Preparation methods for multi-sheet porous ceramic matrices and atomization core thereof

Abstract

Preparation methods for multi-sheet porous ceramic matrices (10, 20, 30, 40) and an atomization core thereof. The preparation method for the multi-sheet porous ceramic matrices (10, 20, 30, 40) comprises: (1) the preparation of ceramic powders, involving: weighing a plurality of groups of components in parts by weight, comprising 25-55 parts of an aggregate, 5-40 parts of a pore former, 5-19 parts of a sintering aid, and 5-35 parts of a powder dispersing agent; (2) the preparation of casting ceramic slurries, involving: weighing a plurality of groups of components in parts by weight, comprising 40-65 parts of each group of ceramic powder, 30-50 parts of a solvent, 0.1-3 parts of a slurry dispersing agent, 1-8 parts of a plasticizer, and 1-10 parts of a binder; (3) the preparation of ceramic green bodies, involving: respectively making the plurality of groups of casting ceramic slurries into a plurality of groups of sheet-like ceramic green bodies by means of a casting process; and (4) the preparation of multi-sheet porous ceramic matrices (10, 20, 30, 40), involving: vertically stacking a plurality of ceramic green bodies of different groups and / or the same group in sequence and then laminating same into an integral body, then feeding same into a furnace for de-binding and sintering, and finally cutting same into required shapes to obtain the multi-sheet porous ceramic matrices (10, 20, 30, 40).

Description

Preparation method of multi-layer porous ceramic substrate and atomizing core thereof Technical Field

[0001] The present invention belongs to the technical field of atomizing cores of electronic cigarette atomizers, and in particular relates to a multi-layer porous ceramic substrate and a method for preparing the atomizing core thereof. Background Art

[0002] The atomizing core of the electronic atomizer is used to heat the liquid to be atomized, i.e., the atomizing liquid, and atomize it into an aerosol or vapor, mist or smoke for the user to inhale. The atomizing liquid can be a cigarette liquid or a solution containing medicine for health and medical purposes. The electronic atomizer can be used for electronic cigarettes.

[0003] The atomizer core of current electronic atomizers includes a porous ceramic substrate as a liquid guide, and then a heating element such as a heating wire, heating sheet, or heating film is attached to the liquid guide. When the heating element is energized, it can be used to heat the atomized liquid on the liquid guide and atomize it into an aerosol, vapor, mist, or smoke. Existing porous ceramic substrates used as liquid guides are mainly formed into a ceramic green body in one step and sintered. The micropore structure within the ceramic green body is simple, with similar pore sizes. The liquid guide or liquid supply speed is single, which does not match the requirement of the heating element to consume atomized liquid at different power levels. This leads to an imbalance between liquid supply and atomization, causing the atomizer core of the electronic atomizer to easily suffer from problems such as dry burning and carbon deposition due to insufficient liquid supply during the atomization process, as well as oil explosion and leakage due to excessive liquid supply. Technical issues

[0004] The technical problem solved by the present invention is to overcome the deficiencies of the prior art and provide a method for preparing a multi-layer porous ceramic substrate and an atomizing core thereof. Technical Solutions

[0005] The technical solution of the present invention is a method for preparing a multi-layer porous ceramic substrate, which includes the following process flow:

[0006] (1) Preparation of ceramic powder:

[0007] Weigh components of several groups of ceramic powders by weight, wherein the components of any group of ceramic powders include: 25-55 parts of aggregate, 5-40 parts of pore former, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant, wherein the average particle size of the aggregate and / or pore former in each group of ceramic powders is different;

[0008] The aggregate is a material used to form a porous ceramic matrix skeleton after sintering, including at least one of kaolin, diatomaceous earth, alumina, silicon nitride, silicon carbide, quartz sand, glass sand, clay, feldspar powder, fused quartz, cordierite, and mullite;

[0009] The pore-forming agent is a material that vaporizes and evaporates during sintering to form micropores in the porous ceramic matrix, including at least one of graphite, starch, wood flour, flour, soybean flour, polystyrene microspheres, polymethyl methacrylate microspheres, sucrose, and fiber;

[0010] The sintering aid is a material used to bond aggregates and help sinter at a suitable temperature to form a porous ceramic matrix, including at least one of boron oxide, sodium silicate, silicon oxide, potassium oxide, lithium oxide, barium oxide, magnesium oxide, calcium oxide, iron oxide, titanium oxide, zinc oxide, and zirconium oxide;

[0011] The powder dispersant is a material used to promote uniform dispersion of aggregates and prevent precipitation and accumulation, including at least one of paraffin, beeswax, boric acid, oleic acid, stearic acid, polyethylene, polypropylene, polyvinyl acetate, polyvinyl acetal, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, perchlorethylene resin, polyacrylate, and polyamide;

[0012] The aggregates, pore formers, sintering aids and powder dispersants weighed in several groups are fully mixed in groups to obtain several groups of ceramic powders;

[0013] (2) Preparation of tape-cast ceramic slurry:

[0014] Weighing several groups of tape-cast ceramic slurry components by weight, wherein the components of each group of tape-cast ceramic slurry respectively include: 40-65 parts of ceramic powder from one of the several groups of ceramic powders, 30-50 parts of solvent, 0.1-3 parts of slurry dispersant, 1-8 parts of plasticizer, and 1-10 parts of binder;

[0015] The solvent is a material used to convert ceramic powder into a fluid, including at least one of ethanol, isopropyl alcohol, acetone, butanone, xylene, trichloroethylene, ethyl acetate, and butyl acetate;

[0016] The slurry dispersant is a material used to disperse the ceramic powder in the solvent, and includes at least one of oleic acid, boric acid, linseed oil, castor oil, stearic acid, and triolein;

[0017] The plasticizer is a material used to improve the plasticity of the ceramic green body, including at least one of polyethylene glycol and dibutyl phthalate;

[0018] The binder is a material used to improve the strength of the ceramic green body, including at least one of polymethyl acrylate, ethyl cellulose, polyethylene, polyvinyl butyral, and polyisobutylene;

[0019] The ceramic powder, dispersant, and solvent of several groups are weighed and fully mixed and ball-milled respectively, and then the plasticizer and binder are added respectively and further fully mixed and ball-milled to obtain several groups of tape-cast ceramic slurries;

[0020] (3) Preparation of ceramic green body:

[0021] The plurality of tape-cast ceramic slurries are respectively formed into a plurality of thin-sheet ceramic green sheets by a tape-casting process, and the plurality of ceramic green sheets are respectively cut into a plurality of ceramic green sheets;

[0022] (4) Preparation of multi-layer porous ceramic matrix:

[0023] A plurality of ceramic green sheets from different groups and / or different sheets from the same group are selected, stacked one above the other in order of the average particle size of the aggregate and / or pore-forming agent contained in each ceramic green sheet, and then pressed into a whole. The stacked sheets are then placed in a furnace for debinding and sintering. After sintering, the stacked sheets are removed and cut into desired shapes, thereby producing a multi-layered porous ceramic matrix having a plurality of ceramic sheets and vesicular micropores uniformly distributed therein. One of the ceramic green sheets constitutes one of the ceramic sheets after sintering.

[0024] Preferably, when preparing a multi-layer porous ceramic matrix, several groups of ceramic green sheets and 1 to several ceramic green sheets in each group are selected. The groups of ceramic green sheets are stacked from bottom to top in the order in which the average particle size of the aggregate and / or pore-forming agent contained in each group changes alternately or changes gradually from large to small, and then pressed into one body, so that after debinding and sintering, the multi-layer porous ceramic matrix having several levels of ceramic sheets and each level having 1 to several layers of ceramic sheets is obtained, the average pore size of the micropores in the ceramic sheets of the same level and different layers is the same, the average pore size of the micropores in the ceramic sheets of different levels is different, and the average pore size of the micropores in the ceramic sheets of the several levels in the order from bottom to top has a rule of alternating size or changing gradually from large to small.

[0025] Preferably, when preparing each group of the ceramic powder, the components of the ceramic powder weighed in parts by weight include: 35-55 parts of the aggregate, 25-30 parts of the pore former, 15-19 parts of the sintering aid, and 5-10 parts of the powder dispersant.

[0026] Preferably, it is characterized in that when preparing each group of the tape-cast ceramic slurry, the components of the tape-cast ceramic slurry weighed in parts by weight include: 45 to 55 parts of ceramic powder from one of the several groups of ceramic powders, 35 to 45 parts of solvent, 0.1 to 1 part of slurry dispersant, 1 to 5 parts of plasticizer, and 3 to 8 parts of binder.

[0027] Preferably, the average particle size of the aggregate is 5-100 um, or 5-50 um, or 10-30 um.

[0028] Preferably, the average particle size of the pore-forming agent is 5 to 100 um, or 15 to 80 um, or 25 to 60 um.

[0029] Preferably, when preparing the ceramic green body, a tape casting process is used to make each piece of the ceramic green body have a thickness of 0.1 to 0.6 mm, or 0.1 to 0.3 mm, or 0.25 to 0.45 mm, or 0.3 to 0.6 mm.

[0030] Preferably, the average pore size of the micropores of each ceramic layer of the multi-layer porous ceramic substrate is 10-50 um, or 15-45 um, or 20-40 um.

[0031] Preferably, the porosity of the micropores of each ceramic layer of the multi-layer porous ceramic substrate is 40%-65%, or 45-60%, or 48-56%.

[0032] Preferably, the thickness of each ceramic layer of the multi-layer porous ceramic substrate is 0.1-0.5 mm, or 0.1-0.25 mm, or 0.2-0.4 mm, or 0.25-0.5 mm.

[0033] Preferably, when preparing the multi-layer porous ceramic matrix, several groups of ceramic green sheets and one ceramic green sheet in each group are selected, and the groups of ceramic green sheets are stacked from bottom to top in the order of the average particle size of the aggregate and / or pore-forming agent contained in each group of ceramic green sheets, and then pressed into one body, so that after debinding and sintering, the multi-layer porous ceramic matrix having several levels of ceramic sheets and one ceramic sheet in each level is obtained.

[0034] Preferably, when preparing the multi-layer porous ceramic matrix, 4 to 10 groups of the ceramic green sheets are selected, and the number of ceramic layers of the porous ceramic matrix is ​​4 to 10 and the number of layers is 4 to 10.

[0035] Preferably, when preparing the multi-layer porous ceramic matrix, 4 to 6 groups of the ceramic green sheets are selected, and the number of ceramic layers of the porous ceramic matrix is ​​4 to 6 levels and the number of layers is 4 to 6.

[0036] Preferably, when preparing the multi-layer porous ceramic matrix, 4 groups, i.e., 4 pieces of the ceramic green body, are selected, wherein, in the order of stacking from bottom to top, the weight parts of the aggregate contained in the first ceramic green body are 40 to 46 parts, the average particle size of the aggregate is 70 to 75 μm, the weight parts of the pore-forming agent are 25 to 28 parts, and the average particle size of the pore-forming agent is 40 to 50 μm; the weight parts of the aggregate contained in the second ceramic green body are 45 to 50 parts, the average particle size of the aggregate is 40 to 60 μm, the weight parts of the pore-forming agent are The weight of the aggregate contained in the third ceramic green body is 40-48 parts, the average particle size of the aggregate is 15-30um, the weight of the pore former is 25-30 parts, and the average particle size of the pore former is 35-40um; the weight of the aggregate contained in the fourth ceramic green body is 35-45 parts, the average particle size of the aggregate is 10-20um, the weight of the pore former is 25-30 parts, and the average particle size of the pore former is 35-40um.

[0037] Preferably, when preparing the multi-layer porous ceramic matrix, 4 groups, i.e., 4 pieces of the ceramic green body, are selected, and the number of ceramic layers of the porous ceramic matrix is ​​4, wherein, in the order of stacking from bottom to top, the pore diameter of the micropores in the first ceramic layer is 40 to 50 um, the pore diameter of the micropores in the second ceramic layer is 30 to 40 um, the pore diameter of the micropores in the third ceramic layer is 20 to 30 um, and the pore diameter of the micropores in the fourth ceramic layer is 10 to 20 um.

[0038] Preferably, when preparing the multi-layer porous ceramic matrix, several groups of ceramic green sheets and two ceramic green sheets in each group are selected. The groups of ceramic green sheets are stacked from bottom to top in the order of the average particle size of the aggregate and / or pore-forming agent contained in each group of ceramic green sheets, and then pressed into one body, so that after debinding and sintering, the multi-layer porous ceramic matrix having several levels of ceramic sheets and two ceramic sheets in each level is obtained.

[0039] Preferably, when preparing the multi-layer porous ceramic matrix, the number of groups of the ceramic green body is selected to be 2 to 5, the level of the multi-layer porous ceramic matrix is ​​2 to 5, and the number of ceramic layers is twice the level.

[0040] Preferably, when preparing the multi-layer porous ceramic matrix, the number of groups of the ceramic green bodies is selected to be 3 or 4, the number of levels of the porous ceramic matrix is ​​obtained to be 3 or 4, and the number of ceramic layers is 6 or 8.

[0041] Preferably, when preparing the multi-layer porous ceramic matrix, the number of groups of the ceramic green embryos is selected to be 3, wherein, in order of stacking from bottom to top, the weight of the aggregate contained in the first group of ceramic green embryos is 40 to 46 parts, the average particle size of the aggregate is 60 to 75 μm, the weight of the pore-forming agent is 25 to 30 parts, and the average particle size of the pore-forming agent is 40 to 50 μm; the weight of the aggregate contained in the second group of ceramic green embryos is 40 to 48 parts, the average particle size of the aggregate is 15 to 50 μm, the weight of the pore-forming agent is 25 to 30 parts, and the average particle size of the pore-forming agent is 35 to 40 μm; the weight of the aggregate contained in the third group of ceramic green embryos is 35 to 45 parts, the average particle size of the aggregate is 10 to 20 μm, the weight of the pore-forming agent is 25 to 30 parts, and the average particle size of the pore-forming agent is 35 to 40 μm.

[0042] Preferably, when preparing the multi-layer porous ceramic matrix, the number of groups of the ceramic green body is selected to be 3, the number of levels of ceramic layers of the porous ceramic matrix is ​​3, and the number of layers of ceramic layers is 6. Among them, in the order of stacking from bottom to top, the pore size of the micropores in the first-level ceramic layer is 35-50um, the pore size of the micropores in the second-level ceramic layer is 20-35um, and the pore size of the micropores in the third-level ceramic layer is 10-20um.

[0043] Preferably, when preparing the multi-layer porous ceramic matrix, the number of groups of the ceramic green body is selected to be 4 groups, wherein, in the order of stacking from bottom to top, the weight parts of the aggregate contained in the first group of ceramic green bodies are 40 to 46 parts, the average particle size of the aggregate is 70 to 75 μm, the weight parts of the pore-forming agent are 25 to 28 parts, and the average particle size of the pore-forming agent is 40 to 50 μm; the weight parts of the aggregate contained in the second group of ceramic green bodies are 45 to 50 parts, the average particle size of the aggregate is 40 to 60 μm, the weight parts of the pore-forming agent are The weight of the aggregate contained in the third group of ceramic green bodies is 40-48 parts, the average particle size of the aggregate is 15-30um, the weight of the pore former is 25-30 parts, and the average particle size of the pore former is 35-40um; the weight of the aggregate contained in the fourth group of ceramic green bodies is 35-45 parts, the average particle size of the aggregate is 10-20um, the weight of the pore former is 25-30 parts, and the average particle size of the pore former is 35-40um.

[0044] Preferably, when preparing the multi-layer porous ceramic matrix, the number of groups of the ceramic green body is selected to be 4, the number of levels of the multi-layer porous ceramic matrix obtained is 4, and the number of layers of ceramic layers is 8, wherein, in the order of stacking from bottom to top, the pore diameter of the micropores in the first-level ceramic layer is 40-50um, the pore diameter of the micropores in the second-level ceramic layer is 30-40um, the pore diameter of the micropores in the third-level ceramic layer is 20-30um, and the pore diameter of the micropores in the fourth-level ceramic layer is 10-20um.

[0045] Another technical solution of the present invention is a method for preparing a multi-layer porous ceramic atomization core. First, a multi-layer porous ceramic substrate is prepared according to the above-mentioned method for preparing a multi-layer porous ceramic substrate, and then a metal slurry is prepared. One of the upper and lower surfaces of the multi-layer porous ceramic substrate is selected as the atomization surface, and the other surface is used as the liquid guide surface. The metal slurry is printed on both ends of the atomization surface by screen printing and sintered to obtain an electrode layer. Finally, a metal heating layer is obtained on the atomization surface by a metal sputtering coating process or by screen printing another metal slurry and then sintering. The metal heating layer covers the electrode layer, thereby obtaining a multi-layer porous ceramic atomization core.

[0046] Preferably, the side with smaller pore size of the micropores on the upper and lower surfaces of the multi-layer porous ceramic substrate is selected as the atomizing surface, and the other side is used as the liquid guiding surface. A metal heating layer is obtained on the atomizing surface by a metal sputtering coating process or by a screen printing metal slurry and then sintering process, that is, a multi-layer porous ceramic atomizing core is obtained. Beneficial effects

[0047] Unlike existing porous ceramics with a single pore structure, the present invention uses a tape casting process to prepare multiple groups of ceramic green sheets with a continuously varying particle size structure. These green sheets are then stacked, pressed, and fired to produce a porous ceramic matrix with multiple layers of varying pore sizes. Specifically, a multi-layer porous ceramic matrix with a gradient pore size structure can be formed. The green sheets are formed using a multi-layer lamination process. Compared to a single-stage forming process, the pressing and sintering of the multi-layer ceramic green sheets creates microscopic interlayer interfaces. The pore size of these interlayer interfaces lies between the pore sizes of the two layers, providing a transitional and buffering effect for the transport of the atomized liquid, facilitating its storage and transmission. In addition, multi-layer ceramic sheets can be stacked to prepare porous ceramics with a gradient pore structure. When applied to the atomization core of an electronic cigarette, the ceramic pore structure can be gradiently adjusted according to the ceramic sheets based on different heating methods and different viscosities of the smoke liquid. The porosity and pore size from the liquid guide surface to the atomization surface are adjusted layer by layer, so that the liquid supply and atomization of the porous ceramic matrix are balanced, achieving the advantages of both fast liquid guide and fine atomization, and improving the atomization experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] FIG1 is a perspective schematic diagram of a ceramic green body according to an embodiment of the present invention;

[0049] FIG2 is a perspective schematic diagram of four groups of ceramic green sheets stacked in accordance with Example 1 of the present invention;

[0050] FIG3 is a cross-sectional view of a multi-layer porous ceramic substrate according to Example 1 of the present invention;

[0051] FIG4 is a three-dimensional schematic diagram of two ceramic green sheets stacked in the same group according to Example 2 of the present invention;

[0052] FIG5 is a perspective schematic diagram of three groups of ceramic green sheets stacked in Example 2 of the present invention;

[0053] FIG6 is a cross-sectional view of a three-level multi-layer porous ceramic substrate according to a second embodiment of the present invention;

[0054] FIG7 is a three-dimensional schematic diagram of four groups of ceramic green sheets stacked in Example 3 of the present invention;

[0055] FIG8 is a cross-sectional view of a four-level multi-layer porous ceramic substrate according to a third embodiment of the present invention;

[0056] FIG9 is an exploded perspective view of a multi-layered porous ceramic atomizing core according to embodiments 4 and 5 of the present invention;

[0057] FIG10 is an inverted exploded view of the multi-layer porous ceramic atomizing core according to the fourth and fifth embodiments of the present invention. Best Mode for Carrying Out the Invention

[0058] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. In order to facilitate the description and better illustrate the present invention and its embodiments, the terms or descriptions indicating direction or positional relationship such as "upper", "lower", "upright", "inverted" in this document all refer to the direction or position of the device or component in the accompanying drawings, and are not used to limit the indicated device, component or component to have a specific orientation, or to be constructed and operated in a specific orientation. In the case of conversion of direction and position, the above-mentioned orientation terms will also change accordingly. In addition, the terms "first", "second"... etc. are mainly used to distinguish different devices, components or components, and are not used to indicate or imply the relative importance or absolute order and quantity of the indicated devices, components or components.

[0059] The present invention will be further described in detail below with reference to the embodiments:

[0060] The present invention provides a method for preparing a multi-layer porous ceramic substrate, comprising the following process flow:

[0061] (1) Preparation of ceramic powder:

[0062] Components of several groups of ceramic powders are weighed in parts by weight, wherein the components of any group of ceramic powders include: 25-55 parts of aggregate, 5-40 parts of pore-forming agent, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant, wherein the average particle size of the aggregate and / or pore-forming agent contained in each group of ceramic powders is different, that is, the average particle size of the aggregate and / or pore-forming agent contained in each group of ceramic powders is different from the average particle size of the aggregate and / or pore-forming agent contained in the remaining groups of ceramic powders.

[0063] 25 to 55 parts of aggregate, including but not limited to: any integer between 25 and 55 parts, and\or 25 to 30 parts, and\or 30 to 35 parts, and\or 35 to 40 parts, and\or 40 to 45 parts, and\or 45 to 50 parts, and\or 50 to 55 parts, and\or 35 to 55 parts;

[0064] The pore-forming agent is 5 to 40 parts, including but not limited to: any integer between 5 and 40 parts, and\or 5 to 10 parts, and\or 10 to 15 parts, and\or 15 to 20 parts, and\or 20 to 25 parts, and\or 25 to 30 parts, and\or 30 to 35 parts, and\or 35 to 40 parts;

[0065] The sintering aid is 5 to 19 parts, including but not limited to: any integer between 5 and 19 parts, and\or 5 to 10 parts, and\or 10 to 15 parts, and\or 15 to 19 parts;

[0066] wherein the powder dispersant is 5 to 35 parts, including but not limited to: any integer between 5 and 35 parts, and\or 5 to 10 parts, and\or 10 to 15 parts, and\or 15 to 20 parts, and\or 20 to 25 parts, and\or 25 to 30 parts, and\or 30 to 35 parts;

[0067] The aggregate is a material used to form a porous ceramic matrix skeleton after sintering, including at least one of kaolin, diatomaceous earth, alumina, silicon nitride, silicon carbide, quartz sand, glass sand, clay, feldspar powder, fused quartz, cordierite, and mullite;

[0068] The average particle size of the aggregate is 5 to 100 um, including but not limited to: any value between 5 and 100 um, and\or 5 to 10 um, and\or 10 to 20 um, and\or 20 to 30 um, and\or 30 to 40 um, and\or 40 to 50 um, and\or 50 to 60 um, and\or 60 to 70 um, and\or 70 to 80 um, and\or 80 to 90 um, and\or 90 to 100 um, and\or 5 to 50 um, and\or 10 to 30 um, and\or 50 to 100 um, and\or 55 to 85 um.

[0069] The pore-forming agent is a material that vaporizes and evaporates during sintering to form micropores in the porous ceramic matrix, including at least one of graphite, starch, wood flour, flour, soybean flour, polystyrene microspheres, polymethyl methacrylate microspheres, sucrose, and fiber;

[0070] The average particle size of the pore-forming agent is 5 to 100 um, including but not limited to any value between 5 and 100 um, and\or 5 to 10 um, and\or 10 to 20 um, and\or 20 to 30 um, and\or 30 to 40 um, and\or 40 to 50 um, and\or 50 to 60 um, and\or 60 to 70 um, and\or 70 to 80 um, and\or 80 to 90 um, and\or 90 to 100 um, and\or 5 to 50 um, and\or 50 to 100 um, and\or 15 to 80 um, and\or 25 to 60 um, and\or 55 to 95 um, and\or 65 to 85 um.

[0071] The sintering aid is used to bond the aggregate and help sinter at a suitable temperature to form a porous ceramic matrix, including at least one of boron oxide, sodium silicate, silicon oxide, potassium oxide, lithium oxide, barium oxide, magnesium oxide, calcium oxide, iron oxide, titanium oxide, zinc oxide, and zirconium oxide;

[0072] The powder dispersant is used to promote uniform dispersion of aggregates and prevent precipitation and accumulation, and includes at least one of paraffin wax, beeswax, boric acid, oleic acid, stearic acid, polyethylene, polypropylene, polyvinyl acetate, polyvinyl acetal, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, perchlorethylene resin, polyacrylate, and polyamide;

[0073] Several groups of the aggregate, pore former, sintering aid and powder dispersant are weighed and fully mixed in groups to obtain several groups of ceramic powders.

[0074] (2) Preparation of tape-cast ceramic slurry:

[0075] Weighing several groups of tape-cast ceramic slurry components by weight, wherein the components of each group of tape-cast ceramic slurry respectively include: 40-65 parts of ceramic powder from one of the several groups of ceramic powders, 30-50 parts of solvent, 0.1-3 parts of slurry dispersant, 1-8 parts of plasticizer, and 1-10 parts of binder;

[0076] The ceramic powder is 40 to 65 parts, including but not limited to: any integer between 40 and 65 parts, and\or 40 to 45 parts, and\or 45 to 50 parts, and\or 50 to 55 parts; and\or 55 to 60 parts, and\or 60 to 65 parts, and\or 45 to 55 parts.

[0077] The solvent is 30 to 50 parts, including but not limited to: any integer between 30 and 50 parts, and\or 31 to 35 parts, and\or 35 to 40 parts, and\or 40 to 45 parts, and\or 45 to 50 parts, and\or 35 to 45 parts;

[0078] The slurry dispersant is 0.1 to 3 parts, including but not limited to: 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1 part, 1.1 part...3 parts, and\or 0.1 to 1 part, and\or 1.1 to 2 parts, and\or 2.1 to 3 parts;

[0079] Wherein the plasticizer is 1 to 8 parts, including but not limited to: any integer between 1 to 8 parts, and\or 1 to 3 parts, and\or 3 to 5 parts, and\or 1 to 5 parts, and\or 5 to 8 parts;

[0080] The binder is 1 to 10 parts, including but not limited to: any integer between 1 and 10 parts, and\or 1 to 3 parts, and\or 3 to 5 parts, and\or 5 to 8 parts, and\or 8 to 10 parts, and\or 3 to 8 parts;

[0081] The solvent used to convert the ceramic powder into a fluid includes at least one of ethanol, isopropyl alcohol, acetone, butanone, xylene, trichloroethylene, ethyl acetate, and butyl acetate;

[0082] The slurry dispersant is used to disperse the ceramic powder in the solvent, and includes at least one of oleic acid, boric acid, linseed oil, castor oil, stearic acid, and triolein;

[0083] The plasticizer is used to improve the plasticity of the ceramic green body, and includes at least one of polyethylene glycol and dibutyl phthalate;

[0084] The binder is used to improve the strength of the ceramic green body and includes at least one of polymethyl acrylate, ethyl cellulose, polyethylene, polyvinyl butyral, and polyisobutylene;

[0085] The ceramic powder, dispersant and solvent of several groups are weighed and fully mixed and ball-milled respectively, and then the plasticizer and binder are added respectively and continue to be fully mixed and ball-milled to obtain several groups of tape-cast ceramic slurries.

[0086] (3) Preparation of ceramic green body:

[0087] Several groups of the above-mentioned tape-cast ceramic slurries are respectively made into several groups of thin-sheet ceramic green sheets by tape-casting process, and the several groups of ceramic green sheets are respectively cut into several pieces of ceramic green sheets.

[0088] The thickness of each ceramic green body made by the casting process is 0.1 to 0.6 mm, including but not limited to: any value between 0.1 and 0.6 mm, and\or 0.1 mm, and\or 0.2 mm, and\or 0.3 mm, and\or 0.4 mm, and\or 0.5 mm, and\or 0.6 mm, and\or 0.1 to 0.3 mm, and or 0.25 to 0.45 mm, and or 0.3 to 0.6 mm.

[0089] (4) Preparation of multi-layer porous ceramic matrix:

[0090] Several ceramic green sheets from different groups and / or different sheets from the same group are selected, stacked one above the other in order of the average particle size of the aggregate and / or pore-forming agent contained in each ceramic green sheet, and then pressed into a whole. The stacked sheets are then placed in a furnace for debinding and sintering. After sintering, the stacked sheets are removed and cut into desired shapes, thereby producing a multi-layered porous ceramic matrix having multiple ceramic sheets and vesicular micropores uniformly distributed therein. One of the ceramic green sheets forms a ceramic sheet after sintering, and the micropores in the multi-layered porous ceramic matrix have different or identical pore sizes depending on the ceramic sheet.

[0091] The multi-layer porous ceramic matrix of the present invention has spherical or nearly spherical bubble-shaped micropores formed therein. The distance between the micropores is relatively close, and some adjacent micropores are connected by tiny through holes. Therefore, the entire multi-layer porous ceramic matrix can be used as a liquid conductor to absorb liquid substances from one side and conduct them to the other side for seepage after adsorption, penetration, and flow through the micropores.

[0092] The average pore size of the micropores of each ceramic layer in the above-mentioned multi-layer porous ceramic matrix is ​​10 to 50 um, including but not limited to any value between 10 and 50 um, and\or 10 to 20 um, and\or 20 to 30 um, and\or 30 to 40 um, and\or 40 to 50 um, and\or 15 to 45 um, and\or 20 to 40 um.

[0093] The porosity of the micropores of each ceramic layer of the prepared multi-layer porous ceramic matrix is ​​40%-65%, including but not limited to any value between 40%-65%, and\or 40%-45%, and\or 45%-50%, and\or 50%-55%, and\or 55%-60%, and\or 60%-65%, and\or 45-60%, and\or 48-56%.

[0094] The thickness of each ceramic layer of the multi-layer porous ceramic matrix is ​​0.1 to 0.5 mm, including but not limited to any value between 0.1 and 0.5 mm, and\or 0.1 mm, and\or 0.2 mm, and\or 0.3 mm, and\or 0.4 mm, and\or 0.5 mm, and\or 0.1 to 0.25 mm, and or 0.2 to 0.4 mm, and or 0.25 to 0.5 mm.

[0095] The above-mentioned average pore diameter, porosity, and thickness structure of the ceramic layers provide the multi-layered porous ceramic substrate with good conductivity for conducting liquid substances under external forces such as suction, while also preventing excessive flow and maintaining a certain balance. In the absence of external forces such as suction, the micropores maintain a certain tension, allowing the liquid substances to be trapped and prevented from flowing naturally and leaking. The multi-layered porous ceramic substrate of the present invention can be used as a liquid conductor for conducting atomized liquids.

[0096] In addition, the above-mentioned method for preparing a multi-layer porous ceramic matrix, wherein when preparing a multi-layer porous ceramic matrix, several ceramic green sheets of different groups and / or different sheets of the same group are selected, and are stacked up and down in the order of the average particle size of the aggregate and / or pore-forming agent contained in each ceramic green sheet, and then pressed into one body. The order of arrangement according to the average particle size of the aggregate and / or pore-forming agent means stacking the ceramic green sheets according to a certain rule, that is, based on the average particle size of the aggregate and / or pore-forming agent in the ceramic green sheet, according to the rule of from large to small, or from small to large, or one large and one small, or two identical and then from large to small, or a rule of alternating size, so that the size of the micropores of each layer of ceramic sheet after production is also arranged according to the above rule.

[0097] When preparing a multi-layer porous ceramic matrix, several groups of ceramic green sheets and 1 to several ceramic green sheets in each group can be selected. For example, 2 to 10 groups of ceramic green sheets and 1 to 3 ceramic green sheets in each group can be selected. The groups of ceramic green sheets are stacked from bottom to top in order such that the average particle size of the aggregate and / or pore-forming agent contained in each group changes alternately or changes gradually from large to small, and then pressed into one body. After debinding and sintering, a multi-layer porous ceramic matrix having several levels of ceramic layers and 1 to several ceramic layers in each level is obtained. For example, a multi-layer porous ceramic matrix having 2 to 10 levels of ceramic layers and 1 to 3 ceramic layers in each level is obtained. The average pore size of the micropores in different layers of the same level is the same, the average pore size of the micropores in different levels of ceramic layers is different, and the average pore size of the micropores in each level of the ceramic layers changes alternately or changes gradually from large to small in the order from bottom to top.

[0098] For example, one ceramic green sheet from each group having different average particle size ranges of aggregate and / or pore-forming agent can be selected, and the green sheets can be stacked from bottom to top in descending order of the average particle size ranges of the aggregate and / or pore-forming agent to produce a multi-layered porous ceramic matrix, wherein the micropore diameters of the ceramic sheets within the multi-layered porous ceramic matrix have a gradient from large to small from bottom to top. Specifically, when preparing the multi-layered porous ceramic matrix, the number of ceramic green sheets, i.e., the number of sheets, can be 4 to 10, preferably 4 to 6, and the number of ceramic sheets in the porous ceramic matrix can be 4 to 10, preferably 4 to 6.

[0099] For another example, two ceramic green sheets having the same average particle size range for aggregate and / or pore-forming agent can be stacked together to form one group. Then, two ceramic green sheets having the same average particle size range for aggregate and / or pore-forming agent can be stacked together to form another group. Several groups of ceramic green sheets having different average particle size ranges can be prepared in this manner. The green sheets of each group can be stacked from bottom to top in descending order of the average particle size ranges for the aggregate and / or pore-forming agent, thereby producing a multi-level multi-layered porous ceramic matrix in which each two ceramic sheets form a level. The micropore diameters of each level within the multi-layered porous ceramic matrix have a gradient from large to small from bottom to top. When preparing the multi-layered porous ceramic matrix, the number of ceramic green sheets is selected to be 2 to 5 groups, preferably 3 or 4 groups. The number of levels of the porous ceramic matrix is ​​2 to 5, and the number of ceramic sheets is twice the number of levels, preferably 3 or 4, and the number of ceramic sheets is 6 or 8.

[0100] It should be noted that during the manufacture of the multi-layered porous ceramic substrate of the present invention, due to the stacking and pressing of the ceramic green sheets, the thickness of each layer of the ceramic green sheets will be slightly greater than the thickness of each layer of the ceramic sheets after sintering. The multi-layered porous ceramic substrate after sintering is actually a whole, and no obvious stratification can be seen from the appearance and cross-section, which is generally difficult to distinguish with the naked eye. The levels and layer-by-layer analysis of the ceramic sheets described in this article are only graded and layered according to the size of the micropores inside each level and each layer of the ceramic sheets.

[0101] The present invention provides a method for preparing a multi-layer porous ceramic atomization core. First, a multi-layer porous ceramic substrate is prepared according to the above-mentioned method for preparing a multi-layer porous ceramic substrate, and then a metal slurry is prepared. One of the upper and lower surfaces of the multi-layer porous ceramic substrate is selected as the atomization surface, and the other surface is used as the liquid guide surface. The metal slurry is printed on both ends of the atomization surface by screen printing and sintered to obtain an electrode layer. Finally, a metal heating layer is obtained on the atomization surface by a metal sputtering coating process or by screen printing another metal slurry and then sintering, thereby obtaining a multi-layer porous ceramic atomization core.

[0102] The preparation method of the above-mentioned multi-layer porous ceramic atomization core may preferably be as follows: among the upper and lower surfaces of the multi-layer porous ceramic substrate, one side with a smaller pore size of the micropores is selected as the atomization surface, and the other side is used as the liquid guide surface. A metal heating layer is obtained on the atomization surface by a metal sputtering coating process or by a screen printing metal slurry and then sintering process, thereby obtaining a multi-layer porous ceramic atomization core.

[0103] The multi-layered porous ceramic substrate and its atomizing core produced by the present invention differ from existing porous ceramics with a single pore structure. The present invention utilizes a tape casting process to prepare multiple groups of ceramic green sheets with continuously varying particle sizes. These green sheets are then stacked, pressed, and fired to produce a porous ceramic substrate with multiple layers of varying pore sizes. Specifically, a multi-layered porous ceramic substrate with a gradient pore size structure can be formed. The green sheets are formed using a multi-layer lamination process. Compared to a single-layer forming process, the pressing and sintering of the multi-layered ceramic green sheets creates microscopic interlayer interfaces. The pore size of these interlayer interfaces lies between the pore sizes of the two layers, providing a transitional and buffering effect for the transport of the atomized liquid, facilitating its storage and transmission. In addition, multi-layer ceramic sheets can be stacked to prepare porous ceramics with a gradient pore structure. When applied to the atomization core of an electronic cigarette, the ceramic pore structure can be gradiently adjusted according to the ceramic sheets based on different heating methods and different viscosities of the smoke liquid. The porosity and pore size from the liquid guide surface to the atomization surface are adjusted layer by layer, so that the liquid supply and atomization of the porous ceramic matrix are balanced, achieving the advantages of both fast liquid guide and fine atomization, and improving the atomization experience. Modes for Carrying Out the Invention

[0104] The present invention will be described in detail below with reference to the accompanying drawings.

[0105] Example 1:

[0106] A method for preparing a multi-layer porous ceramic substrate includes the following process steps:

[0107] (1) Preparation of ceramic powder:

[0108]

[0109] As shown in the table above, first, the components of the first group of ceramic powders are weighed by weight, including: 40-46 parts of aggregate, with an average particle size of 70-75 μm, 25-28 parts of pore former, with an average particle size of 40-50 μm, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant;

[0110] The components of the second group of ceramic powders are weighed in parts by weight: 45-50 parts of aggregate, the average particle size of the aggregate is 40-60 μm, 20-25 parts of pore former, the average particle size of the pore former is 40-50 μm, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant;

[0111] The components of the third group of ceramic powders are weighed in parts by weight: 40-48 parts of aggregate, the average particle size of the aggregate is 15-30 μm, 25-30 parts of pore former, the average particle size of the pore former is 35-40 μm, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant;

[0112] The components of the fourth group of ceramic powders weighed by weight include: 35 to 45 parts of aggregate with an average particle size of 10 to 20 μm, 25 to 30 parts of pore former with an average particle size of 35 to 40 μm, 5 to 19 parts of sintering aid, and 5 to 35 parts of powder dispersant.

[0113] The sintering aid is 5 to 19 parts, including any integer between 5 and 19 parts, and\or 5 to 10 parts, and\or 10 to 15 parts, and\or 15 to 19 parts;

[0114] wherein the powder dispersant is 5 to 35 parts, including any integer between 5 and 35 parts, and\or 5 to 10 parts, and\or 10 to 15 parts, and\or 15 to 20 parts, and\or 20 to 25 parts, and\or 25 to 30 parts, and\or 30 to 35 parts;

[0115] The aggregate is at least one of kaolin, diatomaceous earth, alumina, silicon nitride, silicon carbide, quartz sand, glass sand, clay, feldspar powder, fused quartz, cordierite, and mullite;

[0116] The pore-forming agent is at least one of graphite, starch, wood flour, flour, soybean flour, polystyrene microspheres, polymethyl methacrylate microspheres, sucrose, and fiber;

[0117] The sintering aid is at least one of boron oxide, sodium silicate, silicon oxide, potassium oxide, lithium oxide, barium oxide, magnesium oxide, calcium oxide, iron oxide, titanium oxide, zinc oxide, and zirconium oxide;

[0118] The powder dispersant is at least one of paraffin wax, beeswax, boric acid, oleic acid, stearic acid, polyethylene, polypropylene, polyvinyl acetate, polyvinyl acetal, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, perchlorethylene resin, polyacrylate, and polyamide;

[0119] The four groups of aggregates, pore formers, sintering aids and powder dispersants weighed above are fully mixed in groups to obtain four groups of ceramic powders including the first to fourth groups.

[0120] (2) Preparation of tape-cast ceramic slurry:

[0121] The components of four groups of tape-cast ceramic slurries are weighed separately by weight, wherein the components of each group of tape-cast ceramic slurries include: 40 to 65 parts of ceramic powder of one of the above four groups of ceramic powders, 30 to 50 parts of solvent, 0.5 to 3 parts of slurry dispersant, 1 to 8 parts of plasticizer, and 1 to 10 parts of binder.

[0122] The ceramic powder is 40 to 65 parts, including any integer between 40 and 65 parts, and\or 40 to 45 parts, and\or 45 to 50 parts, and\or 50 to 55 parts, and\or 55 to 60 parts, and\or 55 to 60 parts.

[0123] wherein the above-mentioned solvent is 30 to 50 parts, including any integer between 30 and 50 parts, and\or 30 to 35 parts, and\or 35 to 40 parts, and\or 40 to 45 parts, and\or 45 to 50 parts;

[0124] The above-mentioned slurry dispersant is 0.5 to 3 parts, including any value between 0.5 and 3, and\or 0.5 to 1 part, and\or 1 to 1.5 parts, and\or 1.5 to 2 parts, and\or 2 to 2.5 parts, and\or 2.5 to 3 parts;

[0125] The above-mentioned plasticizer is 1 to 8 parts, including any integer between 1 to 8 parts, and\or 1 to 3 parts, and\or 3 to 6 parts, and\or 6 to 8 parts, and\or 2 to 5 parts;

[0126] The above-mentioned binder is 1 to 10 parts, including any integer between 1 and 10 parts, and\or 1 to 3 parts, and\or 3 to 6 parts, and\or 6 to 9 parts, and\or 3 to 8 parts;

[0127] The solvent used to convert the ceramic powder into a fluid includes at least one of ethanol, isopropyl alcohol, acetone, butanone, xylene, trichloroethylene, ethyl acetate, and butyl acetate;

[0128] The slurry dispersant is used to disperse the ceramic powder in the solvent, and includes at least one of oleic acid, boric acid, linseed oil, castor oil, stearic acid, and triolein;

[0129] The plasticizer is used to improve the plasticity of the ceramic green body, and includes at least one of polyethylene glycol and dibutyl phthalate;

[0130] The binder is used to improve the strength of the ceramic green body and includes at least one of polymethyl acrylate, ethyl cellulose, polyethylene, polyvinyl butyral, and polyisobutylene;

[0131] The ceramic powders, dispersants and solvents of the above four groups were weighed and fully mixed and ball-milled respectively, and then plasticizers and binders were added respectively and continued to be fully mixed and ball-milled to obtain four groups of tape-cast ceramic slurries, including the tape-cast ceramic slurries of groups 1 to 4.

[0132] (3) Preparation of ceramic green body:

[0133] The tape-cast ceramic slurries of the first to fourth groups were each formed into four sets of thin ceramic green sheets 1 using a tape-casting process. The four sets of ceramic green sheets were then cut into a plurality of ceramic green sheets, such as a ceramic green sheet 1 shown in FIG1 . The thickness of each of the four sets of ceramic green sheets formed using the tape-casting process was 0.3 to 0.6 mm.

[0134] (4) Preparation of multi-layer porous ceramic matrix:

[0135] As shown in FIG2 , the tape-cast ceramic slurries of the first to fourth groups are used to prepare the first group of ceramic green embryos 11, the twelfth group of ceramic green embryos 12, the third group of ceramic green embryos 13, and the fourth group of ceramic green embryos 14, respectively. One piece of the ceramic green embryos from each of the above different groups is taken and stacked from bottom to top in the order of the first group of ceramic green embryos 11 to the fourth group of ceramic green embryos 14, and then pressed into a whole. The pieces are then sent into a furnace for debinding and sintering, and finally cut into the desired shape, thereby obtaining a multi-layered porous ceramic matrix 10 having four ceramic layers and uniformly distributed vesicular micropores.

[0136] As shown in FIG3 , the multi-layer porous ceramic substrate 10 includes, from bottom to top, a first ceramic layer 110 , a second ceramic layer 120 , a third ceramic layer 130 , and a fourth ceramic layer 140 .

[0137] The multi-layered porous ceramic substrate 10 produced by the above method has, from bottom to top, the following micropores: the first ceramic layer 110 of the multi-layered porous ceramic substrate has a pore size of 40 to 50 μm; the second ceramic layer 120 has a pore size of 30 to 40 μm; the third ceramic layer 130 has a pore size of 20 to 30 μm; and the fourth ceramic layer 140 has a pore size of 10 to 20 μm. In other words, the average pore size of the micropores within the first through third ceramic layers varies from large to small. In the figure, denser diagonal lines represent smaller pore sizes, while looser lines represent larger pore sizes. Each ceramic layer of the multi-layered porous ceramic substrate has a thickness of 0.25 to 0.5 mm. Example 2

[0138] Another method for preparing a multi-layer porous ceramic substrate includes the following process steps:

[0139] (1) Preparation of ceramic powder:

[0140]

[0141] As shown in the table above, first, the components of the first group of ceramic powders are weighed by weight, including: 40-46 parts of aggregate, with an average particle size of 60-75 μm, 25-30 parts of pore former, with an average particle size of 40-50 μm, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant;

[0142] The components of the second group of ceramic powders are weighed in parts by weight: 40-48 parts of aggregate, the average particle size of the aggregate is 15-50 μm, 25-30 parts of pore former, the average particle size of the pore former is 35-40 μm, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant;

[0143] The components of the third group of ceramic powders weighed by weight include: 35 to 45 parts of aggregate with an average particle size of 10 to 20 μm, 25 to 30 parts of pore former with an average particle size of 35 to 40 μm, 5 to 19 parts of sintering aid, and 5 to 35 parts of powder dispersant.

[0144] The above-mentioned sintering aid 5-19 parts includes any integer between 5-19 parts, and\or 5-10 parts, and\or 10-15 parts, and\or 15-19 parts;

[0145] wherein the above-mentioned powder dispersant 5 to 35 parts includes any integer between 5 and 35 parts, and\or 5 to 10 parts, and\or 10 to 15 parts, and\or 15 to 20 parts, and\or 20 to 25 parts, and\or 25 to 30 parts, and\or 30 to 35 parts;

[0146] The aggregate is a material used to form a porous ceramic matrix skeleton after sintering, including at least one of kaolin, diatomaceous earth, alumina, silicon nitride, silicon carbide, quartz sand, glass sand, clay, feldspar powder, fused quartz, cordierite, and mullite;

[0147] The pore-forming agent is at least one of graphite, starch, wood flour, flour, soybean flour, polystyrene microspheres, polymethyl methacrylate microspheres, sucrose, and fiber;

[0148] The sintering aid is at least one of boron oxide, sodium silicate, silicon oxide, potassium oxide, lithium oxide, barium oxide, magnesium oxide, calcium oxide, iron oxide, titanium oxide, zinc oxide, and zirconium oxide;

[0149] The powder dispersant is at least one of paraffin wax, beeswax, boric acid, oleic acid, stearic acid, polyethylene, polypropylene, polyvinyl acetate, polyvinyl acetal, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, perchlorethylene resin, polyacrylate, and polyamide;

[0150] The three groups of aggregates and pore formers are fully mixed with sintering aids and powder dispersants respectively to obtain three groups of ceramic powders, namely, the ceramic powders of groups 1 to 3.

[0151] (2) Preparation of tape-cast ceramic slurry:

[0152] The following three groups of tape-cast ceramic slurries are weighed respectively by weight, wherein the components of each group of tape-cast ceramic slurries include: 40 to 65 parts of ceramic powder from one of the four groups of ceramic powders, 30 to 50 parts of solvent, 0.5 to 3 parts of slurry dispersant, 1 to 8 parts of plasticizer, and 1 to 10 parts of binder.

[0153] wherein the above-mentioned solvent is 30 to 50 parts, including any integer between 30 and 50 parts, and\or 30 to 35 parts, and\or 35 to 40 parts, and\or 40 to 45 parts, and\or 45 to 50 parts;

[0154] The above-mentioned slurry dispersant is 0.5 to 3 parts, including any value between 0.5 and 3, and\or 0.5 to 1 part, and\or 1 to 1.5 parts, and\or 1.5 to 2 parts, and\or 2 to 2.5 parts, and\or 2.5 to 3 parts;

[0155] The above-mentioned plasticizer is 1 to 8 parts, including any integer between 1 to 8 parts, and\or 1 to 3 parts, and\or 3 to 6 parts, and\or 6 to 8 parts, and\or 2 to 5 parts;

[0156] The above-mentioned binder is 1 to 10 parts, including any integer between 1 and 10 parts, and\or 1 to 3 parts, and\or 3 to 6 parts, and\or 6 to 9 parts, and\or 3 to 8 parts;

[0157] The solvent used to convert the ceramic powder into a fluid includes at least one of ethanol, isopropyl alcohol, acetone, butanone, xylene, trichloroethylene, ethyl acetate, and butyl acetate;

[0158] The slurry dispersant is used to disperse the ceramic powder in the solvent, and includes at least one of oleic acid, boric acid, linseed oil, castor oil, stearic acid, and triolein;

[0159] The plasticizer is used to improve the plasticity of the ceramic green body, and includes at least one of polyethylene glycol and dibutyl phthalate;

[0160] The binder is used to improve the strength of the ceramic green body, and includes at least one of polymethyl acrylate, ethyl cellulose, polyethylene, polyvinyl butyral, and polyisobutylene;

[0161] The three groups of ceramic powders, dispersants and solvents were weighed and fully mixed and ball-milled respectively, and then plasticizers and binders were added respectively and continued to be fully mixed and ball-milled to obtain three groups of tape-cast ceramic slurries, namely, the tape-cast ceramic slurries of Groups 1 to 3.

[0162] (3) Preparation of ceramic green body:

[0163] The tape-cast ceramic slurries of the first to third groups are respectively made into three groups of thin-sheet ceramic green sheets by tape-casting process, and the three groups of ceramic green sheets are respectively cut into several pieces of ceramic green sheets, as shown in FIG1 , which is a piece of ceramic green sheet 1.

[0164] The thickness of each ceramic green body of the three groups manufactured by the tape casting process is 0.25-0.45 mm.

[0165] (4) Preparation of multi-layer porous ceramic matrix:

[0166] As shown in Figures 4-6, two ceramic green sheets are taken from each of the three different groups of the above-mentioned ceramic green sheets. The two ceramic green sheets 2 of the same group are first stacked together to form one group. Then, two ceramic green sheets of another different group are selected and stacked together to form another group. In the order of the above-mentioned ceramic powder groups 1 to 3, a first group of ceramic green sheets 21, a second group of ceramic green sheets 22, and a third group of ceramic green sheets 23 are formed. Then, in the order of the first group to the third group and from bottom to top, the ceramic green sheets of each group are stacked and pressed into a whole. Then, they are sent into a furnace for debinding and sintering, and finally cut into the desired shape, thus obtaining a multi-layered porous ceramic matrix 20 having three levels and six layers of ceramic sheets and uniformly distributed vesicular micropores. As shown in Figure 8, the multi-layered porous ceramic matrix 20 includes, from bottom to top, a first-level ceramic sheet 210, a second-level ceramic sheet 220, and a third-level ceramic sheet 230, each level including two identical ceramic sheets.

[0167] The multi-layered porous ceramic substrate 20 produced by the above method has, from bottom to top, micropores in the first stage 210 of the multi-layered porous ceramic substrate having a pore size of 35 to 50 μm, micropores in the second stage 220 having a pore size of 20 to 35 μm, and micropores in the third stage 230 having a pore size of 10 to 20 μm. In other words, the average pore size of the micropores within the first through third ceramic layers exhibits a gradient from large to small. In the figure, densely shaded stages or ceramic layers represent smaller pore sizes, while looser shaded stages represent larger pore sizes.

[0168] The thickness of each ceramic layer of the multi-layer porous ceramic matrix is ​​0.2-0.4 mm.

[0169] Example 3:

[0170] Another method for preparing a multi-layer porous ceramic substrate includes the following process steps:

[0171] (1) Preparation of ceramic powder:

[0172]

[0173] As shown in the table above, first, the components of the first group of ceramic powders are weighed by weight, including: 40-46 parts of aggregate, with an average particle size of 70-75 μm, 25-28 parts of pore former, with an average particle size of 40-50 μm, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant;

[0174] The components of the second group of ceramic powders are weighed in parts by weight: 45-50 parts of aggregate, the average particle size of the aggregate is 40-60 μm, 20-25 parts of pore former, the average particle size of the pore former is 40-50 μm, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant;

[0175] The components of the third group of ceramic powders are weighed in parts by weight: 40-48 parts of aggregate, the average particle size of the aggregate is 15-30 μm, 25-30 parts of pore former, the average particle size of the pore former is 35-40 μm, 5-19 parts of sintering aid, and 5-35 parts of powder dispersant;

[0176] The components of the fourth group of ceramic powders weighed by weight include: 35 to 45 parts of aggregate with an average particle size of 10 to 20 μm, 25 to 30 parts of pore former with an average particle size of 35 to 40 μm, 5 to 19 parts of sintering aid, and 5 to 35 parts of powder dispersant.

[0177] The above-mentioned sintering aid 5-19 parts includes any integer between 5-19 parts, and\or 5-10 parts, and\or 10-15 parts, and\or 15-19 parts;

[0178] The above-mentioned powder dispersant 5 to 35 parts includes any integer between 5 and 35 parts, and\or 5 to 10 parts, and\or 10 to 15 parts, and\or 15 to 20 parts, and\or 20 to 25 parts, and\or 25 to 30 parts, and\or 30 to 35 parts.

[0179] The aggregate is a material used to form a porous ceramic matrix skeleton after sintering, including at least one of kaolin, diatomaceous earth, alumina, silicon nitride, silicon carbide, quartz sand, glass sand, clay, feldspar powder, fused quartz, cordierite, and mullite;

[0180] The pore-forming agent is at least one of graphite, starch, wood flour, flour, soybean flour, polystyrene microspheres, polymethyl methacrylate microspheres, sucrose, and fiber;

[0181] The sintering aid is at least one of boron oxide, sodium silicate, silicon oxide, potassium oxide, lithium oxide, barium oxide, magnesium oxide, calcium oxide, iron oxide, titanium oxide, zinc oxide, and zirconium oxide;

[0182] The powder dispersant is at least one of paraffin wax, beeswax, boric acid, oleic acid, stearic acid, polyethylene, polypropylene, polyvinyl acetate, polyvinyl acetal, ethylene-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate copolymer resin, perchlorethylene resin, polyacrylate, and polyamide;

[0183] The four groups of aggregates, pore formers, sintering aids and powder dispersants weighed are fully mixed in groups to obtain four groups of ceramic powders, including the ceramic powders of the first to fourth groups mentioned above.

[0184] (2) Preparation of tape-cast ceramic slurry:

[0185] The components of 4 groups of tape-cast ceramic slurries were weighed respectively by weight, wherein the components of each group of tape-cast ceramic slurries include: 40 to 65 parts of ceramic powder of one of the above-mentioned groups 1 to 4, 30 to 50 parts of solvent, 0.1 to 3 parts of slurry dispersant, 1 to 8 parts of plasticizer, and 1 to 10 parts of binder.

[0186] wherein the above-mentioned solvent is 30 to 50 parts, including any integer between 30 and 50 parts, and\or 30 to 35 parts, and\or 35 to 40 parts, and\or 40 to 45 parts, and\or 45 to 50 parts;

[0187] The above-mentioned slurry dispersant is 0.5 to 3 parts, including any value between 0.5 and 3, and\or 0.5 to 1 part, and\or 1 to 1.5 parts, and\or 1.5 to 2 parts, and\or 2 to 2.5 parts, and\or 2.5 to 3 parts;

[0188] The above-mentioned plasticizer is 1 to 8 parts, including any integer between 1 to 8 parts, and\or 1 to 3 parts, and\or 3 to 6 parts, and\or 6 to 8 parts, and\or 2 to 5 parts;

[0189] The above-mentioned binder is 1 to 10 parts, including any integer between 1 and 10 parts, and\or 1 to 3 parts, and\or 3 to 6 parts, and\or 6 to 9 parts, and\or 3 to 8 parts;

[0190] The solvent used to convert the ceramic powder into a fluid includes at least one of ethanol, isopropyl alcohol, acetone, butanone, xylene, trichloroethylene, ethyl acetate, and butyl acetate;

[0191] The slurry dispersant is used to disperse the ceramic powder in the solvent, and includes at least one of oleic acid, boric acid, linseed oil, castor oil, stearic acid, and triolein;

[0192] The plasticizer is used to improve the plasticity of the ceramic green body, and includes at least one of polyethylene glycol and dibutyl phthalate;

[0193] The binder is used to improve the strength of the ceramic green body, and includes at least one of polymethyl acrylate, ethyl cellulose, polyethylene, polyvinyl butyral, and polyisobutylene;

[0194] The 4 groups of weighed ceramic powders, dispersants and solvents were fully mixed and ball-milled respectively, and then plasticizers and binders were added respectively and continued to be fully mixed and ball-milled to obtain 4 groups of tape-cast ceramic slurries, namely, the tape-cast ceramic slurries of groups 1 to 4.

[0195] (3) Preparation of ceramic green body:

[0196] The tape-cast ceramic slurries of the first to fourth groups are respectively made into four groups of thin-sheet ceramic green sheets by tape-casting process, and the four groups of ceramic green sheets are respectively cut into several pieces of ceramic green sheets, as shown in FIG. 1 , which is a piece of ceramic green sheet 1.

[0197] The thickness of each ceramic green body made by the tape casting process is 0.1 to 0.3 mm.

[0198] (4) Preparation of multi-layer porous ceramic matrix:

[0199] As shown in Figures 4, 7, and 8, two ceramic green sheets are taken from each of the four different groups, and the two ceramic green sheets 2 from the same group are first stacked together to form a group. In the order of the ceramic powder groups 1 to 4, a first group of ceramic green sheets 31, a second group of ceramic green sheets 32, a third group of ceramic green sheets 33, and a fourth group of ceramic green sheets 34 are formed. Then, in the order of the first group to the fourth group and from bottom to top, the ceramic green sheets of each group are stacked and pressed into a whole. Then, they are sent into a furnace for debinding and sintering, and finally cut into the desired shape, thus obtaining a multi-layered porous ceramic matrix 30 having 4 levels and 8 layers of ceramic sheets and uniformly distributed vesicular micropores. As shown in Figure 8, the multi-layered porous ceramic matrix 30 includes, from bottom to top, a first level ceramic sheet 310, a second level ceramic sheet 320, a third level ceramic sheet 330, and a fourth level ceramic sheet 340, each level including two identical ceramic sheets.

[0200] The multi-layered porous ceramic substrate 30 produced by the above method has, from bottom to top, micropores in the first stage 310 of the multi-layered porous ceramic substrate having a pore size of 40-50 μm, micropores in the second stage 320 having a pore size of 30-40 μm, micropores in the third stage 330 having a pore size of 20-30 μm, and micropores in the fourth stage 340 having a pore size of 10-20 μm. In other words, the average pore size of the micropores in the ceramic layers of the first to fourth stages varies from large to small. In the figure, densely shaded stages or ceramic layers represent smaller pore sizes, while looser shaded stages represent larger pore sizes.

[0201] The thickness of each ceramic layer of the multi-layer porous ceramic matrix is ​​0.1 to 0.25 mm.

[0202] Example 4:

[0203] As shown in Figures 9 and 10, a method for preparing a multi-layer porous ceramic atomization core of the present invention is as follows: first, a multi-layer porous ceramic substrate 40 is prepared on the basis of the above embodiment, and then a metal slurry is prepared. One of the upper and lower surfaces of the multi-layer porous ceramic substrate is selected as the atomization surface 41, and the other surface is used as the liquid guide surface 42. The metal slurry is printed on both ends of the atomization surface by screen printing and sintered to obtain an electrode layer 43. Finally, a metal heating layer 44 is obtained on the atomization surface by a metal sputtering coating process or by screen printing another metal slurry and then sintering. The metal heating layer 44 covers the electrode layer 43 so that the two can be electrically connected, thereby preparing a multi-layer porous ceramic atomization core. Both the upper and lower surfaces of the multi-layer porous ceramic matrix can be used as liquid guiding surfaces for introducing liquid substances, and the other surface is used as an atomizing surface for seeping out liquid substances. The metal heating layer 44 also has micropores or large through holes, so that the liquid substance seeping out of the atomizing surface 41 can continue to seep out through the metal heating layer, or provide gaseous substances for volatilization into the air. When the metal heating layer 44 is energized, it can heat, evaporate or atomize the liquid substance seeping out of the atomizing surface 41 to form an aerosol or aerosol, smoke. The electrode layer 43 is used to connect the two poles of the power supply to provide electrical energy for the metal heating layer 44.

[0204] The multi-layered porous ceramic atomizing core produced by the present invention has a multi-layered porous ceramic matrix 40 that serves as a liquid conductor. Each layer of the ceramic layers has uniformly distributed bubble-shaped micropores. The average pore size of the micropores in the same level of ceramic layers is the same, while the average pore size of the micropores in different levels of ceramic layers is different. The average pore size of the micropores in each level of ceramic layers, in order from bottom to top, has a pattern of alternating size changes or a gradient change from large to small. The micropores are spherical or nearly spherical bubble-shaped micropores. The distance between the micropores is relatively close, and some adjacent micropores are connected by tiny through-holes. Therefore, the entire multi-layered porous ceramic matrix can serve as a liquid conductor, used to absorb liquid substances from one side and conduct them to the other side after adsorption, penetration, and flow through the micropores. The liquid-conducting structure of the multi-layered porous ceramic atomizer core of the present invention has the aforementioned micropore diameter and ceramic layer thickness structure, which ensures that the multi-layered porous ceramic matrix has good conductivity for conducting liquid substances under external forces such as suction, while preventing excessive flow and maintaining a certain balance. In the absence of external forces such as suction, the micropores have a certain tension, which allows for rapid absorption of liquid substances without causing natural flow and leakage. The multi-layered porous ceramic atomizer core of the present invention can be used in electronic cigarette atomizers to heat, evaporate, and atomize atomized liquid or electronic cigarette liquid within the electronic cigarette liquid storage chamber.

[0205] The present invention uses a tape casting process to prepare multiple groups of ceramic green sheets with continuously different particle size structures, and the multiple ceramic green sheets are stacked and pressed and fired to obtain a porous ceramic matrix with multiple layers of different pore sizes, especially a multi-layer porous ceramic matrix with a gradient pore size structure. The ceramic green sheet is formed by a multi-layer stacking method. Compared with the one-time molding process, after the multi-layer ceramic green sheet is pressed and sintered, an interlayer interface is generated at the microscopic level. The micropore size of the interlayer interface is between the micropore size of the two layers, which has a certain transition and buffering effect on the transmission of the atomized liquid, which is beneficial to the storage and transmission of the atomized liquid. In addition, the multi-layer ceramic sheet can be stacked to prepare a porous ceramic with a gradient pore size structure. When applied to the atomizer core of an electronic cigarette, the ceramic pore size structure can be gradiently adjusted according to the ceramic sheet according to different heating modes and different viscosities of the smoke liquid. The porosity and pore size are adjusted layer by layer from the liquid guide surface to the atomization surface, so that the liquid supply and atomization of the porous ceramic matrix are balanced, achieving the advantages of both fast liquid guide and fine atomization, and improving the atomization experience.

[0206] Figure 9 of the accompanying drawings in this specification shows an upright, exploded perspective view of the multi-layered porous ceramic atomizer core of this embodiment, and Figure 10 shows an inverted, exploded perspective view of the multi-layered porous ceramic atomizer core of this embodiment. In actual use, the multi-layered porous ceramic atomizer core of the present invention is generally installed in the position shown in Figure 10 so that the atomized liquid can flow from top to bottom by gravity and be conducted to the metal heating layer. The position shown in Figure 9 is for the convenience of showing the electrode layer and metal heating layer in the exploded structure.

[0207] Example 5:

[0208] As shown in Figures 9 and 10, another method for preparing a multi-layer porous ceramic atomization core of the present invention is as follows: first, a multi-layer porous ceramic substrate 40 is prepared on the basis of the above embodiment, and then a metal slurry is prepared. The side with the smaller pore size of the micropores on the upper and lower surfaces of the multi-layer porous ceramic substrate is selected as the atomization surface 41, and the other side is used as the liquid guide surface 42. The metal slurry is printed on both ends of the atomization surface by screen printing and sintered to obtain an electrode layer 43. A metal heating layer 44 is obtained on the atomization surface by a metal sputtering coating process or by a process of screen printing the metal slurry and then sintering, thereby obtaining a multi-layer porous ceramic atomization core. In this embodiment, the side with a smaller pore size of the micropores is selected as the atomizing surface 41, and the other side is set as the liquid guiding surface 42, so that the atomized liquid is more easily absorbed by the liquid guiding surface. When it reaches the atomizing surface, due to the smaller micropore size, the seepage rate of the atomized liquid can be controlled, so that the liquid supply and atomization speeds are matched to better achieve a dynamic balance, thereby achieving the advantages of both fast liquid guiding and fine atomization, and improving the atomization experience of electronic cigarette atomizer users. Industrial Applicability

[0209] The above descriptions are merely preferred embodiments of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention shall fall within the scope of the claims of the present invention.

Claims

1. A preparation method of a multi-layer porous ceramic matrix, characterized in that, It includes the following technological processes: (1) Preparing ceramic powder: Weigh several groups of components of ceramic powder by weight. The components of any one group of ceramic powder include: 25 - 55 parts of aggregate, 5 - 40 parts of pore former, 5 - 19 parts of sintering aid, and 5 - 35 parts of powder dispersant. The average particle sizes of the aggregate and / or pore former in each group of ceramic powder are different; The aggregate is a material used to form the porous ceramic matrix skeleton after sintering, including at least one of kaolin, diatomite, alumina, silicon nitride, silicon carbide, quartz sand, glass sand, clay, feldspar powder, fused quartz, cordierite, and mullite; The pore former is a material used to vaporize and evaporate during sintering and form micropores in the porous ceramic matrix, including at least one of graphite, starch, wood powder, flour, bean powder, polystyrene microspheres, polymethyl methacrylate microspheres, sucrose, and fiber; The sintering aid is a material used to bond the aggregate and help sinter into a porous ceramic matrix at an appropriate temperature, including at least one of boron oxide, sodium silicate, silicon oxide, potassium oxide, lithium oxide, barium oxide, magnesium oxide, calcium oxide, iron oxide, titanium oxide, zinc oxide, and zirconium oxide; The powder dispersant is a material used to promote the uniform dispersion of the aggregate and prevent precipitation and accumulation, including at least one of paraffin wax, beeswax, boric acid, oleic acid, stearic acid, polyethylene, polypropylene, polyvinyl acetate, polyvinyl acetal, ethylene - vinyl acetate copolymer resin, vinyl chloride - vinyl acetate copolymer resin, perchloroethylene resin, polyacrylate, and polyamide; Mix the weighed aggregates, pore formers, sintering aids, and powder dispersants of several groups fully by group to obtain several groups of ceramic powder; (2) Preparing tape - casting ceramic slurry: Weigh several groups of components of tape - casting ceramic slurry by weight. The components of each group of tape - casting ceramic slurry respectively include: 40 - 65 parts of the ceramic powder of one group among the several groups of ceramic powder, 30 - 50 parts of solvent, 0.1 - 3 parts of slurry dispersant, 1 - 8 parts of plasticizer, and 1 - 10 parts of binder; The solvent is a material used to convert the ceramic powder into a fluid, including at least one of ethanol, isopropanol, acetone, butanone, xylene, trichloroethylene, ethyl acetate, and butyl acetate; The slurry dispersant is a material used to disperse the ceramic powder in the solvent, including at least one of oleic acid, boric acid, linseed oil, castor oil, stearic acid, and glyceryl trioleate; The plasticizer is a material used to improve the plasticity of the green ceramic body, including at least one of polyethylene glycol and dibutyl phthalate; The binder is a material used to improve the strength of the green ceramic body, including at least one of polymethyl acrylate, ethyl cellulose, polyethylene, polyvinyl butyral, and polyisobutene; Mix the weighed ceramic powder, dispersant, and solvent of several groups fully by group and ball - mill them, then add the plasticizer and binder respectively and continue to mix and ball - mill evenly to obtain several groups of tape - casting ceramic slurry; (3) Preparing green ceramic body: The several groups of tape-cast ceramic slurries are respectively made into several groups of thin ceramic green bodies by tape-casting process, and the several groups of ceramic green bodies are respectively cut into several pieces of ceramic green bodies; (4) Prepare a multi-layer porous ceramic matrix: Select several pieces of the ceramic green bodies from different groups and / or different pieces of the same group, stack them layer by layer from bottom to top in the order of the average particle size of the aggregate and / or pore former contained in each piece of ceramic green body, press them into one body, then send them into a furnace for debinding and sintering. After sintering, take them out and cut them into the required shape, thus obtaining a multi-layer porous ceramic matrix with several layers of ceramic sheets and bubble-like micropores evenly distributed inside. One of the ceramic green bodies forms one layer of the ceramic sheet after sintering.

2. The preparation method of the multi-layer porous ceramic matrix according to claim 1, characterized in that, When preparing the multi-layer porous ceramic matrix, select several groups of ceramic green bodies and 1 to several pieces of ceramic green bodies in each group, stack the groups of ceramic green bodies layer by layer from bottom to top in the order of the average particle size of the aggregate and / or pore former contained in each group of ceramic green bodies changing alternately or changing in a gradient from large to small, so as to obtain the multi-layer porous ceramic matrix with several levels of ceramic sheets and each level having 1 to several layers of ceramic sheets after debinding and sintering. The average pore diameter of the micropores in the ceramic sheets of the same level and different layers is the same, and the average pore diameter of the micropores in the ceramic sheets of different levels is different. In the order from bottom to top of the several levels of ceramic sheets, the average pore diameter of the micropores in each level of ceramic sheets has a law of changing alternately or changing in a gradient from large to small.

3. The preparation method of the multi-layer porous ceramic matrix according to claim 1, characterized in that, When preparing each group of the ceramic powder, the components of the ceramic powder are weighed by parts by weight and include: 35 - 55 parts of the aggregate, 25 - 30 parts of the pore former, 15 - 19 parts of the sintering aid, and 5 - 10 parts of the powder dispersant.

4. The preparation method of the multi-layer porous ceramic matrix according to claim 1, characterized in that, When preparing each group of the tape-cast ceramic slurry, the components of the tape-cast ceramic slurry are weighed by parts by weight and include: 45 - 55 parts of the ceramic powder of one of the several groups of ceramic powders, 35 - 45 parts of the solvent, 0.1 - 1 part of the slurry dispersant, 1 - 5 parts of the plasticizer, and 3 - 8 parts of the binder.

5. The preparation method of the multi-layer porous ceramic matrix according to claim 1, wherein, The average particle size of the aggregate is 5 - 100 um, or 5 - 50 um, or 10 - 30 um.

6. The preparation method of the multi-layer porous ceramic matrix according to claim 1, characterized in that The average particle size of the pore former is 5 - 100 um, or 15 - 80 um, or 25 - 60 um.

7. The preparation method of the multi-layer porous ceramic matrix according to claim 1, characterized in that, When preparing the ceramic green body, the thickness of each piece of the ceramic green body made by tape-casting process is 0.1 - 0.6 mm, or 0.1 - 0.3 mm, or 0.25 - 0.45 mm, or 0.3 - 0.6 mm.

8. The preparation method of the multi-layer porous ceramic matrix according to claim 1, characterized in that The average pore diameter of the micropores in each layer of the ceramic sheet of the obtained multi-layer porous ceramic matrix is 10 - 50 um, or 15 - 45 um, or 20 - 40 um.

9. The preparation method of the multi-layer porous ceramic matrix according to claim 1, characterized in that, The porosity of the micropores in each layer of the ceramic sheet of the obtained multi-layer porous ceramic matrix is 40% - 65%, or 45 - 60%, or 48 - 56%.

10. The preparation method of the multi-layer porous ceramic matrix according to claim 1, characterized in that, The thickness of each layer of the ceramic sheet of the obtained multi-layer porous ceramic matrix is 0.1 - 0.5 mm, or 0.1 - 0.25 mm, or 0.2 - 0.4 mm, or 0.25 - 0.5 mm.

11. The preparation method of the multi-layer porous ceramic matrix according to claim 2, characterized in that, When preparing the multi-layered porous ceramic matrix, several groups of green ceramic bodies and one green ceramic body in each group are selected. The green ceramic bodies of each group are stacked from bottom to top in sequence and pressed into one body in the order of gradually decreasing average particle size of the aggregate and / or pore-forming agent contained in the green ceramic bodies of each group, so as to obtain the multi-layered porous ceramic matrix with several levels of ceramic sheets and one layer of ceramic sheet in each level after debinding and sintering.

12. The preparation method of the multi-layer porous ceramic matrix according to claim 11, characterized in that, When preparing the multi-layered porous ceramic matrix, 4 to 10 groups of the green ceramic bodies are selected, and the number of levels of the ceramic sheets of the obtained porous ceramic matrix is 4 to 10 levels, and the number of layers is 4 to 10 layers.

13. The preparation method of the multi-layer porous ceramic matrix according to claim 11, characterized in that, When preparing the multi-layered porous ceramic matrix, 4 to 6 groups of the green ceramic bodies are selected, and the number of levels of the ceramic sheets of the obtained porous ceramic matrix is 4 to 6 levels, and the number of layers is 4 to 6 layers.

14. The preparation method of the multi-layer porous ceramic matrix according to claim 11, characterized in that, When preparing the multi-layered porous ceramic matrix, 4 groups, namely 4 pieces of the green ceramic bodies, are selected. Among them, in the order of stacking from bottom to top, the weight fraction of the aggregate in the first green ceramic body is 40 to 46 parts, the average particle size of the aggregate is 70 to 75 μm, the weight fraction of the pore-forming agent is 25 to 28 parts, and the average particle size of the pore-forming agent is 40 to 50 μm; the weight fraction of the aggregate in the second green ceramic body is 45 to 50 parts, the average particle size of the aggregate is 40 to 60 μm, the weight fraction of the pore-forming agent is 20 to 25 parts, and the average particle size of the pore-forming agent is 40 to 50 μm; the weight fraction of the aggregate in the third green ceramic body is 40 to 48 parts, the average particle size of the aggregate is 15 to 30 μm, the weight fraction of the pore-forming agent is 25 to 30 parts, and the average particle size of the pore-forming agent is 35 to 40 μm; the weight fraction of the aggregate in the fourth green ceramic body is 35 to 45 parts, the average particle size of the aggregate is 10 to 20 μm, the weight fraction of the pore-forming agent is 25 to 30 parts, and the average particle size of the pore-forming agent is 35 to 40 μm.

15. The preparation method of the multi-layer porous ceramic matrix according to claim 11, characterized in that, When preparing the multi-layered porous ceramic matrix, 4 groups, namely 4 pieces of the green ceramic bodies, are selected, and the number of layers of the ceramic sheets of the obtained porous ceramic matrix is 4 layers. Among them, in the order of stacking from bottom to top, the pore diameter of the micropores in the first layer of ceramic sheet is 40 to 50 μm, the pore diameter of the micropores in the second layer of ceramic sheet is 30 to 40 μm, the pore diameter of the micropores in the third layer of ceramic sheet is 20 to 30 μm, and the pore diameter of the micropores in the fourth layer of ceramic sheet is 10 to 20 μm.

16. The preparation method of the multi-layer porous ceramic matrix according to claim 2, characterized in that, When preparing the multi-layered porous ceramic matrix, several groups of green ceramic bodies and two green ceramic bodies in each group are selected. The green ceramic bodies of each group are stacked from bottom to top in sequence and pressed into one body in the order of gradually decreasing average particle size of the aggregate and / or pore-forming agent contained in the green ceramic bodies of each group, so as to obtain the multi-layered porous ceramic matrix with several levels of ceramic sheets and two layers of ceramic sheet in each level after debinding and sintering.

17. The preparation method of the multi-layer porous ceramic matrix according to claim 16, characterized in that, When preparing the multi-layered porous ceramic matrix, the number of groups of the green ceramic bodies selected is 2 to 5 groups, and the number of levels of the obtained multi-layered porous ceramic matrix is 2 to 5 levels, and the number of layers of the ceramic sheets is twice the number of levels.

18. The preparation method of the multi-layer porous ceramic matrix according to claim 16, characterized in that, When preparing the multi-layered porous ceramic substrate, the number of groups of the green ceramic blanks is selected to be 3 or 4 groups, the number of levels of the obtained porous ceramic substrate is 3 or 4 levels, and the number of layers of the ceramic sheets is 6 or 8 layers.

19. The preparation method of the multi-layer porous ceramic matrix according to claim 16, characterized in that, When preparing the multi-layered porous ceramic substrate, the number of groups of the green ceramic blanks is selected to be 3 groups. Among them, in the order of stacking from bottom to top, the weight fraction of the aggregate in the first group of green ceramic blanks is 40 - 46 parts, the average particle size of the aggregate is 60 - 75 μm, the weight fraction of the pore-forming agent is 25 - 30 parts, and the average particle size of the pore-forming agent is 40 - 50 μm; the weight fraction of the aggregate in the second group of green ceramic blanks is 40 - 48 parts, the average particle size of the aggregate is 15 - 50 μm, the weight fraction of the pore-forming agent is 25 - 30 parts, and the average particle size of the pore-forming agent is 35 - 40 μm; the weight fraction of the aggregate in the third group of green ceramic blanks is 35 - 45 parts, the average particle size of the aggregate is 10 - 20 μm, the weight fraction of the pore-forming agent is 25 - 30 parts, and the average particle size of the pore-forming agent is 35 - 40 μm.

20. The preparation method of the multi-layer porous ceramic matrix according to claim 16, wherein, When preparing the multi-layered porous ceramic substrate, the number of groups of the green ceramic blanks is selected to be 3 groups, the number of levels of the ceramic sheets of the obtained porous ceramic substrate is 3 levels, and the number of layers of the ceramic sheets is 6 layers. Among them, in the order of stacking from bottom to top, the pore diameter of the micropores in the first-level ceramic sheet is 35 - 50 μm, the pore diameter of the micropores in the second-level ceramic sheet is 20 - 35 μm, and the pore diameter of the micropores in the third-level ceramic sheet is 10 - 20 μm.

21. The preparation method of the multi-layer porous ceramic matrix according to claim 16, characterized in that, When preparing the multi-layered porous ceramic substrate, the number of groups of the green ceramic blanks is selected to be 4 groups. Among them, in the order of stacking from bottom to top, the weight fraction of the aggregate in the first group of green ceramic blanks is 40 - 46 parts, the average particle size of the aggregate is 70 - 75 μm, the weight fraction of the pore-forming agent is 25 - 28 parts, and the average particle size of the pore-forming agent is 40 - 50 μm; the weight fraction of the aggregate in the second group of green ceramic blanks is 45 - 50 parts, the average particle size of the aggregate is 40 - 60 μm, the weight fraction of the pore-forming agent is 20 - 25 parts, and the average particle size of the pore-forming agent is 40 - 50 μm; the weight fraction of the aggregate in the third group of green ceramic blanks is 40 - 48 parts, the average particle size of the aggregate is 15 - 30 μm, the weight fraction of the pore-forming agent is 25 - 30 parts, and the average particle size of the pore-forming agent is 35 - 40 μm; the weight fraction of the aggregate in the fourth group of green ceramic blanks is 35 - 45 parts, the average particle size of the aggregate is 10 - 20 μm, the weight fraction of the pore-forming agent is 25 - 30 parts, and the average particle size of the pore-forming agent is 35 - 40 μm.

22. The preparation method of the multi-layer porous ceramic matrix according to claim 16, wherein, When preparing the multi-layered porous ceramic substrate, the number of groups of the green ceramic blanks is selected to be 4 groups, the number of levels of the obtained multi-layered porous ceramic substrate is 4 levels, and the number of layers of the ceramic sheets is 8 layers. Among them, in the order of stacking from bottom to top, the pore diameter of the micropores in the first-level ceramic sheet is 40 - 50 μm, the pore diameter of the micropores in the second-level ceramic sheet is 30 - 40 μm, the pore diameter of the micropores in the third-level ceramic sheet is 20 - 30 μm, and the pore diameter of the micropores in the fourth-level ceramic sheet is 10 - 20 μm.

23. A preparation method of a multi-layer porous ceramic atomizing core, characterized in that, First, a multi-layered porous ceramic substrate is prepared according to the preparation method of the multi-layered porous ceramic substrate described in any one of claims 1-22. Then, a metal paste is prepared. One of the upper and lower surfaces of the multi-layered porous ceramic substrate is selected as the atomization surface, and the other surface is selected as the liquid guiding surface. The metal paste is printed at both ends of the atomization surface by screen printing and sintered to obtain an electrode layer. Finally, a metal heating layer is obtained on the atomization surface by a metal sputtering coating process or by a process of screen printing another metal paste and then sintering. The metal heating layer covers the electrode layer, thus obtaining a multi-layered porous ceramic atomization core.

24. The preparation method of the multi-layer porous ceramic atomization core according to claim 23, characterized in that, One of the upper and lower surfaces of the multi-layered porous ceramic substrate with a smaller pore diameter of micropores is selected as the atomization surface, and the other surface is selected as the liquid guiding surface. A metal heating layer is obtained on the atomization surface by a metal sputtering coating process or by a process of screen printing a metal paste and then sintering, thus obtaining a multi-layered porous ceramic atomization core.

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