A magnesium-based material surface self-healing protective coating and a preparation method and application thereof

Abstract

The application discloses a magnesium-based material surface self-healing protective coating and a preparation method and application thereof. The magnesium-based material surface protective coating is mainly composed of layered double hydroxides (LDH) with organic corrosion inhibitors and inorganic corrosion inhibitors intercalated on the surface of the magnesium-based material. The coating can be quickly and effectively self-repaired after physical damage or chemical corrosion through the innovative design of the organic and inorganic ion intercalated LDH coating with good biocompatibility, which can reduce the maintenance cost, improve the reliability of the material, and realize more efficient and more economical long-term protection of the magnesium-based material surface. The protective coating can not only greatly improve the corrosion resistance of the magnesium-based material, but also provide a possibility for the application in high-demand fields such as medical implant materials, and is also suitable for high-end industrial fields such as aerospace, automobiles and electronic information, and provides a new material protection strategy, which is expected to lead a new trend of material protection technology.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of surface coating, and particularly relates to a magnesium-based material surface self-healing protective coating and a preparation method and application thereof. BACKGROUND

[0002] Compared with traditional medical stainless steel, titanium and other metal materials, magnesium and its alloys have gradually become a research hotspot due to their biodegradability, and have a great potential application prospect in the field of temporary medical implants such as fracture fixation devices, guided bone regeneration membranes and vascular stents. As a green engineering material in the 21st century, magnesium alloy is widely used in aerospace, automobile manufacturing, electronic information and many other fields due to its light weight, high strength and excellent mechanical properties. However, magnesium-based materials are prone to corrosion, and their corrosion resistance is not enough to meet the requirements of long-term use, which is the main bottleneck of their application. In view of this problem, existing research focuses on various physical protection methods, including traditional organic coatings such as paint and coating, as well as inorganic and metal coatings such as anodizing, chemical conversion and electroplating. Although these methods can provide certain protection at the beginning, their protection performance decreases significantly after the material is scratched, impacted or subjected to long-term environmental corrosion. These physical protection methods often lack self-repairing ability and lose their protective effectiveness once damaged, which requires regular maintenance and re-coating, increasing the cost and reducing the service life and reliability of the material.

[0003] Under this background, the research on self-healing coatings has gradually become a new trend in the field of material protection. Self-healing coatings use special design to automatically release repair substances when micro-damage occurs, restoring the integrity and protection function of the coating. Layered double hydroxide (LDH) presents a special layered structure and has its unique interlayer ion exchange ability, providing an excellent carrier for the loading of corrosion inhibitors. For example, WO3 2- , VO4 3- , MoO4 2- and PO4 3- and other inorganic ions are loaded in the interlayer of the LDH coating. Although intercalated corrosion inhibitors improve the corrosion protection performance of the LDH coating, the corrosion inhibition effect of single intercalated corrosion inhibitor LDH coating is limited and has limitations in actual application. At the same time, the intercalated inorganic release agent ions often have potential cytotoxicity and even carcinogenicity, making it difficult to promote the application in the biomedical field. SUMMARY

[0004] The present application aims to overcome the deficiencies of the prior art and provide a magnesium-based material surface self-healing protective coating and a preparation method thereof.

[0005] The application also aims to provide the use of the above-mentioned magnesium-based material surface self-healing protective coating in the preparation of corrosion protection materials or biocompatible materials.

[0006] The above-mentioned first object of the application can be achieved by the following technical solution: a preparation method of a magnesium-based material surface self-healing protective coating, comprising the following steps:

[0007] (1) surface pretreatment of the magnesium-based material;

[0008] (2) preparation of an organic corrosion inhibitor intercalated LDH coating:

[0009] Under a protective atmosphere, an aqueous solution of divalent metal ion salt, trivalent metal ion salt and organic corrosion inhibitor is prepared, and the pH is adjusted to obtain a reaction solution;

[0010] The pretreated magnesium-based material in step (1) and the reaction solution are placed in a hydrothermal reaction container to perform a hydrothermal reaction, and an organic corrosion inhibitor intercalated LDH coating is obtained on the surface of the magnesium-based material;

[0011] (3) preparation of an organic corrosion inhibitor and inorganic corrosion inhibitor co-intercalated LDH coating:

[0012] An aqueous solution of inorganic corrosion inhibitor is prepared;

[0013] The magnesium-based material with the organic corrosion inhibitor intercalated LDH coating obtained on the surface in step (2) is immersed in the aqueous solution of inorganic corrosion inhibitor to perform an ion exchange reaction, and an organic corrosion inhibitor and inorganic corrosion inhibitor co-intercalated LDH self-healing protective coating is obtained on the surface of the magnesium-based material.

[0014] In the above-mentioned preparation method of the magnesium-based material surface self-healing protective coating:

[0015] Preferably, the magnesium-based material in step (1) is magnesium, magnesium alloy, magnesium-containing porous material, magnesium alloy-containing porous material, material treated with magnesium surface, material treated with magnesium alloy surface, material treated with magnesium porous material surface or material treated with magnesium alloy porous material surface.

[0016] More preferably, the magnesium-based material in step (1) is magnesium or magnesium alloy.

[0017] Preferably, the surface pretreatment of the magnesium-based material in step (1) comprises polishing the magnesium-based material to remove surface oxides and impurities, and then cleaning and blowing dry.

[0018] Preferably, the cleaning can use anhydrous ethanol and / or acetone, and more preferably, the cleaning uses anhydrous ethanol.

[0019] Preferably, the divalent metal ion salt in step (2) is one or more of magnesium nitrate, zinc nitrate and copper nitrate.

[0020] Preferably, the concentration of the divalent metal ion salt in step (2) is 30-120 mmol / L.

[0021] More preferably, the concentration of the divalent metal ion salt in step (2) is 40-90 mmol / L.

[0022] Preferably, the trivalent metal ion salt in step (2) is one or both of aluminum nitrate and ferric nitrate.

[0023] Preferably, the concentration of the trivalent metal ion salt in step (2) is 10-40 mmol / L.

[0024] More preferably, the concentration of the trivalent metal ion salt in step (2) is 13-30 mmol / L.

[0025] Preferably, the organic corrosion inhibitor in step (2) is one or more of aspartic acid, sodium aspartate and potassium aspartate.

[0026] Compared with glutamic acid, the complex formed by ASP and magnesium ions in the present application is more stable than the complex formed by glutamic acid and magnesium ions, so that the intercalation of ASP ions can impart stronger self-repairing ability to the LDH coating on the surface of the magnesium-based material.

[0027] Preferably, the concentration of the organic corrosion inhibitor in step (2) is 0.6-30 mmol / L.

[0028] More preferably, the concentration of the organic corrosion inhibitor in step (2) is 1.5-20 mmol / L.

[0029] Preferably, the protective atmosphere in step (2) is one or more of nitrogen, argon and helium.

[0030] Preferably, the pH in step (2) is adjusted to 9-13.

[0031] More preferably, the pH in step (2) is adjusted to 10-12.

[0032] Preferably, the temperature of the hydrothermal reaction in step (2) is 100-160°C, and the time is 1-30 hours.

[0033] More preferably, the temperature of the hydrothermal reaction in step (2) is 110-140°C, and the time is 3-24 hours.

[0034] Preferably, the inorganic corrosion inhibitor in step (3) is sodium silicate, and the concentration of the aqueous solution of the inorganic corrosion inhibitor is 15-150 mmol / L.

[0035] Preferably, the concentration of the inorganic corrosion inhibitor aqueous solution is 25-120 mmol / L.

[0036] Preferably, the temperature of the ion exchange reaction in step (3) is 50-100℃, and the time is 1-10 hours.

[0037] Preferably, the temperature of the ion exchange reaction in step (3) is 60-90℃, and the time is 2-6 hours.

[0038] The application also provides a magnesium-based material surface self-healing protective coating prepared by the above method.

[0039] The magnesium-based material surface protective coating according to the application is mainly composed of organic corrosion inhibitors and inorganic corrosion inhibitors co-intercalated in a layered double hydroxide (LDH) on the surface of a magnesium-based material.

[0040] The above last object of the application can be achieved by the following technical solution: application of the above magnesium-based material surface self-healing protective coating in the preparation of corrosion protection materials or biocompatible materials.

[0041] The protective coating according to the application can be used to protect metal materials and slow down the corrosion of metal materials. There are various anticorrosion coatings. Compared with the prior art, the LDH in the prior art relies on physical barrier effect to achieve protection. For example, when the coating is partially damaged and the substrate is exposed, the substrate will be quickly dissolved. The ASP and silicate ion intercalated LDH in the application can achieve protection by the physical barrier effect of the LDH itself on one hand, and on the other hand, when the coating is damaged, such as having defects or being scratched, the corrosion liquid will directly reach the surface of the metal substrate such as the magnesium substrate, and at this time, the ASP and silicate ions are released, which form chelates and precipitates with magnesium ions generated by magnesium corrosion, thereby achieving self-healing of the coating, and the coating returns to a perfect state and continues to play a protective role for the substrate. Since ASP and silicate have good biocompatibility, the ASP and silicate ion intercalated LDH coating according to the application is particularly suitable for corrosion protection of medical materials.

[0042] In addition, the application further verifies that the magnesium-based material surface self-healing protective coating according to the application has good biocompatibility by the good cell adhesion and spreading of osteoblasts on the surface of the magnesium-based material surface self-healing protective coating.

[0043] Compared with the prior art, the application has the following advantages:

[0044] (1) The present application is characterized in that the organic and inorganic ion intercalated LDH coating layer can be quickly and effectively self-repaired after physical damage and chemical corrosion, thereby reducing the maintenance cost and improving the reliability of the material;

[0045] (2) The protective coating and the preparation method thereof can greatly improve the corrosion resistance of magnesium-based materials (such as magnesium, magnesium alloy, magnesium-containing porous material, magnesium alloy-containing porous material, material treated with magnesium surface, material treated with magnesium alloy surface, material treated with magnesium porous material surface, or material treated with magnesium alloy porous material surface, etc.), and also provide a possibility for the application in high requirement fields such as medical implant materials;

[0046] (3) In general, the present application realizes more efficient and more economical long-term protection of the surface of magnesium-based materials by using the organic and inorganic ion intercalated LDH coating layer with good biocompatibility. This coating layer not only has a broad application prospect in the field of medical implant materials, but also is suitable for high-end industrial fields such as aerospace, automobile and electronic information, and provides a new material protection strategy, which is expected to lead the new trend of material protection technology. BRIEF DESCRIPTION OF DRAWINGS

[0047] The present application will be further described below with reference to the accompanying drawings and examples.

[0048] Figure 1 The surface morphology of the sample prepared in Example 1 under the scanning electron microscope is shown in the following figure;

[0049] Figure 2 The cross-sectional view of the sample prepared in Example 1 under the scanning electron microscope is shown in the following figure;

[0050] Figure 3 The XRD patterns of the LDH coating layer (AZ / L) prepared in Comparative Example 1, the ASP ion intercalated LDH coating layer modified sample (AZ / LA) prepared in Comparative Example 2, the silicate ion intercalated LDH coating layer modified sample (AZ / LS) prepared in Comparative Example 3, the coating layer modified sample (AZ / LAS) prepared in Example 1 and the substrate sample are shown in the following figure;

[0051] Figure 4 The polarization curve results of the samples prepared in Example 1 and Comparative Examples 1-3 in the artificial simulated body fluid at 37℃ are shown in the following figure, wherein AZ / L is the LDH coating layer prepared in Comparative Example 1, AZ / LA is the ASP ion intercalated LDH coating layer modified sample prepared in Comparative Example 2, AZ / LS is the silicate ion intercalated LDH coating layer modified sample prepared in Comparative Example 3, and AZ / LAS is the coating layer modified sample prepared in Example 1;

[0052] Figure 5Figure of mouse preosteoblast cell adhesion results on the surface of the sample prepared in Example 1 and Comparative Examples 1-3, wherein (a) substrate, (b) LDH coating AZ / L prepared in Comparative Example 1, (c) ASP ion intercalated LDH coating modified sample AZ / LA prepared in Comparative Example 2, (d) silicate ion intercalated LDH coating modified sample AZ / LS prepared in Comparative Example 3, (e) coating modified sample AZ / LAS prepared in Example 1, (f) number of adherent cells. DETAILED DESCRIPTION

[0053] The application will be further described in conjunction with the following examples and drawings, but the embodiments of the application are not limited thereto.

[0054] In the following examples, unless specific experimental conditions are indicated, the general experimental conditions are usually conventional or as suggested by the reagent companies. The materials, reagents, etc. used, if not specifically mentioned, are reagents and materials obtained from commercial sources.

[0055] The terms used in the following implementation methods and examples have the meanings generally understood by those of ordinary skill in the art, unless otherwise specified.

[0056] First Part of Magnesium-based Material Surface Protective Coating and Preparation Method Thereof

[0057] Example 1

[0058] The preparation method of the magnesium-based material surface protective coating provided in this example includes the following steps:

[0059] (1) Pretreatment of AZ31B magnesium alloy substrate;

[0060] The 10mm x 10mm x 10mm AZ31B magnesium alloy sample was polished with 500#, 1000# and 2000# sandpaper in sequence, ultrasonically cleaned in anhydrous ethanol for 10 minutes, and then blown dry.

[0061] (2) Preparation of ASP ion intercalated LDH coating;

[0062] Under nitrogen protection, a 60mmol / L Mg(NO3)2·6H2O, 20mmol / L Al(NO3)3·9H2O and 6.6mmol / L aspartic acid (ASP) deionized water solution was prepared, and then 2mol / L NaOH was used to adjust the pH of the solution to 12 to obtain a reaction solution;

[0063] The pretreated AZ31B magnesium alloy substrate of step (1) and the reaction solution were placed in a hydrothermal reaction kettle, and reacted at 120℃ for 15 hours to obtain an ASP ion intercalated LDH coating on the surface of the AZ31B magnesium alloy.

[0064] (3) Preparation of LDH coating with ASP and silicate ion intercalation;

[0065] A 50 mmol / L Na2SiO3·9H2O deionized aqueous solution was prepared, the ASP ion intercalated LDH coating modified magnesium alloy sample obtained in step (2) and the prepared Na2SiO3 aqueous solution were placed in a hydrothermal reaction kettle, and reacted at 90°C for 2 hours to obtain an LDH coating with ASP and silicate ion intercalation on the surface of the AZ31B magnesium alloy (AZ / LAS).

[0066] Example 2

[0067] The preparation method of the magnesium-based material surface protective coating provided in this embodiment includes the following steps:

[0068] (1) Pretreatment of pure magnesium substrate;

[0069] A 10mm×10mm×10mm pure magnesium sample was polished with 500#, 1000# and 2000# sandpaper in sequence, ultrasonically cleaned in anhydrous ethanol for 10 minutes, and then dried.

[0070] (2) Preparation of ASP ion intercalated LDH coating;

[0071] A 60 mmol / L Mg(NO3)2·6H2O, 20 mmol / L Al(NO3)3·9H2O and 16 mmol / L ASP deionized aqueous solution was prepared under nitrogen protection, and then the pH of the solution was adjusted to 10 using 2 mol / L NaOH to obtain a reaction solution;

[0072] The pretreated magnesium substrate in step (1) and the reaction solution were placed in a hydrothermal reaction kettle and reacted at 120°C for 15 hours to obtain an ASP ion intercalated LDH coating on the surface of the magnesium.

[0073] (3) Preparation of LDH coating with ASP and silicate ion intercalation;

[0074] A 50 mmol / L Na2SiO3·9H2O deionized aqueous solution was prepared, the ASP ion intercalated LDH coating modified magnesium sample obtained in step (2) and the prepared Na2SiO3 aqueous solution were placed in a hydrothermal reaction kettle, and reacted at 90°C for 2 hours to obtain an LDH coating with ASP and silicate ion intercalation on the surface of the pure magnesium substrate.

[0075] Example 3

[0076] The preparation method of the magnesium-based material surface protective coating provided in this embodiment includes the following steps:

[0077] (1) Pretreatment of AZ31B magnesium alloy substrate;

[0078] A 10mm x 10mm x 10mm AZ31B magnesium alloy sample was polished with 500#, 1000# and 2000# sandpaper in sequence, and then ultrasonically treated in anhydrous ethanol for 10 minutes and dried.

[0079] (2) Preparation of LDH coating with ASP ion intercalation;

[0080] Under nitrogen protection, a 60mmol / L Mg(NO3)2·6H2O, 20mmol / L Al(NO3)3·9H2O and 6.6mmol / L ASP deionized water solution was prepared, and then the pH of the solution was adjusted to 12 using 2mol / L NaOH to obtain a reaction solution;

[0081] The pretreated AZ31B magnesium alloy substrate of step (1) and the reaction solution were placed in a hydrothermal reactor, and reacted at 140℃ for 12 hours to obtain an LDH coating with ASP ion intercalation on the surface of the magnesium alloy.

[0082] (3) Preparation of LDH coating with ASP and silicate ion co-intercalation.

[0083] A 50mmol / L Na2SiO3·9H2O deionized water solution was prepared, and the ASP ion intercalated LDH coating modified AZ31B magnesium alloy sample obtained in step (2) and the prepared Na2SiO3 water solution were placed in a hydrothermal reactor and reacted at 90℃ for 2 hours to obtain an LDH coating with ASP and silicate ion co-intercalation on the surface of the AZ31B magnesium alloy.

[0084] Example 4

[0085] The preparation method of the magnesium-based material surface protective coating provided in this embodiment includes the following steps:

[0086] (1) Pretreatment of AZ31B magnesium alloy substrate;

[0087] A 10mm x 10mm x 10mm AZ31B magnesium alloy sample was polished with 500#, 1000# and 2000# sandpaper in sequence, and then ultrasonically treated in anhydrous ethanol for 10 minutes and dried.

[0088] (2) Preparation of LDH coating with ASP ion intercalation;

[0089] A solution of 60 mmol / L Zn(NO3)2·6H2O, 20 mmol / L Al(NO3)3·9H2O and 6.6 mmol / L ASP in deionized water was prepared under nitrogen protection, and then the pH of the solution was adjusted to 12 using 2 mol / L NaOH to obtain a reaction solution;

[0090] The pretreated magnesium alloy substrate of step (1) and the reaction solution were placed in a hydrothermal reactor, and reacted at 120℃ for 15 hours to obtain an ASP ion intercalated LDH coating on the surface of the magnesium alloy.

[0091] (3) Preparation of an ASP and silicate ion co-intercalated LDH coating.

[0092] A solution of 50 mmol / L Na2SiO3·9H2O in deionized water was prepared, and the ASP ion intercalated LDH coating modified AZ31B magnesium alloy sample obtained in step (2) and the prepared Na2SiO3 aqueous solution were placed in a hydrothermal reactor and reacted at 80℃ for 4 hours to obtain an ASP and silicate ion co-intercalated LDH coating on the surface of the AZ31B magnesium alloy.

[0093] Example 5

[0094] The preparation method of the magnesium-based material surface protective coating provided in this embodiment includes the following steps:

[0095] (1) Pretreatment of the AZ31B magnesium alloy substrate;

[0096] A 10mm x 10mm x 10mm AZ31B magnesium alloy sample was polished with 500#, 1000# and 2000# sandpaper in sequence, ultrasonically cleaned in anhydrous ethanol for 10 minutes, and then blown dry.

[0097] (2) Preparation of an ASP ion intercalated LDH coating;

[0098] A solution of 45 mmol / L Mg(NO3)2·6H2O, 15 mmol / L Fe(NO3)3·9H2O and 2 mmol / L sodium aspartate in deionized water was prepared under nitrogen protection, and then the pH of the solution was adjusted to 11 using 2 mol / L NaOH to obtain a reaction solution;

[0099] The pretreated AZ31B magnesium alloy substrate of step (1) and the reaction solution were placed in a hydrothermal reactor, and reacted at 110℃ for 25 hours to obtain an ASP ion intercalated LDH coating on the surface of the magnesium alloy.

[0100] (3) Preparation of an ASP and silicate ion co-intercalated LDH coating.

[0101] A 35 mmol / L Na2SiO3·9H2O deionized aqueous solution was prepared, the ASP ion intercalated LDH coating modified magnesium alloy sample obtained in step (2) and the prepared Na2SiO3 aqueous solution were placed in a hydrothermal reactor, and the reaction was carried out at 60°C for 8 hours to obtain an ASP ion and silicate ion co-intercalated LDH coating on the surface of the AZ31B magnesium alloy.

[0102] Example 6

[0103] The preparation method of the protective coating with self-healing ability provided in this embodiment comprises the following steps:

[0104] (1) Pretreatment of pure magnesium substrate;

[0105] An AZ31B magnesium alloy sample with a size of 10 mm x 10 mm x 10 mm was polished with 500#, 1000# and 2000# sandpaper in sequence, ultrasonically cleaned in anhydrous ethanol for 10 minutes, and then blown dry.

[0106] (2) Preparation of ASP ion intercalated LDH coating;

[0107] A 120 mmol / L Cu(NO3)2·3H2O, 40 mmol / L Al(NO3)3·9H2O and 25 mmol / L potassium aspartate deionized aqueous solution was prepared under nitrogen protection, and then the pH of the solution was adjusted to 12 using 2 mol / L NaOH to obtain a reaction solution;

[0108] The pretreated magnesium substrate in step (1) and the reaction solution were placed in a hydrothermal reactor and reacted at 150°C for 5 hours to obtain an ASP ion intercalated LDH coating on the surface of the magnesium.

[0109] (3) Preparation of ASP and silicate ion co-intercalated LDH coating;

[0110] A 150 mmol / L Na2SiO3·9H2O deionized aqueous solution was prepared, the ASP ion intercalated LDH coating modified magnesium sample obtained in step (2) and the prepared Na2SiO3 aqueous solution were placed in a hydrothermal reactor, and the reaction was carried out at 60°C for 8 hours to obtain an ASP and silicate ion co-intercalated LDH coating on the surface of the pure magnesium substrate.

[0111] Comparative Example 1

[0112] Comparative Example 1 differs from Example 1 in that:

[0113] No ASP was added in step (2), and step (3) was not performed, and an LDH coating (AZ / L) was obtained on the surface of the AZ31B magnesium alloy in step (2).

[0114] Comparative Example 2

[0115] Comparative Example 1 differs from Example 1 in that:

[0116] Step (3) was not included, and in Step (2) an ASP ion intercalated LDH coating was obtained on the surface of the AZ31B magnesium alloy (AZ / LA).

[0117] Comparative Example 3

[0118] Comparative Example 3 differs from Example 1 in that:

[0119] Step (2) was not included, and in Step (3) a silicate ion intercalated LDH coating was obtained on the surface of the AZ31B magnesium alloy (AZ / LS).

[0120] Figure 1 The surface morphology of the AZ / LAS sample prepared in Example 1 was observed under a scanning electron microscope, and the surface coating of the AZ / L, AZ / LA and AZ / LS samples in Comparative Examples 1-3 all exhibited similar morphologies, indicating that ion intercalation did not change the overall morphology, and that the different types of LDH coatings grew uniformly on the magnesium alloy substrate as a whole, exhibiting a typical sheet structure.

[0121] Figure 2 The cross-sectional view of the AZ / LAS sample prepared in Example 1 was observed under a scanning electron microscope, and the cross-sectional view of the LDH coating prepared in Comparative Example 1 was observed under a scanning electron microscope. Figure 2 It can be seen that there are no obvious cracks or defects between the coating and the magnesium alloy substrate, and the combination is firm.

[0122] The XRD pattern of the LDH coating modified sample (AZ / L) prepared in Comparative Example 1, the ASP ion intercalated LDH coating modified sample (AZ / LA) prepared in Comparative Example 2, the silicate ion intercalated LDH coating (AZ / LS) prepared in Comparative Example 3, and the ASP and silicate ion co-intercalated LDH coating modified sample (AZ / LAS) prepared in Example 1 is shown in Figure 3 .

[0123] It can be seen from Figure 3 that the LDH coating modified sample (AZ / L) prepared in Comparative Example 1, the ASP ion intercalated LDH coating modified sample (AZ / LA) prepared in Comparative Example 2, the silicate ion intercalated LDH coating modified sample (AZ / LS) prepared in Comparative Example 3, and the ASP and silicate ion co-intercalated LDH coating modified sample (AZ / LAS) prepared in Example 1 all exhibit the (003) characteristic diffraction peak position of LDH.

[0124] The 003 peak position (11.52°) of AZ / LA is shifted to the left relative to the 003 peak position (11.61°) of AZ / L, which is due to the fact that the ionic radius of ASP is larger than that of nitrate ion. According to the Bragg formula, the characteristic diffraction peak position is smaller when the ionic radius is larger. Since the ionic radius of silicate is between that of nitrate and ASP, the 003 peak position of AZ / LS is shifted to 11.60°. The introduction of silicate causes the characteristic diffraction peak position of AZ / LAS to further shift to a lower angle, to 11.24°. Therefore, it can be known that the aspartic acid and silicate co-intercalated hydrotalcite coating is successfully prepared on the magnesium alloy substrate. Compared with Example 1, the sample of Comparative Example 1 does not add ASP in step (2), and the ASP ion intercalated LDH coating cannot be prepared.

[0125] Comparative Example 4

[0126] Compared with Example 1, the difference is that:

[0127] In step (2), the pH of the solution is adjusted to 8 by using 2 mol / L NaOH to obtain a reaction solution, and the remaining steps are the same as those of Example 1. In step (3), an ASP and silicate ion co-intercalated LDH coating is obtained on the surface of the AZ31B magnesium alloy.

[0128] It is found through the test of Comparative Example 4 that if the pH value of the hydrothermal reaction solution is less than 9, the magnesium is relatively active, which will cause corrosion on the surface of the magnesium-based material, leading to rapid dissolution of magnesium, and thus it is impossible to form a coating with good coverage and stability, or even impossible to form a coating.

[0129] Similarly, when the pH value is greater than 13, a large amount of powdery precipitate will be formed on the surface of the substrate material, and it is impossible to form a uniform and well-bonded coating.

[0130] Comparative Example 5

[0131] Compared with Example 1, the difference is that:

[0132] In step (2), the pretreated AZ31B magnesium alloy substrate of step (1) and the reaction solution are placed in a hydrothermal reaction kettle, and reacted at 80°C for 15 hours. The remaining steps are the same as those of Example 1. In step (3), an ASP and silicate ion co-intercalated LDH coating is obtained on the surface of the AZ31B magnesium alloy.

[0133] It is found through the test of Comparative Example 5 that if the hydrothermal temperature is less than 100°C, the following effects may occur:

[0134] 1) Reduced reaction rate: Lower hydrothermal temperature will result in slower deposition reaction rate of LDH, thereby affecting the growth rate and uniformity of the coating. Under low temperature conditions, a relatively thin coating may be formed on the surface of the magnesium alloy, and the quality of the coating may not be as dense and uniform as that under higher temperature.

[0135] 2) Poor crystal structure: When the hydrothermal temperature is low, the crystallinity of the LDH crystal may be poor, and the LDH coating formed is not dense enough, which may affect the mechanical strength, corrosion resistance and adhesion to the substrate of the coating.

[0136] Comparative Example 6

[0137] Compared with Example 1, the difference is that:

[0138] (3) Preparation of LDH coating with co-intercalation of ASP and silicate ions;

[0139] A 50 mmol / L Na2SiO3·9H2O deionized aqueous solution was prepared, and the ASP ion-intercalated LDH coating modified magnesium alloy sample obtained in step (2) and the prepared Na2SiO3 aqueous solution were placed in a hydrothermal reactor, and reacted at 40℃ for 2 hours, to obtain an LDH coating with co-intercalation of ASP and silicate ions on the surface of the AZ31B magnesium alloy.

[0140] It was found through the test of Comparative Example 6 that when the ion exchange temperature is lower than 50℃, the following phenomena will be aggravated:

[0141] 1) Reaction rate reduction effect: The ion exchange reaction rate will be significantly reduced. Ion exchange usually requires a certain temperature to provide enough energy to drive ions to exchange from the solution to the substrate surface. When the temperature is too low, the diffusion rate of ions in the solution is slow, resulting in low reaction efficiency and slow coating formation speed;

[0142] 2) Incomplete intercalation of ions or unstable structure effect: The intercalation ions in the solution may not be completely intercalated into the LDH interlayer, resulting in uneven composition of the coating or lack of expected ion intercalation, especially for coatings that require intercalation of silicate ions. Low temperature may make the ion intercalation process incomplete.

[0143] It was found through the tests of Comparative Examples 4-6 that when the hydrothermal reaction pH value, temperature and ion exchange reaction temperature are not within the scope of the present application, the quality of the coating formed is very poor.

[0144] Second Part: Self-healing protective coating and method for preparing the same

[0145] 1. Corrosion resistance test of each sample

[0146] The LDH coating (AZ / L) prepared in Comparative Example 1, the ASP ion intercalated LDH coating modified sample (AZ / LA) prepared in Comparative Example 2, the silicate ion intercalated LDH coating modified sample (AZ / LS) prepared in Comparative Example 3, the coating modified sample (AZ / LAS) prepared in Example 1 and the substrate sample were subjected to the corrosion resistance test in the artificial simulated body fluid at 37°C, and the polarization curve results of each sample in the artificial simulated body fluid at 37°C are shown in the following figure. Figure 4

[0147] As can be seen from Figure 4 , the corrosion current density value of the AZ31B magnesium alloy substrate in the simulated body fluid is 1.50 x 10 -4 A·cm -2 , which is the highest among all samples, indicating that the AZ31B magnesium alloy substrate is very easy to be eroded, because it has high electrochemical activity and the corrosion products formed cannot provide effective protection, and rapid corrosion occurs in the simulated body fluid.

[0148] Compared with the AZ31B substrate, the corrosion current density of the LDH coating sample (AZ / L) prepared in Comparative Example 1 is reduced by nearly 2 orders of magnitude to 3.24 x 10 -6 A cm -2 , which is much lower than the value of the AZ31B substrate sample, and the degradation is obviously inhibited.

[0149] Compared with the AZ31B substrate, the corrosion current density of the ASP ion intercalated LDH coating modified sample (AZ / LA) prepared in Comparative Example 2 is further reduced, which is attributed to the active sites of the ASP ion polar groups released from the LDH interlayer, which interact with magnesium ions and can be effectively adsorbed on the magnesium-based material to form metal chelates, so that the coating is self-healing and plays a good corrosion protection role on the magnesium substrate.

[0150] It is worth noting that the corrosion current density of the ASP and silicate ion co-intercalated LDH coating modified sample (AZ / LAS) prepared in Example 1 is significantly lower than the corrosion current density value of the ASP ion intercalated LDH coating modified sample (AZ / LA) prepared in Comparative Example 2 and the corrosion current density value of the silicate ion intercalated LDH coating modified sample (AZ / LS) in Comparative Example 3, which may be due to the fact that the silicate ions released from the LDH coating layer form a difficultly soluble magnesium silicate precipitate covering the corrosion site with the magnesium ions dissolved from the substrate, further preventing corrosion from occurring, and the ASP and silicate ions play a synergistic corrosion inhibition effect, forming a high protection performance composite coating, which effectively slows down the degradation of the magnesium substrate. In addition, since ASP and silicate have good biocompatibility, such ASP and silicate ion co-intercalated LDH coating can not only be used in industrial environments such as the ocean, but also be suitable for corrosion protection of medical materials.

[0151] ​2. Mouse preosteoblast adhesion test on each sample surface

[0152] The LDH coating (AZ / L) prepared in Comparative Example 1, the modified LDH coating sample (AZ / LA) with ASP ion intercalation prepared in Comparative Example 2, the silicate intercalated LDH coating (AZ / LS) prepared in Comparative Example 3, the modified coating sample (AZ / LAS) prepared in Example 1, and the AZ31B substrate sample were disinfected with 75% ethanol and placed in a 24-well cell culture plate. 50,000 MC3T3-E1 mouse preosteoblasts were added to each of the sample wells. After 12 hours of co-culture, the cells were fixed with 4% paraformaldehyde for 15 minutes, then stained for cytoskeleton with phalloidin for 40 minutes, and then stained for nuclei with 4,6-diamidino-2-phenylindole for 5 minutes. Finally, the morphology and number of cells on the sample surface were observed under a fluorescence microscope, and statistical calculations were performed.

[0153] The results of mouse preosteoblast adhesion on the surface of the LDH coating (AZ / L) prepared in Comparative Example 1, the LDH coating modified sample (AZ / LA) with ASP ion intercalation prepared in Comparative Example 2, the LDH coating modified sample (AZ / LS) with silicate ion intercalation prepared in Comparative Example 3, the coating modified sample (AZ / LAS) prepared in Example 1 and the AZ31B substrate sample are shown in FIG. Figure 5 As shown, (a) AZ31B substrate sample, (b) LDH coating prepared in comparative example 1 (AZ / L), (c) LDH coating modified sample (AZ / LA) with ASP ion intercalation prepared in comparative example 2, (d) LDH coating modified sample (AZ / LS) with silicate ion intercalation prepared in comparative example 3, (e) coating modified sample (AZ / LAS) prepared in example 1, and (f) statistical results of the number of adhered cells.

[0154] from Figure 5 As can be seen in the figure, after 12 hours of cell culture on the sample surface, the cells on the substrate sample exhibited an irregular shape, a small spreading area, and a cell count of 37 ± 4. In contrast, the LDH coating-modified sample (AZ / L), the LDH coating-modified sample intercalated with aspartic acid (AZ / LA), and the LDH coating-modified sample intercalated with silicate ions (AZ / LS) exhibited increased cell numbers and good cell spreading, with clearly observed pseudopodia. The cell counts on the sample surfaces were 47 ± 13, 54 ± 2, and 45 ± 7, respectively. The LDH coating-modified sample co-intercalated with aspartic acid and silicate (AZ / LAS) exhibited the highest cell count, reaching 85 ± 6, and the best spreading, demonstrating the best cell attachment and spreading behavior.

[0155] ASP is widely present in nature and participates in many life processes, and has good biocompatibility, providing a non-toxic repair material for coating; silicon is one of the essential trace elements for forming normal human bone tissue, cartilage tissue and connective tissue, participates in the physiological process of regulating osteogenesis and bone calcification, and plays an important role in bone metabolism. It can be seen that ASP and silicon have good biocompatibility and are expected to play a certain role in promoting osteogenesis. Such ASP and silicate ion intercalated LDH coating is not only suitable for medical materials with good biocompatibility, but especially suitable for corrosion protection of medical materials.

[0156] The above describes the embodiments of the present application in detail, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations of the embodiments can be made without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A method for preparing a self-healing protective coating on a magnesium-based material surface, characterized by, The method comprises the following steps: (1) surface pretreatment of the magnesium-based material; (2) preparation of the LDH coating intercalated with the organic corrosion inhibitor: under a protective atmosphere, an aqueous solution of divalent metal ion salt, trivalent metal ion salt and organic corrosion inhibitor is prepared, and the pH is adjusted to obtain a reaction solution; the pretreated magnesium-based material in step (1) and the reaction solution are placed in a hydrothermal reaction vessel to perform a hydrothermal reaction, and an LDH coating intercalated with the organic corrosion inhibitor is obtained on the surface of the magnesium-based material; (3) preparation of the LDH coating intercalated with both the organic corrosion inhibitor and the inorganic corrosion inhibitor: an aqueous solution of the inorganic corrosion inhibitor is prepared; the magnesium-based material with the LDH coating intercalated with the organic corrosion inhibitor obtained in step (2) is immersed in the aqueous solution of the inorganic corrosion inhibitor to perform an ion exchange reaction, and an LDH self-healing protective coating intercalated with both the organic corrosion inhibitor and the inorganic corrosion inhibitor is obtained on the surface of the magnesium-based material; in step (2), the organic corrosion inhibitor is one or more of aspartic acid, sodium aspartate and potassium aspartate, and the concentration of the organic corrosion inhibitor is 0.6-30 mmol / L; in step (2), the temperature of the hydrothermal reaction is 100-160 ℃, and the time is 1-30 h; in step (3), the inorganic corrosion inhibitor is sodium silicate; in step (3), the concentration of the aqueous solution of the inorganic corrosion inhibitor is 15-150 mmol / L; in step (3), the temperature of the ion exchange reaction is 50-100 ℃, and the time is 1-10 h.

2. The method of claim 1, wherein the magnesium-based material surface self-healing protective coating is prepared by, in step (1), the magnesium-based material is magnesium, magnesium alloy, magnesium-containing porous material, magnesium alloy-containing porous material, material treated on the surface of magnesium, material treated on the surface of magnesium alloy, material treated on the surface of magnesium porous material or material treated on the surface of magnesium alloy porous material; in step (1), the surface pretreatment of the magnesium-based material comprises polishing the magnesium-based material to remove surface oxides and impurities, and then cleaning and blowing dry.

3. The method of claim 1, wherein the magnesium-based material surface self-healing protective coating is prepared by the steps of: a) providing a magnesium-based material; b) applying a magnesium-based material surface self-healing protective coating to the magnesium-based material; and c) annealing the magnesium-based material surface self-healing protective coating. in step (2), the divalent metal ion salt is one or more of magnesium nitrate, zinc nitrate and copper nitrate; the concentration of the divalent metal ion salt is 30-120 mmol / L; the trivalent metal ion salt is one or both of aluminum nitrate and iron nitrate; and the concentration of the trivalent metal ion salt is 10-40 mmol / L.

4. The method of claim 1, wherein the magnesium-based material surface self-healing protective coating is prepared by, in step (2), the protective atmosphere is one or more of nitrogen, argon and helium; and in step (2), the pH is adjusted to 9-13.

5. A self-healing protective coating for a magnesium-based material surface, characterized by, The magnesium-based material surface self-healing protective coating is prepared by the method described in any one of claims 1-4.

6. Use of the magnesium-based material surface self-healing protective coating described in claim 5 in the preparation of corrosion protection materials or biocompatible materials.

Images