A magnesium alloy surface coloring treatment agent and a method for preparing the same

Abstract

The application discloses a magnesium alloy surface coloring treatment agent and a preparation method thereof, and belongs to the technical field of magnesium alloy surface treatment, wherein the coloring treatment agent comprises the following raw materials in parts by weight: zirconium citrate 30-50 parts, potassium titanium oxalate 20-30 parts, potassium ferrate 10-30 parts, citric acid 10-20 parts, oxalic acid 10-20 parts, nano sol 5-15 parts, disodium ethylenediaminetetraacetate 3-8 parts, antimony nitrate 2-20 parts, cobalt nitrate 1-10 parts, coloring salt 1-10 parts, composite corrosion inhibitor 1-5 parts, dispersing agent 1-5 parts, and water 1000 parts. The coating formed on the surface of the magnesium alloy by the coloring treatment agent prepared by the application has the advantage of controllable color, meets the color requirements of customers in different scenes, and meanwhile, the coloring treatment agent has excellent corrosion resistance, wear resistance, bonding force and other performances.

Description

Technical Field

[0001] This invention belongs to the field of magnesium alloy surface treatment technology, specifically relating to a magnesium alloy surface coloring agent and its preparation method. Background Technology

[0002] Magnesium alloys are the third largest metallic engineering material after steel and aluminum alloys. They have many excellent properties and extremely wide application prospects. They have irreplaceable comprehensive performance advantages and are hailed as the most ideal electronic product housing material and light vehicle steering system material in the 21st century. Using magnesium alloys to manufacture electronic device housings has many advantages, such as: lightweight, auxiliary heat dissipation, electromagnetic compatibility, long service life of magnesium alloy molds, and environmental friendliness.

[0003] The unique performance advantages of magnesium alloys have attracted widespread attention both domestically and internationally, and their application scope is constantly expanding to various fields. In particular, as magnesium alloys are increasingly used in automobiles and 3C electronics, the surface decoration properties of magnesium alloys are becoming an essential factor to consider.

[0004] Currently, the main surface coloring technologies for magnesium alloys on the market are chemical conversion + spraying, metal coating, anodizing secondary coloring, and micro-arc oxidation. Among them, chemical conversion + spraying coloring technology offers a rich variety of powder coating colors and is simple to operate. However, to improve the adhesion between the sprayed coating and the magnesium alloy substrate, the magnesium alloy substrate must first be pretreated to form a protective film through chemical conversion before spraying. The chemical conversion process generally uses solutions containing hexavalent chromium ions, which can be harmful to the environment and organisms. Metal coating coloring technology produces a uniform metal coating thickness, high hardness, and good wear and corrosion resistance. The coating color is also the natural color of the metal, and there will be no coating peeling or blistering. However, the preparation method is time-consuming and labor-intensive, and the stability of the chemical plating solution is poor. Furthermore, when plating corrosion-resistant metals, the plating solution usually contains cyanide, which pollutes the environment. The anodizing secondary coloring technology first creates micropores on the surface of magnesium alloy through anodizing, and then immerses the dye into the micropores for coloring. These surface micropores form corrosion cells, causing the magnesium alloy to be gradually corroded and the dye to be gradually replaced by corrosion products, resulting in poor coloring durability of this technology. Compared with the other three coloring technologies, the colored film layer formed by micro-arc oxidation coloring technology has greatly improved in terms of adhesion, wear resistance, and corrosion resistance. However, due to the limited variety of coloring salts on the market, the color diversity is poor. Moreover, current research on this technology is mainly focused on aluminum alloys, and research on the production of colored film layers for magnesium alloys is relatively scarce, making it difficult to maintain a stable and uniform coloring effect in industrialization. Summary of the Invention

[0005] To address the problems of poor adhesion, poor corrosion resistance, poor wear resistance, monotonous surface color, uneven color, and environmental damage in current magnesium alloy surface coloring processes, this invention provides a magnesium alloy surface coloring agent and its preparation method. Specifically, one objective of this invention is to provide a magnesium alloy surface coloring agent, and another objective is to provide a method for preparing the aforementioned coloring agent.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A magnesium alloy surface coloring agent, comprising the following raw materials in parts by weight:

[0008] Zirconium citrate 30-50 parts, potassium titanium oxalate 20-30 parts, potassium ferrate 10-30 parts, citric acid 10-20 parts, oxalic acid 10-20 parts, nano sol 5-15 parts, disodium ethylenediaminetetraacetate 3-8 parts, antimony nitrate 2-20 parts, cobalt nitrate 1-10 parts, coloring salt 1-10 parts, composite corrosion inhibitor 1-5 parts, dispersant 1-5 parts, water 1000 parts.

[0009] Furthermore, a magnesium alloy surface coloring agent comprises the following raw materials in parts by weight:

[0010] Zirconium citrate 45 parts, potassium titanium oxalate 25 parts, potassium ferrate 30 parts, citric acid 20 parts, oxalic acid 15 parts, nano sol 13 parts, disodium ethylenediaminetetraacetate 6 parts, antimony nitrate 18 parts, cobalt nitrate 10 parts, coloring salt 10 parts, composite corrosion inhibitor 5 parts, dispersant 2 parts, water 1000 parts.

[0011] Furthermore, the nanosol is formed by mixing aqueous nano-SiO2 and aqueous nano-TiO2 in a mass ratio of 1:1.

[0012] Furthermore, the particle size of the aqueous nano-SiO2 is 8-15 nm.

[0013] Furthermore, the particle size of the aqueous nano-TiO2 is 15-30 nm.

[0014] Furthermore, the coloring salt is one of cobalt bromide, copper sulfate, and copper nitrate.

[0015] Furthermore, the composite corrosion inhibitor is composed of polyaspartic acid and polyol phosphate in a mass ratio of 1:1.

[0016] Further, the dispersant is one of polyacrylic acid, sodium butylnaphthalene sulfonate, hydrolyzed polymaleic anhydride, or a mixture of any two of them in a mass ratio of 1:1.

[0017] Furthermore, a method for preparing a magnesium alloy surface coloring agent includes the following steps:

[0018] Step S1: Weigh each raw material according to the mass fraction, add potassium titanium oxalate and zirconium citrate to water, heat in a water bath to 40-60℃, stir at a constant temperature for 1.5-2.5h at a stirring rate of 1000r / min, then add dispersant and nano sol, and sonicate at a constant temperature for 0.5h-1h, then add citric acid, oxalic acid, potassium ferrate, antimony nitrate, cobalt nitrate, coloring salt, disodium ethylenediaminetetraacetate and composite corrosion inhibitor, and stir at a constant temperature for 1-2h to obtain a mixed solution;

[0019] Step S2: Add sodium malonate to the mixed solution to adjust the pH value to 5-7, stir at a constant temperature for 30 minutes, and then cool and let stand to obtain the magnesium alloy surface coloring agent.

[0020] The beneficial effects of this invention are:

[0021] This invention provides a magnesium alloy surface coloring agent, which is mainly composed of zirconium citrate, potassium titanium oxalate, potassium ferrate, citric acid, oxalic acid, nano sol, disodium ethylenediaminetetraacetate, antimony nitrate, cobalt nitrate, coloring salt, composite corrosion inhibitor, dispersant and water. The coloring agent forms a coating after curing on the magnesium alloy surface.

[0022] The coloring agent of this invention uses potassium titanium oxalate and zirconium citrate as the main film-forming substances. The addition of potassium titanium oxalate helps to improve the color and adhesion of the coating. The coloring agent uses disodium ethylenediaminetetraacetate as a complexing agent, which improves the corrosion resistance and wear resistance of the coating by complexing with rare metal ions such as antimony and cobalt ions. The addition of antimony nitrate, a rare metal antimony salt, significantly improves the thickness and stability of the coating because antimony ions in antimony nitrate can form active centers on the magnesium alloy surface, promoting the coating growth rate. The addition of composite sol in the coloring agent improves the wear resistance of the coating. The addition of composite corrosion inhibitor improves the corrosion resistance of the coating. By adjusting the type and content of coloring salts in the coloring agent, the color of the coating can be controlled to meet the color requirements of customers in different scenarios.

[0023] In summary, the coloring agent prepared by this invention has excellent corrosion resistance and wear resistance, and exhibits excellent adhesion to magnesium alloy surfaces. Finally, the coloring agent of this invention does not contain heavy metals such as chromium that pollute the environment, thus causing less environmental pollution and better meeting environmental protection requirements. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention discloses a magnesium alloy surface coloring agent and its preparation method. First, the relevant information of the raw materials involved in this invention is shown in Table 1 below:

[0026] Table 1. Raw Material Information

[0027]

[0028]

[0029] Example 1

[0030] A magnesium alloy surface coloring agent:

[0031] First, the magnesium alloy surface coloring agent comprises the following raw materials in parts by weight:

[0032] 30 parts zirconium citrate, 20 parts potassium titanium oxalate, 10 parts potassium ferrate, 10 parts citric acid, 10 parts oxalic acid, 5 parts nano sol, 3 parts disodium ethylenediaminetetraacetate, 2 parts antimony nitrate, 1 part cobalt nitrate, 1 part coloring salt, 1 part composite corrosion inhibitor, 1 part dispersant, and 1000 parts water.

[0033] The nanosol is composed of aqueous nano-SiO2 (particle size 8-10nm) and aqueous nano-TiO2 (particle size 15-20nm) mixed in a mass ratio of 1:1.

[0034] The coloring salt is cobalt bromide;

[0035] The composite corrosion inhibitor is composed of polyaspartic acid and polyol phosphate in a mass ratio of 1:1.

[0036] The dispersant is a mixture of polyacrylic acid and sodium butylnaphthalene sulfonate in a mass ratio of 1:1.

[0037] Then, the magnesium alloy surface coloring agent is prepared by the following steps:

[0038] Step S1: Weigh each raw material according to its mass percentage;

[0039] Step S2: Add water, potassium titanium oxalate and zirconium citrate to the reaction vessel in sequence. Heat the reaction vessel to 60°C in a water bath and stir at a constant temperature for 1.5 hours at a stirring rate of 1000 r / min.

[0040] Step S3: Continue to add dispersant and nano-sol to the reaction vessel in sequence, and disperse at a constant temperature using ultrasonication for 0.5h-1h;

[0041] Step S4: Continue to add citric acid, oxalic acid, potassium ferrate, antimony nitrate, cobalt nitrate, coloring salt, disodium ethylenediaminetetraacetate and composite corrosion inhibitor to the reaction vessel in sequence, and continue to stir at a constant temperature for 1 hour to obtain a mixed solution;

[0042] Step S5: Finally, add sodium malonate to the reaction vessel to adjust the pH of the mixed solution to 5, and continue stirring at a constant temperature for 30 minutes to obtain the coloring agent;

[0043] Step S6: Cool the coloring agent in the reaction vessel to room temperature, and then let it stand for 30 minutes to obtain the magnesium alloy surface coloring agent.

[0044] Example 2

[0045] A magnesium alloy surface coloring agent:

[0046] First, the magnesium alloy surface coloring agent comprises the following raw materials in parts by weight:

[0047] Zirconium citrate 45 parts, potassium titanium oxalate 25 parts, potassium ferrate 30 parts, citric acid 20 parts, oxalic acid 15 parts, nano sol 13 parts, disodium ethylenediaminetetraacetate 6 parts, antimony nitrate 18 parts, cobalt nitrate 10 parts, coloring salt 10 parts, composite corrosion inhibitor 5 parts, dispersant 2 parts, water 1000 parts.

[0048] The nanosol is composed of aqueous nano-SiO2 (particle size 10-12nm) and aqueous nano-TiO2 (particle size 20-25nm) mixed in a mass ratio of 1:1.

[0049] The coloring salt is copper sulfate;

[0050] The composite corrosion inhibitor is composed of polyaspartic acid and polyol phosphate in a mass ratio of 1:1.

[0051] The dispersant is sodium butylnaphthalene sulfonate.

[0052] Then, the magnesium alloy surface coloring agent is prepared by the following steps:

[0053] Step S1: Weigh each raw material according to its mass percentage;

[0054] Step S2: Add water, potassium titanium oxalate and zirconium citrate to the reaction vessel in sequence. Heat the reaction vessel to 50°C in a water bath and stir at a constant temperature for 2.5 hours at a stirring rate of 1000 r / min.

[0055] Step S3: Continue to add dispersant and nano-sol to the reaction vessel in sequence, and disperse at a constant temperature using ultrasonication for 1 hour;

[0056] Step S4: Continue to add citric acid, oxalic acid, potassium ferrate, antimony nitrate, cobalt nitrate, coloring salt, disodium ethylenediaminetetraacetate and composite corrosion inhibitor to the reaction vessel in sequence, and continue to stir at a constant temperature for 2 hours to obtain a mixed solution;

[0057] Step S5: Finally, add sodium malonate to the reaction vessel to adjust the pH of the mixed solution to 6.5, and continue stirring at a constant temperature for 30 minutes to obtain the coloring agent;

[0058] Step S6: Cool the coloring agent in the reaction vessel to room temperature, and then let it stand for 35 minutes to obtain the magnesium alloy surface coloring agent.

[0059] Example 3

[0060] A magnesium alloy surface coloring agent:

[0061] First, the magnesium alloy surface coloring agent comprises the following raw materials in parts by weight:

[0062] Zirconium citrate 50 parts, potassium titanium oxalate 30 parts, potassium ferrate 20 parts, citric acid 15 parts, oxalic acid 20 parts, nano sol 15 parts, disodium ethylenediaminetetraacetate 8 parts, antimony nitrate 20 parts, cobalt nitrate 5 parts, coloring salt 5 parts, composite corrosion inhibitor 2 parts, dispersant 5 parts, water 1000 parts.

[0063] The nanosol is composed of aqueous nano-SiO2 (particle size 12-15nm) and aqueous nano-TiO2 (particle size 25-30nm) mixed in a mass ratio of 1:1.

[0064] The coloring salt is copper nitrate;

[0065] The composite corrosion inhibitor is composed of polyaspartic acid and polyol phosphate in a mass ratio of 1:1.

[0066] The dispersant is hydrolyzed polymaleic anhydride.

[0067] Then, the magnesium alloy surface coloring agent is prepared by the following steps:

[0068] Step S1: Weigh each raw material according to its mass percentage;

[0069] Step S2: Add water, potassium titanium oxalate and zirconium citrate to the reaction vessel in sequence. Heat the reaction vessel to 40°C in a water bath and stir at a constant temperature for 2.5 hours at a stirring rate of 1000 r / min.

[0070] Step S3: Continue to add dispersant and nano-sol to the reaction vessel in sequence, and disperse at a constant temperature using ultrasonication for 1 hour;

[0071] Step S4: Continue to add citric acid, oxalic acid, potassium ferrate, antimony nitrate, cobalt nitrate, coloring salt, disodium ethylenediaminetetraacetate and composite corrosion inhibitor to the reaction vessel in sequence, and continue to stir at a constant temperature for 2 hours to obtain a mixed solution;

[0072] Step S5: Finally, add sodium malonate to the reaction vessel to adjust the pH of the mixed solution to 7, and continue stirring at a constant temperature for 30 minutes to obtain the coloring agent;

[0073] Step S6: Cool the coloring agent in the reaction vessel to room temperature, and then let it stand for 35 minutes to obtain the magnesium alloy surface coloring agent.

[0074] Comparative Example 1

[0075] Comparative Example 1 served as the control group for Example 2. The nano-sol in Example 2 was replaced with aqueous nano-SiO2 (particle size 10-12nm), i.e., aqueous nano-TiO2 was removed. The remaining raw materials and preparation methods remained unchanged from Example 2, and the magnesium alloy surface coloring agent was finally obtained.

[0076] Comparative Example 2

[0077] Comparative Example 2 is the control group of Example 2. The nano sol in Example 2 was replaced with water-based nano TiO2 (particle size 20-25nm), that is, water-based nano SiO2 was removed. The remaining raw materials and preparation methods remained unchanged from Example 2, and the magnesium alloy surface coloring agent was finally obtained.

[0078] Comparative Example 3

[0079] Comparative Example 3 served as the control group for Example 2. The composite corrosion inhibitor in Example 2 was replaced with polyaspartic acid, i.e., polyol phosphate was removed. The remaining raw materials and preparation methods remained unchanged from those in Example 2, and the final magnesium alloy surface coloring agent was obtained.

[0080] Comparative Example 4

[0081] Comparative Example 4 served as the control group for Example 2. The composite corrosion inhibitor in Example 2 was replaced with polyol phosphate, i.e., polyaspartic acid was removed. The remaining raw materials and preparation methods remained unchanged from Example 2, and the magnesium alloy surface coloring agent was finally obtained.

[0082] Comparative Example 5

[0083] Comparative Example 5 served as the control group for Example 2. Antimony nitrate was removed from Example 2, while the remaining raw materials and preparation methods remained unchanged from Example 2, ultimately yielding a magnesium alloy surface coloring agent.

[0084] Comparative Example 6

[0085] Comparative Example 6 served as the control group for Example 2. Step S5 in Example 2 was removed, i.e., the process of adjusting the pH value using sodium malonate was removed. The remaining raw materials and preparation methods remained unchanged from those in Example 2, and the magnesium alloy surface coloring agent was finally obtained.

[0086] Comparative Example 7

[0087] Comparative Example 7 served as the control group for Example 2. Potassium titanium oxalate was removed from Example 2, while the remaining raw materials and preparation methods remained unchanged from Example 2, ultimately yielding a magnesium alloy surface coloring agent.

[0088] Magnesium alloys from Examples 1-3 and Comparative Examples 1-7 were subjected to surface coloring treatment. After the coloring treatment, performance tests were performed. The coloring treatment process and performance test process are as follows, and the performance test results are shown in Table 2.

[0089] I. Coloring process of magnesium alloy surface coloring agents:

[0090] Magnesium alloy surface pretreatment: The surface of the magnesium alloy workpiece is polished smooth and uniform by passing it through 400#, 600#, 800#, 1000# and 1200# wet sandpaper in sequence. Then it is cleaned with pure water and ultrasonically cleaned in 10g / L sodium hydroxide solution at 50℃ for 5min to remove any grease that may be present on the surface of the magnesium alloy workpiece. It is then cleaned with pure water again and finally ultrasonically cleaned in acetone for 2min. After being dried with cold air, the pretreated magnesium alloy workpiece is obtained and ready for use.

[0091] The magnesium alloy surface coloring agent is heated to 60°C. The pretreated magnesium alloy workpiece is immersed in the magnesium alloy surface coloring agent and stirred at a constant temperature for 10 minutes at a stirring rate of 100 r / min. After the reaction is completed, the magnesium alloy workpiece treated with the coloring agent is taken out from the reaction vessel, washed with pure water, and then placed in a 60°C forced-air drying oven for 30 minutes to dry, thus obtaining the color-treated magnesium alloy workpiece.

[0092] II. Performance Testing:

[0093] Corrosion resistance: The coating surface is considered qualified if no rust appears after 240 hours of neutral salt spray test; otherwise, it is considered unqualified.

[0094] Abrasion resistance: Refer to GB / T1768-2006 "Determination of abrasion resistance of paints and varnishes - Rotary rubber grinding wheel method". Select CS-17 rubber grinding wheel, load 1Kg, 2000 cycles. If the coating is not worn through, it is qualified; otherwise, it is unqualified.

[0095] Coating hardness test: Refer to GB / T6739-2006 "Determination of Hardness of Paints and Varnishes by Pencil Method" standard;

[0096] Coating adhesion test: A scratch test is adopted. A hard steel scratching knife with a blade sharpened to a 30° acute angle is used to scratch two parallel lines 2mm apart on the surface of the test sample. Sufficient pressure is applied when scratching so that the scratching knife can break through the film layer and reach the substrate in one stroke. Adhesive tape is stuck to the scratched area. After peeling off the tape, it is observed whether the film layer is stuck to the tape surface. If the film layer is stuck, it is considered unqualified; otherwise, it is considered qualified.

[0097] Table 2 Performance Test Results

[0098]

[0099] Comparisons with Comparative Examples 1 and 2 and Example 2 show that the present invention utilizes a composite sol to significantly improve the wear resistance of the coating formed after the coloring agent is colored and cured on the surface of magnesium alloy.

[0100] Comparisons of Comparative Examples 3 and 4 with Example 2 show that the present invention utilizes a composite corrosion inhibitor to significantly improve the corrosion resistance of the coating formed after the coloring agent is colored and cured on the magnesium alloy surface, and that polyaspartic acid and polyol phosphate have a synergistic effect.

[0101] Comparison of Comparative Example 5 and Example 2 shows that the present invention utilizes antimony nitrate to significantly improve the thickness and stability of the coating formed after the coloring agent is cured on the magnesium alloy surface (stability affects the appearance of the coating). This is because antimony ions can form active centers on the magnesium alloy surface during coloring, which promotes the coating growth rate.

[0102] Comparison of Comparative Example 6 and Example 2 shows that the present invention utilizes sodium malonate to adjust the pH value, which significantly improves the color of the coating formed after the coloring agent is colored and cured on the magnesium alloy surface. This is because sodium malonate increases the diffusion ability of the coloring agent by stabilizing the pH value of the coloring agent.

[0103] Comparison of Comparative Example 7 and Example 2 shows that the present invention utilizes potassium titanium oxalate as the main film-forming agent, which significantly improves the color and adhesion of the coating formed after the coloring agent is colored and cured on the magnesium alloy surface.

[0104] It should be noted that, in this document, terms such as “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0105] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A magnesium alloy surface coloring treatment agent characterized by comprising: The following raw materials are included by weight parts: Zirconium citrate 30-50 parts, potassium titanium oxalate 20-30 parts, potassium ferrate 10-30 parts, citric acid 10-20 parts, oxalic acid 10-20 parts, nano sol 5-15 parts, disodium ethylenediaminetetraacetate 3-8 parts, antimony nitrate 2-20 parts, cobalt nitrate 1-10 parts, coloring salt 1-10 parts, composite corrosion inhibitor 1-5 parts, dispersant 1-5 parts, and water 1000 parts; The nano sol is formed by mixing water-based nano SiO2 and water-based nano TiO2 at a mass ratio of 1:1; The composite corrosion inhibitor is formed by mixing polyaspartic acid and polyol phosphate at a mass ratio of 1:1; Malonic acid is added to adjust the pH to 5-7.

2. The magnesium alloy surface coloring treatment agent according to claim 1, characterized by The following raw materials are included by mass parts: Zirconium citrate 45 parts, potassium titanium oxalate 25 parts, potassium ferrate 30 parts, citric acid 20 parts, oxalic acid 15 parts, nano sol 13 parts, disodium ethylenediaminetetraacetate 6 parts, antimony nitrate 18 parts, cobalt nitrate 10 parts, coloring salt 10 parts, composite corrosion inhibitor 5 parts, dispersant 2 parts, and water 1000 parts.

3. The magnesium alloy surface coloring treatment agent according to claim 1, characterized by The particle size of the water-based nano SiO2 is 8-15 nm.

4. The magnesium alloy surface coloring treatment agent according to claim 1, characterized by The particle size of the water-based nano TiO2 is 15-30 nm.

5. The surface coloring treatment agent for a magnesium alloy according to any one of claims 1 to 2, characterized by The coloring salt is one of cobalt bromide, copper sulfate, and copper nitrate.

6. The surface coloring treatment agent for a magnesium alloy according to any one of claims 1 to 2, characterized by The dispersant is one of polyacrylic acid, sodium butyl naphthalene sulfonate, and hydrolyzed polymaleic anhydride, or a mixture of any two thereof at a mass ratio of 1:

1.

7. The method of claim 1, wherein the magnesium alloy surface coloring treatment agent is prepared by adding 0.1 to 5 parts by weight of the coloring agent to 100 parts by weight of the magnesium alloy surface coloring treatment agent. The following steps are included: Step S1, the raw materials are weighed by mass parts, potassium titanium oxalate and zirconium citrate are added to water, heated to 40-60°C in a water bath, and stirred at a constant temperature for 1.5-2.5 h at a stirring rate of 1000 r / min, then the dispersant and nano sol are added, ultrasonic dispersion is performed at a constant temperature for 0.5-1 h, then citric acid, oxalic acid, potassium ferrate, antimony nitrate, cobalt nitrate, coloring salt, disodium ethylenediaminetetraacetate, and composite corrosion inhibitor are added, and stirred at a constant temperature for 1-2 h to obtain a mixed solution; Step S2, sodium malonate is added to the mixed solution to adjust the pH to 5-7, stirred at a constant temperature for 30 min, and then cooled and placed to obtain a magnesium alloy surface coloring treatment agent.

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