A stabilizing solution and treatment method for rust layer on the surface of weathering steel bolts

Abstract

The present invention provides a stabilizing solution and treatment method for the rust layer on the surface of a weathering steel bolt, and relates to the field of stabilizing the rust layer on weathering steel. The stabilizing solution comprises: acetic acid, tannic acid, a stabilizer, a surfactant, water, and one or more of Na2S2O3, Na2SO4, and NaHSO4. A treatment method for the rust layer on the surface of a weathering steel bolt comprises the following specific steps: (1) cleaning the surface of the bolt; (2) preparing a rust layer stabilizing solution and applying it; (3) after the bolt forms a uniform rust layer, coating the bolt with a post-treatment agent; (4) installing the bolt after step (3), and coating an isolation protective film on the surface of the installed bolt and nut. The method for treating the weathering steel bolt adopted by the present invention facilitates the subsequent disassembly of the bolt, realizes green and pollution-free rust layer stabilization treatment, and improves the weather resistance of the rust layer. During long-term use, the protective layer can be naturally degraded and is environmentally friendly.

Description

Technical Field

[0001] The invention relates to the field of weathering steel rust layer stabilization, and in particular provides a stabilization solution and a treatment method for the rust layer on the surface of a weathering steel bolt. Background Art

[0002] Weathering steel is a corrosion-resistant material that can be used directly in atmospheric corrosion environments without requiring painting. Compared to other materials, the alloying elements in weathering steel react chemically with airborne gases such as water vapor, free chloride ions, sulfur dioxide, and nitrogen oxides in atmospheric corrosion environments, gradually transforming into a dense, protective rust layer primarily composed of α-FeOOH. This rust layer provides excellent protection and isolation, effectively blocking the penetration and transmission of corrosive media and inhibiting further corrosion. Weathering steel's atmospheric corrosion resistance is generally 2 to 8 times that of ordinary carbon steel, and its weathering effect increases with extended atmospheric service. In some environments, weathering steel can be used directly without the need for surface protective treatments such as painting, saving significant costs. Therefore, it is widely used in structural components such as bridges, building facades, and exterior guardrails.

[0003] Bolts, used to connect and secure structural components, are essential and critical components in the application of weathering steel. Weathering steel components and connecting bolts are often manufactured and designed using the same material. However, compared to weathering steel surfaces, which are exposed to the atmosphere for extended periods, the threads of weathering steel bolts are often in a closed environment, making it difficult for outside air and moisture to penetrate and promote the formation of a protective rust layer primarily composed of α-FeOOH. Once a protective rust layer primarily composed of α-FeOOH forms, the rust layer in the bolt thread crevice remains unstabilized, leading to a high probability of crevice corrosion and galvanic corrosion in atmospheric corrosion environments. Furthermore, since bolted connections require excellent disassembly, the formation of a dense, strong rust layer on the bolt thread significantly increases the torque required to loosen the bolt, making disassembly a significant effort. Furthermore, existing technologies still fail to address the issues of rust layer stabilization treatment for weathering steel bolts, such as the rust layer being easily damaged during bolt tightening, galvanic corrosion caused by varying degrees of rust layer stabilization, and bolt rusting caused by a dense thread rust layer. Summary of the Invention

[0004] The purpose of the present invention is to provide a stabilizing solution and a treatment method for the rust layer on the surface of weathering steel bolts.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] A stabilizing solution for rust layers on the surfaces of weathering steel bolts comprises acetic acid, tannic acid, a stabilizer, a surfactant, water, and one or more of Na2S2O3, Na2SO4, and NaHSO4.

[0007] Furthermore, the mass percentages of the stabilizing solution are as follows: the content of acetic acid is 0.5-2wt%, the content of tannic acid is 0.2-1.0wt%, the content of stabilizer is 0.1-0.5wt%, the content of surfactant is 0.1-0.2wt%, the content of one or more of Na2S2O3, Na2SO4, and NaHSO4 is 1-5wt%, and the balance is water.

[0008] Furthermore, the stabilizer is one or both of Na2MoO4 and CuSO4.

[0009] Furthermore, the surfactant is one or both of sodium dodecylbenzenesulfonate and OP-10.

[0010] A method for treating the rust layer on the surface of weathering steel bolts, the specific steps are as follows:

[0011] (1) Clean the bolt surface;

[0012] (2) Prepare a stabilizing solution and apply it evenly to the entire surface of the bolt to be treated. After application, place the bolt outdoors for 3-4 hours to allow the rust stabilizing solution to dry on the bolt surface and form a uniform rust layer.

[0013] (3) After the bolts form a uniform rust layer, apply a post-treatment agent to the bolts;

[0014] (4) After step (3), installation is performed and an isolation protective film is applied on the surface of the installed bolts and nuts.

[0015] Furthermore, the post-treatment liquid in step (3) is composed of: micron molybdenum disulfide, micron ferric oxide, corrosion inhibitor, film former, moisturizer, and calcium-based grease.

[0016] Furthermore, the post-treatment liquid described in step (3) has the following mass percentages: the content of micron molybdenum disulfide is 1-4wt%, the content of micron ferric oxide is 1-3wt%, the content of corrosion inhibitor is 0.4-1%, the content of film former is 1-4%, the content of moisturizer is 1-5%, and the balance is calcium-based grease.

[0017] Furthermore, the diameter of the micron molybdenum disulfide is 20 microns to 50 microns, the diameter of the micron ferric oxide is 20 microns to 50 microns, the corrosion inhibitor is one or two of sodium silicate, sodium molybdate, and sodium polyphosphate; the film-forming agent is polyvinyl pyrrolidone; and the moisturizing agent is one or two of glycerin and propylene glycol.

[0018] Furthermore, the isolation protective film described in step (4) adopts polyethylene polypropylene rubber powder. Before use, the polyethylene polypropylene rubber powder is mixed with water in a mass ratio of 1:1, stirred and expanded to form a sponge-like colloid, which is applied to the installed bolts and formed into a loose, porous and water-permeable protective film after drying.

[0019] Furthermore, the stirring is carried out by stirring with an agitator at a speed of 500-1000 r / min for 5-10 min.

[0020] The beneficial effects of the present invention are:

[0021] 1. The present invention is applied to the method for treating the rust layer on the surface of weathering steel bolts. On the one hand, it ensures that the formed weathering steel rust layer is dense and stable, and has good protection for the weathering steel substrate; on the other hand, it adopts targeted pre-installation treatment and post-installation treatment processes to avoid the generated rust layer from completely rusting the bolts, thereby facilitating the subsequent disassembly of the bolts.

[0022] 2. The present invention avoids the use of toxic salts such as chromium salts and nitrites, thereby achieving green and pollution-free rust layer stabilization treatment.

[0023] 3. This invention uses a sponge-like colloid made from polyethylene polypropylene rubber powder to protect the bolts. The loose and porous protective layer facilitates the transformation of the rust layer into a stable and dense α-FeOOH-based rust layer, improving the rust layer's weather resistance. Over long-term use, the protective layer will naturally degrade, making it environmentally friendly. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the examples, but is not limited thereto.

[0025] Example 1

[0026] The contents and ratios mentioned are all calculated by mass.

[0027] A total of 17 bolts were processed, with different bolts using different processing processes and subsequent inspection methods.

[0028] The processing technology for bolt numbers 1-14 is as follows:

[0029] (1) Surface cleaning: Use sandblasting to clean the rust and stains on the bolt surface.

[0030] (2) Stabilize the entire rust layer before use. Prepare the stabilization solution.

[0031] The stabilization solution ratio of bolts 1-5 is:

[0032] The content of acetic acid is 2wt%; the content of tannic acid is 1wt%; the total content of Na2S2O3 and Na2SO4 is 5wt%, with a 1:1 ratio; the content of Na2MoO4 is 0.5wt%; the content of sodium dodecylbenzenesulfonate is 0.2wt%, and the balance is water.

[0033] The stabilization solution ratio for bolts 6-8 is:

[0034] The content of acetic acid is 0.5wt%; the content of tannic acid is 0.2wt%; the total content of NaHSO4 and Na2SO4 is 1wt%, and the ratio of the two is 1:1; the content of Na2MoO4 is 0.1wt%; the content of sodium dodecylbenzenesulfonate is 0.1wt%, and the balance is water.

[0035] The stabilization solution ratio for bolts 9-11 is:

[0036] The content of acetic acid is 1.2wt%; the content of tannic acid is 0.6wt%; the total content of NaHSO4 and Na2S2O3 is 3wt%, with a 1:1 ratio; the content of CuSO4 is 0.3wt%; the content of OP-10 is 0.15wt%, and the balance is water.

[0037] The stabilization solution ratio for bolts 12-14 is:

[0038] The content of acetic acid is 1wt%; the content of tannic acid is 0.5wt%; the total content of NaHSO4 and Na2S2O3 is 4wt%, and the ratio of the two is 1:1; the content of CuSO4 is 0.3wt%; the content of sodium dodecylbenzenesulfonate is 0.1wt%, and the balance is water.

[0039] Evenly apply 1 kg of the stabilization solution prepared according to the above ratio to the surfaces of bolts 1-14 to be treated. Spray evenly across the base and crest of the bolts, minimizing runny areas. Use a spray gun to ensure a uniform surface. After application, allow bolts 1-14 to stand outdoors for 3-4 hours to allow the rust stabilization solution to dry and form a uniform rust layer.

[0040] (3) After the stabilized rust layer is formed on the bolts 1-14, the bolts are coated with a post-treatment agent before the bolts and nuts are installed.

[0041] The proportion of post-treatment agent for bolts 1-5 is:

[0042] The content of micron molybdenum disulfide (diameter 20-50 microns) is 4wt%, the content of micron ferric oxide (diameter 20-50 microns) is 3wt%, the total content of sodium silicate and sodium molybdate is 1%, and the two are in a 1:1 ratio; polyvinyl pyrrolidone is 4%, propylene glycol is 5%, and the balance is calcium-based grease.

[0043] The proportion of post-treatment agent for bolts 6-8 is:

[0044] The content of micron molybdenum disulfide (diameter 20-50 microns) is 1wt%, the content of micron ferric oxide (diameter 20-50 microns) is 1wt%, the total content of sodium molybdate and sodium polyphosphate is 0.4%, and the two are in a 1:1 ratio; polyvinyl pyrrolidone is 1%, propylene glycol is 1%, and the balance is calcium-based grease.

[0045] The proportion of post-treatment agent for bolts 9-11 is:

[0046] The content of micron molybdenum disulfide (diameter 20-50 microns) is 2.5wt%, the content of micron ferric oxide (diameter 20-50 microns) is 2wt%, the total content of sodium silicate and sodium polyphosphate is 0.7%, and the two are mixed in a 1:1 ratio; polyvinyl pyrrolidone is 2.5%, glycerol is 3%, and the balance is calcium-based grease.

[0047] The proportion of post-treatment agent for bolts 12-14 is:

[0048] The content of micron molybdenum disulfide (diameter 20-50 microns) is 3wt%, the content of micron ferric oxide (diameter 20-50 microns) is 2wt%, the total content of sodium silicate and sodium molybdate is 0.8%, and the two are in a 1:1 ratio; polyvinyl pyrrolidone is 3%, glycerol is 2%, and the balance is calcium-based grease.

[0049] Evenly apply 0.5 kg of the post-treatment agent prepared according to the above ratio to the surface of the bolt to be treated. Immerse the bolt in the post-treatment agent or apply it by brush. After application, tighten the bolt and nut. Use a torque wrench to tighten the bolt to 800 Nm.

[0050] (4) Apply an isolation protective film. After installation, apply an isolation protective film to the surface of the installed bolts and nuts. Use polyethylene polypropylene rubber powder. Mix it with water in a ratio of 1:1 before use. Use a handheld blender at 800 rpm for 7 minutes to expand it into a sponge-like colloid. Apply it to the installed bolts. After drying, a loose, porous, and water-permeable protective film will be formed.

[0051] The processing technology for bolt numbers 15-17 is as follows:

[0052] After briefly cleaning the bolts and nuts, tighten the nuts with a torque wrench. The fixed torque of the torque wrench is 800N.m.

[0053] Comparison of bolts 1-14 treated with the stabilizing solution and treatment method of the present invention and bolts 15-17 not treated with the stabilizing solution of the present invention, after salt spray accelerated test and outdoor 2-year exposure test, the torque and rust layer quality. All bolts are Q325NH weathering steel

[0054] Test conditions:

[0055] The torque of bolts 1-14 treated with the stabilizing solution and treatment method of the present invention and bolts 15-17 not treated with the stabilizing solution of the present invention after long-term corrosion in atmospheric and simulated environments was compared. The indoor accelerated simulation test used a wet-dry cycle (CCT) treatment. The examples and comparative examples were subjected to indoor accelerated dry-wet cycle simulation tests according to ISO 16539-2013. The specific experimental steps are as follows:

[0056] (I) Place the treated bolts numbered 1, 2, 3, 6, 7, 9, 10, 12, 13, 15, and 16 in a PR-2KP constant temperature and humidity test chamber for 30 minutes at a temperature of 25°C and a relative humidity of 70%.

[0057] (II) Take the bolts numbered 1, 2, 3, 6, 7, 9, 10, 12, 13, 15, and 16 out of the test chamber and apply 40 μL / cm 2 Add the corrosion simulation liquid dropwise and spread it evenly. The simulated industrial atmosphere used in this test is a 3.5% (wt) NaCl aqueous solution and 0.01 mol / L NaHSO3. The time required is about 10 minutes.

[0058] (III) The bolts numbered 1, 2, 3, 6, 7, 9, 10, 12, 13, 15, and 16 were placed back into the test chamber for 344 minutes, ensuring a total time of 6.4 hours for the first stage. This process simulates a high temperature and high humidity environment.

[0059] (IV) The test chamber was programmed to maintain a temperature of 40°C and a relative humidity of 40% for 1.6 hours, simulating a dry environment. Each test cycle consisted of eight hours, with a wet-to-dry ratio of 4:1, simulating the corrosive atmosphere of Shenyang with a relative humidity of 60-70%. The bolt rust composition and torque were tested during each test cycle.

[0060] Taking the Shenyang atmosphere as an example, after two years of outdoor exposure, the weathering effect of bolts was compared. Bolts numbered 4, 5, 8, 11, 14, and 17 were subjected to outdoor exposure tests.

[0061] Test results:

[0062] After long-term testing and simulation tests, all bolts developed a dark yellow-brown rust layer, primarily composed of a protective, dense α-FeOOH matrix. However, the torque levels after testing varied significantly between bolts. XRD was used to analyze the rust layer composition.

[0063] The results showed that bolts 1-14, which had undergone accelerated rust stabilization treatment, formed a dense protective rust layer primarily composed of α-FeOOH after 5 days of CCT and 0.5 years of natural exposure. The rust layer between the bolts did not cause the bolts to seize, and the torque was between 800 and 900. After the complete test cycle, the loose protective film on the surface of bolts 1-14 had completely decomposed, and the surface was covered with a dense protective rust layer primarily composed of α-FeOOH. A torque wrench of approximately 950 N.m was sufficient to remove the nuts.

[0064] Bolts 15-17, which had not been treated with the stabilizing solution of the present invention, had a relatively thin surface rust layer after 5 days of CCT. However, the rust layer stabilized after 60 days of CCT treatment or two years of outdoor exposure. However, the resulting dense rust layer caused the bolts to rust and die.

[0065] Bolt number environment Fixing torque Test cycle loosening torque Rust layer analysis 1 Simulation test, wet-dry cycle 800N.m 5 days 832N.m Mainly α-FeOOH 2 Simulation test, wet-dry cycle 800N.m 30 days 852N.m Mainly α-FeOOH 3 Simulation test, wet-dry cycle 800N.m 60 days 914N.m Mainly α-FeOOH 4 Shenyang Industrial Atmospheric Environment 800N.m 0.5 years 890N.m Mainly α-FeOOH 5 Shenyang Industrial Atmospheric Environment 800N.m 2 years 931N.m Mainly α-FeOOH 6 Simulation test, wet-dry cycle 800N.m 5 days 830N.m Mainly α-FeOOH 7 Simulation test, wet-dry cycle 800N.m 60 days 880N.m Mainly α-FeOOH 8 Shenyang Industrial Atmospheric Environment 800N.m 2 years 909N.m Mainly α-FeOOH 9 Simulation test, wet-dry cycle 800N.m 5 days 836N.m Mainly α-FeOOH 10 Simulation test, wet-dry cycle 800N.m 60 days 923N.m Mainly α-FeOOH 11 Shenyang Industrial Atmospheric Environment 800N.m 2 years 967N.m Mainly α-FeOOH 12 Simulation test, wet-dry cycle 800N.m 5 days 833N.m Mainly α-FeOOH 13 Simulation test, wet-dry cycle 800N.m 60 days 933N.m Mainly α-FeOOH 14 Shenyang Industrial Atmospheric Environment 800N.m 2 years 945N.m Mainly α-FeOOH 15 Simulation test, wet-dry cycle 800N.m 5 days 815N.m Mainly β-FeOOH 16 Simulation test, wet-dry cycle 800N.m 60 days 2600N.m Mainly α-FeOOH 17 Shenyang Industrial Atmospheric Environment 800N.m 2 years Rust Mainly α-FeOOH

[0066] Matters not covered by the present invention are known technologies.

[0067] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

Claims

1. A method for treating the rust layer on the surface of a weathering steel bolt, characterized by: The specific steps are as follows: (1) Clean the bolt surface; (2) Prepare a stabilizing solution and apply it evenly on the entire surface of the bolt to be treated. After application, place the bolt outdoors for 3-4 hours to allow the rust stabilizing solution to dry on the bolt surface and form a uniform rust layer. (3) After the bolts form a uniform rust layer, apply the post-treatment agent to the bolts; (4) After step (3), install the bolts and nuts and apply an isolation protective film on the surface of the installed bolts and nuts; The stabilizing solution comprises: acetic acid, tannic acid, a stabilizer, a surfactant and water, and also comprises one or more of Na2S2O3, Na2SO4 and NaHSO4; The post-treatment agent comprises: micron molybdenum disulfide, micron ferric oxide, corrosion inhibitor, film former, moisturizer, and calcium-based grease; The isolation protective film described in step (4) is made of polyethylene polypropylene rubber powder. Before use, the polyethylene polypropylene rubber powder is mixed with water in a mass ratio of 1:1, stirred and expanded to form a sponge-like colloid, which is then applied to the installed bolts and formed into a loose, porous, water-permeable protective film after drying.

2. The method for treating the rust layer on the surface of weathering steel bolts according to claim 1, characterized in that: The post-treatment liquid described in step (3) has the following mass percentages: 1-4wt% of micron molybdenum disulfide, 1-3wt% of micron ferric oxide, 0.4-1% of corrosion inhibitor, 1-4% of film former, 1-5% of moisturizer, and the balance is calcium-based grease.

3. The method for treating the rust layer on the surface of weathering steel bolts according to claim 1, characterized in that: The diameter of the micron molybdenum disulfide is 20 microns to 50 microns, the diameter of the micron ferric oxide is 20 microns to 50 microns, the corrosion inhibitor is one or two of sodium silicate, sodium molybdate, and sodium polyphosphate; the film-forming agent is polyvinyl pyrrolidone; and the moisturizing agent is one or two of glycerin and propylene glycol.

4. The method for treating the rust layer on the surface of weathering steel bolts according to claim 1, characterized in that: The stirring is carried out by using a stirrer at a speed of 500-1000 r / min for 5-10 minutes.