A hydrophobic self-healing polyaniline / cerium oxide composite coating and a preparation method thereof

Abstract

The application discloses a preparation method of a hydrophobic self-repairing polyaniline / cerium oxide composite coating, and comprises the following steps: S1, pretreating a metal substrate; S2, configuring an electrolyte, wherein the electrolyte contains aniline with a concentration of 0.1-0.3 mol / L, oxalic acid with a concentration of 0.02-0.05 mol / L, sulfuric acid with a concentration of 0.05-0.1 mol / L, cerium nitrate with a concentration of 0.1-0.15 mol / L and ammonium acetate with a concentration of 0.05-0.1 mol / L; and S3, electrochemically co-depositing the polyaniline / cerium oxide composite coating on the surface of the metal substrate by adopting a constant potential method. The polyaniline / cerium oxide composite coating prepared by the application has good hydrophobicity and self-repairing performance, and can be applied to corrosion protection of various metal materials. Meanwhile, the preparation process of the application is simple, has low energy consumption, does not need precious equipment, can be mass-produced, and has a wide industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of functional materials, and particularly relates to a hydrophobic self-repairing polyaniline / cerium oxide composite coating and a preparation method thereof. BACKGROUND

[0002] The polyaniline coating not only has good mechanical isolation effect, but also has certain catalytic passivation effect, and is widely applied in the field of corrosion protection of metal materials.

[0003] Compared with other preparation methods, the electrochemical polymerization method of polyaniline has the advantages of simple operation, simultaneous polymerization and doping, and the like, and the oxidation state and thickness of the polyaniline film can be controlled by changing the polymerization potential and electric quantity, and the obtained product does not need further separation.

[0004] However, during actual service, the polyaniline coating is exposed to corrosive media for a long time and is subjected to mechanical damage from the outside, and its protection performance gradually weakens with the prolongation of service time, which restricts its large-scale practical application. Therefore, it is urgent to use effective measures to prolong the service effect and life of the polyaniline coating. SUMMARY

[0005] An object of the application is to provide a preparation method of a hydrophobic self-repairing polyaniline / cerium oxide composite coating, and the prepared polyaniline / cerium oxide composite coating has good hydrophobicity and self-repairing performance, and can be applied in corrosion protection of various metal materials.

[0006] In order to achieve the above object, the application provides a preparation method of a hydrophobic self-repairing polyaniline / cerium oxide composite coating, comprising the following steps:

[0007] S1: performing pretreatment on a metal substrate;

[0008] S2: configuring an electrolyte, wherein the electrolyte contains aniline with a concentration of 0.1-0.3 mol / L, oxalic acid with a concentration of 0.02-0.05 mol / L, sulfuric acid with a concentration of 0.05-0.1 mol / L, cerium nitrate with a concentration of 0.1-0.15 mol / L, and ammonium acetate with a concentration of 0.05-0.1 mol / L, and the solvent is pure water;

[0009] S3: preparing a polyaniline / cerium oxide composite coating on the surface of the metal substrate by electrochemical co-deposition through a constant potential method.

[0010] Compared with the prior art, the hydrophobic self-repairing polyaniline / cerium oxide composite coating can be directly prepared on the surface of a metal substrate by electrochemical co-deposition through a constant potential method, on the one hand, a uniform rough micro-nano surface of the composite coating is constructed by in-situ doping of the cerium oxide nanoparticles through electrochemical co-deposition, thereby being beneficial to improving the hydrophobicity of the composite coating; on the other hand, the in-situ co-deposited doped cerium oxide nanoparticles exhibit good intrinsic self-repairing performance due to the mixed oxidation state on the surface of the cerium oxide nanoparticles, and can passivate the metal substrate material when the composite coating is damaged by the outside world, and finally realize efficient and long-acting protection for various metal materials. 3+ / Ce 4+ The method has simple preparation process, low energy consumption, and does not need precious equipment, and can be mass-produced, and has wide industrial application prospect.

[0011] Preferably, in step S3, the constant potential is 1.2-1.5 V.

[0012] Preferably, in step S3, the electrodeposition time is 10-15 minutes.

[0013] Preferably, in step S3, the electrodeposition temperature is 30-50 DEG C.

[0014] Preferably, in step S3, the working electrode is a pretreated metal substrate, the auxiliary electrode is a large-area platinum sheet, and the reference electrode is a saturated calomel electrode.

[0015] Preferably, in step S1, the pretreatment includes polishing with a metallographic sandpaper, polishing, oil removal, deionized water cleaning and cold air drying.

[0016] Preferably, the electrolyte contains aniline with a concentration of 0.3 mol / L, oxalic acid with a concentration of 0.05 mol / L, sulfuric acid with a concentration of 0.1 mol / L, cerium nitrate with a concentration of 0.1 mol / L and ammonium acetate with a concentration of 0.05 mol / L.

[0017] The application further provides a hydrophobic self-repairing polyaniline / cerium oxide composite coating prepared by the above preparation method, and the composite coating has good hydrophobicity and self-repairing performance, and can provide long-acting protection for various metal materials and prolong the service life thereof.

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

[0019] On the one hand, a uniform rough micro-nano surface of the composite coating is constructed by in-situ doping of the cerium oxide nanoparticles through electrochemical co-deposition, thereby being beneficial to improving the hydrophobicity of the composite coating; on the other hand, the in-situ co-deposited doped cerium oxide nanoparticles exhibit good intrinsic self-repairing performance due to the mixed oxidation state on the surface of the cerium oxide nanoparticles, and can passivate the metal substrate material when the composite coating is damaged by the outside world, and finally realize efficient and long-acting protection for various metal materials. 3+ / Ce 4+The mixed oxidation state exhibits good intrinsic self-repairing performance, can passivate the metal base material when the composite coating is damaged by the outside world, and ultimately realizes efficient and long-acting protection of various metal materials. Tests show that the polyaniline / cerium oxide composite coating has significantly improved protection efficiency of metal materials compared with existing polyaniline coatings, and has obvious advantages in long-acting protection performance and self-repairing performance. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Morphology diagram of the polyaniline / cerium oxide composite coating prepared on the surface of the aluminum alloy of Example 1

[0021] Figure 2 Contact angle diagram of the polyaniline / cerium oxide composite coating prepared on the surface of the aluminum alloy of Example 1

[0022] Figure 3 Contact angle diagram of the polyaniline coating prepared on the surface of the aluminum alloy of Example 1

[0023] Figure 4 Electrochemical impedance test result curve diagram of the untreated aluminum alloy of Comparative Example 5 in a 3.5% NaCl solution corrosion medium

[0024] Figure 5 Electrochemical impedance test result curve diagram of the polyaniline / cerium oxide composite coating prepared on the surface of the aluminum alloy of Example 2 after being immersed in a 3.5% NaCl solution corrosion medium for 0.5 hours

[0025] Figure 6 Electrochemical impedance test result curve diagram of the polyaniline coating prepared on the surface of the aluminum alloy of Comparative Example 2 after being immersed in a 3.5% NaCl solution corrosion medium for 0.5 hours

[0026] Figure 7 Electrochemical impedance test result curve diagram of the polyaniline / cerium oxide composite coating prepared on the surface of the aluminum alloy of Example 3 after being immersed in a 3.5% NaCl solution corrosion medium for 240 hours

[0027] Figure 8 Electrochemical impedance test result curve diagram of the polyaniline coating prepared on the surface of the aluminum alloy of Comparative Example 3 after being immersed in a 3.5% NaCl solution corrosion medium for 240 hours

[0028] Figure 9 Electrochemical impedance test result curve diagram of the polyaniline / cerium oxide composite coating on the carbon steel base of Example 4 after being scratched and immersed in a 3.5% NaCl solution corrosion medium for 0.5 hours

[0029] Figure 10The electrochemical impedance test result curve of the carbon steel substrate polyaniline / cerium oxide composite coating of Example 4 after scratching and immersed in 3.5% NaCl solution corrosion medium for 12 hours;

[0030] Figure 11 The electrochemical impedance test result curve of the carbon steel substrate polyaniline / cerium oxide composite coating of Example 4 after scratching and immersed in 3.5% NaCl solution corrosion medium for 12 hours;

[0031] Figure 12 The electrochemical impedance test result curve of the carbon steel substrate polyaniline / cerium oxide composite coating of Example 4 after scratching and immersed in 3.5% NaCl solution corrosion medium for 12 hours. DETAILED DESCRIPTION

[0032] The application will be further described with reference to the following specific examples. It should be understood that the application is not limited to these examples, and any form of variation or change based on the application will fall within the scope of the application.

[0033] Example 1:

[0034] The polyaniline / cerium oxide composite coating was prepared according to the following steps:

[0035] The aluminum alloy was pretreated, including polishing with metallographic sandpaper, polishing to mirror surface, degreasing, deionized water cleaning and cold air drying. Then the polyaniline / cerium oxide composite coating was electrochemically co-deposited on the surface of the pretreated aluminum alloy by constant potential method, the electrolyte solvent was pure water, and the solutes included 0.1 mol / L aniline, 0.02 mol / L oxalic acid, 0.05 mol / L sulfuric acid, 0.1 mol / L cerium nitrate and 0.05 mol / L ammonium acetate, the constant potential was set to 1.2 V, the electrodeposition time was 15 minutes, and the temperature was 30°C. The working electrode was the pretreated aluminum alloy; the auxiliary electrode was a large-area platinum sheet, and the reference electrode was a saturated calomel electrode.

[0036] Example 2:

[0037] The polyaniline / cerium oxide composite coating was prepared according to the following steps:

[0038] The aluminum alloy is pretreated, including polishing with metallographic sandpaper, polishing to mirror surface, degreasing, cleaning with deionized water and cold air drying. Then the polyaniline / cerium oxide composite coating is electrochemically co-deposited on the surface of the pretreated aluminum alloy by using the constant potential method, the electrolyte solvent is pure water, the solutes include: 0.3 mol / L aniline, 0.05 mol / L oxalic acid, 0.1 mol / L sulfuric acid, 0.15 mol / L cerium nitrate and 0.1 mol / L ammonium acetate, the constant potential is set to 1.5 V, the electrodeposition time is 10 minutes, and the temperature is 40℃. The working electrode is the pretreated aluminum alloy; the auxiliary electrode is a large-area platinum sheet, and the reference electrode is a saturated calomel electrode.

[0039] Example 3

[0040] The polyaniline / cerium oxide composite coating is prepared according to the following steps:

[0041] The aluminum alloy is pretreated, including polishing with metallographic sandpaper, polishing to mirror surface, degreasing, cleaning with deionized water and cold air drying. Then the polyaniline / cerium oxide composite coating is electrochemically co-deposited on the surface of the pretreated aluminum alloy by using the constant potential method, the electrolyte solvent is pure water, the solutes include: 0.3 mol / L aniline, 0.05 mol / L oxalic acid, 0.1 mol / L sulfuric acid, 0.15 mol / L cerium nitrate and 0.1 mol / L ammonium acetate, the constant potential is set to 1.5 V, the electrodeposition time is 10 minutes, and the temperature is 40℃. The working electrode is the pretreated aluminum alloy; the auxiliary electrode is a large-area platinum sheet, and the reference electrode is a saturated calomel electrode.

[0042] Example 4

[0043] The polyaniline / cerium oxide composite coating is prepared according to the following steps:

[0044] The carbon steel is pretreated, including polishing with metallographic sandpaper, polishing to mirror surface, degreasing, cleaning with deionized water and cold air drying. Then the polyaniline / cerium oxide composite coating is electrochemically co-deposited on the surface of the pretreated carbon steel by using the constant potential method, the electrolyte solvent is pure water, the solutes include: 0.2 mol / L aniline, 0.05 mol / L oxalic acid, 0.05 mol / L sulfuric acid, 0.1 mol / L cerium nitrate and 0.1 mol / L ammonium acetate, the constant potential is set to 1.3 V, the electrodeposition time is 12 minutes, and the temperature is 50℃. The working electrode is the pretreated carbon steel alloy; the auxiliary electrode is a large-area platinum sheet, and the reference electrode is a saturated calomel electrode.

[0045] Comparative Example 1

[0046] The polyaniline coating is prepared according to the following steps:

[0047] The aluminum alloy is pretreated, including polishing with metallographic sandpaper, polishing to mirror surface, degreasing, cleaning with deionized water and cold air drying. Then the polyaniline coating is electrochemically co-deposited on the surface of the pretreated aluminum alloy by using the constant potential method, the electrolyte solvent is pure water, and the solutes include 0.1 mol / L aniline, 0.02 mol / L oxalic acid, 0.05 mol / L sulfuric acid and 0.05 mol / L ammonium acetate, the constant potential is set to 1.2 V, the electrodeposition time is 15 minutes, and the temperature is 30 DEG C. The working electrode is the pretreated aluminum alloy; the auxiliary electrode is a large-area platinum sheet, and the reference electrode is a saturated calomel electrode.

[0048] The difference between Comparative Example 1 and Example 1 is that the electrolyte does not contain 0.1 mol / L cerous nitrate, and the other parameters and steps are the same as those in Example 1.

[0049] Comparative Example 2

[0050] The polyaniline coating is prepared according to the following steps:

[0051] The aluminum alloy is pretreated, including polishing with metallographic sandpaper, polishing to mirror surface, degreasing, cleaning with deionized water and cold air drying. Then the polyaniline coating is electrochemically co-deposited on the surface of the pretreated aluminum alloy by using the constant potential method, the electrolyte includes 0.3 mol / L aniline, 0.05 mol / L oxalic acid, 0.1 mol / L sulfuric acid and 0.1 mol / L ammonium acetate, the constant potential is set to 1.5 V, the electrodeposition time is 10 minutes, and the temperature is 40 DEG C. The working electrode is the pretreated aluminum alloy; the auxiliary electrode is a large-area platinum sheet, and the reference electrode is a saturated calomel electrode.

[0052] The difference between Comparative Example 2 and Example 2 is that the electrolyte does not contain 0.15 mol / L cerous nitrate, and the other parameters and steps are the same as those in Example 2.

[0053] Comparative Example 3

[0054] The polyaniline coating is prepared according to the following steps:

[0055] The aluminum alloy is pretreated, including polishing with metallographic sandpaper, polishing to mirror surface, degreasing, cleaning with deionized water and cold air drying. Then the polyaniline coating is electrochemically co-deposited on the surface of the pretreated aluminum alloy by using the constant potential method, the electrolyte includes 0.1 mol / L aniline, 0.02 mol / L oxalic acid, 0.05 mol / L sulfuric acid and 0.1 mol / L ammonium acetate, the constant potential is set to 1.2 V, the electrodeposition time is 10 minutes, and the temperature is 50 DEG C. The working electrode is the pretreated aluminum alloy; the auxiliary electrode is a large-area platinum sheet, and the reference electrode is a saturated calomel electrode.

[0056] The difference between Comparative Example 3 and Example 3 is that no cerium nitrate with a concentration of 0.15 mol / L is added in the electrolyte, and other parameters and steps are consistent with those of Example 3.

[0057] Comparative Example 4

[0058] The poly-aniline coating layer is prepared according to the following steps:

[0059] The carbon steel is pretreated, including polishing with metallographic sandpaper, polishing to mirror surface, degreasing, cleaning with deionized water and cold air drying. Then, the poly-aniline coating layer is electrochemically co-deposited on the surface of the pretreated carbon steel by using the constant potential method, and the electrolyte includes 0.2 mol / L aniline, 0.05 mol / L oxalic acid, 0.05 mol / L sulfuric acid and 0.1 mol / L ammonium acetate, the constant potential is set to 1.3 V, the electrodeposition time is 12 minutes, and the temperature is 50°C. The working electrode is the pretreated carbon steel alloy; the auxiliary electrode is a large-area platinum sheet, and the reference electrode is a saturated calomel electrode.

[0060] The difference between Comparative Example 4 and Example 4 is that no cerium nitrate with a concentration of 0.1 mol / L is added in the electrolyte, and other parameters and steps are consistent with those of Example 4.

[0061] Comparative Example 5

[0062] The AA6061 aluminum alloy sheet of this comparative example is not subjected to any surface treatment.

[0063] Structural characterization and performance test:

[0064] Structural characterization

[0065] The SEM image of the poly-aniline / cerium oxide composite coating layer prepared in Example 1 is shown in FIG. 1, and it can be seen that the coating surface is composed of heterogeneous organic / inorganic hybrid and has a certain roughness, which is beneficial to the formation of a hydrophobic composite coating. Figure 1

[0066] Contact angle measurement

[0067] The contact angle of the poly-aniline / cerium oxide composite coating layer prepared in Example 1 is measured by using a contact angle tester, and the result is shown in FIG. 2, and it can be seen that the contact angle is higher than 120°. The contact angle test result of the poly-aniline coating layer prepared in Comparative Example 1 is shown in FIG. 3, and the contact angle is only 76°, which is much lower than that of the poly-aniline / cerium oxide composite coating layer prepared in Example 1. Figure 2 Figure 3

[0068] Protection performance test

[0069] ​​​Example 2: The aluminum alloy coated with the polyaniline / cerium oxide composite coating prepared in Example 2 was immersed in a 3.5% NaCl solution corrosion medium for 0.5 hours and then subjected to electrochemical impedance testing (frequency: 100 k-10 m Hz), with the untreated aluminum alloy of Comparative Example 5 and the aluminum alloy coated with the polyaniline coating prepared in Comparative Example 2 serving as controls. The results are shown in Table 1. Figures 4-6 and Table 1. The above test results show that the polyaniline / cerium oxide composite coating has the largest increase in charge transfer resistance compared to the untreated aluminum alloy, and the protection efficiency of the polyaniline / cerium oxide composite coating is as high as 98.9%, which is also much higher than that of the polyaniline coating prepared alone.

[0070] Table 1. Electrochemical impedance test results of aluminum alloy substrates after different treatments

[0071] Conditions [R ct ,Ω.cm 2 ]]> % Protection Comparative Example 5, 0.5 hours 126 Example 2, 0.5 hours 11836 98.9 Comparative Example 2, 0.5 hours 1548 91.8

[0072] Long-term protection performance test

[0073] Example 3: The aluminum alloy coated with the polyaniline / cerium oxide composite coating prepared in Example 3 was immersed in a 3.5% NaCl solution corrosion medium for 240 hours and then subjected to electrochemical impedance testing (frequency: 100 k-10 m Hz). The results are shown in Table 2. Figure 7 and Table 2. For further comparison of protection performance, the aluminum alloy coated with the polyaniline coating prepared in Comparative Example 3 was also immersed in a 3.5% NaCl solution corrosion medium for 240 hours and subjected to electrochemical impedance testing. The results are shown in Table 2. Figure 8 and Table 2, which further compared the long-term protection performance of the polyaniline coating and the polyaniline / cerium oxide composite coating in the corrosion medium. The protection efficiency of the polyaniline / cerium oxide composite coating after being immersed in the corrosion medium for 240 hours was still as high as 98.8%, which was basically the same as that after being immersed for 0.5 hours. The protection efficiency of the polyaniline coating, however, decreased by 2.5%. The above test results show that the polyaniline / cerium oxide composite coating has long-term protection performance and is more durable than the existing polyaniline coating.

[0074] Table 2. Electrochemical impedance test results of aluminum alloy substrates after different treatments

[0075] Conditions [R ct ,Ω.cm 2 ]]> % Protection Untreated, 240 hours 126 Example 3, 240 hours 11023 98.8 Comparative Example 3, 240 hours 1182 89.3

[0076] Self-repairing performance test

[0077] The polyaniline / cerium oxide composite coating prepared in Example 4 was tested for self-repairing performance as follows: a 1-cm scratch was made on the polyaniline / cerium oxide composite coating prepared on the surface of the carbon steel substrate in Example 4, and then the coating was immersed in a 3.5% NaCl solution corrosion medium. After 0.5 h and 12 h of immersion, respectively, electrochemical impedance tests were performed (at a frequency of 100 k-10 m Hz), and the results are shown in Table 3. Figure 9 , Figure 10 Table 3 and Table 4. As can be seen from the test results, as the immersion time is extended (from 0.5 h to 12 h), the charge transfer resistance of the polyaniline / cerium oxide composite coating prepared in Example 4 is increased by 42 times, but the charge transfer resistance of the polyaniline coating prepared in Comparative Example 4 is decreased, indicating that the polyaniline / cerium oxide composite coating prepared in Example 4 has excellent self-repairing performance compared with the polyaniline coating of the prior art. Figure 11 , Figure 12 Using the same test method and conditions, it was found that the charge transfer resistance of the polyaniline / cerium oxide composite coatings prepared in Example 1, Example 2 and Example 3 was increased by 43 times, 45 times and 46 times, respectively.

[0078] Table 3 and Table 4. As can be seen from the test results, as the immersion time is extended (from 0.5 h to 12 h), the charge transfer resistance of the polyaniline / cerium oxide composite coating prepared in Example 4 is increased by 42 times, but the charge transfer resistance of the polyaniline coating prepared in Comparative Example 4 is decreased, indicating that the polyaniline / cerium oxide composite coating prepared in Example 4 has excellent self-repairing performance compared with the polyaniline coating of the prior art.

[0079] Table 3 Electrochemical impedance test results of the polyaniline / cerium oxide composite coating of Example 4

[0080] Conditions [R ct ,Ω.cm 2 ]]> 0.5 hours 2175 12 hours 92353

[0081] Table 4 Electrochemical impedance test results of the polyaniline coating of Comparative Example 4

[0082] Conditions [R ct ,Ω.cm 2 ]]> 0.5 hours 1816 12 hours 1492

[0083] In summary, the polyaniline / cerium oxide composite coating prepared in the present application has good hydrophobic properties compared with the polyaniline coating, the protection efficiency for the metal material substrate is greatly improved, and the long-acting protection performance and self-repairing performance also have obvious advantages, and the high-efficiency and long-acting protection of various metal materials can be realized. In addition, the preparation process of the method of the present application is simple, the energy consumption is low, and no expensive equipment is needed, and large-scale production can be carried out, which has a wide industrial application prospect.

[0084] The application is not limited to the embodiments described in the specification and examples, and can be applied to various fields suitable for the application, and additional modifications and variations can be easily made by those skilled in the art without departing from the spirit and essence of the application, and such corresponding modifications and variations should be included in the scope of protection required by the application.

[0085] The above only describes some embodiments of the application, and does not limit the embodiments and protection scope of the application. Those skilled in the art should realize that any equivalent replacement and obvious changes made according to the content of the specification should be included in the protection scope of the application.

Claims

1. A method for preparing a hydrophobic self-healing polyaniline / cerium oxide composite coating, characterized in that: Includes the following steps: S1: Pretreatment of the metal substrate; S2: Prepare an electrolyte containing 0.1-0.3 mol / L aniline, 0.02-0.05 mol / L oxalic acid, 0.05-0.1 mol / L sulfuric acid, 0.1-0.15 mol / L cerium nitrate, and 0.05-0.1 mol / L ammonium acetate, with pure water as the solvent; S3: A polyaniline / cerium oxide composite coating was prepared by electrochemical co-deposition on the surface of a metal substrate using a constant potential method. The constant potential was set to 1.2~1.5V, the electrodeposition time was 10~15 minutes, and the electrodeposition temperature was 30~50℃.

2. The preparation method according to claim 1, characterized in that: In step S3, the working electrode is a pretreated metal substrate; the auxiliary electrode is a large-area platinum sheet; and the reference electrode is a saturated calomel electrode.

3. The preparation method according to claim 1, characterized in that: In step S1, the pretreatment includes metallographic sanding, polishing, degreasing, deionized water cleaning, and cold air drying.

4. The preparation method according to claim 1, characterized in that: The electrolyte contains 0.3 mol / L aniline, 0.05 mol / L oxalic acid, 0.1 mol / L sulfuric acid, 0.1 mol / L cerium nitrate, and 0.05 mol / L ammonium acetate.

5. A hydrophobic self-healing polyaniline / cerium oxide composite coating, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 4.

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