Biomedical ceramic and method for preparing the same

Abstract

This invention relates to the field of biomedical materials technology, specifically to a biomedical ceramic and its preparation method, comprising a base phase and a doped phase. The base phase consists of hydroxyapatite and β-tricalcium phosphate, and the doped phase consists of yttrium oxide and silicon oxide. The mass ratio of hydroxyapatite to β-tricalcium phosphate is 10:90 to 70:30. The amount of yttrium oxide added is 0.1 to 4 parts by weight of the total mass of the base phase, and the amount of silicon oxide added is 0.1 to 6 parts by weight of the total mass of the base phase. This invention, through the system design of a two-phase base ceramic and a two-oxide doped system, compensates for the performance defects of single bioceramics at the raw material level, enabling the material to possess stable mechanical properties, a suitable degradation rate, and excellent bioactivity, thus meeting the physiological needs of human bone tissue repair. Furthermore, this invention employs a specific powder pretreatment process, which can effectively remove impurities from the raw materials, improve the purity and mixing uniformity of the raw materials, and lay a good foundation for subsequent molding and sintering.

Description

Technical Field

[0001] This invention relates to the field of biomedical materials technology, specifically to a biomedical ceramic and its preparation method. Background Technology

[0002] Biomedical ceramics are core materials in the field of bone tissue repair and replacement, and are widely used in clinical orthopedics and dental restoration. Hydroxyapatite and β-tricalcium phosphate are the mainstream base materials for current bioactive ceramics. Both have good biocompatibility and osteoconductivity, making them ideal raw materials that fit the human bone tissue environment. However, most existing biomedical ceramics are prepared using a single raw material, making it difficult to balance mechanical properties, degradation rate and bioactivity, and thus failing to meet the needs of complex clinical scenarios.

[0003] Existing composite ceramic systems suffer from problems such as unreasonable component matching and single doping system, making it difficult to achieve synergistic optimization of material microstructure and macroscopic properties. At the same time, traditional preparation processes often use petroleum-based binders, which are not only environmentally unfriendly, but also prone to causing cracking of the green body and residual impurities during debinding, affecting material purity and safety. The molding process often relies on cold isostatic pressing, which results in low molding accuracy and poor green body uniformity, making it difficult to prepare complex structure products.

[0004] Furthermore, existing processes mostly employ a single heating regime to complete debinding and sintering, which easily leads to uneven internal porosity, insufficient density, and large fluctuations in mechanical properties. Although some technologies have attempted to optimize components and processes, they have failed to form a systematic preparation scheme, resulting in poor matching between material degradation rate and bone tissue growth, and difficulty in simultaneously achieving bioactivity and mechanical stability. There is an urgent need for a biomedical ceramic with balanced performance, stable process, and strong adaptability, as well as its preparation method, to solve the technical problems of existing technologies. Summary of the Invention

[0005] The primary objective of this invention is to provide a biomedical ceramic and its preparation method.

[0006] A further objective of this invention is to provide a biomedical ceramic comprising a base phase and a doped phase, wherein the base phase is hydroxyapatite and β-tricalcium phosphate, and the doped phase is yttrium oxide and silicon oxide; the mass ratio of hydroxyapatite to β-tricalcium phosphate is 10:90 to 70:30, the amount of yttrium oxide added is 0.1 to 4 parts by weight of the total mass of the base phase, and the amount of silicon oxide added is 0.1 to 6 parts by weight of the total mass of the base phase.

[0007] Preferably, the hydroxyapatite powder has a particle size of 50 nm to 100 nm, the β-tricalcium phosphate powder has a particle size of 80 nm to 150 nm, the yttrium oxide powder has a particle size of 30 nm to 50 nm, and the silicon oxide powder has a particle size of 40 nm to 80 nm.

[0008] Preferably, the raw materials for preparation also include a binder and milling media, wherein the binder is palm stearin and polyethylene, and the milling media is anhydrous ethanol.

[0009] A method for preparing biomedical ceramics includes the following steps: raw material preparation, raw material pretreatment, mixing and ball milling, injection molding, gradient debinding, gradient sintering, and post-treatment.

[0010] Preferably, the mass ratio of palm stearin to polyethylene in the raw material preparation is 1:1 to 2.5:1, the total amount of binder added is 10 to 25 parts by weight of the total raw material mass, and the amount of anhydrous ethanol added is 15 to 25 parts by weight of the total raw material mass.

[0011] Preferably, the raw material pretreatment involves soaking hydroxyapatite, tricalcium β-phosphate, yttrium oxide, and silicon dioxide in 0.5 mol / L dilute hydrochloric acid solution for 1.5 hours, rinsing with deionized water until the pH reaches 7, and drying at 70°C to constant weight; and pulverizing palm stearin and polyethylene to a particle size of 40 μm.

[0012] Preferably, the mixing ball mill uses a planetary ball mill with a ball-to-material ratio of 10:1 to 15:1, a ball milling speed of 200 r / min to 380 r / min, and a ball milling time of 4 to 7 hours.

[0013] Preferably, the injection temperature for injection molding is 150°C to 165°C, the injection pressure is 1.0MPa to 1.2MPa, and the mold temperature is 40°C to 48°C.

[0014] Preferably, the gradient degreasing process employs a two-stage or three-stage heating process. The two-stage process involves raising the temperature from room temperature to 300°C at a heating rate of 2°C / min, holding for 2 hours, then raising it to 500°C at a heating rate of 1°C / min, and holding for 3 hours. The three-stage process involves raising the temperature from room temperature to 200°C at a heating rate of 1.5°C / min, holding for 1 hour, then raising it to 350°C at a heating rate of 2°C / min, holding for 2 hours, then raising it to 550°C at a heating rate of 1°C / min, and holding for 3 hours.

[0015] Preferably, the maximum gradient sintering temperature is 1180℃ to 1280℃, and the holding time is 4 hours to 6 hours; the post-treatment includes grinding and polishing the sintered product, cleaning with deionized water and drying, and it can also undergo biomimetic mineralization treatment by immersing the product in simulated body fluid at 37℃ for 7 days.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention, through the design of a system of two-phase basic ceramics and two oxide doping, makes up for the performance defects of single bioceramics at the raw material level, so that the material has stable mechanical properties, suitable degradation rate and excellent bioactivity, which is suitable for the physiological needs of human bone tissue repair. In addition, this invention adopts a specific powder pretreatment process, which can effectively remove impurities from raw materials, improve the purity of raw materials and the uniformity of mixing, and lay a good foundation for subsequent molding and sintering.

[0017] 2. This invention uses a bio-based binder to replace the traditional petroleum-based binder, which improves the environmental friendliness of the preparation process. Combined with a gradient degreasing process, the binder can be completely removed without damaging the structure of the green body, avoiding cracking, deformation and impurity residue in the green body. The ceramic injection molding process of this invention improves the molding precision of the product and can prepare medical ceramic products with complex structures, thus broadening the application scenarios of the material.

[0018] 3. The gradient sintering process of this invention can precisely control the microstructure of the material, resulting in uniform ceramic density, no internal defects, and stable and reliable mechanical properties. The post-processing can optimize the surface morphology of the material, further improving its biocompatibility and osseointegration ability. The preparation process parameters of this invention have strong adaptability, can stably prepare qualified products within a wide range of proportions, and have high process repeatability and strong industrial feasibility.

[0019] 4. The ceramic products obtained by this invention have a pure phase without impurities, high biocompatibility, a degradation rate that is highly matched with bone tissue growth, and mechanical properties that meet the requirements for clinical use, thus possessing good clinical application value. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] All the following embodiments employ ceramic injection molding combined with gradient sintering. All raw materials used are of industrial-grade medical purity, including hydroxyapatite powder, β-tricalcium phosphate powder, yttrium oxide powder, silica powder, palm stearin, polyethylene, and anhydrous ethanol. Specifically, the hydroxyapatite powder has a particle size of 50-100 nm, the β-tricalcium phosphate powder has a particle size of 80-150 nm, the yttrium oxide powder has a particle size of 30-50 nm, and the silica powder has a particle size of 40-80 nm. The parameters for each embodiment are specific and repeatable. Key process details are also provided to ensure full disclosure, and all operations strictly adhere to biomedical ceramic preparation standards.

[0022] Example 1: Raw material preparation: hydroxyapatite powder, β-tricalcium phosphate powder, palm stearin, polyethylene, and analytical grade anhydrous ethanol. The mass ratio of hydroxyapatite to β-tricalcium phosphate is 40:60, the mass ratio of palm stearin to polyethylene is 2:1, the total amount of binder added is 15 parts by weight of the total raw material mass, and anhydrous ethanol is used as the ball milling medium, with an amount of 20 parts by weight of the total raw material mass.

[0023] Raw material pretreatment: Hydroxyapatite powder and β-tricalcium phosphate powder were soaked in 0.5 mol / L analytical grade dilute hydrochloric acid solution for 1.5 hours to remove surface metal oxide impurities; then rinsed repeatedly with deionized water until pH=7, and dried in a 70℃ forced-air oven to constant weight; palm stearin and polyethylene were pulverized to a particle size of 40 μm to ensure uniform mixing in the subsequent process.

[0024] Mixed ball milling: Add all the pretreated raw materials to a planetary ball mill, and add a preset amount of anhydrous ethanol at the same time. Control the ball-to-material ratio to be 10:1, the ball milling speed to be 300 r / min, and the ball milling time to be 4 hours to obtain a uniform mixed slurry. Place the mixed slurry in a 75℃ forced-air drying oven to dry, remove the anhydrous ethanol, pulverize, and pass through a 100-mesh standard sieve to obtain composite powder.

[0025] Injection molding: The composite powder is added to a semi-automatic injection molding machine, and the injection temperature is set to 160℃, the injection pressure to 1.1MPa, the holding time to 10s, and the mold temperature to 40℃. The green body is obtained by injection molding. The green body is removed from the mold and left to stand naturally at room temperature for 24 hours to remove residual stress on the surface.

[0026] Gradient degreasing: The green body is placed in a degreasing furnace and a two-stage gradient degreasing process is adopted: the first stage is to raise the temperature from room temperature to 300℃ at a heating rate of 2℃ / min and hold for 2 hours to remove palm stearin; the second stage is to raise the temperature from 300℃ to 500℃ at a heating rate of 1℃ / min and hold for 3 hours to remove polyethylene, and finally obtain a porous green body.

[0027] Gradient sintering: The porous green body is placed in a high-temperature sintering furnace and heated from room temperature to 800°C at a rate of 5°C / min, and held for 1 hour to remove residual impurities; then it is heated to 1200°C at a rate of 3°C / min and held for 4 hours to achieve densification; finally, it is cooled to room temperature at a rate of 2°C / min to obtain the basic composite biomedical ceramic.

[0028] Post-processing: The sintered product is polished with a 400-grit grinding wheel to remove burrs and surface defects. It is then washed three times with deionized water for 10 minutes each time, and then dried in a 60℃ forced-air oven until constant weight is achieved to obtain the finished product.

[0029] Example 2: Raw material preparation: hydroxyapatite powder, β-tricalcium phosphate powder, yttrium oxide powder, palm stearin, polyethylene, and analytical grade anhydrous ethanol. The mass ratio of hydroxyapatite to β-tricalcium phosphate is 40:60. The amount of yttrium oxide added is 1 part by weight of the total mass of the base phase. The mass ratio of palm stearin to polyethylene is 2:1. The total amount of binder added is 15 parts by weight, and the amount of anhydrous ethanol added is 20 parts by weight.

[0030] Raw material pretreatment: The pretreatment methods for hydroxyapatite, β-tricalcium phosphate, palm stearin, and polyethylene are the same as in Example 1; yttrium oxide powder is soaked in 0.5 mol / L analytical grade dilute hydrochloric acid solution for 1.5 hours, rinsed with deionized water until pH=7, dried in a 70℃ forced-air oven to constant weight, and pulverized to a particle size of 30 μm.

[0031] Mixed ball milling: All pretreated raw materials were added to a planetary ball mill, along with anhydrous ethanol. The ball-to-material ratio was controlled at 10:1, the rotation speed at 300 r / min, and the ball milling time at 5 hours. The drying, pulverizing, and sieving steps were the same as in Example 1 to obtain composite powder.

[0032] Injection molding: Set the injection temperature to 155℃, injection pressure to 1.2MPa, holding time to 10s, and mold temperature to 40℃. The remaining operations are the same as in Example 1. Obtain the green body and remove residual stress.

[0033] The gradient degreasing and post-treatment steps are exactly the same as in Example 1; the gradient sintering process is as follows: the temperature is raised from room temperature to 800°C at a rate of 5°C / min and held for 1 hour; then the temperature is raised to 1250°C at a rate of 3°C / min and held for 5 hours; finally, the temperature is lowered to room temperature at a rate of 2°C / min to obtain the finished product.

[0034] Example 3: Raw material preparation: hydroxyapatite powder, β-tricalcium phosphate powder, silica powder, palm stearin, polyethylene, and analytical grade anhydrous ethanol. The mass ratio of hydroxyapatite to β-tricalcium phosphate is 40:60, the amount of silica added is 3 parts by weight of the total mass of the base phase, and the proportions of the remaining raw materials are the same as in Example 1.

[0035] Raw material pretreatment: The pretreatment methods for hydroxyapatite, β-tricalcium phosphate, palm stearin, and polyethylene are the same as in Example 1; the pretreatment method for silica powder is the same as that for yttrium oxide powder in Example 2, and the powder is pulverized to a particle size of 40 μm.

[0036] Ball milling: control the ball-to-material ratio at 10:1, the rotation speed at 350 r / min, and the milling time at 5 hours. The remaining operations are the same as in Example 1. Injection molding: set the injection temperature at 165℃, the injection pressure at 1.0 MPa, the holding time at 12 s, and the mold temperature at 40℃. The remaining operations are the same as in Example 1.

[0037] The gradient degreasing process was the same as in Example 1; the gradient sintering process was as follows: the temperature was raised from room temperature to 800°C at a rate of 5°C / min and held for 1 hour; then the temperature was raised to 1180°C at a rate of 3°C / min and held for 4 hours; finally, the temperature was lowered to room temperature at a rate of 2°C / min; the post-treatment process was the same as in Example 1, and the finished product was obtained.

[0038] Example 4: Raw material preparation: hydroxyapatite powder, β-tricalcium phosphate powder, yttrium oxide powder, silica powder, palm stearin, polyethylene, and analytical grade anhydrous ethanol. The mass ratio of hydroxyapatite to β-tricalcium phosphate is 50:50, the amount of yttrium oxide added is 0.8 parts by weight, and the amount of silica added is 2 parts by weight, both based on the total mass of the base phase; the mass ratio of palm stearin to polyethylene is 1.5:1, the total amount of binder added is 18 parts by weight, and the amount of anhydrous ethanol added is 25 parts by weight.

[0039] Raw material pretreatment, mixing and ball milling, injection molding, gradient debinding, gradient sintering and post-treatment are all performed according to the relevant operations in Examples 1-3. The mixing and ball milling speed is 320 r / min, the ball milling time is 6 hours, the injection temperature is 160℃, the injection pressure is 1.15 MPa, and the gradient sintering holding time is 5 hours to ensure that the entire process can be repeated.

[0040] Example 5: The raw material preparation was exactly the same as in Example 4; the raw material pretreatment method was the same as in Example 1; the ball milling was carried out in a segmented manner, with the ball-to-material ratio controlled at 15:1, the rotation speed at 200 r / min for the first 3 hours, and the rotation speed at 380 r / min for the next 4 hours, for a total ball milling time of 7 hours, and the remaining operations were the same as in Example 1.

[0041] Injection molding: Injection temperature set at 158℃, injection pressure at 1.1MPa, holding time at 13s, and mold temperature at 48℃; gradient degreasing adopts a three-stage process: from room temperature to 200℃, heating rate at 1.5℃ / min, holding for 1 hour; from 200℃ to 350℃, heating rate at 2℃ / min, holding for 2 hours; from 350℃ to 550℃, heating rate at 1℃ / min, holding for 3 hours.

[0042] Gradient sintering: The temperature is increased from room temperature to 700℃ at a rate of 4℃ / min and held for 1 hour; then increased to 1000℃ at a rate of 3℃ / min and held for 1 hour; finally increased to 1280℃ at a rate of 2℃ / min and held for 6 hours, with a cooling rate of 1.5℃ / min; the post-treatment steps are the same as in Example 1, with the addition of surface biomimetic mineralization treatment, i.e., immersing in simulated body fluid at a constant temperature of 37℃ for 7 days to obtain the finished product.

[0043] Example 6: Raw material preparation: The mass ratio of hydroxyapatite to β-tricalcium phosphate is 70:30, the amount of yttrium oxide added is 4 parts by weight, the amount of silicon oxide added is 6 parts by weight, both based on the total mass of the base phase; the mass ratio of palm stearin to polyethylene is 2.5:1, the total amount of binder added is 25 parts by weight, and the amount of anhydrous ethanol added is 25 parts by weight.

[0044] The raw material pretreatment method is the same as in Examples 1-3; the ball milling operation is the same as in Example 5, except that the ball milling time is adjusted to 6.5 hours; the injection molding, gradient degreasing, gradient sintering and post-treatment are all performed in accordance with the relevant operations in Example 5 to ensure that the process parameters match the raw material ratio and obtain the finished product.

[0045] Example 7: Raw material preparation: The mass ratio of hydroxyapatite to β-tricalcium phosphate is 10:90, the amount of yttrium oxide added is 0.1 parts by weight, the amount of silicon oxide added is 0.1 parts by weight, both based on the total mass of the base phase; the mass ratio of palm stearin to polyethylene is 1:1, the total amount of binder added is 10 parts by weight, and the amount of anhydrous ethanol added is 15 parts by weight.

[0046] The raw material pretreatment method is the same as in Examples 1-3; the ball milling operation is the same as in Example 5, except that the ball milling time is adjusted to 4.5 hours; the injection molding is set with an injection temperature of 150℃ and an injection pressure of 1.0MPa, the gradient degreasing adopts a two-stage process, the gradient sintering parameters are adapted to the requirements of low-ratio raw materials, and the post-treatment steps are the same as in Example 5 to obtain the finished product.

[0047] Comparative Example 1: Using only hydroxyapatite powder as the basic raw material, without adding β-tricalcium phosphate, yttrium oxide, and silicon oxide, the remaining raw material ratios and preparation steps are the same as in Example 1, and the finished product is obtained.

[0048] Comparative Example 2: Using only β-tricalcium phosphate powder as the basic raw material, without adding hydroxyapatite, yttrium oxide, or silicon dioxide, the remaining raw material ratios and preparation steps are the same as in Example 1, and the finished product is obtained.

[0049] Comparative Example 3: The mass ratio of hydroxyapatite to β-tricalcium phosphate was 40:60. No yttrium oxide or silicon oxide was added. The remaining raw material ratios and preparation steps were the same as in Example 1, and the finished product was obtained.

[0050] Comparative Example 4: The raw material ratio is the same as in Example 1. Paraffin-polyethylene petroleum-based binder is used instead of palm stearin-polyethylene binder. Acetone is added as an auxiliary degreasing agent during the degreasing process. The remaining preparation steps are the same as in Example 1 to obtain the finished product.

[0051] Comparative Example 5: The raw material ratio is the same as in Example 1. The molding method is cold isostatic pressing, with a pressure of 25 MPa and a holding time of 3 min. The remaining preparation steps are the same as in Example 1, and the finished product is obtained.

[0052] Comparative Example 6: The raw material ratio is the same as in Example 2. Paraffin-polyethylene petroleum-based binder and cold isostatic pressing are used. The pressure is controlled at 25 MPa and the holding time is 3 min. The remaining preparation steps are the same as in Example 2 to obtain the finished product.

[0053] Comparative Example 7: The mass ratio of hydroxyapatite to β-tricalcium phosphate was 85:15, the amount of yttrium oxide added was 5 parts by weight, the amount of binder added was 12 parts by weight, and the other raw materials and preparation steps were the same as in Example 1, to obtain the finished product.

[0054] Performance testing and results analysis: For all the finished products of the embodiments and comparative examples, mechanical properties, physical properties, biocompatibility, degradation properties and phase composition were tested in strict accordance with the relevant standards and conventional testing methods for biomedical ceramics. The testing process was standardized and the test data were true and reliable. The specific test results are as follows.

[0055] Test items and methods: (1) Mechanical properties: According to ISO6474-1:2019 standard, the bending strength and elastic modulus were tested by a universal testing machine; the Vickers hardness was tested by a Vickers hardness tester. Five points were tested for each sample, and the average value was taken as the final result.

[0056] (2) Physical properties: According to ASTM B962-17 standard, the relative density and porosity were tested by Archimedes' water displacement method; the particle size distribution of the composite powder was tested by laser particle size analyzer; and the microstructure of the material was observed by field emission scanning electron microscopy.

[0057] (3) Biocompatibility: In accordance with GB / T16886.5-2017 standard, the cell viability was tested by the MTT method, the bioactivity of the material was evaluated by the simulated body fluid immersion experiment, and the hemolysis rate was tested by the hemolysis experiment.

[0058] (4) Degradation performance: The sample was placed in simulated body fluid and incubated at a constant temperature of 37°C. The simulated body fluid was replaced regularly. The mass loss rate was calculated after 7 days, 14 days, 28 days and 60 days, and the pH value of the simulated body fluid after soaking was tested.

[0059] (5) Phase composition: X-ray diffraction was used to test and compare the phase composition of the material with the standard XRD pattern.

[0060] The test results are shown in Table 1 below: Table 1: Results analysis: Example 1, as the basic composite system, exhibits significantly superior overall performance compared to both single ceramic systems and undoped composite systems, fully demonstrating that the combination of hydroxyapatite and β-tricalcium phosphate can effectively compensate for the performance defects of single ceramic materials. Example 2 significantly improved the mechanical properties of the material through yttrium oxide doping. Example 3 optimized the biocompatibility and degradation performance of the material through silicon oxide doping. Example 4, employing dual doping of yttrium oxide and silicon oxide, achieved a synergistic improvement in mechanical properties, biocompatibility, and degradation performance. Example 5, after optimization of process parameters, achieved optimal overall performance. The wide ratio systems of Examples 6 and 7 all met the preset performance requirements, verifying the rationality and scientific nature of the raw material ratio design of this invention.

[0061] Comparison of the various proportions shows that the overall performance of single ceramic systems, undoped composite systems, products using traditional petroleum-based binders or traditional cold isostatic pressing processes, and products prepared by simple combinations of existing technologies are all lower than those of the embodiments of the present invention; products prepared outside the formulation range of the present invention show a significant decrease in performance.

[0062] Furthermore, the phase composition test results showed that all the finished products of the examples were free of impurities, the phase composition was stable, and the reaction process was reasonable, further proving the feasibility and reliability of the preparation process of the present invention.

[0063] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A biomedical ceramic, characterized in that, It consists of a base phase and a doped phase. The base phase is hydroxyapatite and β-tricalcium phosphate, and the doped phase is yttrium oxide and silicon oxide. The mass ratio of hydroxyapatite to β-tricalcium phosphate is 10:90 to 70:

30. The amount of yttrium oxide added is 0.1 to 4 parts by weight of the total mass of the base phase, and the amount of silicon oxide added is 0.1 to 6 parts by weight of the total mass of the base phase.

2. The biomedical ceramic according to claim 1, characterized in that, The particle size of hydroxyapatite powder is 50 nm to 100 nm, the particle size of β-tricalcium phosphate powder is 80 nm to 150 nm, the particle size of yttrium oxide powder is 30 nm to 50 nm, and the particle size of silicon oxide powder is 40 nm to 80 nm.

3. The biomedical ceramic according to claim 1, characterized in that, The raw materials also include a binder and milling media. The binder is palm stearin and polyethylene, and the milling media is anhydrous ethanol.

4. A method for preparing biomedical ceramics, used to prepare the biomedical ceramics according to any one of claims 1 to 3, characterized in that, The process involves raw material preparation, raw material pretreatment, mixing and ball milling, injection molding, gradient debinding, gradient sintering, and post-treatment.

5. The preparation method according to claim 4, characterized in that, In the raw material preparation, the mass ratio of palm stearin to polyethylene is 1:1 to 2.5:1, the total amount of binder added is 10 to 25 parts by weight of the total raw material mass, and the amount of anhydrous ethanol added is 15 to 25 parts by weight of the total raw material mass.

6. The preparation method according to claim 4, characterized in that, The raw material pretreatment involved soaking hydroxyapatite, β-tricalcium phosphate, yttrium oxide, and silicon dioxide in 0.5 mol / L dilute hydrochloric acid solution for 1.5 hours, rinsing with deionized water until the pH reached 7, and drying at 70°C to constant weight. Palm stearin and polyethylene were pulverized to a particle size of 40 μm.

7. The preparation method according to claim 4, characterized in that, The mixing ball mill uses a planetary ball mill with a ball-to-material ratio of 10:1 to 15:1, a ball milling speed of 200 r / min to 380 r / min, and a ball milling time of 4 to 7 hours.

8. The preparation method according to claim 4, characterized in that, The injection temperature for injection molding is 150℃ to 165℃, the injection pressure is 1.0MPa to 1.2MPa, and the mold temperature is 40℃ to 48℃.

9. The preparation method according to claim 4, characterized in that, The gradient degreasing process employs a two-stage or three-stage heating process. The two-stage process involves raising the temperature from room temperature to 300°C at a rate of 2°C / min, holding for 2 hours, then raising it to 500°C at a rate of 1°C / min, and holding for 3 hours. The three-stage process involves raising the temperature from room temperature to 200°C at a rate of 1.5°C / min, holding for 1 hour, then raising it to 350°C at a rate of 2°C / min, holding for 2 hours, then raising it to 550°C at a rate of 1°C / min, and holding for 3 hours.

10. The preparation method according to claim 4, characterized in that, The maximum temperature for gradient sintering is 1180℃ to 1280℃, and the holding time is 4 to 6 hours. The post-treatment includes grinding and polishing the sintered products, cleaning with deionized water and drying. It can also undergo biomimetic mineralization treatment by immersing the products in simulated body fluid at 37℃ for 7 days.

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