into the channels and pores of the pyrolyzed structure 2, allowing the liquid medium to carry the ceramic particles throughout the internal architecture. The viscosity and flow properties of the ceramic slurry 3 may be adjusted to ensure complete filling of the available volume within the pyrolyzed structure 2 while avoiding air entrapment or incomplete infiltration.

[0069] As shown in Figure IB, the ceramic slurry 3 may fill the internal spaces of the pyrolyzed structure 2, creating a composite structure comprising the carbonaceous framework and the ceramic particles. The filling process may result in uniform distribution of the ceramic material throughout the internal lattice structure, with the ceramic slurry 3 occupying the void spaces between the carbon beams and within the interconnected channel network. The filled structure may then be ready for subsequent drying and thermal processing operations that will remove the liquid medium and consolidate the ceramic particles into a dense structure.

[0070] Referring to Figure 5, the drying process may be conducted to avoid crack induction that can result from fast solvent evaporation. The ceramic slurry 3 within the pyrolyzed structure 2 may undergo controlled drying to remove the liquid medium without generating internal stresses that could lead to crack formation. The drying process may involve gradual moisture removal under controlled temperature and humidity conditions to ensure uniform evaporation of the liquid components from the ceramic slurry 3.

[0071] The drying conditions may be selected to prevent abrupt heating that could cause rapid solvent evaporation and subsequent crack formation in the ceramic material. The controlled drying process may maintain the structural integrity of both the pyrolyzed structure 2 and the ceramic particles during moisture removal. The drying stage may result in a "green" ceramic part that retains the shape and internal architecture of the original structure while containing consolidated ceramic particles within the carbonaceous framework.

[0072] As shown in Figure 5, the thermal processing sequence may begin with powder material that undergoes die filling to create the initial structure. The die filling stage may represent the infiltration of the ceramic slurry 3 into the pyrolyzed structure 2, where the ceramic particles become distributed throughout the internal channels and cavities. The filled structure may then proceed through subsequent thermal processing stages that transform the composite material into the final densified ceramic part.

[0073] Following the drying process, the compound may be placed in a furnace for controlled thermal processing. The furnace may heat the structure slowly to ensure uniform temperature distribution and controlled decomposition of the carbonaceous framework. The slow heating process may prevent thermal shock and dimensional distortion that could occur with rapid temperature changes.

[0074] The thermal processing may involve heating the structure at a rate of l°C / min during the temperature ramping phase. This controlled heating rate of l°C / min may provide sufficient time forthermal equilibration throughoutthe structure and may allow forgradual decomposition of the pyrolyzed structure 2 without generating excessive thermal stresses. The l°C / min heating rate may be maintained throughout the temperature range leading to carbon decomposition, ensuring consistent thermal processing conditions.

[0075] The structure may be heated to the carbon decomposition temperature in air during the thermal processing stage. The air environment may provide the oxygen necessary for oxidation of the carbonaceous framework of the pyrolyzed structure 2. The carbon decomposition temperature may be selected based on the specific carbon structure and the desired decomposition kinetics for complete removal of the carbonaceous material.

[0076] The heating to carbon decomposition temperature in air may result in the formation of gaseous CO2as the primary decomposition product. The carbonaceous material of the pyrolyzed structure 2 may undergo oxidation in the air environment, converting the solid carbon framework into gaseous carbon dioxide that may be removed from the furnace atmosphere. Theformation of gaseous CO2may allow for complete elimination of the carbonaceous template material, leaving behind the ceramic particles in their original spatial arrangement.

[0077] With continued reference to Figure 5, the pyrolyzed shape decomposition stage may illustrate the removal of the carbonaceous framework through oxidation. During this stage, the pyrolyzed structure 2 may be consumed through the formation of gaseous CO2, while the ceramic particles may retain their positions within the structure. The decomposition process may occur gradually as the temperature increases, allowing for controlled removal of the carbon material without disrupting the arrangement of the ceramic particles.

[0078] The "green" ceramic part may retain its shape during the carbon decomposition process, with the ceramic particles maintaining their spatial distribution even after removal of the carbonaceous framework. The structural integrity of the ceramic arrangement may be preserved through particle-to-particle contact and the gradual nature of the carbon removal process. The retention of shape during decomposition may ensure that the final ceramic part maintains the desired internal lattice structure and external geometry.

[0079] Following the carbon decomposition stage, the "green" ceramic part may undergo sintering to achieve densification and consolidation of the ceramic particles. The sintering process may involve continued heating or temperature adjustment to promote particle bonding and densification of the ceramic material. The same furnace may be used for both the slow heating and carbon decomposition stages as well as the subsequent sintering process, providing continuity in the thermal processing sequence.

[0080] As further shown in Figure 5, the sintering stage may represent the final densification step where the ceramic particles undergo consolidation to form a coherent, dense ceramic structure. The sintering process may involve diffusion mechanisms that promote particle bonding and elimination of porosity between the ceramic particles. The sintering conditions may be selected based on the specific ceramic material composition and the desired final density characteristics of the ceramic part.

[0081] The thermal processing sequence illustrated in Figure 5 may demonstrate the progressive transformation from the initial powder-filled structure through carbon decomposition to the final sintered ceramic part. The controlled thermal processing may enable the production of ceramic parts with complex internal architectures that would be difficult to achieve through conventional ceramic forming methods. The process may result in ceramic components with controlled porosity, interconnected channel networks, and precise geometric features derived from the original pyrolyzed structure 2 template.

[0082] Referring to Figure 2, a graphite die assembly may be employed for the thermal processing stages of the sintering assisted additive manufacturing process. The graphite die assembly may provide a controlled environment for the densification and sintering of ceramic materials while enabling precise temperature monitoring and uniform heat distribution throughout the processing volume.

[0083] The graphite die assembly may comprise a graphite die structure that forms the primary containment vessel for the thermal processing operations. The graphite die may be constructed from high-purity graphite material that exhibits thermal stability and chemical inertness at elevated processing temperatures. The graphite construction may provide uniform thermal conductivity and may resist thermal shock during heating and cooling cycles. The graphite die may be configured with internal dimensions suitable for accommodating the ceramic parts undergoing thermal processing.

[0084] The graphite die assembly may include pressureless punches positioned at the top and bottom of the die structure. The pressureless punches may provide containment for the processing atmosphere while allowing for thermal expansion and contraction of the materials during temperature cycling. The top and bottom positioning of the pressureless punches may create a sealed processing environment that may control the atmospheric conditions surrounding the ceramic parts during thermal treatment. The pressureless configuration mayavoid applying mechanical stress to the ceramic materials during the sintering process, allowing for natural densification through thermal mechanisms.

[0085] An aperture for a pyrometer may be located on one side of the graphite die assembly to enable temperature monitoring during the thermal processing operations. The pyrometer aperture may provide optical access to the interior of the die assembly, allowing for non-contact temperature measurement of the processing environment. The pyrometer may monitor the temperature conditions within the die assembly throughout the heating, decomposition, and sintering stages of the manufacturing process. The temperature monitoring capability may enable precise control of the thermal processing parameters and may ensure consistent processing conditions for reproducible ceramic part production.

[0086] The interior surfaces of the graphite die assembly may feature a boron nitride coating that provides chemical protection and thermal barrier properties. The boron nitride coating may prevent chemical reactions between the graphite die material and the ceramic components during high-temperature processing. The coating may also provide thermal insulation properties that may contribute to uniform temperature distribution within the processing volume. The boron nitride coating may exhibit chemical inertness and thermal stability at the processing temperatures employed for ceramic sintering operations.

[0087] The central cavity of the graphite die assembly may contain a densifying sample that represents the ceramic part undergoing thermal processing. The densifying sample may be positioned within the controlled atmosphere of the die assembly where the sample may undergo the carbon decomposition and sintering stages of the manufacturing process. The central cavity may provide sufficient volume for thermal expansion of the ceramic material during processing while maintaining containment of the processing atmosphere.

[0088] A pyrolitic interface may be positioned between the densifying sample and the die wall within the graphite die assembly. The pyrolitic interface may provide thermal coupling between the sample and the die structure while preventing direct contact that could lead tocontamination or chemical interaction. The pyrolitic interface may facilitate uniform heat transfer from the die walls to the ceramic sample, promoting consistent temperature distribution throughout the sample volume during thermal processing.

[0089] The graphite die assembly may be designed to facilitate the sintering process while allowing temperature monitoring through the pyrometer aperture. The assembly configuration may enable controlled heating and cooling cycles that promote proper densification of the ceramic materials. The die assembly may accommodate the thermal processing requirements for different ceramic compositions, including hydroxyapatite and yttria-stabilized zirconia materials, by providing adjustable processing parameters and atmospheric control.

[0090] The graphite die assembly may demonstrate the configuration used for thermal processing and densification of ceramic materials during the manufacturing process. The assembly may provide the controlled environment necessary for achieving the desired density and mechanical properties in the final ceramic parts. The die assembly design may enable reproducible processing conditions that result in consistent ceramic part quality and dimensional accuracy.

[0091] With continued reference to Figure IB, a sintered scaffold 4 may be produced through controlled sintering of the ceramic material following the carbon decomposition stage. The sintered scaffold 4 may represent the final ceramic structure that exhibits the desired mechanical properties, density characteristics, and geometric features for the intended application. The sintering process may consolidate the ceramic particles into a coherent structure while maintaining the internal lattice architecture derived from the original pyrolyzed structure 2.

[0092] The sintering conditions for producing the sintered scaffold 4 may vary depending on the ceramic material composition employed in the ceramic slurry 3. For hydroxyapatite-based ceramic materials, the sintered scaffold 4 may be produced through sintering at 1200°C for 6 hours. The 1200°C sintering temperature may provide sufficient thermal energy to promoteparticle bonding and densification of the hydroxyapatite material without causing excessive grain growth or structural distortion. The 6-hour sintering duration at 1200°C may allow for complete densification kinetics and may result in uniform consolidation throughout the ceramic structure.

[0093] The hydroxyapatite sintering process at 1200°C for 6 hours may produce a sintered scaffold 4 with approximately 70% relative density. The 70% relative density may provide a balance between mechanical strength and porosity that may be suitable for biomedical applications such as bone tissue engineering. The controlled porosity resulting from the 70% relative density may facilitate biological processes including cell infiltration, nutrient transport, and tissue integration while maintaining structural integrity of the sintered scaffold 4.

[0094] For yttria-stabilized zirconia-based ceramic materials, the sintered scaffold 4 may be produced through sintering at 1450°C for 2 hours. The 1450°C sintering temperature may be selected to achieve optimal densification of the yttria-stabilized zirconia particles while minimizing processing time and energy consumption. The higher sintering temperature of 1450°C compared to hydroxyapatite may be necessary due to the different sintering characteristics and melting behavior of the yttria-stabilized zirconia material.

[0095] The 2-hour sintering duration at 1450°C may be sufficient to achieve near-complete densification of the yttria-stabilized zirconia material. The shorter sintering time compared to hydroxyapatite processing may be enabled by the higher processing temperature and the enhanced sintering kinetics of the yttria-stabilized zirconia composition. The reduced processing time may also minimize grain growth and may preserve fine structural features in the sintered scaffold 4.

[0096] The yttria-stabilized zirconia sintering process at 1450°C for 2 hours may produce a sintered scaffold 4 that is approximately 97% dense. The 97% density may represent nearcomplete consolidation of the ceramic material, resulting in enhanced mechanical properties and structural integrity. When the internal lattice structure is accounted for in the densitycalculations, the sintered scaffold 4 may exhibit approximately 97% of the theoretical density for the given geometric configuration.

[0097] As shown in Figure IB, the sintered scaffold 4 may demonstrate the successful transformation from the initial ceramic slurry 3 through the thermal processing stagesto the final consolidated ceramic structure. The sintered scaffold 4 may retain the complex internal lattice architecture while exhibiting the enhanced density and mechanical properties achieved through the sintering process. The progression from the ceramic slurry 3 to the sintered scaffold 4 may illustrate the effectiveness of the thermal processing sequence in producing high-quality ceramic components with intricate geometries.

[0098] The sintered scaffold 4 may feature sub-millimetric channels with diameters ranging from 100 to 300 pm. These sub-millimetric channels may be formed through the removal of the carbonaceous framework during the thermal processing stage, with the channel dimensions corresponding to the scaled features of the original pyrolyzed structure 2. The 100 to 300 pm diameter range may provide channels that are suitable for biological applications, allowing for cell migration and nutrient transport while maintaining structural connectivity throughout the sintered scaffold 4.

[0099] The sintered scaffold 4 may include intricate features such as 0.1mm holes that demonstrate the precision achievable through the sintering assisted additive manufacturing process. The 0.1mm holes may represent fine structural details that are preserved throughout the thermal processing sequence, from the initial resin scaffold 1 through the pyrolyzed structure 2 to the final sintered scaffold 4. These intricate features may showcase the capability of the manufacturing process to produce complex ceramic geometries with fine feature resolution that would be challenging to achieve through conventional ceramic forming methods.

[0100] The dimensional accuracy of the intricate features in the sintered scaffold 4 may be maintained through the controlled shrinkage characteristics of the thermal processing stages. The predictable dimensional changes that occur during pyrolysis and sintering may allow forprecise scaling of the initial design parameters to achieve the desired final dimensions in the sintered scaffold 4. The 0.1mm holes and other fine features may retain their geometric relationships and proportional spacing throughout the manufacturing process.

[0101] The sintered scaffold 4 may undergo a cleaning and polishing process following the thermal processing stages to remove any residual processing materials and to achieve the desired surface finish. The cleaning process may involve removal of any remaining carbon residue or processing aids that may be present on the surface of the sintered scaffold 4. The polishing process may enhance the surface quality and may prepare the sintered scaffold 4 for final inspection and characterization.

[0102] Final geometry and channel diameters of the sintered scaffold 4 may be measured using optical microscopy techniques to verify dimensional accuracy and feature resolution. The optical microscope measurements may confirm that the sub-millimetric channels fall within the specified 100 to 300 pm diameter range and that intricate features such as the 0.1mm holes meet the design specifications. The measurement process may provide quality control verification for the sintering assisted additive manufacturing process and may ensure that the sintered scaffold 4 meets the required geometric and dimensional criteria for the intended application.

[0103] Following the sintering process that produces the sintered scaffold 4, the ceramic structure may undergo post-processing operations to achieve the final product specifications. The post-processing operations may include cleaning and polishing procedures that remove residual processing materials and enhance the surface characteristics of the sintered scaffold 4. These post-processing steps may be performed to prepare the sintered scaffold 4 for final inspection and potential biomedical applications.

[0104] The sintered scaffold 4 may undergo a cleaning process that removes any remaining carbon residue, processing aids, or surface contaminants that may be present following the thermal processing stages. The cleaning process may involve chemical cleaning agents, ultrasonic cleaning, or mechanical cleaning methods that effectively remove unwanted materials from thesurface and internal channels of the sintered scaffold 4. The cleaning procedures may be selected based on the ceramic material composition and the specific contaminants that may be present on the sintered scaffold 4.

[0105] The cleaning process may be particularly important for removing any residual carbonaceous material that may remain after the decomposition of the pyrolyzed structure 2 during thermal processing. Complete removal of carbon residue may ensure that the sintered scaffold 4 exhibits the desired biocompatibility characteristics for biomedical applications. The cleaning process may also remove any processing aids or binder materials that may have been introduced during the ceramic slurry 3 preparation or infiltration stages.

[0106] Following the cleaning process, the sintered scaffold 4 may undergo a polishing process that enhances the surface finish and dimensional accuracy of the ceramic structure. The polishing process may involve mechanical polishing techniques, chemical polishing methods, or combinations of both approaches to achieve the desired surface characteristics. The polishing operations may be applied to external surfaces of the sintered scaffold 4 as well as accessible internal surfaces within the channel network.

[0107] The polishing process may improve the surface smoothness of the sintered scaffold 4, which may be beneficial for biomedical applications where surface texture can influence cellular interactions and tissue integration. The polishing operations may also remove minor surface irregularities or processing artifacts that could affect the performance or appearance of the sintered scaffold 4. The extent of polishing may be controlled to maintain the desired surface characteristics while preserving the dimensional accuracy of fine features such as the sub- millimetric channels.

[0108] The final geometry and channel diameters of the sintered scaffold 4 may be measured using optical microscopy techniques to verify dimensional accuracy and feature resolution. An optical microscope may provide the magnification and resolution necessary to accurately measure the sub-millimetric channels and intricate features of the sintered scaffold 4.The optical microscope measurements may confirm that the channel diameters fall within the specified range of 100 to 300 pm and that other geometric features meet the design specifications.

[0109] The optical microscope measurement process may involve systematic examination of multiple locations throughout the sintered scaffold 4 to assess dimensional consistency and manufacturing quality. The measurements may include channel diameter verification, wall thickness assessment, and evaluation of feature spacing and alignment. The optical microscope may enable non-destructive measurement of the sintered scaffold 4, allowing for complete quality assessment without compromising the structural integrity of the ceramic part.

[0110] The measurement data obtained through optical microscopy may provide quality control verification for the sintering assisted additive manufacturing process. The dimensional measurements may confirm that the manufacturing process successfully produces ceramic parts with the desired geometric characteristics and feature resolution. The optical microscope measurements may also provide feedback for process optimization and may enable continuous improvement of the manufacturing parameters to achieve enhanced dimensional accuracy and feature quality in subsequent production runs.

[0111] The complete manufacturing process may integrate multiple sequential steps to produce ceramic scaffolds with intricate shapes and internal lattice structures through coordinated parameter control and material transformation stages. The integration of stereolithography printing, pyrolysis, ceramic slurry infiltration, drying, and thermal processing may enable the production of complex ceramic geometries that would be difficult to achieve through conventional ceramic forming methods.

[0112] The initial mold design stage may establish the foundation for all subsequent processing steps by incorporating design parameters that account for dimensional changes occurring during thermal processing. The mold design may consider the cumulative effects of pyrolysis shrinkage and sintering densification to achieve the desired final dimensions in theceramic scaffold. The design parameters may include wall thickness limitations, beam diameter specifications, and spacing requirements that ensure structural stability throughout the manufacturing sequence.

[0113] The stereolithography printing stage may translate the digital mold design into a physical resin structure with precise geometric features and controlled internal architecture. The printing parameters may include layer thickness, exposure time, and curing intensity that determine the mechanical properties and thermal behavior of the resin structure during subsequent pyrolysis. The resin composition may be selected to provide controlled decomposition characteristics that result in predictable shrinkage and carbon structure formation.

[0114] The pyrolysis stage may convert the printed resin structure into a carbonaceous framework through controlled thermal decomposition in an oxygen-limited environment. The pyrolysis parameters may include heating rate, maximum temperature, and atmosphere composition that influence the dimensional stability and structural integrity of the carbon framework. The pyrolysis conditions may be optimized to achieve isotropic shrinkage while maintaining the geometric relationships between structural features.

[0115] The ceramic slurry infiltration stage may introduce ceramic particles into the carbonaceous framework through controlled flow and filling processes. The slurry parameters may include particle size distribution, solid loading, viscosity, and flow characteristics that determine the infiltration efficiency and final ceramic content. The infiltration process may be conducted under conditions that maximize ceramic particle packing while avoiding damage to the carbonaceous framework.

[0116] The drying stage may remove the liquid medium from the ceramic slurry through controlled evaporation processes that prevent crack formation and structural distortion. The drying parameters may include temperature, humidity, and time duration that ensure uniformmoisture removal without generating internal stresses. The drying conditions may be selected to maintain the spatial distribution of ceramic particles within the carbonaceous framework.

[0117] The thermal processing stage may simultaneously decompose the carbonaceous framework and sinter the ceramic particles to produce the final consolidated ceramic scaffold. The thermal processing parameters may include heating rate, maximum temperature, hold time, and atmosphere composition that control both the carbon removal kinetics and the ceramic densification mechanisms. The thermal processing conditions may be optimized for specific ceramic compositions to achieve the desired density and mechanical properties.

[0118] The integration of these sequential processing stages may enable precise control over the final ceramic scaffold characteristics through coordinated parameter optimization. The heating rate during pyrolysis may influence the carbon structure formation, which may affect the subsequent ceramic infiltration efficiency and final density distribution. The ceramic slurry composition may determine the sintering behavior and final mechanical properties of the consolidated ceramic scaffold.

[0119] The process parameter interactions may be particularly important for achieving controlled porosity and density levels in the final ceramic scaffold. The initial mold design may establish the macroscopic porosity through the lattice structure geometry, while the ceramic slurry infiltration and sintering parameters may control the microscopic porosity and density distribution. The combination of these porosity levels may result in ceramic scaffolds with hierarchical pore structures suitable for biological applications.

[0120] The dimensional accuracy of the final ceramic scaffold may depend on the cumulative effects of shrinkage during pyrolysis and densification during sintering. The pyrolysis shrinkage may be controlled through the resin composition and thermal processing parameters, while the sintering shrinkage may be influenced by the ceramic particle characteristics and sintering conditions. The coordination of these shrinkage mechanisms may enable predictable dimensional scaling from the initial mold design to the final ceramic scaffold.

[0121] The manufacturing process integration may enable the production of ceramic scaffolds with sub-millimetric channel networks that maintain dimensional accuracy and structural connectivity throughout the processing sequence. The channel dimensions may be controlled through the initial mold design parameters, with the final channel diameters determined by the cumulative effects of pyrolysis shrinkage and sintering densification. The channel network connectivity may be preserved through careful control of the thermal processing parameters that prevent structural collapse or channel blockage.

[0122] The process may accommodate different ceramic compositions through adjustment of the thermal processing parameters while maintaining the same basic manufacturing sequence. Hydroxyapatite-based ceramic scaffolds may be produced using lower sintering temperatures and longer processing times to achieve controlled porosity suitable for bone tissue engineering applications. Yttria-stabilized zirconia-based ceramic scaffolds may be produced using higher sintering temperatures and shorter processing times to achieve near-complete densification for structural applications requiring enhanced mechanical properties.

[0123] The manufacturing process integration may provide flexibility in producing ceramic scaffolds with tailored characteristics for specific applications through parameter optimization. The porosity level may be controlled through the ceramic slurry composition and sintering parameters, with higher ceramic loading and more aggressive sintering conditions resulting in denser scaffolds. The mechanical properties may be influenced by the ceramic composition, sintering temperature, and final density achieved through the thermal processing stage.

[0124] The quality control aspects of the integrated manufacturing process may involve monitoring and verification of parameters at each processing stage to ensure consistent scaffold production. The stereolithography printing parameters may be verified through dimensional measurement and surface quality assessment of the printed resin structures. The pyrolysis parameters may be monitored through temperature measurement and dimensional change tracking during the thermal decomposition process.T1

[0125] The ceramic slurry infiltration efficiency may be assessed through weight gain measurements and visual inspection of the filled structures. The drying process may be monitored through moisture content measurement and crack detection to ensure proper solvent removal without structural damage. The thermal processing stage may be controlled through temperature monitoring and atmosphere composition measurement to achieve consistent carbon removal and ceramic sintering.

[0126] The integrated manufacturing process may enable scalable production of ceramic scaffolds through standardization of processing parameters and quality control procedures. The process reproducibility may be achieved through precise control of each processing stage and systematic monitoring of the parameter interactions that influence the final scaffold characteristics. The manufacturing sequence may be adapted for different production volumes through adjustment of batch sizes and processing equipment while maintaining the same fundamental process integration principles.

[0127] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.DOCTRINE OF EQUIVALENTS

[0128] This description of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form described, and many modifications and variations are possible in light of the teaching above. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications. This description will enable others skilled in the art to best utilize and practice the invention in various embodiments and with various modifications as are suited to a particular use. The scope of the invention is defined by the following claims.

[0129] As used herein, the singular terms "a," "an," and "the" may include plural referents unless the context clearly dictates otherwise. Reference to an object in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more."

[0130] As used herein, the terms "approximately" and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs to a close approximation. When used in conjunction with a numerical value, the terms can refer to a range of variation of less than or equal to ± 10% of that numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1 %, less than or equal to ±0.5%, less than or equal to ±0.1 %, or less than or equal to ±0.05%.

[0131] Additionally, amounts, ratios, and other numerical values may sometimes be presented herein in a range format. It is to be understood that such range format is used for convenience and brevity and should be understood flexibly to include numerical values explicitly specified as limits of a range, but also to include all individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly specified. For example, a ratio in the range of about 1 to about 200 should be understood to include the explicitly recited limits of about 1 and about 200, but also to include individual ratios such as about 2, about 3, and about 4, and sub-ranges such as about 10 to about 50, about 20 to about 100, and so forth.

Claims

CLAIMS1. A device manufacturing process, comprising: printing a mold from a resin using stereolithography; pyrolyzing the mold to convert the resin into a carbon structure; filling the carbon structure with a ceramic slurry; drying the ceramic slurry within the carbon structure; and thermally processing the carbon structure and ceramic slurry to decompose the carbon structure and sinter the ceramic slurry into a consolidated ceramic part.

2. The device manufacturing process of claim 1, wherein designing the mold comprises limiting beam thickness and wall thickness to 0.6mm to prevent distortion during pyrolysis.

3. The device manufacturing process of claim 2, wherein the mold is designed for isotropic shrinkage of approximately 50% during pyrolysis.

4. The device manufacturing process of claim 1, wherein printing the mold comprises using stereolithography with a wavelength of 405 nm.

5. The device manufacturing process of claim 4, wherein the resin comprises:15 to 25% of 2,4,6-trioxo-l,3,5-triazine-l,3,5(2H,4H,6H)-triyl)tri-2,l-ethanediyl triacrylate;40 to 60% of acrylate monomer; and25 to 45% urethane dimethacrylate.

6. The device manufacturing process of claim 1, wherein pyrolyzing the mold comprises heating the resin at temperatures ranging from 400°C to 800°C in an oxygen-limited environment.

7. The device manufacturing process of claim 1, wherein the ceramic slurry comprises nanometric hydroxyapatite particles with a theoretical density of 3.1 g / cm3.

8. The device manufacturing process of claim 1, wherein the ceramic slurry comprises nanometric yttria-stabilized zirconia particles with a density of 6.05 g / cm3.

9. The device manufacturing process of claim 7, wherein thermally processing comprises sintering at 1200°C for 6 hours to produce a consolidated ceramic part with approximately 70% relative density.

10. The device manufacturing process of claim 8, wherein thermally processing comprises sintering at 1450°C for 2 hours to produce a consolidated ceramic part that is approximately 97% dense.

11. The device manufacturing process of claim 1, further comprising designing a mold for stereolithography resin printing, wherein the mold is configured to minimize distortion from pyrolysis and sintering.

12. A ceramic scaffold device, comprising: an intricate lattice structure formed from a ceramic material, wherein the ceramic material comprises at least one of hydroxyapatite and yttria-stabilized zirconia, and wherein the lattice structure includes sub-millimetric channels having diameters ranging from 100 to 300 micrometers, the ceramic scaffold device being produced by filling a pyrolyzed carbon mold with a ceramic slurry and thermally processing the filled mold to remove the carbon mold and sinter the ceramic material.

13. The ceramic scaffold device of claim 12, wherein the ceramic material comprises hydroxyapatite with a theoretical density of 3.1 g / cm3.

14. The ceramic scaffold device of claim 12, wherein the ceramic material comprises yttria-stabilized zirconia with a density of 6.05 g / cm3.

15. The ceramic scaffold device of claim 13, wherein the ceramic scaffold device has approximately 70% relative density.

16. The ceramic scaffold device of claim 14, wherein the ceramic scaffold device is approximately 97% dense.

17. The ceramic scaffold device of claim 12, wherein the intricate lattice structure includes features with dimensions of 0.1mm.

18. A mold production process for additive manufacturing, comprising: producing a mold structure by stereolithography of a resin; and pyrolyzing the mold structure to convert the resin into a carbon structure, wherein the pyrolyzing results in isotropic shrinkage of approximately 50%.

19. The mold production process of claim 18, wherein producing the mold structure comprises using stereolithography with a wavelength of 405 nm.

20. The mold production process of claim 19, wherein the resin comprises:15 to 25% of 2,4,6-trioxo-l,3,5-triazine-l,3,5(2H,4H,6H)-triyl)tri-2,l-ethanediyl triacrylate;40 to 60% of acrylate monomer; and25 to 45% urethane dimethacrylate.

21. The mold production process of claim 18, wherein pyrolyzing the mold structure comprises heating the resin at temperatures ranging from 400°C to 800°C in an oxygen-limited environment.

22. The mold production process of claim 18, further comprising designing a mold structure with beam thickness and wall thickness limited to 0.6mm to reduce distortion during thermal processing.

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