Early warning agent for early corrosion early warning of steel and synthetic method thereof

Abstract

The invention discloses an early warning agent for early corrosion early warning of steel and a synthesis method of the early warning agent. The early warning agent comprises a porous MOF-5 material, the phenanthroline (Phen) is used as an early warning substance, is released when corrosion occurs and reacts with a corrosion product, provides visual early warning of color change and plays a role in corrosion inhibition at the same time; and chitosan (CTS) as a particle shell. The synthesis method comprises the following steps: dissolving a zinc source substance (such as zinc acetate dihydrate, zinc nitrate hexahydrate and the like) and terephthalic acid (TPA) in dimethylformamide (DMF), and performing ultrasonic treatment and standing to obtain a porous MOF-5 material; the preparation method comprises the following steps: dispersing an MOF-5 material in absolute ethyl alcohol, adding phenanthroline, and stirring for dissolving; after vacuum treatment and centrifugal washing, a chitosan acetic acid solution is dropwise added, and finally the early warning agent for early corrosion early warning of steel is obtained. The early warning agent has the characteristics of environmental protection, no pollution, intelligent release, and integration of corrosion inhibition and early warning, can provide macroscopic color change early warning when the coating loses efficacy, effectively delays the corrosion process, is suitable for an anticorrosive coating of a steel structure, reduces the maintenance cost, and improves the safety.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion and protection, and in particular to an early warning agent for early warning of steel corrosion and a synthesis method thereof. Background Art

[0002] Currently, steel, as a high-strength, low-cost material, is widely used in the fields of people's livelihood, transportation, military, engineering, etc. However, steel has active chemical properties and is very prone to oxidation and corrosion under service conditions. Corrosion will reduce the cross-sectional area of ​​steel, resulting in a decrease in its bearing capacity and affecting the stability of the structure. Rust pits and cracks caused by rust increase the risk of steel fracture, posing a serious threat to the safe operation of structures and equipment. In addition, corrosion products released into the environment are also potentially environmentally destructive. Therefore, in order to ensure the safe service of steel, effective anti-corrosion measures must be taken. The most common means of anti-corrosion is to apply organic coatings. The anti-corrosion principle of organic coatings is to solidify on the surface of steel to form a barrier film layer to prevent steel from contacting corrosive media (oxygen, water, corrosive ions). However, due to the limitations of preparation methods, coating processes and service conditions, organic coatings always inevitably have microscopic defects, and corrosive media can slowly penetrate along the coating defects or degrade the coating. When the coating is completely penetrated, the coating becomes ineffective and the surface of the coating and the steel will be corroded, destroying the adhesion conditions of the coating. As the corrosion deepens, the organic coating will be damaged and fall off in large quantities, and the situation will continue to deteriorate.

[0003] To protect the surface where the organic coating adheres and further enhance the coating's corrosion resistance, a common practice is to add corrosion inhibitors to the coating. Currently, numerous corrosion inhibitors have been developed and disclosed, such as the glass fiber corrosion inhibitor coating disclosed in CN114539898A and the silane corrosion inhibitor disclosed in CN119119495A. In practical applications, coatings require regular replacement to prevent corrosion of the steel substrate due to coating failure. However, currently available corrosion inhibitors can only slow corrosion and cannot indicate the progress of coating failure, making replacement of anti-corrosion coatings somewhat unreliable.

[0004] Early warning agents should be able to identify the failure state of the coating while inhibiting corrosion, and provide a visual warning when the coating fails, thereby providing a basis for timely replacement of the coating. This can avoid substrate corrosion caused by untimely coating replacement and save maintenance costs caused by too frequent coating replacement. However, the development of early warning agents also faces major technical challenges. For example, the early warning agent migrates in the coating, causing uneven coating properties and reducing the shielding performance of the coating. Another example is that the early warning agent reacts with the film-forming substance, competing for binding active sites and reducing the cross-linking degree of the coating. Therefore, how to ensure the controlled release of the early warning agent so that it can effectively play its early warning function without affecting the performance of the coating is a major technical problem.

[0005] In summary, it is very necessary to develop an early warning agent for steel corrosion that has obvious effects, wide applicability, strong corrosion inhibition, can be released in a controlled manner, and does not affect the properties of the coating, so as to provide a basis for replacing the coating and reduce the operation and maintenance costs of steel structures. Summary of the Invention

[0006] In view of the shortcomings of the background technology, the present invention provides an early warning agent for early warning of steel corrosion and a synthesis method thereof, which solves the problem that current coatings cannot provide visual warnings when the coatings fail.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The first aspect of the present invention provides an early warning agent for early warning of steel corrosion, which is made of the following raw materials in parts by weight: 160-200 parts of porous MOF-5 material; 30-50 parts of o-phenanthroline (Phen); and 2-3 parts of chitosan (CTS).

[0009] Preferably, the synthesis method of the MOF-5 porous material is as follows: dissolving a zinc source material in N-N dimethylformamide (DMF) in an amount of 25-30 parts by weight, adding 70-75 parts of TPA, ultrasonically treating the solution and allowing it to stand. After the solution is clarified, the precipitate is centrifuged, washed, and dried.

[0010] Preferably, the zinc source material is zinc acetate dihydrate (Zn(AC)2·2H2O), zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc sulfate monohydrate (ZnSO4·H2O), zinc naphthenate ((C 11 H7O2)2·Zn) one or more.

[0011] Preferably, in terms of microstructure, the porous MOF-5 material acts as a skeleton in the microparticles, and o-phenanthroline (Phen) is adsorbed and loaded in the gaps of the porous MOF-5 material. Chitosan is located in the outer layer, wrapping the porous MOF-5 material and o-phenanthroline (Phen) inside. The microstructure is a spherical structure with a diameter between 1-5 μm.

[0012] Preferably, the synthesis method of the early warning agent is: ultrasonically dispersing the porous MOF-5 material in anhydrous ethanol, adding phenanthroline (Phen) and stirring to fully dissolve it, then performing vacuum treatment, centrifuging and washing the treated turbid liquid to obtain a precipitate, using deionized water to disperse the precipitate again, and then adding CTS acetic acid solution dropwise while stirring, maintaining the stirring state for a period of time, centrifuging and washing the turbid liquid and drying it to obtain the early warning agent for early warning of steel corrosion.

[0013] Preferably, the ultrasonic dispersion process lasts for 15 to 60 minutes.

[0014] Preferably, the stirring speed during the stirring process is 1500-3000 rpm, and the stirring time is 30-60 min.

[0015] Preferably, the vacuum degree of the vacuum treatment process is 0.09 to 0.1 MPa, and the vacuum treatment time is 1 to 5 days (d).

[0016] Preferably, the drying temperature in the drying process is 60-100° C., and the drying time is 1-2 days.

[0017] The second aspect of the present invention further provides a method for synthesizing an early warning agent for early warning of steel corrosion, comprising the following steps:

[0018] S1, take 25-30 parts by weight of zinc source material and dissolve it in NN dimethylformamide (DMF), the zinc source material is zinc acetate dihydrate (Zn(AC)2·2H2O), zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc sulfate monohydrate (ZnSO4·H2O), zinc naphthenate ((C 11 H7O2)2·Zn) is added to one or more of the following: 70-75 parts by weight of TPA, and after ultrasonic treatment, the solution is allowed to stand. After the solution is clarified, the precipitate is centrifuged, washed, and dried to obtain a porous MOF-5 material;

[0019] S2, ultrasonically dispersing the porous MOF-5 material obtained in S1 in anhydrous ethanol, adding o-phenanthroline (Phen) and stirring to fully dissolve it to obtain a suspension;

[0020] S3, vacuum-treating the suspension obtained in S2, centrifuging and washing the treated turbid liquid to obtain a precipitate, and redispersing the precipitate with deionized water to obtain a turbid liquid;

[0021] S4. Keep stirring the turbid liquid obtained in S3, add the acetic acid solution of CTS dropwise to the stirring liquid, keep stirring for a period of time, centrifuge the turbid liquid, wash and dry it, and obtain the early warning agent for early warning of steel corrosion.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides an early warning agent for early corrosion warning of steel. It can automatically identify early corrosion of steel in the organic coating of steel, and provide a visual warning by causing color changes. The warning effect can be directly observed with the naked eye without the aid of instruments. The warning components of this type of early warning agent are usually wrapped inside the particles and can be released intelligently to avoid coating defects caused by premature release of the warning agent and migration in the coating. When an early warning occurs, the warning component can complex with the early corrosion product, cut off the corrosion process, and play a corrosion inhibition role. The porous MOF-5 material used has a rich nanostructure and can produce a "maze effect" in the coating to prevent further penetration of the corrosive medium. The components of this early warning agent are environmentally friendly and pollution-free, the synthesis method is simple, and it has excellent environmental friendliness and economy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and examples:

[0025] Figure 1 Schematic diagram of the microstructure provided by an embodiment of the present invention.

[0026] Figure 2 It is a schematic diagram of the working principle provided by an embodiment of the present invention.

[0027] Figure 3 This is an infrared spectrum provided by an embodiment of the present invention.

[0028] Figure 4 It is a schematic diagram of the early warning effect of an embodiment of the present invention.

[0029] Explanation of the accompanying symbols: 1. porous MOF-5 material; 2. warning substance; 3. shell. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0031] The first aspect of the present invention provides an early warning agent for early warning of steel corrosion, which is composed of nano- to micron-sized microspheres, such as Figure 1 As shown, the warning agent for early warning of steel corrosion is composed of a skeleton made of porous MOF-5 material 1, which is used to support the microparticle structure. It provides abundant pores for loading warning substances and produces a "maze effect" in the coating to block the penetration of corrosive media.

[0032] The warning substance 2, whose main component is 1, is used to provide color warning. When no corrosion occurs, it is adsorbed in the pores of the porous MOF-5 material 1. When the early corrosion of steel is identified, it is released from the microparticles, combines with the early corrosion products to cause color change, and consumes the corrosion products to inhibit corrosion.

[0033] The shell 3 composed of chitosan is used to encapsulate the warning substance and realize the controllable release of the warning substance.

[0034] like Figure 2 As shown, when the warning agent used for early warning of steel corrosion identifies the local acidified environment caused by early corrosion, the chitosan shell 3 breaks under acidic conditions and releases the warning substance 2. After the warning substance 2 comes into contact with the early corrosion product, a complex reaction occurs, providing a visual color change warning and preventing the development of the early corrosion process.

[0035] The above-mentioned warning agent for early warning of steel corrosion is made of the following raw materials in parts by weight: 160-200 parts of porous MOF-5 material; 30-50 parts of o-phenanthroline (Phen); and 2-3 parts of chitosan (CTS).

[0036] Among them, the synthesis method of MOF-5 porous material is as follows: taking a zinc source material and dissolving it in N-N dimethylformamide (DMF) to make the added amount of zinc element be 25-30 parts by weight, and then adding 70-75 parts of TPA. After ultrasonic treatment, let it stand. After the solution is clarified, the precipitate is centrifuged, washed and dried.

[0037] In an embodiment of the present invention, the zinc source material is zinc acetate dihydrate (Zn(AC)2·2H2O), zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc sulfate monohydrate (ZnSO4·H2O), zinc naphthenate ((C 11 H7O2)2·Zn) one or more.

[0038] The early warning agent prepared by the present invention has a microstructure in which the porous MOF-5 material acts as a skeleton in the microparticles, and o-phenanthroline (Phen) is adsorbed and loaded in the gaps of the porous MOF-5 material. Chitosan is located in the outer layer, wrapping the porous MOF-5 material and o-phenanthroline (Phen) inside. The microstructure is a spherical structure with a diameter between 1-5 μm.

[0039] Example 1

[0040] This embodiment provides a method for synthesizing an early warning agent for early warning of steel corrosion, which includes the following steps:

[0041] S1. Dissolve 15.8 g of Zn(AC)2·2H2O in 80 mL of DMF, add 3.8 g of TPA, and ultrasonicate for 15 min before allowing to stand for 2 days. After the solution becomes clear, centrifuge and wash the precipitate, then dry it at 60 °C for 1 day to obtain a porous MOF-5 material.

[0042] S2. The porous MOF-5 material obtained in S1 was dispersed in anhydrous ethanol by ultrasonication for 15 min, 10 g of Phen was added and stirred at 1500 rpm for 40 min to fully dissolve it;

[0043] S3, vacuum-treating the suspension obtained in S2 at a vacuum degree of 0.1 MPa for 1 day, centrifuging the treated turbid liquid to obtain a precipitate, and ultrasonically dispersing the precipitate again with deionized water for 15 minutes to obtain a turbid liquid;

[0044] S4. Keep stirring the turbid liquid obtained in S3 at 1500 rpm, add CTS acetic acid solution dropwise to the stirring solution, stir for 30 minutes, centrifuge the turbid liquid, wash with deionized water, and dry at 60° C. for 1 day to obtain about 5 g of an early warning agent for early warning of steel corrosion.

[0045] Example 2

[0046] The synthesis of the early warning agent for early warning of steel corrosion is carried out through the following steps:

[0047] S1. Dissolve 2170 g of Zn(NO3)2·6H2O in 5000 mL of DMF, add 370 g of TPA, and ultrasonicate for 50 min before standing for 1 day. After the solution is clarified, centrifuge and wash the precipitate, then dry it at 60 °C for 2 days to obtain a porous MOF-5 material.

[0048] S2. The porous MOF-5 material obtained in S1 was dispersed in anhydrous ethanol by ultrasonication for 40 min, 1000 g of Phen was added and stirred at 2000 rpm for 30 min to fully dissolve it;

[0049] S3, vacuum-treating the suspension obtained in S2 for 4 days, centrifuging and washing the treated turbid liquid to obtain a precipitate, and ultrasonically dispersing the precipitate again with deionized water for 40 minutes to obtain a turbid liquid;

[0050] S4. Keep stirring the turbid liquid obtained in S3 at 2000 rpm, add the acetic acid solution of CTS dropwise to the stirring turbid liquid, stir for 30 minutes, centrifuge the turbid liquid, wash with deionized water, and dry at 80° C. for 2 days to obtain about 500 g of an early warning agent for early warning of steel corrosion.

[0051] Example 3

[0052] The synthesis of the early warning agent for early warning of steel corrosion is carried out through the following steps:

[0053] S1. Dissolve 2327 g of zinc naphthenate in 4500 mL of DMF, add 370 g of TPA, and ultrasonicate for 50 min before allowing to stand for 1 day. After the solution becomes clear, centrifuge and wash the precipitate, then dry it at 80°C for 2 days to obtain a porous MOF-5 material.

[0054] S2. The porous MOF-5 material obtained in S1 was dispersed in anhydrous ethanol by ultrasonication for 60 min, 980 g of Phen was added and stirred at 2500 rpm for 30 min to fully dissolve it;

[0055] S3, vacuum-treating the suspension obtained in S2 at a vacuum degree of 0.09 MPa for 3 days, centrifuging and washing the treated turbid liquid to obtain a precipitate, and ultrasonically dispersing the precipitate again with deionized water for 50 minutes to obtain a turbid liquid;

[0056] S4. Keep stirring the turbid liquid obtained in S3 at 1500 rpm, add the acetic acid solution of CTS dropwise to the stirring turbid liquid, stir for 40 minutes, centrifuge the turbid liquid, wash with deionized water, and dry at 85° C. for 2 days to obtain about 500 g of an early warning agent for early warning of steel corrosion.

[0057] Example 4

[0058] The synthesis of the early warning agent for early warning of steel corrosion is carried out through the following steps:

[0059] S1. Dissolve 130 g of zinc naphthenate in 300 mL of DMF, add 33 g of TPA, and ultrasonicate for 20 min before allowing to stand for 1 day. After the solution becomes clear, centrifuge, wash, and dry the precipitate to obtain a porous MOF-5 material.

[0060] S2. The porous MOF-5 material obtained in S1 was dispersed in anhydrous ethanol by ultrasonication for 50 min, 90 g of Phen was added and stirred at 2000 rpm for 50 min to fully dissolve it;

[0061] S3, vacuum-treating the suspension obtained in S2 at a vacuum degree of 0.1 MPa for 1 day, centrifuging the treated turbid liquid to wash and obtain a precipitate, and ultrasonically dispersing the precipitate again with deionized water for 20 minutes to obtain a turbid liquid;

[0062] S4. Keep stirring the turbid liquid obtained in S3 at 1500 rpm, add the acetic acid solution of CTS dropwise to the stirring liquid, stir for 30 minutes, centrifuge the turbid liquid, wash with deionized water, and dry at 60° C. for 1 day to obtain about 45 g of an early warning agent for early warning of steel corrosion.

[0063] Characterization and performance testing

[0064] The porous MOF-5 material and the early warning agent for early warning of steel corrosion are subjected to infrared spectroscopy analysis. The porous MOF-5 material and the early warning agent for early warning of steel corrosion have the following characteristics: Figure 3 The infrared spectrum characteristics shown. The porous MOF-5 material and the 1689 cm-1 early warning agent for early warning of steel corrosion -1 Corresponding to C=C bond vibration, 1607cm -1 Corresponding to CC vibration and CH out-of-plane bending vibration, 1504 cm -1 Corresponding to the CC vibration of the benzene ring, 1426 cm -1 Corresponding to the vibration of -COOH group, 1390 cm -1 Corresponding to methyl CH vibration, 1290 cm -1 Corresponding to CO stretching vibration, 546cm -1 The peak corresponding to Zn-O vibration; but the 1658cm -1 The peak corresponding to the CN bond vibration in 1,1-phenanthroline proves that the early warning agent 1,1-phenanthroline is successfully adsorbed and loaded into the porous MOF-5.

[0065] 30g of the prepared early warning agent was mixed with 100g of E-51 epoxy resin, and 50g of D400 curing agent was added. After mixing evenly, the mixture was coated on a Q235 steel test piece. After curing, the coating was scratched with a knife to simulate early corrosion conditions. After soaking in 3.5% NaCl solution, the effect was as follows: Figure 4 As shown in the figure, reddish discoloration patches appeared around the scratches on the test piece, proving that the early warning agent can produce visible color changes and provide corrosion warning when encountering early corrosion in the coating.

[0066] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, and all of these should be included in the scope of the claims of the present invention.

Claims

1. A warning agent for early warning of steel corrosion, characterized in that: The invention is prepared from the following raw materials in parts by weight: 160-200 parts of porous MOF-5 material; 30-50 parts of o-phenanthroline (Phen); and 2-3 parts of chitosan (CTS).

2. The early warning agent for early warning of steel corrosion according to claim 1, characterized in that: The MOF-5 porous material is synthesized by dissolving a zinc source in N-N dimethylformamide (DMF) to a concentration of 25-30 parts by weight, adding 70-75 parts of TPA, ultrasonically treating the solution and allowing the solution to stand. After the solution becomes clear, the precipitate is centrifuged, washed, and dried.

3. The early warning agent for early warning of steel corrosion according to claim 2, characterized in that: The zinc source material is zinc acetate dihydrate (Zn(AC)2·2H2O), zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc sulfate monohydrate (ZnSO4·H2O), zinc naphthenate ((C 11 H7O2)2·Zn) one or more.

4. The early warning agent for early warning of steel corrosion according to claim 1, characterized in that: In terms of microstructure, the porous MOF-5 material acts as a skeleton in the microparticles, and o-phenanthroline (Phen) is adsorbed and loaded in the gaps of the porous MOF-5 material. Chitosan is located in the outer layer, wrapping the porous MOF-5 material and o-phenanthroline (Phen) inside. The microstructure is a spherical structure with a diameter between 1-5μm.

5. The early warning agent for early warning of steel corrosion according to claim 1, characterized in that: The synthesis method of the early warning agent is as follows: ultrasonically dispersing the porous MOF-5 material in anhydrous ethanol, adding phenanthroline (Phen) and stirring to fully dissolve it, then performing vacuum treatment, centrifuging and washing the treated turbid liquid to obtain a precipitate, using deionized water to disperse the precipitate again, and then adding CTS acetic acid solution dropwise while stirring, maintaining the stirring state for a period of time, and centrifuging and washing the turbid liquid to dry it to obtain the early warning agent for steel corrosion warning.

6. The early warning agent for early warning of steel corrosion according to claim 5, characterized in that: The ultrasonic dispersion process lasts for 15 to 60 minutes.

7. The early warning agent for early warning of steel corrosion according to claim 5, characterized in that: The stirring speed of the stirring process is 1500-3000 rpm, and the stirring time is 30-60 min.

8. The early warning agent for early warning of steel corrosion according to claim 5, characterized in that: The vacuum degree of the vacuum treatment process is 0.09-0.1 MPa, and the vacuum treatment time is 1-5 days (d).

9. The early warning agent for early warning of steel corrosion according to claim 5, characterized in that: The drying temperature in the drying process is 60-100° C., and the drying time is 1-2 days.

10. A method for synthesizing an early warning agent for early warning of steel corrosion, characterized in that: The steps include: S1, take 25-30 parts by weight of zinc source material and dissolve it in NN dimethylformamide (DMF), the zinc source material is zinc acetate dihydrate (Zn(AC)2·2H2O), zinc nitrate hexahydrate (Zn(NO3)2·6H2O), zinc sulfate monohydrate (ZnSO4·H2O), zinc naphthenate ((C 11 H7O2)2·Zn) is added to one or more of the following: 70-75 parts by weight of TPA, and after ultrasonic treatment, the solution is allowed to stand. After the solution is clarified, the precipitate is centrifuged, washed, and dried to obtain a porous MOF-5 material; S2, ultrasonically dispersing the porous MOF-5 material obtained in S1 in anhydrous ethanol, adding o-phenanthroline (Phen) and stirring to fully dissolve it to obtain a suspension; S3, vacuum-treating the suspension obtained in S2, centrifuging and washing the treated turbid liquid to obtain a precipitate, and redispersing the precipitate with deionized water to obtain a turbid liquid; S4. Keep stirring the turbid liquid obtained in S3, add the acetic acid solution of CTS dropwise to the stirring liquid, keep stirring for a period of time, centrifuge the turbid liquid, wash and dry it, and obtain the early warning agent for early warning of steel corrosion.

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