WO2024124642A1 - Porous ceramic precursor and porous ceramic - Google Patents

Abstract

A porous ceramic precursor and a porous ceramic, relating to the technical field of ceramic precursors and ceramic production. The porous ceramic precursor comprises the following components in mass fraction: 15-40% of lanthanum zirconate, 2-5% of calcium feldspar, 2-5% of silica powder, 1-10% of hydroxypropyl starch, 1-3% of a thickening agent, 0.1-0.8% of a dispersing agent, and the balance of water. The lanthanum zirconate is obtained by ball milling and calcining a mixture of zirconium oxide and lanthanum oxide, and the molar ratio of zirconium oxide to lanthanum oxide is (1.8-2.2):1 in the mixture of zirconium oxide and lanthanum oxide. The porous ceramic precursor is obtained by combination of multiple effective components and a special freeze drying process. The precursor has a complex pyrochlore structure and can be used for preparing porous ceramic to obtain sheet-like porous ceramic having a pore structure. The porous ceramic is applied in the field of atomizing cores, increases the liquid storage amount of atomizing cores, increases the porosity of atomizing cores, namely the permeability of liquids to be atomized, and prolongs the service life of atomizing cores.

Description

A porous ceramic precursor and porous ceramic Technical Field

The present application relates to the technical field of ceramic precursors and ceramic production, and in particular to a porous ceramic precursor and porous ceramics.

Background technique

Existing atomizer cores are generally divided into two categories: cotton cores and ceramic cores. Ceramic atomizer cores generally include a ceramic matrix and a heating circuit. The heating circuit currently includes various forms such as resistance wire, etched mesh and thick film printed circuit. These forms of heating circuits are all solid heating elements. During atomization, the heating circuit generates heat and transfers it to the ceramic, and then a thermal gradient is formed with the solid heating element as the center. The ceramic body heats the vaporized atomized liquid to form an atomized aerosol.

The existing porous ceramic atomizer core has an atomization interface on the ceramic around the heating wire; the working heating circuit generates heat, and the heat is transferred to the surrounding ceramic, which then heats the atomized liquid. However, some atomized liquids have high viscosity, and the effect is not ideal after being atomized by the porous ceramic atomizer core, which is prone to problems such as poor taste, insufficient liquid supply, and low service life.

Therefore, for atomizing liquid with higher viscosity, it is necessary to study a porous ceramic for preparing atomizing core, which can increase the liquid storage capacity of the atomizing core, improve the permeability of the atomizing liquid, make the atomization process smoother, solve the problem of insufficient atomizing liquid supply, improve the taste, and extend the service life of the atomizing core.

Summary of the invention

In view of the shortcomings of the prior art, the present application provides a porous ceramic precursor, which is obtained by combining lanthanum zirconate and multiple effective ingredients such as modified starch, calcium feldspar, silica powder, thickener, dispersant, etc., and using a special freeze-drying process. The precursor has a complex pyrochlore structure. The above-mentioned porous ceramic precursor can be sintered to prepare porous ceramics to obtain porous ceramics with a flaky pore structure, which are applied to the field of atomizer cores to increase the liquid storage capacity of the atomizer core, improve the porosity of the atomizer core, that is, the permeability of the atomizing liquid, and extend the service life of the atomizer core.

At the same time, the preparation method of the porous ceramic precursor of the present application is simple and convenient to operate and is suitable for large-scale production.

Specifically, the present application discloses a porous ceramic precursor, which comprises the following components, by mass fraction: 15-40% lanthanum zirconate, 2-5% calcium feldspar, 2-5% silica powder, 1-10% hydroxypropyl starch, 1-3% thickener, 0.1-0.8% dispersant, and the remainder water; the lanthanum zirconate is obtained by ball milling and calcining a mixture of zirconium oxide and lanthanum oxide, and in the mixture of zirconium oxide and lanthanum oxide, the molar ratio of zirconium oxide to lanthanum oxide is 1.8-2.2:1.

Preferably, the average particle size of the lanthanum zirconate is 20-80 μm.

Preferably, the calcination process parameters are: temperature 1200-1400° C., time 2-4 h.

Preferably, the hydroxypropyl starch is obtained by etherification reaction of starch and propylene oxide, and the mass ratio of the starch to propylene oxide is 10-30:3-7.

Preferably, the average particle size of the silicon powder is 10-20 μm.

Preferably, the thickener is at least one of gelatin and carboxymethyl cellulose.

Preferably, the dispersant is at least one of ammonium polyacrylate and polyvinyl pyrrolidone.

The above-mentioned method for preparing the porous ceramic precursor comprises mixing lanthanum zirconate, calcium feldspar and hydroxypropyl starch evenly, adding water, a thickener and a dispersant, and then ball milling, defoaming and freeze drying to obtain a porous ceramic precursor; the freeze-drying process parameters are: -55°C to -40°C, directional freezing for 4-8h; -55°C to -40°C, vacuum degree 2-6Pa, freeze drying for 24-36h.

The present application also discloses a porous ceramic obtained by sintering the above-mentioned porous ceramic precursor. The sintering process parameters are: heating to 450-550°C at a heating rate of 10-20°C/h, keeping warm for 2-3h, and removing starch; then heating to 1150-1250°C at a heating rate of 180-240°C/h, and keeping warm for 2-4h.

The present application also discloses the application of the above-mentioned porous ceramic in a porous ceramic atomizer core.

Beneficial effects:

(1) The porous ceramic precursor of the present application is obtained by combining lanthanum zirconate and multiple effective ingredients such as modified starch, calcium feldspar, silica powder, thickener, dispersant, etc., while limiting the particle size of lanthanum zirconate and silica powder, and using a special freeze-drying process. The porous ceramic precursor has a complex pyrochlore structure; the porous ceramic precursor can be used for sintering to obtain a porous ceramic with a flaky pore structure, which is used to prepare an atomizer core. The atomizer core prepared by the porous ceramic has a large liquid storage capacity, high porosity, and long service life. It also has high strength, can resist bending, and is not easy to damage.

(2) The preparation method of the porous ceramic precursor of the present application includes the preparation process of lanthanum zirconate and the modification and etherification process of starch, combined with a freeze-drying process, so that the porous ceramic precursor has a complex pyrochlore structure, thereby improving the overall performance of the porous ceramic precursor; and the preparation method is simple and convenient to operate, energy-saving and environmentally friendly, low-cost, and suitable for large-scale production.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

FIG1 is a SEM image of a porous ceramic atomizer core prepared in Example 1 of the present application;

FIG2 is a SEM image of the porous ceramic atomizer core prepared in Comparative Example 1;

FIG. 3 is a SEM image of the porous ceramic atomizer core prepared in Comparative Example 2.

Detailed ways

The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and/or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or combinations thereof.

It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

It should be further understood that the term “and/or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

It should be further understood that the term "concentration" used in the present specification and the appended claims refers to mass concentration, and "%" refers to mass percentage, unless otherwise explained.

In the present specification, the part less than 100% by mass can be supplemented to 100% by water or solvent.

A porous ceramic precursor,

The composition comprises the following ingredients by mass fraction: 15-40% lanthanum zirconate, 2-5% calcium feldspar, 2-5% silica powder, 1-10% hydroxypropyl starch, 1-3% thickener, 0.1-0.8% dispersant, and the balance water;

Lanthanum zirconate is obtained by ball milling and calcining a mixture of zirconium oxide and lanthanum oxide, and has an average particle size of 20-80 μm; in the mixture of zirconium oxide and lanthanum oxide, the molar ratio of zirconium oxide to lanthanum oxide is 1.8-2.2:1, preferably 2:1; wherein the average particle size of zirconium oxide is 10-20 nm, and the average particle size of lanthanum oxide is 30-50 nm.

The preparation method of lanthanum zirconate is specifically as follows: zirconium oxide and lanthanum oxide are mixed, ball milled for 10-15 hours using a zirconium oxide ball milling jar and grinding balls, calcined the powder at 1200-1400° C. for 2-4 hours, and continued ball milling for 2-4 hours after cooling to obtain lanthanum zirconate.

Hydroxypropyl starch is obtained by etherification reaction of starch and propylene oxide, and the mass ratio of starch to propylene oxide is 10-30:3-7. The preparation method of hydroxypropyl starch is specifically as follows: sodium sulfate is mixed evenly with an appropriate amount of deionized water, and then starch and sodium hydroxide are added, nitrogen is introduced after stirring evenly, and propylene oxide is quickly added under the protection of nitrogen atmosphere to obtain a mixture, and the mixture is stirred evenly and then heated to a suitable temperature (30-50°C) for etherification reaction, and after the reaction is completed, the pH value is adjusted to 7.0 using a pH adjuster, and the mixture is dried to constant weight after standing for 5-10 hours to obtain hydroxypropyl starch.

Before the etherification reaction, based on the mass of the mixture as 100%, the mass fraction of deionized water is 70%, the mass fraction of sodium sulfate is 3-7%, the mass fraction of starch is 10-30%, the mass fraction of sodium hydroxide is 0.1-0.5%, and the mass fraction of propylene oxide is 3-7%; the starch is preferably corn starch, the etherification reaction time is 5-15h, and the pH regulator is preferably dilute hydrochloric acid.

The average particle size of silicon powder is 10-20 μm.

The thickener is at least one of gelatin and carboxymethyl cellulose.

The dispersant is at least one of ammonium polyacrylate and polyvinyl pyrrolidone.

The water is preferably deionized water.

Preparation method of porous ceramic precursor,

Lanthanum zirconate, calcium feldspar, and hydroxypropyl starch are mixed evenly, and water, a thickener, and a dispersant are added, followed by ball milling, degassing, and freeze drying to obtain a porous ceramic precursor. The freeze drying process parameters are: -55°C to -40°C, directional freezing for 4-8h; -55°C to -40°C, vacuum degree 2-6Pa, freeze drying for 24-36h.

Specifically, lanthanum zirconate is evenly mixed with calcium feldspar, silicon micropowder and hydroxypropyl starch, put into a ball mill, add an appropriate amount of deionized water, a small amount of thickener and dispersant, and ball mill for 4-6 hours to prepare a stable and uniform slurry; the prepared slurry is placed under vacuum conditions for 0.5-1 hour for vacuum degassing; the degassing slurry is poured into a mold, quickly placed in a cold trap pre-cooled to -55°C to -40°C, and directionally frozen for 4-8 hours; after the slurry is completely frozen, the film is removed, and then placed in a vacuum freeze dryer at a temperature of -55°C to -40°C and a vacuum degree of 2-6Pa for freeze drying for 24-36 hours to obtain a porous ceramic precursor.

A porous ceramic,

The porous ceramic precursor is sintered to obtain the above-mentioned porous ceramic precursor, and the sintering process parameters are: heating to 450-550°C at a heating rate of 10-20°C/h, keeping warm for 2-3h, and removing starch; then heating to 1150-1250°C at a heating rate of 180-240°C/h, and keeping warm for 2-4h.

Specifically, the porous ceramic precursor is placed in a muffle furnace, heated to 500°C at a rate of 10-20°C/h, kept warm for 2-3 hours, the starch is removed, and then heated to 1150-1250°C at a rate of 180-240°C/h, kept warm for 2-4 hours to obtain the porous ceramic.

The porous ceramic can be used to prepare an atomizer core. Specifically, the porous ceramic is cut into a required shape using a laser cutting technology, and an electrode is printed on the surface of the ceramic to obtain a porous ceramic atomizer core.

Embodiment 1:

A method for preparing a porous ceramic in this embodiment is as follows:

(1) Calculated by mass percentage, 5% sodium sulfate and 70% deionized water are weighed, and the sodium sulfate and deionized water are mixed evenly. Then, 19.8% starch and 0.2% sodium hydroxide are weighed, and added to the solution one by one and stirred evenly. Then, nitrogen is introduced into the container, 5% propylene oxide is weighed, and the solution is quickly added under the protection of nitrogen atmosphere. After stirring evenly, the temperature is raised to 40° C. for etherification reaction. After 8 hours, the reaction is completed, and the pH is adjusted to 7.0 with dilute hydrochloric acid. After standing for 5 hours, it is dried to constant weight to obtain hydroxypropyl starch.

(2) Weigh zirconium oxide and lanthanum oxide respectively at a molar ratio of 2:1, mix the zirconium oxide and lanthanum oxide, add them into a ball mill, and ball mill for 10 hours. The powder is calcined at 1250° C. for 2 hours, and after cooling, the ball mill is continued for 3 hours to obtain a powder with an average particle size of 20-80 μm, that is, lanthanum zirconate powder.

(3) Calculated by mass percentage, 30% of lanthanum zirconate, 4% of calcium feldspar, 3% of silica powder, 8% of hydroxypropyl starch, 53.8% of deionized water, 1% of gelatin, and 0.2% of ammonium polyacrylate were weighed. Lanthanum zirconate, calcium feldspar, silica powder, and hydroxypropyl starch were mixed evenly, put into a ball mill, and then deionized water, gelatin, and ammonium polyacrylate were added, and ball milled for 4 hours to prepare a stable and uniform slurry.

(4) The slurry prepared in (3) is placed under vacuum conditions for 1 hour to perform vacuum degassing. The degassing slurry is poured into a mold and quickly placed in a cold trap pre-cooled to -45°C for directional freezing for 5 hours. After the slurry is completely frozen, the mold is removed and quickly placed in a vacuum freeze dryer at a temperature of -45°C and a vacuum degree of 2Pa for freeze drying for 24 hours to obtain a porous ceramic precursor.

(5) The porous ceramic precursor prepared in (4) is placed in a muffle furnace, and the temperature is increased to 500°C at a rate of 20°C/h, and kept at this temperature for 2 hours to remove the starch. The temperature is then increased to 1180°C at a rate of 180°C/h, and kept at this temperature for 2 hours to obtain a porous ceramic.

(6) The porous ceramic is cut into the required shape using laser cutting technology, and electrodes are printed on the ceramic surface to obtain a porous ceramic atomization core, which is then loaded with the corresponding aerosol structure to test the suction effect of the atomized liquid.

Embodiment 2:

A method for preparing a porous ceramic in this embodiment is as follows:

(1) Calculated by mass percentage, 4% sodium sulfate and 70% deionized water are weighed, and the sodium sulfate and deionized water are mixed evenly. Then, 21.5% starch and 0.5% sodium hydroxide are weighed, and added to the solution one by one and stirred evenly. Then, nitrogen is introduced into the container, 4% propylene oxide is weighed, and the solution is quickly added under the protection of nitrogen atmosphere. After stirring evenly, the temperature is raised to 40° C. for etherification reaction. After 10 hours, the reaction is completed, and the pH is adjusted to 7.0 with dilute hydrochloric acid. After standing for 5 hours, it is dried to constant weight to obtain hydroxypropyl starch.

(2) Weigh zirconium oxide and lanthanum oxide respectively at a molar ratio of 2:1, mix the zirconium oxide and lanthanum oxide, add them into a ball mill, and ball mill for 10 hours. The powder is calcined at 1250° C. for 2 hours, and after cooling, the ball mill is continued for 3 hours to obtain a powder with an average particle size of 20-80 μm, that is, lanthanum zirconate powder.

(3) Calculated by mass percentage, weigh 30% of lanthanum zirconate, 2% of calcium feldspar, 5% of silica powder, 5% of hydroxypropyl starch, 56.8% of deionized water, 1% of gelatin, and 0.2% of ammonium polyacrylate. Lanthanum zirconate, calcium feldspar, silica powder, and hydroxypropyl starch are mixed evenly, put into a ball mill, and then deionized water, gelatin, and ammonium polyacrylate are added, and ball milling is performed for 4 hours to prepare a stable and uniform slurry.

(4) The slurry prepared in (3) is placed under vacuum conditions for 1 hour to perform vacuum degassing. The degassing slurry is poured into a mold and quickly placed in a cold trap pre-cooled to -50°C for directional freezing for 5 hours. After the slurry is completely frozen, the mold is removed and quickly placed in a vacuum freeze dryer at a temperature of -50°C and a vacuum degree of 2Pa for freeze drying for 30 hours to obtain a porous ceramic precursor.

(5) The porous ceramic precursor prepared in (4) is placed in a muffle furnace, and the temperature is increased to 500°C at a rate of 20°C/h, and kept at this temperature for 2 hours to remove the starch. The temperature is then increased to 1200°C at a rate of 180°C/h, and kept at this temperature for 3 hours to obtain a porous ceramic.

(6) The porous ceramic is cut into the required shape using laser cutting technology, and electrodes are printed on the ceramic surface to obtain a porous ceramic atomization core, which is then loaded with the corresponding aerosol structure to test the suction effect of the atomized liquid.

Embodiment 3:

A method for preparing a porous ceramic in this embodiment is as follows:

(1) Calculated by mass percentage, 3% sodium sulfate and 70% deionized water are weighed, and the sodium sulfate and deionized water are mixed evenly, then 21.7% starch and 0.3% sodium hydroxide are weighed, and added to the solution one by one and stirred evenly, and then nitrogen is introduced into the container, 5% propylene oxide is weighed, and the solution is quickly added under the protection of nitrogen atmosphere, and the temperature is raised to 40° C. after stirring evenly to carry out etherification reaction. The reaction is completed after 10 hours, and the pH is adjusted to 7.0 with dilute hydrochloric acid, and dried to constant weight after standing for 6 hours to obtain hydroxypropyl starch.

(2) Weigh zirconium oxide and lanthanum oxide respectively at a molar ratio of 2:1, mix the zirconium oxide and lanthanum oxide, add them into a ball mill, and ball mill for 10 hours. The powder is calcined at 1300° C. for 3 hours, and after cooling, the ball mill is continued for 3 hours to obtain a powder with an average particle size of 20-80 μm, that is, lanthanum zirconate powder.

(3) Calculated by mass percentage, weigh 23% of lanthanum zirconate, 2% of calcium feldspar, 3% of silica powder, 7% of hydroxypropyl starch, 63.8% of deionized water, 1% of gelatin, and 0.2% of polyvinyl pyrrolidone. Mix lanthanum zirconate, calcium feldspar, silica powder, and hydroxypropyl starch evenly, put them into a ball mill, then add deionized water, gelatin, and ammonium polyacrylate, and ball mill for 4 hours to prepare a stable and uniform slurry.

(4) The slurry prepared in (3) was placed under vacuum conditions for 1 hour to perform vacuum degassing. The degassing slurry was poured into a mold and quickly placed in a cold trap pre-cooled to -55°C for directional freezing for 5 hours. After the slurry was completely frozen, the mold was removed and quickly placed in a vacuum freeze dryer at a temperature of -55°C and a vacuum degree of 5Pa for freeze drying for 36 hours to obtain a porous ceramic precursor.

(5) The porous ceramic precursor prepared in (4) is placed in a muffle furnace, and the temperature is increased to 500°C at a rate of 20°C/h, and kept at this temperature for 2 hours to remove the starch. The temperature is then increased to 1150°C at a rate of 200°C/h, and kept at this temperature for 2 hours to obtain a porous ceramic.

(6) The porous ceramic is cut into the required shape using laser cutting technology, and electrodes are printed on the ceramic surface to obtain a porous ceramic atomization core, which is then loaded with the corresponding aerosol structure to test the suction effect of the atomized liquid.

Embodiment 4:

A method for preparing a porous ceramic in this embodiment is as follows:

(1) Calculated by mass percentage, 3% sodium sulfate and 72% deionized water are weighed, and the sodium sulfate and deionized water are mixed evenly. Then, 21.7% starch and 0.3% sodium hydroxide are weighed, and they are added to the solution one by one and stirred evenly. Then, nitrogen is introduced into the container, 3% propylene oxide is weighed, and the solution is quickly added under the protection of nitrogen atmosphere. After stirring evenly, the temperature is raised to 40° C. for etherification reaction. After 8 hours, the reaction is completed, and the pH is adjusted to 7.0 with dilute hydrochloric acid. After standing for 5 hours, it is dried to constant weight to obtain hydroxypropyl starch.

(2) Weigh zirconium oxide and lanthanum oxide respectively at a molar ratio of zirconium oxide to lanthanum oxide of 1.8:1, mix the zirconium oxide and lanthanum oxide, add them into a ball mill, and ball mill them for 10 hours. The powder is calcined at 1200° C. for 4 hours, and after cooling, the ball milling is continued for 3 hours to obtain a powder with an average particle size of 20-80 μm, that is, lanthanum zirconate powder.

(3) Calculated by mass percentage, weigh 15% of lanthanum zirconate, 5% of calcium feldspar, 5% of silica powder, 10% of hydroxypropyl starch, 61.2% of deionized water, 3% of gelatin, and 0.8% of ammonium polyacrylate. Lanthanum zirconate, calcium feldspar, silica powder, and hydroxypropyl starch are mixed evenly, put into a ball mill, and then deionized water, gelatin, and ammonium polyacrylate are added, and ball milled for 4 hours to prepare a stable and uniform slurry.

(4) The slurry prepared in (3) is placed under vacuum conditions for 1 hour to perform vacuum degassing. The degassing slurry is poured into a mold and quickly placed in a cold trap pre-cooled to -45°C for directional freezing for 5 hours. After the slurry is completely frozen, the mold is removed and quickly placed in a vacuum freeze dryer at a temperature of -45°C and a vacuum degree of 2Pa for freeze drying for 24 hours to obtain a porous ceramic precursor.

(5) The porous ceramic precursor prepared in (4) is placed in a muffle furnace, and the temperature is increased to 450°C at a rate of 10°C/h, and kept at this temperature for 3 hours to remove the starch. The temperature is then increased to 1150°C at a rate of 240°C/h, and kept at this temperature for 4 hours to obtain a porous ceramic.

(6) The porous ceramic is cut into the required shape using laser cutting technology, and electrodes are printed on the ceramic surface to obtain a porous ceramic atomization core, which is then loaded with the corresponding aerosol structure to test the suction effect of the atomized liquid.

Embodiment 5:

A method for preparing a porous ceramic in this embodiment is as follows:

(1) Calculated by mass percentage, 7% sodium sulfate and 70% deionized water are weighed, and the sodium sulfate and deionized water are mixed evenly. Then, 15.9% starch and 0.1% sodium hydroxide are weighed, and added to the solution one by one and stirred evenly. Then, nitrogen is introduced into the container, 7% propylene oxide is weighed, and the solution is quickly added under the protection of nitrogen atmosphere. After stirring evenly, the temperature is raised to 40° C. for etherification reaction. After 8 hours, the reaction is completed, and the pH is adjusted to 7.0 with dilute hydrochloric acid. After standing for 5 hours, it is dried to constant weight to obtain hydroxypropyl starch.

(2) Weigh zirconium oxide and lanthanum oxide respectively at a molar ratio of zirconium oxide to lanthanum oxide of 2.2:1, mix the zirconium oxide and lanthanum oxide, add them into a ball mill, and ball mill them for 10 hours. The powder is calcined at 1400° C. for 2 hours, and after cooling, the ball milling is continued for 3 hours to obtain a powder with an average particle size of 20-80 μm, that is, lanthanum zirconate powder.

(3) Calculated by mass percentage, weigh 40% of lanthanum zirconate, 2% of calcium feldspar, 2% of silica powder, 1% of hydroxypropyl starch, 53.9% of deionized water, 1% of gelatin, and 0.1% of ammonium polyacrylate. Mix lanthanum zirconate, calcium feldspar, silica powder, and hydroxypropyl starch evenly, put them into a ball mill, then add deionized water, gelatin, and ammonium polyacrylate, and ball mill for 4 hours to prepare a stable and uniform slurry.

(4) The slurry prepared in (3) is placed under vacuum conditions for 1 hour to perform vacuum degassing. The degassing slurry is poured into a mold and quickly placed in a cold trap pre-cooled to -45°C for directional freezing for 5 hours. After the slurry is completely frozen, the mold is removed and quickly placed in a vacuum freeze dryer at a temperature of -45°C and a vacuum degree of 2Pa for freeze drying for 24 hours to obtain a porous ceramic precursor.

(5) The porous ceramic precursor prepared in (4) is placed in a muffle furnace, and the temperature is increased to 550°C at a rate of 20°C/h, and kept at this temperature for 2 hours to remove the starch. The temperature is then increased to 1250°C at a rate of 180°C/h, and kept at this temperature for 2 hours to obtain a porous ceramic.

(6) The porous ceramic is cut into the required shape using laser cutting technology, and electrodes are printed on the ceramic surface to obtain a porous ceramic atomization core, which is then loaded with the corresponding aerosol structure to test the suction effect of the atomized liquid.

At the same time, a comparative example is set according to Example 1, and the differences between the comparative example and Example 1 are shown in Table 1 below.

Table 1 The difference between the comparative example and embodiment 1

The porous ceramics prepared in the embodiments and comparative examples were subjected to performance tests. The porosity of the ceramics was tested using a porosity tester, the pore size of the ceramics was tested using a pore size analyzer, and the bending strength of the ceramics was tested using an electronic universal testing machine. The results are shown in Table 2-3.

Table 2 Performance of porous ceramics prepared in Example

The	Porosity(%)	Average pore size (μm)	Flexural strength(MPa)
Example 1	75	34	3.12
Example 2	79	32	2.95
Example 3	82	34	2.16
Example 4	80	37	2.43
Example 5	76	30	3.08

Table 3 Performance of porous ceramics prepared in comparative example

From the comparison of Table 2-3, it can be seen that the porosity of the porous ceramics prepared in Examples 1-5 is between 75% and 85%, the average pore size is between 30μm and 40μm, and the strength is between 2MPa and 3.5MPa. In Comparative Example 1, zirconium oxide is used alone, which makes the diameter of the ceramic pores smaller and the strength is lower than the line; in Comparative Example 2, lanthanum oxide is used alone, and the ceramic pore size is significantly smaller, and the pore distribution is slightly messy; in Comparative Example 3, the calcination temperature of lanthanum zirconate is reduced, and lanthanum zirconate can basically not be generated. Zirconium oxide and lanthanum oxide are simply piled together, resulting in low ceramic strength.

In Comparative Example 4, the calcination temperature of lanthanum zirconate is increased, the grains of lanthanum zirconate are disorderly stacked, and the grains are larger, which slightly increases the pore size of the ceramic; in Comparative Example 5, the particle size of lanthanum zirconate after ball milling is greater than 80 μm, the pores between the particles become larger, and it is not easy to sinter together, which increases the pore size of the ceramic and reduces the strength.

Hydroxypropyl starch acts as a binder and a pore-forming agent. In the preparation process of hydroxypropyl starch in Comparative Example 6, the ratio of starch to propylene oxide was changed, and only a small part of the starch was modified, which reduced the stability of the ceramic slurry and reduced the strength of the ceramic after sintering. In the preparation process of hydroxypropyl starch in Comparative Example 7, excessive propylene oxide was added, which led to starch gelatinization and the experiment could not be carried out. In Comparative Example 8, ordinary starch was used instead, resulting in results similar to those of Comparative Example 6.

In Comparative Example 9, the temperature during the freeze-drying process was increased, and the porosity of the ceramic remained basically unchanged, but the pore size of the ceramic was significantly increased and the strength was reduced; in Comparative Example 10, the directional freezing process was removed, so that the pores in the ceramic were randomly distributed, which had little effect on the performance of the ceramic; in Comparative Example 11, the starch was removed at a higher heating rate, causing bubbles on the ceramic surface and stratification in the middle of the ceramic; in Comparative Example 12, after removing the starch, the ceramic was sintered at a higher heating rate, causing the ceramic to warp and deform, and the strength was reduced, making it unusable.

The porous ceramic atomizing cores prepared in the examples and comparative examples were subjected to suction tests of different atomizing liquids, and the results are shown in Tables 4 to 7. The atomizing liquids were VOOPOO's vp539, grc14525, and xrq83461.

Among them, the SEM image of the porous ceramic atomizer core prepared in Example 1 is shown in Figure 1; the SEM image of the porous ceramic atomizer core prepared in Comparative Example 1 is shown in Figure 2; the SEM image of the porous ceramic atomizer core prepared in Comparative Example 2 is shown in Figure 3.

The atomizer liquid life test is as follows: use the RTE-CY02A suction machine, set the conditions to draw for 3s and stop for 8s, and cycle the suction. Use 2ml or 5ml of atomizer liquid to add to the porous ceramic atomizer core for testing, where 2ml of atomizer liquid can draw 300-400 puffs, and 5ml of atomizer liquid can draw 800-1000 puffs. During the test, if there is no phenomenon such as core sticking, film breaking, abnormal resistance, and no taste, the test is passed and marked as ‘OK’, otherwise it is marked as ‘NG’.

Table 4 2 ml atomization liquid life test results of the atomization core prepared in Example

Table 5 5 ml atomization liquid life test results of the atomization core prepared in Example

Table 6 Comparative Example of the 2 ml atomization liquid life test results of the atomization core prepared

Table 7 Comparative Example of 5 ml atomization liquid life test results of the atomization core prepared

From the comparison of Tables 4-7, it can be seen that the atomizer cores prepared in Examples 1-5 can pass the life tests of three kinds of 2ml and 5ml atomizing liquids. However, the atomizer core prepared in Comparative Example 1 passed the life tests of two kinds of 2ml atomizing liquids, but failed to pass the life test of 5ml atomizing liquid. The pore size of the ceramic was reduced, and the atomizing liquid could not be atomized well through the ceramic, resulting in dry burning; the atomizer core prepared in Comparative Example 2 could only pass the life test of one kind of 2ml atomizing liquid, but could not pass the life test of 5ml atomizing liquid. The pore size of the ceramic was significantly reduced, and the pore distribution was slightly messy. The atomizing liquid could not be atomized well through the ceramic, resulting in dry burning; the atomizer core prepared in Comparative Example 3 passed the life test of three kinds of 2ml atomizing liquids, but could not pass the life test of 5ml atomizing liquid. Zirconium oxide and lanthanum oxide were simply accumulated in the ceramic, resulting in an insufficient atomization process, serious carbon accumulation on the surface of the ceramic, and the test failed.

The atomizer core prepared in Comparative Example 4 can only pass the life test of 2ml of atomizing liquid, but cannot pass the life test of 5ml of atomizing liquid. The lanthanum zirconate grains in the ceramic are disorderly stacked, resulting in an increase in closed pores, a decrease in the oil storage capacity of the ceramic, and easy dry burning. The strength of the ceramic in Comparative Example 5 is too low and cannot be installed for testing.

The atomizer core prepared in Comparative Example 6 can only pass the life test of 2 ml of atomizing liquid, but cannot pass the life test of 5 ml of atomizing liquid. The stability of the ceramic slurry is poor, and the same sintering environment results in a low degree of ceramic sintering. No ceramic was prepared in Comparative Example 7 and no test was performed. The results of Comparative Example 8 are similar to those of Comparative Example 6.

The strength of the ceramic in Comparative Example 9 is too low and cannot be installed for testing; the atomizer core prepared in Comparative Example 10 passed the life test of two 2ml atomization liquids, but failed the life test of 5ml atomization liquid. The pores in the ceramic are irregularly distributed, which increases the path of the atomization liquid through the ceramic, and the liquid supply speed is lower than the atomization speed. The ceramic in Comparative Example 11 has bubbling and stratification and cannot be installed for testing; the ceramic in Comparative Example 12 warps and deforms and cannot be installed for testing.

In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

The above descriptions are merely embodiments of the present application and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims (20)

1. A porous ceramic precursor comprises the following components by mass fraction: 15-40% lanthanum zirconate, 2-5% calcium feldspar, 2-5% silica powder, 1-10% hydroxypropyl starch, 1-3% thickener, 0.1-0.8% dispersant, and the balance is water; the lanthanum zirconate is obtained by ball milling and calcining a mixture of zirconium oxide and lanthanum oxide, and in the mixture of zirconium oxide and lanthanum oxide, the molar ratio of zirconium oxide to lanthanum oxide is 1.8-2.2:1.
2. The porous ceramic precursor according to claim 1, wherein the average particle size of the lanthanum zirconate is 20-80 μm.
3. The porous ceramic precursor according to claim 1, wherein the calcination process parameters are: temperature 1200-1400°C, time 2-4h.
4. The porous ceramic precursor as described in claim 1, wherein the hydroxypropyl starch is obtained by etherification reaction of starch and propylene oxide, and the mass ratio of starch to propylene oxide is 10-30:3-7.
5. The porous ceramic precursor according to claim 1, wherein the average particle size of the silicon powder is 10-20 μm.
6. The porous ceramic precursor according to claim 1, wherein the thickener is at least one of gelatin and carboxymethyl cellulose.
7. The porous ceramic precursor according to claim 1, wherein the dispersant is at least one of ammonium polyacrylate and polyvinyl pyrrolidone.
8. A method for preparing a porous ceramic precursor, wherein:

   The porous ceramic precursor comprises the following components by mass fraction: 15-40% lanthanum zirconate, 2-5% calcium feldspar, 2-5% silica powder, 1-10% hydroxypropyl starch, 1-3% thickener, 0.1-0.8% dispersant, and the balance water; the lanthanum zirconate is obtained by ball milling and calcining a mixture of zirconium oxide and lanthanum oxide, and in the mixture of zirconium oxide and lanthanum oxide, the molar ratio of zirconium oxide to lanthanum oxide is 1.8-2.2:1;

   The method for preparing the porous ceramic precursor comprises the following steps:

   Lanthanum zirconate, calcium feldspar and hydroxypropyl starch are mixed evenly, and water, a thickener and a dispersant are added, followed by ball milling, defoaming and freeze drying to obtain a porous ceramic precursor; the freeze drying process parameters are: -55°C to -40°C, directional freezing for 4-8h; -55°C to -40°C, vacuum degree 2-6Pa, freeze drying for 24-36h.
9. The method for preparing a porous ceramic precursor according to claim 8, wherein the average particle size of the lanthanum zirconate is 20-80 μm.
10. The method for preparing a porous ceramic precursor as claimed in claim 8, wherein the calcination process parameters are: temperature 1200-1400°C, time 2-4h.
11. The method for preparing a porous ceramic precursor as described in claim 8, wherein the hydroxypropyl starch is obtained by etherification reaction of starch and propylene oxide, and the mass ratio of starch to propylene oxide is 10-30:3-7.
12. The method for preparing a porous ceramic precursor according to claim 8, wherein the average particle size of the silicon powder is 10-20 μm.
13. The method for preparing a porous ceramic precursor as claimed in claim 8, wherein the thickener is at least one of gelatin and carboxymethyl cellulose.
14. The method for preparing a porous ceramic precursor according to claim 8, wherein the dispersant is at least one of ammonium polyacrylate and polyvinyl pyrrolidone.
15. A porous ceramic, wherein the porous ceramic precursor is sintered to obtain the porous ceramic precursor, wherein the porous ceramic precursor comprises the following components by mass fraction: 15-40% lanthanum zirconate, 2-5% calcium feldspar, 2-5% silica powder, 1-10% hydroxypropyl starch, 1-3% thickener, 0.1-0.8% dispersant, and the balance water; the lanthanum zirconate is obtained by ball milling and calcining a mixture of zirconium oxide and lanthanum oxide, wherein the molar ratio of zirconium oxide to lanthanum oxide in the mixture of zirconium oxide and lanthanum oxide is 1.8-2.2:1;

    The sintering process parameters are: heating to 450-550°C at a heating rate of 10-20°C/h, keeping warm for 2-3h to remove starch; then heating to 1150-1250°C at a heating rate of 180-240°C/h, keeping warm for 2-4h.
16. The porous ceramic according to claim 15, wherein the average particle size of the lanthanum zirconate is 20-80 μm.
17. The porous ceramic according to claim 15, wherein the calcination process parameters are: temperature 1200-1400°C, time 2-4h.
18. The porous ceramic as described in claim 15, wherein the hydroxypropyl starch is obtained by etherification reaction of starch and propylene oxide, and the mass ratio of starch to propylene oxide is 10-30:3-7.
19. The porous ceramic according to claim 15, wherein the average particle size of the silicon powder is 10-20 μm.
20. Use of the porous ceramic as claimed in claim 9 in a porous ceramic atomizer core.

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