阅读说明：本技术 一种气氛保护常压烧结制备透明磷酸钙生物陶瓷的方法 (Method for preparing transparent calcium phosphate biological ceramic by atmosphere protection and normal pressure sintering ) 是由 徐传艳 李亚东 朱阳光 李亚军 于 2018-08-09 设计创作，主要内容包括：本发明提出一种气氛保护常压烧结制备透明磷酸钙生物陶瓷的方法,属于生物医用材料技术领域。本发明以高纯纳米羟基磷灰石(HA)和/或高纯纳米β-磷酸三钙(β-TCP)粉体为原料,不添加任何烧结助剂,采用水蒸气保护,在大气压条件下,分段常压烧结获得透光率为50～95％的透明磷酸钙生物陶瓷。所述透明磷酸钙生物陶瓷的相组成为HA单相、β-TCP单相或HA/β-TCP两相混合物。本发明不仅工艺简单,设备投资小,生产周期短,可满足批量生产要求,而且得到的透明磷酸钙生物陶瓷相对密度大于99.5％,晶粒均匀细小,无杂相存在,具有较高的力学强度,可作为观察细胞、组织与磷酸钙生物陶瓷相互作用的良好基体材料,也可用于齿根、牙髓和义眼等修复领域。(The invention provides a method for preparing transparent calcium phosphate bioceramic by atmosphere protection and normal pressure sintering, which belongs to the technical field of biomedical materials, wherein high-purity nano Hydroxyapatite (HA) and/or high-purity nano β -tricalcium phosphate (β -TCP) powder is used as a raw material, no sintering auxiliary agent is added, water vapor is used for protection, and the transparent calcium phosphate bioceramic with the light transmittance of 50-95% is obtained by sectional normal pressure sintering under the atmospheric pressure condition.)

1. The method for preparing the transparent calcium phosphate bioceramic through atmosphere protection and normal pressure sintering is characterized in that high-purity nano hydroxyapatite and/or high-purity nano β -tricalcium phosphate powder is used as a raw material, the transparent calcium phosphate bioceramic with the light transmittance of 50-95% is obtained through segmented high-temperature normal pressure sintering, and steam protection can be selected in the sintering process.

2. The method for preparing transparent calcium phosphate bioceramic according to claim 1, wherein the transparent calcium phosphate bioceramic is hydroxyapatite, β -tricalcium phosphate single-phase or hydroxyapatite/β -tricalcium phosphate two-phase composite ceramic.

3. The method for preparing transparent calcium phosphate bioceramic according to claim 1, wherein the transparent calcium phosphate bioceramic has a relative density of more than 99.5% and a grain size of each phase of less than 10 μm.

4. The method for preparing transparent calcium phosphate bioceramic through atmosphere protection and atmospheric pressure sintering according to claim 1, comprising the following steps:

s1, weighing the high-purity nano hydroxyapatite and/or high-purity nano β -tricalcium phosphate powder according to different proportions of two phases of hydroxyapatite and β -tricalcium phosphate, mixing, ball-milling, pulping, and performing spray granulation;

s2, filling the granulated powder into a die, performing prepressing molding by using a dry press, and then performing cold isostatic pressing to obtain a blank body, wherein the relative density of the blank body is more than 55%;

s3, placing the blank in an electric furnace for sectional sintering, and optionally slowly injecting deionized water into the hearth by using a peristaltic pump to sinter the blank in a high-temperature water vapor environment;

and S4, performing surface grinding and polishing machining treatment on the sintered transparent calcium phosphate bioceramic.

5. The method for preparing transparent calcium phosphate bioceramic through atmosphere protection and atmospheric pressure sintering according to claim 1 or 4, wherein the purity of the high-purity nano-hydroxyapatite and high-purity nano- β -tricalcium phosphate powder is greater than 99.9%, and the grain size of each powder is 10-300 nm.

6. The method for preparing transparent calcium phosphate bioceramic through atmosphere protection and normal pressure sintering according to claim 4, wherein the high-purity nano-hydroxyapatite and/or high-purity nano- β -tricalcium phosphate powder in the step S1 is subjected to ball milling after being mixed, a proper amount of dispersant and defoaming agent are added, zirconia balls are used as ball milling media, ethanol or deionized water is used as ball milling solvents, the mass ratio of the mixed powder to the ball milling media to the ball milling solvents is 1: 1-5: 1-3, the rotating speed of the ball mill is 100-400 r/min, and the ball milling time is 1-10 hours.

7. The method for preparing transparent calcium phosphate bioceramic through atmosphere protection and normal pressure sintering according to claim 4, wherein the microspheres with the diameter of 10-200 microns are obtained through spray granulation after the high-purity nano hydroxyapatite and/or high-purity nano β -tricalcium phosphate powder is mixed, ball-milled and pulped in the step S1.

8. The method for preparing transparent calcium phosphate bioceramic through atmosphere-protection atmospheric-pressure sintering according to claim 4, wherein the pressure of the pre-compaction molding in the step S2 is 20-50 MPa, and the pressure of the cold isostatic pressing is 100-350 MPa.

9. The method for preparing transparent calcium phosphate bioceramic through atmosphere-protection atmospheric-pressure sintering according to claim 4, wherein in step S3, the temperature is raised to 350-650 ℃ at 1-5 ℃/min, the temperature is kept for 1-10 h for degreasing, and then two-stage sintering is performed, wherein the first-stage sintering temperature is 750-1250 ℃, and the temperature is kept for 0.1-30 h; and then heating or cooling for second-stage sintering, wherein the sintering temperature is 750-1300 ℃, the heat preservation time is 0.1-30 h, then the temperature is controlled to be 600 ℃, and then the material is naturally cooled to the room temperature, the heating rate before the two-stage sintering is 10-500 ℃/min, and the cooling rate is controlled to be 1-50 ℃/min.

10. The method for preparing transparent calcium phosphate bioceramic through atmosphere protection and atmospheric sintering according to claim 4, wherein in step S3, deionized water is continuously injected into the furnace at a rate of 0-10 ml/min when the temperature of the furnace chamber rises to 700 ℃, and the deionized water injection is stopped when the temperature of the furnace chamber drops to 600 ℃ after the heat preservation is finished.

Technical Field

The invention relates to the technical field of biomedical materials, in particular to a method for preparing transparent calcium phosphate bioceramic by atmosphere protection and normal pressure sintering.

Background

Hydroxyapatite (HA), β -tricalcium Phosphate (β -TCP) and hydroxyapatite/β -tricalcium Phosphate two-phase composite ceramic (BCP for short) have excellent biocompatibility, can quickly conduct bone cell regeneration, can be directly bonded with bone without an intermediate medium, serve as a good biological hard tissue filling, repairing and replacing material, and are widely applied in clinic.

When the calcium phosphate bioceramic with certain light transmittance is used as a cell culture substrate, the biological properties of cell growth, proliferation, differentiation and the like can be directly observed in real time by using a transmission optical microscope without dyeing cells, and the method has profound significance for evaluating the osteogenic capacity of the calcium phosphate bioceramic implanted in vivo and exploring the interaction mechanism of the cells and the substrate in vitro. Meanwhile, the transparent calcium phosphate biological ceramic has higher mechanical strength and aesthetic property, and can also be used in the field of repairing tooth roots, dental pulp, artificial eyes and the like.

It is well known that when light passes through a medium, the intensity of the light is attenuated by absorption, scattering, refraction, and the like. For transparent ceramics, this attenuation, in addition to being composition-dependent, depends primarily on the microstructure, with grain boundaries and residual porosity being the primary factors affecting light transmission. In general, many pores are formed in the ceramic in the final sintering stage due to rapid growth of crystal grains, and the pores at the grain boundaries can be discharged along with the movement of the grain boundaries, but the closed pores in the crystal are difficult to remove particularly when the closed pores contain phases such as water vapor, nitrogen and carbon. Therefore, since the refractive indexes of the phases at both sides of the pore interface are different, refraction and reflection of light occur, thereby reducing the light transmittance of the ceramic.

The data show that the refractive indexes of HA and β -TCP are very close to each other, namely 1.64-1.65 and 1.63 respectively, so that the transparent BCP two-phase composite ceramic can be obtained through process control.

In order to achieve the above object, the main methods for preparing transparent calcium phosphate ceramics include hot pressing sintering, hot isostatic pressing sintering, microwave sintering and pulse current sintering, Michel Deschamps et al report the preparation of pure β -TCP, pure HA, β -TCP/20 wt% HA (BCP20), β -TCP/40 wt% HA (BCP40), β -TCP/60 wt% HA (BCP60) and β -TCP/80 wt% HA (BCP80) in the literature (Processing and sintering of biphasic calcium phosphate ceramics, microwave sintering and pulse current sintering, and sintering at 1000-Ar 150MPa, wherein sintering is performed at 1000-Ar-150 MPa₂CN1793022 discloses a method for preparing transparent β -tricalcium phosphate biological ceramic material, which adopts discharge plasma sintering technology to obtain compact and transparent β -tricalcium phosphate biological ceramic material, but the method still needs pressure-assisted sintering in the sintering process.

Therefore, the traditional technologies such as hot-pressing sintering, hot isostatic pressing sintering, microwave sintering, pulse current sintering and the like mostly need to be sintered under special conditions such as vacuum, argon and nitrogen atmosphere or electric pulse, pressure assistance, microwave and the like, the operation procedure is complex, the equipment investment and technical requirements are high, batch production cannot be realized, the process difficulty is greatly increased, and the production cost is increased.

Disclosure of Invention

The invention aims to provide a method for preparing transparent calcium phosphate bioceramic by atmosphere protection and normal pressure sintering.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for preparing transparent calcium phosphate bioceramic through atmosphere protection and normal pressure sintering is characterized in that high-purity nano hydroxyapatite and/or high-purity nano β -tricalcium phosphate powder is used as a raw material, the transparent calcium phosphate bioceramic with the light transmittance of 50-95% is obtained through segmented high-temperature normal pressure sintering, and water vapor protection can be selected in the sintering process.

As a further improved technical scheme of the invention, the transparent calcium phosphate bioceramic is hydroxyapatite, β -tricalcium phosphate single-phase or hydroxyapatite/β -tricalcium phosphate two-phase composite ceramic.

As a further improved technical scheme of the invention, the relative density of the transparent calcium phosphate bioceramic is more than 99.5%, and the grain size of each phase is less than 10 μm.

As a further improved technical scheme of the invention, the method comprises the following steps:

s1, weighing the high-purity nano hydroxyapatite and/or high-purity nano β -tricalcium phosphate powder according to different proportions of two phases of hydroxyapatite and β -tricalcium phosphate, mixing, ball-milling, pulping, and performing spray granulation;

s2, filling the granulated powder into a die, performing prepressing molding by using a dry press, and then performing cold isostatic pressing to obtain a blank body, wherein the relative density of the blank body is more than 55%;

s3, placing the blank in an electric furnace for sectional sintering, and optionally slowly injecting deionized water into the hearth by using a peristaltic pump to sinter the blank in a high-temperature water vapor environment;

and S4, performing surface grinding and polishing machining treatment on the sintered transparent calcium phosphate bioceramic.

As a further improved technical scheme of the invention, the purity of the high-purity nano hydroxyapatite and the high-purity nano β -tricalcium phosphate powder is more than 99.9 percent, and the grain size of each powder is 10-300 nm.

As a further improved technical scheme, the high-purity nano-hydroxyapatite and/or high-purity nano- β -tricalcium phosphate powder in the step S1 is mixed, added with a proper amount of dispersing agent and defoaming agent, and then ball-milled, zirconia balls are used as ball-milling media, ethanol or deionized water is used as ball-milling solvent, the mass ratio of the mixed powder to the ball-milling media to the ball-milling solvent is 1: 1-5: 1-3, the rotating speed of the ball mill is 100-400 r/min, and the ball-milling time is 1-10 hours.

As a further improved technical scheme of the invention, after the high-purity nano-hydroxyapatite and/or high-purity nano- β -tricalcium phosphate powder in the step S1 is mixed, ball-milled and pulped, the microspheres with the diameter of 10-200 microns are obtained through spray granulation.

As a further improved technical scheme of the invention, the pressure of the pre-pressing molding in the step S2 is 20-50 MPa, and the pressure of the cold isostatic pressing molding is 100-350 MPa.

As a further improved technical scheme, in the step S3, firstly, the temperature is raised to 350-650 ℃ at the speed of 1-5 ℃/min, the temperature is kept for 1-10 h for degreasing, and then two-stage sintering is carried out, wherein the first-stage sintering temperature is 750-1250 ℃, and the temperature keeping time is 0.1-30 h; and then heating or cooling for second-stage sintering, wherein the sintering temperature is 750-1300 ℃, the heat preservation time is 0.1-30 h, then the temperature is controlled to be 600 ℃, and then the material is naturally cooled to the room temperature, the heating rate before the two-stage sintering is 10-500 ℃/min, and the cooling rate is controlled to be 1-50 ℃/min.

As a further improved technical scheme of the invention, in step S3, when the temperature of the hearth rises to 700 ℃, deionized water is continuously injected into the furnace, the injection rate is 0-10 ml/min, and after the heat preservation is finished, the injection of the deionized water is stopped when the temperature of the hearth drops to 600 ℃.

Compared with the prior art, the invention has the technical effects that:

(1) the adoption of steam for protection sintering not only is more beneficial to removing closed pores in the crystal, but also can avoid the decomposition of hydroxyapatite and the formation of impurity phases;

(2) no sintering aid is added, no impurity pollution is caused, and the sintering process does not need special conditions (vacuum environment, high pressure or special gas and special equipment) requirements;

(3) the obtained transparent calcium phosphate biological ceramic has the light transmittance of 50-95%, the grain size of each phase is less than 10 mu m, the bending strength is not lower than 125MPa, and the requirement of clinical surgical implantation can be met.

(4) The process is simple, the equipment investment is small, the production period is short, and the requirement of batch production can be met;

drawings

FIG. 1 is a schematic flow chart of a method for preparing a transparent calcium phosphate bioceramic by atmosphere protection and atmospheric pressure sintering according to an embodiment of the present invention;

FIG. 2 is an X-ray diffraction spectrum of a transparent calcium phosphate bioceramic.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments shown in the drawings. These embodiments are not intended to limit the present invention, and variations in formulation, phase composition, organization, method, or function, which may be made by one of ordinary skill in the art according to these embodiments, are within the scope of the invention.

Transparent calcium phosphate bioceramics (HA, β -TCP or BCP) are prepared by special sintering techniques such as hot-pressing sintering, microwave sintering, hot isostatic pressing sintering and pulse current sintering, and aims to reduce sintering temperature (lower than 1100 ℃) to realize densification while refining grains, and to prevent calcium phosphate from decomposition reaction at too high sintering temperature to form impurity phase, wherein the decomposition reaction principle is as follows:

Ca₁₀(PO₄)₆(OH)₂→3β-Ca₃(PO₄)₂+CaO+H₂o (decomposing water vapor)

According to the method for preparing the transparent calcium phosphate biological ceramic by atmosphere protection and normal pressure sintering, provided by the invention, the calcium phosphate biological ceramic with better transparency can be obtained by high-temperature normal pressure segmented sintering at 750-1300 ℃ under the condition of water vapor. In comparison, although the highest temperature of the segmented sintering is higher than the sintering temperature adopted by special technologies such as hot-pressing sintering, microwave sintering, hot isostatic pressing sintering, pulse current sintering and the like, the hydroxyapatite is ensured not to be decomposed even at a higher sintering temperature due to the introduction of the water vapor protection. Meanwhile, the high-temperature sintering is carried out under the condition of water vapor, so that the water vapor in the closed pores in the crystal easily enters HA crystal lattices, and the shrinkage and densification of the micropores in the crystal are facilitated. And secondly, the method for preparing the transparent calcium phosphate bioceramic through atmosphere protection and normal pressure sintering further adopts 750-1300 ℃ sectional sintering, and can realize densification and further refinement of crystal grains of each phase by controlling the first-stage sintering temperature and the second-stage sintering temperature and time. Therefore, the method for preparing the transparent calcium phosphate bioceramic through atmosphere protection and normal pressure sintering, provided by the invention, has a positive effect of simultaneously improving the biocompatibility, strength and light transmittance of the calcium phosphate bioceramic.

Referring to fig. 1 to 2, a method for preparing transparent calcium phosphate bioceramic by atmosphere protection and normal pressure sintering is provided, which comprises the steps of taking high-purity nano hydroxyapatite and/or high-purity nano β -tricalcium phosphate powder as a raw material, sintering at high temperature and normal pressure in a segmented manner to obtain the transparent calcium phosphate bioceramic with the light transmittance of 50-95%, and optionally carrying out water vapor protection in the sintering process.

Further, the transparent calcium phosphate bioceramic is hydroxyapatite, β -tricalcium phosphate single-phase or hydroxyapatite/β -tricalcium phosphate two-phase composite ceramic.

Further, the transparent calcium phosphate bioceramic has a relative density of more than 99.5% and a grain size of each phase of less than 10 μm.

Further, the method comprises the following steps:

s1, weighing the high-purity nano hydroxyapatite and/or high-purity nano β -tricalcium phosphate powder according to different proportions of two phases of hydroxyapatite and β -tricalcium phosphate, mixing, ball-milling, pulping, and performing spray granulation;

s2, filling the granulated powder into a die, performing prepressing molding by using a dry press, and then performing cold isostatic pressing to obtain a blank body, wherein the relative density of the blank body is more than 55%;

s3, placing the blank in an electric furnace for sectional sintering, and optionally slowly injecting deionized water into the hearth by using a peristaltic pump to sinter the blank in a high-temperature water vapor environment;

and S4, performing surface grinding and polishing machining treatment on the sintered transparent calcium phosphate bioceramic.

Furthermore, the purity of the high-purity nano hydroxyapatite and the high-purity nano β -tricalcium phosphate powder is more than 99.9 percent, and the grain size of each powder is 10-300 nm.

Further, in the step S1, the high-purity nano hydroxyapatite and/or high-purity nano β -tricalcium phosphate powder is mixed, added with a proper amount of dispersant and defoamer, and then ball-milled, zirconia balls are used as a ball-milling medium, ethanol or deionized water is used as a ball-milling solvent, the mass ratio of the mixed powder to the ball-milling medium to the ball-milling solvent is 1: 1-5: 1-3, the rotating speed of the ball mill is 100-400 r/min, and the ball-milling time is 1-10 hours.

Further, after the high-purity nano hydroxyapatite and/or high-purity nano β -tricalcium phosphate powder is mixed, ball-milled and pulped in the step S1, the microspheres with the diameter of 10-200 microns are obtained through spray granulation.

Further, the pressure of the pre-pressing molding in the step S2 is 20-50 MPa, and the pressure of the cold isostatic pressing molding is 100-350 MPa.

Further, in the step S3, firstly, the temperature is raised to 350-650 ℃ at the speed of 1-5 ℃/min, the temperature is kept for 1-10 hours for degreasing, and then two-stage sintering is carried out, wherein the first-stage sintering temperature is 750-1250 ℃, and the temperature keeping time is 0.1-30 hours; and then heating or cooling for second-stage sintering, wherein the sintering temperature is 750-1300 ℃, the heat preservation time is 0.1-30 h, then the temperature is controlled to be 600 ℃, and then the material is naturally cooled to the room temperature, the heating rate before the two-stage sintering is 10-500 ℃/min, and the cooling rate is controlled to be 1-50 ℃/min.

Further, in step S3, when the temperature of the furnace chamber rises to 700 ℃, continuously injecting deionized water into the furnace at an injection rate of 0-10 ml/min, and after the heat preservation is finished, stopping injecting deionized water when the temperature of the furnace chamber drops to 600 ℃.