Temperature-indicating corrosion-inhibiting coating for bridge fire prevention, preparation equipment and preparation method

Abstract

The invention discloses a temperature-indicating corrosion-inhibiting coating for bridge fire prevention, preparation equipment and a preparation method. The coating is prepared from the following raw material components: base resin, a heat-sensitive material, a flame retardant, a corrosion inhibitor, an anti-corrosion filler and an auxiliary agent, wherein the components are as follows in parts by weight: 45-55 parts of the base resin, 17-23 parts of the heat-sensitive material, 15-18 parts of the flame retardant, 15-20 parts of the corrosion inhibitor, 8-10 parts of the anticorrosive filler and 3-5 parts of the auxiliary agent; the heat-sensitive material comprises a cobalt salt, a nickel salt and a liquid crystal microcapsule, and the cobalt salt, the nickel salt and the liquid crystal microcapsule form a three-stage heat-sensitive material. Through collaborative design of material innovation, process optimization and equipment improvement, the core problems of poor weather resistance, single function and poor adhesive force of a traditional temperature indicating coating in bridge engineering are solved, fire early warning-flame retardance-corrosion prevention integrated protection is achieved, an innovative solution is provided for safe operation and maintenance and sustainable development of bridges, and the application prospect is wide. And the method has good popularization value.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of bridge engineering, and particularly relates to a temperature indicating and corrosion inhibiting coating for bridge fire prevention, a manufacturing device and a preparation method. BACKGROUND

[0002] Temperature indicating coating, also known as heat sensitive coating or color changing coating, indicates the temperature and temperature distribution of the surface of an object through color change. Its working principle is that when the coating is heated to a certain temperature, the heat sensitive pigment in the coating will undergo physical or chemical change, resulting in color change. This feature enables the temperature indicating coating to measure temperature values within a certain range. The unique temperature measuring function of the temperature indicating coating and its important application value in bridge maintenance can help engineers and maintenance personnel better monitor and manage the temperature changes of the bridge, ensuring the safety and stability of the bridge.

[0003] Due to the particularity of the bridge engineering environment, the traditional temperature indicating coating is prone to failure due to ultraviolet and rain erosion, and therefore has poor weather resistance. The traditional temperature indicating coating can only indicate a single threshold, and its temperature response is single. The traditional coating is prone to peeling off on the surface of concrete or metal, and has insufficient adhesion and is prone to cracking due to bridge vibration. The information disclosed in this section of the background art is only intended to increase the understanding of the overall background of the application and should not be considered as recognition or in any form as admitting that this information constitutes prior art known to those of ordinary skill in the art. SUMMARY

[0004] The purpose of the present application is to provide a temperature indicating and corrosion inhibiting coating for bridge fire prevention, a manufacturing device and a preparation method, which can solve the problems of poor weather resistance, single temperature response and insufficient adhesion of the traditional temperature indicating coating.

[0005] In order to achieve the above-mentioned purpose, the technical solution provided by an embodiment of the present application is as follows: A temperature indicating and corrosion inhibiting coating for bridge fire prevention, the raw material components of the coating are base resin, heat sensitive material, flame retardant, corrosion inhibitor, corrosion resistant filler and auxiliary agent; The weight parts of each component are as follows: base resin 45-55 parts, heat sensitive material 17-23 parts, flame retardant 15-18 parts, corrosion inhibitor 15-20 parts, corrosion resistant filler 8-10 parts and auxiliary agent 3-5 parts; wherein the flame retardant delays the spread of fire, the corrosion inhibitor gives the coating long-term slow-release protection ability, and the corrosion resistant filler improves the salt mist resistance.

[0006] The heat-sensitive material includes cobalt salt, nickel salt and liquid crystal microcapsule, and the cobalt salt, nickel salt and liquid crystal microcapsule form a three-level heat-sensitive material. By utilizing the characteristics of the cobalt salt changing red at 300 DEG C, the nickel salt changing brown at 500 DEG C and the liquid crystal microcapsule changing black at 700 DEG C, multi-level temperature response of the temperature indicating paint is realized, so that the color change of the cobalt salt, nickel salt and liquid crystal microcapsule in steps from gray to red, brown and black can accurately indicate the fire development stage. The corrosion inhibitor includes mesoporous silica loaded with ammonium polyphosphate, organic modified montmorillonite intercalated with benzotriazole and silane microcapsule, so as to form a composite corrosion inhibitor with functions of flame-retardant slow release, corrosion prevention slow release and self-repairing. While ensuring the multi-level temperature indicating function of the paint, the long-acting slow-release protection ability of the paint is endowed, and the paint is suitable for extreme environment scenes such as bridges and petrochemical equipment, and the service life of the temperature indicating paint in the extreme environment is effectively improved.

[0007] In one or more embodiments of the present application, the raw material components of the base resin include weather-resistant fluorocarbon resin, silicone-modified acrylic resin, isocyanate curing agent and silane coupling agent. The weather-resistant fluorocarbon resin and the silicone-modified acrylic resin are compounded in a mass ratio of 3:1 to 5:1, the fluorine content is required to be greater than or equal to 22% to improve the ultraviolet aging resistance. The weight fraction of the isocyanate curing agent is 3 to 5 parts to form an interpenetrating network structure to improve the hardness and impact resistance of the coating. The weight fraction of the silane coupling agent is 0.5 to 1.5 parts to enhance the chemical bonding of the coating with the concrete / metal substrate.

[0008] In one or more embodiments of the present application, the cobalt salt is CoCrO4, the outer layer of the CoCrO4 is wrapped with SiO2 to form a CoCrO4@SiO2 core-shell structure microsphere, the SiO2 coating layer delays the oxidation of the cobalt salt and ensures the initial color change at 200 DEG C. The nickel salt is a NiTiO3-ZnWO4 solid solution, the molar ratio of the NiTiO3 and ZnWO4 is 1:1, and the color development at 500 DEG C is realized by band regulation. The liquid crystal microcapsule encapsulates carbon black precursor, the carbon black precursor is a composite of one or both of polyaniline and Fe3O4, the capsule is broken to release Fe3O4 to catalyze carbonization at 700 DEG C, and the coating irreversibly changes black.

[0009] In one or more embodiments of the present application, the flame retardant is nano-aluminum hydroxide, expanded graphite and silane coupling agent, the nano-aluminum hydroxide and expanded graphite are compounded in a mass ratio of 2:1, the particle size of the nano-aluminum hydroxide is 50 nm, the interlayer spacing of the expanded graphite is ≥0.8 nm, the content of the silane coupling agent added is 2%, the silane coupling agent is used for surface modification to improve dispersibility. The anticorrosive filler is mica powder, glass flake and zinc phosphate corrosion inhibitor, the mica powder and glass flake are stacked in a mass ratio of 1:2, the diameter-thickness ratio of the mica powder is >50, the thickness of the glass flake is 1-3 μm, the weight fraction of the zinc phosphate corrosion inhibitor is 1-2 parts, forming a labyrinth anti-permeation barrier. The auxiliary agent is a dispersant, a defoaming agent and a UV absorber.

[0010] A kind of bridge fireproof temperature indicating corrosion inhibitor coating production equipment, the production equipment includes: The dispersion mechanism includes a dispersion kettle body, a rotating head is rotatably connected to the bottom wall plate in the dispersion kettle body, and a plurality of turbine dispersion blades are installed on the side wall of the rotating head. The rotation of the rotating head can drive the rotation of the multi-stage turbine dispersion blades to crush and disperse the material. A first screen is installed in the dispersion kettle body, and the first screen is arranged above the multi-stage turbine dispersion blades. The homogenized glue solution after dispersion is screened by the first screen.

[0011] The grinding mechanism includes a grinding cavity body, a grinding disc is rotatably connected to the bottom wall plate in the grinding cavity body, a plurality of honeycomb grooves are formed in the top of the grinding disc, and a plurality of zirconia grinding beads are arranged on the top of the grinding disc. The rotation of the grinding disc can drive the rolling of the plurality of zirconia grinding beads. The plurality of zirconia grinding beads can finely grind the material when rolling. The honeycomb grooves form multidirectional flow channels, reduce grinding dead angles, promote the mixing of the material and the zirconia grinding beads, guide the grinding beads to form vortex under the action of centrifugal force, prolong the residence time of the material, and increase the number of effective collisions. A second screen is installed on the grinding disc, and the ground material is screened by the second screen under the action of centrifugal force.

[0012] The protective assembly comprises a heat exchange chamber for temperature adjustment of liquid nitrogen so as to change the liquid nitrogen into nitrogen gas for conveying after temperature adjustment. First conveying pipe and second conveying pipe are respectively arranged at left and right ends of the heat exchange chamber, one end of the first conveying pipe away from the heat exchange chamber penetrates through the side wall of the dispersion kettle body and is arranged in the dispersion kettle body, nitrogen gas in the heat exchange chamber is conveyed into the dispersion kettle body through the first conveying pipe so as to disperse the material under the protection of nitrogen gas, the nitrogen gas not only makes the dispersion of the material in the dispersion kettle body in an oxygen-free environment, but also controls the temperature of the material during dispersion to ensure that the heat-sensitive material will not be denatured. One end of the second conveying pipe away from the heat exchange chamber penetrates through the side wall of the grinding cavity body and is arranged in the grinding cavity body, nitrogen gas in the heat exchange chamber is conveyed into the grinding cavity body through the second conveying pipe so as to grind the material under the protection of nitrogen gas, the nitrogen gas not only makes the dispersion of the material in the dispersion kettle body in an oxygen-free environment, but also controls the temperature of the material during grinding to ensure that the heat-sensitive material will not be denatured.

[0013] The spraying and curing all-in-one machine comprises a high-voltage electrostatic spray gun and a curing furnace. The high-voltage electrostatic spray gun is internally provided with a micro eddy current generator to form a ring-shaped airflow and improve the uniformity of the coating. The curing furnace adopts infrared radiation and hot air circulation composite heating to effectively cure the temperature indicating coating after spraying and ensure the uniformity and strength of the temperature indicating coating after spraying. In order to realize intelligent spraying, a high-resolution thermal imaging camera and an AI image recognition system can be carried during spraying to detect defects such as coating pinholes and cracks in real time.

[0014] In one or more embodiments of the present application, the multi-stage turbine dispersion blade includes a first turbine blade, a second turbine blade and a third turbine blade, which are installed on the side wall of the rotating head from bottom to top, respectively, and are all arranged obliquely, with the included angle between the first turbine blade, the second turbine blade and the third turbine blade and the horizontal plane being 15 degrees, 30 degrees and 45 degrees, respectively, so as to optimize the fluid shear path, make the nanoparticle dispersion uniform, and improve the dispersion effect on the material, thereby reducing the energy consumption. The bottom wall plate of the dispersion kettle body is rotatably connected with a first driving shaft, the upper end of the first driving shaft is fixedly connected to the bottom of the rotating head, and the lower end of the first driving shaft is provided with a first high-speed motor, which drives the first driving shaft to rotate, and the rotation of the first driving shaft drives the rotating head to rotate. A feeding pipe is installed on the side wall of the dispersion kettle body, and the material is added into the dispersion kettle body through the feeding pipe for shearing dispersion. A discharge pipe is installed on the bottom wall plate of the dispersion kettle body, a switch valve is installed on the discharge pipe, and the dispersed homogeneous glue solution can be discharged through the discharge pipe and then transported by a pump. A material conveying pipe is installed on the top wall plate of the dispersion kettle body, and the homogeneous glue solution can also be conveyed through the material conveying pipe after being screened by the first screen.

[0015] In one or more embodiments of the present application, the honeycomb groove is arranged in a hexagonal honeycomb structure, the edges of the honeycomb groove form a local high shear zone, and the zirconia grinding beads and the grinding disc structure interact to generate stronger shear force, which is suitable for high-viscosity materials. The length of the side of the hexagonal honeycomb groove is arranged to be 0.75-1.5 mm, the depth of the honeycomb groove is arranged to be 1-1.8 mm, the diameter of the zirconia grinding beads is arranged to be 0.3-0.6 mm, and a shielding frame is integrally formed on the edge of the grinding cavity body, and the second screen is installed on the shielding frame, which can shield the zirconia grinding beads. A second driving shaft is rotatably connected to the bottom wall plate of the grinding cavity body, the upper end of the second driving shaft is fixedly connected to the bottom of the grinding disc, and the lower end of the second driving shaft is provided with a second high-speed motor. A pair of rotating plates are fixedly connected to the side wall of the second driving shaft above the bottom wall plate of the grinding cavity body, the side wall of the grinding cavity body is provided with a discharge port, the outer side of the discharge port is fixedly connected with a material conveying groove, and when the rotating plate is driven to rotate by the rotation of the second driving shaft, the ground and screened material can be discharged through the discharge port. The end of the material conveying pipe away from the dispersion kettle body penetrates through the top wall plate of the grinding cavity body and is placed in the grinding cavity body, and the outlet end of the material conveying pipe placed in the grinding cavity body is located below the side of the second conveying pipe, so that the nitrogen gas sprayed by the second conveying pipe can homogenize the material conveyed by the material conveying pipe.

[0016] In one or more embodiments of the present application, the first conveying pipe is arranged in the dispersion kettle body, one end of the first conveying pipe is provided with a vertical section, the vertical section of the first conveying pipe is located directly above the rotating head, a plurality of first nozzles are arranged on the vertical section of the first conveying pipe in a downwardly inclined manner, nitrogen gas is uniformly discharged into the dispersion kettle body through the plurality of first nozzles, and the nitrogen gas discharged from the first nozzles can also clean the dispersion blades when the nitrogen gas protects and cools the material. A first flow regulating valve is installed on the first conveying pipe, and the first flow regulating valve is used to control the flow and pressure of the nitrogen gas conveyed into the first conveying pipe. A second flow regulating valve is installed on the second conveying pipe, one end of the second conveying pipe is provided with a vertical section, the vertical section of the second conveying pipe coincides with the central axis of the grinding cavity body, an atomizer is fixedly connected below the vertical section of the second conveying pipe, a plurality of second nozzles are arranged on the bottom wall plate of the atomizer in an outwardly diffusing inclined manner, and the nitrogen gas conveyed through the second conveying pipe is uniformly sprayed onto the grinding disc through the second nozzles, so that the nitrogen gas can protect and cool the material ground on the grinding disc, and ensure that the friction between the zirconia grinding beads and the material will not cause the pyrolysis and denaturation of the heat-sensitive material. A liquid nitrogen conveying pipe is installed on the top of the side wall of the heat exchange chamber, a third flow regulating valve is installed on the liquid nitrogen conveying pipe, the amount of liquid nitrogen conveyed by the liquid nitrogen conveying pipe is controlled through the third flow regulating valve, the content of the conveyed liquid nitrogen is accurately adjusted, and the waste of liquid nitrogen is avoided. An ethylene glycol aqueous solution conveying pipe is installed on the bottom of the side wall of the heat exchange chamber, a fourth flow regulating valve is installed on the ethylene glycol aqueous solution conveying pipe, and the ethylene glycol aqueous solution conveying pipe is used to carry the cold source so as to convey the temperature-adjusted liquid nitrogen after mixing with the liquid nitrogen in the heat exchange chamber.

[0017] A preparation method of a temperature-indicating corrosion-inhibiting coating for bridge fire prevention, the preparation method comprising: S1, heat-sensitive material pretreatment, CoCrO4@SiO2core-shell microspheres are synthesized by sol-gel method, surface modification is performed using silane coupling agent to enhance the interface bonding with resin; liquid crystal microcapsules are prepared by microfluidic emulsification-ultraviolet curing; S2, raw material preparation, the base resin is compounded by fluorocarbon resin base and silicone modified acrylic resin at a ratio of 4:1; the flame retardant is mixed by nano-aluminum hydroxide and expanded graphite at a ratio of 2:1, and is surface modified by silane coupling agent; the corrosion inhibitor is mixed by mesoporous silica loaded with ammonium polyphosphate, organic modified montmorillonite intercalated with benzotriazole, and silane microcapsules at a weight ratio of 5:3:2; the anticorrosive filler is compounded by mica powder and glass flake at a ratio of 1:2, and 1.5% zinc phosphate corrosion inhibitor is added.

[0018] S3, pre-dispersion stage, base resin and mixed solvent are added into the dispersion kettle body in a ratio of 1:1, nitrogen protection is turned on, and high-speed shear dispersion is carried out at 5000r / min for 15 minutes; then flame retardant, corrosion inhibitor and anti-corrosion filler are added in sequence, and ultrasonic assisted dispersion is carried out for 30 minutes to form a homogeneous glue solution; S4, grinding stage, add the homogenized glue into the grinding chamber body, start liquid nitrogen cooling, and add the heat-sensitive material in stages; first add CoCrO4@SiO2 microspheres and grind at 1500r / min for 20 minutes; then add NiTiO3-ZnWO4 solid solution, reduce the speed to 1200r / min, and grind for 15 minutes; finally add liquid crystal microcapsules, grind at 800r / min for 10 minutes; adjust the speed to 3000r / min for dynamic centrifugal classification, separate the slurry with D90≤20nm, and return the coarse particles for grinding; S5. Spray curing. Filter the ground slurry through a 200-mesh sieve and add 3% defoaming agent. Use electrostatic spraying to evenly coat the surface of the bridge substrate. Set the voltage to 80kV and the spray distance to 15cm during spraying. Preheat with infrared radiation at 60℃ / 10min to initially evaporate the solvent. Circulate hot air at 80℃ / 30min+120℃ / 1h to form a cross-linked network. Naturally cool to below 40℃ with nitrogen protection throughout the process, so that the temperature-indicating coating can be evenly sprayed on the bridge structure.

[0019] In one or more embodiments of the present invention, the SiO2 shell thickness in S1 is 20~30nm, the particle size of the core-shell microspheres is 50~100nm, and the particle size of the liquid crystal microcapsules is 50~100nm; the temperature in S3 and S4 is controlled at -10~30℃, the Span value of the particle size of the finished slurry in S4 is ≤0.8; the coating thickness in S5 is set to 80±5μm, and the adhesion is ≥5MPa.

[0020] Compared with the prior art, the present invention has the following advantages: 1. The present invention adopts a stepped color change system of CoCrO4@SiO2 core-shell microspheres, NiTiO3-ZnWO4 solid solution and liquid crystal microcapsules to achieve three-level fire temperature indication, which greatly improves the judgment accuracy compared with traditional single-level response coatings and provides a critical time window for bridge fire prevention and control. At the same time, the addition of corrosion inhibitors to the coating not only ensures the coating's multi-level temperature indication function but also gives the coating long-term slow-release protection capabilities, making it suitable for extreme environments such as bridges and petrochemical equipment. 2、The present application adopts fluorocarbon resin base material and gradient anticorrosion filler synergistic effect, greatly improves the salt fog resistance and ultraviolet resistance of the coating, and further improves the weather resistance of the coating, which is suitable for high corrosion environment such as coastal area and industrial pollution area, and the bridge maintenance cycle is greatly prolonged; at the same time, the flame retardant reduces the heat release rate and smoke density, and significantly delays the spread of fire; 3、The present application adopts low-temperature grinding-grading system combined with electrostatic spraying process, effectively shortens the production cycle, improves the raw material utilization rate, effectively reduces the production cost, and greatly improves the adhesion and impact resistance of the prepared coating, adapts to the dynamic load and complex environment of the bridge, prolongs the service life of the coating, and reduces the cost of bridge maintenance; 4、The present application solves the core problems of poor weather resistance, single function and poor adhesion of traditional temperature indicating coating in bridge engineering through the synergistic design of material innovation, process optimization and equipment improvement, realizes fire warning-flame retardant-anticorrosion integrated protection, provides an innovative solution for bridge safety operation and sustainable development, and has good popularization value. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1 It is a front view of a kind of bridge fireproof temperature indicating corrosion inhibiting coating production equipment in an embodiment of the present application; Figure 2 It is a perspective view of a kind of bridge fireproof temperature indicating corrosion inhibiting coating production equipment in an embodiment of the present application; Figure 3 It is a sectional view of a kind of bridge fireproof temperature indicating corrosion inhibiting coating production equipment in an embodiment of the present application; Figure 4 It is a sectional view of a kind of bridge fireproof temperature indicating corrosion inhibiting coating production equipment in an embodiment of the present application; Figure 5 It is a schematic view of A in the present application Figure 4 ; Figure 6 It is a schematic view of B in the present application Figure 4 ; Figure 7 It is a schematic view of C in the present application Figure 4 ; Figure 8 It is a schematic view of C in the present application Figure 9 For the present invention Figure 8 The schematic diagram at D in the present invention.

[0023] Explanation of main reference signs: 1-dispersion structure, 11-dispersion kettle body, 12-rotary head, 13-first turbine blade, 14-second turbine blade, 15-third turbine blade, 16-first drive shaft, 17-first high-speed motor, 18-first screen, 19-feeding pipe, 110-discharge pipe, 111-on-off valve, 112-feeding pipe, 2-grinding mechanism, 21-grinding cavity body, 22-grinding disc, 23-honeycomb groove, 24-zirconium oxide grinding beads, 25-shielding frame, 26-second screen, 27-second drive shaft, 28-second high-speed motor, 29-rotary plate, 210-discharge port, 211-feeding groove, 3-protection assembly, 31-heat exchange chamber, 32-first conveying pipe, 33-first flow regulating valve, 34-first nozzle, 35-second conveying pipe, 36-second flow regulating valve, 37-atomizer, 38-second nozzle, 39-liquid nitrogen conveying pipe, 310-third flow regulating valve, 311-ethylene glycol aqueous solution conveying pipe, 312-fourth flow regulating valve. DETAILED DESCRIPTION

[0024] In order to make the personnel in the technical field better understand the technical solutions in the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person of ordinary skill in the art without creative labor should belong to the protection scope of the present application.

[0025] The temperature indicating corrosion inhibiting coating for bridge fire prevention in an embodiment of the present application can realize real-time sensing of fire temperature through color change, and has weather resistance, flame retardance and corrosion resistance.

[0026] The raw material components of the temperature indicating coating are base resin, heat sensitive material, flame retardant, corrosion inhibitor, corrosion resistant filler and additive; wherein the weight parts of each component are as follows: base resin 45-55 parts, heat sensitive material 17-23 parts, flame retardant 15-18 parts, corrosion inhibitor 15-20 parts, corrosion resistant filler 8-10 parts and additive 3-5 parts; wherein the flame retardant delays the spread of fire, the corrosion inhibitor gives the coating long-term slow-release protection ability, and the corrosion resistant filler improves salt mist resistance.

[0027] The heat-sensitive material includes cobalt salt, nickel salt and liquid crystal microcapsule, and the cobalt salt, nickel salt and liquid crystal microcapsule form a three-level heat-sensitive material. By using the characteristics of the cobalt salt changing red at 300°C, the nickel salt changing brown at 500°C and the liquid crystal microcapsule changing black at 700°C, multi-level temperature response of the temperature indicating paint is realized, so that the color change of the cobalt salt, nickel salt and liquid crystal microcapsule in steps from gray to red, brown and black can precisely indicate the fire development stage.

[0028] The corrosion inhibitor includes mesoporous silica loaded with ammonium polyphosphate, organic modified montmorillonite intercalated with benzotriazole and silane microcapsule, so as to form a composite corrosion inhibitor with functions of flame-retardant slow release, corrosion-resistant slow release and self-repairing. While ensuring the multi-level temperature indicating function of the paint, the long-acting slow-release protection ability of the paint is also endowed, which is suitable for extreme environment scenes such as bridges and petrochemical equipment, and effectively improves the service life of the temperature indicating paint in extreme environments.

[0029] Specifically, the raw material components of the base resin include weather-resistant fluorocarbon resin, silicone-modified acrylic resin, isocyanate curing agent and silane coupling agent. The weather-resistant fluorocarbon resin and the silicone-modified acrylic resin are compounded in a mass ratio of 3:1 to 5:1, and the fluorine content needs to be controlled to be greater than or equal to 22% to improve the ultraviolet aging resistance. The weight fraction of the isocyanate curing agent is 3 to 5 parts to form an interpenetrating network structure, thereby improving the hardness and impact resistance of the coating. The weight fraction of the silane coupling agent is 0.5 to 1.5 parts to enhance the chemical bonding of the paint and the concrete / metal substrate.

[0030] Further, the cobalt salt is CoCrO4, and the outer layer of CoCrO4 is wrapped with SiO2 to form a CoCrO4@SiO2 core-shell structure microsphere. The SiO2 coating layer delays the oxidation of the cobalt salt and ensures the initial color change at 200°C. The nickel salt is a NiTiO3-ZnWO4 solid solution, and the molar ratio of NiTiO3 to ZnWO4 is 1:1. The color development at 500°C is realized by band regulation. The liquid crystal microcapsule encapsulates carbon black precursor, and the carbon black precursor is a composite of one or both of polyaniline and Fe3O4. At 700°C, the capsule ruptures to release Fe3O4 to catalyze carbonization, and the coating irreversibly turns black.

[0031] Further, the flame retardant is nano-aluminum hydroxide, expanded graphite and silane coupling agent. The nano-aluminum hydroxide and the expanded graphite are compounded in a mass ratio of 2:1. The particle size of the nano-aluminum hydroxide is 50 nm, and the interlayer spacing of the expanded graphite is greater than or equal to 0.8 nm. The content of the silane coupling agent is 2%, and the silane coupling agent is used for surface modification to improve the dispersibility. The corrosion-resistant filler is mica powder, glass flake and zinc phosphate corrosion inhibitor. The mica powder and the glass flake are stacked in a mass ratio of 1:2. The diameter-to-thickness ratio of the mica powder is greater than 50, and the thickness of the glass flake is 1-3 μm. The weight fraction of the zinc phosphate corrosion inhibitor is 1-2 parts to form a labyrinthine anti-permeation barrier. The additives are dispersant, defoamer and UV absorber.

[0032] AsFigures 1-4 As shown, a device for producing a temperature-indicating and corrosion-inhibiting coating for bridge fire protection in one embodiment of the present invention includes a dispersion mechanism 1, a grinding mechanism 2, a protection component 3 and a spraying and curing integrated machine.

[0033] like Figures 1-4 As shown, the dispersion mechanism 1 includes a dispersion kettle body 11. A rotating head 12 is rotatably connected to the bottom wall of the dispersion kettle body 11. The side walls of the rotating head 12 are equipped with multi-stage turbine dispersion blades. The rotation of the rotating head 12 drives the multi-stage turbine dispersion blades to rotate and crush and disperse the material. A first screen 18 is installed in the dispersion kettle body 11. The first screen 18 is positioned above the multi-stage turbine dispersion blades and screens the dispersed homogeneous glue liquid.

[0034] Optionally, since the homogeneous glue has strong viscosity, it needs to be screened through the first screen 18 under the centrifugal force and high-pressure gas. At the same time, the first screen 18 adheres to the homogeneous glue and needs to be cleaned in time. Therefore, when the first screen 18 affects the conveying effect of the homogeneous glue, the homogeneous glue can be transported by pumping.

[0035] like Figures 1-4 As shown, the multi-stage turbine dispersion blades include a first turbine blade 13, a second turbine blade 14, and a third turbine blade 15. The first turbine blade 13, the second turbine blade 14, and the third turbine blade 15 are respectively installed on the side wall of the rotating head 12 from bottom to top. The first turbine blade 13, the second turbine blade 14, and the third turbine blade 15 are all inclined. The angles between the first turbine blade 13, the second turbine blade 14, and the third turbine blade 15 and the horizontal plane are 15 degrees, 30 degrees, and 45 degrees, respectively, so as to optimize the fluid shear path, make the nanoparticles dispersed uniformly, and improve the dispersion effect on the material, thereby reducing energy consumption. A first drive shaft 16 is rotatably connected to the bottom wall plate of the dispersion kettle body 11. The upper end of the first drive shaft 16 is fixedly connected to the bottom of the rotating head 12. The lower end of the first drive shaft 16 is installed with a first high-speed motor 17. The first drive shaft 16 is driven to rotate by the first high-speed motor 17, and the rotation of the first drive shaft 16 drives the rotating head 12 to rotate. A feed pipe 19 is mounted on the side wall of the dispersion vessel body 11. Material is added to the dispersion vessel body 11 through the feed pipe 19 for shear dispersion. A discharge pipe 110 is mounted on the bottom wall of the dispersion vessel body 11. This discharge pipe 110 is equipped with an on / off valve 111. The dispersed homogenized adhesive can be discharged through the discharge pipe 110 and then pumped. A delivery pipe 112 is mounted on the top wall of the dispersion vessel body 11. The homogenized adhesive can also be screened by high-pressure gas through the first screen 18 and then delivered through the delivery pipe 112.

[0036] like Figures 1-4As shown, the grinding mechanism 2 comprises a grinding cavity body 21, a grinding disc 22 is rotatably connected to the bottom wall plate in the grinding cavity body 21, a plurality of honeycomb grooves 23 are formed in the top of the grinding disc 22, a plurality of zirconia grinding beads 24 are arranged on the top of the grinding disc 22, the rotation of the grinding disc 22 can drive the plurality of zirconia grinding beads 24 to roll, and the plurality of zirconia grinding beads 24 can finely grind the material when rolling. The honeycomb groove 23 forms a multidirectional flow channel, reduces the grinding dead angle, promotes the mixing of the material and the zirconia grinding bead 24, can guide the grinding bead to form a vortex under the action of centrifugal force, prolong the residence time of the material, and increase the number of effective collisions. The second screen 26 is installed on the grinding disc 22, and the ground material is screened by the second screen 26 under the action of centrifugal force.

[0037] As shown in Figure 4 , Figure 8 and Figure 9 , the honeycomb groove 23 is arranged as a hexagonal honeycomb structure, the edge of the honeycomb groove 23 forms a local high shear zone, the zirconia grinding bead 24 and the grinding disc 22 interact with each other, and stronger shear force is generated, which is suitable for high-viscosity materials. The length of the hexagonal honeycomb groove 23 is set to 0.75-1.5mm, the depth of the honeycomb groove 23 is set to 1-1.8mm, the diameter of the zirconia grinding bead 24 is set to 0.3-0.6mm, and the edge of the grinding cavity body 21 is integrally formed with a shielding frame 25. The second screen 26 is installed on the shielding frame 25, and the shielding frame 25 can shield the zirconia grinding bead 24. The bottom wall plate of the grinding cavity body 21 is rotatably connected with a second driving shaft 27, the upper end of the second driving shaft 27 is fixedly connected to the bottom of the grinding disc 22, and the lower end of the second driving shaft 27 is provided with a second high-speed motor 28. The side wall of the second driving shaft 27 is fixedly connected with a pair of rotating plates 29 above the bottom wall plate of the grinding cavity body 21, the bottom of the side wall of the grinding cavity body 21 is provided with a discharge port 210, the outer side of the discharge port 210 is fixedly connected with a material conveying groove 211, and when the second driving shaft 27 drives the rotating plate 29 to rotate, the ground and screened material can be discharged through the discharge port 210. The end of the material conveying pipe 112 away from the dispersion kettle body 11 penetrates through the top wall plate of the grinding cavity body 21 and is arranged in the grinding cavity body 21, and the outlet end of the material conveying pipe 112 arranged in the grinding cavity body 21 is located below the side of the second conveying pipe 35, so that the nitrogen gas sprayed by the second conveying pipe 35 can homogenize the material conveyed by the material conveying pipe 112.

[0038] As shown in Figures 1-4As shown, the protective assembly 3 includes a heat exchange chamber 31, which is used to adjust the temperature of liquid nitrogen so that the liquid nitrogen is converted into nitrogen gas and transported after the temperature is adjusted. A first delivery pipe 32 and a second delivery pipe 35 are respectively installed at the left and right ends of the heat exchange chamber 31. The end of the first delivery pipe 32 away from the heat exchange chamber 31 passes through the side wall of the dispersion kettle body 11 and is placed in the dispersion kettle body 11. The nitrogen in the heat exchange chamber 31 is transported to the dispersion kettle body 11 through the first delivery pipe 32, so that the material is dispersed under the protection of nitrogen. The nitrogen not only allows the dispersion of the material in the dispersion kettle body 11 to be carried out in an oxygen-free environment, but also controls the temperature of the material during dispersion, ensuring that heat-sensitive materials will not be denatured. One end of the second delivery pipe 35 away from the heat exchange chamber 31 passes through the side wall of the grinding chamber body 21 and is placed in the grinding chamber body 21. The nitrogen in the heat exchange chamber 31 is delivered to the grinding chamber body 21 through the second delivery pipe 35, so that the material can be ground under the protection of nitrogen. The nitrogen not only allows the material in the dispersion kettle body 11 to be dispersed in an oxygen-free environment, but also can control the temperature of the material during grinding through nitrogen to ensure that heat-sensitive materials will not be denatured.

[0039] like Figures 4-7As shown, one end of the first conveying pipe 32 arranged in the dispersion kettle body 11 is provided with a vertical section, the vertical section of the first conveying pipe 32 is located directly above the rotating head 12, and a plurality of first nozzles 34 are arranged on the vertical section of the first conveying pipe 32 in a downward inclined manner, so that the nitrogen gas is uniformly discharged into the dispersion kettle body 11 through the plurality of first nozzles 34, and the nitrogen gas sprayed by the first nozzles 34 can also clean the dispersion blades when protecting and cooling the material. The first conveying pipe 32 is provided with a first flow regulating valve 33, and the first flow regulating valve 33 is used to control the flow and pressure of the nitrogen gas conveyed into the first conveying pipe 32. The second conveying pipe 35 is provided with a second flow regulating valve 36, and one end of the second conveying pipe 35 arranged in the grinding cavity body 21 is provided with a vertical section, the vertical section of the second conveying pipe 35 coincides with the central axis of the grinding cavity body 21, and a atomizer 37 is fixedly connected below the vertical section of the second conveying pipe 35. A plurality of second nozzles 38 are arranged on the bottom wall plate of the atomizer 37 in an outwardly diffusing inclined manner, the nitrogen gas conveyed through the second conveying pipe 35 is sprayed onto the grinding disc 22 after being uniformly diffused through the second nozzles 38, so that the nitrogen gas can protect and cool the material ground on the grinding disc 22 at the same time, and ensure that the friction between the zirconium oxide grinding beads 24 and the material will not cause the pyrolysis and denaturation of the heat-sensitive material. The sidewall top of the heat exchange chamber 31 is provided with a liquid nitrogen conveying pipe 39, the liquid nitrogen conveying pipe 39 is provided with a third flow regulating valve 310, the amount of liquid nitrogen conveyed by the liquid nitrogen conveying pipe 39 is controlled through the third flow regulating valve 310, the precise adjustment of the content of the conveyed liquid nitrogen is realized, and the waste of liquid nitrogen is avoided. The sidewall bottom of the heat exchange chamber 31 is provided with a glycol aqueous solution conveying pipe 311, the glycol aqueous solution conveying pipe 311 is provided with a fourth flow regulating valve 312, and the glycol aqueous solution conveying pipe 311 is used to carry the cold source, so as to convey the temperature-adjusted liquid nitrogen after mixing with the liquid nitrogen in the heat exchange chamber 31.

[0040] Specifically, the spraying and curing integrated machine includes a high-voltage electrostatic spray gun and a curing furnace. The high-voltage electrostatic spray gun is provided with a micro eddy current generator to form a ring-shaped airflow and improve the uniformity of the paint. The curing furnace adopts infrared radiation and hot air circulation composite heating to effectively cure the temperature indicating paint after spraying, thereby ensuring the uniformity and strength of the temperature indicating paint after spraying. In order to realize intelligent spraying, a high-resolution thermal imaging camera and an AI image recognition system can be carried during spraying to detect defects such as coating pinholes and cracks in real time.

[0041] It should be noted that, in order to facilitate the intelligent operation of the device, necessary sensors and electrical elements are provided, and automatic or semi-automatic control of the present application can be realized by a single-chip microcomputer or other control equipment in cooperation with necessary sensors and electrical elements, which are known to those skilled in the art and will not be described here.

[0042] In an embodiment of the present application, a preparation method of a temperature indicating corrosion inhibiting coating for bridge fire prevention is provided. The preparation method comprises: S1, thermal material pretreatment, CoCrO4@SiO2core-shell microspheres are synthesized by sol-gel method, surface modification is performed using silane coupling agent to enhance the interface bonding with resin; liquid crystal microcapsules are prepared by microfluidic emulsification-ultraviolet curing.

[0043] S2, raw material preparation, the base resin is compounded by fluorocarbon resin base and silicone modified acrylic resin at a ratio of 4:1; the flame retardant is mixed by nano aluminum hydroxide and expanded graphite at a ratio of 2:1, and is surface modified by silane coupling agent; the corrosion inhibitor is mixed by mesoporous silica loaded with ammonium polyphosphate, organic modified montmorillonite intercalated with benzotriazole and silane microcapsules at a weight ratio of 5:3:2; the anticorrosive filler is compounded by mica powder and glass flake at a ratio of 1:2, and 1.5% zinc phosphate corrosion inhibitor is added.

[0044] S3, pre-dispersion stage, the base resin and mixed solvent are added to the dispersion kettle body 11 at a ratio of 1:1, nitrogen protection is started, and high-speed shearing dispersion is performed at 5000 r / min for 15 minutes; then the flame retardant, corrosion inhibitor and anticorrosive filler are added in turn, and ultrasonic assisted dispersion is performed for 30 minutes to form a homogeneous glue solution.

[0045] S4, grinding stage, the homogeneous glue solution is added to the grinding cavity body 21, liquid nitrogen cooling is started, and the thermal material is added in stages; CoCrO4@SiO2microspheres are added first, and grinding is performed at 1500 r / min for 20 minutes; then NiTiO3-ZnWO4solid solution is added, the speed is reduced to 1200 r / min, and grinding is performed for 15 minutes; finally, liquid crystal microcapsules are added, the speed is 800 r / min, and grinding is performed for 10 minutes; the speed is adjusted to 3000 r / min for dynamic centrifugal classification, the slurry with D90≤20 nm is separated, and the coarse particles are returned to grinding. By adjusting the speed when adding different thermal materials, it is ensured that the zirconia grinding beads 24 will not damage the structure of the thermal material during grinding.

[0046] S5, spraying and curing, the slurry after grinding is filtered through a 200 mesh screen, and 3% defoaming agent is added; the bridge substrate surface is uniformly coated by electrostatic spraying, the voltage is set to 80 kV during spraying, and the spraying distance is set to 15 cm; the solvent is preliminarily volatilized by infrared radiation under the condition of 60℃ / 10min; a crosslinked network is formed by hot air circulation under the condition of 80℃ / 30min+120℃ / 1h; and the temperature is naturally cooled to below 40℃, and the whole process is protected by nitrogen, so that the temperature indicating paint can be uniformly sprayed on the bridge mechanism.

[0047] In one or more embodiments of the present application, the SiO2 shell thickness in S1 is 20-30 nm, the particle size of the core-shell microspheres is 50-100 nm, and the particle size of the liquid crystal microcapsule is 50-100 nm; the temperature in S3 and S4 is controlled at-10-30 DEG C, the particle size Span value of the finished slurry in S4 is less than or equal to 0.8; the coating thickness in S5 is set to 80+5 mu m, and the adhesion is greater than or equal to 5 MPa.

[0048] Preferably, the particle size Span value of the finished slurry in S4 is less than or equal to 0.8, so that the heat-sensitive material is uniformly dispersed, the three-stage temperature response is more accurate; the coating has no defects, and the long-acting corrosion and flame-retardant properties are stable; the spraying process is efficient and smooth, greatly improving the raw material utilization rate.

[0049] It will be obvious to a person skilled in the art that, as the application is not limited to the details of the exemplary embodiments described above, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the application. Therefore, the embodiments should be considered as exemplary and non-limiting, and the scope of the application is defined by the appended claims rather than the above description, and all changes falling within the meaning and range of the equivalent elements of the claims are intended to be included in the application. Any reference signs in the claims should not be considered as limiting the claims involved.

[0050] Furthermore, it should be understood that, although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the present specification is described in this way only for the sake of clarity, and a person skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by a person skilled in the art.

Claims

1. A temperature-indicating and corrosion-inhibiting coating for bridge fire protection, characterized in that: The raw material components of the coating are base resin, heat-sensitive material, flame retardant, corrosion inhibitor, anti-corrosion filler and additives; The weight proportions of the components are as follows: 45-55 parts of base resin, 17-23 parts of heat-sensitive material, 15-18 parts of flame retardant, 15-20 parts of corrosion inhibitor, 8-10 parts of anticorrosive filler and 3-5 parts of auxiliary agent. The thermosensitive material includes cobalt salt, nickel salt and liquid crystal microcapsules, which form a three-level thermosensitive material; the corrosion inhibitor includes mesoporous silica loaded with ammonium polyphosphate, organically modified montmorillonite intercalated with benzotriazole and silane microcapsules, so as to form a composite corrosion inhibitor with flame retardant slow release, anti-corrosion slow release and self-repairing functions.

2. The temperature-indicating and corrosion-inhibiting coating for bridge fire protection according to claim 1, characterized in that: The raw material components of the base resin include weather-resistant fluorocarbon resin, silicone-modified acrylic resin, isocyanate curing agent and silane coupling agent, wherein the weather-resistant fluorocarbon resin and the silicone-modified acrylic resin are compounded in a mass ratio of 3:1 to 5:1, the weight portion of the isocyanate curing agent is 3 to 5 parts, and the weight portion of the silane coupling agent is 0.5 to 1.5 parts.

3. The temperature-indicating and corrosion-inhibiting coating for bridge fire protection according to claim 1, characterized in that: The cobalt salt is CoCrO4, the outer layer of the CoCrO4 is wrapped with SiO2 to form CoCrO4@SiO2 core-shell structure microspheres, the nickel salt is a NiTiO3-ZnWO4 solid solution, the molar ratio of NiTiO3 and ZnWO4 is 1:1, and the liquid crystal microcapsules contain a carbon black precursor, which is a composite of one or both of polyaniline and Fe3O4.

4. The temperature-indicating and corrosion-inhibiting coating for bridge fire protection according to claim 1, characterized in that: The flame retardant is nano aluminum hydroxide, expanded graphite and a silane coupling agent. The nano aluminum hydroxide and the expanded graphite are compounded in a mass ratio of 2:

1. The particle size of the nano aluminum hydroxide is 50 nm, the interlayer spacing of the expanded graphite is ≥0.8 nm, and the content of the added silane coupling agent is 2%; the anti-corrosion filler is mica powder, glass flakes and a zinc phosphate corrosion inhibitor. The mica powder and the glass flakes are stacked in a mass ratio of 1:2, the diameter-to-thickness ratio of the mica powder is >50, the thickness of the glass flakes is 1~3 μm, and the weight portion of the zinc phosphate corrosion inhibitor is 1~2 parts; the auxiliary agents are a dispersant, a defoaming agent and a UV absorber.

5. A device for producing a temperature-indicating and corrosion-inhibiting coating for bridge fire protection, used for producing a temperature-indicating and corrosion-inhibiting coating for bridge fire protection as claimed in claims 1 to 4, characterized in that: The production equipment includes: The dispersion mechanism includes a dispersion kettle body, a rotating head rotatably connected to a bottom wall plate of the dispersion kettle body, a multi-stage turbine dispersion blade installed on the side wall of the rotating head, and a first screen installed in the dispersion kettle body, the first screen being arranged above the multi-stage turbine dispersion blade; The grinding mechanism includes a grinding chamber body, wherein a grinding disc is rotatably connected to a bottom wall plate of the grinding chamber body, a plurality of honeycomb grooves are formed on the top of the grinding disc, a plurality of zirconia grinding beads are arranged on the top of the grinding disc, and a second screen is installed on the grinding disc; The protective assembly includes a heat exchange chamber, with a first delivery pipe and a second delivery pipe installed at the left and right ends of the heat exchange chamber respectively. The end of the first delivery pipe away from the heat exchange chamber passes through the side wall of the dispersion kettle body and is placed in the dispersion kettle body. The end of the second delivery pipe away from the heat exchange chamber passes through the side wall of the grinding chamber body and is placed in the grinding chamber body. The spraying and curing all-in-one machine comprises a high-voltage electrostatic spray gun and a curing oven. The high-voltage electrostatic spray gun is equipped with a micro eddy current generator, and the curing oven adopts infrared radiation and hot air circulation composite heating.

6. The manufacturing equipment of the temperature-indicating and corrosion-inhibiting coating for bridge fire protection according to claim 5 is characterized in that: The multi-stage turbine dispersion blades include a first turbine blade, a second turbine blade and a third turbine blade, and the first turbine blade, the second turbine blade and the third turbine blade are respectively installed on the side wall of the rotating head from bottom to top, and the first turbine blade, the second turbine blade and the third turbine blade are all inclined. The angles between the first turbine blade, the second turbine blade and the third turbine blade and the horizontal plane are 15 degrees, 30 degrees and 45 degrees respectively. A first drive shaft is rotatably connected to the bottom wall plate of the dispersion kettle body, the upper end of the first drive shaft is fixedly connected to the bottom of the rotating head, and a first high-speed motor is installed at the lower end of the first drive shaft. A feed pipe is installed on the side wall of the dispersion kettle body, a discharge pipe is installed on the bottom wall plate of the dispersion kettle body, a switch valve is installed on the discharge pipe, and a conveying pipe is installed on the top wall plate of the dispersion kettle body.

7. The manufacturing equipment of the temperature-indicating and corrosion-inhibiting coating for bridge fire protection according to claim 6 is characterized in that: The honeycomb groove is set to a hexagonal honeycomb structure, the side length of the hexagon of the honeycomb groove is set to 0.75~1.5mm, the depth of the honeycomb groove is set to 1~1.8mm, the diameter of the zirconia grinding beads is set to 0.5~1mm, and a shielding frame is integrally formed on the edge of the grinding chamber body. The second screen is installed on the shielding frame, and the second drive shaft is rotatably connected to the bottom wall plate of the grinding chamber body. The upper end of the second drive shaft is fixedly connected to the bottom of the grinding disc, and the lower end of the second drive shaft is installed with a second high-speed motor. The side wall of the second drive shaft is fixedly connected to a pair of rotating plates above the bottom wall plate of the grinding chamber body. A discharge port is provided at the bottom of the side wall of the grinding chamber body, and a feed trough is fixedly connected to the outside of the discharge port. The end of the feed pipe away from the dispersion kettle body passes through the top wall plate of the grinding chamber body and is placed in the grinding chamber body. The outlet end of the feed pipe placed in the grinding chamber body is located on the side and lower side of the second conveying pipe.

8. The manufacturing equipment of the temperature-indicating and corrosion-inhibiting coating for bridge fire protection according to claim 7 is characterized in that: One end of the first delivery pipe placed in the dispersion kettle body is provided with a vertical section, the vertical section of the first delivery pipe is located directly above the rotating head, a plurality of first nozzles are provided on the vertical section of the first delivery pipe in a downwardly inclined manner, a first flow regulating valve is installed on the first delivery pipe, a second flow regulating valve is installed on the second delivery pipe, and one end of the second delivery pipe placed in the grinding chamber body is provided with a vertical section, the vertical section of the second delivery pipe coincides with the central axis of the grinding chamber body, an atomizer is fixedly connected below the vertical section of the second delivery pipe, a plurality of second nozzles are provided on the bottom wall plate of the atomizer in an inclined manner that diffuses outward, a liquid nitrogen delivery pipe is installed on the top of the side wall of the heat exchange chamber, a third flow regulating valve is installed on the liquid nitrogen delivery pipe, an ethylene glycol aqueous solution delivery pipe is installed on the bottom of the side wall of the heat exchange chamber, and a fourth flow regulating valve is installed on the ethylene glycol aqueous solution delivery pipe.

9. A method for preparing a temperature-indicating and corrosion-inhibiting coating for bridge fire protection, used for a production device of a temperature-indicating and corrosion-inhibiting coating for bridge fire protection according to any one of claims 5 to 8, characterized in that: The preparation method comprises: S1. Pretreatment of thermosensitive materials: Synthesis of CoCrO4@SiO2 core-shell microspheres by sol-gel method, surface modification with silane coupling agent to enhance interfacial bonding with resin; Preparation of liquid crystal microcapsules by microfluidic emulsification-UV curing; S2. Raw material preparation: base resin is prepared by compounding fluorocarbon resin base and silicone-modified acrylic resin in a ratio of 4:1; flame retardant is prepared by mixing nano-aluminum hydroxide and expanded graphite in a ratio of 2:1 and surface-modified with a silane coupling agent; corrosion inhibitor is prepared by mixing mesoporous silica loaded with ammonium polyphosphate, organically modified montmorillonite intercalated with benzotriazole, and silane microcapsules in a weight ratio of 5:3:2; anti-corrosion filler is prepared by compounding mica powder and glass flakes in a ratio of 1:2 and adding 1.5% zinc phosphate corrosion inhibitor; S3, pre-dispersion stage, base resin and mixed solvent are added into the dispersion kettle body in a ratio of 1:1, nitrogen protection is turned on, and high-speed shear dispersion is carried out at 5000r / min for 15 minutes; then flame retardant, corrosion inhibitor and anti-corrosion filler are added in sequence, and ultrasonic assisted dispersion is carried out for 30 minutes to form a homogeneous glue solution; S4, grinding stage, add the homogenized glue into the grinding chamber body, start liquid nitrogen cooling, and add the heat-sensitive material in stages; first add CoCrO4@SiO2 microspheres and grind at 1500r / min for 20 minutes; then add NiTiO3-ZnWO4 solid solution, reduce the speed to 1200r / min, and grind for 15 minutes; finally add liquid crystal microcapsules, grind at 800r / min for 10 minutes; adjust the speed to 3000r / min for dynamic centrifugal classification, separate the slurry with D90≤20nm, and return the coarse particles for grinding; S5. Spray curing. Filter the ground slurry through a 200-mesh sieve and add 3% defoaming agent. Use electrostatic spraying to evenly coat the surface of the bridge substrate. Set the voltage to 80kV and the spray distance to 15cm during spraying. Preheat with infrared radiation at 60℃ / 10min to initially evaporate the solvent. Circulate hot air at 80℃ / 30min+120℃ / 1h to form a cross-linked network. Naturally cool to below 40℃ with nitrogen protection throughout the process, so that the temperature-indicating coating can be evenly sprayed on the bridge structure.

10. The method for preparing a temperature-indicating and corrosion-inhibiting coating for bridge fire protection according to claim 9, characterized in that: The SiO2 shell thickness in S1 is 20~30nm, the particle size of the core-shell microspheres is 50~100nm, and the particle size of the liquid crystal microcapsules is 50~100nm; the temperature in S3 and S4 is controlled at -10~30℃, and the Span value of the finished slurry particle size in S4 is ≤0.8; the coating thickness in S5 is set to 80±5μm, and the adhesion is ≥5MPa.

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