Heating diaphragm and preparation method therefor, heating pipe and heating electric appliance

Abstract

Provided in the present disclosure are a heating diaphragm and a preparation method therefor, a heating pipe and a heating electric appliance. The raw materials of the heating diaphragm comprise natural graphite, and the thermal diffusion coefficient of the heating diaphragm is 50 m2 / s to 450 m2 / s.

Description

Heating diaphragm and preparation method thereof, heating tube and heating appliance

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This disclosure claims the priority benefit of Chinese patent application No. 202410119770.1, filed on January 26, 2024, and incorporates the entirety of the patent application herein. Technical Field

[0003] The present disclosure relates to the field of electrical appliance technology, and more specifically, to a heating diaphragm and a preparation method thereof, a heating tube, and a heating appliance. Background Art

[0004] Traditional electric ovens primarily heat the air inside the oven cavity, thereby heating the food, and directly heat the food surface through heat radiation. Currently, the heating components used in electric ovens, microwave ovens, steam ovens, and other heating appliances on the market mainly include metal heating tubes (maximum heating temperature range between 550-750°C), quartz heating tubes (heating wire temperature range between 660-800°C), halogen heating tubes (maximum heating temperature less than 1000°C), and carbon fiber heating tubes (maximum heating temperature less than 1000°C). However, these heating tubes have disadvantages such as slow heating rate within the heating temperature range, insufficient heating speed, and insufficient temperature. This prolongs cooking time and makes it difficult to achieve crispy outside and tender inside food during the heating process, resulting in a poor user experience.

[0005] Summary of the Invention

[0006] The present disclosure aims to solve one of the technical problems in the related art to at least a certain extent. To this end, one purpose of the present disclosure is to provide a heating film having the advantages of high heating temperature, fast heating speed, and fast temperature rise speed.

[0007] In one aspect of the present disclosure, a heating film is provided. According to an embodiment of the present disclosure, the raw material of the heating film includes natural graphite, and the thermal diffusion coefficient of the heating film is 50m 2 / s~450m 2 / s, for example, 50m 2 / s、80m 2 / s、100m 2 / s、130m 2 / s、150m 2 / s、280m 2 / s、300m 2 / s、320m 2 / s、350m 2 / s、370m 2 / s、400m 2 / s、450m 2 / s, etc. Thus, the graphite heating diaphragm prepared from natural graphite has a higher heating temperature and a faster heating rate, which helps to achieve higher temperature heating and higher heating efficiency. Moreover, the heating diaphragm disclosed in the present invention uses natural graphite, which has large reserves among the earth's minerals. At the same time, the carbon-based diaphragm material does not require high-temperature graphitization during the preparation process, does not need to be prepared by other processes, and can be produced continuously, reducing costs. In summary, the carbon-based diaphragm material has the advantages of a wide source of raw materials, a simple preparation process, good product stability, and performance parameters that can be adjusted according to demand and easy to adjust. It has great advantages in reducing product costs, enhancing product reliability, and enriching product varieties. If artificial graphite is used, it is necessary to further set up a process flow for making artificial graphite, which will greatly increase the production cost and time of the heating diaphragm and reduce production efficiency. Furthermore, the above-mentioned thermal diffusivity not only helps to improve the heating rate and heating efficiency of the heating diaphragm, but also makes the heating diaphragm have a longer service life and higher manufacturability, that is, the production yield is high and the service life can meet the use requirements.

[0008] According to an embodiment of the present disclosure, the heating diaphragm has a sheet-like structure, the natural graphite has a sheet-like structure, and the sheet-like extension plane of the heating diaphragm is substantially consistent with the sheet-like extension plane of the graphite.

[0009] According to an embodiment of the present disclosure, the carbon content of the heating film is greater than or equal to 99%.

[0010] According to an embodiment of the present disclosure, the power of the heating film is 15W to 10000W.

[0011] According to an embodiment of the present disclosure, the heating film satisfies at least one of the following conditions: the thermal diffusion coefficient of the heating film is 50m 2 / s~200m 2 / s, the power of the heating film is 15W~5000W; the thermal diffusion coefficient of the heating film is 200m 2 / s~300m 2 / s, the power of the heating film is 60W~7000W; the thermal diffusion coefficient of the heating film is 300m 2 / s~450m 2 / s, and the power of the heating film is 100W to 10000W.

[0012] According to an embodiment of the present disclosure, the heating temperature of the heating film is 500°C to 1700°C.

[0013] According to an embodiment of the present disclosure, the heating film is made of graphite.

[0014] According to an embodiment of the present disclosure, the heating film includes a plurality of heating units sequentially arranged along the length direction, and adjacent heating units are arranged at intervals and connected by connecting sections.

[0015] According to an embodiment of the present disclosure, each of the heating units is provided with a hollow hole.

[0016] According to an embodiment of the present disclosure, the heating diaphragm includes a first heating segment and a second heating segment adjacent to each other in the length direction, the first heating segment includes a plurality of connected heating units, the second heating segment includes a plurality of adjacent heating units, the size of the heating unit corresponding to the first heating segment is smaller than the size of the heating unit corresponding to the second heating segment; and / or, the first heating segment and the second heating segment are staggered in the width direction of the heating diaphragm.

[0017] According to an embodiment of the present disclosure, the heating membrane includes a plurality of notches arranged at intervals along the length direction.

[0018] According to an embodiment of the present disclosure, each of the gaps is defined by separating a portion of the heating membrane from the rest and then bending it.

[0019] On the other hand, the present disclosure provides a method for preparing the aforementioned heating diaphragm. According to an embodiment of the present disclosure, the method for preparing the heating diaphragm includes: providing natural graphite, and performing an intercalation treatment on the same to obtain expandable graphite; performing an expansion treatment on the expandable graphite to obtain expanded graphite; and performing calendering and cutting on the expanded graphite to obtain the heating diaphragm. Thus, the heating diaphragm made of graphite material obtained by using natural graphite makes the heating temperature of the heating diaphragm higher and the heating rate faster, which helps to achieve higher temperature heating and higher heating efficiency; moreover, the heating diaphragm of the present disclosure uses natural graphite, and natural graphite ore has large reserves among the earth's minerals. At the same time, the carbon-based diaphragm material does not require high-temperature graphitization during the preparation process, does not need to be prepared by other processes, and can be produced continuously to reduce costs. In summary, the carbon-based diaphragm material has the advantages of a wide source of raw materials, a simple preparation process, good product stability, and performance parameters that can be adjusted according to demand and are easy to adjust. It has huge advantages in reducing product costs, enhancing product reliability, and enriching product types. If artificial graphite is used, it is necessary to further set up a process flow for producing artificial graphite, which will greatly increase the production cost and time of the heating diaphragm and reduce production efficiency.

[0020] According to an embodiment of the present disclosure, the intercalation treatment conditions are: intercalating the natural graphite with concentrated sulfuric acid and / or hydrogen peroxide to obtain the expandable graphite; the expansion treatment conditions are: putting the expandable graphite into an expansion furnace and expanding it at a temperature of 850-1200°C to obtain the worm-shaped expandable graphite.

[0021] In another aspect of the present disclosure, a heat pipe is provided. According to an embodiment of the present disclosure, the heat pipe includes the aforementioned heating film. As a result, the heat pipe achieves a higher heating temperature, a faster heating rate, and a more concentrated heating area, significantly improving the heating efficiency of the heat pipe. Those skilled in the art will appreciate that the heat pipe possesses all the features and advantages of the aforementioned heating film, and further details will not be given here.

[0022] In another aspect of the present disclosure, a heating appliance is provided. According to an embodiment of the present disclosure, the heating appliance includes the aforementioned heating pipe. As a result, the heating appliance has a higher heating temperature, a faster heating rate, and a more concentrated heating area, greatly improving the heating efficiency of the heating appliance.

[0023] According to an embodiment of the present disclosure, the heating appliance is an electric oven, a microwave oven, a steam oven, an electric kettle, an electric blanket, an electric fan heater, an electric heater, a bathroom heater, an electric ceramic stove or a disinfection cabinet. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and / or additional aspects and advantages of the present disclosure will become apparent and readily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0025] FIG1 is a schematic diagram of a curve showing the relationship between the thermal diffusivity of a heating film and the temperature of a conductor;

[0026] FIG2 is a schematic diagram of heat radiation of the heating film disclosed in the present invention;

[0027] FIG3 is a schematic diagram of heat radiation of a heat-generating tube core in the prior art;

[0028] FIG4 is a schematic diagram of a curve showing the relationship between the heating temperature and the resistance of the heating film of the present disclosure;

[0029] FIG5 is a schematic structural diagram of a heating film in other embodiments of the present disclosure;

[0030] FIG6 is a schematic structural diagram of a heating film in other embodiments of the present disclosure;

[0031] FIG7 is a schematic structural diagram of a heating film in other embodiments of the present disclosure;

[0032] FIG8 is a schematic structural diagram of a heating pipe in some other embodiments of the present disclosure;

[0033] FIG9 is a schematic structural diagram of a heating pipe in some other embodiments of the present disclosure;

[0034] FIG10 is a schematic structural diagram of a heating pipe in some other embodiments of the present disclosure;

[0035] FIG11 is a schematic structural diagram of a heating film in other embodiments of the present disclosure. DETAILED DESCRIPTION

[0036] The scheme of the present disclosure will be explained below in conjunction with the examples. Those skilled in the art will understand that the following examples are only used to illustrate the present disclosure and should not be considered to limit the scope of the present disclosure. Where specific techniques or conditions are not specified in the examples, they are carried out according to the techniques or conditions described in the literature in this area or according to the product instructions. Where the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be obtained commercially.

[0037] The present disclosure is described below with reference to specific embodiments. It should be noted that these embodiments are merely illustrative and do not limit the present disclosure in any way.

[0038] Thermal diffusivity is a measure of the rate at which a temperature disturbance at one point in an object is transferred to another point. The larger the thermal diffusivity, the faster the rate of heat conduction. The connecting terminals at both ends of the heating tube will be connected to the wires. If the thermal diffusivity of the heating diaphragm is higher, the rate of heat conduction to both ends will be faster when the heating diaphragm continues to work and generate heat. This will have two adverse effects: 1) The greater the thermal shock to the connecting wire, the higher the temperature of the wire will be, as shown in Figure 1; 2) The more heat the wire conducts, the less heat the heating diaphragm applies to the object to be heated (such as food). Based on this, the present disclosure proposes a heating diaphragm with a suitable thermal diffusivity, which can not only ensure a good heating rate but also improve the heating efficiency.

[0039] Based on this, in one aspect of the present disclosure, the present disclosure provides a heating film. According to an embodiment of the present disclosure, the raw material of the heating film includes natural graphite, and the thermal diffusion coefficient of the heating film is 50m 2 / s~450m 2 / s, for example, 50m 2 / s、80m 2 / s、100m 2 / s、130m 2 / s、150m 2 / s、280m 2 / s、300m 2 / s、320m 2 / s、350m 2 / s、370m 2 / s、400m 2 / s、420m 2 / s、450m 2 / s, etc. Thus, the graphite heating diaphragm prepared from natural graphite has a higher heating temperature and a faster heating rate, which helps to achieve higher temperature heating and higher heating efficiency. Moreover, the heating diaphragm disclosed in the present invention uses natural graphite, which has large reserves among the earth's minerals. At the same time, the carbon-based diaphragm material does not require high-temperature graphitization during the preparation process, does not need to be prepared by other processes, and can be produced continuously, reducing costs. In summary, the carbon-based diaphragm material has the advantages of a wide source of raw materials, a simple preparation process, good product stability, and performance parameters that can be adjusted and easily adjusted according to demand. It has great advantages in reducing product costs, enhancing product reliability, and enriching product varieties. If artificial graphite is used, it is necessary to further set up a process flow for making artificial graphite, which will greatly increase the production cost and time of the heating diaphragm and reduce production efficiency. Furthermore, the above-mentioned thermal diffusivity is appropriate, which not only helps to improve the heating rate and heating efficiency of the heating diaphragm, but also makes the heating diaphragm have a longer service life and higher manufacturability, that is, the production yield is high and the service life can meet the use requirements.

[0040] The principle that the thermal diffusion coefficient disclosed herein helps to improve the heating rate and heating efficiency of the heating diaphragm is as follows: the above-mentioned thermal diffusion coefficient can make the heat emitted by the heating diaphragm be less transferred out of the heating cavity in the form of heat conduction, so that more heat is concentrated on the heating diaphragm, and the heating diaphragm has a higher temperature. According to Boltzmann's law, the greater the temperature difference, the greater the radiation energy, and more heat is transferred to the heating cavity in the form of radiation, so that the heat generated by the heating diaphragm is mainly concentrated on the object to be heated. In this way, a better heating rate can be guaranteed without transferring heat too quickly, resulting in a large heat loss, thereby improving the heating efficiency. Moreover, the above-mentioned thermal diffusion coefficient can also help to extend the service life of the heating diaphragm. The thermal diffusion coefficient is less than 50m 2 / s, the heat transferred by the heating diaphragm in the form of heat conduction is too little, making the temperature of the heating diaphragm too high and the service life cannot meet the requirements; the thermal diffusion coefficient is greater than 450m 2 / s, the heat conducted out is more, the radiation energy is less, the heating efficiency of the heating film is low, and the higher the thermal diffusion coefficient, the higher the density of the heating film required to be made. The thermal diffusion coefficient is greater than 450m 2 / s corresponds to a higher density and is more difficult to manufacture. Meanwhile, the raw materials for the carbon-based heating film disclosed herein are readily available and low-cost; and no high-temperature graphitization treatment is required, making the process simpler and safer.

[0041] According to some embodiments of the present disclosure, the heating diaphragm has a sheet-like structure, the raw graphite used to prepare the heating diaphragm has a sheet-like structure, and the sheet-like extension plane of the heating diaphragm is basically consistent with the sheet-like extension plane of the graphite. Therefore, as shown in Figure 2, when the sheet-like structure heating diaphragm generates heat, the heat is mainly radiated along the vertical direction of the heating surface (i.e., the plane of the diaphragm), with strong directivity and more concentrated radiated heat, which can better improve the heating efficiency and reduce heat loss. In the current prior art, referring to Figure 3, the heat radiation of the heating tube core 1 (such as a metal heating tube core or a quartz tube core) is evenly emitted in all directions, and the heat cannot be concentrated. This usually causes heat waste and reduces heating efficiency. From this comparison, it can be seen that the heat radiation direction of the heating diaphragm disclosed in the present disclosure is more concentrated, which can better direct the heating of the object to be heated and improve the heating efficiency. It should be noted that the above-mentioned "basic consistency" means that the sheet-like extension plane of the heating diaphragm is roughly consistent with the sheet-like extension plane of the natural graphite, and it is not required that the two are completely consistent or completely parallel.

[0042] According to some embodiments of the present disclosure, as described above, the heating diaphragm prepared from the raw material natural graphite is made of graphite, which enables the heating diaphragm of the present disclosure to have a higher heating temperature and a faster heating rate. The prepared graphite still has a flaky structure, and the plane extension direction of the flaky structure is substantially consistent with the plane extension direction of the raw material natural graphite. Therefore, it can be said that the flaky extension plane of the heating diaphragm is substantially consistent with the flaky extension plane of the graphite material it is made of.

[0043] According to some embodiments of the present disclosure, the heating film satisfies at least one of the following conditions: the thickness of the heating film is 0.04 mm to 2 mm, for example, the thickness of the heating film is 0.04 mm, 0.08 mm, 0.2 mm, 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2.0 mm, etc.; the density of the heating film is 0.6 g / cm 3 ~1.8g / cm 3 For example, the density of the heating film is 0.6g / cm 3 , 0.8g / cm 3 , 1.0g / cm 3 , 1.2g / cm 3 , 1.4g / cm 3 , 1.5g / cm 3 , 1.6g / cm 3 , 1.8g / cm 3Thus, the heating film of the above density and thickness can meet the requirements of different power levels for the heating film, that is, both ultra-high power heating films and ultra-low power heating films can be obtained; moreover, the carbon-based heating film disclosed in the present invention has high manufacturability, that is, high production yield and long service life.

[0044] According to some embodiments of the present disclosure, the carbon content of the heating film is greater than or equal to 99%. Therefore, the carbon content of the heating film is higher, that is, the purity is higher, which is conducive to obtaining a heating film with better performance.

[0045] According to some embodiments of the present disclosure, the power of the heating diaphragm is 15W to 10000W, such as 15W, 20W, 40W, 50W, 70W, 100W, 150W, 300W, 500W, 800W, 1000W, 1500W, 3000W, 4500W, 5000W, 6000W, 7000W, 8000W, 9000W, 10000W, etc. Therefore, the heating diaphragm of the present disclosure can effectively achieve heating of different powers with a large span, and can achieve ultra-low power heating as well as ultra-high power heating, meeting the power usage requirements of the heating diaphragm under various application conditions.

[0046] According to an embodiment of the present disclosure, the heating film satisfies at least one of the following conditions: the thermal diffusion coefficient of the heating film is 50m 2 / s~200m 2 / s, the power of the heating film is 15W~5000W; the thermal diffusion coefficient of the heating film is 200m 2 / s~300m 2 / s, the power of the heating film is 60W~7000W; the thermal diffusion coefficient of the heating film is 300m 2 / s~450m 2 / s, the power of the heating film is 100W to 10000W. It can be seen that the power of the heating film varies at different stages of the thermal diffusion coefficient. Therefore, in the present disclosure, the power of the heating film can be adjusted by adjusting the thermal diffusion coefficient of the heating film, so that heating films of various powers can be obtained to meet various heating requirements.

[0047] According to some embodiments of the present disclosure, the heating temperature of the heating film is 500°C to 1700°C. For example, the heating temperature of the heating film can be 500°C, 550°C, 600°C, 700°C, 800°C, 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, 1500°C, 1600°C, 1700°C, etc. It can be seen that the heating temperature of the heating film of the present disclosure can reach up to 1700°C. Moreover, those skilled in the art can flexibly adjust the maximum heating temperature of the heating film by adjusting the density and / or thickness of the heating film according to the specific application requirements of the heating film, thereby meeting more application heating requirements of the heating film and obtaining heating films of various powers, such as ultra-low power heating films or ultra-high power heating films.

[0048] According to some embodiments of the present disclosure, the heating film prepared from natural graphite also has the characteristic of self-limiting temperature. Specifically: with reference to FIG4 , the heating film has a critical temperature. When the temperature of the heating film is less than the critical temperature, the resistance of the heating film decreases as the temperature increases; when the temperature of the heating film is greater than the critical temperature, the resistance of the heating film increases as the temperature increases. It can be seen that the heating film of the present disclosure has the characteristic of self-limiting temperature. Specifically: in the initial stage of heating (that is, when the temperature of the heating film is less than the critical temperature), the resistance of the heating film decreases as the temperature increases, and the current increases, so that the power of the heating film increases as the temperature increases, so in this stage, the heating film can heat up rapidly; when the heating temperature of the heating film reaches the critical temperature, the resistance of the heating film increases as the temperature increases, and the current decreases, so that the power of the heating film decreases as the temperature increases, so in this stage, the heating rate of the heating film begins to slow down, and slowly gradually reaches the maximum heating temperature of the heating film. The self-limiting temperature characteristic of the heating diaphragm described above can, on the one hand, accelerate the heating rate of the heating diaphragm in the temperature zone below the critical temperature, allowing the heating diaphragm to reach the target temperature as quickly as possible. On the other hand, when the heating temperature is above the critical temperature, it can also reduce the problem of melting caused by the continuous increase in the heating temperature, for example, it can improve the reliability and stability of the heating diaphragm. It should be noted that Figure 4 is only a temperature-resistance curve diagram of the heating diaphragm in one embodiment, but the trend of this curve represents the temperature-resistance curve schematic diagram of the heating diaphragm disclosed in the present invention.

[0049] In the embodiments of the present disclosure, the specific cutting shape of the heating film can be diversified. Those skilled in the art can flexibly design the cutting shape of the heating film according to the actual requirements of the resistance, power, etc. of the heating film. The following is an introduction to some cutting shapes of the heating film based on some specific embodiments of the present disclosure:

[0050] In some embodiments of the present disclosure, referring to FIG5 , the heating film includes a plurality of heating units 01 arranged sequentially along the length direction, with adjacent heating units 01 spaced apart and connected by connecting sections 02 . Thus, the heating film of the present disclosure can be cut into a variety of different cut-out structures to meet different usage requirements. Specifically, in some embodiments of the present disclosure, referring to FIG5 , the outer peripheral wall of the heating unit is formed into an oblong or polygonal shape.

[0051] In some embodiments of the present disclosure, referring to (b), (c), and (i) of Figure 5 , each heating unit 01 is provided with a hollow hole 03. Thus, the provision of the hollow hole can accelerate the heat dissipation rate of the heating film and accelerate the heating rate of the object to be heated.

[0052] In some embodiments of the present disclosure, referring to FIG6 , the heating diaphragm includes a first heating segment S2 and a second heating segment S1 adjacent to each other in the length direction, the first heating segment S2 includes a plurality of connected heating units 01, the second heating segment S1 includes a plurality of adjacent heating units 01, the size of the heating unit 01 corresponding to the first heating segment S2 is smaller than the size of the heating unit 01 corresponding to the second heating segment S1, for example, in FIG6 (a), the length of the heating unit 01 corresponding to the first heating segment S2 is the same as the length of the heating unit 01 corresponding to the second heating segment S1, but the widths d2 and d1 of the two are different, d2 < d1; for example, in FIG6 (b) and (c), the width of the heating unit 01 corresponding to the first heating segment S2 is the same as the width of the heating unit 01 corresponding to the second heating segment S1, but the lengths d2 and d1 of the two are different, d2 < d1. This can achieve the diversification of the heating diaphragm structure.

[0053] In some embodiments of the present disclosure, referring to FIG7 , the first heating section and the second heating section are staggered in the width direction of the heating film, thereby achieving a diversified structure of the heating film.

[0054] In some embodiments of the present disclosure, referring to (d), (e), (f), (h), (i), and (j) in FIG5 , the heating diaphragm includes a plurality of notches spaced apart along its length. This allows for a variety of heating diaphragm structures. Furthermore, in some embodiments of the present disclosure, referring to (i) in FIG5 , each notch is defined by separating a portion of the heating diaphragm from the rest and then bending it.

[0055] In some embodiments, as shown in FIG11 , the same heating film may include a plurality of different cut types, or include the same cut type with uneven density distribution.

[0056] In another aspect of the present disclosure, a method for preparing the aforementioned heating film is provided. According to an embodiment of the present disclosure, the method for preparing the heating film can be prepared from natural graphite, and the specific preparation steps are as follows:

[0057] In some embodiments, a method for preparing a heating film using natural graphite includes:

[0058] S100: providing natural graphite and subjecting it to intercalation treatment to obtain expandable graphite (graphite oxide).

[0059] In the present disclosure, natural graphite is used, which does not need to be prepared through other processes, and can further reduce the process flow of preparing the heating diaphragm and reduce costs. If artificial graphite is used, it is necessary to further set up a process flow for making artificial graphite, which will greatly increase the production cost and time of the heating diaphragm and reduce production efficiency; moreover, the use of natural flake graphite, the graphite single-layer structure is a layered structure, which can make the graphite in the prepared heating diaphragm also have a layered structure, thereby improving the centralized heating effect of the heating diaphragm. In addition, natural flake graphite has large reserves in the earth's minerals. At the same time, the carbon-based heating diaphragm material does not require high-temperature graphitization during the preparation process, and can be produced continuously, which can further improve production efficiency and reduce production costs; the lack of high-temperature graphitization also improves production safety.

[0060] In addition, natural flake graphite has large reserves in the earth's mineral resources. At the same time, the heating membrane material disclosed in the present invention does not require high-temperature graphitization during the preparation process and can be produced continuously, which can further improve production efficiency and reduce production costs; the absence of high-temperature graphitization also improves production safety.

[0061] In some embodiments, the specific method of intercalation treatment can be to intercalate natural flake graphite with oxides such as concentrated sulfuric acid and / or hydrogen peroxide to obtain expandable graphite.

[0062] S200: performing expansion treatment on the expandable graphite to obtain expanded graphite.

[0063] In some embodiments, upon entering the expansion furnace, expandable graphite experiences a transient high temperature, rapidly expanding to form graphite worms, also known as expanded graphite. This expansion process can achieve expansion multiples of 30 to 400 times. The expansion process occurs at a temperature of 850-1200°C and for a time of 0.7 to 1.3 seconds.

[0064] S300: Rolling, first heat treatment, and cutting the expanded graphite to obtain a heating film. The heating films obtained after cutting can be seen in Figures 5 to 7 and 11. The specific cutting characteristics are consistent with the requirements described above and will not be described in detail here.

[0065] There are no special requirements for the specific method of the first heat treatment, and those skilled in the art can adopt the specific heat treatment method for deoxidizing expandable graphite to obtain graphite in the prior art.

[0066] In this way, by rolling the expanded graphite, the thickness, density, thermal diffusion coefficient and other parameter characteristics of the heating film can be controlled. The thickness, density and thermal diffusion coefficient of the heating film are as described above and will not be described in detail here.

[0067] According to the embodiments of the present disclosure, the heating diaphragm made of graphite material obtained by using natural graphite as mentioned above makes the heating temperature of the heating diaphragm higher and the heating rate faster, which helps to achieve higher temperature heating and higher heating efficiency; moreover, the heating diaphragm of the present disclosure uses natural graphite, and natural graphite ore has large reserves among the earth's minerals. At the same time, the carbon-based diaphragm material does not require high-temperature graphitization during the preparation process, does not need to be prepared by other processes, and can be produced continuously to reduce costs. In general, the carbon-based diaphragm material has the advantages of a wide source of raw materials, a simple preparation process, good product stability, and performance parameters that can be adjusted according to demand and easy to adjust. It has huge advantages in reducing product costs, enhancing product reliability, and enriching product types. If artificial graphite is used, it is necessary to further set up a process flow for making artificial graphite, which will greatly increase the production cost and time of the heating diaphragm and reduce production efficiency.

[0068] In another aspect of the present disclosure, a heat pipe is provided. According to an embodiment of the present disclosure, the heat pipe includes the aforementioned heating film. As a result, the heat pipe achieves a higher heating temperature, a faster heating rate, and a more concentrated heating area, significantly improving the heating efficiency of the heat pipe. Those skilled in the art will appreciate that the heat pipe possesses all the features and advantages of the aforementioned heating film, and further details will not be given here.

[0069] In some embodiments, referring to Figure 8 (the S area in the figure refers to a partial cross-sectional view of the sleeve), Figure 9 and Figure 10, the heating tube also includes a sleeve 10, and the heating membrane 20 is placed in the sleeve 10. Terminals 21 are provided at both ends of the heating membrane 20, wherein the sleeve can be a quartz glass tube or the like.

[0070] In another aspect of the present disclosure, a heating appliance is provided. According to an embodiment of the present disclosure, the heating appliance includes the aforementioned heating pipe. As a result, the heating appliance has a higher heating temperature, a faster heating rate, and a more concentrated heating area, greatly improving the heating efficiency of the heating appliance.

[0071] According to an embodiment of the present disclosure, the heating appliance is an electric oven, a microwave oven, a steam oven, an electric kettle, an electric blanket, an electric fan heater, an electric heater, a bathroom heater, an electric ceramic stove or a disinfection cabinet.

[0072] Those skilled in the art will understand that, in addition to the above-mentioned heating tubes, the heating appliance also includes the necessary structures or components of the heating appliance. Taking the electric oven as an example, in addition to the above-mentioned heating tubes, it also includes the necessary structures or components such as the shell, heating space, base, and plug.

[0073] Example

[0074] Examples 1 to 9, Comparative Examples 1 and 2

[0075] A heating film was prepared using natural flake graphite. The heating film had a length of 600 mm and a width of 8 mm, and was cut as shown in Figure 5 (a). The thermal diffusivity, lifespan, and heating temperature of the heating films in different embodiments can be found in Table 1 below. The heating films in various embodiments were fabricated into heating tubes. All heating tubes were tested at a power of 600 W, and the time required for each heating tube to reach 200°C was measured. The test results can be found in Table 1. Halogen tubes, quartz tubes, and metal tubes were used in the same oven. All heating tubes were tested at a power of 600 W, and the time required for each heating tube to reach 200°C was measured. The test results can be found in Table 2.

[0076] The test method for the above life is: apply 1.1 times the rated voltage to the heating diaphragm, and after the continuous working time reaches 525 hours, it should meet the following requirements: (1) the heating tube has no cracks, gaps, or deformation; (2) the heating diaphragm has no breakage, no bending or deformation, and the power deviation meets the design requirements of the drawing; (3) insulation resistance: use a DC500V insulation resistance meter to test between the live parts (terminals) and the non-live parts (tube wall) of the heating tube, and the test resistance is ≥500MΩ (DC500V); (4) insulation strength: apply a voltage of 1800VAC / 3S / 5mA between the live parts (terminals) and the non-live parts (tube wall) of the heating tube, and if there is no flashover or breakdown, it is qualified.

[0077] Table 1

[0078] Table 2

[0079] The above test results show that the thermal diffusion number of the heating film of the present invention is 50m 2 / s~450m 2 / s, the life of the heating film can be effectively improved. The heating film has a higher heating temperature and a faster heating rate. Moreover, the heating efficiency of the heating film is higher and it can reach a higher heating temperature in a shorter time. However, the thermal diffusion coefficient is greater than 450m 2 / s, the heating time is extended, and the density of the heating film is higher, which is more difficult to achieve in terms of technology, that is, the difficulty of the process is increased.

[0080] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0081] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0082] Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are illustrative and are not to be construed as limitations on the present disclosure. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present disclosure.

Claims

1. A heating film, wherein, The raw material of the heating film includes natural graphite, and the thermal diffusivity of the heating film is 50m 2 / s to 450m 2 / s.

2. The heating film according to claim 1, wherein, The heating film is in a sheet structure, the graphite is in a sheet structure, and the sheet extension plane of the heating film is substantially the same as the sheet extension plane of the natural graphite.

3. The heating diaphragm according to claim 1 or 2, wherein, The carbon content of the heating film is greater than or equal to 99%.

4. The heating diaphragm according to any one of claims 1 to 3, wherein, The power of the heating film is 15W - 10000W.

5. The heating film according to claim 4, wherein, The heating film satisfies at least one of the following conditions: The thermal diffusivity of the heating film is 50 m 2 / s to 200 m 2 / s, and the power of the heating film is 15 W to 5000 W; The thermal diffusivity of the heating film is 200 m 2 / s to 300 m 2 / s, and the power of the heating film is 60 W to 7000 W; The thermal diffusivity of the heating film is 300 m 2 / s to 450 m 2 / s, and the power of the heating film is 100 W to 10,000 W.

6. The heating film according to any one of claims 1 to 5, wherein, The heating temperature of the heating film is 500°C - 1700°C.

7. The heating film according to any one of claims 1 to 6, wherein, The material of the heating film is graphite.

8. The heating film according to any one of claims 1 to 7, wherein, The heating film includes a plurality of heating units arranged sequentially along the length direction, and adjacent heating units are spaced apart and connected by a connecting section.

9. The heating film according to claim 8, wherein, Each of the heating units is provided with a hollow hole.

10. The heating film according to claim 8 or 9, wherein, The heating film includes a first heating section and a second heating section adjacent in the length direction. The first heating section includes a plurality of connected heating units, the second heating section includes a plurality of adjacent heating units, and the size of the heating units corresponding to the first heating section is smaller than the size of the heating units corresponding to the second heating section; and / or The first heating section and the second heating section are arranged offset in the width direction of the heating film.

11. The heating film according to any one of claims 8 to 10, wherein, The heating film includes a plurality of notches spaced along the length direction.

12. The heating film according to claim 11, wherein, Each of the notches is defined by bending after a part of the heating film is separated from the rest.

13. A method for preparing the heating diaphragm according to any one of claims 1 to 12, wherein, Comprising: Providing natural graphite and subjecting it to intercalation oxidation treatment to obtain expandable graphite; Performing an expansion treatment on the expandable graphite to obtain expanded graphite; [[ID= 14. The method according to claim 13, wherein, ​ ​ 15. A heating tube, wherein, ​ 16. A heating appliance, wherein, ​ 17. The heating appliance according to claim 16, wherein, ​

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