Steel structure surface rust removal treatment method

Abstract

The invention belongs to the technical field of metal surface treatment, particularly relates to a steel structure surface rust removal treatment method, and solves the problems that a traditional rust removal method is low in efficiency, the thickness of a residual rust layer is not accurately controlled, and the adhesive force of a coating is insufficient. According to the technical scheme, the method is characterized by comprising the steps that the surface of the steel structure is preheated to 50-60 DEG C through an infrared radiator, high-pressure water jet treatment is adopted after cooling, the power density and the pulse frequency are dynamically adjusted in combination with laser rust removal equipment so as to adapt to different residual rust layer thicknesses, real-time monitoring is conducted through an infrared thickness gauge, and finally anti-rust coating operation is conducted. According to the method, efficient and accurate rust layer removal and coating protection are achieved through a multi-step synergistic effect, the steel structure surface treatment quality and the durability of an anti-rust coating are remarkably improved, and the method is mainly suitable for surface maintenance and anti-corrosion engineering of large steel structures such as bridges and buildings.

Description

Technical Field

[0001] The invention belongs to the technical field of metal surface treatment, and particularly relates to a method for removing rust from the surface of a steel structure. Background Art

[0002] In the rust removal process for steel structure surfaces, traditional methods are difficult to adapt to the precise removal needs of different rust layer thicknesses due to fixed processing parameters and a lack of real-time control mechanisms. Mechanical grinding or sandblasting relies on manual experience to adjust pressure and speed, which can easily lead to residual rust or excessive damage to the substrate. Single processes (such as high-pressure water jets or chemical cleaning alone) are inefficient for thick rust layers or complex structures and cannot dynamically match the degree of rust. In addition, existing technologies generally lack real-time thickness detection methods, and the treatment effect relies on offline measurement, resulting in process interruptions and repeated operations, affecting overall efficiency. The above problems are particularly prominent in scenarios where the rust layer thickness varies significantly, restricting the treatment quality and the protective life of the coating. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for rust removal on the surface of steel structures. By preheating to optimize the surface state, combining high-pressure water jet pretreatment with dynamic parameter adjustment of laser rust removal, and supplemented by real-time infrared thickness measurement feedback, efficient removal and precise control of the rust layer can be achieved. The synergy of multiple processes significantly improves treatment efficiency and consistency, reduces substrate damage, provides a uniform and clean surface for subsequent anti-rust coating, and enhances coating adhesion and long-term anti-corrosion effect.

[0004] In order to achieve these objects and other advantages of the present invention, a method for rust removal on the surface of a steel structure is provided, comprising the following steps: 1) Use infrared radiators to preheat the surface of the steel structure to 50-60°C; 2) After the surface temperature of the steel structure drops to 40-45°C, the preheated steel structure surface is treated by a high-pressure water jet device with a spray pressure of 20-50 MPa; 3) Use laser rust removal equipment to treat the surface of the steel structure treated with high-pressure water, and use an infrared thickness gauge to detect the thickness of the residual rust layer in real time, and dynamically adjust the operation parameters: When the thickness of the residual rust layer is ≤0.05mm, 10J / cm 2 ≦Laser power density<15J / cm 2 , 100Hz≦pulse frequency<200Hz; When the residual rust thickness is 0.05mm<0.15mm, 15J / cm 2 ≦Laser power density<25J / cm 2 , 200Hz≦pulse frequency<400Hz; When the residual rust thickness is 0.15mm≤0.3mm, 25J / cm2 ≦Laser power density<30J / cm 2 , 400Hz≦pulse frequency<500Hz; When the thickness of the residual rust layer is ≥0.3mm, 30J / cm 2 ≦Laser power density<35J / cm 2 , 500Hz≤pulse frequency<600Hz, and at the same time, compressed air or nitrogen is delivered to the laser action area as auxiliary cooling gas; 4) Apply anti-rust coating on the surface of the steel structure after laser treatment.

[0005] Preferably, in the steel structure surface rust removal treatment method, the preheating wavelength is 2-5 μm and the radiation power is 0.8-1.5 W / cm 2 Infrared radiator with a radiation distance of 200-400mm; During the preheating process, the surface temperature distribution of the steel structure is monitored in real time by a thermal imager, and the operating parameters are adjusted dynamically: If the local temperature is greater than 60°C, reduce the radiation power in that area to 0.5-0.8W / cm 2 ; If the local temperature is 50-60°C, maintain the current radiation power; If the local temperature is less than 50°C, increase the radiation power in that area to 1.5-2.0W / cm 2 .

[0006] Preferably, in the above-mentioned method for removing rust from the surface of a steel structure, the jet pressure of the high-pressure water jet device is adjusted according to the thickness of the rust layer, and the specific adjustment method is: When the rust layer thickness is less than 0.1mm, the spraying pressure is 20-30MPa; When the rust layer thickness is 0.1mm≤≤0.3mm, the injection pressure is 30-40MPa; When the rust layer thickness is greater than 0.3mm, the spray pressure is 40-45MPa; The distance between the nozzle of the high-pressure water jet device and the surface of the steel structure is maintained at 100-300mm, and the spraying is performed at 50-70° along the normal direction of the steel structure surface, and the spraying movement speed is 0.5-1.2m / s.

[0007] Preferably, in the above-mentioned method for removing rust from the surface of a steel structure, the water sprayed by the high-pressure water jet device contains a composite corrosion inhibitor, has a pH value of 8.5-9.5, and a water temperature of 30-40°C; The composite corrosion inhibitor is composed of the following components in parts by weight: 0.5-1.2 parts of sodium bicarbonate, 0.3-0.8 parts of sodium dodecylbenzenesulfonate, 0.05-0.15 parts of sodium molybdate and 0.01-0.05 parts of benzotriazole; The preparation method of the composite corrosion inhibitor is as follows: sodium bicarbonate, sodium dodecylbenzene sulfonate, and sodium molybdate are dissolved in deionized water at 40-50°C in sequence, stirred for 30 minutes, and then benzotriazole is added and stirred for 20 minutes until it is completely dissolved. pH sensor, conductivity sensor and Fe 3+ Concentration detector, and according to the detected pH value, conductivity and Fe 3+ The concentration was adjusted as follows: When the pH value is less than 8.5, add sodium bicarbonate solution until the pH value returns to 8.5-9.5; When 9.5>pH≥8.5, no adjustment is made; When the pH value is ≥9.5, add 0.05-0.1% citric acid solution to adjust the pH value to 8.5-9.5; When the conductivity is ≥2000μS / cm, according to Fe 3+ Based on the concentration test results, the amount of sodium dodecylbenzenesulfonate to be added can be corrected as follows: When Fe 3+ When the concentration is ≤3mmol / L, every 1mmol / L Fe 3+ , reduce the addition amount of sodium dodecylbenzenesulfonate in the composite corrosion inhibitor by 0.15-0.25%; When 3mmol / L<Fe 3+ When the concentration is ≤5mmol / L, every 1mmol / L Fe detected 3+ , reduce the addition amount of sodium dodecylbenzenesulfonate in the composite corrosion inhibitor by 0.1-0.15%; When Fe 3+ When the concentration is greater than 5mmol / L, stop adding sodium dodecylbenzenesulfonate to the composite corrosion inhibitor and replace at least 1 / 3 of the volume of the solution in the circulating water tank; When the conductivity is less than 2000 μS / cm, sodium dodecylbenzene sulfonate is added to the composite corrosion inhibitor according to the initial ratio without correction.

[0008] Preferably, in the steel structure surface rust removal treatment method, the nozzle for delivering compressed air or nitrogen to the laser action area has a coaxially arranged inner channel and outer channel, the inner channel transmits the laser beam, and the outer channel delivers cooling gas; The gas flow rate ejected from the nozzle is dynamically adjusted according to the laser power density: When 10J / cm 2 ≤Laser power density<25J / cm 2When, the gas flow rate is 30-40L / min; When 25J / cm 2 ≤Laser power density<35J / cm 2 When, the gas flow rate is 50-60L / min; The gas is compressed air or dry nitrogen that has been deoiled and dusted, with a gas purity of ≥99.5%. The first-stage filter and the second-stage filter are arranged in sequence along the gas flow direction in the conveying pipeline. The filtration accuracy of the first-stage filter is 5μm, which is used to remove oil and large particles of impurities; the filtration accuracy of the second-stage filter is 1μm, which is used to remove fine dust.

[0009] Preferably, in the method for removing rust from the surface of a steel structure, the anti-rust coating operation includes the following steps: Apply epoxy zinc-rich primer on the surface of the laser-treated steel structure. The mass fraction of zinc powder in the epoxy zinc-rich primer is 60-75%, and the ambient humidity before coating is ≤65%; After applying epoxy zinc-rich primer, apply polyurethane topcoat on the surface of the steel structure; After painting is completed, place the steel structure in an environment with a temperature of 50-60℃ and a humidity of ≤50% for curing for 24-48 hours.

[0010] Preferably, in the steel structure surface rust removal treatment method, the zinc powder in the epoxy zinc-rich primer has a particle size distribution of 5-25 μm, wherein the zinc powder with a particle size of ≤10 μm accounts for ≥60%; The coating temperature of epoxy zinc-rich primer is 15-35℃, and electrostatic spraying equipment is used for spraying at a pressure of 0.3-0.6MPa, the spray gun moving speed is 0.5-1.0m / s, and the spray distance is maintained at 200-400mm; After the epoxy zinc-rich primer is applied, a transition layer is applied on the surface of the epoxy zinc-rich primer, and then a polyurethane topcoat is applied. The transition layer is made by mixing nano-silicon dioxide and epoxy resin, wherein the mass fraction of nano-silicon dioxide is 4.8-6.1% and the balance is epoxy resin. Applying the transition layer includes the following steps: Use electrostatic spraying equipment to spray at a pressure of 0.2-0.4MPa, the spray gun moving speed is 0.8-1.2m / s, the spray distance is maintained at 150-250mm, and the spraying direction is 45-65° to the coating direction of the epoxy zinc-rich primer; After spraying, cure at 60-80℃ for 5-10 minutes to form a tight sealing layer, seal the gaps between zinc powder and inhibit oxidation.

[0011] Preferably, in the method for removing rust from the surface of a steel structure, the polyurethane topcoat is prepared by mixing a main agent and a curing agent in a mass ratio of 4-5:1, the main agent is a hydroxyl acrylic resin having a hydroxyl content of 2.5-3.5%, and the curing agent is a hexamethylene diisocyanate trimer prepolymer having an NCO content of 18-22%; After the main agent and curing agent are mixed, nano-silica defoamer is added to the slurry. The amount of defoamer added is 0.1-0.3% of the total slurry mass, and the particle size is 10-30nm. It is then stirred at a speed of 800-1200r / min for 5-10min using a high-speed disperser. Use airless spraying equipment to spray polyurethane topcoat at a pressure of 0.4-0.8MPa, the spray gun moving speed is 0.3-0.6m / s, the spray distance is maintained at 300-500mm, and the spraying direction is perpendicular to the coating direction of epoxy zinc-rich primer.

[0012] Preferably, in the method for removing rust from the surface of a steel structure, a steel structure surface drying step is added between step 2) and step 3), and the steel structure surface drying step includes: Use a high-pressure vortex compressed air spray gun to continuously blow the steel structure surface at a pressure of 0.5-1.0 MPa and a blowing angle of 20-40° for 15-30 seconds; After purging, the steel structure surface is dried by a medium-wave infrared radiation device. The infrared device emits a wavelength of 2.5-4.0μm and a power density of 1.5-2.5W / cm 2 , radiation distance 150-300mm, drying time 40-80s, control the surface temperature of the steel structure ≤50℃, residual moisture on the surface after drying ≤0.05g / m 2 .

[0013] Preferably, in the method for removing rust from the surface of a steel structure, a steel structure surface treatment step is added between step 3) and step 4), and the steel structure surface treatment step includes: The laser-treated steel structure surface is purged using a pulsed compressed air jet device with a purge pressure of 0.3-0.6 MPa, a jet angle of 30-50°, a pulse frequency of 0.5-2 Hz, and a purge time of 5-15 seconds. After purging, the steel structure surface is dried using a far-infrared radiator with a wavelength of 8-12μm and a radiation power density of 0.5-1.0W / cm 2 , drying time 2-5min, after drying the surface humidity of the steel structure ≤3%; After drying, the steel structure surface is sprayed with a non-ionic surfactant solution consisting of the following components in parts by weight: 95-98 parts of deionized water, 1.5-2.5 parts of fatty alcohol polyoxyethylene ether, 0.3-0.8 parts of siloxane coupling agent and 0.1-0.3 parts of sodium citrate; Spraying amount is 10-20g / m 2 After standing for 30-60 seconds, use a negative pressure liquid suction device to remove excess liquid at a vacuum degree of -0.05~-0.08MPa; After absorbing the liquid, the UV curing equipment was used with a wavelength of 365nm and an irradiation intensity of 80-120mW / cm 2 Irradiate for 10-20s to form a siloxane cross-linked activation layer with a thickness of 50-200nm on the surface of the steel structure.

[0014] The present invention has at least the following beneficial effects: The present invention uses infrared preheating to soften the rust layer, high-pressure water jets to preliminarily remove the loose rust layer, and laser dynamic adaptation to accurately peel off the residual rust layer thickness. Combined with real-time thickness measurement feedback, this achieves efficient removal of the rust layer (residual thickness as low as 0.008mm) and precise control, avoiding the problems of low efficiency of a single process or damage to the substrate. Multiple steps work together to provide a clean and uniform surface for the anti-rust coating, significantly improving the coating adhesion (up to 5B) and corrosion resistance (salt spray rust area ≤ 0.5%), and is suitable for complex working conditions of large steel structures.

[0015] The present invention uses a specific wavelength (2-5μm) infrared radiator to work with a thermal imager, and dynamically adjusts the radiation power (0.5-2.0W / cm 2 ), ensure that the surface temperature of the steel structure is evenly controlled at 50-60℃, avoid local overheating that causes degradation of substrate performance or insufficient preheating that affects the softening effect of the rust layer, and improve the consistency and stability of subsequent high-pressure water jet and laser treatment.

[0016] The present invention adjusts the high-pressure water jet pressure (20-45MPa) according to the thickness of the rust layer, and combines the optimization of the nozzle distance (100-300mm), angle (50-70°) and movement speed (0.5-1.2m / s) to achieve targeted cleaning of surfaces with different degrees of rust. This ensures the effective stripping of thick rust layers and avoids excessive scouring of thin rust layers that damages the substrate, thereby improving treatment efficiency and safety.

[0017] The composite corrosion inhibitor (sodium bicarbonate + sodium dodecylbenzene sulfonate, etc.) of the present invention inhibits secondary corrosion of the substrate during high-pressure water jetting by adjusting the pH value (8.5-9.5) and conductivity; Fe 3+ The concentration linkage controls the amount of sodium dodecylbenzenesulfonate added to avoid reagent waste and prevent the accumulation of pollutants in the circulating water, extending the service life of the solution. At the same time, it improves the surface cleanliness after rust removal and provides a stable base surface for laser processing.

[0018] The coaxial dual-channel nozzle design (laser inside, cooling gas outside) and dynamic flow adjustment (30-60L / min) of the present invention ensure effective cooling of the heat-affected zone during laser treatment, avoiding re-oxidation of the rust layer or thermal damage to the substrate caused by high temperature; two-stage filtration (5μm+1μm) ensures gas cleanliness (purity ≥99.5%), reduces laser energy loss and impurity processing, and improves rust removal accuracy and equipment operation reliability.

[0019] The epoxy zinc-rich primer (zinc powder mass fraction 60-75%) of the present invention provides electrochemical anti-corrosion protection, and humidity control (≤65%) before coating prevents blistering of the coating. The polyurethane topcoat enhances weather resistance, and the curing environment (50-60°C, humidity ≤50%) promotes full cross-linking of the coating to form a dense anti-corrosion layer. The rust area in the salt spray test is reduced by more than 90% compared with the traditional process.

[0020] The zinc powder particle size of the present invention is optimized (≤10μm, accounting for ≥60%) to enhance the conductivity and coverage of the primer; the transition layer (nano-silica + epoxy resin) is cross-sprayed and cured at low temperature (60-80°C) to seal the gaps between the zinc powder and inhibit oxidation, forming a hermetic sealing layer, thereby improving the coating's impermeability and adhesion.

[0021] The precise ratio (4-5:1) of the polyurethane topcoat main agent and curing agent and the addition of a nano-defoaming agent (10-30nm) ensure a uniform, bubble-free coating. The vertical spraying direction and airless spraying process (0.4-0.8MPa) optimize the thickness distribution, forming a protective layer with a high cross-linking density (NCO content 18-22%), significantly improving weather resistance and mechanical strength.

[0022] The present invention combines high-pressure vortex air blowing (0.5-1.0MPa) with medium-wave infrared drying (wavelength 2.5-4.0μm) to quickly remove residual moisture on the surface after high-pressure water jet (≤0.05g / m 2 ), to prevent water vapor from interfering with laser energy absorption or causing secondary rust, provide a dry and clean base surface for laser processing, and shorten the process interval time.

[0023] The present invention uses pulsed compressed air blowing (0.3-0.6MPa) to remove laser treatment residues, and far-infrared drying to control humidity (≤3%); a non-ionic surfactant solution and ultraviolet curing (365nm) form a siloxane cross-linked activation layer (50-200nm thick), which improves surface wettability (contact angle 100-120°) and chemical bonding ability, making the coating adhesion ≥10MPa, which is more than 50% higher than traditional processes.

[0024] Other advantages, objectives and features of the present invention will be reflected in part from the following description and will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0026] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0027] A method for removing rust from the surface of a steel structure comprises the following steps: 1) Use infrared radiators to preheat the steel structure surface to 50-60°C; during the preheating process, use a thermal imager to ensure surface temperature uniformity (temperature difference ≤ ±2°C); 2) After the surface temperature of the steel structure drops to 40-45°C, the preheated steel structure surface is treated using a high-pressure water jet device with a spray pressure of 20-50MPa. After preheating, the surface temperature is cooled by natural convection for 5-15 minutes (based on a 10mm thick steel plate) at an ambient temperature ≤35°C, and an infrared thermometer is used for real-time monitoring until the surface temperature stabilizes within the range of 40-45°C. If the ambient temperature is >35°C, the cooling time needs to be extended to 20-30 minutes or compressed air should be used to assist cooling (pressure ≤0.2MPa, purge angle 30-45°, distance ≥500mm). Cooling can prevent thermal stress cracks in the substrate caused by the high-pressure water jet and keep the rust layer softened. 3) Use laser rust removal equipment to treat the surface of the steel structure treated with high-pressure water, and use an infrared thickness gauge to detect the thickness of the residual rust layer in real time, and dynamically adjust the operation parameters: When the thickness of the residual rust layer is ≤0.05mm, 10J / cm 2 ≦Laser power density<15J / cm 2 , 100Hz≦pulse frequency<200Hz; When the residual rust thickness is 0.05mm<0.15mm, 15J / cm 2 ≦Laser power density<25J / cm 2 , 200Hz≦pulse frequency<400Hz; When the residual rust thickness is 0.15mm≤0.3mm, 25J / cm 2 ≦Laser power density<30J / cm 2 , 400Hz≦pulse frequency<500Hz; When the thickness of the residual rust layer is ≥0.3mm, 30J / cm 2 ≦Laser power density<35J / cm 2, 500Hz≤ pulse frequency<600Hz, and at the same time, compressed air or nitrogen is delivered to the laser action area as auxiliary cooling gas; when the power density is ≥35J / cm 2 When the substrate is micro-melted, the surface of the substrate will be slightly melted, resulting in a roughness of Ra>5μm.

[0028] 4) Apply anti-rust coating on the surface of the steel structure after laser treatment.

[0029] Use infrared radiators to preheat the steel structure surface to 50°C, 55°C, or 60°C, and then naturally cool it to 40°C, 43°C, or 45°C. The infrared radiators can be mounted on adjustable brackets, 200-400mm from the steel structure surface, and the radiation power can be adjusted to achieve uniform temperature.

[0030] The high-pressure water jet device is activated after the surface temperature drops to 40-45°C. The nozzle sprays at an angle of 50°, 60°, or 70° along the surface normal, with a speed adjustable to 0.5m / s, 0.8m / s, or 1.2m / s. The jet pressure is selected based on the thickness of the rust layer, for example, 20-30MPa for thin rust layers and 30-45MPa for thicker layers.

[0031] The laser equipment adjusts the operating parameters according to the real-time detection of the residual rust layer thickness, and simultaneously delivers compressed air or nitrogen to assist in cooling.

[0032] An anti-rust coating is applied to the surface of the laser-treated steel structure. The coating process includes the conventional steps of applying primer and topcoat, and the specific parameters are implemented according to industry standards.

[0033] This solution uses preheating and high-pressure water jets to remove surface impurities, and the laser dynamically adjusts to adapt to different rust layer thicknesses to ensure efficient rust removal and substrate protection. The anti-rust coating provides basic protection to meet the corrosion protection needs of steel structures.

[0034] In another embodiment, in the steel structure surface rust removal treatment method, the preheating wavelength is 2-5 μm and the radiation power is 0.8-1.5 W / cm 2 Infrared radiator with a radiation distance of 200-400mm; During the preheating process, the surface temperature distribution of the steel structure is monitored in real time by a thermal imager, and the operating parameters are adjusted dynamically: If the local temperature is greater than 60°C, reduce the radiation power in that area to 0.5-0.8W / cm 2 ; If the local temperature is 50-60°C, maintain the current radiation power; If the local temperature is less than 50°C, increase the radiation power in that area to 1.5-2.0W / cm 2 .

[0035] The wavelength of the infrared radiator can be selected as 2μm, 3μm or 5μm, and the power density can be set to 0.8W / cm 2 , 1.2W / cm 2 or 1.5W / cm 2 The radiation distance can be adjusted to 200mm, 300mm, or 400mm. The infrared emitter can be a standard commercially available model, such as a shortwave or mediumwave infrared heater. It is mounted on an adjustable bracket, fixed 200-400mm in front of the steel structure surface. The radiation angle is controlled by a servo motor. The emitter power module can be integrated with a temperature feedback interface to connect with the thermal imager data.

[0036] The thermal imager collects temperature distribution images of the steel structure surface in real time, and the data is transmitted to the control terminal. The software algorithm identifies local temperature abnormal areas (such as temperature > 60°C or < 50°C) and generates adjustment instructions.

[0037] When the local temperature is greater than 60°C, the radiation power can be reduced to 0.5W / cm 2 , 0.6W / cm 2 or 0.8W / cm 2 When the temperature is 50-60℃, maintain the current power (0.8-1.5W / cm 2 ); When the temperature is less than 50℃, the power can be increased to 1.5W / cm 2 , 1.8W / cm 2 or 2.0W / cm 2 The adjustment command is output to the infrared radiator power supply through the PWM module of the control system, and the response time is ≤1s. For example, when the temperature of a certain area is detected to be 62℃, the radiation power is increased from 1.2W / cm 2 Reduced to 0.8W / cm 2 If the temperature of a certain area is 48℃, the power will be 1.0W / cm 2 Increased to 1.5W / cm 2 .

[0038] This solution uses real-time monitoring with a thermal imager and dynamic power adjustment to ensure uniform preheating temperature on the steel structure surface, avoid local overheating that could degrade material properties or insufficient preheating that could affect subsequent processing, and improve process stability and consistency.

[0039] In another embodiment, in the steel structure surface rust removal treatment method, the rust layer thickness is obtained by pre-detection equipment and transmitted to the high-pressure water jet control system in real time. The injection pressure of the high-pressure water jet device is adjusted according to the rust layer thickness, and the specific adjustment method is: When the rust layer thickness is less than 0.1mm, the spraying pressure is 20-30MPa; When the rust layer thickness is 0.1mm≤≤0.3mm, the injection pressure is 30-40MPa; When the rust layer thickness is greater than 0.3mm, the spray pressure is 40-45MPa; The distance between the nozzle of the high-pressure water jet device and the surface of the steel structure is maintained at 100-300mm, and the spraying is performed at 50-70° along the normal direction of the steel structure surface, and the spraying movement speed is 0.5-1.2m / s.

[0040] The jet pressure of the high-pressure water jet can be set to 20 MPa, 30 MPa, or 45 MPa, depending on the thickness of the rust layer. For example, when the rust layer is less than 0.1 mm thick, the pressure can be set to 20-30 MPa; when the thickness is 0.1-0.3 mm, the pressure can be set to 30-40 MPa; when the thickness exceeds 0.3 mm, the pressure can be adjusted to 40-45 MPa. Pressure regulation can be achieved using a commercially available proportional relief valve. The valve body is installed in the outlet pipe of the high-pressure water pump and automatically adjusts the opening after receiving the rust layer thickness detection signal through the PLC. Rust layer thickness can be measured using a laser thickness gauge or an ultrasonic thickness gauge. The thickness gauge is installed 100-200 mm in front of the water jet nozzle and communicates with the control system in real time.

[0041] The distance between the nozzle and the steel surface can be set to 100mm, 200mm, or 300mm, and the spray angle can be adjusted to 50°, 60°, or 70°. The nozzle can be a standard carbide fan nozzle, secured to the mobile platform via a retractable bracket. The bracket is equipped with an angle dial and distance scale for manual or electric fine-tuning. For example, when treating areas with thick rust, the nozzle distance can be adjusted to 100mm and the angle to 70° to increase the impact force. When treating delicate areas, the distance can be adjusted to 300mm and the angle to 50° to reduce the risk of substrate damage.

[0042] The spray movement speed can be set to 0.5m / s, 0.8m / s, or 1.2m / s. The moving platform utilizes a servo motor-driven linear guide system, mounted parallel to the steel structure surface. The movement speed is controlled by a frequency converter. For example, when treating large, flat areas, the speed is set to 1.2m / s for improved efficiency; when treating welds or grooves, the speed is reduced to 0.5m / s to ensure effective cleaning. The movement path planning software can import a 3D model of the steel structure and automatically generate a cleaning trajectory that covers the entire surface.

[0043] By combining the above parameters, this solution enables targeted cleaning of rust layers of varying thicknesses using high-pressure water jets, avoiding substrate scratches caused by excessive pressure or residual rust caused by insufficient pressure. Precise control of nozzle distance and angle optimizes the impact of the water jet, while speed adjustment balances treatment efficiency and quality. This solution is suitable for rust removal on steel structures with complex surface features, such as bridge beams and tank siding.

[0044] In another embodiment, in the steel structure surface rust removal treatment method, the water sprayed by the high-pressure water jet device contains a composite corrosion inhibitor, has a pH value of 8.5-9.5, and a water temperature of 30-40° C.; wherein the composite corrosion inhibitor is composed of the following components in parts by weight: 0.5-1.2 parts of sodium bicarbonate, 0.3-0.8 parts of sodium dodecylbenzenesulfonate, 0.05-0.15 parts of sodium molybdate and 0.01-0.05 parts of benzotriazole; The preparation method of the composite corrosion inhibitor is as follows: sodium bicarbonate, sodium dodecylbenzene sulfonate, and sodium molybdate are dissolved in deionized water at 40-50°C in sequence, stirred for 30 minutes, and then benzotriazole is added and stirred for 20 minutes until it is completely dissolved. pH sensor, conductivity sensor and Fe 3+ Concentration detector, and according to the detected pH value, conductivity and Fe 3+ The concentration was adjusted as follows: When the pH value is less than 8.5, add sodium bicarbonate solution until the pH value returns to 8.5-9.5; When 9.5>pH≥8.5, no adjustment is made; When the pH value is ≥9.5, add 0.05-0.1% citric acid solution to adjust the pH value to 8.5-9.5; When the conductivity is ≥2000μS / cm, according to Fe 3+ Based on the concentration test results, the amount of sodium dodecylbenzenesulfonate to be added can be corrected as follows: When Fe 3+ When the concentration is ≤3mmol / L, every 1mmol / L Fe 3+ , reduce the addition amount of sodium dodecylbenzenesulfonate in the composite corrosion inhibitor by 0.15-0.25%; When 3mmol / L<Fe 3+ When the concentration is ≤5mmol / L, every 1mmol / L Fe detected 3+ , reduce the addition amount of sodium dodecylbenzenesulfonate in the composite corrosion inhibitor by 0.1-0.15%; When Fe 3+ When the concentration is greater than 5mmol / L, stop adding sodium dodecylbenzenesulfonate to the composite corrosion inhibitor and replace at least 1 / 3 of the volume of the solution in the circulating water tank; When the conductivity is less than 2000 μS / cm, sodium dodecylbenzene sulfonate is added to the composite corrosion inhibitor according to the initial ratio without correction.

[0045] The composite corrosion inhibitor can contain 0.5, 0.8, or 1.2 parts sodium bicarbonate, 0.3, 0.5, or 0.8 parts sodium dodecylbenzenesulfonate, 0.05, 0.1, or 0.15 parts sodium molybdate, and 0.01, 0.03, or 0.05 parts benzotriazole. To prepare the corrosion inhibitor, sodium bicarbonate, sodium dodecylbenzenesulfonate, and sodium molybdate can be dissolved in deionized water at 40°C, 45°C, or 50°C, respectively. After stirring for 30 minutes, benzotriazole is added and stirring continues for 20 minutes. The dissolution container can be a heated enameled reactor, and the agitator speed can be set to 200-400 rpm.

[0046] pH sensor, conductivity sensor and Fe 3+ Concentration detector. The pH sensor can be glass electrode type, with a range of 0-14 and an accuracy of ±0.1; Fe 3+ The detector can use an online detection device based on the principle of spectrophotometry with a range of 0-10mmol / L. When the pH value is lower than 8.5, a 5% sodium bicarbonate solution can be automatically added to restore the pH to 8.5-9.5; when the pH value exceeds 9.5, a 0.05% or 0.1% citric acid solution can be added to adjust the pH. The conductivity threshold is set to 2000μS / cm. When the conductivity exceeds this value, the Fe 3+ Concentration adjustment of the amount of sodium dodecylbenzenesulfonate added: Fe 3+ For concentrations between 0-3 mmol / L, reduce the dosage by 0.15-0.25% for every 1 mmol / L. For concentrations between 3-5 mmol / L, reduce the dosage by 0.1-0.15%. If the concentration exceeds 5 mmol / L, stop adding and replace at least one-third of the tank solution. The sensor can be installed on the side wall of the circulating water tank or in the return line, and linked to the automatic dosing pump.

[0047] The solution replacement of the circulating water tank can be achieved by controlling the discharge port through an electric ball valve, and the replacement amount is monitored by a level meter. 3+ When the concentration reaches 6 mmol / L, the control system opens the drain valve to discharge one-third of the solution and simultaneously replenishes the solution with an equal amount of freshly prepared corrosion inhibitor solution. This replenishing solution is delivered to the water tank via a metering pump from a reservoir with a capacity of 500L or 1000L, depending on system requirements. During the replacement process, conductivity and pH are monitored in real time to ensure that the new solution parameters meet the requirements.

[0048] Through the above control mechanism, the ratio and pH value of the composite corrosion inhibitor can adapt to different corrosion conditions, inhibit secondary corrosion and extend the service life of the water circulation system. 3+Dynamic concentration adjustment reduces inhibitor waste, while solution replacement rules prevent pollutant accumulation, ensuring the stability and environmental friendliness of high-pressure water jet treatment. This solution is suitable for continuously operating steel structure surface treatment production lines.

[0049] In another embodiment, in the steel structure surface rust removal treatment method, the nozzle for delivering compressed air or nitrogen to the laser action area has a coaxially arranged inner channel and outer channel, the inner channel transmits the laser beam, and the outer channel delivers cooling gas; The gas flow rate ejected from the nozzle is dynamically adjusted according to the laser power density: When 10J / cm 2 ≤Laser power density<25J / cm 2 When, the gas flow rate is 30-40L / min; When 25J / cm 2 ≤Laser power density<35J / cm 2 When, the gas flow rate is 50-60L / min; The gas is compressed air or dry nitrogen that has been deoiled and dusted, with a gas purity of ≥99.5%. The first-stage filter and the second-stage filter are arranged in sequence along the gas flow direction in the conveying pipeline. The filtration accuracy of the first-stage filter is 5μm, which is used to remove oil and large particles of impurities; the filtration accuracy of the second-stage filter is 1μm, which is used to remove fine dust.

[0050] The inner channel of the coaxial nozzle can be constructed from a high-temperature ceramic tube with an inner diameter of 2mm, 3mm, or 5mm for transmitting the laser beam. The outer channel can be configured as an annular gap structure with a gap width of 1mm, 2mm, or 3mm for conveying cooling gas. The nozzle as a whole can be installed at the output end of the laser device and connected to the laser head via a flange to ensure that the inner channel is strictly coaxial with the laser optical path. The gas inlet of the outer channel can be connected to a compressed air or nitrogen supply line equipped with a flow meter and a regulating valve. For example, when processing high-power lasers, the outer channel gap is selected to be 3mm to increase gas flow, while at low power, it is adjusted to 1mm to conserve gas consumption.

[0051] The coaxial laser nozzle can use the IPG Photonics YLS-ECO series standard nozzle (commercially available product). Its inner channel transmits the laser beam, and the outer channel transmits the cooling gas. The gas flow rate is dynamically adjusted to 35L / min (<25J / cm 2 ) or 55 L / min (≥25 J / cm 2 ) The gas flow rate can be dynamically adjusted according to the laser power density. When the laser power density is 10J / cm 2 Up to 25J / cm 2The gas flow rate can be set to 30L / min, 35L / min or 40L / min; the power density is 25J / cm 2 Up to 35J / cm 2 When the laser power density is 15J / cm2, the flow rate can be adjusted to 50L / min, 55L / min or 60L / min. The flow rate can be adjusted by a proportional solenoid valve. The valve body is installed in the gas pipeline and automatically adjusts the opening after receiving the power signal from the laser control system. For example, the laser power density is adjusted from 15J / cm2 to 25J / cm3. 2 Increased to 28J / cm 2 When the flow rate increases linearly from 35L / min to 55L / min, the heat dissipation requirements and process stability are guaranteed.

[0052] The gas purification system can include two-stage filters. The first-stage filter can use a 5μm precision metal sintered filter element to remove oil and large particles; the second-stage filter can use a 1μm precision fiber filter element to intercept fine dust. The filter can be installed in series in the gas supply pipeline, 1-2m away from the nozzle inlet, for easy maintenance and replacement. The compressed air can come from an oil-free air compressor, and the nitrogen can be bottled high-purity gas, with a purity of ≥99.5%. For example, in a continuous operation environment, check the filter element for blockage every 8 hours and replace it immediately if the pressure difference exceeds 0.1MPa.

[0053] This solution utilizes the aforementioned design, with a coaxial nozzle structure that optimizes the synergistic effect of laser and gas. Dynamic flow adjustment matches different process requirements, while graded filtration ensures gas cleanliness. This reduces the expansion of the heat-affected zone during laser processing, improving rust removal accuracy and equipment reliability. This solution is suitable for the cooling and process control needs of high-power laser cleaning equipment.

[0054] In another embodiment, in the method for removing rust from the surface of a steel structure, applying an anti-rust coating comprises the following steps: Apply epoxy zinc-rich primer on the surface of the laser-treated steel structure. The mass fraction of zinc powder in the epoxy zinc-rich primer is 60-75%, and the ambient humidity before coating is ≤65%; After applying epoxy zinc-rich primer, apply polyurethane topcoat on the surface of the steel structure; After painting is completed, place the steel structure in an environment with a temperature of 50-60℃ and a humidity of ≤50% for curing for 24-48 hours.

[0055] The zinc powder mass fraction in the epoxy zinc-rich primer can be set to 60%, 70%, or 75%. The zinc powder particle size distribution can be selected within the 5-25μm range, with the proportion of zinc powder particles ≤10μm controlled to 60%, 70%, or 80%. The ambient humidity can be maintained at ≤65% using an industrial dehumidifier before coating. The spray gun can be mounted at the end of an automated moving arm, with the arm track positioned parallel to the steel structure surface. The spray path is controlled by a pre-set program.

[0056] The equipment for mixing the main agent and curing agent of polyurethane topcoat can be a high-speed disperser, the speed can be set to 800r / min, 1000r / min or 1200r / min, and the stirring time can be controlled to 5min, 7min or 10min.

[0057] After painting, the steel structure can be placed in a curing chamber. The curing temperature can be set to 50°C, 55°C, or 60°C, and the humidity can be controlled to ≤50% using a desiccant or dehumidification system. The curing time can be set to 24h, 36h, or 48h. The curing chamber can be equipped with temperature and humidity sensors, which are installed at the four corners and the center of the room, and the data is transmitted to the PLC control system in real time. For example, when the temperature fluctuates by more than ±2°C, the heating module automatically compensates; when the humidity exceeds 50%, the auxiliary dehumidification device is activated. Multi-layer shelves can be set up inside the curing chamber, and the steel structures are laid flat on the shelves, with a spacing of 200-300mm to facilitate hot air circulation.

[0058] Through the aforementioned process control, this solution creates a uniform zinc barrier with the epoxy zinc-rich primer, while the polyurethane topcoat provides a weather-resistant protective layer. Curing environmental parameters ensure sufficient crosslinking of the coating, thereby enhancing the overall corrosion resistance and mechanical durability of the steel structure. This solution is suitable for the long-term protection needs of outdoor steel structures such as bridges and ships.

[0059] In another embodiment, in the steel structure surface rust removal treatment method, the zinc powder in the epoxy zinc-rich primer has a particle size distribution of 5-25 μm, of which the zinc powder with a particle size of ≤10 μm accounts for ≥60%; The coating temperature of epoxy zinc-rich primer is 15-35℃, and electrostatic spraying equipment is used for spraying at a pressure of 0.3-0.6MPa, the spray gun moving speed is 0.5-1.0m / s, and the spray distance is maintained at 200-400mm; After the epoxy zinc-rich primer is applied, a transition layer is applied on the surface of the epoxy zinc-rich primer, and then a polyurethane topcoat is applied. The transition layer is made by mixing nano-silicon dioxide and epoxy resin, wherein the mass fraction of nano-silicon dioxide is 4.8-6.1% and the balance is epoxy resin. Applying the transition layer includes the following steps: Use electrostatic spraying equipment to spray at a pressure of 0.2-0.4MPa, the spray gun moving speed is 0.8-1.2m / s, the spray distance is maintained at 150-250mm, and the spraying direction is 45-65° to the coating direction of the epoxy zinc-rich primer; After spraying, it is pre-cured at 60-80°C for 5-10 minutes using an infrared heating device to form a hermetic sealing layer, seal the gaps between the zinc powder and inhibit oxidation.

[0060] The particle size distribution of the zinc powder in the epoxy zinc-rich primer can be set to 5-25μm, of which the proportion of zinc powder with a particle size of ≤10μm can be controlled to 60%, 70%, or 80%. The zinc powder can be commercially available spherical zinc powder with a purity of ≥99%. The coating temperature can be set to 15°C, 25°C, or 35°C. The coating equipment can be a rotary cup electrostatic spray gun. The spray gun pressure can be adjusted to 0.3MPa, 0.5MPa, or 0.6MPa, and the spray gun movement speed can be set to 0.5m / s, 0.8m / s, or 1.0m / s. The spray distance is maintained at 200mm, 300mm, or 400mm. The spray gun can be installed on an automatic moving arm. The moving arm track is laid parallel to the surface of the steel structure. The spray path is generated by a preset program to ensure uniform coverage.

[0061] The transition layer is made by mixing nano-silica and epoxy resin. The mass fraction of nano-silica can be set to 4.8%, 5.5%, or 6.1%, with the remainder being epoxy resin. Nano-silica can be a commercially available product with a particle size of 20-30nm, and the epoxy resin can be a bisphenol A liquid resin. During mixing, the nano-silica can be first dispersed in the epoxy resin, with a stirring speed set to 500-800r / min for 30 minutes. The spraying equipment can be a low-pressure electrostatic spray gun. The spray pressure can be set to 0.2MPa, 0.3MPa, or 0.4MPa, and the spray gun movement speed can be adjusted to 0.8m / s, 1.0m / s, or 1.2m / s. The spray distance should be maintained at 150mm, 200mm, or 250mm, and the spray direction should be at an angle of 45°, 55°, or 65° to the primer coating direction. The spray gun can be fixed to another set of movable arms, alternating with the primer spray equipment.

[0062] The curing step is achieved by an infrared heating device. The infrared radiation wavelength can be set to 2.5μm, 3.5μm or 4.0μm, and the power density can be adjusted to 1.5W / cm 2 , 2.0W / cm 2 or 2.5W / cm 2 The heating device can be installed on an adjustable bracket 150mm, 200mm or 300mm away from the surface of the steel structure. The pre-curing temperature can be set to 60℃, 70℃ or 80℃, and the time can be controlled to 5min, 8min or 10min. For example, after the transition layer is sprayed, the infrared heating device is heated at 2.0W / cm2 The power density is radiated onto the surface, raising the temperature to 70°C for 8 minutes, forming a closed layer. The heating area can be monitored in real time by the temperature control module, and the power output is automatically adjusted if the temperature fluctuates by more than ±3°C.

[0063] Through the aforementioned process control, this solution effectively seals gaps in the zinc powder with a transition layer, inhibiting oxidation reactions. The pre-curing step enhances coating density, thereby improving the overall coating's impermeability and mechanical strength. This solution is suitable for anti-corrosion projects in steel structures located in marine environments or high-humidity areas.

[0064] In another embodiment, in the method for removing rust from the surface of a steel structure, the polyurethane topcoat is prepared by mixing a main agent and a curing agent in a mass ratio of 4-5:1, wherein the main agent is a hydroxyl acrylic resin having a hydroxyl content of 2.5-3.5%, and the curing agent is a hexamethylene diisocyanate trimer prepolymer having an NCO content of 18-22%. After the main agent and curing agent are mixed, nano-silica defoamer is added to the slurry. The amount of defoamer added is 0.1-0.3% of the total slurry mass, and the particle size is 10-30nm. It is then stirred at a speed of 800-1200r / min for 5-10min using a high-speed disperser. Use airless spraying equipment to spray polyurethane topcoat at a pressure of 0.4-0.8MPa, the spray gun moving speed is 0.3-0.6m / s, the spray distance is maintained at 300-500mm, and the spraying direction is perpendicular to the coating direction of epoxy zinc-rich primer.

[0065] The base agent of the polyurethane topcoat can be a hydroxylated acrylic resin, with a hydroxyl content of 2.5%, 3.0%, or 3.5%. The curing agent can be a hexamethylene diisocyanate trimer prepolymer, with an NCO content of 18%, 20%, or 22%. The base agent to curing agent mass ratio can be set to 4:1, 4.5:1, or 5:1. For example, for a base agent mass of 40 kg, the corresponding curing agent addition amount is 10 kg (4:1) or 8.89 kg (4.5:1). The mixing vessel can be a stainless steel stirred tank, with a capacity of 100 L or 200 L depending on production requirements, and the stirring blades are removable for cleaning.

[0066] Nano-silica particles can be used as defoamers, and the particle size can be set to 10nm, 20nm, or 30nm. The addition amount can be 0.1%, 0.2%, or 0.3% of the total slurry mass. After the defoamer is added, the mixing equipment can be a high-speed disperser, the speed can be set to 800r / min, 1000r / min, or 1200r / min, and the stirring time can be controlled to 5min, 7min, or 10min. The disperser blade can be of a serrated design, and the ratio of the blade diameter to the container inner diameter can be set to 1:3 to ensure that the slurry is uniform and free of bubbles. For example, when processing 100L of slurry, the blade diameter is selected to be 330mm, the speed is set to 1000r / min, and the stirring is carried out for 7 minutes.

[0067] An airless sprayer can be used as the spraying equipment. The spray pressure can be set to 0.4 MPa, 0.6 MPa, or 0.8 MPa. The spray gun movement speed can be adjusted to 0.3 m / s, 0.5 m / s, or 0.6 m / s, and the spray distance can be maintained at 300 mm, 400 mm, or 500 mm. The spray gun can be mounted at the end of an automated movable arm, the movable arm track laid along the surface of the steel structure, and the spray direction is perpendicular to the primer application direction. For example, when the primer is sprayed horizontally, the topcoat is sprayed vertically. The curing chamber can be equipped with temperature and humidity sensors installed on the ceiling and side walls of the chamber. The data is transmitted to the control system in real time, and the temperature fluctuation is controlled within ±2°C and the humidity deviation is ≤5%.

[0068] Through the aforementioned process control, this solution ensures uniform mixing of the polyurethane topcoat, effectively reduces coating bubbles with the defoamer, and optimizes spray parameters to ensure consistent coating thickness and surface smoothness, thereby enhancing the weathering and corrosion resistance of steel structures. This solution is suitable for protection needs in harsh environments such as chemical equipment and offshore platforms.

[0069] In another embodiment, in the method for removing rust from the surface of a steel structure, a steel structure surface drying step is added between step 2) and step 3), and the steel structure surface drying step includes: Use a high-pressure vortex compressed air spray gun to continuously blow the steel structure surface at a pressure of 0.5-1.0 MPa and a blowing angle of 20-40° for 15-30 seconds; After purging, the steel structure surface is dried by a medium-wave infrared radiation device. The infrared device emits a wavelength of 2.5-4.0μm and a power density of 1.5-2.5W / cm 2 , radiation distance 150-300mm, drying time 40-80s, control the surface temperature of the steel structure ≤50℃, residual moisture on the surface after drying ≤0.05g / m 2 .

[0070] The purge pressure of a high-pressure vortex compressed air spray gun can be set to 0.5 MPa, 0.8 MPa, or 1.0 MPa, the purge angle can be adjusted to 20°, 30°, or 40°, and the purge time can be controlled to 15 seconds, 22 seconds, or 30 seconds. The spray gun can use a commercially available stainless steel vortex nozzle with an outlet diameter of 5 mm, 8 mm, or 10 mm. The nozzle is mounted on a movable bracket fixed 100-200 mm above the steel structure surface. For example, when treating flat surfaces, the pressure is set to 0.8 MPa, the angle is 30°, and the purge time is 22 seconds. When treating welds or grooves, the pressure is increased to 1.0 MPa, the angle is adjusted to 40°, and the purge time is extended to 30 seconds.

[0071] The wavelength of the medium-wave infrared radiation device can be set to 2.5μm, 3.0μm or 4.0μm, and the power density can be adjusted to 1.5W / cm 2 , 2.0W / cm 2 or 2.5W / cm 2 The radiation distance can be set to 150mm, 200mm, or 300mm. The infrared device can be installed directly above the steel structure surface, with the height adjusted using a lifting bracket. The drying time can be controlled to 40s, 60s, or 80s. The surface temperature is monitored in real time using a thermocouple, with a temperature threshold set to ≤50°C. For example, at a radiation power density of 2.0W / cm² and a distance of 200mm, a drying time of 60s stabilizes the surface temperature below 48°C.

[0072] The residual moisture on the surface after drying can be detected by weight method, and the residual amount is controlled to ≤0.05g / m 2 During the test, a precision balance (accuracy 0.001g) can be used to measure the mass change of the sample per unit area. For example, take 1m 2 The sample is qualified if the mass difference before and after purging and drying is ≤0.05g. If the residual moisture exceeds the standard, the purging can be repeated or the infrared drying time can be extended. The detection points can be evenly distributed on the surface of the steel structure, every 10m 2 Set up a testing area to ensure full coverage.

[0073] This solution uses the above steps to effectively remove surface moisture and dust through high-pressure purging. Infrared drying further reduces residual moisture, providing a clean and dry base for subsequent laser rust removal and minimizing moisture interference with coating adhesion or laser treatment effectiveness. This solution is suitable for high-humidity environments or when rapid drying is required after water jet cleaning.

[0074] In another embodiment, in the steel structure surface rust removal treatment method, a steel structure surface treatment step is added between step 3) and step 4), and the steel structure surface treatment step includes: The laser-treated steel structure surface is purged using a pulsed compressed air jet device with a purge pressure of 0.3-0.6 MPa, a jet angle of 30-50°, a pulse frequency of 0.5-2 Hz, and a purge time of 5-15 seconds. After purging, the steel structure surface is dried using a far-infrared radiator with a wavelength of 8-12μm and a radiation power density of 0.5-1.0W / cm 2 , drying time 2-5min, after drying the surface humidity of the steel structure ≤3%; After drying, the steel structure surface is sprayed with a non-ionic surfactant solution consisting of the following components in parts by weight: 95-98 parts of deionized water, 1.5-2.5 parts of fatty alcohol polyoxyethylene ether, 0.3-0.8 parts of siloxane coupling agent and 0.1-0.3 parts of sodium citrate; Spraying amount is 10-20g / m 2 After standing for 30-60 seconds, use a negative pressure liquid suction device to remove excess liquid at a vacuum degree of -0.05~-0.08MPa; After absorbing the liquid, the UV curing equipment was used with a wavelength of 365nm and an irradiation intensity of 80-120mW / cm 2 Irradiate for 10-20s to form a siloxane cross-linked activation layer with a thickness of 50-200nm on the surface of the steel structure. The activation layer remains on the surface of the steel structure before applying the anti-rust coating. Its surface contact angle is 100-120°, and its adhesion to the primer is ≥10MPa.

[0075] The purge pressure of the pulsed compressed air jet can be set to 0.3MPa, 0.4MPa, or 0.6MPa, the jet angle can be adjusted to 30°, 40°, or 50°, the pulse frequency can be set to 0.5Hz, 1Hz, or 2Hz, and the purge time can be controlled to 5s, 10s, or 15s. The spray gun can use a stainless steel pulse nozzle with an outlet diameter of 3mm, 5mm, or 8mm. The nozzle is mounted on a movable bracket that is fixed 200-500mm above the laser processing area. For example, when processing flat areas, the pressure is set to 0.4MPa, the frequency is 1Hz, and the purge time is 10s. When processing complex structures, the pressure is increased to 0.6MPa, the frequency is adjusted to 2Hz, and the purge time is extended to 15s.

[0076] The wavelength of the far-infrared radiator can be set to 8μm, 10μm or 12μm, and the power density can be adjusted to 0.5W / cm 2 , 0.8W / cm 2 or 1.0W / cm 2, the drying time can be controlled to 2min, 3min or 5min. The infrared device can be installed on the top of the drying chamber, and the radiation distance can be adjusted to 300-800mm through the lifting mechanism. The surface humidity after drying is monitored in real time by the humidity sensor, and the threshold is set to ≤3%. For example, when the power density is 0.8W / cm 2 ,After 3 minutes of drying, the surface humidity dropped from 5% to 2.5%, which meets the process requirements. The humidity sensor can be installed on the side wall of the drying chamber, with one detection point per square meter.

[0077] The nonionic surfactant solution can be prepared in the following proportions: 95 parts, 97 parts or 98 parts of deionized water, 1.5 parts, 2.0 parts or 2.5 parts of fatty alcohol polyoxyethylene ether, 0.3 parts, 0.5 parts or 0.8 parts of siloxane coupling agent, 0.1 parts, 0.2 parts or 0.3 parts of sodium citrate. The solution spraying amount can be set to 10g / m 2 , 15g / m 2 or 20g / m 2 The static time can be controlled to 30s, 45s, or 60s. A low-pressure spray gun can be used as the spraying equipment, mounted at the end of a mobile arm that moves laterally along the surface of the steel structure. A negative pressure aspirator can be used as the aspiration device, with a vacuum setting of -0.05MPa, -0.06MPa, or -0.08MPa. The distance between the aspiration head and the surface should be maintained at 10-20mm, and the aspiration path should overlap with the spray path to ensure that any residual liquid is completely removed.

[0078] The wavelength of the UV curing equipment can be fixed at 365nm and the irradiation intensity can be adjusted to 80mW / cm 2 , 100mW / cm 2 or 120mW / cm 2 The irradiation time can be set to 10s, 15s or 20s. The UV lamp can be installed on the top of the curing chamber, and the distance between the lamps should be kept at 200-300mm to ensure uniform radiation. For example, the intensity is set to 100mW / cm 2 After irradiation for 15 seconds, a siloxane cross-linked activation layer with a thickness of 50 nm, 100 nm or 200 nm was formed on the surface, the contact angle was detected to be 100°, 110° or 120°, and the adhesion was tested by the cross-grid method to be ≥10 MPa.

[0079] This solution utilizes the aforementioned steps: pulse purging to remove surface residues after laser treatment, far-infrared drying to control humidity, surfactant treatment to enhance wettability, and UV curing to form a dense activation layer, thereby improving the adhesion and corrosion resistance of subsequent coatings. This solution is suitable for applications requiring high surface treatment, such as precision instrument housings and automotive bodies.

[0080] Example 1 A method for removing rust from the surface of a steel structure comprises the following steps: Use infrared radiators to preheat the steel structure surface to 55°C; After the steel structure surface is cooled to 42°C, the preheated steel structure surface is treated by a high-pressure water jet device; the jet pressure of the high-pressure water jet device is 35MPa; Laser rust removal equipment is used to treat the surface of the steel structure that has been treated with high-pressure water. The thickness of the residual rust layer is detected in real time using an infrared thickness gauge, and the operating parameters are adjusted dynamically: When the thickness of the residual rust layer is ≤0.05mm, the laser power density is 12J / cm² and the pulse frequency is 150Hz; When the residual rust thickness is 0.05mm<0.15mm, the laser power density is 20J / cm² and the pulse frequency is 300Hz; When the residual rust thickness is 0.15mm≤0.3mm, the laser power density is 28J / cm² and the pulse frequency is 450Hz; When the thickness of the residual rust layer is ≥0.3mm, the laser power density is 32J / cm², the pulse frequency is 550Hz, and compressed air or nitrogen is delivered to the laser action area as auxiliary cooling gas; Anti-rust coating operation is performed on the surface of the steel structure after laser treatment: The laser-treated steel structure was coated with PPG Amercoat 450 epoxy zinc-rich primer (70% zinc powder by mass) at a thickness of 80 μm. This was followed by a 50 μm topcoat of AkzoNobel Interthane 990 polyurethane. After coating, the steel structure was cured for 36 hours at a temperature of 55°C and a humidity of ≤40%.

[0081] Example 2 Based on Example 1, in the steel structure surface rust removal method, preheating uses an infrared radiator with a wavelength of 3.5 μm, a radiation power of 1.2 W / cm², and a radiation distance of 300 mm; During the preheating process, the surface temperature distribution of the steel structure is monitored in real time by a thermal imager, and the operating parameters are adjusted dynamically: If the local temperature is greater than 60°C, reduce the radiation power in that area to 0.65W / cm²; If the local temperature is 50-60°C, maintain the current radiation power at 1.2W / cm²; If the local temperature is less than 50°C, increase the radiation power in that area to 1.75W / cm².

[0082] Different from Example 1, the injection pressure of the high-pressure water jet device is adjusted according to the thickness of the rust layer, and the specific adjustment method is: When the rust layer thickness is less than 0.1mm, the spraying pressure is 25MPa; When the rust layer thickness is 0.1mm≤≤0.3mm, the injection pressure is 35MPa; When the rust layer thickness is greater than 0.3mm, the injection pressure is 42MPa; The distance between the nozzle of the high-pressure water jet device and the surface of the steel structure is maintained at 200 mm, and the spraying is performed at 60° along the normal direction of the steel structure surface, and the spraying movement speed is 0.8 m / s.

[0083] Example 3 Based on Example 2, in the steel structure surface rust removal treatment method, the water sprayed by the high-pressure water jet device contains a composite corrosion inhibitor, has a pH value of 9.0, and a water temperature of 35° C.; wherein the composite corrosion inhibitor is composed of the following components in parts by weight: 0.85 parts of sodium bicarbonate, 0.55 parts of sodium dodecylbenzenesulfonate, 0.1 parts of sodium molybdate and 0.03 parts of benzotriazole; The preparation method of the composite corrosion inhibitor is as follows: sodium bicarbonate, sodium dodecylbenzenesulfonate, and sodium molybdate are dissolved in 45°C deionized water in sequence, stirred for 30 minutes, and then benzotriazole is added and stirred for 20 minutes until it is completely dissolved; pH sensor, conductivity sensor and Fe 3+ Concentration detector, and according to the detected pH value, conductivity and Fe 3+ The concentration was adjusted as follows: When the pH value is less than 8.5, add sodium bicarbonate solution until the pH value returns to 9.0; When 9.5>pH≥8.5, no adjustment is made; When the pH value is ≥9.5, add 0.075% citric acid solution to adjust the pH value to 9.0; When the conductivity is ≥2000μS / cm, according to Fe 3+ Based on the concentration test results, the amount of sodium dodecylbenzenesulfonate to be added can be corrected as follows: When Fe 3+ When the concentration is ≤3mmol / L, every 1mmol / L Fe 3+ , reduce the addition amount of sodium dodecylbenzenesulfonate in the composite corrosion inhibitor by 0.20%; When 3mmol / L<Fe 3+ When the concentration is ≤5mmol / L, every 1mmol / L Fe detected 3+ , reduce the addition amount of sodium dodecylbenzene sulfonate in the composite corrosion inhibitor by 0.125%; When Fe 3+When the concentration is greater than 5mmol / L, stop adding sodium dodecylbenzenesulfonate to the composite corrosion inhibitor and replace at least 1 / 3 of the volume of the solution in the circulating water tank; When the conductivity is less than 2000 μS / cm, sodium dodecylbenzene sulfonate is added to the composite corrosion inhibitor according to the initial ratio without correction.

[0084] Example 4 Based on Example 3, in the steel structure surface rust removal treatment method, the nozzle for delivering compressed air or nitrogen to the laser action area has a coaxially arranged inner channel and outer channel, the inner channel transmits the laser beam, and the outer channel transmits the cooling gas; The gas flow rate ejected from the nozzle is dynamically adjusted according to the laser power density: When 10J / cm²≤laser power density<25J / cm², the gas flow rate is 35L / min; When 25J / cm²≤laser power density<35J / cm², the gas flow rate is 55L / min; The gas is compressed air or dry nitrogen that has been deoiled and dusted, with a gas purity of ≥99.5%. The first-stage filter and the second-stage filter are arranged in sequence along the gas flow direction in the conveying pipeline. The filtration accuracy of the first-stage filter is 5μm, which is used to remove oil and large particles of impurities; the filtration accuracy of the second-stage filter is 1μm, which is used to remove fine dust.

[0085] Example 5 Different from Example 4, the anti-rust coating operation includes the following steps: Apply epoxy zinc-rich primer on the laser-treated steel structure surface, then apply a transition layer on the surface of the epoxy zinc-rich primer, and then apply polyurethane topcoat; After painting is completed, the steel structure is placed in an environment with a temperature of 55°C and a humidity of ≤45% for curing for 36 hours.

[0086] The mass fraction of zinc powder in the epoxy zinc-rich primer is 70%, and the ambient humidity before coating is ≤60%. The particle size distribution of zinc powder is 5-25μm, of which the zinc powder with a particle size of ≤10μm accounts for ≥70%; The epoxy zinc-rich primer coating temperature is 25°C, and it is sprayed with an electrostatic spraying device at a pressure of 0.45 MPa, a spray gun moving speed of 0.75 m / s, and a spray distance of 300 mm. The transition layer is made by mixing nano-silicon dioxide and epoxy resin and then coating them, where the mass fraction of nano-silicon dioxide is 5.5% and the balance is epoxy resin; Applying the transition layer includes the following steps: Use electrostatic spraying equipment to spray at a pressure of 0.3MPa, the spray gun moving speed is 1.0m / s, the spray distance is maintained at 200mm, and the spraying direction is 55° to the coating direction of the epoxy zinc-rich primer; After spraying, it is pre-cured at 70°C for 8 minutes using an infrared heating device to form a tight sealing layer, which seals the gaps between the zinc powders and inhibits oxidation.

[0087] The polyurethane topcoat is made by mixing a base agent and a curing agent in a mass ratio of 4.5:1. The base agent is a hydroxyl acrylic resin with a hydroxyl content of 3.0%, and the curing agent is a hexamethylene diisocyanate trimer prepolymer with an NCO content of 20%. After the main agent and curing agent are mixed, nano-silica defoamer is added to the slurry. The amount of the defoamer added is 0.2% of the total slurry mass, and the particle size is 20 nm. The slurry is stirred at a speed of 1000 r / min for 7.5 min using a high-speed disperser. Use airless spraying equipment to spray polyurethane topcoat at a pressure of 0.6MPa, the spray gun moves at a speed of 0.45m / s, the spray distance is maintained at 400mm, and the spraying direction is perpendicular to the coating direction of the epoxy zinc-rich primer.

[0088] The rest is the same as Example 4.

[0089] Example 6 On the basis of Example 5, in the steel structure surface rust removal treatment method, a steel structure surface drying step is added between step 2) and step 3), and the steel structure surface drying step includes: Use a high-pressure vortex compressed air spray gun to continuously blow the steel structure surface at a pressure of 0.8 MPa and a blowing angle of 30° for 20 seconds; After purging, the surface of the steel structure is dried by a medium-wave infrared radiation device. The infrared device has an emission wavelength of 3.0μm, a power density of 2.0W / cm², a radiation distance of 200mm, a drying time of 60s, and a surface temperature of the steel structure is controlled to be ≤50℃. The residual moisture on the surface after drying is ≤0.05g / m².

[0090] A steel structure surface treatment step is added between step 3) and step 4), and the steel structure surface treatment step includes: The laser-treated steel structure surface was purged using a pulsed compressed air jet device with a purge pressure of 0.5 MPa, a jet angle of 40°, a pulse frequency of 1 Hz, and a purge time of 10 s. After purging, the steel structure surface is dried using a far-infrared radiator with a wavelength of 10μm, with a radiation power density of 0.75W / cm² and a drying time of 3 minutes. After drying, the surface humidity of the steel structure is ≤3%; After drying, the steel structure surface is sprayed with a non-ionic surfactant solution consisting of the following components in parts by weight: 96.5 parts of deionized water, 2.0 parts of fatty alcohol polyoxyethylene ether, 0.55 parts of siloxane coupling agent and 0.2 parts of sodium citrate; The spraying amount is 15g / m². After standing for 45 seconds, the excess liquid is sucked out using a negative pressure liquid suction device with a vacuum degree of -0.065MPa; After absorbing the liquid, the steel structure was irradiated with UV light for 15 seconds at a wavelength of 365 nm and an irradiation intensity of 100 mW / cm² to form a siloxane cross-linked activation layer on the surface. The thickness of the siloxane cross-linked activation layer was measured by ellipsometer with an error of ±5 nm. The average value of 5 points on the surface was 125±5 nm.

[0091] Comparative Example 1 A method for removing rust from the surface of a steel structure comprises the following steps: The surface of the steel structure is treated by a high-pressure water jet device with a spray pressure of 35MPa; Laser rust removal equipment is used to treat the surface of the steel structure that has been treated with high-pressure water. The laser power density is 20J / cm² and the pulse frequency is 300Hz. An anti-rust coating operation is performed on the surface of the steel structure after laser treatment (the same as in Example 1).

[0092] experiment Experimental subjects: Examples 1-6, Comparative Example 1 (each group was repeated 5 times) Test items: Residual rust layer thickness (measured by infrared thickness gauge); Coating adhesion, cross-hatch test, performed according to ASTM D3359; 5B: no peeling (best); 4B: peeling area <5%; 3B: peeling area 5-15%; 2B: peeling area 15%-35%; 1B: peeling area 35-65%; 0B: peeling area >65% (worst); Rust resistance (neutral salt spray test, 72h, in accordance with ASTM B117); Surface roughness (Ra value, measured by a surface roughness meter).

[0093] Experimental equipment and materials: Salt spray test chamber: Q-FOG CCT1100 equipment was used, and the test strictly followed ASTM B117 standards. Control conditions were a constant temperature of 35±2°C, and a 5% NaCl solution (pH 6.5-7.2) was sprayed continuously for 72 hours to simulate the marine atmospheric corrosion environment. Sample surface images (50 cm) were collected using a Keyence VHX-7000 digital microscope.2 The pixel-level corrosion area was calculated using ImageJ 1.53 software. Three different areas of each sample were measured, and the results were averaged to eliminate local deviations.

[0094] Surface roughness tester: A Mitutoyo Surftest SJ-410 was used, complying with ISO 4287. Equipped with a diamond stylus (radius 2 μm), it achieved a vertical resolution of 0.01 μm and a horizontal resolution of 0.1 μm. Measurement parameters were set to a sampling length of 0.8 mm and an evaluation length of 4.0 mm. Five sets of data were collected for each specimen along a 45° angle from the surface normal. Ra values ​​were maintained within ±5%.

[0095] Infrared thickness gauge: Elcometer 456, based on the pulse echo principle (ASTM D6132), with a measuring range of 0 to 5 mm and an accuracy of ±0.01 mm, capable of real-time monitoring of dynamic changes in rust thickness.

[0096] Cross-hatch test tool: Elcometer 107 Cross-hatch Tester (ASTM D3359 Method B). After cutting the coating with a knife at 2 mm intervals, 3M600 transparent tape is used to peel it off. The adhesion grade is assessed by the percentage of the peeled area (5B is the best and 0B is the worst).

[0097] Test results: The test results of Examples 1-6 and Comparative Example 1 are shown in Table 1.

[0098] Table 1 Comprehensive data table Group Residual rust layer thickness (mm) Coating adhesion (grade) Salt spray corrosion area (%) Surface roughness Ra (μm) Comparative Example 1 0.035±0.008 2B 8.0% 4.5±0.5 Example 1 0.020±0.005 4B 2.5% 3.2±0.3 Example 2 0.018±0.004 4B 2.0% 2.8±0.2 Example 3 0.015±0.003 5B 1.6% 2.5±0.2 Example 4 0.013±0.002 5B 1.1% 2.3±0.2 Example 5 0.010±0.002 5B 0.6% 1.8±0.1 Example 6 0.008±0.001 5B 0.1% 1.5±0.1 Data Analysis: 1. Residual rust layer thickness The best group: Example 6 (residual rust layer thickness 0.008 mm), which further removed micro-rust and optimized the surface condition due to the addition of surface drying (high-pressure blowing + medium-wave infrared drying) and activation layer treatment (UV-cured silicone).

[0099] Worst group: Comparative Example 1 (residual rust thickness 0.035mm), due to no preheating and fixed laser parameters (20J / cm 2 , 300Hz), it is unable to dynamically adapt to the thickness of the rust layer, resulting in residual rust.

[0100] Trend analysis: The thickness of the residual rust layer in Examples 1→6 is gradually reduced. The key improvements include: Example 3 introduces a composite corrosion inhibitor (pH = 9.0, Fe 3+ Dynamic concentration control), inhibiting secondary corrosion; Example 4 optimizes the laser cooling gas flow rate (35-55 L / min) to reduce the reoxidation of the rust layer caused by thermal damage; The pulse purge (0.5 MPa) and UV activation layer (125 nm) of Example 6 completely removed the laser residues.

[0101] 2. Coating adhesion The best group: Examples 5-6 (coating adhesion 5B), because the transition layer (5.5% nano-silica) and the activation layer (siloxane cross-linking) enhance the substrate wettability, the surface roughness (Ra = 1.5-1.8 μm) is lower.

[0102] The worst group: Comparative Example 1 (coating adhesion 2B), which has poor coating adhesion due to the residual rust layer (0.035 mm) and high roughness (Ra = 4.5 μm) on the surface.

[0103] Key factors: Relationship between surface roughness and adhesion: The lower the Ra value (1.5 μm in Example 6), the larger the contact area between the coating and the substrate, and the stronger the adhesion.

[0104] Function of the activating layer: The siloxane activating layer (contact angle 110°) of Example 6 reduces the surface energy and promotes primer penetration and chemical bonding.

[0105] 3. Salt spray corrosion area The best group: Example 6 (salt spray corrosion area 0.1%), due to the dual protection mechanism: Transition layer: closes the gaps between zinc powders (particle size ≤ 10μm, accounting for 70%), and blocks the penetration of corrosive media; Activating layer: Siloxane cross-linked structure (thickness 125nm) enhances the sealing property of the coating.

[0106] The salt spray corrosion area of ​​0.1% in Example 6 is an average value of multiple experiments, which is achieved through uniformity optimization of the UV activation layer and edge protection treatment. The actual substrate body is free of rust.

[0107] Worst group: Comparative Example 1 (salt spray rust area 8.0%), due to the absence of a transition layer and poor coating uniformity, the corrosive medium invaded the substrate along the pores.

[0108] Mechanism verification: The composite corrosion inhibitor (sodium molybdate + benzotriazole) of Example 3 inhibits Fe 3+ active; The polyurethane topcoat of Example 5 (NCO content 20%) has a high crosslinking density and excellent permeation resistance.

[0109] 4. Surface roughness (Ra value) The best group: Example 6 (Ra value 1.5 μm), which reduces substrate scratches due to the optimization of high-pressure water jet parameters (pressure 42 MPa, nozzle angle 60°) and pulse blowing (0.5 MPa).

[0110] Traditional theory holds that surface roughness (Ra = 2-4 μm) improves adhesion through mechanical engagement. However, the present invention overcomes this limitation by synergizing chemical bonding (siloxane activation layer) with physical reinforcement (nano-layer transition layer). The specific mechanism is as follows: (1) Chemical bonding of siloxane cross-linked activation layer 1) Function of coupling agent: The molecular structure of the siloxane coupling agent (such as KH-550 or similar models) in the non-ionic surfactant solution contains alkoxy (-Si-OR) and amino (-NH2) groups.

[0111] The alkoxy groups undergo hydrolysis and condensation reaction with the hydroxyl groups (-OH) on the surface of the steel structure to form Si-O-Fe covalent bonds; The amino group reacts with the epoxy group in the epoxy zinc-rich primer to form a stable chemical bond (such as a hydrogen bond or a covalent bond).

[0112] 2) UV curing enhancement: Ultraviolet light (365nm) triggers a cross-linking reaction between siloxane molecules, forming a dense three-dimensional network structure, which significantly enhances the bonding strength between the active layer and the substrate.

[0113] (2) Physical enhancement effect of nano-transition layer 1) Nano-silica filling: The 5.5% nano-silicon dioxide (particle size 20-30nm) in the transition layer fills the gaps in the zinc powder, forming a dense barrier, reducing the porosity of the coating (≤0.5%), and blocking the penetration of corrosive media.

[0114] 2) Low temperature curing optimization: Infrared pre-curing (70°C, 8 min) promotes the uniform distribution of epoxy resin and nanoparticles, enhances the coating cohesion, and reduces interfacial stress.

[0115] (3) Hydrophobic effect and wettability improvement Contact angle control: The surface contact angle of the activation layer reaches 110-120°, which reduces the surface energy, allows the primer to spread evenly, and reduces coating defects (such as pinholes and bubbles).

[0116] Chemical bonding dominates: Unlike traditional mechanical biting (Ra=2-4μm), this case achieves adhesion ≥10MPa (ASTM D3359) through chemical bonding (covalent bond + hydrogen bond), and can still maintain 5B adhesion even if the Ra value is as low as 1.5μm.

[0117] The worst group: Comparative Example 1 (Ra value 4.5μm), due to the fixed high-pressure water pressure (20MPa) resulting in insufficient impact force, requires repeated cleaning.

[0118] Process impact: The nozzle movement speed (0.8 m / s) of Example 2 balances cleaning efficiency and surface damage; The medium-wave infrared drying (60 s) in Example 6 reduces residual moisture and avoids secondary oxidation that causes uneven surface.

[0119] in conclusion: The present invention's steel structure surface rust removal method achieves efficient rust removal and long-term protection through multi-process collaborative innovation, solving core issues such as low efficiency, parameter curing, and insufficient coating adhesion in traditional processes. The following details the technical advantages and experimental verification: (1) Technological advantages and synergy mechanisms 1) Preheating to optimize surface conditions Temperature uniformity control: through infrared radiator (wavelength 2-5μm, power dynamic adjustment 0.8-2.0W / cm 2 ) Combined with real-time monitoring by a thermal imager, the surface preheating temperature is maintained at a stable 50-60°C. Preheating softens the rust layer and reduces its adhesion to the substrate, creating favorable conditions for subsequent high-pressure water jet and laser treatment.

[0120] Suppressing substrate damage: Dynamic power adjustment avoids local overheating (>60°C) or insufficient preheating (<50°C), reducing substrate microcracks caused by thermal stress.

[0121] 2) Synergistic effect of high-pressure water jet and laser dynamic adjustment Graded pressure cleaning: Adjust the spray pressure (20-45MPa) according to the thickness of the rust layer (<0.1mm, 0.1-0.3mm, >0.3mm), combined with a composite corrosion inhibitor (pH8.5-9.5, containing sodium molybdate and benzotriazole), to significantly inhibit secondary corrosion.

[0122] Precise matching of laser parameters: Real-time feedback from infrared thickness gauge dynamically adjusts laser power density (10-35J / cm 2 ) and pulse frequency (100-600Hz), supplemented by coaxial cooling gas (30-60L / min), to achieve precise stripping of the rust layer and reduce substrate damage by 30% (Ra value reduced from 4.5μm to 1.5μm).

[0123] 3) Innovation of surface activation layer and coating system Transition layer and activation layer design: The nano-silica transition layer (5.5%) seals the gaps between the zinc powder, and the UV-cured siloxane activation layer (125nm) forms a hydrophobic surface (contact angle 110-120°), enhancing the coating's permeability and chemical bonding strength.

[0124] Improved coating durability: The composite system of epoxy zinc-rich primer (70% zinc powder) and polyurethane topcoat (20% NCO content), combined with constant temperature curing at 55°C, reduced the rust area in the salt spray test from 8.0% in Comparative Example 1 to 0.1% in Example 6.

[0125] (2) Experimental data verification 1) Residual rust layer thickness In Example 6, the residual rust layer thickness was the lowest (0.008 mm) through pulse blowing (0.5 MPa) and UV activation layer treatment, which was 77% lower than that of Comparative Example 1 (0.035 mm).

[0126] Key factor: composite corrosion inhibitor inhibits Fe 3+ Active, laser cooling gas optimization (55L / min) reduces thermal oxidation residues.

[0127] 2) Coating adhesion and corrosion resistance The coating adhesion of Example 6 reached 5B (no peeling), and the rust area in the salt spray test was only 0.1%, which was much better than that of Comparative Example 1 (2B adhesion, 8.0% rust).

[0128] The synergistic effect of surface roughness (Ra=1.5μm) and the activation layer increases the coating bonding strength to ≥10MPa (ASTM D3359).

[0129] 3) Process efficiency and environmental protection The optimization of high-pressure water jet movement speed (0.8m / s) and the adjustment of laser dynamic parameters increased the overall processing efficiency by 40%; Circulating water tank Fe 3+ Concentration closed-loop control (replacement threshold 5mmol / L) reduces corrosion inhibitor waste by 30%, meeting green manufacturing requirements.

[0130] The present method for removing rust from steel structures utilizes a multi-process synergy (preheating, high-pressure water jets, laser dynamic adjustment, composite corrosion inhibitors, and a surface activation layer) to achieve precise rust removal and long-term protection. Example 6 demonstrates excellent performance under extreme conditions, while Comparative Example 1 highlights the limitations of a simplified process.

[0131] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and embodiments shown and described herein.

Claims

1. A method for removing rust from the surface of a steel structure, characterized in that: The following steps are involved: 1) Use infrared radiators to preheat the surface of the steel structure to 50-60°C; 2) After the surface temperature of the steel structure drops to 40-45°C, the preheated steel structure surface is treated by a high-pressure water jet device with a spray pressure of 20-50 MPa; 3) Use laser rust removal equipment to treat the surface of the steel structure treated with high-pressure water, and use an infrared thickness gauge to detect the thickness of the residual rust layer in real time, and dynamically adjust the operation parameters: When the thickness of the residual rust layer is ≤0.05mm, 10J / cm 2 ≦Laser power density<15J / cm 2 , 100Hz≦pulse frequency<200Hz; When the residual rust thickness is 0.05mm<0.15mm, 15J / cm 2 ≦Laser power density<25J / cm 2 , 200Hz≦pulse frequency<400Hz; When the residual rust thickness is 0.15mm≤0.3mm, 25J / cm 2 ≦Laser power density<30J / cm 2 , 400Hz≦pulse frequency<500Hz; When the thickness of the residual rust layer is ≥0.3mm, 30J / cm 2 ≦Laser power density<35J / cm 2 , 500Hz≤pulse frequency<600Hz, and at the same time, compressed air or nitrogen is delivered to the laser action area as auxiliary cooling gas; 4) Apply anti-rust coating on the surface of the steel structure after laser treatment.

2. The method for rust removal on the surface of a steel structure according to claim 1, wherein: The preheating wavelength is 2-5μm and the radiation power is 0.8-1.5W / cm 2 Infrared radiator with a radiation distance of 200-400mm; During the preheating process, the surface temperature distribution of the steel structure is monitored in real time by a thermal imager, and the operating parameters are adjusted dynamically: If the local temperature is greater than 60°C, reduce the radiation power in that area to 0.5-0.8W / cm 2 ; If the local temperature is 50-60°C, maintain the current radiation power; If the local temperature is less than 50°C, increase the radiation power in that area to 1.5-2.0W / cm 2 .

3. The method for rust removal on the surface of a steel structure according to claim 1, wherein: The injection pressure of the high-pressure water jet device is adjusted according to the thickness of the rust layer, and the specific adjustment method is: When the rust layer thickness is less than 0.1mm, the spraying pressure is 20-30MPa; When the rust layer thickness is 0.1mm≤≤0.3mm, the injection pressure is 30-40MPa; When the rust layer thickness is greater than 0.3mm, the spray pressure is 40-45MPa; The distance between the nozzle of the high-pressure water jet device and the surface of the steel structure is maintained at 100-300mm, and the spraying is performed at 50-70° along the normal direction of the steel structure surface, and the spraying movement speed is 0.5-1.2m / s.

4. The method for rust removal on the surface of a steel structure according to claim 1, wherein: The water sprayed by the high-pressure water jet device contains a composite corrosion inhibitor, has a pH value of 8.5-9.5, and a water temperature of 30-40°C; The composite corrosion inhibitor is composed of the following components in parts by weight: 0.5-1.2 parts of sodium bicarbonate, 0.3-0.8 parts of sodium dodecylbenzenesulfonate, 0.05-0.15 parts of sodium molybdate and 0.01-0.05 parts of benzotriazole; The preparation method of the composite corrosion inhibitor is as follows: sodium bicarbonate, sodium dodecylbenzene sulfonate, and sodium molybdate are dissolved in deionized water at 40-50°C in sequence, stirred for 30 minutes, and then benzotriazole is added and stirred for 20 minutes until it is completely dissolved. pH sensor, conductivity sensor and Fe 3+ Concentration detector, and according to the detected pH value, conductivity and Fe 3+ The concentration was adjusted as follows: When the pH value is less than 8.5, add sodium bicarbonate solution until the pH value returns to 8.5-9.5; When 9.5>pH≥8.5, no adjustment is made; When the pH value is ≥9.5, add 0.05-0.1% citric acid solution to adjust the pH value to 8.5-9.5; When the conductivity is ≥2000μS / cm, according to Fe 3+ Based on the concentration test results, the amount of sodium dodecylbenzenesulfonate to be added can be corrected as follows: When Fe 3+ When the concentration is ≤3mmol / L, every 1mmol / L Fe 3+ , reduce the addition amount of sodium dodecylbenzenesulfonate in the composite corrosion inhibitor by 0.15-0.25%; When 3mmol / L<Fe 3+ When the concentration is ≤5mmol / L, every 1mmol / L Fe detected 3+ , reduce the addition amount of sodium dodecylbenzenesulfonate in the composite corrosion inhibitor by 0.1-0.15%; When Fe 3+ When the concentration is greater than 5mmol / L, stop adding sodium dodecylbenzenesulfonate to the composite corrosion inhibitor and replace at least 1 / 3 of the volume of the solution in the circulating water tank; When the conductivity is less than 2000 μS / cm, sodium dodecylbenzene sulfonate is added to the composite corrosion inhibitor according to the initial ratio without correction.

5. The method for rust removal on the surface of a steel structure according to claim 1, wherein: The nozzle for delivering compressed air or nitrogen to the laser action area has an inner channel and an outer channel arranged coaxially, the inner channel transmits the laser beam, and the outer channel transmits the cooling gas; The gas flow rate ejected from the nozzle is dynamically adjusted according to the laser power density: When 10J / cm 2 ≤Laser power density<25J / cm 2 When, the gas flow rate is 30-40L / min; When 25J / cm 2 ≤Laser power density<35J / cm 2 When, the gas flow rate is 50-60L / min; The gas is compressed air or dry nitrogen that has been degreased and dust-removed, with a gas purity of ≥99.5%. A first-stage filter and a second-stage filter are sequentially installed in the delivery pipeline along the gas flow direction. The first-stage filter has a filtration accuracy of 5μm and is used to remove oil and large particles of impurities. The second-stage filter has a filtration accuracy of 1μm and is used to remove fine dust.

6. The method for rust removal on the surface of a steel structure according to claim 1, wherein: Implementing anti-rust coating operations includes the following steps: Apply epoxy zinc-rich primer on the surface of the laser-treated steel structure. The mass fraction of zinc powder in the epoxy zinc-rich primer is 60-75%, and the ambient humidity before coating is ≤65%; After applying epoxy zinc-rich primer, apply polyurethane topcoat on the surface of the steel structure; After painting is completed, place the steel structure in an environment with a temperature of 50-60℃ and a humidity of ≤50% for curing for 24-48 hours.

7. The method for removing rust from the surface of a steel structure according to claim 6, wherein: The particle size distribution of zinc powder in epoxy zinc-rich primer is 5-25μm, of which the zinc powder with a particle size of ≤10μm accounts for ≥60%; The coating temperature of epoxy zinc-rich primer is 15-35℃, and electrostatic spraying equipment is used for spraying at a pressure of 0.3-0.6MPa, the spray gun moving speed is 0.5-1.0m / s, and the spray distance is maintained at 200-400mm; After the epoxy zinc-rich primer is applied, a transition layer is applied on the surface of the epoxy zinc-rich primer, and then a polyurethane topcoat is applied. The transition layer is made by mixing nano-silicon dioxide and epoxy resin, wherein the mass fraction of nano-silicon dioxide is 4.8-6.1% and the balance is epoxy resin. Applying the transition layer includes the following steps: Use electrostatic spraying equipment to spray at a pressure of 0.2-0.4MPa, the spray gun moving speed is 0.8-1.2m / s, the spray distance is maintained at 150-250mm, and the spraying direction is 45-65° to the coating direction of the epoxy zinc-rich primer; After spraying, cure at 60-80℃ for 5-10 minutes to form a hermetic sealing layer, seal the gaps between zinc powder and inhibit oxidation.

8. The method for rust removal on the surface of a steel structure according to claim 6, wherein: The polyurethane topcoat is made by mixing the main agent and the curing agent in a mass ratio of 4-5:

1. The main agent is a hydroxyl acrylic resin with a hydroxyl content of 2.5-3.5%. The curing agent is a hexamethylene diisocyanate trimer prepolymer with an NCO content of 18-22%. After the main agent and curing agent are mixed, nano-silica defoamer is added to the slurry. The amount of defoamer added is 0.1-0.3% of the total slurry mass, and the particle size is 10-30nm. It is then stirred at a speed of 800-1200r / min for 5-10min using a high-speed disperser. Use airless spraying equipment to spray polyurethane topcoat at a pressure of 0.4-0.8MPa, the spray gun moving speed is 0.3-0.6m / s, the spray distance is maintained at 300-500mm, and the spraying direction is perpendicular to the coating direction of epoxy zinc-rich primer.

9. The method for removing rust from the surface of a steel structure according to claim 1, wherein: A steel structure surface drying step is added between step 2) and step 3), and the steel structure surface drying step includes: Use a high-pressure vortex compressed air spray gun to continuously blow the steel structure surface at a pressure of 0.5-1.0 MPa and a blowing angle of 20-40° for 15-30 seconds; After purging, the steel structure surface is dried by a medium-wave infrared radiation device. The infrared device emits a wavelength of 2.5-4.0μm and a power density of 1.5-2.5W / cm 2 , radiation distance 150-300mm, drying time 40-80s, control the surface temperature of the steel structure ≤50℃, residual moisture on the surface after drying ≤0.05g / m 2 .

10. The method for rust removal on the surface of a steel structure according to claim 1, wherein: A steel structure surface treatment step is added between step 3) and step 4), and the steel structure surface treatment step includes: The laser-treated steel structure surface is purged using a pulsed compressed air jet device with a purge pressure of 0.3-0.6 MPa, a jet angle of 30-50°, a pulse frequency of 0.5-2 Hz, and a purge time of 5-15 seconds. After purging, the steel structure surface is dried using a far-infrared radiator with a wavelength of 8-12μm and a radiation power density of 0.5-1.0W / cm 2 , drying time 2-5min, after drying the surface humidity of the steel structure ≤3%; After drying, the steel structure surface is sprayed with a non-ionic surfactant solution, which consists of the following components in parts by weight: 95-98 parts of deionized water, 1.5-2.5 parts of fatty alcohol polyoxyethylene ether, 0.3-0.8 parts of siloxane coupling agent and 0.1-0.3 parts of sodium citrate; Spraying amount is 10-20g / m 2 After standing for 30-60 seconds, use a negative pressure liquid suction device to remove excess liquid at a vacuum degree of -0.05~-0.08MPa; After absorbing the liquid, the UV curing equipment was used with a wavelength of 365nm and an irradiation intensity of 80-120mW / cm 2 Irradiate for 10-20s to form a siloxane cross-linked activation layer with a thickness of 50-200nm on the surface of the steel structure.