Ceramic heating element and its preparation method and electronic smoke atomizer

Abstract

This invention provides a ceramic heating element, comprising a porous substrate and multiple thermally conductive layers disposed within the porous substrate. The multiple thermally conductive layers are stacked vertically within the porous substrate, and each thermally conductive layer comprises multiple aluminum nitride microspheres, with the aluminum nitride microspheres in adjacent layers in contact with each other. The ceramic heating element provided by this invention has high thermal conductivity and good oil and gas conduction effects, improving temperature uniformity and atomization efficiency, thereby enhancing the atomization effect. This invention also provides a method for preparing the ceramic heating element and an electronic cigarette atomizer.

Description

Technical Field

[0001] This invention relates to the field of electronic cigarette technology, and in particular to a ceramic heating element, its preparation method, and an electronic cigarette atomizer. Background Technology

[0002] Electronic cigarettes, also known as virtual cigarettes, vaporizers, or aerosol generators, are mainly used to simulate the feeling of smoking without affecting health, for the purpose of quitting smoking or replacing cigarettes.

[0003] The atomizing coil is the core component of an e-cigarette atomizer, its main function being to heat the e-liquid (vapor paste) to produce vapor. Currently, some e-cigarette atomizing coils use ceramic atomizing components, which mainly consist of a porous ceramic body and a heating element disposed on the surface of the porous ceramic body. The heating element typically uses a heating wire or heating circuitry. Commonly available porous ceramic bodies are generally made from diatomaceous earth and fired to produce a fine atomized particle effect and a good draw; however, due to its low thermal conductivity and slow heat transfer rate, the surface temperature of the porous ceramic body in contact with the heating element is high, while the temperature of the parts of the porous ceramic body away from the heating element is low. Therefore, the overall heating of the porous ceramic body is uneven, thus affecting the atomization effect. Summary of the Invention

[0004] The purpose of this invention is to provide a ceramic heating element with high thermal conductivity and good oil and gas conduction effects, which improves temperature uniformity and atomization efficiency, thereby improving the atomization effect.

[0005] The present invention provides a ceramic heating element, comprising a porous substrate and multiple thermally conductive layers disposed within the porous substrate. The multiple thermally conductive layers are stacked vertically within the porous substrate, and each thermally conductive layer comprises a plurality of aluminum nitride microspheres, with the aluminum nitride microspheres in adjacent vertical thermally conductive layers in contact with each other.

[0006] In one feasible embodiment, the multilayer thermal conductive layer includes multiple layers of first thermal conductive layer and multiple layers of second thermal conductive layer, which are alternately arranged in sequence. The aluminum nitride microspheres in the first thermal conductive layer and the aluminum nitride microspheres in the second thermal conductive layer are staggered, and the aluminum nitride microspheres in the adjacent first and second thermal conductive layers are in contact.

[0007] In one feasible approach, in the first and second thermally conductive layers that are adjacent to each other, at least a portion of the aluminum nitride microspheres in the second thermally conductive layer are in contact with two adjacent aluminum nitride microspheres in the first thermally conductive layer.

[0008] In one feasible manner, in two adjacent layers of the first thermally conductive layer, two corresponding aluminum nitride microspheres are in contact with each other; in two adjacent layers of the second thermally conductive layer, two corresponding aluminum nitride microspheres are in contact with each other.

[0009] In one feasible manner, the aluminum nitride microspheres have a particle size of 50-150 micrometers.

[0010] In one feasible manner, in each of the thermally conductive layers, there are gaps between adjacent aluminum nitride microspheres, and the porous matrix fills the gaps.

[0011] In one feasible embodiment, the porous matrix includes multiple adhesive layers stacked one on top of the other, each adhesive layer corresponding to a thermally conductive layer; multiple aluminum nitride microspheres in each thermally conductive layer are disposed in the corresponding adhesive layer, and adjacent adhesive layers are bonded and fixed to each other.

[0012] The present invention also provides a method for preparing a ceramic heating element, used to manufacture the ceramic heating element described above, the method comprising the following steps:

[0013] S10: Prepare aluminum nitride microsphere slurry and adhesive slurry; wherein the aluminum nitride microsphere slurry comprises aluminum nitride microspheres, and the adhesive slurry comprises a pore-forming agent;

[0014] S20: Screen printing the aluminum nitride microsphere slurry on the substrate to form a first thermally conductive layer; then screen printing the adhesive slurry on the first thermally conductive layer to form an adhesive layer; screen printing the aluminum nitride microsphere slurry on the adhesive layer to form a second thermally conductive layer; then screen printing the adhesive slurry on the second thermally conductive layer to form another adhesive layer.

[0015] S30: Repeat step S20 above until a substrate with multiple layers of thermally conductive layers and multiple layers of adhesive layers are obtained; wherein, the aluminum nitride microspheres in two adjacent thermally conductive layers are in contact with each other, and the two adjacent adhesive layers are in contact with each other.

[0016] S40: The substrate is sintered to obtain a ceramic heating element; wherein, the pore-forming agent in the adhesive layer decomposes and volatilizes during the sintering process, forming a porous structure in the adhesive layer, and multiple adhesive layers are bonded and fixed to each other after sintering, thereby forming a porous matrix.

[0017] In one feasible approach, during step S20 above, when forming the first thermally conductive layer and the second thermally conductive layer by screen printing, different screens are used for staggered screen printing, so that the aluminum nitride microspheres in the two adjacent thermally conductive layers are arranged in a staggered manner.

[0018] In one feasible embodiment, the aluminum nitride microsphere slurry further comprises a first glass powder and a first solvent; wherein the weight parts of the aluminum nitride microspheres, the first glass powder, and the first solvent are respectively: 70-80 parts of aluminum nitride microspheres, 5-10 parts of the first glass powder, and 10-25 parts of the first solvent.

[0019] In one feasible embodiment, the adhesive slurry further comprises a second glass powder and a second solvent, and the pore-forming agent is PMMA; wherein the weight parts of the pore-forming agent, the second glass powder, and the second solvent are respectively: 40-55 parts of the pore-forming agent, 45-60 parts of the second glass powder, and 100 parts of the second solvent.

[0020] In one feasible manner, the preparation process of the aluminum nitride microspheres includes the following steps:

[0021] Aluminum nitride powder, binder, sintering aid and third solvent are mixed and ball-milled to obtain a mixture. The mixture is then added to a spray granulator for granulation to obtain aluminum nitride microparticles with a particle size of 50-150 micrometers. The aluminum nitride microparticles are then sintered in a nitrogen atmosphere at a temperature of 1700-1900℃ for 1-4 hours to obtain aluminum nitride microspheres.

[0022] In one feasible embodiment, the binder comprises at least one selected from polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, and regenerated cellulose; the sintering aid comprises at least one selected from yttrium oxide, lanthanum oxide, calcium oxide, and lithium oxide; and the weight parts of the aluminum nitride powder, the binder, the sintering aid, and the third solvent are respectively: 55-70 parts of aluminum nitride powder, 5-8 parts of the binder, 1-5 parts of the sintering aid, and 20-40 parts of the third solvent.

[0023] The present invention also provides an electronic smoke atomizer, including the ceramic heating element described above.

[0024] The ceramic heating element provided by this invention comprises multiple thermally conductive layers within a porous substrate. Each thermally conductive layer includes multiple aluminum nitride microspheres. Due to the high thermal conductivity of the aluminum nitride microspheres (up to 170 W / m·°C), and the contact between adjacent thermally conductive layers, heat can be rapidly conducted. Therefore, this ceramic heating element exhibits excellent thermal conductivity, improving temperature uniformity and atomization efficiency. Furthermore, the porous structure of the substrate provides excellent oil and air conduction, resulting in superior atomization of e-liquid. Attached Figure Description

[0025] Figure 1 This is a three-dimensional structural diagram of the ceramic heating element in an embodiment of the present invention.

[0026] Figure 2 for Figure 1 A schematic diagram of the explosion structure.

[0027] Figure 3 for Figure 1 A cross-sectional schematic diagram.

[0028] Figure 4 This is a cross-sectional schematic diagram of the ceramic heating element in another embodiment of the present invention.

[0029] Figure 5 This is a schematic diagram of a ceramic heating element being tested for temperature according to an embodiment of the present invention. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0031] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0032] The directional terms such as "up," "down," "left," "right," "front," "back," "top," and "bottom" (if present) used in the specification and claims of this invention are defined by the position of the structures in the drawings and the relative positions of the structures, and are only for the clarity and convenience of expressing the technical solution. It should be understood that the use of directional terms should not limit the scope of protection claimed by this invention.

[0033] like Figures 1 to 3As shown, the ceramic heating element provided in this embodiment of the invention includes a porous substrate 1 and a multilayer thermally conductive layer 2 disposed within the porous substrate 1. The porous substrate 1 has a porous structure, and the multilayer thermally conductive layer 2 is stacked vertically within the porous substrate 1. Each thermally conductive layer 2 includes a plurality of aluminum nitride microspheres 20, and the aluminum nitride microspheres 20 in two adjacent thermally conductive layers 2 are in contact with each other.

[0034] Specifically, the ceramic heating element provided in this embodiment comprises multiple thermally conductive layers 2 within a porous substrate 1. Each thermally conductive layer 2 includes multiple aluminum nitride microspheres 20. Due to the high thermal conductivity of the aluminum nitride microspheres 20 (the thermal conductivity of aluminum nitride can reach 170 W / m·°C, exceeding that of many metals), and the contact between adjacent aluminum nitride microspheres 20 in the upper and lower thermally conductive layers 2, heat can be rapidly conducted. Therefore, this ceramic heating element has excellent thermal conductivity, improving temperature uniformity and atomization efficiency. Moreover, because the porous substrate 1 has a porous structure, the ceramic heating element has good oil and air guiding effects, thereby enabling the ceramic heating element to have a good atomization effect on e-liquid.

[0035] While ordinary aluminum nitride ceramics also possess high thermal conductivity (reaching 170 W / m·°C), their fabrication requires high-temperature densification sintering. The sintering temperature of aluminum nitride is as high as 1700-1900°C, while the sintering temperatures of other components in aluminum nitride ceramics are generally around 900-1200°C. Due to the significant differences in sintering temperatures between the components, co-firing is not convenient, thus posing a certain challenge to the manufacturing process. In this embodiment, aluminum nitride microspheres 20 are placed within a porous substrate 1. The aluminum nitride microspheres 20 can be pre-sintered individually (i.e., they have already undergone high-temperature sintering during fabrication). Therefore, when manufacturing the ceramic heating element, sintering only needs to be performed according to the sintering temperature of the porous substrate 1, thereby avoiding the problem of co-firing due to significant differences in sintering temperatures between components and reducing the manufacturing difficulty.

[0036] like Figure 2 and Figure 3 As shown, multiple aluminum nitride microspheres 20 in each thermally conductive layer 2 are located on the same plane and arranged in an array; in each thermally conductive layer 2, there is a gap 200 between adjacent aluminum nitride microspheres 20 (i.e., adjacent aluminum nitride microspheres 20 are spaced apart), and the porous matrix 1 fills the gap 200.

[0037] Specifically, by setting gaps 200 between adjacent aluminum nitride microspheres 20 and filling the gaps 200 with porous substrate 1, the connection between aluminum nitride microspheres 20 is made stronger (adjacent aluminum nitride microspheres 20 can be tightly connected through porous substrate 1), which improves the structural strength of the ceramic heating element. It also increases the contact area between aluminum nitride microspheres 20 and porous substrate 1, thereby improving the thermal conductivity. At the same time, it increases the coverage area of ​​porous substrate 1 (i.e., porous substrate 1 can fill various positions), which increases the channels for oil and gas conduction, thereby improving the oil and gas conduction effect of porous substrate 1 (if adjacent aluminum nitride microspheres 20 are closely arranged in each thermal conductive layer 2, the oil and gas conduction channels will be blocked, thus affecting the oil and gas conduction effect). Therefore, in order to form a gap 200 between adjacent aluminum nitride microspheres 20 (so that the arrangement of aluminum nitride microspheres 20 has a certain regularity), the thermal conductive layer 2 is generally made by screen printing (while coating or other methods cannot guarantee that a gap 200 is formed between adjacent aluminum nitride microspheres 20).

[0038] like Figure 2 and Figure 3 As shown, in one embodiment, the multilayer thermally conductive layer 2 includes multiple first thermally conductive layers 21 and multiple second thermally conductive layers 22. The multiple first thermally conductive layers 21 and multiple second thermally conductive layers 22 are arranged alternately in a vertical sequence. The aluminum nitride microspheres 20 in each first thermally conductive layer 21 are arranged in the same way, and the aluminum nitride microspheres 20 in each second thermally conductive layer 22 are arranged in the same way. The aluminum nitride microspheres 20 in the first thermally conductive layer 21 and the aluminum nitride microspheres 20 in the second thermally conductive layer 22 are staggered, and the aluminum nitride microspheres 20 in the adjacent first thermally conductive layers 21 and second thermally conductive layers 22 are in contact.

[0039] Specifically, by staggering the aluminum nitride microspheres 20 in the first thermally conductive layer 21 and the second thermally conductive layer 22, the distribution density of the aluminum nitride microspheres 20 is increased, space utilization is improved, and thus thermal conductivity is enhanced. During manufacturing, the adjacent first and second thermally conductive layers 21 and 22 can be screen-printed using a staggered screen printing method to achieve the staggered arrangement effect.

[0040] like Figure 3As shown, in one embodiment, in the adjacent first thermally conductive layer 21 and the second thermally conductive layer 22, at least a portion of the aluminum nitride microspheres 20 in the second thermally conductive layer 22 are in contact with two adjacent aluminum nitride microspheres 20 in the first thermally conductive layer 21. In the two adjacent first thermally conductive layers 21, each pair of corresponding aluminum nitride microspheres 20 is in contact; in the two adjacent second thermally conductive layers 22, each pair of corresponding aluminum nitride microspheres 20 is in contact, thereby ensuring that at least a portion of the aluminum nitride microspheres 20 are in contact with six adjacent aluminum nitride microspheres 20 simultaneously, thus increasing the contact area between the aluminum nitride microspheres 20 and improving the thermal conductivity.

[0041] like Figure 4 As shown, in another embodiment, in the two adjacent first thermally conductive layers 21, the two corresponding aluminum nitride microspheres 20 may not contact each other; in the two adjacent second thermally conductive layers 22, the two corresponding aluminum nitride microspheres 20 may also not contact each other. Even if some aluminum nitride microspheres 20 are in contact with four adjacent aluminum nitride microspheres 20 simultaneously, the thermal conductivity of this arrangement is slightly lower than that of the first layer. Figure 3 The thermal conductivity of the arrangement shown.

[0042] As one implementation method, the aluminum nitride microspheres 20 have a particle size of 50-150 micrometers, which makes the aluminum nitride microspheres 20 have a small size and a large specific surface area, thereby increasing the contact area between the aluminum nitride microspheres 20 and the porous substrate 1, thereby improving the thermal conductivity.

[0043] like Figures 1 to 3 As shown, in one embodiment, the porous substrate 1 includes multiple adhesive layers 11, which are stacked one on top of the other and correspond to multiple thermally conductive layers 2. Multiple aluminum nitride microspheres 20 in each thermally conductive layer 2 are disposed in the corresponding adhesive layer 11, and adjacent adhesive layers 11 are bonded and fixed together. Thus, the porous substrate 1 is formed by bonding multiple adhesive layers 11 together. Furthermore, adhesive layers 11 are also provided on the outer side of the top thermally conductive layer 2 (i.e., above the top thermally conductive layer 2) and on the outer side of the bottom thermally conductive layer 2 (below the bottom thermally conductive layer 2), so that each thermally conductive layer 2 is completely embedded within the porous substrate 1.

[0044] like Figures 1 to 3 As shown, in one embodiment, the ceramic heating element has a cuboid structure, with a length direction L, a width direction W, and a thickness direction T. Multiple thermally conductive layers 2 are stacked vertically within the porous substrate 1 along the thickness direction T, and multiple adhesive layers 11 are stacked vertically along the thickness direction T. Multiple aluminum nitride microspheres 20 in each thermally conductive layer 2 are arranged in an array along the length direction L and the width direction W.

[0045] In one embodiment, the ceramic heating element also includes a heating element (not shown), which is disposed on the surface of the porous substrate 1. The heating element can be a heating wire, heating circuit, or other structure. The heating element generates heat after being energized, thereby conducting heat to the porous substrate 1. Of course, in other embodiments, the heating element can also be disposed inside the porous substrate 1, in which case the heating element can be a spiral heating wire or other structure.

[0046] This invention also provides a method for preparing a ceramic heating element, used to manufacture the above-mentioned ceramic heating element. The method for preparing the ceramic heating element includes the following steps:

[0047] S10: Prepare aluminum nitride microsphere slurry and adhesive slurry; wherein, the aluminum nitride microsphere slurry comprises aluminum nitride microspheres 20, and the adhesive slurry comprises a pore-forming agent.

[0048] S20: Aluminum nitride microsphere paste is screen-printed on a substrate (not shown) to form a first thermally conductive layer 2. Then, an adhesive paste is screen-printed on the first thermally conductive layer 2. The adhesive paste penetrates into the gaps 200 between adjacent aluminum nitride microspheres 20 in the first thermally conductive layer 2 to form an adhesive layer 11. Aluminum nitride microsphere paste is screen-printed on the adhesive layer 11 to form a second thermally conductive layer 2. Then, an adhesive paste is screen-printed on the second thermally conductive layer 2. The adhesive paste penetrates into the gaps 200 between adjacent aluminum nitride microspheres 20 in the second thermally conductive layer 2 to form another adhesive layer 11.

[0049] S30: Repeat step S20 above until a substrate with multiple layers of thermally conductive layers 2 and multiple layers of adhesive layers 11 stacked in sequence is obtained, the thickness of the substrate being 1-2 mm; wherein, the aluminum nitride microspheres 20 in two adjacent thermally conductive layers 2 are in contact with each other, and the two adjacent adhesive layers 11 are in contact with each other.

[0050] S40: The substrate is sintered first at 250-300℃ for 1-3 hours, and then at 500-700℃ for 1-3 hours to obtain a ceramic heating element; wherein, the pore-forming agent in the adhesive layer 11 decomposes and volatilizes during the sintering process, so that a porous structure is formed in the adhesive layer 11, and the multiple adhesive layers 11 are bonded and fixed to each other after sintering, thereby forming a porous matrix 1.

[0051] In one embodiment, in step S20 above, when forming the first thermal conductive layer 2 and the second thermal conductive layer 2 by screen printing, different screens are used for staggered screen printing so that the aluminum nitride microspheres 20 in the two adjacent thermal conductive layers 2 are arranged in a staggered manner.

[0052] Specifically, in step S20 above, an aluminum nitride microsphere paste can be screen-printed using a first screen to form a first thermally conductive layer 2, an adhesive paste can be screen-printed using a second screen to form an adhesive layer 11, and an aluminum nitride microsphere paste can be screen-printed using a third screen to form a second thermally conductive layer 2. The first and third screens have the same mesh count, for example, both 100 mesh, but their mesh structures are reversed (i.e., the wires of the first screen are the holes of the third screen, and the holes of the first screen are the wires of the third screen), thus achieving a misaligned screen printing effect; the second screen can have a mesh count of 200 mesh.

[0053] As one implementation, in step S20 above, before screen printing aluminum nitride microsphere slurry on the substrate to form the first thermally conductive layer 2, an adhesive slurry can be screen printed on the substrate to form an adhesive layer 11, and then aluminum nitride microsphere slurry can be screen printed on the adhesive layer 11 to form the first thermally conductive layer 2, so that the outermost part of the ceramic heating element is the adhesive layer 11.

[0054] In one embodiment, in step S10 above, the aluminum nitride microsphere slurry further comprises a first glass powder and a first solvent, wherein the first solvent can be at least one of ethanol and water. The weight parts of the aluminum nitride microspheres 20, the first glass powder, and the first solvent are as follows: 70-80 parts of aluminum nitride microspheres 20, 5-10 parts of the first glass powder, and 10-25 parts of the first solvent.

[0055] In one embodiment, in step S10 above, the adhesive slurry further comprises a second glass powder and a second solvent. The pore-forming agent is PMMA, and the second solvent can be at least one of ethanol and water. The weight parts of the pore-forming agent, the second glass powder, and the second solvent are as follows: 40-55 parts of pore-forming agent, 45-60 parts of second glass powder, and 100 parts of second solvent.

[0056] As one implementation method, the preparation process of aluminum nitride microspheres 20 in step S10 above includes the following steps:

[0057] Aluminum nitride powder, binder, sintering aid, and third solvent are mixed and ball-milled for 4-8 hours. The mixture is then added to a spray granulator for granulation to obtain aluminum nitride microparticles with a particle size of 50-150 micrometers. The aluminum nitride microparticles are then sintered in a nitrogen atmosphere at a temperature of 1700-1900℃ for 1-4 hours to obtain aluminum nitride microspheres 20.

[0058] In one embodiment, the binder comprises at least one selected from polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, and regenerated cellulose; the sintering aid comprises at least one selected from yttrium oxide, lanthanum oxide, calcium oxide, and lithium oxide; and the third solvent may be at least one of ethanol and water. The weight parts of aluminum nitride powder, binder, sintering aid, and third solvent are as follows: aluminum nitride powder 55-70 parts, binder 5-8 parts, sintering aid 1-5 parts, and third solvent 20-40 parts.

[0059] This invention also provides an electronic cigarette atomizer, including the ceramic heating element described above.

[0060] The ceramic heating element provided in this embodiment has multiple thermally conductive layers 2 within a porous substrate 1. Each thermally conductive layer 2 includes multiple aluminum nitride microspheres 20. Due to the high thermal conductivity of the aluminum nitride microspheres 20, and the fact that adjacent thermally conductive layers 2 have contacting aluminum nitride microspheres 20, heat can be quickly conducted. Therefore, this ceramic heating element has excellent thermal conductivity, improving temperature uniformity and atomization efficiency. Moreover, because the porous substrate 1 has a porous structure, the ceramic heating element has good oil and air conduction effects, resulting in excellent atomization of e-liquid.

[0061] Example 1

[0062] This embodiment provides a method for preparing a ceramic heating element, including the following steps:

[0063] S10: Prepare aluminum nitride microsphere slurry and adhesive slurry; wherein, the aluminum nitride microsphere slurry comprises 70 parts of aluminum nitride microspheres, 10 parts of first glass powder, and 20 parts of first solvent; the adhesive slurry comprises 40 parts of pore-forming agent PMMA, 60 parts of second glass powder, and 100 parts of second solvent.

[0064] S20: A first thermally conductive layer 2 is formed by screen printing aluminum nitride microsphere paste on a substrate using a first screen with a mesh size of 100. Then, an adhesive layer 11 is formed by screen printing adhesive paste on the first thermally conductive layer 2 using a second screen with a mesh size of 200. A second thermally conductive layer 2 is formed by screen printing aluminum nitride microsphere paste on the adhesive layer 11 using a third screen with a mesh size of 100. Then, another adhesive layer 11 is formed by screen printing adhesive paste on the second thermally conductive layer 2 using a second screen.

[0065] S30: Repeat step S20 above until a substrate with multiple layers of thermally conductive layer 2 and multiple layers of adhesive layer 11 stacked in sequence is obtained. The substrate has the following dimensions: 1 mm thick, 4 mm long, and 2 mm wide.

[0066] S40: A heating wire with a resistance of 1.2 ohms is pre-embedded on the substrate, and then the substrate is sintered. First, it is sintered at 250-300℃ for 1-3 hours, and then sintered at 500-700℃ for 1-3 hours to obtain a ceramic heating element.

[0067] Example 2

[0068] This embodiment provides a method for preparing a ceramic heating element, including the following steps:

[0069] S10: Prepare aluminum nitride microsphere slurry and adhesive slurry; wherein, the aluminum nitride microsphere slurry comprises 75 parts aluminum nitride microspheres, 5 parts first glass powder, and 20 parts first solvent; the adhesive slurry comprises 55 parts pore-forming agent PMMA, 45 parts second glass powder, and 100 parts second solvent.

[0070] S20: A first thermally conductive layer 2 is formed by screen printing aluminum nitride microsphere paste on a substrate using a first screen with a mesh size of 100. Then, an adhesive layer 11 is formed by screen printing adhesive paste on the first thermally conductive layer 2 using a second screen with a mesh size of 200. A second thermally conductive layer 2 is formed by screen printing aluminum nitride microsphere paste on the adhesive layer 11 using a third screen with a mesh size of 100. Then, another adhesive layer 11 is formed by screen printing adhesive paste on the second thermally conductive layer 2 using a second screen.

[0071] S30: Repeat step S20 above until a substrate with multiple layers of thermally conductive layer 2 and multiple layers of adhesive layer 11 stacked in sequence is obtained. The substrate has the following dimensions: 1 mm thick, 4 mm long, and 2 mm wide.

[0072] S40: A heating wire with a resistance of 1.2 ohms is pre-embedded on the substrate, and then the substrate is sintered. First, it is sintered at 250-300℃ for 1-3 hours, and then sintered at 500-700℃ for 1-3 hours to obtain a ceramic heating element.

[0073] Example 3

[0074] This embodiment provides a method for preparing a ceramic heating element, including the following steps:

[0075] S10: Prepare aluminum nitride microsphere slurry and adhesive slurry; wherein, the aluminum nitride microsphere slurry comprises 80 parts of aluminum nitride microspheres, 5 parts of first glass powder, and 15 parts of first solvent; the adhesive slurry comprises 40 parts of pore-forming agent PMMA, 60 parts of second glass powder, and 100 parts of second solvent.

[0076] S20: A first thermally conductive layer 2 is formed by screen printing aluminum nitride microsphere paste on a substrate using a first screen with a mesh size of 100. Then, an adhesive layer 11 is formed by screen printing adhesive paste on the first thermally conductive layer 2 using a second screen with a mesh size of 200. A second thermally conductive layer 2 is formed by screen printing aluminum nitride microsphere paste on the adhesive layer 11 using a third screen with a mesh size of 100. Then, another adhesive layer 11 is formed by screen printing adhesive paste on the second thermally conductive layer 2 using a second screen.

[0077] S30: Repeat step S20 above until a substrate with multiple layers of thermally conductive layer 2 and multiple layers of adhesive layer 11 stacked in sequence is obtained. The substrate has the following dimensions: 1 mm thick, 4 mm long, and 2 mm wide.

[0078] S40: A heating wire with a resistance of 1.2 ohms is pre-embedded on the substrate, and then the substrate is sintered. First, it is sintered at 250-300℃ for 1-3 hours, and then sintered at 500-700℃ for 1-3 hours to obtain a ceramic heating element.

[0079] Comparative Example

[0080] This comparative example provides a method for preparing a ceramic heating element, including the following steps:

[0081] 60 parts diatomaceous earth, 10 parts glass powder, 15 parts PMMA, and 15 parts paraffin wax are placed in a ball mill and ball-milled for 24 hours to obtain a ceramic slurry. The ceramic slurry is then injection-molded to obtain a heat-conducting preform. A heating wire with a resistance of 1.2 ohms is pre-embedded in the heat-conducting preform. The heat-conducting preform is then sintered, first at 200-400℃ for 1-5 hours, and then at 900-1400℃ for 2-4 hours to obtain a ceramic heating element with dimensions of 1mm thickness, 4mm length, and 2mm width.

[0082] The ceramic heating elements prepared in the three embodiments and the comparative example were tested respectively. The specific test methods are as follows: Figure 5 As shown, the heating wires in each ceramic heating element are connected to a power source, and then each ceramic heating element is heated under a rated power of 20W; when the middle position of the ceramic heating element (i.e. Figure 5 When the temperature at measurement point 1) reaches 220℃, the positions at both ends of the ceramic heating element (i.e. Figure 5 The temperatures at measurement points 2 and 3 are measured. Higher temperatures at both ends of the ceramic heating element indicate better thermal conductivity. Specific test results are shown in the table below:

[0083]

[0084] As can be seen from the table above, the temperature at both ends of the ceramic heating element in each embodiment is higher than that at both ends of the ceramic heating element in the comparative example. This indicates that the ceramic heating element in each embodiment has a faster heat conduction rate, better temperature uniformity, and significantly improved thermal conductivity.

[0085] The above are merely specific embodiments 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 ceramic heating element, characterized in that, It includes a porous matrix and multiple thermally conductive layers disposed within the porous matrix. The multiple thermally conductive layers are stacked one on top of the other within the porous matrix. Each thermally conductive layer includes multiple aluminum nitride microspheres, and the aluminum nitride microspheres in two adjacent thermally conductive layers are in contact with each other.

2. The ceramic heating element as described in claim 1, characterized in that, The multilayer thermal conductive layer includes multiple first thermal conductive layers and multiple second thermal conductive layers, which are arranged alternately in sequence. The aluminum nitride microspheres in the first thermal conductive layer and the aluminum nitride microspheres in the second thermal conductive layer are arranged in a staggered manner, and the aluminum nitride microspheres in the adjacent first thermal conductive layer and the second thermal conductive layer are in contact.

3. The ceramic heating element as described in claim 2, characterized in that, In the first and second thermally conductive layers that are adjacent to each other, at least a portion of the aluminum nitride microspheres in the second thermally conductive layer are in contact with two adjacent aluminum nitride microspheres in the first thermally conductive layer.

4. The ceramic heating element as described in claim 2, characterized in that, In the two adjacent first thermally conductive layers, each pair of corresponding aluminum nitride microspheres is in contact with each other; in the two adjacent second thermally conductive layers, each pair of corresponding aluminum nitride microspheres is in contact with each other.

5. The ceramic heating element as described in claim 1, characterized in that, The aluminum nitride microspheres have a particle size of 50-150 micrometers.

6. The ceramic heating element as described in claim 1, characterized in that, In each of the thermally conductive layers, there are gaps between adjacent aluminum nitride microspheres, and the porous matrix fills the gaps.

7. The ceramic heating element as described in claim 1, characterized in that, The porous matrix includes multiple adhesive layers, which are stacked one on top of the other, and each adhesive layer corresponds to a thermally conductive layer. Multiple aluminum nitride microspheres in each thermally conductive layer are disposed in the corresponding adhesive layer, and adjacent adhesive layers are bonded and fixed to each other.

8. A method for preparing a ceramic heating element, characterized in that, The method for preparing the ceramic heating element as described in any one of claims 1-7 includes the following steps: S10: Prepare aluminum nitride microsphere slurry and adhesive slurry; wherein the aluminum nitride microsphere slurry comprises aluminum nitride microspheres, and the adhesive slurry comprises a pore-forming agent; S20: Screen printing the aluminum nitride microsphere slurry on the substrate to form a first thermally conductive layer; then screen printing the adhesive slurry on the first thermally conductive layer to form an adhesive layer; screen printing the aluminum nitride microsphere slurry on the adhesive layer to form a second thermally conductive layer; then screen printing the adhesive slurry on the second thermally conductive layer to form another adhesive layer. S30: Repeat step S20 above until a substrate with multiple layers of thermally conductive layers and multiple layers of adhesive layers are obtained; wherein, the aluminum nitride microspheres in two adjacent thermally conductive layers are in contact with each other, and the two adjacent adhesive layers are in contact with each other. S40: The substrate is sintered to obtain a ceramic heating element.

9. The method for preparing the ceramic heating element as described in claim 8, characterized in that, In step S20 above, when forming the first thermal conductive layer and the second thermal conductive layer by screen printing, different screens are used for staggered screen printing so that the aluminum nitride microspheres in the two adjacent thermal conductive layers are arranged in a staggered manner.

10. The method for preparing the ceramic heating element as described in claim 8, characterized in that, The aluminum nitride microsphere slurry further comprises a first glass powder and a first solvent; wherein the weight parts of the aluminum nitride microspheres, the first glass powder and the first solvent are respectively: 70-80 parts of aluminum nitride microspheres, 5-10 parts of the first glass powder and 10-25 parts of the first solvent.

11. The method for preparing the ceramic heating element as described in claim 8, characterized in that, The adhesive slurry further comprises a second glass powder and a second solvent, and the pore-forming agent is PMMA; wherein the weight parts of the pore-forming agent, the second glass powder and the second solvent are respectively: 40-55 parts of the pore-forming agent, 45-60 parts of the second glass powder and 100 parts of the second solvent.

12. The method for preparing the ceramic heating element as described in claim 8, characterized in that, The preparation process of the aluminum nitride microspheres includes the following steps: Aluminum nitride powder, binder, sintering aid and third solvent are mixed and ball-milled to obtain a mixture. The mixture is then added to a spray granulator for granulation to obtain aluminum nitride microparticles with a particle size of 50-150 micrometers. The aluminum nitride microparticles are then sintered in a nitrogen atmosphere at a temperature of 1700-1900℃ for 1-4 hours to obtain aluminum nitride microspheres.

13. The method for preparing the ceramic heating element as described in claim 12, characterized in that, The binder comprises at least one of polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, carboxymethyl cellulose, starch, hydroxypropyl cellulose, and regenerated cellulose; the sintering aid comprises at least one of yttrium oxide, lanthanum oxide, calcium oxide, and lithium oxide; the weight parts of the aluminum nitride powder, the binder, the sintering aid, and the third solvent are as follows: 55-70 parts of aluminum nitride powder, 5-8 parts of the binder, 1-5 parts of the sintering aid, and 20-40 parts of the third solvent.

14. An electronic cigarette atomizer, characterized in that, Includes a ceramic heating element as described in any one of claims 1-7.

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