A method for preparing a high-strength Zn / Cu / Mg layered composite material

Abstract

This invention discloses a method for preparing a high-strength Zn / Cu / Mg layered composite material. A pure Cu coating is prepared on a Zn plate using electroplating. Two Zn plates with Cu coatings are then stacked with a Mg plate to obtain a composite plate. The composite plate is then subjected to single-pass cold rolling to obtain a cold-rolled plate. The cold-rolled plate is cut in half lengthwise, stacked, and then subjected to single-pass cold rolling again. This process of cutting, stacking, and single-pass cold rolling is repeated to obtain the Zn / Cu / Mg layered composite material. The Zn / Cu / Mg layered composite material prepared by this invention exhibits a 50%-190% increase in strength compared to rolled pure Zn plates, while maintaining high room-temperature plasticity. Its corrosion resistance is also significantly improved compared to rolled pure Zn plates.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biodegradable zinc alloy, and particularly relates to a preparation method of high-strength Zn / Cu / Mg layered composite material. BACKGROUND

[0002] At present, zinc-based degradable metal materials are considered as potential new biomaterials. Since most magnesium alloys have the defect of too fast degradation speed and iron-based alloys have the defect of too slow degradation speed, the corrosion rate of zinc and its alloys is between the two, and the zinc and zinc-based alloys have moderate degradation rate and good biocompatibility, so they show great potential and advantages as alternative to existing metal implant materials. However, since the mechanical properties of pure zinc are not enough to meet the use as medical implants, the zinc alloy degradable biomaterials are mainly treated by adding alloy elements, rapid solidification, heat treatment and other treatment methods, and through denaturation and other means, the mechanical properties of the zinc alloy are effectively improved on the basis of meeting the biocompatibility.

[0003] ARB was first developed by YSaito in 1998 and successfully applied to pure aluminum, aluminum alloy and interstitial free (IF) steel and a small amount of deformed magnesium alloy. Since then, the cumulative roll bonding process has been developed and applied to the preparation of ultra-fine-grained or nanocrystalline metal layered composite materials. The principle of cumulative roll bonding process: first, the size of the metal plate is treated, the attached oil and the surface oxide layer are removed, so as to realize the good combination of different metals. Then, the initial metal is cross-stacked in the form of A-B-A-B-A, and is rolled at room temperature or below the recrystallization temperature. Under the action of more than 50% reduction, rolling force and friction, the stacked plate is rolled into a whole, and then the rolled plate is cut into the same size, and the same process is repeated for repeated rolling. The cumulative strain can reach a large value, and a large reduction can be obtained in theory. This process breaks through the limitation of traditional rolling reduction, and can continuously prepare metal layered composite material sheet with ultra-fine grain structure. ARB is an interface bonding, solid phase diffusion and strain generation and accumulation rolling process. In the process of cumulative roll bonding, the cumulative strain increases continuously, and the mechanical alloying effect produced not only improves the bonding ability between the heterogeneous interfaces, but also refines the grain size of the component metal layer, thereby improving the mechanical properties of the material and improving the plastic deformation. Compared with other SPD processes, ARB technology has its own outstanding advantages, mainly in: low cost, simple process. Only through ARB modification, without adding alloy elements, high strength can be obtained, which has the same strength as high alloyed alloy. This process has great advantages in reducing production cost and material density and improving the recycling performance of metal materials. In addition, this process does not require special equipment, since the rolling welding has been widely used in metal cladding production, the productivity is high, and large size materials can be produced, which is easy to realize industrial production. Therefore, the cumulative roll bonding process has become the most potential application process in the field of preparing high strength, high toughness, lightweight ultra-fine-grained metal layered composite materials.

[0004] Magnesium (Mg) is an essential element for the human body and one of the most abundant metallic elements. It plays many vital physiological and biochemical roles, existing in various tissues and participating in numerous biological processes. Over 60% of magnesium in the human body is distributed in bones and teeth, forming complexes with bone proteins to promote bone phosphorylation. Because magnesium participates in the hydrolysis of adenosine triphosphate (ATP), it is involved in almost every physiological activity in the body. It is an important cofactor in the metabolism of carbohydrates and fats, and maintains the transmission and normal function of muscles and nerves. Magnesium also has an inhibitory effect on the central nervous system, thus having a sedative effect, and acts on peripheral blood vessels, promoting vasodilation and lowering blood pressure. Furthermore, adding magnesium to zinc matrices can improve zinc's cellular compatibility.

[0005] Copper (Cu) has a certain solid solubility in a zinc matrix. Adding Cu can improve the strength, hardness, plasticity, and antibacterial properties of the alloy. Cu is one of the essential micronutrients in the human body. The content in a healthy adult is about 110-160mg. It is mainly found in human muscles and bones and is closely related to the human skeletal and cardiovascular systems.

[0006] However, in existing technologies, when using pure Mg and pure Zn plates as raw materials and employing a cumulative rolling process to prepare Zn / Mg layered composites, ZnMg intermetallic compounds easily form at the Zn / Mg interface, leading to a decrease in the composite's plasticity. Simultaneously, the formation of the Mg / Zn layer generates a galvanic cell effect during corrosion, accelerating the corrosion rate of the composite. Inserting a pure copper layer between the Mg and Zn interfaces to prepare Zn / Cu / Mg layered composites holds promise for solving this problem. To date, there have been no reports of preparing Zn / Cu / Mg layered composites via laminated rolling, and no reports of Zn / Cu / Mg layered composites exhibiting high strength and excellent corrosion resistance. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the first objective of this invention is to provide a method for preparing a Zn / Cu / Mg layered composite material that combines high strength and excellent corrosion resistance. The method of this invention obtains the Zn / Cu / Mg layered composite material by simply using a cumulative rolling process, and the prepared composite material has high strength.

[0008] The second objective of this invention is to provide a high-strength, corrosion-resistant Zn / Cu / Mg layered composite material prepared by the above-described preparation method.

[0009] The third objective of this invention is to provide an application of a high-strength, corrosion-resistant Zn / Cu / Mg layered composite material prepared by the above-described preparation method.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] This invention discloses a method for preparing a high-strength Zn / Cu / Mg layered composite material. A pure Cu coating is prepared on a Zn plate, and then two Zn plates with Cu coatings and a Mg plate are stacked to obtain a composite plate. The composite plate is subjected to single-pass cold rolling to obtain a cold-rolled plate. The cold-rolled plate is cut into two pieces from the middle, stacked, and then subjected to single-pass cold rolling. This process of cutting-stacking-single-pass cold rolling is repeated to obtain the Zn / Cu / Mg layered composite material.

[0012] The preparation method of this invention involves stacking a Zn plate with a Cu coating and a Mg plate, followed by cold rolling to achieve alloying, thereby obtaining a high-strength Zn-based composite material. The main advantage of this method is that the preferred pure copper coating layer effectively prevents direct contact between the Mg and Zn plates, avoiding the formation of brittle intermetallic compounds. The resulting layered interface hinders the recovery and recrystallization of Zn during rolling, thereby improving the strength of the composite material, especially its corrosion resistance, through interface strengthening and grain refinement. The inventors discovered that if Mg is introduced into the Zn plate through contact instead of first coating it with Cu, the Mg and Zn will alloy, forming a second phase dispersed in the matrix, creating a zinc-magnesium galvanic cell that accelerates the corrosion rate.

[0013] Furthermore, in this invention, Cu is preferred to coat the Zn plate. During the rolling process, Cu and Zn can undergo metallurgical bonding, and a small amount of CuZn5 second phase is generated, which strengthens the matrix. Cu can also metallurgically bond with Mg and generate a small amount of CuMg2 second phase, thereby strengthening the interface. Ultimately, the resulting Zn / Cu / Mg layered composite material can not only improve corrosion resistance but also achieve a significant improvement in mechanical properties. In addition, the addition of Cu can also give the composite material excellent antibacterial properties.

[0014] In a preferred embodiment, the method for preparing a pure Cu coating on the Zn plate is as follows: using a copper plate as the cathode, a zinc plate as the anode, and a copper sulfate solution as the electrolyte, a copper layer is electroplated on the zinc plate to obtain a Zn plate with a copper coating, and then the Zn plate with the copper coating is heat-treated to obtain a Zn plate with a Cu coating.

[0015] In the preferred embodiment described above, a copper layer is electroplated onto the Zn plate using a small amount of Cu, which is sufficient to achieve a uniform and complete coating of the Zn plate. After coating, the Zn plate is heat-treated to reduce the hardness of Cu and eliminate residual stress.

[0016] In a further preferred embodiment, the thickness of the Zn plate is 0.9-1 mm.

[0017] In a further preferred embodiment, after adjusting the pH of the electrolyte to 8.5-9 with ammonia water, electroplating is started. During electroplating, the voltage is controlled at 3.9-1V and the electroplating time is 55-60s.

[0018] In a further preferred embodiment, the copper sulfate solution contains 14-16% copper sulfate by mass.

[0019] Further preferably, the thickness of the copper layer obtained after electroplating is 0.5-1 μm. By controlling the thickness of the copper layer obtained after electroplating to 0.5-1 μm, the final Zn / Cu / Mg layered composite material exhibits optimal performance. If the thickness is too thin, it will cause discontinuity in the encapsulation and prevent the formation of a complete encapsulation.

[0020] In a further preferred embodiment, the heat treatment temperature is 150°-280° and the heat treatment time is 20-40 min.

[0021] In actual operation, the electrolyte temperature is room temperature (e.g., 25°C).

[0022] The inventors discovered that when obtaining a Zn plate with a Cu coating using electroplating, controlling the copper layer thickness to 0.5-1 μm yields the best mechanical properties and corrosion resistance in the resulting Zn / Cu / Mg layered composite plate. If the electroplating time is too short and the copper layer is too thin, it cannot completely coat the surface of the zinc plate.

[0023] A preferred method for preparing a pure Cu coating on a Zn plate involves stacking two 0.5-0.6 mm thick copper plates and a 0.08-0.1 mm thick Mg plate in a Cu / Mg / Cu configuration, then rolling them to obtain a 0.7-0.8 mm thin plate, followed by heat treatment.

[0024] The inventors discovered that by controlling the thickness of the copper plate within the aforementioned range, the resulting Zn / Cu / Mg layered composite material exhibits the best performance.

[0025] In a further preferred embodiment, the heat treatment temperature is 150°-280° and the heat treatment time is 20-40 min.

[0026] In this invention, the purity of the raw materials used—zinc plates, copper plates, and magnesium plates—is ≥99.99%.

[0027] In actual operation, the Zn plate is placed in alcohol and ultrasonically cleaned for 10 minutes to remove surface grease. After air drying, holes are drilled at the four corners of the Zn plate to facilitate the subsequent fixation with copper wire. Next, a round stainless steel brush is used to scrape the contact surface of the Zn plate parallel to the rolling direction to remove surface oxides and impurities. After grinding, the zinc plate is placed in acetone for ultrasonic cleaning to remove residual powder and other impurities.

[0028] In a preferred embodiment, two Zn plates with Cu coating and one Mg plate are stacked together, with the Mg plate placed between the two Cu-coated Zn plates to obtain a composite plate.

[0029] In a preferred embodiment, the thickness of the Mg plate is 0.08-0.1 mm.

[0030] In the preferred embodiment, the deformation amount of the composite plate in a single cold rolling pass is 50%-60%.

[0031] The inventors discovered that by controlling the deformation of the composite plate in a single cold rolling pass within the above-mentioned range, the metal sheet can form a metallurgical bond effectively while avoiding cracking.

[0032] In the preferred embodiment, the cold-rolled sheet is cut into two pieces from the middle, stacked, and then subjected to single-pass cold rolling. The process of cutting-stacking-single-pass cold rolling is repeated, while controlling the deformation of any single-pass cold rolling to be 50%-60%.

[0033] The inventors discovered that by using the above method, cutting the cold-rolled sheet, stacking it, and then cold-rolling it together, the increased thickness provides a protective covering for the sheet, making it less prone to cracking and allowing the sheet to bond better.

[0034] In the preferred embodiment, the number of repeated cutting-lamination-single-pass cold rolling is 1-12 times, preferably 10-12 times.

[0035] The present invention also provides a Zn / Cu / Mg layered composite material prepared by the above preparation method.

[0036] The present invention also provides the application of the Zn / Cu / Mg layered composite material prepared by the above preparation method, wherein the Zn / Cu / Mg layered composite material is used as a biodegradable implant material.

[0037] Beneficial effects

[0038] The preparation method of this invention involves preparing a pure Cu coating on a Zn plate, then laminating it with a Mg plate and cold rolling it to achieve alloying, thereby obtaining a high-strength Zn-based composite material. The main advantage of this method is that the preferred coating metal effectively prevents the formation of brittle intermetallic compounds between the Mg and Zn plates. The resulting layered interface hinders the recovery and recrystallization of Zn during rolling, thereby improving the strength of the composite material, especially its corrosion resistance, through interface strengthening and grain refinement.

[0039] This invention obtains Zn / Cu / Mg layered composite materials simply through layer rolling, and the preparation process is simple, controllable, and easy to industrialize.

[0040] The Zn / Cu / Mg layered composite material prepared by this invention has a 50%-190% improvement in strength compared to rolled pure Zn plate, and its corrosion resistance is also significantly improved compared to rolled pure Zn plate. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0042] Figure 1 The image shows the metallographic microstructure of the Zn / Cu / Mg layered composite material obtained in Example 1.

[0043] Figure 2 The image shows the metallographic microstructure of the Zn / Cu / Mg layered composite material obtained in Example 2.

[0044] Figure 3 Metallographic microstructure of Zn plate after rolling 12 times using the method described in the example.

[0045] Figure 4 The figures show the tensile deformation curves and corresponding tensile property data after rolling in the examples. The black curve represents the tensile deformation curve after rolling electroplated copper, the red curve represents the tensile deformation curve after rolling copper plate, the blue curve represents the tensile deformation curve after rolling pure zinc and pure magnesium plates, the green curve represents the tensile deformation curve after rolling pure zinc and pure copper plates, and the purple curve represents the tensile deformation curve after rolling pure zinc plate.

[0046] Figure 5 The images show the XRD patterns of each pass of the Zn / Cu / Mg layered composite material obtained in Example 1.

[0047] Figure 6 XRD patterns of each pass of the Zn / Cu / Mg layered composite material obtained in Example 2.

[0048] Figure 7 The image shows the polarization curves of the rolled samples in Hanks' solution in the examples. The green curve represents the result of rolling zinc with copper and magnesium plates, while the purple curve represents the result of rolling zinc plates with copper plating with magnesium plates. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0050] Example 1 (Electroplated Cu)

[0051] A 1mm thick Zn plate with 99.99% purity was cut into 50mm long and 25mm wide sheets using wire cutting. The cut sheets were ultrasonically cleaned in alcohol for 10 minutes to remove surface grease. After air drying, holes were drilled at the four corners of the Zn plate to facilitate the subsequent fixation with copper wire. Then, a circular stainless steel brush with a wire diameter of 0.3mm was used to scrape the contact surface of the Zn plate parallel to the rolling direction to remove surface oxides and impurities. After polishing, the Zn plate was ultrasonically cleaned in acetone for 5 minutes to remove residual powder and other impurities. Then, using a copper plate as the cathode, a zinc plate as the anode, and copper sulfate solution as the electrolyte, an external power supply was used. The pH was adjusted to 9 with concentrated ammonia. The electroplating time was 60 seconds, the power supply voltage was 4V, and the temperature was 25℃. Using this method, a copper layer with a thickness of 1μm completely covering the zinc plate was electroplated. Subsequently, the copper-plated Zn plate was vacuum-sealed and heat-treated at 150°C for 30 minutes. After this, a Mg plate was placed between two copper-plated Zn plates in a sandwich structure to obtain a composite plate, which was then fixed with perforated copper wire to prevent the strips from sliding against each other. Next, a single-pass cold rolling process was performed using a two-roll mill, controlling the deformation amount of each pass to 55%. The cold-rolled plate was then cut in half, stacked, and subjected to another single-pass cold rolling. This cutting-stacking-single-pass cold rolling process was repeated 12 times, with the deformation amount of each pass being 50%-60%.

[0052] The composite plate is rolled into a thickness of 1.3 mm. This invention does not require any lubricant treatment. Repeated cold rolling completes the preparation of the final Zn / Cu / Mg layered composite material.

[0053] Specific data

[0054] 1. Figure 1 The image shows the metallographic microstructure of the Zn / Cu / Mg layered composite material obtained in Example 1. Figure 3 Metallographic microstructure of Zn plate after 12 rolling cycles as described in the example. Figure 1 It can be seen that the Zn / Cu / Mg composite material after lamination and rolling is mainly composed of gray striped Zn and white striped Mg, which can clearly distinguish the Zn and Mg regions. The regions are distributed in a continuous and uninterrupted fibrous alternation uniformly.

[0055] 2. Figure 4The tensile deformation curves and corresponding tensile property data after rolling are shown in the examples. The tensile yield strength (YS), tensile ultimate strength (UTS), and elongation of the pure Zn plate after lamination rolling are 95 MPa, 132 MPa, and 82.3%, respectively. The tensile mechanical properties of the Zn-Cu-Mg layered composite material after lamination rolling show a significant improvement, with tensile yield strength (YS), tensile ultimate strength (UTS), and elongation of 286 MPa, 348 MPa, and 12.9%, respectively.

[0056] 3. Figure 5 The XRD patterns of the rolling passes in this example show that Cu and Zn can undergo metallurgical bonding, with a small amount of CuZn5 second phase forming, which strengthens the matrix. Furthermore, Zn and Mg also undergo metallurgical bonding, forming a very small amount of brittle Mg2Zn. 11 The second phase has a strengthening effect on the matrix.

[0057] 4. Electrochemical tests in Hank's solution revealed that the corrosion potential, corrosion current density, and corrosion rate of the pure Zn plate after lamination and rolling were -0.982 V, 7.115 μA / cm², and 105.7 μm / y, respectively; while the corrosion potential, corrosion current density, and corrosion rate of the lamination-rolled Zn / Cu / Mg composite material were -0.987 V and 0.924 μA / cm², respectively. 2 And 32.3 μm / y. It can be found that the Zn / Cu / Mg layered composite material has good corrosion resistance after rolling.

[0058] Example 2 (Cu plate)

[0059] A 1mm thick Zn plate with 99.99% purity was cut into 50mm long and 25mm wide sheets using wire cutting. The cut sheets were ultrasonically cleaned in alcohol for 10 minutes to remove surface grease. After air drying, holes were drilled at the four corners of the Zn plate to facilitate subsequent fixation with copper wire. Then, a circular stainless steel brush with a wire diameter of 0.3mm was used to scrape the contact surface of the Zn plate parallel to the rolling direction to remove surface oxides and impurities. After polishing, the Zn plate was ultrasonically cleaned in acetone for 5 minutes to remove residual powder and other impurities. Then, two Cu plates and one Mg plate were polished and degreased to remove impurities using the same method. Next, they were rolled in Cu / Mg / Cu layers to about 0.8mm. After that, the rolled sample was vacuum sealed and heat-treated at 280°C for 30 minutes. After completion, the rolled sample was placed between two Zn plates in a sandwich structure to obtain a composite plate, which was fixed with perforated copper wire to prevent the strips from sliding against each other. Then, the cold-rolled sheet is cold-rolled in a single pass using a two-roll mill, with the deformation amount controlled at 55%. The cold-rolled sheet is then cut in half, stacked, and cold-rolled in a single pass. This process of cutting, stacking, and cold-rolling in a single pass is repeated 12 times. During this process, the deformation amount of each cold-rolling pass is 50%-60%. The resulting composite sheet has a thickness of 1.3 mm. This invention requires no lubricant treatment and involves repeated cold rolling to complete the final preparation of the Zn / Cu / Mg composite material.

[0060] Implementation effect

[0061] Figure 2 The image shows the metallographic microstructure of the Zn / Cu / Mg layered composite material obtained in Example 2. Figure 3 Metallographic microstructure of Zn plate after 12 rolling cycles as described in the example. Figure 2 As can be seen, the Zn / Cu / Mg layered composite material after lamination rolling mainly consists of white striped Zn, gray striped Mg, and broken elliptical Cu, clearly distinguishing Zn from Mg and Cu. The regions exhibit a continuous, uninterrupted, alternating, and uniform fibrous distribution. The tensile yield strength (YS), tensile ultimate strength (UTS), and elongation of the pure Zn plate after lamination rolling are 95 MPa, 132 MPa, and 82.3%, respectively. The tensile mechanical properties of the Zn / Cu / Mg layered composite material after lamination rolling show a significant improvement, with tensile yield strength (YS), tensile ultimate strength (UTS), and elongation of 271 MPa, 316 MPa, and 10.8%, respectively. Figure 6The XRD patterns of the rolling passes in this example show that Cu and Zn can undergo metallurgical bonding, with a small amount of CuZn5 second phase forming. Cu can also metallurgically bond with Mg, forming a small amount of CuMg2 second phase, thereby strengthening the interface and enhancing the matrix. Furthermore, Zn and Mg also undergo metallurgical bonding, forming a small amount of Mg2Zn. 11 The second phase strengthens the matrix. Electrochemical tests in Hank's solution showed that the corrosion potential, corrosion current density, and corrosion rate of the pure Zn plate after lamination rolling were -0.982 V and 7.115 μA / cm, respectively. 2 The corrosion potential, corrosion current density, and corrosion rate of the laminated Zn / Cu / Mg composite material were -0.955 V, 2.393 μA / cm², and 105.7 μm / y, respectively. 2 And 83.7 μm / y. It can be found that the Zn / Cu / Mg layered composite material has good corrosion resistance.

[0062] Comparative Example 1 (Zn / Cu)

[0063] A 1mm thick Zn plate with 99.99% purity was cut into 50mm long and 25mm wide sheets using wire cutting. The cut sheets were ultrasonically cleaned in alcohol for 10 minutes to remove surface grease. After air drying, holes were drilled at the four corners of the Zn plate to facilitate subsequent fixation with copper wire. Then, a circular stainless steel brush with a 0.3mm diameter wire was used to scrape the contact surface of the Zn plate parallel to the rolling direction to remove surface oxides and impurities. After polishing, the Zn plate was ultrasonically cleaned in acetone for 5 minutes to remove residual powder and other impurities. The same method was used to treat a 0.5mm pure copper plate. After vacuum sealing and heat treatment at 280°C for 30 minutes, the plates were stacked in a Zn / Cu / Zn sandwich structure and fixed with perforated copper wire to prevent the strips from slipping. The cold-rolled sheet is cold-rolled in a single pass using a two-roll mill, with the deformation controlled at 55%. Then, the cold-rolled sheet is cut in half, stacked, and cold-rolled in a single pass. This process of cutting, stacking, and cold-rolling in a single pass is repeated 12 times. During this process, the deformation of each cold-rolled sheet is 50%-60%. The resulting composite sheet has a thickness of 1.3 mm. This invention requires no lubricant treatment and completes the final preparation of the Zn / Cu composite material by repeated cold rolling.

[0064] Implementation effect

[0065] The Zn / Cu composite material after lamination and rolling mainly consists of white striped Zn and gray striped Cu, making it easy to distinguish between Zn and Cu. Most of the Cu fragments are broken. The tensile yield strength (YS), tensile ultimate strength (UTS), and elongation of the pure Zn plate after lamination and rolling are 95 MPa, 132 MPa, and 82.3%, respectively. The tensile mechanical properties of the Zn / Cu layered composite material after lamination and rolling show a significant improvement, with tensile yield strength (YS), tensile ultimate strength (UTS), and elongation of 226 MPa, 271 MPa, and 15.8%, respectively. Electrochemical tests in Hank's solution showed that the corrosion potential, corrosion current density, and corrosion rate of the pure Zn plate after lamination and rolling were -0.982 V and 7.115 μA / cm, respectively. 2 The corrosion potential, corrosion current density, and corrosion rate of the laminated Zn / Cu composite material were -0.802 V and 6.679 μA / cm, respectively, with a value of 105.7 μm / y. 2 And 196.9 μm / y. After Cu addition treatment and heat treatment, it exhibited a faster corrosion rate and poor corrosion resistance.

[0066] Comparative Example 2 (Zn / Mg)

[0067] 1mm thick Zn sheets with 99.99% purity were cut into 50mm long and 25mm wide sheets using wire EDM. The cut sheets were then ultrasonically cleaned in alcohol for 10 minutes to remove surface grease. After air drying, holes were drilled at the four corners of the Zn sheets to facilitate subsequent fixation with copper wire. Next, a circular stainless steel brush with a 0.3mm diameter wire was used to scrape the contact surfaces of the Zn sheets parallel to the rolling direction to remove surface oxides and impurities. After polishing, the Zn sheets were ultrasonically cleaned in acetone for 5 minutes to remove residual powder and other impurities. The same method was used to treat 0.1mm thick pure magnesium sheets, which were then stacked in a Zn / Mg / Zn sandwich structure and secured with perforated copper wire to prevent slippage between the strips. The cold-rolled sheet is cold-rolled in a single pass using a two-roll mill, with the deformation controlled at 55%. Then, the cold-rolled sheet is cut in half, stacked, and cold-rolled in a single pass. This process of cutting, stacking, and cold-rolling in a single pass is repeated 12 times. During the repetition, the deformation of each cold-rolling pass is 50%-60%. The resulting composite sheet has a thickness of 1.3 mm. This invention requires no lubricant treatment and completes the final preparation of the Zn / Mg composite material by repeated cold rolling.

[0068] Implementation effect

[0069] The Zn / Mg composite material after lamination and rolling mainly consists of white striped Zn and gray striped Mg, clearly distinguishing Zn and Mg. These regions are continuously and uniformly distributed in alternating fibrous patterns. The tensile yield strength (YS), tensile ultimate strength (UTS), and elongation of the pure Zn plate after lamination and rolling are 95 MPa, 132 MPa, and 82.3%, respectively. The tensile mechanical properties of the Zn / Mg layered composite material after lamination and rolling show a significant improvement, with tensile yield strength (YS), tensile ultimate strength (UTS), and elongation of 286 MPa, 348 MPa, and 7.9%, respectively. Electrochemical tests in Hank's solution revealed that the corrosion potential, corrosion current density, and corrosion rate of the pure Zn plate after lamination and rolling are -0.982 V and 7.115 μA / cm, respectively. 2 The corrosion potential, corrosion current density, and corrosion rate of the laminated Zn / Mg composite material were -1.169 V and 10.041 μA / cm, respectively, with a corrosion value of 105.7 μm / y. 2 And 204.3 μm / y. Adding Mg resulted in a faster corrosion rate and poor corrosion resistance.

Claims

1. A method for preparing a high-strength Zn / Cu / Mg layered composite material, characterized in that: A pure Cu coating is prepared on a Zn plate. Then, two Zn plates with Cu coatings are stacked with a Mg plate to obtain a composite plate. The composite plate is subjected to single-pass cold rolling to obtain a cold-rolled plate. The cold-rolled plate is cut into two pieces from the middle, stacked, and then subjected to single-pass cold rolling. The cutting-stacking-single-pass cold rolling process is repeated to obtain a Zn / Cu / Mg layered composite material. The method for preparing a pure Cu coating on a Zn plate is as follows: a zinc plate is used as the cathode, a copper plate as the anode, and a copper sulfate solution is used as the electrolyte. Then, a copper layer is electroplated on the zinc plate to obtain a Zn plate with a copper coating. The Zn plate with the copper coating is then heat-treated to obtain a Zn plate with a Cu coating. The thickness of the Zn plate is 0.9-1 mm; After adjusting the pH of the electrolyte to 8.5-9 with ammonia, electroplating begins. During electroplating, the voltage is controlled at 3.9V and the electroplating time is 55-60s. The copper sulfate solution contains 14-16% copper sulfate by mass. The thickness of the copper layer obtained after electroplating is 0.5-1 μm; The heat treatment temperature is 150-280℃, and the heat treatment time is 20-40 minutes.

2. The method for preparing a high-strength Zn / Cu / Mg layered composite material according to claim 1, characterized in that: The deformation of composite plates in a single cold rolling pass is 50%-60%.

3. The method for preparing a high-strength Zn / Cu / Mg layered composite material according to claim 1, characterized in that: The cold-rolled sheet is cut into two pieces from the middle, stacked, and then subjected to single-pass cold rolling. The process of cutting-stacking-single-pass cold rolling is repeated, while controlling the deformation of any single-pass cold rolling to be 50%-60%. The number of repeated cutting-lamination-single-pass cold rolling is 1-12 times.

4. The Zn / Cu / Mg layered composite material prepared by the preparation method according to any one of claims 1-3.

5. The application of the Zn / Cu / Mg layered composite material prepared by the preparation method according to any one of claims 1-3, characterized in that: The Zn / Cu / Mg layered composite material is used in biodegradable implant materials.

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