Zinc-based composite material for medical implantation as well as preparation method and application of zinc-based composite material
By embedding iron reinforcement in zinc-based materials and covering them with tantalum coatings, and using electrode heating and sputtering technology to form an interface bond, the problem of simultaneous optimization of the mechanical properties and degradation properties of zinc-based materials was solved, achieving the effects of high strength and controllable degradation.
Patent Information
- Application Number
- CN202510928782.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-07
- Publication Date
- 2025-10-14
AI Technical Summary
Existing zinc-based medical implant materials are difficult to achieve simultaneous optimization between mechanical properties and degradation properties, and there are problems such as uneven degradation, weak interface bonding, and high cost.
By coupling electrode heating with sputtering technology, iron reinforcements are embedded in the zinc matrix and covered with a tantalum coating on the outside to achieve interface diffusion bonding, forming a gradient transition layer, and simultaneously improving the material's compressive strength and degradation performance.
The compressive yield strength of zinc-based composite materials was increased by more than 3 times, the degradation rate was reduced by 70%, the pH value of the degradation products was stable, local alkalinization was avoided, and the mechanical strength and biodegradability requirements of medical implant materials were met.
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Figure CN120776248A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of biomedical materials, and in particular to a zinc-based composite material for medical implantation, a preparation method thereof, and applications thereof. Background Art
[0002] Traditional medical implant materials (such as stainless steel and titanium alloys) require a second surgery to remove, which is associated with long treatment cycles, high costs, and the risk of postoperative complications. Biodegradable metal materials (such as magnesium, zinc, and iron-based alloys) have become a research hotspot due to their degradability and biocompatibility. Zinc-based materials are considered ideal candidate materials because of their moderate degradation rate (standard degradation potential -0.76V) and no hydrogen release. However, the mechanical properties of pure zinc are insufficient (compressive strength <100MPa), and the degradation rate does not match the bone growth rate, which can easily lead to excessive local zinc ion concentration. Existing technologies improve material properties through alloying (such as Zn-Ti) or composite reinforcement (such as Zn / hydroxyapatite combination), but these methods have obvious defects: uneven distribution of reinforcements, weak interface bonding, complex and costly surface modification processes, and difficulty in achieving simultaneous optimization of mechanical strengthening and degradation properties. Summary of the Invention
[0003] The purpose of the present invention is to solve the defects in the prior art and provide a material that can achieve simultaneous strengthening and degradation.
[0004] In order to achieve the above-mentioned objectives, the present invention provides a zinc-based composite material for medical implants, wherein the zinc-based composite material has a zinc matrix as a core and an iron reinforcement embedded inside. Interface diffusion bonding between the two is achieved by heating, and the surface of the zinc matrix is covered with a tantalum coating; the coverage area of the tantalum coating on the outside of the zinc matrix accounts for 10% to 40%; the zinc matrix and the iron reinforcement are connected by a cathode electrode to the iron reinforcement for resistance heating, and the interface bonding strength obtained is 300 to 520 MPa; the tantalum coating is formed by sputtering a cylindrical tantalum target material set on the outside of the zinc matrix.
[0005] This method utilizes a coupled electrode heating and sputtering technology to achieve reinforcement sintering, matrix densification, and surface modification in a single step. Internal iron reinforcements share the load and slow matrix degradation. Cathode resistance heating utilizes zinc's high thermal expansion coefficient to fill interfacial gaps, promoting Zn-Fe interdiffusion and increasing interfacial bonding strength. The source sputters a Ta target to form a dense coating and gradient transition layer, inhibiting initial degradation and guiding uniform degradation, avoiding localized alkalization. This one-step process also avoids interface contamination associated with multiple-step processes.
[0006] The present invention achieves simultaneous degradation cycle regulation and compression strength improvement through the coupling parameter optimization and interface diffusion process of electrode heating and sputtering technology, meeting the requirements of medical implant materials for mechanical strength and biodegradability, and filling a technological gap.
[0007] Through process exploration, the present invention discovered the key parameter affecting degradation performance - the surface coverage area of the tantalum coating, thereby providing different medical implant materials in a targeted manner.
[0008] When used in cardiovascular stent materials, the coverage area of the above-mentioned tantalum coating on the outside of the zinc substrate accounts for 10% to 30%.
[0009] When used in bone repair materials, the coverage area of the tantalum coating on the outside of the zinc substrate accounts for 35% to 40%.
[0010] Furthermore, in some embodiments, preferably, the zinc-based composite material comprises O, Ta, Zn, and Fe, wherein, by molar percentage, the O element content is 34-44%, the Ta element content is 19-36%, the Zn element content is 16-37%, and the Fe element content is 5-10%.
[0011] The present invention also provides a method for preparing the above zinc-based composite material, comprising the following steps:
[0012] (1) Prefabricate a corresponding hole in the center of the zinc matrix along the axial direction, insert the iron reinforcement into the hole, and complete the assembly of the zinc matrix and the columnar reinforcement;
[0013] (2) placing the assembled zinc substrate in a vacuum chamber, connecting the iron reinforcement to the cathode electrode, and setting a cylindrical Ta target connected to the source electrode outside the zinc substrate;
[0014] (3) starting the cathode electrode to perform resistance heating on the iron reinforcement, and synchronously starting the source electrode to sputter the Ta target material, so that Ta ions are deposited on the surface of the zinc substrate to form a gradient transition layer;
[0015] (4) By regulating the cathode resistance heating temperature and heating time, the interface bonding strength is adjusted to achieve interface diffusion bonding between the iron reinforcement and the zinc matrix, and uniform sintering is completed simultaneously; and by regulating the sputtering voltage and time, the coverage area ratio of the tantalum coating on the outside of the zinc matrix is adjusted to obtain the zinc-based composite material.
[0016] Wherein, in step (4), the sputtering voltage is 200V to 600V, and the time is 2 to 4 hours.
[0017] When used for cardiovascular stent materials, the sputtering voltage is 200V to 450V, and the time is 2 to 4 hours; or the sputtering voltage is 600V, and the time is 2 to 3 hours.
[0018] When used for bone repair materials, the sputtering voltage is 600 V and the time is 4 hours.
[0019] Furthermore, in the above step (4), the cathode resistance heating temperature is 400° C. to 600° C., and the holding time is 2 to 4 hours.
[0020] The source sputtering parameters in step (4) are: argon flow rate of 30-50 sccm, oxygen flow rate of 3-5 sccm, and sputtering power density of 2-4 W / cm 2 .
[0021] The present invention also provides the application of the zinc-based composite material in medical implant materials, such as bone fixation devices, cardiovascular stents or oral implants.
[0022] Furthermore, the zinc-based composite material can be used as a bone repair material, wherein the coverage area of the tantalum coating on the outside of the zinc matrix accounts for 40%.
[0023] The zinc-based composite material can be used for cardiovascular stent materials, wherein the coverage area of the tantalum coating on the outside of the zinc substrate accounts for 10% to 30%.
[0024] Compared with the prior art, the present invention has the following advantages:
[0025] 1. Structural design: A zinc matrix is embedded with columnar iron reinforcements, which are covered with a Ta gradient coating. The iron reinforcements share the load and delay the degradation of the matrix; the Ta coating inhibits initial degradation and guides uniform degradation.
[0026] 2. Process innovation: By coupling electrode heating with sputtering technology, reinforcement sintering, matrix densification, and surface modification are achieved in a single step. Cathode resistance heating utilizes zinc's high thermal expansion coefficient to fill interfacial gaps and promote Zn-Fe interdiffusion. Source sputtering of the Ta target forms a dense coating and gradient transition layer, avoiding interface contamination associated with multi-step processes.
[0027] 3. Performance synergy: Through the interfacial diffusion bonding between the iron reinforcement and the zinc matrix, the compressive yield strength is ≥350MPa (more than 3 times that of pure zinc); the degradation rate of the matrix is delayed, and the degradation rate is reduced by 70%; at the same time, the Ta coating coverage area regulates the surface degradation uniformity, and the pH value of the degradation product is stable (7.2-7.7), avoiding local alkalinization.
[0028] 4. Product application: The present invention couples electrode heating and sputtering technology to precisely control the coverage area percentage of the tantalum coating, thereby achieving adaptation of the biodegradation rate and the implantation cycle.
[0029] Based on experimental data, the present invention establishes a nonlinear relationship between the Ta coating coverage area percentage (0%-40%) and the biodegradation rate, obtaining a nonlinear correlation model between coverage area and degradation cycle. The model shows that the degradation rate is lowest (0.0007 mg / day) when the coverage area is 40%, and significantly increases (0.0016 mg / day and 0.0019 mg / day) when the coverage area is 10% or 30%, respectively. The degradation time is adapted to 18-24 months. This process can be controlled according to the performance requirements of medical implant materials.
[0030] At the same time, experiments show that when the Ta coating coverage area accounts for 30%, the biodegradation rate is the highest (0.0019 mg / day), the material is completely degraded within 18 months and the compressive strength reaches 402 MPa; when the coverage area accounts for 10%, the degradation time increases to 21 months, and the compressive strength still remains ≥350 MPa.
[0031] This technology is applicable to medical fields such as bone repair and vascular stents. BRIEF DESCRIPTION OF THE DRAWINGS
[0032] Figure 1 Schematic diagram of the structure of the device for preparing the zinc-based composite material of the present invention;
[0033] In the figure, 1-Zn rod, 2-Fe rod, 3-cylindrical tantalum target, 4-electrode rod, 5-tray, 6-stainless steel sheet, 7-insulating ceramic sheet, 8-protective cover;
[0034] Figure 2 This is a schematic diagram of the sputtering principle during the preparation of the zinc-based composite material of the present invention;
[0035] In the figure, an electric field is introduced between the two electrodes of the glow discharge. Under the acceleration of the high-voltage electric field, Ar+ ions collide with the target and release energy, causing the target atoms on the target surface to escape from the target and fly toward the Zn rod, and then deposit on the surface of the Zn rod to form a thin film;
[0036] Figure 3 This is a SEM image of the Zn-Fe interface in the composite material prepared in Example 1; the right image is a partial enlarged image of the left image;
[0037] Figure 4 This is a scan of the intermetallic compound surface of the Zn-Ta composite material prepared in Example 1;
[0038] Figure 5 The degradation rate and pH value change curves of the zinc-based composite materials with different Ta coverage ratios prepared in Example 3 in simulated body fluids;
[0039] Figure 5a is the degradation rate curve with the percentage of Ta coverage: the degradation rate and Ta coverage are nonlinearly related. When the Ta coverage is greater than 0%, the degradation rate is higher than 0.001 mg / day; however, when the Ta coverage increases to 40%, the degradation rate drops to 0.0007 mg / day. Figure 5 b is the curve of pH value changing with the number of days: as the soaking time increases, the pH value also gradually increases, but always maintains between 7.2-7.7.
[0040] Figure 6 Surface morphology of the zinc-based composite materials with different Ta coverage ratios prepared in Example 3 after being immersed in simulated body fluid for 20 days;
[0041] Figure 6 a-10% Ta coverage, b-20% Ta coverage, c-30% Ta coverage, d-40% Ta coverage. DETAILED DESCRIPTION
[0042] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0043] like Figure 1 、 Figure 2 As shown, the preparation method of the zinc-based composite material of the present invention is as follows: first, a hole is prefabricated axially in the center of the zinc rod 1, and then the iron rod 2 is polished to a size that matches the hole and inserted into it to ensure a close fit with the substrate. The gap after insertion is about 0.1mm; then the whole is placed on the insulating ceramic gasket 7, and the gasket below is stacked from top to bottom in the form of stainless steel sheet 6-insulating ceramic gasket 7-stainless steel sheet 6-insulating ceramic gasket 7-tray 5 (the tray is made of stainless steel). The height of the iron rod 2 is slightly greater than the depth of the hole, and the raised part above is connected to the cathode through the electrode rod 4 for cathode resistance heating; at the same time, a cylindrical tantalum target 3 (with a gap of 15mm-22mm) is set around the zinc rod 1 and connected to the source for sputtering. A protective cover 8 is used on the outermost periphery. The entire device is placed in a vacuum chamber, the cathode electrode is started to perform resistance heating on the iron rod 2, and the source electrode is simultaneously started to sputter the Ta target material, so that Ta ions are deposited on the surface of the zinc rod 1 to form a gradient transition layer; by adjusting the heating and sputtering parameters, the interface diffusion bonding between the iron reinforcement and the zinc matrix is achieved, and homogenized sintering is completed simultaneously to obtain a zinc-based composite material with both high mechanical properties and controllable degradation rate.
[0044] Example 1:
[0045] The zinc rod hole had a diameter of 5.5 mm, and a 5.5 mm diameter iron rod was inserted (with a gap of 0.1 mm). The vacuum chamber was evacuated to 2 × 10⁻³ Pa, and the Ta target inter-electrode spacing was adjusted to 22 mm. The cathode was heated to 530°C (93% of the melting point of zinc) and held for 2 hours. The source sputtering parameters were 50 sccm argon flow, 3 sccm oxygen flow, 400 V sputtering voltage, and 2 hours. The mixture was then cooled to room temperature, resulting in a composite material with a 20% Ta coating coverage.
[0046] like Figure 3 As shown in the figure, the interface gap between Zn rod and Fe rod does not exceed 150 μm, indicating that the Zn-Fe interface is tightly bonded.
[0047] Figure 4 The following table shows the EDS analysis results of the composite material surface. The material contains O, Ta, Zn, and Fe elements. The composition of each element is shown in Table 1. The compound composition may be O 11 Ta9Zn4Fe.
[0048] Table 1 Element composition of composite materials
[0049] element At.% O 43.6 Zn 15.8 Ta 35.8 Fe 4.3 .
[0050] Example 2:
[0051] This example tests the effect of holding time on interface bonding strength:
[0052] The zinc rod had a 5.0 mm diameter central hole, into which a 5.0 mm diameter iron rod was inserted. Cathode heating was fixed at a voltage of 350 V and a heating temperature of 500°C, with hold times set at 2, 3, and 4 hours. Source sputtering was also simultaneously initiated at a voltage of 450 V and a sputtering time of 2 hours. After cooling to room temperature in the furnace, zinc-based composite materials with varying interfacial bonding strengths were obtained. Test results showed that after a 2-hour hold, the interfacial bonding strength reached 300 MPa; after a 3-hour hold, the bonding strength reached 380 MPa; and after a 4-hour hold, the bonding strength reached 420 MPa.
[0053] Example 3:
[0054] This example tests the effect of coverage percentage on degradation cycle:
[0055] The diameter of the center hole of the zinc rod is 3.0mm, and an iron rod with a diameter of 3.0mm is inserted into it. The zinc substrate is placed in a vacuum chamber (vacuum degree 5×10-3Pa), the iron rod is connected to the cathode, and the cylindrical Ta target (inter-electrode distance 15mm) is connected to the source. The cathode is heated to 500℃ (90% of the melting point of zinc) and kept warm for 2h; the source sputtering is started synchronously, with an argon flow rate of 30sccm, an oxygen flow rate of 3sccm, sputtering voltages of 250V, 350V, 450V, 600V, inter-electrode distance of 20mm, and time of 4h, respectively, to prepare composite materials with Ta coverage of 10%, 20%, 30%, and 40%, respectively. As Figure 5 The test results are as follows: 10% Ta: biodegradation rate 0.0016 mg / day, complete degradation within 21 months, compressive strength 350 MPa; 20% Ta: biodegradation rate 0.0012 mg / day, complete degradation within 21 months, compressive strength 380 MPa; 30% Ta: biodegradation rate 0.0019 mg / day, complete degradation within 18 months, compressive strength 402 MPa; 40% Ta: biodegradation rate 0.0007 mg / day, complete degradation within 48 months, compressive strength 512 MPa.
[0056] like Figure 6 Shown is the surface morphology of zinc-based composite materials with different Ta coverage ratios after immersion in simulated body fluid for 20 days; it can be seen from the figure that when the Ta coverage is 40%, the degree of degradation of the sample is the lowest.
[0057] Example 4:
[0058] This example tests the effect of heating time on coating coverage:
[0059] The center hole of the zinc rod had a diameter of 5.0 mm, and a 5.0 mm diameter iron rod was inserted. The cathode heating temperature was 500°C, the sputtering voltage was 350 V, and the heating time was set to 1 hour. The sputtering voltage was fixed at 600 V, the interelectrode spacing was 15 mm, and the sputtering time was adjusted to 2, 3, and 4 hours. After 2 hours of sputtering, the coverage was 14%; after 3 hours of sputtering, the coverage was 22%; and after 4 hours of sputtering, the coverage was 38%.
[0060] The present invention couples electrode heating with sputtering technology to clarify the nonlinear relationship between the Ta coating coverage percentage (0%-40%) and the biodegradation rate, and achieves synergistic optimization of degradation and strength based on the interface strengthening of the iron reinforcement (bonding strength ≥380MPa). When the Ta coverage area accounts for 10-30%, the material completely degrades within 18-28 months, with a compressive strength of around 400MPa, meeting the high strength and controlled degradation requirements of cardiovascular stents; when the Ta coverage area accounts for 40%, the material degradation time is >30 months, and the compressive strength is ≥350MPa, making it suitable for bone fixation devices.
Claims
1. A zinc-based composite material for medical implants, characterized in that: The zinc-based composite material has a zinc matrix as its core and an iron reinforcement embedded inside. Interface diffusion bonding is achieved between the two by heating, and the surface of the zinc matrix is covered with a tantalum coating. The coverage area of the tantalum coating on the outside of the zinc matrix accounts for 10% to 40%. The zinc matrix and the iron reinforcement are connected by a cathode electrode to the iron reinforcement for resistance heating, and the interface bonding strength obtained is 300 to 520 MPa. The tantalum coating is formed by sputtering a cylindrical tantalum target material set on the outside of the zinc matrix.
2. The zinc-based composite material for medical implants according to claim 1, characterized in that: The coverage area of the tantalum coating on the outside of the zinc substrate accounts for 10% to 30%.
3. The zinc-based composite material for medical implants according to claim 1, characterized in that: The coverage area of the tantalum coating on the outside of the zinc substrate accounts for 35% to 40%.
4. The zinc-based composite material for medical implants according to claim 1, characterized in that: The zinc-based composite material comprises O, Ta, Zn and Fe, wherein the O content is 34-44%, the Ta content is 19-36%, the Zn content is 16-37% and the Fe content is 5-10% in terms of molar percentage.
5. The method for preparing the zinc-based composite material according to claim 1, characterized in that: The following steps are involved: (1) Prefabricate the corresponding hole in the center of the zinc matrix along the axial direction, insert the iron reinforcement into the hole, and complete the assembly of the zinc matrix and the columnar reinforcement; (2) The assembled zinc substrate is placed in a vacuum chamber, the iron reinforcement is connected to the cathode electrode, and a cylindrical Ta target connected to the source electrode is set outside the zinc substrate; (3) Start the cathode electrode to perform resistance heating on the iron reinforcement, and simultaneously start the source electrode to sputter the Ta target material, so that Ta ions are deposited on the surface of the zinc substrate to form a gradient transition layer; (4) By regulating the cathode resistance heating temperature and heating time, the interface bonding strength is adjusted to achieve interface diffusion bonding between the iron reinforcement and the zinc matrix, and uniform sintering is completed simultaneously; and by regulating the sputtering voltage and time, the coverage area ratio of the tantalum coating on the outside of the zinc matrix is adjusted to obtain the zinc-based composite material.
6. The preparation method according to claim 5, characterized in that In the step (4), the sputtering voltage is 200V to 600V, and the time is 2 to 4 hours.
7. The preparation method according to claim 6, characterized in that In the step (4), the cathode resistance heating temperature is 400° C. to 600° C., and the holding time is 2 to 4 hours.
8. The preparation method according to claim 5, characterized in that The source sputtering parameters in step (4) are: argon flow rate of 30 to 50 sccm, oxygen flow rate of 3 to 5 sccm, and sputtering power density of 2 to 4 W / cm².
9. Use of the zinc-based composite material according to claim 1 in bone repair materials, wherein the coverage area of the tantalum coating on the outside of the zinc substrate accounts for 40%.
10. Use of the zinc-based composite material according to claim 1 in cardiovascular stent materials, wherein the coverage area of the tantalum coating on the outside of the zinc substrate accounts for 10% to 30%.