Micro-arc oxidation method for valve metal reinforced magnesium-based composite material and surface corrosion-resistant micro-arc oxidation coating of valve metal reinforced magnesium-based composite material

Abstract

The invention relates to a micro-arc oxidation method for a valve metal reinforced magnesium-based composite material and a surface corrosion-resistant micro-arc oxidation coating of the valve metal reinforced magnesium-based composite material. The method comprises the steps that firstly, a micro-arc oxidation electrolyte is prepared, then the valve metal reinforced magnesium composite material is subjected to oxidation treatment in the prepared micro-arc oxidation electrolyte in a constant-current mode, the micro-arc oxidation current ranges from 5 A / dm < 2 > to 12 A / dm < 2 >, and the micro-arc oxidation treatment time ranges from 5 min to 30 min. The micro-arc oxidation electrolyte is composed of a main salt, an additive, a pH regulator and deionized water, the mass concentration of the main salt is 10-35 g / L, the mass concentration of the additive is 0-20 g / L, and the mass concentration of the pH regulator is 0-5 g / L. Through the synergistic coupling effect of the main salt and the additive (including the pH regulator) and in combination with reasonable parameter configuration in a constant current mode, the discharge intensity difference between valve metal reinforced particles and a magnesium matrix is inhibited, the uniformity and compactness of the coating are optimized, and the micro-arc oxidation coating with excellent corrosion resistance is obtained. The method is particularly suitable for obtaining a coating with excellent corrosion resistance on the surface of the magnesium-based composite material reinforced by valve metal particles such as Ti, Nb and Zr.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a micro-arc oxidation method for a valve metal reinforced magnesium-based composite material and a surface corrosion-resistant micro-arc oxidation coating thereof. Background Art

[0002] With the growing global demand for energy conservation, emission reduction and lightweight materials, magnesium alloys, as the lightest structural materials, have great application potential in aerospace, automobile manufacturing and renewable energy. However, the inherent limitations of magnesium alloys, including low absolute strength, limited plastic deformation capacity and poor corrosion resistance, must be addressed. The introduction of metal particles such as Cu, Ti, Mn, Nb, Zr, etc. into magnesium alloys to make magnesium-based composites has been shown to improve strength and ductility. Due to the high electrochemical activity of magnesium, the corrosion resistance of composites still needs to be improved. Surface treatment provides an effective and direct method to improve surface properties such as corrosion resistance. Among these technologies, micro-arc oxidation is widely used for surface treatment of alloys such as aluminum, magnesium and titanium due to its low cost and environmental friendliness.

[0003] However, unlike conventional magnesium alloys, the presence of metal reinforcement phase in magnesium-based composites changes their micro-arc oxidation discharge behavior. The metal reinforcement phase has an adverse effect on the discharge and growth of micro-arc oxidation coatings on magnesium-based composites, thereby affecting the corrosion resistance of the coatings. For example, compared with AZ91, the thickness of the micro-arc oxidation coating on AZ91 / Ti composites is reduced and the porosity is increased. Therefore, optimizing the structure of micro-arc oxidation coatings on magnesium-based composites to obtain excellent corrosion resistance is crucial for its practical application. Summary of the invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides a method for micro-arc oxidation of a valve metal reinforced magnesium-based composite material and a surface corrosion-resistant micro-arc oxidation coating thereof. The method suppresses the difference in discharge intensity between valve metal reinforced particles and magnesium matrix through the synergistic coupling effect of the main salt and additives (including pH regulators), combined with reasonable parameter configuration in the constant current mode, optimizes the uniformity and density of the coating, and obtains a micro-arc oxidation coating with excellent corrosion resistance. On the one hand, the main salt can make the magnesium matrix region and the valve metal enhanced phase region form a uniform film; on the other hand, the additive can change the physical phase composition of the magnesium matrix region and the enhanced phase region coating through the doping effect, optimize the dielectric properties of the coating, thereby greatly reducing the difficulty of discharge breakdown in the two-phase region, suppressing the continuous strong discharge in the enhanced phase region, and making the coating uniform and dense. The present invention is particularly suitable for obtaining a coating with excellent corrosion resistance on the surface of magnesium-based composite materials reinforced with valve metal particles such as Ti, Nb, and Zr.

[0005] According to a first aspect of the technical solution of the present invention, a method for micro-arc oxidation of a valve metal reinforced magnesium-based composite material is provided, wherein the method comprises the following steps:

[0006] S1: Prepare the micro-arc oxidation electrolyte, completely dissolve 10-35g / L of the main salt, 0-20g / L of the additive and 0-5g / L of the pH adjuster in deionized water to form a uniform aqueous solution and place it in the micro-arc oxidation tank.

[0007] S2: Preparation of micro-arc oxidation coating. Connect the valve metal particle reinforced magnesium-based composite material sample to the anode of the micro-arc oxidation power supply, immerse the sample in the micro-arc oxidation electrolyte, and then start the power supply to perform micro-arc oxidation treatment in a constant current mode, so as to prepare a corrosion-resistant micro-arc oxidation coating on the surface of the valve metal particle reinforced magnesium-based composite material sample, thereby realizing micro-arc oxidation.

[0008] According to the aspects and any possible implementation methods described above, an implementation method is further provided, wherein the valve metal in the valve metal reinforced magnesium-based composite material is any one of pure metal or alloy particles of Ti, Nb and Zr, the particles are spherical or irregular in shape, the particle content is less than 25wt%, and the particle size is 50nm to 50μm.

[0009] Aspects as described above and any possible implementations further provide an implementation, wherein the main salt is a combination of any two or more of sodium silicate nonahydrate, sodium silicate pentahydrate, liquid sodium silicate, trisodium phosphate dodecahydrate, sodium hexametaphosphate, ammonium phosphate, and sodium dihydrogen phosphate dihydrate. The main salt functions to form a film quickly, and a reasonable combination is used to quickly form a film layer and a main phase component on the surface of the magnesium-based composite material. In addition, the oxidation of the matrix can also be accelerated, thereby increasing the content of matrix oxides. For example, for AZ91 / Ti, the addition of phosphates can simultaneously increase the oxidation of Mg and Ti, and increase the content of MgO and TiO2.

[0010] As described above, in any possible implementation, an implementation is further provided, wherein the additive is any one or more of sodium aluminate, sodium fluoroaluminate, titanyl sulfate, potassium titanate, magnesium titanate, and ammonium niobate. Further, the additive also contains any one or a combination of glycerol and PEG. The inorganic salt in the additive belongs to the coating electrical property regulator, which can react with the main phase in the coating to form a new phase after addition. On the one hand, the conductivity of the magnesium matrix region can be improved, and on the other hand, the dielectric constant of the metal enhanced phase region can be reduced. Thereby making the coating discharge on the magnesium matrix region and the metal enhanced phase region more uniform, which is conducive to the formation of a densified coating. The organic matter in the additive belongs to an auxiliary regulator, which is used to assist the inorganic additive in further controlling the discharge uniformity.

[0011] According to the above aspects and any possible implementation, an implementation is further provided, wherein the pH regulator is sodium hydroxide, potassium hydroxide, sodium carbonate, phosphoric acid, or sulfuric acid. The pH regulator is used to control the pH value and conductivity of the electrolyte, create the solution environment required for the corrosion-resistant coating, and achieve the purpose of balancing the coating thickness and porosity.

[0012] Here, in the process of preparing the micro-arc oxidation electrolyte, the content range of 10-35g / L of the main salt, 0-20g / L of the additive and 0-5g / L of the pH adjuster is selected for the purpose of controlling the film-forming speed and the uniformity of the discharge in the two-phase region to obtain a more uniform and dense coating. Specifically, the composition and concentration of the main salt and the pH adjuster have a great influence on the film-forming speed of different metals, and a relatively uniform coating can be obtained in this concentration range. Further, the two-phase region phase is regulated by the additive to achieve the purpose of homogenizing the dielectric properties of the two-phase coating. Exceeding this range is not conducive to the uniformity of the dielectric properties of the coating.

[0013] Preferably, the main salt is a combination of sodium silicate nonahydrate and sodium hexametaphosphate, wherein the mass concentration of sodium silicate nonahydrate is 12 g / L, and the mass concentration of sodium hexametaphosphate is 5 g / L; the additive is sodium aluminate, and its mass concentration is 0.5 g / L; the pH adjuster is sodium hydroxide, and its mass concentration is 0.5 g / L.

[0014] Preferably, the main salt is a combination of sodium silicate nonahydrate and trisodium phosphate dodecahydrate, wherein the mass concentration of sodium silicate nonahydrate is 12 g / L, and the mass concentration of trisodium phosphate dodecahydrate is 6 g / L; the additive is sodium aluminate and glycerol, wherein the mass concentration of sodium aluminate is 0.5 g / L, and the mass concentration of glycerol is 15 g / L; the pH adjuster is sodium hydroxide, and the mass concentration is 0.5 g / L.

[0015] According to the above aspects and any possible implementation, a further implementation is provided, in the constant current mode, the micro-arc oxidation current density is 5-12A / dm 2 , frequency is 500-1000Hz, duty cycle is 10%-50%, and micro-arc oxidation treatment time is 5-30min. This parameter setting can control the energy input intensity and coating film forming speed.

[0016] Preferably, in the constant current mode, the micro-arc oxidation current density is 5A / dm 2 , frequency is 500 Hz, duty cycle is 20%, and micro-arc oxidation treatment time is 15 min.

[0017] According to a second aspect of the technical solution of the present invention, a corrosion-resistant micro-arc oxidation coating on the surface of a valve metal reinforced magnesium-based composite material is provided, wherein the corrosion-resistant micro-arc oxidation coating is obtained by the method described in any one of the above aspects.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention discloses a method for preparing a micro-arc oxidation corrosion-resistant coating of a valve metal reinforced magnesium-based composite material. The micro-arc oxidation electrolyte developed for the valve metal reinforced magnesium-based composite material comprises a main salt, an additive, a pH regulator and water; wherein the main salt mass concentration is 10-35 g / L, the additive mass concentration is 0-4 g / L, and the pH regulator mass concentration is 0-5 g / L, so as to have the following beneficial effects: (1) enhancing the uniform film-forming ability of the valve metal reinforced magnesium-based composite material. Valve metals such as Mg, Ti, Nb, and Zr have different film-forming abilities in several common micro-arc oxidation electrolyte systems, which results in poor film-forming uniformity of the valve metal reinforced magnesium-based composite material in common micro-arc oxidation electrolyte systems, limiting the voltage climbing rate of micro-arc oxidation. The electrolyte combination of the present invention can achieve uniform film formation in the magnesium matrix region and the valve metal reinforcement phase region.

[0020] (2) Enhance the discharge uniformity of valve metal reinforced magnesium-based composite materials. The physical differences formed by Mg, Ti, Nb, Zr, etc. in several common micro-arc oxidation electrolyte systems lead to obvious differences in the physical composition of the magnesium matrix region and the reinforcement phase region of the valve metal reinforced magnesium-based composite materials, which makes the discharge breakdown difficulty of the two phase regions different, that is, the reinforcement phase region is more likely to discharge and produce a discharge channel that penetrates the coating. The electrolyte combination of the present invention can change the physical composition of the magnesium matrix region and the reinforcement phase region coating, thereby greatly reducing the discharge breakdown difficulty of the two phase regions, inhibiting the continuous discharge of the reinforcement phase region, and making the coating uniform and densified. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flow chart of the method of the present invention;

[0022] Figure 2 The voltage-time curves of micro-arc oxidation of Example 1, Example 2 and Comparative Example 1 are shown;

[0023] Figure 3 The micro-arc oxidation coating morphology of Example 2, wherein (a) is the surface morphology and (b) is the cross-sectional morphology;

[0024] Figure 4 The morphology of the micro-arc oxidation coating of Control Example 1, wherein (a) is the surface morphology and (b) is the cross-sectional morphology. DETAILED DESCRIPTION

[0025] In order to better understand the technical solution of the present invention, the content of the present invention includes but is not limited to the specific implementation methods described below, and similar technologies and methods should be considered to be within the scope of protection of the present invention. In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] It should be clear that the embodiments described in the present invention are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0028] The technical solution of the present invention first provides a method for preparing a valve metal reinforced magnesium-based composite material micro-arc oxidation corrosion-resistant coating, such as Figure 1 As shown, the following steps are included:

[0029] S101: Prepare a micro-arc oxidation electrolyte, completely dissolve 10-35 g / L of main salt, 0-20 g / L of additives and 0-2 g / L of pH adjuster in deionized water to form a uniform aqueous solution and place it in a micro-arc oxidation tank.

[0030] In a preferred embodiment, the main salt is any one or more of sodium silicate nonahydrate, sodium silicate pentahydrate, liquid sodium silicate, trisodium phosphate dodecahydrate, sodium hexametaphosphate, ammonium phosphate, and sodium dihydrogen phosphate dihydrate.

[0031] In a preferred embodiment, it is characterized in that the additive is a combination of any one or more of sodium aluminate, potassium titanate, magnesium titanate, glycerol, and PEG.

[0032] In a preferred embodiment, the micro-arc oxidation electrolyte is specially optimized for valve metal reinforced magnesium-based composite materials, which can promote rapid film formation on the workpiece surface, optimize the coating discharge behavior and obtain a uniform and dense micro-arc oxidation coating. The micro-arc oxidation electrolyte can only contain main salt, pH regulator and deionized water, and can be used for micro-arc oxidation treatment with or without additives.

[0033] In a preferred embodiment, the main salt is a combination of sodium silicate nonahydrate and sodium hexametaphosphate, wherein the mass concentration of sodium silicate nonahydrate is 12 g / L, and the mass concentration of sodium hexametaphosphate is 5 g / L; the additive is sodium aluminate, and its mass concentration is 0.5 g / L; the pH adjuster is sodium hydroxide, and its mass concentration is 0.5 g / L.

[0034] In a preferred embodiment, the main salt is a combination of sodium silicate nonahydrate and trisodium phosphate dodecahydrate, wherein the mass concentration of sodium silicate nonahydrate is 12 g / L, and the mass concentration of trisodium phosphate dodecahydrate is 6 g / L; the additive is sodium aluminate and glycerol, wherein the mass concentration of sodium aluminate is 0.5 g / L, and the mass concentration of glycerol is 15 g / L; the pH adjuster is sodium hydroxide, and the mass concentration is 0.5 g / L.

[0035] S102: Preparation of micro-arc oxidation coating, connecting the valve metal particle reinforced magnesium-based composite material sample to the anode of the micro-arc oxidation power supply, and immersing the sample in the micro-arc oxidation electrolyte, then starting the power supply to perform micro-arc oxidation treatment in a constant current mode, and preparing a corrosion-resistant micro-arc oxidation coating on the surface of the valve metal particle reinforced magnesium-based composite material sample, thereby achieving micro-arc oxidation.

[0036] In a preferred embodiment, in the constant current mode, the micro-arc oxidation current density is 5-12A / dm 2 , frequency is 500-1000Hz, duty cycle is 10%-50%, and micro-arc oxidation treatment time is 5-30min.

[0037] In a preferred embodiment, in the constant current mode, the micro-arc oxidation current density is 5A / dm 2 , frequency is 500 Hz, duty cycle is 20%, and micro-arc oxidation treatment time is 15 min.

[0038] The technical solution of the present invention also provides a corrosion-resistant micro-arc oxidation coating on the surface of a valve metal reinforced magnesium-based composite material, wherein the corrosion-resistant micro-arc oxidation coating is obtained according to the method described above.

[0039] The method of the present invention is specifically described below using examples.

[0040] Example 1

[0041] AZ91 / Ti (pure Ti, 5wt%) composite material was used as a sample to prepare the coating in a micro-arc oxidation electrolyte without using additives. The specific implementation process is as follows:

[0042] 1. Prepare an electrolyte. The main salt is a combination of sodium silicate nonahydrate and sodium hexametaphosphate, and the mass concentration of the sodium silicate nonahydrate is 12g / L, and the mass concentration of the sodium hexametaphosphate is 5g / L; the pH adjuster is sodium hydroxide, with a mass concentration of 1g / L, and 1L of electrolyte is prepared.

[0043] 2. Cut the AZ91 / Ti composite material into disc-shaped samples, polish them with sandpaper to 2000#, clean them with alcohol and blow them dry, and then connect them to the positive electrode of the micro-arc oxidation power supply.

[0044] 3. Select the constant current mode in the micro-arc oxidation power supply and set the micro-arc oxidation current density to 5A / dm 2 , frequency is 500 Hz, duty cycle is 20%, and micro-arc oxidation treatment time is 15 min.

[0045] 4. After the micro-arc oxidation treatment is completed, take out the sample, wash it with running water and blow it dry.

[0046] Example 1 shows that the coating can be prepared when the micro-arc oxidation electrolyte does not use additives, but the voltage rise rate during the preparation process is slow (e.g. Figure 2 The sample prepared in this embodiment was tested, and the results showed that the coating thickness was about 25 μm, the coating porosity was 7.5%, and the self-corrosion current density was 3.8×10 -7 A / cm 2 .

[0047] Example 2

[0048] AZ91 / Ti (pure Ti, 5wt%) composite material was used as a sample, and the coating was prepared in a micro-arc oxidation electrolyte using an additive. The specific implementation process is as follows:

[0049] 1. Prepare the electrolyte. The main salt is a combination of sodium silicate nonahydrate and sodium hexametaphosphate, where the mass concentration of sodium silicate nonahydrate is 12g / L and the mass concentration of sodium hexametaphosphate is 5g / L. Sodium aluminate is used as an additive with a mass concentration of 0.5g / L. Sodium hydroxide is used as a pH adjuster with a mass concentration of 0.5g / L to prepare 1L of electrolyte.

[0050] 2. Cut the AZ91 / Ti composite material into disc-shaped samples, polish them with sandpaper to 2000#, clean them with alcohol and blow them dry, and then connect them to the positive electrode of the micro-arc oxidation power supply.

[0051] 3. Select the constant current mode in the micro-arc oxidation power supply and set the micro-arc oxidation current density to 5A / dm 2 , frequency is 500 Hz, duty cycle is 20%, and micro-arc oxidation treatment time is 15 min.

[0052] 4. After the micro-arc oxidation treatment is completed, take out the sample, wash it with running water and blow it dry.

[0053] Example 2 shows that after the electrolyte is added with additives, the micro-arc oxidation voltage rises rapidly, suppressing the voltage delay platform existing in the early stage of micro-arc oxidation of magnesium-based composite materials, which is conducive to rapid film formation (such as Figure 2 In addition, from Figure 3 The morphology shows that the coating is more uniform and dense. This indicates that the electrolyte combination of this embodiment can make the AZ91 / Ti composite material discharge more uniformly. The samples prepared in this embodiment were tested, and the results showed that the coating thickness was about 30 μm, the coating porosity was 6.5%, and the self-corrosion current density was 2.1×10 -7 A / cm 2 .

[0054] Example 3

[0055] AZ91 / Ti (pure Ti, 5wt%) composite material was used as a sample, and the coating was prepared in a micro-arc oxidation electrolyte using an additive. The specific implementation process is as follows:

[0056] 1. Prepare the electrolyte. The main salt is a combination of sodium silicate nonahydrate and trisodium phosphate dodecahydrate, where the mass concentration of sodium silicate nonahydrate is 12g / L and the mass concentration of trisodium phosphate dodecahydrate is 6g / L. The additives are sodium aluminate and glycerol, where the mass concentration of sodium aluminate is 0.5g / L and the mass concentration of glycerol is 15g / L. The pH adjuster is sodium hydroxide with a mass concentration of 0.5g / L, and 1L of electrolyte is prepared.

[0057] 2. Cut the AZ91 / Ti composite material into disc-shaped samples, polish them with sandpaper to 2000#, clean them with alcohol and blow them dry, and then connect them to the positive electrode of the micro-arc oxidation power supply.

[0058] 3. Select the constant current mode in the micro-arc oxidation power supply and set the micro-arc oxidation current density to 5A / dm 2 , frequency is 500 Hz, duty cycle is 20%, and micro-arc oxidation treatment time is 15 min.

[0059] 4. After the micro-arc oxidation treatment is completed, take out the sample, wash it with running water and blow it dry.

[0060] The electrolyte combination of Example 3 can further control the discharge intensity and discharge uniformity of the magnesium matrix region and the Ti reinforcement phase region during micro-arc oxidation of the AZ91 / Ti composite material. The obtained coating has higher uniformity and density. The samples prepared in this example were tested, and the results showed that the coating thickness was about 30 μm, the coating porosity was 6%, and the self-corrosion current density was 1.1×10 -7 A / cm 2 .

[0061] Comparative Example 1

[0062] AZ91 / Ti (pure Ti, 5wt%) composite material was used as a sample. The difference between Control Example 1 and Examples 1-3 is that the electrolyte is only a combination of sodium silicate nonahydrate and sodium hydroxide, which represents the commonly used electrolyte for micro-arc oxidation of magnesium alloys.

[0063] from Figure 4 The coating morphology shows that the coating surface is relatively rough and the cross-sectional morphology shows through discharge holes. The control example shows that the discharge of AZ91 / Ti composite material is uneven, that is, the electrolyte combination commonly used for magnesium alloy is not suitable for AZ91 / Ti composite material. The samples prepared in the control example were tested, and the results showed that the coating thickness was about 25μm, the coating porosity was 13%, and the self-corrosion current density was 1.5×10 -6 A / cm 2 .

[0064] Comparative Example 2

[0065] AZ91 magnesium alloy was used as the sample, and the electrolyte was only a combination of sodium silicate nonahydrate and sodium hydroxide, which represents the micro-arc oxidation of ordinary magnesium alloys in a common magnesium alloy micro-arc oxidation electrolyte.

[0066] When AZ91 magnesium alloy is micro-arc oxidized in common electrolyte, the voltage rises rapidly and there is no delay platform (such as Figure 2 The samples prepared in the control example were tested, and the results showed that the coating thickness was about 32 μm, the coating porosity was 6.5%, and the self-corrosion current density was 5×10 -7 A / cm 2 .

[0067] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not depart from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A method for micro-arc oxidation of valve metal reinforced magnesium-based composite materials, characterized in that: The steps include: S1: Prepare micro-arc oxidation electrolyte, completely dissolve 10-35g / L of main salt, 0-20g / L of additives and 0-5g / L of pH adjuster in deionized water to form a uniform aqueous solution and place it in a micro-arc oxidation tank; S2: Preparation of micro-arc oxidation coating. Connect the valve metal particle reinforced magnesium-based composite material sample to the anode of the micro-arc oxidation power supply, immerse the sample in the micro-arc oxidation electrolyte, and then start the power supply to perform micro-arc oxidation treatment in a constant current mode, so as to prepare a corrosion-resistant micro-arc oxidation coating on the surface of the valve metal particle reinforced magnesium-based composite material sample, thereby realizing micro-arc oxidation.

2. The micro-arc oxidation method for valve metal reinforced magnesium-based composite materials according to claim 1, characterized in that: The valve metal in the valve metal reinforced magnesium-based composite material is any one of pure metal or alloy particles of Ti, Nb and Zr, the particles are spherical or irregular in shape, the particle content is less than 25wt%, and the particle size is 50nm to 50μm.

3. The micro-arc oxidation method for valve metal reinforced magnesium-based composite materials according to claim 1, characterized in that: The main salt is a combination of any two or more of sodium silicate nonahydrate, sodium silicate pentahydrate, liquid sodium silicate, trisodium phosphate dodecahydrate, sodium hexametaphosphate, ammonium phosphate, and sodium dihydrogen phosphate dihydrate.

4. The micro-arc oxidation method for valve metal reinforced magnesium-based composite materials according to claim 3, characterized in that: The additive is any one or more combinations of sodium aluminate, sodium fluoroaluminate, titanyl sulfate, potassium titanate, magnesium titanate, and ammonium niobate; Wherein, the additive further comprises any one or more combinations of glycerol and PEG.

5. The micro-arc oxidation method for valve metal reinforced magnesium-based composite materials according to claim 4, characterized in that: The pH regulator is sodium hydroxide, potassium hydroxide, sodium carbonate, phosphoric acid, and sulfuric acid.

6. The micro-arc oxidation method for valve metal reinforced magnesium-based composite materials according to claim 5, characterized in that: The main salt is a combination of sodium silicate nonahydrate and sodium hexametaphosphate, wherein the mass concentration of the sodium silicate nonahydrate is 12 g / L; the mass concentration of the sodium hexametaphosphate is 5 g / L; the additive is sodium aluminate, and its mass concentration is 0.5 g / L; the pH adjuster is sodium hydroxide, and its mass concentration is 0.5 g / L.

7. The micro-arc oxidation method for valve metal reinforced magnesium-based composite materials according to claim 5, characterized in that: The main salt is a combination of sodium silicate nonahydrate and trisodium phosphate dodecahydrate, wherein the mass concentration of sodium silicate nonahydrate is 12 g / L, and the mass concentration of trisodium phosphate dodecahydrate is 6 g / L; the additive is sodium aluminate and glycerol, wherein the mass concentration of sodium aluminate is 0.5 g / L, and the mass concentration of glycerol is 15 g / L; the pH adjuster is sodium hydroxide, and the mass concentration is 0.5 g / L.

8. The micro-arc oxidation method for valve metal reinforced magnesium-based composite materials according to claim 1, characterized in that: In the constant current mode, the micro-arc oxidation current density is 5-12A / dm 2 , frequency is 500-1000Hz, duty cycle is 10%-50%, and micro-arc oxidation treatment time is 5-30min.

9. The micro-arc oxidation method for valve metal reinforced magnesium-based composite materials according to claim 8, characterized in that: In the constant current mode, the micro-arc oxidation current density is 5A / dm 2 , frequency is 500 Hz, duty cycle is 20%, and micro-arc oxidation treatment time is 15 min.

10. A corrosion-resistant micro-arc oxidation coating on the surface of a valve metal reinforced magnesium-based composite material, characterized in that: The corrosion-resistant micro-arc oxidation coating is obtained by the method according to any one of claims 1 to 9.

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