Surface treatment method for magnesium or magnesium alloy
Through the combined treatment method of hydrothermal and beeswax, a composite coating is formed, which solves the problem of rapid degradation speed of magnesium in aqueous solution, and effectively regulates the degradation time of magnesium products, meets clinical needs, and is simple and environmentally friendly.
Patent Information
- Application Number
- CN202510290154.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-12
- Publication Date
- 2025-06-17
AI Technical Summary
The chemical properties of magnesium are active, resulting in rapid degradation in aqueous solutions, especially in solutions containing chloride ions, which cannot meet clinical needs. The existing alloying elements are harmful or have unclear impacts on the human body, limiting the application of magnesium in the field of degradable biological materials.
By combining hydrothermal and beeswax treatment, the outer oxide film on the surface of magnesium or magnesium alloy is polished off, and hydrothermal reaction is carried out in Na2CO3 solution to form a hydrothermal conversion film, and then insulated in the molten beeswax solution to form a wax film, and the film thickness is regulated to control the degradation time of magnesium products.
The obtained composite coating is non-toxic and has no side effects on the human body, has good biocompatibility and protection, and can effectively regulate the degradation time of magnesium products in the human body, meet clinical needs, and has simple process, cheap raw materials, and the solution after use is free of pollution to the environment.
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Figure CN120158735A_ABST
Abstract
Description
Technical Field
[0001] The present disclosure relates to the field of metal surface treatment, and particularly to a surface treatment method for magnesium or magnesium alloy. Background Art
[0002] Magnesium and magnesium alloys have good biocompatibility and degradability; they have good mechanical strength, and their density and elastic modulus are comparable to those of human bones. Therefore, they have broad application prospects in the field of degradable magnesium biomaterials. However, magnesium has active chemical properties, and its standard electrode potential is -2.38 V vs. NHE; the formed corrosion product film is loose and porous with poor protection. Therefore, in aqueous solutions, especially in solutions containing chloride ions, the degradation rate is fast, unable to meet clinical requirements. The corrosion problem of magnesium greatly limits the application of magnesium in the field of degradable biomaterials.
[0003] Alloying and surface treatment are the main methods to solve the magnesium corrosion problem. Since many alloying elements are harmful to the human body or their effects are not yet clear, the means of solving the magnesium biological corrosion problem by alloying methods are limited. Therefore, it is very important to find a green and non-toxic surface treatment method with good protection to control the degradation time of magnesium in the human environment. Since some degradable magnesium biological products (such as magnesium alloy degradable stents) need to withstand large deformations (contraction and expansion) during implantation, many existing coatings will crack and peel off. Therefore, it is necessary to develop coatings that can withstand a certain amount of deformation to control the degradation rate of magnesium alloy biological products. Summary of the Invention
[0004] In view of the problems in the background art, the present disclosure provides a surface treatment method for magnesium or magnesium alloy.
[0005] The surface treatment method for magnesium or magnesium alloy provided by the present disclosure includes the steps: Step 1, grind off the outer layer oxide film on the surface of magnesium or magnesium alloy and clean it; Step 2, put the ground magnesium or magnesium alloy into a hydrothermal reaction kettle containing Na2CO3 solution for reaction to form a hydrothermal conversion film on the surface of magnesium or magnesium alloy, the reaction temperature is 130°C to 160°C, and the time is maintained for 2 h to 3 h, then take out the reaction kettle and cool it to obtain the hydrothermally treated magnesium or magnesium alloy; Step 3, put the hydrothermally treated magnesium or magnesium alloy into a molten beeswax solution for heat preservation, the temperature is 70°C to 95°C, and the time is maintained for 5 min to 10 min to form a wax film on the surface of magnesium or magnesium alloy, then take out and cool it to complete the surface treatment.
[0006] In some embodiments, in Step 1, the outer layer oxide film on the surface of magnesium or magnesium alloy is ground off with 400-mesh to 2000-mesh sandpaper.
[0007] In some embodiments, in Step 2, the thickness of the hydrothermal conversion film is 10 microns to 30 microns.
[0008] In some embodiments, in step two, the cooling conditions of the reaction kettle are as follows: first, cool in air for 5 min to 15 min, and then cool with cold water.
[0009] In some embodiments, step two is as follows: put the polished magnesium or magnesium alloy into a hydrothermal reaction kettle containing a mixed solution of 0.1 M Na2CO3 and 0.01 M NaOH to react to form a hydrothermal conversion film on the surface of the magnesium or magnesium alloy. The mixed solution submerges the magnesium or magnesium alloy. The reaction temperature is 130 to 160 °C, and the time is maintained for 2 h to 3 h. Then, take out the reaction kettle and first cool it in air for 8 min to 10 min, and then cool it with cold water.
[0010] In some embodiments, the composition of the hydrothermal conversion film includes MgCO3, Mg(OH)2, and MgO.
[0011] In some embodiments, step three is as follows: place the solid beeswax in a beaker at 70 °C to 95 °C to melt it. Then, take the magnesium or magnesium alloy after the hydrothermal reaction and put it into the beaker. Keep it at 70 °C to 95 °C for 5 min to 10 min and then take it out and cool it in air.
[0012] In some embodiments, in step one, the outer oxide film on the surface of the magnesium or magnesium alloy is polished off to form a block-shaped sample.
[0013] In some embodiments, in step three, the magnesium or magnesium alloy is turned over every 2 min in the beeswax solution.
[0014] In some embodiments, in step three, the thickness of the wax film is 5 microns to 15 microns.
[0015] The beneficial effects of the present disclosure are as follows:
[0016] The composite coating obtained by the combined treatment of hydrothermal and beeswax is non-toxic and has no side effects on the human body, has an obvious protective effect on the magnesium matrix, and has good biocompatibility. By regulating the film thickness, the degradation time of magnesium products in the human body can be effectively regulated to meet the clinical requirements. The raw materials used are cheap, the process is simple, and the solution after use is environmentally friendly. Description of the Drawings
[0017] Figure 1 It is an electron microscope image and a cross-sectional view of the pure magnesium wire after surface treatment in Example 1; among them, (a) is the electron microscope image and (b) is the cross-sectional view.
[0018] Figure 2 It is a hydrogen evolution amount diagram of the pure magnesium wire in Example 1 for 7 days.
[0019] Figure 3 It is a potentiodynamic polarization curve diagram of the pure magnesium wire in Example 1.
[0020] Figure 4 The AC impedance diagram of the pure magnesium wire of Example 1.
[0021] Figure 5 The cytotoxicity test diagram of the pure magnesium wire of Example 1.
[0022] Figure 6 The hydrogen evolution amount diagram of the pure magnesium block of Example 2 in 7 days.
[0023] Figure 7 The potentiodynamic polarization curve diagram of the pure magnesium block of Example 2. Detailed implementation manners
[0024] It should be understood that the disclosed embodiments are only examples of the present disclosure, and the present disclosure can be implemented in various forms. Therefore, the specific details of the present disclosure should not be construed as limitations, but only as the basis for the claims to teach those of ordinary skill in the art to implement the present disclosure in various ways. In the description of the present disclosure, the terms and technical terms not clearly stated are the common knowledge of those skilled in the art, and the methods not clearly stated are the conventional methods well known to those skilled in the art.
[0025] The surface treatment method of magnesium or magnesium alloy provided by the present disclosure will be described in detail below.
[0026] The surface treatment method of magnesium or magnesium alloy provided by the present disclosure includes the following steps: Step 1, grind off the outer oxide film on the surface of magnesium or magnesium alloy and clean it; Step 2, put the ground magnesium or magnesium alloy into a hydrothermal reaction kettle containing Na2CO3 solution for reaction to form a hydrothermal conversion film on the surface of magnesium or magnesium alloy, the reaction temperature is 130°C to 160°C, and the time is maintained at 2h to 3h, and then take out the reaction kettle to cool to obtain the hydrothermally treated magnesium or magnesium alloy; Step 3, put the hydrothermally treated magnesium or magnesium alloy into the molten beeswax solution for heat preservation, the temperature is 70°C to 95°C, and the time is maintained at 5min to 10min to form a wax film on the surface of magnesium or magnesium alloy, and then take out and cool to complete the surface treatment.
[0027] The treatment method obtains a composite coating by hydrothermal and beeswax impregnation treatment of the surface of magnesium or magnesium alloy, and controls the film thickness by controlling the hydrothermal time. The role of the hydrothermal reaction is to form a protective corrosion product film.
[0028] In some embodiments, in Step 1, the outer oxide film on the surface of magnesium or magnesium alloy is ground off with sandpaper of 400 mesh to 2000 mesh.
[0029] In some embodiments, in Step 2, the thickness of the hydrothermal conversion film is 10 microns to 30 microns.
[0030] In some embodiments, in step 2, the cooling condition of the reactor is: first cooling in air for 5 min to 15 min, and then cooling with cold water.
[0031] In some embodiments, in step 2, the hydrothermal reactor contains a mixed solution of Na2CO3 and NaOH.
[0032] In some embodiments, the step two is: placing the polished magnesium or magnesium alloy into a hydrothermal reactor containing a mixed solution of 0.1M Na2CO3 and 0.01M NaOH to react so that a hydrothermal conversion film is formed on the surface of the magnesium or magnesium alloy, the mixed solution immerses the magnesium or magnesium alloy, the reaction temperature is 130-160°C, and the time is maintained at 2h-3h. After that, the reactor is taken out and placed in the air to cool for 8min-10min, and then cooled with cold water.
[0033] In some embodiments, the hydrothermal conversion film component includes MgCO3, Mg(OH)2, and MgO. In some embodiments, the hydrothermal conversion film component is a crystalline hydrate of MgCO3, Mg(OH)2, MgO, and MgCO3.
[0034] The purpose of the beeswax treatment in step 3 is to seal the hydrothermal conversion film and form an outermost organic protective film. In some embodiments, step 3 is: melt the solid beeswax in a beaker at 70°C to 95°C, then put the magnesium or magnesium alloy after the hydrothermal reaction into the beaker, keep it at 70°C to 95°C for 5min to 10min, then take it out and cool it in the air.
[0035] In some embodiments, in step one, the outer oxide film on the surface of magnesium or magnesium alloy is polished off to form a block sample.
[0036] In some embodiments, in step three, the magnesium or magnesium alloy is turned over in the beeswax solution every 2 minutes.
[0037] In some embodiments, in step three, the wax film has a thickness of 5 microns to 15 microns.
[0038] The present disclosure is further described below in conjunction with the examples. In the following examples and comparative examples, the reagents, materials and instruments used, unless otherwise specified, can be obtained commercially or prepared by methods known in the art.
[0039] Example 1
[0040] Take two identical Pure magnesium wire samples, one without surface treatment and the other with the following surface treatment:
[0041] Step 1: Use 2000-mesh sandpaper to polish off the outer oxide film on the surface of the pure magnesium wire, clean it with alcohol, and then perform a certain bending treatment to imitate the processing of the bracket.
[0042] Step 2: Place the polished pure magnesium wire into a hydrothermal reaction kettle containing a solution of 0.1M Na2CO3 + 0.01M NaOH for treatment. The temperature is 150 °C and the time is maintained for 2.5 h. Then take out the reaction kettle and cool it. Cool it in the air for 10 minutes, and then cool it with tap water. A conversion film with a thickness of 21 ± 2 μm is formed on the surface of the pure magnesium wire. See Figure 1 (b) Cross-sectional view.
[0043] Step 3: Heat the solid beeswax in a beaker to 90 °C until it melts. After complete melting, take out the hydrothermally treated pure magnesium wire and put it into the beaker. Keep it warm at 90 °C for 5 min and then take it out. Cool it in the air. A beeswax film layer with a thickness of 10 μm to 15 μm is formed on the outside of the hydrothermal conversion film of the pure magnesium wire. See Figure 1 (b) Cross-sectional view.
[0044] The following tests are carried out on both the untreated and surface-treated magnesium wire samples:
[0045] (1) Corrosion test. Rinse the magnesium wire sample with deionized water, dry it with cold air, put it into a 100 ml beaker, and add 80 ml of HBSS (Hank's Balanced Salt Solution). Place it in a drying oven at 36.5 °C and change the solution every 2 - 3 days. Observe the corrosion situation (whether it breaks and degrades).
[0046] The results show that: the fracture time of the untreated magnesium wire is 1 - 3 days, and the fracture time of the surface-treated magnesium wire sample is 25 - 35 days.
[0047] (2) Hydrogen evolution test. Immerse the magnesium wire sample in the HBSS solution for a hydrogen evolution experiment. The hydrogen evolution amount in 7 days is as Figure 2 shown.
[0048] The results show that: the average hydrogen evolution amount of the bare sample is 0.072 ± 0.004 mL / cm 2 / d, while the average hydrogen evolution amount of the surface-treated sample is 0.012 ± 0.001 mL / cm 2 / d.
[0049] (3) Electrochemical performance test. Perform an electrochemical performance test in the HBSS solution. Use a 1.5 cm × 1.5 cm platinum sheet as the counter electrode and Ag / AgCl / Sat.KCl as the reference electrode. The results of the potentiodynamic polarization curve are as Figure 3 shown, and the results of the AC impedance are as Figure 4 shown.
[0050] The results show that: compared with the magnesium wire without surface treatment, the corrosion current density of the surface-treated magnesium wire sample decreases by 2-3 orders of magnitude, and the film resistance value increases by 3-4 orders of magnitude.
[0051] (4) Cytotoxicity test. Mouse calvarial pre-osteoblasts (MC3T3-E1) cultured in a cell incubator at 37 °C with a CO2 concentration of 5% were selected. They were cultured in complete medium (DMEM), which contained 1% penicillin, streptomycin, and 10% fetal bovine serum. When the cells in the culture dish grew to 80-90%, they were passaged, and the cells used in the experiment were the third to sixth generations. Before the formal experiment started, the specimens were irradiated with an ultraviolet lamp for more than 2 h for ultraviolet sterilization treatment. The disinfected samples were soaked in complete medium at a ratio of 1.25 cm 2 / mL for 24 hours, and the leaching solution was stored at 4 °C for later use.
[0052] An appropriate amount of cells was digested into a cell suspension with trypsin and centrifuged at a speed of 1000 rpm. The MC3T3-E1 cells were inoculated on a 96-well plate at a concentration of approximately 20,000 cells per milliliter. After 24 hours in the incubator, the leaching solution was used to replace the complete medium for continued culture (among them, the cells cultured with complete medium were the negative control group). After continuous culture for 1, 3, and 5 days, the leaching solution was removed, and the complete medium containing 10% CCK-8 cell counting reagent was used to replace it. After 2 h, the absorbance was measured with a spectrophotometer at a wavelength of 450 nm, and the cell survival rate was calculated using the following formula:
[0053] Cell survival rate (%) = (A - B) / (C - B) × 100%; where A represents the absorbance of each experimental group, B represents the absorbance of the blank group, and C represents the absorbance of the negative control group.
[0054] The results of the cytotoxicity test are as Figure 5 shown.
[0055] The results show that: for the magnesium wire sample treated with hydrothermal beeswax, the survival rate of cells is higher than that of the untreated magnesium wire and even higher than that of the negative control group, and the biocompatibility is very good.
[0056] Example 2
[0057] Take two identical rectangular pure magnesium block samples of 1.5 cm × 1.5 cm × 1 cm. One is not surface-treated, and the other is surface-treated as follows;
[0058] Step 1: The pure magnesium was ground step by step with 400#, 800#, 1500#, and 2000# SiC sandpaper. After grinding, the specimens were rinsed with distilled water and alcohol and dried with cold air for later use.
[0059] Step 2: Place the dried pure magnesium sample in a hydrothermal reactor containing 0.1 M NaCO3 solution for hydrothermal reaction. The hydrothermal temperature is 150 °C and the hydrothermal time is 2 h. After cleaning and drying, the hydrothermally treated sample is obtained.
[0060] Step 3: Melt the beeswax in a beaker at 90 °C. Then, put the dried pure magnesium sample into the beaker and keep it at 90 °C for 10 min. During this period, turn it over every 2 min to ensure that each surface is covered with an organic coating. After cooling, the beeswax-treated sample is obtained.
[0061] Step 4: Keep part of the hydrothermally treated sample in the melted beeswax solution at 90 °C for 10 min, and turn it over every 2 min. After cooling, the hydrothermal + beeswax-treated sample is obtained.
[0062] For the pure magnesium block samples without surface treatment and after surface treatment, the following tests are carried out:
[0063] (1) Hydrogen evolution test. Immerse the pure magnesium block sample in 3.5% NaCl solution for hydrogen evolution experiment. The hydrogen evolution amount in 7 days is as Figure 6 shown.
[0064] The results show that: the average hydrogen evolution amount of the sample without surface treatment is 0.61 ± 0.06 mL / cm 2 / d, the average hydrogen evolution amount of the hydrothermally treated sample is 0.12 ± 0.01 mL / cm 2 / d, the average hydrogen evolution amount of the beeswax-treated sample is 0.18 ± 0.02 mL / cm 2 / d, and the average hydrogen evolution amount of the hydrothermal and beeswax-treated sample is 0.010 ± 0.001 mL / cm 2 / d.
[0065] (2) Electrochemical performance test. Immerse the pure magnesium block sample in 3.5% NaCl solution for electrochemical performance test. Use a platinum sheet of 1.5 cm × 1.5 cm as the counter electrode and Ag / AgCl / Sat.KCl as the reference electrode. The results of the potentiodynamic polarization curve are as Figure 7 shown.
[0066] The results show that: compared with the magnesium block without surface treatment, the corrosion current density of the surface-treated magnesium block sample decreases by 2 - 3 orders of magnitude.
[0067] (3) Cytotoxicity test. The test method and operation are exactly the same as those in Example 1.
[0068] The results show that for the magnesium block samples with surface treatment, the cell survival rate is higher than that of the magnesium blocks without surface treatment and also higher than that of the negative control group, indicating that its biocompatibility is also very good. Among them, the cell survival rate in the magnesium block samples treated by hydrothermal and beeswax treatment is higher than that in the magnesium block samples treated only by hydrothermal treatment.
[0069] The above are only examples of the present disclosure and do not impose any form of limitation on the present disclosure. Although the present disclosure is disclosed above with preferred embodiments, it is not intended to limit the present disclosure. Any person skilled in the art, without departing from the scope of the technical solution of the present disclosure, makes some changes or modifications using the technical content disclosed above, which are equivalent to equivalent implementation cases and are all within the scope of the technical solution of the present disclosure.
Claims
1. A method for surface treatment of magnesium or magnesium alloy, comprising the steps of: Step 1: Grind off the outer oxide film on the surface of magnesium or magnesium alloy and clean it; Step 2: placing the polished magnesium or magnesium alloy into a hydrothermal reactor containing a Na2CO3 solution to react so that a hydrothermal conversion film is formed on the surface of the magnesium or magnesium alloy, the reaction temperature is 130°C to 160°C, and the time is maintained at 2h to 3h, then taking out the reactor and cooling it to obtain hydrothermally treated magnesium or magnesium alloy; Step three, placing the hydrothermally treated magnesium or magnesium alloy into a molten beeswax solution and keeping it warm at 70°C to 95°C for 5min to 10min, forming a wax film on the surface of the magnesium or magnesium alloy, then taking it out and cooling it to complete the surface treatment.
2. The surface treatment method of magnesium or magnesium alloy according to claim 1, characterized in that: In step 1, the outer oxide film on the surface of magnesium or magnesium alloy is polished off with sandpaper of 400-2000 mesh.
3. The surface treatment method of magnesium or magnesium alloy according to claim 1, characterized in that: In step 2, the thickness of the hydrothermal conversion film is 10 microns to 30 microns.
4. The surface coating method of magnesium or magnesium alloy according to claim 1, characterized in that: In step 2, the reactor is cooled in air for 5 to 15 minutes and then cooled with cold water.
5. The method for surface treatment of magnesium or magnesium alloy according to claim 1, characterized in that: The second step is: putting the polished magnesium or magnesium alloy into a hydrothermal reactor filled with a mixed solution of 0.1M Na2CO3 and 0.01MNaOH to react so that a hydrothermal conversion film is formed on the surface of the magnesium or magnesium alloy, the mixed solution immerses the magnesium or magnesium alloy, the reaction temperature is 130-160°C, the time is maintained at 2h-3h, and then the reactor is taken out and cooled in the air for 8min-10min, and then cooled with cold water.
6. The surface treatment method of magnesium or magnesium alloy according to claim 1 or 3, characterized in that: The hydrothermal conversion film components include MgCO3, Mg(OH)2, and MgO.
7. The surface treatment method of magnesium or magnesium alloy according to claim 1, characterized in that: The step three is: placing solid beeswax in a beaker at 70°C to 95°C to melt it, then taking the magnesium or magnesium alloy after the hydrothermal reaction and putting it into the beaker, keeping it at 70°C to 95°C for 5min to 10min, then taking it out and cooling it in the air.
8. The surface treatment method of magnesium or magnesium alloy according to claim 1, characterized in that: In step one, the outer oxide film on the surface of magnesium or magnesium alloy is polished off to form a block sample.
9. The surface treatment method of magnesium or magnesium alloy according to claim 1, characterized in that: In step 3, the magnesium or magnesium alloy is turned over in the beeswax solution every 2 minutes.
10. The surface treatment method of magnesium or magnesium alloy according to claim 1, characterized in that: In step three, the wax film has a thickness of 5 microns to 15 microns.