Graphene microcrystal far infrared electric heating plate and preparation method thereof

Abstract

The invention discloses a graphene microcrystalline far-infrared electric heating plate and a preparation method thereof. The graphene microcrystalline far-infrared electric heating plate comprises a base layer, a functional layer arranged on the base layer and a microcrystalline glass layer covering the functional layer, the base layer is formed by compounding silicon nitride ceramic and boron carbide short fibers, the volume fraction of the boron carbide short fibers is 15%-20%, the bending strength is larger than or equal to 800 MPa, and the heat conductivity coefficient is 80-100 W / (m.K); and the functional layer comprises an electric conduction and heat conduction layer and a far infrared radiation layer. The graphene microcrystal far infrared electric heating plate adopts a multi-layer composite structure, a functional main body is formed by compounding a graphene nanosheet and a hexagonal boron nitride nanotube, the square resistance is less than or equal to 100 omega / square, the heat conductivity coefficient reaches 500-800 W / (m.K), 30-second rapid thermal response is realized, and the heating response speed is increased by more than 90% compared with that of a traditional resistance wire; the far infrared radiation layer is compounded with nano titanium dioxide through tourmaline, and can stably emit far infrared rays of 8-14 microns, the emissivity is greater than or equal to 88% and is far higher than that of a common material and is less than 70%, and the blood circulation and metabolism of a human body are effectively promoted.

Description

Technical Field

[0001] The invention belongs to the technical field of physiotherapy electric heating plates and relates to a graphene microcrystal far-infrared electric heating plate and a preparation method thereof. Background Art

[0002] As people's health awareness increases, market demand for heating therapy devices, both for home and medical use, is growing as tools to promote blood circulation and relieve fatigue. However, current mainstream therapy devices face numerous technical bottlenecks, making it difficult to meet users' demands for efficient, safe, and comfortable therapy.

[0003] Most existing heating therapy devices only provide basic heat and lack the far-infrared radiation that is crucial for human health. Far-infrared radiation can penetrate deep into the human subcutaneous tissue, resonating with cells and promoting blood circulation and metabolism. It is significantly effective in relieving muscle soreness and improving joint inflammation. However, the common heating materials used in traditional devices have a low far-infrared emissivity, typically less than 70%, and the emission wavelength is poorly matched with the human body's optimal absorption band (6-12μm), making it difficult to fully utilize the therapeutic benefits of far-infrared radiation. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A graphene microcrystal far-infrared electric heating plate, comprising: a base layer, a functional layer arranged on the base layer, and a microcrystalline glass layer covering the functional layer;

[0006] The base layer is composed of silicon nitride ceramics and boron carbide short fibers. The volume fraction of boron carbide short fibers is 15%-20%, the flexural strength is ≥800MPa, and the thermal conductivity is 80-100W / (m·K);

[0007] Functional layer: includes an electrically conductive and thermally conductive layer and a far-infrared radiation layer; the electrically conductive and thermally conductive layer is a composite of graphene nanosheets and hexagonal boron nitride nanotubes, and has both electrical heating and thermal conductivity functions; power electrodes are provided on both sides of the functional layer, and both sides of the electrically conductive and thermally conductive layer are electrically connected to the power electrodes;

[0008] The far-infrared radiation layer is a composite of tourmaline powder and nano-titanium dioxide, with a tourmaline content of 30%-40%, which can stably emit far-infrared rays with a wavelength of 8-14μm;

[0009] The glass-ceramic layer is a rare earth doped glass-ceramic structure, and the rare earth ions are "Ce 3+ ” or “La 3+ ", doping concentration 0.5%-1.0%, transmittance ≥85%, the surface is nano-level frosted to form a skin-friendly texture.

[0010] As a further solution of the present invention: the nano-titanium dioxide in the far-infrared radiation layer has a particle size of 20-30 nm and is compounded with tourmaline by a sol-gel method, and a silane coupling agent is grafted on the surface of the nano-titanium dioxide to enhance dispersibility.

[0011] As a further solution of the present invention: the nanocrystalline phase in the rare earth-doped microcrystalline glass has a grain size of 50-100 nm and is prepared by a gradient temperature rise annealing process with a heating rate of 5°C / min and kept at 600°C for 2h to promote full growth of the crystal phase.

[0012] As a further solution of the present invention: in the conductive and thermal conductive layer, the number of graphene nanosheets is 3-5 layers, the lateral size is 2-5 μm, and the aspect ratio of the hexagonal boron nitride nanotubes is 10-20, and the two are uniformly mixed through an ultrasonic dispersion process.

[0013] A method for preparing a graphene microcrystal far-infrared electric heating plate, used for preparing the above-mentioned graphene microcrystal far-infrared electric heating plate, comprises the following steps:

[0014] Preparation of the base layer: Silicon nitride powder and boron carbide short fibers were dry-pressed into a mold and then sintered at 1650°C for 3 hours in a nitrogen atmosphere.

[0015] Functional interlayer construction: Graphene nanosheets, hexagonal boron nitride nanotubes, and an organic solvent are first mixed and ultrasonically dispersed for 2 hours to prepare a conductive and thermally conductive layer slurry with a solid content of 6%. This is then formed through a coating process. Tourmaline powder, nano-titanium dioxide, a binder, and a solvent are then mixed and a far-infrared radiation layer slurry is prepared through a sol-gel method. This is then applied to the surface of the conductive and thermally conductive layer.

[0016] Glass-ceramic layer sealing: hot-press and sinter the rare earth-doped glass-ceramic powder and the functional interlayer at a sintering temperature of 850°C and a pressure of 10 MPa for 1 hour;

[0017] Surface treatment: The glass-ceramic layer of the composite panel is nano-sandblasted with a particle size of 50-100nm to form a skin-friendly texture, followed by chemical polishing to achieve a surface roughness Ra of 0.2-0.5μm.

[0018] The beneficial effects of the present invention are as follows: the graphene microcrystal far-infrared electric heating plate adopts a multi-layer composite structure, the functional body is composed of graphene nanosheets and hexagonal boron nitride nanotubes, and the square resistance is ≤100Ω / □ The thermal conductivity coefficient reaches 500-800W / (m·K), achieving a rapid thermal response of 30 seconds, which is more than 90% faster than the heating response speed of traditional resistance wire; the far-infrared radiation layer is compounded by tourmaline and nano-titanium dioxide, stably emitting 8-14μm far-infrared rays, with an emissivity of ≥88%, which is much higher than the <70% of ordinary materials, effectively promoting human blood circulation and metabolism. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. It should be understood that this application is not limited to the example embodiments disclosed herein. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0021] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0022] In the embodiments of the present invention, unless otherwise expressly specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0023] like Figure 1 As shown, the graphene microcrystal far-infrared electric heating plate is composed of: a base layer 2, a functional layer 4 arranged on the base layer 2, and a microcrystalline glass layer 1 covering the functional layer 4;

[0024] The base layer 2, serving as the main supporting structural layer, is composed of a composite of silicon nitride ceramic and boron carbide short fibers. The volume fraction of the boron carbide short fibers is controlled at 15%-20%, giving the base layer 2 excellent mechanical properties, a flexural strength ≥800 MPa, and a thermal conductivity coefficient of 80-100 W / (m·K), which can better extend the service life of the heating plate.

[0025] Functional layer 4 is the main working structural layer, including an electrical and thermal conductive layer and a far-infrared radiation layer;

[0026] The conductive and thermally conductive layer is composed of a composite of graphene nanosheets and hexagonal boron nitride nanotubes, which are uniformly mixed through an ultrasonic dispersion process. The graphene nanosheets have 3-5 layers and a lateral size of 2-5μm, while the hexagonal boron nitride nanotubes have an aspect ratio of 10-20. This structural design ensures that the conductive and thermally conductive layer has excellent electrical and thermal conductivity.

[0027] Graphene nanosheets and hexagonal boron nitride nanotubes are compounded in a mass ratio of 8:2 to form a three-dimensional conductive and thermal network with a sheet resistance of ≤100Ω / □ The thermal conductivity is as high as 500-800W / (m·K), achieving a rapid thermal response effect of 30 seconds. It can quickly transfer heat to various parts of the chamber, greatly shortening the warm-up time before physical therapy.

[0028] At the same time, power electrodes 3 are provided on both sides of the conductive and thermal conductive layer. For example, silver paste printed electrodes are used and connected to the temperature control module through wires to support precise temperature adjustment of 0-50°C. Users can flexibly adjust the temperature according to their own needs to improve the comfort and pertinence of physical therapy.

[0029] Far-infrared radiation layer: The far-infrared radiation layer is composed of a composite of tourmaline powder and nano-titanium dioxide, with a tourmaline content of 30%-40%. To enhance the dispersion uniformity and interfacial bonding between the nano-titanium dioxide and tourmaline, the nano-titanium dioxide particle size is controlled at 20-30nm. It is compounded with tourmaline via a sol-gel method, and a silane coupling agent is grafted onto the surface of the nano-titanium dioxide. This composite structure stably emits far-infrared light with a wavelength of 8-14μm, with an emissivity of ≥88%. Far-infrared light in this wavelength band is similar to the vibration frequency of human cells, effectively promoting blood circulation and metabolism, enhancing metabolism, relieving fatigue, and improving physical function, significantly enhancing the therapeutic effect.

[0030] The glass-ceramic layer 1 is used as the surface protection structure, and adopts rare earth doped glass-ceramic structure, and the rare earth ions are "Ce 3 + ” or “La 3+ ", with a doping concentration of 0.5%-1.0%. It is prepared through a gradient temperature annealing process with a heating rate of 5℃ / min and a heat preservation at 600℃ for 2h to promote the full growth of the crystal phase and form a nanocrystalline phase of 50-100nm, so that the transmittance of the microcrystalline glass layer 1 is ≥85%. The surface of the microcrystalline glass layer 1 is nano-frosted to form a skin-friendly texture with a roughness of Ra0.2-0.5μm, which feels delicate and soft, reducing friction stimulation when in contact with human skin and improving user comfort.

[0031] At the same time, rare earth doping enhances the ultraviolet shielding ability and chemical stability of the microcrystalline glass layer 1. The nanocrystalline phase structure makes the microcrystalline glass layer 1 have a hardness of 6-7H, which is wear-resistant and not easy to scratch, effectively protecting the internal functional layer 4 and extending the service life of the electric heating plate.

[0032] The comparative parameter structure of the graphene microcrystal far-infrared electric heating plate in this embodiment and the far-infrared electric heating plate in the prior art is shown in the following table:

[0033]

[0034]

[0035] This embodiment also provides a method for preparing the above-mentioned graphene microcrystal far-infrared heating plate, which specifically includes the following steps:

[0036] Preparation of Base Layer 2: Silicon nitride powder and boron carbide short fibers are thoroughly mixed in a specific ratio and formed into a green body using a dry pressing process at a pressure of 50 MPa. The green body is then placed in a nitrogen atmosphere furnace and sintered at 1650°C for 3 hours to form Base Layer 2, a porous ceramic skeleton structure with a controlled porosity of 10%-15%. This preparation process fully integrates the silicon nitride ceramic and boron carbide short fibers, leveraging their respective strengths to enhance the overall performance of Base Layer 2.

[0037] Functional layer 4 preparation steps:

[0038] Preparation of the conductive and thermally conductive layer: Graphene nanosheets and hexagonal boron nitride nanotubes are first mixed with an organic solvent and ultrasonically dispersed for 2 hours to uniformly disperse them in the solvent, producing a conductive and thermally conductive layer slurry with a solids content of 6%. This slurry is then applied to the surface of the substrate 2 via curtain coating or vacuum filtration and dried in a vacuum environment at 80°C for 12 hours to form a conductive layer approximately 50 μm thick. During the coating process, process parameters are controlled to ensure that the graphene nanosheets have an alignment degree of ≥85%, further improving the electrical and thermal conductivity of the conductive and thermally conductive layer.

[0039] Preparation of the far-infrared radiation layer: Tourmaline powder, nano-titanium dioxide, a binder, and a solvent are mixed in a certain proportion. First, the nano-titanium dioxide is pretreated and a sol is prepared using a sol-gel method. The tourmaline powder is then added to the sol and stirred evenly to prepare a far-infrared radiation layer slurry. This slurry is then applied to the surface of the conductive and thermally conductive layer to form a 30-60μm thick coating. The coating is then cured at 120°C for 2 hours to fully dry and solidify, forming a stable far-infrared radiation layer.

[0040] Sealing and treatment of the glass-ceramic layer 1: Rare earth-doped glass-ceramic powder is evenly spread on the surface of the functional layer 4 and hot pressed at 850°C and 10 MPa for 1 hour to tightly bond the glass-ceramic powder to the functional layer 4. The composite plate glass-ceramic layer 1 is then nano-sandblasted using aluminum oxide sandblasting particles with a particle size of 50-100 nm, a sandblasting pressure of 0.3 MPa, and a sandblasting time of 2 minutes to form a skin-friendly texture. Finally, chemical polishing is performed to reduce the surface roughness Ra to 0.2-0.5 μm, completing the preparation of the graphene microcrystal far-infrared heating plate.

[0041] The glass-ceramic layer 1 can also be provided by first forming and then attaching. In actual processing, those skilled in the art will make different choices based on processing costs and processing requirements.

[0042] It should also be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0043] The above description of the disclosed embodiments will enable one skilled in the art to implement or use the present application. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A graphene microcrystal far-infrared heating plate, characterized in that: The graphene microcrystal far-infrared electric heating plate comprises: a base layer, a functional layer arranged on the base layer, and a microcrystal glass layer covering the functional layer; The base layer is composed of silicon nitride ceramics and boron carbide short fibers. The volume fraction of boron carbide short fibers is 15%-20%, the flexural strength is ≥800MPa, and the thermal conductivity is 80-100W / (m·K); Functional layer: includes an electrically conductive and thermally conductive layer and a far-infrared radiation layer; the electrically conductive and thermally conductive layer is a composite of graphene nanosheets and hexagonal boron nitride nanotubes, and has both electrical heating and thermal conductivity functions; power electrodes are provided on both sides of the functional layer, and both sides of the electrically conductive and thermally conductive layer are electrically connected to the power electrodes; The far-infrared radiation layer is a composite of tourmaline powder and nano-titanium dioxide, with a tourmaline content of 30%-40%, which can stably emit far-infrared rays with a wavelength of 8-14μm; The glass-ceramic layer is a rare earth doped glass-ceramic structure, and the rare earth ions are "Ce 3+ ” or "La 3+ ", doping concentration 0.5%-1.0%, transmittance ≥85%, the surface is nano-level frosted to form a skin-friendly texture.

2. The graphene microcrystal far-infrared heating plate according to claim 1, characterized in that: The nano-titanium dioxide particles in the far-infrared radiation layer have a diameter of 20-30 nm and are compounded with tourmaline through a sol-gel method. A silane coupling agent is grafted on the surface of the nano-titanium dioxide to enhance its dispersibility.

3. The graphene microcrystal far-infrared heating plate according to claim 1, characterized in that: The nanocrystalline phase in the rare earth-doped glass-ceramics has a grain size of 50-100 nm and is prepared by a gradient temperature ramp annealing process with a heating rate of 5°C / min and a temperature retention time of 2 hours at 600°C to promote full growth of the crystal phase.

4. The graphene microcrystal far-infrared heating plate according to claim 1, characterized in that: In the conductive and thermal conductive layer, the number of graphene nanosheets is 3-5, the lateral size is 2-5 μm, and the aspect ratio of hexagonal boron nitride nanotubes is 10-20. The two are evenly mixed through an ultrasonic dispersion process.

5. A method for preparing a graphene microcrystal far-infrared electric heating plate, used for preparing a graphene microcrystal far-infrared electric heating plate according to any one of claims 1 to 4, characterized in that: The following steps are involved: Preparation of the base layer: Silicon nitride powder and boron carbide short fibers were dry-pressed into a mold and then sintered at 1650°C for 3 hours in a nitrogen atmosphere. Functional interlayer construction: Graphene nanosheets, hexagonal boron nitride nanotubes, and an organic solvent are first mixed and ultrasonically dispersed for 2 hours to prepare a conductive and thermally conductive layer slurry with a solid content of 6%. This is then formed through a coating process. Tourmaline powder, nano-titanium dioxide, a binder, and a solvent are then mixed and a far-infrared radiation layer slurry is prepared through a sol-gel method. This is then applied to the surface of the conductive and thermally conductive layer. Glass-ceramic layer sealing: hot-press and sinter the rare earth-doped glass-ceramic powder and the functional interlayer at a sintering temperature of 850°C and a pressure of 10 MPa for 1 hour; Surface treatment: The glass-ceramic layer of the composite panel is nano-sandblasted with a particle size of 50-100nm to form a skin-friendly texture, followed by chemical polishing to achieve a surface roughness Ra of 0.2-0.5μm.

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