Weathering-resistant steel surface treating agent and using method thereof

Abstract

The invention relates to a weathering steel surface treating agent and a using method thereof, and belongs to the technical field of corrosion prevention of steel and iron materials. The surface treating agent is prepared from the following components in parts by mass: 30 to 50 parts of water-soluble acrylic resin, 1 to 10 parts of alpha-FeOOH, 5 to 15 parts of gamma-FeOOH, 1 to 10 parts of Fe2O3, 0.5 to 3 parts of NaCl, 0.01 to 0.1 part of a de-foaming agent and 0.01 to 0.1 part of a wetting agent. The water-soluble acrylic resin in the surface treating agent is a film forming main body, alpha-FeOOH and gamma-FeOOH can promote generation of alpha-FeOOH in a weathering resistant steel rust layer and shorten the stabilization process of the rust layer, Fe2O3 plays a color matching role and can ensure that the appearance of the surface treating agent is close to the color of the weathering resistant steel stable rust layer, NaCl is an inducer, the initial corrosion speed of weathering resistant steel can be increased, and the corrosion resistance of the weathering resistant steel is improved. Phase transformation in a rust layer is promoted. The surface treating agent is scientific in proportion, and when the surface treating agent is coated on the surface of the weathering resistant steel, conversion from an unstable phase to a stable phase in a rust layer is accelerated, so that generation of the stable rust layer is promoted, and the corrosion resistance of the weathering resistant steel is improved.

Description

Technical Field

[0001] This application relates to the technical field of anti-corrosion of steel materials, and particularly relates to a weathering steel surface treatment agent and a method for using the same. Background Art

[0002] Weathering steel can form a dense protective rust layer on its surface in the atmospheric environment, and can replace the use plan of carbon steel + organic coating in the traditional steel structure field, thus avoiding the use of a large amount of organic coatings and the later maintenance costs, and having good economic and social benefits. Therefore, the non-painting of weathering steel has been widely used in fields such as bridges, power towers, and buildings. However, in the natural state, it takes about 10 years for a stable rust layer to form on the surface of the exposed weathering steel, and the directly exposed weathering steel usually shows phenomena such as uneven color and rust liquid dripping in the initial stage, resulting in uneven appearance color and environmental pollution. In addition, in some environments with too high Cl - and SO2 content, it is difficult to form a stable rust layer on the surface of weathering steel, and weathering steel must be painted when used in these areas, which increases the use cost and later maintenance costs.

[0003] To solve the above problems caused by the direct use of weathering steel, relevant research has been carried out at home and abroad. Abroad, weather resistance coating technology, oxide coating technology, and rusted coating N treatment, as well as new surface treatment agents (that is, adding a certain amount of chromium sulfate to polyvinyl butyral resin to make a surface composite treatment agent, directly coating 15-20 μm thick on the surface of atmospheric corrosion-resistant steel, and the interface between the coating and the steel reacts to generate a stable rust layer on the steel surface in a short time) have been formed. In addition, the newly developed CUPTEN COAT M surface treatment technology recently can promote the formation of a stable rust layer in a high-salt atmosphere environment and avoid the phenomenon of rust liquid dripping. At present, many domestic scientific research institutions are also conducting research on the technology for stabilizing the rust layer on the surface of weathering steel, but no relatively mature treatment technology widely used for stabilizing the rust layer on the surface of weathering steel components has been developed.

[0004] A patent for invention discloses a solution for stabilizing the rust layer of weathering steel and a treatment method. Its main components include NaCl, Cr2(SO4)3, H2SO4, Fe2O3, etc. This composition contains harmful metals such as Cr2(SO4)3 and strong acid H2SO4, which affect the safety of construction workers and pollute the environment. A patent for invention discloses a treatment agent for stabilizing the rust layer of hot-rolled weathering steel, which is divided into a pretreatment component A and a post-treatment component B. Among them, A is pickling waste liquid with a pH value of 1-5, and B is a mixed solution of K2Cr2O7, Sb(NO3)3, and SnSO4. This composition also contains heavy metals such as Cr and strong acid, which are not friendly to construction and the surrounding environment. A patent for invention discloses a pretreatment solution and a pretreatment method for stabilizing the rust layer on the surface of weathering steel in an industrial atmospheric environment. The main components of this treatment solution include Cr2(SO4)3, FeSO4, CuSO4, NaHSO3, NiSO4, and water. This solution also contains heavy metals such as Cr, and the pretreatment method of weathering steel requires spraying and wetting-drying about 6 times. For large components, the drying time is too long and the operation is complex. Summary of the Invention

[0005] The present application provides a surface treatment agent for weathering steel and its use method to solve the following technical problem: how to improve the corrosion resistance of weathering steel.

[0006] In the first aspect, the present application provides a surface treatment agent for weathering steel, and the surface treatment agent includes: water-soluble acrylic resin, α-FeOOH, γ-FeOOH, Fe2O3, NaCl, defoaming agent, wetting agent, and solvent.

[0007] Optionally, by mass, the surface treatment agent includes: water-soluble acrylic resin: 30 parts to 50 parts, α-FeOOH: 1 part to 10 parts, γ-FeOOH: 5 parts to 15 parts, Fe2O3: 1 part to 10 parts, NaCl: 0.5 part to 3 parts, defoaming agent: 0.01 part to 0.1 part, wetting agent: 0.01 part to 0.1 part.

[0008] Optionally, the defoaming agent is an organosilicon defoaming agent.

[0009] Optionally, the wetting agent is an organosilicon wetting agent.

[0010] Optionally, the solvent is water.

[0011] In the second aspect, the present application provides a use method of the surface treatment agent for weathering steel described in the first aspect, and the method includes:

[0012] Mix the water-soluble acrylic resin and the solvent and stir to obtain a mixed solution;

[0013] Add α-FeOOH, γ-FeOOH, Fe2O3, NaCl, defoamer and wetting agent to the above-mentioned mixed solution in sequence to obtain the weathering steel surface treatment agent;

[0014] Pretreat the weathering steel to remove the surface scale;

[0015] Coat the weathering steel surface treatment agent on the surface of the weathering steel to obtain coated steel;

[0016] Dry the coated steel.

[0017] Optionally, the pretreatment method is any one of sandblasting and shot peening.

[0018] Optionally, the coating method is any one of brushing and spraying.

[0019] Optionally, the drying temperature is room temperature, and the drying time ≥ 24h.

[0020] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0021] The present application provides a weathering steel surface treatment agent. In terms of mass parts, the surface treatment agent includes: water-soluble acrylic resin: 30 parts - 50 parts, α-FeOOH: 1 part - 10 parts, γ-FeOOH: 5 parts - 15 parts, Fe2O3: 1 part - 10 parts, NaCl: 0.5 parts - 3 parts, defoamer: 0.01 parts - 0.1 parts, wetting agent: 0.01 parts - 0.1 parts. The water-soluble acrylic resin in the surface treatment agent is the film-forming main body. α-FeOOH and γ-FeOOH can promote the formation of α-FeOOH in the rust layer of weathering steel, shorten the rust layer stabilization process, Fe2O3 plays a color adjustment role, which can ensure that the appearance of the surface treatment agent is similar to the color of the stable rust layer of weathering steel, and NaCl is an inducer, which can accelerate the initial corrosion rate of weathering steel and promote the phase transformation in the rust layer. The surface treatment agent has a scientific ratio. Coating it on the surface of weathering steel accelerates the transformation from unstable phase to stable phase in the rust layer, thereby promoting the formation of a stable rust layer and improving the corrosion resistance of weathering steel. Description of the Drawings

[0022] The drawings here are incorporated into the specification and constitute a part of this specification, showing the embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0024] Figure 1 It is a schematic flow chart of a method for using a weathering steel surface treatment agent provided by an embodiment of the present application;

[0025] Figure 2 It is a macroscopic morphology diagram of weathering steel after being coated with the surface treatment agent provided by an embodiment of the present application;

[0026] Figure 3 It is a corrosion rate diagram of the bare steel sample and the surface-treated sample of weathering steel provided by an embodiment of the present application;

[0027] Figure 4 It is a distribution diagram of alloy elements in the rust layer of the surface-treated weathering steel sample provided by an embodiment of the present application. Detailed implementation manners

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0029] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and single values within that range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within that range, such as 1, 2, 3, 4, 5, and 6, regardless of the range; additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0030] In this text, terms such as "including" mean "including but not limited to". Relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the associated relationship of associated objects and indicates that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "a plurality" means two or more; "at least one kind", "at least one of the following items (pieces)" or similar expressions refer to any combination of these items, including any combination of single items (pieces) or plural items (pieces); for example, "at least one of a, b, or c", or "at least one of a, b, and c" can both represent: a, b, c, a-b (that is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or plural respectively. Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in this application can be obtained through market purchases or can be prepared by existing methods.

[0031] In a first aspect, the present application provides a weathering steel surface treatment agent, and the surface treatment agent includes: water-soluble acrylic resin, α-FeOOH, γ-FeOOH, Fe2O3, NaCl, defoaming agent, wetting agent, and solvent.

[0032] In some embodiments, by mass, the surface treatment agent includes: water-soluble acrylic resin: 30 parts to 50 parts, α-FeOOH: 1 part to 10 parts, γ-FeOOH: 5 parts to 15 parts, Fe2O3: 1 part to 10 parts, NaCl: 0.5 part to 3 parts, defoaming agent: 0.01 part to 0.1 part, wetting agent: 0.01 part to 0.1 part.

[0033] The positive effect of limiting the mass of the water-soluble acrylic resin to 30 parts to 50 parts: The water-soluble acrylic resin is the main film-forming substance of the treatment agent and has good film-forming properties. The mass of 30 parts to 50 parts helps to form a continuous, dense and protective film with a certain thickness. This protective film can effectively isolate the corrosive medium in the external environment and protect the weathering steel substrate from erosion. In addition, as the main body of the surface treatment agent, the water-soluble acrylic resin can make the added pigments more fully dispersed. If the mass is higher than the above range, the fluidity of the treatment agent will be reduced, which is not conducive to coating. If the mass is lower than the above range, the dispersibility of the pigment and filler will be reduced. Exemplarily, the mass of the water-soluble acrylic resin can be 30 parts, 34 parts, 38 parts, 42 parts, 46 parts, 50 parts, etc.

[0034] Positive effects of limiting the mass fraction of α-FeOOH to 1 part to 10 parts: α-FeOOH, also known as goethite, is an important component in the rust layer on the surface of weathering steel. It can gradually stabilize and form a protective rust layer during long-term atmospheric corrosion. A stable α-FeOOH rust layer can more effectively isolate corrosive media in the external environment, such as moisture, oxygen, and chloride ions, thereby slowing down the corrosion rate of weathering steel and extending its service life. An α-FeOOH content of 1 part to 10 parts by mass helps promote the transformation of other unstable components (such as γ-FeOOH) in the rust layer into more stable α-FeOOH, thereby improving the overall stability and protection of the rust layer. If the mass fraction is higher than the above range, the cost will increase and the economy of the surface treatment agent will be reduced. If the mass fraction is lower than the above range, the effect on shortening the rust layer stabilization process is not obvious. In addition, as a mineral component existing in nature, the use of α-FeOOH meets environmental protection requirements. Appropriately adding α-FeOOH to the surface treatment agent helps reduce the emission of harmful substances and reduce environmental pollution. Exemplarily, the mass fraction of α-FeOOH can be 1 part, 3 parts, 5 parts, 7 parts, 9 parts, 10 parts, etc.

[0035] Positive effects of limiting the mass fraction of γ-FeOOH to 5 parts to 15 parts: γ-FeOOH, also known as lepidocrocite, the transformation of the rust layer usually involves multiple chemical and electrochemical processes, including dissolution, reprecipitation, redox reactions, etc. In these processes, the presence of γ-FeOOH can act as a catalyst or reaction intermediate to accelerate the transformation of unstable components, thereby promoting the formation of a stable rust layer. If the mass fraction is higher than the above range, the cost will increase. If the mass fraction is lower than the above range, the transformation effect is not obvious. Exemplarily, the mass fraction of γ-FeOOH can be 5 parts, 8 parts, 11 parts, 13 parts, 15 parts, etc.

[0036] Positive effects of limiting the mass fraction of Fe2O3 to 1% to 10%: Fe2O3 is a red inorganic pigment often used as a colorant to impart a specific color to materials. In the surface treatment agent for weathering steel, the main role of Fe2O3 is to ensure the chocolate color of the stable rust layer formed after the treatment agent dries. This color is not only beautiful but also can simulate the effect of natural rust to a certain extent, increasing the artistic sense of weathering steel. When the mass fraction of Fe2O3 is in the range of 1 part to 10 parts, the color of the surface treatment agent after drying can be ensured to be stable and uniform. If the mass fraction of Fe2O3 is higher than the above range, it may cause the color to be too deep, showing a reddish or blackish phenomenon; if the mass fraction is lower than the above range, it may not form sufficient color coverage, resulting in a lighter color or color difference. Exemplarily, the mass fraction of Fe2O3 can be 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, etc.

[0037] Positive effects of limiting the mass fraction of NaCl to 0.5 part to 3 parts: The introduction of NaCl can accelerate the electrochemical corrosion process on the surface of weathering steel. Since NaCl is an electrolyte, it can promote the ion conduction in water, thereby accelerating the reaction between the surface of weathering steel and corrosion media such as oxygen and water in the atmosphere, and then accelerating the occurrence of initial corrosion. In addition, in the surface treatment agent of weathering steel, the presence of NaCl can accelerate the transformation of the unstable rust layer components into more stable rust layer components. This transformation process helps to form a denser and more stable rust layer, thereby improving the corrosion resistance of weathering steel. When the mass fraction of NaCl is higher than the above range, although it can further accelerate the initial corrosion and rust layer transformation rate of weathering steel, too much Cl - will damage the structure of the rust layer. This is because Cl- has strong penetrability and activity, which can penetrate the rust layer and react with the internal metal matrix, resulting in the rust layer becoming loose and porous, and even forming local corrosion phenomena such as pitting corrosion. In this way, the rust layer that should originally play a protective role instead becomes a factor accelerating corrosion, making it difficult to form a stable rust layer. On the contrary, if the mass fraction of NaCl is lower than the above range, its role as a promoter will become insignificant. This will lead to a slowdown in the initial corrosion process of weathering steel and a decrease in the transformation rate of the rust layer. Although this can reduce the problem of rust layer damage caused by too much Cl - , it may also cause the rust layer to form too slowly to effectively protect the weathering steel in a timely manner. Exemplarily, the mass fraction of NaCl can be 0.5 part, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, etc.

[0038] Positive effects of limiting the mass fraction of the defoamer to 0.01 part to 0.1 part: This mass fraction range can ensure that the defoamer plays the best defoaming effect in the treatment agent. An appropriate amount of defoamer can quickly and effectively destroy the foam structure and avoid the influence of foam on the uniform distribution of the treatment agent. In addition, foam may cause defects such as shrinkage holes and fisheyes on the surface of weathering steel during the drying process, affecting the appearance quality. The use of an appropriate amount of defoamer can effectively reduce the occurrence of these defects and improve the quality of the treated weathering steel. When the mass fraction of the defoamer is higher than the above range, the overall fluidity of the treatment agent decreases, which is not conducive to coating. When the mass fraction is lower than the above range, the defoaming effect is not obvious. Exemplarily, the content of the defoamer can be 0.01 part, 0.02 part, 0.04 part, 0.06 part, 0.08 part, 0.1 part, etc.

[0039] Positive effects of limiting the mass fraction of the wetting agent to 0.01 part to 0.1 part: The wetting agent can significantly reduce the surface tension of the treatment agent, making it easier for the treatment agent to penetrate into the tiny pores on the surface of weathering steel, thereby increasing the contact area and wettability between the treatment agent and the steel. This excellent wetting performance helps to improve the adhesion and durability of the treatment agent on the steel surface. In addition, a wetting agent with a mass fraction of 0.01 part to 0.1 part can ensure the uniform distribution of the treatment agent on the surface of weathering steel, avoiding situations of too high or too low local concentration, thus ensuring the consistency of the treatment effect. A mass fraction of the wetting agent higher than the above range is not conducive to economy, and a mass fraction lower than the above range results in an insignificant wetting effect. Exemplarily, the mass fraction of the wetting agent can be 0.01 part, 0.02 part, 0.04 part, 0.06 part, 0.08 part, 0.1 part, etc.

[0040] In some embodiments, the solvent is water.

[0041] In the weathering steel surface treatment agent, using water as the solvent enables the water-soluble acrylic resin to be fully dissolved and uniformly dispersed in the solution, which is the basis for forming a stable and uniform surface treatment agent. Compared with organic solvents, water as a solvent has better environmental friendliness and safety. It reduces the emission of harmful substances and lowers the potential harm to the environment and the human body. In addition, the cost of water is relatively low, and using it as a solvent can reduce the overall cost of the surface treatment agent and improve its economy.

[0042] In some embodiments, the defoaming agent is a silicone defoaming agent.

[0043] The silicone defoaming agent has a low surface tension. Usually, only a small amount needs to be added to achieve a significant defoaming effect; the silicone defoaming agent can be used within a wide temperature range and will not fail due to temperature changes; the silicone defoaming agent is difficult to chemically react with other substances. As long as it is properly formulated, it can be used in acid, alkali, and salt solutions without polluting the defoamed system and without affecting the product quality; the silicone defoaming agent is harmless to the human body and meets environmental protection requirements.

[0044] In some embodiments, the wetting agent is a silicone wetting agent.

[0045] The silicone wetting agent is an auxiliary agent that can significantly improve the coverage of a liquid object on a solid surface, reduce the surface tension, and thus improve the wettability of the liquid on the solid surface. It is mainly composed of components such as modified silicone oxygen alkane copolymers and has various characteristics and a wide range of application fields.

[0046] Figure 1 It is a schematic flowchart of the usage method of a weathering steel surface treatment agent provided by an embodiment of the present application.

[0047] Please refer to Figure 1, Second aspect, the present application provides a method for using the weather-resistant steel surface treatment agent described in the first aspect, the method comprising:

[0048] Mix the water-soluble acrylic resin with a solvent and stir to obtain a mixed solution;

[0049] Add α-FeOOH, γ-FeOOH, Fe2O3, NaCl, defoamer and wetting agent to the mixed solution in sequence to obtain the weather-resistant steel surface treatment agent;

[0050] Pretreat the weather-resistant steel to remove the surface scale;

[0051] Coat the weather-resistant steel surface treatment agent on the surface of the weather-resistant steel to obtain coated steel;

[0052] Dry the coated steel.

[0053] In some embodiments, the pretreatment method is any one of sandblasting and shot peening.

[0054] In some embodiments, the coating method is any one of brushing and spraying.

[0055] In some embodiments, the drying temperature is room temperature, and the drying time ≥ 24h.

[0056] The drying temperature is room temperature. In the examples of the present application, room temperature can be 0°C to 30°C.

[0057] A drying time ≥ 24h can ensure that the components in the treatment agent, especially the water-soluble acrylic resin, have sufficient time for a sufficient curing reaction. Exemplarily, the natural drying time can be 24h, 24.1h, 24.2h, 24.3h, 24.4h, 24.5h, 24.6h, etc.

[0058] The following further elaborates the present application in conjunction with specific examples. For the experimental methods without specific conditions indicated in the following examples, they are generally determined according to industry standards; if there is no corresponding industry standard, they are carried out according to general international standards, conventional conditions, or conditions recommended by the manufacturer.

[0059] In the examples of the present application, after coating the surface treatment agent on the weather-resistant steel, a cyclic immersion accelerated corrosion experiment is carried out, which specifically includes the following steps:

[0060] Step 1: Process the weather-resistant steel into specimens of 40mm × 60mm × 4mm, sandblast the surface, degrease with acetone, clean with alcohol, and dry for standby.

[0061] Step 2: prepare 1000g of surface treatment agent (36% water-soluble acrylic resin, 2% α-FeOOH, 8% γ-FeOOH, 33% Fe2O, 1% NaCl, 0.05% defoaming agent, 0.05% wetting agent, and the remainder is solvent water), and stir well.

[0062] Step 3: Use a brush to evenly apply the surface treatment agent on the surface of the weathering steel and dry it naturally at room temperature for 24 hours.

[0063] Step 4: Further, a 7-day periodic immersion corrosion test was conducted on the surface treated samples and bare steel samples (the experimental medium was a 3.5% by mass NaCl solution, the experimental temperature was 45°C, the humidity was 70%, each cycle was 60 minutes, the immersion time was 12 minutes, and the drying time was 48 minutes.), and the corrosion rate and rust layer composition of the samples after the experiment were analyzed.

[0064] Figure 2 This is the macroscopic morphology of weathering steel after coating with surface treatment agent. It can be seen that the surface treatment agent turns chocolate color after drying, which is consistent with the color of the stable weathering steel rust layer.

[0065] Figure 3 In order to accelerate the corrosion rate of bare weathering steel specimens and surface treated specimens after 7 days of corrosion, the results showed that the surface treatment agent can significantly improve the corrosion resistance of weathering steel.

[0066] Furthermore, the distribution of alloy elements in the rust layer of the surface treated weathering steel samples was observed using a scanning electron microscope. Figure 4 , Cr and Cu elements are obviously enriched in the rust layer. The enrichment of Cr in the rust layer can replace Fe in α-FeOOH to generate α-(Fe1-xCrx)OOH, which improves the compactness of the rust layer. The enrichment of Cu in the rust layer can refine the rust layer grains and improve the protection of the rust layer to the substrate. The enrichment of Cr and Cu elements in the rust layer is one of the beneficial effects of adding α-FeOOH and γ-FeOOH to the surface treatment agent.

[0067] In summary, the weathering steel surface treatment agent provided by the present application is safe, environmentally friendly and easy to operate. After being coated on the surface of weathering steel, it can significantly improve the corrosion resistance of weathering steel. By adding pigments and fillers that are beneficial to stabilizing the rust layer, it promotes the enrichment of Cr and Cu elements in the rust layer, shortens the stabilization process of the weathering steel rust layer, and ensures uniform appearance color.

[0068] One or more technical solutions in the embodiments of the present application also have at least the following technical effects or advantages:

[0069] (1) The surface treatment agent has a scientific composition ratio, and the organic volatile solvent is replaced by an aqueous solution. The pigments and fillers do not contain harmful substances such as hexavalent chromium or trivalent chromium, thereby minimizing the pollution to the environment.

[0070] (2) The surface treatment agent obtained in this application is safe, environmentally friendly, and has no toxic or irritating volatile gases. It can be directly brushed or sprayed on the surface of weathering steel. The coating process is simple, and it forms a film quickly at room temperature, making it suitable for large-scale industrial production.

[0071] (3) The appearance of the surface treatment agent is close to the color of the stable rust layer of weathering steel, which can ensure color consistency while shortening the stabilization process of the rust layer of weathering steel.

[0072] (4) The surface treatment agent can effectively improve the corrosion resistance of the rust layer of weathering steel and is applicable to areas with high Cl - content, thus broadening the geographical scope of the application of weathering steel without painting.

[0073] The above are only the specific embodiments of this application, which enable those skilled in the art to understand or implement this application. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined in this application can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to these embodiments shown in this application, but will conform to the broadest scope consistent with the principles and novel features claimed in this application.

Claims

1. A weather-resistant steel surface treatment agent, characterized in that, The surface treatment agent includes: water-soluble acrylic resin, α-FeOOH, γ-FeOOH, Fe2O3, NaCl, defoamer, wetting agent and solvent.

2. The surface treatment agent according to claim 1, characterized in that By mass, the surface treatment agent includes: water-soluble acrylic resin: 30 parts to 50 parts, α-FeOOH: 1 part to 10 parts, γ-FeOOH: 5 parts to 15 parts, Fe2O3: 1 part to 10 parts, NaCl: 0.5 part to 3 parts, defoamer: 0.01 part to 0.1 part, wetting agent: 0.01 part to 0.1 part.

3. The surface treatment agent according to claim 1, characterized in that, The defoamer is a silicone defoamer.

4. The surface treatment agent according to claim 1, characterized in that, The wetting agent is a silicone wetting agent.

5. The surface treatment agent according to claim 1, characterized in that, The solvent is water.

6. A method for using the weathering steel surface treatment agent according to any one of claims 1 to 5, characterized in that, The method includes: Mix and stir the water-soluble acrylic resin and the solvent to obtain a mixed solution; Add α-FeOOH, γ-FeOOH, Fe2O3, NaCl, defoamer and wetting agent to the mixed solution in sequence to obtain the weathering steel surface treatment agent; Pretreat the weathering steel to remove the mill scale on the surface; Coat the surface of the weathering steel with the weathering steel surface treatment agent to obtain a coated steel; Dry the coated steel.

7. The method according to claim 5, characterized in that, The way of the pretreatment is any one of sandblasting and shot peening.

8. The method according to claim 5, characterized in that, The way of the coating is any one of brushing and spraying.

9. The surface treatment agent according to claim 1, wherein The drying temperature is room temperature, and the drying time ≥ 24h.

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