Method for enhancing mechanics of biomedical zinc-based alloy through barb-shaped eutectic structure

Abstract

The invention relates to a method for enhancing the mechanics of a biomedical zinc-based alloy through a barb-shaped eutectic structure, and belongs to the field of biomedical material manufacturing. The barb-shaped eutectic structure reinforced biomedical zinc-based alloy is composed of zinc powder, aluminum powder (5 wt.%) and tin powder, and the mass percentage of the tin powder is 0.5-3.6 wt.%. The mixture of the zinc powder, the aluminum powder and the tin powder is subjected to mechanical mixing and ball-milling dispersion and then is sintered and formed by electric sparks. The preparation method has the beneficial effects that the barb-shaped eutectic structure is generated, a multi-angle contact surface can be formed between the barb-shaped eutectic structure and the grain boundary of each grain, and more acting points are formed on the surface of the grain boundary, so that the capability of resisting deformation of different degrees is greatly improved, and the mechanical property of the biomedical zinc-based alloy is improved.

Description

Technical Field

[0001] This invention relates to the preparation of biodegradable zinc-based alloy bone implant materials for biomedical use, and belongs to the field of biomedical materials manufacturing. Background Technology

[0002] In recent years, biodegradable zinc metal has attracted increasing attention due to its suitable degradation rate and good biocompatibility. A suitable degradation rate means that the implant will gradually degrade within an appropriate timeframe, adapting to the tissue repair process without adversely affecting normal physiological functions. Biodegradable zinc metal not only has a suitable degradation rate but also degrades well after tissue repair, avoiding the need for secondary surgery for removal. Simultaneously, the good biocompatibility of biodegradable zinc metal is also one of its most noteworthy characteristics. Zinc is an essential trace element in the human body, participating in various biological functions such as gene expression, nucleic acid metabolism, and signal transduction. During bone repair, zinc metal gradually releases zinc ions, which helps promote the proliferation and differentiation of osteocytes, thereby promoting new bone formation. The role of zinc metal in bone tissue further emphasizes its potential advantages in orthopedic applications.

[0003] Although biodegradable zinc metal exhibits a suitable degradation rate and good biocompatibility in vivo, its mechanical properties as a hard alloy material are relatively insufficient. The ultimate compressive strength of pure zinc is only 120 MPa, which undoubtedly affects the load-bearing capacity after implantation and limits the application of biodegradable zinc metal in the manufacture of biomedical materials. Various studies have been searching for methods to improve the mechanical properties of biodegradable zinc metal. Results show that alloying with different elements to promote the formation of eutectic structures is an effective way to significantly improve its mechanical properties. Currently, studies on eutectic structures such as granular, rod-shaped, and layered structures have confirmed that they can improve the mechanical properties of biodegradable zinc. However, these eutectic structures have fewer contact surfaces with grain boundaries and insufficient bonding points, which cannot fully meet the requirements for the mechanical properties of supporting bone tissue repair. Therefore, it is essential to find a novel eutectic structure to enhance the mechanical properties of biodegradable zinc metal. Summary of the Invention

[0004] To address the relatively insufficient mechanical properties of existing biomedical zinc metals, which affect their load-bearing performance after implantation, this invention proposes a method to enhance the mechanical properties of biomedical zinc-based alloys using a hook-shaped eutectic structure. Aluminum and tin are introduced into the biomedical zinc metal. Under the localized high temperature during electric spark sintering, aluminum, with its higher melting point, preferentially precipitates along grain boundaries in the zinc-aluminum eutectic. Tin, with its lowest melting point, remains in a liquid state for a longer period. Under the pressure of electric spark sintering, it flows, dispersing the precipitated aluminum and forming a hook-shaped zinc-tin eutectic with the zinc. Compared to granular and rod-shaped eutectic structures, the hook-shaped eutectic structure can form multi-angle contact surfaces with the grain boundaries and create more stress points on the grain boundary surface, greatly increasing the resistance to deformation of varying degrees, thereby improving the mechanical properties of biomedical zinc-based orthopedic implant materials. Furthermore, the hook-shaped eutectic structure refines the grains of the biomedical zinc-based alloy, forming a denser, non-porous microstructure. Meanwhile, the tin element in the barbed zinc-tin eutectic has a certain stability in vivo and can promote growth and development as well as wound healing, exhibiting good biocompatibility.

[0005] To achieve the goal of enhancing the mechanical properties of biomedical zinc-based alloys through a barbed eutectic structure, this invention provides the following technical solution:

[0006] A method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure is composed of zinc powder, aluminum powder (5 wt.%), and tin powder, wherein the tin powder accounts for 0.5-3.6 wt.% by mass.

[0007] Furthermore, in the method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure, the tin powder comprises 2.0-3.0 wt.% by mass.

[0008] Furthermore, in the method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure, the tin powder has a mass percentage of 2.4 wt.%.

[0009] Furthermore, the tin powder has a size of 15-25 micrometers, the zinc powder has a size of 30-50 micrometers, and the aluminum powder has a size of 20-30 micrometers.

[0010] In a method for enhancing the mechanical properties of biomedical zinc-based alloys using a hook-shaped eutectic structure, under the localized high temperature during electric spark sintering, aluminum in the zinc-aluminum eutectic has a relatively high melting point (660℃) and preferentially precipitates along the grain boundaries. Tin, with the lowest melting point, remains in a liquid state for a longer period (232℃) and flows under the pressure of electric spark sintering. During this flow, the liquid tin not only disperses the precipitated aluminum but also forms a hook-shaped zinc-tin eutectic with zinc. Compared to granular and rod-shaped eutectic structures, the hook-shaped eutectic structure can form multi-angle contact surfaces with each grain boundary and generate more concentrated stress points on the grain boundary surface, significantly improving its resistance to deformation of different degrees, thereby effectively enhancing the mechanical properties of biomedical zinc-based alloys.

[0011] Furthermore, the Vickers hardness of the aforementioned barbed eutectic structure reinforced biomedical zinc-based alloy is 75-90 HV.

[0012] Furthermore, the ultimate compressive strength of the barbed eutectic structure reinforced biomedical zinc-based alloy is 188.31-263.67 MPa.

[0013] The barbed eutectic structure reinforced biomedical zinc-based alloy of the present invention is prepared by the following technical steps:

[0014] Step 1: Mechanical mixing

[0015] After the tin powder is dried at a constant temperature, it is added in equal amounts to a mixture of zinc powder and aluminum powder (5 wt.%) in 2-5 portions and stirred for 25-35 minutes. The mixture is then repeatedly poured into another grinding mortar using two grinding mortars to evenly disperse the tin powder.

[0016] Step 2: Ball milling dispersion

[0017] After mechanical mixing, the zinc, aluminum, and tin mixed powder is loaded into a ball mill for wet ball milling dispersion. The ball-to-powder ratio is 10:1, the rotation speed of the ball mill is 200-350 r / min, and the ball milling time is 180-330 minutes. Every 30-60 minutes of operation, the ball mill is stopped for 3-10 minutes to prevent excessive heat from being generated in the ball mill jar due to friction.

[0018] Step 3: Electrical Discharge Sintering

[0019] The zinc, aluminum, and tin mixed powder, after being dispersed by ball milling, was solidified and formed by electric spark sintering. The sintering temperature was 250-360 degrees Celsius, the sintering pressure was 9-20 kN, and the holding time was 8-25 minutes, thus preparing a hook-shaped eutectic structure reinforced biomedical zinc-based alloy.

[0020] In this invention, the parameters of the electric spark sintering process need to be strictly controlled. If the electric spark sintering temperature is too low, the mixed powder will be difficult to completely melt, and the barbed zinc-tin eutectic will be difficult to form, thus failing to improve its load-bearing performance. If the electric spark sintering temperature is too high, some powder will volatilize during sintering, resulting in poor overall mechanical properties of the formed biomedical zinc-based orthopedic implant.

[0021] In this invention, the content of tin powder needs to be strictly controlled. Although tin, produced by the barbed eutectic structure in biomedical zinc-based orthopedic implants, is an essential trace element for the human body, possesses certain stability in vivo, and can promote growth, development, and wound healing, exhibiting good biocompatibility, excessive tin in the body can cause digestive discomfort and, in severe cases, may affect the human immune system. Therefore, it is necessary to rationally select the tin powder ratio to ensure its safety in zinc-based orthopedic implants.

[0022] Compared with the prior art, the advantages of the present invention are as follows:

[0023] (1) In this invention, biomedical zinc-based alloys are prepared by electric spark sintering. During the instantaneous local high temperature sintering process, aluminum in the zinc-aluminum eutectic has a relatively high melting point and preferentially precipitates along the grain boundary. Tin, which has the lowest melting point, remains in a liquid state for a long time and flows under the pressure of electric spark sintering. During the flow, the liquid tin not only disperses the precipitated aluminum but also forms a hook-shaped zinc-tin eutectic with zinc.

[0024] (2) In this invention, the hook-shaped eutectic structure formed by zinc and tin is a key advantage. Compared with granular and rod-shaped eutectic structures, the hook-shaped eutectic structure can form multi-angle contact surfaces with each grain boundary and create more force points on the grain boundary surface, greatly increasing the ability to resist deformation of different degrees, thereby improving the mechanical properties of zinc-based orthopedic implants for biomedical applications. Zinc-aluminum-tin alloys will be a promising potential alloy for biodegradable implant applications.

[0025] (3) In this invention, the tin element in the barbed zinc-tin eutectic has a certain stability in vivo and can promote growth and development as well as wound healing. At the same time, the zinc element in it is more conducive to promoting the proliferation and differentiation of bone tissue and has good biocompatibility. Attached Figure Description

[0026] Figure 1 The hook-shaped zinc-tin eutectic morphology of the 2.4 wt.% tin-containing biomedical zinc-based alloy in this invention.

[0027] Figure 2 The ultimate compressive strength of the 2.4 wt.% tin-containing biomedical zinc-based alloy in this invention.

[0028] Figure 3The ultimate compressive strength of the 3.2 wt.% tin-containing biomedical zinc-based alloy in this invention.

[0029] Figure 4 The ultimate compressive strength of the 0.8 wt.% tin-containing biomedical zinc-based alloy in this invention.

[0030] Figure 5 The ultimate compressive strength of the 2.8 wt.% tin-containing biomedical zinc-based alloy in this invention.

[0031] Figure 6 The ultimate compressive strength of the tin-containing 2.4 wt.% biomedical zinc-based alloy in this invention, due to excessively high sintering temperature, is...

[0032] Figure 7 This refers to the microscopic surface of the 2.4 wt.% tin-containing biomedical zinc-based alloy in this invention that was not sufficiently stirred. Detailed Implementation

[0033] Example 1

[0034] The average particle size of tin powder is 20 micrometers. 2.4 wt.% of tin powder is weighed and dried at a constant temperature. This is then added in three equal portions to zinc powder (average particle size 35 micrometers) and aluminum powder (average particle size 25 micrometers, 5 wt.%), and stirred for 30 minutes each time. The mixture is repeatedly poured into another grinding bowl using two grinding bowls to evenly disperse the tin powder. After mechanical mixing, the zinc, aluminum, and tin powder mixture is fed into a ball mill for wet ball milling dispersion. The ball-to-powder ratio is 10:1, and the ball mill speed is 250 r / min. During the ball milling dispersion process, the ball mill runs for 50 minutes and then stops for 8 minutes, for a total milling time of 260 minutes. After ball milling dispersion, the zinc, aluminum, and tin powder mixture is solidified using an electric spark sintering process. The sintering temperature is 350 degrees Celsius, the sintering pressure is 15 kN, and the holding time is 10 minutes.

[0035] Results: The barbed zinc-tin eutectic morphology of the biomedical zinc-based alloy prepared by this method is as follows: Figure 1 As shown, after testing with a universal compression testing machine and a Vickers hardness tester, its ultimate compressive strength and Vickers hardness were measured. The ultimate compressive strength was 246.78 MPa. Figure 2 As shown, the Vickers hardness is 81.3 HV.

[0036] Example 2

[0037] The average particle size of tin powder is 20 micrometers. 3.2 wt.% of tin powder is weighed and dried at a constant temperature. This is then added in three equal portions to zinc powder (average particle size 35 micrometers) and aluminum powder (average particle size 25 micrometers, 5 wt.%), and stirred for 30 minutes each time. The mixture is repeatedly poured into another grinding bowl using two grinding bowls to evenly disperse the tin powder. After mechanical mixing, the zinc, aluminum, and tin powder mixture is fed into a ball mill for wet ball milling dispersion. The ball-to-powder ratio is 10:1, and the ball mill speed is 220 r / min. During the ball milling dispersion process, the ball mill runs for 50 minutes and then stops for 8 minutes, for a total milling time of 260 minutes. After ball milling dispersion, the zinc, aluminum, and tin powder mixture is solidified using an electric spark sintering process. The sintering temperature is 350 degrees Celsius, the sintering pressure is 15 kN, and the holding time is 10 minutes.

[0038] Results: The biomedical zinc-based alloy prepared by this method was tested using a universal compression testing machine and a Vickers hardness tester. The results showed that its ultimate compressive strength and Vickers hardness were measured. The ultimate compressive strength was 196.51 MPa. Figure 3 As shown, the Vickers hardness is 79.9 HV.

[0039] Example 3

[0040] The average particle size of tin powder is 20 micrometers. 0.8 wt.% of tin powder is weighed and dried at a constant temperature. This is then added in three equal portions to zinc powder (average particle size 35 micrometers) and aluminum powder (average particle size 25 micrometers, 5 wt.%), and stirred for 30 minutes each time. The mixture is repeatedly poured into another grinding bowl using two grinding bowls to evenly disperse the tin powder. After mechanical mixing, the zinc, aluminum, and tin powder mixture is loaded into a ball mill for wet ball milling dispersion. The ball-to-powder ratio is 10:1, and the ball mill speed is 250 r / min. During the ball milling dispersion process, the ball mill runs for 35 minutes and then stops for 5 minutes, for a total milling time of 200 minutes. After ball milling dispersion, the zinc, aluminum, and tin powder mixture is solidified using an electric spark sintering process. The sintering temperature is 350 degrees Celsius, the sintering pressure is 15 kN, and the holding time is 10 minutes.

[0041] Results: The biomedical zinc-based alloy prepared by this method was tested using a universal compression testing machine, and its ultimate compressive strength was determined to be 210.78 MPa. Figure 4 As shown, the Vickers hardness is 84.3 HV.

[0042] Example 4

[0043] The average particle size of tin powder is 20 micrometers. 2.8 wt.% of tin powder is weighed and dried at a constant temperature. This is then added in three equal portions to zinc powder (average particle size 35 micrometers) and aluminum powder (average particle size 25 micrometers, 5 wt.%), and stirred for 30 minutes each time. The mixture is repeatedly poured into another grinding bowl using two grinding bowls to evenly disperse the tin powder. After mechanical mixing, the zinc, aluminum, and tin powder mixture is fed into a ball mill for wet ball milling dispersion. The ball-to-powder ratio is 10:1, and the ball mill speed is 250 r / min. During the ball milling dispersion process, the ball mill runs for 50 minutes and then stops for 8 minutes, for a total milling time of 260 minutes. After ball milling dispersion, the zinc, aluminum, and tin powder mixture is solidified using an electric spark sintering process. The sintering temperature is 280 degrees Celsius, the sintering pressure is 10 kN, and the holding time is 20 minutes.

[0044] Results: The biomedical zinc-based alloy prepared by this method was tested using a universal compression testing machine, and its ultimate compressive strength was determined to be 216.75 MPa. Figure 5 As shown, the Vickers hardness is 82.1 HV.

[0045] Comparative Example 1

[0046] All other conditions were the same as in Example 1, except that tin powder, zinc and aluminum (5 wt.%) were mixed in a mass ratio of 0.3:99.4 to form a barbed zinc-tin eutectic structure to enhance the biomedical zinc-based alloy. After testing, it was found that there was no obvious barbed eutectic formation inside the sample, and its ultimate compressive strength was 133.94 MPa.

[0047] Comparative Example 2

[0048] All other conditions were the same as in Example 1, except that when tin powder, zinc and aluminum (5 wt.%) were mixed in a mass ratio of 15:90, a biomedical zinc-based alloy could not be sintered. This may be because the thermal expansion and contraction of the tin powder during the electric spark sintering process caused the biomedical zinc-based alloy to expand and crack during sintering, thus preventing it from being formed.

[0049] Comparative Example 3

[0050] All other conditions were the same as in Example 1, except that the electric spark sintering temperature was 800 degrees Celsius, the powder was easily volatile, a biomedical zinc-based alloy was not obtained, no barbed zinc-tin eutectic was formed, and the mechanical properties were significantly reduced. Figure 6 As shown.

[0051] Comparative Example 4

[0052] All other conditions were the same as in Example 1, except that the ball mill speed was 80 r / min and the ball milling time was 50 minutes, resulting in a biomedical zinc-based alloy with obvious defects on its microscopic surface, such as... Figure 7 As shown.

[0053] As can be seen from Examples 1, 2, 3, and 4 and Comparative Examples 1, 2, 3, and 4, the components and preparation process of the present invention constitute an organic whole. When any one or more of these key parameters are outside the scope of protection of the present invention, its effectiveness is significantly reduced. By comparing Examples 1, 2, 3, and 4 of the present invention, we found that the preferred embodiment of the present invention produces unexpectedly significant effects.

Claims

1. A method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure, comprising zinc powder, aluminum powder (5 wt.%), and tin powder, wherein the tin powder comprises 0.5-3.6 wt.% by mass.

2. The method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure according to claim 1, characterized in that: The tin powder has a mass percentage of 2.0-3.0 wt.%.

3. The method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure according to claim 1, characterized in that: The tin powder has a mass percentage of 2.4 wt.%.

4. The method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure according to claim 1, characterized in that: The tin powder has a size of 15-25 micrometers, the zinc powder has a size of 30-50 micrometers, and the aluminum powder has a size of 20-30 micrometers.

5. The method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure as described in claim 1, characterized in that, Includes the following steps: Step 1: Mechanical mixing After the tin powder is dried at a constant temperature, it is added in equal amounts to a mixture of zinc powder and aluminum powder (5 wt.%) in 2-5 portions and stirred for 25-35 minutes to evenly disperse the tin powder. Step 2: Ball milling dispersion After mechanical mixing, the zinc, aluminum, and tin mixed powder is loaded into a ball mill for wet ball milling dispersion. The ball-to-powder ratio is 10:1, the rotation speed of the ball mill is 200-350 r / min, and the ball milling time is 180-330 minutes. Every 30-60 minutes of operation, the ball mill is stopped for 3-10 minutes to prevent excessive heat from being generated in the ball mill jar due to friction. Step 3: Electrical Discharge Sintering The zinc, aluminum, and tin mixed powder, after being dispersed by ball milling, is solidified and formed by electric spark sintering. The sintering temperature is 250-360 degrees Celsius, the sintering pressure is 9-20 kN, and the holding time is 8-25 minutes.

6. The method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure according to claim 1, characterized in that: The ball mill rotates at 250 r / min.

7. The method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure according to claim 1, characterized in that: The electric spark sintering temperature is 250-360 degrees Celsius.

8. The method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure according to claim 1, characterized in that: The electric spark sintering pressure is 9-20 kN.

9. The method for enhancing the mechanical properties of biomedical zinc-based alloys with a barbed eutectic structure according to claim 1, characterized in that: The ultimate compressive strength is 188.31-263.67 MPa.

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