A large porous artificial bone based on adhesive jetting molding and a method for manufacturing the same

Abstract

The application discloses a kind of large porous artificial bone based on binder jetting forming and preparation method thereof, it is related to artificial bone technical field.The preparation method of the application is to obtain printing body with binder jetting equipment with ceramic secondary particles as raw material;Again, defatting, sintering, obtain porous artificial bone;Among them, the preparation of ceramic secondary particles is as follows: S1, take ceramic powder 50~99.9 parts, sintering aid powder 0~20 parts, glass powder 0.1~50 parts, pore-forming agent 0~40 parts by mass fraction, mix uniformly, obtain composite powder;S2, granulation to composite powder, obtain granulated powder;S3, the low-temperature sintering is carried out to the granulated powder, the temperature of the low-temperature sintering is higher than the softening point temperature of glass and lower than the sintering temperature of ceramic powder, ceramic secondary particles are prepared after sintering.The application uses ceramic secondary particles as binder jetting raw material, introduces pore-forming agent, and prepares the required porous ceramic artificial bone by controlling the content and particle size of pore-forming agent.

Description

Technical Field

[0001] This invention relates to the field of large-size porous artificial bone technology, and in particular to a large-size porous artificial bone based on adhesive spray molding and its preparation method. Background Technology

[0002] In modern society, the number of pet owners is growing rapidly. As people place greater importance on their pets, the demand for veterinary care for sick pets is also increasing. Large pets suffering irreversible bone damage due to accidents require replacement with artificial bone. Similarly, large wild animals and endangered species in zoos also require bone replacement therapy when they suffer severe bone injuries. Furthermore, the human body also contains large bones. Therefore, the demand for large, biocompatible artificial bone replacements is constantly rising. Natural bone typically has a complex porous structure, requiring artificial replacements to mimic the internal structure of natural bone as closely as possible, achieving not only high mechanical properties but also promoting bone regeneration. Porous ceramic bone scaffolds are excellent candidates for bone replacement, but complex-shaped ceramics are difficult to manufacture using traditional molding processes.

[0003] 3D printing offers a promising technological approach for fabricating ceramic materials with complex shapes. The model required for 3D printing can be created by combining X-ray imaging technology to obtain the shape and dimensions of the target bone. This means that in the future, when bone replacement therapy is needed, this model can be used to fabricate porous ceramic bone scaffolds through 3D printing.

[0004] Large-scale bone scaffolds are typically over 300mm in length, such as 500mm. Binder jet 3D printing is an ideal method for fabricating large-scale porous ceramic bone scaffolds, capable of constructing large and complex geometric ceramic parts with high precision and high forming efficiency. Although binder jet-produced ceramics have very high porosity, their density and strength are very low, and the internal pores are uncontrollable, limiting their development in the fabrication of large porous artificial bones. This is mainly because binder jet technology requires highly fluid powder during powder spreading, typically using coarse powder larger than 20µm as the printing powder. This significantly reduces the sintering activity of the ceramic powder, preventing dense sintering. Large coarse ceramic particles can only form partial sintering necks, resulting in low strength and a lack of controllable porosity. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that it is difficult to prepare existing large-size porous artificial bones and the morphology of their internal pores is difficult to control.

[0006] To address the above problems, the present invention proposes the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing large-scale porous artificial bone based on adhesive spray molding, comprising:

[0008] Based on the size and shape of the target bone, a model was created. Secondary ceramic particles were used as raw material for powder preparation, and a binder spraying device was used to fabricate the porous artificial bone, obtaining a printed body. The printed body was then degreased and sintered to obtain the porous artificial bone.

[0009] The secondary ceramic particles are prepared by the following steps:

[0010] S1. By weight, take 50-99.9 parts of ceramic powder, 0-20 parts of sintering aid powder, 0.1-50 parts of glass powder, and 0-40 parts of pore-forming agent, mix them evenly, dry and sieve to obtain composite powder raw material;

[0011] S2. The composite powder is granulated to obtain granulated powder with a particle size of 0.1um to 150um;

[0012] S3. The granulated powder is sintered at a low temperature. The low temperature sintering temperature is higher than the softening point temperature of glass and lower than the sintering temperature of ceramic powder. After sintering, secondary ceramic particles are obtained.

[0013] The particle size range of the ceramic powder is 10 nm to 10 μm, preferably 50 nm to 1 μm; the particle size range of the glass powder is 100 nm to 50 μm, preferably 500 nm to 10 μm; the particle size range of the sintering aid powder is 10 nm to 10 μm, preferably 50 nm to 1 μm; and the particle size range of the pore-forming agent is 0.1 to 50 μm.

[0014] To ensure the high sintering activity of the raw material powder used in adhesive spraying, this invention employs a melt-re-firing method to prepare porous secondary ceramic particles, enabling the printed body to achieve porosity and densification through sintering. Specifically, by adding glass powder and a pore-forming agent to the ceramic powder, high-density, high-sphericity, and high-flowability secondary ceramic particles are obtained after regranulation and low-temperature sintering. The low-temperature sintering temperature is higher than the softening point of glass but lower than the sintering temperature of the ceramic powder. During low-temperature melt sintering, due to capillary forces, the molten glass permeates and diffuses into the gaps between the ceramic powder particles, causing the particle volume to shrink and adhere to the ceramic powder, thereby increasing the density of the secondary ceramic particles. The resulting secondary ceramic particles are highly beneficial for the powder bed spreading operation of the adhesive spraying equipment, significantly improving the powder bed density while retaining the high sintering activity of the ceramic powder. When the degreased printed body is sintered, the molten glass undergoes another infiltration and diffusion. The capillary force generated by the liquid phase further increases the initial density of the ceramic sintered body. When the temperature reaches the sintering temperature of the ceramic, the ceramic powder begins to sinter and densify. The liquid phase promotes the diffusion and mass transfer of the ceramic powder, ultimately resulting in a high-density, porous binder-sprayed ceramic.

[0015] It should be noted that by controlling printing parameters (glue saturation, powder spreading speed, roller speed, etc.) during printing, a printed object with good shape and precision can be obtained.

[0016] Understandably, in step S1, the proportion of glass powder in the raw material powder should not be too high, so as not to affect the performance of the final ceramic product. The mass fraction of glass powder = glass powder / (glass powder + sintering aid powder + ceramic powder) should be 1%-35%, with 5%-25% being more preferred.

[0017] Furthermore, the ceramic powder is selected from at least one of alumina, zirconium oxide, zirconium oxide-toughened alumina, and silicon nitride.

[0018] Furthermore, the sintering aid powder is selected from one or more of MgO, ZrO2, CaO, SiO2, Cr2O3, Al2O3, SrO, TiO2, Sc2O3, Y2O3, Li2O, MgF2, and YF3.

[0019] Furthermore, the glass powder is selected from one or more of high silica glass, soda-lime glass, lead silicate glass, aluminosilicate glass, borosilicate glass, and phosphate glass.

[0020] Generally speaking, the main component of glass powder is SiO2. Other components in glass powder may include one or more of the following: MgO, Al2O3, CaO, Na2O, K2O, Li2O, B2O3, P2O5, PbO, CaF2, Y2O3, as well as metal halides, metal oxides, metal nitrides, rare earth halides, rare earth oxides, and rare earth nitrides, but are not limited to these.

[0021] Furthermore, the pore-forming agent includes one or more of polystyrene, starch, PMMA, walnut shell powder, and plant fiber.

[0022] Furthermore, the granulated powder contains organic matter, and before the granulated powder is sintered at low temperature in step S3, the granulated powder is further degreased.

[0023] It should be noted that this degreasing step is used to remove organic pore-forming agents and organic binders used in the granulation process.

[0024] In step S2, the granulation method includes one of the following: dry molding and crushing granulation, wet molding and crushing granulation, wet granulation, fluidized bed granulation, pressure spray granulation, rotary spray granulation, water atomization spray granulation, gas atomization spray granulation, and drip sedimentation granulation, but is limited to these few methods.

[0025] Furthermore, the degreasing temperature is 300–600°C.

[0026] Degreasing methods include one or more of vacuum thermal degreasing, air thermal degreasing, and protective atmosphere thermal degreasing, but are not limited to these methods. The degreasing temperature is between 300-600℃, depending on the thermal decomposition of the organic matter contained therein.

[0027] Furthermore, the temperature of the low-temperature sintering in step S3 is 900℃~1600℃.

[0028] Generally, due to limitations in the composition of glass powder, its softening point is typically between 500 and 1300°C. Therefore, in step S3, the sintering temperature for low-temperature sintering is between 900°C and 1600°C. This sintering temperature should be higher than the glass softening point to allow the glass to melt and promote particle volume shrinkage. Simultaneously, this low-temperature melting and sintering temperature should be lower than the liquid-phase sintering temperature of the ceramic powder. It should be noted that the softening point is the temperature of the fourth inflection point measured using a macroscopic differential calorimeter (DTA).

[0029] The sintering process for the printed body in this invention is a conventional preparation process for ceramic materials. Appropriate equipment and processes are used depending on the specific ceramic material. For example, a muffle furnace is used for alumina and zirconium oxide, and an atmosphere furnace or pressure furnace is used for silicon nitride, but it is not limited to these methods. The sintering temperature should be between 1300-1900℃, which is determined by the densification process of the ceramic.

[0030] It should be noted that, in order to make the performance of porous artificial bone approximate the density, strength, and porosity of known natural bone, this invention designs a macroscopic porous structure within the model during model building. The shape of the pore units can include: bone-shaped, micro-curved, cylindrical, cubic, hexagonal, octagonal, etc., and is not limited to these. The binder jet printing technology, based on the powder used, printhead resolution, and print layer thickness requirements, controls the size of the macroscopic pores to 100-600 μm. Furthermore, the proportion of submicron and micron-sized pores in the ceramic matrix is ​​directly determined by controlling the type, size, and content of the pore-forming agent. The added pore-forming agent is uniformly distributed within the matrix, forming pores after high-temperature sintering. The size and shape of the pores are the same as the pore-forming agent; typically, the size of the pore-forming agent is 0.1-150 μm. The larger the pore-forming agent size and the higher its content, the higher the porosity of the matrix.

[0031] In summary, this invention jointly regulates the pore structure of artificial bone from two aspects: material composition design and macroscopic pore design in modeling, in order to obtain ideal porous artificial bone. Through sample preparation, performance characterization, and microstructural observation, the relationship between the model's macroscopic pores and material composition ratios (type, size, and content of pore-forming agents) and the properties and pore structure of the prepared artificial bone is obtained.

[0032] Secondly, the present invention provides a large porous artificial bone, which is prepared by the aforementioned preparation method.

[0033] Thirdly, the present invention provides a raw material for preparing large porous artificial bones using adhesive spray molding, wherein the raw material is secondary ceramic particles, and the secondary ceramic particles are prepared by the following steps:

[0034] S1. By weight, take 50-99.9 parts of ceramic powder, 0-20 parts of sintering aid powder, 0.1-50 parts of glass powder, and 0-40 parts of pore-forming agent, mix them evenly, dry and sieve to obtain composite powder raw material;

[0035] S2. The composite powder is granulated to obtain granulated powder with a particle size of 0.1um to 150um;

[0036] S3. The granulated powder is sintered at a low temperature. The low temperature sintering temperature is higher than the softening point temperature of glass and lower than the sintering temperature of ceramic powder. After sintering, secondary ceramic particles are obtained.

[0037] The particle size range of the ceramic powder is 10 nm to 10 μm, the particle size range of the glass powder is 100 nm to 50 μm, the particle size range of the sintering aid powder is 10 nm to 10 μm, and the particle size range of the pore-forming agent is 0.1 to 50 μm.

[0038] It should be noted that in step S1, in order to reduce the breakage of the pore-forming agent, the ceramic powder, additive powder and glass powder can be mixed evenly first, and then the pore-forming agent can be added and mixed.

[0039] The granulated powder obtained in step S2 should have high sphericity and high flowability.

[0040] The secondary ceramic particles obtained by low-temperature sintering have higher density and strength compared to granulated powders, while maintaining high sphericity and flowability. Furthermore, the loose density, tapped density, and powder bed density are significantly improved.

[0041] Compared with the prior art, the technical effects achieved by the present invention include:

[0042] This invention utilizes adhesive spray molding technology to fabricate large-size porous ceramic artificial bones without requiring support, without damaging the printing surface, and with high molding efficiency. By selecting biocompatible ceramic powders, sintering aids, and glass powders, the pore-forming agent can be completely removed during the preparation process, ensuring that the resulting artificial bone is non-toxic and harmless to organisms. The pore morphology of large-size porous ceramic artificial bones can be comprehensively controlled by modeling and constructing macroscopic pore structures and raw material powders with internal pore structures, achieving a multi-level pore structure with submicron-scale pores, micron-scale pores, and macroscopic pores, providing favorable attachment and regeneration areas for bone regeneration.

[0043] The present invention provides a method for preparing large porous artificial bone based on adhesive spray molding. Through structural design, material composition design and pore-forming agent improvement, it achieves the effect of rapid molding preparation of large porous artificial bone scaffolds based on adhesive spraying technology. It has the advantages of controllable performance and controllable pore structure, and can more realistically replicate the structure of natural bone. Attached Figure Description

[0044] Figure 1 This is a process flow diagram of the method for preparing large porous artificial bone based on adhesive spray molding according to the present invention;

[0045] Figure 2 This is a schematic diagram of the method for preparing large porous artificial bone based on adhesive spray molding according to the present invention.

[0046] Figure 3 Macroscopic pore diagram for model design of the large porous artificial bone preparation method based on adhesive spray molding of the present invention;

[0047] Figure 4This is a high-magnification SEM image of a large porous ceramic obtained by adhesive spray molding in Example 2 of the present invention.

[0048] Figure 5 This is a low-magnification SEM image of a large porous ceramic obtained by adhesive spray molding in Example 2 of the present invention. Detailed Implementation

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0050] Example 1

[0051] This embodiment provides a large-scale artificial bone based on adhesive spray molding and its preparation method, as detailed below:

[0052] The powder raw material is silicon nitride with a medium particle size of 1 μm. The sintering aids are alumina and yttrium oxide with medium particle sizes of 200 nm and 50 nm, respectively. The glass powder is borosilicate glass with a particle size of 1 μm.

[0053] S1: By weight, take 85 parts silicon nitride, 5 parts aluminum oxide, 5 parts yttrium oxide, and 5 parts glass powder. Add silicon nitride grinding balls to alcohol as a medium, and mix by roller ball milling for 12 hours. After drying with a rotary evaporator, pass through a 100-mesh sieve to obtain a uniformly mixed powder.

[0054] S2: The S1 neutralized and mixed powder is subjected to cold isostatic pressing by cold isostatic pressing. The formed block is crushed and passed through a 200-mesh sieve to control the particle size of the granulated powder to be less than 74um.

[0055] Since the granulated powder in this embodiment does not contain organic matter, it is not necessary to degrease the granulated powder.

[0056] S3: The loose granulated powder is placed into an atmosphere sintering furnace and sintered at low temperature in an argon atmosphere of 0.1 MPa for 2 hours to obtain high-density and high-strength ceramic secondary particles.

[0057] S4: Using a commercial adhesive jet printer and commercial glue to print parts, the powder thickness was set at 150um, and the printing parameters (powder spreading speed, glue spraying amount, etc.) were optimized. Finally, a ceramic print with good shape and precision was printed. No macroscopic pores were designed inside during the model design.

[0058] S6: The printed samples were degreased using a muffle furnace. The degreasing process consisted of vacuum degreasing and air degreasing, both at a temperature of 550℃ for 2 hours. The degreased samples were then sintered using an atmosphere sintering furnace at 1800℃ for 2 hours, resulting in high-density, high-performance silicon nitride ceramics.

[0059] Example 2

[0060] This embodiment provides a large-scale porous artificial bone based on adhesive spray molding and its preparation method, as detailed below:

[0061] The raw materials for the powder, sintering aid, and glass powder are the same as in Example 1. Additionally, this example uses PMMA as a pore-forming agent with a particle size of 10 μm.

[0062] S1: By mass, take 85 parts of silicon nitride, 5 parts of aluminum oxide, 5 parts of yttrium oxide, and 5 parts of glass powder. Using alcohol as a medium, add silicon nitride grinding balls and mix by drum ball milling for 12 hours. Add 2 parts of PMMA powder (2% of the total mass of ceramic powder) and mix by drum ball milling for 3 hours. After drying using a rotary evaporator, pass through a 100-mesh sieve to obtain a uniformly mixed powder.

[0063] S2: The S1 neutralized and mixed powder is subjected to cold isostatic pressing by cold isostatic pressing. The formed block is crushed and passed through a 200-mesh sieve to control the particle size of the granulated powder to be less than 74um.

[0064] S3 Powder Degreasing: Granulated powder is degreased using a muffle furnace. The degreasing process is air degreasing at a temperature of 550℃ for 2 hours.

[0065] S4: The degreased and loose powder is placed into an atmosphere sintering furnace and sintered at low temperature in an argon atmosphere of 0.1 MPa for 2 hours to obtain high-density and high-strength ceramic secondary particles.

[0066] S5: Using a commercial adhesive jet printer and commercial glue to print parts, the powder thickness is set at 150um, and the printing parameters (powder spreading speed, glue spraying amount, etc.) are optimized. Finally, a ceramic print body with good shape and precision is printed. No macro holes are designed inside during the model design.

[0067] S6: The printed samples were degreased using a muffle furnace. The degreasing process consisted of vacuum degreasing and air degreasing, both at a temperature of 550℃ for 2 hours. The degreased samples were then sintered using an atmosphere sintering furnace at 1800℃ for 2 hours, resulting in high-density, high-performance silicon nitride ceramics.

[0068] Example 3

[0069] This embodiment provides a large porous artificial bone based on adhesive spray molding and its preparation method. The raw materials and preparation process are the same as in Embodiment 2, except that the amount of PMMA pore-forming agent added is 6 parts (6% of the total mass of ceramic powder).

[0070] Example 4

[0071] This embodiment provides a large porous artificial bone based on adhesive spray molding and its preparation method. The raw materials and preparation process are the same as in Embodiment 2, except that the amount of PMMA powder added is 20 parts (20% of the total mass of ceramic powder).

[0072] Example 5

[0073] This embodiment provides a large porous artificial bone based on adhesive spray molding and its preparation method. The raw materials and preparation process are the same as in Embodiment 3, except that the particle size of the pore-forming agent PMMA powder is 30um.

[0074] Example 6

[0075] This embodiment provides a large porous artificial bone based on adhesive spray molding and its preparation method. The raw materials and preparation process are the same as in embodiment 3. The difference is that when constructing the structural model in step S5, macroscopic pores are designed, the pore unit structure is cylindrical, the pore size is 500um, and the cross-sectional material removal rate is 20%.

[0076] Example 7

[0077] This embodiment provides a large porous artificial bone based on adhesive spray molding and its preparation method. The raw materials and preparation process are the same as in embodiment 3. The difference is that when constructing the structural model in step S5, macroscopic pores are designed, the pore unit structure is cylindrical, the pore size is 500um, and the cross-sectional material removal rate is 25%.

[0078] The relevant data of the large porous artificial bone (silicon nitride ceramic) prepared in Examples 1-6 above are shown in Table 1.

[0079] Table 1. Experimental data and comparative data of Examples 1-3 of the present invention.

[0080]

[0081]

[0082] As can be seen from the data in Table 1, Example 1 of this invention uses secondary ceramic particles without pore-forming agents to prepare adhesive-sprayed silicon nitride ceramics, which have high density, low porosity, and high strength. Examples 2-4 use secondary ceramic particles with added pore-forming agents to prepare adhesive-sprayed porous silicon nitride ceramics. In Examples 2-3, after adding a small amount of pore-forming agent, the porosity of the porous ceramics increases, and the density and mechanical properties decrease. However, when the pore-forming agent content is too high (Example 4), due to the uneven pores inside the printed body, the ceramic body cracks after debinding and sintering, resulting in extremely low strength of the ceramic block, which cannot meet the application requirements. Example 5 uses secondary ceramic particles with large-particle-size pore-forming agents to prepare adhesive-sprayed porous silicon nitride ceramics, which have a slightly lower increase in porosity compared to Example 3, while the strength remains unchanged.

[0083] Furthermore, high-magnification microscopic observation of the surface of the porous silicon nitride ceramic prepared in Example 2 revealed the formation of a micron-scale pore structure retained after degreasing with a pore-forming agent, such as... Figure 4 , Figure 5 As shown.

[0084] Example 6, based on Example 3, designed a macroporous structure. Due to the presence of macroporous pores, the strength of the resulting printed part was weakened; however, the macroporous pores increased the contact area with cells, promoting bone regeneration. Example 7 increased the proportion of macroporous pores, resulting in a further decrease in the strength of the printed part.

[0085] Therefore, this invention is based on the technology of using secondary ceramic particles as a binder spraying material. By introducing a pore-forming agent and controlling its content and particle size, porous ceramic artificial bones that meet the requirements for porosity and strength can be prepared using binder spraying technology. Understandably, the macroscopic pore structure designed within the model in this invention can be as follows... Figure 3 The three pore structures shown, but not limited to those illustrated, are used to rapidly fabricate large porous artificial bones that meet performance requirements.

[0086] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0087] The above description describes specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing large-scale porous artificial bone based on adhesive spray molding, characterized in that, include: Based on the size and shape of the target bone, a model was created. Secondary ceramic particles were used as raw material for powder preparation, and a binder spraying device was used to fabricate the porous artificial bone, obtaining a printed body. The printed body was then degreased and sintered to obtain the porous artificial bone. The secondary ceramic particles are prepared by the following steps: S1. By weight, take 50-99.9 parts of ceramic powder, 0-20 parts of sintering aid powder, 0.1-50 parts of glass powder, and 0-40 parts of pore-forming agent, mix them evenly, dry and sieve to obtain composite powder raw material; S2. The composite powder is granulated to obtain granulated powder with a particle size of 0.1μm to 150μm; S3. The granulated powder is sintered at a low temperature of 900℃~1600℃, which is higher than the softening point of glass and lower than the sintering temperature of ceramic powder. After sintering, secondary ceramic particles are obtained. The ceramic powder has a particle size range of 10 nm to 10 μm, the glass powder has a particle size range of 100 nm to 50 μm, the sintering aid powder has a particle size range of 10 nm to 10 μm, and the pore-forming agent has a particle size range of 0.1 to 50 μm; the pore-forming agent includes one or more of polystyrene, starch, PMMA, walnut shell powder, and plant fiber. The mass fraction of the glass powder is 1% to 35% of the total mass of the glass powder, sintering aid powder, and ceramic powder. In the modeling step, a macroscopic porous structure is designed inside the model, with the size of the macroscopic pores ranging from 100 to 600 μm. The proportion of submicron-sized pores and micron-sized pores in the ceramic matrix is ​​directly determined by controlling the type, size, and content of the pore-forming agent.

2. The preparation method according to claim 1, characterized in that, The ceramic powder is selected from at least one of alumina, zirconium oxide, zirconium oxide-toughened alumina, and silicon nitride.

3. The preparation method according to claim 1, characterized in that, The sintering aid powder is selected from one or more of MgO, ZrO2, CaO, SiO2, Cr2O3, Al2O3, SrO, TiO2, Sc2O3, Y2O3, Li2O, MgF2, and YF3.

4. The preparation method according to claim 1, characterized in that, The glass powder is selected from one or more of the following: high silica glass, soda-lime glass, lead silicate glass, aluminosilicate glass, borosilicate glass, and phosphate glass.

5. The preparation method according to claim 1, characterized in that, The granulated powder contains organic matter. Before the granulated powder is sintered at low temperature in step S3, the granulated powder is further degreased.

6. The preparation method according to claim 5, characterized in that, The degreasing temperature is 300–600°C.

7. A large porous artificial bone, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

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