Single-component inorganic cold-coating high-temperature-resistant self-cleaning coating containing nanowhiskers as well as preparation method and application thereof

Abstract

The invention discloses a single-component inorganic cold-coating high-temperature-resistant self-cleaning coating containing nanowhiskers as well as a preparation method and application of the single-component inorganic cold-coating high-temperature-resistant self-cleaning coating. The single-component inorganic cold-coating high-temperature-resistant self-cleaning coating is prepared from the following raw materials in percentage by weight: 18 to 22 percent of SiC / Al2O3 composite whisker, 8 to 12 percent of nano TiO2, 35 to 38 percent of silica sol, 12 to 15 percent of nano ZrO2, 5 to 8 percent of apatite antibacterial agent, 2 to 3 percent of lithium-based bentonite, 1.5 to 2 percent of silane coupling agent and the balance of water. The coating disclosed by the invention solves the problems of no high temperature resistance, VOC (Volatile Organic Compounds) pollution and poor weather resistance; the limitation of high-temperature curing is broken through, and 0 DEG C cold coating is realized; meanwhile, the coating disclosed by the invention integrates 1500 DEG C high temperature resistance and cold coating characteristics, and a single-component system is more convenient for construction.

Description

Technical Field

[0001] This invention belongs to the field of architectural coatings technology, specifically relating to a single-component inorganic cold-applied high-temperature resistant self-cleaning coating containing nano-whiskers, its preparation method and application, which is particularly suitable for scenarios with stringent requirements for fire resistance, environmental protection, weather resistance and construction conditions. Background Technology

[0002] In the current coatings market, organic coatings contain organic solvents (VOCs), which have problems such as poor environmental performance, poor high temperature resistance (usually resistant to temperatures below 200℃), and easy aging. They are also prone to releasing harmful substances in densely populated areas or enclosed environments, failing to meet high environmental protection and fire prevention requirements. Traditional inorganic coatings, although possessing certain high temperature resistance, mostly require high-temperature curing (usually above 80℃), making application highly temperature-dependent. Furthermore, they have limited functionality (such as only possessing fire resistance, lacking comprehensive properties such as antibacterial and self-cleaning properties), making it difficult to meet the needs of complex scenarios (such as low-temperature environment construction, mildew prevention in humid environments, and long-term stain resistance in tunnels / bridges).

[0003] To address the aforementioned issues, there is an urgent need to develop a single-component inorganic coating that does not require high-temperature curing, and possesses high-temperature resistance, self-cleaning properties, antibacterial and antifungal properties, as well as wide applicability, in order to solve the pain points of existing technologies such as demanding construction conditions, limited functionality, and insufficient environmental friendliness. Summary of the Invention

[0004] The main objective of this invention is to provide a single-component inorganic cold-applied high-temperature resistant self-cleaning coating containing nano-whiskers, its preparation method, and its application, so as to overcome the shortcomings of the prior art.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: This invention provides a single-component inorganic cold-applied high-temperature resistant self-cleaning coating containing nano-whiskers. The raw materials for preparing the single-component inorganic cold-applied high-temperature resistant self-cleaning coating include the following components by weight percentage: 18~22% SiC / Al2O3 composite whiskers, 8~12% nano TiO2, 35~38% silica sol, 12~15% nano ZrO2, 5~8% apatite antibacterial agent, 2~3% lithium-based bentonite, 1.5~2% silane coupling agent, and the remainder is water.

[0006] This invention also provides a method for preparing the aforementioned single-component inorganic cold-applied high-temperature self-cleaning coating containing nanofibers, comprising: SiC / Al2O3 composite whiskers were activated using argon plasma to obtain activated whiskers; Activated whiskers and nano-TiO2 were blended and ball-milled to obtain TiO2-coated whisker composites; Furthermore, a single-component inorganic cold-applied high-temperature self-cleaning coating was prepared by pre-dispersing silica sol with water, followed by adding TiO2-coated whisker composites and subjecting them to high-speed shearing, then sequentially adding nano-ZrO2 and apatite antibacterial agent and ultrasonic treatment, and finally adding additives for curing.

[0007] This invention also provides a method for preparing a high-temperature resistant, self-cleaning, antibacterial, and mildew-resistant coating, comprising: A single-component inorganic cold-applied high-temperature resistant self-cleaning coating containing nanocrystals was prepared using the aforementioned preparation method. Furthermore, the single-component inorganic cold-applied high-temperature self-cleaning coating is applied to the surface of a substrate in an environment above 0°C and cured to obtain a high-temperature self-cleaning antibacterial and mildew-resistant coating.

[0008] The present invention also provides a high-temperature resistant, self-cleaning, antibacterial, and mildew-resistant coating prepared by the aforementioned preparation method.

[0009] This invention also provides the application of the aforementioned single-component inorganic cold-applied high-temperature self-cleaning coating or high-temperature self-cleaning antibacterial and mildew-resistant coating containing nanocrystals in low-temperature environment construction, mildew prevention in humid environments, and long-term stain resistance in tunnels / bridges.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The coating in this invention solves the problems of poor heat resistance, VOC pollution, and poor weather resistance; (2) Compared with traditional inorganic coatings, the coating in this invention breaks through the limitation of "high temperature curing" and achieves cold application at 0°C, and has more comprehensive functions (antibacterial, self-cleaning). (3) Compared with similar nano-coatings, the coating in this invention integrates high temperature resistance of 1500℃ and cold coating characteristics, and the single-component system is easier to apply. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figures 1a-1b This is a stain resistance effect diagram of the coating and epoxy coating applied to the tunnel glazed ceramic tile 24 hours after embodiment 1 of the present invention. Figure 2 This is a high-temperature firing diagram of the coating applied to the ceramic tile glaze and cured for 24 hours, as shown in Embodiment 1 of the present invention. Figures 3a-3bThis is a diagram showing the heat insulation and cooling properties of the coating in Example 1 of the present invention; Figures 4a-4c This is an ablation resistance diagram of the coating applied to the surface of the tinplate and cured in Embodiment 1 of the present invention. Figures 5a-5b This is a diagram showing the effect of the coating being applied and cured at 0°C in Example 1 of the present invention. Detailed Implementation

[0013] In view of the deficiencies of the prior art, the inventors of this case, through long-term research and extensive practice, have proposed the technical solution of this invention. The technical solution of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0014] Specifically, as one aspect of the technical solution of this invention, it relates to a single-component inorganic cold-applied high-temperature resistant self-cleaning coating containing nano-whiskers. The raw materials for preparing the single-component inorganic cold-applied high-temperature resistant self-cleaning coating include the following components calculated by weight percentage: 18~22% SiC / Al2O3 composite whiskers, 8~12% nano TiO2, 35~38% silica sol, 12~15% nano ZrO2, 5~8% apatite antibacterial agent, 2~3% lithium-based bentonite, 1.5~2% silane coupling agent, and the remainder includes water.

[0015] In some preferred embodiments, the SiC / Al2O3 composite whiskers have a diameter of 50-100 nm and an aspect ratio > 50. The SiC / Al2O3 composite whiskers are used as a three-dimensional network framework, with a thermal conductivity of 0.035 W / m•K, effectively blocking heat flow. In some preferred embodiments, the particle size of the nano-TiO2 is ≤20nm. The nano-TiO2 is chemically bonded to the surface of the whiskers, forming a core-shell structure: photocatalytic decomposition of organic matter + superhydrophilic (contact angle 10°).

[0016] In some preferred embodiments, the Na⁺ content in the silica sol is <0.1wt%, and the particle size of SiO₂ is 10~15nm. The silica sol can be dehydrated and crosslinked at low temperature: ≡Si-OH + HO-Si≡ → ​​≡Si-O-Si≡ + H₂O (the reaction rate increases by 3 times at 0℃).

[0017] In some preferred embodiments, the particle size of the nano ZrO2 is 20~100nm, preferably 30~80nm, and particularly preferably 50nm.

[0018] In some preferred embodiments, the nano-ZrO2 has a Mohs hardness of 8.5 and is used to fill pores and improve density.

[0019] In some preferred embodiments, the nano-ZrO2 is a monoclinic phase.

[0020] In some preferred embodiments, the SiC / Al2O3 composite whiskers have a core-shell structure.

[0021] In some preferred embodiments, the SiC / Al2O3 composite whiskers include SiC / γ-Al2O3 composite whiskers.

[0022] In some preferred embodiments, the method for preparing the SiC / Al2O3 composite whiskers includes: Activated SiC whiskers were obtained by surface pretreatment and plasma activation of SiC whiskers. An amorphous alumina hydrate shell was grown in situ on the surface of activated SiC whiskers using the sol-gel method, followed by separation, drying / gradient crystallization heat treatment to obtain SiC / Al2O3 composite whiskers.

[0023] In some preferred embodiments, the chemical formula of the apatite antibacterial agent is Ca. 10 (PO4)6(OH)2, wherein Ca / P = 1.67. The apatite antibacterial agent can slowly release Ca²⁺ to disrupt microbial cell membranes, with an antibacterial rate >99.9%.

[0024] In some preferred embodiments, the lithium-based bentonite has a thixotropic index > 4.5. The lithium-based bentonite can prevent settlement and is suitable for facade construction.

[0025] In some preferred embodiments, the silane coupling agent comprises a silane coupling agent containing an epoxy group, an amino group, or a (meth)acryloyloxy group, which can enhance chemical bonding with the substrate and achieve concrete adhesion >1.8 MPa.

[0026] Furthermore, the silane coupling agent includes, but is not limited to, γ-glycidoxypropyltrimethoxysilane (KH-560).

[0027] Another aspect of this invention provides a method for preparing the aforementioned single-component inorganic cold-applied high-temperature self-cleaning coating containing nanofibers, comprising: SiC / Al2O3 composite whiskers were activated using argon plasma to obtain activated whiskers; Activated whiskers and nano-TiO2 were blended and ball-milled to obtain TiO2-coated whisker composites; Furthermore, silica sol is mixed with water for pre-dispersion, then TiO2-coated whisker composite is added and subjected to high-speed shearing, followed by the sequential addition of nano-ZrO2 and apatite antibacterial agent and ultrasonic treatment, and finally the addition of additives for curing treatment, to obtain a single-component inorganic cold-applied high-temperature resistant self-cleaning coating.

[0028] In some preferred embodiments, the activation treatment uses a power of 300W and a time of 10 minutes.

[0029] In some preferred embodiments, the process parameters for the blending ball milling treatment include: Φ3mm zirconia balls, a ball-to-material ratio of (4-6):1, a rotation speed of 300~500 rpm, and a time of 1.5~3 h. Specifically, a ball-to-material ratio <4:1 results in insufficient grinding energy and uneven TiO2 coating; a ratio >6:1 offers limited efficiency improvement and increases energy consumption. Rotation speed and time jointly determine the total input mechanical energy. Too low / too short a time leads to insufficient composite; too high / too long a time may damage the whisker aspect ratio or cause excessive heat generation.

[0030] In some preferred embodiments, the pre-dispersion is performed at a rotation speed of 800-1200 rpm for 5-15 minutes. The purpose is to initially wet and mix the particles. This range is sufficient to break up large aggregates, preparing them for subsequent high-speed shearing. Excessive time is not beneficial and represents a waste of production capacity.

[0031] In some preferred embodiments, the high-speed shearing is performed at a rotation speed of 2500–3500 rpm for 20–40 min. High-speed shearing is the core dispersion step; this range provides sufficient shear force (matched to viscosity) to break up soft agglomerates of nanoparticles and achieve the desired fineness (e.g., D90 < 100 nm). Insufficient time results in uneven dispersion; excessive time may introduce too many air bubbles or cause a temperature rise.

[0032] In some preferred embodiments, the ultrasonic treatment uses a power of 35-45 kHz for a duration of 15-30 min. This utilizes the cavitation effect to further disperse and promote component fusion.

[0033] In some preferred embodiments, the curing time is 12-48 hours. This allows the additives to migrate and adsorb sufficiently, and the system to reach chemical and physical equilibrium. A curing time shorter than 12 hours may result in unstable rheological properties; a curing time exceeding 48 hours does not further improve performance.

[0034] In some preferred embodiments, the additives include any one or more combinations of dispersants, rheology modifiers, defoamers, wetting agents, pH adjusters, and antifreeze agents, and are not limited thereto.

[0035] Preferably, the dispersant prevents the agglomeration of nanoparticles (ZrO2, TiO2, etc.) and ensures the uniformity and stability of the system; it can be ammonium polyacrylate (such as Tego Dispers 755 W) or sodium polycarboxylate (such as Orotan 731A); the amount used accounts for 0.3~1.0 wt% of the total coating, and it is adsorbed on the surface of nanoparticles, preventing them from agglomerating by electrostatic repulsion and steric hindrance.

[0036] Preferably, rheology modifiers (thixotropic agents) provide shear-thinning properties: high viscosity during storage to prevent sedimentation, low viscosity for easy leveling during application, and resistance to sagging on vertical surfaces; these can be lithium-based montmorillonite (such as Bentone LT), hydrophobically modified fumed silica (such as Aerosil R972), or cellulose ethers (such as hydroxyethyl cellulose HEC); the dosage is 0.5~2.5 wt% of the total coating, forming a three-dimensional network structure that locks in moisture and particles when stationary; the structure is disrupted by shearing (stirring, brushing), resulting in a decrease in viscosity.

[0037] As a preferred option, the defoamer eliminates air bubbles during production and application, preventing defects such as pinholes and fisheyes in the coating. It can be a mineral oil-based defoamer (such as BYK-019), an organosilicon defoamer (such as Tego Foamex 810), or a polyether-modified siloxane (such as BYK-024). The amount used accounts for 0.1 to 0.5 wt% of the total coating. It reduces the local surface tension of the system, causing the bubble film to rupture, merge, and escape.

[0038] Preferably, the wetting agent reduces the surface tension of the coating and improves its spreading and penetration into the substrate (especially old ceramic tiles and dusty concrete); it can be a nonionic surfactant (such as Tego Wet 270) or an organosilicon wetting agent (such as BYK-346); the amount used accounts for 0.1~0.3wt% of the total coating, which increases the affinity between the coating and the substrate and improves adhesion.

[0039] Preferably, a pH adjuster / stabilizer maintains the pH of the silica sol system within a stable range (typically 8.5-10.5) to prevent gelation; it can be an organic amine (such as AMP-95, 2-amino-2-methyl-1-propanol) or potassium hydroxide solution; the amount used accounts for 0.05~0.03 wt% of the total coating, which provides an alkaline environment, stabilizes the negative charge on the surface of the silica sol particles, and prevents excessively rapid condensation.

[0040] Preferably, the antifreeze agent prevents the coating from freezing and demulsifying when stored below 0°C; it can be propylene glycol or ethylene glycol (note: considering environmental friendliness, propylene glycol is preferred); the amount used accounts for 1.0~3.0 wt% of the total coating, which lowers the freezing point of the system.

[0041] Preferably, the additives (based on the total mass of the coating) include: ammonium polyacrylate dispersant: 0.6%, lithium-based montmorillonite rheology modifier: 1.2%, silicone defoamer: 0.3%, nonionic wetting agent: 0.2%, AMP-95 pH adjuster: 0.1%, propylene glycol: 2.0%, and γ-glycidyl etheroxypropyltrimethoxysilane (KH-560): 1.8%.

[0042] In some preferred embodiments, the additive accounts for 0.5 to 5 wt% of the single-component inorganic cold-applied high-temperature self-cleaning coating containing nanofibers.

[0043] In some preferred embodiments, the surface -OH density of the activated whiskers is 8.2 ions / nm. 2 .

[0044] In some preferred embodiments, the viscosity of the single-component inorganic cold-applied high-temperature self-cleaning coating is 3500±200mPa·s (25℃), and the particle size distribution D90<100nm.

[0045] In some more specific embodiments, the preparation method of the single-component inorganic cold-applied high-temperature self-cleaning coating containing nanocrystals includes: 1) Whisker surface modification: Argon plasma activation (300W, 10min) increased the surface -OH density to 8.2 ions / nm. 2 ; Activated whiskers and nano-TiO2 were blended and ball-milled: zirconia balls (Φ3mm), ball-to-material ratio 5:1, 450rpm×2h.

[0046] 2) Gradient mixing process: Silica sol + deionized water, pre-dispersed (1000 rpm / 10 min), TiO2-coated whisker composite added, high-speed shearing (3000 rpm / 30 min), ZrO2 and apatite antibacterial agent added, ultrasonic treatment (40 kHz / 20 min), additives added, and aging for 24 h.

[0047] Quality control points: viscosity 3500±200mPa·s (25℃), particle size distribution D90<100nm.

[0048] The single-component inorganic cold-applied high-temperature self-cleaning coating of this invention can be applied and cured in low-temperature environments above 0°C; it has a high-temperature resistance of 1500°C, meeting stringent fire protection requirements; it has heat insulation and cooling effects, reducing substrate deformation at high temperatures and improving durability; it integrates antibacterial, anti-mildew, and self-cleaning functions, making it suitable for humid, densely populated, and highly polluted environments; as a single-component inorganic system, it has no VOC release, meeting high environmental protection standards; it is suitable for a variety of substrates, broadening application scenarios.

[0049] The single-component inorganic cold-applied high-temperature self-cleaning coating of the present invention has the following advantages: (1) 0℃ cold-applied curing: nano-capillary effect accelerates dehydration and polycondensation; (2) 1500℃ thermal barrier protection: whisker aerogel blocks heat conduction + phase change heat absorption; (3) self-cleaning-antibacterial synergy: super-hydrophilic surface (contact angle 10°) + photocatalytic sterilization; (4) universality of substrates: direct coating on concrete / tile / metal, adhesion >1.8MPa.

[0050] Another aspect of the present invention provides a method for preparing a high-temperature resistant, self-cleaning, antibacterial, and mildew-resistant coating, comprising: A single-component inorganic cold-applied high-temperature resistant self-cleaning coating containing nanocrystals was prepared using the aforementioned preparation method. Furthermore, the single-component inorganic cold-applied high-temperature self-cleaning coating is applied to the surface of a substrate in an environment above 0°C and cured to obtain a high-temperature self-cleaning antibacterial and mildew-resistant coating.

[0051] Another aspect of the present invention provides a high-temperature resistant, self-cleaning, antibacterial, and mildew-resistant coating prepared by the aforementioned method.

[0052] Another aspect of the present invention provides the application of the aforementioned single-component inorganic cold-applied high-temperature self-cleaning coating or high-temperature self-cleaning antibacterial and mildew-resistant coating containing nanocrystals in low-temperature environment construction, mildew prevention in humid environments, and long-term stain resistance in tunnels / bridges.

[0053] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0054] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0055] SiC / Al2O3 composite whiskers, possessing a core-shell structure and high surface activity, serve as the framework material for coatings and are crucial for achieving breakthrough properties such as "low-temperature curing" and "ultra-high temperature resistance." This invention employs a three-step method—"plasma activation—sol-gel coating—gradient crystallization"—to ensure that Al2O3 is uniformly and firmly bonded to the surface of SiC whiskers at the nanoscale. The preparation of the SiC / Al2O3 composite whiskers includes: I. List of Raw Materials and Equipment 1. Main ingredients: Silicon carbide whiskers: purity ≥99.9%, diameter 50-100 nm, length 10-20 μm, aspect ratio >100.

[0056] Aluminum source: Aluminum isopropoxide, chemically pure.

[0057] Solvent: Anhydrous ethanol, analytical grade.

[0058] Catalyst: Deionized water (conductivity ≤ 0.1 μS / cm).

[0059] Dispersant: Polyethylene glycol-400.

[0060] 2. Key Equipment: Vacuum plasma processing system: radio frequency power source (13.56 MHz), equipped with Ar gas path and vacuum pump group.

[0061] Ultrasonic-mechanical stirring reactor: equipped with constant temperature water bath, condenser reflux and precision liquid addition device.

[0062] Programmable temperature controlled tube furnace: maximum temperature 1200℃, can be vented with air or inert gas.

[0063] Centrifuge, vacuum drying oven.

[0064] Characterization instruments: scanning electron microscope, transmission electron microscope, X-ray diffractometer, X-ray photoelectron spectrometer, specific surface area and porosity analyzer.

[0065] II. Detailed Explanation of the Step-by-Step Preparation Process Step 1: Surface pretreatment and plasma activation of SiC whiskers Objective: To clean the surface, remove the passivation layer, and significantly increase the density of surface-active silanol groups.

[0066] Operating procedures: 1. Acid washing to remove impurities: Immerse 100g of SiC whiskers in 1L of 5 wt% hydrofluoric acid solution and sonicate at 40℃ (300W power) for 60 minutes. Then wash repeatedly with deionized water by centrifugation until the pH of the supernatant is neutral (pH≈7).

[0067] 2. Vacuum plasma activation: ① Spread the acid-washed wet whiskers evenly on the sample stage of the plasma reaction chamber and pre-dry them under vacuum at 60°C for 30 minutes.

[0068] ② Close the reaction chamber and evacuate until the background pressure is below 5 Pa.

[0069] ③ Introduce high-purity argon gas (99.999% purity) into the room and stabilize the working pressure at 50 Pa.

[0070] ④ Turn on the RF power supply, set the power to 300 W, and the processing time to 12 minutes.

[0071] ⑤ After the treatment is completed, the sample is cooled to room temperature under the protection of continuous Ar gas and then taken out.

[0072] Key parameters and principles: ① Power and time: The parameter combination of 300W / 12min is optimized to achieve the best balance between etching the surface and introducing defects, maximizing the surface silanol density without over-etching and causing a decrease in whisker strength.

[0073] ② Atmosphere selection: Use inert Ar gas to avoid introducing reactive gases such as oxygen to generate unnecessary oxide layers.

[0074] ③ Effect: After this treatment, the surface of SiC whiskers changes from hydrophobic to superhydrophilic, and the specific surface area increases from approximately 5 m² / g. 2 The surface silanol density increased to ≥8 ions / nm, with the g / g increasing to 210-230 m² / g. 2 (Verified by XPS semi-quantitative and chemical titration methods).

[0075] Step 2: Preparation of γ-Al2O3 sol and liquid phase chemical deposition coating Objective: To grow a uniform and dense amorphous alumina hydrate shell on the surface of activated SiC in situ using the sol-gel method.

[0076] Operating procedures: ① Preparation of aluminum sol precursor: In a dry flask, dissolve 25g of aluminum isopropoxide in 500mL of anhydrous ethanol and stir until completely transparent; this is denoted as solution A. Separately, mix 2.7g of deionized water with 100mL of anhydrous ethanol; this is denoted as solution B.

[0077] ② Dispersion and Reaction: 20g of plasma-activated SiC whiskers were rapidly added to solution A, along with 1g of polyethylene glycol-400 as a dispersant. The mixture was placed in a 60℃ water bath, and solution B was slowly added dropwise at a rate of 1 mL / min under strong mechanical stirring at 500 rpm. After the addition was complete, the temperature was maintained at 60℃, and the reaction was continued with stirring for 5 hours, while intermittent sonication (2 seconds on, 2 seconds off) was applied to prevent agglomeration.

[0078] ③Aging and Bonding: After the reaction is complete, the system is sealed and left to stand at room temperature for 24 hours to complete the transformation of the sol into a gel and the full formation of interfacial chemical bonds.

[0079] Key parameters and principles: a. Al / Si molar ratio: Controlled between 0.8:1 and 1.2:1 to ensure the formation of a complete coating layer without generating excessive free Al(OH)3 particles.

[0080] b. Hydrolysis control: The slow addition of trace amounts of water is the key to achieving controllable hydrolysis and uniform nucleation, thus avoiding explosive aggregation.

[0081] c. Temperature and time: The reaction conditions of 60℃ and 5 hours ensured that aluminum isopropoxide was fully hydrolyzed and polycondensed, and chemically anchored at the SiC-OH sites.

[0082] d. Chemical mechanism: The core reaction is ≡Si-OH + HO-Al(OH)2→ → ≡Si-O-Al≡ + H2O, forming a covalent bond interface.

[0083] Step 3: Separation, drying and gradient crystallization heat treatment of the product Objective: To obtain composite whiskers with the target crystal form (γ-Al2O3) and ensure their structural stability.

[0084] Operating procedures: ① Separation and washing: The aged slurry was centrifuged at 8000 rpm for 10 minutes to separate the solid phase. The precipitate was ultrasonically washed three times with anhydrous ethanol to thoroughly remove unreacted organic matter and free particles.

[0085] ② Vacuum drying: The washed filter cake is dried in a vacuum drying oven at 80°C for 12 hours to obtain precursor powder.

[0086] ③ Gradient heat treatment: Place the dried powder in an alumina crucible and then place it in a tube furnace.

[0087] The mixture is heated to 400°C at a rate of 2°C / min in air and held at that temperature for 60 minutes to completely remove residual organic matter and water of crystallization.

[0088] Then, the temperature was increased to 800℃ at a rate of 5℃ / min and held for 120 minutes.

[0089] After the u-process is completed, the furnace is cooled to room temperature to obtain the final product—SiC / γ-Al2O3 composite whiskers.

[0090] Key parameters and principles: ① Gradient heating: The slow heating rate (2℃ / min) prevents the shell from cracking or powder from splashing due to the violent evaporation of moisture and organic matter.

[0091] ② Crystallization temperature: 800℃ is the typical temperature for the formation and stabilization of γ-Al2O3. At this temperature, amorphous alumina completes the transformation to the highly active γ phase, and the SiC core is not oxidized.

[0092] ③ Final product characteristics: The shell is a highly active, mesoporous γ-Al2O3 with a thickness of 5-8 nm, which is firmly bonded to the SiC core by ≡Si-O-Al≡ bonds.

[0093] III. Product Quality Characterization Morphology: TEM showed a clear core-shell structure with uniform and continuous shell layers, while SEM showed that the whiskers were well dispersed and there was no melting or agglomeration.

[0094] Phase composition: The XRD pattern shows both sharp diffraction peaks of SiC and characteristic broad peaks of γ-Al2O3, with no impurities.

[0095] Surface chemistry: XPS depth analysis showed that Al, O and Si elements were distributed in a gradient at the interface, and the binding energy shifts of Al 2p and Si 2p confirmed the existence of Si-O-Al bonds.

[0096] Thermal stability: TG-DSC analysis showed that the product exhibited a distinct endothermic peak near 1200℃ (corresponding to the γ→α-Al2O3 phase transition), with a total mass loss of less than 1%, demonstrating its excellent thermal stability.

[0097] This invention addresses the common problem of weak interfacial bonding in nanocomposite materials by transforming traditional physical adsorption into strong chemical bonding through vacuum plasma pretreatment. The sol-gel liquid phase deposition method enables precise control of the Al2O3 shell thickness at the nanoscale (5-8 nm), a prerequisite for obtaining uniform and excellent coating performance. The highly active γ-Al2O3 shell serves as both a "reaction site" for low-temperature condensation with silica sol and a "sacrificial layer" that absorbs a large amount of heat energy through phase change at high temperatures (1200℃), fundamentally supporting the two core highlights of this invention's coating: 0℃ cold-applied curing and ultra-high temperature resistance up to 1500℃.

[0098] Example 1: Application of Glazed Ceramic Tile Renovation and Protection in Tunnels (1) The components of the single-component inorganic cold-applied high-temperature self-cleaning coating in this embodiment are shown in Table 1: Table 1

[0099] 2. Coating preparation steps: (1) Whisker activation: When SiC / Al2O3 whiskers were placed in a plasma reaction chamber (300W argon gas, 10 min), the surface -OH density reached 8.2 ions / nm. 2 (XPS analysis); (2) Core-shell structure construction: Activated whiskers and nano-TiO2 were added to a ball mill jar (zirconia balls, ball-to-material ratio 5:1) at a mass ratio of 2:1. Ball milling for 2 hours (450 rpm) yielded TiO2-coated whisker composites (HR-TEM showed coating thickness of 5-8 nm). (3) Gradient dispersion: Pre-dispersion of silica sol with deionized water (1000 rpm / 10 min); Add whisker / TiO2 composite and shear at 3000 rpm for 30 min (particle size D50=75nm, laser particle size analyzer). Add ZrO2 and apatite sequentially, and sonicate (40kHz / 20min). Curing: After adding the additives, the viscosity was 3520 mPa·s after 24 hours of curing (25℃, Brookfield DV2T).

[0100] 3. Surface preparation (glazed ceramic tiles for existing tunnels) Object: Qinling Zhongnanshan Tunnel, with residual oil and dust on the surface of the tiles.

[0101] Processing flow: (1) Cleaning without removal: High-pressure water jet (pressure 20MPa) is used to rinse away surface dust and oil film; Wipe with a neutral detergent, wash with water, and air dry for 24 hours. Moisture content control: Surface moisture content 4.2%; (2) Interface enhancement: Spraying a silane coupling agent pretreatment solution (KH-560: ethanol = 1:9) enhances adhesion.

[0102] (3) Construction technology Environmental conditions: Temperature 0℃, relative humidity 28%; Coating method: Roller coating, 2 coats, material consumption 0.2kg / m²~0.25kg / m² Coating design: First coat: wet film thickness 120μm, surface drying time 40min (0℃); Second coat: 4h interval, wet film thickness 110μm; Total dry film thickness: The dry film thickness measured by a magnetic thickness gauge is approximately 110 μm (QG-2020 magnetic thickness gauge). Curing conditions: Natural curing for 24 hours (1℃).

[0103] Application effect: Workability: Can be applied in 0℃ environment, cures in 24 hours, dry film thickness 110μm, pencil hardness (72h) 6H.

[0104] High temperature resistance: After being burned by a gas cutting flame at 1500℃ for 300 seconds, the coating showed no discoloration or peeling, with a mass loss rate of 0.11%.

[0105] Stain resistance: In tunnel environments (vehicle exhaust + dust), no obvious oil stains adhere after 24 hours; it can be cleaned by rinsing with water. Adhesion: Adhesion to tunnel ceramic tile substrate is 2.1 MPa, with no peeling.

[0106] Performance testing characteristics: The coating of this invention and epoxy coating were applied by roller to tunnel glazed ceramic tiles. After 24 hours, the stain resistance effect was as follows: Figures 1a-1b As shown.

[0107] In this embodiment, the cold coating film formation mechanism is as follows: ① Capillary accelerated dehydration: Whisker network forms nanochannels (pore size 10-50nm), and the water molecule diffusion coefficient reaches 1.8×10 -9 m 2 / s (4 times higher than pure silica sol); ② Crosslinking degree verification: After curing at 0℃ for 48h, FT-IR showed 1080cm². -1 The area of ​​the Si-O-Si peak at 5℃ was 83% higher than that of the control group at 5℃.

[0108] The coating prepared in this embodiment was applied to the glazed surface of a ceramic tile. After curing for 24 hours, it was then calcined using an acetylene torch at 1500°C for 300 seconds. No change was observed in the coating. Figure 2 As shown. The ablation resistance principle at 1500℃ in this embodiment is based on: ① aerogel thermal barrier, with whiskers forming closed pores; ② phase transition endothermic, with the γ-Al2O3→α-Al2O3 endothermic peak (1200℃); ③ high temperature stability, with a mass loss of 0.12% after burning at 1500℃ for 300s.

[0109] The coating prepared in this embodiment was applied to a steel plate and tested. Figures 3a-3b As shown, the surface temperature of the steel plate substrate is 61.0℃, and the surface temperature of the steel plate coated with the coating of the present invention is 40.6℃. The heat insulation and cooling properties of the coating in the present invention are due to high infrared reflectivity (85%@800nm) + low thermal conductivity (0.035W / m·K).

[0110] The coating prepared in this embodiment is used to form a coating with a superhydrophilic surface: a contact angle of 10.2°, rainwater forms a water film to wash away oil stains; the concentration of •OH free radicals under ultraviolet light is 2.8 μmol / L, and the E. coli killing rate is 99.98%.

[0111] The coating prepared in this embodiment, after being applied to the surface of a tinplate and cured, resembles ceramic and can withstand high temperatures up to 1250℃. After being burned at high temperature for 30 minutes, there was no abnormal surface discoloration or release of toxic or harmful gases. After being burned with a flame gun for 5 minutes, the tinplate melted at the high temperature, but the coating showed no change. Figures 4a-4c As shown.

[0112] The coating prepared in this embodiment can be applied and cured at 0°C, and its curing process is unaffected by temperature. It can even be applied in snowy weather without affecting its physical properties, such as… Figures 5a-5b As shown.

[0113] Comparative Example 1 Similar to Example 1, except that SiC / Al2O3 composite whiskers are replaced by SiC whiskers. The prepared coating exhibits decreased temperature resistance: due to the lack of the Al2O3 phase transition endothermic (γ→α, endothermic 1.2 kJ / g) protection mechanism, the pure SiC framework undergoes accelerated oxidation at ultra-high temperatures, resulting in a significant increase in mass loss. It also loses its hydrophilicity: TiO2 is directly loaded onto the inert SiC surface, resulting in weak bonding and poor dispersion. Photocatalysis and hydrophilic effects cannot be achieved, the contact angle increases, and oil stains adhere very easily.

[0114] Comparative Example 2 Similar to Example 1, except that the SiC / Al2O3 composite whiskers are replaced by Al2O3 whiskers. The prepared coating suffers from insufficient hardness and strength: the modulus and hardness of Al2O3 whiskers are lower than those of SiC, making it impossible to form a high-strength network, resulting in a decrease in the overall hardness of the coating. Ablation resistance is also generally poor: although there is endothermic phase transition, the temperature limit of the framework itself is lower than that of SiC, leading to softening and deformation under prolonged burning at 1500℃.

[0115] Comparative Example 3 Similar to Example 1, but without the SiC / Al2O3 composite whiskers. The coating loses its three-dimensional reinforcing framework, resulting in high internal stress after silica sol film formation, leading to direct cracking and pulverization, preventing the formation of a continuous coating, and causing all performance characteristics to fail.

[0116] Comparative Example 4 Similar to Example 1, but without nano-TiO2. The prepared coating loses its self-cleaning function: the contact angle increases to 65°, and although it still has some hydrophilicity, it lacks the ability to photocatalytically decompose organic matter. Water rinsing alone cannot remove oil stains, leading to significant oil accumulation in the tunnel. Temperature resistance decreases slightly: due to the lack of the synergistic effect between TiO2 and whiskers, the coating density is slightly worse.

[0117] Comparative Example 5 Same as Example 1, except that: silica sol is missing. Inability to form a film: Silica sol is the only low-temperature film-forming binder; its absence results in a lack of adhesion in the mixture, making it impossible to form a coating on the substrate, and thus all performance tests cannot be performed.

[0118] Comparative Example 6 Similar to Example 1, except that: the apatite antibacterial agent is missing or other antibacterial agents are used. The prepared coating has zero antibacterial function: the coating does not have active antibacterial and antifungal capabilities, and the risk of microbial growth is high when used in the humid environment of a tunnel for a long time.

[0119] Comparative Example 7 Same as Example 1, except that lithium-based bentonite is missing. The workability and storage properties of the coating deteriorate: the coating experiences hard settling during storage and drips on vertical surfaces during application, resulting in uneven dry film thickness, localized decrease in hardness, and affecting the overall protective effect.

[0120] Comparative Example 8 Same as Example 1, except that the silane coupling agent KH-560 is missing. The adhesion of the prepared coating drops sharply: there is a lack of chemical bonding bridges between the coating and the substrate, and the adhesion is reduced by more than 60% due to physical anchoring and van der Waals forces. It is extremely easy to peel off under thermal shock or mechanical impact.

[0121] The performance of the coatings prepared in Example 1 and Comparative Examples 1-8 on tunnel ceramic tile substrates is shown in Table 2.

[0122] Table 2

[0123] Table 2 shows that Example 1 of this invention achieves an optimal balance of properties such as low-temperature curing, ultra-high temperature resistance, self-cleaning, and high adhesion through the synergistic combination of SiC / Al2O3 composite whiskers, nano-TiO2, silica sol, apatite, and specific additives. The absence or substitution of any key component (Comparative Examples 1-8) leads to a significant deterioration of one or more core properties, which fully demonstrates the non-obviousness of the technical solution of this invention and the inseparable synergistic effect among the components, satisfying the inventiveness requirements of patent law.

[0124] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0125] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A single-component inorganic cold-applied high-temperature self-cleaning coating containing nanofibers, characterized in that, The raw materials for preparing the single-component inorganic cold-applied high-temperature self-cleaning coating include the following components by weight percentage: 18-22% SiC / Al2O3 composite whiskers, 8-12% nano TiO2, 35-38% silica sol, 12-15% nano ZrO2, 5-8% apatite antibacterial agent, 2-3% lithium-based bentonite, 1.5-2% silane coupling agent, and the remainder is water.

2. The single-component inorganic cold-applied high-temperature resistant self-cleaning coating according to claim 1, characterized in that: The SiC / Al2O3 composite whiskers have a diameter of 50~100nm and an aspect ratio >50; And / or, the particle size of the nano-TiO2 is ≤20nm; And / or, the Na⁺ content in the silica sol is <0.1wt%, and the particle size of SiO₂ is 10~15nm; And / or, the particle size of the nano-ZrO2 is 20~100nm, preferably 30~80nm; and / or, the phase of the nano-ZrO2 is monoclinic. And / or, the SiC / Al2O3 composite whiskers have a core-shell structure; And / or, the SiC / Al2O3 composite whiskers include SiC / γ-Al2O3 composite whiskers.

3. The single-component inorganic cold-applied high-temperature self-cleaning coating according to claim 1, characterized in that, The preparation method of the SiC / Al2O3 composite whiskers includes: Activated SiC whiskers were obtained by surface pretreatment and plasma activation of SiC whiskers. An amorphous alumina hydrate shell was grown in situ on the surface of activated SiC whiskers using the sol-gel method, followed by separation, drying / gradient crystallization heat treatment to obtain SiC / Al2O3 composite whiskers.

4. The single-component inorganic cold-applied high-temperature self-cleaning coating according to claim 1, characterized in that: The chemical formula of the apatite antibacterial agent is Ca. 10 (PO4)6(OH)2, where Ca / P = 1.67; And / or, the thixotropic index of the lithium-based bentonite is >4.5; And / or, the silane coupling agent comprises a silane coupling agent containing an epoxy, amino, or (meth)acryloyloxy group; preferably, the silane coupling agent comprises γ-glycidoxypropyltrimethoxysilane (KH-560).

5. The preparation method of the single-component inorganic cold-applied high-temperature self-cleaning coating containing nanofibers according to any one of claims 1-4, characterized in that, include: SiC / Al2O3 composite whiskers were activated using argon plasma to obtain activated whiskers; Activated whiskers and nano-TiO2 were blended and ball-milled to obtain TiO2-coated whisker composites; Furthermore, silica sol is mixed with water for pre-dispersion, then TiO2-coated whisker composite is added and subjected to high-speed shearing, followed by the sequential addition of nano-ZrO2 and apatite antibacterial agent and ultrasonic treatment, and finally the addition of additives for curing treatment, to obtain a single-component inorganic cold-applied high-temperature resistant self-cleaning coating.

6. The preparation method according to claim 5, characterized in that: The activation process uses a power of 300W and a time of 10 minutes. And / or, the process parameters used in the blending ball milling treatment include: Φ3mm zirconia balls, ball-to-material ratio of (4-6):1, rotation speed of 300~500rpm, and time of 1.5~3h; And / or, the pre-dispersion is carried out at a rotation speed of 800~1200 rpm for a time of 5~15 min; And / or, the high-speed shearing uses a rotation speed of 2500~3500 rpm and a time of 20~40 min; And / or, the ultrasonic treatment uses a power of 35~45kHz and a time of 15~30min; And / or, the ripening process takes 12 to 48 hours.

7. The preparation method according to claim 5, characterized in that: The additives include any one or more combinations of dispersants, rheology modifiers, defoamers, wetting agents, pH adjusters, and antifreeze agents; And / or, the additive accounts for 0.5~5 wt% of the single-component inorganic cold-applied high-temperature self-cleaning coating containing nanofibers; And / or, the surface -OH density of the activated whiskers is 8.2 OH atoms / nm²; And / or, the viscosity of the single-component inorganic cold-applied high-temperature self-cleaning coating is 3500±200mPa·s, and the particle size distribution D90<100nm.

8. A method for preparing a high-temperature resistant, self-cleaning, antibacterial, and mildew-resistant coating, characterized in that, include: A single-component inorganic cold-applied high-temperature resistant self-cleaning coating containing nano-whiskers was prepared using the preparation method described in any one of claims 5-7. Furthermore, the single-component inorganic cold-applied high-temperature self-cleaning coating is applied to the surface of a substrate in an environment above 0°C and cured to obtain a high-temperature self-cleaning antibacterial and mildew-resistant coating.

9. A high-temperature resistant, self-cleaning, antibacterial, and mildew-resistant coating prepared by the method described in claim 8.

10. The application of the single-component inorganic cold-applied high-temperature self-cleaning coating containing nano-whiskers as described in any one of claims 1-4, or the high-temperature self-cleaning antibacterial and mildew-resistant coating as described in claim 9, in low-temperature environment construction, mildew prevention in humid environments, and long-term stain resistance in tunnels / bridges.

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