Carbon fiber reinforced gypsum board with broadband electromagnetic shielding function and preparation method thereof

Abstract

The invention discloses a carbon fiber reinforced gypsum board with a broadband electromagnetic shielding function and a preparation method of the carbon fiber reinforced gypsum board. The gypsum board is prepared from the following components in percentage by mass: 74.0 to 89.0 weight percent of gypsum powder, 10.0 to 25.0 weight percent of iron-nickel oxide modified short carbon fibers, 0.3 to 0.5 weight percent of a water reducing agent and 0.3 to 0.5 weight percent of a retarder. The carbon fibers modified by the iron-nickel oxide nanoparticles are adopted to reinforce the gypsum board, a conductive network is constructed in a matrix, and magnetic eddy current loss and magnetic hysteresis loss are enhanced, so that the gypsum board can achieve high-efficiency wide-frequency-band electromagnetic shielding effectiveness while obtaining excellent mechanical properties. The gypsum board disclosed by the invention can be widely applied to internal and external walls of large-scale electronic and electrical equipment, supercomputers and electronic security facilities, and a security room with a good electromagnetic security effect can be quickly assembled and built.

Description

Technical Field

[0001] This invention relates to the field of inorganic composite materials, and in particular to a carbon fiber reinforced gypsum board with broadband electromagnetic shielding function and its preparation method. Background Technology

[0002] Gypsum is an important gelling material, and gypsum products made from gypsum gel are widely used in industrial, construction, and medical materials fields. my country has abundant gypsum mineral reserves, and its mining energy consumption is relatively low. Many industrial wastes are also used as raw materials for producing gypsum (such as phosphogypsum and fluorogypsum), thus the application fields of gypsum-based composite materials will become increasingly broad. Gypsum not only possesses advantages such as light weight, strong thermal insulation, good sound insulation, and simple molding and processing, but also has a "breathing" ability, automatically adjusting the humidity inside buildings, thereby improving the living environment to a certain extent. Gypsum materials have very distinct advantages and disadvantages. In terms of mechanical properties, it has high compressive strength, but its flexural strength and impact resistance are low. Based on an understanding of composite materials, appropriate reinforcing fibers are used as reinforcing materials for gypsum to enhance its mechanical properties. Composite materials made of fibers and gypsum improve the flexural strength, impact strength, and toughness of the gypsum matrix, and also improve its crack resistance and water resistance. Fiber-reinforced gypsum-based composites retain the original advantages of gypsum matrix while improving its shortcomings, thus enhancing its physical and mechanical properties and expanding the application range of gypsum, which is of great significance.

[0003] There are already publicly disclosed invention patents for fiber-reinforced gypsum, such as Chinese patent CN101851081A. This patent utilizes glass fiber-reinforced gypsum, whose components include gypsum powder, glass fiber, water-reducing agent, retarder, and water. The glass fiber is short, with a length of 1-3 cm, and is uniformly distributed in the gypsum product, achieving good results. Chinese patent CN102442813A utilizes a cotton stalk fiber-reinforced gypsum composite material. First, cotton stalks are roller-pressed and cut, and the cotton stalk fibers are peeled and crushed using a pulverizer to remove dust. The cotton stalk fibers are then modified by immersing them in a low-alkali solution, drained, and the additives are dissolved in water. The gypsum and modified cotton stalk fibers are then uniformly mixed, and the mixture is injected into an aqueous solution containing the additives. After thorough mixing, the mixture is poured into a mold and cured. The product has good flexural strength, low raw material cost, and a simple production process.

[0004] Simultaneously, with societal development, there are higher demands for the high performance and functionality of materials, particularly for their electromagnetic shielding properties. For instance, when electronic devices are powered on, they emit electromagnetic radiation. This radiation often interferes with or malfunctions other devices. In severe cases, such as in large substations, the transient overvoltages generated during the operation of disconnecting switches can cause electromagnetic interference in the secondary circuits, leading to serious equipment damage. Computer monitors, communication lines, mainframes, and associated output devices all emit electromagnetic radiation. If these electromagnetic waves, carrying a large amount of information, are intercepted, it can result in serious information leaks.

[0005] To reduce or prevent the hazards caused by electromagnetic radiation, it is necessary to modify the external building materials of special equipment to ensure conductivity, thereby enabling them to shield against electromagnetic waves. Therefore, modifying gypsum building materials to provide electromagnetic shielding is of great significance. Chinese patent CN102173703B discloses a method for preparing a carbon black-gypsum-based composite material, and Chinese patent CN103342533A discloses a method for preparing electromagnetically shielding gypsum board. Both methods involve adding carbon black and graphite flakes to gypsum, respectively. While the resulting gypsum boards possess some electromagnetic shielding properties, they do not reinforce the gypsum matrix. Carbon fiber is one of the most high-performance synthetic fibers with broad application prospects. Carbon fiber itself is conductive, and its fabrics can effectively block high-frequency electromagnetic waves. Chemically nickel-plating carbon fiber and using it to reinforce gypsum board not only effectively improves the mechanical properties of the gypsum board but also provides excellent electromagnetic shielding capabilities.

[0006] This invention incorporates carbon fibers modified with iron-nickel oxide nanoparticles into gypsum to form a reinforced composite gypsum board with broadband electromagnetic shielding. The short-cut carbon fibers construct a conductive network within the gypsum matrix, reducing its volume resistivity and enhancing its conductivity and dielectric properties, thereby improving the gypsum board's electromagnetic shielding performance in the high-frequency range. Furthermore, modifying the short-cut carbon fibers with iron-nickel oxide nanoparticles (a mixture of iron(III) oxide and nickel(III) oxide nanoparticles) enhances the eddy current loss and hysteresis loss of the gypsum board, thus enabling it to achieve low-frequency electromagnetic shielding performance. Ultimately, this invention allows gypsum board to achieve excellent mechanical properties while simultaneously providing highly efficient broadband electromagnetic shielding. Summary of the Invention

[0007] The problem this invention aims to solve is to overcome the shortcomings of the prior art by employing a step-by-step preparation method to produce a carbon fiber reinforced gypsum board with good strength and broadband electromagnetic shielding performance. This invention uses high-strength chopped carbon fibers as reinforcement, employs plasma surface treatment to roughen and etch the surface of the fiber cloth, and then modifies its surface with a mixture of iron oxide nanoparticles and nickel oxide nanoparticles.

[0008] The carbon fiber reinforced gypsum board with broadband electromagnetic shielding function has the following mass percentage composition: gypsum powder 74.0-89.0 wt.%, iron-nickel oxide modified short-cut carbon fiber 10.0-25.0 wt.%, water-reducing agent 0.3-0.5 wt.%, retarder 0.3-0.5 wt.%, and lubricant 0.5-1.0 wt.%.

[0009] The gypsum powder is β-type hemihydrate gypsum; the iron-nickel oxide modified short-cut carbon fiber is T300 type short-cut carbon fiber with a length of 20.0-30.00 mm, and the iron-nickel oxide used to modify the short-cut carbon fiber is a mixture of iron oxide nanoparticles and nickel oxide nanoparticles with a mass ratio of 2:1; the water-reducing agent is polycarboxylate water-reducing agent, and the retarder is diammonium pyrophosphate retarder.

[0010] The preparation method of the iron-nickel oxide modified short-cut carbon fiber is as follows: (1) A plasma etching machine was used to perform dielectric barrier discharge plasma etching on the surface of short-cut carbon fibers, and the etching depth was only 0 to 100 Å on the fiber surface. (2) The plasma-etched short carbon fibers were dispersed in a tris(hydroxymethyl)aminomethane-hydrochloride buffer solution with pH=8.4. Dopamine hydrochloride, a mixture of iron oxide nanoparticles and nickel oxide nanoparticles in a mass ratio of 2:1 were added sequentially. The mixture was mechanically stirred at room temperature. During this process, dopamine hydrochloride gradually underwent oxidative polymerization, while the iron oxide nanoparticles and nickel oxide nanoparticles adhered to the surface of the short carbon fibers due to the self-adhesive effect of polydopamine and formed a uniform magnetic nanoparticle composite layer. The reaction was stopped after stirring for 24 hours. (3) The above suspension reaction liquid is filtered, and the obtained moist iron-nickel oxide modified short carbon fiber is dried in an oven at 80°C for 24 hours to obtain dry iron-nickel oxide modified short carbon fiber.

[0011] In step (2), the amount of tris(hydroxymethyl)aminomethane-hydrochloric acid buffer added is 5.0 L of tris(hydroxymethyl)aminomethane-hydrochloric acid buffer added for every 1.0 kg of chopped carbon fiber; the amount of dopamine hydrochloride added is 150.0 g of dopamine hydrochloride added for every 1.0 kg of chopped carbon fiber; and the amount of the mixture of iron(III) oxide nanoparticles and nickel(III) oxide nanoparticles added is 50.0 g of the mixture of iron(III) oxide nanoparticles and nickel(III) oxide nanoparticles added for every 1.0 kg of chopped carbon fiber.

[0012] The method for preparing the reinforced gypsum board with broadband electromagnetic shielding function is as follows: (1) Weigh out gypsum powder, iron-nickel oxide modified short carbon fiber, water, water-reducing agent and retarder according to the proportion. The mass ratio of water to gypsum powder is controlled at 30:100. Put all raw materials into a mixing pot, let stand for 1 min, and stir 30 times with a stirring rod within 30 s to obtain a uniform slurry. (2) The slurry prepared in step (1) is injected into a mold designed according to the building size requirements and molded at room temperature for 2 hours; (3) Demold the composite gypsum board obtained in step (2), bake the demolded sample in a constant temperature oven at 40±2℃ until constant weight, then heat it to 70℃, keep it at that temperature for 1 h, take it out, put it back in a constant temperature drying oven to cool to room temperature, and then take out the sample, which is the carbon fiber reinforced gypsum board with broadband electromagnetic shielding function.

[0013] The carbon fiber reinforced gypsum board prepared by this invention has the following advantages: (1) The present invention uses building gypsum as the matrix and adopts a simple molding preparation mode. The carbon fiber reinforced gypsum board prepared not only has excellent mechanical properties, but also has excellent broadband electromagnetic shielding performance.

[0014] (2) The gypsum board of the present invention can be applied to the interior and exterior walls of large electronic and electrical equipment, large communication facilities, supercomputer rooms, and electronic security facilities, and can be quickly assembled and built with good electromagnetic security effect.

[0015] (3) The method of modifying the surface of carbon fiber with iron-nickel oxide in this invention uses polydopamine with self-adhesion as a conductive polymer, which is in situ compounded with a mixture of iron oxide nanoparticles and nickel oxide nanoparticles, resulting in good magnetization effect.

[0016] (4) The raw materials and additives used in this invention are all commercially available products with reasonable prices, which not only have low material costs, but also simple preparation processes. Detailed Implementation

[0017] The following are examples of embodiments based on the formulations provided by the technical solutions of this invention, used to further explain the invention. These embodiments enable those skilled in the art to more fully understand the invention, but they are not intended to limit the scope of protection of this invention. The term "an embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that excludes other embodiments. Example 1

[0018] A carbon fiber reinforced gypsum board with broadband electromagnetic shielding function has the following raw material mass ratio:

[0019] The specific preparation method of iron-nickel oxide modified short-cut carbon fibers is as follows: (1) The surface of 30 kg of short carbon fiber was etched by dielectric barrier discharge plasma using a plasma etching machine, and the etching depth was only 0-100 Å on the fiber surface; (2) The plasma-etched short carbon fiber was dispersed in 150.0 L of tris(hydroxymethyl)aminomethane-hydrochloride buffer (pH=8.4), and 4.5 kg of dopamine hydrochloride and 1.5 kg of iron-nickel oxide (the mass ratio of iron(III) oxide nanoparticles to nickel oxide nanoparticles was 2:1) were added sequentially. The mixture was mechanically stirred at room temperature, and the reaction was stopped after stirring for 24 hours; (3) The suspension reaction solution was filtered, and the obtained wet iron-nickel oxide modified short carbon fiber was dried in an oven at 80 °C for 24 hours to obtain dry iron-nickel oxide modified short carbon fiber.

[0020] The specific preparation method of carbon fiber reinforced gypsum board with broadband electromagnetic shielding function is as follows: (1) Weigh out gypsum powder, iron-nickel oxide modified short carbon fiber, water, water-reducing agent and retarder according to the ratio, put all raw materials into a mixing pot, let stand for 1 min, stir 30 times in 30 s with a stirring rod to obtain a uniform slurry; (2) Inject the slurry prepared in step (1) into the mold designed according to the building size requirements, and mold at room temperature for 2 h; (3) Demold the composite gypsum board obtained in step (2), bake the demolded sample in a constant temperature oven at 40±2℃ to constant weight, then heat to 70℃, keep warm for 1 h, take it out, put it back in a constant temperature drying oven to cool to room temperature, and take out the sample, which is the carbon fiber reinforced gypsum board with broadband electromagnetic shielding function. Example 2

[0021] A carbon fiber reinforced gypsum board with broadband electromagnetic shielding function has the following raw material mass ratio:

[0022] The specific preparation method of iron-nickel oxide modified short-cut carbon fibers is the same as in Example 1.

[0023] The specific preparation method of carbon fiber reinforced gypsum board with broadband electromagnetic shielding function is as follows: (1) Weigh out gypsum powder, iron-nickel oxide modified short carbon fiber, water, water-reducing agent and retarder according to the ratio, put all raw materials into a mixing pot, let stand for 1 min, stir 30 times in 30 s with a stirring rod to obtain a uniform slurry; (2) Inject the slurry prepared in step (1) into the mold designed according to the building size requirements, and mold at room temperature for 2 h; (3) Demold the composite gypsum board obtained in step (2), bake the demolded sample in a constant temperature oven at 40±2℃ to constant weight, then heat to 70℃, keep warm for 1 h, take it out, put it back in a constant temperature drying oven to cool to room temperature, and take out the sample, which is the carbon fiber reinforced gypsum board with broadband electromagnetic shielding function. Example 3

[0024] A carbon fiber reinforced gypsum board with broadband electromagnetic shielding function has the following raw material mass ratio:

[0025] The specific preparation method of iron-nickel oxide modified short-cut carbon fibers is the same as in Example 1.

[0026] The specific preparation method of carbon fiber reinforced gypsum board with broadband electromagnetic shielding function is as follows: (1) Weigh out gypsum powder, iron-nickel oxide modified short carbon fiber, water, water-reducing agent and retarder according to the ratio, put all raw materials into a mixing pot, let stand for 1 min, stir 30 times in 30 s with a stirring rod to obtain a uniform slurry; (2) Inject the slurry prepared in step (1) into the mold designed according to the building size requirements, and mold at room temperature for 2 h; (3) Demold the composite gypsum board obtained in step (2), bake the demolded sample in a constant temperature oven at 40±2℃ to constant weight, then heat to 70℃, keep warm for 1 h, take it out, put it back in a constant temperature drying oven to cool to room temperature, and take out the sample, which is the carbon fiber reinforced gypsum board with broadband electromagnetic shielding function. Example 4

[0027] A carbon fiber reinforced gypsum board with broadband electromagnetic shielding function has the following raw material mass ratio:

[0028] The specific preparation method of iron-nickel oxide modified short-cut carbon fibers is the same as in Example 1.

[0029] The specific preparation method of carbon fiber reinforced gypsum board with broadband electromagnetic shielding function is as follows: (1) Weigh out gypsum powder, iron-nickel oxide modified short carbon fiber, water, water-reducing agent and retarder according to the ratio, put all raw materials into a mixing pot, let stand for 1 min, stir 30 times in 30 s with a stirring rod to obtain a uniform slurry; (2) Inject the slurry prepared in step (1) into the mold designed according to the building size requirements, and mold at room temperature for 2 h; (3) Demold the composite gypsum board obtained in step (2), bake the demolded sample in a constant temperature oven at 40±2℃ to constant weight, then heat to 70℃, keep warm for 1 h, take it out, put it back in a constant temperature drying oven to cool to room temperature, and take out the sample, which is the carbon fiber reinforced gypsum board with broadband electromagnetic shielding function. Example 5

[0030] A carbon fiber reinforced gypsum board with broadband electromagnetic shielding function has the following raw material mass ratio:

[0031] The specific preparation method of iron-nickel oxide modified short-cut carbon fibers is the same as in Example 1.

[0032] The specific preparation method of carbon fiber reinforced gypsum board with broadband electromagnetic shielding function is as follows: (1) Weigh out gypsum powder, iron-nickel oxide modified short carbon fiber, water, water-reducing agent and retarder according to the ratio, put all raw materials into a mixing pot, let stand for 1 min, stir 30 times in 30 s with a stirring rod to obtain a uniform slurry; (2) Inject the slurry prepared in step (1) into the mold designed according to the building size requirements, and mold at room temperature for 2 h; (3) Demold the composite gypsum board obtained in step (2), bake the demolded sample in a constant temperature oven at 40±2℃ to constant weight, then heat to 70℃, keep warm for 1 h, take it out, put it back in a constant temperature drying oven to cool to room temperature, and take out the sample, which is the carbon fiber reinforced gypsum board with broadband electromagnetic shielding function. Example 6

[0033] A carbon fiber reinforced gypsum board with broadband electromagnetic shielding function has the following raw material mass ratio:

[0034] The specific preparation method of iron-nickel oxide modified short-cut carbon fibers is the same as in Example 1.

[0035] The specific preparation method of carbon fiber reinforced gypsum board with broadband electromagnetic shielding function is as follows: (1) Weigh out gypsum powder, iron-nickel oxide modified short carbon fiber, water, water-reducing agent and retarder according to the ratio, put all raw materials into a mixing pot, let stand for 1 min, stir 30 times in 30 s with a stirring rod to obtain a uniform slurry; (2) Inject the slurry prepared in step (1) into the mold designed according to the building size requirements, and mold at room temperature for 2 h; (3) Demold the composite gypsum board obtained in step (2), bake the demolded sample in a constant temperature oven at 40±2℃ to constant weight, then heat to 70℃, keep warm for 1 h, take it out, put it back in a constant temperature drying oven to cool to room temperature, and take out the sample, which is the carbon fiber reinforced gypsum board with broadband electromagnetic shielding function.

[0036] To verify the performance of the carbon fiber reinforced gypsum board with broadband electromagnetic shielding function prepared in this invention, the flexural strength and compressive strength of the gypsum board samples prepared in Examples 1-6 were tested according to GB / T 9776-2008 standard, and their electromagnetic shielding effectiveness was tested according to GB / T 12190-2006 standard, with a frequency range of 100 kHz to 1.5 GHz. All performance test results are shown in Table 1. The data in Table 1 indicate that the carbon fiber reinforced gypsum board prepared in the embodiments of this invention not only possesses excellent mechanical properties but also achieves high electromagnetic shielding effectiveness in a wide frequency range of 100 kHz to 1.5 GHz. This shielding effectiveness meets the electromagnetic shielding requirements of industrial-grade electronics.

[0037] Table 1. Properties of carbon fiber reinforced gypsum boards with broadband electromagnetic shielding prepared in Examples 1-6

[0038] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A reinforced gypsum board with broadband electromagnetic shielding function, characterized in that: The weight percentage composition of the reinforced gypsum board is as follows: gypsum powder 74.0~89.0 wt.%, iron-nickel oxide modified short-cut carbon fiber 10.0~25.0 wt.%, water-reducing agent 0.3~0.5 wt.%, and retarder 0.3~0.5 wt.%.

2. The reinforced gypsum board with broadband electromagnetic shielding function as described in claim 1, characterized in that: The gypsum powder is β-type hemihydrate gypsum; the iron-nickel oxide modified short-cut carbon fiber is T300 type short-cut carbon fiber with a length of 20.0-30.00 mm, and the iron-nickel oxide used to modify the short-cut carbon fiber is a mixture of iron oxide nanoparticles and nickel oxide nanoparticles with a mass ratio of 2:1; the water-reducing agent is polycarboxylate water-reducing agent, and the retarder is diammonium pyrophosphate retarder.

3. The reinforced gypsum board with broadband electromagnetic shielding function as described in claim 2, characterized in that: The preparation method of the iron-nickel oxide modified short-cut carbon fiber is as follows: (1) A plasma etching machine was used to perform dielectric barrier discharge plasma etching on the surface of short-cut carbon fibers, and the etching depth was only 0 to 100 Å on the fiber surface. (2) The plasma-etched short carbon fibers were dispersed in a tris(hydroxymethyl)aminomethane-hydrochloride buffer solution with pH=8.

4. Dopamine hydrochloride, a mixture of iron oxide nanoparticles and nickel oxide nanoparticles in a mass ratio of 2:1 were added sequentially. The mixture was mechanically stirred at room temperature. During this process, dopamine hydrochloride gradually underwent oxidative polymerization, while the iron oxide nanoparticles and nickel oxide nanoparticles adhered to the surface of the short carbon fibers due to the self-adhesive effect of polydopamine and formed a uniform magnetic nanoparticle composite layer. The reaction was stopped after stirring for 24 hours. (3) The above suspension reaction liquid is filtered, and the obtained moist iron-nickel oxide modified short carbon fiber is dried in an oven at 80°C for 24 hours to obtain dry iron-nickel oxide modified short carbon fiber.

4. The reinforced gypsum board with broadband electromagnetic shielding function as described in claim 3, characterized in that: In step (2), the amount of tris(hydroxymethyl)aminomethane-hydrochloric acid buffer added is 5.0 L of tris(hydroxymethyl)aminomethane-hydrochloric acid buffer added for every 1.0 kg of chopped carbon fiber; the amount of dopamine hydrochloride added is 150.0 g of dopamine hydrochloride added for every 1.0 kg of chopped carbon fiber; and the amount of the mixture of iron(III) oxide nanoparticles and nickel(III) oxide nanoparticles added is 50.0 g of the mixture of iron(III) oxide nanoparticles and nickel(III) oxide nanoparticles added for every 1.0 kg of chopped carbon fiber.

5. The method for preparing reinforced gypsum board with broadband electromagnetic shielding function as described in any one of claims 1-4, characterized in that: The method includes the following steps: (1) Weigh out gypsum powder, iron-nickel oxide modified short carbon fiber, water, water-reducing agent and retarder according to the proportion. The mass ratio of water to gypsum powder is controlled at 30:

100. Put all raw materials into a mixing pot, let stand for 1 min, and stir 30 times with a stirring rod within 30 s to obtain a uniform slurry. (2) The slurry prepared in step (1) is injected into a mold designed according to the building size requirements and molded at room temperature for 2 hours; (3) Demold the composite gypsum board obtained in step (2), bake the demolded sample in a constant temperature oven at 40±2℃ until constant weight, then heat it to 70℃, keep it at that temperature for 1 h, take it out, put it back in a constant temperature drying oven to cool to room temperature, and then take out the sample, which is the carbon fiber reinforced gypsum board with broadband electromagnetic shielding function.

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