A corrosion-resistant self-repairing metal coating system and preparation method thereof

Abstract

The present invention belongs to the technical field of metal corrosion and protection, and specifically relates to a corrosion-resistant self-repairing metal coating system for protecting a metal substrate from external erosion and a preparation method thereof. Firstly, the surface of mesoporous silica is functionally modified by silanization, and then nano-mesoporous silica particles carrying an inorganic corrosion inhibitor are used as a self-repairing material. Finally, the self-repairing material and a nickel-based coating are co-deposited on the surface of the metal substrate by an electrochemical method to obtain a metal coating system with corrosion resistance, wear resistance and self-repairing functions. When corrosion occurs, the corrosion inhibitor anions loaded in the mesoporous silica are released to form an insoluble iron-based protective film at the corrosion site, which plays a role in inhibiting the corrosion of the metal substrate. Compared with the organic self-repairing coating prepared on the surface of the metal substrate, it also has the advantages of high microhardness, good wear resistance and high economic value, and is a powerful means to protect the metal substrate from external erosion.

Description

Technical field:

[0001] The present invention belongs to the technical field of metal corrosion and protection, and specifically relates to a corrosion-resistant self-repairing metal coating system for protecting a metal substrate from external corrosion and a preparation method thereof. Background technology:

[0002] Electroplating is the most commonly used treatment method in the material surface treatment process. After electroplating, the surface characteristics and appearance of the base metal material can be changed, and the corrosion resistance and wear resistance and other properties can be improved. Metal and its alloy coatings have good physical, chemical and mechanical properties: high hardness, wear resistance and corrosion resistance, etc., and are widely used in the surface treatment of steel. Among them, nickel plating has good corrosion resistance and good wear resistance, so it is widely used in petrochemical, shipbuilding, machinery and metallurgy as a protective decorative coating. Nickel plating is a cathodic coating for iron base. In the process of electrodeposition, solid nanoparticles can be added to the electroplating solution as a reinforcing phase to prepare a composite coating with finer grains and better performance, which can meet the needs of engineering applications.

[0003] In engineering applications, when the coating is in good condition, its physical shielding effect has an excellent barrier effect on corrosive ions and water, thereby providing good protection for the metal substrate. However, during transportation, installation and service, the coating is inevitably mechanically damaged and produces microcracks. Microcracks will become channels for the rapid penetration of corrosive media, affecting the protection of the metal substrate by the coating system. If timely and effective repairs are not taken, it will eventually lead to premature failure of the coating and accelerate the corrosion of the metal substrate. How to improve the anti-corrosion performance and service life has become a key issue that needs to be solved in the actual application of the coating. With the development of smart material technology, self-repairing anti-corrosion coatings have been rapidly developed. This type of coating has self-healing properties after local damage, and can repair defects without affecting the overall performance of the system, which can significantly improve the anti-corrosion performance and service life of the coating. Specifically, the self-repairing material in the self-repairing anti-corrosion coating responds to damage, repairs the damaged part without affecting the overall performance of the system, ensures the durability and safety of the material, thereby greatly reducing the cost of maintenance and repair, and provides an ideal way to solve the external trauma and internal defects of the material.

[0004] At present, most self-repairing anti-corrosion coatings are organic coating systems. By adding self-repairing materials to the organic coating, the purpose of actively protecting the metal substrate is achieved. Due to the many factors that affect the electrodeposition process, there are relatively few studies on the preparation of metal self-repairing coatings. How to achieve co-deposition of self-repairing materials and metal coatings is a difficult point in this technical field. Nguyen et al. prepared a self-repairing Zn-Ni-SiO2 (Ce) metal coating for the protection of carbon steel substrates by co-depositing Ce-loaded nano-silica particles in Zn-Ni composite coatings. Salt spray tests show that the corrosion inhibitor Ce 3+ It can be released from the silica nanoparticles to inhibit the cathode reaction to inhibit the corrosion of the alloy coating, but the corrosion inhibitor Ce in the Zn-Ni-SiO2 (Ce) metal coating 3+ It mainly acts on the surface of SiO2 particles through electrostatic adsorption, the corrosion inhibitor loading rate is low and it is easy to leak prematurely, and the self-repairing efficiency is low. Therefore, it is necessary to construct an efficient corrosion-resistant self-repairing metal coating system for the protection of carbon steel substrates. Summary of the invention:

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art, develop and design a corrosion-resistant self-repairing metal coating system and a preparation method thereof, and electroplate a nickel-based composite coating with self-repairing properties on the surface of carbon steel.

[0006] In order to achieve the above-mentioned purpose, the corrosion-resistant self-repairing metal coating system involved in the present invention includes a metal coating and a nanocontainer loaded with a corrosion inhibitor doped inside the metal coating; the nanocontainer includes mesoporous silica (MSN), which has a large specific surface area and a large pore volume, can refine the metal coating grains, and helps to load more corrosion inhibitors.

[0007] When the corrosion-resistant self-repairing metal coating system of the present invention is used, the corrosive medium penetrates the pores of the metal coating and diffuses to the surface of the metal substrate, causing the metal substrate to corrode and dissolve, and the released cations Fe 3+ It reacts with the corrosion inhibitor anions loaded in the nanocontainer in the corrosion anode area to form an insoluble iron-based protective film with a hard texture and good bonding with the metal matrix, which can effectively inhibit further corrosion and dissolution of the metal matrix.

[0008] The process of the method for preparing the corrosion-resistant self-repairing metal coating system of the present invention comprises five steps: preparing amino-modified mesoporous silica, preparing mesoporous silica with trivalent iron adsorbed on the surface, preparing mesoporous silica loaded with corrosion inhibitor, preparing composite electroplating solution and electrochemical co-deposition:

[0009] (1) Preparation of amino-modified mesoporous silica

[0010] Mesoporous silica with a particle size of 10-80 nm is dispersed in methanol to form a mixed solution, 3-aminopropyltriethylsilane (APTES) is added dropwise to the mixed solution, wherein the ratio of the concentration of 3-aminopropyltriethylsilane to the molar concentration of mesoporous silica is 1-1.5:1, stirred at room temperature for 24 hours, centrifuged, and washed with methanol to obtain amino-modified mesoporous silica (MSN-NH2);

[0011] (2) Preparation of mesoporous silica with trivalent iron adsorbed on the surface

[0012] MSN-NH2 particles and FeCl3 were dispersed in propanol, wherein the ratio of the concentration of MSN-NH2 to the concentration of FeCl3 was 1:1, stirred at room temperature for 6 hours, centrifuged, and washed with ethanol to obtain mesoporous silica (MSN-NH2-Fe) with trivalent iron adsorbed on the surface;

[0013] (3) Preparation of mesoporous silica loaded with corrosion inhibitor

[0014] Dispersing MSN-NH2-Fe particles and corrosion inhibitor in water, wherein the ratio of the concentration of MSN-NH2-Fe to the concentration of the corrosion inhibitor is 1-2:1, the corrosion inhibitor is an inorganic corrosion inhibitor, including orthophosphate, condensed phosphate, and molybdate, magnetic stirring for 24 hours, centrifugal separation, washing with ethanol, and vacuum drying to obtain mesoporous silica loaded with corrosion inhibitor;

[0015] (4) Preparation of composite electroplating solution

[0016] Add nickel sulfate, nickel chloride and boric acid to deionized water, stir magnetically for 24 hours to obtain a salt solution, add mesoporous silica loaded with a corrosion inhibitor to the salt solution, stir fully for 1-2 hours to obtain a composite electroplating solution with uniformly dispersed solid particles, wherein the concentration of nickel sulfate is 200-300 g / L, the concentration of nickel chloride is 20-60 g / L, the concentration of boric acid is 25-45 g / L, and the concentration of mesoporous silica loaded with a corrosion inhibitor is 1-10 g / L;

[0017] (5) Electrochemical co-deposition

[0018] The pretreated metal substrate is placed in the composite electroplating solution, with a pure nickel plate as the anode and an Ag / AgCl electrode as the reference electrode. 2Electrodeposition is carried out for 20-60 minutes under the conditions of , the metal substrate is taken out, washed with deionized water, and dried with cold air to obtain a corrosion-resistant self-repairing metal coating system, and the composite electroplating solution is magnetically stirred during the electrodeposition process; the metal substrate includes a carbon steel substrate, and the pretreatment is to degrease, derust and polish the surface of the metal substrate. The specific process is: first, the surface of the metal substrate is polished step by step to 2000 mesh with SiC sandpaper, and then mechanical polishing is performed, and finally, it is ultrasonically cleaned with anhydrous ethanol and deionized water in turn, and dried for use.

[0019] The purpose of the silylation of the mesoporous silica surface by 3-aminopropyltriethylsilane involved in the present invention is to generate active sites for chemical reactions, so that the surface aminated MSN is further modified by Fe(III) ions to efficiently adsorb corrosion inhibitor anions.

[0020] Compared with the prior art, the present invention first performs silanization functional modification on the surface of mesoporous silica, then uses nano-mesoporous silica particles carrying inorganic corrosion inhibitors as self-repairing materials, and finally realizes co-deposition of the self-repairing material and the nickel-based coating on the surface of the metal substrate by an electrochemical method, thereby obtaining a metal coating system with corrosion resistance, wear resistance and self-repairing functions. When corrosion occurs, the corrosion inhibitor anions loaded in the mesoporous silica are released to form an insoluble iron-based protective film at the corrosion site, thereby inhibiting the corrosion of the metal substrate. Compared with the organic self-repairing coating prepared on the surface of the metal substrate, the present invention also has the advantages of high microhardness, good wear resistance and high economic value, and is a powerful means of protecting the metal substrate from external corrosion. The present invention is suitable for petrochemical, automotive, marine equipment and engineering, and is particularly suitable for various types of metal fasteners. Description of the drawings:

[0021] Figure 1 The present invention is a flow chart of the preparation process of mesoporous silica loaded with corrosion inhibitor.

[0022] Figure 2 The present invention is a schematic diagram comparing the working principles of the pure nickel plating layer and the corrosion inhibitor@nanocontainer doped nickel plating layer, wherein (A) is the pure nickel plating layer and (B) is the corrosion inhibitor@nanocontainer doped nickel plating layer. Specific implementation method:

[0023] The present invention will be further described below in conjunction with the accompanying drawings and in conjunction with specific implementation methods.

[0024] Embodiment 1:

[0025] The specific process of the method for preparing the corrosion-resistant self-repairing metal coating system involved in this embodiment is as follows:

[0026] 0.6 g of MSN was dispersed in 150 mL of methanol to form a mixed solution, 3 mL of 3-aminopropyltriethylsilane (APTES) was added dropwise to the mixed solution, stirred at room temperature for 24 h, centrifuged, and washed with methanol to obtain amino-modified mesoporous silica (MSN-NH2);

[0027] 0.5 g MSN-NH2 particles and 0.5 g FeCl3 were dispersed in 150 mL propanol, stirred at room temperature for 6 h, centrifuged, and washed with ethanol to obtain mesoporous silica with trivalent iron adsorbed on the surface (MSN-NH2-Fe);

[0028] 0.5 g MSN-NH2-Fe particles and 0.25 g sodium phosphate were dispersed in 100 mL water, magnetically stirred for 24 h, centrifuged, washed with ethanol, and vacuum dried to obtain mesoporous silica loaded with sodium phosphate;

[0029] Nickel sulfate, nickel chloride, boric acid and deionized water were mixed to form a mixed solution with a volume of 200 mL, and after stirring at room temperature for 24 hours, 0.4 g of mesoporous silica particles loaded with sodium phosphate were added and stirred for 1 hour to obtain a composite electroplating solution, wherein the concentration of nickel sulfate was 280 g / L, the concentration of nickel chloride was 40 g / L, and the concentration of boric acid was 40 g / L;

[0030] The pretreated carbon steel substrate was placed in the composite electroplating solution at 2.5A / dm 2 Electrodeposition was carried out for 30 min at a current density of , and the carbon steel substrate was taken out, washed with deionized water, and dried with cold air to obtain a corrosion-resistant self-repairing metal coating system. The composite electroplating solution was electromagnetically stirred during the electrodeposition process.

[0031] Embodiment 2:

[0032] The specific process of the method for preparing the corrosion-resistant self-repairing metal coating system involved in this embodiment is as follows:

[0033] 0.6 g of MSN was dispersed in 150 mL of methanol to form a mixed solution, 3 mL of 3-aminopropyltriethylsilane (APTES) was added dropwise to the mixed solution, stirred at room temperature for 24 h, centrifuged, and washed with methanol to obtain amino-modified mesoporous silica (MSN-NH2);

[0034] 0.5 g MSN-NH2 particles and 0.5 g FeCl3 were dispersed in 150 mL propanol, stirred at room temperature for 6 h, centrifuged, and washed with ethanol to obtain mesoporous silica with trivalent iron adsorbed on the surface (MSN-NH2-Fe);

[0035] 0.5 g MSN-NH2-Fe particles and 0.3 g sodium polyphosphate were dispersed in 100 mL water, magnetically stirred for 24 h, centrifuged, washed with ethanol, and vacuum dried to obtain mesoporous silica loaded with sodium polyphosphate;

[0036] Nickel sulfate, nickel chloride, boric acid and deionized water were mixed to prepare a mixed solution with a volume of 200 mL, and after stirring at room temperature for 24 hours, 0.3 g of mesoporous silica particles loaded with sodium polyphosphate were added and stirred for 2 hours to obtain a composite electroplating solution;

[0037] The pretreated carbon steel substrate is placed in the composite electroplating solution at 2A / dm 2 Electrodeposition was carried out for 60 min at a current density of , and the carbon steel substrate was taken out, washed with deionized water, and dried with cold air to obtain a corrosion-resistant self-repairing metal coating system. The composite plating solution was electromagnetically stirred during the electrodeposition process.

[0038] Embodiment 3:

[0039] The specific process of the method for preparing the corrosion-resistant self-repairing metal coating system involved in this embodiment is as follows:

[0040] 0.6 g of MSN was dispersed in 150 mL of methanol to form a mixed solution, 3 mL of 3-aminopropyltriethylsilane (APTES) was added dropwise to the mixed solution, stirred at room temperature for 24 h, centrifuged, and washed with methanol to obtain amino-modified mesoporous silica (MSN-NH2);

[0041] 0.5 g MSN-NH2 particles and 0.5 g FeCl3 were dispersed in 150 mL propanol, stirred at room temperature for 6 h, centrifuged, and washed with ethanol to obtain mesoporous silica with trivalent iron adsorbed on the surface (MSN-NH2-Fe);

[0042] 0.5 g MSN-NH2-Fe particles and 0.25 g sodium molybdate were dispersed in 100 mL water, magnetically stirred for 24 h, centrifuged, washed with ethanol, and vacuum dried to obtain mesoporous silica loaded with sodium molybdate;

[0043] Nickel sulfate, nickel chloride, boric acid and deionized water were mixed to prepare a mixed solution with a volume of 200 mL, and after stirring at room temperature for 24 hours, 0.5 g of mesoporous silica particles loaded with sodium molybdate were added and stirred for 1.5 hours to obtain a composite electroplating solution;

[0044] The pretreated carbon steel substrate was placed in the composite plating solution at 3A / dm 2 Electrodeposition was carried out for 40 min at a current density of , and the carbon steel substrate was taken out, washed with deionized water, and dried with cold air to obtain a corrosion-resistant self-repairing metal coating system. The composite electroplating solution was electromagnetically stirred during the electrodeposition process.

Claims

1. A method for preparing a corrosion-resistant self-repairing metal coating system, characterized in that: The method includes five steps: preparing amino-modified mesoporous silica, preparing mesoporous silica with trivalent iron adsorbed on the surface, preparing mesoporous silica loaded with corrosion inhibitor, preparing composite electroplating solution and electrochemical co-deposition. (1) Preparation of amino-modified mesoporous silica Dispersing mesoporous silica in methanol to form a mixed solution, adding 3-aminopropyltriethylsilane dropwise to the mixed solution, stirring at room temperature for 24 hours, centrifuging, and washing with methanol to obtain amino-modified mesoporous silica; (2) Preparation of mesoporous silica with trivalent iron adsorbed on the surface MSN-NH2 particles and FeCl3 were dispersed in propanol, stirred at room temperature for 6 h, centrifuged, and washed with ethanol to obtain mesoporous silica with trivalent iron adsorbed on the surface; (3) Preparation of mesoporous silica loaded with corrosion inhibitor The MSN-NH2-Fe particles and the corrosion inhibitor were dispersed in water, magnetically stirred for 24 hours, centrifuged, washed with ethanol, and vacuum dried to obtain mesoporous silica loaded with the corrosion inhibitor; Among them, the corrosion inhibitor is an inorganic corrosion inhibitor, including orthophosphate, condensed phosphate, and molybdate; (4) Preparation of composite electroplating solution Add nickel sulfate, nickel chloride and boric acid to deionized water, stir magnetically for 24 hours to obtain a salt solution, add mesoporous silica loaded with a corrosion inhibitor to the salt solution, stir fully for 1-2 hours, and obtain a composite electroplating solution with uniformly dispersed solid particles; (5) Electrochemical co-deposition The pretreated metal substrate is placed in the composite electroplating solution, with a pure nickel plate as the anode and an Ag / AgCl electrode as the reference electrode. 2 Electrodeposition is carried out for 20-60 minutes under the conditions, the metal substrate is taken out, washed with deionized water, and dried with cold air to obtain a corrosion-resistant self-repairing metal coating system.

2. The method for preparing the corrosion-resistant self-repairing metal coating system according to claim 1, characterized in that: In step (1), the ratio of the concentration of 3-aminopropyltriethylsilane to the molar concentration of mesoporous silica is 1-1.5:

1.

3. The method for preparing the corrosion-resistant self-repairing metal coating system according to claim 1, characterized in that: In step (2), the ratio of the concentration of MSN-NH2 to the concentration of FeCl3 is 1:

1.

4. The method for preparing the corrosion-resistant self-repairing metal coating system according to claim 1, characterized in that: In step (3), the ratio of the concentration of MSN-NH2-Fe to the concentration of the corrosion inhibitor is 1-2:

1.

5. The method for preparing the corrosion-resistant self-repairing metal coating system according to claim 1, characterized in that: In step (4), the concentration of nickel sulfate is 200-300 g / L, the concentration of nickel chloride is 20-60 g / L, the concentration of boric acid is 25-45 g / L, and the concentration of mesoporous silica loaded with corrosion inhibitor is 1-10 g / L.

6. The method for preparing the corrosion-resistant self-repairing metal coating system according to claim 1, characterized in that: In step (5), the composite electroplating liquid is magnetically stirred during the electrodeposition process; the metal substrate includes a carbon steel substrate, and the pretreatment is to degrease, derust and polish the surface of the metal substrate. The specific process is: first, the surface of the metal substrate is gradually polished to 2000 mesh with SiC sandpaper, then mechanically polished, and finally, ultrasonically cleaned with anhydrous ethanol and deionized water in turn, and dried for use.

7. The method for preparing the corrosion-resistant self-repairing metal coating system according to claim 1 or 2, characterized in that: In step (1), the particle size of the mesoporous silica is 10-80 nm.

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