Ceramic substrate, ceramic heating element and preparation method and application of ceramic substrate and ceramic heating element

Abstract

The invention discloses a ceramic substrate, a ceramic heating element and a preparation method and application of the ceramic heating element, and belongs to the technical field of electric heating ceramic heating elements. The ceramic substrate is prepared by processing ceramic green body slurry, and the ceramic green body slurry is prepared from the following components: 50-90 parts of zirconium oxide, 18-50 parts of micron-sized aluminum oxide, 1-13 parts of silicon nitride, 0.1-2 parts of nano-sized aluminum oxide and 0.1-5 parts of a sintering aid, the average particle size of the nanoscale aluminum oxide is 300 to 800 nm. A certain amount of silicon nitride and a certain amount of nanoscale aluminum oxide with a specific particle size are added, so that the thermal conductivity of the ceramic substrate and the fitting property of the ceramic substrate and a heating component are improved, the ceramic substrate is quick in heat transfer and uniform in heating, the temperature zone uniformity of the ceramic substrate is improved, tobacco shreds are fully heated, the smoke amount is increased, and the tobacco shreds are more uniform. And the smoking taste of a user is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrothermal ceramic heating elements, and more specifically, to a ceramic substrate, a ceramic heating element, and a preparation method and application thereof. Background Art

[0002] After being ignited, traditional tobacco maintains a smoldering state, and uses the temperature generated by the smoldering to heat the tobacco raw materials near the combustion area, releasing smoke for inhalation. In this process, the temperature of the tobacco materials at different positions varies depending on the distance from the combustion cone. The smoke release process of traditional tobacco products occurs in a system with a large temperature variation range and poor heating uniformity. The unstable temperature makes the composition of the compounds in the smoke components very complicated, which also affects the stability of the smoke suction quality and makes the release of many harmful chemical components difficult to control.

[0003] In recent years, scientific research has shown that effectively controlling and lowering the combustion temperature of cigarettes can significantly increase the release of harmful components in smoke and improve the safety of tobacco products. Based on this theory, heat-not-burn products have been developed. These heat-not-burn products heat and bake tobacco materials through heating elements and control the heating temperature at around 350°C, allowing tobacco to release smoke but still remain in a non-burning state. Compared with traditional smoking cigarettes, heat-not-burn tobacco has greatly improved the temperature stability of tobacco smoke release, thereby reducing the harmfulness of the product.

[0004] The ceramic heating element of the existing heat-not-burn cigarette smoking device mainly achieves heating and temperature sensing by setting a heating circuit on a ceramic substrate, and heats an atomizing medium such as tobacco through the ceramic heating element to generate smoke.

[0005] The prior art discloses a composite ceramic heating element for use in the field of heating non-burning cigarette smoking utensils, wherein the heating tube body is formed by self-winding a composite cast green sheet, a first insulating layer is provided on one side of the front of the composite cast green sheet, a heating circuit is provided on the surface of the first insulating layer, and a second insulating layer is provided on the surface of the heating circuit. Among them, the composite cast green sheet is made of a composite ceramic cast slurry, and the composite ceramic cast slurry includes 10-70 parts of zirconium oxide, 20-80 parts of aluminum oxide, and 3-10 parts of other ceramic powders composed of magnesium oxide, calcium oxide, silicon dioxide and yttrium trioxide in a weight ratio of 1-3:1-3:0.5-2:0.5-2. However, the ceramic material prepared by the formula has a small heating area after being heated by the heating route, resulting in uneven temperature zone of the composite cast green sheet (ceramic substrate), and thus the tobacco shreds cannot be uniformly and fully carbonized, resulting in low smoke volume generated by the tobacco shreds, which makes the user's taste poor when smoking. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the ceramic substrate of the existing ceramic heating body, which leads to a decrease in the amount of smoke produced by tobacco and thus a worsening of the user's taste. A ceramic substrate is provided, which has good temperature zone uniformity when heated, so that the tobacco is fully heated, the amount of smoke is increased, and the user's smoking taste is improved.

[0007] Another object of the present invention is to provide a ceramic heating element.

[0008] Another object of the present invention is to provide a method for preparing a ceramic heating element.

[0009] Another object of the present invention is to provide an application of a ceramic heating element in the preparation of heat-not-burn cigarette smoking articles.

[0010] Another object of the present invention is to provide a heat-not-burn cigarette smoking device.

[0011] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0012] A ceramic substrate is made from ceramic green body slurry, wherein the ceramic green body slurry comprises the following components in parts by weight: 50-90 parts of zirconium oxide, 18-50 parts of micron-grade aluminum oxide, 1-13 parts of silicon nitride, 0.1-2 parts of nano-grade aluminum oxide, and 0.1-5 parts of a sintering aid; the average particle size of the nano-grade aluminum oxide is 300-800 nm.

[0013] The ceramic substrate of the present invention uses zirconium oxide and micron-sized aluminum oxide in ceramic green body slurry as main components, thereby ensuring the basic mechanical strength of the ceramic substrate.

[0014] The inventors of the present invention have found that silicon nitride has a high thermal conductivity and can be fully dissolved and diffused in micron alumina during processing. Therefore, adding a certain amount of silicon nitride can improve the thermal conductivity of the ceramic substrate, thereby expanding the heating area of ​​the ceramic substrate after being heated by the heating component (the first insulating layer provided with a heating layer), and improving the temperature zone uniformity of the ceramic substrate to a certain extent. However, the degree to which silicon nitride improves the temperature zone uniformity is limited. When the amount of silicon nitride is further increased, the temperature zone uniformity of the ceramic substrate is no longer improved, and the ceramic substrate still cannot achieve a good heating effect on the tobacco.

[0015] The inventor of the present invention has continued to study and found that the temperature zone uniformity of the ceramic substrate is not only related to the thermal conductivity of the ceramic substrate, but also has a great relationship with the surface roughness of the ceramic substrate. The present invention adds a certain amount of nano-alumina with a specific particle size on the basis of adding a certain amount of silicon nitride. The nano-alumina with a specific particle size can improve the sintering activity of the ceramic green body slurry of the present invention, improve the density of the ceramic substrate, thereby reducing the surface roughness of the ceramic substrate, so that the ceramic substrate and the heating component have good adhesion, thereby improving the uniformity of the heating of the ceramic substrate, and further improving the uniformity of the temperature zone.

[0016] That is, the present invention adds a certain amount of silicon nitride and a certain amount of nano-aluminum oxide with a specific particle size to improve the thermal conductivity of the ceramic substrate and its fit with the heating component, so that the ceramic substrate transfers heat quickly and is heated evenly, thereby improving the temperature zone uniformity of the ceramic substrate, allowing the tobacco to be fully heated, increasing the amount of smoke, and improving the user's smoking taste.

[0017] In addition, silicon nitride can also significantly improve the flexural strength of the ceramic substrate of the present invention.

[0018] Preferably, the average particle size of the nano-alumina is 500-600 nm.

[0019] In the present invention, the average particle size of the micron-sized aluminum oxide may be 5-10 μm.

[0020] Preferably, the sintering aid is a mixture of magnesium oxide, calcium oxide, silicon dioxide and yttrium trioxide, and the weight ratio of magnesium oxide, calcium oxide, silicon dioxide and yttrium trioxide is (3.9-5): (3.5-4): (0.1-0.3): (0.1-0.3).

[0021] The sintering aid of the present invention is more conducive to improving the density of ceramics.

[0022] In the present invention, the ceramic substrate can be prepared by step S11, and the step S11 comprises:

[0023] S111. The zirconium oxide, micron-sized alumina, silicon nitride, nano-sized alumina and sintering aids are stirred uniformly in a reaction apparatus according to parts by weight, and ball-milled for 3-10 hours to obtain a ceramic powder;

[0024] S112. The ceramic powder obtained in step S111 is added to a solvent, stirred evenly, and heated and baked, and then ball milled for 10-72 hours to obtain a ceramic green body slurry;

[0025] S113. Degassing the ceramic green body slurry obtained in step S112, where the ceramic green body viscosity is 4000-21000 PA·S;

[0026] S114. Cast the ceramic green body slurry after degassing in step S113, control the speed of the casting machine to 8-30mm / s, and obtain a ceramic substrate after casting.

[0027] Preferably, in step S112, the mass ratio of the solvent to the ceramic powder is 1:(1-2).

[0028] Preferably, the solvent in step S112 includes but is not limited to at least one of anhydrous ethanol, butanone, herring oil, dibutyl phthalate (DBP), polyethylene glycol (PEG) or polyvinyl butyral (PVB).

[0029] The present invention also protects a ceramic heating element, comprising any of the above-mentioned ceramic substrates, a first insulating layer arranged on the surface of the ceramic substrate, a heating layer arranged on the surface of the first insulating layer, and a second insulating layer arranged on the surface of the heating layer.

[0030] Preferably, the heating layer comprises at least one group of heating circuits; the heating circuits are single-track circuits or multi-track circuits; the multi-track circuits comprise at least two single-track circuits parallel to each other.

[0031] The single track line leads out a first single track track from the first line end and returns to the second line end. The track of the single track line is reciprocatingly folded in a U-shaped track along the longitudinal direction of the ceramic substrate or in a multi-point fold line, or the track of the single track line is reciprocatingly folded in a U-shaped track along the transverse direction of the ceramic substrate.

[0032] The double-track line leads out a double-track track from the first line end, and the double-track track, namely the first single-track track and the second single-track track, respectively returns to the second line end, and the tracks of the double-track line are respectively folded back and forth in a U-shaped track along the longitudinal direction of the ceramic substrate or in a multi-point fold line, or the tracks of the double-track line are respectively folded back and forth in a U-shaped track along the transverse direction of the ceramic substrate.

[0033] The heating circuit of the ceramic heating element is a single track and / or a double track circuit, so that the temperature zone of the ceramic heating element is evenly distributed, so that the tobacco leaves are evenly heated as a whole, and the baking effect is better. At the same time, it has good thermal conductivity and high flexural strength, which effectively extends the service life of the ceramic heating element and is highly practical.

[0034] The total length of a single-track line track is longer, there are more reciprocating inflection points, and the area presented by the track is larger; thus, the heating area of ​​the ceramic heating element is larger, the temperature zone distribution is more uniform, and the heating effect is better.

[0035] When the multi-track line is a dual-track line, the dual-track line can be connected in parallel, and the first single-track line and the second single-track line can be connected in parallel, which can increase the track heating area, the temperature zone distribution is very uniform, and the power of the ceramic heating element is maximized, while the heat generated by the heating line can be fully utilized. The multi-track line has better thermal conductivity, good consistency, and stable performance. The ceramic heating element can make the tobacco leaves evenly heated as a whole, and the baking effect is better.

[0036] More preferably, the heating circuit is a multi-track circuit, because the total heating area of ​​the multi-track circuit is larger than that of the single-track circuit, and the temperature zone presented is more uniform, so that the heating area of ​​the ceramic heating element is larger and the heat is generated more uniformly and fully.

[0037] Preferably, in the multi-track circuit, the line width L of the heating circuit is 0.3-2 mm, and the ratio of the spacing H between two adjacent heating circuits to the line width L of the heating circuit is (0.3-1):1.

[0038] A slightly larger spacing ratio can prevent watermarks from forming on the heating circuit printing, which can cause short circuits. A slightly smaller spacing ratio is more conducive to improving the uniformity of temperature distribution.

[0039] In the present invention, the heating circuit may be a conventional heating circuit in the art.

[0040] Preferably, the heating layer is printed by metal slurry, and the metal slurry is a mixture of resistor metal slurry and porcelain slurry, and the weight ratio of resistor metal slurry to porcelain slurry is (80-97): (3-20); the resistor metal slurry is composed of the following components in parts by weight: 20-80 parts of pineol, 1-8 parts of tributyl citrate, 0.1-5 parts of diethylene glycol butyl ether acetate, 1-8 parts of ethyl cellulose and 60-98 parts of tungsten powder; the porcelain slurry is composed of the following components in parts by weight: 20-80 parts of pineol, 1-10 parts of tributyl citrate, 0.1-10 parts of diethylene glycol butyl ether acetate, 1-10 parts of ethyl cellulose and 50-95 parts of porcelain powder.

[0041] The metal slurry can be prepared by step S21, and the step S21 includes:

[0042] S211 preparation of porcelain slurry: according to weight parts, pinene alcohol, tributyl citrate, diethylene glycol butyl ether acetate and ethyl cellulose were added to the reaction unit and mixed and stirred evenly, and then the porcelain powder was added and stirred to obtain a porcelain slurry and set aside;

[0043] S212 preparation of resistor metal slurry: according to weight parts, pinene alcohol, tributyl citrate, diethylene glycol butyl ether acetate and ethyl cellulose were added to the reaction device and mixed and stirred evenly, and then tungsten powder was added and stirred to obtain a resistor metal slurry, set aside;

[0044] S213. Add the ceramic slurry obtained in the above step to the resistor metal slurry obtained above, mix and stir evenly, bake for 2-7 hours, and then ball mill for 7-30 hours to obtain metal slurry.

[0045] Preferably, the first insulating layer is formed by printing a first insulating layer slurry, and the second insulating layer is formed by printing a second insulating layer slurry; the first insulating layer slurry is composed of the following components in parts by weight: 20-60 parts of terpineol, 1-5 parts of tributyl citrate, 0.1-2 parts of diethylene glycol butyl ether acetate, 1-5 parts of ethyl cellulose, 80-98 parts of aluminum oxide, 0.1-2 parts of calcium oxide, 0.1-2 parts of magnesium oxide and 0.1-1 parts of silicon dioxide; the second insulating layer slurry is composed of the following components in parts by weight: 20-60 parts of terpineol, 1-5 parts of tributyl citrate, 0.1-2 parts of diethylene glycol butyl ether acetate, 1-5 parts of ethyl cellulose, 80-98 parts of aluminum oxide, 0.1-2 parts of calcium oxide, 0.1-2 parts of magnesium oxide and 0.1-1 parts of silicon dioxide.

[0046] The composition of the first insulating layer paste may be the same as or different from that of the second insulating layer paste.

[0047] The function of the insulating layer is to protect the heating layer having the heating circuit.

[0048] The insulating layer slurry can be prepared by step S22, and the step S22 includes:

[0049] S221. According to parts by weight, aluminum oxide, calcium oxide, magnesium oxide and silicon dioxide were added to the reaction device and mixed and stirred to obtain an insulating layer of mixed powder for later use;

[0050] S222. According to parts by weight, terpineol, tributyl citrate, diethylene glycol butyl ether acetate and ethyl cellulose were added to the reaction apparatus and mixed to obtain an organic carrier for later use;

[0051] S223. Add the insulating layer mixed powder to the organic carrier, mix and stir evenly, bake for 2-9 hours, and then ball mill for 10-30 hours to obtain an insulating layer slurry.

[0052] The ceramic heating element of the present invention comprises a ceramic heating body and a pointed piece arranged at one end of the ceramic heating body. The other end of the ceramic heating body away from the pointed piece is sleeved with a flange.

[0053] The ceramic heating body is formed into a tubular structure by winding the ceramic substrate.

[0054] The function of the pointed piece is to improve the structural stability and make the ceramic heating element easier to insert into the cigarette. The flange is provided with a flange filling hole, which can be filled with glass glaze to seal and fix the flange to the ceramic heating body, making it easier to fix the ceramic heating element to the external assembly, thereby improving the practicality of the ceramic heating element.

[0055] A glass glaze layer can be provided on the outer surface of the ceramic heating element to smooth and protect it. It can isolate external oxygen from diffusing into the interior of the ceramic heating element and is not easily corroded by smoke oil, thereby improving the structural stability and service life of the ceramic heating element and making it highly practical.

[0056] The ceramic heating body may be composed of at least two layers of a ceramic substrate provided with a heating layer wound by itself.

[0057] The ceramic heating body may also be composed of a ceramic substrate wrapped around the outer surface of a ceramic rod.

[0058] The heating layer includes a heating circuit and an electrode pad.

[0059] The present invention also protects a method for preparing the ceramic heating element described in any one of the above items, comprising the following steps:

[0060] S1. The ceramic green body slurry is tape-cast to obtain a ceramic substrate;

[0061] S2. Prepare the first insulating layer by printing the first insulating layer slurry on the surface of the ceramic substrate of S1, prepare the heating layer by printing the metal slurry on the surface of the first insulating layer, prepare the second insulating layer by printing the second insulating layer slurry on the surface of the heating layer, and sinter to obtain a ceramic heating element.

[0062] In step S2, the sintering atmosphere is a reducing atmosphere, and the sintering temperature is 1500-1700° C. This is beneficial to improving the compactness of the ceramic heating element.

[0063] Specifically, the preparation method of the ceramic heating element, step S1, also includes the following steps:

[0064] S100. Preparing ceramic green body slurry, metal slurry, and insulating layer slurry;

[0065] S101. Preparation of ceramic green body: tape casting the ceramic green body slurry;

[0066] S102. The ceramic tape-cast green body is cut into a ceramic substrate of the desired size;

[0067] S2. The first insulating layer is prepared by printing a first insulating layer slurry on the surface of the ceramic substrate of S1, the heating layer is prepared by printing a metal slurry on the surface of the first insulating layer, and the second insulating layer is prepared by printing a second insulating layer slurry on the surface of the heating layer;

[0068] S3. The ceramic substrate obtained in S2 is self-wound to form a tubular structure, and a shaping fixture is placed in a sealing sleeve in the tubular structure for isostatic pressing to obtain a ceramic heating body;

[0069] S4. The ceramic heating body is subjected to binder removal sintering and co-fired at 1500-1700°C in a hydrogen reducing atmosphere;

[0070] S5. The sintered ceramic heating body is encapsulated with a glass glaze tip;

[0071] S6. Coating the outer surface of the ceramic heating body with the tip member with a glass glaze layer;

[0072] S7. Use glass glaze to seal the flange on the ceramic heating body and weld the leads to obtain the ceramic heating element.

[0073] The ceramic heating element prepared by the present invention has good thermal conductivity and thermal shock resistance, and can be widely used in the preparation of ceramic heating elements. The present invention especially protects the use of the ceramic heating element in the preparation of heat-not-burn cigarette smoking utensils.

[0074] The present invention also specifically protects a heat-not-burn cigarette smoking device, which includes the above-mentioned ceramic heating element.

[0075] The ceramic heating element of the present invention can have a diameter of 1.95-2.5 mm and a length of 17-25 mm, and is applied to the field of heat-not-burn cigarette smoking utensils.

[0076] Compared with the prior art, the present invention has the following beneficial effects:

[0077] The present invention adds a certain amount of silicon nitride and a certain amount of nano-aluminum oxide with a specific particle size to improve the thermal conductivity of the ceramic substrate and its fit with the heating component, so that the ceramic substrate transfers heat quickly and is heated evenly, thereby improving the temperature zone uniformity of the ceramic substrate, allowing the tobacco to be fully heated, increasing the amount of smoke, and improving the user's smoking taste. BRIEF DESCRIPTION OF THE DRAWINGS

[0078] Figure 1 This is a schematic diagram of the structure in which the heating circuit of the ceramic heating element of Example 1 is a dual-track circuit. In the figure, 11 is a ceramic substrate, 41 is a first circuit end; 42 is a second circuit end; 43 is a first single-line track; 44 is a second single-line track.

[0079] Figure 2 This is a schematic diagram of the structure of the heating circuit of the ceramic heating element in Example 8 as a single-track circuit, in which: 11-ceramic substrate, 41-first circuit end; 42-second circuit end; 43-first single-circuit track.

[0080] Figure 3Schematic diagram of a thermal imager with a ceramic heating element. DETAILED DESCRIPTION

[0081] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0082] Nano alumina 1#, average particle size is 500nm.

[0083] Nano alumina 2#, average particle size is 800nm.

[0084] Nano alumina 3#, average particle size is 300nm.

[0085] Nano alumina 4#, average particle size is 100nm.

[0086] Alumina 5#, average particle size is 1μm.

[0087] Example 1

[0088] like Figure 1 As shown, a ceramic heating element includes a ceramic substrate 11, which is formed by molding a ceramic green body slurry. A first insulating layer, a heating layer and a second insulating layer are respectively arranged on one side of the ceramic substrate. The ceramic green body slurry includes ceramic powder and a solvent. The ceramic powder is composed of the following components in parts by weight: 68 parts of zirconium oxide, 30 parts of micron-grade alumina, 3 parts of silicon nitride, 0.5 parts of nano-grade alumina 1#, and 1 part of a sintering aid.

[0089] The sintering aid is a mixture of magnesium oxide, calcium oxide, silicon dioxide and yttrium trioxide, wherein the weight ratio of magnesium oxide, calcium oxide, silicon dioxide and yttrium trioxide is 4.2:3.7:0.2:0.2.

[0090] The average particle size of micron-sized alumina is 8 μm.

[0091] The heating layer includes two groups of heating circuits, and the heating circuits are double-track circuits.

[0092] The double track line is a double track line drawn from the first line end 41, the double track line is a first single track line 43 and a second single track line 44, and returns to the second line end 42 respectively, and the tracks of the double track line are respectively folded back and forth in a U-shaped track or a multi-point fold line along the longitudinal direction of the ceramic substrate 11. Among them, the line width of the heating line is 0.5mm, and the ratio of the spacing H between two adjacent heating lines to the line width L of the heating line is 1:1.

[0093] The heating layer is printed by metal paste, which is a mixture of resistor metal paste and porcelain paste, and the weight ratio of resistor metal paste to porcelain paste is 85:5; the resistor metal paste is composed of the following components: 60 parts of pineol, 3 parts of tributyl citrate, 1 part of diethylene glycol butyl ether acetate, 2 parts of ethyl cellulose and 75 parts of tungsten powder; the porcelain paste is composed of the following components: 65 parts of pineol, 2.5 parts of tributyl citrate, 1 part of diethylene glycol butyl ether acetate, 2.3 parts of ethyl cellulose and 70 parts of porcelain powder.

[0094] The first insulating layer and the second insulating layer are both printed by insulating layer slurry, and the insulating layer slurry consists of the following components: 40 parts of pineol, 2 parts of tributyl citrate, 2 parts of diethylene glycol butyl ether acetate, 3 parts of ethyl cellulose, 90 parts of aluminum oxide, 1.2 parts of calcium oxide, 1.3 parts of magnesium oxide and 0.5 parts of silicon dioxide.

[0095] The preparation method of the above ceramic heating element is as follows:

[0096] S1. The ceramic green body slurry is tape-cast to obtain a ceramic substrate;

[0097] Specifically, the preparation method of the ceramic heating element, step S1, further includes the following steps: S100. preparing ceramic green body slurry, metal slurry, and insulating layer slurry;

[0098] S101. Preparation of ceramic green body: tape casting the ceramic green body slurry;

[0099] S102. The ceramic tape-cast green body is cut into a ceramic substrate of the desired size;

[0100] S2. Using metal slurry and insulating layer slurry, a first insulating layer, a heating layer and a second insulating layer are printed on the ceramic substrate respectively;

[0101] S3. The ceramic substrate is self-wound to form a tubular structure, and a shaping fixture is placed in a sealing sleeve in the tubular structure for isostatic pressing to obtain a ceramic heating body;

[0102] S4. The ceramic heating body is subjected to binder removal sintering and co-fired at 1500°C in a hydrogen reducing atmosphere;

[0103] S5. The sintered ceramic heating body is encapsulated with a glass glaze tip;

[0104] S6. Coating the outer surface of the ceramic heating body with the tip member with a glass glaze layer;

[0105] S7. Use glass glaze to seal the flange on the ceramic heating body and weld the leads to obtain the ceramic heating element.

[0106] Among them, in S100,

[0107] The ceramic green body slurry is prepared by the following steps:

[0108] Zirconia, micron-sized alumina, silicon nitride, nano-sized alumina, and sintering aids are uniformly mixed in a reaction device according to weight parts, and ball-milled for 4 hours to obtain ceramic powder;

[0109] The ceramic powder obtained above was added with 20 parts of anhydrous ethanol, 25 parts of butanone, and 1.8 parts of dibutyl phthalate (DBP) according to weight parts, stirred evenly, heated and baked, and then ball-milled for 13 hours to obtain a ceramic green body slurry;

[0110] The ceramic green body slurry obtained above is subjected to a degassing treatment, and the viscosity of the ceramic green body at this time is 5000 PA·S;

[0111] The defoamed ceramic green body slurry is cast, and the rate of the casting machine is controlled at 15 mm / s to obtain a ceramic green body after casting.

[0112] The metal slurry is prepared by the following steps:

[0113] According to parts by weight, terpineol, tributyl citrate, diethylene glycol butyl ether acetate and ethyl cellulose are added into a reaction device and mixed and stirred evenly, and then porcelain powder is added and stirred evenly to obtain a porcelain slurry for standby use;

[0114] According to parts by weight, terpineol, tributyl citrate, diethylene glycol butyl ether acetate and ethyl cellulose are added into a reaction device and mixed and stirred evenly, and then tungsten powder is added and stirred evenly to obtain a resistor metal slurry for standby use;

[0115] The ceramic slurry obtained above is added to the resistor metal slurry obtained above, mixed and stirred evenly, baked for 3 hours, and then ball-milled for 8 hours to obtain the metal slurry.

[0116] The insulating layer slurry is prepared by the following steps:

[0117] According to parts by weight, aluminum oxide, calcium oxide, magnesium oxide and silicon dioxide are added into a reaction device and mixed and stirred evenly to obtain an insulating layer mixed powder for later use;

[0118] According to parts by weight, terpineol, tributyl citrate, diethylene glycol butyl ether acetate and ethyl cellulose are added into a reaction device and mixed and stirred to obtain an organic carrier for later use;

[0119] The insulating layer mixed powder obtained above is added to the organic carrier obtained above, mixed and stirred evenly, baked for 3 hours, and then ball-milled for 8 hours to obtain an insulating layer slurry.

[0120] Embodiment 2 to Embodiment 7

[0121] A ceramic heating element, which differs from Example 1 in that the raw material components of the ceramic powder in the ceramic green body slurry are different, wherein the raw materials of each component are shown in Table 1 below.

[0122] Table 1: Raw materials of ceramic powder in ceramic green body slurry (by weight)

[0123] Components Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Zirconia 68 68 68 68 50 90 Micron Alumina 30 30 30 30 50 18 Silicon Nitride 1 5 10 13 1 13 Sintering Aids 1 1 1 1 0.1 5 Nano-alumina 1# 0.5 0.5 0.5 0.5 0.1 2 Nano-alumina 2# / / / / / / Nano-alumina 3# / / / / / /

[0124] The preparation method is the same as that in Example 1 and will not be described again here.

[0125] Example 8

[0126] A ceramic heating element, which is different from the embodiment 1 in that the heating circuit is a single track circuit, such as Figure 2 shown.

[0127] The preparation method is the same as that in Example 1 and will not be described again here.

[0128] Example 9

[0129] A ceramic heating element, which differs from Example 1 in that: the heating circuit is a double-track circuit, wherein the line width L of the heating circuit is 0.8 mm, and the ratio of the spacing H between two adjacent heating circuits to the line width L of the heating circuit is 0.8:1.

[0130] The preparation method is the same as that in Example 1 and will not be described again here.

[0131] Example 10 to Example 13

[0132] A ceramic heating element, which differs from Example 1 in that the raw material components of the ceramic powder in the ceramic green body slurry are different, wherein the raw materials of each component are shown in Table 2 below.

[0133] Table 2: Raw materials of ceramic powder in ceramic green body slurry (by weight)

[0134]

[0135]

[0136] The preparation method is the same as that in Example 1 and will not be described again here.

[0137] Comparative Example 1 to Comparative Example 5

[0138] A ceramic heating element, which differs from Example 1 in that the raw material components of the ceramic powder in the ceramic green body slurry are different, wherein the raw materials of each component are shown in Table 3 below.

[0139] Table 3: Raw materials of various components of ceramic powder in ceramic green body slurry (by weight)

[0140] Components Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Zirconia 68 68 68 68 68 Micron Alumina 30 30 30 30 30 Silicon Nitride / 30 3 3 3 Sintering Aids 1 1 1 1 1 Nano-alumina 1# 0.5 0.5 / / / Nano-alumina 4# / / / 0.5 / Alumina 5# / / / / 0.5

[0141] The preparation method is the same as that in Example 1 and will not be described again here.

[0142] Results

[0143] The ceramic substrates of the above embodiments and comparative examples or the ceramic heating elements made thereof are tested by the following performance testing methods:

[0144] Flexural strength: According to the standard test method specified in GB / T4741-1999 Ceramic Material Flexural Strength Test Method, the test conditions are: using a push-pull dynamometer for testing, and the test temperature is 25±3℃.

[0145] Thermal conductivity: Tested using a thermal conductivity tester in accordance with the standard test method specified in GB / T39862-2021 Testing of thermal conductivity of high thermal conductivity ceramics.

[0146] Surface roughness: GB / T13841-1992 Surface roughness of electronic ceramic parts, tested with a torsion spring meter. The lower the surface roughness of the ceramic substrate, the smaller the number after Ra, indicating that the density of the ceramic substrate is better.

[0147] Temperature zone uniformity of ceramic heating element: The overall length of the ceramic heating element is 17mm. Test conditions: Tested in an ambient temperature of 25±1℃; in a windless closed environment, the highest temperature on the ceramic substrate of the ceramic heating element is stabilized at 350±3℃, and a sample picture is taken after 5 minutes; tested with a thermal imager. The highest temperature point of the ceramic substrate of the ceramic heating element usually appears near the center, and the temperature of the ceramic substrate gradually decreases from the highest temperature point to the surrounding direction. It is generally believed that the temperature of the highest temperature point (about 350℃) Tmax~Tmax-5℃ temperature zone (hereinafter referred to as the 5℃ temperature zone range) or Tmax~Tmax-10℃ temperature zone (hereinafter referred to as the 10℃ temperature zone range) has the best heating effect on tobacco, so the larger the range of these two temperatures, the better the temperature zone uniformity is considered. Since the ceramic substrate is in the shape of a long strip, the shape of the temperature zone is also in the shape of a long strip. In the test of the present invention, the length of the 5℃ temperature zone range and the 10℃ temperature zone range of the ceramic substrate in the length direction is mainly measured (taking the 5℃ temperature zone range as an example, such as Figure 3 As shown in the figure, the distance between the two points pointed by the yellow arrows in the length direction of the ceramic substrate is the length of the 5°C temperature zone). The longer the length of the temperature zone, the larger the range of the temperature zone and the better the uniformity of the temperature zone.

[0148] The specific test results of each embodiment are described in Table 4 below:

[0149] Table 4

[0150] Group Example 1 Example 2 Example 3 Example 4 Example 5 Flexural strength(kgf) 33 32 34 34.5 35 Thermal conductivity (W / (m·k)) 31 28 34 37 39 Surface roughness Ra6.3 Ra6.3 Ra12.5 Ra12.5 Ra12.5 Length of 5℃ temperature range (mm) 3.16 2.55 2.68 2.64 2.62 Length of 10℃ temperature range (mm) 4.68 4.38 4.51 4.49 4.45

[0151] Table 4

[0152] Group Example 6 Example 7 Example 8 Example 9 Example 10 Flexural strength(kgf) 31.5 35.4 33 33 33 Thermal conductivity (W / (m·k)) 28 30 31 31 31 Surface roughness Ra6.3 Ra12.5 Ra6.3 Ra6.3 Ra6.3 Length of 5℃ temperature range (mm) 2.52 2.47 3.12 3.25 3.20 Length of 10℃ temperature range (mm) 4.33 4.30 4.68 4.81 4.78

[0153] Table 4

[0154] Group Embodiment 11 Example 12 Embodiment 13 Flexural strength(kgf) 33 33 33 Thermal conductivity (W / (m·k)) 31 30 31 Surface roughness Ra6.3 Ra6.3 Ra6.3 Length of 5℃ temperature range (mm) 3.18 2.80 2.91 Length of 10℃ temperature range (mm) 4.75 4.57 4.60

[0155] The specific test results of each comparative example are described in Table 5 below:

[0156] Table 5

[0157] Group Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Flexural strength(kgf) 21 36 34 33 33 Thermal conductivity (W / (m·k)) 17 40 31 31 30 Surface roughness Ra6.3 Ra25 Ra25 Ra25 Ra25 Length of 5℃ temperature range (mm) 1.61 1.89 1.70 1.72 1.68 Length of 10℃ temperature range (mm) 2.92 3.48 3.31 3.31 3.27

[0158] From Table 4 and Table 5, we can see that:

[0159] The thermal conductivity of each embodiment is above 28W / (m·k), and the surface roughness is below Ra12.5. Correspondingly, the length of the 5°C temperature range of the ceramic substrate of the ceramic heating element is above 2.47mm, and the length of the 10°C temperature range is above 4.30mm, indicating that the temperature uniformity of the ceramic substrate of the present invention is good, which can fully heat the tobacco, increase the amount of smoke, and improve the user's smoking taste. In addition, silicon nitride can also significantly improve the flexural strength of the ceramic substrate of the present invention.

[0160] The amount of silicon nitride used in Examples 2, 1, 3, 4 and 5 gradually increases, and the temperature zone uniformity first increases and then decreases. This is because as the amount of silicon nitride increases, the thermal conductivity of the ceramic substrate increases, but when the amount of silicon nitride continues to increase, the roughness of the ceramic substrate increases, and the fit between the ceramic substrate and the heating component decreases, resulting in the temperature zone uniformity no longer improving or even gradually decreasing.

[0161] The amount of nano-alumina used in Examples 1, 10 and 11 gradually increases, and the temperature zone uniformity first increases and then decreases. This is because within a certain range of dosage, the more nano-alumina is used, the lower the roughness of the ceramic substrate, which leads to better temperature zone uniformity. When the amount of nano-alumina is further increased, the grain growth is not inhibited during sintering, the voids increase, and the roughness begins to increase, resulting in a decrease in temperature zone uniformity.

[0162] Comparative Example 1 does not add silicon nitride, and its thermal conductivity is too low, resulting in poor uniformity in the temperature zone. Comparative Example 2 adds too much silicon nitride, resulting in a significantly higher surface roughness, which in turn leads to poor uniformity in the temperature zone. Comparative Example 3 does not add nano-alumina, which will cause the ceramic grains to be sparsely arranged and the ceramic surface roughness to increase, resulting in an uneven temperature zone in the heating body. Comparative Example 4 uses nano-alumina 4#, and because of its relatively small average particle size, it will cause the ceramic grains to be sparsely arranged and the ceramic surface roughness to increase, resulting in an uneven temperature zone in the heating body. Comparative Example 5 uses alumina 5#, and because of its relatively large average particle size, the ceramic voids increase, and the ceramic surface roughness increases, resulting in an uneven temperature zone in the heating body.

[0163] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A ceramic substrate, characterized in that: The ceramic green body slurry is processed and prepared, wherein the ceramic green body slurry comprises the following components in parts by weight: 50-90 parts of zirconium oxide, 18-50 parts of micron-grade aluminum oxide, 1-13 parts of silicon nitride, 0.1-2 parts of nano-grade aluminum oxide, and 0.1-5 parts of sintering aid; the average particle size of the nano-grade aluminum oxide is 300-800nm.

2. The ceramic substrate according to claim 1, characterized in that: The average particle size of the micron-sized aluminum oxide is 5-10 μm.

3. The ceramic substrate according to claim 1 or 2, characterized in that: The sintering aid is a mixture of magnesium oxide, calcium oxide, silicon dioxide and yttrium trioxide, and the weight ratio of magnesium oxide, calcium oxide, silicon dioxide and yttrium trioxide is (3.9-5): (3.5-4): (0.1-0.3): (0.1-0.3).

4. A ceramic heating element, characterized in that: It comprises the ceramic substrate according to any one of claims 1 to 3, and a first insulating layer arranged on the surface of the ceramic substrate, a heating layer arranged on the surface of the first insulating layer, and a second insulating layer arranged on the surface of the heating layer.

5. The ceramic heating element according to claim 4, characterized in that: The heating layer includes at least one group of heating circuits; the heating circuits are single-track circuits or multi-track circuits; the multi-track circuits include at least two single-track circuits parallel to each other.

6. The ceramic heating element according to claim 4, characterized in that: The heating layer is printed by metal paste, and the metal paste is a mixture of resistor metal paste and porcelain paste, and the weight ratio of resistor metal paste to porcelain paste is (80-97): (3-20); the resistor metal paste is composed of the following components: 20-80 parts of pineol, 1-8 parts of tributyl citrate, 0.1-5 parts of diethylene glycol butyl ether acetate, 1-8 parts of ethyl cellulose and 60-98 parts of tungsten powder; the porcelain paste is composed of the following components: 20-80 parts of pineol, 1-10 parts of tributyl citrate, 0.1-10 parts of diethylene glycol butyl ether acetate, 1-10 parts of ethyl cellulose and 50-95 parts of porcelain powder.

7. The ceramic heating element according to claim 4, characterized in that: The first insulating layer is formed by printing a first insulating layer slurry, and the second insulating layer is formed by printing a second insulating layer slurry; the first insulating layer slurry consists of the following components: 20-60 parts of pineol, 1-5 parts of tributyl citrate, 0.1-2 parts of diethylene glycol butyl ether acetate, 1-5 parts of ethyl cellulose, 80-98 parts of aluminum oxide, 0.1-2 parts of calcium oxide, 0.1-2 parts of magnesium oxide and 0.1-1 parts of silicon dioxide; the second insulating layer slurry consists of the following components: 20-60 parts of pineol, 1-5 parts of tributyl citrate, 0.1-2 parts of diethylene glycol butyl ether acetate, 1-5 parts of ethyl cellulose, 80-98 parts of aluminum oxide, 0.1-2 parts of calcium oxide, 0.1-2 parts of magnesium oxide and 0.1-1 parts of silicon dioxide.

8. The method for preparing the ceramic heating element according to any one of claims 4 to 7, characterized in that: The steps include: S1. The ceramic green body slurry is tape-cast to obtain a ceramic substrate; S2. Prepare the first insulating layer by printing the first insulating layer slurry on the surface of the ceramic substrate of S1, prepare the heating layer by printing the metal slurry on the surface of the first insulating layer, prepare the second insulating layer by printing the second insulating layer slurry on the surface of the heating layer, and sinter to obtain a ceramic heating element.

9. Use of the ceramic heating element according to any one of claims 4 to 7 in the preparation of heat-not-burn cigarette smoking articles.

10. A heat-not-burn cigarette smoking device, characterized in that: It comprises the ceramic heating element as described in any one of claims 4 to 7.

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