Conductive ceramic heating element, preparation method thereof and electronic cigarette

Abstract

The invention provides a conductive ceramic heating element, the conductive ceramic heating element is provided with a first end and a second end which are oppositely arranged, and the conductivity of the conductive ceramic heating element is gradually increased in the direction from the first end to the second end. When the conductive ceramic heating body is used, a gradually-changed heating area can be formed, the heat utilization rate is guaranteed, the influence caused by mismatching of thermal expansion and thermal stress is relieved, and then the use performance of the conductive ceramic heating body is improved. The invention further provides a preparation method of the conductive ceramic heating body and an electronic cigarette.

Description

Technical Field

[0001] The present application relates to the technical field of electronic cigarettes, and in particular to a conductive ceramic heating element, a preparation method thereof, and an electronic cigarette. Background Art

[0002] Heat-not-burn electronic cigarettes are electronic cigarettes that use a heating element to heat tobacco leaves until they emit smoke. In related technologies, the heating element can be a conductive ceramic, but conductive ceramics are prone to thermal expansion after heating, which affects the structural stability of the conductive ceramics. At the same time, the thermal stress between the heated conductive ceramics and other structural parts does not match, affecting the connection between the conductive ceramics and other structural parts, which in turn affects the use of electronic cigarettes. Summary of the invention

[0003] In view of this, the present application provides a conductive ceramic heating element, a preparation method thereof, and an electronic cigarette. The electrical conductivity of the conductive ceramic heating element gradually changes, and a gradual heating zone can be formed when the conductive ceramic heating element is used, which not only ensures the heat utilization rate, but also alleviates the effects of thermal expansion and thermal stress mismatch, thereby improving the performance of the conductive ceramic heating element.

[0004] In a first aspect, the present application provides a conductive ceramic heating element, which has a first end and a second end that are relatively arranged, and the electrical conductivity of the conductive ceramic heating element gradually increases along the direction from the first end to the second end.

[0005] Optionally, along the direction from the first end to the second end, the conductivity of the conductive ceramic heating element gradually increases from 10S / cm-90S / cm to 0.5×10 4 S / cm-9×10 4 S / cm.

[0006] Optionally, the material of the conductive ceramic heating element includes insulating ceramic material, conductive ceramic material and conductive non-ceramic material, and the conductive non-ceramic material includes acid-resistant material.

[0007] Furthermore, the mass content of the insulating ceramic material in the conductive ceramic heating element is 65%-95%.

[0008] Furthermore, the mass content of the conductive ceramic material in the conductive ceramic heating element is 4.5%-34.5%.

[0009] Furthermore, the mass content of the conductive non-ceramic material in the conductive ceramic heating element is 0.5%-5%.

[0010] Furthermore, along the direction from the first end to the second end, the mass content of the conductive non-ceramic material gradually increases.

[0011] Furthermore, the mass content of the acid-resistant material gradually increases along the direction from the first end to the second end.

[0012] Furthermore, the conductive non-ceramic material also includes an acid-resistant material, and the mass ratio of the non-acid-resistant material to the acid-resistant material in the conductive ceramic heating element is 1:(0.05-9).

[0013] Furthermore, along the direction from the first end to the second end, the mass content of the acid-resistant material in the conductive non-ceramic material gradually increases from 0%-10% to 10%-100%, and the mass content of the acid-resistant material gradually decreases from 90%-100% to 0%-90%.

[0014] Furthermore, the material of the conductive ceramic heating element also includes a sintering aid, and the mass content of the sintering aid in the conductive ceramic heating element is 0.5%-3%.

[0015] In a second aspect, the present application provides a method for preparing a conductive ceramic heating element, comprising:

[0016] The insulating ceramic material, the conductive ceramic material, the conductive non-ceramic material and the solvent are mixed and then formed into a green body, wherein the conductive non-ceramic material includes an acid-resistant material;

[0017] sintering the green body to obtain a preform;

[0018] The preform is etched with acid solution to obtain a conductive ceramic heating element, wherein the conductive ceramic heating element has a first end and a second end that are relatively arranged, and the conductivity of the conductive ceramic heating element gradually increases along the direction from the first end to the second end.

[0019] Optionally, etching the preform with acid solution includes: placing the preform in the acid solution for etching, and moving the preform during the etching until the preform leaves the acid solution, wherein the movement speed is 0.05 mm / min-1 mm / min.

[0020] In a third aspect, the present application provides an electronic cigarette, comprising the conductive ceramic heating element described in the first aspect or the conductive ceramic heating element prepared by the preparation method described in the second aspect.

[0021] The conductivity of the conductive ceramic heating element provided by the present application changes gradually. When the conductive ceramic heating element is energized to generate heat, less heat is generated in the area with higher conductivity, and more heat is generated in the area with lower conductivity, so that the conductive ceramic heating element can form a temperature gradient from the first end to the second end, thereby improving the full utilization of the heat generated by the conductive ceramic heating element. At the same time, the gradual temperature can alleviate the thermal expansion and reduce the thermal stress difference between the conductive ceramic heating element and other structures, which is beneficial to the connection between the conductive ceramic heating element and other structures and improves the use performance of the conductive ceramic heating element. The preparation method of the conductive ceramic heating element is simple and easy to operate, which is beneficial to the use of the conductive ceramic heating element. The electronic cigarette with the conductive ceramic heating element has high heat utilization rate and strong structural reliability, which is beneficial to the use of the electronic cigarette. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the prior art description. The specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0023] Figure 1 A schematic diagram of the structure of a conductive ceramic heating element provided in one embodiment of the present application.

[0024] Figure 2 A flow chart of a method for preparing a conductive ceramic heating element provided in one embodiment of the present application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] See also Figure 1, is a schematic diagram of the structure of a conductive ceramic heating element provided in an embodiment of the present application, wherein the conductive ceramic heating element 100 has a first end 101 and a second end 102 arranged relatively to each other, and the conductivity of the conductive ceramic heating element 100 gradually increases in the direction from the first end 101 to the second end 102. That is to say, the conductivity of the first end of the conductive ceramic heating element is relatively small, the resistance is relatively large, the heat generated after power-on is relatively more, and the temperature is relatively high, while the conductivity of the second end is relatively large, the resistance is relatively small, the heat generated after power-on is relatively less, and the temperature is relatively low, so that the conductive ceramic heating element after power-on forms a trend of gradually decreasing temperature from the first end to the second end. In the related art, when the conductive ceramic heating element is used in an electronic cigarette, since the heated object such as tobacco leaves does not completely cover the conductive ceramic heating element, the heat generated by the uncovered conductive ceramic heating element is lost, and the heat utilization rate is low; at the same time, the conductive ceramic heating element will undergo thermal expansion after heating, which affects its structural stability, and the mismatch of thermal stress will affect the connection between the conductive ceramic heating element and other structures. The conductivity gradient of the conductive ceramic heating element provided by the present application can form a temperature gradient after power is turned on, so that the heat generated by the conductive ceramic heating element can be efficiently utilized, heat loss can be avoided, and heat utilization rate can be improved; at the same time, the lower temperature area provides a buffer area for the thermal expansion of the conductive ceramic heating element after heating, which can effectively suppress the adverse effects of the thermal expansion of the conductive ceramic heating element and improve the structural stability of the conductive ceramic heating element. At the same time, the thermal stress matching between the conductive ceramic heating elements in different temperature zones and other structures is improved, which can effectively suppress the influence caused by thermal stress mismatch and improve the performance and service life of the conductive ceramic heating element.

[0027] In the present application, when the conductivity of the conductive ceramic heating element is detected, any position on the conductive ceramic heating element is used as the origin, one electrode is connected to the origin, and the other electrode is connected to any position in the direction from the first end to the second end, and the conductivity at any position in the direction from the first end to the second end is detected, so as to obtain the conductivity distribution in the direction from the first end to the second end. In the present application, the conductivity of the conductive ceramic heating element gradually increases along the direction from the first end to the second end; the "gradual increase" in the present application can be a linear increase or a nonlinear increase, etc., and the nonlinear increase can be a parabolic increase, a quasi-parabolic increase, a gradient increase, etc. In one embodiment of the present application, the gradual increase can be first kept constant and then increased nonlinearly. In another embodiment of the present application, the gradual increase can be a linear increase. In yet another embodiment of the present application, the gradual increase can be first kept constant and then increased gradiently. The present application does not limit the shape of the conductive ceramic heating element, and the shape of the conductive ceramic heating element can be set according to the application needs. Specifically, the conductive ceramic heating element can be a regular shape, such as a cuboid, a cube, a cylinder, a cone, etc., or an irregular shape, for example Figure 1The conductive ceramic heating element shown in has a pointed end. In one embodiment of the present application, the length of the conductive ceramic heating element is 10cm-15cm, the width is 0.5cm-2cm, and the thickness is 0.05cm-1cm. The conductive ceramic heating element has a regular shape, which is conducive to the arrangement of the conductive ceramic heating element in the electronic cigarette, and is also conducive to the coating of the heated object to improve the heating efficiency. Specifically, the length of the conductive ceramic heating element may be but is not limited to 10cm, 11cm, 12cm, 13cm, 14cm or 15cm, etc., the width may be but is not limited to 0.5cm, 1cm, 1.5cm or 2cm, etc., and the thickness may be but is not limited to 0.05cm, 0.08cm, 0.1cm, 0.3cm, 0.5cm, 0.8cm or 1cm, etc. The first end and the second end of the conductive ceramic heating element are arranged opposite to each other, which is also referred to as being arranged opposite to each other; for example, when the conductive ceramic heating element is a rectangular parallelepiped, the two ends along its length direction may be the first end and the second end, or the two ends along its width direction may be the first end or the second end, or the two ends along its thickness direction may be the first end or the second end. In one embodiment of the present application, the conductive ceramic heating element has a first end and a second end arranged opposite to each other in its extension direction. The extension direction of the conductive ceramic heating element is the extension direction of the maximum side length among all surfaces of the conductive ceramic heating element. In one embodiment of the present application, the direction from the first end to the second end may be the length direction of the conductive ceramic heating element; that is, along the length direction of the conductive ceramic heating element, the conductivity of the conductive ceramic heating element gradually increases.

[0028] In one embodiment of the present application, the conductivity of the conductive ceramic heating element gradually increases from 10S / cm-90S / cm to 0.5×10 4 S / cm-9×10 4 S / cm. That is to say, the minimum conductivity of the conductive ceramic heating element is 10S / cm-90S / cm, and the maximum conductivity is 0.5×10 4 S / cm-9×10 4 S / cm; the conductivity span of the conductive ceramic heating element is suitable, which is conducive to improving the temperature span of the conductive ceramic heating element after heating, so that the higher temperature area can fully heat the heated object, and the lower temperature area can improve the structural stability of the conductive ceramic heating element, thereby further improving the performance and service life of the conductive ceramic heating element. Specifically, the minimum conductivity of the conductive ceramic heating element can be but not limited to 10S / cm-30S / cm, 20S / cm-50S / cm, 30S / cm-60S / cm, 40S / cm-80S / cm or 60S / cm-90S / cm, etc., and the maximum conductivity of the conductive ceramic heating element can be but not limited to 0.5×10 4 S / cm-2×10 4 S / cm, 1×104 S / cm-3×10 4 S / cm, 2×10 4 S / cm-5×10 4 S / cm, 4×10 4 S / cm-7×10 4 S / cm or 6×10 4 S / cm-9×10 4 In one embodiment of the present application, the conductivity of the conductive ceramic heating element can be gradually increased from 60S / cm-90S / cm to 6×10 4 S / cm-9×10 4 In one embodiment of the present application, the conductivity of the conductive ceramic heating element can gradually increase from 40 S / cm to 90 S / cm to 6×10 4 S / cm-9×10 4 S / cm.

[0029] In one embodiment of the present application, the material of the conductive ceramic heating element includes insulating ceramic material, conductive ceramic material and conductive non-ceramic material, and the conductive non-ceramic material includes acid-resistant material. The insulating ceramic material ensures the heating performance of the conductive ceramic heating element, the conductive ceramic material ensures the conductive performance of the conductive ceramic heating element, and the conductive non-ceramic material ensures the conductive performance of the conductive ceramic heating element and the gradual distribution of conductivity. In the present application, the insulating ceramic material is a non-conductive ceramic material with a resistivity greater than 10 7 Ω·cm; Conductive ceramic material is a ceramic material with conductive properties, and its resistivity is less than or equal to 10 7 Ω·cm; acid-resistant materials are materials that have electrical conductivity and can react with acid; the resistivity in this application refers to the resistivity value at 25°C. In one embodiment of this application, the resistivity of the conductive ceramic material can be less than or equal to 10 3 Ω·cm. In another embodiment of the present application, the resistivity of the conductive ceramic material may be less than or equal to 10 2 Ω·cm.

[0030] In one embodiment of the present application, the mass content of the insulating ceramic material in the conductive ceramic heating element is 65%-95%, which is conducive to increasing the temperature of the conductive ceramic heating element after power is supplied, helps to heat the heated object, and improves the heating efficiency of the conductive ceramic heating element. That is to say, the insulating ceramic material in the conductive ceramic heating element is the main component. Specifically, the mass content of the insulating ceramic material in the conductive ceramic heating element may be, but is not limited to, 65%, 68%, 70%, 75%, 77%, 80%, 84%, 85%, 90% or 95%, etc. In one embodiment of the present application, the mass content of the insulating ceramic material in the conductive ceramic heating element may be 65%-90%. In another embodiment of the present application, the mass content of the insulating ceramic material in the conductive ceramic heating element may be 65%-80%. In one embodiment of the present application, the insulating ceramic material includes at least one of zirconium oxide and aluminum oxide. The above insulating ceramic material is conducive to improving the mechanical properties of the conductive ceramic heating element and further improving the service life of the conductive ceramic heating element.

[0031] In one embodiment of the present application, the mass content of the conductive ceramic material in the conductive ceramic heating element is 4.5%-34.5%, which is beneficial to improve the conductive performance and conductivity of the conductive ceramic heating element. Specifically, the mass content of the conductive ceramic material in the conductive ceramic heating element may be, but is not limited to, 4.5%, 5%, 10%, 12%, 15%, 16%, 20%, 25%, 28%, 30% or 34%, etc. In one embodiment of the present application, the mass content of the conductive ceramic material in the conductive ceramic heating element may be 10%-33%. In another embodiment of the present application, the mass content of the conductive ceramic material in the conductive ceramic heating element may be 20%-30%. In one embodiment of the present application, the conductive ceramic material includes at least one of silicon carbide and molybdenum disilicide. The above-mentioned conductive ceramic material is beneficial to improve the conductivity of the conductive ceramic heating element and enhance the mechanical properties of the conductive ceramic heating element, which is beneficial to the use of the conductive ceramic heating element. It can be understood that the insulating ceramic material and the conductive ceramic material in the present application are acid-resistant and do not react with acid.

[0032] In one embodiment of the present application, the mass content of the conductive non-ceramic material in the conductive ceramic heating element is 0.5%-5%, which is conducive to the regulation of the conductivity of the conductive ceramic heating element. Specifically, the mass content of the conductive non-ceramic material in the conductive ceramic heating element may be, but is not limited to, 0.5%, 1%, 2%, 2.5%, 3%, 3.7%, 4%, 4.2%, 4.5% or 5%, etc. In one embodiment of the present application, the mass content of the conductive non-ceramic material in the conductive ceramic heating element may be 0.5%-3%. In one embodiment of the present application, the mass content of the conductive non-ceramic material in the conductive ceramic heating element may be 3%-5%. The conductive non-ceramic material in the present application includes an acid-resistant material, that is, a conductive substance that can react with acid, which may be a metal substance or a non-metal substance. In one embodiment of the present application, the acid-resistant material includes at least one of aluminum, zinc, iron, tin, lead, nickel, chromium, titanium, cobalt and manganese.

[0033] In one embodiment of the present application, the conductive non-ceramic material also includes an acid-resistant material. Acid-resistant materials are conductive materials that do not react with acids, and can be metal materials or non-metal materials. The conductive ceramic heating element has an acid-resistant material that can further improve its strength, which is beneficial to its use. In one embodiment of the present application, the acid-resistant material includes at least one of copper, silver, platinum, gold, tungsten and molybdenum. In one embodiment of the present application, the mass ratio of the non-acid-resistant material and the acid-resistant material in the conductive ceramic heating element is 1: (0.05-9), which can not only regulate the conductivity of the conductive ceramic heating element, but also ensure the strength of the conductive ceramic heating element and improve the performance of the conductive ceramic heating element. Specifically, the mass ratio of the non-acid-resistant material and the acid-resistant material in the conductive ceramic heating element can be, but not limited to, 1: 0.05, 1: 0.08, 1: 0.1, 1: 0.15, 1: 0.2, 1: 0.5, 1: 1, 1: 3, 1: 5, 1: 6, 1: 8 or 1: 9, etc.

[0034] In one embodiment of the present application, the mass content of the conductive non-ceramic material in the conductive ceramic heating element gradually increases in the direction from the first end to the second end. The change in the mass content of the conductive non-ceramic material in the conductive ceramic heating element can regulate the change in the electrical conductivity of the conductive ceramic heating element. The electrical conductivity of the area with a relatively small mass content of the conductive non-ceramic material is relatively low, and the electrical conductivity of the area with a relatively high mass content of the conductive non-ceramic material is relatively high. In one embodiment of the present application, the mass content of the acid-resistant material in the conductive ceramic heating element gradually increases in the direction from the first end to the second end. The change in the mass content of the acid-resistant material is beneficial to the regulation of the electrical conductivity of the conductive ceramic heating element and the use of the electrical conductivity of the conductive ceramic heating element.

[0035] In one embodiment of the present application, when the conductive non-ceramic material includes an acid-resistant material, the mass of the acid-resistant material in the conductive ceramic heating element does not change significantly in the direction from the first end to the second end. That is, the mass difference of the acid-resistant material in the conductive ceramic heating element does not exceed 0.1% in the direction from the first end to the second end, which is conducive to ensuring the mechanical properties of the conductive ceramic heating element. That is, the mass difference of the acid-resistant material in the first region of the conductive ceramic heating element and the mass difference of the acid-resistant material in the second region of the conductive ceramic heating element does not exceed 0.1% in the direction from the first end to the second end.

[0036] In one embodiment of the present application, when the conductive non-ceramic material includes an acid-resistant material, along the direction from the first end to the second end, the mass content of the non-acid-resistant material in the conductive non-ceramic material gradually increases from 0%-10% to 10%-100%, and the mass content of the acid-resistant material gradually decreases from 90%-100% to 0%-90%; the change in the mass content of the non-acid-resistant material can regulate the conductivity of the conductive ceramic heating element, and the acid-resistant material ensures the mechanical properties of the conductive ceramic heating element. Specifically, along the direction from the first end to the second end, the mass content of the acid-resistant material in the conductive non-ceramic material can gradually increase from 0%-3%, 3%-5%, 1%-5% or 5%-9% to 20%-45%, 35%-50%, 40%-70% or 60%-100%, etc.; along the direction from the first end to the second end, the mass content of the acid-resistant material in the conductive non-ceramic material can gradually decrease from 97%-100%, 95%-97%, 95%-99% or 91%-95% to 55%-80%, 50%-65%, 30%-60% or 3%-40%, etc. In one embodiment of the present application, when the conductive non-ceramic material includes an acid-resistant material, along the direction from the first end to the second end, the mass content of the non-acid-resistant material in the conductive non-ceramic material gradually increases from 0%-10% to 20%-97%, and the mass content of the acid-resistant material gradually decreases from 90%-100% to 3%-80%. In one embodiment of the present application, when the conductive non-ceramic material includes an acid-resistant material, along the direction from the first end to the second end, the mass content of the non-acid-resistant material in the conductive non-ceramic material gradually increases from 0%-10% to 50%-95%, and the mass content of the acid-resistant material gradually decreases from 90%-100% to 5%-50%.

[0037] In one embodiment of the present application, the material of the conductive ceramic heating element also includes a sintering aid. The sintering aid in the conductive ceramic heating element is beneficial to improving the performance of the conductive ceramic heating element and is beneficial to the use of the conductive ceramic heating element. In one embodiment of the present application, the mass content of the sintering aid in the conductive ceramic heating element is 0.5%-3%. Specifically, the mass content of the sintering aid in the conductive ceramic heating element may be but is not limited to 0.5%, 1%, 1.5%, 2%, 2.5% or 3%, etc. In one embodiment, the mass content of the sintering aid in the conductive ceramic heating element is 0.5%-2%. In another embodiment, the mass content of the sintering aid in the conductive ceramic heating element is 0.8%-1.5%. In one embodiment of the present application, the sintering aid includes at least one of silicon nitride and silicon oxide.

[0038] In one embodiment of the present application, the conductive ceramic heating element comprises an insulating ceramic material having a mass content of 65%-95%, a conductive ceramic material having a mass content of 4.5%-34.5%, and a conductive non-ceramic material having a mass content of 0.5%-5%. In another embodiment of the present application, the conductive ceramic heating element comprises an insulating ceramic material having a mass content of 65%-94.5%, a conductive ceramic material having a mass content of 4.5%-34.5%, a conductive non-ceramic material having a mass content of 0.5%-5%, and a sintering aid having a mass content of 0.5%-3%.

[0039] The present application provides a method for preparing a conductive ceramic heating element, which can prepare a conductive ceramic heating element in any of the above embodiments. Figure 2 , is a flow chart of a method for preparing a conductive ceramic heating element provided in one embodiment of the present application, comprising:

[0040] S201: mixing insulating ceramic material, conductive ceramic material, conductive non-ceramic material and solvent and forming the mixture into a green body, wherein the conductive non-ceramic material includes acid-resistant material.

[0041] S202: Sintering the green body to obtain a preform.

[0042] S203: etching the preform with acid solution to obtain a conductive ceramic heating element, wherein the conductive ceramic heating element has a first end and a second end that are relatively arranged, and the conductivity of the conductive ceramic heating element gradually increases along the direction from the first end to the second end.

[0043] In the present application, the raw materials for preparing the conductive ceramic heating element are mixed, formed, sintered, and then etched to obtain a conductive ceramic heating element with a gradual change in conductivity; the preparation method is simple, easy to operate, does not require large equipment, and is conducive to the production and use of conductive ceramic heating elements.

[0044] In S201, the green body can be prepared by dry pressing or tape casting. In one embodiment of the present application, the insulating ceramic material, the conductive ceramic material, the conductive non-ceramic material and the solvent are mixed and granulated, and then the green body is obtained by dry pressing. At this time, the solvent can be a binder. In one embodiment of the present application, the pressure of dry pressing can be 40MPa-100MPa, which is conducive to improving the compactness of the green body and the conductive ceramic heating element, and improving the performance of the conductive ceramic heating element. Specifically, the pressure of dry pressing can be but not limited to 40MPa, 50MPa, 75MPa, 80MPa, 90MPa or 100MPa, etc. In another embodiment of the present application, the insulating ceramic material, the conductive ceramic material, the conductive non-ceramic material and the solvent are mixed to form a slurry, and the green body is obtained after tape casting. At this time, the solvent can be a substance that can disperse each raw material. The specific material of the solvent in the present application can be selected by the molding process, which is not limited to this. In the present application, the molding can be carried out in a mold to obtain a conductive ceramic heating element of the desired shape. In one embodiment of the present application, the mass content of the solvent in the mixed substance can be 1%-3% (such as 1%, 1.5%, 2%, 2.5% or 3%). In a specific embodiment, the mass content of the solvent in the mixed substance is 1%-3%, and the solvent is polyvinyl butyral ester. After mixing, the green body is obtained by dry pressing.

[0045] In one embodiment of the present application, an insulating ceramic material, a conductive ceramic material, a conductive non-ceramic material and a solvent can be mixed and molded to obtain a green body, and the conductive non-ceramic material includes an acid-resistant material and an acid-resistant material. The acid-resistant material and the acid-resistant material can jointly regulate the conductivity of the conductive ceramic heater, and the acid-resistant material can regulate the gradual distribution of the conductivity of the conductive ceramic heater. The acid-resistant material will not react with the acid solution and can be retained in the green body, further improving the strength of the conductive ceramic heater. In one embodiment of the present application, an insulating ceramic material, a conductive ceramic material, a conductive non-ceramic material, a sintering aid and a solvent can be mixed and molded to obtain a green body. The addition of a sintering aid can improve the performance of the conductive ceramic heater, which helps to improve the performance of the conductive ceramic heater.

[0046] In S202, the green body can be sintered to remove volatile and easily decomposable substances, such as organic matter, to ensure the mechanical properties of the conductive ceramic heating element. In one embodiment of the present application, the sintering temperature can be 1550°C-1750°C, the sintering time can be 0.5h-2h, and the sintering is carried out in a vacuum environment or an inert atmosphere with a reducing gas (such as hydrogen, etc.). The above sintering process is conducive to the removal of organic matter and other substances in the green body, thereby ensuring the performance of the preform and the conductive ceramic heating element. Specifically, the sintering temperature can be but not limited to 1550°C, 1570°C, 1600°C, 1620°C, 1650°C, 1675°C, 1700°C, 1730°C or 1750°C, etc., and the sintering time can be but not limited to 0.5h, 1h, 1.5h or 2h, etc. In one embodiment, the sintering can be carried out in a vacuum furnace.

[0047] In S203, by placing the preform in an acid solution, the acid-resistant material in the conductive non-ceramic material will react with the acid, and by controlling the reaction between the acid-resistant material in the preform and the acid, a conductive ceramic heating element with a gradually varying conductivity distribution is achieved; the acid-resistant material that reacts with the acid is etched away, providing a buffer space for the thermal expansion that occurs during use of the conductive ceramic heating element, thereby improving the structural stability of the conductive ceramic heating element.

[0048] In one embodiment of the present application, the concentration of the acid solution is 0.01mo / L-0.1mo / L. In the present application, the acid solution is a dilute acid, which can react with acid-resistant materials while not affecting the performance of other components; at the same time, the acid concentration is relatively low, which can avoid non-gradient etching caused by acid residue in the preform due to capillary phenomena when the concentration is high. Specifically, the concentration of the acid solution can be but not limited to 0.01mo / L, 0.03mo / L, 0.05mo / L, 0.07mo / L or 0.1mo / L. In one embodiment of the present application, the concentration of the acid solution can be 0.01mo / L-0.05mo / L. In another embodiment of the present application, the concentration of the acid solution can be 0.05mo / L-0.1mo / L. The acid solution in the present application can be an inorganic acid or an organic acid, as long as it can react with acid-resistant materials. Specifically, the acid solution can be but not limited to at least one of hydrochloric acid, sulfuric acid and nitric acid. In one embodiment of the present application, the etching temperature can be less than or equal to 25° C., which ensures the progress of etching while not damaging or etching other components in the preform, which is beneficial to improving the performance of the conductive ceramic heating element.

[0049] In one embodiment of the present application, an acid solution is used to etch a preform, including: placing the preform in an acid solution for etching, and moving the preform during etching until the preform leaves the acid solution. By moving the preform during the etching process, some areas of the preform can leave the acid solution first to avoid further reaction of the acid-resistant material with the acid solution, and some areas leave the acid solution later, so that the acid-resistant material reacts with the acid solution for a long time, and more acid-resistant materials are etched away, so that the mass content of the acid-resistant material in the etched preform has a gradual distribution, so that the conductivity of the conductive ceramic heating element can be gradually distributed; that is, by controlling the time when different areas of the preform are etched, the gradual distribution of the conductivity of the conductive ceramic heating element is achieved. It can be understood that the preform has a third end and a fourth end that are relatively set, and the preform is lifted in the direction from the third end to the fourth end during etching, so that the area close to the fourth end leaves the acid solution first, and the part close to the third end leaves the acid solution later, the third end after etching is the first end, and the fourth end after etching is the second end. In one embodiment of the present application, when the conductive non-ceramic material also includes an acid-resistant material, the acid-resistant material will not react with the acid during etching, thereby ensuring the toughness and strength of the conductive ceramic heating element, which is beneficial to improving the service life of the conductive ceramic heating element.

[0050] In the present application, the preform can be completely placed in the acid solution, and then the preform can be moved away from the acid solution until the preform completely leaves the acid solution; the preform can also be placed in the acid solution, and the fourth end is flush with the surface of the acid solution, and then the preform is moved away from the acid solution until the preform completely leaves the acid solution; the preform near the third end can also be placed in the acid solution, and the preform near the fourth end is not placed in the acid solution, and then the preform is moved away from the acid solution until the preform completely leaves the acid solution. In the present application, different forms of conductivity gradient distribution can be achieved by controlling the moving speed of the preform during etching, for example, it can move uniformly, it can also move non-uniformly, it can also move a certain distance and then stay for a period of time before continuing to move, etc. The moving mode can be selected as needed. In one embodiment of the present application, the moving speed of the preform during etching is 0.05mm / min-1mm / min, which is conducive to the appropriate conductivity span of the conductive ceramic heating element and the use of the conductive ceramic heating element. Specifically, the moving speed may be, but is not limited to, 0.05 mm / min, 0.1 mm / min, 0.3 mm / min, 0.5 mm / min, 0.6 mm / min, 0.9 mm / min or 1 mm / min.

[0051] The present application provides an electronic cigarette, comprising a conductive ceramic heating element in any of the above embodiments or a conductive ceramic heating element prepared by the preparation method in any of the above embodiments. The above conductive ceramic heating element has good performance and long service life, and can improve the product competitiveness of the electronic cigarette.

[0052] In one embodiment of the present application, a metal layer is provided on one side surface of the conductive ceramic heating element. Specifically, the metal layer can be formed by screen printing metal slurry, and the metal layer can cover part of the surface of the conductive ceramic heating element; the provided metal layer can be connected to the electrode of the power supply so that the conductive ceramic heating element is powered on to generate heat and realize the heating function. It can be understood that the electronic cigarette is a heat-not-burn electronic cigarette at this time; in the related art, the conductive ceramic heating element is placed in a heated object such as tobacco leaves, and the heated object does not completely wrap the conductive ceramic heating element, which will cause heat loss. The present application sets a conductive ceramic heating element with a gradient conductivity, so that the temperature at different positions of the conductive ceramic heating element when it heats up has a difference, so that the first end with low conductivity and high temperature when heating can be placed in the heated object, and the heated object can completely cover the area close to the first end; the second end with high conductivity and low temperature when heating can be wrapped by the heated object, or it can not be wrapped by the heated object. Since the area close to the second end generates less heat, it will not cause obvious Heat loss is reduced, thereby improving heat utilization rate; in the related art, after the conductive ceramic heating element is connected to other structures (such as metal layers, etc.), thermal expansion will occur due to the conductive ceramic heating element, and thermal mismatch will occur between the conductive ceramic heating element and other structures, affecting its performance; in the present application, a conductive ceramic heating element with changing conductivity is provided, so that the temperature of the conductive ceramic heating element after heating changes, and the etched acid-resistant metal material improves the thermal expansion of the conductive ceramic heating element, thereby improving the stability of the conductive ceramic heating element, and at the same time, the bonding performance between the conductive ceramic heating element with changing temperature and other structures is improved, thereby improving its performance and service life, which is beneficial to the use of electronic cigarettes.

[0053] In one embodiment of the present application, the electronic cigarette includes an atomizing core, and the atomizing core includes a conductive ceramic heating element. Specifically, the conductive ceramic heating element is a porous structure, which is conducive to atomization. It can be understood that the electronic cigarette is an atomizing type electronic cigarette.

[0054] The effect of the technical solution of this application is further illustrated below through specific examples.

[0055] Example 1

[0056] 65 parts by weight of zirconium oxide powder, 30 parts by weight of silicon carbide powder, 2.5 parts by weight of silicon nitride powder, 2.7 parts by weight of nickel powder and 0.3 parts by weight of copper powder were dry mixed to form a mixed powder. Polyvinyl butyral (PVB) was added to the mixed powder and granulated to obtain granulated powder, the mass of PVB accounting for 1% of the mass of the mixed powder. 5 g of granulated powder was placed in a mold (12 cm long and 1.2 cm wide) and maintained at a pressure of 40 MPa for 3 minutes to obtain a green body.

[0057] The green body is placed vertically in a vacuum furnace along the length direction and sintered at 1600° C. for 30 minutes to obtain a preform. The preform has a third end and a fourth end that are oppositely arranged along the length direction of the preform.

[0058] The preform is completely immersed in a dilute sulfuric acid solution (concentration of 0.1 mol / L) and etched with ultrasonic vibration, and the preform is lifted along the length direction of the preform at a speed of 1 mm / min until the preform completely leaves the dilute sulfuric acid solution, wherein the fourth end leaves the dilute sulfuric acid solution first and the third end leaves the dilute sulfuric acid solution last; then, the preform is washed with water and vacuum dried to obtain a conductive ceramic heating element, which has a first end and a second end relatively set, the first end is the third end after etching, and the second end is the fourth end after etching.

[0059] Example 2

[0060] 70 parts by weight of zirconium oxide powder, 20 parts by weight of silicon carbide powder, 2.5 parts by weight of silicon nitride powder, 2.8 parts by weight of nickel powder and 0.2 parts by weight of copper powder were dry mixed to form a mixed powder. PVB was added to the mixed powder and granulated to obtain granulated powder, the mass of PVB accounting for 1% of the mass of the mixed powder. 5 g of granulated powder was placed in a mold (12 cm long and 1.2 cm wide) and maintained at a pressure of 40 MPa for 3 minutes to obtain a green body.

[0061] The green body is placed vertically in a vacuum furnace along the length direction and sintered at 1600° C. for 30 minutes to obtain a preform. The preform has a third end and a fourth end that are oppositely arranged along the length direction of the preform.

[0062] The preform is completely immersed in a dilute sulfuric acid solution (concentration of 0.1 mol / L) and etched with ultrasonic vibration, and the preform is lifted along the length direction of the preform at a speed of 1 mm / min until the preform completely leaves the dilute sulfuric acid solution, wherein the fourth end leaves the dilute sulfuric acid solution first and the third end leaves the dilute sulfuric acid solution last; then, the preform is washed with water and vacuum dried to obtain a conductive ceramic heating element, which has a first end and a second end relatively set, the first end is the third end after etching, and the second end is the fourth end after etching.

[0063] Example 3

[0064] 70 parts by weight of zirconium oxide powder, 25 parts by weight of silicon carbide powder, 4.75 parts by weight of zinc powder and 0.25 parts by weight of copper powder were dry mixed to form a mixed powder. PVB was added to the mixed powder and granulated to obtain granulated powder, the mass of PVB accounting for 1% of the mass of the mixed powder. 5 g of granulated powder was placed in a mold (12 cm long and 1.2 cm wide) and maintained at a pressure of 40 MPa for 3 minutes to obtain a green body.

[0065] The green body is placed vertically in a vacuum furnace along the length direction and sintered at 1600° C. for 30 minutes to obtain a preform. The preform has a third end and a fourth end that are oppositely arranged along the length direction of the preform.

[0066] The preform is completely immersed in a dilute sulfuric acid solution (concentration of 0.01 mol / L) and etched with ultrasonic vibration, and the preform is lifted along the length direction of the preform at a speed of 1 mm / min until the preform completely leaves the dilute sulfuric acid solution, wherein the fourth end leaves the dilute sulfuric acid solution first and the third end leaves the dilute sulfuric acid solution last; then, the preform is washed with water and vacuum dried to obtain a conductive ceramic heating element, which has a first end and a second end relatively set, the first end is the third end after etching, and the second end is the fourth end after etching, and the mass ratio of zinc to copper in the conductive ceramic heating element is 1:0.1.

[0067] Example 4

[0068] It is substantially the same as Example 3, except that the etching time is shorter, so that the mass ratio of zinc to copper in the conductive ceramic heating element is 1:0.06.

[0069] Example 5

[0070] It is substantially the same as Example 3, except that the mixed powder includes 0.5 parts by weight of zinc powder and 4.5 parts by weight of copper powder, and the mass ratio of zinc to copper in the conductive ceramic heating element is 1:12.

[0071] Comparative Example 1

[0072] It is substantially the same as Example 3, except that etching is not performed and the preform is directly used as a conductive ceramic heating element.

[0073] Comparative Example 2

[0074] It is substantially the same as Example 3, except that 4.75 parts by weight of zinc powder and 0.25 parts by weight of copper powder are replaced with 5 parts by weight of copper powder.

[0075] Performance Testing

[0076] The conductivity of the conductive ceramic heating elements prepared in the above-mentioned embodiments and comparative examples was measured, wherein one electrode was fixed at the second end (as the origin), and the position of the other electrode on the conductive ceramic heating element was changed. The voltage, current and distance between the two electrodes were measured, and the average conductivity at positions at different distances from the origin along the length direction of the conductive ceramic heating element was calculated. The results are shown in Table 1.

[0077] Table 1 Conductivity test results

[0078]

[0079] After silk-screening metal electrodes on the surface of the conductive ceramic heating element prepared in the embodiment and the comparative example, the external circuit is soldered and the conductive ceramic heating element is heated by power. When the temperature rises to 250°C, the heating is stopped and the conductive ceramic heating element is cooled to room temperature with a room temperature (25°C) fan and heated to 250°C again. After 10,000 cycles, the tensile strength of the pads (pad length less than 3.5 mm, width less than 3 mm, height less than 1.5 mm) on the conductive ceramic heating elements of the embodiment and the comparative example is tested according to the IPC-2221 standard. The results are shown in Table 2.

[0080] Table 2 Tensile strength test results

[0081] <![CDATA[Tensile strength (kgf / mm 2 )]]> Example 1 0.33 Example 2 0.38 Example 3 0.47 Example 4 0.26 Example 5 0.25 Comparative Example 1 0.2 Comparative Example 2 0.2

[0082] It can be seen from the above results that compared with the comparative example, in the embodiments of the present application, the conductivity gradient of the conductive ceramic is changed by acid etching, so that the temperature gradient of the conductive ceramic heating element after heating changes, and the etched acid-inresistant metal material improves the thermal expansion of the conductive ceramic heating element, improves the stability of the conductive ceramic heating element, and at the same time, the bonding performance (tensile strength) between the temperature-changing conductive ceramic heating element and the welding electrode is improved, which improves the performance and service life of the conductive ceramic heating element, and is beneficial to the use of electronic cigarettes; at the same time, compared with Examples 4-5, the conductivity gradient change of the conductive ceramic heating element obtained in Examples 1-3 is appropriate, and the measured tensile strength is higher, which significantly improves the performance of the conductive ceramic heating element.

[0083] The above is an exemplary embodiment of the present application, but it should not be understood as limiting the scope of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application, and these improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. A conductive ceramic heating element, characterized in that: The conductive ceramic heating element has a first end and a second end that are arranged opposite to each other, and the conductivity of the conductive ceramic heating element gradually increases along the direction from the first end to the second end.

2. The conductive ceramic heating element according to claim 1, characterized in that: In the direction from the first end to the second end, the conductivity of the conductive ceramic heating element gradually increases from 10S / cm-90S / cm to 0.5×10 4 S / cm-9×10 4 S / cm.

3. The conductive ceramic heating element according to claim 1 or 2, characterized in that: The material of the conductive ceramic heating element includes insulating ceramic material, conductive ceramic material and conductive non-ceramic material, and the conductive non-ceramic material includes acid-resistant material; The mass content of the insulating ceramic material in the conductive ceramic heating element is 65%-95%; The mass content of the conductive ceramic material in the conductive ceramic heating element is 4.5%-34.5%; The mass content of the conductive non-ceramic material in the conductive ceramic heating element is 0.5%-5%.

4. The conductive ceramic heating element according to claim 3, characterized in that: The mass content of the conductive non-ceramic material gradually increases in a direction from the first end to the second end; The mass content of the acid-resistant material gradually increases along the direction from the first end to the second end.

5. The conductive ceramic heating element according to claim 3, characterized in that: The conductive non-ceramic material also includes an acid-resistant material. The mass ratio of the non-acid-resistant material to the acid-resistant material in the conductive ceramic heating element is 1:(0.05-9).

6. The conductive ceramic heating element according to claim 5, characterized in that: Along the direction from the first end to the second end, the mass content of the acid-resistant material in the conductive non-ceramic material gradually increases from 0%-10% to 10%-100%, and the mass content of the acid-resistant material gradually decreases from 90%-100% to 0%-90%.

7. The conductive ceramic heating element according to claim 3, characterized in that: The material of the conductive ceramic heating element also includes a sintering aid, and the mass content of the sintering aid in the conductive ceramic heating element is 0.5%-3%.

8. A method for preparing a conductive ceramic heating element, characterized in that: include: The insulating ceramic material, the conductive ceramic material, the conductive non-ceramic material and the solvent are mixed and then formed into a green body, wherein the conductive non-ceramic material includes an acid-resistant material; sintering the green body to obtain a preform; The preform is etched with acid solution to obtain a conductive ceramic heating element, wherein the conductive ceramic heating element has a first end and a second end that are relatively arranged, and the conductivity of the conductive ceramic heating element gradually increases along the direction from the first end to the second end.

9. The preparation method according to claim 8, characterized in that: The method of etching the preform with acid solution comprises: The preform is placed in the acid solution for etching, and the preform is moved during the etching until the preform leaves the acid solution, wherein the moving speed is 0.05 mm / min-1 mm / min.

10. An electronic cigarette, characterized in that: It comprises the conductive ceramic heating element as described in any one of claims 1 to 7 or the conductive ceramic heating element prepared by the preparation method as described in any one of claims 8 to 9.

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