An electrically conductive and heatable graphene glass fiber cloth and a method for preparing the same

Abstract

The present application relates to the technical field of electric heating material, and particularly relates to a graphene glass fiber cloth capable of electrically heating and a preparation method thereof. The graphene glass fiber cloth electric heating device comprises: a graphene glass fiber cloth and electrodes connected to the longitudinal edges of the graphene glass fiber cloth; the graphene glass fiber cloth comprises: a pre-deposited glass fiber cloth and a coating layer covering the surface of the pre-deposited glass fiber cloth; when the graphene glass fiber cloth electric heating device is applied with 270V direct current, the electric heating rate is greater than or equal to 85 DEG C / s; when the graphene glass fiber cloth electric heating device is applied with 150V direct current, the electric heating temperature stability value is greater than or equal to 200 DEG C, and the electric-heat radiation conversion efficiency is greater than or equal to 40%. The present application not only can maintain the flexibility of the glass fiber cloth, but also has good self-repairing effect in a high-temperature environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric heating materials, in particular to a graphene glass fiber cloth capable of electric heating and a preparation method thereof. BACKGROUND

[0002] Flexible thin film heater is a film-shaped electric heating device with bendable and foldable characteristics. As a surface heater, it has the advantages of large heat exchange area and high heat exchange power. This kind of device has the outstanding characteristics of high heating efficiency, good heat dissipation performance, large surface power density and not easy to ablate, and has broad application prospects in industrial heating, medical care, aerospace and other fields.

[0003] Graphene, as a two-dimensional carbon material, is considered as an ideal candidate for the next generation of flexible electric heating materials due to its ultra-high thermal conductivity, excellent electric-thermal conversion efficiency and extremely low resistivity. By coating a graphene layer on the surface of glass fiber through chemical vapor deposition, a graphene glass fiber cloth composite material with high electrical conductivity, flexibility and mechanical strength is prepared, which has excellent prospects for application in flexible thin film heaters.

[0004] However, in the high temperature application environment of the current flexible thin film heater, on the one hand, the graphene deposited on the surface of the glass fiber may react with oxygen in the atmosphere, leading to material structure damage and a sharp decrease in electrical conductivity; on the other hand, due to the significant difference in thermal expansion coefficient between graphene and the glass fiber substrate, thermal stress will be generated during temperature cycling, leading to interfacial peeling between the graphene layer and the substrate, forming a network of micro-cracks and defects. These defects not only reduce the mechanical strength of the material, but also significantly increase the resistance, affecting the heating uniformity and efficiency.

[0005] In the field of military defense and aerospace, there is an urgent need for lightweight, high power density flexible heating systems. Traditional metal-based electric heating systems have the disadvantages of heavy weight and high energy consumption, while existing flexible thin film heaters cannot meet the stable working requirements in extreme high temperature environments. The existing technology either sacrifices flexibility by using rigid heaters or uses flexible materials but cannot guarantee high temperature stability. This supply-demand contradiction has become a key factor restricting the upgrading of related industries. SUMMARY

[0006] The purpose of the present application is to solve the problems existing in the prior art and provide a graphene glass fiber cloth capable of electric heating and a preparation method thereof.

[0007] The graphene glass fiber cloth electric heating device comprises a graphene glass fiber cloth and electrodes connected to the longitudinal edges of the graphene glass fiber cloth; the graphene glass fiber cloth comprises a pre-deposited glass fiber cloth and a coating layer on the surface of the pre-deposited glass fiber cloth; the graphene glass fiber cloth is coated with a coating liquid on the surface of the pre-deposited glass fiber cloth, and the coating liquid is applied for the first time n The first time of applying the coating liquid is performed after the coating layer is completely dried. n +1 layer of coating, n is 1, 2 or 3; after complete drying, heat treatment is performed at 200-220℃ for 1-3min, and then the temperature is reduced to room temperature.

[0008] When a direct current of 270V is applied to the graphene glass fiber cloth electric heating device, the electric heating rate is ≥85℃ / s; when a direct current of 150V is applied to the graphene glass fiber cloth electric heating device, the electric heating temperature stability value is ≥200℃, and the electric-thermal radiation conversion efficiency is ≥40%.

[0009] Preferably, the raw materials of the coating liquid comprise, by mass fraction, silver nitrate 1-5 parts, dopamine hydrochloride 1-3 parts, single-walled carbon nanotubes 1-3 parts, bismuthate glass powder 0.1-0.5 parts, expanded graphite 0.1-0.5 parts, a dispersing agent 0.1-0.5 parts, 20-30 parts of an ethanol aqueous solution with a mass fraction of 50-60%, and 10-20 parts of water.

[0010] Preferably, the initial expansion temperature of the expanded graphite is 250℃, and the preparation method of the low-temperature expandable graphite can be found in CN1613757A (application number 2004100657397, application date 2004-11-16, publication date 2005-05-11).

[0011] Preferably, the softening point temperature of the bismuthate glass powder is 260-280℃, and the melting point temperature is 320-330℃.

[0012] Preferably, the dispersing agent is sodium dodecyl benzene sulfonate.

[0013] Preferably, the coating liquid is prepared by the following steps: silver nitrate and dopamine hydrochloride are added to an ethanol aqueous solution and stirred until uniform, the pH value of the system is adjusted to 8-9, stirring is performed for 10-15h, centrifugation and washing are performed, the temperature is reduced to -30~-40℃ for freezing for 1-3h, freeze-drying is performed, calcination is performed at 400-500℃ for 1-2h in a sealed environment, the temperature is reduced to room temperature, and crushing is performed; the product is added to water for ultrasonic dispersion for 1-2h together with single-walled carbon nanotubes, bismuthate glass powder, expanded graphite and a dispersing agent.

[0014] Preferably, the pre-deposited glass fiber cloth is prepared by the following steps: using pre-treated glass fiber as a growth substrate, vacuumizing the chemical vapor deposition system for 10-20 min, washing with argon, heating to 1050-1100℃ and introducing a second mixed gas composed of ethanol vapor, argon and hydrogen, growing for 1-2 h, and then introducing argon to reduce the temperature to room temperature.

[0015] More preferably, the flow rate of ethanol vapor is 50-70 sccm, and the flow rate ratio of ethanol vapor, argon and hydrogen is 5-7:5-10:5-10.

[0016] More preferably, the pressure of the vacuumized chemical vapor deposition system is not higher than 2.5 Pa.

[0017] More preferably, the pre-treated glass fiber cloth is prepared by the following steps: cutting the glass fiber cloth into a rectangular shape, rolling it into a cylindrical shape, placing it in the center of a quartz glass tube, and then placing it in the center of the constant temperature zone of a three-zone tube furnace, vacuumizing the tube furnace, heating to 650-700℃ and introducing a first mixed gas composed of argon and oxygen for 0.5-1 h, and cooling to room temperature.

[0018] Specifically, the thickness of the glass fiber cloth is 0.1-0.3 mm, and the gram weight per square meter is 200-300 g / m 2 .

[0019] Specifically, the tube furnace is vacuumized to a pressure of not higher than 2.5 Pa.

[0020] Specifically, the flow rate of the first mixed gas is 1200-1500 sccm, and the volume ratio of argon and oxygen is 10:1-2.

[0021] The above method for preparing a graphene glass fiber cloth electric heating device comprises the following steps: applying a coating liquid to the surface of a pre-deposited glass fiber cloth, applying the first n layer of coating liquid to the surface of the first n layer of coating liquid, n wherein the number of layers is 1, 2 or 3, the thickness of each layer of coating liquid is 0.5-2 μm, and after complete drying, the coating is heated at 200-220℃ for 1-3 min and then cooled to room temperature to obtain a graphene glass fiber cloth; and then connecting electrodes to the longitudinal edges of the graphene glass fiber cloth.

[0022] Advantages

[0023] The application utilizes chemical vapor deposition to deposit graphene on the surface of pretreated glass fiber cloth to form a high-conductive network, and the excellent electro-thermal conversion efficiency and low resistivity of graphene itself provide a basis for efficient conductive heating; the single-walled carbon nanotubes in the coating liquid have one-dimensional quantum conductive characteristics, and the carrier mobility is extremely high, which, in combination with graphene, forms a three-dimensional conductive network, significantly reduces the overall resistance, and through the compounding and deposition of nitrate and dopamine hydrochloride and calcination, carbon-doped silver nanoparticles are formed, which, in combination with the graphene conductive network, build a multi-scale conductive path, and the synergistic conductive heating effect is excellent.

[0024] The application utilizes the viscous flow of bismuthate glass powder at high temperature, and the expansion coefficient of the bismuthate glass powder is similar to that of the glass fiber substrate, so that when the temperature is high, the flow generated fills and cooperates with the volume expansion of the expanded graphite, thereby generating internal pressure to push the flow, which can effectively repair the microcracks and defects in the material, compensate for the volume shrinkage caused by thermal stress, and maintain the structural integrity.

[0025] The application can effectively enhance the stable combination of the subsequent deposition and coating layer structure on the surface of the glass fiber through pretreatment of the glass fiber cloth, not only can maintain the flexibility of the glass fiber cloth, but also can maintain the stability of the conductive heating of the material during deformation, reduce the crack propagation caused by repeated deformation, and have good self-repairing effect at high temperature, realizing the balance of flexibility, conductive heating stability and high-temperature self-repairing of the graphene glass fiber cloth, and ensuring the stable operation of the flexible thin film heater in extreme environment. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 The figure is a comparison of the electric heating rate of the graphene glass fiber cloth obtained in Examples 1-5 and the graphene glass fiber cloth obtained in Comparative Examples 1-2.

[0027] Figure 2 The figure is a comparison of the electric heating temperature stability value of the graphene glass fiber cloth obtained in Examples 1-5 and the graphene glass fiber cloth obtained in Comparative Examples 1-2.

[0028] Figure 3 The figure is a comparison of the electric-thermal radiation conversion efficiency of the graphene glass fiber cloth obtained in Examples 1-5 and the graphene glass fiber cloth obtained in Comparative Examples 1-2.

[0029] Figure 4 The figure is a comparison of the electric heating rate change rate of the graphene glass fiber cloth obtained in Examples 1-5 and Comparative Examples 1-2 after being folded 5 times at 180° under the application of 100V or 200V direct current. DETAILED DESCRIPTION

[0030] The application will be further described below in conjunction with specific embodiments.

[0031] The thickness of the glass fiber cloth used below is 0.20±0.05 mm, and the grammage is 240 g / m2. The bismuthate glass powder used below is sourced from Suzhou Qiuxian New Material Co., Ltd., adopts a Bi-Cu-Zn ternary system, and has a softening point of 260-280°C and a melting point of 320-330°C. The expanded graphite used below is prepared according to Example 31 in CN1613757A, and has an expansion volume of 45 mL / g when expanded at 250°C and an expansion volume of 105 mL / g when expanded at 300°C.

[0032] Example 1

[0033] A method for preparing a graphene glass fiber cloth electric heating device, comprising the following steps: coating a coating liquid on the surface of a pre-deposited glass fiber cloth, completely drying each layer before coating the next layer, a total of 2 layers, each layer having a thickness of 0.5 μm, after complete drying, heating to 200°C, maintaining for 1 min, and then reducing to room temperature to obtain a graphene glass fiber cloth; cutting the obtained graphene glass fiber cloth to 10 cm x 10 cm, using a copper foil conductive tape to tightly paste the warp edge of the graphene glass fiber cloth, and using solder to fix the end of the tape to a copper wire, and connecting to the two electrode columns of a power supply.

[0034] The raw materials of the coating liquid include: 1 g of silver nitrate, 1 g of dopamine hydrochloride, 1 g of single-walled carbon nanotubes, 0.1 g of bismuthate glass powder, 0.1 g of expanded graphite, and 0.1 g of sodium dodecyl benzene sulfonate.

[0035] The coating liquid is prepared by the following steps: adding silver nitrate and dopamine hydrochloride into 20 g of 50% mass fraction ethanol aqueous solution and stirring until uniform, adding 0.1 mol / L ammonia water dropwise into the system under stirring to adjust the pH value to 8, stirring for 10 h, centrifuging, washing, freezing at -30°C for 1 h, freeze-drying, calcining in a sealed muffle furnace at 400°C for 1 h, reducing to room temperature, and crushing through a 100 mesh sieve; and adding the product, single-walled carbon nanotubes, bismuthate glass powder, expanded graphite, and sodium dodecyl benzene sulfonate into 10 g of deionized water and ultrasonic dispersing for 1 h at an ultrasonic frequency of 50 kHz.

[0036] The pre-deposited glass fiber cloth is prepared by the following steps: using pretreated glass fiber as a growth substrate, placing it in the center of the constant temperature zone of a three-zone tube furnace, using a mechanical pump to reduce the pressure of the entire chemical vapor deposition system to 2 Pa and maintaining for 10 min, washing with argon gas, increasing the temperature of the system to 1050°C within 30 min, introducing a second mixed gas of 50 sccm of ethanol vapor, 50 sccm of argon, and 50 sccm of hydrogen, growing for 1 h, and then reducing to room temperature by introducing argon gas.

[0037] The pretreated glass fiber cloth is prepared by the following steps: cutting the glass fiber cloth into a rectangle, rolling into a cylinder, placing in the center of a quartz glass tube, then placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the tube furnace to 2 Pa, heating the system to 650 DEG C in 10 min, introducing a first mixed gas composed of argon and oxygen (total flow rate is 1200 sccm, volume ratio of argon to oxygen is 10:1) for 0.5 h, and cooling to room temperature.

[0038] Example 2

[0039] A graphene glass fiber cloth electric heating device preparation method comprises the following steps: coating a coating liquid on the surface of a pre-deposited glass fiber cloth, drying each layer before coating the next layer, coating a total of 4 layers, each layer having a thickness of 2 μm, heating to 220 DEG C after complete drying, maintaining for 3 min, and then cooling to room temperature to obtain a graphene glass fiber cloth; cutting the obtained graphene glass fiber cloth to 10 cm x 10 cm, using a copper foil conductive tape to adhere to the warp edge of the graphene glass fiber cloth, and using solder to fix the end of the tape to a copper wire, and connecting to the two electrode columns of a power supply.

[0040] The raw materials of the coating liquid include: silver nitrate 5 g, dopamine hydrochloride 3 g, single-walled carbon nanotubes 3 g, bismuthate glass powder 0.5 g, expanded graphite 0.5 g, and sodium dodecyl benzene sulfonate 0.5 g.

[0041] The coating liquid is prepared by the following steps: adding silver nitrate and dopamine hydrochloride to 30 g of a 60% mass fraction ethanol aqueous solution and stirring until uniform, adding concentrated ammonia water with a concentration of 0.2 mol / L to the system under stirring to adjust the pH value to 9, stirring for 15 h, centrifuging, washing, freezing at -40 DEG C for 3 h, freeze-drying, calcining in a sealed muffle furnace at 500 DEG C for 2 h, cooling to room temperature, and crushing through a 100 mesh sieve; and adding the product, single-walled carbon nanotubes, bismuthate glass powder, expanded graphite, and sodium dodecyl benzene sulfonate to 20 g of deionized water and ultrasonic dispersing for 2 h at an ultrasonic frequency of 70 kHz.

[0042] The pre-deposited glass fiber cloth is prepared by the following steps: using pretreated glass fiber as a growth substrate, placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the entire chemical vapor deposition system to 2.4 Pa and maintaining for 20 min, washing with argon, heating the system to 1100 DEG C in 60 min, introducing a second mixed gas composed of 70 sccm of ethanol vapor, 100 sccm of argon, and 100 sccm of hydrogen, growing for 2 h, and then introducing argon to cool to room temperature.

[0043] The pretreated glass fiber cloth is prepared by the following steps: cutting the glass fiber cloth into a rectangle, rolling into a cylinder, placing in the center of a quartz glass tube, then placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the tube furnace to 2.3 Pa, heating the system to 700 ℃ in 20 min, introducing a first mixed gas composed of argon and oxygen (total flow rate is 1500 sccm, volume ratio of argon to oxygen is 5:1) for 1 h, and cooling to room temperature.

[0044] Example 3

[0045] A graphene glass fiber cloth electric heating device preparation method comprises the following steps: coating a coating liquid on the surface of a pre-deposited glass fiber cloth, drying each layer completely before coating the next layer, a total of 3 layers, each layer is 1 μm thick, after complete drying, heating to 205 ℃, holding for 2.5 min, and then cooling to room temperature to obtain a graphene glass fiber cloth; cutting the obtained graphene glass fiber cloth to 10 cm x 10 cm, using a copper foil conductive tape to stick to the warp edge of the graphene glass fiber cloth, and using solder to fix the copper wire at one end of the tape and connect to the two electrode columns of a power supply.

[0046] The raw materials of the coating liquid include: 2 g of silver nitrate, 2.5 g of dopamine hydrochloride, 1.5 g of single-walled carbon nanotubes, 0.4 g of bismuthate glass powder, 0.2 g of expanded graphite, and 0.4 g of sodium dodecyl benzene sulfonate.

[0047] The coating liquid is prepared by the following steps: adding silver nitrate and dopamine hydrochloride into 22 g of 58% mass fraction ethanol aqueous solution and stirring until uniform, adding 0.12 mol / L ammonia water dropwise into the system under stirring to adjust the pH value to 8.5, stirring for 13 h, centrifuging, washing, freezing at-33 ℃ for 2.5 h, freeze-drying, calcining in a sealed muffle furnace for 80 min, the calcining temperature is 480 ℃, and then cooling to room temperature and crushing through a 100 mesh sieve; adding the product, single-walled carbon nanotubes, bismuthate glass powder, expanded graphite, and sodium dodecyl benzene sulfonate into 12 g of deionized water and ultrasonic dispersing for 100 min, the ultrasonic frequency is 55 kHz.

[0048] The pre-deposited glass fiber cloth is prepared by the following steps: using pretreated glass fiber as a growth substrate, placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the entire chemical vapor deposition system to 1 Pa and maintaining for 18 min, washing with argon, heating the system to 1090 ℃ in 40 min, introducing a second mixed gas composed of 55 sccm of ethanol vapor, 90 sccm of argon, and 70 sccm of hydrogen, growing for 100 min, and then introducing argon to cool to room temperature.

[0049] The pretreated glass fiber cloth is prepared by the following steps: cutting the glass fiber cloth into a rectangle, rolling into a cylinder, placing in the center of a quartz glass tube, then placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the tube furnace to 1 Pa, heating the system to 690 ℃ in 12 min, introducing a first mixed gas composed of argon and oxygen (total flow rate of 1300 sccm, volume ratio of argon to oxygen of 5:0.9) for 40 min, and cooling to room temperature.

[0050] Example 4

[0051] A graphene glass fiber cloth electric heating device preparation method comprises the following steps: coating a coating liquid on the surface of a pre-deposited glass fiber cloth, drying each layer completely before coating the next layer, a total of 3 layers, each layer having a thickness of 1 μm, heating to 215 ℃ after complete drying, maintaining for 1.5 min, and then cooling to room temperature to obtain a graphene glass fiber cloth; cutting the obtained graphene glass fiber cloth to 10 cm x 10 cm, using a copper foil conductive tape to adhere to the warp edge of the graphene glass fiber cloth, and using solder to fix the copper wire at one end of the tape and connect to the two electrode columns of a power supply.

[0052] The raw materials of the coating liquid include: silver nitrate 4 g, dopamine hydrochloride 1.5 g, single-walled carbon nanotubes 2.5 g, bismuthate glass powder 0.2 g, expanded graphite 0.4 g, and sodium dodecyl benzene sulfonate 0.2 g.

[0053] The coating liquid is prepared by the following steps: adding silver nitrate and dopamine hydrochloride to 28 g of a 52% mass fraction ethanol aqueous solution and stirring until uniform, adding concentrated ammonia water with a concentration of 0.18 mol / L to the system under stirring to adjust the pH value to 8.5, stirring for 11 h, centrifuging, washing, freezing at -37 ℃ for 1.5 h, freeze-drying, calcining in a sealed muffle furnace for 100 min at a calcining temperature of 420 ℃, and then cooling to room temperature and crushing through a 100 mesh sieve; and adding the product, single-walled carbon nanotubes, bismuthate glass powder, expanded graphite, and sodium dodecyl benzene sulfonate to 18 g of deionized water and ultrasonic dispersing for 80 min at an ultrasonic frequency of 65 kHz.

[0054] The pre-deposited glass fiber cloth is prepared by the following steps: using pretreated glass fiber as a growth substrate, placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the entire chemical vapor deposition system to 1 Pa, maintaining for 12 min, introducing argon gas for washing, heating the system to 1070 ℃ in 50 min, introducing a second mixed gas composed of 65 sccm of ethanol vapor, 70 sccm of argon, and 90 sccm of hydrogen, growing for 80 min, and then introducing argon to reduce to room temperature.

[0055] The pretreated glass fiber cloth is prepared by the following steps: cutting the glass fiber cloth into a rectangle, rolling into a cylinder, placing in the center of a quartz glass tube, then placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the tube furnace to 1 Pa, heating the system to 670 DEG C in 18 min, introducing a first mixed gas composed of argon and oxygen (total flow rate of 1400 sccm, volume ratio of argon to oxygen of 5:0.6) for 50 min, and cooling to room temperature.

[0056] Example 5

[0057] A graphene glass fiber cloth electric heating device preparation method comprises the following steps: coating a coating liquid on the surface of a pre-deposited glass fiber cloth, drying each layer before coating the next layer, coating a total of 3 layers, each layer having a thickness of 1 μm, heating to 210 DEG C after complete drying, maintaining the temperature for 2 min, and then cooling to room temperature to obtain a graphene glass fiber cloth; cutting the obtained graphene glass fiber cloth to 10 cm x 10 cm, using a copper foil conductive tape to adhere to the warp edge of the graphene glass fiber cloth, and using solder to fix the copper wire at one end of the tape and connect to the two electrode columns of a power supply.

[0058] The raw materials of the coating liquid include: 3 g of silver nitrate, 2 g of dopamine hydrochloride, 2 g of single-walled carbon nanotubes, 0.3 g of bismuthate glass powder, 0.3 g of expanded graphite, and 0.3 g of sodium dodecyl benzene sulfonate.

[0059] The coating liquid is prepared by the following steps: adding silver nitrate and dopamine hydrochloride to 25 g of a 55% mass fraction ethanol aqueous solution and stirring until uniform, adding concentrated ammonia water with a concentration of 0.15 mol / L to the system under stirring to adjust the pH value to 8.5, stirring for 12 h, centrifuging, washing, freezing at -35 DEG C for 2 h, freeze-drying, calcining in a sealed muffle furnace for 60 min at a calcining temperature of 450 DEG C, and then cooling to room temperature and crushing through a 100 mesh sieve; and adding the product, single-walled carbon nanotubes, bismuthate glass powder, expanded graphite, and sodium dodecyl benzene sulfonate to 15 g of deionized water and ultrasonic dispersing for 90 min at an ultrasonic frequency of 60 kHz.

[0060] The pre-deposited glass fiber cloth is prepared by the following steps: using pretreated glass fiber as a growth substrate, placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the entire chemical vapor deposition system to 1 Pa and maintaining for 15 min, washing with argon, heating the system to 1080 DEG C in 45 min, introducing a second mixed gas composed of 60 sccm of ethanol vapor, 80 sccm of argon, and 80 sccm of hydrogen, growing for 90 min, and then introducing argon to reduce the temperature to room temperature.

[0061] The pretreated glass fiber cloth is prepared by the following steps: cutting the glass fiber cloth into a rectangle, rolling into a cylinder, placing in the center of a quartz glass tube, then placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the tube furnace to 1 Pa, heating the system to 680℃ in 15 min, introducing a first mixed gas composed of argon and oxygen (total flow rate of 1350 sccm, volume ratio of argon to oxygen of 2:0.3) for 45 min, and cooling to room temperature.

[0062] Comparative Example 1

[0063] A method for preparing a graphene glass fiber cloth electric heating device, comprising the following steps: coating a coating liquid on the surface of a pre-deposited glass fiber cloth, drying each layer completely before coating the next layer, a total of 3 layers, each layer having a thickness of 1 μm, heating to 210℃ after complete drying, maintaining for 2 min, and then cooling to room temperature to obtain a graphene glass fiber cloth; cutting the obtained graphene glass fiber cloth to 10 cm x 10 cm, using a copper foil conductive tape to adhere to the warp edge of the graphene glass fiber cloth, and using solder to fix the end of the tape to a copper wire, and connecting to the two electrode columns of a power supply.

[0064] The raw materials of the coating liquid include: silver nitrate 3 g, dopamine hydrochloride 2 g, single-walled carbon nanotubes 2 g, expanded graphite 0.6 g, and sodium dodecyl benzene sulfonate 0.3 g.

[0065] The coating liquid is prepared by the following steps: adding silver nitrate and dopamine hydrochloride to 25 g of a 55% mass fraction ethanol aqueous solution and stirring until uniform, adding concentrated ammonia water with a concentration of 0.15 mol / L to the solution while stirring to adjust the pH value to 8.5, stirring for 12 h, centrifuging, washing, freezing at -35℃ for 2 h, freeze-drying, calcining in a sealed muffle furnace for 60 min at a calcining temperature of 450℃, and then cooling to room temperature and crushing through a 100 mesh sieve; and adding the product, single-walled carbon nanotubes, expanded graphite, and sodium dodecyl benzene sulfonate to 15 g of deionized water and ultrasonic dispersing for 90 min at an ultrasonic frequency of 60 kHz.

[0066] The pre-deposited glass fiber cloth is prepared by the following steps: using pretreated glass fiber as a growth substrate, placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the entire chemical vapor deposition system to 1 Pa, maintaining for 15 min, washing with argon, heating the system to 1080℃ in 45 min, introducing a second mixed gas composed of 60 sccm of ethanol vapor, 80 sccm of argon, and 80 sccm of hydrogen, and growing for 90 min, and then introducing argon to reduce to room temperature.

[0067] The pretreated glass fiber cloth is prepared by the following steps: cutting the glass fiber cloth into a rectangle, rolling into a cylinder, placing in the center of a quartz glass tube, then placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the tube furnace to 1 Pa, heating the system to 680℃ in 15 min, introducing a first mixed gas composed of argon and oxygen (total flow rate of 1350 sccm, volume ratio of argon to oxygen of 2:0.3) for 45 min, and cooling to room temperature.

[0068] Comparative Example 2

[0069] A method for preparing a graphene glass fiber cloth electric heating device, comprising the following steps: coating a coating liquid on the surface of a pre-deposited glass fiber cloth, drying each layer completely before coating the next layer, a total of 3 layers, each layer having a thickness of 1 μm, heating to 210℃ after complete drying, maintaining for 2 min, and then cooling to room temperature to obtain a graphene glass fiber cloth; cutting the obtained graphene glass fiber cloth to 10 cm x 10 cm, using a copper foil conductive tape to adhere to the warp edge of the graphene glass fiber cloth, and using solder to fix the end of the tape to a copper wire, and connecting to the two electrode columns of a power supply.

[0070] The raw materials of the coating liquid include: silver nitrate 3 g, dopamine hydrochloride 2 g, single-walled carbon nanotubes 2 g, bismuthate glass powder 0.6 g, and sodium dodecyl benzene sulfonate 0.3 g.

[0071] The coating liquid is prepared by the following steps: adding silver nitrate and dopamine hydrochloride to 25 g of a 55% mass fraction ethanol aqueous solution and stirring until uniform, adding concentrated ammonia water with a concentration of 0.15 mol / L to the solution while stirring to adjust the pH value to 8.5, stirring for 12 h, centrifuging, washing, freezing at -35℃ for 2 h, freeze-drying, calcining in a sealed muffle furnace for 60 min at a calcining temperature of 450℃, and then cooling to room temperature and crushing through a 100 mesh sieve; and adding the product, single-walled carbon nanotubes, bismuthate glass powder, and sodium dodecyl benzene sulfonate to 15 g of deionized water and ultrasonic dispersing for 90 min at an ultrasonic frequency of 60 kHz.

[0072] The pre-deposited glass fiber cloth is prepared by the following steps: using pretreated glass fiber as a growth substrate, placing in the center of a constant temperature zone of a three-zone tube furnace, using a mechanical pump to draw the pressure in the entire chemical vapor deposition system to 1 Pa, maintaining for 15 min, washing with argon, heating the system to 1080℃ in 45 min, introducing a second mixed gas composed of 60 sccm of ethanol vapor, 80 sccm of argon, and 80 sccm of hydrogen, growing for 90 min, and then introducing argon to reduce the temperature to room temperature.

[0073] The above-mentioned pretreated glass fiber cloth is prepared by the following steps: the glass fiber cloth is cut into rectangles, rolled into a cylindrical shape, placed in the center of a quartz glass tube, and then placed in the center of the constant temperature zone of a three-temperature zone tube furnace. The pressure inside the tube furnace is evacuated to 1 Pa using a mechanical pump, and the system temperature is raised to 680°C in 15 min. A first mixed gas composed of argon and oxygen (total flow rate of 1350 sccm, volume ratio of argon to oxygen of 2:0.3) is introduced for 45 min and then cooled to room temperature.

[0074] Experimental Example 1

[0075] A DC voltage of 270V was applied to the graphene glass fiber cloth electric heating devices obtained in Examples 1-5 and Comparative Examples 1-2. An infrared thermal imager was used to vertically align with the sample surface, and the voltage and DC current were set to perform electric heating analysis and calculate the electric heating rate.

[0076] like Figure 1 As shown, the electric heating rate of the graphene glass fiber cloth electric heating device obtained in Examples 1-5 is faster than that of Comparative Examples 1-2; and the electric heating rate of the graphene glass fiber cloth electric heating device obtained in Example 5 is the fastest, which is significantly better than that of Comparative Examples 1-2.

[0077] Experimental Example 2

[0078] Apply a 150V DC voltage to the graphene glass fiber cloth electric heating devices obtained in Examples 1-5 and Comparative Examples 1-2, and continue heating for 3-5 seconds until the temperature stabilizes. Record the stable temperature values ​​for each group of electric heating devices.

[0079] like Figure 2 As shown, the electric heating temperature stability values ​​of the graphene glass fiber cloth electric heating devices obtained in Examples 1-5 are significantly higher than those in Comparative Examples 1-2; while the electric heating temperature stability value of the graphene glass fiber cloth electric heating device obtained in Example 5 is the highest.

[0080] Experimental Example 3

[0081] Referring to the thermal imaging measurement method in GB / T 7287-2008 "Test Methods for Infrared Radiation Heaters", an infrared thermal imager was placed 50 cm away from the sample to measure the temperature of the graphene glass fiber cloth electric heating devices obtained in Examples 1-5 and Comparative Examples 1-2 under a DC voltage of 150V, and the electro-thermal radiation conversion efficiency was calculated.

[0082]

[0083] In the formula, η The electro-thermal radiation conversion efficiency is expressed as %; σ is the Stefan-Boltzmann constant, 5.67 × 10⁻⁶. -8W / (m 2 ·K 4 ); S is the sample area, in m 2 ; T t is the average radiant temperature, in K; T0 is the ambient temperature, in K; P is the measured electrical power, in W.

[0084] As Figure 3 shown, the electrical-thermal radiation conversion efficiency of the graphene glass fiber cloth electric heating device obtained in Examples 1-5 is higher than that of Comparative Examples 1-2; and the electrical-thermal radiation conversion efficiency of the graphene glass fiber cloth electric heating device obtained in Example 5 is the highest, which is significantly better than that of Comparative Examples 1-2.

[0085] Test Example 4

[0086] A 200V direct current voltage was applied to the graphene glass fiber cloth electric heating devices obtained in Examples 1-5 and the graphene glass fiber cloth electric heating devices obtained in Comparative Examples 1-2, and the heating was continued for 3-5s, and it was found that the stable electric heating temperature values of each group could reach 270℃.

[0087] A 100V direct current voltage was applied to the graphene glass fiber cloth electric heating device obtained in Example 5, and the heating was continued for 3-5s, and it was found that the stable electric heating temperature value thereof was about 160℃.

[0088] New graphene glass fiber cloth electric heating devices were taken from each group, and the direct current voltage was adjusted to 200V according to the above-mentioned Test Example 1 step, and the original electric heating rate was calculated. Subsequently, each group of graphene glass fiber cloth electric heating devices was folded by 180° for 5 times, and the above-mentioned electric heating rate detection step was performed again, and the electric heating rate after 180° folding was calculated. According to the original electric heating rate and the electric heating rate after 180° folding, the electric heating rate change rate was calculated to represent the self-repairing ability of each group of graphene glass fiber cloth electric heating devices.

[0089] New graphene glass fiber cloth electric heating devices obtained in Example 5 were taken, and the direct current voltage was adjusted to 100V according to the above-mentioned Test Example 1 step, and the original electric heating rate was calculated. Subsequently, it was folded by 180° for 5 times, and the above-mentioned electric heating rate detection step was performed again, and the electric heating rate after 180° folding was calculated. According to the original electric heating rate and the electric heating rate after 180° folding, the electric heating rate change rate was calculated.

[0090] The electric heating rate change rate = (original electric heating rate - electric heating rate after 180° folding) ÷ original electric heating rate × 100%.

[0091] As Figure 4As shown, by comparing the change rates of the electrical heating rate of the graphene glass fiber cloth electrical heating device obtained in Example 5 at different direct current voltages, it can be seen that the 180° repeated folding causes the wrinkles and cracks on the surface of the graphene glass fiber cloth, resulting in the increase of the resistance and the significant increase of the change rate of the electrical heating rate. When the graphene glass fiber cloth electrical heating devices obtained in Examples 1-5 and Comparative Examples 1-2 are applied with a direct current of 200V, the change rate of the electrical heating rate of the graphene glass fiber cloth electrical heating device (200V) obtained in Examples 1-5 is significantly smaller than that of Comparative Examples 1-2; and the change rate of the electrical heating rate of the graphene glass fiber cloth electrical heating device (200V) obtained in Example 5 is the smallest, which confirms that the graphene glass fiber cloth electrical heating device obtained in the application has excellent self-repairing effect after being treated at 270°C.

[0092] The reason for the above results is that: the application utilizes chemical vapor deposition to deposit graphene on the surface of the pretreated glass fiber cloth to form a high-conductive network, and the excellent electro-thermal conversion efficiency and low resistivity characteristics of graphene provide a basis for high-efficiency conductive heating; and the single-walled carbon nanotubes in the coating liquid have one-dimensional quantum conductive characteristics, and have extremely high carrier mobility, which forms a three-dimensional conductive network with graphene, significantly reduces the overall resistance, and utilizes the nitrate and hydrochloric acid dopamine to form carbon-doped silver nanoparticles through polymerization deposition and calcination, which cooperates with the graphene conductive network to build a multi-scale conductive path, and has excellent synergistic conductive heating effect.

[0093] And the application utilizes the viscous flow of bismuthate glass powder to fill and cooperate with the volume expansion of the expanded graphite to generate internal pressure to effectively repair the micro-cracks and defects in the material, and compensate for the volume shrinkage caused by thermal stress to maintain the structural integrity.

[0094] The above is only the preferred specific embodiment of the application, but the protection scope of the application is not limited thereto, and any person skilled in the art can make equivalent substitutions or changes to the technical solutions and inventive concepts of the application within the technical range disclosed by the application, which should be covered within the protection scope of the application.

Claims

1. A graphene glass fiber cloth electric heating device, characterized in that, include: Graphene glass fiber cloth and electrodes connected to the radial edges of the graphene glass fiber cloth; The graphene glass fiber cloth includes: a pre-deposited glass fiber cloth and a coating applied to the surface of the pre-deposited glass fiber cloth; The pre-deposited glass fiber cloth is prepared by the following steps: using pretreated glass fiber cloth as the growth substrate, the chemical vapor deposition system is evacuated and kept for 10-20 minutes, argon gas is introduced for washing, the temperature is raised to 1050-1100℃ and a second mixed gas composed of ethanol vapor, argon and hydrogen is introduced, the growth is carried out for 1-2 hours, and then argon gas is introduced to cool down to room temperature. The graphene glass fiber cloth is coated with a coating liquid onto the surface of a pre-deposited glass fiber cloth. After the nth coating layer is completely dry, the (n+1)th coating layer is applied, where n is 1, 2, or 3. After complete drying, it is heat-treated at 200-220℃ for 1-3 minutes and then cooled to room temperature to obtain the final product. The coating solution is prepared by the following steps: silver nitrate and dopamine hydrochloride are added to an ethanol aqueous solution and stirred until homogeneous. The pH of the system is adjusted to 8-9, and the mixture is stirred for 10-15 hours. The mixture is then centrifuged, washed, cooled to -30 to -40°C and frozen for 1-3 hours. The mixture is then freeze-dried, calcined in a sealed environment at 400-500°C for 1-2 hours, cooled to room temperature, and pulverized. The product, along with single-walled carbon nanotubes, bismuthate glass powder, expanded graphite, and a dispersant, is added to water and ultrasonically dispersed for 1-2 hours. When the graphene glass fiber cloth electric heating device is subjected to 270V DC power, the electric heating rate is ≥85℃ / s; when the graphene glass fiber cloth electric heating device is subjected to 150V DC power, the electric heating temperature stability is ≥200℃, and the electro-thermal radiation conversion efficiency is ≥40%.

2. The graphene glass fiber cloth electric heating device according to claim 1, characterized in that, The raw materials of the coating solution, by mass, include: 1-5 parts silver nitrate, 1-3 parts dopamine hydrochloride, 1-3 parts single-walled carbon nanotubes, 0.1-0.5 parts bismuthate glass powder, 0.1-0.5 parts expanded graphite, 0.1-0.5 parts dispersant, 20-30 parts of an ethanol aqueous solution with a mass fraction of 50-60%, and 10-20 parts water.

3. The graphene glass fiber cloth electric heating device according to claim 1, characterized in that, The flow rate of ethanol vapor is 50-70 sccm, and the flow ratio of ethanol vapor, argon, and hydrogen is 5-7:5-10:5-10.

4. The graphene glass fiber cloth electric heating device according to claim 1, characterized in that, The vacuum pressure of the chemical vapor deposition system should not exceed 2.5 Pa.

5. The graphene glass fiber cloth electric heating device according to claim 1, characterized in that, The pretreated glass fiber cloth is prepared by the following steps: the glass fiber cloth is cut into rectangles, rolled into a cylindrical shape, placed in the center of a quartz glass tube, and then placed in the center of the constant temperature zone of a three-temperature zone tube furnace. The tube furnace is evacuated, heated to 650-700℃, and treated with a first mixed gas composed of argon and oxygen for 0.5-1 hours, and then cooled to room temperature.

6. The graphene glass fiber cloth electric heating device according to claim 5, characterized in that, The fiberglass cloth has a thickness of 0.1-0.3 mm and a weight of 200-300 g / m². 2 .

7. The graphene glass fiber cloth electric heating device according to claim 5, characterized in that, The flow rate of the first mixed gas is 1200-1500 sccm, and the volume ratio of argon to oxygen is 10:1-2.

8. A method for preparing a graphene glass fiber cloth electric heating device as described in any one of claims 1-7, characterized in that, The process includes the following steps: coating the coating solution onto the surface of the pre-deposited glass fiber cloth; after the nth coating layer is completely dry, the (n+1)th coating layer is applied, where n is 1, 2, or 3; the thickness of each coating layer is 0.5-2 μm; after complete drying, heat treatment is performed at 200-220℃ for 1-3 minutes, and then cooled to room temperature to obtain the graphene glass fiber cloth; then, the electrode is connected to the warp edge of the graphene glass fiber cloth.

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