Graphene heating film assembly, preparation method thereof and cooking utensil

Abstract

The invention provides a graphene heating film assembly, a preparation method thereof and a cooking utensil, the graphene heating film assembly comprises a substrate, the substrate comprises a preparation surface, the roughness value of the preparation surface is less than or equal to a roughness threshold; the insulating layer is arranged on the preparation surface; the graphene heating layer is arranged on the side, away from the substrate, of the insulating layer. According to the graphene heating film assembly provided by the invention, the insulating layer is arranged between the graphene heating layer and the substrate, so that the insulating performance of the substrate can be improved, and the safety performance of a device using the graphene heating film assembly is ensured. Wherein the roughness value of the preparation surface is smaller than or equal to the roughness threshold value, so that the roughness value of the preparation surface is relatively low, that is, the preparation surface is relatively flat, and when the insulating layer is arranged on the preparation surface, the thickness consistency and no weak area of the insulating layer can be ensured, and the condition of electric breakdown during working of the graphene heating film assembly is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of household appliances, and in particular, to a graphene heating film assembly, a preparation method thereof, and a cooking appliance. Background Art

[0002] In the related art, when the graphene film heating technology is applied to small household appliances, the graphene heating material is directly printed on the substrate to be heated, and after being powered on, the resistance of the graphene heating material is used for heating. This method directly heats the substrate, and the heating efficiency is very high. However, since the energized graphene heating material directly acts on the substrate, its electrical safety is an issue that needs to be emphasized. Currently, microcrystalline glass is usually selected as the substrate. On the one hand, the graphene on the microcrystalline glass can penetrate through the glass after high-temperature heating to generate infrared radiation. On the other hand, microcrystalline glass is a good electrical insulator at room temperature and meets the electrical strength (3000V / 1min) required by safety regulations. However, in the field of small household appliances, the temperature usually used is above 300°C. When the temperature of microcrystalline glass exceeds 250°C, the diffusion movement of ions in the microcrystalline glass is enhanced, and its electrical insulation cannot be maintained, resulting in breakdown. Therefore, when a small household appliance product uses a microcrystalline panel printed with a graphene heating material, it is necessary to solve the problem that the electrical strength does not meet the requirements of safety regulations under high temperature and high pressure. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0004] To this end, the first aspect of the present invention provides a graphene heating film assembly.

[0005] The second aspect of the present invention further provides a preparation method of a graphene heating film assembly.

[0006] The third aspect of the present invention further provides a cooking appliance.

[0007] In view of this, the first aspect of the present invention proposes a graphene heating film assembly, including: a substrate, the substrate includes a preparation surface, and the roughness value of the preparation surface is less than or equal to a roughness threshold; an insulating layer, disposed on the preparation surface; and a graphene heating layer, disposed on the side of the insulating layer away from the substrate.

[0008] The graphene heating film assembly provided by the present invention includes a substrate, and an insulating layer and a graphene heating layer sequentially disposed on the preparation surface of the substrate. The graphene heating layer is a heating component, which can utilize the resistance of the graphene heating material to heat after being energized. The graphene heating layer has a relatively high heating efficiency, which can improve the heating efficiency of the graphene heating film assembly. The insulating layer is disposed between the graphene heating layer and the substrate, which can improve the insulation performance of the substrate and ensure the safety performance of the device using the graphene heating film assembly. Among them, the roughness value of the preparation surface is less than or equal to the roughness threshold, so that the roughness value of the preparation surface is relatively low, that is, the preparation surface is relatively flat. Furthermore, when the insulating layer is disposed on the preparation surface, the thickness of the insulating layer can be ensured to be consistent and there is no weak area, thereby avoiding the occurrence of electric breakdown when the graphene heating film assembly works.

[0009] According to the graphene heating film assembly provided by the present invention, the following additional technical features may also be included:

[0010] In some possible designs, the roughness threshold is greater than 0 and less than or equal to 10 μm.

[0011] In this design, the roughness threshold is set between 0 and 10 μm, so that the roughness value of the preparation surface is relatively small and the preparation surface is relatively flat. In this way, when the insulating layer is prepared on the preparation surface, the thickness of the insulating layer at each position can be relatively uniform and there will be no weak points, thereby avoiding the occurrence of breakdown during operation.

[0012] In some possible designs, the insulating layer includes a ceramic insulating layer, and the thermal expansion coefficient of the ceramic insulating layer is greater than 0 and less than or equal to 1×10 -6 K.

[0013] In this design, the insulating layer includes a ceramic insulating layer, which can withstand a relatively high temperature. At the same time, the thermal expansion coefficient of the ceramic insulating layer is set to be less than or equal to 1×10 -6 K, so that the thermal expansion coefficient of the ceramic insulating layer is relatively small, and thus it is adapted to the thermal expansion coefficient of the substrate, avoiding the situation that the thermal expansion coefficient gap between the ceramic insulating layer and the substrate is too large, resulting in the ceramic insulating layer falling off or cracking, thereby ensuring the reliability of the ceramic insulating layer.

[0014] In some possible designs, the thickness of the insulating layer is greater than or equal to 45 μm and less than or equal to 200 μm.

[0015] In this design, if the thickness of the insulating layer is too thick, the manufacturing cost will increase and it is easy to fall off. If the thickness of the insulating layer is too thin, the insulation performance will be reduced. Therefore, setting the thickness of the insulating layer between 45 μm and 200 μm can not only ensure the insulation performance of the insulating layer but also reduce the cost.

[0016] In some possible designs, the insulating layer includes multiple insulating coatings, and the thickness of any one insulating coating is greater than or equal to 15 μm and less than or equal to 40 μm.

[0017] In this design, the insulating layer includes multiple insulating coatings, that is, the insulating layer has a multi-layer structure. The thickness of each insulating coating cannot be too thick, as it is not conducive to the preparation of each insulating coating. If it is too thin, the number of preparation times increases, thereby increasing the manufacturing cost. Therefore, the thickness of any one insulating coating is set to be greater than or equal to 15 μm and less than or equal to 40 μm, which is not likely to cause coating damage and ensures the insulating effect of the insulating layer.

[0018] In some possible designs, the graphene heating film assembly further includes: a conductive layer disposed on the insulating layer and connected to the graphene heating layer. The conductive layer is located on at least one side of the graphene heating layer, or on at least two relatively arranged sides of the graphene heating layer to supply power to the graphene heating layer.

[0019] In this design, the conductive layer is disposed on the substrate and located on at least one side of the graphene heating layer. Further, or the conductive layer is located on at least two relatively arranged sides of the graphene heating layer. For example, the conductive layer is located on the left and right sides that are relatively arranged of the graphene heating layer, or the conductive layer is located on the front and back sides that are relatively arranged of the graphene heating layer. Of course, the conductive layer can also be disposed on the front, back, left, and right sides of the graphene heating layer. In actual processes, among the conductive layers relatively arranged on both sides, one conductive layer is the positive electrode and the other conductive layer is the negative electrode.

[0020] In some possible designs, the conductive layer includes a silver conductive layer or a copper electrode.

[0021] In this design, the conductive layer includes a silver conductive layer or a copper electrode, and the silver conductive layer or the copper electrode has good conductivity. Among them, when the conductive layer includes a silver conductive layer, the sintering temperature of the silver conductive layer is less than or equal to 500 °C to prevent the silver conductive layer from penetrating into the insulating layer and affecting the insulating performance of the insulating layer.

[0022] In some possible designs, the silver conductive layer includes a binder containing Bi element; the weight percentage of Bi element is greater than or equal to 15% and less than or equal to 30%.

[0023] In this design, the silver conductive layer includes a binder containing Bi element (bismuth element), and the weight percentage of Bi element in the silver paste is greater than or equal to 15% and less than or equal to 30% to reduce the sintering temperature of the silver conductive layer.

[0024] In some possible designs, the silver conductive layer further includes Ag element, Si element and Zn element; the weight percentage of Ag element is greater than or equal to 15% and less than or equal to 25%; the weight percentage of Si element is greater than or equal to 5% and less than or equal to 10%; the weight percentage of Zn element is greater than or equal to 1% and less than or equal to 5%.

[0025] In this design, the silver conductive layer further includes Ag (silver) element, Si (silicon) element and Zn (zinc) element, which ensures the conductivity of the silver conductive layer. Specifically, the weight percentage of Ag element is greater than or equal to 15% and less than or equal to 25%; the weight percentage of Si element is greater than or equal to 5% and less than or equal to 10%; the weight percentage of Zn element is greater than or equal to 1% and less than or equal to 5%.

[0026] In some possible designs, the graphene heating film assembly further includes: a protective layer, which is provided on the side of the graphene heating layer facing away from the conductive layer.

[0027] In this design, the protective layer can protect the graphene heating layer to play a role in waterproofing, insulation and preventing scratching damage.

[0028] In some possible designs, the substrate includes a microcrystalline panel.

[0029] In this design, when the graphene heating layer on the microcrystalline glass is heated at a high temperature, it can penetrate through the glass to generate infrared radiation. Moreover, the microcrystalline glass is a good electrical insulator at room temperature, which ensures the safety performance of the graphene heating film assembly. In addition, microcrystalline glass is relatively common, so it is easier to purchase and the cost will be relatively low.

[0030] According to the second aspect of the present invention, a method for preparing a graphene heating film assembly is also proposed, which is used for the graphene heating film assembly. The graphene heating film assembly includes a substrate, and the substrate includes a preparation surface. The preparation method includes: performing roughness treatment on the substrate so that the roughness value of the preparation surface is less than or equal to the roughness threshold; preparing an insulating layer on the preparation surface; and preparing a graphene heating layer on the insulating layer.

[0031] The method for preparing a graphene heating film assembly provided by the second aspect of the present invention includes: performing roughness treatment on the substrate so that the roughness value of the preparation surface of the substrate is less than or equal to the roughness threshold, and then preparing an insulating layer on the preparation surface so that the thickness of each position of the insulating layer is consistent, thus no weak areas will be generated, ensuring the insulation performance of the insulating layer. After preparing the insulating layer, a graphene heating layer is prepared on the insulating layer to achieve heating through the graphene heating layer.

[0032] In some possible designs, the step of performing roughness treatment on the substrate so that the roughness value of the prepared surface is less than or equal to a roughness threshold specifically includes: performing roughness treatment on the substrate so that the roughness value of the prepared surface is greater than 0 and less than or equal to 10 μm.

[0033] In this design, the roughness value of the preparation surface is greater than 0 and less than or equal to 10μm, so that the roughness value of the preparation surface is smaller, and the preparation surface is relatively smooth. In this way, when preparing an insulating layer on the preparation surface, the thickness of the insulating layer at various positions can be relatively uniform, and there will be no weak points, thereby avoiding breakdown during operation.

[0034] In some possible designs, the insulating layer includes a ceramic insulating layer, the ceramic insulating layer includes multiple layers of insulating coatings, and the step of preparing the insulating layer on the preparation surface specifically includes: preparing the insulating coating on the preparation surface in multiple times, wherein the thickness of any insulating coating is greater than or equal to 15μm and less than or equal to 40μm.

[0035] In this design, the insulating layer includes a ceramic insulating layer, which is prepared by multiple layers of insulating coating. Specifically, the insulating coating is prepared on the preparation surface multiple times, that is, the insulating coating is printed or sprayed layer by layer, so as to avoid cracking of the insulating layer during a single sintering and baking process, and also avoid defects that occur during the preparation process. Furthermore, the thickness of each layer of insulating coating is greater than or equal to 15μm and less than or equal to 40μm, that is, the thickness of the insulating coating prepared in a single time is between 15μm and 40μm.

[0036] In some possible designs, before the step of preparing the graphene heating layer on the insulating layer, the step further includes: preparing a conductive layer on the side of the insulating layer facing away from the substrate, wherein the conductive layer is located between the insulating layer and the graphene heating layer.

[0037] In this design, before preparing the graphene heating layer on the insulating layer, a conductive layer is prepared on the insulating layer, and then the graphene heating layer is prepared, so that the graphene heating layer is connected to the conductive layer, and then the graphene heating layer is energized, so that the graphene heating layer generates heat after being energized, thereby realizing the heating function of the graphene heating film assembly.

[0038] In some possible designs, the conductive layer includes a silver conductive layer, and the step of preparing the conductive layer on the side of the insulating layer facing away from the substrate specifically includes: on the side of the insulating layer facing away from the substrate, using silver paste to sinter to form the silver conductive layer, wherein the sintering temperature is less than or equal to 500°C.

[0039] In this design, the steps of preparing the conductive layer specifically include sintering the silver paste at a sintering temperature less than or equal to 500 °C to form a silver conductive layer. The limitation of the sintering temperature can prevent the silver paste from penetrating into the insulating layer due to high temperature and affecting the performance of the insulating layer, thereby avoiding breakdown of the substrate.

[0040] In some possible designs, the part of the conductive layer exposed to the graphene heating layer has a chamfer design. Specifically, the edge of the part of the conductive layer exposed to the graphene heating layer has a certain curvature, which can effectively prevent corona discharge from occurring after the graphene heating layer is powered on, and further avoid the phenomenon of the substrate being electrically broken down under high-voltage power-on.

[0041] In some possible designs, the silver conductive layer includes a binder containing Bi element; the weight percentage of Bi element is greater than or equal to 15% and less than or equal to 30%; the silver conductive layer also includes Ag element, Si element and Zn element; the weight percentage of Ag element is greater than or equal to 15% and less than or equal to 25%; the weight percentage of Si element is greater than or equal to 5% and less than or equal to 10%; the weight percentage of Zn element is greater than or equal to 1% and less than or equal to 5%.

[0042] In this design, the silver conductive layer includes Bi element to reduce the sintering temperature of the silver paste, thereby preventing the silver paste from penetrating into the insulating layer due to high-temperature sintering. Specifically, the weight percentage of Bi element in the binder is greater than or equal to 15% and less than or equal to 30%. The silver conductive layer also includes Ag (silver) element, Si (silicon) element and Zn (zinc) element, ensuring the conductivity of the silver conductive layer. Specifically, the weight percentage of Ag element is greater than or equal to 15% and less than or equal to 25%; the weight percentage of Si element is greater than or equal to 5% and less than or equal to 10%; the weight percentage of Zn element is greater than or equal to 1% and less than or equal to 5%.

[0043] In some possible designs, the method for preparing the graphene heating film assembly further includes: preparing a protective layer on the side of the graphene heating film facing away from the conductive layer.

[0044] In this design, the method for preparing the graphene heating film assembly further includes preparing a protective layer on the graphene heating layer to protect the graphene heating layer against water, scratches and insulation.

[0045] According to the third aspect of the present application, a cooking appliance is further provided, including: the graphene heating film assembly as described in any one of the first aspect. Therefore, it has all the beneficial effects of the graphene heating film assembly, which will not be elaborated here.

[0046] The additional aspects and advantages of the present invention will become apparent in the following description section or be understood through the practice of the present invention. Description of the Drawings

[0047] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of embodiments in conjunction with the accompanying drawings, in which:

[0048] Figure 1 The structural schematic diagram of a graphene heating film assembly according to an embodiment of the present invention is shown;

[0049] Figure 2 Shown is Figure 1 The cross-sectional view at region 1 of the graphene heating film assembly of the shown embodiment;

[0050] Figure 3 Shown is Figure 1 The cross-sectional view at region 2 of the graphene heating film assembly of the shown embodiment;

[0051] Figure 4 The microscopic structural schematic diagram between the substrate and the insulating layer according to an embodiment of the present invention is shown;

[0052] Figure 5 The process schematic diagram of the preparation method of the graphene heating film assembly according to an embodiment of the present invention is shown.

[0053] Wherein, Figures 1 to 4 The corresponding relationship between the reference numerals and the component names in the drawings is as follows:

[0054] 1 Substrate, 10 Preparation surface, 2 Insulating layer, 3 Graphene heating layer, 4 Conductive layer, 5 Protective layer. Detailed embodiments

[0055] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments may be combined with each other.

[0056] Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0057] The following refers to Figures 1 to 5 Describe a graphene heating film assembly, a preparation method thereof and a cooking appliance according to some embodiments of the present invention.

[0058] As Figure 1 , Figure 2 And Figure 3 Shown, according to an embodiment of the present invention, the present invention provides a graphene heating film assembly, including: a substrate 1, an insulating layer 2 and a graphene heating layer 3.

[0059] Specifically, the substrate 1 includes a preparation surface 10, and the roughness value of the preparation surface 10 is less than or equal to a roughness threshold. The insulating layer 2 is disposed on the preparation surface 10. The graphene heating layer 3 is disposed on a side of the insulating layer 2 away from the substrate 1.

[0060] The graphene heating film assembly provided by the present invention includes a substrate 1, and an insulating layer 2 and a graphene heating layer 3 sequentially disposed on the preparation surface 10 of the substrate 1. The graphene heating layer 3 is a heating component, which can utilize the resistance of the graphene heating material to heat after being powered on. The graphene heating layer 3 has a relatively high heating efficiency, which can improve the heating efficiency of the graphene heating film assembly. The insulating layer 2 is disposed between the graphene heating layer 3 and the substrate 1, which can improve the insulation performance of the substrate 1 and ensure the safety performance of the device using the graphene heating film assembly. Among them, as Figure 4 shown, the roughness value of the preparation surface 10 is less than or equal to the roughness threshold, so that the roughness value of the preparation surface 10 is relatively low, that is, the preparation surface 10 is relatively flat. Furthermore, when the insulating layer 2 is disposed on the preparation surface 10, the thickness of the insulating layer 2 can be ensured to be consistent and there is no weak area, thereby avoiding the situation that the substrate 1 is broken down when the graphene heating film assembly works.

[0061] In a specific application, the roughness of the substrate 1 is processed so that the roughness value of the preparation surface 10 is less than or equal to the roughness threshold. Among them, the roughness processing of the preparation surface 10 includes polishing the preparation surface 10.

[0062] Specifically, the substrate 1 can be a single part, such as a plate or other structures. At the same time, the substrate 1 can also be a heating container such as a cooking pot, that is, this kind of graphene heating film assembly can exist independently of the heating container or can be directly formed on the heating container.

[0063] According to some embodiments of the present application, the roughness threshold is greater than 0 and less than or equal to 10 μm.

[0064] In this embodiment, the roughness threshold is set between 0 and 10 μm, so that the roughness value of the preparation surface 10 is relatively small, making the preparation surface 10 relatively flat. In this way, when the insulating layer 2 is prepared on the preparation surface 10, the thickness of the insulating layer 2 at each position can be relatively uniform, and there will be no weak points, thereby avoiding the situation of being broken down during operation.

[0065] In a specific application, the roughness threshold is equal to any value among 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, and 9 μm.

[0066] According to some embodiments of the present application, the insulating layer 2 includes a ceramic insulating layer, and the thermal expansion coefficient of the ceramic insulating layer is greater than 0 and less than or equal to 1×10 -6 K.

[0067] In this embodiment, the insulating layer 2 includes a ceramic insulating layer that can withstand high temperatures. At the same time, the coefficient of thermal expansion of the ceramic insulating layer is set to be less than or equal to 1×10 -6 K, so that the coefficient of thermal expansion of the ceramic insulating layer is small, and thus it is adapted to the coefficient of thermal expansion of the substrate 1, avoiding a too large difference in the coefficient of thermal expansion between the ceramic insulating layer and the substrate 1, which may cause the ceramic insulating layer to fall off or crack, thereby ensuring the reliability of the ceramic insulating layer.

[0068] In a specific application, the substrate 1 includes glass-ceramics, and the ceramic insulating layer includes a flaky boron nitride layer.

[0069] In this embodiment, the flaky boron nitride layer contains a boron nitride material with flaky characteristics (microscopically characterized). On the one hand, boron nitride has high thermal conductivity and high electrical insulation, so its insulation performance can be ensured by itself, avoiding electrical breakdown. At the same time, the flaky morphology is conducive to forming a "layer-by-layer barrier" effect, increasing the current transmission path, and thus further greatly reducing the breakdown effect of high-voltage electricity.

[0070] Furthermore, the flaky boron nitride layer is prepared from a boron nitride material including a plurality of flaky structures, and along the transverse section of the flaky boron nitride layer, there is an overlap between adjacent two flaky structures.

[0071] In this embodiment, the insulating layer includes a flaky boron nitride layer, which is prepared from a boron nitride material including a plurality of flaky structures (boron nitride flakes), and along the transverse section of the flaky boron nitride layer, there is an overlap between adjacent two flaky structures, that is, there is no gap (seamless) between adjacent two boron nitride flakes and they partially overlap. Such a setting can make the insulating layer form a mutual stacking between layers up and down, thereby increasing the current transmission path and further reducing the breakdown effect of high-voltage electricity.

[0072] Furthermore, in the flaky boron nitride layer, the weight percentage of boron element is 20%-40%.

[0073] In this embodiment, in the flaky boron nitride layer, the weight percentage of boron element is 20%-40% (the lateral dimension of the insulating layer). Among them, when the weight percentage of boron element is less than 20%, the amount of boron nitride is insufficient. From the lateral cross-section of the insulating layer, effective gapless lap joints cannot be formed between boron nitride flakes, resulting in the sheet layer gap being electrically broken down as a weak point. Since boron nitride itself is powdery and has no adhesiveness to substrates such as glass-ceramics, when the weight percentage of boron element is higher than 40%, the contents of film-forming agent, leveling agent, and binder in the insulating layer slurry are too low, resulting in uneven surface thickness and powder shedding after sintering of the insulating layer. Therefore, setting the weight percentage of boron element within the range of 20%-40% can ensure effective gapless lap joints between boron nitride flakes, thereby avoiding the formation of a weak structure in the insulating layer that is easily broken down. At the same time, this setting can ensure the contents of film-forming agent, leveling agent, and binder in the insulating layer slurry, thereby improving the adhesiveness between the insulating layer and the substrate, and thus avoiding uneven surface thickness and powder shedding after sintering of the insulating layer.

[0074] According to some embodiments of the present application, the thickness of the insulating layer 2 is greater than or equal to 45 μm and less than or equal to 200 μm.

[0075] In this embodiment, if the thickness of the insulating layer 2 is too thick, the manufacturing cost is increased and it is easy to fall off. If the thickness of the insulating layer 2 is too thin, the insulating performance is reduced. Therefore, setting the thickness of the insulating layer 2 between 45 μm and 200 μm can not only ensure the insulating performance of the insulating layer 2 but also reduce the cost.

[0076] Specifically, when the thickness of the insulating layer 2 is less than 45 μm, the withstand voltage of the insulating layer 2 is insufficient and breakdown will occur at a voltage of 3000V. When the thickness of the insulating layer 2 is greater than 200 μm, the insulating layer 2 is too thick and there is internal stress, and microcracks are likely to occur during thermal shock and cold shock, resulting in breakdown of the insulating layer 2. In addition, the thicker insulating layer 2 also has a high cost. Therefore, it is better to set the insulating layer 2 between 45 μm and 200 μm.

[0077] In specific applications, the thickness of the insulating layer 2 is between 90 μm and 150 μm. Specifically, the thickness of the insulating layer 2 is any value among 100 μm, 110 μm, 120 μm, 130 μm, and 140 μm.

[0078] According to some embodiments of the present application, the insulating layer 2 includes multiple insulating coatings, and the thickness of any insulating coating is greater than or equal to 15 μm and less than or equal to 40 μm.

[0079] In this embodiment, the insulating layer 2 includes multiple insulating coatings, that is, the insulating layer 2 has a multi-layer structure. The thickness of each insulating coating should not be too thick, as this is not conducive to the preparation of each insulating coating. If it is too thin, the number of preparation times increases, thereby increasing the manufacturing cost. Therefore, the thickness of any insulating coating is set to be greater than or equal to 15 μm and less than or equal to 40 μm, which is not likely to cause coating damage and ensures the insulation effect of the insulating layer 2.

[0080] In specific applications, the thickness of any insulating coating is equal to any value among 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, 25 μm, 26 μm, 28 μm, 30 μm, 32 μm, 35 μm, and 38 μm.

[0081] It should be noted that the insulating layer 2 is prepared from an insulating slurry, which contains organic substances such as film-forming agents, leveling agents, and binders required for printing, as well as water. During sintering and curing, the organic substances decompose at high temperatures, and the water evaporates at high temperatures. When the thickness of the insulating layer 2 is relatively large, the organic substances and moisture in the upper and middle parts of the insulating layer 2 first decompose and evaporate, and then sinter and cure. At this time, the decomposition of the organic substances and the evaporation of the moisture at the bottom of the insulating layer 2 have not been completed, and due to the curing of the upper and middle parts, a large resistance is encountered, resulting in bubbling and cracking of the insulating layer 2, seriously affecting the insulation performance. In this application, the insulating layer 2 is formed into a multi-layer structure through multiple processing steps. Moreover, each time of processing, the printing thickness is between 15 micrometers and 40 micrometers, which can ensure that the organic substances and moisture in the insulating slurry are completely discharged without causing coating damage.

[0082] In specific applications, the number of the multiple insulating coatings is greater than or equal to 2 layers and less than or equal to 5 layers.

[0083] Furthermore, the multi-layer structure of the insulating layer 2 is formed by sequentially processing layer by layer. That is, the insulating layer 2 is formed into a multi-layer structure through multiple processing steps. Specifically, the multi-layer structure of the insulating layer 2 is formed through successive processing. Specifically, the bottom layer structure is first processed on the substrate 1, then the second layer structure is processed on the bottom layer structure, and then the third layer structure is processed until the structure of the required number of layers is processed. Through multiple processing and forming, it can ensure that the organic substances and moisture in the insulating slurry are completely discharged without causing coating damage.

[0084] Furthermore, each layer structure of the insulating layer 2 is formed by curing after printing. Among them, for each layer structure of the insulating layer 2, the slurry of the insulating layer 2 can be coated on the previous coating or the substrate 1 by means of screen printing or the like, and after each layer is coated to the required thickness, the current processed layer is cured through processes such as curing and sintering.

[0085] Such as Figure 1 and Figure 2As shown, according to some embodiments of the present application, the graphene heating film assembly further includes: a conductive layer 4.

[0086] Specifically, the conductive layer 4 is located on the insulating layer 2, and the conductive layer is connected to the graphene heating layer 3. The conductive layer 4 is located on at least one side of the graphene heating layer 3, or the conductive layer 4 is located on at least two opposite sides of the graphene heating layer 3 to supply power to the graphene heating layer 3.

[0087] In this embodiment, the conductive layer 4 is disposed on the insulating layer 2 and is located on at least one side of the graphene heating layer 3. Further, or the conductive layer 4 is located on at least two opposite sides of the graphene heating layer 3. For example, the conductive layer 4 is located on the left and right opposite sides of the graphene heating layer 3 or the conductive layer 4 is located on the front and back opposite sides of the graphene heating layer 3. Of course, the conductive layer 4 can also be disposed on the front, back, left, and right sides of the graphene heating layer 3. In actual process, among the conductive layers 4 disposed on two opposite sides, one conductive layer 4 is the positive electrode and the other conductive layer 4 is the negative electrode.

[0088] According to some embodiments of the present application, the conductive layer 4 includes a silver conductive layer or a copper electrode.

[0089] In this embodiment, the conductive layer 4 includes a silver conductive layer or a copper electrode, and the silver conductive layer or the copper electrode has good conductivity. Among them, when the conductive layer 4 includes a silver conductive layer, the sintering temperature of the silver conductive layer is less than or equal to 500 °C to prevent the silver conductive layer from penetrating into the insulating layer 2 and affecting the insulation performance of the insulating layer 2.

[0090] According to some embodiments of the present application, the silver conductive layer includes a binder containing Bi element. Among them, the weight percentage of the Bi element is greater than or equal to 15% and less than or equal to 30%.

[0091] In this embodiment, the silver conductive layer includes a binder containing Bi element (bismuth element). The weight percentage of the Bi element in the silver paste is greater than or equal to 15% and less than or equal to 30% to reduce the sintering temperature of the silver conductive layer.

[0092] In specific applications, the weight percentage of the Bi element in the binder is any value among 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%.

[0093] According to some embodiments of the present application, the silver conductive layer further includes Ag element, Si element and Zn element.

[0094] Specifically, the weight percentage of the Ag element is greater than or equal to 15% and less than or equal to 25%. The weight percentage of the Si element is greater than or equal to 5% and less than or equal to 10%. The weight percentage of the Zn element is greater than or equal to 1% and less than or equal to 5%.

[0095] In this embodiment, the silver conductive layer further includes Ag (silver), Si (silicon), and Zn (zinc) elements, which ensure the electrical conductivity of the silver conductive layer. Specifically, the weight percentage of the Ag element is greater than or equal to 15% and less than or equal to 25%; the weight percentage of the Si element is greater than or equal to 5% and less than or equal to 10%; the weight percentage of the Zn element is greater than or equal to 1% and less than or equal to 5%.

[0096] In specific applications, the weight percentage of the Ag element is any value among 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, and 24%; the weight percentage of the Si element is any value among 6%, 7%, 8%, and 9%; the weight percentage of the Zn element is any value among 2%, 3%, and 4%.

[0097] As Figure 2 and Figure 3 shown, according to some embodiments of the present application, the graphene heating film assembly further includes: a protective layer 5.

[0098] Among them, the protective layer 5 is disposed on the top of the graphene heating layer 3, that is, on the side of the graphene heating layer 3 facing away from the conductive layer 4.

[0099] In this embodiment, the protective layer 5 can protect the graphene heating layer 3 to play a role in waterproofing, insulation, and preventing scratching damage.

[0100] Specifically, the protective layer 5 can be prepared into an insulating protective layer 5 through an insulating material to avoid product leakage.

[0101] According to some embodiments of the present application, the substrate 1 includes a microcrystalline panel.

[0102] In this embodiment, when the graphene heating layer 3 on the microcrystalline glass is heated at a high temperature, it can penetrate through the glass to generate infrared radiation. Moreover, the microcrystalline glass is a good electrical insulator at room temperature, which ensures the safety performance of the graphene heating film assembly. In addition, microcrystalline glass is relatively common, so it is easier to purchase and the cost will be relatively low.

[0103] Furthermore, the substrate 1, the insulating layer 2, the conductive layer 4, the graphene heating layer 3, and the protective layer 5 are of an integral structure.

[0104] According to an embodiment of the present invention, a preparation method of a graphene heating film assembly is also proposed for the graphene heating film assembly. Among them, the graphene heating film assembly includes a substrate, and the substrate includes a preparation surface.

[0105] As Figure 5 shown, a schematic flow diagram of a preparation method of the graphene heating film assembly is shown:

[0106] Step 102: Perform roughness treatment on the substrate so that the roughness value of the preparation surface is less than or equal to the roughness threshold;

[0107] Step 104: Prepare an insulating layer on the preparation surface;

[0108] Step 106: Prepare a graphene heating layer on the insulating layer.

[0109] The method for preparing the graphene heating film assembly provided by the present application includes: performing roughness treatment on the substrate so that the roughness value of the preparation surface of the substrate is less than or equal to the roughness threshold, and then preparing an insulating layer on the preparation surface so that the thickness of each position of the insulating layer is consistent, thereby not generating weak areas and ensuring the insulation performance of the insulating layer. After the insulating layer is prepared, a graphene heating layer is prepared on the insulating layer, and heating is achieved through the graphene heating layer.

[0110] It should be noted that during the process of performing roughness treatment on the substrate, at least the preparation surface is subjected to roughness treatment, that is, other surfaces of the substrate can also be subjected to roughness treatment together, so as to reduce the roughness of other surfaces of the substrate together with the preparation surface.

[0111] It can be understood that performing roughness treatment on the substrate includes performing grinding and / or polishing treatment on the substrate to at least make the roughness value of the preparation surface less than or equal to the roughness threshold.

[0112] In some possible designs, the step of performing roughness treatment on the substrate so that the roughness value of the preparation surface is less than or equal to the roughness threshold specifically includes: performing roughness treatment on the substrate so that the roughness value of the preparation surface is greater than 0 and less than or equal to 10 μm.

[0113] In this design, the roughness value of the preparation surface is greater than 0 and less than or equal to 10 μm, so that the roughness value of the preparation surface is relatively small and the preparation surface is relatively flat. In this way, when preparing the insulating layer on the preparation surface, the thickness of the insulating layer at each position can be relatively uniform, without weak points, thereby avoiding the situation of being broken down during operation.

[0114] According to some embodiments of the present application, the insulating layer includes a ceramic insulating layer, and the ceramic insulating layer includes multiple insulating coatings. The step of preparing the insulating layer on the preparation surface specifically includes: preparing the insulating coatings on the preparation surface in multiple times.

[0115] Wherein, the thickness of any insulating coating is greater than or equal to 15 μm and less than or equal to 40 μm.

[0116] In this embodiment, the insulating layer includes a ceramic insulating layer, and the ceramic insulating layer is prepared by multiple layers of insulating coating. Specifically, the insulating coating is prepared on the preparation surface multiple times, that is, the insulating coating is printed or sprayed layer by layer, so as to avoid cracking of the insulating layer during a single sintering and baking process, and also to avoid defects occurring during the preparation process. Furthermore, the thickness of each layer of insulating coating is greater than or equal to 15 μm and less than or equal to 40 μm, that is, the thickness of the insulating coating prepared in a single time is between 15 μm and 40 μm.

[0117] It should be noted that the insulating layer is prepared from an insulating slurry, and the insulating slurry contains organic substances and water such as film-forming agents, leveling agents and adhesives required for printing. During sintering and curing, the organic substances decompose at high temperature and the water evaporates at high temperature. When the thickness of the insulating layer is large, the organic matter and water in the upper and middle parts of the insulating layer are first decomposed and evaporated, and sintered and cured. At this time, the decomposition of organic matter and the evaporation of water at the bottom of the insulating layer have not been completed, and due to the curing of the upper and middle parts, they encounter greater resistance, causing bubbling and cracking of the insulating layer, which seriously affects the insulation. In the present application, the insulating layer is formed into a multilayer structure through multiple processing, and the printing thickness is between 15 microns and 40 microns during each processing, which can ensure that the organic matter and water in the insulating slurry are completely discharged without causing damage to the coating.

[0118] In a specific application, the number of the multi-layer insulating coating is greater than or equal to layers, and less than or equal to layers.

[0119] Furthermore, the multilayer structure of the insulating layer is formed by processing the structure layer by layer in sequence. That is, the insulating layer is formed into a multilayer structure through multiple processing. Specifically, the multilayer structure of the insulating layer is formed by sequential processing, specifically, first processing the bottom layer structure on the substrate, then processing the second layer structure on the bottom layer structure, and then processing the third layer structure until the structure with the required number of layers is processed. And through multiple processing and forming, it can be ensured that the organic matter and moisture in the insulating slurry are completely discharged without causing damage to the coating.

[0120] Furthermore, each layer structure of the insulating layer is formed by curing after printing. In particular, each layer structure of the insulating layer can be formed by first coating the slurry of the insulating layer on the previous coating layer or the substrate by screen printing or the like, and after each layer is coated to a desired thickness, curing and sintering or the like are performed to cure the current processing layer.

[0121] According to some embodiments of the present application, before the step of preparing the graphene heating layer on the insulating layer, the step further includes: preparing a conductive layer on the side of the insulating layer facing away from the substrate.

[0122] Among them, the conductive layer is located between the insulating layer and the graphene heating layer.

[0123] In this embodiment, before preparing the graphene heating layer on the insulating layer, a conductive layer is prepared on the insulating layer, and then the graphene heating layer is prepared, so that the graphene heating layer is connected to the conductive layer, thereby realizing the energization of the graphene heating layer, causing the graphene heating layer to generate heat after being energized, and realizing the heating function of the graphene heating film assembly.

[0124] According to some embodiments of the present application, the conductive layer includes a silver conductive layer. The step of preparing the conductive layer on the side of the insulating layer facing away from the substrate specifically includes: on the side of the insulating layer facing away from the substrate, using silver paste to sinter to form a silver conductive layer, wherein the sintering temperature is less than or equal to 500 °C.

[0125] In this embodiment, the step of preparing the conductive layer specifically includes sintering the silver paste at a sintering temperature of less than or equal to 500 °C to form a silver conductive layer. The limitation of the sintering temperature can prevent the silver paste from penetrating into the insulating layer due to high temperature and affecting the performance of the insulating layer, thereby avoiding breakdown of the substrate.

[0126] According to some embodiments of the present application, the silver conductive layer includes a binder containing Bi element, and the silver conductive layer also includes Ag element, Si element and Zn element.

[0127] Among them, the weight percentage of the Bi element is greater than or equal to 15% and less than or equal to 30%. The weight percentage of the Ag element is greater than or equal to 15% and less than or equal to 25%. The weight percentage of the Si element is greater than or equal to 5% and less than or equal to 10%. The weight percentage of the Zn element is greater than or equal to 1% and less than or equal to 5%.

[0128] In this embodiment, the silver conductive layer includes the Bi element to reduce the sintering temperature of the silver paste, thereby preventing the silver paste from penetrating into the insulating layer due to high-temperature sintering. Specifically, the weight percentage of the Bi element in the binder is greater than or equal to 15% and less than or equal to 30%. The silver conductive layer also includes Ag (silver) element, Si (silicon) element and Zn (zinc) element, ensuring the electrical conductivity of the silver conductive layer. Specifically, the weight percentage of the Ag element is greater than or equal to 15% and less than or equal to 25%; the weight percentage of the Si element is greater than or equal to 5% and less than or equal to 10%; the weight percentage of the Zn element is greater than or equal to 1% and less than or equal to 5%.

[0129] In specific applications, the weight percentage of Bi element in the binder is any value among 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%. The weight percentage of Ag element is any value among 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%; the weight percentage of Si element is any value among 6%, 7%, 8%, 9%; the weight percentage of Zn element is any value among 2%, 3%, 4%.

[0130] According to some embodiments of the present application, the method for preparing the graphene heating film assembly further includes: preparing a protective layer on the side of the graphene heating film facing away from the conductive layer.

[0131] In this embodiment, the method for preparing the graphene heating film assembly further includes preparing a protective layer on the graphene heating layer to protect the graphene heating layer against water, scratches, and insulation, etc.

[0132] According to the third aspect of the present application, a cooking appliance is further provided, including: the graphene heating film assembly as proposed in any one of the above embodiments. Therefore, it has all the beneficial effects of the graphene heating film assembly, which will not be elaborated here.

[0133] It should be noted that the cooking appliance includes a rice cooker, a food processor, etc.

[0134] In specific applications, an insulating layer 2 needs to be constructed between the glass-ceramics and the graphene heating film, and its structure is as Figure 1 shown. The schematic diagram of the overall graphene heating film assembly is as Figure 2 shown. The graphene heating film assembly from bottom to top is respectively: glass-ceramics, insulating layer 2, silver electrode (i.e., silver conductive layer), graphene heating layer 3, and protective layer 5. In this structure, it is required to ensure the surface insulation stability of the overall structure without weak areas. However, when the glass-ceramic panel is produced by the rolling method, there are usually bumps on the back (process marks left by the rolling method). The existence of the bumps will cause weak points in the insulating coating, resulting in the breakdown of the insulating layer 2 at this position. Therefore, before making the insulating layer 2 on the substrate 1, we need to polish the substrate 1. The treated substrate 1 is as Figure 4 shown, with the back surface ground flat and the roughness Rz≤10um, the smaller the better. At this time, there will be no weak points in the printed insulating layer 2 on this basis.

[0135] Furthermore, in order to overcome the decrease in insulation performance of the microcrystalline panel at high temperatures, which cannot meet the safety requirements of small household appliances, an insulating layer 2 is added between the microcrystalline panel and the graphene heating layer 3. When the back surface of the substrate 1 is ground flat to ensure that the thickness of the insulating layer 2 is consistent and there are no weak points, the selection of the insulating layer 2 is also crucial. Considering that the product needs to be used under the condition of 350 °C heat generation, it is basically impossible to select polymer insulating materials. When selecting a ceramic insulating material, the difference in thermal expansion coefficient between the insulating material and the substrate 1 needs to be considered. When the difference in thermal expansion coefficient between the ceramic insulating material and the substrate 1 is too large, under the condition of rapid heating and cooling, the thermal stress caused by the inconsistent thermal expansion coefficient is likely to lead to cracking, peeling, etc. of the insulating coating, resulting in weak points in the insulating coating and thus losing the insulating effect. Considering the thermal expansion coefficient of the glass-ceramics, the thermal expansion coefficient of the ceramic insulating coating is suitable between 0 - 1×10 -6 K. In addition to the thermal expansion coefficient of the ceramic coating itself, the process of preparing the ceramic coating on the microcrystalline panel is also very crucial. There are certain requirements for the thickness of the ceramic insulating layer, which cannot be too thin or too thick. Usually, it is between 45 μm - 200 μm, and the optimal range is between 90 μm - 150 μm. During the preparation process, a ceramic insulating coating with a certain thickness cannot be printed or sprayed on at one time. This is because there are two problems with a ceramic coating printed or sprayed on at one time: 1. Defects that occur during the preparation process cannot be avoided; 2. If printed too thick at one time, it is very easy to crack during the sintering and baking process. The ceramic insulating coating is usually prepared in multiple times, and the single thickness is between 15 μm - 40 μm.

[0136] After the printing of the insulating layer 2 is completed, the selection of the conductive silver paste is also crucial. A silver paste conductive layer 4 is screen-printed on the insulating ceramic coating, and the permeability of the silver paste needs to be considered. The characteristics of the silver paste show that it has a certain penetration effect at high temperatures. When the silver paste penetrates into the insulating layer 2, under the state of high temperature and high pressure, the performance of the insulating layer 2 decreases and electrical breakdown is likely to occur. In order to eliminate the influence of the silver paste on the insulating layer 2, usually, we need to limit the sintering temperature of the silver paste ≤ 500 °C. In order to reduce the sintering temperature of the silver paste, we usually choose a Bi-containing glass powder as the binder in the slurry binder, and the content of the Bi element is between 15 wt% - 30 wt%. The remaining elements in the silver paste are C, Ag, Si, O, Zn, and other minor impurities. Among them, the Ag content is between 15 wt% - 25 wt%, the Si content is between 5 wt% - 10 wt%, and the Zn content is between 1 wt% - 5 wt%.

[0137] Test method:

[0138] 1. Initial electrical insulation: The insulation of the graphene heating film assembly should be able to withstand a test voltage of 50 Hz and 3000 V for 1 minute. During the test, there should be no flashover or breakdown; after the test, the graphene heating film assembly can work normally.

[0139] 2. High-temperature electrical insulation: The graphene heating film component on the microcrystalline panel should be able to withstand a test voltage of 50 Hz and 3000 V at the working temperature (350 °C) for 1 minute, and there should be no flashover or breakdown during the test (leakage current < 100 mA); after the test, the graphene heating component on the microcrystalline panel can work normally.

[0140] 3. Thermal shock: Put the ceramic plate of the graphene heating film component into an incubator at a constant temperature of 350 °C. After reaching thermal equilibrium, take it out and cool it to room temperature with a fan. Repeat 20 times. The graphene heating film component can pass the electrical insulation test and heat normally.

[0141] Embodiment solutions:

[0142] Embodiment 1: The plane of the graphene screen-printed on the substrate 1 is ground flat. The thickness of the insulating layer 2 is 120 μm. Flaky boron nitride is selected, and its thermal expansion coefficient is 0.6×10 -6 K. The 120-μm-thick insulating coating is printed in 4 times, 30 μm each time. The sintering temperature of the silver paste is 450 °C.

[0143] Embodiment 2: The plane of the graphene screen-printed on the substrate 1 is ground flat. The thickness of the insulating layer 2 is 60 μm. Flaky boron nitride is selected, and its thermal expansion coefficient is 0.6×10 -6 K. The 120-μm-thick insulating coating is printed in 3 times, 40 μm each time. The sintering temperature of the silver paste is 400 °C.

[0144] Comparative Example 1: The plane of the graphene screen-printed on the substrate 1 is uneven. The thickness of the insulating layer 2 is 120 μm. Flaky boron nitride is selected, and its thermal expansion coefficient is 0.6×10 -6 K. The 120-μm-thick insulating coating is printed in 3 times, 40 μm each time. The sintering temperature of the silver paste is 450 °C.

[0145] Comparative Example 2: The plane of the graphene screen-printed on the substrate 1 is ground flat. The thickness of the insulating layer 2 is 30 μm. Flaky boron nitride is selected, and its thermal expansion coefficient is 0.6×10 -6 K. The 30-μm-thick insulating coating is printed in 2 times, 15 μm each time. The sintering temperature of the silver paste is 450 °C.

[0146] Comparative Example 3: The plane of the graphene screen-printed on the substrate 1 is ground flat. The thickness of the insulating layer 2 is 120 μm. Alumina is selected, and its thermal expansion coefficient is 8.4×10 -6 K. The 120-μm-thick insulating coating is printed in 3 times, 40 μm each time. The sintering temperature of the silver paste is 450 °C.

[0147] Comparative Example 4: The surface of the substrate 1 printed with graphene was ground flat. The thickness of the insulating layer 2 was 120 μm. Flaky boron nitride was selected, and its coefficient of thermal expansion was 0.6×10 -6 K. The 120-μm-thick insulating coating was printed 2 times, 60 μm each time. The sintering temperature of the silver paste was 450 °C.

[0148] Comparative Example 5: The surface of the substrate 1 printed with graphene was ground flat. The thickness of the insulating layer 2 was 120 μm. Flaky boron nitride was selected, and its coefficient of thermal expansion was 0.6×10 -6 K. The 120-μm-thick insulating coating was printed in 4 times, 30 μm each time. The sintering temperature of the silver paste was 680 °C.

[0149] Table 1

[0150]

[0151] Among them, OK in Table 1 indicates passing the test, and NG indicates failing the test. From the above tests, it can be seen that in Example 1 and Example 2, before printing the insulating layer 2, the surface of the substrate 1 was polished to reduce its roughness, which could improve the performance of the graphene heating film assembly. Correspondingly, selecting an appropriate insulating layer thickness, a material with an appropriate coefficient of thermal expansion, and controlling the thickness of each printing and the sintering temperature of the silver paste could ensure the initial electrical insulation, high-temperature electrical insulation, thermal shock insulation, and the state of the insulating layer. From Comparative Example 1, it can be seen that printing graphene on an unpolished surface would reduce the high-temperature electrical insulation. From Comparative Example 2, it can be seen that too low a thickness of the insulating layer 2 would lead to a reduction in high-temperature electrical insulation. From Comparative Example 3, it can be seen that when the insulating layer was made of a material with a relatively large coefficient of thermal expansion, cracking would occur after thermal shock. From Comparative Example 4, it can be seen that too thick a thickness of the insulating layer 2 for each printing would reduce the high-temperature electrical insulation, thermal shock insulation, and was prone to cracking and bubbling. From Comparative Example 5, it can be seen that too high a sintering temperature of the silver paste would lead to a reduction in high-temperature electrical insulation.

[0152] In the present invention, the term "a plurality of" means two or more, unless otherwise clearly defined. Terms such as "mounted", "connected", "connected to", "fixed", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; "connected" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0153] In the description of this specification, the descriptions of terms such as "one embodiment", "some embodiments", "specific embodiments", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or instance. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0154] The foregoing is only the preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A graphene heating film assembly, It is characterized in that include: A substrate, the substrate comprising a preparation surface, the roughness value of the preparation surface being less than or equal to a roughness threshold; An insulating layer, disposed on the preparation surface; The graphene heating layer is arranged on a side of the insulating layer away from the substrate.

2. The graphene heating film assembly according to claim 1, It is characterized in that The roughness threshold is greater than 0 and less than or equal to 10 μm.

3. The graphene heating film assembly according to claim 1, It is characterized in that The insulating layer comprises a ceramic insulating layer, and the thermal expansion coefficient of the ceramic insulating layer is greater than 0 and less than or equal to 1×10 - 6 K.

4. The graphene heating film assembly according to claim 1, It is characterized in that The thickness of the insulating layer is greater than or equal to 45 μm and less than or equal to 200 μm.

5. The graphene heating film assembly according to claim 1, It is characterized in that The insulating layer includes multiple insulating coating layers, and the thickness of any layer of the insulating coating layer is greater than or equal to 15 μm and less than or equal to 40 μm.

6. The graphene heating film assembly according to any one of claims 1 to 5, It is characterized in that Also includes: A conductive layer is disposed on the insulating layer and connected to the graphene heating layer, and the conductive layer is located on at least one side of the graphene heating layer, or on at least two opposite sides of the graphene heating layer to supply power to the graphene heating layer.

7. The graphene heating film assembly according to claim 6, It is characterized in that The conductive layer includes a silver conductive layer or a copper electrode.

8. The graphene heating film assembly according to claim 7, It is characterized in that The silver conductive layer includes a binder containing Bi element; The weight percentage of the Bi element is greater than or equal to 15% and less than or equal to 30%.

9. The graphene heating film assembly according to claim 8, It is characterized in that The silver conductive layer also includes Ag element, Si element and Zn element; The weight percentage of the Ag element is greater than or equal to 15% and less than or equal to 25%; The weight percentage of the Si element is greater than or equal to 5% and less than or equal to 10%; The weight percentage of the Zn element is greater than or equal to 1% and less than or equal to 5%.

10. The graphene heating film assembly according to claim 6, It is characterized in that Also includes: A protective layer is arranged on a side of the graphene heating layer away from the conductive layer.

11. The graphene heating film assembly according to any one of claims 1 to 5, It is characterized in that The substrate includes a microcrystalline panel.

12. A method for preparing a graphene heating film assembly, for a graphene heating film assembly, wherein the graphene heating film assembly comprises a substrate, wherein the substrate comprises a preparation surface, It is characterized in that The preparation method comprises: Performing roughness treatment on the substrate so that the roughness value of the prepared surface is less than or equal to a roughness threshold; preparing an insulating layer on the preparation surface; A graphene heating layer is prepared on the insulating layer.

13. The method for preparing the graphene heating film assembly according to claim 12, It is characterized in that The step of performing roughness treatment on the substrate so that the roughness value of the prepared surface is less than or equal to a roughness threshold value specifically includes: The substrate is subjected to roughness treatment so that the roughness value of the prepared surface is greater than 0 and less than or equal to 10 μm.

14. The method for preparing the graphene heating film assembly according to claim 12, It is characterized in that The insulating layer includes a ceramic insulating layer, and the ceramic insulating layer includes a multi-layer insulating coating. The step of preparing the insulating layer on the preparation surface specifically includes: The insulating coating is prepared on the preparation surface in multiple steps. Wherein, the thickness of any of the insulating coatings is greater than or equal to 15 μm and less than or equal to 40 μm.

15. The method for preparing the graphene heating film assembly according to claim 12, It is characterized in that Before the step of preparing the graphene heating layer on the insulating layer, the method further comprises: A conductive layer is prepared on a side of the insulating layer facing away from the substrate, wherein the conductive layer is located between the insulating layer and the graphene heating layer.

16. The method for preparing the graphene heating film assembly according to claim 15, It is characterized in that The conductive layer comprises a silver conductive layer, and the step of preparing the conductive layer on the side of the insulating layer away from the substrate specifically comprises: On the side of the insulating layer away from the substrate, the silver conductive layer is formed by sintering silver paste, The sintering temperature is less than or equal to 500°C.

17. The method for preparing the graphene heating film assembly according to claim 16, It is characterized in that The silver conductive layer includes a binder containing Bi element; The weight percentage of the Bi element is greater than or equal to 15% and less than or equal to 30%; The silver conductive layer also includes Ag element, Si element and Zn element; The weight percentage of the Ag element is greater than or equal to 15% and less than or equal to 25%; The weight percentage of the Si element is greater than or equal to 5% and less than or equal to 10%; The weight percentage of the Zn element is greater than or equal to 1% and less than or equal to 5%.

18. The method for preparing the graphene heating film assembly according to claim 15, It is characterized in that Also includes: A protective layer is prepared on a side of the graphene heating film facing away from the conductive layer.

19. A cooking utensil, It is characterized in that include: A graphene heating film assembly as claimed in any one of claims 1 to 11.

Images