Composite magnesium cement fireproof and anticorrosive integrated coating and preparation method thereof

Abstract

The invention relates to a composite magnesium cement fireproof and anticorrosion integrated coating and a preparation method thereof, and belongs to the technical field of building materials, the coating comprises an inorganic cement component, a foaming component and a function regulation component; the inorganic cement component is prepared from the following components in percentage by mass: (1) 50%-60% of a magnesium material, (2) 25%-40% of phosphate and (3) 0-5% of a retarder; the sum of the mass percentages of the components is 100%. Based on the total mass of the inorganic cement components, foaming components are additionally added and comprise (1) 1%-5% of ammonium polyphosphate, (2) 0.5%-3% of pentaerythritol and (3) 0.5%-3% of melamine; the function regulation and control component comprises (1) 2%-8% of a toughening material, (2) 0.5%-1.5% of an interface modifier, (3) 1.5%-5% of a light heat insulation filler, (4) 1%-5% of an auxiliary flame retardant and (5) 0.1%-2% of an auxiliary agent. The preparation method comprises the following steps: (1) preparing powder components; (2) preparing a liquid component; and (3) double-component spraying construction. The coating is thin in coating, high in cohesiveness, excellent in corrosion resistance, high in fire endurance and suitable for mechanical spraying.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically a composite magnesium cement fireproof and anti-corrosion integrated coating and its preparation method. Background Technology

[0002] With the increasing sophistication, scale, and complexity of modern architecture, and the ever-increasing safety requirements for industrial facilities, fire protection and corrosion protection of structures have become critical issues in the field of building materials. Steel structures are widely used in such constructions, but their low fire resistance limit leads to rapid strength loss at high temperatures, resulting in structural collapse. Furthermore, electrochemical corrosion of metals is a significant problem in corrosive environments such as chemical plants and marine environments. Therefore, developing a coating material that can simultaneously provide both highly efficient fire protection and durable corrosion protection is of great importance for ensuring the safety of life and property and extending the service life of structures.

[0003] Currently, the steel structure protection field generally adopts a technical system of separate application of fire-retardant and anti-corrosion coatings. This is mainly due to the functional limitations of the two types of materials: the organic resin film-forming base of conventional anti-corrosion coatings lacks high-temperature resistance, and the flame-retardant system of fire-retardant coatings struggles to provide long-term rust prevention in complex corrosive environments. Anti-corrosion coatings typically employ a multi-layer system of "primer-intermediate coat-topcoat," acting as a protective barrier between the substrate and its corrosive environment, protecting it from exposure to moisture, chemicals, and other corrosive substances. The synergistic use of fire-retardant and anti-corrosion coatings often faces multiple technical challenges. For example, insufficient physical adhesion between the fire-retardant coating and the anti-corrosion topcoat may lead to weakened interfacial peel strength under high-temperature conditions. After high-temperature carbonization, the bonding strength between the carbonized layer and the steel substrate degrades; simultaneously, the mismatch in thermal expansion coefficients between the fire-retardant layer and the inorganic primer can induce shear stress concentration under thermal cyclic loading, ultimately leading to system delamination failure.

[0004] Although researchers have attempted to develop multifunctional integrated coatings through physical blending or simple compounding, the problems are often not fundamentally solved due to poor compatibility between components and weak functional synergy. Chinese Patent CN106497157B discloses a potassium magnesium phosphate cement-based fire-retardant coating for steel structures, its preparation method, and its application method. The fire-retardant coating, with a thickness of not less than 20 mm, has a fire resistance limit of 2.6 hours. However, such magnesium phosphate cement-based coatings generally suffer from short workability and difficulty in controlling the curing rate during actual construction, seriously affecting their large-scale engineering application. Chinese Patent CN106318128A discloses an outdoor ultra-thin fire-retardant coating, which is compounded by adding a bromine-containing flame retardant and nanomaterials. However, this patent uses a bromine-containing flame retardant and nanomaterials for corrosion protection, still posing a risk of deterioration in the synergistic effect between coating durability and fire and corrosion resistance. Chinese patent CN106752888A discloses an ultra-thin fire-retardant coating. This patent uses inorganic heat-insulating fillers and an organic expansion system. Although the coating system has a thickness of 2mm and a fire resistance limit of not less than 1 hour, it does not address the long-term durability and corrosion resistance of the coating in complex environments. Therefore, fire-retardant coatings suffer from problems such as thick coatings, short fire resistance time, insufficient adhesion to the substrate, and the need for layer-by-layer application with anti-corrosion coatings. This invention aims to improve the overall performance of a novel fire-retardant coating by developing a lightweight, fire-resistant, highly adhesive, corrosion-resistant, and easy-to-apply fire-retardant material. Summary of the Invention

[0005] To address the aforementioned shortcomings, this invention provides a composite magnesium cement fireproof and corrosion-resistant integrated coating and its preparation method. This method utilizes a magnesium cement matrix, foaming components, toughening materials, interface modifiers, lightweight heat-insulating fillers, auxiliary flame retardants, and additives to prepare a thin, high-fire-resistance, and corrosion-resistant integrated fireproof and corrosion-resistant coating that fully meets the requirements of the "Fireproof Coatings for Steel Structures" specification. It avoids the complexity of layering fireproof and corrosion-resistant coatings in traditional construction, effectively improving the coating's durability and construction efficiency, and fully complies with the relevant requirements of the "Fireproof Coatings for Steel Structures" specification.

[0006] The technical solution of this invention is:

[0007] A composite magnesium cement fireproof and anticorrosive integrated coating, characterized in that the composite magnesium cement fireproof and anticorrosive coating includes an inorganic cement component, a foaming component, and a functional regulating component; the inorganic cement component is composed of the following components by mass percentage: (1) 50%-60% magnesium material, (2) 25%-40% phosphate, (3) 0-5% retarder; and the sum of the mass percentages of each component is 100%; based on the total mass of the inorganic cement component, the following components are added in addition: the foaming component includes: (1) 1%-5% ammonium polyphosphate, (2) 0.5%-3% pentaerythritol, (3) 0.5-3% melamine; the functional regulating component includes: (1) 2%-8% toughening material, (2) 0.5%-1.5% interface modifier, (3) 1.5%-5% lightweight heat insulation filler, (4) 1-5% auxiliary flame retardant; (5) 0.1-2% additives.

[0008] The amount of water added to the coating during preparation and application is 20%-40% of the total mass of the inorganic cement components.

[0009] The magnesium material in the inorganic cement component is brucite powder with a particle size range of 100-200μm. The Mg(OH)2 content in the brucite is not less than 80%, the carbonate mineral content (such as magnesite, dolomite, etc.) is not more than 8%, and the remaining main components are natural minerals such as silicates, mainly serpentine, with a content of 2-10%.

[0010] The phosphate in the inorganic cement component is prepared by mixing ammonium dihydrogen phosphate and aluminum dihydrogen phosphate in a mass ratio of 8:2; the retarder is borax.

[0011] The toughening material in the functional regulating component includes one or more of polyurethane acrylate emulsion, polyethersulfone emulsion, styrene-acrylic emulsion, and waterborne epoxy emulsion, and the solid content of the emulsion is 40%-55%.

[0012] The interface modifier in the functional regulating component includes one or more of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

[0013] The lightweight thermal insulation filler in the functional regulating component includes one or more of expandable graphite, hollow glass microspheres, mullite fiber, aluminosilicate fiber, silica aerogel, or expanded clay; the expandable graphite has an expansion ratio of 200-400 times and an expansion temperature of 200-300℃; the hollow glass microspheres have a true density of 0.2-0.4 g / cm³. 3 It has a thermal conductivity of 0.03-0.05 W / (m·k) and a compressive strength greater than 30 MPa.

[0014] The auxiliary flame retardants in the functional regulating components include one or more of zinc molybdate, boron nitride nanosheets, graphene oxide, or zinc ferrite.

[0015] The functional regulating components include one or more of sodium bicarbonate, sodium carboxymethyl cellulose, silicone amide, or ammonium carbamate.

[0016] A method for preparing a composite magnesium cement fireproof and corrosion-resistant integrated coating, characterized in that the coating is a two-component system, comprising a powder component (component A) and a liquid component (component B); the preparation method includes the following steps:

[0017] ①Preparation of powder components:

[0018] Magnesium materials, lightweight heat-insulating fillers, auxiliary flame retardants and additives are added to a mixer in sequence according to the formula ratio and dry-mixed at 300-500 rpm for 8-10 minutes to obtain a uniform base material; then ammonium polyphosphate, pentaerythritol and melamine are added and mixed for another 3-5 minutes to make the foaming components uniformly dispersed in the inorganic powder to obtain powder component A.

[0019] ②Preparation of liquid components:

[0020] Add phosphate and retarder to 70 wt% of the total water volume and stir for 3-5 min until fully dissolved to obtain a phosphate solution; dilute the interface modifier with ethanol and the remaining 30 wt% water at an ethanol to water mass ratio of 1:(5-10), stir and hydrolyze for 10 min, then mix with the toughening material and stir for 10-20 min to form a pre-modified emulsion; mix the pre-modified emulsion with the phosphate solution evenly to obtain liquid component B;

[0021] ③ Spray coating application:

[0022] Powder component A and liquid component B are placed in the powder hopper and liquid hopper of the two-component high-pressure airless spraying equipment, respectively. They are mixed in real time at the spray gun end through independent pipelines and then atomized and sprayed by a high-pressure pump. The construction adopts layered spraying, with the thickness of each layer controlled at 1-2mm, until the total coating thickness is reached.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1) Composite fireproof and heat-insulating performance

[0025] This invention combines magnesium cement with foaming components, and adds toughening materials and interface modifiers to form an inorganic-organic composite coating system. This allows the coating, even when applied thinly under fire conditions, to effectively block heat transfer, slowing the temperature rise of steel structures and other load-bearing components, thereby significantly improving its fire resistance. The introduction of lightweight materials reduces the overall density of the coating, making it difficult for heat to conduct rapidly. Simultaneously, the coating expands at high temperatures, forming a thermal barrier and a porous carbonized layer, effectively blocking flame spread and oxygen diffusion. This design not only ensures the high-temperature stability of the coating but also improves the feasibility of thin-layer application and structural protection, making the coating significantly superior in fire safety to traditional single inorganic or organic coatings.

[0026] 2) Improved mechanical stability and durability

[0027] This invention utilizes an inorganic-organic composite system design, enabling the coating to maintain structural integrity and adhesion under high-temperature, fire, and long-term use conditions. The composite fibers, functional fillers, and toughening materials work synergistically to improve the coating's resistance to peeling, cracking, and impact, while also enhancing its abrasion and weathering resistance. The thin-layer coating exhibits significantly superior residual strength, toughness, and peeling resistance after a fire compared to existing single-layer systems, providing long-term protection for steel structures and load-bearing components from high temperatures, impacts, or external forces, thereby extending the service life of the coating and the load-bearing structure and improving the overall safety and reliability of the project.

[0028] 3) Construction-friendly and lightweight advantages

[0029] The composite coating of this invention exhibits excellent dispersibility, flowability, and application adaptability. It can be applied in thin layers via two-component spraying, while also providing corrosion protection without the need for an additional anti-corrosion coating, thus reducing construction steps and material consumption, and simplifying the construction process. The coating is lightweight, which helps reduce structural weight and construction difficulty. The thin-layer design also improves construction efficiency and shortens the construction cycle. While maintaining a balance of fire resistance, heat insulation, and corrosion protection, the coating of this invention has good engineering applicability and operability, and is particularly suitable for coating large-area steel structures or complex components.

[0030] 4) Environmental adaptability and overall safety

[0031] This invention utilizes the synergistic effect of its components to form a stable and dense composite structure, enabling the coating to maintain excellent performance even under complex environments such as fire, humidity, high temperature, and corrosion. The coating not only provides excellent thermal insulation and oxygen barrier properties but also effectively slows down the corrosion process of steel structures and load-bearing components, enhancing their durability. The porous carbonized structure strengthens the overall stability of the coating, ensuring greater safety and reliability for buildings and facilities during long-term use, while reducing maintenance costs and providing reliable protection against fire and corrosion in complex environments. Detailed Implementation

[0032] The present invention will be described in detail below with reference to embodiments. The embodiments are only used to describe the principles and features of the present invention and are only used to explain the present invention, and are not intended to limit the scope of the present invention.

[0033] Example 1

[0034] A composite magnesium cement fireproof and corrosion-resistant integrated coating, the formulation and preparation steps are as follows:

[0035] 1. The composite magnesium cement fireproof and anticorrosive integrated coating includes an inorganic cement component, a foaming component, and a functional regulating component; the inorganic cement component is composed of the following components by mass percentage: (1) 60% magnesium material, (2) 35% phosphate, (3) 5% retarder; and the sum of the mass percentages of each component is 100%; based on the total mass of the inorganic cement component, the following components are added in addition: the foaming component includes: (1) 3% ammonium polyphosphate, (2) 1.5% pentaerythritol, (3) 1.5% melamine; the functional regulating component includes: (1) 5% toughening material, (2) 1% interface modifier, (3) 3% lightweight heat insulation filler, (4) 2% auxiliary flame retardant, (5) 0.4% additives.

[0036] 2. The amount of water added during the preparation and application of the coating is 30% of the total mass of the inorganic cement components.

[0037] 3. The magnesium material in the inorganic cement component is brucite powder with a particle size range of 100-200μm. The Mg(OH)2 content in the brucite is 85%, the carbonate mineral content (magnesite, dolomite, etc.) is 6%, and the remaining main components are natural minerals such as silicates, mainly serpentine, with a content of 5%.

[0038] 4. The phosphate in the inorganic cement component is prepared by mixing ammonium dihydrogen phosphate and aluminum dihydrogen phosphate in a mass ratio of 8:2; the retarder is borax.

[0039] 5. The toughening material in the functional regulating component is a styrene-acrylic emulsion, and the solid content of the emulsion is 40%.

[0040] 6. The interface modifier in the functional regulating component is γ-aminopropyltriethoxysilane.

[0041] 7. The lightweight thermal insulation filler in the functional regulating component includes expandable graphite with an expansion ratio of 200 times and an expansion temperature of 200℃.

[0042] 8. The auxiliary flame retardant in the functional regulating component is zinc molybdate.

[0043] 9. The additives in the functional regulating component are sodium carboxymethyl cellulose and silicone amide, wherein the amount of sodium carboxymethyl cellulose is 0.3% of the total mass of the inorganic cement component, and the amount of silicone amide is 0.1% of the total mass of the inorganic cement component.

[0044] 10. The preparation method of the composite magnesium cement fireproof and corrosion-resistant integrated coating, wherein the coating is a two-component system, including a powder component (component A) and a liquid component (component B); the preparation method includes the following steps:

[0045] ①Preparation of powder components:

[0046] Magnesium materials, lightweight heat-insulating fillers, auxiliary flame retardants and additives are added to a mixer in sequence according to the formula ratio and dry-mixed at 500 rpm for 8 minutes to obtain a uniform base material; then ammonium polyphosphate, pentaerythritol and melamine are added and mixed for another 3 minutes to make the foaming components uniformly dispersed in the inorganic powder to obtain powder component A.

[0047] ②Preparation of liquid components:

[0048] Phosphate and retarder were added to 70 wt% of the total water volume and stirred for 3 min until fully dissolved to obtain a phosphate solution. The interface modifier was diluted with ethanol and the remaining 30 wt% water at an ethanol to water mass ratio of 1:5, stirred and hydrolyzed for 10 min, and then mixed with the toughening material and stirred for 10 min to form a pre-modified emulsion. The pre-modified emulsion was mixed evenly with the phosphate solution to obtain liquid component B.

[0049] ③ Spray coating application:

[0050] Powder component A and liquid component B are placed in the powder hopper and liquid hopper of the two-component high-pressure airless spraying equipment, respectively. They are mixed in real time at the spray gun end through independent pipelines and then atomized and sprayed by a high-pressure pump. The construction adopts layered spraying, with the thickness of each layer controlled at 1-2mm, until the total coating thickness is reached.

[0051] Example 2

[0052] A composite magnesium cement fireproof and corrosion-resistant integrated coating, the formulation and preparation steps are as follows:

[0053] 1. The composite magnesium cement fireproof and anticorrosive integrated coating includes an inorganic cement component, a foaming component, and a functional regulating component; the inorganic cement component is composed of the following components by mass percentage: (1) 58% magnesium material, (2) 38% phosphate, (3) 4% retarder; and the sum of the mass percentages of each component is 100%; based on the total mass of the inorganic cement component, the following components are added in addition: the foaming component includes: (1) 4% ammonium polyphosphate, (2) 2% pentaerythritol, (3) 2% melamine; the functional regulating component includes: (1) 6% toughening material, (2) 0.8% interface modifier, (3) 2.5% lightweight heat insulation filler, (4) 3% auxiliary flame retardant, (5) 0.7% additive.

[0054] 2. The amount of water added during the preparation and application of the coating is 35% of the total mass of the inorganic cement components.

[0055] 3. The magnesium material in the inorganic cement component is brucite powder with a particle size range of 100-200μm. The Mg(OH)2 content in the brucite is 86%, the carbonate mineral content (magnesite, dolomite, etc.) is 7%, and the remaining main components are natural minerals such as silicates, mainly serpentine, with a content of 6%.

[0056] 4. The phosphate in the inorganic cement component is prepared by mixing ammonium dihydrogen phosphate and aluminum dihydrogen phosphate in a mass ratio of 8:2; the retarder is borax.

[0057] 5. The toughening material in the functional regulating component is an aqueous epoxy emulsion, and the solid content of the emulsion is 45%.

[0058] 6. The interface modifier in the functional regulating component is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0059] 7. The lightweight thermal insulation filler in the functional regulating component is hollow glass microspheres with a true density of 0.3 g / cm³. 3 It has a thermal conductivity of 0.03 W / (m·k) and a compressive strength of 40 MPa.

[0060] 8. The auxiliary flame retardant in the functional regulating component is boron nitride nanosheets.

[0061] 9. The additives in the functional regulating component are sodium bicarbonate and ammonium carbamate, wherein the amount of sodium bicarbonate is 0.4% of the total mass of the inorganic cement component, and the amount of ammonium carbamate is 0.3% of the total mass of the inorganic cement component.

[0062] 10. The preparation method of the composite magnesium cement fireproof and corrosion-resistant integrated coating, wherein the coating is a two-component system, including a powder component (component A) and a liquid component (component B); the preparation method includes the following steps:

[0063] ①Preparation of powder components:

[0064] Magnesium materials, lightweight heat-insulating fillers, auxiliary flame retardants and additives are added to a mixer in sequence according to the formula ratio and dry-mixed at 300 rpm for 10 min to obtain a uniform base material; then ammonium polyphosphate, pentaerythritol and melamine are added and mixed for another 5 min to make the foaming components uniformly dispersed in the inorganic powder to obtain powder component A.

[0065] ②Preparation of liquid components:

[0066] Phosphate and retarder were added to 70 wt% of the total water volume and stirred for 5 min until fully dissolved to obtain a phosphate solution. The interface modifier was diluted with ethanol and the remaining 30 wt% water at an ethanol to water mass ratio of 1:10, and stirred for 10 min to hydrolyze it. Then, it was mixed with the toughening material and stirred for 10 min to form a pre-modified emulsion. The pre-modified emulsion was mixed evenly with the phosphate solution to obtain liquid component B.

[0067] ③ Spray coating application:

[0068] Powder component A and liquid component B are placed in the powder hopper and liquid hopper of the two-component high-pressure airless spraying equipment, respectively. They are mixed in real time at the spray gun end through independent pipelines and then atomized and sprayed by a high-pressure pump. The construction adopts layered spraying, with the thickness of each layer controlled at 1-2mm, until the total coating thickness is reached.

[0069] Example 3

[0070] A composite magnesium cement fireproof and corrosion-resistant integrated coating, the formulation and preparation steps are as follows:

[0071] 1. The composite magnesium cement fireproof and anticorrosive integrated coating includes an inorganic cement component, a foaming component, and a functional regulating component; the inorganic cement component is composed of the following components by mass percentage: (1) 60% magnesium material, (2) 38% phosphate, (3) 2% retarder; and the sum of the mass percentages of each component is 100%; based on the total mass of the inorganic cement component, the following components are added in addition: the foaming component includes: (1) 2% ammonium polyphosphate, (2) 1% pentaerythritol, (3) 1% melamine; the functional regulating component includes: (1) 4% toughening material, (2) 1.2% interface modifier, (3) 4% lightweight heat insulation filler, (4) 1.5% auxiliary flame retardant, (5) 0.3% additives.

[0072] 2. The amount of water added during the preparation and application of the coating is 25% of the total mass of the inorganic cement components.

[0073] 3. The magnesium material in the inorganic cement component is brucite powder with a particle size range of 100-200μm. The Mg(OH)2 content in the brucite is 85%, the carbonate mineral content (magnesite, dolomite, etc.) is 5%, and the remaining main components are natural minerals such as silicates, mainly serpentine, with a content of 5%.

[0074] 4. The phosphate in the inorganic cement component is prepared by mixing ammonium dihydrogen phosphate and aluminum dihydrogen phosphate in a mass ratio of 8:2; the retarder is borax.

[0075] 5. The toughening material in the functional regulating component is a polyurethane acrylate emulsion, and the solid content of the emulsion is 40%.

[0076] 6. The interface modifier in the functional regulating component is γ-(methacryloyloxy)propyltrimethoxysilane.

[0077] 7. The lightweight thermal insulation filler in the functional regulating component is expandable graphite and mullite fiber, wherein the amount of expandable graphite is 2% of the total mass of the inorganic cement component, the expansion ratio is 300 times, and the expansion temperature is 300℃; the amount of mullite fiber is 2% of the total mass of the inorganic cement component.

[0078] 8. The auxiliary flame retardant in the functional regulating component is boron nitride nanosheets.

[0079] 9. The additives in the functional regulating component are sodium carboxymethyl cellulose and silicone amide, wherein the amount of sodium carboxymethyl cellulose is 0.2% of the total mass of the inorganic cement component, and the amount of silicone amide is 0.1% of the total mass of the inorganic cement component.

[0080] 10. The preparation method of the composite magnesium cement fireproof and corrosion-resistant integrated coating, wherein the coating is a two-component system, including a powder component (component A) and a liquid component (component B); the preparation method includes the following steps:

[0081] ①Preparation of powder components:

[0082] Magnesium materials, lightweight heat-insulating fillers, auxiliary flame retardants and additives are added to a mixer in sequence according to the formula ratio and dry-mixed at 300 rpm for 10 min to obtain a uniform base material; then ammonium polyphosphate, pentaerythritol and melamine are added and mixed for another 5 min to make the foaming components uniformly dispersed in the inorganic powder to obtain powder component A.

[0083] ②Preparation of liquid components:

[0084] Phosphate and retarder were added to 70 wt% of the total water volume and stirred for 5 min until fully dissolved to obtain a phosphate solution. The interface modifier was diluted with ethanol and the remaining 30 wt% water at an ethanol to water mass ratio of 1:8, stirred and hydrolyzed for 10 min, and then mixed with the toughening material and stirred for 10 min to form a pre-modified emulsion. The pre-modified emulsion was mixed evenly with the phosphate solution to obtain liquid component B.

[0085] ③ Spray coating application:

[0086] Powder component A and liquid component B are placed in the powder hopper and liquid hopper of the two-component high-pressure airless spraying equipment, respectively. They are mixed in real time at the spray gun end through independent pipelines and then atomized and sprayed by a high-pressure pump. The construction adopts layer spraying, with the thickness of each layer controlled at 1±0.2mm, until the total coating thickness is reached.

[0087] Example 4

[0088] Similar to Example 1, except that: the toughening materials in the functional regulating component are styrene-acrylic emulsion and waterborne epoxy emulsion, wherein the styrene-acrylic emulsion content is 2.5% of the total mass of the inorganic cement component, and the solid content is 45%. The waterborne epoxy emulsion content is 2.5% of the total mass of the inorganic cement component, and the solid content is 45%. The interface modifier in the functional regulating component is γ-aminopropyltriethoxysilane; the auxiliary flame retardant in the functional regulating component is zinc molybdate and graphene oxide, wherein the zinc molybdate content is 1% of the total mass of the inorganic cement component; and the graphene oxide content is 1% of the total mass of the inorganic cement component. The additives in the functional regulating component are sodium carboxymethyl cellulose and silicone amide, wherein the sodium carboxymethyl cellulose content is 0.2% of the total mass of the inorganic cement component; and the silicone amide content is 0.2% of the total mass of the inorganic cement component.

[0089] Example 5

[0090] Similar to Example 1, except that: the toughening material in the functional regulating component is an aqueous epoxy emulsion with a solid content of 50%; the interface modifier in the functional regulating component is γ-(2,3-epoxypropoxy)propyltrimethoxysilane; the lightweight thermal insulation filler in the functional regulating component is silica aerogel; and the additives in the functional regulating component are sodium carboxymethyl cellulose and sodium bicarbonate, wherein the sodium carboxymethyl cellulose content is 0.3% of the total mass of the inorganic cement component; and the sodium bicarbonate content is 0.1% of the total mass of the inorganic cement component.

[0091] Example 6

[0092] Similar to Example 1, except that: the toughening material in the functional regulating component is polyethersulfone emulsion with a solid content of 50%; the lightweight thermal insulation filler in the functional regulating component is a mixture of silica aerogel and aluminosilicate fiber, wherein the silica aerogel content is 1.5% of the total mass of the inorganic cement component, and the aluminosilicate fiber content is 1.5% of the total mass of the inorganic cement component; the auxiliary flame retardant in the functional regulating component is graphene oxide; the additives in the functional regulating component are sodium carboxymethyl cellulose and ammonium carbamate, wherein the sodium carboxymethyl cellulose content is 0.2% of the total mass of the inorganic cement component, and the ammonium carbamate content is 0.2% of the total mass of the inorganic cement component.

[0093] Comparative Example 1

[0094] This comparative example uses a non-expanding ordinary silicate cement-based fireproof coating for steel structures, which is mainly composed of ordinary silicate cement, fillers (expanded vermiculite, vitrified microspheres), polymer latex (powder) and additives (defoamer, anti-settling agent), with a coating thickness of 15mm.

[0095] Comparative Example 2

[0096] This comparative example uses a non-expanding gypsum-based fireproof coating for steel structures, which mainly consists of gypsum, expanded perlite, aluminum silicate fiber cotton, and polymer latex adhesive, with a coating thickness of 15mm.

[0097] Comparative Example 3

[0098] This comparative example uses a common intumescent organic fire-retardant coating, which consists of ammonium polyphosphate (15%), pentaerythritol (8%), and melamine (7%), with an acrylic emulsion as the film substrate and a coating thickness of 5 mm.

[0099] Comparative Example 4

[0100] In this comparative example, a complete anti-corrosion coating system (including epoxy zinc-rich primer, intermediate paint and topcoat, with a total dry film thickness of 80 μm) was first constructed on a steel substrate, and then the non-expansive ordinary silicate cement-based fire retardant coating described in Comparative Example 1 was coated on its surface, with a fire retardant coating thickness of 15 mm.

[0101] Comparative Example 5

[0102] In this comparative example, a complete anti-corrosion coating system (including epoxy zinc-rich primer, intermediate paint and topcoat, with a total dry film thickness of 80 μm) was first constructed on a steel substrate, and then the non-intumescent gypsum-based fire retardant coating described in Comparative Example 2 was coated on its surface, with a fire retardant coating thickness of 15 mm.

[0103] Comparative Example 6

[0104] In this comparative example, a complete anti-corrosion coating system (including epoxy zinc-rich primer, intermediate paint and topcoat, with a total dry film thickness of 80 μm) was first constructed on a steel substrate, and then the intumescent organic fire retardant coating described in Comparative Example 3 was applied to its surface, with a fire retardant coating thickness of 5 mm.

[0105] Comprehensive analysis of the performance data from the embodiments and comparative examples shows that the composite magnesium-based fireproof and corrosion-resistant integrated coating developed in this invention is significantly superior to intumescent and non-intumescent fireproof coatings in many key performance indicators. Under a uniform coating thickness of 5 mm, the compressive strength of this coating is 2.3-2.8 times that of the comparative example, the bonding strength is increased by more than 25%, with a maximum enhancement of 50%; its surface drying time is less than 1 hour, far lower than the control group, and its dry density is stably controlled at 590–640 kg / m³. 3 Within its range, it demonstrates excellent lightweight characteristics and construction adaptability.

[0106] As shown in Table 2, the product of this invention possesses both excellent fire resistance and corrosion resistance. Its fire resistance limit is increased by 60% to 100% compared to the comparative examples, and the coating remains intact and rust-free in all environmental corrosion tests, while the comparative examples all exhibited significant powdering, peeling, or substrate corrosion. The test results demonstrate that this invention effectively solves the technical bottlenecks of traditional coatings, such as the inability to simultaneously achieve fire resistance and corrosion resistance, and the ease with which the coating deteriorates, achieving efficient and long-lasting protection even under ultra-thin coating conditions.

[0107] Table 1

[0108]

[0109]

[0110] Table 2

[0111]

[0112] Note: The testing methods for freeze-thaw cycle resistance test, acid resistance test, alkali resistance test, salt spray corrosion resistance test, and wet-dry cycle resistance test all comply with relevant national standards.

[0113] The experimental results clearly show that, within the scope of the patent claims, this invention successfully constructs a stable and efficient inorganic-organic composite coating system by combining magnesium cement with foaming components and synergistically incorporating toughening materials, interface modifiers, auxiliary flame retardants, and lightweight insulating fillers. This system exhibits a synergistic flame-retardant effect under fire conditions. On one hand, the magnesium cement matrix forms a stable insulating layer; on the other hand, the organic components expand and foam to form a dense carbon layer. This dual barrier effectively blocks heat transfer to the substrate, significantly slowing down the heating rate of the steel structure. Even under thin-coat conditions, the coating still exhibits excellent fire and corrosion resistance, with its fire resistance limit significantly exceeding that of traditional intumescent fire-retardant coatings. It fully meets the performance requirements of "Fire-retardant Coatings for Steel Structures" (GB14907), improving the fire safety of steel structures while also possessing good workability and economy, demonstrating significant engineering application value and market potential.

[0114] Finally, the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A composite magnesium cement fireproof and corrosion-resistant integrated coating, characterized in that, The composite magnesium cement fireproof and anticorrosive coating includes an inorganic cement component, a foaming component, and a functional regulating component. The inorganic cement component consists of the following components by mass percentage: (1) 50%-60% magnesium material, (2) 25%-40% phosphate, (3) 0-5% retarder; and the sum of the mass percentages of each component is 100%. Based on the total mass of the inorganic cement component, the following components are added: The foaming component includes: (1) 1%-5% ammonium polyphosphate, (2) 0.5%-3% pentaerythritol, (3) 0.5-3% melamine; The functional regulating component includes: (1) 2%-8% toughening material, (2) 0.5%-1.5% interface modifier, (3) 1.5%-5% lightweight heat insulation filler, (4) 1-5% auxiliary flame retardant, and (5) 0.1-2% additives.

2. The composite magnesium cement fireproof and corrosion-resistant integrated coating according to claim 1, characterized in that, The amount of water added to the coating during preparation and application is 20%-40% of the total mass of the inorganic cement components.

3. The composite magnesium cement fireproof and corrosion-resistant integrated coating according to claim 1, characterized in that, The magnesium material in the inorganic cement component is brucite powder with a particle size range of 100-200μm. The Mg(OH)2 content in the brucite is not less than 80%, the carbonate mineral content (such as magnesite, dolomite, etc.) is not more than 8%, and the remaining main components are natural minerals such as silicates, mainly serpentine, with a content of 2-10%.

4. The composite magnesium cement fireproof and corrosion-resistant integrated coating according to claim 1, characterized in that, The phosphate in the inorganic cement component is prepared by mixing ammonium dihydrogen phosphate and aluminum dihydrogen phosphate in a mass ratio of 8:2; the retarder is borax.

5. The composite magnesium cement fireproof and corrosion-resistant integrated coating according to claim 1, characterized in that, The toughening material in the functional regulating component includes one or more of polyurethane acrylate emulsion, polyethersulfone emulsion, styrene-acrylic emulsion, and waterborne epoxy emulsion, and the solid content of the emulsion is 40%-55%.

6. The composite magnesium cement fireproof and corrosion-resistant integrated coating according to claim 1, characterized in that, The interface modifier in the functional regulating component includes one or more of γ-aminopropyltriethoxysilane, γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-(methacryloyloxy)propyltrimethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.

7. The composite magnesium cement fireproof and corrosion-resistant integrated coating according to claim 1, characterized in that, The lightweight thermal insulation filler in the functional regulating component includes one or more of expandable graphite, hollow glass microspheres, mullite fiber, aluminosilicate fiber, silica aerogel, or expanded clay; the expandable graphite has an expansion ratio of 200-400 times and an expansion temperature of 200-300℃; the hollow glass microspheres have a true density of 0.2-0.4 g / cm³. 3 It has a thermal conductivity of 0.03-0.05 W / (m·k) and a compressive strength greater than 30 MPa.

8. The composite magnesium cement fireproof and corrosion-resistant integrated coating according to claim 1, characterized in that, The auxiliary flame retardants in the functional regulating components include one or more of zinc molybdate, boron nitride nanosheets, graphene oxide, or zinc ferrite.

9. The composite magnesium cement fireproof and corrosion-resistant integrated coating according to claim 1, characterized in that, The functional regulating components include one or more of sodium bicarbonate, sodium carboxymethyl cellulose, silicone amide, or ammonium carbamate.

10. A method for preparing a composite magnesium cement fireproof and corrosion-resistant integrated coating as described in claim 1, characterized in that, The coating is a two-component system, comprising a powder component (component A) and a liquid component (component B); its preparation method includes the following steps: ①Preparation of powder components: Magnesium materials, lightweight heat-insulating fillers, auxiliary flame retardants and additives are added to a mixer in sequence according to the formula ratio and dry-mixed at 300-500 rpm for 8-10 minutes to obtain a uniform base material; then ammonium polyphosphate, pentaerythritol and melamine are added and mixed for another 3-5 minutes to make the foaming components uniformly dispersed in the inorganic powder to obtain powder component A. ②Preparation of liquid components: Add phosphate and retarder to 70 wt% of the total water volume and stir for 3-5 min until fully dissolved to obtain a phosphate solution; dilute the interface modifier with ethanol and the remaining 30 wt% water at an ethanol to water mass ratio of 1:(5-10), stir and hydrolyze for 10 min, then mix with the toughening material and stir for 10-20 min to form a pre-modified emulsion; mix the pre-modified emulsion with the phosphate solution evenly to obtain liquid component B; ③ Spray coating application: Powder component A and liquid component B are placed in the powder hopper and liquid hopper of the two-component high-pressure airless spraying equipment, respectively. They are mixed in real time at the spray gun end through independent pipelines and then atomized and sprayed by a high-pressure pump. The construction adopts layered spraying, with the thickness of each layer controlled at 1-2mm, until the total coating thickness is reached.

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