Preparation method of medical composite ceramic material based on zirconium oxide

Abstract

The invention relates to the technical field of medical ceramic materials, in particular to a zirconium oxide-based medical composite ceramic material preparation method, which comprises the following steps: adjusting a target cycle index in response to a slurry mixing state or adjusting spray granulation process parameters in a compensatory manner based on slurry state parameters; based on the characteristics of the green bodies, determining whether the current batch of green bodies have the risk of closed pores, determining an adjusting characteristic point in combination with the change degree of the actual shrinkage rate so as to respond to the adjusting characteristic point to stop sintering heating and add a heat preservation stage, and determining the heat preservation intermediate temperature and the time length of the heat preservation stage; and obtaining a sintered body phase to determine the tetragonal phase zirconia retention rate so as to determine whether a sintering adjustment strategy is matched with the characteristics of the current batch of slurry based on the sintered body performance, and adjusting the intermediate heat preservation temperature of the subsequent sintering process according to the tetragonal phase retention rate deviation in response to the sintered body performance. According to the invention, the performance of the ceramic implant is improved by adjusting the sintering temperature curve based on the zirconium oxide conforming to the powder characteristics.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical ceramic materials, and particularly relates to a preparation method of a medical composite ceramic material based on zirconia. BACKGROUND

[0002] Zirconia ceramics, especially yttrium stabilized tetragonal phase zirconia, have been widely used in medical fields, especially dental restoration (such as dental crown, bridge body) and orthopedic implants (such as femoral head), due to their high strength, high fracture toughness, good wear resistance and excellent biocompatibility. The core toughening mechanism is the stress-induced martensitic phase transformation from tetragonal phase to monoclinic phase, i.e. "phase transformation toughening". However, pure Y-TZP has the risk of low-temperature degradation (LTD), i.e. the metastable tetragonal phase will transform into monoclinic phase when used in a humid environment for a long time, resulting in micro-cracks and performance degradation. In addition, its fracture toughness is still higher than that of human bone, and its bioactivity is insufficient.

[0003] Chinese Patent Publication No. CN109574634A discloses a medical alumina ceramic composite material and a preparation method thereof, which comprises the following steps: uniformly mixing 98-99.75%vol alumina ceramic and 0.25-2%vol graphene, pressing into a green body, and cooling after sintering the green body at 1450-1650°C. The medical alumina ceramic composite material prepared by the method has the advantages of not being easy to age, good wear resistance, bending strength, fracture toughness and biocompatibility. It can be seen that the medical alumina ceramic composite material and the preparation method thereof have the following problems: The composite system added with alumina or other second phase materials introduces heterogeneous phase interfaces, which may become crack sources or affect optical performance or interfere with the phase transformation toughening effect of zirconia. SUMMARY

[0004] Therefore, the present application provides a preparation method of a medical composite ceramic material based on zirconia to overcome the problem of interference with the phase transformation toughening effect of zirconia caused by the introduction of heterogeneous phase interfaces in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides a preparation method of a medical composite ceramic material based on zirconia, which comprises: The slurry is wet ball-milled according to a target number of cycles to obtain a particle size distribution characteristic value of the slurry and an actual slurry viscosity to determine a slurry dispersibility index to determine the mixing state of the slurry; The target number of cycles is adjusted in response to the mixing state of the slurry or the spray granulation process parameters are compensatorily adjusted based on the slurry state parameters; The powder filling characteristic parameters and the initial green body density of the green body are combined with the slurry dispersibility index to determine a dynamic sintering activity index to determine the green body characteristics of the current batch of green body; Another particle size distribution characteristic value of the slurry is used to predict sintering driving force of the green body in the sintering process, to adjust the temperature rising rate of the sintering process, and to dynamically adjust the sintering adjustment strategy of the sintering process based on a dynamic sintering activity index in response to the green body characteristics; The green body characteristics are used to determine whether the sintering process is at risk of coarse grains, to obtain the actual relative density of the green body, and to adjust the temperature stage and sintering temperature of the sintering process; The green body characteristics are used to determine whether the current batch of green body is at risk of closed pores, to determine an adjustment characteristic point in combination with the degree of change in the actual shrinkage rate, to stop the sintering temperature rising and add a holding stage in response to the adjustment characteristic point, and to determine the holding intermediate temperature and the holding stage time length; The phase of the sintered body is obtained to determine the retention rate of tetragonal zirconia, to determine whether the sintering adjustment strategy matches the characteristics of the current batch of slurry based on the performance of the sintered body, and to adjust the intermediate holding temperature of the subsequent sintering process according to the deviation of the tetragonal phase retention rate in response to the performance of the sintered body.

[0006] Further, the slurry in the grinding cavity is sampled and detected to obtain the particle size distribution characteristic value and the actual slurry viscosity of the slurry to determine the slurry dispersibility index; When the slurry dispersibility index is greater than or equal to a first index threshold value, it is determined that the slurry is in a first mixing state, the fineness and fluidity of the slurry meet the requirements, and the current cycle number of the wet ball milling is set as the target cycle number; When the slurry dispersibility index is less than the first index threshold value and greater than or equal to a second index threshold value, it is determined that the slurry is in a second mixing state, and the slurry state has an adjustable deviation, so that compensatory adjustment is made on the subsequent process; When the slurry dispersibility index is less than the second index threshold value, it is determined that the slurry is in a third mixing state, and the slurry state does not meet the requirements, so that the target cycle number of the wet ball milling is increased; The particle size distribution characteristic value of the slurry includes the D90 value and the median particle size D50 value in the particle size distribution of the slurry.

[0007] Further, when the slurry is in the second mixing state, the spray granulation process parameters are adjusted according to the slurry state parameters, which include the viscosity ratio and the fineness ratio; If the actual slurry viscosity is greater than the target slurry viscosity, the solid content of the slurry liquid in the spray granulation is reduced in proportion according to the ratio of the target slurry viscosity to the actual slurry viscosity; If the particle size distribution characteristic value is greater than the target characteristic value, the atomization pressure of the spray granulation is increased according to the ratio of the particle size distribution characteristic value to the target characteristic value.

[0008] Further, the powder filling characteristic parameters and the initial green body density of the green body are obtained to calculate the dynamic sintering activity index to reflect the green body characteristics of the current batch of green body, and the actual tap density of the powder is the powder filling characteristic parameter. When the dynamic sintering activity index exceeds the calibrated index range, it is determined that the current batch of green bodies has intrinsic activity beyond the range and the green body characteristics of the green body microstructure, and the sintering driving force and the densification rate exceed the preset range; When the dynamic sintering activity index is within the calibrated index range, it is determined that the green body characteristics of the current batch of green bodies are within the preset range; When the dynamic sintering activity index is below the calibrated index range, it is determined that the current batch of green bodies has pores due to poor dispersion or poor compaction efficiency, and the sintering resistance is large.

[0009] Further, the sintering driving force coefficient is determined according to the median particle size D50 value; When the sintering driving force coefficient is greater than the driving force warning threshold, it is determined that the current batch of slurry has a driving force risk of too fast densification rate under the current sintering parameters, and the heating rate of the sintering process is adjusted according to the sintering driving force coefficient.

[0010] Further, when the current batch of green bodies has intrinsic activity beyond the range and the green body characteristics of the green body microstructure, the current batch of green bodies has the risk of grain coarsening during the sintering process; The initial volume, initial mass and initial length of the green body are obtained, and the linear shrinkage of the green body in the axial or radial direction is detected to determine the actual relative density; When the actual relative density is greater than the critical relative density, it is determined that the current batch of green bodies is densified to the critical density, and the sintering temperature is reduced to the preset adjustment range according to the maximum controllable temperature adjustment rate, and the temperature is kept for a preset holding time.

[0011] Further, when the sintering resistance of the current batch of green bodies is large, it is determined that the current batch of green bodies has the risk of forming closed pores, and the adjustment feature point is determined according to the change degree of the actual shrinkage rate; The actual shrinkage rate is calculated according to the linear shrinkage, the actual shrinkage rate-sintering actual temperature curve is drawn, and the interval maximum rate of the actual shrinkage rate-sintering actual temperature curve in several preset temperature intervals is obtained; When the actual ratio of the interval maximum rate in the current preset temperature interval to the interval average rate in the last preset temperature interval is greater than the minimum increment threshold, it is determined that the interval maximum rate in the current preset temperature interval meets the significance condition.

[0012] Further, after determining the interval maximum rate that meets the significance condition, the linear fitting slope of the peak point corresponding to the interval maximum rate in the subsequent unit time is calculated, and the shrinkage rate difference of several data points and the previous data point is obtained according to the preset temperature unit, and the actual negative value of the shrinkage rate difference is calculated. The proportion of negative values in several shrinkage rate differences; When the linear fitting slope is less than the slope threshold value and the actual negative value proportion is greater than or equal to the proportion threshold value, it is determined that the peak point corresponding to the interval maximum rate meets the persistence trend, and the dominant diffusion mechanism of the sintering stage corresponding to the current preset temperature interval exceeds the maximum rate period.

[0013] Further, when the interval maximum rate meets the significance condition and the corresponding peak point meets the persistence trend, the temperature is stopped from being raised, and the sintering temperature is adjusted to an intermediate holding temperature, which is the sintering actual temperature corresponding to the interval maximum rate. The actual shrinkage rate of the green body is detected in real time, and when the actual shrinkage rate is less than the shrinkage rate evaluation value, it is determined that the pore optimization by surface diffusion is completed, and the intermediate holding stage is stopped to continue to raise the temperature for sintering the green body, and the shrinkage rate evaluation value is the product of the interval maximum rate and the calibration percentage.

[0014] Further, the sintered body is sampled after sintering, and the phase of the sintered body is analyzed to confirm the retention rate of tetragonal zirconia. When the retention rate of tetragonal zirconia is greater than or equal to the target retention rate, it is determined that the performance of the sintered body meets the standard, and the sintering strategy matches the characteristics of the current batch of slurry. When the retention rate of tetragonal zirconia is less than the target retention rate, it is determined that the performance of the sintered body with insufficient tetragonal phase retention has hidden dangers, and the intermediate holding temperature of the subsequent sintering process is adjusted according to the deviation of the tetragonal phase retention rate.

[0015] Compared with the prior art, the beneficial effects of the present application are that zirconia is used as the main component to prepare ceramic implants through online diagnosis of slurry state, dynamic prediction of sintering activity and full-process closed-loop control. Compared with the existing composite scheme of adding alumina, the present application realizes essential improvement of low-temperature aging resistance performance of the material through high-purity component control and precise yttrium stabilization, fundamentally avoiding the risk of micro-stress and crack initiation at the heterogeneous interface caused by mismatch of thermal expansion coefficients of alumina and zirconia. At the same time, the present application intelligently matches the sintering strategy through the dynamic sintering activity index, which not only utilizes the higher phase transition toughening potential of pure zirconia system, but also effectively suppresses grain coarsening and closed pore formation through “critical density triggering” and “shrinkage rate peak monitoring” and other control means, finally obtaining a microstructure with fine and dense uniform grains. The prepared implant has high strength and excellent biocompatibility, and its long-term service stability and reliability are significantly better than those of zirconia-alumina composite materials.

[0016] Further, the method adopts a wet ball milling method to ensure that the powders of different components are uniformly mixed at a molecular level. Nanometer powders are prone to self-agglomeration into larger "soft agglomerates". Wet ball milling can effectively break these agglomerates, further reduce the particle size of the powders, and increase the specific surface area, so that the powders have higher activity and are more easily densified in the subsequent sintering process. The spray granulation method is to add a small amount of high-purity organic binder (such as polyvinyl alcohol) to the slurry after ball milling, and then put the slurry into a spray granulator. Liquid droplets are sprayed through the nozzle and dried to obtain spherical granulated powder with good flowability and concentrated particle size distribution. By reducing the surface energy to improve the flowability and uniformly fill the mold, the method provides a guarantee for the subsequent automatic molding.

[0017] Further, the slurry dispersion index includes a viscosity ratio and a fineness ratio. The lower the measured viscosity (η), the larger the ratio, indicating that the slurry has better flowability and possibly better dispersibility. The fewer the measured large particles (D90), the larger the ratio, indicating that the grinding effect is better, and the large particle agglomerates are effectively broken. The present application combines "grinding fineness" and "flow dispersibility" to introduce the slurry dispersion index to reflect the state of the slurry. Based on the D90 value and viscosity, the actual dispersion state of the slurry can be intelligently judged to be in an ideal, adjustable, or unqualified state, and decisions can be made to stop ball milling, compensate for subsequent processes, or precisely increase the number of cycles. This method effectively avoids particle agglomeration caused by insufficient ball milling or pollution and energy waste caused by excessive ball milling, ensuring that the slurry has a highly uniform particle size distribution (D90 and D50) and excellent flowability, providing a stable and reliable precursor for subsequent spray granulation and sintering processes. From the source, the uniformity and consistency of the microstructure of the medical zirconia ceramic implant are improved, and the mechanical properties and long-term reliability of the product are ultimately ensured.

[0018] Further, the present application uses the viscosity ratio and fineness ratio, which are refinement parameters of the slurry dispersion index, to precisely compensate and regulate the spray granulation process for the slurry in the adjustable deviation state. For high viscosity, the system proportionally reduces the solid content of the liquid, effectively ensuring the atomization effect and drying uniformity. For coarse particle size, the atomization pressure is proportionally increased to crush soft agglomerates and optimize the particle size distribution. This dynamic adjustment mechanism overcomes the lack of adaptability of fixed process parameters to precursor state fluctuations, significantly improving the flowability and filling uniformity of the granulated powder, and laying a reliable powder foundation for the subsequent sintering process of preparing high-density and high-performance zirconia ceramic implants.

[0019] Further, the composite powder is easier to obtain high density during sintering to achieve rapid densification, and small pores need to be eliminated by grain boundary diffusion or volume diffusion at the later stage of sintering, and insufficient temperature will leave micropores, and excessive temperature or time will cause rapid grain growth and swallow pores, which needs to be timely inhibited; the present application relates the precursor slurry state to the green body forming characteristics by constructing a dynamic sintering activity index, accurately predicts the sintering behavior of the green body in the sintering process, and comprehensively reflects the inherent activity of the powder, the dispersion of the slurry, the microstructure density of the green body and the compaction efficiency, so as to identify the risk of grain coarsening caused by high activity or closed pore defects caused by low density in advance; the sintering process is personalized preset and dynamically controlled, which overcomes the industry problem that the fixed sintering curve cannot adapt to the batch fluctuation of raw materials, and improves the uniformity and density of the microstructure of the zirconia implant.

[0020] Further, the sintering driving force is inversely proportional to the powder particle size, and the green body composed of the composite powder has a very high sintering driving force, if the heating rate is not properly controlled, the high driving force will cause the sintering rate to be too fast, which may cause the surface to be prematurely densified and form a "crust", block the channel for the internal pores to discharge and finally form closed pores, and the heating rate needs to be adjusted based on the powder particle size; the present method predicts the sintering driving force of the green body in the sintering process through the characteristic value of the particle size distribution of the slurry, actively slows down the input of heat energy, provides more sufficient time for the migration of internal substances, balances the densification process of the surface and the interior, and prevents "crusting" from a procedural point of view, as a pre-positioned fine management of subsequent control measures, to avoid the risk of crust and closed pores.

[0021] Further, a high DSAI value means a very high intrinsic sintering activity and excellent initial microstructure, and the sintering driving force is strong, under the traditional single heating sintering curve, the densification rate will be too fast, causing rapid migration of grain boundaries and grain coarsening, and the closed pores are wrapped by the grains to form "intragranular pores" which are difficult to eliminate and become crack sources; the core of the present method is to actively separate the densification process and the grain growth process in time, and the migration rate of the grain boundary is greatly inhibited after adjusting the temperature because of its higher activation energy, while the diffusion of atoms along the grain boundary can still be effectively carried out; this enables the material to be continuously transported to the closed pores, so that they gradually shrink and disappear, but the grain size is maintained in a small state at the end of the first step because the grain boundary hardly moves; the high activity of the material is used to achieve rapid preliminary densification, and the negative effects caused by high activity are avoided through the precise "density-triggered cooling" mechanism, and finally a high-performance microstructure with small grains, complete densification and no intragranular pores is obtained.

[0022] Further, a low DSAI value indicates the presence of large irregularly shaped pores in the green body, which will quickly sinter the matrix material, leading to premature densification, blocking the path of atmospheric pores and external communication, and reducing the density and reliability of the material; the present method intelligently identifies the significance peak and persistent downward trend of the shrinkage rate curve, accurately captures the key node of the transition of the sintering mechanism from surface diffusion to grain boundary diffusion, and automatically triggers intermediate holding, preferentially pre-treating and repairing potential large pores before the microstructure is "locked", at a temperature at which the grain has not yet begun to grow significantly, using the dominant mechanism of surface diffusion to smooth the pore surface and reduce the pore size, providing sufficient time for surface diffusion-dominated pore optimization, effectively eliminating the risk of closed pores formed by premature closure of large pores in low-activity green bodies, and dynamically determining the holding termination point based on the rate peak ratio, achieving the best balance between pore repair and energy efficiency.

[0023] Further, a low tetragonal phase retention rate usually indicates that the holding temperature in the second step of sintering is too high or the time is too long, causing excessive metastable tetragonal phase to transform into stable cubic phase; the present invention establishes a negative feedback adjustment mechanism for tetragonal zirconia retention rate and sintering process parameters, achieving closed-loop control of the long-term phase stability of the material; when insufficient tetragonal phase retention is detected, the intermediate holding temperature of the subsequent batch can be automatically reduced in proportion, effectively inhibiting the excessive transformation of tetragonal phase to cubic phase, thereby significantly improving the low-temperature aging resistance of the implant; by setting a temperature lower limit, the risk of over-regulation is avoided, ensuring that the product maintains excellent densification while achieving high phase stability, providing a key guarantee for the long-term clinical reliability of zirconia implants. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A flowchart of the preparation method of the zirconia-based medical composite ceramic material in the embodiments of the present invention; Figure 2 A schematic diagram of the structure inside the wet ball mill in the embodiments of the present invention; Figure 3 A schematic diagram of the circulation of the wet ball milling in the embodiments of the present invention; Figure 4 A flowchart of determining the mixing state of the slurry in the embodiments of the present invention; In the figure: 1-wet grinder, 2-circulating pump, 3-circulating tank, 11-material inlet, 12-rotary shaft, 13-grinding cavity, 14-main shaft, 15-slurry outlet, 16-ball milling slurry, 17-grinding balls. DETAILED DESCRIPTION

[0025] In order to make the objects and advantages of the present application clearer, the following further describes the present application with reference to the embodiments; it should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0026] The preferred embodiments of the present application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application and not to limit the protection scope of the present application.

[0027] It should be noted that, in the description of the present application, the terms indicating the direction or positional relationship of "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0028] In addition, it should also be noted that, in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication inside two elements. Those skilled in the art can understand the specific meaning of the above terms in the present application according to the specific circumstances.

[0029] Please refer to Figures 1-4 shown, Figure 1 is a flowchart of the preparation method of the zirconia-based medical composite ceramic material in the embodiments of the present application; Figure 2 is a structural schematic diagram of the internal structure of the wet ball mill in the embodiments of the present application; Figure 3 is a circulation schematic diagram of the wet ball milling in the embodiments of the present application; Figure 4 is a flowchart of determining the mixing state of the slurry in the embodiments of the present application.

[0030] The present application provides a preparation method of a zirconia-based medical composite ceramic material, comprising: Step S1, the slurry is circulated by wet ball milling according to a target cycle number, one of the particle size distribution characteristics of the slurry and the actual slurry viscosity are obtained to determine the dispersion index of the slurry, so as to determine the mixing state of the slurry; Step S2, the target cycle number is adjusted or the spray granulation process parameters are compensatorily adjusted based on the slurry state parameters in response to the mixing state of the slurry; Step S3, the powder filling characteristic parameters and the initial green compact density of the green compact are combined with the dispersion index of the slurry to determine the dynamic sintering activity index, so as to determine the green compact characteristics of the current batch of green compact; Step S4, predicting the sintering driving force of the green body in the sintering process based on another particle size distribution characteristic value of the slurry, adjusting the temperature rising rate of the sintering process, and dynamically adjusting the sintering adjustment strategy of the sintering process based on the dynamic sintering activity index in response to the green body characteristics; Step S5, determining whether there is a risk of grain coarsening in the sintering process based on the green body characteristics, and adjusting the temperature stage and sintering temperature of the sintering process by obtaining the actual relative density of the green body; Step S6, determining whether there is a risk of closed porosity in the current batch of green body based on the green body characteristics, and determining the adjustment characteristic point to stop the sintering temperature rising and add a holding stage and determine the holding intermediate temperature and holding stage time according to the change degree of the actual shrinkage rate in response to the adjustment characteristic point; Step S7, obtaining the sintered body phase to determine the tetragonal zirconia retention rate to determine whether the sintering adjustment strategy matches the current batch of slurry characteristics based on the sintered body performance, and adjusting the intermediate holding temperature of the subsequent sintering process according to the deviation of the tetragonal phase retention rate in response to the sintered body performance.

[0031] In this embodiment, the medical composite ceramic material is a ceramic implant with zirconia as the main component. The percentage of chemical components in the medical composite ceramic material is ZrO2+HfO2+Y2O3≥99.0%, Y2O3>4.5% and ≤6.0%, HfO2≤5%, Al2O3≤0.5%, and other oxides ≤0.5%. The chemical properties and mechanical properties of the qualified medical composite ceramic material should meet the material performance requirements in YY / T 1715-2020.

[0032] Specifically, the present application prepares ceramic implants by online diagnosis of slurry state, dynamic prediction of sintering activity and full-process closed-loop control with zirconia as the main component. Compared with the existing composite scheme of adding aluminum oxide, the present application realizes essential improvement of low-temperature aging resistance performance of the material through high-purity component control and precise yttrium stabilization, fundamentally avoiding the risk of micro-stress and crack initiation at the heterogeneous interface caused by the mismatch of thermal expansion coefficients of aluminum oxide and zirconia. At the same time, the present application intelligently matches the sintering strategy through the dynamic sintering activity index, which not only utilizes the higher phase transition toughening potential of pure zirconia system, but also effectively inhibits grain coarsening and closed porosity formation through "critical density trigger" and "peak value monitoring of shrinkage rate" and other control means, finally obtaining a microstructure with fine grains, high density and uniformity. The prepared implant has high strength and excellent biocompatibility, and its long-term service stability and reliability are significantly better than those of zirconia-aluminum oxide composite materials.

[0033] In this embodiment, yttrium stabilized zirconia composite powder prepared by coprecipitation method is selected as the main raw material, and a coprecipitation preparation method of yttrium stabilized zirconia composite powder is provided, which includes but is not limited to the coprecipitation preparation method of yttrium stabilized zirconia composite powder. Specifically, the salt solution containing zirconium, hafnium and yttrium ions such as zirconium oxychloride and yttrium nitrate is mixed in the required stoichiometric ratio, and then a precipitant such as ammonia is added to precipitate all the metal ions simultaneously and synchronously to form a homogeneous hydroxide or carbonate precursor, which is washed, dried and calcined to obtain yttrium-stabilized zirconia composite powder.

[0034] To further ensure the absolute uniformity of the components and crush the soft agglomerates, the powder is mixed with anhydrous ethanol and a small amount of dispersant such as ammonium polyacrylate in a certain proportion to form a slurry, which is wet ball milled for 12 to 24 hours using zirconia balls and a planetary ball mill. This achieves further nanometerization and uniform mixing of the powder while avoiding the introduction of aluminum impurities beyond the standard.

[0035] Specifically, the preparation process of the medical composite ceramic material includes co-precipitation method for preparing yttrium-stabilized zirconia composite powder, wet ball milling, spray granulation, implant forming, high-temperature sintering and post-processing. In this embodiment, the wet ball milling is performed on the ball milling slurry 16 by a wet ball mill 1. The ball milling slurry 16 to be dispersed is put into a cylindrical grinding cavity 13 containing grinding balls 17 through a material inlet 11, continuously transported by a circulating pump 2, and the operating parameters of the main shaft 14 are adjusted by changing the rotation of the rotating shaft 12 and other aspects to change the shearing force and collision force between the grinding balls 17, so that the ball milling slurry 16 is wet dispersed and then output from a slurry outlet 15. In the implementation, the ball milling slurry 16 enters the circulating tank 3 through the slurry outlet 15 and is circulated to the material inlet 11 of the wet ball mill 1 under the output action of the circulating pump 2 and enters the grinding cavity 13.

[0036] Specifically, the circulating wet ball milling method ensures that the powders of different components are uniformly mixed at the molecular level. Nanometer powders are prone to agglomerate into larger "soft agglomerates". Wet ball milling can effectively break these agglomerates, further reduce the particle size of the powder, and increase its specific surface area, so that the powder has higher activity and is more easily densified in the subsequent sintering process. The spray granulation method adds a small amount of high-purity organic binder (such as polyvinyl alcohol) to the slurry after ball milling. The slurry is put into a spray granulator, and liquid droplets are sprayed through a nozzle and then dried to obtain spherical granulated powder with good flowability and concentrated particle size distribution. By reducing the surface energy to improve the flowability and uniformly filling the mold, the subsequent automated forming is ensured.

[0037] In the preparation of advanced ceramics, "granulation" is also necessary, which has a direct impact on the quality of the finished ceramic product. For example, from the perspective of sintering, the finer the ceramic powder, the better. However, due to high surface energy and poor flowability, fine powder is often difficult to uniformly fill the mold during compression molding, resulting in problems such as voids, non-densification of edges and corners, layer cracking, and elastic aftereffect. The use of the granulation process can solve this problem.

[0038] The granulation powder is accurately filled into a mold in the shape of an implant, an axial dry pressing obtains an implant green body, the dry pressed green body is sealed in a high-elastic rubber mold and placed in a cold isostatic pressing machine; The green body is placed in a high-temperature sintering furnace for sintering, and in the initial stage, the temperature is slowly raised to 600 degrees Celsius for 1 to 2 hours; In the densification sintering stage, the temperature is raised at a relatively fast rate to the final sintering temperature, which is determined through process optimization, between 1350 degrees Celsius and 1500 degrees Celsius, for 1 to 2 hours, to realize the diffusion of crystal grains and complete densification of the material.

[0039] In the cooling stage, the furnace is cooled slowly or according to a set program to release internal stress.

[0040] In the post-processing procedure, the implant surface is sandblasted or acid-etched to increase surface roughness and promote osseointegration.

[0041] In the wet ball milling process of the embodiment, the wet ball milling device performs cyclic wet ball milling on the slurry according to a preset target cycle number.

[0042] The slurry in the grinding cavity during the wet ball milling is sampled and detected according to an initial detection cycle to obtain the particle size distribution characteristic value and the actual slurry viscosity of the slurry, and calculate the slurry dispersibility index; Slurry dispersibility index = (target slurry viscosity / actual slurry viscosity) x (target characteristic value / particle size distribution characteristic value); In the implementation, the particle size distribution characteristic value is the D90 value and the median particle size D50 value in the particle size distribution of the slurry, and the target characteristic value is the target D90 value.

[0043] When the slurry dispersibility index is greater than or equal to the first index threshold value, it is judged that the slurry is in a first mixed state, the fineness and fluidity of the slurry meet the requirements, and the current cycle number of the wet ball milling is set as the target cycle number; When the slurry dispersibility index is less than the first index threshold value and greater than or equal to the second index threshold value, it is judged that the slurry is in a second mixed state, and the slurry state has an adjustable deviation, which is compensated for in the subsequent process; When the slurry dispersibility index is less than the second index threshold value, it is judged that the slurry is in a third mixed state, and the slurry state does not meet the requirements, and the target cycle number of the wet ball milling is increased; Specifically, the target cycle number of the wet ball milling is increased by an integer value of the product of the ratio of the second index threshold value to the slurry dispersibility index and the target cycle number.

[0044] In the implementation, the value range of the target slurry viscosity is preferably 200-400 mPa·s, the value range of the target D90 value is preferably 0.3-0.6 μm, the first exponential threshold is 1.0, and the second exponential threshold is 0.7.

[0045] Specifically, the slurry dispersibility index includes a viscosity ratio and a fineness ratio. The lower the actual viscosity (the smaller η), the greater the ratio, which indicates that the slurry fluidity is better and the dispersibility can be better. The fewer the actual large particles (the smaller D90), the greater the ratio, which indicates that the grinding effect is better, and the large particle agglomerates are effectively broken. The present application combines “grinding fineness” and “flow dispersibility” to introduce the slurry dispersibility index to reflect the slurry state. The slurry dispersibility index can intelligently judge the actual dispersion state of the slurry based on the D90 value and the viscosity, and automatically make decisions to stop ball milling, compensate for subsequent processes, or precisely increase the number of cycles. This method effectively avoids particle agglomeration caused by insufficient ball milling or pollution and energy waste caused by excessive ball milling, ensures that the slurry has a highly uniform particle size distribution (D90 and D50) and excellent fluidity, provides a stable and reliable precursor for subsequent spray granulation and sintering processes, improves the uniformity and consistency of the microstructure of the medical zirconia ceramic implant from the source, and ultimately ensures the mechanical properties and long-term reliability of the product.

[0046] When the slurry is in the second mixed state, the process parameters of the spray granulation are dynamically adjusted according to the actual state of each parameter of the slurry; When the slurry is in the second mixed state, the preset process parameters of the spray granulation process are adjusted according to the slurry state parameters, which include a viscosity ratio and a fineness ratio. The viscosity ratio is (target slurry viscosity / actual slurry viscosity), and the fineness ratio is (target characteristic value / particle size distribution characteristic value). Specifically, if the actual slurry viscosity is greater than the target slurry viscosity, the solid content of the spray granulation is reduced in proportion to the ratio of the target slurry viscosity to the actual slurry viscosity, to ensure the atomization effect and the uniformity of droplet drying. If the particle size distribution characteristic value is greater than the target characteristic value, the atomization pressure of the spray granulation is increased according to the ratio of the particle size distribution characteristic value to the target characteristic value, to crush possible soft agglomerates and obtain a narrower particle size distribution.

[0047] Specifically, the present application implements accurate compensatory regulation of the spray granulation process for slurry in an adjustable deviation state through the refined parameters of slurry dispersibility index, i.e., viscosity ratio and fineness ratio. For high viscosity, the system proportionally reduces the solid content of the slurry to effectively ensure the atomization effect and drying uniformity; for coarse particle size, the atomization pressure is proportionally increased to crush soft agglomerates and optimize the particle size distribution. This dynamic adjustment mechanism overcomes the insufficient adaptability of fixed process parameters to precursor state fluctuations, significantly improves the flowability and filling uniformity of the granulated powder, and lays a reliable powder foundation for the subsequent sintering process of preparing high-density and high-performance zirconia ceramic implants.

[0048] The actual tap density of the powder after spray granulation is obtained, which is used to reflect the filling characteristics of the granulated powder, and the actual tap density is a powder filling characteristic parameter of the granulated powder; After dry pressing, the initial green density of the green body is measured using non-destructive testing, and the dynamic sintering activity index is calculated to reflect the green body characteristics of the current batch of green bodies, wherein the dynamic sintering activity index = slurry dispersibility index 第一权重 × (initial green density / actual tap density) 第二权重 ; It can be understood that the higher the slurry dispersibility index, the more completely the original powder agglomeration is broken, and the higher the intrinsic sintering activity; the higher the (initial green density / actual tap density) ratio, the better the granulated powder fills under pressure, the stronger the particle rearrangement and deformation ability, and the more the contact points inside the green body, indicating that the material transport path in the sintering process is more optimal and the densification driving force is stronger.

[0049] When the dynamic sintering activity index exceeds the calibrated index range, it is determined that the current batch of green bodies has high intrinsic activity and excellent green body microstructure, and the sintering driving force is strong, and the densification rate is fast; When the dynamic sintering activity index is within the calibrated index range, it is determined that the green body characteristics of the current batch of green bodies are within the preset range; When the dynamic sintering activity index is lower than the calibrated index range, it is determined that the current batch of green bodies has pores due to poor dispersion or poor green body efficiency, and the sintering resistance is large; In implementation, the first weight has a value range of 0.4-0.6, the second weight has a value range of 0.4-0.6, the sum of the weights is one, and the calibrated index range is (0.85, 1.15).

[0050] Specifically, the composite powder is easier to obtain high density during sintering process to achieve rapid densification, and small pores need to be eliminated by grain boundary diffusion or volume diffusion at the later stage of sintering, and insufficient temperature will leave micropores, and excessive temperature or long time will cause rapid grain growth and engulf pores, which needs to be timely inhibited; the present application relates the precursor slurry state to the green body forming characteristics by constructing a dynamic sintering activity index, accurately predicts the sintering behavior of the green body sintering process; comprehensively reflects the powder intrinsic activity slurry dispersity and the green body microstructure density compaction efficiency, can identify the grain coarsening risk caused by high activity or closed pore defects caused by low density in advance; individualize the sintering process and dynamically control it, overcome the industry problem that fixed sintering curve cannot adapt to raw material batch fluctuation, and improve the uniformity and density of zirconia implant microstructure.

[0051] Specifically, the driving force of the sintering process is almost entirely from the reduction of surface energy and grain boundary energy (densification), without consuming additional energy and time for long-range component homogenization diffusion. This makes the sintering starting temperature lower, the densification rate faster, and it is easier to obtain high density at lower temperature.

[0052] The sintering driving force of the green body in the sintering process is predicted based on the particle size distribution characteristic value of the slurry, and the heating rate of the sintering process is adjusted; In the particle size distribution characteristic value of the slurry, the median particle size D50 value in the particle size distribution of the slurry is obtained, the sintering driving force coefficient is calculated, and the sintering driving force coefficient = target median particle size / median particle size D50 value; When the sintering driving force coefficient is greater than the driving force warning threshold, it is judged that the current batch of slurry has ultra-high sintering driving force, and there is a high driving force risk that the densification rate is too fast under the current sintering parameters, and the heating rate of the sintering process is adjusted; Specifically, when there is a high driving force risk, the heating rate of the sintering process is reduced according to a ratio of the sintering driving force coefficient before the sintering process starts; In the implementation, the target median particle size is preferably 0.05-0.15 μm, and the driving force warning threshold is 1.2.

[0053] Specifically, the sintering driving force is inversely proportional to the powder particle size, and the green body composed of composite powder has extremely high sintering driving force. If the heating rate is not properly controlled, the excessively high driving force will cause the sintering rate to be too fast, which may cause the surface to prematurely densify and form a "crust", blocking the channels for the internal pores to discharge and eventually forming closed pores. The heating rate needs to be adjusted based on the powder particle size; the method predicts the sintering driving force of the green body in the sintering process through the characteristic value of the particle size distribution of the slurry, actively slows down the input of heat energy, provides more sufficient time for the diffusion of matter, especially the migration of internal matter, balances the densification process of the surface and the interior, and prevents "crusting" from a procedural point of view. As a pre-positioned fine management of subsequent control measures, it avoids the risk of closed pores due to crusting.

[0054] According to the dynamic sintering activity index, the sintering adjustment strategy of the sintering process is dynamically adjusted; When the current batch of green bodies have high intrinsic activity and excellent green body microstructure, it is determined that the current batch of green bodies have the risk of grain coarsening in the sintering process, and the temperature stage of the sintering process is adjusted according to the sintering critical density of the green body; Specifically, the initial volume, initial mass and initial length of the green body are obtained before the sintering process, the linear shrinkage of the green body in the axial or radial direction is detected in real time by a non-contact laser displacement sensor, and the actual sintering temperature in the sintering furnace is detected synchronously; The actual volume of the green body = initial volume x (1-linear shrinkage / initial length) 3 The actual density = initial mass / actual volume, and the actual relative density = (actual density / theoretical density) x 100%. When the actual relative density is greater than the critical relative density, it is determined that the current batch of green bodies are densified to the critical density, and the sintering temperature is reduced and the temperature is maintained; Specifically, when the actual relative density of the current batch of green bodies reaches the critical relative density, the sintering temperature is reduced to a preset adjustment range at the maximum controllable temperature adjustment rate, and the temperature is maintained for a preset holding time.

[0055] In implementation, the theoretical density is the required theoretical density of the green body prepared from zirconia composite powder after sintering, and the unit is g / cm³. The critical relative density is preferably 80%-85%, and in implementation, it is 82%. The preset adjustment range is 150-250℃, and the preset holding time is 2-5h.

[0056] Specifically, the critical relative density is established based on experiments. When the relative density is below this range, the open pore network in the green body has not yet completely closed, and premature cooling will lead to insufficient densification. When the relative density is higher than this range (such as > 90%), the grains have begun to grow rapidly, and it is too late to inhibit grain boundary migration at this time. At a relative density of 82%, the open pores just disappear and turn into closed pores, and the grain boundary network is initially formed but has not yet begun to migrate violently. At this time, cooling is the best window to separate the densification and grain growth processes.

[0057] Specifically, a high DSAI value means extremely high intrinsic sintering activity and excellent initial microstructure. Its sintering driving force is strong, and under the traditional single heating sintering curve, the densification rate will be too fast, leading to rapid migration of grain boundaries, grain coarsening, and closed pores being wrapped by grains to form "intragranular pores" that are difficult to eliminate and become crack sources. The core of the method is to actively separate the densification process and the grain growth process in time. Through real-time density feedback triggering adjustment strategies, the rate of grain boundary migration is greatly inhibited after adjusting the temperature, while atomic diffusion along the grain boundary can still be effectively carried out. This allows the material to continue to transport to the closed pores, causing them to gradually shrink and disappear, but because the grain boundaries hardly move, the grain size remains small at the end of the first step. The high activity of the material is used to achieve rapid preliminary densification, and the negative effects of high activity are avoided through the precise "density-triggered cooling" mechanism, ultimately obtaining a high-performance microstructure with fine grains, complete densification, and no intragranular pores.

[0058] When the sintering resistance of the current batch of green bodies is large, it is determined that the current batch of green bodies has a risk of forming closed pores, and the adjustment feature point is determined according to the degree of change in the actual shrinkage rate to adjust the sintering temperature; Specifically, the actual shrinkage rate is calculated based on the linear shrinkage amount, an actual shrinkage rate-sintering actual temperature curve is drawn, and the interval maximum rate of the actual shrinkage rate-sintering actual temperature curve in a plurality of preset temperature intervals is obtained. When the actual ratio of the interval maximum rate in the current preset temperature interval to the interval average rate in the last preset temperature interval is greater than the minimum increase threshold, it is determined that the interval maximum rate in the current preset temperature interval meets the significance condition.

[0059] After determining the interval maximum rate that meets the significance condition, the linear fitting slope of the peak point corresponding to the interval maximum rate in the subsequent unit time is calculated, and the shrinkage rate difference of a plurality of data points and the shrinkage rate difference of the previous data point is obtained according to the preset temperature unit. The actual negative value proportion of the shrinkage rate difference that is negative in a plurality of shrinkage rate differences is calculated. When the linear fitting slope is less than the slope threshold value and the actual negative value proportion is greater than or equal to the proportion threshold value, it is determined that the peak point corresponding to the interval maximum rate meets the persistence trend, and the dominant diffusion mechanism of the sintering stage corresponding to the current preset temperature interval has passed the maximum rate period; When the interval maximum rate meets the significance condition and the corresponding peak point meets the persistence trend, the temperature is stopped from being raised, and the sintering temperature is adjusted to the intermediate holding temperature, which is the sintering actual temperature corresponding to the interval maximum rate; The sintering process is performed at the intermediate holding temperature, and the surface diffusion mechanism continues to polish and repair the pores, and the actual shrinkage rate of the green body is detected in real time; When the actual shrinkage rate is less than the shrinkage rate evaluation value, it is determined that the pore optimization by surface diffusion is completed, and the intermediate holding stage is stopped, and the green body is sintered by continuing to raise the temperature, and the shrinkage rate evaluation value is the product of the interval maximum rate and the calibration percentage.

[0060] In implementation, the preset temperature interval is 100℃, the interval average rate is the average value of the actual shrinkage rate in the preset temperature interval, the preset temperature unit is 10℃, and the calibration percentage is 20%.

[0061] Specifically, a low DSAI value indicates that there are pores with large size and irregular shape in the green body, and the matrix material will be quickly sintered to cause premature densification, reduce the material density and reliability by blocking the path of atmospheric pores and the outside, and the method accurately captures the key node of the conversion of the sintering mechanism from surface diffusion to grain boundary diffusion by intelligently identifying the significant peak and persistent downward trend of the shrinkage rate curve, and automatically triggers the intermediate holding, pre-processes and repairs the potential large pores before the microstructure is “locked”, and uses the surface diffusion mechanism at a temperature at which the grain has not started to grow significantly to smooth the pore surface and reduce the pore size, provides sufficient action time for the pore optimization dominated by surface diffusion, effectively eliminates the risk of closed pores caused by the premature closure of large pores in the low-activity green body, and dynamically determines the holding termination point based on the rate peak proportion to achieve the best balance between pore repair and energy efficiency.

[0062] The sintered body is sampled, X-ray diffraction (XRD) is used to analyze the sintered body phase, and the tetragonal zirconia retention rate is confirmed, the tetragonal zirconia retention rate = (tetragonal phase content in the sintered body / total content of tetragonal phase and cubic phase) × 100%; When the tetragonal zirconia retention rate is greater than or equal to the target retention rate, it is determined that the sintered body performance meets the standard, and the sintering strategy matches the current batch of slurry characteristics; When the tetragonal phase zirconia retention rate is less than the target retention rate, it is determined that the performance of the tetragonal phase retention insufficient sintered body has hidden dangers, and the intermediate holding temperature of the subsequent sintering process is adjusted according to the deviation of the tetragonal phase retention rate; Specifically, the adjusted intermediate holding temperature = current intermediate holding temperature-adjustment gain coefficient x (target retention rate-tetragonal phase zirconia retention rate). To avoid over-adjustment leading to insufficient densification, a minimum temperature lower limit such as 1250°C is set, and when the adjusted intermediate holding temperature is lower than the minimum temperature lower limit, the minimum temperature lower limit is used as the intermediate holding temperature, and a front-end process warning is generated.

[0063] In implementation, the target retention rate is 97%, and the adjustment gain coefficient is 1°C / %.

[0064] Specifically, too low tetragonal phase retention rate usually means that the second step sintering holding temperature is too high or the time is too long, resulting in excessive metastable tetragonal phase transforming into stable cubic phase; the present application realizes closed-loop control of long-term phase stability of the material by establishing a negative feedback adjustment mechanism of tetragonal phase zirconia retention rate and sintering process parameters. When the tetragonal phase retention rate is detected to be insufficient, the intermediate holding temperature of the subsequent batch can be automatically reduced in proportion, effectively inhibiting the excessive transformation of the tetragonal phase to the cubic phase, thereby significantly improving the low-temperature aging resistance of the implant; by setting a temperature lower limit, the risk of over-adjustment is avoided, ensuring that the product maintains excellent densification while obtaining high phase stability, providing a key guarantee for the long-term clinical reliability of zirconia implants.

[0065] So far, the technical solutions of the present application have been described in combination with the preferred embodiments shown in the drawings, but those skilled in the art can easily understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will fall within the protection scope of the present application.

[0066] The above description is only the preferred embodiments of the present application and is not intended to limit the present application; for those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for producing a medical composite ceramic material based on zirconia, characterized in that, The method comprises the following steps: acquiring one of the particle size distribution characteristic values of the slurry circulated according to the target cycle number in the circulating wet ball milling process and the actual slurry viscosity to determine the slurry dispersion index, so as to determine the mixing state of the slurry; adjusting the target cycle number in response to the mixing state of the slurry or compensatively adjusting the parameters of the slurry spray granulation process based on the slurry state parameters; acquiring the powder filling characteristic parameters and the initial green compact density to determine the dynamic sintering activity index in combination with the slurry dispersion index, so as to determine the green compact characteristics of the current batch of green compacts; predicting the sintering driving force of the green compact in the sintering process based on another particle size distribution characteristic value of the slurry, adjusting the temperature rising rate of the sintering process, and dynamically adjusting the sintering adjustment strategy of the sintering process based on the dynamic sintering activity index in response to the green compact characteristics; determining whether there is a risk of grain coarsening in the sintering process based on the green compact characteristics, acquiring the actual relative density of the green compact to adjust the temperature stage and the sintering temperature of the sintering process; determining whether there is a risk of closed pore in the current batch of green compacts based on the green compact characteristics, determining the adjustment feature point in combination with the change degree of the actual shrinkage rate to stop the sintering temperature rising and add a holding stage in response to the adjustment feature point, and determining the holding intermediate temperature and the holding stage time length; acquiring the phase of the sintered body to determine the retention rate of tetragonal zirconia, so as to determine whether the sintering adjustment strategy matches the characteristics of the current batch of slurry based on the performance of the sintered body, and adjust the intermediate holding temperature of the subsequent sintering process according to the deviation of the tetragonal phase retention rate in response to the performance of the sintered body.

2. The method for producing a zirconia-based medical composite ceramic material according to claim 1, characterized by, The slurry in the grinding cavity is sampled and detected to acquire the particle size distribution characteristic value and the actual slurry viscosity to determine the slurry dispersion index; when the slurry dispersion index is greater than or equal to the first index threshold value, it is determined that the slurry is in the first mixing state, the fineness and fluidity of the slurry meet the requirements, and the current cycle number of the wet ball milling is set as the target cycle number; when the slurry dispersion index is less than the first index threshold value and greater than or equal to the second index threshold value, it is determined that the slurry is in the second mixing state, and the slurry state has an adjustable deviation, so that compensative adjustment is made on the subsequent process; when the slurry dispersion index is less than the second index threshold value, it is determined that the slurry is in the third mixing state, and the slurry state does not meet the requirements, so that the target cycle number of the wet ball milling is increased; The particle size distribution characteristic value of the slurry includes the D90 value and the median particle size D50 value in the particle size distribution of the slurry.

3. The method for producing a zirconia-based medical composite ceramic material according to claim 2, characterized by, When the slurry is in the second mixing state, the spray granulation process parameters are adjusted according to the slurry state parameters, and the slurry state parameters include the viscosity ratio and the fineness ratio; if the actual slurry viscosity is greater than the target slurry viscosity, the solid content of the slurry solution in the spray granulation is reduced in proportion according to the ratio of the target slurry viscosity to the actual slurry viscosity; if the particle size distribution characteristic value is greater than the target characteristic value, the atomization pressure of the spray granulation is increased according to the ratio of the particle size distribution characteristic value to the target characteristic value.

4. The method for producing a zirconia-based medical composite ceramic material according to claim 3, characterized by, The powder filling characteristic parameters and the initial green compact density are acquired to calculate the dynamic sintering activity index, so as to reflect the green compact characteristics of the current batch of green compacts, and the powder filling characteristic parameters include the actual tap density of the powder. When the dynamic sintering activity index exceeds the calibrated index range, it is determined that the current batch of green bodies has intrinsic activity beyond the range and the green body characteristics of the green body microstructure, and the sintering driving force and densification rate exceed the preset range; When the dynamic sintering activity index is within the calibrated index range, it is determined that the green body characteristics of the current batch of green bodies are within the preset range; When the dynamic sintering activity index is below the calibrated index range, it is determined that the current batch of green bodies has pores due to poor dispersion or poor compaction efficiency, and the sintering resistance is large.

5. The method for producing a zirconia-based medical composite ceramic material according to claim 4, characterized by, The sintering driving force coefficient is determined according to the median particle size D50 value; When the sintering driving force coefficient is greater than the driving force warning threshold, it is determined that the current batch of slurry has a driving force risk of too fast densification rate under the current sintering parameters, and the heating rate of the sintering process is adjusted according to the sintering driving force coefficient.

6. The method for producing a zirconia-based medical composite ceramic material according to claim 3, characterized by, When the current batch of green bodies has intrinsic activity beyond the range and the green body characteristics of the green body microstructure, the current batch of green bodies has the risk of grain coarsening during the sintering process; The initial volume, initial mass and initial length of the green body are obtained, and the linear shrinkage of the green body in the axial or radial direction is detected to determine the actual relative density; When the actual relative density is greater than the critical relative density, it is determined that the current batch of green bodies is densified to the critical density, and the sintering temperature is reduced to the preset adjustment range at the maximum controllable temperature adjustment rate, and the temperature is kept for a preset holding time.

7. The method for producing a zirconia-based medical composite ceramic material according to claim 3, characterized by, When the sintering resistance of the current batch of green bodies is large, it is determined that the current batch of green bodies has the risk of forming closed pores, and the adjustment feature point is determined according to the change degree of the actual shrinkage rate; The actual shrinkage rate is calculated according to the linear shrinkage, the actual shrinkage rate-sintering actual temperature curve is drawn, and the interval maximum rate of the actual shrinkage rate-sintering actual temperature curve in several preset temperature intervals is obtained; When the actual ratio of the interval maximum rate in the current preset temperature interval to the interval average rate in the last preset temperature interval is greater than the minimum increase threshold, it is determined that the interval maximum rate in the current preset temperature interval meets the significance condition.

8. The method for producing a zirconia-based medical composite ceramic material according to claim 7, characterized by, After determining the interval maximum rate that meets the significance condition, the linear fitting slope of the peak point corresponding to the interval maximum rate in the subsequent unit time is calculated, and the shrinkage rate difference of several data points and the shrinkage rate difference of the previous data point is obtained according to the preset temperature unit, and the actual negative value proportion of the shrinkage rate difference that is negative in several shrinkage rate differences is calculated. When the linear fitting slope is less than the slope threshold and the actual negative value proportion is greater than or equal to the proportion threshold, it is determined that the peak point corresponding to the interval maximum rate meets the persistence trend, and the dominant diffusion mechanism of the sintering stage corresponding to the current preset temperature interval exceeds the maximum rate period.

9. The method for producing a zirconia-based medical composite ceramic material according to claim 8, characterized by, When the interval maximum rate meets the significance condition and the peak point corresponding to the interval maximum rate meets the persistence trend, the temperature adjustment is stopped and the sintering temperature is adjusted to the intermediate holding temperature, and the intermediate holding temperature is the sintering actual temperature corresponding to the interval maximum rate; Real-time detection of the actual shrinkage rate of the green body, when the actual shrinkage rate is less than the shrinkage rate evaluation value, it is judged that the pore optimization by surface diffusion is completed, the intermediate holding stage is stopped, and the green body is sintered by continuing to heat, the shrinkage rate evaluation value is the product of the maximum rate in the interval and the calibration percentage.

10. The method for producing a zirconia-based medical composite ceramic material according to claim 9, characterized by, Sampling the sintered body after sintering, analyzing the sintered body phase to confirm the retention rate of tetragonal zirconia; When the retention rate of tetragonal zirconia is greater than or equal to the target retention rate, it is judged that the performance of the sintered body meets the standard, and the sintering strategy matches the current batch of slurry characteristics; When the retention rate of tetragonal zirconia is less than the target retention rate, it is judged that the performance of the sintered body with insufficient tetragonal phase retention has hidden dangers, and the intermediate holding temperature of the subsequent sintering process is adjusted according to the deviation of the tetragonal phase retention rate.

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