Porous ceramic with non-uniform fusion structure as well as preparation method and application of porous ceramic

Abstract

The invention discloses a preparation method of porous ceramic with a non-uniform fusion structure, which comprises the following steps: step 1, constructing a fusion function, and determining parameters of the fusion function; 2, preparing a wax pattern negative template; step 3, preparing ceramic slurry; step 4, dipping and freezing; step 5, low-pressure drying; and 6, sintering to obtain the TPMS structure porous ceramic. The invention further discloses the porous ceramic with the non-uniform fusion structure. The invention further discloses application of the porous ceramic with the non-uniform fusion structure in the field of bionic bone scaffolds. According to the method, the fusion function is constructed by fusing the G-shaped function and the TPMS function, so that non-uniform fusion of various hole patterns is realized; the mode of wax negative template freezing casting and indirect forming is adopted, the design freedom degree of a complex structure is reserved, meanwhile, the problems of resolution limitation, shrinkage deformation, supporting difficulty and the like during direct 3D printing of the porous ceramic are solved, and the use effect is good.

Description

Technical Field

[0001] This invention relates to the field of ceramic products technology, and more specifically, to a non-uniform fused porous ceramic, its preparation method and application. Background Technology

[0002] Porous ceramic materials have demonstrated significant value in multiple fields due to their unique structural advantages. These materials possess high specific surface area, excellent permeability, and good mechanical properties. In particular, porous ceramics designed with TPMS structures further enhance the material's functionality and biomimetic properties through their highly interconnected three-dimensional pore structure, providing new possibilities for engineering applications.

[0003] Although the fusion of G-shaped functions and TPMS functions has expanded the structural design space of porous ceramics, achieving precise control over pore size remains challenging, primarily due to three key factors: first, the difficulty in decoupling parameters during function fusion leads to deviations between pore size changes and preset gradients; second, existing implicit modeling methods lack local parameterization control for complex topologies generated by composite functions; and third, the resolution limitations of 3D printing processes restrict the accuracy of achieving micron-level pore size changes, particularly in pore transition regions where unexpected structural distortions are prone to occur. These technical bottlenecks mean that continuous gradient control of pore size remains a challenge.

[0004] Achieving precise control over pore size will greatly expand the application potential of porous ceramics. In the biomedical field, it is possible to construct gradient porous structures ranging from dense to porous, mimicking the mechanical and biological properties of natural bone, providing optimal cell migration channels while maintaining ideal mechanical support strength. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a non-uniform fused porous ceramic and its preparation method and application, which addresses the shortcomings of the above-mentioned prior art. The ceramic has a simple structure and reasonable design. It integrates G-shaped function and TPMS function to construct fusion function and realizes non-uniform fusion of multiple pore types. It adopts a wax negative template cryogenic casting method for indirect forming, which not only retains the design freedom of complex structure, but also solves the problems of resolution limitation, shrinkage deformation and support difficulties faced when directly 3D printing porous ceramics. The application effect is good.

[0006] To solve the above-mentioned technical problems, the technical solution adopted in this application is as follows: The first aspect of the present invention provides a method for preparing a non-uniformly fused porous ceramic structure, characterized by comprising the following steps: Step 1: Construct the fusion function F new (x,y,z), fusion function F new (x,y,z)=α·F G +β·F TPMSα represents the G-shaped function F G The weights, F G Let F represent the G-shaped function, β represent the weights of the TPMS function, and F... TPMS Represent the TPMS function; determine the fusion function F. new The parameters of (x,y,z); Step 2: Prepare the wax-type negative template: based on the fusion function F new (x,y,z) to obtain the surface model, convert the surface model into a triangular mesh model, import the triangular mesh model into the slicing software, generate layer-by-layer slicing files, import the slicing files into the 3D printer, set the printing parameters, and print the wax pattern negative template. Step 3: Prepare a ceramic slurry with a solid content of 25-50 vol.%; Step 4: Immerse the wax pattern negative template in ceramic slurry, freeze the immersed wax pattern negative template, set the freezing parameters, and solidify the ceramic slurry to form a green body structure; Step 5: Dry the green body structure under low pressure, set the sublimation parameters, sublimate and remove the liquid phase in the green body structure, and obtain the wax negative template and the bulk of the ceramic green body. Step 6: Sinter the wax pattern negative template and the ceramic green body, remove the wax pattern negative template, and obtain TPMS structured porous ceramic.

[0007] The above-mentioned method for preparing a non-uniform fused porous ceramic structure is characterized in that: in step one, the G-shaped function F G =G(x,y,z,a), where parameter a is a function that varies with spatial coordinates (x,y,z).

[0008] The above-mentioned method for preparing a non-uniformly fused porous ceramic structure is characterized in that: in step one, the TPMS function F TPMS =T(C,x,y,z), where parameter C is a function that varies with spatial coordinates (x,y,z).

[0009] The above-mentioned method for preparing a non-uniform fused porous ceramic structure is characterized by: parameter a = a0 + a1sin(πx / L)×sin(πy / L)×sin(πz / L), where a0 represents the basic pore size parameter and a1 represents the variation range.

[0010] The above-mentioned method for preparing a non-uniform fused porous ceramic is characterized by: parameter C = C0 + (C1 - C0) × z / L; where C0 represents the pore diameter parameter at z = 0, C1 represents the pore diameter parameter at z = L, and L represents the side length of the porous ceramic.

[0011] The above-mentioned method for preparing a non-uniformly fused porous ceramic structure is characterized by: TPMS function F TPMSThis includes the TPMS Schwarz function, the TPMS Splitp function, or the TPMS Neovius function.

[0012] The above-mentioned method for preparing a non-uniformly fused porous ceramic structure is characterized in that: in step four, the freezing parameters include the freezing rate, and the freezing rate... ,in This represents the difference between the interfacial energy between ice crystals and ceramic particles and the interfacial energy between ice crystals and the solvent. This represents the average distance between ceramic particles in the liquid phase. This represents the viscosity of the liquid phase at 0℃, and r represents the radius of the ceramic particles. This represents the correction factor.

[0013] The above-mentioned method for preparing a non-uniform fused porous ceramic is characterized by: adding a dispersant with a solute mass fraction of 1% and a binder with a mass fraction of 2% to a deionized aqueous solution, and preparing a slurry with a solid content of 25~50 vol.% with alumina powder with a particle size of about 1.0 µm; stirring the slurry on a temperature-controlled magnetic stirrer for 0.5 h, and then ball milling it on a roller ball mill for 24 h to obtain a ceramic slurry.

[0014] A second aspect of the present invention provides a non-uniformly fused porous ceramic, characterized in that it is prepared by any one of the preparation methods described above.

[0015] A third aspect of this invention provides an application of a non-uniformly fused porous ceramic in the field of biomimetic bone scaffolds, the application comprising the following steps: Step 11: Divide the target bionic bone scaffold into multiple bone segments according to the pore size distribution, and determine whether the pore size distribution of the bone segments is a gradient fusion structure. If yes, proceed to step 13; otherwise, proceed to step 12. Step 12: Construct the hole-type transition function F new1 (x,y,z), F new1 (x,y,z)=α1·G(a1,x,y,z)+β1·T(C1,x,y,z), where G(a1,x,y,z) represents the orifice transition G-shape function, α1 represents the weight of the orifice transition G-shape function, T(C1,x,y,z) represents the orifice transition TPMS function, and β1 represents the weight of the orifice transition TPMS function; parameter a1 or parameter C1 is a function related to the coordinates; determine the orifice transition function F. new1 The parameters of (x,y,z); Step 13: Construct the gradient fusion function F new2 (x,y,z), F new2(x,y,z) = α²·G(a²,x,y,z) + β²·T(C²,x,y,z), where G(a²,x,y,z) represents the gradient fusion G-shape function, α² represents the weights of the gradient fusion G-shape function, T(C²,x,y,z) represents the gradient fusion TPMS function, and β² represents the weights of the gradient fusion TPMS function; parameters a and C are functions related to the coordinates; the gradient fusion function F is determined. new2 The parameters of (x,y,z); Step 14: Combine bone segment functions in space; Step 15: Prepare a wax-type negative template based on the bone segment function: Step 16: Prepare a ceramic slurry with a solid content of 25~50 vol.%; Step 17: Immerse the wax pattern negative template in ceramic slurry, freeze the immersed wax pattern negative template, set the freezing parameters, and solidify the ceramic slurry to form a green body structure; Step 18: Dry the green body structure under low pressure, set the sublimation parameters, sublimate and remove the liquid phase in the green body structure, and obtain the wax negative template and the ceramic green body in bulk. Step 19: Sinter the wax pattern negative template and the ceramic green body, remove the wax pattern negative template, and obtain the target biomimetic bone scaffold.

[0016] This application has the following advantages compared with the prior art: 1. This application has a simple structure, reasonable design, and is easy to implement and use.

[0017] 2. The wax negative template process used in this application effectively solves the technical bottlenecks faced by direct 3D printing of porous ceramics. It retains the design freedom of 3D printing technology for complex geometric structures, avoids the problems of resolution limitation, shrinkage deformation and support difficulties that exist when directly printing ceramic materials, and realizes the preparation of complex non-uniform fused porous ceramics through indirect forming.

[0018] 3. This application uses cryogenic casting technology. By adjusting the freezing rate, the size and distribution of ice crystals can be accurately controlled, resulting in a pore structure with better connectivity and regularity.

[0019] 4. This application integrates the G-shaped function and the TPMS function to construct a fusion function, thereby achieving non-uniform fusion of various pore types. This can form a dense structure in the high-stress region of the bionic bone scaffold to enhance mechanical strength, and a loose structure in the low-stress region of the bionic bone scaffold to promote cell growth and nutrient transport, thus taking into account both mechanical support and biological characteristics.

[0020] In summary, this application integrates the G-shaped function and the TPMS function to construct a fusion function, achieving non-uniform fusion of various hole types; it adopts a wax negative template cryogenic casting method for indirect forming, which not only retains the design freedom of complex structures, but also solves the problems of resolution limitations, shrinkage deformation and support difficulties faced when directly 3D printing porous ceramics, resulting in good performance.

[0021] The technical solution of this application will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0022] Figure 1 This is a flowchart of the preparation method of the present invention.

[0023] Figure 2 This is a schematic diagram of the structure of the porous ceramic in Embodiment 1 of the present invention.

[0024] Figure 3 This is a schematic diagram of the porous ceramic structure in Embodiment 2 of the present invention.

[0025] Figure 4 This is a schematic diagram of the porous ceramic structure in Embodiment 3 of the present invention.

[0026] Figure 5 This is a flowchart illustrating the method used in applying the present invention.

[0027] Figure 6 This is a schematic diagram of the pore transition structure of the porous ceramic in Embodiment 5 of the present invention. Figure 7 This is a schematic diagram of the gradient fusion structure of porous ceramics in Embodiment 5 of the present invention. Detailed Implementation

[0028] The present application will now be described in further detail with reference to the accompanying drawings and embodiments thereof.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0033] Example 1 like Figures 1 to 2 As shown, the first aspect of this application provides a method for preparing a non-uniformly fused porous ceramic structure, comprising the following steps: Step 1: Construct the fusion function F new (x,y,z), fusion function F new (x,y,z)=α·F G +β·F TPMS α represents the G-shaped function F G The weights, F G Let F represent the G-shaped function, β represent the weights of the TPMS function, and F... TPMS Represent the TPMS function; determine the fusion function F. new The parameters of (x,y,z).

[0034] Among them, F TPMS =T(C,x,y,z),F G =G(a,x,y,z). The fusion function F newThe parameters of (x, y, z) refer to the range of values ​​for the spatial coordinates x, y, and z, the ratio of the weights α and β, the parameter a, and the parameter C. The range of values ​​for the spatial coordinates x, y, and z determines the macroscopic geometric dimensions of the porous ceramic; for example, x = y = z, z ∈ [0, L], where L represents the side length of the porous ceramic. The parameter a determines the pore size, and the parameter C determines the pore diameter. The ratio of the weights α and β controls the overall contribution ratio of the two functions, determining the pore distribution. By determining the range of values, the structure of the porous ceramic becomes controllable.

[0035] In this embodiment, the weights α and β are constants, the parameter a is a constant, and the parameter C is a function that varies linearly with the spatial coordinates (x, y, z).

[0036] In one possible embodiment, T(C,x,y,z) = cos(x) + cos(y) + cos(z) + C, where T(C,x,y,z) represents the TPMS Schwarz function, and the parameter C is a function that varies linearly with the spatial coordinate z. G(a,x,y,z) = sin(ax)cos(ay) + sin(ay)cos(az) + sin(az)cos(ay).

[0037] In the TPMS structure, the value of parameter C directly affects the morphology and porosity characteristics of the surface model. C = C0 + (C1 - C0) × z / L; where C0 represents the pore diameter parameter at z = 0, and C1 represents the pore diameter parameter at z = L; as the z value increases, the C value increases linearly with the z value, and the pore diameter increases from small to large. Mathematically, the original TPMS surface is defined as an isosurface where the function value is equal to 0, i.e., F... TPMS =0. C controls the offset of the surface. As the value of C changes, the position of the isosurface will shift relative to the original TPMS surface. C=0: Represents the standard original TPMS surface; C>0: The surface will shrink inwards towards the original TPMS surface, reducing solid material, leading to increased porosity and larger pore size; in the extreme case where C approaches the upper limit, the structure may become an interconnected rod-like or plate-like network. C<0: The surface will expand outwards towards the original TPMS surface, increasing solid material, leading to decreased porosity and smaller pore size. In the extreme case where C approaches the lower limit, the pores may completely close, and the structure becomes solid.

[0038] like Figure 2As shown, the generated structure exhibits a coexistence of lamellar pores and gradually changing circular pores. The region dominated by the G-shape function (i.e., areas with high G-shape function values) presents original periodic lamellar pores with flat, interconnected channels, providing a high specific surface area suitable for cell attachment. The region dominated by the TPMS Schwarz function (i.e., areas with high TPMS Schwarz function values) presents gradually changing circular pores, enhancing permeability and facilitating nutrient transport. In the transition zone, where parameter C approaches its minimum value (an extreme case), the circular pores completely close, and the transition zone becomes solid. By continuously varying parameter C, the pore shape is driven to change with spatial coordinates, achieving a smooth transition from lamellar pores to circular pores, resulting in non-uniform fusion. This approach is suitable for simulating the transitional structure from cortical to cancellous bone in biomimetic bone scaffolds, such as the metaphysis of long bones, especially the transition zone of the metaphysis.

[0039] Adjusting the G-shape function F G The weight α of the function, or the weight β of the TPMS function, causes the transition region to shift. For example, increasing the weight α shifts the transition region towards the region dominated by the G-shaped function, increasing the proportion of lamellar holes; increasing the weight β shifts the transition region towards the region dominated by the TPMS Schwarz function, increasing the proportion of circular holes. The G-shaped function and the TPMS Schwarz function share the same spatial coordinates (x, y, z), and through the superposition of function values, local structural deformation is achieved under the same coordinates.

[0040] It should be noted that the TPMS function T(C,x,y,z) can also use other TPMS functions, such as the TPMSSplitp function or the TPMS Neovius function.

[0041] Step 2: Prepare the wax-type negative template: based on the fusion function F new The surface model is obtained by (x,y,z). The surface model is converted into a triangular mesh model. The triangular mesh model is imported into the slicing software to generate layer-by-layer slicing files. The slicing files are imported into the 3D printer, the printing parameters are set, and the wax pattern negative template is printed.

[0042] A 3D model of a non-uniform fusion structure is constructed based on implicit modeling software, and a fusion function F is generated using implicit modeling. newA surface model (x, y, z) is generated. This surface model is then converted into a triangular mesh model. The mesh model is scaled or trimmed according to the 3D printer's forming size and precision requirements. Appropriate layer thickness, printing speed, and exposure time are set to meet printing resolution limitations. After adjustments, the optimized mesh model is imported into slicing software to generate layer-by-layer slicing files. Suitable printing parameters are set to ensure the minimum wall thickness meets printing requirements. Using 3D printing technology and a special wax model from 3D Systems (USA) used for lost-wax casting, a corresponding wax pattern negative template is created by layer-by-layer deposition.

[0043] The process of using a wax negative template effectively solves the technical bottlenecks faced by direct 3D printing of porous ceramics. It retains the design freedom of 3D printing technology for complex geometric structures, but cleverly avoids the problems of resolution limitations, shrinkage deformation and support difficulties that exist when directly printing ceramic materials. It realizes the preparation of complex non-uniform fused porous ceramics through indirect molding.

[0044] Step 3: Prepare a ceramic slurry with a solid content of 25~50 vol.%.

[0045] In a deionized aqueous solution, a dispersant with a solute mass fraction of 1% and a binder with a mass fraction of 2% were added, and alumina powder with a particle size of about 1.0µm was prepared to form a slurry with a solid content of 25~50 vol.%. The slurry was stirred on a temperature-controlled magnetic stirrer for 0.5h, and then ball-milled on a roller ball mill for 24h to obtain a ceramic slurry.

[0046] The dispersant is 1% polyacrylamide or 1% sodium polyacrylate, and the binder is carboxymethyl cellulose.

[0047] Step 4: Immerse the wax pattern negative template in the ceramic slurry, freeze the immersed wax pattern negative template, set the freezing parameters, and solidify the ceramic slurry to form a green body structure.

[0048] In one possible embodiment, a wax-type negative template is immersed in a ceramic slurry with a solid content of 25 vol.%, placed in a cryogenic mold, with the top and bottom of the mold insulated and the bottom serving as a cold source to ensure directional freezing of the ceramic slurry from bottom to top. Cryogenic casting technology provides an effective means of porosity control for porous ceramics by precisely controlling the growth behavior of ice crystals. Utilizing the directional growth characteristics of ice crystals during unidirectional freezing, highly oriented through-hole structures can be directly formed. By adjusting the freezing rate, the size and distribution of ice crystals can be accurately controlled. Compared to traditional pore-forming methods, the resulting pore structure exhibits better connectivity and regularity.

[0049] Freezing parameters include freezing rate, freezing rate ,in This represents the difference between the interfacial energy between ice crystals and ceramic particles and the interfacial energy between ice crystals and the solvent. This represents the average distance between ceramic particles in the liquid phase. This represents the viscosity of the liquid phase at 0℃, and r represents the radius of the ceramic particles. This represents the correction factor.

[0050] During the freezing process, when the freezing rate is During this process, ice crystals exert a repulsive force on ceramic particles in the ceramic slurry, causing them to move into the space of adjacent solidified phases for rearrangement, ultimately resulting in a green body structure where a waxy negative template and a porous ceramic structure coexist. For example, considering the side of the growing ice crystals as a plane, taking... =0.1J / m 2 , =10nm, =1.793 mPa·s (viscosity of the solvent at 0°C), therefore, when the radius r of the ceramic particles is 0.1~2 μm, the freezing rate is... The range is 1.872×10⁶ to 9.36×10⁴ μm / s.

[0051] In one possible embodiment, during the freezing stage, the temperature is controlled between -30°C and -10°C, and the freezing is carried out for 6 hours, followed by a phased temperature increase in increments of 5°C.

[0052] The temperature is gradually increased at fixed intervals of 5℃, with the specific temperature increase sequence being: -30℃, -25℃, -20℃, -15℃, and -10℃. Each temperature plateau needs to be maintained for a certain period of time to ensure that the corresponding sublimation process can be completed at each temperature plateau.

[0053] Step 5: Dry the green body structure under low pressure, set the sublimation parameters, sublimate and remove the liquid phase in the green body structure, and obtain the wax negative template and the bulk of the ceramic green body. Under standard atmospheric pressure, the sublimation rate of ice is slow, and the boiling point of water is high, which is not conducive to the drying process. Reducing the pressure can lower the boiling point of water, making ice crystals easier to sublimate. During the drying stage, the pressure is gradually reduced within the range of 100 Pa to 1 Pa, and the temperature is controlled between 0 °C and 10 °C. Drying is carried out for 10 to 12 hours to sublimate and remove the liquid phase in the green embryo structure.

[0054] Step 6: Sinter the wax pattern negative template and the ceramic green body, remove the wax pattern negative template, and obtain TPMS structured porous ceramic.

[0055] Sintering refers to the densification process under high-temperature conditions, characterized by reduced surface density, crystal growth, grain boundary formation, decreased porosity, and improved mechanical properties. Excessive heating rate or excessively high sintering temperature can cause the shrinkage rate of porous ceramics to decrease too rapidly, leading to the closure or disappearance of some pores. Conversely, excessively low sintering temperatures result in porous ceramic structures with low strength. During this stage, grain growth and grain boundary movement gradually lead to densification of the green body. In one possible embodiment, using a KSL-1700X box-type resistance furnace as an example, when sintering the wax mold negative template and the ceramic green body, the sintering temperature is 600℃, the heating rate from room temperature to 200℃ is 2℃ / min, the heating rate from 200℃ to 600℃ is 1℃ / min, and the holding time at 600℃ is 1~2 hours.

[0056] Example 2 Unlike Example 1, in this example, the weights α and β are constants, parameter a is a function that varies with spatial coordinates (x, y, z), and parameter C is a constant.

[0057] In one possible embodiment, F new (x,y,z)=α·F G +β·F TPMS TPMS function F TPMS =T(C,x,y,z), G-shaped function F G =G(a,x,y,z), where weights α and β are constants, G(a,x,y,z)=sin(ax)cos(ay)+sin(ay)cos(az)+sin(az)cos(ay), a=a0+a1sin(πx / L)×sin(πy / L)×sin(πz / L), where a0 represents the basic pore size parameter and a1 represents the variation range. The TPMS function T(C,x,y,z)=cos(x)+cos(y)+cos(z)+C, where T(C,x,y,z) represents the TPMS Schwarz.

[0058] In a G-shaped structure, the parameter 'a' varies with spatial coordinates (x, y, z), giving the G-shaped structure dynamically adjustable geometric characteristics. Specifically, the pore size and distribution of the G-shaped structure change periodically with position. When a = a0 + a1sin(πx / L) × sin(πy / L) × sin(πz / L), the larger the parameter 'a', the higher the frequency of the trigonometric function, resulting in smaller pore spacing and a denser structure. In the extreme case where the parameter 'a' approaches its upper limit, the lamellar pores may completely close, and the structure becomes solid.

[0059] like Figure 3As shown, in the generated structure, periodic lamellar pores and uniform circular pores coexist. The region dominated by the G-shaped function presents periodic lamellar pores, while the region dominated by the TPMS Schwarz function presents uniform circular pores, thus forming a pore-type transitional fusion structure. This structure is suitable for simulating the transitional structure from cortical bone to cancellous bone in a biomimetic bone scaffold, such as the metaphysis of long bones, especially the transition zone of the metaphysis.

[0060] Example 3 Unlike Embodiment 1 and Embodiment 2, in this embodiment, the weights α and β are constants, the parameter a is a function of spatial coordinates (x,y,z), and the parameter C is also a function of spatial coordinates (x,y,z).

[0061] In one possible embodiment, F new (x,y,z)=α·F G +β·F TPMS TPMS function F TPMS =T(C,x,y,z), G-shaped function F G =G(a,x,y,z), where weights α and β are constants, G(a,x,y,z)=sin(ax)cos(ay)+sin(ay)cos(az)+sin(az)cos(ay), and the TPMS function T(C,x,y,z)=cos(x)+cos(y)+cos(z)+C, where T(C,x,y,z) represents the TPMS Schwarz. Parameter a=a0+a1sin(πx / L)×sin(πy / L)×sin(πz / L), where a0 represents the basic pore size parameter, and a1 represents the variation range. Parameter C=C0+(C1-C0)×z / L; where C0 represents the pore diameter parameter at z=0, and C1 represents the pore diameter parameter at z=L.

[0062] When both parameters a and C are functions of spatial coordinates, the pore diameters of the sheet-like holes and the circular holes will change simultaneously with their spatial positions, forming a more complex gradient fusion structure.

[0063] like Figure 4 As shown, in the generated structure, periodic lamellar pores and gradually changing circular pores coexist. The diameter of the lamellar pores gradually increases from left to right, and the diameter of the circular pores gradually increases from left to right. The overall pore diameter layout presents a gradual pattern in space, which is used to simulate the transition zone inside cancellous bone.

[0064] Example 4 A second aspect of this application provides a non-uniformly fused porous ceramic prepared according to the above preparation method.

[0065] Example 5 like Figure 5As shown, a third aspect of this application provides an application of porous ceramic with a non-uniform fusion structure as described above in the field of biomimetic bone scaffolds, the application comprising the following steps: Step 11: Divide the target bionic bone scaffold into multiple bone segments according to the pore size distribution, and determine whether the pore size distribution of the bone segments is a gradient fusion structure. If yes, proceed to step 13; otherwise, proceed to step 12. Step 12: Construct the hole-type transition function F new1 (x,y,z), F new1 (x,y,z)=α1·G(a1,x,y,z)+β1·T(C1,x,y,z), where G(a1,x,y,z) represents the orifice transition G-shape function, α1 represents the weight of the orifice transition G-shape function, T(C1,x,y,z) represents the orifice transition TPMS function, and β1 represents the weight of the orifice transition TPMS function; parameter a1 or parameter C1 is a function related to the coordinates; determine the orifice transition function F. new1 The parameters of (x,y,z); Step 13: Construct the gradient fusion function F new2 (x,y,z), F new2 (x,y,z) = α²·G(a²,x,y,z) + β²·T(C²,x,y,z), where G(a²,x,y,z) represents the gradient fusion G-shape function, α² represents the weights of the gradient fusion G-shape function, T(C²,x,y,z) represents the gradient fusion TPMS function, and β² represents the weights of the gradient fusion TPMS function; parameters a and C are functions related to the coordinates; the gradient fusion function F is determined. new2 The parameters of (x,y,z); Step 14: Combine bone segment functions in space; Step 15: Prepare a wax-pattern negative template based on the bone segment function. Wax-pattern negative template technology can accurately replicate complex three-dimensional porous structures through 3D printing, providing a high-fidelity molding template for porous ceramic fabrication. This indirect molding method effectively avoids common problems encountered when directly 3D printing ceramic materials, while retaining the design freedom for complex geometries. The easy removal of wax materials simplifies the subsequent demolding process, ensuring that the final product fully retains the designed porous features, making it suitable for preparing porous ceramics with non-uniform fusion structures.

[0066] Step 16: Prepare a ceramic slurry with a solid content of 25~50 vol.%; Step 17: Immerse the wax pattern negative template in ceramic slurry, then freeze the wax pattern negative template, setting the freezing parameters to solidify the ceramic slurry and form a green structure. Cryocasting technology achieves directional growth of ice crystals through precise control of freezing parameters, resulting in a highly oriented and well-connected pore structure. By adjusting parameters such as the freezing rate, this technology can accurately control the size and distribution of ice crystals, thereby obtaining a regular pore network with uniform pore size and smooth pore walls.

[0067] Step 18: Dry the green body structure under low pressure, set the sublimation parameters, sublimate and remove the liquid phase in the green body structure, and obtain the wax negative template and the ceramic green body in bulk. Step 19: Sinter the wax pattern negative template and the ceramic green body, remove the wax pattern negative template, and obtain the target biomimetic bone scaffold.

[0068] like Figure 6 and Figure 7 As shown, the biomimetic bone scaffold of this application, by fusing the G-shaped function and the TPMS function, can achieve pore transition structures and gradient fusion structures. It can be used to construct different bone segments of the same bone, as well as different bone structures. It is suitable for natural bone structures with complex pore gradient changes, such as the metaphysis of long bones, providing an ideal biomimetic replacement solution for bone defect repair.

[0069] Specifically, Figure 6 It features a transitional hole structure with gradient lamellar holes and regular circular holes. Figure 7 As a gradient fusion structure, it features gradient lamellar pores and gradient circular pores, achieving continuous gradient changes in pore size and morphology. It can provide sufficient mechanical support in the high-stress areas of the biomimetic bone scaffold, while forming a loose porous structure in the low-stress areas of the biomimetic bone scaffold to promote cell migration, nutrient transport, and vascularization. It can match the pore distribution and mechanical properties of different bone segments, simulating the mechanical properties and biological characteristics of natural bone.

[0070] The above description is merely an embodiment of this application and does not constitute any limitation on this application. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of this application shall still fall within the protection scope of the technical solution of this application.

Claims

1. A method for preparing a non-uniformly fused porous ceramic, characterized in that: Includes the following steps: Step 1: Construct the fusion function F new (x,y,z), fusion function F new (x,y,z)=α·F G +β·F TPMS α represents the G-shaped function F G The weights, F G Let F represent the G-shaped function, β represent the weights of the TPMS function, and F... TPMS Represent the TPMS function; determine the fusion function F. new The parameters of (x,y,z); Step 2: Prepare the wax-type negative template: based on the fusion function F new (x,y,z) to obtain the surface model, convert the surface model into a triangular mesh model, import the triangular mesh model into the slicing software, generate layer-by-layer slicing files, import the slicing files into the 3D printer, set the printing parameters, and print the wax pattern negative template. Step 3: Prepare a ceramic slurry with a solid content of 25-50 vol.%; Step 4: Immerse the wax pattern negative template in ceramic slurry, freeze the immersed wax pattern negative template, set the freezing parameters, and solidify the ceramic slurry to form a green body structure; Step 5: Dry the green body structure under low pressure, set the sublimation parameters, sublimate and remove the liquid phase in the green body structure, and obtain the wax negative template and the bulk of the ceramic green body. Step 6: Sinter the wax pattern negative template and the ceramic green body, remove the wax pattern negative template, and obtain TPMS structured porous ceramic.

2. The method for preparing a non-uniformly fused porous ceramic according to claim 1, characterized in that: In step one, the G-shaped function F G =G(x,y,z,a), where parameter a is a function that varies with spatial coordinates (x,y,z).

3. A method for preparing a non-uniformly fused porous ceramic according to claim 1 or 2, characterized in that: Step 1 TPMS function F TPMS =T(C,x,y,z), where parameter C is a function that varies with spatial coordinates (x,y,z).

4. The method for preparing a non-uniformly fused porous ceramic according to claim 2, characterized in that: The parameter a = a0 + a1sin(πx / L)×sin(πy / L)×sin(πz / L), where a0 represents the basic pore size parameter and a1 represents the variation range.

5. The method for preparing a non-uniformly fused porous ceramic according to claim 3, characterized in that: The parameter C = C0 + (C1 - C0) × z / L; where C0 represents the pore diameter parameter at z = 0, C1 represents the pore diameter parameter at z = L, and L represents the side length of the porous ceramic.

6. The method for preparing a non-uniformly fused porous ceramic according to claim 1, characterized in that: TPMS function F TPMS This includes the TPMS Schwarz function, the TPMS Splitp function, or the TPMS Neovius function.

7. The method for preparing a non-uniformly fused porous ceramic according to claim 1, characterized in that: In step four, the freezing parameters include the freezing rate. ,in This represents the difference between the interfacial energy between ice crystals and ceramic particles and the interfacial energy between ice crystals and the solvent. This represents the average distance between ceramic particles in the liquid phase. This represents the viscosity of the liquid phase at 0℃, and r represents the radius of the ceramic particles. This represents the correction factor.

8. The method for preparing a non-uniformly fused porous ceramic according to claim 1, characterized in that: In a deionized aqueous solution, a dispersant with a solute mass fraction of 1% and a binder with a mass fraction of 2% were added, and alumina powder with a particle size of about 1.0µm was prepared to form a slurry with a solid content of 25~50 vol.%. The slurry was stirred on a temperature-controlled magnetic stirrer for 0.5h, and then ball-milled on a roller ball mill for 24h to obtain a ceramic slurry.

9. A non-uniformly fused porous ceramic, characterized in that: It is prepared by the method described in any one of claims 1 to 8.

10. The application of the non-uniform fused porous ceramic structure according to claim 9 in the field of biomimetic bone scaffolds, the application comprising the following steps: Step 11: Divide the target bionic bone scaffold into multiple bone segments according to the pore size distribution, and determine whether the pore size distribution of the bone segments is a gradient fusion structure. If yes, proceed to step 13; otherwise, proceed to step 12. Step 12: Construct the hole-type transition function F new1 (x,y,z), F new1 (x,y,z)=α1·G(a1,x,y,z)+β1·T(C1,x,y,z), where G(a1,x,y,z) represents the orifice transition G-shape function, α1 represents the weight of the orifice transition G-shape function, T(C1,x,y,z) represents the orifice transition TPMS function, and β1 represents the weight of the orifice transition TPMS function; parameter a1 or parameter C1 is a function related to the coordinates; determine the orifice transition function F. new1 The parameters of (x,y,z); Step 13: Construct the gradient fusion function F new2 (x,y,z), F new2 (x,y,z) = α²·G(a²,x,y,z) + β²·T(C²,x,y,z), where G(a²,x,y,z) represents the gradient fusion G-shape function, α² represents the weights of the gradient fusion G-shape function, T(C²,x,y,z) represents the gradient fusion TPMS function, and β² represents the weights of the gradient fusion TPMS function; parameters a and C are functions related to the coordinates; the gradient fusion function F is determined. new2 The parameters of (x,y,z); Step 14: Combine bone segment functions in space; Step 15: Prepare a wax-type negative template based on the bone segment function: Step 16: Prepare a ceramic slurry with a solid content of 25~50 vol.%; Step 17: Immerse the wax pattern negative template in ceramic slurry, freeze the immersed wax pattern negative template, set the freezing parameters, and solidify the ceramic slurry to form a green body structure; Step 18: Dry the green body structure under low pressure, set the sublimation parameters, sublimate and remove the liquid phase in the green body structure, and obtain the wax negative template and the ceramic green body in bulk. Step 19: Sinter the wax pattern negative template and the ceramic green body, remove the wax pattern negative template, and obtain the target biomimetic bone scaffold.

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