Corrosion-resistant bolt and preparation method thereof

Abstract

The invention relates to the field of alloy steel, and provides a corrosion-resistant bolt and a preparation method thereof. The corrosion-resistant bolt comprises a bolt body and a corrosion-resistant coating sprayed on the surface of the bolt body, and the corrosion-resistant coating is prepared from, by weight, 55-65 parts of epoxy resin, 14-20 parts of an MIO-SiO2 composite material, 10-14 parts of zinc phosphate, 4-6 parts of talcum powder, 6-8 parts of a xylene / butanone mixed solvent, 1-1.4 parts of a dispersing agent, 0.5-1 part of a defoaming agent and 0.5-0.7 part of an ultraviolet light absorber. According to the corrosion-resistant bolt provided by the invention, the corrosion resistance of the bolt is effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy steel, and specifically, to a corrosion-resistant bolt and a preparation method thereof. Background Art

[0002] As an important connecting part in mechanical structures, bolts are often disassembled and reassembled repeatedly during actual application. It is required that the strength of the bolts meets the actual needs to ensure the stability of the overall mechanical structure and avoid potential safety hazards. At the same time, in complex application environments such as acidic, alkaline, and salt spray corrosive environments, the corrosion resistance of bolts is also crucial. If the surface of the bolt material is corroded, pitting pits will gradually appear. Over time, the pitting pits will continuously extend vertically, resulting in a significant reduction in the service life of the bolts.

[0003] Currently, common bolt materials are mostly metal materials such as carbon steel. These bolt materials have defects such as relatively large weight, low comprehensive mechanical properties, and poor corrosion resistance. Although the corrosion resistance can be improved by surface coating with an anti-corrosion coating, the coating is prone to aging, wear, or peeling, and cannot protect the bolts for a long time, affecting the service life of the bolts.

[0004] Surface treatment technology is also an important means to improve the corrosion resistance of bolts. Common surface treatment technologies include electroplating, hot dip plating, dacromet treatment, Teflon coating, etc. These technologies can form a protective layer on the surface of the bolts to isolate the direct contact between the corrosive medium and the bolt substrate, thereby extending the service life of the bolts. However, there are still problems in the prior art such as poor corrosion resistance of bolt materials, easy aging and peeling of surface coatings, and difficulty in balancing the strength and corrosion resistance of bolts. Based on this, the present invention proposes a corrosion-resistant bolt and a preparation method thereof. Summary of the Invention

[0005] The present invention proposes a corrosion-resistant bolt and a preparation method thereof, which can effectively improve the corrosion resistance of the bolts and balance the bolt strength at the same time.

[0006] The technical solution of the present invention is as follows: In a first aspect, the present invention proposes a corrosion-resistant bolt, including a bolt body and a corrosion-resistant coating sprayed on the surface of the bolt body. The corrosion-resistant coating comprises the following materials in parts by weight: 55 - 65 parts of epoxy resin, 14 - 20 parts of MIO@SiO2 composite material, 10 - 14 parts of zinc phosphate, 4 - 6 parts of talcum powder, 6 - 8 parts of xylene / butanone mixed solvent, 1 - 1.4 parts of dispersant, 0.5 - 1 part of defoamer, and 0.5 - 0.7 part of ultraviolet absorber.

[0007] As a further technical solution, the bolt body is composed of the following components by mass percentage: C 0.2% - 0.24%, Si 0.15% - 0.2%, Cu 0.1% - 0.15%, Cr 1.0% - 1.2%, Mn 2.15% - 2.55%, Ni 1.5% - 1.8%, Co 0.05% - 0.14%, Al 0.05% - 0.07%, Ti 0.02% - 0.05%, V 0.04% - 0.06%, Mo 0.45% - 0.65%, and the balance is Fe and other inevitable impurities.

[0008] As a further technical solution, the bolt body is composed of the following components by mass percentage: C 0.2% - 0.24%, Si 0.15% - 0.2%, Cu 0.1% - 0.15%, Cr 1.0% - 1.2%, Mn 2.15% - 2.55%, Ni 1.5% - 1.8%, Co 0.05% - 0.14%, Al 0.05% - 0.07%, Ti 0.02% - 0.05%, V 0.04% - 0.06%, Mo 0.45% - 0.65%, and the balance is Fe and other inevitable impurities, and the mass ratio of Mo / (Cr + V) = 0.357 - 0.7.

[0009] As a further technical solution, the preparation method of the MIO@SiO2 composite material includes: dispersing mica iron oxide after surface activation with dilute hydrochloric acid in an ethanol - water mixed solvent, adding tetraethyl orthosilicate, stirring at 55 - 65 °C for 6 - 8 hours, controlling the pH = 9 - 10 with ammonia water during this period, naturally cooling to room temperature, centrifuging, and washing after the reaction is completed; dispersing the obtained product in ethanol, adding stearic acid, stirring and reacting at 65 - 75 °C and 300 - 400 rpm for 1 - 2 h, and then centrifuging, washing, and drying to obtain the product.

[0010] As a further technical solution, the activation step of the mica iron oxide includes: adding mica iron oxide to an aqueous solution of dilute hydrochloric acid with a mass concentration of 3% - 5%, performing ultrasonic oscillation at 30 - 40 kHz for 40 - 60 min, maintaining the temperature at 25 - 30 °C, centrifuging, washing with deionized water until neutral, and drying to obtain it.

[0011] As a further technical solution, the dosage ratio of the activated mica iron oxide, ethanol - water mixed solvent, tetraethyl orthosilicate, and stearic acid is 100 g : 500 - 600 mL : 30 - 50 mL : 2 - 3 g, where the volume ratio of ethanol to water in the ethanol - water mixed solvent is 4 - 5 : 1.

[0012] As a further technical solution, the epoxy resin is epoxy resin E-44; the talcum powder is 1200-1300 mesh; the weight ratio of toluene to methyl ethyl ketone in the toluene / methyl ethyl ketone mixed solvent is 2-3:1.

[0013] As a further technical solution, the dispersant is BYK-161 dispersant; the defoaming agent is BYK-020 defoaming agent; the ultraviolet absorber is UV-9 ultraviolet absorber.

[0014] In a second aspect, the present invention provides a method for preparing a corrosion-resistant bolt, the steps including: S1. Weigh the raw materials according to the components of the bolt body, then carry out melting and casting to obtain a bolt blank; forge and heat-treat the bolt blank to obtain a bolt rod. S2. Process and form the bolt rod, and perform surface pretreatment to obtain the bolt body. S3. Mix the components of the corrosion-resistant coating to obtain a mixture; spray the mixture on the surface of the bolt body, and after curing, obtain the corrosion-resistant bolt.

[0015] As a further technical solution, the preparation method of the corrosion-resistant coating includes: premix the xylene / methyl ethyl ketone mixed solvent with the dispersant, and sequentially add epoxy resin, MIO@SiO2, and zinc phosphate and stir and mix them; add talcum powder, ultraviolet absorber, and defoaming agent, and perform vacuum degassing to obtain the product.

[0016] The working principle and beneficial effects of the present invention are as follows: In the corrosion-resistant bolt of the present invention, the MIO@SiO2 composite material is introduced into the coating. This material is coated with SiO2 and modified with stearic acid, which significantly enhances the barrier effect and hydrophobicity of the coating. Compared with unactivated and unmodified mica iron oxide, the MIO@SiO2 composite material can more effectively block the penetration of corrosive media. The SiO2 coating layer can form a dense protective film, effectively blocking the penetration of corrosive media such as moisture and oxygen into the bolt body, thereby prolonging the service life of the bolt. The stearic acid modification improves the hydrophobicity of the material, making it more difficult for corrosive media such as moisture to stay and penetrate on the surface of the coating, further enhancing the corrosion resistance of the bolt.

[0017] The alloy composition of the bolt body in the present invention is carefully optimized. By adjusting the mass percentages of various elements, the addition of alloy elements such as Mo, Cr, and V can form a stable passive film to protect the bolt body from being eroded by corrosive media. Especially the control of the Mo / (Cr + V) mass ratio makes the passive film more stable, thereby improving the corrosion resistance of the bolt. The synergistic effect of Ni and Co stabilizes austenite, refines the grains, and improves the mechanical properties and corrosion resistance of the bolt.

[0018] The formulation design of the corrosion-resistant coating of the present invention is scientific and reasonable. The components interact with each other and jointly improve the performance of the coating. The epoxy resin base material in the corrosion-resistant coating forms good adhesion with the metal surface, ensuring the firmness of the coating. The zinc phosphate anti-rust pigment reacts with the metal surface to generate an insoluble phosphate protective film, further enhancing the corrosion resistance of the bolt. The addition of fillers such as talcum powder improves the hardness and wear resistance of the coating, making the coating more durable. The addition of diluents such as xylene / butanone mixed solvent helps the uniform mixing of each component and the spraying of the coating, improving the overall performance of the coating. The addition of dispersants, defoamers and ultraviolet absorbers further improves the dispersibility, stability and aging resistance of the coating, making the coating more durable.

[0019] Specific implementation mode The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention. It should be noted that the mica iron oxide in the present invention is in flake shape with an average particle size of 10 μm.

[0020] Example 1 A corrosion-resistant bolt is provided in this embodiment, including a bolt body and a corrosion-resistant coating sprayed on the surface of the bolt body; The corrosion-resistant coating includes the following materials in parts by weight: 60 parts of epoxy resin E-44, 17 parts of MIO@SiO2 composite material, 12 parts of zinc phosphate, 5 parts of 1250-mesh talcum powder, 7 parts of xylene / butanone mixed solvent, 1.2 parts of BYK-161 dispersant, 0.7 part of BYK-020 defoamer, and 0.6 part of UV-9 ultraviolet absorber; The bolt body is composed of the following components in mass percentage: C 0.22%, Si 0.18%, Cu 0.12%, Cr 1.0%, Mn 2.35%, Ni 1.65%, Co 0.1%, Al 0.06%, Ti 0.03%, V 0.04%, Mo 0.6%, and the balance is Fe and other inevitable impurities, and the mass ratio of Mo / (Cr+V)=0.577; Among them, the preparation method of the MIO@SiO2 composite material includes: taking 200 g of mica at 27 °C, centrifuging, washing with deionized water until neutral, and drying in a vacuum oven at 60 °C for 12 h to obtain activated mica iron oxide. Dispersing 100 g of the activated mica iron oxide in 550 mL of an ethanol-water mixed solvent (the volume ratio of ethanol to water is 4.5:1), adding 40 mL of tetraethyl orthosilicate, stirring in a water bath at 60 °C at a rotation speed of 200 rpm for 7 hours, controlling the pH = 9.5 with ammonia water during this period, naturally cooling to room temperature after the reaction is completed, centrifuging, and washing with ethanol 3 times; dispersing the obtained product in 200 mL of ethanol, adding 2.5 g of stearic acid, stirring and reacting at 70 °C and 350 rpm for 1.5 h, centrifuging, washing with ethanol 2 times, and drying in a vacuum at 60 °C for 8 h to obtain the product.

[0021] The preparation method of the corrosion-resistant bolt includes the following steps: S1. After weighing the raw materials according to the components of the bolt body, melting in an intermediate frequency induction furnace, controlling the melting temperature at 1570 °C, introducing argon for protection, refining and removing impurities, and then standing for 17 minutes, casting into a cylindrical ingot, controlling the casting temperature at 1500 °C, and using a water-cooled copper mold for rapid solidification to obtain the bolt blank; heating the bolt blank to 1170 °C and holding for 2 hours, performing multi-directional forging (the deformation amount is 60%), and the final forging temperature is 900 °C to obtain a uniformly refined forging blank, heating to 770 °C at a rate of 47 °C / min, holding for 17 minutes and then air-cooling to room temperature, and then tempering at 225 °C for 1.5 hours to obtain the bolt bar; S2. Processing and forming the bolt bar, performing sandblasting surface pretreatment with 90-mesh brown fused alumina, and ultrasonically cleaning in acetone and ethanol for 15 minutes each to obtain the bolt body; S3. Premixing the xylene / butanone mixed solvent and the dispersant at 2000 rpm for 10 minutes, successively adding epoxy resin, MIO@SiO2, and zinc phosphate and stirring and mixing at a rotation speed of 400 rpm for 50 minutes; adding talcum powder, ultraviolet absorber, and defoaming agent and continuing to stir for 25 minutes, performing vacuum degassing at a vacuum degree of -0.095 MPa for 30 minutes to obtain a mixture; spraying the mixture on the surface of the bolt body, with a spray gun pressure of 19 MPa, a nozzle diameter of 0.5 mm, a spraying distance of 225 mm, controlling the wet film thickness at 90 μm, spraying in 2 times, pre-curing at 80 °C for 30 minutes, curing at 120 °C for 2 hours, and naturally cooling to below 50 °C to obtain the corrosion-resistant bolt.

[0022] Example 2 In this example, a corrosion-resistant bolt is provided, which includes a bolt body and a corrosion-resistant coating sprayed on the surface of the bolt body; The corrosion-resistant coating comprises the following materials by weight: 55 parts of epoxy resin E-44, 14 parts of MIO@SiO2 composite material, 10 parts of zinc phosphate, 4 parts of talc powder with a mesh number of 1200, 6 parts of xylene / butanone mixed solvent, 1 part of BYK-161 dispersant, 0.5 part of BYK-020 defoamer, and 0.5 part of UV-9 ultraviolet absorber; The bolt body is composed of the following components by mass percentage: C 0.2%, Si 0.15%, Cu 0.1%, Cr 1.0%, Mn 2.2%, Ni 1.6%, Co 0.1%, Al 0.06%, Ti 0.04%, V 0.04%, Mo 0.65%, the balance being Fe and other inevitable impurities, and the mass ratio of Mo / (Cr + V)=0.625; Among them, the preparation method of the MIO@SiO2 composite material includes: adding 200 g of mica iron oxide into 1 L of dilute hydrochloric acid aqueous solution with a mass concentration of 3%, ultrasonic oscillation at 30 kHz for 40 min, maintaining the temperature at 25 °C, centrifuging, washing with deionized water until neutral, and drying in a vacuum oven at 60 °C for 12 h to obtain activated mica iron oxide. Dispersing 100 g of activated mica iron oxide in 500 mL of ethanol-water mixed solvent (the volume ratio of ethanol to water is 4:1), adding 30 mL of tetraethyl orthosilicate, stirring in a water bath at 55 °C and a rotation speed of 200 rpm for 6 h, controlling the pH = 9 with ammonia water during the period, naturally cooling to room temperature after the reaction is completed, centrifuging, and washing with ethanol 3 times; dispersing the obtained product in 200 mL of ethanol, adding 2 g of stearic acid, stirring and reacting at 65 °C and 300 rpm for 1 h, centrifuging, washing with ethanol 2 times, and drying in vacuum at 60 °C for 8 h to obtain the product.

[0023] The preparation method of the corrosion-resistant bolt comprises the following steps: S1. After weighing the raw materials according to the components of the bolt body, melting in an intermediate frequency induction furnace, controlling the melting temperature at 1550 °C, introducing argon for protection, refining and removing impurities, and then standing for 15 minutes, casting into a cylindrical ingot, controlling the casting temperature at 1480 °C, and rapidly solidifying with a water-cooled copper mold to obtain a bolt blank. Heating the bolt blank to 1150 °C and holding for 2 h, performing multi-directional forging (the deformation amount is 60%), and the final forging temperature is 900 °C to obtain a uniformly refined forging blank. Heating to 750 °C at a rate of 45 °C / min, holding for 15 min, and then air-cooling to room temperature, and subsequently tempering at 200 °C for 1 h to obtain a bolt bar; S2. Processing and forming the bolt bar, using 80-mesh brown fused alumina sand for sandblasting surface pretreatment, and ultrasonically cleaning in acetone and ethanol for 15 min each to obtain the bolt body; S3. Premix the xylene / butanone mixed solvent and the dispersant at 2000 rpm for 10 min, then sequentially add epoxy resin, MIO@SiO2, and zinc phosphate and stir and mix at a rotation speed of 400 rpm for 40 min; add talcum powder, ultraviolet absorber, and defoamer and continue stirring for 20 min. After vacuum degassing at a vacuum degree of -0.095 MPa for 30 min, a mixture is obtained; spray the mixture on the surface of the bolt body, with a spray gun pressure of 18 MPa, a nozzle diameter of 0.5 mm, a spraying distance of 200 mm, a wet film thickness controlled at 80 μm, spray in 2 times, pre-cure at 80 °C for 30 minutes, cure at 120 °C for 2 hours, and naturally cool to below 50 °C to obtain the corrosion-resistant bolt.

[0024] Example 3 In this example, a corrosion-resistant bolt is provided, including a bolt body and a corrosion-resistant coating sprayed on the surface of the bolt body; The corrosion-resistant coating includes the following materials in parts by weight: 65 parts of epoxy resin E-44, 20 parts of MIO@SiO2 composite material, 14 parts of zinc phosphate, 6 parts of 1300-mesh talcum powder, 8 parts of xylene / butanone mixed solvent, 1.4 parts of BYK-161 dispersant, 1 part of BYK-020 defoamer, and 0.7 part of UV-9 ultraviolet absorber; The bolt body is composed of the following components in mass percentages: C 0.24%, Si 0.2%, Cu 0.15%, Cr 1.2%, Mn 2.15%, Ni 1.5%, Co 0.05%, Al 0.05%, Ti 0.02%, V 0.06%, Mo 0.5%, the balance being Fe and other inevitable impurities, and the mass ratio of Mo / (Cr + V) = 0.397; Among them, the preparation method of the MIO@SiO2 composite material includes: adding 200 g of mica iron oxide to 1 L of a dilute hydrochloric acid aqueous solution with a mass concentration of 5%, ultrasonic oscillation at 40 kHz for 60 min, maintaining the temperature at 30 °C, centrifuging, washing with deionized water until neutral, and drying in a 60 °C vacuum oven for 12 h to obtain activated mica iron oxide. Disperse 100 g of the activated mica iron oxide in 600 mL of an ethanol-water mixed solvent (the volume ratio of ethanol to water is 5:1), add 50 mL of tetraethyl orthosilicate, stir in a 65 °C water bath at a rotation speed of 200 rpm for 8 hours, and control the pH = 10 with ammonia water during the period. After the reaction is completed, naturally cool to room temperature, centrifuge, and wash with ethanol 3 times; disperse the obtained product in 200 mL of ethanol, add 3 g of stearic acid, stir and react at 75 °C and 400 rpm for 2 h, centrifuge, wash with ethanol 2 times, and vacuum dry at 60 °C for 8 h to obtain.

[0025] The preparation method of the corrosion-resistant bolt includes the following steps: S1. After weighing the raw materials according to the components of the bolt body, melt them in an intermediate frequency induction furnace, control the melting temperature at 1600 °C, introduce argon for protection, refine and remove impurities, then let it stand for 20 minutes, and cast it into a cylindrical ingot. Control the casting temperature at 1520 °C, and use a water-cooled copper mold for rapid solidification to obtain a bolt blank. Heat the bolt blank to 1200 °C and hold for 2 hours, perform multi-directional forging (deformation amount is 60%), and the final forging temperature is 900 °C to obtain a uniformly refined forged blank. Heat it to 800 °C at a rate of 50 °C / min, hold for 20 min, then air-cool to room temperature, and then temper at 250 °C for 2 hours to obtain a bolt bar; S2. Process and form the bolt bar, use 100-mesh brown fused alumina sand for sandblasting surface pretreatment, and ultrasonically clean it in acetone and ethanol for 15 min each in sequence to obtain the bolt body; S3. Premix the xylene / butanone mixed solvent and the dispersant at 2000 rpm for 10 min, sequentially add epoxy resin, MIO@SiO2, and zinc phosphate, and stir and mix at a rotation speed of 400 rpm for 60 min; add talcum powder, ultraviolet absorber, and defoaming agent and continue to stir for 30 min, perform vacuum degassing at a vacuum degree of -0.095 MPa for 30 min to obtain a mixture; spray the mixture on the surface of the bolt body, with the spray gun pressure of 20 MPa, the nozzle diameter of 0.5 mm, the spraying distance of 250 mm, control the wet film thickness at 100 μm, spray in 2 times, pre-cure at 80 °C for 30 minutes, cure at 120 °C for 2 hours, and naturally cool to below 50 °C to obtain a corrosion-resistant bolt.

[0026] Example 4 In this example, a corrosion-resistant bolt is provided, including a bolt body and a corrosion-resistant coating sprayed on the surface of the bolt body; The corrosion-resistant coating includes the following materials in parts by weight: 60 parts of epoxy resin E-44, 17 parts of MIO@SiO2 composite material, 12 parts of zinc phosphate, 5 parts of 1250-mesh talcum powder, 7 parts of xylene / butanone mixed solvent, 1.2 parts of BYK-161 dispersant, 0.7 part of BYK-020 defoaming agent, and 0.6 part of UV-9 ultraviolet absorber; The bolt body is composed of the following components in mass percentages: C 0.23%, Si 0.17%, Cu 0.14%, Cr 1.2%, Mn 2.55%, Ni 1.8%, Co 0.14%, Al 0.07%, Ti 0.05%, V 0.06%, Mo 0.45%, and the balance is Fe and other inevitable impurities, and the mass ratio of Mo / (Cr + V) = 0.357; Among them, the preparation method of the MIO@SiO2 composite material includes: taking 200 g of mica at 27°C, centrifuging, washing with deionized water until neutral, and drying in a vacuum oven at 60°C for 12 h to obtain activated mica iron oxide. Dispersing 100 g of the activated mica iron oxide in 550 mL of an ethanol-water mixed solvent (the volume ratio of ethanol to water is 4.5:1), adding 40 mL of tetraethyl orthosilicate, stirring in a water bath at 60°C at a rotation speed of 200 rpm for 7 hours, controlling the pH = 9.5 with ammonia water during this period, naturally cooling to room temperature after the reaction is completed, centrifuging, and washing with ethanol 3 times; dispersing the obtained product in 200 mL of ethanol, adding 2.5 g of stearic acid, stirring and reacting at 70°C and 350 rpm for 1.5 h, centrifuging, washing with ethanol 2 times, and drying in a vacuum at 60°C for 8 h to obtain the product.

[0027] The preparation method of the corrosion-resistant bolt includes the following steps: S1. After weighing the raw materials according to the components of the bolt body, melting in an intermediate frequency induction furnace, controlling the melting temperature at 1570°C, introducing argon for protection, refining and removing impurities, and then standing for 17 minutes, casting into a cylindrical ingot, controlling the casting temperature at 1500°C, and rapidly solidifying with a water-cooled copper mold to obtain a bolt blank; heating the bolt blank to 1170°C and holding for 2 hours, performing multi-directional forging (the deformation amount is 60%), and the final forging temperature is 900°C to obtain a uniformly refined forged blank, heating to 770°C at a rate of 47°C / min, holding for 17 minutes and then air-cooling to room temperature, and then tempering at 225°C for 1.5 hours to obtain a bolt bar; S2. Processing and forming the bolt bar, performing sandblasting surface pretreatment with 90-mesh brown fused alumina, and ultrasonically cleaning in acetone and ethanol for 15 minutes each to obtain the bolt body; S3. Premixing the xylene / butanone mixed solvent and the dispersant at 2000 rpm for 10 minutes, sequentially adding epoxy resin, MIO@SiO2, and zinc phosphate and stirring and mixing at a rotation speed of 400 rpm for 50 minutes; adding talcum powder, ultraviolet absorber, and defoaming agent and continuing to stir for 25 minutes, performing vacuum degassing at a vacuum degree of -0.095 MPa for 30 minutes to obtain a mixture; spraying the mixture on the surface of the bolt body, with the spray gun pressure of 19 MPa, the nozzle diameter of 0.5 mm, the spraying distance of 225 mm, controlling the wet film thickness at 90 μm, spraying in 2 times, pre-curing at 80°C for 30 minutes, curing at 120°C for 2 hours, and naturally cooling to below 50°C to obtain the corrosion-resistant bolt.

[0028] Comparative Example 1 In Comparative Example 1, the mica iron oxide was not activated, and the rest was the same as in Example 1, and the preparation steps were the same as in Example 1.

[0029] Comparative Example 2 The preparation method of the MIO@SiO2 composite material in Comparative Example 2 includes: taking 200 g of mica, heating it to 27 °C, centrifuging, washing it with deionized water until neutral, and drying it in a vacuum oven at 60 °C for 12 h to obtain activated mica iron oxide. 100 g of the activated mica iron oxide is dispersed in 550 mL of an ethanol-water mixed solvent (the volume ratio of ethanol to water is 4.5:1), 40 mL of tetraethyl orthosilicate is added, and the mixture is stirred in a water bath at 60 °C at a rotation speed of 200 rpm for 7 hours. During this period, ammonia water is used to control the pH to 9.5. After the reaction is completed, it is naturally cooled to room temperature, centrifuged, and washed with ethanol three times; after vacuum drying at 60 °C for 8 h, the product is obtained. There is no stearic acid modification step, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0030] Comparative Example 3 In Comparative Example 3, the MIO@SiO2 composite material is replaced with mica iron oxide, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0031] Comparative Example 4 In Comparative Example 4, the MIO@SiO2 composite material is replaced with silicon dioxide, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0032] Comparative Example 5 In Comparative Example 5, the MIO@SiO2 composite material is not added, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0033] Comparative Example 6 The bolt body in Comparative Example 6 is composed of the following components by mass percentage: C 0.22%, Si 0.18%, Cu 0.12%, Cr 0.8%, Mn 2.35%, Ni 1.65%, Co 0.1%, Al 0.06%, Ti 0.03%, V 0.04%, Mo 0.72%, and the balance is Fe and other inevitable impurities, and the mass ratio of Mo / (Cr + V) = 0.85; the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0034] Comparative Example 7 In Comparative Example 7, the bolt body components do not include Ni and Co, and the rest is the same as in Example 1, and the preparation steps are the same as in Example 1.

[0035] Test Example 1: The corrosion-resistant bolts prepared in the foregoing Examples 1-4 and Comparative Examples 1-7 were tested as follows: Tensile strength: Refer to GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature" to detect the tensile strength of the bolts at room temperature; Salt spray resistance: Refer to the ASTM B117 standard and test the bolts with a 5% mass concentration of NaCl solution; Acid resistance: Immerse the bolt in a sulfuric acid aqueous solution with a weight concentration of 10% for 30 days, and observe and record the outer surface of the bolt; Alkali resistance: Immerse the bolt in a sodium hydroxide aqueous solution with a weight concentration of 10% for 30 days, and observe and record the outer surface of the bolt; Adhesion: Test according to ASTM D3359 standard; The results are shown in Table 1 below: Table 1

[0036] Combined with the foregoing content, it can be seen that the salt spray resistance of Examples 1-4 is significantly better than that of Comparative Examples 3-5, indicating that MIO@SiO2 enhances the barrier effect and hydrophobicity of the coating through SiO2 coating and stearic acid modification. Comparative Example 5 has the worst corrosion resistance, indicating that zinc phosphate alone cannot provide long-term protection. The adhesion of Comparative Example 1 and Comparative Example 2 is significantly lower than that of Example 1, indicating that pickling activation improves the binding force between MIO and SiO2, and stearic acid modification improves the dispersibility and reduces coating defects. Example 1 has the highest tensile strength (1511 MPa), while local pitting occurs in Comparative Example 6, indicating that too high a ratio leads to coarsening of carbides and reduces corrosion resistance. The tensile strength of Comparative Example 7 drops sharply and the salt spray resistance is only 600 h, confirming that the synergistic effect of Ni stabilizing austenite and Co refining grains is crucial for mechanical properties and passivation ability.

[0037] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A corrosion-resistant bolt, characterized in that, It includes a bolt body and a corrosion-resistant coating sprayed on the surface of the bolt body. The corrosion-resistant coating comprises the following materials in parts by weight: 55-65 parts of epoxy resin, 14-20 parts of MIO@SiO2 composite material, 10-14 parts of zinc phosphate, 4-6 parts of talcum powder, 6-8 parts of xylene / butanone mixed solvent, 1-1.4 parts of dispersant, 0.5-1 part of defoamer, and 0.5-0.7 part of ultraviolet absorber.

2. The corrosion-resistant bolt according to claim 1, wherein The bolt body is composed of the following components in mass percentage: C 0.2% - 0.24%, Si 0.15% - 0.2%, Cu 0.1% - 0.15%, Cr 1.0% - 1.2%, Mn 2.15% - 2.55%, Ni 1.5% - 1.8%, Co 0.05% - 0.14%, Al 0.05% - 0.07%, Ti 0.02% - 0.05%, V 0.04% - 0.06%, Mo 0.45% - 0.65%, and the balance is Fe and other inevitable impurities.

3. The corrosion-resistant bolt according to claim 2, wherein The bolt body is composed of the following components in mass percentage: C 0.2% - 0.24%, Si 0.15% - 0.2%, Cu 0.1% - 0.15%, Cr 1.0% - 1.2%, Mn 2.15% - 2.55%, Ni 1.5% - 1.8%, Co 0.05% - 0.14%, Al 0.05% - 0.07%, Ti 0.02% - 0.05%, V 0.04% - 0.06%, Mo 0.45% - 0.65%, and the balance is Fe and other inevitable impurities, and the mass ratio of Mo / (Cr + V) = 0.357 - 0.

7.

4. A corrosion-resistant bolt according to claim 1, characterized in that, The preparation method of the MIO@SiO2 composite material includes: dispersing mica iron oxide after surface activation with dilute hydrochloric acid in an ethanol-water mixed solvent, adding tetraethyl orthosilicate, stirring at 55 - 65 °C for 6 - 8 hours, controlling the pH = 9 - 10 with ammonia water during this period, naturally cooling to room temperature, centrifuging, and washing after the reaction is completed; dispersing the obtained product in ethanol, adding stearic acid, stirring and reacting at 65 - 75 °C and 300 - 400 rpm for 1 - 2 h, and obtaining the product after centrifuging, washing, and drying.

5. The corrosion-resistant bolt according to claim 4, characterized in that, The activation step of the mica iron oxide includes: adding mica iron oxide to an aqueous solution of dilute hydrochloric acid with a mass concentration of 3% - 5%, ultrasonic vibrating at 30 - 40 kHz for 40 - 60 min, maintaining the temperature at 25 - 30 °C, centrifuging, washing with deionized water until neutral, and drying to obtain.

6. The corrosion-resistant bolt according to claim 4, characterized in that, The dosage ratio of the activated mica iron oxide, ethanol-water mixed solvent, tetraethyl orthosilicate, and stearic acid is 100 g: 500 - 600 mL: 30 - 50 mL: 2 - 3 g, where the volume ratio of ethanol to water in the ethanol-water mixed solvent is 4 - 5:

1.

7. An anti-corrosion bolt according to claim 1, characterized in that, The epoxy resin is epoxy resin E-44; the talcum powder is 1200 - 1300 mesh; the weight ratio of toluene to butanone in the toluene / butanone mixed solvent is 2 - 3:

1.

8. The corrosion-resistant bolt according to claim 1, characterized in that, The dispersant is BYK-161 dispersant; the defoamer is BYK-020 defoamer; the ultraviolet absorber is UV-9 ultraviolet absorber.

9. A method for preparing a corrosion-resistant bolt according to any one of claims 1-8, characterized in that the steps It includes: S1. Weigh the raw materials according to the components of the bolt body, then carry out smelting and casting to obtain the bolt blank; forge and heat-treat the bolt blank to obtain the bolt bar. S2. Process and form the bolt bar, and obtain the bolt body after surface pretreatment. S3. Mix the components of the corrosion-resistant coating to obtain a mixture; spray the mixture on the surface of the bolt body, and obtain the corrosion-resistant bolt after curing.

10. The preparation method of a corrosion-resistant bolt according to claim 9, wherein, The preparation method of the corrosion-resistant coating includes: premix the xylene / butanone mixed solvent with the dispersant, and successively add epoxy resin, MIO@SiO2, and zinc phosphate and stir and mix them; add talcum powder, ultraviolet absorber, and defoamer, and obtain it after vacuum defoaming.

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