A medical high-strength and low-elasticity degradable zinc-titanium composite material with a nano core-shell structure, its preparation method and application

Abstract

The present invention discloses a nano-core-shell structured medical high-strength and low-elasticity zinc-titanium degradable composite material, its preparation method and application, belonging to the technical field of composite materials. The zinc-titanium degradable composite material of the present invention has a core-shell structure, good mechanical properties, good compactness and biodegradable characteristics. Its hardness is higher than that of titanium metal and zinc metal, and the elastic modulus of the material is close to that of human bone. The present invention provides a preparation method for the above-mentioned material. The steps are simple and the preparation is convenient. The spark plasma sintering process is adopted to overcome the technical problem of difficult processing caused by the too large melting point difference between zinc and titanium. When the zinc-titanium degradable composite material is applied to metal implant materials, the "stress shielding" effect after implantation can be effectively solved, providing new ideas for the selection of implant materials.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and particularly relates to a nano-core-shell structured medical high-strength and low-elasticity zinc-titanium degradable composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Degradable metal materials have biocompatibility and biodegradability, and have become an important research direction in the field of medical bioactive implant materials in recent years. Common degradable metal materials include iron, magnesium, and zinc. Iron materials have a relatively high elastic modulus and a slow degradation rate in the human body. When used as an implant material for human load-bearing parts, a "stress shielding" effect will occur. If the bone does not receive appropriate load for a long time, osteoporosis will occur. Magnesium materials degrade too fast and hydrogen gas is generated during the degradation process, which is not conducive to the integration of the implant with human tissues. Zinc materials are essential trace elements in the human body and are involved in the synthesis of various enzymes; and have certain antibacterial ability. More importantly, zinc has a suitable degradation rate in the human body, which can achieve a good match with the bone healing time; at the same time, zinc has a good osteogenic promotion function, can stimulate the proliferation of osteoblasts, and plays an indispensable role in bone metabolism, and is an excellent choice for degradable metal implant materials. However, the mechanical properties of pure zinc are poor, and both the strength and plasticity are difficult to meet the clinical requirements of orthopedic materials, which may lead to the failure of the implant material and cause more serious harm to the patient. At present, many scholars have been committed to improving the mechanical properties of zinc-based biodegradable materials, and alloying is an important method. Available alloy systems such as Zn-Ag and Zn-Li have been widely studied.

[0003] Titanium has excellent biocompatibility and corrosion resistance. Titanium has no toxic or side effects on the human body, and has both low density and excellent mechanical properties, and has been widely used in implant materials. However, pure titanium does not have antibacterial properties, and it is also difficult to establish a close connection with biological tissues after being implanted as a bioinert material. The implant may become loose after long-term use. In addition, the elastic modulus of titanium is still higher than that of human bone, and there is still a "stress shielding" effect after being implanted into the human body as an implant material.

[0004] Alloying titanium and zinc to reduce the elastic modulus is a feasible means to solve the "stress shielding" effect. At present, there is no extensive report on the application of zinc-titanium composite materials. However, due to the large difference in melting points between zinc and titanium, it is difficult to prepare zinc-titanium composite materials that meet the requirements by traditional metal processing processes such as casting. Therefore, it is of great significance to alloy titanium and zinc by using appropriate processing means to prepare composite materials. Summary of the Invention

[0005] In view of the above-mentioned defects of the prior art, in the first aspect of the present invention, a zinc-titanium degradable composite material with good mechanical properties and good compactness is provided; the zinc-titanium degradable composite material has a core-shell structure; the core-shell structure includes a titanium core, a first titanium-zinc compound layer wrapping the titanium core, and a second titanium-zinc compound layer on the outer layer of the first titanium-zinc compound layer; the first titanium-zinc compound layer is composed of TiZn3, and the TiZn3 crystal grains are nanoscale; the second titanium-zinc compound layer is composed of TiZn7.

[0006] In the second aspect of the present invention, a preparation method of a zinc-titanium degradable composite material with simple steps and convenient preparation is provided, including the following steps:

[0007] (1) Zinc powder and titanium powder are mixed evenly according to a ratio to obtain a pre-sintered powder;

[0008] (2) The pre-sintered powder undergoes interatomic diffusion and reaction under the conditions of spark plasma sintering to form a zinc-titanium degradable composite material.

[0009] Spark Plasma Sintering (SPS) is a new type of rapid sintering technology, which can realize heating with current while applying pressure, and can rapidly sinter powder materials into dense bulk materials at relatively low temperatures. In the present invention, through solid-phase diffusion means, the uniformly mixed pre-sintered powder undergoes interatomic diffusion and reaction under the high temperature and high pressure conditions of spark plasma sintering (SPS). Due to the difference in the diffusion rates of titanium and zinc atoms, the pure titanium particles are gradually consumed, and around the pure titanium particles, a metal compound TiZn3 is formed and wraps the pure titanium particles in the form of a shell layer. The grain size of the TiZn3 layer is all at the nanoscale; on the outer layer of TiZn3, an intermetallic compound TiZn7 is formed and wraps the internal particles in the form of a shell layer.

[0010] Preferably, in the step (1), the mass ratio of titanium in the pre-sintered powder ≤ 50 wt.%.

[0011] Preferably, the specific method of the step (2) is as follows: The pre-sintered powder is pressurized and heated under vacuum conditions to reach and undergo interatomic diffusion and reaction under the pressure and temperature conditions of spark plasma sintering, and then naturally cooled to room temperature to form a zinc-titanium degradable composite material with a core-shell structure.

[0012] More preferably, when pressurizing and heating the pre-sintered powder, the pressure is applied first and then the temperature is increased.

[0013] More preferably, the heating rate of the heating is 50 - 100 °C / min.

[0014] Further preferably, the spark plasma sintering is carried out by a one-step reaction method, and the pre-sintered powder is sintered by holding for 20 - 40 min under the conditions of a pressure of 50 - 60 MPa and a temperature of 300 - 400 °C.

[0015] In the third aspect of the present invention, there is provided an application of the zinc-titanium degradable composite material of the first aspect of the present invention or the zinc-titanium degradable composite material prepared by the preparation method of the second aspect of the present invention as a raw material in the preparation of metal implant materials.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0017] The present invention provides a zinc-titanium degradable composite material, which has a core-shell structure, good mechanical properties, good compactness and biodegradable characteristics. Its hardness is higher than that of titanium metal and zinc metal, and the elastic modulus of the material is close to that of human bone.

[0018] The present invention provides a preparation method of a zinc-titanium degradable composite material. The method has simple steps and is convenient to prepare. By adopting the spark plasma sintering process, the technical problem of difficult processing caused by the too large melting point difference between zinc and titanium is overcome, and zinc and titanium are successfully alloyed to form a composite material.

[0019] The present invention also provides an application of a zinc-titanium degradable composite material as a raw material in the preparation of metal implant materials. The elastic modulus of the composite material is close to that of human bone, and applying it to metal implant materials can effectively solve the "stress shielding" effect after implantation, providing a new idea for the selection of implant materials. Description of the Drawings

[0020] Figure 1 It is the scanning electron microscope (SEM) images of Examples 1 - 3, and (a) - (i) represent the images of the products of the corresponding examples at different magnification ratios;

[0021] Figure 2 It is the composition diagrams of the X-ray energy spectrometer composition analysis (EDS) of Examples 1 - 3, and (a) - (c) represent the composition components of the products of the corresponding examples;

[0022] Figure 3 It is the measured density and relative density measurement results of Examples 1 - 5;

[0023] Figure 4 It is the hardness test results of Examples 1 - 5, where the horizontal lines TA1 and pure Zn respectively represent the hardness values of pure titanium and pure zinc;

[0024] Figure 5 It is the test results of the ultimate compressive strength, yield strength and ultimate compression ratio of Examples 1 - 5;

[0025] Figure 6 Elastic modulus test results for Examples 1 to 5;

[0026] Figure 7 Wettability test results for Examples 1 to 3 and Comparative Examples 1 and 2;

[0027] Figure 8 Cytotoxicity test results for Examples 1 to 3 and Comparative Examples 1 and 2, where (a) to (d) represent test results at different dilution ratios; among them, 1 extraction, 1 / 2 extraction, 1 / 4 extraction, 1 / 8 extraction represent the material extract diluted to 1, 1 / 2, 1 / 4, 1 / 8 respectively, and the horizontal line is the cell activity standard. Detailed implementation manners

[0028] The present invention will be further described below by way of examples, but the present invention is not limited to the scope of the described examples. The experimental methods without specific conditions noted in the following examples are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0029] Example 1

[0030] Preparation method of zinc-titanium degradable composite material:

[0031] (1) Mix 10 wt.% of titanium powder with the remaining zinc powder, and then ball mill at 250 r / min and a ball-to-powder ratio of 1:1 for 7 h to make it uniformly mixed, and recover the pre-sintered powder;

[0032] (2) Place the pre-sintered powder in a spark plasma sintering furnace. After evacuating the chamber, first pressurize the pre-sintered powder to 50 MPa, and then heat it at a rate of 100 °C / min to 350 °C. Keep it at this pressure and temperature for 25 min to cause interatomic diffusion and reaction of the pre-sintered powder, and complete the spark plasma sintering; finally, the sintered product is naturally cooled to room temperature, and after cleaning and polishing, a zinc-titanium degradable composite material with a core-shell structure is obtained, which is denoted as Zn-10Ti according to the zinc-titanium ratio of the raw materials.

[0033] Example 2

[0034] Preparation method of zinc-titanium degradable composite material:

[0035] (1) Mix 20 wt.% of titanium powder with the remaining zinc powder, and then ball mill at 250 r / min and a ball-to-powder ratio of 1:1 for 7 h to make it uniformly mixed, and recover the pre-sintered powder;

[0036] (2) Place the pre-sintered powder in a spark plasma sintering furnace. After evacuating the chamber, first press the pre-sintered powder to 50 MPa, and then heat it at a rate of 100 °C / min to 350 °C. Hold it at this pressure and temperature for 25 min to cause interatomic diffusion and reaction of the pre-sintered powder, and complete the spark plasma sintering. Finally, the sintered product is naturally cooled to room temperature, and after cleaning and polishing, a zinc-titanium degradable composite material with a core-shell structure is obtained, denoted as Zn-20Ti according to the zinc-titanium ratio of the raw materials.

[0037] Example 3

[0038] Preparation method of zinc-titanium degradable composite material:

[0039] (1) Mix 30 wt.% of titanium powder with the remaining zinc powder, and then ball-mill it for 7 h under the conditions of 250 r / min and a ball-to-powder ratio of 1:1 to make it uniformly mixed, and recycle to obtain the pre-sintered powder;

[0040] (2) Place the pre-sintered powder in a spark plasma sintering furnace. After evacuating the chamber, first press the pre-sintered powder to 50 MPa, and then heat it at a rate of 100 °C / min to 350 °C. Hold it at this pressure and temperature for 25 min to cause interatomic diffusion and reaction of the pre-sintered powder, and complete the spark plasma sintering. Finally, the sintered product is naturally cooled to room temperature, and after cleaning and polishing, a zinc-titanium degradable composite material with a core-shell structure is obtained, denoted as Zn-30Ti according to the zinc-titanium ratio of the raw materials.

[0041] Example 4

[0042] Preparation method of zinc-titanium degradable composite material:

[0043] (1) Mix 40 wt.% of titanium powder with the remaining zinc powder, and then ball-mill it for 7 h under the conditions of 250 r / min and a ball-to-powder ratio of 1:1 to make it uniformly mixed, and recycle to obtain the pre-sintered powder;

[0044] (2) Place the pre-sintered powder in a spark plasma sintering furnace. After evacuating the chamber, first press the pre-sintered powder to 50 MPa, and then heat it at a rate of 100 °C / min to 350 °C. Hold it at this pressure and temperature for 25 min to cause interatomic diffusion and reaction of the pre-sintered powder, and complete the spark plasma sintering. Finally, the sintered product is naturally cooled to room temperature, and after cleaning and polishing, a zinc-titanium degradable composite material with a core-shell structure is obtained, denoted as Zn-40Ti according to the zinc-titanium ratio of the raw materials.

[0045] Example 5

[0046] Preparation method of zinc-titanium degradable composite material:

[0047] (1) Mix 50 wt.% of titanium powder with the remaining zinc powder, and then ball mill for 7 h under the conditions of 250 r / min and a ball-to-powder ratio of 1:1 to make the mixture uniform, and recover the pre-sintered powder;

[0048] (2) Place the pre-sintered powder in a spark plasma sintering furnace. After the chamber is evacuated, first press the pre-sintered powder to 50 MPa, and then heat it to 350 °C at a rate of 100 °C / min. Keep it at this pressure and temperature for 25 min to cause interatomic diffusion and reaction of the pre-sintered powder, and complete the spark plasma sintering; finally, the sintered product is naturally cooled to room temperature, and after cleaning and polishing, a zinc-titanium degradable composite material with a core-shell structure is obtained, denoted as Zn-50Ti according to the zinc-titanium ratio of the raw materials.

[0049] Example 6

[0050] Preparation method of zinc-titanium degradable composite material:

[0051] (1) Mix 10 wt.% of titanium powder with the remaining zinc powder, and then ball mill for 7 h under the conditions of 250 r / min and a ball-to-powder ratio of 1:1 to make the mixture uniform, and recover the pre-sintered powder;

[0052] (2) Place the pre-sintered powder in a spark plasma sintering furnace. After the chamber is evacuated, first press the pre-sintered powder to 60 MPa, and then heat it to 300 °C at a rate of 50 °C / min. Keep it at this pressure and temperature for 40 min to cause interatomic diffusion and reaction of the pre-sintered powder, and complete the spark plasma sintering; finally, the sintered product is naturally cooled to room temperature, and after cleaning and polishing, a zinc-titanium degradable composite material with a core-shell structure is obtained.

[0053] Example 7

[0054] Preparation method of zinc-titanium degradable composite material:

[0055] (1) Mix 10 wt.% of titanium powder with the remaining zinc powder, and then ball mill for 7 h under the conditions of 250 r / min and a ball-to-powder ratio of 1:1 to make the mixture uniform, and recover the pre-sintered powder;

[0056] (2) Place the pre-sintered powder in a spark plasma sintering furnace. After the chamber is evacuated, first press the pre-sintered powder to 50 MPa, and then heat it to 400 °C at a rate of 100 °C / min. Keep it at this pressure and temperature for 20 min to cause interatomic diffusion and reaction of the pre-sintered powder, and complete the spark plasma sintering; finally, the sintered product is naturally cooled to room temperature, and after cleaning and polishing, a zinc-titanium degradable composite material with a core-shell structure is obtained.

[0057] Comparative Example 1

[0058] Preparation method of pure titanium bulk material:

[0059] Put the titanium powder in a spark plasma sintering furnace. After the chamber is evacuated, first press the titanium powder to 30 MPa, and then heat it to 700 °C at a rate of 100 °C / min. Keep it at this pressure and temperature for 10 min to complete the spark plasma sintering. Finally, the sintered product is naturally cooled to room temperature, and after cleaning and polishing, a pure titanium bulk material is obtained.

[0060] Comparative Example 2

[0061] In this comparative example, commercially available pure zinc metal is used as the pure zinc bulk material for use as a comparative material in the performance test of the zinc-titanium degradable composite material.

[0062] Test Example 1

[0063] Test the various properties of the zinc-titanium degradable composite material prepared in the example.

[0064] Observe the microstructure of the material by scanning electron microscopy (SEM); and determine the composition of the material by energy dispersive spectroscopy (EDS) of X-ray. The results are shown in Figure 1 、 Figure 2 respectively. It can be seen from Figure 1 that a core-shell structure is formed in the products of Examples 1-3; from Figure 2 combined with Figure 1 it can be seen that the inner core of the zinc-titanium degradable composite material is titanium, the TiZn3 layer wraps the titanium core, the TiZn3 grains reach the nanoscale, and the material composition of the outer layer of TiZn3 is TiZn7, and composite materials that meet the requirements are obtained.

[0065] Use a densitometer to measure the density of the material based on the principle of Archimedes' drainage method. The higher the relative density, the higher the sintering density; it can be seen from the test results of Figure 3 that the density of the material is above 96.7%, and most can reach above 98%, indicating a high sintering density.

[0066] Use a Vickers hardness tester to test the hardness. It can be seen from Figure 4 that the hardness of the composite materials in Examples 1-3 is higher than that of titanium, and those in Examples 4-5 are slightly lower than titanium, but are much higher than pure zinc, which can meet the application requirements.

[0067] Use a universal testing machine to test the compressive properties of a cylinder with a sample specification of Φ4mm*8mm. The test contents include mechanical properties such as ultimate compressive strength, yield strength, ultimate compression ratio, and elastic modulus. It can be known from the results of Figure 5 that the materials obtained in the examples have good mechanical properties. It can be seen from Figure 6It can be seen that the elastic modulus of the composite material is between 25 and 35 GPa, and the elastic modulus of human bone is between 4 and 30 GPa, indicating that the composite material is compatible with human bone and can avoid the "stress shielding" effect.

[0068] The wettability of the material surface to deionized water was tested using a contact angle measuring instrument. A contact angle < 90° indicates good wettability of the material. According to Figure 7 the test results, all the composite materials have good wettability.

[0069] The cytotoxicity was tested using the material extract. Figure 8 For the corresponding test results, values above the standard line in the figure indicate that the cytotoxicity of the material meets the specified requirements. When directly culturing cells with the material extract, except for the pure titanium control group in Comparative Example 1 that meets the cytotoxicity requirements, the zinc-based composite materials prepared in the present invention all show strong cytotoxicity due to the relatively high content of Zn element and do not meet the requirements. When the material extract is diluted by half, the materials in Example 1 and Comparative Examples 1 and 2 can meet the cytotoxicity requirements. When the material extract is diluted to 1 / 4, except for factors such as improper cell culture, it can be seen that all materials meet the cytotoxicity requirements at this time.

[0070] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should be within the protection scope determined by the claims.

Claims

1. A zinc-titanium degradable composite material, characterized in that, The zinc-titanium degradable composite material has a core-shell structure; the core-shell structure includes a titanium core, a first titanium-zinc compound layer wrapping the titanium core, and a second titanium-zinc compound layer on the outer layer of the first titanium-zinc compound layer; the first titanium-zinc compound layer is composed of TiZn3, and the grains of the TiZn3 layer are nanoscale; the second titanium-zinc compound layer is composed of TiZn7.

2. A method for preparing the zinc-titanium degradable composite material according to claim 1, characterized in that, It includes the following steps: (1) Zinc powder and titanium powder are mixed evenly according to a ratio to obtain a pre-sintered powder; (2) The pre-sintered powder undergoes interatomic diffusion and reaction under the conditions of spark plasma sintering to form a zinc-titanium degradable composite material.

3. The method according to claim 2, characterized in that: In the step (1), the mass proportion of titanium in the pre-sintered powder is ≤50wt.%.

4. The method according to claim 2, wherein The specific method of the step (2) is as follows: Under vacuum conditions, the pre-sintered powder is pressurized and heated to reach the pressure and temperature conditions of spark plasma sintering, and interatomic diffusion and reaction occur under these conditions, and then it is naturally cooled to room temperature to form a zinc-titanium degradable composite material with a core-shell structure.

5. The method according to claim 4, wherein: When pressurizing and heating the pre-sintered powder, the pressure is applied first and then the temperature is raised.

6. The method according to claim 4, wherein: The heating rate of the heating is 50~100°C / min.

7. The method according to claim 4, characterized in that: The spark plasma sintering adopts a one-step reaction method, and the pre-sintered powder is sintered for 20~40min under the conditions of a pressure of 50~60MPa and a temperature of 300~400°C.

8. Application of a zinc-titanium degradable composite material as described in claim 1 or a zinc-titanium degradable composite material prepared by the method described in any one of claims 2~7 as a raw material in the preparation of a metal implant material.

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