Highly heat-conductive heating element and method for manufacturing the same

Abstract

The application provides a high-thermal-conductivity heating element and a preparation method thereof. The high-thermal-conductivity heating element is prepared from first black silicon carbide powder, second black silicon carbide powder, flaky graphite, polyvinyl alcohol aqueous solution and a small amount of high-thermal-conductivity MgO sintering aid. The particle sizes of the first black silicon carbide powder and the second black silicon carbide powder are different, and the particle size ratio of the first black silicon carbide powder and the second black silicon carbide powder satisfies the Horsfield filling relationship. The application uses two silicon carbide powder raw materials with different particle size distributions, so that the D50 index satisfies the Horsfield filling relationship, the small-particle-size silicon carbide powder can be filled in the gaps formed by the particle accumulation of the large-particle-size silicon carbide powder, the forming density of the pressed silicon carbide heating sheet blank is improved, the requirement for realizing the densification of the heating sheet through the shrinkage of the later high-temperature sintering is reduced, the sintering temperature is reduced, and the loss of the flaky graphite in the sintering process is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat generating materials, in particular to a high-thermal-conductivity heating element and a preparation method thereof. BACKGROUND

[0002] At present, when growing artificial diamond single crystals using various ultra-high pressure devices such as cubic anvil and Belt, a high-temperature-high-pressure temperature gradient method is usually adopted, that is, the growth temperature and gradient of the diamond single crystal are precisely controlled by controlling the heating elements at different positions through a series of heating circuits in a high-temperature-high-pressure environment. However, the currently used heating elements have a series of problems. The conventional heating elements are composed of ZrO2 and graphite composite powder, and the preparation process thereof is prone to cause insufficient mechanical strength, and the container is easy to break during assembly. In addition, during the long-time single crystal growth process, ZrO2 reacts with graphite, which changes the resistance ratio and further affects the distribution of heating power. In addition, due to the non-uniform heat conduction of the heating element, the temperature field in the single crystal growth container cannot reach the ideal uniformity, which affects the high-quality growth of the diamond single crystal.

[0003] Based on the shortcomings of the prior art, there is an urgent need for a high-thermal-conductivity heating element and a preparation method thereof. SUMMARY

[0004] The present application aims to provide a high-thermal-conductivity heating element and a preparation method thereof to improve the above problems. In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0005] On the one hand, the present application provides a high-thermal-conductivity heating element, characterized in that the high-thermal-conductivity heating element is prepared from first black silicon carbide powder, second black silicon carbide powder, flaky graphite, polyvinyl alcohol aqueous solution and high-thermal-conductivity sintering aid, the particle sizes of the first black silicon carbide powder and the second black silicon carbide powder are different, and the particle size ratio of the first black silicon carbide powder and the second black silicon carbide powder satisfies the Horsfield filling relationship.

[0006] Further, the weight ratio of the first black silicon carbide powder, the second black silicon carbide powder, the flaky graphite, the polyvinyl alcohol aqueous solution and the sintering aid is 100:100:(6-20):(10-20):(10-12).

[0007] Further, the particle size of the first black silicon carbide powder is D50=5-10 microns, and the particle size of the second black silicon carbide powder is D50=15-25 microns.

[0008] Further, the particle size of the flaky graphite is D50=10-15 microns.

[0009] Further, the sintering aid is saturated magnesium acetate aqueous solution.

[0010] In a second aspect, the application further provides a preparation method of the high-thermal-conductivity heating element, and the method comprises the following steps:

[0011] The first black silicon carbide powder, the second black silicon carbide powder and the flaky graphite are mixed to obtain a first mixed powder;

[0012] According to the ratio of the mass of MgO generated after magnesium acetate decomposition to the total mass of MgO, graphite and silicon carbide, 5% of polyvinyl alcohol aqueous solution with a concentration of 5%-10% is weighed according to 5%-10% of the weight of the silicon carbide powder, and the polyvinyl alcohol aqueous solution and the magnesium acetate aqueous solution are simultaneously added to the first mixed powder to obtain a second mixed powder;

[0013] The second mixed powder is stirred, granulated and pressed to obtain a green compact round sheet by setting the forming pressure to 150-300 MPa;

[0014] The green compact round sheet is sintered to obtain a heating element.

[0015] The application has the following advantages:

[0016] The application uses two different particle size distribution silicon carbide powder raw materials, so that the D50 index meets the Horsfield filling relationship, so that the small particle size silicon carbide powder can be filled in the gap formed by the particle accumulation of the large particle size silicon carbide powder, thereby improving the forming density of the pressed silicon carbide heating sheet green compact, reducing the requirement for densification of the heating sheet through later high-temperature sintering shrinkage, thereby reducing the sintering temperature and avoiding the loss of flaky graphite during the sintering process. The application uses magnesium acetate as a sintering aid, which melts and decomposes to form MgO during sintering. Since the magnesium acetate is added to the silicon carbide-graphite raw material powder in the form of a solution during granulation, the MgO formed by decomposition has high reactivity and can be sintered at a relatively low sintering temperature lower than that of silicon carbide ceramics, and finally forms a space filament network connection, so that the sintered heating sheet has mechanical strength that meets the assembly requirements of the synthetic block.

[0017] Other features and advantages of the application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the application as described in the written description and claims. The objects and other advantages of the application will be realized and attained by the structure particularly pointed out in the written description and claims. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some of the embodiments of the present application, and therefore should not be regarded as a limitation to the scope. For those skilled in the art, other related drawings can also be obtained without creative labor.

[0019] Figure 1 is a schematic diagram of the placement mode in the green compact disc sintering in the embodiments of the present application;

[0020] Figure 2 is a flow chart of the preparation method of the high-thermal-conductivity heating element in the embodiments of the present application.

[0021] In the figure, the marks are as follows: 1, saggar; 2, saggar cover; 3, graphite powder; 4, first pad burning paper; 5, first graphite paper; 6, graphite ring; 7, green compact disc; 8, second graphite paper; 9, second pad burning paper. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to make a clear and complete description of the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of the present application. Embodiment 1

[0023] The present embodiment provides a high-thermal-conductivity heating element, which is prepared from five main raw materials, including first black silicon carbide powder, second black silicon carbide powder, flaky graphite, polyvinyl alcohol aqueous solution and high-thermal-conductivity sintering aid. The five raw materials together constitute the basic components of the heating element, and each raw material plays an important role in the performance and characteristics of the final element. The particle sizes of the first and second black silicon carbide powders are different, and at the same time, their particle size ratio is designed to meet the Horsfield packing relationship. This packing relationship ensures that the small-particle-size silicon carbide powder can be filled into the gaps of the large-particle-size silicon carbide powder particles, thereby improving the forming density of the heating sheet. Such treatment helps to reduce the shrinkage requirement at the later high-temperature sintering, and thus reduces the sintering temperature.

[0024] It is worth noting that in this embodiment, black silicon carbide is chosen as the main material instead of the traditional zirconia heating sheet. This is because black silicon carbide has very high thermal conductivity, electrical insulation and chemical stability. Among them, the high thermal conductivity ensures that the heating element can efficiently conduct heat when working, and its electrical insulation and chemical stability ensure the reliability of the element in high temperature-high pressure environment. In addition, black silicon carbide is used instead of other forms of silicon carbide because black silicon carbide has excellent insulation performance, which is crucial as an insulating material for the heating sheet substrate. This enables silicon carbide to effectively prevent electrical leakage and breakdown in a high-pressure environment, ensuring stable and reliable electrical performance of the element.

[0025] Further, the Horsfield model is a relatively simple and rough model that is based on the assumption of spherical particles. In practical applications, powders are often not spherical, especially in the case of ultra-fine powders, which are difficult to sieve because of the high cost of such operations. Therefore, the present patent takes into account the actual situation by measuring the particle size of the raw material powder obtained by ball milling or purchased using a powder particle size tester, ensuring that the D50 (median particle size) meets the design requirements. In practical applications, there may be a portion of particles in the raw material powder that are coarser than D50 or finer than D50, which does not affect its applicability. In fact, these two powders have been treated by ball milling and their particle size distribution has been measured by a powder particle size tester, with D50 being a basic parameter representing the particle size distribution of the powder. Therefore, the present patent takes into account the complexity of actual production, making the selection of raw materials more flexible while ensuring the performance requirements of the heating element.

[0026] Preferably, the weight ratio of the first black silicon carbide powder, the second black silicon carbide powder, the flaky graphite, the polyvinyl alcohol aqueous solution and the sintering aid is 100:100:(6-20):(10-20):(10-12). The balance of the first and second black silicon carbide powders, as well as their ratio to flaky graphite, enables the final heating element to strike a balance between thermal conductivity and mechanical properties. The introduction of the polyvinyl alcohol aqueous solution helps to meet the requirements of granulation and green strength and density. The content of the sintering aid can affect the sintering density and mechanical strength of the heating element.

[0027] Preferably, the particle size of the first black silicon carbide powder is D50=5-10 microns, and the particle size of the second black silicon carbide powder is D50=15-25 microns. This differentiated particle size selection may be to achieve better filling effect and microstructure control.

[0028] Preferably, the particle size of the flaky graphite is D50 = 10-15 microns. The flaky graphite is used as a heat-conducting material, and its unique flaky structure can provide an effective electrical and thermal conduction path. By controlling the particle size of the graphite, the size of the flakes can be adjusted to enhance the electrical and thermal conductivity of the final material.

[0029] Preferably, the sintering aid is a saturated magnesium acetate aqueous solution. The sintering aid magnesium acetate decomposes into high-thermal-conductivity MgO through melting during the sintering process, ultimately forming a spatial filamentous network connection, further improving the mechanical strength of the heating sheet. Embodiment 2:

[0030] The embodiment provides a preparation method of a high-thermal-conductivity heating element, comprising the following steps:

[0031] Step S100, mixing and processing the first silicon carbide powder, the second silicon carbide powder and the flaky graphite to obtain a first mixed powder.

[0032] It can be understood that the first silicon carbide powder and the second silicon carbide powder have different particle sizes to achieve better filling effect and meet the Horsfield filling relationship, which helps to improve the forming density of the green body. Such filling relationship can help to optimize the subsequent sintering step, thereby improving the performance of the heating element. The introduction of the flaky graphite increases the thermal conduction channel while meeting the heating requirement, and improves the overall thermal conductivity. The special structure of the flaky graphite provides an effective path for heat conduction, which helps to form a thermal conduction network. In this process, sufficient mixing is ensured to obtain a uniform raw material mixture, which helps to achieve uniform material distribution in the subsequent steps.

[0033] Step S200, a polyvinyl alcohol aqueous solution with a concentration of 5%-10% is weighed according to 5%-10% of the weight of the silicon carbide powder, and the polyvinyl alcohol aqueous solution and the saturated magnesium acetate aqueous solution are simultaneously added to the first mixed powder to obtain a second mixed powder, wherein the addition ratio of the magnesium acetate aqueous solution is: the mass ratio of MgO generated after the decomposition of magnesium acetate to the total mass of MgO, graphite and silicon carbide is 5%.

[0034] It can be understood that the purpose of this step is to achieve the adhesion between the powder particles by adding polyvinyl alcohol aqueous solution, to bond the powder particles together to form spherical particles with a diameter of tens of microns, which have high fluidity when dry-pressed, facilitating the flow of the powder under the forming pressure to ensure uniform density everywhere. At the same time, the addition of polyvinyl alcohol should be as little as possible to meet the adhesion, otherwise it will lead to too large pores and too large shrinkage during sintering, resulting in deformation. Through experimental verification, it is preferred to add polyvinyl alcohol aqueous solution with a concentration of 5%-10% at a ratio of 5%-10% of the weight of the silicon carbide powder. Further, this step is to uniformly add magnesium acetate, so it adopts the way of adding magnesium acetate aqueous solution, and the MgO generated by its decomposition realizes the modification of the second mixed powder. During high temperature process, the saturated magnesium acetate aqueous solution decomposes to produce MgO, which plays the role of sintering aid and helps to form a dense and mechanically heated element in the subsequent steps.

[0035] It should be noted that the amount of magnesium acetate added is controlled in a small amount to avoid significant negative impact on the thermal conductivity of the heating sheet. Since the thermal conductivity of MgO is relatively low, excessive addition may reduce the thermal conductivity of the heating sheet. However, in this patent, through the design principles of "high thermal conductivity sintering aid" and "a small amount of magnesium acetate has no significant effect on the thermal conductivity of the heating sheet", it is ensured that the heating sheet meets the mechanical strength requirement while maintaining high thermal conductivity.

[0036] It should be noted that this patent does not pursue to prepare a heating sheet with "excellent" mechanical strength like traditional high-density silicon carbide ceramic. On the contrary, the mechanical strength of the heating sheet meets the requirements of the assembly of the synthetic block, which is because in the application scenario of high temperature-high pressure synthesis, it is only necessary to ensure that the heating sheet can be easily assembled into the synthetic block, not scattered, not peeled, not dropped. Such design concept makes the preparation process more flexible, while meeting the needs in practical applications

[0037] Step S300, the second mixed powder is mixed, granulated and pressed, and a green compact round sheet is obtained by setting the forming pressure to 150-300 MPa.

[0038] It can be understood that the mixing granulation process can include spraying or compressing the mixture into granules to ensure the uniformity and consistency of the mixture. Next, the mixed and granulated material is subjected to pressing treatment by setting the forming pressure to 150-300 MPa to form the green compact round sheet. The selection of the forming pressure is targeted to improve the density of the green compact as much as possible under the premise of not generating green compact defects such as layering, cracking, and uneven density. Specifically, different granulation equipment or granulation methods can be used in the mixing granulation process, such as using a disc granulator, a drum granulator, etc.; or taking the steps of pre-pressing large pieces, drying, crushing, and passing through a 1-2 millimeter screen for manual granulation. By controlling the size and shape of the granules through granulation, good flowability of the raw material powder is achieved, and finally a green compact round sheet with ideal density is formed. Such processing steps help to ensure that high-quality heating elements are obtained in the subsequent sintering process.

[0039] Step S400, sintering the green compact round sheet to obtain a heating element.

[0040] It can be understood that by precisely controlling the sintering process, the conversion of the green compact round sheet to the final heating element is realized, ensuring the structural density and performance consistency of the element.

[0041] The high-thermal-conductivity heating element prepared by the above method is measured in real time by different synthesis cavities and high-temperature-high-pressure experiments, and the improvement effect of the radial temperature difference is as follows:

[0042] Table 1 Comparison of radial temperature difference improvement effect of high-thermal-conductivity heating element

[0043]

[0044] Test conditions:

[0045] Synthesis pressure: 5 GPa, synthesis temperature: 1380℃, temperature measurement point height: 15mm, catalyst alloy melt height: 20mm.

[0046] As can be seen from Table 1, when the catalyst alloy melt height is 20mm, at the height of 15mm at the top of the crystal bed, according to different test conditions, when the traditional graphite-ZrO2 heating sheet is used, the temperature difference between the center of the single crystal growth container and the inner wall of the container is 8-13℃; while using the high-thermal-conductivity heating element, the temperature difference between the center of the single crystal growth container and the inner wall of the container is only 3-6.5℃. It shows that by using the new heating sheet, the flatness of the isothermal surface in the single crystal growth container is significantly improved.

[0047] It should be noted that step S200 includes step S210, step S220, step S230, and step S240.

[0048] Step S210, the first black silicon carbide powder and the second black silicon carbide powder are subjected to a powder particle size regulation treatment, and the particle size thereof is adjusted to a preset range to obtain an adjusted raw material.

[0049] It can be understood that, for each silicon carbide powder, the particle size thereof is adjusted to a preset range by controlling the parameters of the powder particle size regulation treatment. The selection of this range is determined according to the design requirements and performance standards of the high-thermal-conductivity heating element, so as to ensure that the final adjusted raw material meets the design specifications.

[0050] Step S220, the adjusted raw material and flaky graphite are mixed by using a three-dimensional mixer to obtain a preliminary mixture.

[0051] It can be understood that the mixing process can adopt mechanical stirring, drum mixing or other appropriate mixing means to ensure uniform distribution of each component.

[0052] Step S230, the polyvinyl alcohol aqueous solution and the magnesium acetate aqueous solution are simultaneously added to the preliminary mixture to obtain a wet mixture by wetting the preliminary mixture.

[0053] It can be understood that this can be completed by stirring, pressing and crushing, or other appropriate means, so as to ensure that the polyvinyl alcohol aqueous solution and the magnesium acetate aqueous solution can fully cover and wet the silicon carbide powder and flaky graphite in the preliminary mixture.

[0054] Step S240, the wet mixture is granulated to obtain a second mixed powder.

[0055] It can be understood that the three-dimensional mixer is a device commonly used for mixing powders, and its unique motion trajectory helps to achieve more uniform mixing effect. The device usually has high-efficiency mixing performance and is suitable for multi-component, granular raw materials. The three-dimensional mixer enables the various components in the mixture to be fully mixed through multi-dimensional motion such as rotation, tumbling and swinging inside the device, but at the same time does not change the powder particle size and the mutual proportion relationship between different powder particle sizes, which helps to ensure the fixed proportion relationship between the flaky graphite addition amount and the resistance of the heating sheet.

[0056] It should be noted that step S400 includes step S410, step S420, step S430 and step S440.

[0057] Step S410, the green round sheet is subjected to a heating pretreatment, by placing the green round sheet in an industrial muffle furnace and gradually heating it to 400-450 degrees Celsius, and maintaining the temperature range for degumming treatment, the degumming time is 0.5-1 hour.

[0058] It can be understood that the purpose of this step is to remove the organic components in the green compact disc, so that it will not be cemented or produce gas in the subsequent high temperature treatment.

[0059] Step S420, the green compact disc is subjected to temperature sintering treatment, and the furnace temperature is raised to the final sintering temperature of 1400-1450 degrees Celsius through atmospheric sintering, and the temperature is kept in the temperature range for 2-3 hours.

[0060] It can be understood that the atmospheric atmosphere is used in the sintering process, that is, the atmosphere in the sintering furnace is atmospheric environment. This obviously reduces the actual production cost. However, in order to protect the added graphite from being burned in the atmospheric atmosphere, the sintering temperature should be as low as possible, preferably 1400-1450 degrees Celsius. It should be noted that the sintering of high-density silicon carbide is very difficult. However, if graphite is added, the added graphite in the green compact will react with air to generate carbon dioxide and volatilize. However, if the sintering is protected by atmosphere, vacuum sintering or vacuum hot pressing sintering will bring very high cost, therefore, the present patent adopts the method of loading the graphite powder in the sintering pot and placing the graphite paper on the top and bottom of the green compact, which realizes the atmospheric sintering of ordinary muffle furnace and greatly reduces the manufacturing cost. This series of operations aims to densify the green compact disc through high temperature treatment and form a heating element with excellent heat conduction performance. Further, as shown in Figure 1 the specific placement method during sintering, wherein: the outermost layer is sealed by the sintering pot 1 and the sintering pot cover 2, a layer of graphite powder 3 is laid in the sintering pot 1, the first pad burning paper 4 is arranged on the graphite powder 3, the first graphite paper 5 is arranged on the first pad burning paper 4, the annular graphite ring 6 is arranged on the first graphite paper 5, and the green compact disc 7 is placed inside the graphite ring 6, and then the second graphite paper 8 and the second pad burning paper 9 are placed on the surface of the graphite ring 6 in sequence. By using the sintering pot 1 to seal and using the graphite powder 3 and the graphite paper to perform buried sintering, the ablation of the graphite in the raw material is avoided, and the uniform sintering of the green compact is promoted.

[0061] Step S430, after the holding is finished, the heating is stopped, and the temperature in the furnace is gradually reduced to room temperature according to the preset temperature curve to obtain the sintered product.

[0062] It can be understood that this process is a cooling stage, and the purpose is to control the cooling rate of the sintered product to prevent rapid cooling from causing uneven structure or other problems.

[0063] Step S440, the sintered product is subjected to appearance inspection and electrical test respectively to obtain the heating element.

[0064] It can be understood that through the two operations, it can be confirmed that the prepared heating element meets the requirements in appearance and electrical performance, which provides guarantee for the final product quality.

[0065] It should be noted that step S440 includes step S441, step S442, step S443 and step S444.

[0066] Step S441, using a microscope to inspect the surface of the sintered product, obtaining appearance inspection records.

[0067] It can be understood that the appearance inspection records obtained in this step include the description of various surface features, the additional information of photos or images, and any findings that may affect the performance of the final product. These records are crucial to ensure the quality and reliability of the heating element, as minor surface defects or foreign matter may have a negative impact on the performance of the element.

[0068] Step S442, based on the preset appearance quality evaluation standard, the appearance inspection records are evaluated and processed, and the appearance evaluation result is obtained by mapping the types and degrees of appearance curves into numerical values.

[0069] It can be understood that the preset appearance quality evaluation standard in this step includes the types and allowable degrees of various appearance features, such as cracks, pores, color changes, etc. Each type of appearance feature is assigned a certain weight or score to reflect its degree of influence on the overall appearance quality. By applying these standards and weights to the observed conditions in the appearance inspection records, a numerical appearance evaluation result can be obtained.

[0070] Step S443, based on the preset electrical performance standard, the sintered product is electrically detected, and the electrical test result is obtained by using the four-terminal method to quantitatively measure the resistance and conductivity of the sintered product.

[0071] It can be understood that the preset electrical performance standard includes the specification of key electrical parameters such as resistance, conductivity, etc. to ensure that the heating element can meet the specific electrical performance requirements in actual use. By using the four-terminal method, the influence of test lead resistance can be eliminated, and the accuracy of the test can be improved.

[0072] Step S444, according to the appearance evaluation result and the electrical test result, the sintered product is screened to obtain the heating element.

[0073] It can be understood that by comprehensively considering the results of appearance evaluation and electrical test, the sintered product can be screened to select the required heating element. This helps to ensure that the product meets the actual application requirements under high temperature-high pressure conditions when in use.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high thermal conductive heat generating element, characterized by, The high-thermal-conductivity heating element is prepared from a first black silicon carbide powder, a second black silicon carbide powder, flaky graphite, a polyvinyl alcohol aqueous solution, and a small amount of a high-thermal-conductivity sintering aid, wherein the first black silicon carbide powder and the second black silicon carbide powder have different particle sizes, and the particle size ratio of the first black silicon carbide powder and the second black silicon carbide powder satisfies the Horsfield filling relationship. The weight ratio of the first black silicon carbide powder, the second black silicon carbide powder, the flaky graphite, the polyvinyl alcohol aqueous solution, and the sintering aid is 100:100:(6-20):(10-20):(10-12). The particle size of the first black silicon carbide powder is D50=5-10 microns, and the particle size of the second black silicon carbide powder is D50=15-25 microns. The particle size of the flaky graphite is D50=10-15 microns. The sintering aid is a saturated magnesium acetate aqueous solution, which generates high-thermal-conductivity MgO through melting and decomposition during the sintering process, forms a space filament network connection, and improves the mechanical strength of the heating sheet.

2. A method of producing a high thermal conductive heat generating element as claimed in claim 1, characterized by, The method comprises the following steps: The first black silicon carbide powder, the second black silicon carbide powder, and the flaky graphite are mixed to obtain a first mixed powder. The polyvinyl alcohol aqueous solution with a concentration of 5%-10% is weighed according to 5%-10% of the weight of the silicon carbide powder, and the polyvinyl alcohol aqueous solution and the saturated magnesium acetate aqueous solution are simultaneously added to the first mixed powder to obtain a second mixed powder, wherein the addition ratio of the magnesium acetate aqueous solution is 5% according to the mass ratio of MgO generated after decomposition of magnesium acetate to the total mass of MgO, graphite, and silicon carbide. The second mixed powder is stirred, granulated, and pressed to obtain a green compact round sheet through setting the forming pressure to 150-300 MPa. The green compact round sheet is sintered to obtain a heating element.

3. The method for preparing a high thermal conductivity heating element according to claim 2, characterized in that, The polyvinyl alcohol aqueous solution with a concentration of 5%-10% is weighed according to 5%-10% of the weight of the silicon carbide powder, and the polyvinyl alcohol aqueous solution and the saturated magnesium acetate aqueous solution are simultaneously added to the first mixed powder to obtain a second mixed powder, which comprises: The first black silicon carbide powder and the second black silicon carbide powder are subjected to powder particle size regulation treatment to adjust the particle size of the raw materials to a preset range to obtain adjusted raw materials. The adjusted raw materials and the flaky graphite are mixed by using a three-dimensional mixer to obtain a preliminary mixture. The polyvinyl alcohol aqueous solution and the magnesium acetate aqueous solution are simultaneously added to the preliminary mixture, and the mixture is stirred to obtain a wet mixture. The wet mixture is granulated to obtain a second mixed powder.

4. The method for preparing a high thermal conductivity heating element according to claim 2, characterized in that, The green compact round sheet is sintered to obtain a heating element, which comprises: The green compact round sheet is subjected to a heating pretreatment, i.e., the green compact round sheet is placed in an industrial muffle furnace, gradually heated to 400-450 degrees Celsius, and subjected to a degumming treatment at this temperature range for 0.5-1 hours. The green disc is subjected to a temperature rising sintering process, sintering in an atmospheric atmosphere, raising the furnace temperature to a final sintering temperature of 1400-1450 degrees Celsius, and performing a heat preservation process at the temperature range for 2-3 hours; After the heat preservation is completed, the heating is stopped, and the sintered product is obtained by natural cooling with the furnace to room temperature; The sintered product is subjected to appearance inspection and electrical testing to obtain a heating element.

5. The method of claim 4, wherein the high thermal conductive heating element is prepared by the steps of: (a) preparing a mixture of the high thermal conductive material and the binder; (b) coating the mixture on a surface of the heating element; and (c) drying the mixture. The sintered product is subjected to appearance inspection and electrical testing to obtain a heating element, comprising: The surface of the sintered product is inspected using a microscope to obtain an appearance inspection record; The appearance inspection record is evaluated based on a preset appearance quality evaluation standard, and the type and degree of the appearance curve are mapped to a numerical value to obtain an appearance evaluation result; The sintered product is subjected to electrical testing based on a preset electrical performance standard, and the resistance and conductivity of the sintered product are quantitatively measured using a four-terminal method to obtain an electrical test result; The sintered product is screened based on the appearance evaluation result and the electrical test result to obtain a heating element.

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