Method for synchronously improving hardness, strength and elongation of medical degradable Zn-Li-x ternary composite plate

Abstract

The application relates to a method for synchronously improving the hardness, strength and elongation rate of a medical degradable Zn-Li-x ternary composite plate, and particularly relates to a melting-casting-extrusion-rolling manufacturing technology of Zn-Li-x (x=Mg / Ag / Fe) alloy. The Zn-Li-x ternary composite plate comprises the following components in percentage by mass: 0.4-0.6% of Li; 0.05-0.15% of x; and the balance of zinc; the x is selected from one of Mg, Ag and Fe; and the preparation method comprises the following steps: taking each component according to the designed component allocation to melt and cast to obtain an ingot; then, the ingot is subjected to homogenizing annealing and extrusion to obtain an extruded rod; the rod is subjected to multi-pass rolling with a variable deformation amount after heat treatment to obtain a composite plate with a thickness of 0.1-1 mm; and finally, a finished product is obtained. The component design is reasonable, the preparation process is simple, and the obtained product simultaneously has high strength and elongation rate and proper hardness.

Description

Technical Field

[0001] This invention relates to a method for simultaneously improving the hardness, strength, and elongation of medical biodegradable Zn-Li-x ternary composite plates, specifically involving the casting-extrusion-rolling manufacturing technology of Zn-Li-x (x=Mg / Ag / Fe) alloys. Background Technology

[0002] With increasing human lifespan and rapid advancements in medical technology, more stringent requirements have been placed on the reliability and lifespan of biodegradable medical materials. Therefore, the design and fabrication technology of biodegradable medical materials has received significant international attention. After years of development, the main biodegradable medical materials currently available are Fe-based alloys, Mg-based alloys, and Zn-based alloys. Extensive research indicates that Zn-based alloys exhibit a moderate degradation rate, allowing them to degrade at an appropriate rate during their service life as biodegradable medical materials. However, most current research focuses on the design of alloy systems and simple plastic deformation. To promote the healthy and rapid development of biodegradable medical materials, research on material system design and biomolecular property evaluation remains a key area of ​​focus.

[0003] The microstructure of Zn alloys mainly consists of a matrix phase (α-Zn) and intermetallic compound phases. The intermetallic phases and their volume fraction, size, and distribution within the Zn matrix significantly influence the mechanical properties of Zn alloys. These microstructural characteristics depend on the preparation and processing methods. Current research has certain limitations. Some studies investigate the effects of different Li contents on the microstructure and mechanical properties, others focus on the biological characteristics of alloys with specific Li contents, and still others only examine the as-cast or final rolled state, neglecting post-processing studies such as extrusion / rolling for Zn-Li binary alloys with different Li contents and subsequent biological characterization. Furthermore, existing publicly available data lacks information on how to simultaneously improve the hardness, strength, and elongation of Zn-0.5Li-x ternary composite plates. Summary of the Invention

[0004] Based on our group's previous research (such as CN108396176A), this invention proposes a method to simultaneously improve the hardness, strength, and elongation of a product while ensuring that the product retains its biological characteristics.

[0005] This invention is the first to further improve the hardness of a product by controlling the amount of rolling deformation, while ensuring that other mechanical properties do not suffer a significant decline.

[0006] This invention discloses a method for simultaneously improving the hardness, strength, and elongation of medical biodegradable Zn-Li-x ternary composite panels; the Zn-Li-x ternary composite panels comprise, by mass percentage, the following components:

[0007] Li 0.4–0.6%;

[0008] x 0.05~0.15%;

[0009] The balance is zinc; x is selected from Mg, Ag, and Fe.

[0010] Its preparation method is as follows:

[0011] Using as-cast Zn-Li-x ternary alloys as the target material, the following steps were performed:

[0012] Step 1: Homogenization Annealing

[0013] The as-cast Zn-Li-x ternary alloy was heated to 250-350℃ and homogenized annealed for 24-60h, and then water quenched to obtain a zinc alloy ingot A with uniform microstructure.

[0014] Step Two: Extrusion

[0015] Zinc alloy ingot A is held at 200-400℃ for 50-80 minutes and then immediately taken out and hot-extruded in an extrusion machine through a die of fixed size to obtain a bar with a diameter between 10-20mm. The extrusion ratio in this process is 5:1-20:1.

[0016] Step 3 Heat Treatment

[0017] The extruded bars are held at 150-300℃ for 0.5-2 hours to obtain aged heat-treated bars.

[0018] Step 4 Rolling

[0019] The heat-treated bars are rolled in multiple passes, with each pass involving a deformation of 10-30%, ultimately yielding a composite plate with a thickness of 0.1-1 mm.

[0020] This invention discloses a method for simultaneously improving the hardness, strength, and elongation of medical biodegradable Zn-Li-x ternary composite plates; the as-cast Zn-Li-x ternary alloy is prepared through the following steps:

[0021] (1) Melting: First, place the high-purity Zn matrix into the melting crucible. After the Zn melts, add high-purity Li metal. After adding, stir for a period of time to ensure that the different components are evenly distributed. When preparing ternary alloys, pay attention to adding the high-purity third element in the same way after stirring and continue stirring. During the melting process, pay attention to preheating the equipment and raw materials to a certain extent. Preheating is generally carried out at 200-300℃. During melting, control the temperature at 400-600℃.

[0022] (2) Casting: After the mixture is stirred evenly, the heating device can be turned off. After the temperature stabilizes, the impurities on the surface of the melt can be removed and then poured into the mold. After it is completely cooled and solidified, it can be demolded to obtain the cast alloy of the expected size.

[0023] This invention provides a method for simultaneously improving the hardness, strength, and elongation of medical biodegradable Zn-Li-x ternary composite plates; in step one, the homogenization annealing temperature is 295–305°C and the homogenization annealing time is 46–50 h.

[0024] This invention provides a method for simultaneously improving the hardness, strength, and elongation of medical biodegradable Zn-Li-x ternary composite plates; in step two, zinc alloy ingot A is kept at 295-305℃ for 60 minutes and then immediately taken out and hot-extruded in an extrusion device using a die of fixed size to obtain a bar with a diameter between 15-17mm.

[0025] This invention provides a method for simultaneously improving the hardness, strength, and elongation of medical biodegradable Zn-Li-x ternary composite plates. In step four, the bar after aging heat treatment is subjected to multiple rolling passes, with the deformation amount in each pass being between 10-30%. The deformation amount in the first rolling pass is greater than the deformation amount in any subsequent rolling pass, and the deformation amount in the nth rolling pass is greater than the deformation amount in the (n+1)th rolling pass.

[0026] or

[0027] This invention discloses a method for preparing a medical biodegradable Zn-Li-x ternary composite plate with moderate hardness. In step four, the bar after aging heat treatment is subjected to multiple rolling passes, with the deformation amount of each pass between 10-30%. The deformation amount of the first rolling pass is less than the deformation amount of any subsequent rolling pass; and the deformation amount of the nth rolling pass is less than the deformation amount of the (n+1)th rolling pass.

[0028] When using a Zn-Li-Mg as-cast alloy containing 0.5 wt% Li and 0.1 wt% Mg,

[0029] Homogenization annealing was performed at 300℃ for 48 hours, followed by room temperature water quenching to obtain a homogeneous Zn-0.5%Li-0.1%Mg alloy ingot. The ingot was then held at 300℃ for 1 hour and immediately extruded through a die of fixed dimensions in an extrusion apparatus to obtain bars. The extrusion ratio was approximately 10:1. The extruded bars were then subjected to artificial aging heat treatment at 200℃ for 1 hour. Finally, the artificially aged bars were further processed... The material undergoes five rolling passes, with each pass containing a deformation of 30%-10%, and the initial deformation is 30%. The deformation decreases with each pass, and the final deformation is 10%, resulting in a Zn-0.5%Li-0.1%Mg composite sheet. The hardness, modulus, tensile strength, and elongation of this Zn-0.5%Li-0.1%Mg composite sheet are 1.01 GPa, 142.37 GPa, 306.5 MPa, and 27.9%, respectively.

[0030] When using a Zn-Li-Mg as-cast alloy containing 0.5wt% Li and 0.1% Mg, the homogenization annealing temperature is 300℃ for 48 hours, followed by room temperature water quenching to obtain a homogeneous Zn-0.5%Li-0.1%Mg alloy ingot. The ingot is then held at 300℃ for 1 hour and immediately removed for hot extrusion through a die of fixed dimensions in an extrusion apparatus to obtain bars. The extrusion ratio in this process is approximately 10:1. The extruded bars are then subjected to artificial aging heat treatment at 200℃ for 1 hour. Finally, the bars after artificial aging heat treatment were rolled in 5 passes, with the deformation amount in each pass between 30% and 10%, and the initial deformation amount being 10%. The number of rolling passes was 5, with the deformation amount increasing each time. The deformation amount in the last rolling pass was 30%, resulting in a Zn-0.5%Li-0.1%Mg composite plate. The hardness, modulus, flexural strength, and elongation of this Zn-0.5%Li-0.1%Mg composite plate were 0.98GPa, 136.43GPa, 318.6MPa, and 26.8%, respectively.

[0031] When using a Zn-Li-Ag as-cast alloy containing 0.5wt% Li and 0.1% Ag, the homogenization annealing temperature is 300℃ and the time is 48h. A Zn-0.5%Li-0.1%Ag alloy ingot with uniform microstructure is obtained by room temperature water quenching. The obtained ingot is then held at 300℃ for 1h and immediately taken out and hot-extruded in an extrusion device through a die of fixed size to obtain a bar. The extrusion ratio in this process is about 10:1. Then, the extruded bar is subjected to artificial aging heat treatment by holding at 200℃ for 1h. Finally, the bars after artificial aging heat treatment were rolled in 5 passes, with the deformation amount in each pass between 30% and 10%, and the initial deformation amount being 30%. The number of rolling passes was 5, with the deformation amount increasing with each pass, and the deformation amount in the last rolling pass being 10%, to obtain Zn-0.5%Li-0.1%Ag composite plate. The hardness, Young's modulus, bending strength, and elongation of this Zn-0.5%Li-0.1%Ag composite plate were 1.02 GPa, 83.17 GPa, 251.6 MPa, and 92.7%, respectively.

[0032] When using a Zn-Li-Ag as-cast alloy containing 0.5wt% Li and 0.1% Ag, the homogenization annealing temperature is 300℃ and the time is 48h. A Zn-0.5%Li-0.1%Ag alloy ingot with uniform microstructure is obtained by room temperature water quenching. The obtained ingot is then held at 300℃ for 1h and immediately taken out and hot-extruded in an extrusion device through a die of fixed size to obtain a bar. The extrusion ratio in this process is about 10:1. Then, the extruded bar is subjected to artificial aging heat treatment by holding at 200℃ for 1h. Finally, the bars after artificial aging heat treatment were rolled in 5 passes, with the deformation in each pass ranging from 30% to 10%, and the initial deformation being 10%. The number of rolling passes was 5, with the deformation increasing with each pass, and the deformation in the final rolling pass being 30%, resulting in a Zn-0.5%Li-0.1%Ag composite plate. The hardness, Young's modulus, flexural strength, and elongation of this Zn-0.5%Li-0.1%Ag composite plate were 0.99 GPa, 81.36 GPa, 254.8 MPa, and 94.1%, respectively.

[0033] This invention discloses a method for preparing a medical biodegradable Zn-Li-x ternary composite plate with moderate hardness. During the extrusion process, the ingot is extruded into a rod, which can effectively reduce stress concentration and structural defects generated during the extrusion process and significantly improve the mechanical properties of the material.

[0034] This invention discloses a method for preparing a medical biodegradable Zn-Li-x ternary composite material with moderate hardness, which achieves integrated structure and function and is suitable as a promising medical biodegradable implant material.

[0035] The process designed in this invention produces ternary composite plates with high microstructure uniformity, reducing stress concentration in the material matrix.

[0036] This invention enables mass production of materials, which can further reduce production costs.

[0037] Advantages

[0038] I. This invention can achieve uniform element distribution by controlling the melting process;

[0039] Second, the present invention obtains bars by optimizing the extrusion process, which can reduce stress concentration and structural defects caused by uneven force during the extrusion process;

[0040] Third, the preparation process of this invention is simple and low-cost, enabling mass production of materials and further reducing production costs;

[0041] Fourth, the hardness of the product of this invention is moderate; and compared with the cast state, the mechanical properties of the product of this invention are significantly improved. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the preparation route for preparing medical biodegradable Zn-Li-x (x=Mg / Ag / Fe) ternary composite plates in this invention.

[0043] Figure 2 The microstructure and grain size distribution of the Zn-0.5%Li-0.1%Mg composite plate prepared in Example 1 are shown.

[0044] Figure 3 The microstructure and grain size distribution of the Zn-0.5%Li-0.1%Ag composite plate prepared in Example 4 are shown.

[0045] Figure 4 The xRD patterns of the three medical biodegradable alloys obtained in Examples 1, 4 and the comparative example are shown. It can be seen that due to the insufficient content of the added tertiary component, the generated secondary phase cannot be reflected in the xRD pattern.

[0046] Figure 5 The electrochemical corrosion curves of the three medical biodegradable alloys obtained in Examples 1, 4 and the comparative example show that the addition of the third component has a significant effect on regulating the degradation rate of the alloy. Detailed Implementation

[0047] The preparation technology of the medical biodegradable Zn-Li-x (x=Mg / Ag / Fe) ternary composite board of the present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0048] Example 1

[0049] (1) Smelting: First, put 99.4% Zn blocks with a purity of 99.9% into the smelting crucible. After the Zn melts, stir it evenly and then add 0.5% Li particles with a purity of 99.9%. Continue to stir evenly and then add 0.1% Mg blocks with a purity of 99.9%. During the smelting process, pay attention to preheating the equipment and raw materials to a certain extent. The preheating is carried out at 200℃; the smelting temperature is 550℃.

[0050] (2) Casting: After stirring evenly, the heating device can be turned off. After the temperature stabilizes at 500℃, the impurities on the surface of the melt can be removed and then poured into the mold. After it is completely cooled and solidified, it can be demolded to obtain the Zn-0.5%Li-0.1%Mg as-cast alloy of the expected size.

[0051] (3) Homogenization annealing: In order to eliminate the residual stress in the cast alloy, the ingot was homogenized annealed at 300℃ for 48h before extrusion, and then water quenched at room temperature to obtain a Zn-0.5%Li-0.1%Mg alloy ingot with uniform structure.

[0052] (4) Extrusion: After the ingot obtained in step 3 is kept at 300℃ for 1 hour, it is immediately taken out and hot extruded in the extrusion equipment through a die of fixed size to obtain a bar with a diameter of 16mm. The extrusion ratio in this process is about 10:1.

[0053] (5) Heat treatment: The extruded bars are subjected to artificial aging heat treatment by holding them at 200℃ for 1 hour.

[0054] (6) Rolling: The bar from step 5 is rolled in multiple passes, with the deformation amount in each pass between 30% and 10% (the initial deformation amount is 30%, the number of rolling passes is 5, the deformation amount decreases with each pass, and the deformation amount in the last rolling pass is 10%), and finally a Zn-0.5%Li-0.1%Mg composite plate with a thickness of 1mm is obtained.

[0055] The mechanical properties of the biodegradable Zn-0.5%Li-0.1%Mg composite board obtained in this embodiment were tested. Its hardness, Young's modulus, tensile strength, and elongation were 1.01 GPa, 142.37 GPa, 306.5 MPa, and 27.9%, respectively. Its microstructure and grain size distribution are as follows: Figure 2 As shown.

[0056] Example 2

[0057] All other conditions were the same as in Example 1, and the deformation amount in each pass in step (6) was fixed at 20%; the hardness, Young's modulus, flexural strength and elongation of the obtained product were 1.02 GPa, 144.67 GPa, 301.7 MPa and 24.7%, respectively.

[0058] Example 3

[0059] All other conditions were the same as in Example 1. In step (6), the deformation amount of the first pass was 10%, and then gradually increased to 5 passes. The deformation of the last pass was 30%. The hardness, Young's modulus, bending strength and elongation of the obtained product were 0.98 GPa, 136.43 GPa, 318.6 MPa and 26.8%, respectively.

[0060] The comparative examples in Examples 1 and 3 show that, when the composition is exactly the same (i.e., Zn-0.5%Li-0.1%Mg) and other processes are exactly the same, starting with a large deformation and then decreasing the deformation yields the product with the highest elongation. Furthermore, the product exhibits good hardness, elastic modulus, and strength in this case. When a scheme with small variables initially followed by incremental increases is used, the hardness, elastic modulus, and elongation of the resulting product are slightly lower than the previous scheme, but the strength is indeed improved.

[0061] Comparative Example 1

[0062] All other conditions were the same as in Example 1, but steps (3) to (6) were omitted. The hardness, Young's modulus, flexural strength and elongation of the resulting product (i.e. the cast product) were 0.91 GPa, 135.42 GPa, 173.84 MPa and 9.76%, respectively.

[0063] Example 4

[0064] (1) Melting: First, put 99.4% Zn blocks with a purity of 99.9% into the melting crucible. After the Zn melts, stir it evenly and then add 0.5% Li particles with a purity of 99.9%. Continue to stir evenly and then add 0.1% Ag flakes with a purity of 99.9%. During the melting process, pay attention to preheating the equipment and raw materials to a certain extent. The preheating is carried out at 200℃; the melting temperature is 550℃.

[0065] (2) Casting: After stirring evenly, the heating device can be turned off. After the temperature stabilizes at 500℃, the impurities on the surface of the melt can be removed and then poured into the mold. After it is completely cooled and solidified, it can be demolded to obtain the Zn-0.5%Li-0.1%Ag cast alloy of the expected size.

[0066] (3) Homogenization annealing: In order to eliminate residual stress in the cast alloy, the ingot was homogenized annealed at 300℃ for 48h before extrusion, and then water quenched at room temperature to obtain a Zn-0.5%Li-0.1%Ag alloy ingot with uniform structure.

[0067] (4) Extrusion: After the ingot obtained in step 3 is kept at 300℃ for 1 hour, it is immediately taken out and hot extruded in the extrusion equipment through a die of fixed size to obtain a bar with a diameter of 16mm. The extrusion ratio in this process is about 10:1.

[0068] (5) Heat treatment: The extruded bars are subjected to artificial aging heat treatment by holding them at 200℃ for 1 hour.

[0069] (6) Rolling: The bar from step 5 is rolled in multiple passes, with the deformation amount in each pass between 10-30% (the initial deformation amount is 30%, the number of rolling passes is 5, the deformation amount decreases with each pass, and the deformation amount in the last rolling pass is 10%), and finally a Zn-0.5%Li-0.1%Ag composite plate with a thickness of 1mm is obtained.

[0070] The performance of the biodegradable Zn-0.5%Li-0.1%Ag ternary composite material obtained in this embodiment was tested. Its hardness, modulus, tensile strength, and elongation were 1.02 GPa, 83.17 GPa, 251.6 MPa, and 92.7%, respectively. Its microstructure and grain size distribution are as follows: Figure 3 As shown.

[0071] Example 5

[0072] All other conditions were the same as in Example 4, and the deformation amount in each pass in step (6) was fixed at 20%; the hardness, modulus, flexural strength and elongation of the obtained product were 1.04 GPa, 88.17 GPa, 241.6 MPa and 83.2%, respectively.

[0073] Example 6

[0074] All other conditions were the same as in Example 4. In step (6), the deformation amount of the first pass was 10%, and then gradually increased to 5 rolling passes. The deformation of the last rolling pass was 30%. The hardness, modulus, bending strength and elongation of the obtained product were 0.99 GPa, 81.36 GPa, 254.8 MPa and 94.1%, respectively.

[0075] The comparative examples in Examples 4 and 6 show that, with identical compositions (i.e., Zn-0.5%Li-0.1%Ag) and identical processes, starting with a large deformation followed by a decreasing deformation yields a product with moderate mechanical properties. When a small variable is used initially, followed by an increasing deformation, the elongation and strength of the resulting product are improved compared to the previous method. Compared to the as-cast state, the overall performance of the product is significantly enhanced.

[0076] Comparative Example 2

[0077] All other conditions were the same as in Example 4, but steps (3) to (6) were omitted. The hardness, modulus, flexural strength and elongation of the resulting product were 0.95 GPa, 76.54 GPa, 185.83 MPa and 16.92%, respectively.

Claims

1. A method for synchronously improving the hardness, strength and elongation of a medical degradable Zn-Li-x ternary composite sheet material, characterized in that, Comprising the following steps: (1) Melting: first put 99.4wt% of Zn block with purity of 99.9% into the melting crucible, after the Zn is melted, stir evenly, then add 0.5wt% of Li particles with purity of 99.9%, continue to stir evenly, then add 0.1wt% of Ag sheet with purity of 99.9%, preheat the equipment and raw materials during the melting process, preheat at 200℃; the melting temperature is 550℃; (2) Casting: after stirring evenly, turn off the heating device, after the temperature stabilizes at 500℃, remove the impurities on the surface of the melt, then cast in the mold, after completely cooling and solidifying, demold, get the expected size of Zn-0.5%Li-0.1%Ag as-cast alloy; (3) Homogenization annealing: in order to eliminate the residual stress in the as-cast alloy, the ingot is homogenized at 300℃ for 48h before extrusion, and the microstructure of the Zn-0.5%Li-0.1%Ag alloy ingot is uniform after water quenching at room temperature; (4) Extrusion: the ingot obtained in step (3) is taken out immediately after being kept at 300℃ for 1h, then hot extruded through a fixed size mold in the extrusion equipment to get a rod with a diameter of 16mm, the extrusion ratio in this process is 10:1; (5) Heat treatment: the extruded rod is artificially aged at 200℃ for 1h; (6) Rolling: the rod of step (5) is rolled in multiple passes, the deformation in each pass is between 10-30%, the first deformation is 30%, the rolling number is 5, the deformation in each pass is decreasing, the last rolling deformation is 10%, finally a Zn-0.5%Li-0.1%Ag composite sheet with a thickness of 1mm is obtained.

2. A method for synchronously improving the hardness, strength and elongation of a medical degradable Zn-Li-x ternary composite sheet material, characterized in that, Comprising the following steps: (1) Melting: first put 99.4wt% of Zn block with purity of 99.9% into the melting crucible, after the Zn is melted, stir evenly, then add 0.5wt% of Li particles with purity of 99.9%, continue to stir evenly, then add 0.1wt% of Ag sheet with purity of 99.9%, preheat the equipment and raw materials during the melting process, preheat at 200℃; the melting temperature is 550℃; (2) Casting: after stirring evenly, turn off the heating device, after the temperature stabilizes at 500℃, remove the impurities on the surface of the melt, then cast in the mold, after completely cooling and solidifying, demold, get the expected size of Zn-0.5%Li-0.1%Ag as-cast alloy; (3) Homogenization annealing: in order to eliminate the residual stress in the as-cast alloy, the ingot is homogenized at 300℃ for 48h before extrusion, and the microstructure of the Zn-0.5%Li-0.1%Ag alloy ingot is uniform after water quenching at room temperature; (4) Extrusion: the ingot obtained in step (3) is taken out immediately after being kept at 300℃ for 1h, then hot extruded through a fixed size mold in the extrusion equipment to get a rod with a diameter of 16mm, the extrusion ratio in this process is 10:1; (5) Heat treatment: the extruded rod is artificially aged at 200℃ for 1h; (6) rolling: the bar of step (5) is subjected to multi-pass rolling, the deformation of each pass is between 10-30%, the first deformation is 10%, the rolling number is 5, the deformation of each pass is increased, and the deformation of the last rolling is 30%.

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