High-interfacial-activity high-strength electromagnetic shielding thin-spraying cement material and preparation method thereof

Abstract

The invention discloses a high-interfacial-activity high-strength electromagnetic shielding thin-spraying cement material and a preparation method thereof. The material comprises the following components in parts by weight: 15-45 parts of cement, 8-15 parts of water-borne epoxy resin, 8-15 parts of an epoxy resin curing agent, 15-30 parts of a water-borne styrene-acrylate emulsion, 15-45 parts of heavy calcium carbonate, 5-15 parts of quartz powder, 5-10 parts of titanium dioxide, 2-8 parts of attapulgite, 1-5 parts of calcium carbonate whiskers, 0.5-2 parts of a coupling agent, 5-10 parts of mixing water and 0.1-0.3 part of a water reducing agent. And 1-5 parts by weight of core-shell-like tetrapod-like zinc oxide whiskers. According to the invention, the interfacial activity, the crack resistance, the strength and the spraying property of the thin-spraying cement material can be synergistically improved, and the material is endowed with the required electromagnetic shielding characteristic when being used in special scenes such as intelligent buildings.

Description

Technical Field

[0001] This invention relates to the field of concrete materials technology, specifically to a high-interfacial-activity, high-strength electromagnetically shielded thin-film sprayed cement material and its preparation method. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Marine cement concrete has been widely used in the construction of marine engineering infrastructure such as ports, wharves, and cross-sea bridges due to its advantages such as high compressive strength, convenient construction, and low cost. However, as a porous, heterogeneous, multiphase material, marine cement concrete is susceptible to corrosion from harmful ions such as chloride and sulfate ions present in the marine environment. This corrosion leads to steel reinforcement corrosion, expansion, and cracking of the marine cement concrete, significantly reducing the safety and stability of the structure. Applying a protective coating to the surface of marine cement concrete can effectively block the corrosion of harmful ions and is an effective measure to improve its service life.

[0004] Organic coatings offer good flexibility but suffer from poor environmental friendliness, durability, and interfacial compatibility. Inorganic coatings formed from cementitious materials, while exhibiting good aging resistance and environmental friendliness, suffer from brittleness, susceptibility to cracking, and low bond strength. Thin-layer sprayed cementitious materials, with a thickness of 5-10 mm, serve as a novel organic-inorganic composite protective coating material that can significantly reduce the risk of substrate exposure. However, they still exhibit shortcomings such as low interfacial activity, susceptibility to cracking, blistering, and peeling, low tensile strength, and poor resistance to sagging during spraying. Furthermore, conventional thin-layer sprayed cementitious materials struggle to meet the additional electromagnetic protection requirements of special scenarios such as intelligent buildings. Summary of the Invention

[0005] This invention provides a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material and its preparation method. It achieves a synergistic improvement in the interfacial activity, crack resistance, strength, and sprayability of the thin-film sprayed cement material, and endows the material with the electromagnetic shielding properties required for use in special scenarios such as intelligent buildings. Ultimately, it realizes the integrated improvement of "protection-reinforcement-electromagnetic shielding" for marine cement concrete structures. Specifically, the technical aspects of this invention are as follows.

[0006] First, a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material is provided, comprising the following components in the following proportions: 15-45 parts by weight of cement, 8-15 parts by weight of waterborne epoxy resin, 8-15 parts by weight of epoxy resin curing agent, 15-30 parts by weight of waterborne styrene-acrylate emulsion, 15-45 parts by weight of heavy calcium carbonate, 5-15 parts by weight of quartz powder, 5-10 parts by weight of titanium dioxide, 2-8 parts by weight of attapulgite, 1-5 parts by weight of calcium carbonate whiskers, 0.5-2 parts by weight of coupling agent, 5-10 parts by weight of mixing water, 0.1-0.3 parts by weight of water-reducing agent, and 1-5 parts by weight of core-shell type tetraneedle zinc oxide whiskers. The whiskers are prepared by the following method: (1) A dispersion of zinc powder, ferric nitrate powder, and graphite powder is formed in anhydrous ethanol and dried to obtain mixed powder A.

[0007] (2) After calcining the mixed powder A, cool it to room temperature, wash it and dry it. Then mix the obtained powder B with acetic acid solution and let it stand. Then separate the solid product and wash it to obtain neutral powder C.

[0008] (3) The neutral powder C is purified under heating conditions, and then cooled to room temperature to obtain powder D.

[0009] (4) Disperse the powder D and dopamine in water, then adjust the system to alkaline and stir the reaction. After completion, separate the solid product, wash and dry it to obtain powder E.

[0010] (5) Mix the powder E with Co 2+ The source is dispersed in anhydrous methanol, and then the resulting mixture F is added to a solution G formed by dissolving 2-methylimidazole in anhydrous methanol and ultrasonically treated. Then, the resulting mixture H is washed and dried to obtain the core-shell type tetraneedle zinc oxide whiskers.

[0011] Further, in step (1), the ratio of zinc powder, ferric nitrate powder, graphite powder, and anhydrous ethanol is 20-40 parts by weight: 0.3-1.5 parts by weight: 0.5-6 parts by weight: 100-150 mL. The graphite powder can not only consume oxygen and reduce local oxygen partial pressure by reacting with oxygen, thus creating a low-oxygen potential environment conducive to Zn vapor generation and vapor-phase deposition growth, but also the CO-reducing atmosphere generated by the graphite and oxygen helps promote the formation and transport of Zn vapor, inhibiting the densification and sintering agglomeration of ZnO, thereby increasing the probability of nucleation and directional growth of tetraneedle zinc oxide whiskers. In addition, the graphite powder can also buffer the oxidizing atmosphere and facilitate the iron doping process, thereby improving the electronic structure and electromagnetic loss characteristics of the whiskers.

[0012] Furthermore, in step (2), the calcination temperature is 920~1000℃ and the time is 15~30min.

[0013] Furthermore, in step (2), the drying temperature is 40~60℃ and the time is 18~24h.

[0014] Further, in step (2), the mass ratio of powder B to acetic acid solution is 1:10~20. Optionally, the pH of the acetic acid solution is 3~4.

[0015] Furthermore, in step (3), the heating temperature is 200~350℃ and the holding time is 1~2 hours.

[0016] Further, in step (4), the mass ratio of powder D, dopamine, and water is 3~10:0.2~1.0:80~150.

[0017] Further, in step (4), the pH of the system is adjusted to 8.4-8.6 using a buffer solution. Optionally, the buffer solution includes any one of: tris(hydroxymethyl)aminomethane hydrochloride buffer, borate buffer, phosphate buffer, carbonate buffer, etc.

[0018] Furthermore, in step (4), the stirring reaction time is 6 to 24 hours.

[0019] Further, in step (5), the powders E and Co 2+ The mass ratio of raw material to anhydrous methanol is 4~6:2~6:200~300.

[0020] Further, in step (5), the Co 2+ The sources include at least one of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt sulfate.

[0021] Further, in step (5), the mass ratio of the mixture F to the solution G is 1:0.8~1. Optionally, the solution G is composed of 2.2~6.7 parts by weight of 2-methylimidazole and 200~300 parts by weight of anhydrous methanol.

[0022] Furthermore, in step (5), the ultrasonic treatment time is 5 to 15 minutes.

[0023] Furthermore, the solid content of the waterborne epoxy resin is 45-55%, the solid content of the epoxy curing agent is 35-45%, and the solid content of the waterborne styrene-acrylate emulsion is 50-60%.

[0024] Furthermore, the epoxy curing agent includes at least one of the following: water-based aliphatic polyamine curing agents, cashew phenol modified amine curing agents, etc.

[0025] Furthermore, the coupling agent includes at least one of KH-550, KH-560, KH-570, KH-792, etc.

[0026] Furthermore, the water-reducing agent includes at least one of the following: polycarboxylate water-reducing agent, naphthalene-based water-reducing agent, lignin sulfonate water-reducing agent, etc.

[0027] Secondly, this invention provides a method for preparing the aforementioned high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, comprising the following steps: (1) Mix the cement, heavy calcium carbonate, quartz powder, titanium dioxide, attapulgite, calcium carbonate whiskers and water-reducing agent to obtain a mixed powder for later use.

[0028] (2) After mixing the coupling agent with the mixing water, adjust it to alkaline to obtain a hydrolyzed solution for later use.

[0029] (3) Mix the waterborne epoxy resin and waterborne styrene-acrylate emulsion, then add the core-shell type tetrane zinc oxide whiskers and mix well to obtain liquid system I, for later use.

[0030] (4) Mix the hydrolysis solution with liquid system I, then add the water-based epoxy curing agent and mix to obtain liquid system II. Finally, mix liquid system II with the mixed powder to obtain the thin-spray cement material.

[0031] Further, in step (2), alkalinity refers to pH = 8.0~8.2. Optionally, any one of sodium bicarbonate, ammonia, etc., can be used to adjust the pH.

[0032] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects: This invention uses a mixed powder A formed from zinc powder, ferric nitrate, and graphite powder, which is calcined. The zinc vapor formed by the evaporation of zinc powder reacts with the oxygen produced by the decomposition of ferric nitrate to form zinc oxide, which grows in four specific directions to form a tetrap-like structure. Simultaneously, during this process, it reacts with Zn... 2+ Fe with similar ionic radii 3+ with Fe 2+ (Under the localized reduction conditions synergistically generated by graphite and ferric nitrate (Fe(NO3)3→Fe2O3+NO2+O2, NO2+C→N2+CO), some Fe...) 3+ To Fe 2+ Transformation) replaces a small amount of Zn in the zinc oxide lattice 2+Lattice doping yields iron-doped tetrapod-shaped zinc oxide whiskers, altering their electronic structure and enhancing their electromagnetic shielding properties. Furthermore, this invention utilizes in-situ polymerization of dopamine on the surface of the tetrapod-shaped zinc oxide whiskers under alkaline conditions to form a polydopamine layer. The catechols and amino groups within this layer adhere firmly and uniformly to the whisker surface through hydrogen bonding, coordination, and Michael addition reactions, ultimately forming a nanoscale thin film. This film completely encapsulates the tetrapod-shaped zinc oxide whiskers, improving their compatibility with organic components in the thin-film coating system. Additionally, the abundant catechols and amino groups in the polydopamine can anchor Co... 2+ This acts as a "coordination layer," laying the foundation for the subsequent in-situ self-assembly of the cobalt-based imidazolium ester framework structure. Furthermore, this invention involves immersing the treated whiskers / powder E into a solution containing Co. 2+ In the anhydrous methanol of the source, Co 2+ It will rapidly undergo strong coordination with amino and phenolic hydroxyl groups on the thin film layer, causing Co 2+ Co is formed by directional adsorption on the surface of the thin film layer. 2+ The localized enrichment regions provide metal ion sites for the nucleation of the cobalt-based imidazolium ester framework structure. Furthermore, this invention anchors a large number of Co... 2+ When tetra-needle zinc oxide whiskers / mixture F are mixed with 2-methylimidazole, the 2-methylimidazole molecules rapidly diffuse to the whisker surface and interact with the anchored Co. 2+ Coordination self-assembly and directional formation of cobalt-based imidazole ester framework nanoparticles yield the core-shell type tetraneedle zinc oxide whiskers of this invention.

[0033] When the core-shell type tetraneedle zinc oxide whiskers are incorporated into thin-layer sprayed cementitious materials, on the one hand, the Fe-doped tetraneedle zinc oxide whiskers provide skeletal support and basic dielectric / magnetic loss capability; the conjugated π-electron system or metal coordination mechanism of the middle polydopamine film layer provides effective electron transition and transport paths, promoting interfacial polarization and conductivity loss, and enhancing the overall conductivity and dielectric response of the material. The outermost cobalt-based imidazolium ester framework nanoparticles can both adsorb electromagnetic waves and provide magnetic loss through the Co-based components, while their polarization effect enhances dielectric loss; this three-level synergy achieves the integration of "structural support, dielectric loss, and magnetic loss," ultimately endowing the thin-layer sprayed material with excellent electromagnetic shielding properties. On the other hand, the "steel bar-mortise and tenon" effect generated by the special structural morphology of the core-shell type tetraneedle zinc oxide whiskers of this invention can effectively improve the mechanical interlocking effect and improve the performance of the thin-layer sprayed material. This includes: (1) Enhanced interfacial activity and bridging ability: The polydopamine layer on the surface of the core-shell type tetrane zinc oxide whisker acts as a "universal adhesive". Its abundant catechol and amino functional groups not only have a strong binding effect with the whisker body, but also can form strong hydrogen bonds, coordination bonds or covalent bonds with the epoxy groups of the waterborne epoxy resin and the carboxyl groups of the waterborne styrene-acrylate emulsion, etc., to achieve the "first-level" strong connection between the inorganic core and the organic matrix. The cobalt-based imidazole ester framework structure has a porous structure and a huge specific surface area. Its surface active sites can form strong chemical adsorption and physical entanglement with the organic resin chains (formed after the waterborne epoxy resin and waterborne styrene-acrylate emulsion are cured). At the same time, the pores formed by the accumulation of cobalt-based imidazole ester framework nanoparticles allow organic resin chain segments to penetrate, fill and entangle, forming an interfacial "mechanical interlock" to achieve the "second-level" enhanced connection. Through these two stages of action, a strong, multi-layered chemical-physical bond can be established between the organic phase and the inorganic phase (such as CSH gel) formed by cement hydration products, forming a "steel-mortise and tenon" effect, which greatly improves stress transfer efficiency, strengthens the weak interface transition zone between the organic and inorganic phases, and improves the adhesion and tensile properties of thin-sprayed cement materials.

[0034] (2) Synergistic Improvement of Multi-Network Interpenetrating Structure and Performance: The core-shell type four-needle zinc oxide whiskers interlock in the slurry to form a physical three-dimensional network. During the curing process, it guides and promotes the curing of waterborne epoxy resin to form a rigid cross-linked network, the formation of a flexible polymer network by waterborne styrene-acrylate emulsion film, and the generation of an inorganic rigid network by cement hydration products. These three types of networks interpenetrate, entwine, and lock at the bridging points and interfaces of the whiskers, forming a stable "three-dimensional interpenetrating mesh structure". The rigid network provides strength, while the bridging and pull-out effects of the flexible network and whiskers provide toughness and crack resistance. The three work together to achieve a balance between rigidity and flexibility, and to achieve a synergistic improvement in the strength and crack resistance of the thin-film coating. In addition, the core-shell type tetraneedle zinc oxide whiskers form a weak gel network through hydrogen bonding and other interactions between the cobalt-based imidazole ester framework nanoparticles on their surface and organic polymer chains, attapulgite, etc. This makes the cement slurry thinner when sheared (low viscosity and easy atomization during spraying), and the network quickly recovers after shearing stops (anti-sagging), giving the thin spray coating material excellent thixotropic properties and sprayability. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0036] Figure 1 Image of a core-shell type tetraneedle zinc oxide whisker sample prepared in Example 1 below.

[0037] Figure 2 Scanning electron microscope (SEM) image of the core-shell type tetraneedle zinc oxide whiskers prepared for Example 1 below.

[0038] Figure 3 Transmission electron microscopy (TEM) image of the core-shell type tetraneedle zinc oxide whiskers prepared for Example 1 below.

[0039] Figure 4 The image shows a core-shell type tetraneedle zinc oxide whisker sample prepared in Example 2 below.

[0040] Figure 5 Image of a core-shell type tetraneedle zinc oxide whisker sample prepared in Example 3 below.

[0041] Figure 6 The image shows a core-shell type tetraneedle zinc oxide whisker sample prepared in Example 4 below.

[0042] Figure 7 Image of a core-shell type tetraneedle zinc oxide whisker sample prepared in Example 5 below.

[0043] Figure 8 Image of a core-shell type tetraneedle zinc oxide whisker sample prepared in Example 6 below.

[0044] Figure 9 Image of a core-shell type tetraneedle zinc oxide whisker sample prepared in Example 7 below.

[0045] Figure 10 Image of a core-shell type tetraneedle zinc oxide whisker sample prepared in Example 8 below. Detailed Implementation

[0046] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0047] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. All reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions.

[0048] Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the method of this invention. The technical solution of this invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0049] Example 1: 1. Preparation of a core-shell type tetraneedle zinc oxide whisker, comprising the following steps: (1) Zinc powder, ferric nitrate powder, graphite powder and anhydrous ethanol are mixed in a ratio of 30 parts by weight: 1.0 parts by weight: 3 parts by weight: 120 mL and then ultrasonically treated for 40 min to obtain a dispersion. The mixture is then dried to obtain mixed powder A for later use.

[0050] (2) The mixed powder A is heated to 950°C and calcined for 20 min, then naturally cooled to room temperature. The calcined product is washed with water and dried at 50°C for 24 hours. Then, the powder B is mixed with acetic acid solution (pH=3) at a mass ratio of 1:15 and allowed to stand. After no more bubbles are overflowed, the solid product is filtered out and washed with water until neutral to obtain neutral powder C for later use.

[0051] (3) Heat the neutral powder C to 300°C and keep it at that temperature for 1.5 hours. After that, cool it to room temperature to obtain powder D for later use.

[0052] (4) Mix the powder D, dopamine, and water at a mass ratio of 6:0.7:100 and stir until homogeneous. Then, adjust the pH of the system to 8.5 using tris(hydroxymethyl)aminomethane hydrochloride buffer and stir for 18 hours. After completion, filter out the solid product, wash and dry it to obtain powder E for later use.

[0053] (5) The powder E, cobalt nitrate, and anhydrous methanol are mixed at a mass ratio of 4.5:4:250 and stirred until homogeneous. Then, the resulting mixture F is mixed with solution G (composed of 5 parts by weight of 2-methylimidazole and 250 parts by weight of anhydrous methanol) at a mass ratio of 1:1 and ultrasonically treated for 10 minutes. The resulting mixture H is then washed with water and dried to obtain core-shell type tetraneedle zinc oxide whiskers (e.g. Figure 1 As shown, its microscopic diagram is as follows Figure 2 and Figure 3 (As shown).

[0054] 2. A method for preparing a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, comprising the following steps: (I) Take the following raw materials in the following proportions: 40 parts by weight of 42.5 ordinary silicate cement, 12 parts by weight of waterborne epoxy resin with a solid content of 50%, 13 parts by weight of epoxy resin curing agent (model FN-215A, from Ruisan (Shandong) New Material Technology Co., Ltd.) with a solid content of 40%, 25 parts by weight of waterborne styrene-acrylate emulsion with a solid content of 55%, 30 parts by weight of heavy calcium carbonate, 10 parts by weight of quartz powder, 7 parts by weight of titanium dioxide, 5 parts by weight of attapulgite, 2.5 parts by weight of calcium carbonate whiskers, 1.5 parts by weight of coupling agent (KH-550), 7.5 parts by weight of mixing water, 0.2 parts by weight of polycarboxylate superplasticizer, and 3.5 parts by weight of the core-shell type tetraneedle zinc oxide whiskers described in this embodiment.

[0055] (II) Mix the cement, heavy calcium carbonate, quartz powder, titanium dioxide, attapulgite, calcium carbonate whiskers and water-reducing agent and stir for 5 minutes to obtain a mixed powder for later use.

[0056] (III) Mix the coupling agent with the mixing water and stir for 5 minutes. Then add sodium bicarbonate to adjust the pH of the system to 8.0 to obtain a hydrolyzed solution for later use.

[0057] (IV) Mix the waterborne epoxy resin and waterborne styrene-acrylate emulsion and stir for 3 minutes. Then add the core-shell type tetrane zinc oxide whiskers and stir for 10 minutes to obtain liquid system I, which is ready for use.

[0058] (V) The hydrolyzed solution is mixed with liquid system I and stirred for 2 minutes. Then, the water-based epoxy curing agent is added and stirred for 1 minute to obtain liquid system II. Finally, liquid system II is mixed with the mixed powder and stirred for 1 minute to obtain thin-spray cement material.

[0059] Performance Testing: The various properties of the cement material prepared in this embodiment were tested, and the results are shown in Table 1 below. Specifically: bond strength was tested according to standard GB / T 16777-2008; tensile strength and elongation at break were tested according to standard ASTM D638; shielding effectiveness was tested according to standard GB / T 25471-2010; and sag resistance index was tested according to standard ASTM D4400.

[0060] Table 1

[0061] Example 2: 1. Preparation of a core-shell type four-needle zinc oxide whisker, comprising the following steps: (1) Zinc powder, ferric nitrate powder, graphite powder and anhydrous ethanol are mixed in a ratio of 40 parts by weight: 1.5 parts by weight: 6 parts by weight: 150 mL and then ultrasonically treated for 40 min to obtain a dispersion. The mixture is then dried to obtain mixed powder A for later use.

[0062] (2) The mixed powder A is heated to 920°C and calcined for 30 min, then naturally cooled to room temperature. The calcined product is washed with water and dried at 60°C for 18 hours. Then, the powder B is mixed with acetic acid solution (pH=4) at a mass ratio of 1:20 and allowed to stand. After no more bubbles are overflowed, the solid product is filtered out and washed with water until neutral to obtain neutral powder C for later use.

[0063] (3) Heat the neutral powder C to 350°C and keep it at that temperature for 1 hour. After that, cool it to room temperature to obtain powder D for later use.

[0064] (4) Mix the powder D, dopamine, and water at a mass ratio of 10:1:150 and stir until homogeneous. Then, adjust the pH of the system to 8.4 using tris(hydroxymethyl)aminomethane hydrochloride buffer and stir for 24 hours. After completion, filter out the solid product, wash and dry it to obtain powder E for later use.

[0065] (5) The powder E, cobalt nitrate, and anhydrous methanol are mixed at a mass ratio of 4:2:200 and stirred until homogeneous. Then, the resulting mixture F is mixed with solution G (composed of 6.7 parts by weight of 2-methylimidazole and 300 parts by weight of anhydrous methanol) at a mass ratio of 1:0.8 and ultrasonically treated for 15 minutes. The resulting mixture H is then washed with water and dried to obtain core-shell type tetraneedle zinc oxide whiskers (e.g. Figure 4 (As shown).

[0066] 2. A method for preparing a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, comprising the following steps: (I) Take the following raw materials in the following proportions: 45 parts by weight of 42.5 ordinary silicate cement, 15 parts by weight of waterborne epoxy resin with a solid content of 45%, 15 parts by weight of epoxy resin curing agent (model FN-215A, from Ruisan (Shandong) New Material Technology Co., Ltd.) with a solid content of 35%, 30 parts by weight of waterborne styrene-acrylate emulsion with a solid content of 50%, 45 parts by weight of heavy calcium carbonate, 15 parts by weight of quartz powder, 10 parts by weight of titanium dioxide, 8 parts by weight of attapulgite, 5 parts by weight of calcium carbonate whiskers, 2 parts by weight of coupling agent (KH-570), 10 parts by weight of mixing water, 0.3 parts by weight of polycarboxylate superplasticizer, and 5 parts by weight of the core-shell type tetraneedle zinc oxide whiskers described in this embodiment.

[0067] (II) Mix the cement, heavy calcium carbonate, quartz powder, titanium dioxide, attapulgite, calcium carbonate whiskers and water-reducing agent and stir for 5 minutes to obtain a mixed powder for later use.

[0068] (III) Mix the coupling agent with the mixing water and stir for 5 minutes. Then add sodium bicarbonate to adjust the pH of the system to 8.2 to obtain a hydrolyzed solution for later use.

[0069] (IV) Mix the waterborne epoxy resin and waterborne styrene-acrylate emulsion and stir for 3 minutes. Then add the core-shell type tetrane zinc oxide whiskers and stir for 10 minutes to obtain liquid system I, which is ready for use.

[0070] (V) The hydrolyzed solution is mixed with liquid system I and stirred for 2 minutes. Then, the water-based epoxy curing agent is added and stirred for 1 minute to obtain liquid system II. Finally, liquid system II is mixed with the mixed powder and stirred for 1 minute to obtain thin-spray cement material.

[0071] Performance testing: The various properties of the cement material prepared in this embodiment were tested using the same method as in Example 1 above, and the results are shown in Table 2 below.

[0072] Table 2

[0073] Example 3: 1. Preparation of a core-shell type four-needle zinc oxide whisker, comprising the following steps: (1) Zinc powder, ferric nitrate powder, graphite powder and anhydrous ethanol are mixed in a ratio of 20 parts by weight: 0.3 parts by weight: 0.5 parts by weight: 100 mL and then ultrasonically treated for 30 min to obtain a dispersion. Then the mixture is dried to obtain mixed powder A for later use.

[0074] (2) Heat the mixed powder A to 1000℃ and calcine for 15 minutes, then cool it naturally to room temperature. Wash the calcined product with water and dry it at 40℃ for 24 hours. Then mix the obtained powder B with acetic acid solution (pH=4) at a mass ratio of 1:10 and let it stand. After no more bubbles are overflowed, filter out the solid product and wash it with water until it is neutral to obtain neutral powder C for later use.

[0075] (3) Heat the neutral powder C to 200°C and keep it at that temperature for 2 hours. After that, cool it to room temperature to obtain powder D for later use.

[0076] (4) Mix the powder D, dopamine, and water at a mass ratio of 3:0.2:80 and stir until homogeneous. Then, adjust the pH of the system to 8.6 using tris(hydroxymethyl)aminomethane hydrochloride buffer and stir for 6 hours. After completion, filter out the solid product, wash and dry it to obtain powder E for later use.

[0077] (5) The powder E, cobalt nitrate, and anhydrous methanol are mixed at a mass ratio of 6:6:300 and stirred until homogeneous. Then, the resulting mixture F is mixed with solution G (composed of 2.2 parts by weight of 2-methylimidazole and 200 parts by weight of anhydrous methanol) at a mass ratio of 1:0.9 and ultrasonically treated for 5 minutes. The resulting mixture H is then washed with water and dried to obtain core-shell type tetraneedle zinc oxide whiskers (e.g. Figure 5 (As shown).

[0078] 2. A method for preparing a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, comprising the following steps: (I) Take the following raw materials in the following proportions: 15 parts by weight of 42.5 ordinary silicate cement, 8 parts by weight of waterborne epoxy resin with a solid content of 55%, 8 parts by weight of cashew phenol modified amine curing agent with a solid content of 45%, 15 parts by weight of waterborne styrene-acrylate emulsion with a solid content of 60%, 15 parts by weight of heavy calcium carbonate, 5 parts by weight of quartz powder, 5 parts by weight of titanium dioxide, 2 parts by weight of attapulgite, 1 part by weight of calcium carbonate whiskers, 0.5 parts by weight of coupling agent (KH-792), 5 parts by weight of mixing water, 0.1 parts by weight of polycarboxylate superplasticizer, and 1 part by weight of the core-shell type tetraneedle zinc oxide whiskers described in this embodiment.

[0079] (II) Mix the cement, heavy calcium carbonate, quartz powder, titanium dioxide, attapulgite, calcium carbonate whiskers and water-reducing agent and stir for 5 minutes to obtain a mixed powder for later use.

[0080] (III) Mix the coupling agent with the mixing water and stir for 5 minutes. Then add sodium bicarbonate to adjust the pH of the system to 8.0 to obtain a hydrolyzed solution for later use.

[0081] (IV) Mix the waterborne epoxy resin and waterborne styrene-acrylate emulsion and stir for 3 minutes. Then add the core-shell type tetrane zinc oxide whiskers and stir for 10 minutes to obtain liquid system I, which is ready for use.

[0082] (V) The hydrolyzed solution is mixed with liquid system I and stirred for 2 minutes. Then, the water-based epoxy curing agent is added and stirred for 1 minute to obtain liquid system II. Finally, liquid system II is mixed with the mixed powder and stirred for 1 minute to obtain thin-spray cement material.

[0083] Performance testing: The various properties of the cement material prepared in this embodiment were tested using the same method as in Example 1 above, and the results are shown in Table 3 below.

[0084] Table 3

[0085] Example 4: A method for preparing a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, the same as in Example 1 above, except that: in this example, powder D (i.e., tetraneedle zinc oxide whiskers without a polydopamine layer) prepared in Example 1 above is used instead of core-shell type tetraneedle zinc oxide whiskers (such as...). Figure 6 (As shown).

[0086] Performance testing: The various properties of the cement material prepared in this embodiment were tested using the same method as in Example 1 above, and the results are shown in Table 4 below.

[0087] Table 4

[0088] Example 5: A method for preparing a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, the same as Example 1 above, except that: in this example, powder E (i.e., without cobalt-based imidazole ester framework nanoparticles loaded on the polydopamine layer) prepared in Example 1 above is used instead of core-shell-like tetraneedle zinc oxide whiskers (such as... Figure 7 (As shown).

[0089] Performance testing: The various properties of the cement material prepared in this embodiment were tested using the same method as in Example 1 above, and the results are shown in Table 5 below.

[0090] Table 5

[0091] Example 6: A method for preparing a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, the same as in Example 2 above, except that: in this example, zinc oxide powder is used instead of the core-shell type tetraneedle zinc oxide whiskers (such as...). Figure 8 (As shown).

[0092] Performance testing: The various properties of the cement material prepared in this embodiment were tested using the same method as in Example 1 above, and the results are shown in Table 6 below.

[0093] Table 6

[0094] Example 7: A method for preparing a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, the same as in Example 3 above, except that: in this example, commercially available ordinary zinc oxide whiskers are used instead of the core-shell type tetraneedle zinc oxide whiskers (such as...). Figure 9 (As shown).

[0095] Performance testing: The various properties of the cement material prepared in this embodiment were tested using the same method as in Example 1 above, and the results are shown in Table 7 below.

[0096] Table 7

[0097] Example 8: A method for preparing a high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, the same as in Example 3 above, except that: the core-shell type tetraneedle zinc oxide whiskers in this example are prepared by the following method: (1) Zinc powder, ferric nitrate powder and anhydrous ethanol were mixed in a ratio of 40 parts by weight: 1.5 parts by weight: 150 mL and then ultrasonically treated for 40 min to obtain a dispersion. The mixture was then dried to obtain mixed powder A for later use.

[0098] (2) The mixed powder A is heated to 920°C and calcined for 30 min, then naturally cooled to room temperature. The calcined product is washed with water and dried at 60°C for 18 hours. Then, the powder B is mixed with acetic acid solution (pH=4) at a mass ratio of 1:20 and allowed to stand. After no more bubbles are overflowed, the solid product is filtered out and washed with water until neutral to obtain neutral powder C for later use.

[0099] (3) Heat the neutral powder C to 350°C and keep it at that temperature for 1 hour. After that, cool it to room temperature to obtain powder D for later use.

[0100] (4) Mix the powder D, dopamine, and water at a mass ratio of 10:1:150 and stir until homogeneous. Then, adjust the pH of the system to 8.4 using tris(hydroxymethyl)aminomethane hydrochloride buffer and stir for 24 hours. After completion, filter out the solid product, wash and dry it to obtain powder E for later use.

[0101] (5) The powder E, cobalt nitrate, and anhydrous methanol are mixed at a mass ratio of 4:2:200 and stirred until homogeneous. Then, the resulting mixture F is mixed with solution G (composed of 6.7 parts by weight of 2-methylimidazole and 300 parts by weight of anhydrous methanol) at a mass ratio of 1:0.8 and ultrasonically treated for 15 minutes. The resulting mixture H is then washed with water and dried to obtain core-shell type tetraneedle zinc oxide whiskers (e.g. Figure 10 (As shown).

[0102] Performance testing: The various properties of the cement material prepared in this embodiment were tested using the same method as in Example 1 above, and the results are shown in Table 8 below.

[0103] Table 8

[0104] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material, characterized in that, The product comprises the following components in the following proportions: 15-45 parts by weight of cement, 8-15 parts by weight of waterborne epoxy resin, 8-15 parts by weight of epoxy resin curing agent, 15-30 parts by weight of waterborne styrene-acrylate emulsion, 15-45 parts by weight of heavy calcium carbonate, 5-15 parts by weight of quartz powder, 5-10 parts by weight of titanium dioxide, 2-8 parts by weight of attapulgite, 1-5 parts by weight of calcium carbonate whiskers, 0.5-2 parts by weight of coupling agent, 5-10 parts by weight of mixing water, 0.1-0.3 parts by weight of water-reducing agent, 0.4-1.2 parts by defoamer, 0.3-0.6 parts by dispersant, 0.1-0.5 parts by wetting agent, 0.1-0.5 parts by leveling agent, and 1-5 parts by core-shell type tetraneedle zinc oxide whiskers. These whiskers are prepared using the following method: (1) A dispersion of zinc powder, ferric nitrate powder, and graphite powder is formed in anhydrous ethanol and dried to obtain mixed powder A; (2) After calcining the mixed powder A, cool it to room temperature, wash it and dry it. Then mix the obtained powder B with acetic acid solution and let it stand. Then separate the solid product and wash it to obtain neutral powder C. (3) The neutral powder C is purified under heating conditions, and then cooled to room temperature to obtain powder D; (4) Disperse the powder D and dopamine in water, then adjust the system to alkaline and stir the reaction; after completion, separate the solid product, wash and dry it to obtain powder E; (5) Mix the powder E with Co 2+ The source is dispersed in anhydrous methanol, and then the resulting mixture F is added to a solution G formed by dissolving 2-methylimidazole in anhydrous methanol and ultrasonically treated. Then, the resulting mixture H is washed and dried to obtain the core-shell type tetraneedle zinc oxide whiskers.

2. The high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material according to claim 1, characterized in that, In step (1), the ratio of zinc powder, ferric nitrate powder, graphite powder and anhydrous ethanol is 20~40 parts by weight: 0.3~1.5 parts by weight: 0.5~6 parts by weight: 100~150 mL.

3. The high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material according to claim 1, characterized in that, In step (2), the calcination temperature is 920~1000℃ and the time is 15~30 min; Optionally, in step (2), the drying temperature is 40~60℃ and the time is 18~24h; Optionally, in step (2), the mass ratio of powder B to acetic acid solution is 1:10~20; Optionally, in step (2), the pH of the acetic acid solution is 3 to 4.

4. The high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material according to claim 1, characterized in that, In step (3), the heating temperature is 200~350℃ and the holding time is 1~2 hours.

5. The high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material according to claim 1, characterized in that, In step (4), the mass ratio of powder D, dopamine, and water is 3~10:0.2~1.0:80~150; Optionally, in step (4), the pH of the system is adjusted to 8.4-8.6 using a buffer solution; Optionally, the buffer solution includes any one of: tris(hydroxymethyl)aminomethane hydrochloride buffer, borate buffer, phosphate buffer, and carbonate buffer; Optionally, in step (4), the stirring reaction time is 6 to 24 hours.

6. The high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material according to claim 1, characterized in that, In step (5), the powders E and Co 2+ The mass ratio of raw material to anhydrous methanol is 4~6:2~6:200~300; Optionally, in step (5), the Co 2+ The sources include at least one of cobalt nitrate, cobalt acetate, cobalt chloride, and cobalt sulfate.

7. The high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material according to claim 1, characterized in that, In step (5), the mass ratio of the mixture F to the solution G is 1:0.8~1; Optionally, in step (5), the solution G is composed of 2.2 to 6.7 parts by weight of 2-methylimidazole and 200 to 300 parts by weight of anhydrous methanol; Optionally, in step (5), the ultrasonic treatment time is 5 to 15 minutes.

8. The high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material according to any one of claims 1-7, characterized in that, The solid content of the waterborne epoxy resin is 45-55%; Optionally, the solid content of the epoxy curing agent is 35-45%; Optionally, the solid content of the aqueous styrene-acrylate emulsion is 50-60%.

9. The high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material according to any one of claims 1-7, characterized in that, The epoxy curing agent includes at least one of the following: water-based aliphatic polyamine curing agents and cashew phenol modified amine curing agents; Optionally, the coupling agent includes at least one of KH-550, KH-560, KH-570, and KH-792; Optionally, the water-reducing agent includes at least one of polycarboxylate water-reducing agent, naphthalene-based water-reducing agent, and lignin sulfonate water-reducing agent.

10. The method for preparing the high-interfacial-activity, high-strength electromagnetic shielding thin-film sprayed cement material according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Mix the cement, heavy calcium carbonate, quartz powder, titanium dioxide, attapulgite, calcium carbonate whiskers and water-reducing agent to obtain a mixed powder for later use; (2) After mixing the coupling agent with the mixing water, adjust the solution to alkaline to obtain a hydrolyzed solution for later use; (3) Mix the waterborne epoxy resin and waterborne styrene-acrylate emulsion, then add the core-shell type tetrane zinc oxide whiskers and mix well to obtain liquid system I for later use; (4) Mix the hydrolysis solution with liquid system I, then add the water-based epoxy curing agent and mix to obtain liquid system II; finally, mix liquid system II with the mixed powder to obtain the thin-spray cement material. Optionally, in step (2), alkalinity refers to pH = 8.0~8.2; Optionally, either sodium bicarbonate or ammonia solution can be used to adjust the pH.

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