阅读说明：本技术 一种水溶性钽溶液的制备方法 (Preparation method of water-soluble tantalum solution ) 是由 王庆琨 杨机妹 于 2020-12-02 设计创作，主要内容包括：本发明提供了一种水溶性钽溶液的制备方法,其步骤包括：以五氯化钽的正丁醇溶液为起始原料,通过加入氢氧化钠水溶液使五氯化钽水解生成氢氧化钽固体,氢氧化钽固体加入到体积浓度20％的醋酸溶液中,再加入草酸后加热,滴加30％双氧水溶液至溶液透明,最后浓缩至指定浓度。本发明的目的在于提供一种水溶性钽溶液的制备方法,该溶液与氯铱酸混合后得到的涂液性能好,制备安全性好,适用于工业化生产,降低了生产成本。(The invention provides a preparation method of a water-soluble tantalum solution, which comprises the following steps: taking an n-butanol solution of tantalum pentachloride as a starting material, adding an aqueous solution of sodium hydroxide to hydrolyze the tantalum pentachloride to generate a solid tantalum hydroxide, adding the solid tantalum hydroxide into an acetic acid solution with the volume concentration of 20%, adding oxalic acid, heating, dropwise adding a 30% hydrogen peroxide solution until the solution is transparent, and finally concentrating to the specified concentration. The invention aims to provide a preparation method of a water-soluble tantalum solution, which is good in performance and preparation safety of a coating liquid obtained by mixing the solution with chloroiridic acid, is suitable for industrial production and reduces the production cost.)

1. The preparation method of the water-soluble tantalum solution is characterized by comprising the following steps:

step 1, taking an n-butanol solution of tantalum pentachloride as a starting material, and adding an aqueous solution of sodium hydroxide to hydrolyze the tantalum pentachloride to generate a tantalum hydroxide solid;

step 2, adding the obtained tantalum hydroxide solid into an acetic acid solution with the volume concentration of 20%, adding oxalic acid, heating, and dropwise adding a 30% hydrogen peroxide solution until the solution is transparent;

and 3, concentrating the obtained transparent solution to obtain a water-soluble tantalum solution with a specified concentration.

2. The method as claimed in claim 1, wherein the n-butanol solution of tantalum pentachloride in step 1 contains 200g/L of tantalum.

3. The method for preparing a water-soluble tantalum solution according to claim 1, wherein the pH value of the aqueous sodium hydroxide solution in step 1 is 12-14, and the volume ratio of the aqueous sodium hydroxide solution to the tantalum pentachloride n-butanol solution is (2-1): 1.

4. The method for preparing a water-soluble tantalum solution according to claim 1, wherein the reaction temperature in step 1 is room temperature and the reaction time is 15-30 minutes.

5. The method for preparing a water-soluble tantalum solution according to claim 1, wherein the tantalum hydroxide (g) in step 2: 20% acetic acid solution (mL): oxalic acid (g) ═ 1: (20-25): (4-8).

6. The method for preparing a water-soluble tantalum solution according to claim 1 or 5, wherein the ratio of oxalic acid (g) in step 2: 30% hydrogen peroxide (mL) ═ 1 (10-30).

7. The method as claimed in claim 1, wherein the heating temperature in step 2 is 100 ℃ and 110 ℃ for 1-1.5 hours.

Technical Field

The invention belongs to the technical field of anode coatings, and particularly relates to a preparation method of a water-soluble tantalum solution.

Background

The development of the chlor-alkali industry has increased the requirements on anodes with dimensional stability, the titanium-based ruthenium-containing coatings being strongly acidic due to RuO₂RuO formation under oxygen₄And constantly dissolve, resulting in the loss of active substance. IrO₂Oxygen evolution over potential ratio RuO₂High, working life in strong acid is much longer than the latter. Taken together, IrO₂Is an ideal active component of the oxygen evolution electrode coating. Ta₂O₅Is a substance with strong chemical stability. Studies have shown that it protects the active substance as an inert component of the coating (appl. eletrochem.,1994(24): 1262-1266).

The tantalum iridium coating is generally prepared by dissolving tantalum pentachloride or tantalum ethoxide in n-butyl alcohol and preparing the solution with chloroiridic acid according to different proportions, such as the high-efficiency and high-activity iridium tantalum coating liquid and the iridium tantalum coating formed by the same in the prior patent (application number 201810531750. X). However, since tantalum pentachloride or tantalum ethoxide is easily hydrolyzed, in order to prevent hydrolysis from affecting the product quality during the coating process, the workshop needs to strictly control humidity, which greatly increases the process cost.

The reported methods for synthesizing water-soluble tantalum salts mainly include: prior patent "Process for preparing Water-soluble tantalum carboxylate Complex" (application No. 201510739819.4): mixing Ta₂O₅Dissolving in HF acid, and adding oxalate solution into the solution for reaction; then adding ammonia water into the solution to obtain a tantalum hydroxide precipitate; after aging, alkali washing, water washing and filtering, the tantalum hydroxide precipitate is dissolved in hydroxycarboxylic acid to form a stable tantalum carboxylate complex. The method uses the HF acid with strong corrosivity, has great harm to human bodies and equipment, can corrode coating materials, limits the expansion of production scale, takes longer time for dissolving the tantalum hydroxide in the hydroxycarboxylic acid, and is difficult to treat fluorine-containing wastewater generated in the production process.

In another method, the preparation method and application of stable water-soluble niobium and tantalum precursor (application No. 200410014962.9) uses tantalum or niobium pentoxide as raw material, mixes and grinds niobium pentoxide or tantalum pentoxide and potassium hydroxide or sodium hydroxide uniformly according to molar ratio, and burns and reacts for 2-4 hours at 400-550 ℃ to obtain the melt of potassium (sodium) niobate or potassium (sodium) tantalate; dissolving the melt in deionized water, filtering to obtain clear solution with strong acidity (pH)<2) Completely precipitating niobium or tantalum in the solution in the form of niobic acid or tantalic acid; adding appropriate amount of citric acid aqueous solution or adding appropriate amount of oxalic acid aqueous solution into the niobic acid precipitate to obtain water-soluble niobium precursor or tantalum oxalate aqueous solution. The method has the advantages that the production cost is increased when the reaction is carried out at high temperature, the potassium (sodium) ions exceed the standard due to the use of the raw material containing the potassium (sodium) ions, the quality of the coating is influenced, and in addition, oxalic acid or citric acid has certain reductionWhen the coating solution is prepared together with the chloroiridium (IV) acid solution, the Iridium (IV) is reduced into iridium (III), and the final coating contains Ir₂O₃Seriously affecting the performance of the coating.

Disclosure of Invention

The embodiment of the invention aims to provide a preparation method of a water-soluble tantalum solution, and the obtained coating has good performance and good preparation safety, is suitable for industrial production and reduces the production cost.

The technical scheme adopted by the invention is as follows: a preparation method of a water-soluble tantalum solution comprises the following steps:

step 1, taking an n-butanol solution of tantalum pentachloride as a starting material, and adding an aqueous solution of sodium hydroxide to hydrolyze the tantalum pentachloride to generate a tantalum hydroxide solid;

step 2, adding the obtained tantalum hydroxide solid into an acetic acid solution with the volume concentration of 20%, adding oxalic acid, heating, and dropwise adding a 30% hydrogen peroxide solution until the solution is transparent;

and 3, concentrating the obtained transparent solution to obtain a water-soluble tantalum solution with a specified concentration.

Further, the tantalum content in the n-butanol solution of tantalum pentachloride in the step 1 is 200 g/L.

Further, in the step 1, the pH value of the aqueous solution of sodium hydroxide is 12-14, and the volume ratio of the aqueous solution of sodium hydroxide to the solution of tantalum pentachloride in n-butyl alcohol is (2-1): 1.

Further, in the step 1, the reaction temperature in the step 1 is room temperature, and the reaction time is 15-30 minutes.

Further, the tantalum hydroxide (g) in step 2: 20% acetic acid solution (mL): oxalic acid (g) ═ 1: (20-25): (4-8).

Further, oxalic acid (g) in the step 2: 30% hydrogen peroxide (mL) ═ 1 (10-30).

Further, the reaction temperature in step 2 is 100-110 ℃ and the time is 1-1.5 hours.

The invention has the beneficial effects that:

(1) the water-soluble tantalum solution prepared by the method provided by the invention can be kept stable for a long time after being prepared into a masking liquid with a chloroiridic acid solution.

(2) The invention can be mixed with the chloroiridic acid coating liquid under the condition of a common workshop, and a uniform gray-black coating without hydrolysis traces can be obtained by 100 percent.

(3) Under the same process conditions, the coating prepared by the invention is coated on H₂SO₄The enhanced lifetime of the electrolysis in solution is longer than that of the coating prepared by the prior method in H₂SO₄The strengthening life of electrolysis in the solution is long.

(4) The method has good preparation safety, has no requirement on workshop environment, reduces the production cost and is suitable for industrial mass production.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow chart of the method of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The preparation method of the water-soluble tantalum solution is shown in a flow chart of figure 1 and specifically comprises the following steps:

taking a tantalum pentachloride n-butyl alcohol solution with the tantalum content of 200g/L as a starting material, adding a sodium hydroxide aqueous solution to hydrolyze the tantalum pentachloride to generate a tantalum hydroxide solid, adding the tantalum hydroxide solid into an acetic acid solution with the volume concentration of 20%, adding oxalic acid, heating, dropwise adding a 30% hydrogen peroxide solution until the solution is transparent, and concentrating to a specified concentration.

Wherein the pH value of the sodium hydroxide aqueous solution is 12-14, the volume ratio of the sodium hydroxide aqueous solution to the tantalum pentachloride n-butyl alcohol solution is (2-1):1, the reaction temperature is room temperature, and the reaction time is 15-30 minutes; tantalum hydroxide (g): 20% acetic acid solution (mL): oxalic acid (g) ═ 1: (20-25): (4-8); oxalic acid (g): 30 percent hydrogen peroxide (mL) is 1 (10-30), the reaction temperature is 100-.

Due to Ta⁵⁺Is high, therefore, Ta (OH) is dissolved with an acid₅Is difficult to dissolve, and needs to add excessive strong acid such as HCl and HNO₃、H₂SO₄And HF and the like. But if the strong acid is mixed with Ta (OH)₅The strong acid can severely corrode coating materials when the coating solution is used for preparation, HCl and HF have strong volatility, a large amount of volatile matters can affect the safety of people and equipment, and TaCl is generated along with the volatilization of the acid₅Or TaF₅Hydrolysis begins again, so if only strong acid is added, the plant requirements of the process will still be high.

In addition, although oxalic acid is generally easily coordinated to metal ions to give a stable soluble metal oxalate compound, it is generally compatible with Ta (OH) in the present method₅Ta of⁵⁺When the coordination is carried out, a reversible chemical reaction as shown in the following formula can easily occur:thus, Ta (OH)₅It is extremely difficult to obtain a stable soluble oxalic acid metal compound by the reaction with oxalic acid, so that a large amount of oxalic acid must be added to smoothly proceed the reaction, and the reaction is ensured to proceed toward the formation of oxalic acid complex under severe conditions such as melting, and Ta⁵⁺The oxalic acid complex is extremely easy to hydrolyze, so that the oxalic acid complex is difficult to stably exist in an aqueous solution, and the added large amount of oxalic acid causes the solution to have reducibility, so that the oxalic acid complex is not suitable for being mixed with chloroiridic acid for preparing a coating solution, and the use of the oxalic acid alone is not feasible.

In the present invention, Ta⁵⁺The structure of the product is similar to that of the product in the presence of hydrogen peroxide₂O₂)]³⁺The transition product of (1) has reduced charge to facilitate acidic dissolution, and simultaneously cooperates with the coordination capacity of oxalic acid to enable the reaction to proceed towards the reaction which is favorable for generating the oxalic acid complex, in addition, the existence of acetic acid is favorable for increasing the acidity of a reaction system, inhibiting the hydrolysis of tantalum oxalate, promoting the reaction to proceed further towards the direction of generating the tantalum oxalate, and increasing the stability of the solution, the addition of hydrogen peroxide can also react with redundant oxalic acid to generate carbon dioxide and water, the oxidability of the solution is improved, the generation of + 3-valent iridium is inhibited when the solution is prepared with chloroiridic acid, so that the tantalum oxalate and chloroiridic acid can be prepared into stable coating solution, in addition, the hydrogen peroxide and oxalic acid are volatilized and removed in the high-temperature sintering process, and Ta-removed₂O₅And IrO₂And substances that affect the quality of the coating.

Example 1

In a common workshop, taking an n-butanol solution of tantalum pentachloride with the tantalum content of 200g/L as a starting material, and adding an aqueous solution of sodium hydroxide with the pH value of 12 to hydrolyze the tantalum pentachloride to generate a solid tantalum hydroxide, wherein the volume ratio of the aqueous solution of sodium hydroxide to the n-butanol solution of tantalum pentachloride is 1:1, the reaction temperature is room temperature, and the reaction time is 15 minutes; then adding the tantalum solid into an acetic acid solution with the volume concentration of 20%, adding oxalic acid, heating, and dropwise adding a 30% hydrogen peroxide solution until the solution is transparent, wherein the weight ratio of tantalum hydroxide (g): 20% acetic acid solution (mL): oxalic acid (g) ═ 1: 20: 4; oxalic acid (g): and (3) preparing a coating liquid with the tantalum content of 10% by using 30% hydrogen peroxide (mL) at a ratio of 1:10, reacting at 100 ℃ for 1 hour, concentrating to obtain a water-soluble tantalum solution with the tantalum content of 10%, and finally preparing the water-soluble tantalum solution and a chloroiridic acid solution.

Example 2

In a common workshop, taking an n-butanol solution of tantalum pentachloride with the tantalum content of 200g/L as a starting material, and adding an aqueous solution of sodium hydroxide with the pH value of 14 to hydrolyze the tantalum pentachloride to generate a solid tantalum hydroxide, wherein the volume ratio of the aqueous solution of sodium hydroxide to the n-butanol solution of tantalum pentachloride is 2:1, the reaction temperature is room temperature, and the reaction time is 30 minutes; then adding the tantalum solid into an acetic acid solution with the volume concentration of 20%, adding oxalic acid, heating, and dropwise adding a 30% hydrogen peroxide solution until the solution is transparent, wherein the weight ratio of tantalum hydroxide (g): 20% acetic acid solution (mL): oxalic acid (g) ═ 1: 25: 8; oxalic acid (g): and (3) concentrating 30% hydrogen peroxide (mL) at a reaction temperature of 110 ℃ for 1.5 hours to obtain a water-soluble tantalum solution with the tantalum content of 10%, and finally preparing the water-soluble tantalum solution with the chloroiridic acid solution into a coating liquid with the tantalum content of 10%.

Example 3

In a common workshop, taking an n-butanol solution of tantalum pentachloride with the tantalum content of 200g/L as a starting material, and adding an aqueous solution of sodium hydroxide with the pH value of 13 to hydrolyze the tantalum pentachloride to generate a solid tantalum hydroxide, wherein the volume ratio of the aqueous solution of sodium hydroxide to the n-butanol solution of tantalum pentachloride is 1.5:1, the reaction temperature is room temperature, and the reaction time is 25 minutes; then adding the tantalum solid into an acetic acid solution with the volume concentration of 20%, adding oxalic acid, heating, and dropwise adding a 30% hydrogen peroxide solution until the solution is transparent, wherein the weight ratio of tantalum hydroxide (g): 20% acetic acid solution (mL): oxalic acid (g) ═ 1: 23: 6; oxalic acid (g): and (3) preparing 30% hydrogen peroxide (mL) into 1:20, reacting at 105 ℃ for 1.2 hours, concentrating to obtain a water-soluble tantalum solution with the tantalum content of 10%, and finally preparing the water-soluble tantalum solution with the chloroiridic acid solution into a coating liquid with the tantalum content of 30%.

Example 4

In a common workshop, taking an n-butanol solution of tantalum pentachloride with the tantalum content of 200g/L as a starting material, and adding an aqueous solution of sodium hydroxide with the pH value of 13 to hydrolyze the tantalum pentachloride to generate a solid tantalum hydroxide, wherein the volume ratio of the aqueous solution of sodium hydroxide to the n-butanol solution of tantalum pentachloride is 2:1, the reaction temperature is room temperature, and the reaction time is 28 minutes; then adding the tantalum solid into an acetic acid solution with the volume concentration of 20%, adding oxalic acid, heating, and dropwise adding a 30% hydrogen peroxide solution until the solution is transparent, wherein the weight ratio of tantalum hydroxide (g): 20% acetic acid solution (mL): oxalic acid (g) ═ 1: 21: 5; oxalic acid (g): 30% hydrogen peroxide (mL) is 1:18, the reaction temperature is 108 ℃, the reaction time is 1 hour, a water-soluble tantalum solution with the tantalum content of 10% is obtained after concentration, and finally the water-soluble tantalum solution and a chloroiridic acid solution are prepared into a coating liquid with the tantalum content of 40%.

Example 5

In a common workshop, taking an n-butanol solution of tantalum pentachloride with the tantalum content of 200g/L as a starting material, and adding an aqueous solution of sodium hydroxide with the pH value of 14 to hydrolyze the tantalum pentachloride to generate a solid tantalum hydroxide, wherein the volume ratio of the aqueous solution of sodium hydroxide to the n-butanol solution of tantalum pentachloride is 1.8:1, the reaction temperature is room temperature, and the time is 30 minutes; then adding the tantalum solid into an acetic acid solution with the volume concentration of 20%, adding oxalic acid, heating, and dropwise adding a 30% hydrogen peroxide solution until the solution is transparent, wherein the weight ratio of tantalum hydroxide (g): 20% acetic acid solution (mL): oxalic acid (g) ═ 1: 24: 7; oxalic acid (g): 30% hydrogen peroxide (mL) is 1:26, the reaction temperature is 104 ℃, the reaction time is 1.2 hours, a water-soluble tantalum solution with the tantalum content of 10% is obtained after concentration, and finally the water-soluble tantalum solution and a chloroiridic acid solution are prepared into a coating liquid with the tantalum content of 50%.

Comparative example 1

In a common workshop, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with the tantalum content of 10%, wherein the tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 4:4: 1.

Comparative example 2

In a common workshop, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with the tantalum content of 20%, wherein the tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 4:3: 1.

Comparative example 3

In a common workshop, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with the tantalum content of 30%, wherein the tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 5:4: 1.

Comparative example 4

In a common workshop, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with the tantalum content of 40%, wherein the tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 5:3: 1.

Comparative example 5

In a common workshop, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with the tantalum content of 50%, wherein the weight ratio of tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 6:3: 1.

Comparative example 6

In a standard workshop with humidity control, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with the tantalum content of 10%, wherein the weight ratio of the tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 4:4: 1.

Comparative example 7

In a standard workshop with humidity control, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with the tantalum content of 20%, wherein the weight ratio of the tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 4:3: 1.

Comparative example 8

In a standard workshop with humidity control, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with a tantalum content of 30%, wherein the weight ratio of the tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 5:4: 1.

Comparative example 9

In a standard workshop with humidity control, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with a tantalum content of 40%, wherein the weight ratio of the tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 5:3: 1.

Comparative example 10

In a standard workshop with humidity control, mixing an n-butyl alcohol solution of tantalum pentachloride and an aqueous solution of chloroiridic acid to prepare a coating liquid with the tantalum content of 50%, wherein the weight ratio of the tantalum pentachloride: n-butanol: the part ratio of the chloroiridic acid is 6:3: 1.

Experimental example 1:

examples 1-5 water-soluble tantalum solutions having a tantalum content of 10% were prepared using the methods described herein and formulated with chloroiridic acid solutions to form coating solutions having a tantalum content of 10% to 50%, and the stability was observed on days 1, 3, 7, and 15, respectively, and the results are shown in table 1.

TABLE 1 stability of tantalum iridium solutions at various contents

	1 day	3 days	7 days	15 days
					Example 1	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free
Example 2	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free
					Example 3	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free
Example 4	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free
					Example 5	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free	Transparent and precipitate-free

As can be seen from Table 1, the coating solutions containing 10-50% of tantalum prepared in examples 1-5 according to the preparation method of the present application were stable, transparent and free of precipitation within 15 days.

Experimental example 2

Under the condition of a common workshop, the water-soluble tantalum solution with the tantalum content of 10% is prepared by the method in the examples 1 to 5, and the water-soluble tantalum solution and the chloroiridic acid solution are prepared into a coating liquid with the tantalum content of 10% -50%; comparative examples 1-5 n-butanol tantalum pentachloride/chloroiridate masking liquids having a tantalum content of 10% to 50% were prepared using the prior art. The surface condition of the coatings of examples 1 to 5 and comparative examples 1 to 5 were observed, respectively, and the results are shown in Table 2.

TABLE 2 common workshop TaIr coating surface conditions

As can be seen from Table 1, comparing the coating conditions of examples 1-5 and comparative examples 1-5, it can be seen that examples 1-5 using the preparation method described herein all gave 100% uniform coating of grayish black without traces of hydrolysis, whereas comparative examples 1-5 gave up to 60% yield and the yield of the coating became lower with increasing tantalum content, much less as in examples 1-5 herein.

Experimental example 3

Respectively preparing coating liquids with the tantalum content of 10-50% prepared by the method in the application in the examples 1-5 under the condition of a common workshop and coating liquids with the tantalum content of 10-50% prepared by the prior art in the standard workshop with the humidity controlled in the comparative examples 6-10At 50% H₂SO₄At a concentration of 5A/cm in the solution²The electrolysis was carried out, and the life of the electrolyte was measured and measured to 250 hours, and the results are shown in Table 3.

TABLE 3 enhanced life

	Enhanced lifetime (hours)
		Example 1	>250
Example 2	>250
		Example 3	>250
Example 3	>250
		Example 5	>250
Comparative example 6	214
		Comparative example 7	220
Comparative example 8	217
		Comparative example 9	231
Comparative example 10	235

As can be seen from Table 3, the strengthening lives of the coating solutions of examples 1 to 5 were all 250 hours or more, whereas those of comparative examples 6 to 10 were 235 hours at the maximum, which were much shorter than those of examples 1 to 5.

The experimental examples show that the coating liquid prepared by the method provided by the invention has good stability and low requirement on workshop environment, and is superior to the coating liquid prepared by the prior art in terms of coating uniformity and electrolytic strengthening service life.

All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.