Film coating agent for accelerating stabilization of weathering resistant steel rust layer in severe atmospheric environment and application method of film coating agent

Abstract

The invention discloses a film coating agent for accelerating stabilization of a weathering resistant steel rust layer in a severe atmospheric environment. The film coating agent comprises a film-forming agent and a spraying agent, the film-forming agent comprises a gel agent and a transforming agent; the gel is prepared from one or more of tannic acid, carbomer, chitosan and gelatin; the transforming agent comprises one or more of magnesium sulfate, zinc sulfate and sodium molybdate; the spraying agent comprises an accelerant and an aggressive agent; the accelerant comprises one or more of sodium sulfate, potassium sulfate and chromium sulfate; the aggressive agent comprises one or more of sodium chloride, aluminum chloride and sodium fluoride. The film coating agent provided by the invention can form a stable and uniform rust layer on the surface of the weathering resistant steel, so that the corrosion resistance of the weathering resistant steel is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of steel anticorrosion, and particularly relates to a coating agent and an application method for accelerating the stabilization of a weathering steel rust layer in a harsh atmospheric environment. Background Art

[0002] Compared with ordinary carbon steel, weathering steel can form a dense and well-bonded stable rust layer in the atmosphere. The rust layer can effectively prevent the corrosive medium from penetrating into the steel body and corroding the matrix. Therefore, weathering steel has excellent atmospheric corrosion resistance. However, the formation of a protective rust layer on the surface of weathering steel in a typical coastal atmospheric environment takes at least 3-5 years, or even cannot be formed. In addition, in the early stage of use, rust will flow and rust liquid will fly, which not only pollutes the environment, but also seriously affects the beauty of the building.

[0003] In order to solve the problems of slow growth and rust flow of weathering steel rust layer, researchers have carried out a lot of research work. At present, the stabilization treatment technology of weathering steel rust layer mainly includes weathering coating technology, oxide coating technology and the use of new treatment liquid technology, but there are still many shortcomings and disadvantages. For example: complex operation process, high cost of treatment agent, long construction period, not suitable for construction site, polluting environment, etc.

[0004] The Chinese application with publication number CN115354314A discloses "a rust layer stabilizing agent for weathering steel surface and its use method". The main components of the rust layer stabilizing agent for weathering steel include phosphoric acid, anhydrous copper sulfate, etc., which pollute the environment to a certain extent and violate the concept of environmental friendliness. The Japanese patent JP2001156254 discloses "a method for treating the surface of weathering steel", which can prevent the early rust liquid from flowing out. Although it does not pollute the environment, it requires three or more layers of treatment agent to be applied on the surface of weathering steel, and the operation process is complicated. The Chinese patent application with publication number CN111793394A discloses "a rust layer stabilizing agent for weathering steel surface and a method for treating the surface coating of weathering steel". The treatment agent component contains a phosphating agent, which will pollute the water body and does not conform to the concept of environmental friendliness. A Chinese patent application with publication number CN105568208A discloses "a method for surface treatment of weathering steel", in which the weathering steel is shot peened and then oxidized at 250-350°C for 1 to 4 hours. This method is cumbersome and complicated to operate, requires oxidation at a relatively high temperature, and is difficult to apply to actual on-site operations.

[0005] In addition, in addition to the above-mentioned shortcomings, the existing rust layer stabilization technology has the following problems. In actual engineering applications, after the rust layer stabilization treatment, most of the stabilizer on the weathering steel will flow to the bottom due to the influence of gravity, and finally the rust layer will have uneven thickness from top to bottom, which not only affects the appearance but also fails to form a uniform and stable rust layer, seriously affecting the later maintenance and promotion of weathering steel. Summary of the invention

[0006] The purpose of the present invention is to provide a coating agent and an application method thereof for accelerating the stabilization of the rust layer of weathering steel in a harsh atmospheric environment. The coating agent has a scientific ratio and is simple to prepare. It can effectively solve the technical problems of uneven and unstable rust layer and is environmentally friendly. The application method is simple and suitable for on-site environment and large-scale coastal industrial application.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A coating agent that accelerates the stabilization of a weathering steel rust layer in a harsh atmospheric environment, the coating agent comprising a film-forming agent and a spraying agent.

[0009] Furthermore, the film-forming agent of the present invention comprises a gelling agent and a conversion agent.

[0010] Furthermore, the gelling agent of the present invention comprises one or more of tannic acid, carbomer, chitosan and gelatin; and the converting agent comprises one or more of magnesium sulfate, zinc sulfate and sodium molybdate.

[0011] Furthermore, the mass concentration of tannic acid and carbomer in the gel of the present invention in the film-forming agent is 0.1-6 g / L; the mass concentration of chitosan in the gel in the film-forming agent is 0.1-3 g / L; the mass concentration of gelatin in the gel in the film-forming agent is 0.1-2 g / L.

[0012] Furthermore, the promoter of the present invention is composed of tannic acid, carbomer, chitosan and gelatin; the mass ratio of the tannic acid, carbomer, chitosan and gelatin is 1-4:1-4:1:1.

[0013] Furthermore, the mass concentration of magnesium sulfate and zinc sulfate in the conversion agent of the present invention in the film-forming agent is 0.1-6 g / L; the mass concentration of sodium molybdate in the conversion agent in the film-forming agent is 0.1-8 g / L.

[0014] Furthermore, the accelerator of the present invention is composed of magnesium sulfate, zinc sulfate and sodium molybdate; the mass ratio of the magnesium sulfate, zinc sulfate and sodium molybdate is 1-3:1-3:1-4.

[0015] Furthermore, the spraying agent of the present invention comprises an accelerator and an etchant.

[0016] Furthermore, the accelerator of the present invention comprises one or more of sodium sulfate, potassium sulfate and chromium sulfate; the etchant comprises one or more of sodium chloride, aluminum chloride and sodium fluoride.

[0017] Furthermore, the mass concentration of sodium sulfate, potassium sulfate and chromium sulfate in the accelerator of the present invention in the spraying agent is 0.1-5 g / L.

[0018] Furthermore, the accelerator of the present invention is composed of sodium sulfate, potassium sulfate and chromium sulfate; the mass ratio of the sodium sulfate, potassium sulfate and chromium sulfate is 1-2:1:1-2.

[0019] Furthermore, the mass concentration of sodium chloride, aluminum chloride and sodium fluoride in the etchant of the present invention in the spraying agent is 0.1-5 g / L.

[0020] Furthermore, the etching agent of the present invention is composed of sodium chloride, aluminum chloride and sodium fluoride; the mass ratio of the sodium chloride, aluminum chloride and sodium fluoride is 1-2:1-2:1.

[0021] The application method of the coating agent for accelerating the stabilization of the rust layer of weathering steel in a harsh atmospheric environment of the present invention comprises the following steps:

[0022] (1) Use sandpaper to pre-treat the surface of weathering steel to remove the oxide layer, clean it with anhydrous ethanol and blow it dry;

[0023] (2) preparing a film-forming agent; applying the prepared film-forming agent evenly on the surface of the weathering steel, and then leaving it to stand until the film-forming agent dries naturally and forms a 4-12 μm thick film layer on the surface of the weathering steel;

[0024] (3) Prepare a spray agent; use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel. After multiple cycles of treatment, a stable rust layer can be formed on the surface of the weathering steel.

[0025] Furthermore, in the application method of the coating agent of the present invention, the specific operation of the atomization wetting cycle treatment in step (3) is: setting the air pressure of the air compressor to 0.1-1.5 MPa, the solvent is a spray agent, the air compressor is connected to a spray gun, and after the solvent passes through the air compressor, atomized water vapor is formed at the outlet of the spray gun and then wets the surface of the weathering steel component. The outlet of the spray gun is 0.1-1.8 meters away from the surface of the weathering steel component, and the atomized water vapor is sprayed out to wet the surface of the rust layer, and the treatment is stopped when the surface of the rust layer is completely wetted; the treatment is performed once every 24 hours, and 5-7 cycles are performed.

[0026] The inventive principle of the technical solution of the present invention is:

[0027] The coating agent provided by the present invention comprises a film-forming agent and a spraying agent, wherein the film-forming agent comprises a gelling agent and a converting agent, and the spraying agent comprises an accelerator and an etchant, and the above components cooperate and work together in the process of accelerating the stabilization of the weathering steel rust layer.

[0028] The main function of the gelling agent is to make the coating agent in a relatively viscous gel state. Applying it evenly on the surface of weathering steel can prevent the coating agent from being deposited under the weathering steel sample due to gravity, which is conducive to the formation of a uniform protective film. In addition, the microscopic morphology of the formed protective film presents a dry riverbed shape. On the one hand, it can effectively prevent the corrosive ions from penetrating the rust layer and corroding the substrate; on the other hand, it can selectively penetrate oxygen and converters to promote the formation of stable phase substances (ɑ-FeOOH) in the rust layer. The converter is one or more of magnesium sulfate, zinc sulfate, and sodium molybdate; because the protective film can selectively penetrate the converter, the converter penetrates into the rust layer, participates in the process of the rust layer transforming from an unstable phase substance to a stable phase substance, and improves the corrosion resistance of the rust layer.

[0029] The accelerator is one or more of sodium sulfate, potassium sulfate and chromium sulfate. Sulfate provides sulfate radicals, and the addition of sulfate radicals can promote the formation of stable phase ɑ-FeOOH in weathering steel and promote the stabilization of the rust layer of weathering steel; the addition of cations can produce complex chelating reactions with gelling agents, which is helpful to repair and re-form the surface protective film. The corrosive agent is one or more of sodium chloride, aluminum chloride and sodium fluoride, which can promote the electrochemical reaction of the rust layer on the surface of weathering steel, provide a "bridge" for the electrochemical reaction, provide a fast channel for electron transfer, and make the corrosion products accumulate quickly. When used together with the accelerator, it can further promote the formation of relatively stable ɑ-FeOOH in weathering steel, make the rust layer denser, and form a physical barrier.

[0030] The advantages and beneficial technical effects of the technical solution of the present invention are:

[0031] The coating agent provided by the present invention does not contain any substance harmful to the environment and is environmentally friendly; in addition, the coating agent has a scientific composition ratio, a simple preparation method and low production cost.

[0032] The coating agent and application method provided by the present invention can not only accelerate the rapid formation of a stable rust layer on the surface of weathering steel and improve corrosion resistance, but also avoid the problem of the coating agent sprayed or applied on the surface of weathering steel flowing to the bottom due to gravity, forming an uneven rust layer.

[0033] The application method of the present invention has simple steps and can rapidly form a film on weathering steel at room temperature to generate a stable rust layer, which is suitable for on-site construction and large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the macroscopic morphology of weathering steel after being treated with the coating agent described in Example 1.

[0035] Figure 2 This is the macroscopic morphology of weathering steel after treatment with the coating agent described in Example 2.

[0036] Figure 3This is the macroscopic morphology of weathering steel after treatment with the coating agent described in Example 3.

[0037] Figure 4 This is the macroscopic morphology of weathering steel after treatment with the coating agent described in Example 5.

[0038] Figure 5 This is the macroscopic morphology of weathering steel after treatment with the coating agent described in Example 7.

[0039] Figure 6 This is a Tafel plot of weathering steel treated with the coating agent described in Example 6 and untreated weathering steel placed in 3.5wt.% NaCl solution respectively.

[0040] Figure 7 These are AC impedance spectra of weathering steel treated with the coating agent described in Example 6 and untreated weathering steel placed in 3.5 wt.% NaCl solution respectively. DETAILED DESCRIPTION

[0041] The technical solution of the present invention is further described in detail below through embodiments.

[0042] Example 1

[0043] Taking weather-resistant structural steel Q355NH as the substrate, a coating agent is used to stabilize the rust layer on its surface. The coating agent includes a film-forming agent and a spraying agent. The specific treatment steps are as follows:

[0044] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0045] (2) Prepare a film-forming agent, wherein the film-forming agent is prepared from tannic acid, carbomer, gelatin, sodium molybdate and deionized water; wherein the mass concentrations of tannic acid, carbomer and gelatin in the film-forming agent are 4 g / L, 4 g / L and 2 g / L respectively, and the mass concentration of sodium molybdate in the film-forming agent is 2 g / L. Evenly apply the prepared film-forming agent to the surface of the weathering steel component pretreated in step (1), and then let it stand until the film-forming agent is naturally dried; after measurement, the thickness of the dried film layer is 4 μm.

[0046] (3) Prepare a spray agent, which is prepared from sodium sulfate, chromium sulfate, sodium chloride, sodium fluoride and deionized water; the mass concentrations of sodium sulfate and chromium sulfate in the spray agent are both 2g / L, and the mass concentrations of sodium chloride and sodium fluoride in the spray agent are 4g / L and 2g / L respectively. Use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel component with the prepared spray agent. Set the air pressure of the air compressor to 0.1Mpa, and the distance between the spray gun outlet and the surface of the weathering steel component is 0.1m. Take 24 hours as one cycle, and perform 5 cycles.

[0047] After the cycle treatment, a stable and uniform rust layer is formed on the surface of the weathering steel component, and the macroscopic morphology of the rust layer is relatively beautiful, such as Figure 1 shown.

[0048] Example 2

[0049] Taking weather-resistant structural steel Q355NH as the substrate, a coating agent is used to stabilize the rust layer on its surface. The coating agent includes a film-forming agent and a spraying agent. The specific treatment steps are as follows:

[0050] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0051] (2) Prepare a film-forming agent, wherein the film-forming agent is prepared from chitosan, zinc sulfate and deionized water; wherein the mass concentration of chitosan in the film-forming agent is 3 g / L, and the mass concentration of zinc sulfate in the film-forming agent is 5 g / L. The prepared film-forming agent is evenly applied to the surface of the weathering steel component pretreated in step (1), and then allowed to stand until the film-forming agent is naturally dried; after measurement, the thickness of the dried film layer is 7 μm.

[0052] (3) Prepare a spray agent, which is prepared from sodium sulfate, sodium fluoride and deionized water; the mass concentration of sodium sulfate in the spray agent is 0.1g / L, and the mass concentration of sodium fluoride in the spray agent is 5g / L. Use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel component with the prepared spray agent. Set the air pressure of the air compressor to 1.2Mpa, and the distance between the spray gun outlet and the surface of the weathering steel component is 1.5m. Take 24 hours as one cycle, and perform 6 cycles.

[0053] After the cycle treatment, a stable and uniform rust layer is formed on the surface of the weathering steel component, and the macroscopic morphology of the rust layer is more beautiful, such as Figure 2 shown.

[0054] Example 3

[0055] Taking weather-resistant structural steel Q355NH as the substrate, a coating agent is used to stabilize the rust layer on its surface. The coating agent includes a film-forming agent and a spraying agent. The specific treatment steps are as follows:

[0056] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0057] (2) Prepare a film-forming agent, which is prepared from 2g of tannic acid, 2g of carbomer, magnesium sulfate and deionized water; wherein the mass concentration of tannic acid in the film-forming agent is 2g / L, the mass concentration of carbomer in the film-forming agent is 2g / L, and the mass concentration of magnesium sulfate in the film-forming agent is 4g / L. The prepared film-forming agent is evenly applied to the surface of the weathering steel component pretreated in step (1), and then allowed to stand until the film-forming agent is naturally dried; after measurement, the thickness of the dried film layer is 12μm.

[0058] (3) Prepare a spray agent, which is prepared from potassium sulfate, aluminum chloride and deionized water; the mass concentration of potassium sulfate in the spray agent is 5g / L, and the mass concentration of aluminum chloride in the spray agent is 0.1g / L. Use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel component with the prepared spray agent. Set the air pressure of the air compressor to 1.5Mpa, and the distance between the spray gun outlet and the surface of the weathering steel component is 0.5m. Take 24 hours as one cycle, and perform 5 cycles.

[0059] After the cycle treatment, a stable and uniform rust layer is formed on the surface of the weathering steel component, and the macroscopic morphology of the rust layer is more beautiful, such as Figure 3 shown.

[0060] Example 4

[0061] Taking weather-resistant structural steel Q355NH as the substrate, a coating agent is used to stabilize the rust layer on its surface. The coating agent includes a film-forming agent and a spraying agent. The specific treatment steps are as follows:

[0062] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0063] (2) Prepare a film-forming agent, which is prepared from tannic acid, carbomer, chitosan, gelatin, magnesium sulfate, sodium molybdate and deionized water; wherein the mass concentrations of tannic acid, carbomer, chitosan and gelatin in the film-forming agent are 4 g / L, 4 g / L, 2 g / L and 2 g / L respectively, and the mass concentrations of magnesium sulfate and sodium molybdate in the film-forming agent are both 5 g / L. Evenly apply the prepared film-forming agent on the surface of the weathering steel component pretreated in step (1), and then let it stand until the film-forming agent is naturally dried; after measurement, the thickness of the dried film layer is 8 μm.

[0064] (3) Prepare a spray agent, which is prepared from chromium sulfate, sodium chloride and deionized water; the mass concentration of chromium sulfate in the spray agent is 0.1g / L, and the mass concentration of sodium chloride in the spray agent is 0.1g / L. Use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel component. Set the air pressure of the air compressor to 0.5Mpa, and the distance between the spray gun outlet and the surface of the weathering steel component is 1.8m. Take 24 hours as one cycle, and perform 6 cycles.

[0065] After the cyclic treatment, a stable and uniform rust layer is formed on the surface of the weathering steel components, and the macroscopic morphology of the rust layer is more beautiful.

[0066] Example 5

[0067] Taking weather-resistant structural steel Q355NH as the substrate, a coating agent is used to stabilize the rust layer on its surface. The coating agent includes a film-forming agent and a spraying agent. The specific treatment steps are as follows:

[0068] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0069] (2) Prepare a film-forming agent, which is prepared from tannic acid, carbomer, chitosan, gelatin, magnesium sulfate, zinc sulfate, sodium molybdate and deionized water; wherein the mass concentrations of tannic acid, carbomer, chitosan and gelatin in the film-forming agent are all 0.1 g / L, and the mass concentrations of magnesium sulfate, zinc sulfate and sodium molybdate in the film-forming agent are 0.1 g / L, 0.1 g / L and 0.1 g / L respectively. Apply the prepared film-forming agent evenly on the surface of the weathering steel component pretreated in step (1), and then let it stand until the film-forming agent is naturally dried; after measurement, the thickness of the dried film layer is 10 μm.

[0070] (3) Prepare a spray agent, which is prepared from potassium sulfate, chromium sulfate, sodium fluoride and deionized water; the mass concentrations of potassium sulfate and chromium sulfate in the spray agent are both 0.1 g / L, and the mass concentration of sodium fluoride in the spray agent is 0.1 g / L. Use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel component with the prepared spray agent. Set the air pressure of the air compressor to 0.4 MPa, and the distance between the spray gun outlet and the surface of the weathering steel component is 0.8 m. Take 24 hours as one cycle, and perform 7 cycles.

[0071] After the cycle treatment, a stable and uniform rust layer is formed on the surface of the weathering steel component, and the macroscopic morphology of the rust layer is more beautiful, such as Figure 4 shown.

[0072] Example 6

[0073] Taking weather-resistant structural steel Q355NH as the substrate, a coating agent is used to stabilize the rust layer on its surface. The coating agent includes a film-forming agent and a spraying agent. The specific treatment steps are as follows:

[0074] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0075] (2) Prepare a film-forming agent, which is prepared from tannic acid, carbomer, gelatin, magnesium sulfate, zinc sulfate and deionized water; wherein the mass concentrations of tannic acid, carbomer and gelatin in the film-forming agent are 4 g / L, 4 g / L and 1 g / L, respectively, and the mass concentrations of magnesium sulfate and zinc sulfate in the film-forming agent are 3 g / L and 2 g / L, respectively. Evenly apply the prepared film-forming agent to the surface of the weathering steel component pretreated in step (1), and then let it stand until the film-forming agent is naturally dried; after measurement, the thickness of the dried film layer is 10 μm.

[0076] (3) Prepare a spray agent, which is prepared from sodium sulfate, chromium sulfate, sodium chloride, sodium fluoride and deionized water; the mass concentrations of sodium sulfate and chromium sulfate in the spray agent are both 5g / L, and the mass concentrations of sodium chloride and sodium fluoride in the spray agent are 4g / L and 2g / L respectively. Use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel component with the prepared spray agent. Set the air pressure of the air compressor to 0.2Mpa, and the distance between the spray gun outlet and the surface of the weathering steel component is 0.9m. Take 24 hours as one cycle, and perform 7 cycles.

[0077] After the cyclic treatment, a stable and uniform rust layer is formed on the surface of the weathering steel components, and the macroscopic morphology of the rust layer is more beautiful.

[0078] Example 7

[0079] Taking weather-resistant structural steel Q355NH as the substrate, a coating agent is used to stabilize the rust layer on its surface. The coating agent includes a film-forming agent and a spraying agent. The specific treatment steps are as follows:

[0080] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0081] (2) Prepare a film-forming agent, which is prepared from tannic acid, carbomer, chitosan, gelatin, magnesium sulfate, zinc sulfate, sodium molybdate and deionized water; wherein the mass concentrations of tannic acid, carbomer, chitosan and gelatin in the film-forming agent are 6g / L, 6g / L, 1.5g / L and 1.5g / L, respectively, and the mass concentrations of magnesium sulfate, zinc sulfate and sodium molybdate in the film-forming agent are 6g / L, 6g / L and 8g / L, respectively. Apply the prepared film-forming agent evenly on the surface of the weathering steel component pretreated in step (1), and then let it stand until the film-forming agent is naturally dried; after measurement, the thickness of the dried film layer is 10μm.

[0082] (3) Prepare a spray agent, which is prepared from sodium sulfate, potassium sulfate, chromium sulfate, sodium chloride, aluminum chloride, sodium fluoride and deionized water; the mass concentrations of sodium sulfate, potassium sulfate and chromium sulfate in the spray agent are 2g / L, 1g / L and 2g / L respectively, and the mass concentrations of sodium chloride, aluminum chloride and sodium fluoride in the spray agent are 5g / L, 5g / L and 2.5g / L respectively. Use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel component with the prepared spray agent, set the air pressure of the air compressor to 0.4Mpa, and the distance between the spray gun outlet and the surface of the weathering steel component is 1.3m. Take 24 hours as one cycle, and perform 7 cycles.

[0083] After the cycle treatment, a stable and uniform rust layer is formed on the surface of the weathering steel component, and the macroscopic morphology of the rust layer is relatively beautiful, such as Figure 5 shown.

[0084] Comparative Example 1

[0085] Taking weather-resistant structural steel Q355NH as the matrix, a film-forming agent is used to stabilize the rust layer on its surface. The specific treatment steps are as follows:

[0086] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0087] (2) Prepare a film-forming agent, which is prepared from tannic acid, carbomer, gelatin, magnesium sulfate, zinc sulfate and deionized water; wherein the mass concentration of tannic acid, carbomer and gelatin in the film-forming agent is 1 g / L, and the mass concentration of magnesium sulfate and zinc sulfate in the film-forming agent is 3 g / L and 2 g / L respectively. Apply the prepared film-forming agent evenly on the surface of the weathering steel component pretreated in step (1), and then let it stand until the film-forming agent is naturally dried; after measurement, the thickness of the dried film layer is 5 μm.

[0088] After treatment, there is a small amount of rust on the surface of the weathering steel.

[0089] Comparative Example 2

[0090] Taking weather-resistant structural steel Q355NH as the substrate, the rust layer on its surface is stabilized by spraying agent. The specific treatment steps are as follows:

[0091] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0092] (3) Prepare a spray agent, which is prepared from chromium sulfate, sodium chloride, aluminum chloride, sodium fluoride and deionized water; the mass concentration of chromium sulfate in the spray agent is 2g / L, and the mass concentrations of sodium chloride, aluminum chloride and sodium fluoride in the spray agent are 6g / L, 6g / L and 3g / L respectively. Use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel component with the prepared spray agent. Set the air pressure of the air compressor to 0.4Mpa, the distance between the spray gun outlet and the surface of the weathering steel component is 1.3m, and treat for 7 cycles with 24 hours as one cycle.

[0093] After treatment, the rust layer on the surface of the weathering steel components is uneven and the macroscopic appearance is not beautiful.

[0094] Comparative Example 3

[0095] Taking weather-resistant structural steel Q355NH as the substrate, a coating agent is used to stabilize the rust layer on its surface. The coating agent includes a film-forming agent and a spraying agent. The specific treatment steps are as follows:

[0096] (1) The weather-resistant structural steel Q355NH was processed into a size of 10 mm × 10 mm × 4 mm, and its surface was pretreated with sandpaper to remove the oxide layer. It was cleaned with anhydrous ethanol and then blown dry.

[0097] (2) Prepare a film-forming agent, which is prepared from tannic acid, carbomer, gelatin, magnesium sulfate, sodium molybdate and deionized water; wherein the mass concentrations of tannic acid, carbomer and gelatin in the film-forming agent are 4 g / L, 4 g / L and 1 g / L respectively, and the mass concentrations of magnesium sulfate and sodium molybdate in the film-forming agent are both 8 g / L. Evenly apply the prepared film-forming agent on the surface of the weathering steel component pretreated in step (1), and then let it stand until the film-forming agent is naturally dried; after measurement, the thickness of the dried film layer is 13 μm.

[0098] (3) Prepare a spray agent, which is prepared from sodium sulfate, potassium sulfate, chromium sulfate, sodium chloride, aluminum chloride, sodium fluoride and deionized water; the mass concentration of sodium sulfate, potassium sulfate and chromium sulfate in the spray agent is 5g / L, and the mass concentration of sodium chloride, aluminum chloride and sodium fluoride in the spray agent is 5g / L. Use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel component with the prepared spray agent. Set the air pressure of the air compressor to 1.5Mpa, and the outlet of the spray gun is 2m away from the surface of the weathering steel component. Take 24 hours as one cycle, and perform 4 cycles.

[0099] After the cyclic treatment, a stable and uniform rust layer is formed on the surface of the weathering steel component, but the rust layer is uneven and the macroscopic appearance is not beautiful.

[0100] The colors and uniformity of the rust layers formed in Examples 1-7 and Comparative Examples 1-3 were summarized, and the results are shown in Table 1.

[0101] The rusted specimens treated in Examples 1-7 and Comparative Examples 1-3 were subjected to a laboratory accelerated corrosion test, i.e., periodic immersion, and the corrosion rates were measured.

[0102] Cyclic infiltration test method: using 3.5wt.% NaCl solution, the experimental temperature is 25℃, each cycle is 40min, including immersion for 5min and drying for 35min, and the experimental cycle is 30 times; the corrosion rate of the sample after the cyclic infiltration test is calculated according to the method described in GB / T14165-1993: "Ferrous Metal Outdoor Atmospheric Exposure Test Method", and the calculation formula is as follows.

[0103]

[0104] In the formula, V represents the corrosion rate in g / m 2 h; m1 represents the mass of the sample before the test, in g; m2 represents the mass of the sample after the test, in g; A represents the surface area of ​​the sample, in m 2 ; t represents the test duration, in hours.

[0105] The results of the periodic infiltration tests of the samples of the embodiments and comparative examples are shown in Table 1.

[0106] Table 1 Evaluation results of rust layer performance of each embodiment and comparative example Q355NH

[0107]

[0108]

[0109] Through comparison, it was found that the weathering steel treated with the coating agent provided by the present invention had a lower corrosion rate and a more uniform rust layer than the weathering steel treated with the coating agent provided in the comparative example, which can effectively alleviate the phenomenon of uneven rust layer caused by the sprayed treatment agent flowing to the bottom due to gravity.

[0110] Comparative Example 1 uses only a film-forming agent to treat weathering steel, and the rust layer formed is uneven and incomplete; Comparative Example 2 uses only a spraying agent to treat weathering steel, and the rust liquid flows to the bottom, and the rust layer formed is uneven and incomplete; Comparative Example 3 uses a film-forming agent with a large mass concentration of the conversion agent magnesium sulfate, the spray gun outlet is far away from the surface of the weathering steel component, the treatment cycle is short, and the film layer formed is thicker, which affects the treatment effect of the weathering steel. The rust layer formed on the surface of the weathering steel component is uneven, and the macroscopic morphology is not beautiful. Compared with the coating agent provided by the present invention, the corrosion rate of the weathering steel after the three comparative examples are significantly increased.

[0111] The present invention also uses a CHI660E electrochemical workstation, using the weathering steel treated with the coating agent in Example 6 and bare steel as working electrodes, a saturated calomel electrode as a reference electrode, and a platinum electrode as an auxiliary electrode to conduct an electrochemical performance comparison test on the treated weathering steel (weathering steel treated with the coating agent in Example 6) and bare steel. During the test, a three-electrode system was used, and a NaCl solution with a mass percentage concentration of 3.5% was used as the electrolyte. The effective detection area was 1 cm 2 The stabilization time is 10 min, the measurement is carried out under open circuit potential, and the measurement frequency range is 0.01~1.00×10 5 Hz, the measured signal is a sine wave with an amplitude of 10mV, and the Tafel curve obtained by the test is as follows Figure 6 To further analyze the dynamics of the polarization curve, Figure 6 The polarization curve data are extrapolated to calculate the kinetic parameters: self-corrosion potential (Ecorr) and self-corrosion current density (Icorr). It is generally believed that the more positive the Ecorr is and the smaller the Icorr is, the lower the corrosion rate of the sample being tested. Figure 6 It can be seen that the Icorr of the weathering steel after the stabilization treatment in Example 6 is reduced, and the Ecorr is positively shifted, indicating that the corrosion resistance of the weathering steel after the stabilization treatment by the method of the present invention is improved.

[0112] The AC impedance spectrum obtained by the test is as follows Figure 7As shown, the rust layer resistance can be determined from the diameter of the capacitive reactance arc in the high frequency band. The results show that after being treated with the treatment solution of Example 6, the rust layer resistance of the weathering steel is significantly greater than that of the bare steel, indicating that the polarization resistance increases when the corrosion reaction occurs.

[0113] The weathering steel treated with the coating agent of the present invention can effectively inhibit the corrosion of the weathering steel substrate by the corrosive medium, thereby significantly improving the corrosion resistance of the weathering steel. The coating agent provided by the present invention is further used to perform rust layer stabilization treatment on different types of weathering steel. The obtained experimental results can show that the coating agent of the present invention can significantly accelerate the stabilization of the rust layer of weathering steel in coastal environments, and can effectively alleviate the phenomenon of uneven rust layer caused by the sprayed treatment agent flowing to the bottom due to gravity.

[0114] In summary, it can be seen that the coating agent provided by the present invention has a scientific composition ratio, a simple preparation method, low production cost, and is environmentally friendly; the operating process steps are simple, and the film is formed quickly at room temperature, and a stable rust layer can be quickly generated, which is suitable for on-site construction and large-scale industrial applications; the coating agent and the application method can not only accelerate the rapid formation of a stable rust layer on the surface of weathering steel and improve corrosion resistance, but also avoid the problem of the treatment agent sprayed or applied on the surface of the weathering steel flowing to the bottom due to gravity to form an uneven rust layer.

Claims

1. A coating agent that accelerates the stabilization of the rust layer of weathering steel in a harsh atmospheric environment, characterized in that: The coating agent comprises a film-forming agent and a spraying agent; The film-forming agent comprises a gelling agent and a conversion agent; the gelling agent comprises one or more of tannic acid, carbomer, chitosan, and gelatin; the conversion agent comprises one or more of magnesium sulfate, zinc sulfate, and sodium molybdate; The spraying agent comprises an accelerator and an etchant; the accelerator comprises one or more of sodium sulfate, potassium sulfate and chromium sulfate; the etchant comprises one or more of sodium chloride, aluminum chloride and sodium fluoride.

2. The coating agent according to claim 1, which accelerates the stabilization of the rust layer of weathering steel in a harsh atmospheric environment, is characterized in that: The mass concentration of tannic acid and carbomer in the gel is 0.1-6 g / L in the film-forming agent; the mass concentration of chitosan in the gel is 0.1-3 g / L in the film-forming agent; and the mass concentration of gelatin in the gel is 0.1-2 g / L in the film-forming agent.

3. The coating agent according to claim 1, characterized in that: The gelling agent is composed of tannic acid, carbomer, chitosan and gelatin; the mass ratio of the tannic acid, carbomer, chitosan and gelatin is 1-4:1-4:1:

1.

4. The coating agent according to claim 1, characterized in that: The mass concentration of magnesium sulfate and zinc sulfate in the conversion agent in the film-forming agent is 0.1-6 g / L; the mass concentration of sodium molybdate in the conversion agent in the film-forming agent is 0.1-8 g / L.

5. The coating agent according to claim 1, characterized in that: The conversion agent consists of magnesium sulfate, zinc sulfate and sodium molybdate; the mass ratio of the magnesium sulfate, zinc sulfate and sodium molybdate is 1-3:1-3:1-4.

6. The coating agent according to claim 1, characterized in that: The mass concentration of the sodium sulfate, potassium sulfate and chromium sulfate in the accelerator in the spraying agent is 0.1-5 g / L.

7. The coating agent according to claim 1, characterized in that: The accelerator consists of sodium sulfate, potassium sulfate and chromium sulfate; the mass ratio of the sodium sulfate, potassium sulfate and chromium sulfate is 1-2:1:1-2.

8. The coating agent according to claim 1, characterized in that: The mass concentration of sodium chloride, aluminum chloride and sodium fluoride in the etchant in the spraying agent is 0.1-5 g / L.

9. The coating agent according to claim 1, characterized in that: The etching agent is composed of sodium chloride, aluminum chloride and sodium fluoride; the mass ratio of the sodium chloride, aluminum chloride and sodium fluoride is 1-2:1-2:

1.

10. The method for applying the coating agent for accelerating the stabilization of the rust layer of weathering steel in a harsh atmospheric environment according to claim 1, characterized in that: The steps include: (1) Use sandpaper to pre-treat the surface of weathering steel to remove the oxide layer, clean it with anhydrous ethanol and blow it dry; (2) Prepare a film-forming agent; evenly apply the prepared film-forming agent on the surface of the weathering steel, and then let it stand until the film-forming agent dries naturally and forms a 4-12 μm thick film layer on the surface of the weathering steel; (3) Prepare the spray agent; use a spray gun to perform atomization and wetting cycle treatment on the surface of the weathering steel. After multiple cycles of treatment, a stable rust layer can be formed on the surface of the weathering steel.

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