Low-silicon low-sulfur cold-rolled steel sheet and processing technology thereof

Abstract

The invention relates to the technical field of steel and iron materials, in particular to a low-silicon low-sulfur cold-rolled steel sheet and a processing technology thereof. Steel raw materials are sequentially subjected to smelting, forging, hot rolling, acid pickling, cold rolling, critical annealing and leveling processes, and the steel plate is obtained. And then the copper-coated graphene powder and metal powder are used as raw materials, and the metal reinforced coating is prepared. The fluorine modified organic polysilazane is obtained by adding the organic polysilazane, the isocyanate terminated polyurethane, the tetrafluoroethylene, the hexafluoropropylene and the perfluoromethyl vinyl ether. And the fluorine modified organic polysilazane and amphiphilic nano silicon dioxide are used as raw materials to prepare the wear-resistant and corrosion-resistant coating. And sequentially depositing the metal reinforced coating and the wear-resistant and corrosion-resistant coating on the surface of the steel plate through a cold spraying process to obtain a finished product. The finished product prepared by the method has good surface strength, wear resistance and corrosion resistance, so that the finished product has a wide application prospect in the field of steel and iron materials.

Description

Technical Field

[0001] The present invention relates to the technical field of steel materials, in particular to a low-silicon and low-sulfur cold-rolled steel plate and a processing technology thereof. Background Art

[0002] In modern industry, low-silicon, low-sulfur cold-rolled steel sheet is playing an irreplaceable role with its unique properties, demonstrating multi-dimensional value. In the automotive manufacturing industry, low-silicon, low-sulfur cold-rolled steel sheet is a key material. The reduced silicon and sulfur content increases the steel sheet's strength and toughness, making automotive parts more durable and effectively ensuring driving safety. At the same time, its excellent stamping properties make it easy to achieve complex car body shapes, meeting consumer demand for diverse vehicle appearances. Furthermore, its low silicon and low sulfur properties reduce the risk of cracking during processing, improving production efficiency, reducing manufacturing costs, and enhancing the market competitiveness of automakers. The construction industry also benefits from low-silicon, low-sulfur cold-rolled steel sheet. In steel structures, the high strength of low-silicon, low-sulfur cold-rolled steel sheet can reduce the building's deadweight, lower foundation costs, and accelerate construction progress.

[0003] However, parts in the mechanical field need to frequently contact and rub against other objects, such as conveyor belt rollers and machine tool guide rails. If the wear resistance of the steel plate is poor, it will cause rapid wear on the surface of the parts, shortening their service life and increasing the maintenance and replacement costs of the equipment. In addition, in the construction of infrastructure such as buildings and bridges, steel plates are exposed to the natural environment for a long time and are easily corroded by rain, moisture, chemicals, etc., which not only damages the service life of the steel plate structure but also increases maintenance costs. Furthermore, in high-end manufacturing industries such as automobile manufacturing and aerospace, steel plates need to withstand greater pressure and impact. If the surface strength of the steel plate is insufficient, it is easy to deform and damage, thereby affecting the accuracy and performance of the parts.

[0004] In order to overcome the defects of the prior art, the present invention provides a low-silicon and low-sulfur cold-rolled steel plate and a processing technology thereof. Summary of the Invention

[0005] The object of the present invention is to provide a low-silicon and low-sulfur cold-rolled steel plate and a processing technology thereof, so as to solve the problems in the prior art.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A processing technology for low-silicon and low-sulfur cold-rolled steel sheets comprises the following steps:

[0008] Step 1: Smelt and forge the steel raw materials to obtain slabs; then the slabs are sequentially hot rolled, pickled, cold rolled, critical annealed, and leveled to obtain steel plates;

[0009] Step 2: Select pure copper as the target material, and plate copper on the graphene surface through a magnetron sputtering plating process to obtain copper-coated graphene powder; Place copper, nickel, and titanium in a ball mill respectively, grind for 5-7 hours, mix them evenly, heat to 1800-2000°C for melting, and then spray granulate, cool, and sieve to obtain a metal powder with a particle size of 45-70μm. Mix the metal powder with the copper-coated graphene powder, shake and blend for 10-15 minutes to obtain a metal-reinforced coating; Deposit the metal-reinforced coating on the surface of the steel plate through a cold spray process to obtain a steel plate with a metal reinforcement layer;

[0010] Step 3: Under an argon environment, the organic polysilazane and tetrahydrofuran are mixed evenly, and then the isocyanate-terminated polyurethane is added, the temperature is raised to 30-35°C and the reaction is carried out for 8-12 hours. After the reaction is completed, the polyurethane-modified organic polysilazane is obtained by rotary evaporation; under an argon environment, the polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene, perfluoromethyl vinyl ether and tetrahydrofuran are mixed evenly, and then the Karstedt catalyst is added, the temperature is raised to 80-90°C and the reaction is carried out for 50-60 hours. After the reaction is completed, the fluorine-modified organic polysilazane is obtained by rotary evaporation;

[0011] Step 4: Evenly mix the fluorine-modified organic polysilazane, amphiphilic nano-silica and ethyl acetate solvent, and stir the reaction at 45-55°C for 3-5 hours to obtain a wear-resistant and corrosion-resistant coating; deposit the wear-resistant and corrosion-resistant coating onto the surface of the steel plate with a metal reinforcement layer through a cold spray process, and then cure it at 130-140°C for 2-3 hours to obtain a finished product with a wear-resistant and corrosion-resistant layer.

[0012] More optimally, in step one, the content of each component of the steel plate raw material is: by mass fraction, 0.20-0.25% carbon, 4.5-6.5% manganese, 0.05-0.08% silicon, 0.002-0.003% phosphorus, 0.002-0.003% sulfur, 0.001-0.002% aluminum, 88-90% iron, and the remainder is impurities; the hot rolling temperature is 850-1200°C, the cold rolling reduction rate is 60-80%, the critical annealing temperature is 700-750°C, and the leveling reduction rate is 1.0-1.5%.

[0013] More optimally, in step 2, the magnetron sputtering coating process: the pressure is 0.10-0.15Pa, the time is 20-30min; the cold spray process: the spray gun speed is 100-120mm / s, the spraying distance is 25-30mm, and the number of spraying times is 3-5 times.

[0014] More optimally, in step three, when preparing the polyurethane-modified organic polysilazane, the reaction mass ratio of the organic polysilazane and the isocyanate-terminated polyurethane is 1:(0.3-0.5); when preparing the fluorine-modified organic polysilazane, the reaction mass ratio of the polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene, and perfluoromethyl vinyl ether is 1:0.04:(0.06-0.08):0.03.

[0015] More optimally, the preparation process of isocyanate-terminated polyurethane is as follows: dehydrate polyethylene glycol 2000 at 120-130°C and -0.095 to -0.098 MPa for 2-3 hours, then add mixed solvent 1 and stir evenly, raise the temperature to 50-55°C under a nitrogen environment, then add isocyanate dropwise and stir thoroughly for 35-45 minutes, after stirring, heat to 85-90°C and react for 2-3 hours, then cool the system to 50-55°C and add 1,4-butanediol, then heat the system to 80-85°C and react for 4-5 hours to obtain isocyanate-terminated polyurethane.

[0016] More optimally, the mixed solvent 1 is composed of xylene, butyl acetate, and cyclohexanone in a volume ratio of 2: (2.5-3.0): 1; in the isocyanate-terminated polyurethane system, the molar ratio of hydroxyl groups provided by polyethylene glycol 2000 and 1,4-butanediol to isocyanate groups provided by isocyanate is 1: (1.5-1.7).

[0017] More optimally, in step 4, the preparation process of amphiphilic nano-silica is as follows: γ-aminopropyltriethoxysilane and 3-chloropropyltriethoxysilane are respectively added to the mixed solvent 2, and ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2; the nano-silica is respectively added to anhydrous ethanol, ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2, and then the temperature is raised to 40-50°C, and then the modified liquid 1 and modified liquid 2 are respectively added dropwise, and the reaction is continued for 4-5 hours and aged for 4-5 hours. After the reaction is completed, the mixture is centrifuged, washed, and vacuum dried to obtain amino-modified nano-silica and chloropropyl-modified nano-silica, respectively;

[0018] Then, amino-modified nano-silica and chloropropyl-modified nano-silica are added to anhydrous ethanol, uniformly dispersed by ultrasonication, stirred in a water bath at 40-45° C. for reaction for 4-5 hours, aged for 4-5 hours, and after the reaction is completed, centrifuged, washed, and vacuum-dried to obtain amphiphilic nano-silica.

[0019] More optimally, the mixed solvent 2 is composed of anhydrous ethanol and water in a volume ratio of (10-12):1; the reaction mass ratio of γ-aminopropyltriethoxysilane to nano-silica is (0.10-0.12):1; the reaction mass ratio of 3-chloropropyltriethoxysilane to nano-silica is (0.17-0.20):1; the reaction mass ratio of amino-modified nano-silica and chloropropyl-modified nano-silica is 1:(1.0-1.1).

[0020] More optimally, in step four, the mixing ratio of ethyl acetate solvent, fluorine-modified organic polysilazane and amphiphilic nano-silica is 30: (8-12): 1; cold spray process: the spray gun speed is 100-120 mm / s, the spraying distance is 25-30 mm, and the number of spraying times is 3-5 times; the steel plate thickness is 6-10 mm; the metal reinforcement layer thickness is 30-50 μm; and the wear-resistant and corrosion-resistant layer thickness is 60-80 μm.

[0021] Beneficial effects of the present invention:

[0022] The feature of the present invention is that, in step 1, the steel raw material is subjected to smelting, forging, hot rolling, pickling, cold rolling, critical annealing and leveling processes in sequence to obtain a steel plate.

[0023] The present invention is characterized by the following: in step 2, pure copper is first selected as the target material, and copper is plated onto the graphene surface through a magnetron sputtering plating process to obtain copper-coated graphene powder. The copper-coated graphene powder and metal powder are then used as raw materials to prepare a metal-reinforced coating, forming a metal-reinforced layer. The copper-coated graphene powder has a high hardness. When added to metal powder to form a metal-reinforced coating and deposited on the surface of a steel plate, it can significantly increase the surface hardness of the steel plate. This makes the steel plate less susceptible to scratches and deformation when subjected to external impact or friction, effectively enhancing the steel plate's wear resistance and extending its service life in frictional environments.

[0024] The present invention is characterized in that, in step 3, a condensation coupling reaction occurs by adding an organopolysilazane, an isocyanate-terminated polyurethane, and tetrahydrofuran to obtain a polyurethane-modified organopolysilazane. Furthermore, a hydrosilylation reaction occurs by adding the polyurethane-modified organopolysilazane, tetrafluoroethylene, hexafluoropropylene, perfluoromethyl vinyl ether, and tetrahydrofuran to obtain a fluorine-modified organopolysilazane.

[0025] Among them, the organopolysilazane itself has a certain rigid structure. After polyurethane modification, the flexible chain segments of the polyurethane cooperate with the rigid structure of the organopolysilazane to form a molecular structure that is both rigid and flexible. This structure can effectively disperse stress and reduce the wear of the coating when the coating is subjected to external friction. At the same time, the fluoride groups introduced in the subsequent fluorine modification process further enhance the interaction between molecules, making the coating more dense and improving the hardness and wear resistance of the coating. In addition, the fluorine atom has a strong electronegativity, which makes the fluorine-modified organopolysilazane molecule have extremely low surface energy. The contact angle between the low surface energy material and water is large, showing excellent hydrophobic properties, thereby effectively preventing the adsorption and penetration of water and reducing corrosion and damage caused by water.

[0026] Furthermore, in step 4, amphiphilic nano-silica is obtained by adding γ-aminopropyltriethoxysilane, 3-chloropropyltriethoxysilane, and nano-silica. A wear-resistant and corrosion-resistant coating is then prepared using fluorine-modified organopolysilazane and amphiphilic nano-silica as raw materials. The wear-resistant and corrosion-resistant coating is deposited onto the surface of a steel plate having a metal reinforcement layer using a cold spray process, resulting in a finished product having a wear-resistant and corrosion-resistant layer.

[0027] In this step, the amphiphilic nano-silica is used as a filler and added to a coating with fluorine-modified organopolysilazane as the main component. The remaining isocyanate group in the fluorine-modified organopolysilazane can react chemically with the amino group of the amphiphilic nano-silica to form a strong chemical bond. This chemical bonding allows the nano-silica to be better dispersed in the coating system and tightly integrated into the polymer network structure of the coating. In addition, 3-chloropropyltriethoxysilane introduces a chloropropyl group with certain hydrophobic properties by modifying the nano-silica. These hydrophobic groups are oriented on the coating surface, reducing the surface energy of the coating surface. After the amphiphilic nano-silica is combined with the fluorine-modified organopolysilazane, this hydrophobic effect is further enhanced, and by forming a hydrophobic barrier on the coating surface, the hydrophobic corrosion resistance of the steel plate is effectively improved. DETAILED DESCRIPTION

[0028] The following will provide a clear and complete description of the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0029] Source of raw materials:

[0030] Graphene was provided by Jinan Yuanhai Chemical Co., Ltd. with a particle size of 2000 mesh; nanosilica was provided by Beijing Dekedaojin Technology Co., Ltd. with a specification of 15 nm; organic polysilazane was provided by Merck, Germany with a specification of 100%.

[0031] Example 1: Step 1: Smelting and forging a steel raw material to obtain a slab; then sequentially hot rolling, pickling, cold rolling, critical annealing, and leveling to obtain a steel plate; the steel plate raw material comprises the following components, by mass fraction: 0.20% carbon, 4.5% manganese, 0.05% silicon, 0.002% phosphorus, 0.002% sulfur, 0.001% aluminum, 90% iron, and 5.245% impurities; the hot rolling temperature is 1200° C., the cold rolling reduction is 80%, the critical annealing temperature is 750° C., and the leveling reduction is 1.5%;

[0032] Step 2: Select pure copper as the target material, and plate copper on the graphene surface through a magnetron sputtering plating process to obtain copper-coated graphene powder; Place copper, nickel, and titanium in a ball mill respectively, grind for 7 hours, mix them evenly, heat to 2000°C for melting, and then spray granulate, cool, and sieve to obtain a metal powder with a particle size of 50 μm. Mix the metal powder with the copper-coated graphene powder, shake and blend for 15 minutes to obtain a metal-reinforced coating; Deposit the metal-reinforced coating on the surface of the steel plate through a cold spray process to obtain a steel plate with a metal reinforcement layer;

[0033] The magnetron sputtering coating process has a pressure of 0.15 Pa and a time of 30 min. The cold spray process has a spray gun speed of 120 mm / s, a spray distance of 30 mm, and 5 spray times.

[0034] Step 3: The preparation process of isocyanate-terminated polyurethane is as follows: dehydrating polyethylene glycol 2000 at 130°C and -0.098 MPa for 3 hours, then adding mixed solvent 1 and stirring evenly, heating to 55°C under a nitrogen environment, then adding isocyanate dropwise and stirring thoroughly for 45 minutes, heating to 90°C after stirring for 3 hours, then cooling the system to 55°C and adding 1,4-butanediol, and then heating the system to 85°C and reacting for 5 hours to obtain isocyanate-terminated polyurethane; the mixed solvent 1 is composed of xylene, butyl acetate, and cyclohexanone in a volume ratio of 2:2.7:1; in the isocyanate-terminated polyurethane system, the molar ratio of hydroxyl groups provided by polyethylene glycol 2000 and 1,4-butanediol to isocyanate groups provided by isocyanate is 1:1.6;

[0035] Under an argon environment, an organic polysilazane and tetrahydrofuran are uniformly mixed, and then isocyanate-terminated polyurethane is added, the temperature is raised to 35° C. and the reaction is carried out for 12 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a polyurethane-modified organic polysilazane; under an argon environment, a polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene, perfluoromethyl vinyl ether and tetrahydrofuran are uniformly mixed, and then a Karstedt catalyst is added, the temperature is raised to 90° C. and the reaction is carried out for 60 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a fluorine-modified organic polysilazane; when preparing the polyurethane-modified organic polysilazane, the reaction mass ratio of the organic polysilazane and the isocyanate-terminated polyurethane is 1:0.4; when preparing the fluorine-modified organic polysilazane, the reaction mass ratio of the polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene and perfluoromethyl vinyl ether is 1:0.04:0.07:0.03;

[0036] Step 4: γ-aminopropyltriethoxysilane and 3-chloropropyltriethoxysilane are respectively added to the mixed solvent 2, and ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2; nano-silica is respectively added to anhydrous ethanol, ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2, and then the temperature is raised to 50°C, and then modified liquid 1 and modified liquid 2 are added dropwise, and the reaction is continued for 5 hours and aged for 5 hours. After the reaction is completed, the mixture is centrifuged, washed, and vacuum dried to obtain amino-modified nano-silica and chloropropyl-modified nano-silica, respectively;

[0037] The amino-modified nano-silica and the chloropropyl-modified nano-silica were then added to anhydrous ethanol, uniformly dispersed by ultrasonication, stirred in a water bath at 45°C for reaction for 5 hours, aged for 5 hours, and after the reaction was completed, centrifuged, washed, and vacuum-dried to obtain amphiphilic nano-silica; the mixed solvent 2 consisted of anhydrous ethanol and water in a volume ratio of 11:1; the reaction mass ratio of γ-aminopropyltriethoxysilane to nano-silica was 0.11:1; the reaction mass ratio of 3-chloropropyltriethoxysilane to nano-silica was 0.18:1; and the reaction mass ratio of amino-modified nano-silica to chloropropyl-modified nano-silica was 1:1;

[0038] The fluorine-modified organic polysilazane, amphiphilic nano-silica and ethyl acetate solvent are mixed evenly, stirred and reacted at 55°C for 5 hours to obtain a wear-resistant and corrosion-resistant coating; the wear-resistant and corrosion-resistant coating is deposited on the surface of a steel plate with a metal reinforcement layer through a cold spray process, and then cured at 140°C for 3 hours to obtain a finished product with a wear-resistant and corrosion-resistant layer; the mixing ratio of ethyl acetate solvent, fluorine-modified organic polysilazane and amphiphilic nano-silica is 30:10:1; cold spray process: the spray gun speed is 120 mm / s, the spraying distance is 30 mm, and the number of spraying times is 5 times; the steel plate thickness is 8 mm; the metal reinforcement layer thickness is 40 μm; and the wear-resistant and corrosion-resistant layer thickness is 70 μm.

[0039] Example 2: Step 1: Smelting and forging a steel raw material to obtain a slab; then sequentially hot rolling, pickling, cold rolling, critical annealing, and leveling to obtain a steel plate; the steel plate raw material comprises the following components, by mass: 0.20% carbon, 4.5% manganese, 0.05% silicon, 0.002% phosphorus, 0.002% sulfur, 0.001% aluminum, 90% iron, and 5.245% impurities; the hot rolling temperature is 1000° C., the cold rolling reduction is 70%, the critical annealing temperature is 725° C., and the leveling reduction is 1.3%;

[0040] Step 2: Select pure copper as the target material, and plate copper on the graphene surface through a magnetron sputtering plating process to obtain copper-coated graphene powder; Place copper, nickel, and titanium in a ball mill respectively, grind for 6 hours, mix evenly, heat to 1900°C for melting, and then spray granulate, cool, and sieve to obtain a metal powder with a particle size of 50 μm. Mix the metal powder with the copper-coated graphene powder, shake and blend for 12 minutes to obtain a metal-reinforced coating; Deposit the metal-reinforced coating on the surface of the steel plate through a cold spray process to obtain a steel plate with a metal reinforcement layer;

[0041] The magnetron sputtering coating process has a pressure of 0.13 Pa and a time of 25 min. The cold spray process has a spray gun speed of 110 mm / s, a spray distance of 27 mm, and 4 spray times.

[0042] Step 3: The preparation process of isocyanate-terminated polyurethane is as follows: dehydrating polyethylene glycol 2000 at 125°C and -0.096 MPa for 2.5 hours, then adding mixed solvent 1 and stirring evenly, heating to 53°C under a nitrogen environment, then adding isocyanate dropwise and stirring thoroughly for 40 minutes, heating to 87°C after stirring for 2.5 hours, then cooling the system to 53°C and adding 1,4-butanediol, and then heating the system to 83°C and reacting for 4.5 hours to obtain isocyanate-terminated polyurethane; the mixed solvent 1 is composed of xylene, butyl acetate, and cyclohexanone in a volume ratio of 2:2.7:1; in the isocyanate-terminated polyurethane system, the molar ratio of hydroxyl groups provided by polyethylene glycol 2000 and 1,4-butanediol to isocyanate groups provided by isocyanate is 1:1.6;

[0043] Under an argon environment, an organic polysilazane and tetrahydrofuran are uniformly mixed, and then isocyanate-terminated polyurethane is added, the temperature is raised to 32° C. and the reaction is carried out for 10 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a polyurethane-modified organic polysilazane; under an argon environment, a polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene, perfluoromethyl vinyl ether and tetrahydrofuran are uniformly mixed, and then a Karstedt catalyst is added, the temperature is raised to 85° C. and the reaction is carried out for 55 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a fluorine-modified organic polysilazane; when preparing the polyurethane-modified organic polysilazane, the reaction mass ratio of the organic polysilazane and the isocyanate-terminated polyurethane is 1:0.4; when preparing the fluorine-modified organic polysilazane, the reaction mass ratio of the polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene and perfluoromethyl vinyl ether is 1:0.04:0.07:0.03;

[0044] Step 4: γ-aminopropyltriethoxysilane and 3-chloropropyltriethoxysilane are respectively added to the mixed solvent 2, and ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2; nano-silica is respectively added to anhydrous ethanol, ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2, and then the temperature is raised to 45°C, and then modified liquid 1 and modified liquid 2 are added dropwise, and the reaction is continued for 4.5 hours and aged for 4.5 hours. After the reaction is completed, the mixture is centrifuged, washed, and vacuum dried to obtain amino-modified nano-silica and chloropropyl-modified nano-silica, respectively;

[0045] The amino-modified nano-silica and the chloropropyl-modified nano-silica were then added to anhydrous ethanol, and after ultrasonic dispersion, the mixture was stirred in a water bath at 42° C. for reaction for 4.5 hours and aged for 4.5 hours. After the reaction, the mixture was centrifuged, washed, and vacuum-dried to obtain amphiphilic nano-silica. The mixed solvent 2 consisted of anhydrous ethanol and water in a volume ratio of 11:1. The reaction mass ratio of γ-aminopropyltriethoxysilane to nano-silica was 0.11:1. The reaction mass ratio of 3-chloropropyltriethoxysilane to nano-silica was 0.18:1. The reaction mass ratio of amino-modified nano-silica to chloropropyl-modified nano-silica was 1:1.

[0046] The fluorine-modified organic polysilazane, amphiphilic nano-silica and ethyl acetate solvent are mixed evenly, stirred and reacted at 50°C for 4 hours to obtain a wear-resistant and corrosion-resistant coating; the wear-resistant and corrosion-resistant coating is deposited on the surface of a steel plate with a metal reinforcement layer through a cold spray process, and then cured at 135°C for 2.5 hours to obtain a finished product with a wear-resistant and corrosion-resistant layer; the mixing ratio of ethyl acetate solvent, fluorine-modified organic polysilazane and amphiphilic nano-silica is 30:10:1; cold spray process: the spray gun speed is 110 mm / s, the spraying distance is 27 mm, and the number of spraying is 4 times; the steel plate thickness is 8 mm; the metal reinforcement layer thickness is 40 μm; the wear-resistant and corrosion-resistant layer thickness is 70 μm.

[0047] Example 3: Step 1: Smelting and forging a steel raw material to obtain a slab; then sequentially hot rolling, pickling, cold rolling, critical annealing, and leveling to obtain a steel plate; the steel plate raw material comprises the following components, by mass: 0.20% carbon, 4.5% manganese, 0.05% silicon, 0.002% phosphorus, 0.002% sulfur, 0.001% aluminum, 90% iron, and 5.245% impurities; the hot rolling temperature is 850° C., the cold rolling reduction is 60%, the critical annealing temperature is 700° C., and the leveling reduction is 1.0%;

[0048] Step 2: Select pure copper as the target material, and plate copper on the graphene surface through a magnetron sputtering plating process to obtain copper-coated graphene powder; Place copper, nickel, and titanium in a ball mill respectively, grind for 5 hours, mix them evenly, heat to 1800°C for melting, and then spray granulate, cool, and sieve to obtain a metal powder with a particle size of 50 μm. Mix the metal powder with the copper-coated graphene powder, shake and blend for 10 minutes to obtain a metal-reinforced coating; Deposit the metal-reinforced coating on the surface of the steel plate through a cold spray process to obtain a steel plate with a metal reinforcement layer;

[0049] The magnetron sputtering coating process has a pressure of 0.10 Pa and a time of 20 min. The cold spraying process has a spray gun speed of 100 mm / s, a spray distance of 25 mm, and three spray times.

[0050] Step 3: The preparation process of isocyanate-terminated polyurethane is as follows: dehydrating polyethylene glycol 2000 at 120°C and -0.095 MPa for 2 hours, then adding mixed solvent 1 and stirring evenly, heating to 50°C under a nitrogen environment, then adding isocyanate dropwise and stirring thoroughly for 35 minutes, heating to 85°C after stirring for 2 hours, then cooling the system to 50°C and adding 1,4-butanediol, and then heating the system to 80°C and reacting for 4 hours to obtain isocyanate-terminated polyurethane; the mixed solvent 1 is composed of xylene, butyl acetate, and cyclohexanone in a volume ratio of 2:2.7:1; in the isocyanate-terminated polyurethane system, the molar ratio of hydroxyl groups provided by polyethylene glycol 2000 and 1,4-butanediol to isocyanate groups provided by isocyanate is 1:1.6;

[0051] Under an argon environment, an organic polysilazane and tetrahydrofuran are uniformly mixed, and then an isocyanate-terminated polyurethane is added, the temperature is raised to 30° C. and the reaction is carried out for 8 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a polyurethane-modified organic polysilazane; under an argon environment, a polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene, perfluoromethyl vinyl ether and tetrahydrofuran are uniformly mixed, and then a Karstedt catalyst is added, the temperature is raised to 80° C. and the reaction is carried out for 50 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a fluorine-modified organic polysilazane; when preparing the polyurethane-modified organic polysilazane, the reaction mass ratio of the organic polysilazane and the isocyanate-terminated polyurethane is 1:0.4; when preparing the fluorine-modified organic polysilazane, the reaction mass ratio of the polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene and perfluoromethyl vinyl ether is 1:0.04:0.07:0.03;

[0052] Step 4: γ-aminopropyltriethoxysilane and 3-chloropropyltriethoxysilane are respectively added to the mixed solvent 2, and ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2; nano-silica is respectively added to anhydrous ethanol, ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2, and then the temperature is raised to 40°C, and then modified liquid 1 and modified liquid 2 are added dropwise, and the reaction is continued for 4 hours and aged for 4 hours. After the reaction is completed, the mixture is centrifuged, washed, and vacuum dried to obtain amino-modified nano-silica and chloropropyl-modified nano-silica, respectively;

[0053] The amino-modified nano-silica and the chloropropyl-modified nano-silica were then added to anhydrous ethanol, and after ultrasonic dispersion, the mixture was stirred in a water bath at 40°C for 4 hours and aged for 4 hours. After the reaction, the mixture was centrifuged, washed, and vacuum-dried to obtain amphiphilic nano-silica. The mixed solvent 2 consisted of anhydrous ethanol and water in a volume ratio of 11:1. The reaction mass ratio of γ-aminopropyltriethoxysilane to nano-silica was 0.11:1. The reaction mass ratio of 3-chloropropyltriethoxysilane to nano-silica was 0.18:1. The reaction mass ratio of amino-modified nano-silica to chloropropyl-modified nano-silica was 1:1.

[0054] The fluorine-modified organic polysilazane, amphiphilic nano-silica and ethyl acetate solvent are mixed evenly, stirred and reacted at 45°C for 3 hours to obtain a wear-resistant and corrosion-resistant coating; the wear-resistant and corrosion-resistant coating is deposited on the surface of a steel plate with a metal reinforcement layer through a cold spray process, and then cured at 130°C for 2 hours to obtain a finished product with a wear-resistant and corrosion-resistant layer; the mixing ratio of ethyl acetate solvent, fluorine-modified organic polysilazane and amphiphilic nano-silica is 30:10:1; cold spray process: the spray gun speed is 100 mm / s, the spraying distance is 25 mm, and the number of spraying times is 3 times; the steel plate thickness is 8 mm; the metal reinforcement layer thickness is 40 μm; and the wear-resistant and corrosion-resistant layer thickness is 70 μm.

[0055] Comparative Example 1: The metal reinforcement layer is removed, and the rest is the same as Example 1, with the following specific steps: Step 1: The steel raw material is smelted and forged to obtain a slab; the slab is then subjected to hot rolling, pickling, cold rolling, critical annealing, and leveling processes in sequence to obtain a steel plate; the components of the steel plate raw material contain, by mass fraction, 0.20% carbon, 4.5% manganese, 0.05% silicon, 0.002% phosphorus, 0.002% sulfur, 0.001% aluminum, 90% iron, and 5.245% impurities; the hot rolling temperature is 1200° C., the cold rolling reduction is 80%, the critical annealing temperature is 750° C., and the leveling reduction is 1.5%;

[0056] Step 2: The preparation process of isocyanate-terminated polyurethane is as follows: dehydrating polyethylene glycol 2000 at 130°C and -0.098 MPa for 3 hours, then adding mixed solvent 1 and stirring evenly, heating to 55°C under a nitrogen environment, then adding isocyanate dropwise and stirring thoroughly for 45 minutes, heating to 90°C after stirring for 3 hours, then cooling the system to 55°C and adding 1,4-butanediol, and then heating the system to 85°C and reacting for 5 hours to obtain isocyanate-terminated polyurethane; the mixed solvent 1 is composed of xylene, butyl acetate, and cyclohexanone in a volume ratio of 2:2.7:1; in the isocyanate-terminated polyurethane system, the molar ratio of hydroxyl groups provided by polyethylene glycol 2000 and 1,4-butanediol to isocyanate groups provided by isocyanate is 1:1.6;

[0057] Under an argon environment, an organic polysilazane and tetrahydrofuran are uniformly mixed, and then isocyanate-terminated polyurethane is added, the temperature is raised to 35° C. and the reaction is carried out for 12 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a polyurethane-modified organic polysilazane; under an argon environment, a polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene, perfluoromethyl vinyl ether and tetrahydrofuran are uniformly mixed, and then a Karstedt catalyst is added, the temperature is raised to 90° C. and the reaction is carried out for 60 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a fluorine-modified organic polysilazane; when preparing the polyurethane-modified organic polysilazane, the reaction mass ratio of the organic polysilazane and the isocyanate-terminated polyurethane is 1:0.4; when preparing the fluorine-modified organic polysilazane, the reaction mass ratio of the polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene and perfluoromethyl vinyl ether is 1:0.04:0.07:0.03;

[0058] Step 3: γ-aminopropyltriethoxysilane and 3-chloropropyltriethoxysilane are respectively added to the mixed solvent 2, and ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2; nano-silica is respectively added to anhydrous ethanol, ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2, and then the temperature is raised to 50°C, and then modified liquid 1 and modified liquid 2 are respectively added dropwise, and the reaction is continued for 5 hours and aged for 5 hours. After the reaction is completed, the mixture is centrifuged, washed, and vacuum dried to obtain amino-modified nano-silica and chloropropyl-modified nano-silica, respectively;

[0059] The amino-modified nano-silica and the chloropropyl-modified nano-silica were then added to anhydrous ethanol, uniformly dispersed by ultrasonication, stirred in a water bath at 45°C for reaction for 5 hours, aged for 5 hours, and after the reaction was completed, centrifuged, washed, and vacuum-dried to obtain amphiphilic nano-silica; the mixed solvent 2 consisted of anhydrous ethanol and water in a volume ratio of 11:1; the reaction mass ratio of γ-aminopropyltriethoxysilane to nano-silica was 0.11:1; the reaction mass ratio of 3-chloropropyltriethoxysilane to nano-silica was 0.18:1; and the reaction mass ratio of amino-modified nano-silica to chloropropyl-modified nano-silica was 1:1;

[0060] The fluorine-modified organic polysilazane, amphiphilic nano-silica and ethyl acetate solvent are mixed evenly, stirred and reacted at 55°C for 5 hours to obtain a wear-resistant and corrosion-resistant coating; the wear-resistant and corrosion-resistant coating is deposited on the surface of the steel plate through a cold spray process, and then cured at 140°C for 3 hours to obtain a finished product with a wear-resistant and corrosion-resistant layer; the mixing ratio of ethyl acetate solvent, fluorine-modified organic polysilazane and amphiphilic nano-silica is 30:10:1; cold spray process: the spray gun speed is 120 mm / s, the spraying distance is 30 mm, and the number of spraying times is 5 times; the thickness of the steel plate is 8 mm; the thickness of the wear-resistant and corrosion-resistant layer is 70 μm.

[0061] Comparative Example 2: The amphiphilic nano-silica was removed, and the rest was the same as in Example 1, with the following specific steps: Step 1: The steel raw material was smelted and forged to obtain a slab; the slab was then subjected to hot rolling, pickling, cold rolling, critical annealing, and leveling processes in sequence to obtain a steel plate; the content of each component of the steel plate raw material was: by mass fraction, 0.20% carbon, 4.5% manganese, 0.05% silicon, 0.002% phosphorus, 0.002% sulfur, 0.001% aluminum, 90% iron, and 5.245% impurities; the hot rolling temperature was 1200° C., the cold rolling reduction was 80%, the critical annealing temperature was 750° C., and the leveling reduction was 1.5%;

[0062] Step 2: Select pure copper as the target material, and plate copper on the graphene surface through a magnetron sputtering plating process to obtain copper-coated graphene powder; Place copper, nickel, and titanium in a ball mill respectively, grind for 7 hours, mix them evenly, heat to 2000°C for melting, and then spray granulate, cool, and sieve to obtain a metal powder with a particle size of 50 μm. Mix the metal powder with the copper-coated graphene powder, shake and blend for 15 minutes to obtain a metal-reinforced coating; Deposit the metal-reinforced coating on the surface of the steel plate through a cold spray process to obtain a steel plate with a metal reinforcement layer;

[0063] The magnetron sputtering coating process has a pressure of 0.15 Pa and a time of 30 min. The cold spray process has a spray gun speed of 120 mm / s, a spray distance of 30 mm, and 5 spray times.

[0064] Step 3: The preparation process of isocyanate-terminated polyurethane is as follows: dehydrating polyethylene glycol 2000 at 130°C and -0.098 MPa for 3 hours, then adding mixed solvent 1 and stirring evenly, heating to 55°C under a nitrogen environment, then adding isocyanate dropwise and stirring thoroughly for 45 minutes, heating to 90°C after stirring for 3 hours, then cooling the system to 55°C and adding 1,4-butanediol, and then heating the system to 85°C and reacting for 5 hours to obtain isocyanate-terminated polyurethane; the mixed solvent 1 is composed of xylene, butyl acetate, and cyclohexanone in a volume ratio of 2:2.7:1; in the isocyanate-terminated polyurethane system, the molar ratio of hydroxyl groups provided by polyethylene glycol 2000 and 1,4-butanediol to isocyanate groups provided by isocyanate is 1:1.6;

[0065] Under an argon environment, an organic polysilazane and tetrahydrofuran are uniformly mixed, and then isocyanate-terminated polyurethane is added, the temperature is raised to 35° C. and the reaction is carried out for 12 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a polyurethane-modified organic polysilazane; under an argon environment, a polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene, perfluoromethyl vinyl ether and tetrahydrofuran are uniformly mixed, and then a Karstedt catalyst is added, the temperature is raised to 90° C. and the reaction is carried out for 60 hours. After the reaction is completed, the mixture is subjected to rotary evaporation to obtain a fluorine-modified organic polysilazane; when preparing the polyurethane-modified organic polysilazane, the reaction mass ratio of the organic polysilazane and the isocyanate-terminated polyurethane is 1:0.4; when preparing the fluorine-modified organic polysilazane, the reaction mass ratio of the polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene and perfluoromethyl vinyl ether is 1:0.04:0.07:0.03;

[0066] Step 4: Evenly mix the fluorine-modified organic polysilazane and ethyl acetate solvent, stir and react at 55°C for 5 hours to obtain a wear-resistant and corrosion-resistant coating; deposit the wear-resistant and corrosion-resistant coating onto the surface of the steel plate with a metal reinforcement layer through a cold spray process, and then cure it at 140°C for 3 hours to obtain a finished product with a wear-resistant and corrosion-resistant layer; the mixing ratio of ethyl acetate solvent and fluorine-modified organic polysilazane is 3:1; cold spray process: the spray gun speed is 120 mm / s, the spraying distance is 30 mm, and the number of spraying times is 5 times; the steel plate thickness is 8 mm; the metal reinforcement layer thickness is 40 μm; the wear-resistant and corrosion-resistant layer thickness is 70 μm.

[0067] Comparative Example 3: The wear-resistant and corrosion-resistant coating was removed, and the rest was the same as in Example 1, with the following specific steps: Step 1: The steel raw material was smelted and forged to obtain a slab; the slab was then subjected to hot rolling, pickling, cold rolling, critical annealing, and leveling processes in sequence to obtain a steel plate; the components of the steel plate raw material contained, by mass fraction, 0.20% carbon, 4.5% manganese, 0.05% silicon, 0.002% phosphorus, 0.002% sulfur, 0.001% aluminum, 90% iron, and 5.245% impurities; the hot rolling temperature was 1200° C., the cold rolling reduction was 80%, the critical annealing temperature was 750° C., and the leveling reduction was 1.5%;

[0068] Step 2: Select pure copper as the target material, and plate copper on the graphene surface through a magnetron sputtering plating process to obtain copper-coated graphene powder; Place copper, nickel, and titanium in a ball mill respectively, grind for 7 hours, mix them evenly, heat to 2000°C for melting, and then spray granulate, cool, and sieve to obtain a metal powder with a particle size of 50 μm. Mix the metal powder with the copper-coated graphene powder, shake and blend for 15 minutes to obtain a metal-reinforced coating; Deposit the metal-reinforced coating on the surface of the steel plate through a cold spray process to obtain a steel plate with a metal reinforcement layer, i.e., the finished product;

[0069] The magnetron sputtering coating process has a pressure of 0.15 Pa and a time of 30 min. The cold spraying process has a spray gun speed of 120 mm / s, a spray distance of 30 mm, and 5 spray times. The steel plate thickness is 8 mm. The metal reinforcement layer thickness is 40 μm.

[0070] Detection test:

[0071] Hardness test: The finished steel plate prepared in the present invention was used as a sample, and the microstructure of the coating interface was observed using a Zeiss metallographic microscope. The Vickers hardness test was performed in accordance with the GB / T4340.1-2009 standard.

[0072] Yield strength test: The finished steel plate prepared by the present invention was used as a sample, and the yield strength test was performed with reference to GB / T 228.1-2021 standard.

[0073] Wear resistance test: The finished steel plate prepared in the present invention was used as a specimen. Referring to ASTM G65-16 standard, a load of 140 N was applied to the specimen. The rubber rotated at a speed of 250 r / min and the gravel contacted the interface at a speed of 300 g / min. The mass loss of the sample after linear wear was tested as a wear resistance test.

[0074] Water contact angle test: The finished steel plate produced by the present invention was used as a sample. The hydrophobicity and corrosion resistance of the sample were characterized by static water contact angle. The sample surface was polished, cleaned, and dried in sequence. Then, a 2 μl water droplet was added to the sample surface. The water contact angle value was read after the droplet stabilized. Three different locations on each sample were tested, and the average value and standard deviation were calculated. The results are shown in the following table:

[0075] Vickers hardness / HV <![CDATA[Yield strength / MPa > Mass loss / g Water contact angle / ° Example 1 886 688 85 143 Example 2 883 686 87 142 Example 3 881 685 89 140 Comparative Example 1 307 537 102 142 Comparative Example 2 879 685 95 126 Comparative Example 3 845 667 108 105

[0076] Conclusion: The dosage of Examples 1 to 3 remains unchanged, and only some reaction parameters are modified. From the experimental data, it can be seen that there is no significant fluctuation in the performance of the samples.

[0077] Comparative Example 1: The metal reinforcement layer is removed, and the rest is the same as Example 1. It can be seen from the experimental data that compared with Example 1, the Vickers hardness is reduced to 307HV, the yield strength is reduced to 537MPa, and the mass loss is increased to 102g. The reason for this is analyzed as follows: the metal reinforcement layer can significantly improve the hardness and surface strength of the steel plate surface, making the steel plate less likely to be scratched and deformed when subjected to external impact or friction. Therefore, after the metal reinforcement layer is removed, the Vickers hardness is reduced, the yield strength is reduced, and the mass loss is increased.

[0078] Comparative Example 2: The amphiphilic nano-silica was removed, and the rest was the same as in Example 1. It can be seen from the experimental data that the water contact angle was reduced to 126° compared with Example 1. The reason for this is that the amphiphilic nano-silica introduced a chloropropyl group with hydrophobic properties, which interacted with the nano-silica to form a hydrophobic barrier, thereby effectively improving the hydrophobic corrosion resistance of the coating. Therefore, after the amphiphilic nano-silica was removed, the water contact angle was reduced.

[0079] Comparative Example 3: The wear-resistant and corrosion-resistant coating is removed, and the rest is the same as Example 1. It can be seen from the experimental data that compared with Example 1, the Vickers hardness is reduced to 845HV, the yield strength is reduced to 667MPa, the mass loss is increased to 108g, and the water contact angle is reduced to 105°. The reasons are analyzed as follows: the wear-resistant and corrosion-resistant coating contains fluorine-modified organic polysilazane and amphiphilic nano-silica, which can effectively improve the surface strength, wear resistance and hydrophobic corrosion resistance of the steel plate. Therefore, after removing the wear-resistant and corrosion-resistant coating, the Vickers hardness is reduced, the yield strength is reduced, the mass loss is increased, and the water contact angle is reduced.

[0080] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include," "comprise," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0081] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A processing technology for low-silicon and low-sulfur cold-rolled steel sheets, characterized by: The following steps are involved: Step 1: Smelt and forge the steel raw materials to obtain slabs; then the slabs are sequentially hot rolled, pickled, cold rolled, critical annealed, and leveled to obtain steel plates; Step 2: Select pure copper as the target material, and plate copper on the graphene surface through a magnetron sputtering plating process to obtain copper-coated graphene powder; Place copper, nickel, and titanium in a ball mill respectively, grind for 5-7 hours, mix them evenly, heat to 1800-2000°C for melting, and then spray granulate, cool, and sieve to obtain a metal powder with a particle size of 45-70μm. Mix the metal powder with the copper-coated graphene powder, shake and blend for 10-15 minutes to obtain a metal-reinforced coating; Deposit the metal-reinforced coating on the surface of the steel plate through a cold spray process to obtain a steel plate with a metal reinforcement layer; Step 3: Under an argon environment, the organic polysilazane and tetrahydrofuran are mixed evenly, and then the isocyanate-terminated polyurethane is added, the temperature is raised to 30-35°C and the reaction is carried out for 8-12 hours. After the reaction is completed, the polyurethane-modified organic polysilazane is obtained by rotary evaporation; under an argon environment, the polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene, perfluoromethyl vinyl ether and tetrahydrofuran are mixed evenly, and then the Karstedt catalyst is added, the temperature is raised to 80-90°C and the reaction is carried out for 50-60 hours. After the reaction is completed, the fluorine-modified organic polysilazane is obtained by rotary evaporation; Step 4: Evenly mix the fluorine-modified organic polysilazane, amphiphilic nano-silica and ethyl acetate solvent, and stir the reaction at 45-55°C for 3-5 hours to obtain a wear-resistant and corrosion-resistant coating; deposit the wear-resistant and corrosion-resistant coating onto the surface of the steel plate with a metal reinforcement layer through a cold spray process, and then cure it at 130-140°C for 2-3 hours to obtain a finished product with a wear-resistant and corrosion-resistant layer.

2. The processing technology of low-silicon and low-sulfur cold-rolled steel sheet according to claim 1, characterized in that: In step 1, the content of each component of the steel plate raw material is: by mass fraction, 0.20-0.25% carbon, 4.5-6.5% manganese, 0.05-0.08% silicon, 0.002-0.003% phosphorus, 0.002-0.003% sulfur, 0.001-0.002% aluminum, 88-90% iron, and the remainder is impurities; the hot rolling temperature is 850-1200° C., the cold rolling reduction rate is 60-80%, the critical annealing temperature is 700-750° C., and the tempering reduction rate is 1.0-1.5%.

3. The processing technology of a low-silicon and low-sulfur cold-rolled steel sheet according to claim 1, characterized in that: In step 2, the magnetron sputtering coating process: the pressure is 0.10-0.15Pa, and the time is 20-30min; the cold spray process: the spray gun speed is 100-120mm / s, the spraying distance is 25-30mm, and the number of spraying times is 3-5 times.

4. The processing technology of a low-silicon and low-sulfur cold-rolled steel sheet according to claim 1, characterized in that: In step three, when preparing the polyurethane-modified organic polysilazane, the reaction mass ratio of the organic polysilazane and the isocyanate-terminated polyurethane is 1:(0.3-0.5); when preparing the fluorine-modified organic polysilazane, the reaction mass ratio of the polyurethane-modified organic polysilazane, tetrafluoroethylene, hexafluoropropylene, and perfluoromethyl vinyl ether is 1:0.04:(0.06-0.08):0.

03.

5. The processing technology of low-silicon and low-sulfur cold-rolled steel sheet according to claim 4, characterized in that: The preparation process of isocyanate-terminated polyurethane is as follows: polyethylene glycol 2000 is dehydrated at 120-130° C. and -0.095 to -0.098 MPa for 2-3 hours, mixed solvent 1 is added and stirred evenly, the temperature is raised to 50-55° C. under a nitrogen environment, isocyanate is added dropwise and stirred thoroughly for 35-45 minutes, the temperature is raised to 85-90° C. after stirring, the reaction is carried out for 2-3 hours, the system is cooled to 50-55° C., 1,4-butanediol is added, and the system is heated to 80-85° C. and reacted for 4-5 hours to obtain isocyanate-terminated polyurethane.

6. The processing technology of low-silicon and low-sulfur cold-rolled steel sheet according to claim 5, characterized in that: The mixed solvent 1 is composed of xylene, butyl acetate, and cyclohexanone in a volume ratio of 2: (2.5-3.0): 1; in the isocyanate-terminated polyurethane system, the molar ratio of hydroxyl groups provided by polyethylene glycol 2000 and 1,4-butanediol to isocyanate groups provided by isocyanate is 1: (1.5-1.7).

7. The processing technology of low-silicon and low-sulfur cold-rolled steel sheet according to claim 1, characterized in that: In step 4, the preparation process of amphiphilic nano-silica is as follows: γ-aminopropyltriethoxysilane and 3-chloropropyltriethoxysilane are respectively added to the mixed solvent 2, and ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2; the nano-silica is respectively added to anhydrous ethanol, ultrasonically dispersed to obtain modified liquid 1 and modified liquid 2, and then the temperature is raised to 40-50° C., and then the modified liquid 1 and modified liquid 2 are respectively added dropwise, and the reaction is continued for 4-5 hours and aged for 4-5 hours. After the reaction is completed, the reaction is centrifuged, washed, and vacuum dried to obtain amino-modified nano-silica and chloropropyl-modified nano-silica, respectively; Then, amino-modified nano-silica and chloropropyl-modified nano-silica are added to anhydrous ethanol, uniformly dispersed by ultrasonication, stirred in a water bath at 40-45° C. for reaction for 4-5 hours, aged for 4-5 hours, and after the reaction is completed, centrifuged, washed, and vacuum-dried to obtain amphiphilic nano-silica.

8. The processing technology of low-silicon and low-sulfur cold-rolled steel sheet according to claim 7, characterized in that: The mixed solvent 2 is composed of anhydrous ethanol and water in a volume ratio of (10-12):1; the reaction mass ratio of γ-aminopropyltriethoxysilane to nano-silica is (0.10-0.12):1; the reaction mass ratio of 3-chloropropyltriethoxysilane to nano-silica is (0.17-0.20):1; and the reaction mass ratio of amino-modified nano-silica to chloropropyl-modified nano-silica is 1:(1.0-1.1).

9. The processing technology of low-silicon and low-sulfur cold-rolled steel sheet according to claim 1, characterized in that: In step 4, the mixing ratio of ethyl acetate solvent, fluorine-modified organic polysilazane and amphiphilic nano-silica is 30: (8-12): 1; cold spray process: the spray gun speed is 100-120 mm / s, the spraying distance is 25-30 mm, and the number of spraying times is 3-5 times; the steel plate thickness is 6-10 mm; the metal reinforcement layer thickness is 30-50 μm; and the wear-resistant and corrosion-resistant layer thickness is 60-80 μm.

10. A low-silicon, low-sulfur cold-rolled steel sheet, characterized in that: Obtained by processing according to any one of claims 1 to 9.